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Life-threatening thrombotic events and neurological symptoms are prevalent in COVID-19 and are persistent in patients with long COVID experiencing post-acute sequelae of SARS-CoV-2 infection1-4. Despite the clinical evidence1,5-7, the underlying mechanisms of coagulopathy in COVID-19 and its consequences in inflammation and neuropathology remain poorly understood and treatment options are insufficient. Fibrinogen, the central structural component of blood clots, is abundantly deposited in the lungs and brains of patients with COVID-19, correlates with disease severity and is a predictive biomarker for post-COVID-19 cognitive deficits1,5,8-10. Here we show that fibrin binds to the SARS-CoV-2 spike protein, forming proinflammatory blood clots that drive systemic thromboinflammation and neuropathology in COVID-19. Fibrin, acting through its inflammatory domain, is required for oxidative stress and macrophage activation in the lungs, whereas it suppresses natural killer cells, after SARS-CoV-2 infection. Fibrin promotes neuroinflammation and neuronal loss after infection, as well as innate immune activation in the brain and lungs independently of active infection. A monoclonal antibody targeting the inflammatory fibrin domain provides protection from microglial activation and neuronal injury, as well as from thromboinflammation in the lung after infection. Thus, fibrin drives inflammation and neuropathology in SARS-CoV-2 infection, and fibrin-targeting immunotherapy may represent a therapeutic intervention for patients with acute COVID-19 and long COVID.

The functional state of cells is dependent on their microenvironmental context. Prior studies described how polarizing cytokines alter macrophage transcriptomes and epigenomes. Here, we characterized the functional responses of 6 differentially polarized macrophage populations by measuring the dynamics of transcription factor nuclear factor κB (NF-κB) in response to 8 stimuli. The resulting dataset of single-cell NF-κB trajectories was analyzed by three approaches: (1) machine learning on time-series data revealed losses of stimulus distinguishability with polarization, reflecting canalized effector functions. (2) Informative trajectory features driving stimulus distinguishability (signaling codons) were identified and used for mapping a cell state landscape that could then locate macrophages conditioned by an unrelated condition. (3) Kinetic parameters, inferred using a mechanistic NF-κB network model, provided an alternative mapping of cell states and correctly predicted biochemical findings. Together, this work demonstrates that a single analytes dynamic trajectories may distinguish the functional states of single cells and molecular network states underlying them. A record of this papers transparent peer review process is included in the supplemental information.

Mutations in GBA (glucosylceramidase beta), which encodes the lysosomal enzyme glucocerebrosidase (GCase), are the strongest genetic risk factor for the neurodegenerative disorders Parkinson's disease (PD) and Lewy body dementia. Recent work has suggested that neuroinflammation may be an important factor in the risk conferred by GBA mutations. We therefore systematically tested the contributions of immune-related genes to neuropathology in a Drosophila model of GCase deficiency. We identified target immune factors via RNA-Seq and proteomics on heads from GCase-deficient flies, which revealed both increased abundance of humoral factors and increased macrophage activation. We then manipulated the identified immune factors and measured their effect on head protein aggregates, a hallmark of neurodegenerative disease. Genetic ablation of humoral (secreted) immune factors did not suppress the development of protein aggregation. By contrast, re-expressing Gba1b in activated macrophages suppressed head protein aggregation in Gba1b mutants and rescued their lifespan and behavioral deficits. Moreover, reducing the GCase substrate glucosylceramide in activated macrophages also ameliorated Gba1b mutant phenotypes. Taken together, our findings show that glucosylceramide accumulation due to GCase deficiency leads to macrophage activation, which in turn promotes the development of neuropathology. Author summary: Mutations in the gene GBA are the largest risk factor for developing Parkinson's disease and Lewy body dementia, diseases in which important brain cells die. We know that the immune system can be involved in these diseases, and that GBA mutations cause immune changes. We did experiments to learn how the immune system changes could make brain cells more likely to die. Using a fruit fly that was missing the fly version of GBA, we found out that inappropriately activated immune cells, but not secreted immune proteins, were important in the development of brain problems. We also learned that the abnormal activation was triggered by the lack of GBA function in the immune cells, not by signals from the brain or other parts of the body. We would like to find out next whether the immune cells get inside the brain or cause harm from a distance. What we learned matters because it could help us prevent or cure brain diseases associated with GBA mutations. Treating the abnormal activation of immune cells in people with these mutations might help prevent damage to the brain. [ABSTRACT FROM AUTHOR]

Intratumoral TLR9 agonists and anti-PD-1 produce clinical responses and broad immune activation. We conducted a single-arm study of neoadjuvant TLR9 agonist vidutolimod combined with anti-PD-1 nivolumab in high-risk resectable melanoma. In 31 evaluable patients, 55% major pathologic response (MPR) was observed, meeting primary endpoint. MPR was associated with necrosis, and melanophagocytosis with increased CD8+ tumor-infiltrating lymphocytes and plasmacytoid dendritic cells (pDCs) in the tumor microenvironment, and increased frequencies of Ki67+CD8+ T cells peripherally. MPRs had an enriched pre-treatment gene signature of myeloid cells, and response to therapy was associated with gene signatures of immune cells, pDCs, phagocytosis, and macrophage activation. MPRs gut microbiota were enriched for Gram-negative bacteria belonging to the Bacteroidaceae and Enterobacteriaceae families and the small subgroup of Gram-negative Firmicutes. Our findings support that combined vidutolimod and nivolumab stimulates a broad anti-tumor immune response and is associated with distinct baseline myeloid gene signature and gut microbiota. ClinicalTrials.gov identifier: NCT03618641. [Display omitted] • Neoadjuvant intratumoral vidu/nivo produces pathologic responses in stage III melanoma • Response is linked to myeloid cells, pDCs, and CD8+ T cells within tumor • Responder gut microbiota signatures vidu/nivo are distinct from those in anti-PD-1 Neoadjuvant immunotherapy improves relapse-free survival in stage III melanoma. The novel combination of intratumoral vidu/nivo produces 55% major pathologic response (MPR) with an acceptable safety profile. MPR was associated with intratumoral myeloid cells, pDCs, and CD8+ TIL. Gut microbiota signatures in vidu/nivo MPR are distinct from those in anti-PD-1 responders. [ABSTRACT FROM AUTHOR]

Excessive macrophage activation and production of pro-inflammatory cytokines are hallmarks of the Cytokine Storm Syndrome (CSS), a lethal condition triggered by sepsis, autoimmune disorders, and cancer immunotherapies. While depletion of macrophages at disease onset protects from lethality in an infection-induced CSS murine model, patients are rarely diagnosed early, hence the need to characterize macrophage populations during CSS progression and assess the therapeutic implications of macrophage targeting after disease onset. In this study, we identified MHCII+F4/80+Tim4- macrophages as the primary contributors to the pro-inflammatory environment in CSS, while CD206+F4/80+Tim4+ macrophages, with an anti-inflammatory profile, become outnumbered. Additionally, we observed an expansion of Tim4- macrophages coinciding with increased hematopoietic stem progenitor cells and reduction of committed myeloid progenitors in bone marrow and spleen. Critically, macrophage targeting with clodronate liposomes at disease onset prolonged survival, while their targeting in mice with established CSS exacerbated disease severity, leading to a more dramatic loss of Tim4+ macrophages and an imbalance in pro- versus anti-inflammatory Tim4− macrophage ratio. Our findings highlight the significance of timing in macrophage-targeted interventions for effective management of CSS and suggest potential therapeutic strategies for diseases characterized by uncontrolled inflammation, such as sepsis. [ABSTRACT FROM AUTHOR]

Exosomes, membrane-bound extracellular vesicles, ranging from approximately 30–200 nm in diameter, are released by almost all cell types and play critical roles in intercellular communication. In response to the prevailing stress, the exosome-bound protein signatures vary in abundance and composition. To identify the bronchoalveolar lavage fluid (BALF) exosome-bound proteins associated with mucoinflammatory lung disease and to gain insights into their functional implications, we compared BALF exosomes-derived proteins from adult Scnn1b transgenic (Scnn1b -Tg+) and wild type (WT) mice. A total of 3,144 and 3,119 proteins were identified in BALF exosomes from Scnn1b -Tg+ and WT mice, respectively. Using cutoff criteria (Log2 fold-change > 1 and adjusted p -value < 0.05), the comparison of identified proteins revealed 127 and 30 proteins that were significantly upregulated and downregulated, respectively, in Scnn1b -Tg+ versus WT mice. In addition, 52 and 27 proteins were exclusively enriched in Scnn1b -Tg+ and WT mice, respectively. The identified exosome-bound proteins from the homeostatic airspaces of WT mice were mostly relevant to the normal physiological processes. The protein signatures enriched in the BALF exosomes of Scnn1b -Tg+ mice were relevant to macrophage activation and mucoinflammatory processes. Ingenuity pathway analyses revealed that the enriched proteins in Scnn1b -Tg+ mice contributed to the inflammatory responses and antimicrobial defense pathways. Selective proteins including, RETNLA/FIZZ1, LGALS3/Galectin-3, S100A8/MRP8, and CHIL3/YM1 were immunolocalized to specific cell types. The comparative analysis between enriched BALF exosome proteins and previously identified differentially upregulated genes in Scnn1b -Tg+ versus WT mice suggested that the compartment-/cell-specific upregulation in gene expression dictates the enrichment of their respective proteins in the lung airspaces. Taken together, this study demonstrates that the BALF exosome-bound protein signatures reflect disease-relevant disturbances. Our findings suggest that the exosomes carry disease-relevant protein signatures that can be used as a diagnostic as well as predictive biomarkers for mucoinflammatory lung disease. [ABSTRACT FROM AUTHOR]

Activation of the Toll-like receptor 4 (TLR4) by bacterial endotoxins in macrophages plays a crucial role in the pathogenesis of sepsis. However, the mechanism underlying TLR4 activation in macrophages is still not fully understood. Here, we reveal that upon lipopolysaccharide (LPS) stimulation, lysine acetyltransferase CBP is recruited to the TLR4 signalosome complex leading to increased acetylation of the TIR domains of the TLR4 signalosome. Acetylation of the TLR4 signalosome TIR domains significantly enhances signaling activation via NF-κB rather than IRF3 pathways. Induction of NF-κB signaling is responsible for gene expression changes leading to M1 macrophage polarization. In sepsis patients, significantly elevated TLR4-TIR acetylation is observed in CD16+ monocytes combined with elevated expression of M1 macrophage markers. Pharmacological inhibition of HDAC1, which deacetylates the TIR domains, or CBP play opposite roles in sepsis. Our findings highlight the important role of TLR4-TIR domain acetylation in the regulation of the immune responses in sepsis, and we propose this reversible acetylation of TLR4 signalosomes as a potential therapeutic target for M1 macrophages during the progression of sepsis. Synopsis: Activation of macrophage TLR4 by bacterial endotoxins is important for the progression of sepsis, but the underlying mechanisms remain unknown. This study demonstrates that lipopolysaccharide (LPS) stimulation induces acetylation of the TLR4 signalosome TIR domains, which plays an important role in M1 macrophage polarization. LPS induces CBP-mediated acetylation of the TIR domains of TLR4, Mal, and MyD88 in the TLR4 signalosome complex. TIR domain acetylation in the TLR4 complex enhances NF-κB activation, leading to pro-inflammatory gene expression in M1 macrophages during sepsis. Inhibition of the primary TIR domain acetyltransferase CBP or deacetylase HDAC1 has opposite effects on the progression of sepsis. LPS-induced acetylation of the TLR4 complex TIR domains induces NF-κB signaling, leading to macrophage polarization. [ABSTRACT FROM AUTHOR]

Macrophages measure the "eat-me" signal immunoglobulin G (IgG) to identify targets for phagocytosis. We tested whether prior encounters with IgG influence macrophage appetite. IgG is recognized by the Fc receptor. To temporally control Fc receptor activation, we engineered an Fc receptor that is activated by the light-induced oligomerization of Cry2, triggering phagocytosis. Using this tool, we demonstrate that subthreshold Fc receptor activation primes mouse bone-marrow-derived macrophages to be more sensitive to IgG in future encounters. Macrophages that have previously experienced subthreshold Fc receptor activation eat more IgG-bound human cancer cells. Increased phagocytosis occurs by two discrete mechanisms—a short- and long-term priming. Long-term priming requires new protein synthesis and Erk activity. Short-term priming does not require new protein synthesis and correlates with an increase in Fc receptor mobility. Our work demonstrates that IgG primes macrophages for increased phagocytosis, suggesting that therapeutic antibodies may become more effective after initial priming doses. [Display omitted] • Oligomerization of FcR-ITAM domains is sufficient to trigger phagocytosis • Prior subthreshold activation of FcRs enhances antibody-dependent phagocytosis • FcR activation increases FcR mobility within 1 h • FcR activation increases phagocytosis for days by changing gene expression via Erk Bond et al. use optogenetics to show that prior subthreshold Fc receptor activation increases the phagocytosis of future antibody-opsonized targets. This priming response lasts at least 72 h and is associated with increased FcR mobility in the short term and Erk-mediated transcriptional changes in the long term. [ABSTRACT FROM AUTHOR]

Epidemiological studies have shown that smoking is associated with increased incidence of severe viral infections leading to hospitalization. Moreover, studies in experimental models have identified impaired antiviral responses and altered inflammatory responses, yet it is unclear how the effects of smoke exposure and influenza A infection interact and how this varies over the course of infection. We hypothesized that smoking would exacerbate innate immune responses against influenza. To test this, female BALB/c mice were exposed to cigarette smoke or air twice a day for 24–28 days and (mock) infected with H3N2 influenza A on day 21 while smoking continued. About 3 and 7 days after infection, changes in immune cell populations, the transcriptome, and viral clearance in lung tissue were analyzed. After influenza A infection, smoke-exposed mice lost significantly more weight than air-exposed controls, indicating that smoking resulted in more severe disease. Immune cell and lung tissue transcriptome analysis revealed that neutrophil infiltration was prolonged and macrophage activation dysregulated after infection of smoke-exposed mice compared with air-exposed controls. Expression of genes in IL-6 and interferon pathways was similarly longer active. In parallel, we observed slower clearance of influenza virus in smoke-exposed mice after infection compared with air-exposed controls, indicating ineffective antiviral responses. Altogether, the data from our mouse model indicate that cigarette smoke exposure prolongs innate immune responses against influenza A. The results from this study help to explain the susceptibility of current smokers to severe influenza A disease. NEW & NOTEWORTHY: In this study, we describe how cigarette smoke exposure modulates immune responses against influenza in mice over time. Using a unique model that continues smoke exposure after infection, we demonstrate that inflammation is prolonged and viral clearance is delayed. This clinically relevant model for smokers that contract influenza is well positioned to investigate interactions between smoke and influenza infection. [ABSTRACT FROM AUTHOR]

Objectives: Investigate whether and which synoviocytes would acquire trained immunity characteristics that could exacerbate joint inflammation following a secondary Staphylococcus aureus infection. Methods: Lipopolysaccharide (LPS) and S. aureus were separately or double injected (21 days of interval) into the tibiofemoral joint cavity of male C57BL/6 mice. At different time points after these stimulations, mechanical nociception was analyzed followed by the analysis of signs of inflammation and damage in the affected joints. The trained immunity markers, including the glycolytic and mTOR pathway, were analyzed in whole tissue or isolated synoviocytes. A group of mice was treated with Rapamycin, an mTOR inhibitor before LPS or S. aureus stimulation. Results: The double LPS – S. aureus hit promoted intense joint inflammation and damage compared to single joint stimulation, including markers in synoviocyte activation, production of proinflammatory cytokines, persistent nociception, and bone damage, despite not reducing the bacterial clearance. The double LPS - S. aureus hit joints increased the synovial macrophage population expressing CX3CR1 alongside triggering established epigenetic modifications associated with trained immunity events in these cells, such as the upregulation of the mTOR signaling pathway (p-mTOR and HIF1α) and the trimethylation of histone H3. Mice treated with Rapamycin presented reduced CX3CR1+ macrophage activation, joint inflammation, and bone damage. Conclusions: There is a trained immunity phenotype in CX3CR1+ synovial macrophages that contributes to the exacerbation of joint inflammation and damage during septic arthritis caused by S. aureus. [ABSTRACT FROM AUTHOR]

Otitis media (OM), a condition stemming from the proliferation of various bacteria within the tympanic cavity (TC), is commonly addressed through the administration of ofloxacin (OFL), a fluoroquinolone antibiotic. Nevertheless, the escalating issue of antibiotic resistance and the challenge of drug leakage underscore the exploration of an alternative, more effective treatment modality in clinical practice. Here, we introduce a simple and easily implementable fluid-regulated strategy aimed at delivering immunomodulatory hydrogels into the TC, ensuring conformal contact with the irregular anatomical surfaces of the middle ear cavity to more effectively eliminate bacteria and treat OM. This innovative strategy exhibits expedited therapeutic process of antibiotic-resistant, acute and chronic OM rats, and significant reductions in the severity of tympanic membrane (TM) inflammation, residual bacteria within the TC (0.12 *105 CFU), and the thickness of TM/TC mucosa (17.63/32.43 μm), as compared to conventional OFL treatment (3.6, 0.76 *105 CFU, 48.70/151.26 μm). The broad-spectrum antibacterial and antibiofilm properties of this strategy against a spectrum of OM pathogens are demonstrated. The strategy is validated to bolster the host's innate immune response through the stimulation of antibacterial protein synthesis, macrophage proliferation and activation, thereby accelerating bacterial eradication and inflammation resolution within the TC. This facile, cost-effective and in vivo degradable technology exhibits promising prospects for future clinical implementation. [ABSTRACT FROM AUTHOR]

Objective: Adult‐onset Still's disease (AOSD) and secondary hemophagocytic lymphohistiocytosis (sHLH) are both hyperferritinemic cytokine storm syndromes that can be difficult to distinguish from each other in hospitalized patients. The objective of this study was to compare the inflammatory markers ferritin, D‐dimer, C‐reactive protein (CRP), and soluble CD25 (sCD25) in patients with AOSD and sHLH. These four markers were chosen as they are widely available and represent different aspects of inflammatory diseases: macrophage activation (ferritin); endothelialopathy (D‐dimer); interleukin‐1/interleukin‐6/tumour necrosis factor elevation (CRP) and T cell activation (sCD25). Methods: This was a single‐center retrospective study. Patients diagnosed by the Hematology service at Vancouver General Hospital for AOSD or sHLH from 2009 to 2023 were included. Results: There were 16 AOSD and 44 sHLH patients identified. Ferritin was lower in AOSD than HLH (median 11 360 μg/L vs. 29 020 μg/L, p =.01) while D‐dimer was not significantly different (median 5310 mg/L FEU vs. 7000 mg/L FEU, p =.3). CRP was higher (median 168 mg/L vs. 71 mg/L, p <.01) and sCD25 was lower (median 2220 vs. 7280 U/mL, p =.004) in AOSD compared to HLH. The combined ROC curve using CRP >130 mg/L and sCD25< 3900 U/mL to distinguish AOSD from HLH had an area under the curve (AUC) of 0.94 (95% confidence interval 0.93–0.97) with sensitivity 91% and specificity 93%. Conclusions: These findings suggest that simple, widely available laboratory tests such as CRP and sCD25 can help clinicians distinguish AOSD from HLH in acutely ill adults with extreme hyperferritinemia. Larger studies examining a wider range of clinically available inflammatory biomarkers in a more diverse set of cytokine storm syndromes are warranted. [ABSTRACT FROM AUTHOR]

We provide an overview of the expanding literature on the role of cytokines and immune mediators in pathophysiology of age-related macular degeneration (AMD). Although many immunological mediators have been linked to AMD pathophysiology, the broader mechanistic picture remains unclear with substantial variations in the levels of evidence supporting these mediators. Therefore, we reviewed the literature considering the varying levels of supporting evidence. A Medical Subject Headings (MeSH) term-based literature research was conducted in September, 2023, consisting of the MeSH terms "cytokine" and "Age-related macular degeneration" connected by the operator "AND". After screening the publications by title, abstract, and full text, a total of 146 publications were included. The proinflammatory cytokines IL-1β (especially in basic research studies), IL-6, IL-8, IL-18, TNF-α, and MCP-1 are the most extensively characterised cytokines/chemokines, highlighting the role of local inflammasome activation and altered macrophage function in the AMD pathophysiology. Among the antiinflammatory mediators IL-4, IL-10, and TGF-β were found to be the most extensively characterised, with IL-4 driving and IL-10 and TGF-β suppressing disease progression. Despite the extensive literature on this topic, a profound understanding of AMD pathophysiology has not yet been achieved. Therefore, further studies are needed to identify potential therapeutic targets, followed by clinical studies • IL-1β, IL-6, IL-8, IL-18, TNF-α, and MCP-1 are the most extensively characterised cytokines/chemokines in the context of AMD. • A wide range of immune modulators are implicated in the pathophysiology of AMD. • Several immune modulators, especially with proinflammatory function, are elevated in the systemic circulation in AMD. [ABSTRACT FROM AUTHOR]

Background: Psoriasis is a common immune-related chronic inflammatory skin disease, often accompanied by significant itching, and once diseased, the course of the disease lasts for most of the lifetime. Tanshinol (TAN) is an active ingredient of Salvia miltiorrhiza, which possesses pharmacological effects such as anti-inflammatory and antioxidant properties. However, the effects of TAN on psoriasis have not been widely reported. Therefore, the aim of this study was to investigate the therapeutic effects and mechanisms of TAN in psoriasis. Methods: An imiquimod (IMQ)-induced psoriasis mouse model was constructed and treated with different doses of TAN to observe the changes in skin lesion phenotype, macrophage polarization, inflammation and Notch signaling pathway in mice. Further removal of macrophages or inhibition or activation of Notch signaling pathway was performed to examine the changes in skin lesion phenotype, macrophage polarization, inflammation and Notch signaling pathway in mice. In addition, in vitro experiments verified that TAN regulates RAW264.7 macrophage polarization and cytokine secretion through the Notch pathway. Results: The results showed that TAN alleviated IMQ-induced skin lesions and pathological phenotypes in psoriasis mice and inhibited Notch signaling pathway and M1-type macrophage polarization. Moreover, macrophage clearance and Notch signaling pathway activation inhibited the effect of TAN on psoriasis. Further in vitro experiments showed that Notch agonists reversed the effects of TAN on macrophage polarization and inflammatory cytokines. Conclusions: Collectively, these findings suggest that TAN may exert a therapeutic effect on psoriasis by inhibiting the Notch signaling pathway and thus M1-type macrophage polarization. [ABSTRACT FROM AUTHOR]

The majority of anticancer agents have a reduced or even complete loss of a therapeutic effect within hypoxic tumors. To overcome this limitation, research efforts have been devoted to the development of therapeutic agents with biological mechanisms of action that are independent of the oxygen concentration. Here we show the design, synthesis, and biological evaluation of the incorporation of a ruthenium (Ru) catalyst into polymeric nanoreactors for hypoxic anticancer therapy. The nanoreactors can catalyze the oxidation of glutathione (GSH) to glutathione disulfide (GSSG) in hypoxic cancer cells. This initiates the buildup of reactive oxygen species (ROS) and lipid peroxides, leading to the demise of cancer cells. It also stimulates the overexpression of the transient receptor potential melastatin 2 (TRPM2) ion channels, triggering macrophage activation, leading to a systemic immune response. Upon intravenous injection, the nanoreactors can systemically activate the immune system, and nearly fully eradicate an aggressive osteosarcoma tumor inside a mouse model. Hypoxic tumor microenvironment (TME) limits the therapeutic efficacy of anticancer drugs. Here this group reports a ruthenium-based nanocatalyst alleviating hypoxic TME, activating protein transient receptor potential melastatin 2 ion channel, promoting systemic immune response thereby eliciting its therapeutic efficacy against osteosarcoma. [ABSTRACT FROM AUTHOR]

It has remained yet unclear which soluble factors regulate the anti-inflammatory macrophage phenotype observed in both homeostasis and tumourigenesis. We show here that haptoglobin, a major serum protein with elusive immunoregulatory properties, binds and buffers bacterial lipopolysaccharides to attenuate activation of NFkB in macrophages. Haptoglobin binds different lipopolysaccharides with low micromolar affinities. Given its abundance, haptoglobin constitutes a buffer for serum-borne lipopolysaccharides, shielding them to safeguard against aberrant inflammatory reactions by reducing the amount of free lipopolysaccharides available for binding to TLR4. Concordantly, NFkB activation by haptoglobin-associated lipopolysaccharides was markedly delayed relative to stimulation with pure lipopolysaccharide. Our findings warrant evaluation of therapeutic benefits of haptoglobin for inflammatory conditions and re-evaluation of purification strategies. Finally, they allow to elucidate mechanisms of enhanced immunosuppression by oncofetal haptoglobin. [ABSTRACT FROM AUTHOR]

Background: Gram-negative bacteria are the main bacterial pathogens infecting Chinese giant salamanders (Andrias davidianus; CGS) in captivity and the wild, causing substantial economic losses in the CGS industry. However, the molecular mechanisms underlying pathogenesis following infection remain unclear. Results: Spleen-derived macrophages from healthy CGS were isolated, cultured, and identified using density gradient centrifugation and immunofluorescence. A macrophage transcriptome database was established 0, 6, and 12 h post lipopolysaccharide stimulation using RNA-sequencing. In the final database 76,743 unigenes and 4,698 differentially expressed genes (DEGs) were functionally annotated. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment results showed that DEGs were concentrated in toll-like receptor–nuclear factor kappa B-related immune pathways. Ten DEGs were validated 12 h after lipopolysaccharide (LPS) stimulation. Although the common LPS recognition receptor toll-like receptor 4 was not activated and the key adaptor protein MyD88 showed no significant response, we observed significant up-regulation of the following adaptors: toll/interleukin-1 receptor domain-containing adaptor inducing interferon-β, tumour necrosis factor receptor-associated factor 6, and transforming growth factor-β activated kinase 1, which are located downstream of the non-classical MyD88 pathway. Conclusions: In contrast to that in other species, macrophage activation in CGS could depend on the non-classical MyD88 pathway in response to bacterial infection. Our study provides insights into the molecular mechanisms regulating CGS antibacterial responses, with implications for disease prevention and understanding immune evolution in amphibians. [ABSTRACT FROM AUTHOR]

Background Purpose Postoperative ileus (POI) is a condition marked by a temporary suppression of gastrointestinal motility following abdominal surgery. The mechanism of POI encompasses various factors and is characterized by two phases: the early neurogenic phase involving both adrenergic and non‐adrenergic neural pathways; the later immune‐mediated phase is characterized by a sterile inflammatory response that lasts several days. Activation of muscularis macrophages triggers a sterile inflammatory process that results in dysfunction of the enteric nervous system (ENS) and a reversible inhibition of gastrointestinal motility.In this minireview, recent insights in the pathophysiological mechanisms underlying POI and potential new therapeutic strategies are described. [ABSTRACT FROM AUTHOR]

Introduction: Streptococcus uberis is a member of the pyogenic cluster of Streptococcus commonly associated with intramammary infection and mastitis in dairy cattle. It is a poorly controlled globally endemic pathogen responsible for a significant cause of the disease worldwide. The ruminant mammary gland provides an atypical body niche in which immune cell surveillance occurs on both sides of the epithelial tissue. S. uberis does not cause disease in nonruminant species and is an asymptomatic commensal in other body niches. S. uberis exploits the unusual niche of the mammary gland to initiate an innate response from bovine mammary macrophage (BMMO) present in the secretion (milk) in which it can resist the host immune responses. As a result - and unexpectedly - the host inflammatory response is a key step in the pathogenesis of S.uberis, without which colonisation is impaired. In contrast to other bacteria pathogenic to the bovine mammary gland, S. uberis does not elicit innate responses from epithelial tissues; initial recognition of infection is via macrophages within milk. Methods: We dissected the role of the bacterial protein SUB1154 in the inflammasome pathway using ex vivo bovine mammary macrophages isolated from milk, recombinant protein expression, and a panel of inhibitors, agonists, and antagonists. We combine this with reverse-transcription quantitative realtime PCR to investigate the mechanisms underlying SUB1154-mediated priming of the immune response. Results: Here, we show that SUB1154 is responsible for priming the NLRP3 inflammasome in macrophages found in the mammary gland. Without SUB1154, IL-1b is not produced, and we were able to restore IL-1b responses to a sub1154 deletion S. uberis mutant using recombinant SUB1154. Surprisingly, only by blocking internalisation, or the cytoplasmic TIR domain of TLR2 were we able to block SUB1154-mediated priming. Discussion: Together, our data unifies several contrasting past studies and provides new mechanistic understanding of potential early interactions between pyogenic streptococci and the host. [ABSTRACT FROM AUTHOR]

Background: In mouse models of atherosclerosis, knockout of the PLA2G2A gene has been shown to reduce the volume of atherosclerotic plaques. Clinical trials have demonstrated the potential of using the sPLA2 inhibitor Varespladib in combination with statins to reduce lipid levels. However, this approach has not yielded the expected results in reducing the risk of cardiovascular events. Therefore, it is necessary to further investigate the mechanisms of PLA2G2A. Methods: Single-cell transcriptome data from two sets of carotid plaques, combined with clinical patient information. were used to describe the expression characteristics of PLA2G2A in carotid plaques at different stages. In order to explore the mechanisms of PLA2G2A, we conducted enrichment analysis, cell–cell communication analysis and single-cell regulatory network inference and clustering analyses. We validated the above findings at the cellular level. Results: Our findings indicate that PLA2G2A is primarily expressed in vascular fibroblasts and shows significant cell interactions with macrophages in the early-stage, especially in complement and inflammation-related pathways. We also found that serum sPLA2 levels have stronger diagnostic value in patients with mild carotid artery stenosis. Subsequent comparisons of single-cell transcriptomic data from early and late-stage carotid artery plaques corroborated these findings and predicted transcription factors that might regulate the progression of early carotid atherosclerosis (CA) and the expression of PLA2G2A. Conclusions: Our study discovered and validated that PLA2G2A is highly expressed by vascular fibroblasts and promotes plaque progression through the activation of macrophage complement and coagulation cascade pathways in the early-stage of CA. [ABSTRACT FROM AUTHOR]

TANK binding kinase 1 (TBK1) is an important kinase that is involved in innate immunity and tumor development. Macrophage colony‐stimulating factor (M‐CSF) regulates the differentiation and function of macrophages towards the immunosuppressive M2 phenotype in the glioblastoma multiforme microenvironment. The role of TBK1 in macrophages, especially in regulating macrophage polarization in response to M‐CSF stimulation, remains unclear. Here, we found high TBK1 expression in human glioma‐infiltrating myeloid cells and that phosphorylated TBK1 was highly expressed in M‐CSF‐stimulated macrophages but not in granulocyte‐macrophage CSF‐induced macrophages (granulocyte‐macrophage‐CSF is involved in the polarization of M1 macrophages). Conditional deletion of TBK1 in myeloid cells induced M‐CSF‐stimulated bone marrow‐derived macrophages to exhibit a proinflammatory M1‐like phenotype with increased protein expression of CD86, interleukin‐1β and tumor necrosis factor‐α, as well as decreased expression of arginase 1. Mechanistically, TBK1 deletion or inhibition by amlexanox or GSK8612 reduced the expression of the transcription factor interferon‐regulatory factor (IRF)4 and increased the level of IRF5 activation in macrophages stimulated with M‐CSF, leading to an M1‐like profile with highly proinflammatory factors. IRF5 deletion reversed the effect of TBK1 inhibition on M‐CSF‐mediated macrophage polarization. Our findings suggest that TBK1 contributes to the regulation of macrophage polarization in response to M‐CSF stimulation partly through the IRF5/IRF4 axis. [ABSTRACT FROM AUTHOR]

Macrophage polarization is an important phenomenon that underlies various physiological mechanisms protective to the host and pathological mechanisms manipulated by microbes, thus we need to come to terms with this phenomenon and understand it at the molecular level. This paper highlights various aspects of macrophage activation and polarization starting from the discovery of macrophages to the latest advancements like using algorithms to determine polarization in a marker-free manner. We have covered macrophage polarization in response to various stimuli and also how this is affected in various disease conditions. Macrophage polarization in many neurodegenerative diseases has also been covered in this review. Various methods used for detecting and quantifying this phenomenon have been discussed below. It has been noted that our understanding of this phenomenon may lead to many novel therapeutic approaches in dealing with a varied set of disease pathologies making it extremely valuable for clinical practice. Newer technological advancements in the field have the potential to act as diagnostic tools for various diseases. In this paper, we have tried to summarize the existing information on macrophage polarization and activation to understand the progress we have made in understanding this phenomenon. Highlights: History of macrophage activation and polarization have been discussed. Various metabolic pathways that underline the functions of polarized macrophages has been discussed. Macrophage polarization in response to various stimuli in the microenvironment has been discussed including the newer discovered M4 macrophage state. Macrophage polarization in response to various disease pathologies like neurodegenerative diseases, mycobacterial diseases, plaque, HIV and other disease has been highlighted. Different methods for describing macrophage polarization have been discussed including newer methods using algorithms and machine learning. [ABSTRACT FROM AUTHOR]

Deposition of monosodium urate and calcium pyrophosphate (MSU and CPP) micro-crystals is responsible for painful and recurrent inflammation flares in gout and chondrocalcinosis. In these pathologies, the inflammatory reactions are due to the activation of macrophages responsible for releasing various cytokines including IL-1β. The maturation of IL-1β is mediated by the multiprotein NLRP3 inflammasome. Here, we find that activation of the NLRP3 inflammasome by crystals and concomitant production of IL-1β depend on cell volume regulation via activation of the osmo-sensitive LRRC8 anion channels. Both pharmacological inhibition and genetic silencing of LRRC8 abolish NLRP3 inflammasome activation by crystals in vitro and in mouse models of crystal-induced inflammation. Activation of LRRC8 upon MSU/CPP crystal exposure induces ATP release, P2Y receptor activation and intracellular calcium increase necessary for NLRP3 inflammasome activation and IL-1β maturation. We identify a function of the LRRC8 osmo-sensitive anion channels with pathophysiological relevance in the context of joint crystal-induced inflammation. Formation of urate and calcium pyrophosphate micro-crystals is responsible for painful inflammatory flares in gout and chondrocalcinosis. Here the authors show that the osmo-sensitive LRRC8 anion channel is involved with macrophage inflammasome activation by crystals involving cell volume regulation and ATP release leading to P2Y receptor activation. [ABSTRACT FROM AUTHOR]

ABSTRACT Aims Methods Results Conclusions Since its discovery, the patatin‐like phospholipase domain containing 3 (PNPLA3) (rs738409 C>G p.I148M) variant has been studied extensively to unravel its molecular function. Although several studies proved a causal relationship between the PNPLA3 I148M variant and MASLD development and particularly fibrosis, the pathological mechanisms promoting this phenotype have not yet been fully clarified.We summarise the latest data regarding the PNPLA3 I148M variant in hepatic stellate cells (HSCs) activation and macrophage biology or the path to inflammation‐induced fibrosis.Elegant but contradictory studies have ascribed PNPLA3 a hydrolase or an acyltransferase function. The PNPLA3 I148M results in hepatic lipid accumulation, which predisposes the hepatocyte to lipotoxicity and lipo‐apoptosis, producing DAMPs, cytokines and chemokines leading to recruitment and activation of macrophages and HSCs, propagating fibrosis. Recent studies showed that the PNPLA3 I148M variant alters HSCs biology via attenuation of PPARγ, AP‐1, LXRα and TGFβ activity and signalling.The advent of refined techniques in isolating HSCs has made PNPLA3's direct role in HSCs for liver fibrosis development more apparent. However, many other mechanisms still need detailed investigations. [ABSTRACT FROM AUTHOR]

Exosomes, membrane-bound extracellular vesicles, ranging from approximately 30-200 nm in diameter, are released by almost all cell types and play critical roles in intercellular communication. In response to the prevailing stress, the exosome-bound protein signatures vary in abundance and composition. To identify the bronchoalveolar lavage fluid (BALF) exosome-bound proteins associated with mucoinflammatory lung disease and to gain insights into their functional implications, we compared BALF exosomes-derived proteins from adult Scnn1b transgenic (Scnn1b-Tg+) and wild type (WT) mice. A total of 3,144 and 3,119 proteins were identified in BALF exosomes from Scnn1b-Tg+ and WT mice, respectively. Using cutoff criteria (Log2 fold-change > 1 and adjusted p-value < 0.05), the comparison of identified proteins revealed 127 and 30 proteins that were significantly upregulated and downregulated, respectively, in Scnn1b-Tg+ versus WT mice. In addition, 52 and 27 proteins were exclusively enriched in Scnn1b-Tg+ and WT mice, respectively. The identified exosome-bound proteins from the homeostatic airspaces of WT mice were mostly relevant to the normal physiological processes. The protein signatures enriched in the BALF exosomes of Scnn1b-Tg+ mice were relevant to macrophage activation and mucoinflammatory processes. Ingenuity pathway analyses revealed that the enriched proteins in Scnn1b-Tg+ mice contributed to the inflammatory responses and antimicrobial defense pathways. Selective proteins including, RETNLA/FIZZ1, LGALS3/Galectin-3, S100A8/MRP8, and CHIL3/YM1 were immunolocalized to specific cell types. The comparative analysis between enriched BALF exosome proteins and previously identified differentially upregulated genes in Scnn1b-Tg+ versus WT mice suggested that the compartment-/cell-specific upregulation in gene expression dictates the enrichment of their respective proteins in the lung airspaces. Taken together, this study demonstrates that the BALF exosome-bound protein signatures reflect disease-relevant disturbances. Our findings suggest that the exosomes carry disease-relevant protein signatures that can be used as a diagnostic as well as predictive biomarkers for mucoinflammatory lung disease. [ABSTRACT FROM AUTHOR]

The prevention and treatment strategies for traumatic infection often focus on the use of antibiotics, while eschew the combined treatment of the bacteria, their toxins, and inflammatory mediators. This might be a main reason the prognosis of wound victims has not improved. Although our previous work found that the combination of indomethacin (IND) and ciprofloxacin (CIP) could promote skin wound repair and enhance the immune function, the efficacy and safety of this strategy for severe traumatic infection-mediated complications remain unknown. Additionally, there is no study on the relevant target cells and molecular mechanisms. In this study, C57BL/6 adult male mice were modeled for severe traumatic infection, and the optimal doses of IND and CIP alone were determined. After that, the efficacy and safety of IND plus CIP in traumatic infection mice were explored. Then the differentially expressed genes of activated macrophages in this process were analysed and verified by transcriptomic methods and conventional experimental techniques. The role of a candidate signalling pathway (PI3K/Akt) in regulating macrophage function and drug combination therapy was evaluated. The results showed that IND plus CIP increased the survival rate, reduced the degree of inflammatory response, and enhanced the bacteriostatic effect in mice under traumatic infection. This combined therapy did not cause significant damage to the functions of important organs (liver, kidney, heart). In addition, IND combined with CIP induced macrophages to significantly change their expression levels of several cytokines, including interleukin (IL) -1β, IL-6, IL-10, IL-22, IL-23A, IL-17A, IL-17F, cluster of differentiation (CD) 11b and other genes/encode proteins. Further study showed that intervention with the PI3K inhibitor LY294002 modulated the secretion function of the above-mentioned macrophages and Akt activation (phosphorylation at serine 473). IND plus CIP can regulate macrophage function through the PI3K/Akt signalling pathway and improve the prognosis of severe traumatic infected mice. This may be a new therapeutic strategy for the prevention and treatment of severe traumatic infection. [ABSTRACT FROM AUTHOR]

Endometriosis is a significant reproductive health issue with pain being the primaru symptom. The complex pain in endometriosis involves the activation of macrophages, inflammatory activators such as NF-kB, neural growth factors (NGF), cytokines, adhesive molecules (ICAM-1), and mediators (PGE2) which they are stimulate sensory nerve fibers and produce nociceptive signals. This study is aim for investigate the effect of Mesenchymal Stem Cell (MSC) administration on the expression of NF-kB, NGF, and PGE2 concentration in a mouse model of endometriosis. Thirty-three mices were randomly divided into 3 groups consist non-endometriosis (P0), endometriosis without treatment (P1), and endometriosis with MSC administration (P2). The results showed MSC administration significantly reduced the expression of NF-kB by found scoring 2 groups (P1: 6.96 ± 0.13 and P2: 4.446 ± 0.228) and NGF (P1: 7.118 ± 0.629 and P2: 4.927 ± 1.187) also PGE2 (P1:1005.862 ± 176.656 and P2: 891.218 ± 54.031. In onclusion, this study demonstrates that MSC administration can able reduce the expression of NF-kB and NGF, but not to PGE2. The suggestion we can said is the MSC have potential therapeutic value in managing endometriosis-asssosciated pain by modulating inflammatory and neurotrophic factors. [ABSTRACT FROM AUTHOR]

As an important member of innate immunity, macrophages show remarkable plasticity and heterogeneity, and play an important role in immune regulation, tissue development, homeostasis of the internal environment and injury repair. However, the excessive activation of macrophages is closely related to the occurrence and development of many diseases. The prenylated flavonoid structure is one of the characteristic structures isolated from Sophora flavescens, with anti-inflammatory, anti-tumor, anti-allergy and other effects. In this study, the effects of (2R)-3β,7,4′-trihydroxy-5-methoxy-8-prenylflavanone (TMP), a prenylated dihydroflavonol, on the polarization and phagocytosis of macrophages were systematically studied. In LPS-induced M1-type macrophages, TMP dose-dependently inhibited the expression of COX-2, iNOS and the secretion of NO, IL-1β, IL-6 and IL-18, showing an inhibitory effect on M1 polarization. Further experiments revealed that it was related to the inhibition of TLR4-related AKT/mTOR, MAPK and NF-κB signaling pathways; in IL-4-induced M2-type macrophages, TMP down-regulated the expression of M2-related Arg1, IL-10, TGF-β, CD206 and CD163, as well as the phosphorylation levels of AKT1 and STAT6. For macrophages in a physiological state, it was very important for cells to return from a stress state to a phenotypic stability in the M0 state. These results indicated that TMP negatively regulated the M1/M2 polarization of macrophages, and made them tend to M0 homeostasis, which might provide new theoretical and data support for explaining the anti-inflammatory immunoregulatory activity of Sophora flavescens. [ABSTRACT FROM AUTHOR]

Objective: ST-elevation myocardial infarction (STEMI) poses a significant challenge despite advances in reperfusion strategies. The "no-reflow" phenomenon, characterized by inadequate microvascular blood flow restoration following successful revascularization, remains poorly understood. Inflammation, particularly interleukin-34 (IL-34), is implicated in cardiovascular disease, prompting investigation into its role in no-reflow. Methods: This observational study included 182 patients with STEMI (32 with no-reflow, 150 without) and 100 controls. Clinical and angiographic data were analyzed, and IL-34 levels were measured. Logistic regression and receiver operating characteristic (ROC) analysis assessed IL-34's predictive value for no-reflow. Results: Patients with no reflow exhibited elevated IL-34 levels compared with controls and those without no-reflow. Logistic regression identified IL-34 as an independent predictor of no-reflow (odds ratio: 1,020, p<0.001). ROC analysis showed IL-34's significant predictive value (area under the curve: 0.972, p<0.001). Conclusion: IL-34 emerges as a robust predictor of no-reflow in STEMI, potentially reflecting its role in macrophage activation and the inflammatory response. These findings suggest a novel avenue for understanding and mitigating no-reflow in STEMI, paving the way for targeted therapies. Early identification of high-risk patients could inform tailored interventions, ultimately improving STEMI outcomes. Further research is warranted to elucidate IL-34's mechanistic involvement and validate its predictive value in larger cohorts. [ABSTRACT FROM AUTHOR]

Glucocorticoids are steroid hormones well known for their potent anti-inflammatory effects. However, their immunomodulatory properties are multifaceted. Increasing evidence suggests that glucocorticoid signaling promotes effective immunity and that disruption of glucocorticoid signaling impairs immune function. In this study, we conditionally deleted the glucocorticoid receptor (GR) in the myeloid lineage using the LysM-Cre driver (myGRKO). We examined the impact on macrophage activation and gastric immune responses to Helicobacter pylori, the best-known risk factor of gastric cancer. Our results indicate that, compared with wild type (WT), glucocorticoid receptor knockout (GRKO) macrophages exhibited higher expression of proinflammatory genes in steroid-free conditions. However, when challenged in vivo, GRKO macrophages exhibited aberrant chromatin landscapes and impaired proinflammatory gene expression profiles. Moreover, gastric colonization with H. pylori revealed impaired gastric immune responses and reduced T cell recruitment in myGRKO mice. As a result, myGRKO mice were protected from atrophic gastritis and pyloric metaplasia development. These results demonstrate a dual role for glucocorticoid signaling in preparing macrophages to respond to bacterial infection but limiting their pathogenic activation. In addition, our results support that macrophages are critical for gastric H. pylori immunity. NEW & NOTEWORTHY: Signaling by endogenous glucocorticoids primes macrophages toward more robust responses to pathogens. Disruption of glucocorticoid signaling caused dysregulation of the chromatin landscape, blunted proinflammatory gene activation upon bacterial challenge, and impaired the gastric inflammatory response to Helicobacter pylori infection. [ABSTRACT FROM AUTHOR]

There is considerable evidence that the immune system plays a role in hypertension, however this role is not fully characterized. Our previous studies demonstrated that mesenteric perivascular adipose tissue (mPVAT) harbors a large T cell population, which is a cell type identified as contributing to hypertension. In the present study, we tested the hypothesis that soluble mediators in mPVAT influence T cell function just prior to the development of hypertension. Toward this end, we utilized a unique model of hypertension in which Dahl S rats on a high fat (HF) diet develop hypertension. We found that conditioned media (CM) from mPVAT from healthy Dahl S rats on control diet buffers T cell activation, however, mPVAT-CM from Dahl S rats on a HF diet markedly increased inflammatory cytokine induction (IFNγ, GM-CSF and IL-17a) by activated T cells. These cytokines are known to promote activation of macrophages and neutrophils, among other effects. Conversely, the anti-inflammatory cytokine, IL-10, was not different between the groups, suggesting the effect is selective for inflammatory cytokines. Furthermore, we conducted bulk RNA-seq on activated T cells cultured in mPVAT-CM from Dahl S rats on either control (CTL) or HF diet for 10 weeks. In accordance with the cytokine analysis, mPVAT-CM from HF diet-fed rats significantly upregulated many genes associated with IFNγ/IL-17 induction, whereas Th2/Treg-associated genes were downregulated. Taken together, these data strongly suggest soluble mediators from mPVAT influence T cell inflammatory status and may promote Th1/Th17 differentiation preceding the development of hypertension triggered by HF diet. [ABSTRACT FROM AUTHOR]

Leishmania parasites embedded in the promastigote secretory gel in the midgut of its sand fly vector is analogous to a classical attached microbial biofilm. Leishmania biofilm is important for positioning parasites for transmission but also maintenance of sand fly infection. Leishmania proteophosphoglycans within the biofilm are important for the establishment of infection in mice by hijacking the wound-healing response in skin and the activation of macrophages. Biofilms have been observed during the insect stage of other trypanosomatid parasites, including the honeybee parasite, Lotmaria passim. Leishmania make an abundant glycoprotein and proteophosphoglycan-rich gel, called the promastigote secretory gel, in the anterior midgut of their sand fly vector. This gel is a multi-faceted virulence factor which promotes the survival and transmission of the parasites between hosts. Here, we present the case that Leishmania parasites embedded in the promastigote secretory gel should be redefined as a biofilm as it shares striking similarities in biogenesis, form, and function with biofilms of other unicellular organisms. We believe that this reinterpretation will stimulate new hypotheses and avenues of research to improve our understanding of the developmental programme of Leishmania and the interaction these parasites and other kinetoplastids have with their insect hosts. [ABSTRACT FROM AUTHOR]

Background: Gremlin1 is a multifunctional protein whose expression is demonstrated to be involved in a series of physiology and pathological processes. The association between Gremlin1 and apcial periodontitis (AP) has been established. M1-polarized macrophages are crucial immune cells that exacerbate the progression of apical periodontal inflammatory response, but the function of Gremlin1 during macrophages activation in periapical lesions is still unclear. This study attempts to explore the regulatory effects of Gremlin1 on macrophage polarization on apical periodontitis microenviroment. Methods: Clinical specimens were used to determine the expression of Gremlin1 in periapical tissues by immunohistochemical (IHC) staining. Then, the disease models of periapical inflammation in rats were established, and adenovirus- associated virus (AAVs) was used to blockade Gremlin1 expression. Lentivirus carrying sh-Gremlin1 particles were used to transfect THP-1 induced M1-subtype macrophages. To assess the expression of associated molecules, Western blot, immunofluorescence staining were performed. Results: Gremlin1 was significantly up-regulated in the periapical tissues of subjects with AP as identified by IHC staining, and positively correlated with levels of M1 macrophage-associated genes. Rats AP model with inhibition of Gremlin1 in periapical lesions exhibited limited infiltration of macrophages and decreased expression of M1 macrophage-related genes in periapical lesions. Furthermore, Gremlin1 blockade substantially decreased the Notch1/Hes1 signaling pathway activation level. The in vitro experiments confirmed the above results. Conclusion: Taken together, current study illustrated that the Gremlin1 suppression in periapical lesions inhibited M1 macrophage polarization through Notch1/Hes1 axis. Moreover, Gremlin1 may act as a potential candidate in the treatment of AP. [ABSTRACT FROM AUTHOR]

The choroid plexus (ChP) serves as the principal origin of cerebrospinal fluid (CSF). CSF hypersecretion due to ChP inflammation has emerged as an important pathogenesis of hydrocephalus recently. Nevertheless, the precise mechanisms of ChP inflammation and the ensuing CSF hypersecretion in hydrocephalus remain ill-defined. In the present study, we elucidate the critical role of macrophages in the pathogenesis of ChP inflammation. Specifically, we identify the chemokine CCL2, released by ChP epithelial cells, recruits CCR2+ monocytes to the ChP thereby inciting hydrocephalus pathogenesis. The accumulated ChP macrophages increase the inflammation in ChP epithelial cells through TNF- α /TNFR1/NF- κ B signaling cascade, thereby leading to CSF hypersecretion. Strikingly, augmentation of ChP‒CCL2 using an adeno-associated viral approach (AAV) exacerbates macrophage recruitment, activation, and ventriculomegaly in rat PHH models. Systemic application of Bindarit, a specific CCL2 inhibitor, significantly inhibits ChP macrophage infiltration and activation and reduces CSF secretion rate. Furthermore, the administration of CCR2 antagonist (INCB 3284) reduces ChP macrophage accumulation and ventriculomegaly. This study not only unveils the ChP CCL2‒CCR2 signaling in the pathophysiology of hydrocephalus but also unveils Bindarit as a promising therapeutic choice for the management of posthemorrhagic hydrocephalus. After intraventricular hemorrhage, CCL2 secreted by choroid plexus epithelial cells recruited CCR2+ monocytes and released inflammatory cytokines including TNF- α. Inhibition of CCL2 secretion through Bindarit could ameliorate hydrocephalus. [Display omitted] [ABSTRACT FROM AUTHOR]

Purinergic signaling plays a causal role in the modulation of immune inflammatory response in the course of psoriasis, but its regulatory mechanism remains unclear. As a member of purinoceptors, P2Y 6 R mainly distributed in macrophages was significantly up-expressed in skin lesions from patients with psoriasis in the present study. Here, the severity of psoriasis was alleviated in imiquimod-treated mice with macrophages conditional knockout of P2Y 6 R, while the cell-chat algorithm showed there was a correlation between macrophage P2Y 6 R and Th1 cells mediated by IL-27. Mechanistically, P2Y 6 R enhanced PLC β /p-PKC/MAPK activation to induce IL-27 release dependently, which subsequently regulated the differentiation of Th1 cells, leading to erythematous and scaly plaques of psoriasis. Interestingly, we developed a novel P2Y 6 R inhibitor FS-6, which bonds with the ARG266 side chain of P2Y 6 R, exhibited remarkable anti-psoriasis effects targeting P2Y 6 R. Our study provides insights into the role of P2Y 6 R in the pathogenesis of psoriasis and suggests its potential as a target for the development of therapeutic interventions. A novel P2Y 6 R inhibitor FS-6 could be developed as an anti-psoriasis drug candidate for the clinic. Macrophage P2Y 6 R enhances release of IL-27 to mediate Th1 cell differentiation in the pathogenesis of psoriasis via PLC β /p-PKC/MAPK signaling, which could be reversed by a novel P2Y 6 R inhibitor FS-6. [Display omitted] [ABSTRACT FROM AUTHOR]

Background/objective: Amyotrophic lateral sclerosis (ALS) is a diagnosis that incorporates a heterogeneous set of neurodegenerative processes into a single progressive and uniformly fatal disease making the development of a uniformly applicable therapeutic difficult. Recent multinational ALS natural history incidence studies have identified systemic chronic activation of the innate immune system as a major risk factor for developing ALS. Persistent immune activation in patients with ALS leads to loss of muscle and lowering of serum creatinine. The goal of the current study was to test whether the slowing of nerve and muscle destruction in NP001-treated ALS patients compared with controls in phase 2 studies would lead to extension of survival. Methods: Phase 2 clinical studies with NP001, an intravenously administered form of the innate immune system regulator NaClO2, are now reporting long-term survival benefits for drug recipients vs. placebo controls after only six months of intermittent treatment. As a prodrug, NP001 is converted by macrophages to taurine chloramine, a long-lived regulator of inflammation. We performed a pooled analysis of all patients who had completed the studies in two six-month NP001 phase 2 trials. Changes in respiratory vital capacity and the muscle mass product, creatinine, defined treated patients who, compared to placebo, had up to a year of extended survival. Conclusions: The observed longer survival in ALS patients with the greatest inflammation-associated muscle loss provides further evidence that ALS is a disease of ongoing innate immune dysfunction and that NP001 is a disease-modifying drug with sustained clinical activity. [ABSTRACT FROM AUTHOR]

Implants and medical devices are efficient and practical therapeutic solutions for a multitude of pathologies. Titanium and titanium alloys are used in orthopedics, dentistry, and cardiology. Despite very good mechanical properties and corrosion resistance, titanium implants can fail due to inflammatory or tissue degradation–related complications. Macrophages are major immune cells that control acceptance of failure of the implant. In this study, for the first time, we have performed a systematic analysis of the response of differentially activated human macrophages, M(Control), M(IFNγ), and M(IL-4), to the polished and porous titanium surfaces in order to identify the detrimental effect of titanium leading to the tissue destruction and chronic inflammation. Transcriptome analysis revealed that the highest number of differences between titanium and control settings are found in M(IL-4) that model healing type of macrophages. Real-time quantitative polymerase chain reaction analysis confirmed that both polished and porous titanium affected expression of cytokines, chitinases/chitinase-like proteins, and matrix metalloproteinases (MMPs). Titanium-induced release and activation of MMP7 by macrophages was enhanced by fibroblasts in both juxtacrine and paracrine cell interaction models. Production of titanium-induced MMPs and cytokines associated with chronic inflammation was independent of the presence of Staphylococcus aureus. MMP7, one of the most pronounced tissue-destroying factors, and chitinase-like protein YKL-40 were expressed in CD68+ macrophages in peri-implant tissues of patients with orthopedic implants. In summary, we demonstrated that titanium induces proinflammatory and tissue-destructing responses mainly in healing macrophages, and the detrimental effects of titanium surfaces on implant-adjacent macrophages are independent on the bacterial contamination. [ABSTRACT FROM AUTHOR]

Introduction: Obesity is one of the major healthcare challenges. It affects one in eight people around the world and leads to several comorbidities, including type 2 diabetes, hyperlipidemia, and arterial hypertension. GLP-1 analogs have become major players in the therapy of obesity, leading to significant weight loss in patients. However, benefits resulting from their usage seem to be greater than simple appetite reduction and glucose-lowering potential. Recent data show better cardiovascular outcomes, which are connected with the improvements in the course of atherosclerosis. Macrophages are crucial cells in the forming and progression of atherosclerotic lesions. Previously, it was shown that in vitro treatment with GLP-1 analogs can affect macrophage phenotype, but there is a paucity of in vivo data. Objective: To evaluate the influence of in vivo treatment with liraglutide on basic phenotypic and functional markers of macrophages. Methods: Basic phenotypic features were assessed (including inducible nitric oxide synthase, arginase 1 and mannose receptors), proinflammatory cytokine (IL-1β, TNFα) release, and oxidative stress markers (reactive oxygen species, malondialdehyde) in macrophages obtained prior and after 3-month therapy with liraglutide in patients with obesity. Results: Three-month treatment with subcutaneous liraglutide resulted in the alteration of macrophage phenotype toward alternative activation (M2) with accompanying reduction in the TNFα release and diminished oxidative stress markers. Conclusions: Our results show that macrophages in patients treated with GLP-1 can alter their phenotype and function. Those findings may at least partly explain the pleiotropic beneficial cardiovascular effects seen in subjects treated with GLP-1 analogs. [ABSTRACT FROM AUTHOR]

Background: Glioblastoma (GBM) is the most frequent and aggressive brain tumor in adults with the lowest survival rates five years post-diagnosis. Oncolytic viruses (OVs) selectively target and damage cancer cells, and for this reason they are being investigated as new therapeutic tools also against GBM. Methods: An oncolytic herpes simplex virus type 1 (oHSV-1) with deletions in the γ34.5 neurovirulence gene and the US12 gene, expressing enhanced green fluorescent protein (EGFP-oHSV-1) as reporter gene was generated and tested for its capacity to infect and kill the murine GL261 glioblastoma (GBM) cell line. Syngeneic mice were orthotopically injected with GL261cells. Seven days post-implantation, EGFP-oHSV-1 was administered intratumorally. Twenty-one days after parental tumor challenge in the opposite brain hemisphere, mice were sacrified and their brains were analysed by immunohistochemistry to assess tumor presence and cell infiltrate. Results: oHSV-1 replicates and induces cell death of GL261 cells in vitro. A single intracranial injection of EGFP-oHSV-1 in established GL261 tumors significantly prolongs survival in all treated mice compared to placebo treatment. Notably, 45% of treated mice became long-term survivors, and rejected GL261 cells upon rechallenge in the contralateral brain hemisphere, indicating an anamnestic antitumoral immune response. Post-mortem analysis revealed a profound modification of the tumor microenvironment with increased infiltration of CD4 + and CD8 + T lymphocytes, intertumoral vascular collapse and activation and redistribution of macrophage, microglia, and astroglia in the tumor area, with the formation of intense fibrotic tissue suggestive of complete rejection in long-term survivor mice. Conclusions: EGFP-oHSV1 demonstrates potent antitumoral activity in an immunocompetent GBM model as a monotherapy, resulting from direct cell killing combined with the stimulation of a protective adaptive immune response. These results open the way to possible application of our strategy in clinical setting. [ABSTRACT FROM AUTHOR]

Introduction: HIV-exposed uninfected (HEU) infants exhibit elevated proinflammatory biomarkers that persist after birth. However, comprehensive assessments of bioprofiles associated with immune regulation and development in pregnant women with HIV (PWH) and HEU infants has not been performed. Maternal immunity in PWH may be imprinted on their HEU newborns, altering immune bioprofiles during early immune development. Methods: Cryopreserved paired plasma samples from 46 HEU infants and their mothers enrolled in PACTG 316, a clinical trial to prevent perinatal HIV-1 transmission were analyzed. PWH received antiretrovirals (ARV) and had either fully suppressed or unsuppressed viral replication. Maternal blood samples obtained during labor and infant samples at birth and 6 months were measured for 21 biomarkers associated with germinal centers (GC), macrophage activation, T-cell activation, interferon gamma (IFN-g)-inducible chemokines, and immune regulatory cytokines using Mesoscale assays. Pregnant women without HIV (PWOH) and their HIV unexposed uninfected (HUU) newborns and non-pregnant women without HIV (NPWOH) served as reference groups. Linear regression analysis fitted for comparison among groups and adjusted for covariant(s) along with principal component analysis performed to assess differences among groups. Results: Compared with NPWOH, PWOH displayed higher levels of GC, macrophage, and regulatory biomarkers. PWH compared to PWOH displayed elevated GC, T cell activation, and IFN-γ-inducible chemokines biomarkers at delivery. Similar to their mothers, HEU infants had elevated GC, macrophage, and IFN-γ-inducible chemokines, as well as elevated anti-inflammatory cytokines, IL-10 and IL-1RA. Across all mother/newborn dyads, multiple biomarkers positively correlated, providing further evidence that maternal inflammation imprints on newborn bioprofiles. By 6 months, many HEU biomarkers normalized to levels similar to HUU infants, but some GC and inflammatory biomarkers remained perturbed. Bioprofiles in PWH and HEU infants were similar regardless of the extent of maternal viral suppression by ARV. Conclusions: GC immune pathways are perturbed in HEU newborns, but immune regulatory responses down regulate inflammation during early infancy, indicating a transient inflammatory effect. However, several GC biomarkers that may alter immune development remain perturbed. [ABSTRACT FROM AUTHOR]

Background. Atherosclerosis is an inflammatory cardiovascular disease. However, whether the association of immune cells in plaques promotes the progression of this disease has not yet been completely elucidated. Materials and Methods. Thus, this study aimed to investigate the relationship between C1q+ macrophages and CD8T cells through scRNA‐seq data reanalysis, quantitative real‐time PCR, and flow cytometry. Chromatin immunoprecipitation‐quantitative polymerase chain reaction, western blot, and antibody‐blocking experiments were performed to investigate the role of macrophage–CD8T interaction in atherosclerosis. An atherosclerotic mouse model was developed to confirm our findings. Results. Mechanistically, Spi1 expression induced by granulocyte–macrophage colony‐stimulating factor promoted C1q expression in the macrophages. Moreover, C1q+ macrophages suppressed CD8T cell apoptosis by upregulating Slc7a7 expression to enhance the L‐arginine uptake of CD8T cells. CD8T‐derived interferon‐γ promoted macrophage activation to induce atherosclerosis. Blockade of the C1q–C1qbp axis attenuated atherosclerosis. Conclusion. In conclusion, macrophages interacting with CD8T promote atherosclerosis development via the C1q–C1qbp axis. [ABSTRACT FROM AUTHOR]

Objective: Schizonepeta tenuifolia -Saposhnikovia divaricata (Jingjie-Fangfeng, JF) has been used for years to treat allergic inflammatory skin diseases like atopic dermatitis, but the specific effects and mechanisms of JF are still unclear. Purpose: We aim to investigate the therapeutic effect and mechanism of JF in MC903-induced atopic dermatitis-like model. Methods: JF decoction was subjected to rigorous HPLC and GC analysis. The JF decoction was then freshly prepared and administered to MC903-induced atopic dermatitis -like mice models to investigate its therapeutic effects. Our evaluation focused on several markers of inflammation including the TEWL index, ear thickness, swelling, and specific inflammation indicators such as TSLP, IL33, IgE, and immune cell presence at the lesion sites. We measured Transient Receptor Potential Vanilloid 1 (TRPV1) expression levels through immunofluorescent staining in skin tissue from both atopic dermatitis patients and the MC903-treated mice. Furthermore, TRPV1 expression and macrophage activation markers were measured in LPS/IFN-γ-stimulated Raw264.7 and THP-1 cell models in vitro. Additionally, we developed cell lines that overexpress TRPV1 and investigated how JF treatment affects NF-κB p65 phosphorylation in these cells to understand better the role of TRPV1 in atopic dermatitis. Results: The JF decoction met the standards outlined in the Chinese pharmacopeia. The JF decoction significantly alleviated inflammatory skin symptoms and helped restore skin barrier function. Additionally, it reduced the levels of IgE and pro-inflammatory cytokines TSLP, IL-33, and IL-4. There was also a noticeable decrease in mast cell infiltration and degranulation. Notably, JF decoction reduced infiltrated macrophages with limited affection on T cell infiltration. It also decreased F4/80+/TRPV1+ cells in atopic dermatitis mice and TRPV1 expression in LPS/IFNγ-stimulated microphages. Additionally, we observed that CD68+/TRPV1+ cells increased in human atopic dermatitis tissue. Further studies showed that JF water extract (JF-WE) suppressed TRPV1 expression in macrophages, potentially by affecting NF-κB p65 phosphorylation rather than the JAK-STAT6 pathway. Conclusion: This study offers initial evidence of the effectiveness of JF-WE in suppressing inflammation in atopic dermatitis. The therapeutic effect might stems from its ability to downregulate TRPV1 expression and subsequent NF-κB p65 phosphorylation in macrophages. [ABSTRACT FROM AUTHOR]

Background: Islet transplantation is a promising treatment for type 1 diabetes that aims to restore insulin production and improve glucose control, but long term graft survival remains a challenge due to immune rejection. Methods: ScRNA-seq data from syngeneic and allogeneic islet transplantation grafts were obtained from GSE198865. Seurat was used for filtering and clustering, and UMAP was used for dimension reduction. Differentially expressed genes were analyzed between syngeneic and allogeneic islet transplantation grafts. Gene set variation analysis (GSVA) was performed on the HALLMARK gene sets from MSigDB. Monocle 2 was used to reconstruct differentiation trajectories, and cytokine signature enrichment analysis was used to compare cytokine responses between syngeneic and allogeneic grafts. Results: Three distinct macrophage clusters (Mø-C1, Mø-C2, and Mø-C3) were identified, revealing complex interactions and regulatory mechanisms within macrophage populations. The significant activation of macrophages in allogeneic transplants was marked by the upregulation of allograft rejection related genes and pathways involved in inflammatory and interferon responses. GSVA revealed eight pathways significantly upregulated in the Mø-C2 cluster. Trajectory analysis revealed that Mø-C3 serves as a common progenitor, branching into Mø-C1 and Mø-C2. Cytokine signature enrichment analysis revealed significant differences in cytokine responses, highlighting the distinct immunological environments created by syngeneic and allogeneic grafts. Conclusion: This study significantly advances the understanding of macrophage roles within the context of islet transplantation by revealing the interactions between immune pathways and cellular fate processes. The findings highlight potential therapeutic targets for enhancing graft survival and function, emphasizing the importance of understanding the immunological aspects of transplant acceptance and longevity. [ABSTRACT FROM AUTHOR]

Background: Idiopathic pulmonary fibrosis (IPF) is a group of chronic interstitial pulmonary diseases characterized by myofibroblast proliferation and extracellular matrix (ECM) deposition. However, current treatments are not satisfactory. Therefore, more effective therapies need to be explored. Cepharanthine (CEP) is a naturally occurring alkaloid that has recently been reported to have multiple pharmacological effects, particularly in chronic inflammation. Methods: For in vivo experiments, first, a pulmonary fibrosis murine model was generated via tracheal injection of bleomycin (BLM). Second, the clinical manifestations and histopathological changes of the mice were used to verify that treatment with CEP might significantly reduce BLM-induced fibrosis. Furthermore, flow cytometric analysis was used to analyze the changes in the number of M2 macrophages in the lung tissues before and after treatment with CEP to explore the relationship between macrophage M2 polarization and pulmonary fibrosis. In vitro, we constructed two co-culture systems (THP-1 and MRC5 cells, RAW264.7 and NIH 3T3 cells), and measured the expression of fibrosis-related proteins to explore whether CEP could reduce pulmonary fibrosis by regulating macrophage M2 polarization and fibroblast activation. Results: The results showed that the intranasal treatment of CEP significantly attenuated the symptoms of pulmonary fibrosis induced by BLM in a murine model. Our findings also indicated that CEP treatment markedly reduced the expression of fibrosis markers, including TGF-β1, collagen I, fibronectin and α-SMA, in the mouse lung. Furthermore, in vitro studies demonstrated that CEP attenuated pulmonary fibrosis by inhibiting fibroblast activation through modulating macrophage M2 polarization and reducing TGF-β1 expression. Conclusions: This study demonstrated the potential and efficacy of CEP in the treatment of pulmonary fibrosis. In particular, this study revealed a novel mechanism of CEP in inhibiting fibroblast activation by regulating macrophage M2 polarization and reducing the expression of fibrosis-associated factors. Our findings open a new direction for future research into the treatment of pulmonary fibrosis. [ABSTRACT FROM AUTHOR]

Pulmonary fibrosis (PF) is an interstitial lung disease characterized by inflammation and fibrotic changes, with an unknown cause. In the early stages of PF, severe inflammation leads to the destruction of lung tissue, followed by upregulation of fibrotic factors like Transforming growth factor-β (TGF-β) and connective tissue growth factor (CTGF), which disrupt normal tissue repair. Geniposide, a natural iridoid glycoside primarily derived from the fruits of Gardenia jasminoides Ellis, possesses various pharmacological activities, including liver protection, choleretic effects, and anti-inflammatory properties. In this study, we investigated the effects of Geniposide on chronic inflammation and fibrosis induced by bleomycin (BLM) in mice with pulmonary fibrosis (PF). PF was induced by intratracheal instillation of bleomycin, and Geniposide(100/50/25mg•kg-1) was orally administered to the mice once a day until euthanasia(14 day/28 day). The Raw264.7 cell inflammation induced by LPS was used to evaluate the effect of Geniposide on the activation of macrophage. Our results demonstrated that Geniposide reduced lung coefficients, decreased the content of Hydroxyproline, and improved pathological changes in lung tissue. It also reduced the number of inflammatory cells and levels of pro-inflammatory cytokines in bronchoalveolar lavage fluid (BALF) of bleomycin-induced PF mice. At the molecular level, Geniposide significantly down-regulated the expression of TGF-β1, Smad2/3, p38, and CTGF in lung tissues of PF mice induced by bleomycin. Molecular docking results revealed that Geniposide exhibited good binding activity with TGF-β1, Smad2, Smad3, and p38. In vitro study showed Geniposide directly inhibited the activation of macrophage induced by LPS. In conclusion, our findings suggest that Geniposide can ameliorate bleomycin-induced pulmonary fibrosis in mice by inhibiting the TGF-β/Smad and p38MAPK signaling pathways. [ABSTRACT FROM AUTHOR]

Intervertebral disc degeneration (IDD) is a major cause of discogenic pain, and is attributed to the dysfunction of nucleus pulposus, annulus fibrosus, and cartilaginous endplate (CEP). Osteopontin (OPN), a glycoprotein, is highly expressed in the CEP. However, little is known on how OPN regulates CEP homeostasis and degeneration, contributing to the pathogenesis of IDD. Here, we investigate the roles of OPN in CEP degeneration in a mouse IDD model induced by lumbar spine instability and its impact on the degeneration of endplate chondrocytes (EPCs) under pathological conditions. OPN is mainly expressed in the CEP and decreases with degeneration in mice and human patients with severe IDD. Conditional Spp1 knockout in EPCs of adult mice enhances age-related CEP degeneration and accelerates CEP remodeling during IDD. Mechanistically, OPN deficiency increases CCL2 and CCL5 production in EPCs to recruit macrophages and enhances the activation of NLRP3 inflammasome and NF-κB signaling by facilitating assembly of IRAK1-TRAF6 complex, deteriorating CEP degeneration in a spatiotemporal pattern. More importantly, pharmacological inhibition of the NF-κB/NLRP3 axis attenuates CEP degeneration in OPN-deficient IDD mice. Overall, this study highlights the importance of OPN in maintaining CEP and disc homeostasis, and proposes a promising therapeutic strategy for IDD by targeting the NF-κB/NLRP3 axis. [ABSTRACT FROM AUTHOR]

The cytokine IFNγ is a principal effector of macrophage activation and immune resistance to mycobacterial infection; however, pathogenic mycobacteria are capable of surviving in IFNγ-activated macrophages by largely unknown mechanisms. In this study, we find that pathogenic mycobacteria, including M. bovis BCG and M. tuberculosis can sense IFNγ to promote their proliferative activity and virulence phenotype. Moreover, interaction with the host intracellular environment increases the susceptibility of mycobacteria to IFNγ through upregulating expression of mmpL10, a mycobacterial IFNγ receptor, thereby facilitating IFNγ-dependent survival and growth of mycobacteria in macrophages. Transmission electron microscopy analysis reveals that IFNγ triggers the secretion of extracellular vesicles, an essential virulence strategy of intracellular mycobacteria, while proteomics identifies numerous pivotal IFNγ-induced effectors required for mycobacterial infection in macrophages. Our study suggests that sensing host IFNγ is a crucial virulence mechanism used by pathogenic mycobacteria to survive and proliferate inside macrophages. [ABSTRACT FROM AUTHOR]

Many anti-tumor effects of group-specific component-derived macrophage-activating factors (GcMAFs) have been reported; however, the specific mechanisms remain unclear. Controlling tumor-associated macrophages (TAMs) in the tumor microenvironment is essential for cancer treatment. This study assessed the role of GcMAF in macrophage activation, elucidated the mechanisms by which it exerts its anti-tumor effects, and determined its effects on TAMs in the tumor microenvironment. GcMAF-stimulated RAW264.7 macrophages and EMT6 breast tumor cells were co-cultured in a 0.4 µm pore cell culture insert, and gene and protein expression and cell viability were evaluated. DNA microarray analysis of GcMAF-stimulated RAW264.7 cells was conducted. The induction of M2 RAW264.7 cells by interleukin (IL)-4 and IL-13 was analyzed. GcMAF stimulation increased the tumor necrosis factor-α and inducible nitric oxide synthase mRNA and protein levels in RAW264.7 cells but decreased the viability of co-cultured EMT6 cells. Although the details of the receptor or signal pathway of GcMAF are still unclear, these results were confirmed in the M2 RAW264.7 cells, suggesting that GcMAF exerts anti-tumor effects by inducing the differentiation of macrophages into the M1 type and reprogramming M2 macrophages to the M1 type. The anti-tumor activity of GcMAF via M2-to-M1 macrophage reprogramming could aid in developing novel cancer immunotherapies. [ABSTRACT FROM AUTHOR]

Background: Uncontrolled inflammation caused by macrophages and monocytes plays a crucial role in worsening acute respiratory distress syndrome (ARDS). Previous studies have highlighted the importance of IFIH1 in regulating macrophage polarisation in ARDS triggered by pneumonia. However, the mechanisms by which IFIH1 is activated in ARDS remain unclear. Methods: In this study, we utilised multiomics sequencing and molecular interaction experiments to explore the molecular mechanisms underlying IFIH1 activation in ARDS. Through the use of conditional gene knockout mice and primary cells, we demonstrated the significant role of these mechanisms in the development of ARDS. Additionally, we validated the associations between these mechanisms and ARDS by quantitative PCR analysis of CD14+ cells obtained from the peripheral blood of 140 ARDS patients. Results: Our investigation revealed that lipopolysaccharide, a critical component derived from Gram‐negative bacteria, activated IFIH1 by upregulating a novel transcript known as IFIH1‐binding RNA1 (IBR1) in monocytes and macrophages. Specifically, as an endogenous double‐stranded RNA, IBR1 bind to the helicase domain of IFIH1 because of its unique double‐stranded structure. Deletion of IBR1 significantly reduced the activation of IFIH1, M1 polarisation of macrophages, and inflammatory lung injury in ARDS. Moreover, IBR1 directly induced M1 polarisation of macrophages and ARDS, whereas deletion of IFIH1 inhibited IBR1‐induced macrophage M1 polarisation and inflammatory lung injury. Importantly, we observed a notable increase in IBR1 expression in ARDS patients with pneumonia caused by Gram‐negative bacteria. Furthermore, we demonstrated that the delivery of IFIH1 mutants through exosomes effectively counteracted IBR1, thereby reducing pulmonary inflammation and alleviating lung injury. Conclusions: This study revealed a novel mechanism involving IBR1, an endogenous double‐stranded RNA (dsRNA) that binds to IFIH1, shedding light on the complex process of macrophage polarisation in ARDS. The administration of IFIH1 variants has the potential to eliminate pulmonary dsRNA and alleviate inflammatory lung injury in ARDS. Highlights: In monocytes and macrophages, the endogenous double‐stranded RNA, IFIH1‐binding RNA 1 (IBR1), binds to the helicase domain of IFIH1 because of its unique double‐stranded structure.IBR1 plays a significant role in macrophage polarisation and the development of acute respiratory distress syndrome (ARDS) induced by Gram‐negative bacteria or lipopolysaccharide (LPS).Administration of IFIH1 variants has potential for eliminating pulmonary IBR1 and reducing inflammatory lung injury in ARDS patients. [ABSTRACT FROM AUTHOR]

Enteroviruses are a genus of small RNA viruses that are responsible for approximately one billion global infections annually. These infections range in severity from the common cold and flu-like symptoms to more severe diseases, such as viral myocarditis, pancreatitis, and neurological disorders, that continue to pose a global health challenge with limited therapeutic strategies currently available. In the current study, we sought to understand the interaction between coxsackievirus B3 (CVB3), which is a model enterovirus, and macrophage cells, as there is limited understanding of how this virus interacts with macrophage innate immune cells. Our study demonstrated that CVB3 can robustly activate macrophages without apparent viral replication in these cells. We also showed that myeloid cells lacked the viral entry receptor coxsackievirus and adenovirus receptor (CAR). However, the expression of exogenous CAR in RAW264.7 macrophages was unable to overcome the viral replication deficit. Interestingly, the CAR expression was associated with altered inflammatory responses during prolonged infection. Additionally, we identified the autophagy protein LC3 as a novel stimulus for macrophage activation. These findings provide new insights into the mechanisms of CVB3-induced macrophage activation and its implications for viral pathogenesis. [ABSTRACT FROM AUTHOR]