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Compared with young liver donors, aged liver donors are more susceptible to ischemia-reperfusion injury (IRI) following transplantation, which may be related to excessive inflammatory response and macrophage dysfunction, but the specific mechanism is unclear. Macrophage scavenger receptor 1 (MSR1) is a member of the scavenger receptor family, and plays an important regulatory role in inflammation response and macrophage function regulation. But its role in IRI following aged-donor liver transplantation is still unclear. This study demonstrates that MSR1 expression is decreased in macrophages from aged donor livers, inhibiting their efferocytosis and pro-resolving polarisation. Decreased MSR1 is responsible for the more severe IRI suffered by aged donor livers. Overexpression of MSR1 using F4/80-labelled AAV 9 improved intrahepatic macrophage efferocytosis and promoted pro-resolving polarisation, ultimately ameliorating IRI following aged-donor liver transplantation. In vitro co-culture experiments further showed that overexpression of MSR1 promoted an increase in calcium concentration, which further activated the PI3K-AKT-GSK3β pathway, and induced the upregulation of β-catenin. Overall, MSR1-dependent efferocytosis promoted the pro-resolving polarisation of macrophages through the PI3K-AKT-GSK3β pathway-induced up-regulating of β-catenin leading to improved IRI following aged-donor liver transplantation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Physiochemical properties of nanoparticles, such as their size and chemical composition, dictate their interaction with professional phagocytes of the innate immune system. Macrophages, in particular, are key regulators of the immune microenvironment that heavily influence particle biodistribution as a result of their uptake. This attribute enables macrophage-targeted delivery, including for phenotypic modulation. Saccharide-based materials, including polyglucose polymers and nanoparticles, are efficient vehicles for macrophage-targeted delivery. Here, we investigate the influence of particle size on cyclodextrin nanoparticle (CDNP) uptake by macrophages and further examine the receptor-mediated interactions that drive macrophage-targeted delivery. We designed and synthesized CDNPs ranging in size from 25 nm to >100 nm in diameter. Increasing particle size was correlated with greater uptake by macrophages in vitro . Both scavenger receptor A1 and mannose receptor were critical mediators of macrophage-targeted delivery, inhibition of which reduced the extent of uptake. Finally, we investigated the cellular bioavailability of drug-loaded CDNPs using a model anti-inflammatory drug, celastrol, which demonstrated that drug bioactivity is improved by CDNP loading relative to free drug alone. This study thus elucidates the interactions between the polyglucose nanoparticles and macrophages, thereby facilitating their application in macrophage-targeted drug delivery that has applications in the context of tissue injury and repair.

This study aimed to investigate whether class A1 scavenger receptor (SR-A1) regulated macrophage polarization and gut microbial alteration during intestinal inflammation of colitis. A murine colitis model was established by feeding with dextran sulfate sodium (DSS), and treatment groups were injected intravenously with SR-A1 antibody. Results showed a preventive effect on colitis symptoms and fewer inflammatory cell infiltrates in treatment groups. Down-regulation of inflammatory cytokines and up-regulation of anti-inflammatory cytokine related to macrophages were seen in murine PBMC and LPMC after injected with SR-A1 antibody. The percentage of M2 macrophages was also elevated in treatment groups. In addition, SR-A1 antibody treatment resulted in the decreased apoptosis and increased proliferation of colonic epithelial cells. Other findings indicated that SR-A1 antibody injection could mediate its anti-inflammatory effect via inhibiting TLR4-MyD88-NF-kB signaling pathway and alterating the gut microbiota composition. Our research identified SR-A1 as a potential therapeutic target in inflammatory bowel disease (IBD)., (© 2024. The Author(s).)

The removal of axonal and myelin debris by macrophages is crucial for safeguarding nerves and facilitating functional recuperation in cerebral ischemic stroke. However, the physiological function of macrophage scavenger receptor 1 (MSR1) in ischemic white matter injury remains poorly de-fined. In this study, we observed an elevation in Msr1 expression levels in mice with experimental cerebral ischemic stroke. Msr 1-deficient (Msr1-/-) mice exhibited exacerbated behavioral deficits and aggravated white matter injury after ischemic stroke. Furthermore, the overexpression of Msr1 led to an increase in the phosphorylation of Akt via Hrh1, which in turn expedited the clearance of myelin debris through the PI3K/AKT pathway. In conclusion, our findings underscore the essential role of MSR1 in microglial phagocytosis and its ability to mitigate ischemic white matter injury in cerebral ischemic stroke., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Circular RNAs (circRNAs) are stable RNAs present in cell-free RNA, which may comprise cellular debris and pathogen genomes. Here, we investigate the phenomenon and mechanism of cellular uptake and intracellular fate of exogenous circRNAs. Human myeloid cells and B cells selectively internalize extracellular circRNAs. Macrophage uptake of circRNA is rapid, energy dependent, and saturable. CircRNA uptake can lead to translation of encoded sequences and antigen presentation. The route of internalization influences immune activation after circRNA uptake, with distinct gene expression programs depending on the route of RNA delivery. Genome-scale CRISPR screens and chemical inhibitor studies nominate macrophage scavenger receptor MSR1, Toll-like receptors, and mTOR signaling as key regulators of receptor-mediated phagocytosis of circRNAs, a dominant pathway to internalize circRNAs in parallel to macropinocytosis. These results suggest that cell-free circRNA serves as an "eat me" signal and danger-associated molecular pattern, indicating orderly pathways of recognition and disposal., Competing Interests: Declaration of interests H.Y.C. is a co-founder of Accent Therapeutics, Boundless Bio, Cartography Biosciences, and Orbital Therapeutics and is an advisor of 10x Genomics, Arsenal Biosciences, Chroma Medicine, Exai Bio, and Spring Discovery. H.Y.C. is a member of the Molecular Cell advisory board. R.M. is on the advisory boards of Kodikaz Therapeutic Solutions, Orbital Therapeutics, and 858 Therapeutics and is an inventor on a number of patents related to CD47 cancer immunotherapy licensed to Gilead Sciences. R.M. is a co-founder and equity holder of Pheast Therapeutics, MyeloGene, and Orbital Therapeutics. B.A. is a current employee at Eli Lilly., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Morinda officinalis polysaccharide (MOP) is the bioactive ingredient extracted from the root of Morinda officinalis, and Morinda officinalis is applied to treat osteoporosis (OP). The purpose of this study was to determine the role of MOP on human bone marrow mesenchymal stem cells (hBMSCs) and the underlying mechanism. HBMSCs were isolated from bone marrow samples of patients with OP and treated with MOP. Quantitative real-time polymerase chain reaction was adopted to quantify the expression of microRNA-210-3p (miR-210-3p) and scavenger receptor class A member 3 (SCARA3) mRNA. Cell Counting Kit-8 assay was employed to detect cell viability; Terminal-deoxynucleotidyl Transferase Mediated Nick End Labeling assay and flow cytometry were adopted to detect apoptosis; Alkaline Phosphatase (ALP) activity assay kit was applied to detect ALP activity; Western blot was executed to quantify the expression levels of SCARA3, osteogenic and adipogenic differentiation markers. Ovariectomized rats were treated with MOP. Bone mineral density (BMD), serum tartrate-resistant acid phosphatase 5b (TRACP 5b), and N-telopeptide of type I collagen (NTx) levels were assessed by BMD detector and Enzyme-linked immunosorbent assay kits. It was revealed that MOP could promote hBMSCs' viability and osteogenic differentiation and inhibit apoptosis and adipogenic differentiation. MOP could also upregulate SCARA3 expression through repressing miR-210-3p expression. Treatment with MOP increased the BMD and decreased the TRACP 5b and NTx levels in ovariectomized rats. MOP may boost the osteogenic differentiation and inhibit adipogenic differentiation of hBMSCs by miR-210-3p/SCARA3 axis., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Scavenger receptor A (SRA) is preferentially expressed in macrophages and implicated as a multifunctional pattern recognition receptor for innate immunity. Hepatic macrophages play a primary role in the pathogenesis of alcoholic liver disease. Herein, we observed that SRA expression was significantly increased in the liver tissues of mice with alcohol-related liver injury. SRA-deficient (SRA-/-) mice developed more severe alcohol-induced liver disease than wild-type mice. Enhanced liver inflammation existed in alcohol-challenged SRA-/- mice and was associated with increased Notch activation in hepatic macrophages compared with wild-type control animals. Mechanistically, SRA directly bound with Notch1 and suppressed its S-glutathionylation, thereby inhibiting Notch pathway activation. Further, we determined that the SRA interacted with thioredoxin-1 (Trx-1), a redox-active protein. SRA inhibited Trx-1 dimerization and facilitated the interaction of Trx-1 with Notch1. Application of a Trx-1-specific inhibitory agent during macrophage stimulation abolished SRA-mediated regulation of the Notch pathway and its downstream targets. In summary, our study revealed that SRA plays a critical role in macrophage inflammatory response by targeting Notch1 for its glutathionylation. SRA-mediated negative regulation of Notch activation might serve as a novel therapeutic strategy for alcohol-induced liver injury., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2023. Published by Oxford University Press on behalf of Society for Leukocyte Biology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Scavenger receptor class A, member 5 (SCARA5) has been identified a novel tumor suppressor in several cancers. However, the functional and underlying mechanism of SCARA5 in bladder cancer (BC) need investigation. Here, we found SCARA5 expression was downregulated in both BC tissues and cell lines. Low SCARA5 in BC tissues was associated with a shorter overall survival. Moreover, SCARA5 overexpression reduced BC cell viability, colony formation, invasion, and migration. Further investigation demonstrated that the expression of SCARA5 was negatively regulated by miR-141. Furthermore, the long non-coding RNA prostate cancer associated transcript 29 (PCAT29) inhibited the proliferation, invasion, and migration of BC cells by sponging miR-141. Luciferase activity assays revealed that PCAT29 targeted miR-141 and miR-141 targeted SCARA5. In conclusion, SCARA5, as a downstream factor of the PCAT29/miR-141 axis, inhibited the proliferation, migration, and invasion of BC cells. These findings provide novel insights into the detailed molecular mechanisms of BC development., Competing Interests: Declaration of Competing Interest The authors declare that they have no competing interest., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

The opportunistic fungal pathogen Cryptococcus neoformans causes lethal infections in immunocompromised patients. Macrophages are central to the host response to cryptococci; however, it is unclear how C. neoformans is recognised and phagocytosed by macrophages. Here we investigate the role of TLR4 in the non-opsonic phagocytosis of C. neoformans. We find that loss of TLR4 function unexpectedly increases phagocytosis of non-opsonised cryptococci by murine and human macrophages. The increased phagocytosis observed in Tlr4 -/- cells was dampened by pre-treatment of macrophages with oxidised-LDL, a known ligand of scavenger receptors. The scavenger receptor, macrophage scavenger receptor 1 (MSR1) (also known as SR-A1 or CD204) was upregulated in Tlr4 -/- macrophages. Genetic ablation of MSR1 resulted in a 75% decrease in phagocytosis of non-opsonised cryptococci, strongly suggesting that it is a key non-opsonic receptor for this pathogen. We go on to show that MSR1-mediated uptake likely involves the formation of a multimolecular signalling complex involving FcγR leading to SYK, PI3K, p38 and ERK1/2 activation to drive actin remodelling and phagocytosis. Altogether, our data indicate a hitherto unidentified role for TLR4/MSR1 crosstalk in the non-opsonic phagocytosis of C. neoformans., (© 2023. Springer Nature Limited.)

Colorectal cancer (CRC) is the fourth most frequently diagnosed cancer worldwide. Bone marrow stromal cells (BMSCs) play an essential role in tumor development by secreting exosomes. Scavenger receptor class A member 5 (SCARA5) is a newly identified tumor suppressor. This study aimed to investigate the effects of BMSCs-derived exosomes (BMSCs-Exos) on CRC development and to explore their regulatory mechanisms. BMSCs-Exos showed an oval-shaped, bilayer membrane structure. BMSCs-Exos inhibited growth and motility of CRC cells, while BMSCs-Exos with SCARA5 knockdown significantly promoted cell proliferation and movement. Exosomal SCARA5 also effectively suppressed colorectal tumor growth in mouse xenografts. Further analysis revealed that exosomal SCARA5 inhibited the phosphorylation of protein kinase B and phosphoinositide 3-kinase in both CRC cells and tumors. In conclusion, SCARA5 in BMSCs-Exos inhibited CRC progression by inactivating PI3K/Akt, thus suggesting the potential clinical application of SCARA5-containing BMSCs-Exos for CRC treatment., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest., (Copyright © 2023. Published by Elsevier Inc.)

Background: SCARA5 may play an important role in nasopharyngeal carcinoma. Materials & methods: PCR and immunohistochemistry were used to detect the expression and promoter methylation of SCARA5 . Cell proliferation assays, spheroid culture, flow cytometry analysis, Transwell assays and xenotransplantation tests were utilized to determine the functional effects of SCARA5 . RNA-sequencing, western blotting, immunofluorescence and dual-luciferase reporter assays were used to assess SCARA5 -mediated outcomes. Results: SCARA5 was downregulated by promoter methylation. Overexpression of SCARA5 inhibited cell migration, invasion and proliferation. SCARA5 enhanced nasopharyngeal carcinoma cell sensitivity to chemotherapy with cisplatin and 5-fluorouracil. SCARA5 drives tumor apoptosis by downregulating HSPA2 . Conclusion: SCARA5 may be a useful clinical marker in nasopharyngeal carcinoma.

Background: CircRNAs are involved in the pathogenesis of several central nervous system diseases. However, their functions and mechanisms in spinal cord injury (SCI) are still unclear. Therefore, the purpose of this study was to evaluate circRNA and mRNA expression profiles in the pathological setting of SCI and to predict the potential function of circRNA through bioinformatics., Methods: A microarray-based approach was used for the simultaneous measurement of circRNAs and mRNAs, together with qPCR, fluorescence in situ hybridization, western immunoblotting, and dual-luciferase reporter assays to investigate the associated regulatory mechanisms in a rat SCI model., Results: SCI was found to be associated with the differential expression of 414 and 5337 circRNAs and mRNAs, respectively. Pathway enrichment analyses were used to predict the primary function of these circRNAs and mRNAs. GSEA analysis showed that differentially expressed mRNAs were primarily associated with inflammatory immune response activity. Further screening of these inflammation-associated genes was used to construct and analyze a competing endogenous RNA network. RNO_CIRCpedia_4214 was knocked down in vitro, resulting in reduced expression of Msr1, while the expression of RNO-miR-667-5p and Arg1 was increased. Dual-luciferase assays demonstrated that RNO_CIRCpedia_4214 bound to RNO-miR-667-5p. The RNO_CIRCpedia_4214/RNO-miR-667-5p/Msr1 axis may be a potential ceRNA that promotes macrophage M2-like polarization in SCI., Conclusion: Overall, these results highlighted the critical role that circRNAs may play in the pathophysiology of SCI and the discovery of a potential ceRNA mechanism based on novel circRNAs that regulates macrophage polarization, providing new targets for the treatment of SCI., (© 2023. The Author(s).)

Aim: This study aimed to elucidate the relationship between SCARA5 and RMRP in bladder cancer and their underlying mechanism. Methods: Biological functions were evaluated using cell-counting kit 8 assay, 5-ethynyl-2'-deoxyuridine incorporation, wound healing and Transwell assays. RNA immunoprecipitation, RNA pull-down and chromatin immunoprecipitation were employed. A xenograft tumor model in nude mice was also conducted. Results & conclusion: RMRP and SCARA5 exhibited an inverse correlation. Downregulation of RMRP significantly suppressed bladder cancer cell proliferation, migration and invasion, which was reversed by SCARA5 overexpression. RMRP recruited DNA methyltransferases to the promoter region of SCARA5 , thereby triggering the methylation of the SCARA5 promoter to epigenetically suppress its expression. Our findings elucidate the machinery by which RMRP , stabilized by METTL3, exerts a promoter role in bladder cancer tumorigenesis by triggering SCARA5 methylation.

Obesity induces a chronic inflammatory state associated with changes in adipose tissue macrophages (ATMs). Macrophage scavenger receptor 1 (MSR1) has been implicated in the regulation of adipose tissue inflammation and diabetes pathogenesis; however, reports have been mixed on the contribution of MSR1 in obesity and glucose intolerance. We observed increased MSR1 expression in VAT of obese diabetic individuals compared to non-diabetic and single nuclear RNA sequencing identified macrophage-specific expression of MSR1 in human adipose tissue. We examined male Msr1 -/- (Msr1KO) and WT controls and observed protection from obesity and AT inflammation in non-littermate Msr1KO mice. We then evaluated obese littermate Msr1 +/- (Msr1HET) and Msr1KO mice. Both Msr1KO mice and Msr1HET mice became obese and insulin resistant when compared to their normal chow diet counterparts, but there was no Msr1-dependent difference in body weight, glucose metabolism, or insulin resistance. Flow cytometry revealed no significant differences between genotypes in ATM subtypes or proliferation in male and female mice. We observed increased frequency of proliferating ATMs in obese female compared to male mice. Overall, we conclude that while MSR1 is a biomarker of diabetes status in human adipose tissue, in mice Msr1 is not required for obesity-associated insulin resistance or ATM accumulation., (© 2023. The Author(s).)

Hydrocephalus has been observed in rats with spontaneous hypertension (SHRs). It has been demonstrated that activation of the oxidative stress related protein retinoic acid receptor alpha (RARα) has neuroprotective impacts. Our investigation aims to determine the potential role and mechanism of RARα in hydrocephalus. The RARα-specific agonist (Am80) and RARα inhibitor (AGN196996) were used to investigate the role of RARα in cerebrospinal fluid (CSF) secretion in the choroid plexus of SHRs. Evaluations of CSF secretion, ventricular volume, Western blotting, and immunofluorescent staining were performed. Hydrocephalus and CSF hypersecretion were identified in SHRs but not in Wistar-Kyoto rats, occurring at the age of 7 weeks. The RARα/MAFB/MSR1 pathway was also activated in SHRs. Therapy with Am80 beginning in week 5 decreased CSF hypersecretion, hydrocephalus development, and pathological changes in choroid plexus alterations by week 7. AGN196996 abolished the effect of Am80. In conclusion, activation of the RARα attenuated CSF hypersecretion to inhibit hydrocephalus development via regulating the MAFB/MSR1 pathway. RARα may act as a possible therapeutic target for hydrocephalus.

Atherosclerotic plaques develop from the accumulation of macrophage-derived foam cells via the uptake of modified low-density lipoprotein (LDL). CD36 and CD204 are the principal scavenger receptors responsible for the uptake of modified LDL. Although glucocorticoids are suspected to exacerbate atherosclerosis, the precise mechanisms have not been fully elucidated. We investigated the effects of long-term treatment (2 weeks) with both a natural glucocorticoid (hydrocortisone, HC, 1 μM) and a synthetic glucocorticoid (dexamethasone, Dex, 100 nM) on murine bone marrow-derived macrophages using flow cytometry and western blotting. Treatment with HC and Dex enhanced CD204 expression but not CD36 expression and acetylated LDL (Ac-LDL) uptake. Treatment with HC and Dex also induced the phosphorylation of extracellular signal-regulated kinase (ERK). The Dex-induced enhancement in CD204 expression and Ac-LDL uptake were suppressed by an inhibitor of the mitogen-activated protein kinase (MAPK)/ERK kinase. These results suggest that glucocorticoids activate the MAPK/ERK pathway, which enhances CD204 expression and results in increased uptake of Ac-LDL in macrophages. The MAPK/ERK pathway in macrophages might be a key target to prevent atherosclerosis that is worsened by glucocorticoids., Competing Interests: Declaration of competing interest None declared., (Copyright © 2022 The Authors. Production and hosting by Elsevier B.V. All rights reserved.)

LncRNAs can be transported to tumor cells where they exert regulatory effects by bone marrow mesenchymal stem cells (BMSC)-derived exosomes. Here, we aimed to investigate the functional mechanism of BMSC-derived exosomal lncRNA PTENP1 in the progression of bladder cancer (BC). Methods of BMSC were identified by detecting surface markers through flow cytometry. Exosomes from BMSC were identified by transmission electron microscopy, nanoparticle tracking analysis (NTA), and western blot analysis of exosome markers. Cellular internalization of BMSC-derived exosomes (BMSC-Exo) into BC cells was detected by confocal microscopy. CCK-8, colony formation, flow cytometry, wound healing, and transwell assays were adopted to estimate cell proliferation, apoptosis, migration, and invasion abilities, respectively. Interplay between miR-17 and lncRNA PTENP1 or SCARA5 was verified by dual-luciferase reporter, RNA pull down, and/or RNA immunoprecipitation (RIP) assays. Tumor xenograft assay was conducted in nude mice to study the role of exosomal lncRNA PTENP1 in BC progression in vivo . We showed exosomal lncRNA PTENP1 can be delivered into and suppress the malignant phenotypes of BC cells. LncRNA PTENP1 was identified as a sponge of miR-17, and SCARA5 was identified as a target gene of miR-17. The exosomes derived from PTENP1-overexpressing BMSC (BMSC OE-PTENP1 -Exo) abolished the promotive effects of miR-17 overexpression or SCARA5 knockdown on the malignant phenotypes of BC cells. Moreover, exosomal lncRNA PTENP1 was demonstrated to inhibit BC tumor growth in nude mice by miR-17/SCARA5 axis. In conclusion, BMSC-derived exosomal PTENP1 suppressed the BC progression by upregulating the expression of SCARA5 via sponging miR-17, offering a potential novel therapeutic target for BC therapy.

microRNA-331-3p (miR-331-3p) has been displayed as an oncogene in pancreatic cancer (PC). The current research set out to elucidate how miR-331-3p in carcinoma-associated fibroblasts (CAFs)-derived extracellular vesicles (EVs) facilitated the tumorigenesis in PC. First, a dual-luciferase reporter assay was adopted to investigate the relationship between miR-331-3p and SCARA5. In addition, EVs were isolated normal fibroblasts and CAFs, and these isolated EVs were co-cultured with PC cells. Cell proliferative and migrating/invasive potentials were further evaluated with the help of a CCK-8 and Transwell assays, respectively. Gain- and loss-of-function assays were also implemented to assess the role of miR-331-3p, SCARA5, and FAK pathway in PC cells. Lastly, xenograft nude mice were established to investigate the role of miR-331-3p in vivo . miR-331-3p negatively targeted SCARA5 and was highly expressed in CAFs-derived EVs, which accelerated the proliferative, migrating, and invasive potentials of PC cells. Meanwhile, over-expression of miR-331-3p enhanced the proliferative, migrating, and invasive properties of PC cells and promoted tumor growth in vivo by manipulating SCARA5/FAK axis, whereas SCARA5 countered the oncogenic effects of miR-331-3p. Overall, miR-331-3p in CAFs-derived EVs inhibits SCARA5 expression and activates the FAK pathway, thereby augmenting the progression of PC. Our study provides a potential therapeutic target for the treatment of PC.

The innate immune system is the first line of host defense against microbial infections. During virus infection, pattern recognition receptors (PRRs) are engaged to detect specific viral components, such as viral RNA or DNA, and regulate the innate immune response in the infected cells or immune cells. Our previous study demonstrated that scavenger receptor A (SRA), an important innate PRR, impaired the anti-hepatitis B virus (HBV) response in hepatocytes. Given that SRA is primarily expressed in macrophages, here, we assessed the function of SRA expressed in macrophages in response to RNA or DNA viral infection. SRA-deficient (SRA -/- ) mice showed reduced susceptibility to viral infection caused by vesicular stomatitis virus (VSV) or herpes simplex virus 1 (HSV-1). In the virus-infected SRA -/- mice, compared with their wild-type (WT) counterparts, we observed low amounts of virus accompanied by enhanced interferon (IFN) production. Furthermore, SRA significantly inhibited the phosphorylation of TANK-binding kinase 1 (TBK1) and interferon regulatory factor 3 (IRF3). We provided biochemical evidence showing that SRA directly interacts with the N-terminal kinase domain (KD) of TBK1, resulting in the limitation of its K63-linked ubiquitination. Moreover, we demonstrated that SRA negatively regulates the activity of TBK1 by promoting the recruitment of ubiquitin-specific protease 15 (USP15) to deubiquitinate TBK1. In summary, we have identified the connection between SRA and the TBK1/IRF3 signaling pathway in macrophages, indicating a critical role of SRA in the regulation of host antiviral immunity. IMPORTANCE During virus infection, PRRs are engaged to detect specific viral components, such as viral RNA or DNA, and regulate the innate immune response in the infected cells or other immune cells. We reported that deficiency of SRA, an important innate PRR, promoted IRF3 activation, type I IFN production, and innate antiviral responses against RNA and DNA viruses in vivo and in vitro . Furthermore, the biochemical analysis showed that SRA directly interacts with the KD domain of TBK1 and limits its K63-linked polyubiquitination, reducing TBK1 activation. Further analyses determined that SRA is a modulator for TBK1 activation via the recruitment of USP15, which delineated a previously unrecognized function for SRA in innate antiviral immunity.

Hyperferritinemic syndrome, an overwhelming inflammatory condition, is characterized by high ferritin levels, systemic inflammation and multi-organ dysfunction, but the pathogenic role of ferritin remains largely unknown. Here we show in an animal model that ferritin administration leads to systemic and hepatic inflammation characterized by excessive neutrophil leukocyte infiltration and neutrophil extracellular trap (NET) formation in the liver tissue. Ferritin-induced NET formation depends on the expression of peptidylarginine deiminase 4 and neutrophil elastase and on reactive oxygen species production. Mechanistically, ferritin exposure increases both overall and cell surface expression of Msr1 on neutrophil leukocytes, and also acts as ligand to Msr1 to trigger the NET formation pathway. Depletion of neutrophil leukocytes or ablation of Msr1 protect mice from tissue damage and the hyperinflammatory response, which further confirms the role of Msr1 as ferritin receptor. The relevance of the animal model is underscored by the observation that enhanced NET formation, increased Msr1 expression and signalling on neutrophil leukocytes are also characteristic to adult-onset Still's disease (AOSD), a typical hyperferritinemic syndrome. Collectively, our findings demonstrate an essential role of ferritin in NET-mediated cytokine storm, and suggest that targeting NETs or Msr1 may benefit AOSD patients., (© 2022. The Author(s).)

Background: M2 macrophages play an important role in gastric cancer progression and metastasis, but the underlying tumor-promoting mechanisms are largely unknown., Methods: The TCIA database was used to identify the infiltration profile of macrophages. Integrated ATAC-seq, RNA-seq, and single-cell RNA sequencing (scRNA-seq) data from GC samples were used for the analysis. Using ATAC-seq profiles and RNA-seq datasets, combined with cox univariate survival analysis, we identified prognosis-related differentially expressed genes (DEGs) with chromatin accessibility, which were identified as hub genes. The CIBERSORTx algorithm was utilized to estimate the relative infiltration level of M2 macrophages, and Pearson correlation analysis was performed to investigate the relationship between hub genes and M2 macrophages. Multidimensional database validations were carried out to avoid biases. The expression level and function of hub genes in the clusters of macrophages were evaluated by using scRNA-seq data. The role of hub genes in the alternative activation of macrophages and gastric cancer malignant behaviors, as well as their potential regulatory mechanism in gastric cancer progression, were further explored., Results: 17,334 genes were acquired with chromatin accessibility in promoter regions by ATAC-seq. 2,714 genes were identified with both chromatin accessibility and differential expression based on the gene expression profiles (RNA-seq). By performing Cox univariate survival analysis, 171 survival-related DEGs with chromatin accessibility were identified as hub genes. Through the CIBERSORTx algorithm and Pearson correlation analysis, the gene MSR1 most associated with M2 macrophages was screened out. According to the scRNA-seq analysis, MSR1 was highly expressed in the clusters of macrophages and may be involved in regulating M2 macrophage polarization. In vitro experiments confirmed that M2 macrophage polarization and its induced malignant behavior of gastric cancer cells were inhibited by knockdown of MSR1. Furthermore, MSR1 mediated M2 macrophage polarization by regulating arginine and proline metabolism, thereby activating the AMPK/mTOR pathway to promote gastric cancer progression., Conclusion: We identified a gene-MSR1-characterized by chromatin accessibility, associated with poor prognosis in gastric cancer. This gene dictates the progression of gastric cancer by facilitating M2 macrophage polarization., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Author(s). Published by Elsevier B.V. All rights reserved.)

Macrophage scavenger receptor 1 (MSR1), also named CD204, holds key inflammatory roles in multiple pathophysiologic processes. Present primarily on the surface of various types of macrophage, this receptor variably affects processes such as atherosclerosis, innate and adaptive immunity, lung and liver disease, and more recently, cancer. As highlighted throughout this review, the role of MSR1 is often dichotomous, being either host protective or detrimental to the pathogenesis of disease. We will discuss the role of MSR1 in health and disease with a focus on the molecular mechanisms influencing MSR1 expression, how altered expression affects disease process and macrophage function, the limited cell signalling pathways discovered thus far, the emerging role of MSR1 in tumour associated macrophages as well as the therapeutic potential of targeting MSR1., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Gudgeon, Marín-Rubio and Trost.)

Background: Fibroblasts are important structural cells in synovium and play key roles in maintaining the synovial homeostasis. By single-cell RNA sequencing (scRNA-seq), subpopulation of synovium-resident cells has been reported to protect intra-articular structures from chronic inflammation and promote tissue repair. However, a significant number of researchers have concentrated on the role of fibroblasts in the progress of rheumatoid arthritis (RA) while few reports had described the contribution of distinct fibroblast subsets in the RA remission. It is helpful to understand the role of fibroblast subpopulations in the RA process to provide predictive biomarkers and address RA remission mechanisms. Here, we found HBEGF+ fibroblasts that contributed to RA remission by integrating scRNA-seq datasets and bulk RNA sequencing (bulk RNA-seq) datasets., Method: Three single-cell RNA datasets of cells harvested from RA patients were processed and integrated by Seurat and Harmony R packages. After identifying cell types by classic marker genes, the integrated dataset was used to run CellChat for analysis of cell-cell communication. Specially, EGF signaling pathway was found and HBEGF+ fibroblasts were identified based on HBEGF expression. Differential expressed genes of HBEGF+ were shown in heatmap and volcano plot and used to run gene ontology (GO) enrichment analysis. Next, bulk RNA-seq datasets of synovium under different conditions (health, osteoarthritis (OA), rheumatoid arthritis, before and after classical treatment) were compared to show expression change of HBEGF and gene markers that are mainly expressed by HBEGF+ fibroblasts such as CLIC5, PDGFD, BDH2, and ENPP1. Finally, two single-cell RNA sequencing datasets of synovial cells from mice were integrated to identify Hbegf+ fibroblasts and calculate the population of Hbegf+ fibroblasts under different joint conditions (health, K/BxN serum transfer arthritis (STA), and remission of STA)., Result: After integrating three single-cell RNA sequencing datasets, we identified 11 clusters of synovial cells, such as fibroblasts, mural cells, endothelial cells, CD4+ T cells, CD8+ T cells, natural killer cells, synovium macrophage, peripheral blood macrophages, plasma cells, B cells, and STMN1+ cells. We found fibroblasts had an extensive communication network with other clusters and interacted with synovial macrophages through EGF signaling pathway via analysis of cell-cell communication between synovial cells. HBEGF, ligand to EGF signaling pathway, was highly expressed by a subset of fibroblasts and macrophages, and EGFR, receptor to EGF signaling pathway, was highly expressed by fibroblasts and meniscus cells. Moreover, HBEGF was downregulated under RA state and it had an increase after classical treatment. We then defined fibroblasts with high expression of HBEGF as HBEGF+ fibroblasts. In addition, we also found that HBEGF+ fibroblasts highly expressed CRTAC1, ITGB8, SCARA5, THBS4, and ITGBL1, genes relative to encoding extracellular matrix proteins and engaged in positive regulation of cell migration and motility, cellular component movement, and cell growth by GO enrichment analysis. We eventually identified HBEGF+ fibroblasts specially expressed CLIC5, PDGFD, BDH2, and ENPP1, which positively correlated with the expression of HBEGF. Moreover, the expression of CLIC5, PDGFD, BDH2, and ENPP1 was downregulated under RA state and elevated by classical therapy. On the contrary, the HBEGF+ macrophages specially expressed SLAMF8, GK, L1RN, and JAK2, which negatively correlated with the expression of HBEGF. The expression was upregulated in SLAMF8, GK, L1RN, and JAK2 under the RA state, whereas it was decreased after classical treatment. In mice, the number of Hbegf+ fibroblasts was reduced in the RA synovium but increased in the RA remitting synovium., Conclusions: HBEGF+ fibroblasts play a role in the remission of rheumatoid arthritis, and HBEGF has potential to become a novel biomarker for prediction of RA progress., (© 2022. The Author(s).)

Scavenger receptors (SRs) have been shown to participate in regulating the immune response of macrophages, and fucoidan from Fucus vesiculosus has been verified as a ligand of class A SRs (SR-A). However, the roles of SRs in the immunomodulatory activity of fucoidan from Saccharina japonica are not clear. Thus, we performed a comparative study of the immunomodulatory activities of six different fucoidans from S. japonica on RAW 264.7 macrophages, and the roles of SRs in the processes were studied. Six fucoidans (0.5 M FPS, 1 M FPS, 2 M FPS, 0.5 M DFPS, 1 M DFPS and 2 M FPS) had different molecular weights and chemical compositions. Griess reagent system, ELISA and RT-qPCR results showed that different fucoidans displayed different stimulation of macrophages to secrete NO, IL-6, IL-1β and TNF-α, as well as differences in the upregulation of their gene expressiones. Flow cytometric analysis of the protein expression level indicated the upregulation of TLR4 after treatment with all the fucoidans but different expressions of SRs. Furthermore, only 0.5 M DFPS and 1 M DFPS were confirmed to be ligands of SR-A through the competitive binding assay with Ac-LDL bound to the fluorescent probe DiI by flow cytometry. Our results revealed that fucoidans with low molecular weight and heterogeneity more easily bound to SRs and contributed to their immunomodulatory effects. This comparative study might promote the biological study of targeted SRs and the discovery of new pharmacological mechanisms of different fucoidans., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Dermal papilla (DP) cells regulate hair follicle epithelial cells and melanocytes by secreting functional factors, playing a key role in hair follicle morphogenesis and hair growth. DP cells can reconstitute new hair follicles and induce hair regeneration, providing a potential therapeutic strategy for treating hair loss. However, current methods for isolating DP cells are either inefficient (physical microdissection) or only applied to genetically labeled mice. We systematically screened for the surface proteins specifically expressed in skin DP using mRNA expression databases. We identified two antibodies against receptors LEPTIN Receptor (LEPR ) and Scavenger Receptor Class A Member 5 (SCARA5) which could specifically label and isolate DP cells by flow cytometry from mice back skin at the growth phase. The sorted LEPR + cells maintained the DP characteristics after culturing in vitro, expressing DP marker alkaline phosphatase and functional factors including RSPO1/2 and EDN3, the three major DP secretory factors that regulate hair follicle epithelial cells and melanocytes. Furthermore, the low-passage LEPR + DP cells could reconstitute hair follicles on nude mice using chamber graft assay when combined with epithelial stem cells. The method of isolating functional DP cells we established here lays a solid foundation for developing DP cell-based therapy., (© 2022 International Society for Advancement of Cytometry.)

First discovered on macrophages by Goldstein and Brown in 1979, Scavenger Receptors have since been shown to participate in a diverse number of cell functions; equally diverse are their structures and the ligands they bind. Macrophage activation is crucial in the outcome of an immune response. SR-A1 is highly abundant on macrophages and recognizes both host- and microorganism-derived molecules that impact processes that are initiated, perpetuated, or modified. This review summarizes the involvement of SR-A1 in both inflammatory and anti-inflammatory responses, the multiple-ligand internalization mechanisms and the diversity of signaling pathways that impact macrophage function and activation. Engagement of SR-A1 results in the stimulation of differential signaling pathways and patterns of cytokine expression, kinetics, magnitude of response and activation status. SR-A1 plays essential roles in phagocytosis and efferocytosis, interacting with other receptors and promoting tolerance in response to apoptotic cell uptake. In cell adhesion, tissue remodeling, and cell migration, SR-A1 signals through different pathways engaging different cytoplasmic motifs. We describe the role of SR-A1 during innate and adaptive immune responses, such as participation in macrophage polarization and interaction with other innate receptors, as well as in antigen uptake, processing, and presentation, regulating T and B cell activation. The dichotomous contribution of SR-A1 on macrophage functions is discussed. A better understanding of the role SR-A1 plays through molecular mechanisms and crosstalk with other receptors may provide insights into developing novel therapeutic strategies to modulate immune responses and immunopathologies.

The nonunion following a fracture is associated with severe patient morbidity and economic consequences. Currently, accumulating studies are focusing on the importance of macrophages during fracture repair. However, details regarding the process by which macrophages facilitate endochondral ossification (EO) are largely unknown. In this study, we present evidence that apoptotic chondrocytes (ACs) are not inert corpses awaiting removal, but positively modulate the osteoinductive ability of macrophages. In vivo experiments revealed that fatty acid (FA) metabolic processes up-regulated following EO. In vitro studies further uncovered that FAs derived from ACs are taken up by macrophages mainly through macrophage scavenger receptor 1 (MSR1). Then, our functional experiments confirmed that these exogenous FAs subsequently activate peroxisome proliferator-activated receptor α (PPARα), which further facilitates lipid droplets generation and fatty acid oxidation (FAO). Mechanistically, elevated FAO is involved in up-regulating the osteoinductive effect by generating BMP7 and NAD + /SIRT1/EZH2 axis epigenetically controls BMP7 expression in macrophages cultured with ACs culture medium. Our findings advanced the concept that ACs could promote bone regeneration by regulating metabolic and function reprogram in macrophages and identified macrophage MSR1 represents a valuable target for fracture treatments., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Purpose: We previously reported that a calpain inhibitor (CAI) prevents the development of atherosclerosis in rats. This study aimed to investigate the effects of CAI (1 mg/kg) on atherosclerosis in apolipoprotein E knockout (ApoE KO) mice that were fed a high-fat diet (HFD) and explore the underlying mechanism by analyzing the expression of genes related to the uptake and efflux of cholesterol., Methods: Atherosclerotic plaques were evaluated. The activity of calpain in the aorta and that of superoxide dismutase (SOD) in the serum were assessed. Lipid profiles in the serum and liver were examined. Serum oxidized low-density lipoprotein (oxLDL), malondialdehyde (MDA), tumor necrosis factor (TNF-α), and interleukin-6 (IL-6) levels were measured. The mRNA expressions of CD68, TNF-α, IL-6, CD36, scavenger receptor (SR-A), peroxisome proliferator-activated receptor gamma (PPAR-γ), liver-x-receptor alpha (LXR-α), and ATP-binding cassette transporter class A1 (ABCA1) in the aorta and peritoneal macrophages were also evaluated., Results: CAI reduced calpain activity in the aorta. CAI also impeded atherosclerotic lesion formation and mRNA expression of CD68 in the aorta and peritoneal macrophages of ApoE KO mice compared with those of mice receiving HFD. However, CAI had no effect on body weight and lipid levels in both the serum and liver. CAI significantly decreased MDA, oxLDL, TNF-α, and IL-6 levels and increased SOD activity in the serum. Moreover, CAI significantly inhibited the mRNA expression of TNF-α and IL-6 genes in the aorta and peritoneal macrophages. In addition, CAI significantly downregulated the mRNA expression of scavenger receptors CD36 and SR-A and upregulated the expression of genes involved in the cholesterol efflux pathway, i.e., PPAR-γ, LXR-α, and ABCA1 in the aorta and peritoneal macrophages., Conclusions: CAI inhibited the development of atherosclerotic lesions in ApoE KO mice, and this effect might be related to the reduction of oxidative stress and inflammation and the improvement of cholesterol intake and efflux pathways., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: We examined the relationship between the tumour microenvironment and the clinical efficacy of neoadjuvant chemotherapy in patients with cT2-4aN0M0 bladder cancer using multiplex fluorescence immunohistochemistry., Methods: The study retrospectively evaluated 51 patients who underwent radical cystectomy following neoadjuvant chemotherapy for cT2-4aN0M0 muscle-invasive bladder cancer. Patients were divided into responders (+ T cell (p = 0.0056) and CD204 + cell (p = 0.0394) densities were significantly higher in the intratumoural area in non-responders than in responders. Patients with higher CD204 + cell densities in cancerous areas had worse prognosis., Conclusions: This comprehensive analysis of the immune microenvironment of a muscle-invasive bladder cancer specimen revealed that preexisting tumour-infiltrating proliferating CD8 + T cells and CD204 + cells are indicators of the response to neoadjuvant chemotherapy and that CD204 + cells can be considered an unfavourable prognostic factor in these patients., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Background: In mouse models of amyloidosis, macrophage receptor 1 (MSR1) and neprilysin (NEP) have been shown to interact to reduce amyloid burden in the brain., Objective: The purpose of this study is to analyze these two gene products in combination with apolipoproteins and Aβ1-42 in the cerebrospinal fluid (CSF) and plasma of individuals at different stages of Alzheimer's disease (AD), as well as in autopsied brain samples from ROSMAP (Religious Orders Study and Memory and Aging Project)., Methods: CSF/plasma levels of MSR1 and NEP were measured using the sensitive primer extension assay technology. CSF Aβ1-42 was assessed with ELISA, while CSF ApoE and ApoJ were measured with the Luminex's multiplex technology. Brain MSR1, APOE, and CLU (APOJ) mRNA levels were measured with RNA-Seq and contrasted to amyloid plaques pathology using CERAD staging., Results: While plasma and CSF MSR1 levels are significantly correlated, this correlation was not observed for NEP. In addition to be highly correlated to one another, CSF levels of both MSR1 and NEP are strongly correlated with AD status and CSF Aβ1-42, ApoE, and ApoJ levels. In the cortical tissues of subjects from ROSMAP, MSR1 mRNA levels are correlated with CLU mRNA levels and the CERAD scores but not with APOE mRNA levels., Conclusion: The discrepancies observed between CSF/plasma levels of MSR1 and NEP with CSF Aβ1-42 and ApoE concentrations can be explained by many factors, such as the disease stage or the involvement of the blood-brain barrier breakdown that leads to the infiltration of peripheral monocytes or macrophages.

Leptospirosis, caused by pathogenic Leptospira species, has emerged as a widespread zoonotic disease worldwide. Macrophages mediate the elimination of pathogens through phagocytosis and cytokine production. Scavenger receptor A1 (SR-A1), one of the critical receptors mediating this process, plays a complicated role in innate immunity. However, the role of SR-A1 in the immune response against pathogenic Leptospira invasion is unknown. In the present study, we found that SR-A1 is an important nonopsonic phagocytic receptor on murine macrophages for Leptospira . However, intraperitoneal injection of leptospires into WT mice presented with more apparent jaundice, subcutaneous hemorrhaging, and higher bacteria burdens in blood and tissues than that of SR-A1 -/- mice. Exacerbated cytokine and inflammatory mediator levels were also observed in WT mice and higher recruited macrophages in the liver than those of SR-A1 -/- mice. Our findings collectively reveal that although beneficial in the uptake of Leptospira by macrophage, SR-A1 might be exploited by Leptospira to modulate inflammatory activation and increase the susceptibility of infection in the host. These results provide our new insights into the innate immune response during early infection by L. interrogans .

To stratify the heterogeneity of prostate cancer (PCa) with seminal vesicle invasion (SVI) immunologically after radical prostatectomy focusing on the tumor microenvironment. We retrospectively reviewed the clinicopathological data of 71 PCa patients with SVI, which is known as a factor of very high-risk PCa. Preoperative clinical variables and postoperative pathological variables were evaluated as predictors of biochemical recurrence (BCR) with a multivariate logistic regression. Immune cell infiltration including the CD8-positive cell (CD8 + cell) and CD204-positive M2-like macrophage (CD204 + cell) was investigated by immunohistochemistry. The cumulative incidence and risk of BCR were assessed with a Kaplan-Meier analysis and competing risks regression. A higher CD8 + cell count in the SVI area significantly indicated a favorable prognosis for cancers with SVI (p = 0.004). A lower CD204 + cell count in the SVI area also significantly indicated a favorable prognosis for cancers with SVI (p = 0.004). Furthermore, the combination of the CD8 + and CD204 + cell infiltration ratio of the SVI area to the main tumor area was a significant factor for BCR in the patients with the PCa with SVI (p = 0.001). In PCa patients with SVI, the combination of CD8 + and CD204 + cell infiltration is useful to predict the prognosis., (© 2021. The Author(s).)

Retinitis pigmentosa 11 (RP11) is caused by dominant mutations in PRPF31 , however a significant proportion of mutation carriers do not develop retinopathy. Here, we investigated the relationship between CNOT3 polymorphism, MSR1 repeat copy number and disease penetrance in RP11 patients and non-penetrant carriers (NPCs). We further characterized PRPF31 and CNOT3 expression in fibroblasts from eight RP11 patients and one NPC from a family carrying the c.1205C>T variant. Retinal organoids (ROs) and retinal pigment epithelium (RPE) were differentiated from induced pluripotent stem cells derived from RP11 patients, an NPC and a control subject. All RP11 patients were homozygous for the 3-copy MSR1 repeat in the PRPF31 promoter, while 3/5 NPCs carried a 4-copy MSR1 repeat. The CNOT3 rs4806718 genotype did not correlate with disease penetrance. PRFP31 expression declined with age in adult cadaveric retina. PRPF31 and CNOT3 expression was reduced in RP11 fibroblasts, RO and RPE compared with controls. Both RP11 and NPC RPE displayed shortened primary cilia compared with controls, however a subpopulation of cells with normal cilia lengths was present in NPC RPE monolayers. Our results indicate that RP11 non-penetrance is associated with the inheritance of a 4-copy MSR1 repeat, but not with CNOT3 polymorphisms.

Atherosclerosis is one of the most common cardiovascular diseases with highly mortality worldwide. The formation of foam cell plays an important role in the early stage of atherosclerosis pathogenesis. L-theanine is the most abundant free amino acid in tea, which possesses anti-inflammatory, anti-tumor and anti-atherosclerosis effects. However, little is known about the effects of L-theanine on the foam cell formation. In our study, RAW264.7 cells and primary mouse peritoneal macrophages were exposed to oxidized low density lipoprotein (ox-LDL) for inducing foam cell formation. We found that L-theanine significantly impeded cholesterol accumulation in macrophages, while inhibiting the formation of foam cell. Our further experiments showed that L-theanine attenuated the cholesterol uptake of RAW264.7 cells and primary mouse peritoneal macrophages by reducing the protein level of macrophage scavenger receptor A (SR-A), but not the level of mRNA suggesting that L-theanine regulates scavenger receptor A at the translational rather than transcriptional level. The present results demonstrated that L-theanine obviously promoted the degradation of scavenger receptor A protein and scavenger receptor A was degraded by ubiquitination dependent manner. Collectively, our research indicates that L-theanine suppresses the formation of macrophage foam cell by promoting the ubiquitination dependent degradation of scavenger receptor A., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Objectives: Scavenger receptor class A, member 3 (Scara3) was involved in adipogenesis. However, the effect of Scara3 on the switch between osteogenesis and adipogenesis of bone marrow mesenchymal stem cells (BMSCs) remains elusive., Materials and Methods: The correlations between SCARA3 with the osteogenic-related were analysed based on the GTEx database. The effects of Scara3 on osteogenic or adipogenic differentiation of BMSCs were evaluated by qPCR, Western blot (WB) and cell staining. The mechanisms of Scara3 regulating Foxo1 and autophagy were validated by co-expression analysis, WB and immunofluorescence. In vivo, Scara3 adeno-associated virus was injected into intra-bone marrow of the aged mice and ovariectomized (OVX) mice whose phenotypes were confirmed by micro-CT, calcein double labelling and immunochemistry (HE and OCN staining)., Results: SCARA3 was positively correlated with osteogenic-related genes. Scara3 expression gradually decreased during adipogenesis but increased during osteogenesis. Moreover, the deletion of Scara3 favoured adipogenesis over osteogenesis, whereas overexpression of Scara3 significantly enhanced the osteogenesis at the expense of adipogenesis. Mechanistically, Scara3 controlled the cell fate by promoting Foxo1 expression and autophagy flux. In vivo, Scara3 promoted bone formation and reduced bone marrow fat accumulation in OVX mice. In the aged mice, Scara3 overexpression alleviated bone loss as well., Conclusions: This study suggested that Scara3 regulated the switch between adipocyte and osteoblast differentiation, which represented a potential therapeutic target for bone loss and osteoporosis., (© 2021 The Authors. Cell Proliferation published by John Wiley & Sons Ltd.)

This study aims to determine the correlation between the percent viable tumor cells (%VTC) and the tumor microenvironment in resected non-small cell lung cancer after induction therapy. We enrolled 72 patients with non-small cell lung cancer (NSCLC) who received chemoradiotherapy (CRT) or chemotherapy (CT) prior to surgery. The ratio of the area of viable tumor cells to the total tumor area was calculated to obtain the %VTC. We also examined the number of CD4 (+), CD8 (+), CD20 (+) and FOXP3 (+) tumor-infiltrating lymphocytes (TILs), podoplanin (PDPN) (+) cancer-associated fibroblasts (CAFs), and CD204 (+) tumor-associated macrophages (TAMs) by immunohistochemistry (IHC). In the CRT group (n = 37), the tumors had significantly lower %VTC than the CT group (n = 35) (P < 0.001). In both of the CT group and CRT group, the %VTC showed a significant positive correlation with the number of CD204 (+)-TAMs (P = 0.014 and 0.005, respectively). Only in the CRT group, a higher number of CD204 (+) TAMs was associated with a shorter overall survival (OS) (P = 0.007) and recurrence-free survival (RFS) (P = 0.015). In the CRT group, the number of CD204 (+) TAMs is associated with %VTC and prognosis, suggesting that these cells may have tumor-promoting effects on the residual lung cancer in specific microenvironments after CRT., (© 2021 Japanese Society of Pathology and John Wiley & Sons Australia, Ltd.)

The progression of prion diseases is accompanied by the accumulation of prions in the brain. Ablation of microglia enhances prion accumulation and accelerates disease progression, suggesting that microglia play a neuroprotective role by clearing prions. However, the mechanisms underlying the phagocytosis and clearance of prion are largely unknown. The macrophage scavenger receptor 1 (Msr1) is an important phagocytic receptor expressed by microglia in the brain and is involved in the uptake and clearance of soluble amyloid-β. We therefore asked whether Msr1 might play a role in prion clearance and assessed the scavenger function of Msr1 in prion pathogenesis. We found that Msr1 expression was upregulated in prion-infected mouse brains. However, Msr1 deficiency did not change prion disease progression or lesion patterns. Prion deposition in Msr1 deficient mice was similar to their wild-type littermates. In addition, prion-induced neuroinflammation was not affected by Msr1 ablation. We conclude that Msr1 does not play a major role in prion pathogenesis. KEY MESSAGES: Msr1 expression is upregulated in prion-infected mouse brains at the terminal stage Msr1 deficiency does not affect prion disease progression Msr1 does not play a major role in prion clearance or prion pathogenesis Microglia-mediated phagocytosis and clearance of Aβ and prion may adopt distinct molecular pathways.

The macrophage scavenger receptor 1 (MSR1)-induced resolution of neuroinflammation may be a novel therapeutic strategy for ischemic stroke. Our previous study showed that the neuroprotective and anti-inflammatory effects of phthalide are associated with the inhibition of the post-ischemic damage-associated molecular pattern (DAMP)/Toll-like receptor 4 (TLR4) pathway. This study investigated the effects of the phthalide derivative CD21 on ischemic brain injury and the mechanism underlying MSR1-induced resolution of neuroinflammation. Using a rat model of 2 h transient middle cerebral artery occlusion (MCAO), MSR1-induced peroxiredoxin1 (PRX1) clearance in RAW264.7 macrophages were investigated. We show here that CD21 significantly ameliorated infarct volumes and neurological deficits in a dose-dependent manner with a ≥ 12 h therapeutic time window. Moreover, administration of 5 mg/kg/day CD21 over 24 h significantly reduced pathological damages, with associated inhibition of PRX1 expression, reduced TLR4/nuclear factor-κB activation and the suppression of the inflammatory response in MCAO rats. Furthermore, the expression of MAFB/MSR1 in the ischemic brain was elevated and the phagocytosis of PRX1 in CD68-positive macrophages isolated from the ischemic brain was enhanced. Further in vitro studies show that CD21 (20 μM) strongly enhanced the Msr1 mRNA and MSR1 protein levers in RAW264.7 cells and PRX1 internalization in cellular lysosomes, which were significantly reversed by N-acetylcysteine treatment. These results suggest that CD21 may exert neuroprotective and anti-inflammatory effects with a wide time window for the treatment of ischemic stroke. The anti-stroke effects of CD21 appear to be mediated partially via the induction of MSR1-promoted DAMP (PRX1) clearance, TLR4/nuclear factor-κB pathway inhibition, and the resolution of inflammation. Graphical Abstract The neuroprotective action of CD21 was associated with the resolution of neuroinflammation through enhancement of the MAFB-MSR1 pathway that leads to DAMP (PRX1) phagocytosis and TLR4 pathway inhibition. Red solid arrows represent promotion, red dotted arrow represents the positive correlation, green arrows represent inhibition.

Despite the efficient uptake of polypod-like nanostructured DNA, or polypodna, by macrophage-like RAW264.7 and other immune cells, the detailed mechanism has not been fully elucidated. Our previous study using HEK-Blue hTLR9 cells showed that transfection of macrophage scavenger receptor 1 (MSR1) increased the uptake of tetrapod-like structured DNA. Here, we investigated the involvement of MSR1 in the structure-dependent uptake of polypodna. Transfection of MSR1 to HEK-Blue hTLR9 cells pod number-dependently increased the uptake of polypodna, and its knockout in RAW264.7 cells reduced the uptake and subsequent cytokine release. To examine the binding of DNA with MSR1, biotinylated DNA added to RAW264.7 cells was cross-linked with cell surface proteins. Then, MSR1 cross-linked with polypodna, but not with single-stranded DNA. Similar results were obtained with murine primary immune cells. Taken together, MSR1 discriminates between simple and nanostructured DNAs and plays a dominant role in the efficient uptake of polypodna by immune cells., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Scavenger receptors clear pathogens, transport lipid, and mediate polyanionic ligand uptake in macrophages, but their expression and role in the skin are poorly understood. Although the epidermal barrier typically excludes nucleic acid entry, topically applied, spherically arranged oligonucleotide nanoconjugates (spherical nucleic acids [SNAs]) penetrate mouse skin, three-dimensional (3D) skin equivalents, and human skin. We explored the mechanism of SNA uptake in normal human epidermal keratinocytes and 3D skin equivalents. Normal human epidermal keratinocytes and 3D raft treatment with SR-A inhibitors reduced SNA uptake by >80%. The human epidermis expresses SR-As SCARA3 and, to a lesser extent, MARCO. Simultaneous lentiviral knockdown of SCARA3 and MARCO reduced SNA uptake in normal human epidermal keratinocytes and 3D rafts after topical application, affirming a role for SR-As in SNA uptake and 3D raft penetration. Incubation of normal human epidermal keratinocytes at 4 o C or with sodium azide prevented SNA uptake, suggesting active endocytosis. Endocytosis inhibitors, immunofluorescence, immunoprecipitation, and knockdown studies localized functional SR-As to FLOT-1-containing lipid rafts throughout the epidermis and CAV-1-containing rafts only in the upper epidermis. These studies suggest a central role for SR-A complexes in epidermal lipid rafts in mediating the uptake of nucleic acid‒laden nanoparticles., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Scope: β-lactoglobulin (BLG) is a major cow milk allergen encountered by the immune system of infants fed with milk-based formulas. To determine the effect of processing on immunogenicity of BLG, this article characterized how heated and glycated BLG are recognized and internalized by APCs. Also, the effect of heat-induced structural changes as well as gastrointestinal digestion on immunogenicity of BLG is evaluated., Methods and Results: The binding and uptake of BLG from raw cow milk and heated either alone (BLG-H) or with lactose/glucose (BLG-Lac and BLG-Glu) to the receptors present on APCs are analyzed by ELISA and cell-binding assays. Heated and glycated BLG is internalized via galectin-3 (Gal-3)and scavenger receptors (CD36 and SR-AI) while binding to the receptor for advanced glycation end products (R AGE) does not cause internalization. Receptor affinity of BLG is dependent on increased hydrophobicity, β-sheet exposure and aggregation. Digested glycated BLG maintained binding to sRAGE and Gal-3 but not to CD36 and SR-AI, and is detected on the surface of APCs. This suggests a mechanism via which digested glycated BLG may trigger innate (via RAGE) and adaptive immunity (via Gal-3)., Conclusions: This study defines structural characteristics of heated and glycated BLG determining its interaction with APCs via specific receptors thus revealing enhanced immunogenicity of glycated versus heated BLG., (© 2021 The Authors. Molecular Nutrition & Food Research published by Wiley-VCH GmbH.)

Circulating tumor cells (CTC) can be isolated via a minimally invasive blood draw and are considered a "liquid biopsy" of their originating solid tumors. CTCs contain a small subset of metastatic precursors that can form metastases in secondary organs and provide a resource to identify mechanisms underlying metastasis-initiating properties. Despite technological advancements that allow for highly sensitive approaches of detection and isolation, CTCs are very rare and often present as single cells, posing an extreme challenge for ex vivo expansion after isolation. Here, using previously established patient-derived CTC lines, we performed a small-molecule drug screen to identify compounds that can improve ex vivo culture efficiency for single CTCs. We found that N-acetyl-L-cysteine (NAC) and other antioxidants can promote ex vivo expansion of single CTCs, by reducing oxidative and other stress particularly at the initial stage of single-cell expansion. RNA-seq analysis of growing clones and nongrowing clones confirmed the effect by NAC, but also indicates that NAC-induced decrease in oxidative stress is insufficient for promoting proliferation of a subset of cells with predominant senescent features. Despite the challenge in expanding all CTCs, NAC treatment led to establishment of single CTC clones that have similar tumorigenic features. IMPLICATIONS: Through a small molecule screen and validation study, we found that NAC could improve the success of ex vivo expansion of single CTCs by mitigating the initial stress, with the potential to facilitate the investigation of functional heterogeneity in CTCs., (©2020 American Association for Cancer Research.)

Retinoblastoma (RB) is the most common ocular malignancy that occurs during childhood. Scavenger receptor class A member 5 (SCARA5) is considered to function as an anti‑oncogene in several types of malignant tumor. The present study investigated the functional role and underlying mechanism of SCARA5 in human RB cells. Reverse transcription‑quantitative PCR and western blotting were used to detect the relative expression levels of SCARA5 in four human RB cell lines. In addition, transfection was performed to either knockdown or induce overexpression of SCARA5 in human RB Y79 cells. The proliferation, migration and apoptosis of RB cells was then measured by Cell Counting Kit 8 assay, 5‑ethynyl‑2'‑deoxyuridine assay, clone formation assay, Transwell assay, Hoechst staining and TUNEL staining, respectively. Western blotting was performed to detect changes in the expression levels of key proteins involved in the PI3K/AKT and apoptotic pathways. The present study revealed that SCARA5 was expressed at lower levels in four tumorigenic human RB cell lines compared with in a human retinal pigment non‑tumorigenic cell line. Functional analysis demonstrated that overexpression of SCARA5 decreased the proliferation and migration, and promoted the apoptosis of human RB cells in vitro , whereas in vivo experiments revealed a decrease in RB progression following SCARA5 overexpression. In addition, overexpression of SCARA5 inhibited phosphorylated (p)‑PI3K and p‑AKT expression, and knockdown of SCARA5 increased p‑PI3K and p‑AKT expression; however, no changes in total PI3K and AKT expression were observed. Bcl‑2 exhibited similar changes in expression to those displayed by p‑PI3K and p‑AKT, whereas Bax and cleaved caspase‑3 exhibited trends in expression that were the opposite to those shown by p‑PI3K and p‑AKT. In conclusion, the present results demonstrated that SCARA5 could inhibit the proliferation and promote the apoptosis of RB cell lines by suppressing the PI3K/AKT signaling pathway, thus suggesting a novel strategy for treating RB.

Active foamy macrophage enrichment drives atherosclerotic plaque initiation and evolution, and is the prominent target for precisely identifying vulnerable plaque. Precise imaging of high-risk plaque allows promotion of treatment and prevention of vascular pathema. However, current iron oxide (IO) nanoparticles-based magnetic resonance (MR) imaging of plaque is often limited by insufficient perfusion and nonspecific accumulation of peri-aortic lymph nodes. Besides that, intrinsic defects of MR also impede its use for accurately identifying plaque details. Herein, by conjugating with PP1 peptide, a novel magnetic mesoporous silica nanoparticle (PIMI) loaded with near-infrared fluorescence (NIRF) dye (IR820) was fabricated to specifically target and quantify macrophage enrichment of atherosclerotic plaque in ApoE -/- mice using dual MR/NIRF imaging. Biocompatibility experiments ulteriorly confirmed the high safety of PIMI nanoparticles in vivo, which lays the foundation of next-generation contrast agent for recognizing macrophage-rich plaque in the near future., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Lung transplantation has been performed worldwide and admitted as an effective treatment for patients with various end-stage lung diseases. However, limit reliable clinical indicators exist to identify patients at high risk for allograft failure in lung transplant recipients. The recent advances in the knowledge of immunological aspects of the pulmonary diseases, for that innate macrophage activation, are induced by pathogen or pathogen-derived molecules and widely accepted as the critical evidence among the pathogenesis of lung inflammation and fibrosis. This study was aimed at evaluating the clinical significance of CD86- and macrophage scavenger receptor 1- (MSR1-) positive cells during the development of idiopathic pulmonary fibrosis (IPF) and pulmonary arterial hypertension (PAH), and their potential roles in the prediction of the outcomes after lung transplantation were examined., Methods: Tissues from lung transplantation for 37 IPF and 15 PAH patients from the Department of Cardiothoracic Surgery in Wuxi People's Hospital from December 2015 to December 2016 were analyzed by immunohistochemistry (IHC) for detecting the expression and CD86 and MSR1 and correlated with clinical events after lung transplantation., Results: IHC results showed that the expression of MSR1, IL-13, and arginase-1 (Arg1) but not CD86 in the lung section of IPF patients was dramatically enhanced when compared with that of PAH patients. The expression of MSR1, IL-13, and Arg1 but not CD86 in the lung from IPF patients with smoking was significantly increased when compared with that from nonsmoking subjects. In addition, the expression of MSR1-positive cells in IPF subjects with Klebsiella pneumoniae infection was dramatically enhanced than that in noninfection subjects. MSR1-positive macrophages were negatively associated with FEV1 and with FVC but not associated with TLC and with TL CO . However, CD86-positive macrophages were not significantly associated with the above lung function-related factors. Furthermore, MSR1 had a higher area under the ROC curve (AUC) than CD86 for IPF diagnosis. Survival analysis indicated that high levels of MSR1-positive macrophages had a worse prognostic effect for IPF patients with lung transplantation., Conclusion: Our study indicates the clinical significance of Klebsiella pneumoniae infection-related MSR1-positive cells in IPF progression, and it could be a prognostic marker in IPF after the lung transplant; development strategies to reduce the expression of MSR1-positive macrophages in IPF may be beneficial for the lung transplant., Competing Interests: The authors declare that they have no competing financial interests., (Copyright © 2021 Mingfeng Zheng et al.)

Careful control of iron availability in the retina is central to maintenance of iron homeostasis, as its imbalance is associated with oxidative stress and the progression of several retinopathies. Ferritin, known for its role in iron storage and detoxification, has also been proposed as an iron-transporter protein, through its binding to Scara5 and TIM2 membrane receptors. In this study, the presence and iron-related functions of TIM2 in the mouse retina were investigated. Our results revealed for the first time the presence of TIM2 receptors in the mouse retina, mainly in Müller cells. Experimental TIM2 downregulation in the mouse retina promoted, probably due to a compensatory mechanism, Scara5 overexpression that increased retinal ferritin uptake and induced iron overload. Consecutive reactive oxygen species (ROS) overproduction and vascular endothelial growth factor (VEGF) overexpression led to impaired paracellular and transcellular endothelial transport characterized by tight junction degradation and increased caveolae number. In consequence, blood-retinal barrier (BRB) breakdown and retinal edema were observed. Altogether, these results point to TIM2 as a new modulator of retinal iron homeostasis and as a potential target to counteract retinopathy., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Obesity is characterized by the expansion of adipose tissue which is partially modulated by adipogenesis. In the present study, we identified five differentially expressed genes by incorporating two adipogenesis-related datasets from the GEO database and their correlation with adipogenic markers. However, the role of scavenger receptor class A member 3 ( SCARA3 ) in obesity-related disorders has been rarely reported. We found that Scara3 expression in old adipose tissue-derived mesenchymal stem cells (Ad-MSCs) was lower than it in young Ad-MSCs. Obese mice caused by deletion of the leptin receptor gene ( db/db ) or by a high-fat diet both showed reduced Scara3 expression in inguinal white adipose tissue. Moreover, hypermethylation of SCARA3 was observed in patients with type 2 diabetes and atherosclerosis. Data from the CTD database indicated that SCARA3 is a potential target for metabolic diseases. Mechanistically, JUN was predicted as a transcriptional factor of SCARA3 in different databases which is consistent with our further bioinformatics analysis. Collectively, our study suggested that SCARA3 is potentially associated with age-related metabolic dysfunction, which provided new insights into the pathogenesis and treatment of obesity as well as other obesity-associated metabolic complications.