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In the pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, epithelial populations in the distal lung expressing Angiotensin-converting enzyme 2 (ACE2) are infrequent, and therefore, the model of viral expansion and immune cell engagement remains incompletely understood. Using human lungs to investigate early host-viral pathogenesis, we found that SARS-CoV-2 had a rapid and specific tropism for myeloid populations. Human alveolar macrophages (AMs) reliably expressed ACE2 allowing both spike-ACE2-dependent viral entry and infection. In contrast to Influenza A virus, SARS-CoV-2 infection of AMs was productive, amplifying viral titers. While AMs generated new viruses, the interferon responses to SARS-CoV-2 were muted, hiding the viral dissemination from specific antiviral immune responses. The reliable and veiled viral depot in myeloid cells in the very early phases of SARS-CoV-2 infection of human lungs enables viral expansion in the distal lung and potentially licenses subsequent immune pathologies.

Professional phagocytes like neutrophils and macrophages tightly control what they consume, how much they consume, and when they move after cargo uptake. We show that plasma membrane abundance is a key arbiter of these cellular behaviors. Neutrophils and macrophages lacking the G protein subunit Gβ4 exhibited profound plasma membrane expansion, accompanied by marked reduction in plasma membrane tension. These biophysical changes promoted the phagocytosis of bacteria, fungus, apoptotic corpses, and cancer cells. We also found that Gβ4-deficient neutrophils are defective in the normal inhibition of migration following cargo uptake. Sphingolipid synthesis played a central role in these phenotypes by driving plasma membrane accumulation in cells lacking Gβ4. In Gβ4 knockout mice, neutrophils not only exhibited enhanced phagocytosis of inhaled fungal conidia in the lung but also increased trafficking of engulfed pathogens to other organs. Together, these results reveal an unexpected, biophysical control mechanism central to myeloid functional decision-making.

IntroductionMaternal intervillous monocytes (MIMs) and fetal Hofbauer cells (HBCs) are myeloid-derived immune cells at the maternal-fetal interface. Maternal reproductive history is associated with differential risk of pregnancy complications. The molecular phenotypes and roles of these distinct monocyte/macrophage populations and the influence of gravidity on these phenotypes has not been systematically investigated.MethodsHere, we used RNA sequencing to study the transcriptional profiles of MIMs and HBCs in normal term pregnancies.ResultsOur analyses revealed distinct transcriptomes of MIMs and HBCs. Genes involved in differentiation and cell organization pathways were more highly expressed in MIMs vs. HBCs. In contrast, HBCs had higher expression of genes involved in inflammatory responses and cell surface receptor signaling. Maternal gravidity influenced monocyte programming, as expression of pro-inflammatory molecules was significantly higher in MIMs from multigravidae compared to primigravidae. In HBCs, multigravidae displayed enrichment of gene pathways involved in cell-cell signaling and differentiation.DiscussionOur results demonstrated that MIMs and HBCs have highly divergent transcriptional signatures, reflecting their distinct origins, locations, functions, and roles in inflammatory responses. Furthermore, maternal gravidity influences the gene signatures of MIMs and HBCs, potentially modulating the interplay between tolerance and trained immunity. The phenomenon of reproductive immune memory may play a novel role in the differential susceptibility of primigravidae to pregnancy complications.

Background: Alzheimer's disease (AD) is associated with gradual memory loss and anxiety which affects ~75% of AD patients. This study investigated whether AD‐associated anxiety correlated with modulation of extrasynaptic δ‐subunit‐containing GABAA receptors (δ‐GABAARs) in experimental mouse models of AD. Experimental approach: We combined behavioural experimental paradigms to measure cognition performance, and anxiety with neuroanatomy and molecular biology, using familial knock‐in (KI) mouse models of AD that harbour β‐amyloid (Aβ) precursor protein App (AppNL‐F) with or without humanized microtubule‐associated protein tau (MAPT), age‐matched to wild‐type control mice at three different age windows. Results: AppNL‐F KI and AppNL‐F/MAPT AD models showed a similar magnitude of cognitive decline and elevated magnitude of anxiety correlated with neuroinflammatory hallmarks, including triggering receptor expressed on myeloid cells 2 (TREM2), reactive astrocytes and activated microglia consistent with accumulation of Aβ, tau and down‐regulation of Wnt/β‐catenin signalling compared to aged‐matched WT controls. In both the CA1 region of the hippocampus and dentate gyrus, there was an age‐dependent decline in the expression of δ‐GABAARs selectively expressed in parvalbumin (PV)‐expressing interneurons, encapsulated by perineuronal nets (PNNs) in the AD mouse models compared to WT mice. In vivo positive allosteric modulation of the δ‐GABAARs, using a δ‐selective‐compound DS2, decreased the level of anxiety in the AD mouse models, which was correlated with reduced hallmarks of neuroinflammation, and 'normalisation' of the expression of δ‐GABAARs. Conclusions: Our data show that the δ‐GABAARs could potentially be targeted for alleviating symptoms of anxiety, which would greatly improve the quality of life of AD individuals. [ABSTRACT FROM AUTHOR]

Myeloid cells are pivotal in the inflammatory and remodeling phases of fracture repair. Here, we investigate the effect of periostin expressed by myeloid cells on bone regeneration in a monocortical tibial defect (MTD) model. In this study, we show that periostin is expressed by periosteal myeloid cells, primarily the M2 macrophages during bone regeneration. Knockout of periostin in myeloid cells reduces cortical bone thickness, disrupts trabecular bone connectivity, impairs repair impairment, and hinders M2 macrophage polarization. Mechanical stimulation is a regulator of periostin in macrophages. By activating transforming growth factor-β (TGF-β), it increases periostin expression in macrophages and induces M2 polarization. This mechanosensitive effect also reverses the delayed bone repair induced by periostin deficiency in myeloid cells by strengthening the angiogenesis-osteogenesis coupling. In addition, transplantation of mechanically conditioned macrophages into the periosteum over a bone defect results in substantially enhanced repair, confirming the critical role of macrophage-secreted periostin in bone repair. In summary, our findings suggest that mechanical stimulation regulates periostin expression and promotes M2 macrophage polarization, highlighting the potential of mechanically conditioned macrophages as a therapeutic strategy for enhancing bone repair. [ABSTRACT FROM AUTHOR]

Background: Ischemic stroke (IS) is a global health issue linked to lipid metabolism and immune cell responses. This study uses Mendelian randomization (MR) to identify genetic risk factors for IS subtypes using comprehensive genetic data from lipidomic and immune cell profiles. Methods: We assessed genetic susceptibility to IS across 179 lipids and 731 immune cell phenotypes using instrumental variables (IVs) from recent genome- wide association studies. A two-sample MR approach evaluated correlations, and a two-step MR mediation analysis explored the role of immune cell phenotypes in the lipid-IS pathway. Sensitivity analyses, including MR-Egger and Cochran Q tests, ensured robust results. Results: Genetic IVs for 162 lipids and 614 immune cell phenotypes were identified. Significant genetic causality was found between 35 lipids and large artery stroke (LAS), with 12 as risk factors (sterol esters, phosphatidylcholines, phosphatidylethanolamines) and 23 as protective factors (phosphatidylcholines, phosphatidylethanolamines, phosphatidylinositols). For small vessel stroke (SVS), 8 as risk factors (sterol esters, phosphatidylcholines), and 2 as protective factors (phosphatidylinositol, sphingomyelin). For cardioembolic stroke (CS), 2 as risk factors, and 4 as protective factors. Mediation analysis revealed that CCR2 on granulocytes, CD11c on CD62L+ myeloid dendritic cells, and FSC-A on granulocytes mediated the lipid-immune cell-LAS pathway, while CD4 on activated CD4 regulatory T cells and CD4 on activated & secreting CD4 regulatory T cells mediated the lipid-immune cell-SVS pathway. Conclusion: This study identifies genetic links between specific lipids and IS subtypes, highlights immune cells’ role in IS risk and mediation, suggests new therapeutic targets, and uncovers IS genetic drivers. [ABSTRACT FROM AUTHOR]

This document examines the clonal dynamics of advanced systemic mastocytosis (AdvSM) and associated acute myeloid leukemia (ASM-AHN) in patients receiving avapritinib therapy. The study utilized single-cell RNA sequencing and whole-genome sequencing to analyze genetic and cellular changes before and after treatment. The findings indicate that avapritinib targets different subclones and cellular compartments based on the position of the KITD816V driver mutation. The study suggests that a combination of avapritinib and hypomethylating agents may be effective in addressing the entire malignant network and promoting normal hematopoiesis in AdvSM. [Extracted from the article]

Acute myeloid leukemia (AML) is a hostile hematological malignancy under great danger of relapse and poor long-term survival rates, despite recent therapeutic advancements. To deal with this unfulfilled clinical necessity, innovative cellbased immunotherapies have surfaced as promising approaches to improve antitumor immunity and enhance patient outcomes. In this comprehensive review, we provide a detailed examination of the latest developments in cell-based immunotherapies for AML, including chimeric antigen receptor (CAR) T-cell therapy, T-cell receptor (TCR)-engineered T-cell therapy, and natural killer (NK) cell-based therapies. We critically evaluate the unique mechanisms of action, current challenges, and evolving strategies to improve the efficacy and safety of these modalities. The review emphasizes how promising these cuttingedge immune-based strategies are in overcoming the inherent complexities and heterogeneity of AML. We discuss the identification of optimal target antigens, the importance of mitigating on-target/off-tumor toxicity, and the need to enhance the persistence and functionality of engineered immune effector cells. All things considered, this review offers a thorough overview of the rapidly evolving field of cell-based immunotherapy for AML, underscoring the significant progress made and the ongoing efforts to translate these innovative approaches into more effective and durable treatments for this devastating disease. [ABSTRACT FROM AUTHOR]

Background: Dysregulated innate immune responses underlie multiple inflammatory diseases, but clinical translation of preclinical innate immunity research in mice is hampered by the difficulty of studying human inflammatory reactions in an in vivo context. We therefore sought to establish in vivo human inflammatory responses in NSG-QUAD mice that express four human myelopoiesis transgenes to improve engraftment of a human innate immune system. Methods: We reconstituted NSG-QUAD mice with human hematopoietic stem and progenitor cells (HSPCs), after which we evaluated human myeloid cell development and subsequent human responses to systemic and local lipopolysaccharide (LPS) challenges. Results: NSG-QUAD mice already displayed engraftment of human monocytes, dendritic cells and granulocytes in peripheral blood, spleen and liver at 6 weeks after HSPC reconstitution, in which both classical, intermediate and non-classical monocytes were present. These huNSG-QUAD mice responded to intraperitoneal and intranasal LPS challenges with production of NF-kBdependent human cytokines, a human type I interferon response, as well as inflammasome-mediated production of human IL-1b and IL-18. The latter were specifically abrogated by the NLRP3 inhibitor MCC950, while LPS-induced human monocyte death was not altered. Besides providing proof-of-principle for small molecule testing of human inflammatory reactions in huNSG-QUAD mice, this observation suggests that LPS-induced in vivo release of human NLRP3 inflammasome-generated cytokines occurs in a cell death-independent manner. Conclusion: HuNSG-QUAD mice are competent for the NF-kB, interferon and inflammasome effectors of human innate immunity, and can thus be utilized to investigate signaling mechanisms and pharmacological targeting of human inflammatory responses in an in vivo setting. [ABSTRACT FROM AUTHOR]

Acute myeloid leukemia (AML) is a malignant tumor of the hematological system. Because of its characteristics of recurrence, refractory and chemoresistance, new therapeutic targets need to be identified. Adhesion and proliferation are characteristics of AML cells, and critical steps in inducing chemotherapy resistance. In this study, we reported that UNC5B inhibits AML cell bone marrow adhesion, inhibits AML cell proliferation and increases sensitivity to chemotherapy. Mechanistically, RNA sequencing (RNA-seq) and experimental results revealed that overexpression of UNC5B inhibits adhesion and proliferation signaling pathways and inhibits the expression of MPZL1, CLDN23, IGF2 and WNT7B. In conclusion, our findings suggest that UNC5B serves as a prognostic indicator and a potential therapeutic target for AML. [ABSTRACT FROM AUTHOR]

The precise neurophysiological changes prompted by meningeal lymphatic dysfunction remain unclear. Here, we showed that inducing meningeal lymphatic vessel ablation in adult mice led to gene expression changes in glial cells, followed by reductions in mature oligodendrocyte numbers and specific lipid species in the brain. These phenomena were accompanied by altered meningeal adaptive immunity and brain myeloid cell activation. During brain remyelination, meningeal lymphatic dysfunction provoked a state of immunosuppression that contributed to delayed spontaneous oligodendrocyte replenishment and axonal loss. The deficiencies in mature oligodendrocytes and neuroinflammation due to impaired meningeal lymphatic function were solely recapitulated in immunocompetent mice. Patients diagnosed with multiple sclerosis presented reduced vascular endothelial growth factor C in the cerebrospinal fluid, particularly shortly after clinical relapses, possibly indicative of poor meningeal lymphatic function. These data demonstrate that meningeal lymphatics regulate oligodendrocyte function and brain myelination, which might have implications for human demyelinating diseases. [Display omitted] • Meningeal lymphatic vessel ablation causes loss of mature oligodendrocytes • Demyelination due to meningeal lymphatic ablation relies on a competent immune system • Meningeal lymphatic dysfunction affects brain remyelination and aggravates axonal loss • Multiple sclerosis patients have decreased VEGF-C levels in their cerebrospinal fluid The neurophysiological processes regulated by meningeal lymphatic function remain unclear. das Neves et al. showed that meningeal lymphatic dysfunction leads to loss of mature oligodendrocytes and demyelination in the brain. Defective meningeal lymphatics incited a neuroinflammatory environment that limited oligodendrocyte replenishment after a demyelinating insult. This work might have therapeutic implications for the central nervous system demyelinating autoimmune disorders. [ABSTRACT FROM AUTHOR]

Immunological priming—in the context of either prior infection or vaccination—elicits protective responses against subsequent Mycobacterium tuberculosis (Mtb) infection. However, the changes that occur in the lung cellular milieu post-primary Mtb infection and their contributions to protection upon reinfection remain poorly understood. Using clinical and microbiological endpoints in a non-human primate reinfection model, we demonstrated that prior Mtb infection elicited a long-lasting protective response against subsequent Mtb exposure and was CD4+ T cell dependent. By analyzing data from primary infection, reinfection, and reinfection-CD4+ T cell-depleted granulomas, we found that the presence of CD4+ T cells during reinfection resulted in a less inflammatory lung milieu characterized by reprogrammed CD8+ T cells, reduced neutrophilia, and blunted type 1 immune signaling among myeloid cells. These results open avenues for developing vaccines and therapeutics that not only target lymphocytes but also modulate innate immune cells to limit tuberculosis (TB) disease. [Display omitted] • CD4+ T cells are required for protection against Mtb reinfection in macaques • Mtb reinfection promotes immuno-modulatory CD8+ T cell-biased immunity • Myeloid-derived cells downregulate gene networks implicated in TB susceptibility • Self-reinforcing cellular circuits balance host immunity in reinfection granulomas Th1 CD4+ T cells mediate protective anti- Mtb immunity across biological systems and organisms. Bromley, Ganchua, et al. demonstrate that CD4+ T cells regulate immune tone in TB granulomas and are necessary for immune recall and protection against reinfection. Following reinfection, CD4+ T cells facilitate the development of a growth restrictive niche via the induction of immuno-modulatory genes and cellular interaction networks. [ABSTRACT FROM AUTHOR]

Background: Radiotherapy has both immunostimulant and immunosuppressive effects, particularly in radiation-induced lymphopenia. Proton therapy has demonstrated potential in mitigating this lymphopenia, yet the mechanisms by which different types of radiation affect the immune system function are not fully characterized. The Circulating Immunes Cells, Cytokines and Brain Radiotherapy (CYRAD) trial aims to compare the effects of postoperative X-ray and proton radiotherapy on circulating leukocyte subpopulations and cytokine levels in patients with head and neck (CNS and ear nose throat) cancer. Methods: CYRAD is a prospective, non-randomized, single-center non interventional study assessing changes in the circulating leukocyte subpopulations and cytokine levels in head and neck cancer patients receiving X-ray or proton radiotherapy following tumor resection. Dosimetry parameters, including dose deposited to organs-at-risk such as the blood and cervical lymph nodes, are computed. Participants undergo 29 to 35 radiotherapy sessions over 40 to 50 days, followed by a 3-month follow-up. Blood samples are collected before starting radiotherapy (baseline), before the 11th (D15) and 30th sessions (D40), and three months after completing radiotherapy. The study will be conducted with 40 patients, in 2 groups of 20 patients per modality of radiotherapy (proton therapy and photon therapy). Statistical analyses will assess the absolute and relative relationship between variations (depletion, recovery) in immune cells, biomarkers, dosimetry parameters and early outcomes. Discussion: Previous research has primarily focused on radiation-induced lymphopenia, paying less attention to the specific impacts of radiation on different lymphoid and myeloid cell types. Early studies indicate that X-ray and proton irradiation may lead to divergent outcomes in leukocyte subpopulations within the bloodstream. Based on these preliminary findings, this study aims to refine our understanding of how proton therapy can better preserve immune function in postoperative (macroscopic tumor-free) head and neck cancer patients, potentially improving treatment outcomes. Protocol version: Version 2.1 dated from January 18, 2023. Trial registration: The CYRAD trial is registered from October 19, 2021, at the US National Library of Medicine, ClinicalTrials.gov ID NCT05082961. [ABSTRACT FROM AUTHOR]

The pathophysiology of immune checkpoint inhibitor-related pneumonitis remains incompletely understood. We conducted single-cell and T-cell receptor transcriptomic sequencing on the bronchoalveolar lavage fluid from five patients with grade ≥2 immune checkpoint inhibitor-related pneumonitis. Our analyses revealed a prominent enrichment of T cells in the bronchoalveolar lavage fluid of patients with immune checkpoint inhibitor-related pneumonitis. Within the CD4 + T cell subset, Tfh-like T cells were highly enriched and exhibited signatures associated with inflammation and clonal expansion. Regulatory T cells were also enriched and displayed enhanced inhibitory functions. Within the CD8 + T-cell subset, effector memory/tissue-resident memory T cells with an elevated cytotoxic phenotype were highly infiltrated. Among myeloid cells, alveolar macrophages were depleted, while pro-inflammatory intermediate monocytes were elevated. Dendritic cells demonstrated enhanced antigen presentation capabilities. Cytokines CXCR4, CXCL13, TNF-α, IFN-α, IFN-γ, and TWEAK were elevated. Through a comprehensive single-cell analysis, we depicted the landscape of immune checkpoint inhibitor-related pneumonitis. [ABSTRACT FROM AUTHOR]

Emphysema in patients with chronic obstructive pulmonary disease (COPD) is characterized by progressive inflammation. Preclinical studies suggest that lung volume reduction surgery (LVRS) and mesenchymal stromal cell (MSC) treatment dampen inflammation. We investigated the effects of bone marrow-derived MSC (BM-MSC) and LVRS on circulating and pulmonary immune cell profiles in emphysema patients using mass cytometry. Blood and resected lung tissue were collected at the first LVRS (L1). Following 6–10 weeks of recovery, patients received a placebo or intravenous administration of 2 × 106 cells/kg bodyweight BM-MSC (n = 5 and n = 9, resp.) in week 3 and 4 before the second LVRS (L2), where blood and lung tissue were collected. Irrespective of BM-MSC or placebo treatment, proportions of circulating lymphocytes including central memory CD4 regulatory, effector memory CD8 and γδ T cells were higher, whereas myeloid cell percentages were lower in L2 compared to L1. In resected lung tissue, proportions of Treg (p = 0.0067) and anti-inflammatory CD163− macrophages (p = 0.0001) were increased in L2 compared to L1, while proportions of pro-inflammatory CD163+ macrophages were decreased (p = 0.0004). There were no effects of BM-MSC treatment on immune profiles in emphysema patients. However, we observed alterations in the circulating and pulmonary immune cells upon LVRS, suggesting the induction of anti-inflammatory responses potentially needed for repair processes. [ABSTRACT FROM AUTHOR]

Traumatic brain injury (TBI) can cause major disability and increases the risk of neurodegeneration. Post-TBI, there is infiltration of peripheral myeloid and lymphoid cells; there is limited information on the peripheral immune response post-TBI in the immature brain—where injury may interfere with neurodevelopment. We carried out two injury types in juvenile mice: invasive TBI with a controlled cortical impact (CCI) and repetitive mild TBI (rmTBI) using weight drop injury and analysed the response at 5- and 35-days post-injury. In the two models, we detected the brain infiltration of immune cells (e.g., neutrophils, monocytes, dendritic cells, CD4+ T cells, and NK cells). There were increases in macrophages, neutrophils, and dendritic cells in the spleen, increases in dendritic cells in blood, and increases in CD8+ T cells and B cells in lymph nodes. These results indicate a complex peripheral immune response post-TBI in the immature brain, with differences between an invasive injury and a repetitive mild injury. [ABSTRACT FROM AUTHOR]

Protein tyrosine phosphatases (PTPs) play central roles in the regulation of cell signaling, organismal development, cellular differentiation and proliferation, and cancer. In the immune system, PTPs regulate the activation, differentiation and effector function of lymphocytes and myeloid cells whilst single-nucleotide polymorphisms (SNPs) in PTP-encoding genes have been identified as risk factors for the development of autoimmunity. In this review we describe the roles for PTP nonreceptor type 22 (PTPN22) in the regulation of T lymphocyte signaling and activation in autoimmunity, infection and cancer. We summarize recent progress in our understanding of the regulation of PTPN22 activity, the impact of autoimmune disease-associated PTPN22 SNPs on T cell responses and describe approaches to harness PTPN22 as a target to improve T cell-based immunotherapies in cancer. [ABSTRACT FROM AUTHOR]

Apoptosis, inflammation, and wound healing are critical pathophysiological events associated with various liver diseases. Currently, there is a lack of in vivo approaches to study hepatocyte apoptosis-induced liver injury and repair. To address this critical knowledge gap, we developed a unique genetically modified mouse model, namely, 3-Transgene (Tg) with inducible Hepatocyte-Specific Apoptosis Phenotype (3xTg-iHAP) in this study. The 3xTg-iHAP mice possess three transgenes including Alb-Cre, Rosa26-rtTA, and tetO-Fasl on a B6 background. These mice are phenotypically normal, viable, and fertile. After subcutaneous administration of a single dose of doxycycline (5 mg/kg, Dox) to 3xTg-iHAP mice, we observed a complete histological spectrum of sterile liver wound-healing responses: asymptomatic hepatocyte apoptosis at 8 h, necrotic liver injury and sterile inflammation at 48 h, followed by hepatocyte mitosis and regeneration within 7 days. During the injury phase, the mice exhibited an increase in the biomarkers of alanine aminotransferase (ALT), chemokine (C-X-C motif) ligand 1 (CXCL1), and IL-6 in peripheral blood, as well as α-smooth muscle actin (α-SMA) protein in liver tissues. Conversely, the mice displayed a decrease in these markers in the recovery phase. Remarkably, this model shows that the sterile liver injury following elevated hepatocyte apoptosis is associated with an increase in myeloid cells in the liver. Within 7 days post-Dox administration, the liver of Dox-treated 3xTg-iHAP mice displays a normal histological structure, indicating the completion of wound healing. Together, we established a novel mouse model of injury and regeneration induced by hepatocyte apoptosis. This tool provides a robust in vivo platform for studying the pathophysiology of sterile liver inflammation, regeneration, and new therapeutic interventions for liver diseases. NEW & NOTEWORTHY: Bu et al. present a triple-transgenic mouse model, namely, 3xTg-iHAP mice that are engineered to explore hepatocyte apoptosis-triggered sterile liver injury and regeneration. This model demonstrates a full spectrum of liver wound-healing responses from asymptomatic apoptosis to injury, myeloid cell-dominant sterile inflammation, and repair after induction of hepatocyte-specific apoptosis. The robust nature of this model makes it an invaluable in vivo tool for studying sterile liver inflammation, regeneration, and new therapeutic strategies. [ABSTRACT FROM AUTHOR]

This document discusses the limitations of cancer immunotherapy using PD-1/PD-L1 immune checkpoint blockade (ICBs) and the importance of understanding the tumor immune microenvironment (TIME). The document focuses on the role of tumor-associated macrophages (TAMs) in solid tumors and their impact on immunotherapy efficacy. It highlights the potential of targeting the immune receptor SIRPA on TAMs as a promising strategy for cancer immunotherapy. The document also explores the role of TAMs in glioblastoma multiforme (GBM) and suggests targeting the immune checkpoint Siglec-9 on TAMs as a potential treatment for GBM. The overall goal is to reprogram the tumor immune microenvironment to enhance the effectiveness of immunotherapy. [Extracted from the article]

Background: Immunotherapies, including chimeric antigen receptor (CAR) T cells and bispecific antibodies (BsAbs), encounter several challenges in the management of acute myeloid leukemia (AML), including limited persistence of these treatments, antigen loss and resistance of leukemia stem cells (LSCs) to therapy. Methods: Here, we proposed a novel dual-targeting approach utilizing engineered anti-IL10R CAR-T cells to secrete bispecific antibodies targeting CD33. This innovative strategy, rooted in our previous research which established a connection between IL-10 and the stemness of AML cells, designed to improve targeting efficiency and eradicate both LSCs and AML blasts. Results: We first demonstrated the superior efficacy of this synergistic approach in eliminating AML cell lines and primary cells expressing different levels of the target antigens, even in cases of low CD33 or IL10R expression. Furthermore, the IL10R CAR-T cells that secret anti-CD33 bsAbs (CAR.BsAb-T), exhibited an enhanced activation and induction of cytotoxicity not only in IL10R CAR-T cells but also in bystander T cells, thereby more effectively targeting CD33-positive tumor cells. Our in vivo experiments provided additional evidence that CAR.BsAb-T cells could efficiently redirect T cells, reduce tumor burden, and demonstrate no significant toxicity. Additionally, delivering bsAbs locally to the tumor sites through this strategy helps mitigate the pharmacokinetic challenges typically associated with the rapid clearance of prototypical bsAbs. Conclusions: Overall, the engineering of a single-vector targeting IL10R CAR, which subsequently secretes CD33-targeted bsAb, addresses the issue of immune escape due to the heterogeneous expression of IL10R and CD33, and represents a promising progress in AML therapy aimed at improving treatment outcomes. [ABSTRACT FROM AUTHOR]

Purpose: Acquired resistance to immune checkpoint blockers (ICBs) is a major barrier in cancer treatment, emphasizing the need for innovative strategies. Dectin-1 (gene Clec7a) is a C-type lectin receptor best known for its ability to recognize β-glucan-rich structures in fungal cell walls. While Dectin-1 is expressed in myeloid cells and tumor cells, its significance in cancer remains the subject of controversy. Methods: Using Celc7a-/- mice and curdlan administration to stimulate Dectin-1 signaling, we explored its impact. VISTA KO mice were employed to assess VISTA's role, and bulk RNAseq analyzed curdlan effects on neutrophils. Results: Our findings reveal myeloid cells as primary Dectin-1 expressing cells in the tumor microenvironment (TME), displaying an activated phenotype. Strong Dectin-1 co-expression/co-localization with VISTA and PD-L1 in TME myeloid cells was observed. While Dectin-1 deletion lacked protective effects, curdlan stimulation significantly curtailed B16-F10 tumor progression. RNAseq and pathway analyses supported curdlan's role in triggering a cascade of events leading to increased production of pro-inflammatory mediators, potentially resulting in the recruitment and activation of immune cells. Moreover, we identified a heterogeneous subset of Dectin-1+ effector T cells in the TME. Similar to mice, human myeloid cells are the prominent cells expressing Dectin-1 in cancer patients. Conclusion: Our study proposes Dectin-1 as a potential adjunctive target with ICBs, orchestrating a comprehensive engagement of innate and adaptive immune responses in melanoma. This innovative approach holds promise for overcoming acquired resistance to ICBs in cancer treatment, offering avenues for further exploration and development. [ABSTRACT FROM AUTHOR]

Purpose: The overall survival rate for metastatic osteosarcoma hovers around 20%. Responses to second-line chemotherapy, targeted therapies, and immunotherapies have demonstrated limited efficacy in metastatic osteosarcoma. Our objective is to validate differentially expressed genes and signaling pathways between non-metastatic and metastatic osteosarcoma, employing single-cell RNA sequencing (scRNA-seq) and additional functional investigations. We aim to enhance comprehension of metastatic mechanisms and potentially unveil a therapeutic target. Methods: scRNA-seq was performed on two primary osteosarcoma lesions (1 non-metastatic and 1 metastatic). Seurat package facilitated dimensionality reduction and cluster identification. Copy number variation (CNV) was predicted using InferCNV. CellChat characterized ligand-receptor-based intercellular communication networks. Differentially expressed genes underwent GO function enrichment analysis and GSEA. Validation was achieved through the GSE152048 dataset, which identified PDGFD-PDGFRB as a common ligand-receptor pair with significant contribution. Immunohistochemistry assessed PDGFD and PDGFRB expression, while multicolor immunofluorescence and flow cytometry provided insight into spatial relationships and the tumor immune microenvironment. Kaplan-Meier survival analysis compared metastasis-free survival and overall survival between high and low levels of PDGFD and PDGFRB. Manipulation of PDGFD expression in primary osteosarcoma cells examined invasion abilities and related markers. Results: Ten clusters encompassing osteoblasts, osteoclasts, osteocytes, fibroblasts, pericytes, endothelial cells, myeloid cells, T cells, B cells, and proliferating cells were identified. Osteoblasts, osteoclasts, and osteocytes exhibited heightened CNV levels. Ligand-receptor-based communication networks exposed significant fibroblast crosstalk with other cell types, and the PDGF signaling pathway was activated in non-metastatic osteosarcoma primary lesion. These results were corroborated by the GSE152048 dataset, confirming the prominence of PDGFD-PDGFRB as a common ligand-receptor pair. Immunohistochemistry demonstrated considerably greater PDGFD expression in non-metastatic osteosarcoma tissues and organoids, correlating with extended metastasis-free and overall survival. PDGFRB expression showed no significant variation between non-metastatic and metastatic osteosarcoma, nor strong correlations with survival times. Multicolor immunofluorescence suggested co-localization of PDGFD with PDGFRB. Flow cytometry unveiled a highly immunosuppressive microenvironment in metastatic osteosarcoma. Manipulating PDGFD expression demonstrated altered invasive abilities and marker expressions in primary osteosarcoma cells from both non-metastatic and metastatic lesions. Conclusions: scRNA-seq illuminated the activation of the PDGF signaling pathway in primary lesion of non-metastatic osteosarcoma. PDGFD displayed an inhibitory effect on osteosarcoma metastasis, likely through the suppression of the EMT signaling pathway. [ABSTRACT FROM AUTHOR]

Background: Alveolar macrophage pyroptosis exacerbates inflammatory lung diseases, and tanshinone IIA is known for its anti-inflammatory properties. Thus, understanding how tanshinone IIA affects alveolar macrophage pyroptosis is essential. Methods: NR8383 cells were exposed to lipopolysaccharide (LPS) and adenosine triphosphate (ATP). We assessed cell viability, pyroptosis, and the expression of triggering receptors expressed on myeloid cells 2 (TREM2), p-β-catenin, β-catenin, and pyroptosis-related factors. We also examined the interaction between tanshinone IIA and TREM2. Results: Co-stimulation with LPS and ATP significantly reduced NR8383 cell viability, increased pyroptosis, and upregulated pyroptosis-associated factors. Treatment with tanshinone IIA mitigated these effects. Tanshinone IIA was effectively bound to the TREM2 protein. Knockdown of TREM2 reduced its expression and the p-β-catenin and β-catenin levels, thereby reversing the protective effects of tanshinone IIA. Conversely, overexpression of TREM2 enhanced NR8383 cell viability, reduced pyroptosis, and suppressed pyroptosis-related factors following LPS and ATP co-stimulation. Furthermore, the NOD-like receptor family pyrin domain containing 3 (NLRP3) activation reversed the reduced pyroptosis induced by β-catenin overexpression. β-catenin knockdown reversed the protective effects of TREM2 overexpression, and activation of NLRP3 exacerbated pyroptosis in β-catenin knockdown cells. Conclusion: Tanshinone IIA inhibited NLRP3 activation and alleviated alveolar macrophage pyroptosis through the TREM2/β-catenin pathway. [ABSTRACT FROM AUTHOR]

Astrocytes respond to infection, injury, and disease with a robust and heterogeneous set of responses often associated with inflammation. Astrocyte heterogeneity is largely modeled at the descriptive level, with the identification of novel signatures of gene expression, proteins, and lipids that are tightly spatiotemporally controlled. While traditionally thought of as passive responders, astrocytes are active contributors to inflammation and release several effector cytokines and chemokines that help to modulate immune responses. In vertebrates, some astrocytes may even be involved in the presentation of antigens to infiltrating T cells. This places them as key initiators of the earliest response to inflammation, without the need for a myeloid cell intermediary. Astrocytes are key modulators of the inflammatory immune response in the mammalian central nervous system (CNS). While traditionally thought of as having only passive roles in the response to inflammatory insults, recent evidence indicates that astrocytes are active players in the earliest stages of inflammation, and may even have a role as atypical antigen-presenting cells. The astrocyte, a major glial cell type in the central nervous system (CNS), is widely regarded as a functionally diverse mediator of homeostasis. During development and throughout adulthood, astrocytes have essential roles, such as providing neuron metabolic support, modulating synaptic function, and maintaining the blood–brain barrier (BBB). Recent evidence continues to underscore their functional heterogeneity and importance for CNS maintenance, as well as how these cells ensure optimal CNS and immune responses to disease, acute trauma, and infection. Advances in our understanding of neuroimmune interactions complement our knowledge of astrocyte functional heterogeneity, where astrocytes are now regarded as key effectors and propagators of immune signaling. This shift in perspective highlights the role of astrocytes not merely as support cells, but as active participants in CNS immune responses. [ABSTRACT FROM AUTHOR]

Background: Microglia (MG) are myeloid cells of the central nervous system that support homeostasis and instigate neuroinflammation in pathologies. Single-cell RNA sequencing (scRNA-seq) revealed the functional heterogeneity of MG in mouse brains. Microglia are self-renewing cells and inhibition of colony-stimulating factor 1 receptor (CSF1R) signaling depletes microglia which rapidly repopulate. The functions of repopulated microglia are poorly known. Methods: We combined scRNA-seq, bulk RNA-seq, immunofluorescence, and confocal imaging to study the functionalities and morphology of repopulated microglia. Results: A CSRF1R inhibitor (BLZ-945) depleted microglia within 21 days and a number of microglia was fully restored within 7 days, as confirmed by TMEM119 staining and flow cytometry. ScRNA-seq and computational analyses demonstrate that repopulated microglia originated from preexisting progenitors and reconstituted functional clusters but upregulated inflammatory genes. Percentages of proliferating, immature microglia displaying inflammatory gene expression increased in aging mice. Morphometric analysis of MG cell body and branching revealed a distinct morphology of repopulated MG, particularly in brains of old mice. We demonstrate that with aging some repopulated MG fail to reach the homeostatic phenotype. These differences may contribute to the deterioration of MG protective functions with age. [ABSTRACT FROM AUTHOR]

Despite being the leading cause of cancer-related childhood mortality, pediatric gliomas have been relatively understudied, and the repurposing of immunotherapies has not been successful. Whole-transcriptome sequencing, single-cell sequencing, and sequential multiplex immunofluorescence were used to identify an immunotherapeutic strategy that could be applied to multiple preclinical glioma models. MAPK-driven pediatric gliomas have a higher IFN signature relative to other molecular subgroups. Single-cell sequencing identified an activated and cytotoxic microglia (MG) population designated MG-Act in BRAF-fused, MAPK-activated pilocytic astrocytoma (PA), but not in high-grade gliomas or normal brain. T cell immunoglobulin and mucin domain 3 (TIM3) was expressed on MG-Act and on the myeloid cells lining the tumor vasculature but not normal brain vasculature. TIM3 expression became upregulated on immune cells in the PA microenvironment, and anti-TIM3 reprogrammed ex vivo immune cells from human PAs to a proinflammatory cytotoxic phenotype. In a genetically engineered murine model of MAPK-driven, low-grade gliomas, anti-TIM3 treatment increased median survival over IgG- and anti–PD-1–treated mice. Single-cell RNA-Seq data during the therapeutic window of anti-TIM3 revealed enrichment of the MG- Act population. The therapeutic activity of anti-TIM3 was abrogated in mice on the CX3CR1 MG–KO background. These data support the use of anti-TIM3 in clinical trials of pediatric low-grade, MAPK-driven gliomas. [ABSTRACT FROM AUTHOR]

Spleen tyrosine kinase (SYK), a non-receptor tyrosine kinase that is overexpressed in several solid tumors, presents a promising therapeutic target. SYK activation downstream of various receptors drives signaling pathways that facilitate tumor progression and immune evasion. SYK inhibition enhances the antitumor immune response in solid tumors by reprogramming myeloid and B cells or directly targeting tumor cells. SYK inhibition can overcome resistance to chemotherapy and immunotherapy in solid tumors. Clinical trials targeting SYK in solid tumors are underway. Spleen tyrosine kinase (SYK) is predominantly expressed in hematopoietic cells and has been extensively studied for its pivotal role in B cell malignancies and autoimmune diseases. In epithelial solid tumors, SYK shows a paradoxical role, acting as a tumor suppressor in some cancers while driving tumor growth in others. Recent preclinical studies have identified the role of SYK in the tumor microenvironment (TME), revealing that SYK signaling in immune cells, especially B cells, and myeloid cells, promote immunosuppression, tumor growth, and metastasis across various solid tumors. This review explores the emerging roles of SYK in solid tumors, the mechanisms of SYK activation, and findings from preclinical and clinical studies of SYK inhibitors as either standalone treatments or in combination with immunotherapy or chemotherapy for solid tumors. [ABSTRACT FROM AUTHOR]

Multi-ancestry genome-wide association studies (GWASs) have highlighted the existence of variants with ancestry-specific effect sizes. Understanding where and why these ancestry-specific effects occur is fundamental to understanding the genetic basis of human diseases and complex traits. Here, we characterized genes differentially expressed across ancestries (ancDE genes) at the cell-type level by leveraging single-cell RNA-sequencing data in peripheral blood mononuclear cells for 21 individuals with East Asian (EAS) ancestry and 23 individuals with European (EUR) ancestry (172,385 cells); then, we tested whether variants surrounding those genes were enriched in disease variants with ancestry-specific effect sizes by leveraging ancestry-matched GWASs of 31 diseases and complex traits (average n ∼ 90,000 and ∼ 267,000 in EAS and EUR, respectively). We observed that ancDE genes tended to be cell-type specific and enriched in genes interacting with the environment and in variants with ancestry-specific disease effect sizes, which suggests cell-type-specific, gene-by-environment interactions shared between regulatory and disease architectures. Finally, we illustrated how different environments might have led to ancestry-specific myeloid cell leukemia 1 (MCL1) expression in B cells and ancestry-specific allele effect sizes in lymphocyte count GWASs for variants surrounding MCL1. Our results imply that large single-cell and GWAS datasets from diverse ancestries are required to improve our understanding of human diseases. We identified genes differentially expressed across two ancestry groups in seven immune cell types. These genes display cell-type specificity as well as enrichment in environmental interactions and variants with ancestry-specific disease effect sizes. These results suggest the impact of cell-type-specific, gene-by-environment interactions shared between regulatory and disease architectures. [ABSTRACT FROM AUTHOR]

Introduction: In sarcoidosis granulomas, monocyte-derived macrophages are activated by pro-inflammatory cytokines including TNF and IL-6. Current drug treatment for sarcoidosis aims to suppress inflammation but disabling side effects can ensue. The macrolide azithromycin may be anti-inflammatory. We aimed to determine whether treatment with azithromycin affects blood inflammatory gene expression and monocyte functions in sarcoidosis. Methods: Blood samples were collected from patients with chronic pulmonary sarcoidosis enrolled in a single arm, open label clinical trial who received oral azithromycin 250 mg once daily for 3 months. Whole blood inflammatory gene expression with or without LPS stimulation was measured using a 770-mRNA panel. Phenotypic analysis and cytokine production were conducted by flow cytometry and ELISA after 24h stimulation with growth factors and TLR ligands. mTOR activity was assessed by measuring phosphorylated S6RP. Results: Differential gene expression analysis indicated a state of heightened myeloid cell activation in sarcoidosis. Compared with controls, sarcoidosis patients showed increased LPS responses for several cytokines and chemokines. Treatment with azithromycin had minimal effect on blood gene expression overall, but supervised clustering analysis identified several chemokine genes that were upregulated. At the protein level, azithromycin treatment increased LPS-stimulated TNF and unstimulated IL-8 production. No other cytokines showed significant changes following azithromycin. Blood neutrophil counts fell during azithromycin treatment whereas mononuclear cells remained stable. Azithromycin had no detectable effects on mTOR activity or activation markers. Conclusion: Blood myeloid cells are activated in sarcoidosis, but azithromycin therapy did not suppress inflammatory gene expression or cytokine production in blood. Trial registration: EudraCT 2019-000580-24 (17 May 2019) [ABSTRACT FROM AUTHOR]

This article discusses a study that used spatial transcriptomics to gain insights into the pathogenesis and therapy of pemphigus vulgaris (PV) and bullous pemphigoid (BP), which are autoimmune bullous skin diseases. The study compared the gene expression profiles of intact and blistered epidermis, as well as dermal immune cells, in PV and BP patients. The findings revealed distinct pathways and gene expression patterns associated with blister formation in each disease. The study provides a foundation for identifying potential therapeutic targets to regulate intracellular pathways involved in blister formation. [Extracted from the article]

Background: Previous observational studies have indicated a complex association between gut microbiota (GM) and neuropathic pain (NP). Nonetheless, the precise biological mechanisms underlying this association remain unclear. Therefore, we adopted a Mendelian randomization (MR) approach to investigate the causal relationship between GM and neuropathic pain including post-herpetic neuralgia (PHN), painful diabetic peripheral neuropathy (PDPN), and trigeminal neuralgia (TN), as well as to explore the potential mediation effects of immune cells. Methods: We performed a two-step, two-sample Mendelian randomization study with an inverse variance-weighted (IVW) approach to investigate the causal role of GM on three major kinds of NP and the mediation effect of immune cells between the association of GM and NP. In addition, we determine the strongest causal associations using Bayesian weighted Mendelian randomization (BWMR) analysis. Furthermore, we will investigate the mediating role of immune cells through a two-step Mendelian randomization design. Results: We identified 53 taxonomies and pathways of gut microbiota that had significant causal associations with NP. In addition, we also discovered 120 immune cells that exhibited significant causal associations with NP. According to the BWMR and two-step Mendelian randomization analysis, we identified the following results CD4 on CM CD4 + (maturation stages of T cell) mediated 6.7% of the risk reduction for PHN through the pathway of fucose degradation (FUCCAT.PWY). CD28 + DN (CD4-CD8-) AC (Treg) mediated 12.5% of the risk reduction for PHN through the influence on Roseburia inulinivorans. CD45 on lymphocyte (Myeloid cell) mediated 11.9% of the risk increase for TN through the superpathway of acetyl-CoA biosynthesis (PWY.5173). HLA DR + CD8br %T cell (TBNK) mediated 3.2% of the risk reduction for TN through the superpathway of GDP-mannose-derived O-antigen building blocks biosynthesis (PWY.7323). IgD-CD38-AC (B cell) mediated 7.5% of the risk reduction for DPN through the pathway of thiazole biosynthesis I in E. coli (PWY.6892). Discussion: These findings provided evidence supporting the causal effect of GM with NP, with immune cells playing a mediating role. These findings may inform prevention strategies and interventions directed toward NP. Future studies should explore other plausible biological mechanisms. [ABSTRACT FROM AUTHOR]

The objective of this study was to enhance the anticancer potential of curcumin (CR)-loaded niosomal formulation against human myeloid leukemia cell lines and its antioxidant activity by the incorporation of amphiphilic palmitoyl-modified arginine (PL-ARG) serving as a positively charged amphiphile. PL-ARG was synthesized by using palmitoyl chloride (PL) and l-arginine (ARG) followed by characterization through ESI–MS, 1H-NMR, and FT-IR. The proportion of niosomal constituents including Tween 80/20 and cholesterol was optimized using experimental design to achieve small size vesicle with enhanced encapsulation of CR, and the optimized proportion was then used for the development of niosomal formulation functionalized with synthesized PL-ARG (PL-ARG-CR-NSMs). For the comparison, non-functionalized CR-loaded niosomes (CR-NSMs) were also prepared. The developed niosomal vesicles were characterized for encapsulation efficiency, size, PDI, zeta potential and surface morphology, and in vitro drug release. CR was encapsulated in niosomes with entrapment efficiency of 78.94 ± 5.16% (PL-ARG-CR-NSMs) and 65.82 ± 3.52% (CR-NSM) and provided a sustained drug release profile. Interestingly, when compared to CR-NSMs, the PL-ARG-CR-NSMs demonstrated enhanced growth inhibition of human myeloid leukemia cell lines supporting the antitumor efficacy of CR delivered from PL-ARG-CR-NSMs against human myeloid leukemia cell lines as well as the feasibility of arginine modified niosomes as a sustainable cancer treatment approach. [ABSTRACT FROM AUTHOR]

Inflammation contributes to the development of thrombosis, but the mechanistic basis for this association remains poorly understood. Innate immune responses and coagulation pathways are activated in parallel following infection or injury, and represent an important host defense mechanism to limit pathogen spread in the bloodstream. However, dysregulated proinflammatory activity is implicated in the progression of venous thromboembolism and arterial thrombosis. In this review, we focus on the role of myeloid cells in propagating thromboinflammation in acute inflammatory conditions, such as sepsis and coronavirus disease 2019 (COVID-19), and chronic inflammatory conditions, such as obesity, atherosclerosis, and inflammatory bowel disease. Myeloid cells are considered key drivers of thromboinflammation via upregulated tissue factor activity, formation of neutrophil extracellular traps (NETs), contact pathway activation, and aberrant coagulation factor–mediated protease-activated receptor (PAR) signaling. We discuss how strategies to target the intersection between myeloid cell–mediated inflammation and activation of blood coagulation represent an exciting new approach to combat immunothrombosis. Specifically, repurposed anti-inflammatory drugs, immunometabolic regulators, and NETosis inhibitors present opportunities that have the potential to dampen immunothrombotic activity without interfering with hemostasis. Such therapies could have far-reaching benefits for patient care across many thromboinflammatory conditions. [ABSTRACT FROM AUTHOR]

For the first time, an analysis of leukocyte changes in the organs of the immune system (pronephros, mesonephros, and spleen) of the Baikal omul Coregonus migratorius (Georgi, 1775) (Salmoniformes: Coregonidae) infected with Dibothriocephalus dendriticus (Nitsch, 1824) (syn. Diphyllobothrium dendriticum) (Cestoda: Diphyllobothriidea) is presented in natural habitat conditions. In the pronephros of infected fish, the number of poorly differentiated neutrophils (myelocytes and metamyelocytes) was significantly higher than in uninfected fish, which indicated inflammatory processes. D. dendriticus triggered the immunoregulatory processes in the body of infected fish, as evidenced by the decrease in the total number of lymphocytes and prolymphocytes (B-lymphocytes) in the pronephros and the increase in prolymphocytes in the spleen. The other effector elements (cells of the monocyte–macrophage lineage, basophils, and eosinophils) were barely involved in antiparasitic defense. [ABSTRACT FROM AUTHOR]

Colony stimulating factor 1 receptor (CSF1R) is an essential receptor for both colony stimulating factor 1 (CSF1) and interleukin (IL) 34 signaling expressed on monocyte precursors and myeloid cells, including monocytes, dendritic cells (DC), and microglia. In humans, dominant heterozygous pathogenic variants in CSF1R cause a neurological condition known as CSF1R-related disorder (CSF1R-RD), typically with late onset, previously referred to as adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP). CSF1R-RD is characterized by microglia reduction and altered monocyte function; however, the impact of pathogenic CSF1R variants on the human DC lineage remains largely unknown. We previously reported that cord blood CD34+ stem cell-derived DCs generated in vitro originate specifically from CSF1R expressing precursors. In this study, we examined the DC lineage of four unrelated patients with late-onset CSF1R-RD who carried heterozygous missense CSF1R variants (c.2330G>A, c.2375C>A, c.2329C>T, and c.2381T>C) affecting different amino acids in the protein tyrosine kinase domain of CSF1R. CD34+ stem cells and CD14+ monocytes were isolated from peripheral blood and subjected to an in vitro culture protocol to differentiate towards conventional DCs and monocyte-derived DCs, respectively. Flow cytometric analysis revealed that monocytes from patients with late-onset CSF1R-RD were still able to differentiate into monocyte-derived DCs in vitro , whereas the ability of CD34+ stem cells to differentiate into conventional DCs was impaired. Strikingly, the peripheral blood of patients contained all naturally occurring DC subsets. We conclude that the in vitro abrogation of DC-development in patients with heterozygous pathogenic missense CSF1R variants does not translate to an impairment in DC development in vivo and speculate that CSF1R signalling in vivo is compensated, which needs further study. • CSF1R is crucial for in vitro cDC differentiation from CD34+ stem cells but not essential for monocyte-derived DC development. • Late-onset CSF1R-RD patients have all naturally occurring dendritic cell subsets in their peripheral blood despite impaired CSF1R. • In vivo compensation by other cytokines might explain normal DC subsets in late-onset CSF1R-RD patients. [ABSTRACT FROM AUTHOR]

Acute pancreatitis (AP) is an inflammatory disease of the pancreas and the main cause of hospital admissions for gastrointestinal diseases. Here, the work studied the circular RNA DTNB/microRNA-485-5p/MCL1 axis in AP and hoped to unravel the related mechanism. Caerulein exposure replicated an AP model in AR42J cells, and caerulein-mediated expression of circDTNB, miR-485-5p, and MCL1 was recorded. After exposure, cells were intervened with transfection plasmids and tested for LDH release, apoptosis, and inflammation. To determine the interwork of circDTNB, miR-485-5p, and MCL1, prediction results and verification experiments were conducted. Caerulein exposure reduced circDTNB and MCL1, while elevated miR-485-5p levels in AR42J cells. Upregulating circDTNB protected AR42J cells from caerulein-induced LDH cytotoxicity, apoptosis, and inflammation, but circDTNB upregulation-induced protections could be muffled by inhibiting MCL1. On the contrary, downregulating circDTNB further damaged AR42J cells under caerulein exposure, however, this phenomenon could be partially rescued after silencing miR-485-5p. miR-485-5p was mechanistically verified to be a target of circDTNB to mediate MCL1. Overall, the circDTNB/miR-485-5p/MCL1 axis protects inflammatory response and apoptosis in caerulein-exposed AR42J cells, promisingly identifying circDTNB as a novel molecule for AP treatment. [ABSTRACT FROM AUTHOR]

Lymph node metastasis contributed to the leading cause and treatment failure in nasopharyngeal carcinoma (NPC). The microenvironment and the cellular communications of lymph node metastasized tumours determine the tumour progression and therapeutic effect, but the ecosystems about the lymph node metastasis (LNM) for NPC patients remain poorly characterized. Here, we integrated the transcriptomes of 47,618 single cells from eight samples related to NPC LNM. The dynamic immune ecosystems and immunosuppressive microenvironment including T cells, myeloid cells and B cells were observed in the lymph node metastatic samples compared with primary tumours. Additionally, the heterogeneity of epithelial cells was also revealed, and several clusters with expression programs that were associated with the progression‐free survival of NPC patients were identified. Additionally, our data revealed the complex intercellular communications from primary to lymph node metastasis. The rewiring of CCL signalling which plays an important role in tumour metastasis was further identified. Altogether, we systematically characterized the ecosystem of NPC primary and lymph node metastasized tumours, which may shed light on the development of a therapeutic strategy to improve clinical outcomes of NPC patients with lymph node metastasis. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms by which cancer cells switch between different adaptive states and evade therapeutic interventions is essential for clinical management. In this study, the in vivo cellular dynamics of a new chronic myeloid leukaemia cell line displaying altered phenotype and resistance to tyrosine kinase inhibitors were investigated in correlation with their parental cells for invasiveness/metastasis, angiogenic potential and population kinetics. We showed that the cells exhibiting drug resistance and plastic phenotype possess an increased capacity for invasion compared to their parental cells, that exposure to imatinib mesylate has the potential to enhance cellular motility and that in a leukaemic cell population, even a minority of plastic cells exhibit improved migratory ability. Furthermore, we show that these plastic cells have angiogenic and extravasation potential. The present study provides significant insights into the cellular dynamics displayed by a TKI‐resistant, phenotypically plastic CML cell line, using a zebrafish (Danio rerio) xenograft model. [ABSTRACT FROM AUTHOR]

Objective: Signal regulatory protein α (SIRPα) is found primarily on myeloid cells, including macrophages and neutrophils; binds to CD47; and regulates phagocytosis, antigen presentation, cellular fusion, cell proliferation, and migration. Therefore, SIRPα may be involved in the pathogenesis of autoimmune diseases, including systemic vasculitis. This study aimed to assess SIRPα expression in tissue samples from patients with vasculitis. Methods: Immunohistochemical staining for SIRPα was performed on temporal artery (TA), kidney, and lung biopsy samples from patients with giant cell arteritis (GCA), patients with microscopic polyangiitis (MPA), patients with granulomatosis with polyangiitis (GPA), and patients without vasculitis. A score of SIRPα+ expression was calculated, derived from the percentages of monocytes, macrophages, and dendritic cells and neutrophils with different staining intensities in affected tissues. Results: A total of 46 samples from patients with different vasculitides (GCA, MPA, and GPA) were included in the study. Tissue samples included TA samples from 15 patients with GCA; kidney samples from 11 and 9 patients with GPA and MPA, respectively; and lung samples from 11 patients with GPA. Most tissue samples from patients with active vasculitis (15 of 15 TA samples, 17 of 20 kidney samples, and 9 of 11 lung samples) showed SIRPα staining. SIRPα staining intensity was less in kidney samples compared to TA and lung samples. Conclusion: This study demonstrates high‐level expression of SIRPα in macrophages and monocytes in affected tissue in systemic vasculitis. These findings provide a foundation for further studies exploring the role of the SIRPα–CD47 pathway in the pathogenesis of systemic vasculitis and the potential for the blockade of SIRPα and/or the depletion of SIRPα+ cells as treatment of systemic vasculitis. [ABSTRACT FROM AUTHOR]

Background: The gut microbiota (GM) plays a pivotal role in influencing various health outcomes, including immune-mediated conditions, but its potential association with autoimmune thyroid disease (AITD) remains underexplored. We aimed to investigate the potentially pathogenic or protective causal impacts of specific GM on two types of AITD, namely Graves' disease and Hashimoto's thyroiditis, and analyzed the mediating effect of 731 immune cell phenotypes. Methods: Leveraging pooled genome-wide association study (GWAS) data of 211 gut microbiota traits, 731 immune cell phenotypes, and two types of AITD (Hashimoto's thyroiditis and Graves' disease), we performed bidirectional Mendelian randomization (MR) analyses to explore the causal relationships between the GM and AITD. Subsequently, we employed a multivariable MR analysis to discover potential mediating immune cell traits. Additionally, sensitivity analyses were utilized to ensure the reliability of the outcomes. Results: Our analysis revealed that a total of 7 GM taxa were positively associated with AITD, and other 14 taxa showed a negative correlation with AITD. Furthermore, we identified several immune cell traits that mediated the effects of GM on AITD. Most notably, Actinobacteria (p) presented protective effects on Hashimoto's thyroiditis via CCR2 on myeloid Dendritic Cell (5.0%), and Bifidobacterium (g) showed facilitating effects on Graves' disease through CD39+ CD4+ T cell %CD4+ T cell (5.0%) and CD14 on CD33+ HLA DR+ CD14dim (12.2%). Conclusion: The current MR study provides evidence supporting the causal relationships between several specific GM taxa and AITD, and further identified potential mediating immunophenotypes. [ABSTRACT FROM AUTHOR]

Osteosarcoma has a unique tumor microenvironment (TME), which is characterized as a complex microenvironment comprising of bone cells, immune cells, stromal cells, and heterogeneous vascular structures. These elements are intricately embedded in a mineralized extracellular matrix, setting it apart from other primary TMEs. In a state of normal physiological function, these cell types collaborate in a coordinated manner to maintain the homeostasis of the bone and hematopoietic systems. However, in the pathological condition, i.e., neoplastic malignancies, the tumor-immune microenvironment (TIME) has been shown to promote cancer cells proliferation, migration, apoptosis and drug resistance, as well as immune escape. The intricate and dynamic system of the TIME in osteosarcoma involves crucial roles played by various infiltrating cells, the complement system, and exosomes. This complexity is closely associated with tumor cells evading immune surveillance, experiencing uncontrolled proliferation, and facilitating metastasis. In this review, we elucidate the intricate interplay between diverse cell populations in the osteosarcoma TIME, each contributing uniquely to tumor progression. From chondroblastic and osteoblastic osteosarcoma cells to osteoclasts, stromal cells, and various myeloid and lymphoid cell subsets, the comprehensive single-cell analysis provides a detailed roadmap of the complex osteosarcoma ecosystem. Furthermore, we summarize the mutations, epigenetic mechanisms, and extracellular vesicles that dictate the immunologic landscape and modulate the TIME of osteosarcoma. The perspectives of the clinical implementation of immunotherapy and therapeutic approaches for targeting immune cells are also intensively discussed. [ABSTRACT FROM AUTHOR]

BACKROUND Complement activation may facilitate hypertension through its effects on immune responses. The anaphylatoxin C5a, a major inflammatory effector, binds to the C5a receptors 1 and 2 (C5aR1, C5aR2). We have recently shown that C5aR1−/− mice have reduced hypertensive renal injury. The role of C5aR2 in hypertension is unknown. METHODS For examination of C5aR2 expression on infiltrating and resident renal cells a tandem dye Tomato-C5aR2 knock-in reporter mouse was used. Human C5aR2 expression was analyzed in a single-cell RNAseq data set from the kidneys of hypertensive patients. Finally, we examined the effect of angiotensin II-induced hypertension in C5aR2-deficient mice. RESULTS Flow cytometric analysis of leukocytes isolated from kidneys of the reporter mice showed that dendritic cells are the major C5aR2-expressing population (34%) followed by monocyte/macrophages (30%) and neutrophils (14%). Using confocal microscopy C5aR2 was not detected in resident renal or cardiac cells. In the human kidney, C5aR2 was also mainly found in monocytes, macrophages, and dendritic cells with a significantly higher expression in hypertension (P  < 0.05). Unilateral nephrectomy was performed followed by infusion of Ang II (0.75 ng/g/min) and a high salt diet in wildtype (n  = 18) and C5aR2-deficient mice (n  = 14). Blood pressure, renal injury (albuminuria, glomerular filtration rate, glomerular and tubulointerstitial injury, inflammation), and cardiac injury (cardiac fibrosis, heart weight, gene expression) did not differ between hypertensive wildtype and C5aR2−/− mice. CONCLUSIONS In summary, C5aR2 is mainly expressed in myeloid cells in the kidney in mice and humans but its deficiency has no effect on Ang II-induced hypertensive injury. [ABSTRACT FROM AUTHOR]

Escherichia coli strains producing the genotoxin colibactin, designated as CoPEC (colibactin-producing E. coli), have emerged as an important player in the etiology of colorectal cancer (CRC). Here, we investigated the role of macroautophagy/autophagy in myeloid cells, an important component of the tumor microenvironment, in the tumorigenesis of a susceptible mouse model infected with CoPEC. For that, a preclinical mouse model of CRC, the ApcMin/+ mice, with Atg16l1 deficiency specifically in myeloid cells (ApcMin/+/Atg16l1[∆MC]) and the corresponding control mice (ApcMin/+), were infected with a clinical CoPEC strain 11G5 or its isogenic mutant 11G5∆clbQ that does not produce colibactin. We showed that myeloid cell-specific Atg16l1 deficiency led to an increase in the volume of colonic tumors in ApcMin/+ mice under infection with 11G5, but not with 11G5∆clbQ. This was accompanied by increased colonocyte proliferation, enhanced inflammasome activation and IL1B/IL-1β secretion, increased neutrophil number and decreased total T cell and cytotoxic CD8+ T cell numbers in the colonic mucosa and tumors. In bone marrow-derived macrophages (BMDMs), compared to uninfected and 11G5∆clbQ-infected conditions, 11G5 infection increased inflammasome activation and IL1B secretion, and this was further enhanced by autophagy deficiency. These data indicate that ATG16L1 in myeloid cells was necessary to inhibit colonic tumor growth in CoPEC-infected ApcMin/+ mice via inhibiting colibactin-induced inflammasome activation and modulating immune cell response in the tumor microenvironment. Abbreviation: AOM, azoxymethane; APC, APC regulator of WNT signaling pathway; ATG, autophagy related; Atg16l1[∆MC] mice, mice deficient for Atg16l1 specifically in myeloid cells; CASP1, caspase 1; BMDM, bone marrow-derived macrophage; CFU, colony-forming unit; CoPEC, colibactin-producing Escherichia coli; CRC, colorectal cancer; CXCL1/KC, C-X-C motif chemokine ligand 1; ELISA, enzyme-linked immunosorbent assay; IL, interleukin; MC, myeloid cell; MOI, multiplicity of infection; PBS, phosphate-buffered saline; pks, polyketide synthase; qRT-PCR, quantitative real-time reverse-transcription polymerase chain reaction; siRNA, small interfering RNA; TME, tumor microenvironment; TNF/TNF-α, tumor necrosis factor. [ABSTRACT FROM AUTHOR]

Helicobacter pylori (H. pylori) is a bacterial pathogen that exclusively colonizes the human gastric mucosa and can cause persistent infection. In this process, H. pylori employs various strategies to avoid recognition by the human immune system. These range from passive defense strategies (e.g., altered LPS or flagellin structures) that prevent recognition by pattern recognition receptors (PRRs) to more active approaches, such as inhibition of IL-2 secretion and proliferation of T cells via VacA. Despite the growing evidence that H. pylori actively manipulates the human immune system for its own benefit, the direct interaction of H. pylori with immune cells in situ is poorly studied. Here, we present a novel intravital imaging model of the murine stomach gastric mucosa and show for the first time the in situ recruitment of neutrophils during infection and a direct H. pylori-macrophage interaction. For this purpose, we applied multiphoton intravital microscopy adapted with live drift correction software (VivoFollow) on LysM-eGFP and CX3CR1-eGFP reporter mice strains in which specific subsets of leukocytes are fluorescently labeled. Multiphoton microscopy is proving to be an excellent tool for characterizing interactions between immune cells and pathogens in vivo. Author summary: This study focuses on the dynamics of H. pylori infection and its interaction with myeloid immune cells, using an innovative in vivo multiphoton imaging approach to observe real-time events in the infected gastric mucosa. In contrast to conventional methods, this novel technique allows us to dynamically investigate the host immune response. Our results show the spatio-temporal distribution of neutrophils and the internalization of H. pylori by macrophages over time. Using intravital multiphoton microscopy enhanced with live drift correction software and utilizing LysM-eGFP and CX3CR1-eGFP reporter mice, we established an intravital imaging model for the gastric mucosa of mice. Notably, we observe a significant increase in neutrophil infiltration into the gastric submucosa during early infection, indicating a rapid response of the innate immune system within the gastric crypts. However, in the chronic infection phase, a contrasting decrease in neutrophil influx is seen, indicating an adaptive innate immune response with fewer neutrophils infiltrating the tissue at an increased rate. Importantly, our data suggest that H. pylori is dependent on macrophages to proliferate and colonize the gastric mucosa during chronic infection. [ABSTRACT FROM AUTHOR]

Western diets are the underlying cause of metabolic and liver diseases. Recent trend to limit the consumption of protein-rich animal products has become more prominent. This dietary change entails decreased protein consumption; however, it is still unknown how this affects innate immunity. Here, we studied the influence of a low protein diet (LPD) on the liver response to bacterial infection in mice. We found that LPD protects from Salmonella enterica serovar Typhimurium (S. Typhimurium)-induced liver damage. Bulk and single-cell RNA sequencing of murine liver cells showed reduced inflammation and upregulation of autophagy-related genes in myeloid cells in mice fed with LPD after S. Typhimurium infection. Mechanistically, we found reduced activation of the mammalian target of rapamycin (mTOR) pathway, whilst increased phagocytosis and activation of autophagy in LPD-programmed macrophages. We confirmed these observations in phagocytosis and mTOR activation in metabolically programmed human peripheral blood monocyte-derived macrophages. Together, our results support the causal role of dietary components on the fitness of the immune system. Low protein diet protects against Salmonella Typhimurium-mediated liver injury in mice corresponding to reduced mTOR activation and increased autophagy in macrophages. mTOR pathway activation with amino acid supplementation reverses this protection. [ABSTRACT FROM AUTHOR]

Age-related hearing loss (ARHL) or presbycusis is associated with irreversible progressive damage in the inner ear, where the sound is transduced into electrical signal; but the detailed mechanism remains unclear. Here, we sought to determine the potential molecular mechanism involved in the pathogeneses of ARHL with bioinformatics methods. A single-cell transcriptome sequencing study was performed on the cochlear samples from young and aged mice. Detection of identified cell type marker allowed us to screen 18 transcriptional clusters, including myeloid cells, epithelial cells, B cells, endothelial cells, fibroblasts, T cells, inner pillar cells, neurons, inner phalangeal cells, and red blood cells. Cell-cell communications were analyzed between young and aged cochlear tissue samples by using the latest integration algorithms Cellchat. A total of 56 differentially expressed genes were screened between the two groups. Functional enrichment analysis showed these genes were mainly involved in immune, oxidative stress, apoptosis, and metabolic processes. The expression levels of crucial genes in cochlear tissues were further verified by immunohistochemistry. Overall, this study provides new theoretical support for the development of clinical therapeutic drugs. [ABSTRACT FROM AUTHOR]

Background: Acute myeloid leukaemia (AML) comprises a group of heterogeneous and aggressive haematological malignancies with unsatisfactory prognoses and limited treatment options. Treatments targeting B-cell lymphoma-2 (BCL-2) with venetoclax have been approved for patients with AML, and venetoclax-based drug combinations are becoming the standard of care for older patients unfit for intensive chemotherapy. However, the therapeutic duration of either single or combination strategies is limited, and the development of resistance seems inevitable. Therefore, more effective combination regimens are urgently needed. Methods: The efficacy of combination therapy with NL101, a SAHA-bendamustine hybrid, and venetoclax was evaluated in preclinical models of AML including established cell lines, primary blasts from patients, and animal models. RNA-sequencing and immunoblotting were used to explore the underlying mechanism. Results: NL101 significantly potentiated the activity of venetoclax in AML cell lines, as evidenced by the enhanced decrease in viability and induction of apoptosis. Mechanistically, the addition of NL101 to venetoclax decreased the stability of the antiapoptotic protein myeloid cell leukaemia-1 (MCL-1) by inhibiting ERK, thereby facilitating the release of BIM and triggering mitochondrial apoptosis. Moreover, the strong synergy between NL101 and venetoclax also relied on the downregulation of c-Myc via PI3K/Akt/GSK3β signalling. The combination of NL101 and venetoclax synergistically eliminated primary blasts from 10 AML patients and reduced the leukaemia burden in an MV4-11 cell-derived xenograft model. Conclusions: Our results encourage the pursuit of clinical trials of combined treatment with NL101 and venetoclax and provide a novel venetoclax-incorporating therapeutic strategy for AML. [ABSTRACT FROM AUTHOR]

Disease recurrence following chemotherapy is a major clinical challenge in ovarian cancer (OC), but little is known regarding how the tumour epigenome regulates transcriptional programs underpinning chemoresistance. We determine the single cell chromatin accessibility landscape of omental OC metastasis from treatment-naïve and neoadjuvant chemotherapy-treated patients and define the chromatin accessibility profiles of epithelial, fibroblast, myeloid and lymphoid cells. Epithelial tumour cells display open chromatin regions enriched with motifs for the oncogenic transcription factors MEIS and PBX. Post chemotherapy microenvironments show profound tumour heterogeneity and selection for cells with accessible chromatin enriched for TP53, TP63, TWIST1 and resistance-pathway-activating transcription factor binding motifs. An OC chemoresistant tumour subpopulation known to be present prior to treatment, and characterised by stress-associated gene expression, is enriched post chemotherapy. Nuclear receptors RORa, NR2F6 and HNF4G are uncovered as candidate transcriptional drivers of these cells whilst closure of binding sites for E2F2 and E2F4 indicate post-treated tumour having low proliferative capacity. Delineation of the gene regulatory landscape of ovarian cancer cells surviving chemotherapy treatment therefore reveals potential core transcriptional regulators of chemoresistance, suggesting novel therapeutic targets for improving clinical outcome. Interrogating the single cell chromatin accessibility landscape of Ovarian Cancer metastatic tumour cells that reside following chemotherapy treatment highlights potential regulatory drivers of chemoresistance. [ABSTRACT FROM AUTHOR]

The catfish industry is the largest sector of U.S. aquaculture production. Given its role in food production, the catfish immune response to industry-relevant pathogens has been extensively studied and has provided crucial information on innate and adaptive immune function during disease progression. To further examine the channel catfish immune system, we performed single-cell RNA sequencing on nuclei isolated from whole spleens, a major lymphoid organ in teleost fish. Libraries were prepared using the 10X Genomics Chromium X with the Next GEM Single Cell 3' reagents and sequenced on an Illumina sequencer. Each demultiplexed sample was aligned to the Coco_2.0 channel catfish reference assembly, filtered, and counted to generate feature-barcode matrices. From whole spleen samples, outputs were analyzed both individually and as an integrated dataset. The three splenic transcriptome libraries generated an average of 278,717,872 reads from a mean 8,157 cells. The integrated data included 19,613 cells, counts for 20,121 genes, with a median 665 genes/cell. Cluster analysis of all cells identified 17 clusters which were classified as erythroid, hematopoietic stem cells, B cells, T cells, myeloid cells, and endothelial cells. Subcluster analysis was carried out on the immune cell populations. Here, distinct subclusters such as immature B cells, mature B cells, plasma cells, γδ T cells, dendritic cells, and macrophages were further identified. Differential gene expression analyses allowed for the identification of the most highly expressed genes for each cluster and subcluster. This dataset is a rich cellular gene expression resource for investigation of the channel catfish and teleost splenic immunome. [ABSTRACT FROM AUTHOR]

Summary The iron chelator deferasirox (DFX) is effective in the treatment of iron overload. In certain patients with myelodysplastic syndrome, DFX can also provide a dramatic therapeutic benefit, improving red blood cell production and decreasing transfusion requirements. Nuclear Factor‐kappa B (NF‐kB) signalling has been implicated as a potential mechanism behind this phenomenon, with studies focusing on the effect of DFX on haematopoietic progenitors. Here, we examine the phenotypic and transcriptional effects of DFX throughout myeloid cell maturation in both murine and human model systems. The effect of DFX depends on the stage of differentiation, with effects on mitochondrial reactive oxygen species (ROS) production and NF‐kB pathway regulation that vary between progenitors and neutrophils. DFX triggers a greater increase in mitochondrial ROS production in neutrophils and this phenomenon is mitigated when cells are cultured in hypoxic conditions. Single‐cell transcriptomic profiling revealed that DFX decreases the expression of NF‐kB and MYC (c‐Myc) targets in progenitors and decreases the expression of PU.1 (SPI1) gene targets in neutrophils. Together, these data suggest a role of DFX in impairing terminal maturation of band neutrophils. [ABSTRACT FROM AUTHOR]