Regulation Of Macrophage Activation Research Articles

Paeoniflorin exhibits anti-Helicobacter pylori activity by regulating macrophage activity

Paeoniflorin exhibits anti-Helicobacter pylori activity by regulating macrophage activity

CCL2-Mediated Stromal Interactions Drive Macrophage Polarization to Increase Breast Tumorigenesis.

CCL2 is an inflammatory cytokine that regulates macrophage activity and is implicated in increased mammographic density and early breast tumorigenesis. The role of CCL2 in mediating stromal interactions that contribute to breast tumorigenesis has yet to be fully elucidated. THP-1-derived macrophages and mammary fibroblasts were co-cultured for 72 h. Fibroblasts and macrophages were analysed for phenotype, expression of inflammatory and ECM-regulatory genes and collagen production. Mice overexpressing CCL2 in the mammary glands were analysed for global gene expression by RNAseq at 12 weeks of age. These mice were cross-bred with PyMT mammary tumour mice to examine the role of CCL2 in tumorigenesis. The co-culture of macrophages with fibroblasts resulted in macrophage polarization towards an M2 phenotype, and upregulated expression of CCL2 and other genes associated with inflammation and ECM remodelling. CCL2 increased the production of insoluble collagen by fibroblasts. A global gene expression analysis of CCL2 overexpressing mice revealed that CCL2 upregulates cancer-associated gene pathways and downregulates fatty acid metabolism gene pathways. In the PyMT mammary tumour model, CCL2 overexpressing mice exhibited increased macrophage infiltration and early tumorigenesis. Interactions between macrophages and fibroblasts regulated by CCL2 can promote an environment that may increase breast cancer risk, leading to enhanced early tumorigenesis.

8-Prenyl daidzein and 8-prenyl genistein from germinated soybean modulate inflammatory response in activated macrophages.

Soy isoflavones have been shown to have anti-inflammatory properties; however, the anti-inflammatory effects of isoflavone metabolites produced during soybean germination remain unclear. We found that the daidzein and genistein derivatives, 8-prenyl daidzein (8-PD) and 8-prenyl genistein (8-PG), demonstrated a more potent effect than daidzein and genistein on repressing inflammatory responses in macrophages. Although IkB protein levels were unaltered, 8-PD and 8-PG repressed nuclear factor kappa B (NF-κB) activation, which was associated with reduced ERK1/2, JNK, and p38 MAPK activation and suppressed mitogen- and stress-activated kinase 1 phosphorylation. Inflammatory responses induced by the medium containing hypertrophic adipocyte secretions were successfully suppressed by 8-PD and 8-PG treatment. In the ex vivo study, 8-PD and 8-PG significantly inhibited proinflammatory C-C motif chemokine ligand 2 (CCL2) secretion from the adipose tissues of mice fed a long-term high-fat diet. The data suggest that 8-PD and 8-PG could regulate macrophage activation under obesity conditions.

Abstract 2347: Producing genetically defined CAFs for the study of hypoxia signaling in the pancreatic cancer TME

Abstract Introduction (or Objective): Pancreatic ductal adenocarcinoma (PDAC) is characterized by having an extensive desmoplastic stroma that contributes to its resistance to therapeutic treatments resulting in a poor prognosis. Cancer associated fibroblasts (CAFs) are the most prevalent stromal cells within the pancreatic tumor microenvironment (TME), making up roughly 70-80% of the tumor volume. Pancreatic tumors are extremely hypoxic due to this dense stromal infiltration. We previously showed that CAFs in PDAC regulate macrophage activity and polarization in a HIF2-dependent manner, revealing the importance of hypoxia signaling in stromal cells. PDAC-CAFs also participate in cross talk with cancer cells inducing cancer malignancy, angiogenesis, metastasis, and drug resistance. In this study, we utilized a novel mouse model to produce genetically defined CAFs to study how HIFs (including HIF1a, HIF2a, and their binding partner ARNT) contribute to the function of CAFs in the pancreatic cancer TME. Methods: LSL-tdTomato mice were obtained from Jackson laboratories. TdTomato mice were bred with aSMACreERT2/+ mice, and their progeny were bred with Hif1afl/fl, Hif2afl/fl and ARNTfl/fl mice to produce LSL-tdTomato; aSMACreERT2/+; HIF1afl/fl (HIF1-KO)/HIF2afl/fl (HIF2-KO)/ARNTfl/fl (ARNT-KO) mice, respectively. KPC tumor cells (KrasG12D;Trp53R172H) were then injected orthotopically into the pancreas of these mice. After one month, tumors were harvested and digested to allow for CAF isolation. Digested single cells were then sorted for tdTomato expression to specifically isolate aSMA+ CAFs. All mice are on a C57BL/6J genetic background. Results: We isolated genetically defined CAFs lacking either HIF1, HIF2 and ARNT in a syngeneic orthotopic tumor model. After dissociating solid tumors and isolating tdTomato+ cells, we isolated early passage CAFs as verified by expression of fibroblast markers (ACTA1, COL1A1, FN1, etc.) without epithelial markers (EPCAM, KRT19). Genetic loss of HIF1, HIF2 or ARNT was verified via western blot and qPCR analysis. Conclusion: We created a Cre-driven model to specifically label CAFs and genetically manipulate hypoxia signaling that can be used with any desired promoter. This model allows the isolation and characterization of spatially and temporally genetically defined stromal populations, which may enable downstream syngeneic transplantation. We believe that this powerful system could be used to interrogate each stromal component in a definitive fashion without the need for more complex multiallelic mouse models. Citation Format: Sahar B. Fattani, Matthew T. Cribb, Abagail M. Delahoussaye, Nefetiti P. Mims, Natividad R. Fuentes, Cullen M. Taniguchi. Producing genetically defined CAFs for the study of hypoxia signaling in the pancreatic cancer TME [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2347.

Dehydration Accelerates Cytogenesis and Cyst Growth in Pkd1-/- Mice by Regulating Macrophage M2 Polarization.

Adult autosomal dominant polycystic kidney disease (ADPKD) has been shown to be related as a "third hit" to the occurrence of acute or chronic kidney injury. Here, we examined whether dehydration, as a common kidney risk factor, could cause cystogenesis in chronic-onset Pkd1-/- mice by regulating macrophage activation. First, we confirmed that dehydration accelerated cytogenesis in Pkd1-/- mice and that macrophages infiltrated the kidney tissues even earlier than macroscopic cyst formation. Then, microarray analysis suggested that glycolysis pathway may be involved in macrophage activation in Pkd1-/- kidneys under conditions of dehydration. Further, we confirmed glycolysis pathway was activated and lactic acid (L-LA) was overproduced in the Pkd1-/- kidney under conditions of dehydration. We have already proved that L-LA strongly stimulated M2 macrophage polarization and overproduction of polyamine in macrophage in vitro, and in the present study, we further discovered that M2 polarization-induced polyamine production shortened the primary cilia length by disrupting the PC1/PC2 complex. Finally, the activation of L-LA-arginase 1-polyamine pathway contributed to cystogenesis and progressive cyst growth in Pkd1-/- mice recurrently exposed to dehydration.

Ginsenoside Rb1 Interfered with Macrophage Activation by Activating PPARγ to Inhibit Insulin Resistance in Obesity.

Type 2 diabetes (T2D) is characterized by insulin resistance (IR), often accompanied by inflammation. Macrophage activation acts as an inflammatory response, which is characterized by macrophage recruitment in the initial stage. Ginsenoside Rb1 (Rb1) is a main active ingredient, which is known for its fat-reducing, anti-inflammatory effects. To clarify that Rb1 regulates macrophage activation in adipose tissue and improves tissue inflammation, network pharmacology and molecular docking were used for target prediction and preliminary validation. By constructing the co-culture model of adipose-derived stem cells (ADSC) and primary macrophage (PM), the body adipose tissue microenvironment was simulated to observe the adipogenesis degree of adipocytes under the effect of Rb1. The levels of cytokines, macrophage polarization, and protein or RNA expression in the inflammatory signaling pathway were finally detected. The results showed that 89 common targets of T2D-Rb1 were obtained after their intersection. Furthermore, according to the results of the KEGG pathway and PPI analysis, PTGS2 (COX-2) is the downstream protein of PPARγ-NF-κB. The molecular binding energy of PPARγ-Rb1 is -6.8 kcal/mol. Rb1 significantly inhibited the increase in MCP-1, TNF-α, and IL-1β induced by hypertrophic adipocytes supernatant and promoted the expression of IL-10. Rb1 inhibited the activation of inflammatory macrophages and PM migration and upregulated PPARγ expression with the blocking of NF-κB activation. Additionally, Rb1 promoted the expression of IRS1 and PI3K in the insulin signal pathway, which had a similar effect with ROS. Therefore, Rb1 might affect macrophage activation through PPARγ, which might alleviate obese insulin resistance in T2D early stage.

Pharmacological blockade of HDAC3 accelerates diabetic wound healing by regulating macrophage activation

AimsHere, we report the effect of histone deacetylase 3 (HDAC3) inhibition associated with macrophage activation, IL-1β expression, angiogenesis and wound healing in diabetic mice. Main methodsTo determine the expression of HDAC3 in diabetic mice wounds, hyperglycemia was induced in C57BL/6 mice with streptozotocin followed by induction of 6 mm wounds. To understand the effect of HDAC3 selective inhibitor, BG45, wound tissues were isolated for analysing M1/M2 markers expression, immune cells infiltration, angiogenesis and healing factors expression. CD11b+F4/80+ cells were sorted from the wound tissues and analysed for the expression of M1/M2 markers using RT-qPCR and flow cytometer. In cell based assays, HDAC3 expression was measured in macrophages stimulated with high glucose (HG) plus LPS. Macrophages treated with BG45 and HG + LPS were analysed for the expression of pro-IL-1β, mature IL-1β, oxidative stress and pro-inflammatory (M1) and anti-inflammatory (M2) factors. Key findingsHDAC3 was found to be upregulated in impaired diabetic mice wounds and in macrophages stimulated with HG + LPS. Topical application of BG45 loaded gel accelerated the wound healing in diabetic mice and was evident by improved expression of Collagen-1A, IL-10, TGF-β, and angiogenesis (CD31, VEGF). BG45 treatment decreased the expression of IL-1β, TNF-α, and IL-6 (M1 phenotype), reduced oxidative stress and promoted the expression of Arginase-1 and YM1/2 (M2 phenotype) in macrophages treated with HG + LPS. BG45 also improved the expression of CD11b+F4/80+CD206+ cells in wound tissues and reduced expression of inflammatory markers. SignificanceHDAC3 is upregulated in diabetic mice wounds and HDAC3 selective inhibitor promotes the wound healing by regulating macrophage activation, angiogenesis and IL-1β.

Bidirectional Regulation of Sodium Acetate on Macrophage Activity and Its Role in Lipid Metabolism of Hepatocytes

Short-chain fatty acids (SCFAs) are important metabolites of the intestinal flora that are closely related to the development of non-alcoholic fatty liver disease (NAFLD). Moreover, studies have shown that macrophages have an important role in the progression of NAFLD and that a dose effect of sodium acetate (NaA) on the regulation of macrophage activity alleviates NAFLD; however, the exact mechanism of action remains unclear. This study aimed to assess the effect and mechanism of NaA on regulating the activity of macrophages. RAW264.7 and Kupffer cells cell lines were treated with LPS and different concentrations of NaA (0.01, 0.05, 0.1, 0.5, 1, 1.5, 2, and 5 mM). Low doses of NaA (0.1 mM, NaA-L) significantly increased the expression of inflammatory factors tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin 1 beta (IL-1β); it also increased the phosphorylation of inflammatory proteins nuclear factor-κB p65 (NF-κB p65) and c-Jun (p < 0.05), and the M1 polarization ratio of RAW264.7 or Kupffer cells. Contrary, a high concentration of NaA (2 mM, NaA-H) reduced the inflammatory responses of macrophages. Mechanistically, high doses of NaA increased intracellular acetate concentration in macrophages, while a low dose had the opposite effect, consisting of the trend of changes in regulated macrophage activity. Besides, GPR43 and/or HDACs were not involved in the regulation of macrophage activity by NaA. NaA significantly increased total intracellular cholesterol (TC), triglycerides (TG), and lipid synthesis gene expression levels in macrophages and hepatocytes at either high or low concentrations. Furthermore, NaA regulated the intracellular AMP/ATP ratio and AMPK activity, achieving a bidirectional regulation of macrophage activity, in which the PPARγ/UCP2/AMPK/iNOS/IκBα/NF-κB signaling pathway has an important role. In addition, NaA can regulate lipid accumulation in hepatocytes by NaA-driven macrophage factors through the above-mentioned mechanism. The results revealed that the mode of NaA bi-directionally regulating the macrophages further affects hepatocyte lipid accumulation.

N6-methyladenosine of Spi2a attenuates inflammation and sepsis-associated myocardial dysfunction in mice

Bacteria-triggered sepsis is characterized by systemic, uncontrolled inflammation in affected individuals. Controlling the excessive production of pro-inflammatory cytokines and subsequent organ dysfunction in sepsis remains challenging. Here, we demonstrate that Spi2a upregulation in lipopolysaccharide (LPS)-stimulated bone marrow-derived macrophages reduces the production of pro-inflammatory cytokines and myocardial impairment. In addition, exposure to LPS upregulates the lysine acetyltransferase, KAT2B, to promote METTL14 protein stability through acetylation at K398, leading to the increased m6A methylation of Spi2a in macrophages. m6A-methylated Spi2a directly binds to IKKβ to impair IKK complex formation and inactivate the NF-κB pathway. The loss of m6A methylation in macrophages aggravates cytokine production and myocardial damage in mice under septic conditions, whereas forced expression of Spi2a reverses this phenotype. In septic patients, the mRNA expression levels of the human orthologue SERPINA3 negatively correlates with those of the cytokines, TNF, IL-6, IL-1β and IFNγ. Altogether, these findings suggest that m6A methylation of Spi2a negatively regulates macrophage activation in the context of sepsis.

Identification and verification of feature biomarkers associated with immune cells in neonatal sepsis

BackgroundNeonatal sepsis (NS), a life-threatening condition, is characterized by organ dysfunction and is the most common cause of neonatal death. However, the pathogenesis of NS is unclear and the clinical inflammatory markers currently used are not ideal for diagnosis of NS. Thus, exploring the link between immune responses in NS pathogenesis, elucidating the molecular mechanisms involved, and identifying potential therapeutic targets is of great significance in clinical practice. Herein, our study aimed to explore immune-related genes in NS and identify potential diagnostic biomarkers. Datasets for patients with NS and healthy controls were downloaded from the GEO database; GSE69686 and GSE25504 were used as the analysis and validation datasets, respectively. Differentially expressed genes (DEGs) were identified and Gene Set Enrichment Analysis (GSEA) was performed to determine their biological functions. Composition of immune cells was determined and immune-related genes (IRGs) between the two clusters were identified and their metabolic pathways were determined. Key genes with correlation coefficient > 0.5 and p < 0.05 were selected as screening biomarkers. Logistic regression models were constructed based on the selected biomarkers, and the diagnostic models were validated.ResultsFifty-two DEGs were identified, and GSEA indicated involvement in acute inflammatory response, bacterial detection, and regulation of macrophage activation. Most infiltrating immune cells, including activated CD8 + T cells, were significantly different in patients with NS compared to the healthy controls. Fifty-four IRGs were identified, and GSEA indicated involvement in immune response and macrophage activation and regulation of T cell activation. Diagnostic models of DEGs containing five genes (PROS1, TDRD9, RETN, LOC728401, and METTL7B) and IRG with one gene (NSUN7) constructed using LASSO algorithm were validated using the GPL6947 and GPL13667 subset datasets, respectively. The IRG model outperformed the DEG model. Additionally, statistical analysis suggested that risk scores may be related to gestational age and birth weight, regardless of sex.ConclusionsWe identified six IRGs as potential diagnostic biomarkers for NS and developed diagnostic models for NS. Our findings provide a new perspective for future research on NS pathogenesis.

Biomaterial scaffolds regulate macrophage activity to accelerate bone regeneration.

Bones are important for maintaining motor function and providing support for internal organs. Bone diseases can impose a heavy burden on individuals and society. Although bone has a certain ability to repair itself, it is often difficult to repair itself alone when faced with critical-sized defects, such as severe trauma, surgery, or tumors. There is still a heavy reliance on metal implants and autologous or allogeneic bone grafts for bone defects that are difficult to self-heal. However, these grafts still have problems that are difficult to circumvent, such as metal implants that may require secondary surgical removal, lack of bone graft donors, and immune rejection. The rapid advance in tissue engineering and a better comprehension of the physiological mechanisms of bone regeneration have led to a new focus on promoting endogenous bone self-regeneration through the use of biomaterials as the medium. Although bone regeneration involves a variety of cells and signaling factors, and these complex signaling pathways and mechanisms of interaction have not been fully understood, macrophages undoubtedly play an essential role in bone regeneration. This review summarizes the design strategies that need to be considered for biomaterials to regulate macrophage function in bone regeneration. Subsequently, this review provides an overview of therapeutic strategies for biomaterials to intervene in all stages of bone regeneration by regulating macrophages.

1,25-Dihydroxyvitamin D regulates macrophage activation through FBP1/PKR and ameliorates arthritis in TNF-transgenic mice

1,25-Dihydroxyvitamin D (1,25(OH)2D3) has immunomodulatory activity and its deficiency correlates with rheumatoid arthritis (RA) incidence. Whether 1,25(OH)2D3 modulates macrophage activation or protects against RA remains unclear. We demonstrate that 1,25(OH)2D3 suppresses M1 macrophage polarization and CD80, IL-6, CXCL10, IFIT1, IFI44, and double-stranded RNA-dependent protein kinase R (PKR) expression in the macrophages of RA patients. In phorbol 12-myristate 13-acetate-induced THP-1 cells, 1,25(OH)2D3 upregulates fructose-1,6-bisphosphatase 1 (FBP1) expression through direct promoter interaction. FBP1 interacts with PKR and promotes PKR ubiquitination degradation. SiR-FBP1 transfection impairs 1,25(OH)2D3 action and suppresses IL-6, CXCL10, IFIT1, IFI27, and IFI44 expression in macrophages, whereas siR-PKR transfection impairs siR-FBP1 activity in 1,25(OH)2D3-treated macrophages. 1,25(OH)2D3 treatment ameliorates the clinical signs of arthritis in tumor necrosis factor-transgenic mice, inhibits M1 polarization and marker expression, and promotes FBP1 expression in mononuclear cells isolated from swollen joints; thus, 1,25(OH)2D3 suppresses M1 macrophage activation through FBP1/PKR and ameliorates arthritis by restoring the macrophage subtype.

Regulation of Macrophage Activation During Hepatic Fibrogenic Response By Socs1 in Hepatic Stellate Cells

Regulation of Macrophage Activation During Hepatic Fibrogenic Response By Socs1 in Hepatic Stellate Cells

The Ninj1/Dusp1 Axis Contributes to Liver Ischemia Reperfusion Injury by Regulating Macrophage Activation and Neutrophil Infiltration

Liver ischemia-reperfusion (IR) injury represents a major risk factor in both partial hepatectomy and liver transplantation. Nerve injury-induced protein 1 (Ninj1) is widely recognized as an adhesion molecule in leukocyte trafficking under inflammatory conditions, but its role in regulating sterile inflammation during liver IR injury remains unclear. Myeloid Ninj1-deficient mice were generated by bone marrow chimeric models using Ninj1 knockout mice and wild-type mice. Invivo, a liver partial warm ischemia model was applied. Liver injury and hepatic inflammation were investigated. Invitro, primary Kupffer cells (KCs) isolated from Ninj1 knockout and wild-type mice were used to explore the function and mechanism of Ninj1 in modulating KC inflammation upon lipopolysaccharide stimulation. Ninj1 deficiency in KCs protected mice against liver IR injury during the later phase of reperfusion, especially in neutrophil infiltration, intrahepatic inflammation, and hepatocyte apoptosis. This prompted ischemia-primed KCs to decrease proinflammatory cytokine production. Invitro and invivo, using small-interfering RNA against dual-specificity phosphatase 1 (DUSP1), we found that Ninj1 deficiency diminished the inflammatory response in KCs and neutrophil infiltration through DUSP1-dependent deactivation of the c-Jun-N-terminal kinase and p38 pathways. Sivelestat, a neutrophil elastase inhibitor, functioned similarly to Ninj1 deficiency, resulting in both mitigated hepatic IR injury in mice and a more rapid recovery of liver function in patients undergoing liver resection. The Ninj1/Dusp1 axis contributes to liver IR injury by regulating the proinflammatory response of KCs, and influences neutrophil infiltration, partly by subsequent regulation of C-X-C motif chemokine ligand 1 (CXCL1) production after IR.

What Are the Roles of Proprotein Convertases in the Immune Escape of Tumors?

Protein convertases (PCs) play a significant role in post-translational procedures by transforming inactive precursor proteins into their active forms. The role of PCs is crucial for cellular homeostasis because they are involved in cell signaling. They have also been described in many diseases such as Alzheimer's and cancer. Cancer cells are secretory cells that send signals to the tumor microenvironment (TME), remodeling the surrounding space for their own benefits. One of the most important components of the TME is the immune system of the tumor. In this review, we describe recent discoveries that link PCs to the immune escape of tumors. Among PCs, many findings have determined the role of Furin (PC3) as a paramount enzyme causing the TME to induce tumor immune evasion. The overexpression of various cytokines and proteins, for instance, IL10 and TGF-B, moves the TME towards the presence of Tregs and, consequently, immune tolerance. Furthermore, Furin is implicated in the regulation of macrophage activity that contributes to the increased impairment of DCs (dendritic cells) and T effector cells. Moreover, Furin interferes in the MHC Class_1 proteolytic cleavage in the trans-Golgi network. In tumors, the T cytotoxic lymphocytes (CTLs) response is impeded by the PD1 receptor (PD1-R) located on CTLs and its ligand, PDL1, located on cancer cells. The inhibition of Furin is a subtle means of enhancing the antitumor response by repressing PD-1 expression in tumors or macrophage cells. The impacts of other PCs in tumor immune escape have not yet been clarified to the extent that Furin has. Accordingly, the influence of other types of PCs in tumor immune escape is a promising topic for further consideration.

Macrophage-Targeted Sodium Chlorite (NP001) Slows Progression of Amyotrophic Lateral Sclerosis (ALS) through Regulation of Microbial Translocation.

Amyotrophic lateral sclerosis (ALS) is a heterogeneous, progressive, and universally fatal neurodegenerative disease. A subset of ALS patients has measurable plasma levels of lipopolysaccharide (LPS) and C-reactive protein (CRP) consistent with low-grade microbial translocation (MT). Unless interrupted, MT sets up a self-perpetuating loop of inflammation associated with systemic macrophage activation. To test whether MT contributed to ALS progression, blood specimens from a phase 2 study of NP001 in ALS patients were evaluated for changes in activity in treated patients as compared to controls over the 6-month study. In this post hoc analysis, plasma specimens from baseline and six-month timepoints were analyzed. Compared with baseline values, biomarkers related to MT were significantly decreased (LPS, LPS binding protein (LBP), IL-18, Hepatocyte growth factor (HGF), soluble CD163 (sCD163)) in NP001-treated patients as compared to controls, whereas wound healing and immunoregulatory factors were increased (IL-10, Epidermal growth factor (EGF), neopterin) by the end of study. These biomarker results linked to the positive clinical trial outcome confirm that regulation of macrophage activation may be an effective approach for the treatment of ALS and, potentially, other neuroinflammatory diseases related to MT.

Abstract 11998: ADAR1 Mediates Macrophage Activation by Its Non-Editing Activity-Mediated Pri-miRNA Processing in Abdominal Aortic Aneurysm

Introduction: Macrophage activation plays a critical role in abdominal aortic aneurysm (AAA) development. However, molecular mechanisms controlling macrophage activation in AAA remain largely unknown. The objective of the study was to identify novel mechanisms underlying adenosine deaminase acting on RNA (ADAR1) function in macrophage activation and AAA formation. Methods: Aortic transplantation was conducted to determine the importance of non-vascular ADAR1 in AAA development. Angiotensin II (Ang II) infusion of ApoE–/– mouse combined with macrophage-specific knockout of ADAR1 was used to study ADAR1 macrophage-specific role in AAA formation. Primary cultured bone-marrow derived and peritoneal macrophages were used to study how ADAR1 regulates macrophage activation. Moreover, a novel humanized AAA model was established by transplanting human artery to immunodeficient mouse aorta followed by immunity reconstitution with ADAR1-deficient human monocytes to test the role of human macrophages in aneurysm formation in human arteries. Results: Allograft transplantation of wild type abdominal aortas to ADAR1+/- recipient mice significantly attenuated AAA formation, suggesting that non-vascular ADAR1 is essential for AAA development. ADAR1 deficiency in hematopoietic cells decreased the prevalence of AAA while inhibited macrophage infiltration and aorta wall inflammation. ADAR1 deletion blocked the classic macrophage activation, diminished NF-κB signaling, and enhanced the expression of many anti-inflammatory miRNAs. Mechanistically, ADAR1 interacted with Drosha to promote its degradation, which attenuated Drosha-DGCR8 interaction, and consequently inhibited pri- to pre-miRNA processing of miRNAs targeting IKKβ, resulting in an increased IKKβ expression and enhanced NF-κB signaling. Reconstitution of ADAR1-deficient, but not the wild type, human monocytes to immunodeficient mice blocked the aneurysm formation in transplanted human arteries. Conclusions: Macrophage ADAR1 promotes AAA formation in both mouse and human arteries through a novel mechanism, i.e., Drosha protein degradation, which inhibits the processing of miRNAs targeting NF-kB signaling and thus elicits macrophage-mediated vascular inflammation.

EGFR tyrosine kinase activity and Rab GTPases coordinate EGFR trafficking to regulate macrophage activation in sepsis

EGFR phosphorylation is required for TLR4-mediated macrophage activation during sepsis. However, whether and how intracellular EGFR is transported during endotoxemia have largely been unknown. Here, we show that LPS promotes high levels cell surface expression of EGFR in macrophages through two different transport mechanisms. On one hand, Rab10 is required for EEA1-mediated the membrane translocation of EGFR from the Golgi. On the other hand, EGFR phosphorylation prevents its endocytosis in a kinase activity-dependent manner. Erlotinib, an EGFR tyrosine kinase inhibitor, significantly reduced membrane EGFR expression in LPS-activated macrophage. Mechanistically, upon LPS induced TLR4/EGFR phosphorylation, MAPK14 phosphorylated Rab7a at S72 impaired membrane receptor late endocytosis, which maintains EGFR membrane localization though blocking its lysosomal degradation. Meanwhile, Rab5a is also involved in the early endocytosis of EGFR. Subsequently, inhibition of EGFR phosphorylation switches M1 phenotype to M2 phenotype and alleviates sepsis-induced acute lung injury. Mechanistic study demonstrated that Erlotinib suppressed glycolysis-dependent M1 polarization via PKM2/HIF-1ɑ pathway and promoted M2 polarization through up-regulating PPARγ induced glutamine metabolism. Collectively, our data elucidated a more in-depth mechanism of macrophages activation, and provided stronger evidence supporting EGFR as a potential therapeutic target for the treatment of sepsis.

Regulation of macrophage activation by S-Nitrosothiols following ozone-induced lung injury

Acute exposure to ozone causes oxidative stress, characterized by increases in nitric oxide (NO) and other reactive nitrogen species in the lung. NO has been shown to modify thiols generating S-nitrosothiols (SNOs); this results in altered protein function. In macrophages this can lead to changes in inflammatory activity which impact the resolution of inflammation. As SNO formation is dependent on the redox state of both the NO donor and the recipient thiol, the local microenvironment plays a key role in its regulation. This dictates not only the chemical feasibility of SNO formation but also mechanisms by which they may form. In these studies, we compared the ability of the SNO donors, ethyl nitrite (ENO), which targets both hydrophobic and hydrophilic thiols, SNO-propanamide (SNOPPM) which targets hydrophobic thiols, and S-nitroso-N-acetylcysteine. (SNAC) which targets hydrophilic thiols. to modify macrophage activation following ozone exposure. Mice were treated with air or ozone (0.8 ppm, 3 h) followed 1 h later by intranasal administration of ENO, SNOPPM or SNAC (1–500 μM) or appropriate controls. Mice were euthanized 48 h later. Each of the SNO donors reduced ozone-induced inflammation and modified the phenotype of macrophages both within the lung lining fluid and the tissue. ENO and SNOPPM were more effective than SNAC. These findings suggest that the hydrophobic SNO thiol pool targeted by SNOPPM and ENO plays a major role in regulating macrophage phenotype following ozone induced injury.

Cancer cell intrinsic TIM-3 induces glioblastoma progression

Glioblastoma (GBM) is identified to share common signal pathways between glioma and immune cells. Here, we find that Tcell immunoglobulin domain and mucin domain protein 3 (TIM-3) is one of the most common co-inhibitory immune checkpoints in GBM shared by tumor and non-tumor cells. Glioma cell-intrinsic TIM-3 is involved in not only regulating malignant behaviors of glioma cells but also inducing macrophage migration and transition to anti-inflammatory/pro-tumorigenic phenotype by a TIM-3/interleukin 6 (IL6) signal. In mechanism, as one of the major regulators of IL6, TIM-3 regulates its expression through activating NF-κB. Blocking this feedback loop by Tocilizumab, an IL6R inhibitor, inhibited the above effects and repressed the tumorigenicity of GBM invivo. Our work identifies glioma cell-intrinsic functions of TIM-3/IL6 signal mediating the crosstalk feedback loop between glioma cells and tumor-associated macrophages (TAMs). Blocking this feedback loop may provide a novel therapeutic strategy for GBM.