ARL11 regulates lipopolysaccharide-stimulated macrophage activation by promoting mitogen-activated protein kinase (MAPK) signaling

Promotion of osteochondral repair through immune microenvironment regulation and activation of endogenous chondrogenesis via the release of apoptotic vesicles from donor MSCs

Utilizing transplanted human umbilical cord mesenchymal stem cells (HUMSCs) for cartilage defects yielded advanced tissue regeneration, but the underlying mechanism remain elucidated. Early after HUMSCs delivery to the defects, we observed substantial apoptosis. The released apoptotic vesicles (apoVs) of HUMSCs promoted cartilage regeneration by alleviating the chondro-immune microenvironment. ApoVs triggered M2 polarization in macrophages while simultaneously facilitating the chondrogenic differentiation of endogenous MSCs. Mechanistically, in macrophages, miR-100-5p delivered by apoVs activated the MAPK/ERK signaling pathway to promote M2 polarization. In MSCs, let-7i-5p delivered by apoVs promoted chondrogenic differentiation by targeting the eEF2K/p38 MAPK axis. Consequently, a cell-free cartilage regeneration strategy using apoVs combined with a decellularized cartilage extracellular matrix (DCM) scaffold effectively promoted the regeneration of osteochondral defects. Overall, new mechanisms of cartilage regeneration by transplanted MSCs were unconcealed in this study. Moreover, we provided a novel experimental basis for cell-free tissue engineering-based cartilage regeneration utilizing apoVs.

ARL11 knockdown alleviates spinal cord injury by inhibiting neuroinflammation and M1 activation of microglia in mice

Spinal cord injury (SCI) is a severe central nervous system injury and microglia are major participants in neuroinflammation after injury. ADP-ribosylation factor-like GTPase 11 (ARL11) is a GTP-binding protein. Whether ARL11 is involved in the SCI progression is unknown. In the impactor-induced moderate SCI mouse model, ARL11 protein and mRNA expression were significantly increased in the injury site. LPS (100 ng/mL) and IFN-γ (20 ng/mL) were incubated with BV2 cells (immortalized mouse microglial cell line) to drive them into an M1-like phenotype. ARL11 up-regulation was also observed in activated microglia in SCI mice and LPS and IFN-γ treated BV2 cells. Basso Mouse Scale scores and inclined plate test revealed that ARL11 deletion promoted motor function recovery in SCI mice. Pathological examination showed ARL11 knockdown reduced spinal cord tissue damage, increased neuron numbers, and inhibited neuronal apoptosis in SCI mice. ARL11 knockdown notably inhibited IL-1β and IL-6 production in vivo and in vitro. Furthermore, ARL11 deletion significantly inhibited iNOS protein and mRNA expression in vivo and in vitro, and COX-2 expression in vivo. Mechanism studies revealed that ARL11 silencing decreased phosphorylated ERK1/2 protein expression. Additionally, ELF1 knockdown significantly inhibited ARL11 protein and mRNA expression in vitro. ELF1 acted as a transcription activator in regulating ARL11 expression by binding to the promoter. In conclusion, ARL11 knockdown protects neurons by inhibiting M1 microglia-induced neuroinflammation, thereby promoting motor functional recovery in SCI mice. This may occur in part under the regulation of ELF1. Our study provides a new molecular target for SCI treatment.

Silencing ARL11 relieved atherosclerotic inflammation and lipid deposition via retraining JAK2/STAT1 pathway

BACKGROUND AND AIMS

Atherosclerosis (AS), an arterial vasculature disease, is characterized by abnormal lipid accumulation and inflammatory response. ADP ribosylation factor like GTPase 11 (ARL11) is linked to multifarious processes in cells. This study aims to clarify the underlying mechanism of ARL11 in AS.

METHODS

ApoE-/- mice fed with high-fat diet were used as mouse model of AS. Gene expression in AS was determined by mRNA-sequencing. ARL11 expression was detected by real-time PCR, Western blot and immunofluorescence. M1 polarization of macrophages was indicated by TNF-α and IL-6 levels as detected with ELISA, and iNOS expression determined by real-time PCR and Western blot. The role of ARL11 during AS was explored through loss-of-function analysis.

RESULTS

There were 1301 upregulated and 1110 downregulated genes during AS. These differentially expressed genes (DEGs) were mainly enriched in pathways and terms which are involved in inflammation. Moreover, Arl11 was highly expressed in AS models. Downregulation of Arl11 decreased lipid deposition and atherosclerotic plaques in the aortas of AS mice, and declined inflammatory cytokines and M1 polarization of macrophages induced by IFN-γ. Furthermore, ARL11 interacted with JAK2 and p-JAK2 and modulated their degradation, thus inhibiting the activation of JAK2/STAT1 pathway.

CONCLUSIONS

ARL11 promoted the development of AS via interacting with JAK2 and activating JAK2/STAT1 pathway. Thus, silencing ARL11 may prevent the process of AS and be a novel way to treat AS.

Quantitative Proteomic Analysis of Macrophages Infected with Trypanosoma cruzi Reveals Different Responses Dependent on the SLAMF1 Receptor and the Parasite Strain

Chagas disease is caused by the intracellular protozoan parasite Trypanosoma cruzi. This disease affects mainly rural areas in Central and South America, where the insect vector is endemic. However, this disease has become a world health problem since migration has spread it to other continents. It is a complex disease with many reservoirs and vectors and high genetic variability. One of the host proteins involved in the pathogenesis is SLAMF1. This immune receptor acts during the infection of macrophages controlling parasite replication and thus affecting survival in mice but in a parasite strain-dependent manner. Therefore, we studied the role of SLAMF1 by quantitative proteomics in a macrophage in vitro infection and the different responses between Y and VFRA strains of Trypanosoma cruzi. We detected different significant up- or downregulated proteins involved in immune regulation processes, which are SLAMF1 and/or strain-dependent. Furthermore, independently of SLAMF1, this parasite induces different responses in macrophages to counteract the infection and kill the parasite, such as type I and II IFN responses, NLRP3 inflammasome activation, IL-18 production, TLR7 and TLR9 activation specifically with the Y strain, and IL-11 signaling specifically with the VFRA strain. These results have opened new research fields to elucidate the concrete role of SLAMF1 and discover new potential therapeutic approaches for Chagas disease.

Membrane trafficking alterations in breast cancer progression

Breast cancer (BC) is the most common type of cancer in women, and remains one of the major causes of death in women worldwide. It is now well established that alterations in membrane trafficking are implicated in BC progression. Indeed, membrane trafficking pathways regulate BC cell proliferation, migration, invasion, and metastasis. The 22 members of the ADP-ribosylation factor (ARF) and the >60 members of the rat sarcoma (RAS)-related in brain (RAB) families of small GTP-binding proteins (GTPases), which belong to the RAS superfamily, are master regulators of membrane trafficking pathways. ARF-like (ARL) subfamily members are involved in various processes, including vesicle budding and cargo selection. Moreover, ARFs regulate cytoskeleton organization and signal transduction. RABs are key regulators of all steps of membrane trafficking. Interestingly, the activity and/or expression of some of these proteins is found dysregulated in BC. Here, we review how the processes regulated by ARFs and RABs are subverted in BC, including secretion/exocytosis, endocytosis/recycling, autophagy/lysosome trafficking, cytoskeleton dynamics, integrin-mediated signaling, among others. Thus, we provide a comprehensive overview of the roles played by ARF and RAB family members, as well as their regulators in BC progression, aiming to lay the foundation for future research in this field. This research should focus on further dissecting the molecular mechanisms regulated by ARFs and RABs that are subverted in BC, and exploring their use as therapeutic targets or prognostic markers.

ARL11 correlates with the immunosuppression and poor prognosis in breast cancer: A comprehensive bioinformatics analysis of ARL family members

ADP-ribosylation factor-like protein (ARL) family members (ARLs) may regulate the malignant phenotypes of cancer cells. However, relevant studies on ARLs in breast cancer (BC) are limited. In this research, the expression profiles, genetic variations, and prognostic values of ARLs in BC have been systematically analyzed for the first time using various databases. We find that ARLs are significantly dysregulated in BC according to the TCGA database, which may result from DNA methylation and copy number alteration. Prognostic analysis suggests that ARL11 is the most significant prognostic indicator for BC, and higher ARL11 predicts worse clinical outcomes for BC patients. Further functional enrichment analysis demonstrates that ARL11 enhances the immunosuppression in BC, and dysregulation of ARL11 is significantly associated with immune infiltration in various types of cancer. Our results demonstrate the potential of ARL11 as an immune therapeutic target for BC.

Farnesoid X receptor regulates lung macrophage activation and injury following nitrogen mustard exposure

Nitrogen mustard (NM) is a cytotoxic vesicant known to cause acute lung injury which progresses to fibrosis; this is associated with a sequential accumulation of pro- and anti-inflammatory macrophages in the lung which have been implicated in NM toxicity. Farnesoid X receptor (FXR) is a nuclear receptor involved in regulating lipid homeostasis and inflammation. In these studies, we analyzed the role of FXR in inflammatory macrophage activation, lung injury and oxidative stress following NM exposure. Wild-type (WT) and FXR-/- mice were treated intratracheally with PBS (control) or NM (0.08 mg/kg). Bronchoalveolar lavage fluid (BAL) and lung tissue were collected 3, 14 and 28 d later. NM caused progressive histopathologic alterations in the lung including inflammatory cell infiltration and alveolar wall thickening and increases in protein and cells in BAL; oxidative stress was also noted, as reflected by upregulation of heme oxygenase-1. These changes were more prominent in male FXR-/- mice. Flow cytometric analysis revealed that loss of FXR resulted in increases in proinflammatory macrophages at 3 d post NM; this correlated with upregulation of COX-2 and ARL11, markers of macrophage activation. Markers of anti-inflammatory macrophage activation, CD163 and STAT6, were also upregulated after NM; this response was exacerbated in FXR-/- mice at 14 d post-NM. These findings demonstrate that FXR plays a role in limiting macrophage inflammatory responses important in lung injury and oxidative stress. Maintaining or enhancing FXR function may represent a useful strategy in the development of countermeasures to treat mustard lung toxicity.

Comparative genomic analyses of multiple backcross mouse populations suggest SGCG as a novel potential obesity-modifier gene

To nominate novel disease genes for obesity and type 2 diabetes (T2D), we recently generated two mouse backcross populations of the T2D-susceptible New Zealand Obese (NZO/HI) mouse strain and two genetically different, lean and T2D-resistant strains, 129P2/OlaHsd and C3HeB/FeJ. Comparative linkage analysis of our two female backcross populations identified seven novel body fat-associated quantitative trait loci (QTL). Only the locus Nbw14 (NZO body weight on chromosome 14) showed linkage to obesity-related traits in both backcross populations, indicating that the causal gene variant is likely specific for the NZO strain as NZO allele carriers in both crosses displayed elevated body weight and fat mass. To identify candidate genes for Nbw14, we used a combined approach of gene expression and haplotype analysis to filter for NZO-specific gene variants in gonadal white adipose tissue (gWAT), defined as the main QTL-target tissue. Only two genes, Arl11 and Sgcg, fulfilled our candidate criteria. In addition, expression QTL analysis revealed cis-signals for both genes within the Nbw14 locus. Moreover, retroviral overexpression of Sgcg in 3 T3-L1 adipocytes resulted in increased insulin-stimulated glucose uptake. In humans, mRNA levels of SGCG correlated with BMI and body fat mass exclusively in diabetic subjects, suggesting that SGCG may present a novel marker for metabolically unhealthy obesity. In conclusion, our comparative-cross analysis could substantially improve the mapping resolution of the obesity locus Nbw14. Future studies will shine light on the mechanism by which Sgcg may protect from the development of obesity.

Wu-Mei-Wan Ameliorates Murine Ulcerative Colitis by Regulating Macrophage Polarization

An increasing body of evidence shows that macrophages play an important role in the pathogenesis of ulcerative colitis (UC). Macrophage polarization and changes in related signaling pathways are reported to have a protective effect on intestinal inflammation. The well-known Chinese medicine Wumeiwan (WMW) has been used to treat diarrhea, one of the main symptoms of colitis, for more than 2,000 years. Increasing evidence shows that WMW can inhibit intestinal inflammation and repair damaged intestinal mucosa, but its effector mechanisms are unknown. Therefore, we studied the prophylactic effects of WMW in dextran sulfate sodium (DSS)-induced UC and its effects on macrophage mechanisms and polarization. The results show that colitis was significantly alleviated in mice in the WMW group, and the secretion and expression of pro-inflammatory factors TNF-α, IL-1, and IL-6 were inhibited in the serum and colonic tissues of mice with WMW-treated colitis, whereas anti-inflammatory factors IL-10, Arg-1, and TGF-β1 were increased. Subsequent studies found that WMW could inhibit M1 polarization and promote M2 polarization in colonic macrophages in DSS-induced colitis mice. Network pharmacology was used to predict potential targets and pathways, and further studies confirmed the related targets The results showed that WMW gradually inhibits the activation of the P38MAPK and NF-κB signaling pathways and further activates the STAT6 signaling pathway. In summary, WMW interferes with the p38MAPK, NF-κB and STAT6 signaling pathways to regulate M1/M2 polarization in macrophages, thereby protecting mice against DSS-induced colitis.

Droplet-based screening of phosphate transfer catalysis reveals how epistasis shapes MAP kinase interactions with substrates

The combination of ultrahigh-throughput screening and sequencing informs on function and intragenic epistasis within combinatorial protein mutant libraries. Establishing a droplet-based, in vitro compartmentalised approach for robust expression and screening of protein kinase cascades (>10⁷ variants/day) allowed us to dissect the intrinsic molecular features of the MKK-ERK signalling pathway, without interference from endogenous cellular components. In a six-residue combinatorial library of the MKK1 docking domain, we identified 29,563 sequence permutations that allow MKK1 to efficiently phosphorylate and activate its downstream target kinase ERK2. A flexibly placed hydrophobic sequence motif emerges which is defined by higher order epistatic interactions between six residues, suggesting synergy that enables high connectivity in the sequence landscape. Through positive epistasis, MKK1 maintains function during mutagenesis, establishing the importance of co-dependent residues in mammalian protein kinase-substrate interactions, and creating a scenario for the evolution of diverse human signalling networks.

Here, the authors use a droplet-based screen for phosphate transfer catalysis, testing variants of the human protein kinase MKK1 for its ability to activate its downstream target ERK2. Data reveal a flexible motif in the MKK1 docking domain that promotes efficient activation of ERK2, and suggest epistasis between the residues within that sequence.

Unraveling the Relevance of ARL GTPases in Cutaneous Melanoma Prognosis through Integrated Bioinformatics Analysis

Cutaneous melanoma (CM) is the deadliest skin cancer, whose molecular pathways underlying its malignancy remain unclear. Therefore, new information to guide evidence-based clinical decisions is required. Adenosine diphosphate (ADP)-ribosylation factor-like (ARL) proteins are membrane trafficking regulators whose biological relevance in CM is undetermined. Here, we investigated ARL expression and its impact on CM prognosis and immune microenvironment through integrated bioinformatics analysis. Our study found that all 22 ARLs are differentially expressed in CM. Specifically, ARL1 and ARL11 are upregulated and ARL15 is downregulated regardless of mutational frequency or copy number variations. According to TCGA data, ARL1 and ARL15 represent independent prognostic factors in CM as well as ARL11 based on GEPIA and OncoLnc. To investigate the mechanisms by which ARL1 and ARL11 increase patient survival while ARL15 reduces it, we evaluated their correlation with the immune microenvironment. CD4+ T cells and neutrophil infiltrates are significantly increased by ARL1 expression. Furthermore, ARL11 expression was correlated with 17 out of 21 immune infiltrates, including CD8+ T cells and M2 macrophages, described as having anti-tumoral activity. Likewise, ARL11 is interconnected with ZAP70, ADAM17, and P2RX7, which are implicated in immune cell activation. Collectively, this study provides the first evidence that ARL1, ARL11, and ARL15 may influence CM progression, prognosis, and immune microenvironment remodeling.

Runx proteins mediate protective immunity against Leishmania donovani infection by promoting CD40 expression on dendritic cells

The level of CD40 expression on dendritic cells (DCs) plays a decisive role in disease protection during Leishmania donovani (LD) infection. However, current understanding of the molecular regulation of CD40 expression remains elusive. Using molecular, cellular and functional approaches, we identified a role for Runx1 and Runx3 transcription factors in the regulation of CD40 expression in DCs. In response to lipopolysaccharide (LPS), tumor necrosis factor alpha (TNFα) or antileishmanial drug sodium antimony gluconate (SAG), both Runx1 and Runx3 translocated to the nucleus, bound to the CD40 promoter and upregulated CD40 expression on DCs. These activities of Runx proteins were mediated by the upstream phosphatidylinositol 3-kinase (PI3K)-Akt pathway. Notably, LD infection attenuated LPS- or TNFα-induced CD40 expression in DCs by inhibiting PI3K-Akt-Runx axis via protein tyrosine phosphatase SHP-1. In contrast, CD40 expression induced by SAG was unaffected by LD infection, as SAG by blocking LD-induced SHP-1 activation potentiated PI3K-Akt signaling to drive Runx-mediated CD40 upregulation. Adoptive transfer experiments further showed that Runx1 and Runx3 play a pivotal role in eliciting antileishmanial immune response of SAG-treated DCs in vivo by promoting CD40-mediated type-1 T cell responses. Importantly, antimony-resistant LD suppressed SAG-induced CD40 upregulation on DCs by blocking the PI3K-Akt-Runx pathway through sustained SHP-1 activation. These findings unveil an immunoregulatory role for Runx proteins during LD infection.

Alteration of tumor-associated macrophage subtypes mediated by KRT6A in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is severely affecting the health and lives of patients. Clarifying the composition and regulatory factors of tumor immune microenvironment (TIME) is helpful for the treatment of PDAC. We analyzed the unique TIMEs and gene expression patterns between PDAC and adjacent normal tissue (ANT) using Gene Expression Omnibus (GEO) to find new immunotherapy targets. The Cancer Genome Atlas (TCGA) datasets were used to elucidate the possible mechanism of which tumor-associated macrophages (TAMs) changed in PDAC. We found that the composition of TAMs subtypes, including M0, M1, and M2, was different between PDAC and ANT, which was validated in recently published single-cell RNA-seq data. Many immune cells interacted with each other to affect the TIME. There were many DEGs enriched in some pathways that could potentially change the immune cell composition. KRT6A was found to be a DEG between PDAC and ANT that overlapped with DEGs between the M0-high group and the M0-low group in TCGA datasets, and it might alter and regulate TAMs via a collection of genes including COL5A2, COL1A2, MIR3606, SPARC, and COL6A3. TAMs, which could be a target of immunotherapy, might be influenced by genes through KRT6A and indicate an undesirable prognosis in PDAC.

Plants derived therapeutic strategies targeting chronic respiratory diseases: Chemical and immunological perspective

The apparent predicament of the representative chemotherapy for managing respiratory distress calls for an obligatory deliberation for identifying the pharmaceuticals that effectively counter the contemporary intricacies associated with target disease. Multiple, complex regulatory pathways manifest chronic pulmonary disorders, which require chemotherapeutics that produce composite inhibitory effect. The cost effective natural product based molecules hold a high fervor to meet the prospects posed by current respiratory-distress therapy by sparing the tedious drug design and development archetypes, present a robust standing for the possible replacement of the fading practice of poly-pharmacology, and ensure the subversion of a potential disease relapse. This study summarizes the experimental evidences on natural products moieties and their components that illustrates therapeutic efficacy on respiratory disorders.

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Plant derived therapeutics for managing chronic respiratory disorders.

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Activity of natural product based molecules on key regulatory pathways of COPD.

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Preclinical evidence for the efficacy of natural product moieties.

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Clinical significance of plant derived molecules in pulmonary distress.

Different cytokine patterns induced by Helicobacter pylori and Lactobacillus acidophilus extracts in PBMCs of patients with abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a degenerative inflammatory disease with unknown etiology. AAA is characterized by abdominal aortic dilatation more than 3 cm and is often asymptomatic, but the rupture of aneurysm can lead to death. Age, smoking and male sex are major predisposing factors of AAA. This study compares the effect of Helicobacter (H.) pylori and Lactobacillus (L.) acidophilus on the cytokine profile of PBMCs of 5 men with abdominal aortic aneurysm (AAA) and 5 men with normal/insignificant angiography, CT-Scan and ultrasonography results in the single-culture and in the co-culture with HUVECs. IL-2, IL-4, IL-5, IL-6, IL-9, IL-10, IL-13, IL-17A, IL-17 F, IL-21, IL-22, IFN-γ and TNF-α were measured in culture supernatants using a commercial fluorescent-labeled-bead assay. In general, CagA+ H. pylori-extract induced higher production of IFN-γ, IL-13 and IL-21 by PBMCs. Treatment of patients' PBMCs with CagA⁺H. pylori-extract induced Th2 cytokines while treatment of controls' PBMCs with CagA⁺H. pylori-extract increased Th1 cytokines. In the co-culture, however, patients' PBMCs produced Th1 cytokines irrespective of extract treatment, while controls' PBMCs produced Th2 cytokines and decreased IL-10. CagA+ H. pylori- as well as L. acidophilus-extract induced higher levels of IL-9 by controls' PBMCs in co-culture with HUVECs than patients (P = 0.05 and P = 0.01). The cytokine pattern of PBMCs induced by CagA+ H. pylori- and L. acidophilus-extracts in the co-culture with HUVECs shows differences in AAA patients and in comparison to controls. Decreased secretion of IL-9, IL-21 and IL-22 by PBMCs of patients treated with CagA+ H. pylori extract in co-culture, as opposed to non-AAA controls may indicate the active role ECs play in AAA. Simultaneous production of IL-10 and Th1 cytokines in patients and pronounced Th2 cytokines in controls in response to both bacteria may point to the inherent differences between patients and controls, which need further investigation.

Phagocytosis mediated by scavenger receptor class BI promotes macrophage transition during skeletal muscle regeneration

Macrophages play an essential role in skeletal muscle regeneration. The phagocytosis of muscle cell debris induces a switch of pro-inflammatory macrophages into an anti-inflammatory phenotype, but the cellular receptors mediating this phagocytosis are still unclear. In this paper, we report novel roles for SRB1 (scavenger receptor class BI) in regulating macrophage phagocytosis and macrophage phenotypic transitions for skeletal muscle regeneration. In a mouse model of cardiotoxin-induced muscle injury/regeneration, infiltrated macrophages expressed a high level of SRB1. Using SRB1 knockout mice, we observed the impairment of muscle regeneration along with decreased myogenin expression and increased matrix deposit. Bone marrow transplantation experiments indicated that SRB1 deficiency in bone marrow cells was responsible for impaired muscle regeneration. Compared with WT mice, SRB1 deficiency increased pro-inflammatory macrophage number and pro-inflammatory gene expression and decreased anti-inflammatory macrophage number and anti-inflammatory gene expression in injured muscle. In vitro, SRB1 deficiency led to a strong decrease in macrophage phagocytic activity on myoblast debris. SRB1-deficient macrophages easily acquired an M1 phenotype and failed to acquire an M2 phenotype in lipopolysaccharide/myoblast debris activation. Furthermore, SRB1 deficiency promoted activation of ERK1/2 MAPK signaling in macrophages stimulated with lipopolysaccharide/myoblast debris. Taken together, SRB1 in macrophages regulates phagocytosis and promotes M1 switch into M2 macrophages, contributing to muscle regeneration.

Inhibition of EZH2 methyltransferase decreases immunoediting of mesothelioma cells by autologous macrophages through a PD-1-dependent mechanism

The roles of macrophages in orchestrating innate immunity through phagocytosis and T lymphocyte activation have been extensively investigated. Much less understood is the unexpected role of macrophages in direct tumor regression. Tumoricidal macrophages can indeed manifest cancer immunoediting activity in the absence of adaptive immunity. We investigated direct macrophage cytotoxicity in malignant pleural mesothelioma, a lethal cancer that develops from mesothelial cells of the pleural cavity after occupational asbestos exposure. In particular, we analyzed the cytotoxic activity of mouse RAW264.7 macrophages upon cell-cell contact with autologous AB1/AB12 mesothelioma cells. We show that macrophages killed mesothelioma cells by oxeiptosis via a mechanism involving enhancer of zeste homolog 2 (EZH2), a histone H3 lysine 27-specific (H3K27-specific) methyltransferase of the polycomb repressive complex 2 (PRC2). A selective inhibitor of EZH2 indeed impaired RAW264.7-directed cytotoxicity and concomitantly stimulated the PD-1 immune checkpoint. In the immunocompetent BALB/c model, RAW264.7 macrophages pretreated with the EZH2 inhibitor failed to control tumor growth of AB1 and AB12 mesothelioma cells. Blockade of PD-1 engagement restored macrophage-dependent antitumor activity. We conclude that macrophages can be directly cytotoxic for mesothelioma cells independent of phagocytosis. Inhibition of the PRC2 EZH2 methyltransferase reduces this activity because of PD-1 overexpression. Combination of PD-1 blockade and EZH2 inhibition restores macrophage cytotoxicity.

Sarcoid-Like Granulomatous Disease: Pathologic Case Series in World Trade Center Dust Exposed Rescue and Recovery Workers

Sarcoid-like granulomatous diseases (SGD) have been previously identified in cohorts of World Trade Center (WTC) dust-exposed individuals. In the present studies, we analyzed lung and/or lymph node biopsies from patients referred to our clinic with suspected WTC dust-induced lung disease to evaluate potential pathophysiologic mechanisms. Histologic sections of lung and/or lymph node samples were analyzed for markers of injury, oxidative stress, inflammation, fibrosis, and epigenetic modifications. Out of seven patients examined, we diagnosed four with SGD and two with pulmonary fibrosis; one was diagnosed later with SGD at another medical facility. Patients with SGD were predominantly white, obese men, who were less than 50 years old and never smoked. Cytochrome b5, cytokeratin 17, heme oxygenase-1, lipocalin-2, inducible nitric oxide synthase, cyclooxygenase 2, tumor necrosis factor α, ADP-ribosylation factor-like GTPase 11, mannose receptor-1, galectin-3, transforming growth factor β, histone-3 and methylated histone-3 were identified in lung and lymph nodes at varying levels in all samples examined. Three of the biopsy samples with granulomas displayed peri-granulomatous fibrosis. These findings are important and suggest the potential of WTC dust-induced fibrotic sarcoid. It is likely that patient demographics and/or genetic factors influence the response to WTC dust injury and that these contribute to different pathological outcomes.

MAPping the kinase landscape of macrophage activation

ARL11 is a tumor suppressor gene with established pro-apoptotic properties, but its function beyond this role is poorly understood. A new analysis of macrophage activation has identified ARL11 as a novel regulator of a mitogen-activated protein kinase (MAPK). These findings expand on the function of ARL11 beyond its tumor suppressor activity and highlight a novel role as a regulator of macrophage activation and inflammatory response.

Method for Studying the Effect of Gene Silencing on Bacterial Infection-induced ERK1/2 Signaling in Bone-marrow Derived Macrophages

Macrophages are highly phagocytic cells that utilize various pathogen recognition receptors (PRRs) to recognize pathogen-associated molecular patterns (PAMPs). These PAMPs can be present within the microbe, such as bacterial CpG DNA, and are recognized by Toll-like receptor 9 (TLR9), a PRR present on the endosomal membrane of macrophages. PAMPs can also be present on the surface of microbes, such as Lipopolysaccharide (LPS), which decorates the outer membrane of gram-negative bacteria like Salmonella typhimurium and Escherichia coli. LPS is recognized by TLR4 present on the plasma membrane of macrophages, and LPS-TLR4 association leads to activation of signaling cascades including MAPK phosphorylation, which in turn promotes macrophage activation and microbial killing. This protocol describes the method for studying the role of a gene of interest in Extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) signaling, induced by bacterial infection in primary bone-marrow derived macrophages (BMDMs).