Modular bioinformatics analysis demonstrates that a Toll‑like receptor signaling pathway is involved in the regulation of macrophage polarization

12,13-diHOME Promotes Inflammatory Macrophages and Epigenetically Modifies Their Capacity to Respond to Microbes and Allergens

Elevated infant fecal concentrations of the bacterial-derived lipid 12,13-dihydroxy-9Z-octadecenoic acid (12,13-diHOME) increase the risk for childhood atopy and asthma. However, the mechanisms by which this lipid contributes to disease development are largely unknown. We hypothesized that macrophages, which are key to both antimicrobial and antigen responses, are functionally and epigenetically modified by 12,13-diHOME leading to short- and long-term dysfunction with consequences for both antimicrobial and antigenic responses. Macrophages exposed to 12,13-diHOME are skewed toward inflammatory IL-1β highCD206low cells, a phenomenon that is further amplified in the presence of common microbial-, aero-, and food-allergens. These IL-1β highCD206low macrophages also exhibit reduced bacterial phagocytic capacity. In primary immune cell coculture assays involving peanut allergen stimulation, 12,13-diHOME promotes both IL-1β and IL-6 production, memory B cell expansion, and increased IgE production. Exposure to 12,13-diHOME also induces macrophage chromatin remodeling, specifically diminishing access to interferon-stimulated response elements resulting in reduced interferon-regulated gene expression upon bacterial lipopolysaccharide stimulation. Thus 12,13-diHOME reprograms macrophage effector function, B-cell interactions and promotes epigenetic modifications that exacerbate inflammatory response to allergens and mutes antimicrobial response along the interferon axis. These observations offer plausible mechanisms by which this lipid promotes early-life pathogenic microbiome development and innate immune dysfunction associated with childhood allergic sensitization.

Somatic USP8 alteration affects the immune landscape of corticotroph pituitary adenomas- a pilot study

INTRODUCTION

Somatic mutations in ubiquitin-specific protease-8 (USP8), encoding a deubiquinating protein, are found in approximately 30% of corticotroph-derived pituitary adenomas (CPAs). Stratifin, a protein encoded by SFN, inhibits USP8 catalytic activity. USP8 has immunomodulating properties that have been demonstrated in non-tumoral diseases.

METHODS

We assessed the influence of USP8 on the immune landscape of CPA and validated this effect and its dependency on stratifin in large cohorts of non-pituitary tumors. We analyzed data of CPA samples (n = 20) and additional non-pituitary tumors from the TCGA database, using transcriptome signature-recognition algorithms. Immune tumor microenvironment (iTME) was compared both by USP8 and SFN expression levels (n = 843) and by USP8 mutation status and SFN expression (n = 12,389).

RESULTS

CPA with activating USP8 mutations was associated with "cold" iTME compared with wild-type USP8 CPA, as reflected by lower fractions of immune cells, including B cells, CD4, regulatory and gamma/delta T cells, natural killer cells, M0 and M1 macrophages, dendritic cells, and eosinophils (p < 0.05 for all comparisons). Pathways altered by the presence of USP8 mutation, based on the most differentially expressed genes (3061 genes), included microglia pathogen phagocytosis and multiple toll-like receptor signaling pathways (p < 0.0001). In a validation analysis based on large cohorts of non-pituitary tumors, high expression of USP8 was associated with a suppressed iTME effect that was augmented by a low SFN expression.

CONCLUSIONS

Our data demonstrate for the first time, to our knowledge, a distinct immune landscape of tumors based on USP8 status and expression and the dependency of this immunological effect on SFN expression.

The GFPT2-O-GlcNAcylation-YBX1 axis promotes IL-18 secretion to regulate the tumor immune microenvironment in pancreatic cancer

The immunosuppressive microenvironment caused by several intrinsic and extrinsic mechanism has brought great challenges to the immunotherapy of pancreatic cancer. We identified GFPT2, the key enzyme in hexosamine biosynthesis pathway (HBP), as an immune-related prognostic gene in pancreatic cancer using transcriptome sequencing and further confirmed that GFPT2 promoted macrophage M2 polarization and malignant phenotype of pancreatic cancer. HBP is a glucose metabolism pathway leading to the generation of uridine diphosphate N-acetylglucosamine (UDP-GlcNAc), which is further utilized for protein O-GlcNAcylation. We confirmed GFPT2-mediated O-GlcNAcylation played an important role in regulating immune microenvironment. Through cellular proteomics, we identified IL-18 as a key downstream of GFPT2 in regulating the immune microenvironment. Through CO-IP and protein mass spectrum, we confirmed that YBX1 was O-GlcNAcylated and nuclear translocated by GFPT2-mediated O-GlcNAcylation. Then, YBX1 functioned as a transcription factor to promote IL-18 transcription. Our study elucidated the relationship between the metabolic pathway of HBP in cancer cells and the immune microenvironment, which might provide some insights into the combination therapy of HBP vulnerability and immunotherapy in pancreatic cancer.

Arsenic album 30C exhibits crystalline nano structure of arsenic trioxide and modulates innate immune markers in murine macrophage cell lines

Macrophages are associated with innate immune response and M1-polarized macrophages exhibit pro-inflammatory functions. Nanoparticles of natural or synthetic compounds are potential triggers of innate immunity. As2O3 is the major component of the homeopathic drug, Arsenic album 30C.This has been claimed to have immune-boosting activities, however, has not been validated experimentally. Here we elucidated the underlying mechanism of Ars. alb 30C-mediated immune priming in murine macrophage cell line. Transmission Electron Microscopy (TEM) and X-ray diffraction (XRD) used for the structural analysis of the drug reveals the presence of crystalline As2O3 nanoparticles of cubic structure. Similarly, signatures of M1-macrophage polarization were observed by surface enhanced Raman scattering (SERS) in RAW 264.7 cells with concomitant over expression of M1 cell surface marker, CD80 and transcription factor, NF-κB, respectively. We also observed a significant increase in pro-inflammatory cytokines like iNOS, TNF-α, IL-6, and COX-2 expression with unaltered ROS and apoptosis in drug-treated cells. Enhanced expression of Toll-like receptors 3 and 7 were observed both in transcriptional and translational levels after the drug treatment. In sum, our findings for the first time indicated the presence of crystalline As2O3 cubic nanostructure in Ars. alb 30C which facilitates modulation of innate immunity by activating macrophage polarization.

Diesel exhaust particles induce polarization state-dependent functional and transcriptional changes in human monocyte-derived macrophages

Macrophage populations exist on a spectrum between the proinflammatory M1 and proresolution M2 states and have demonstrated the ability to reprogram between them after exposure to opposing polarization stimuli. Particulate matter (PM) has been repeatedly linked to worsening morbidity and mortality following respiratory infections and has been demonstrated to modify macrophage function and polarization. The purpose of this study was to determine whether diesel exhaust particles (DEP), a key component of airborne PM, would demonstrate polarization state-dependent effects on human monocyte-derived macrophages (hMDMs) and whether DEP would modify macrophage reprogramming. CD14+CD16- monocytes were isolated from the blood of healthy human volunteers and differentiated into macrophages with macrophage colony-stimulating factor (M-CSF). Resulting macrophages were left unpolarized or polarized into the proresolution M2 state before being exposed to DEP, M1-polarizing conditions (IFN-γ and LPS), or both and tested for phagocytic function, secretory profile, gene expression patterns, and bioenergetic properties. Contrary to previous reports, we observed a mixed M1/M2 phenotype in reprogrammed M2 cells when considering the broader range of functional readouts. In addition, we determined that DEP exposure dampens phagocytic function in all polarization states while modifying bioenergetic properties in M1 macrophages preferentially. Together, these data suggest that DEP exposure of reprogrammed M2 macrophages results in a highly inflammatory, highly energetic subpopulation of macrophages that may contribute to the poor health outcomes following PM exposure during respiratory infections.NEW & NOTEWORTHY We determined that reprogramming M2 macrophages in the presence of diesel exhaust particles (DEP) results in a highly inflammatory mixed M1/M2 phenotype. We also demonstrated that M1 macrophages are particularly vulnerable to particulate matter (PM) exposure as seen by dampened phagocytic function and modified bioenergetics. Our study suggests that PM causes reprogrammed M2 macrophages to become a highly energetic, highly secretory subpopulation of macrophages that may contribute to negative health outcomes observed in humans after PM exposure.

The marriage of immunomodulatory, angiogenic, and osteogenic capabilities in a piezoelectric hydrogel tissue engineering scaffold for military medicine

BACKGROUND

Most bone-related injuries to grassroots troops are caused by training or accidental injuries. To establish preventive measures to reduce all kinds of trauma and improve the combat effectiveness of grassroots troops, it is imperative to develop new strategies and scaffolds to promote bone regeneration.

METHODS

In this study, a porous piezoelectric hydrogel bone scaffold was fabricated by incorporating polydopamine (PDA)-modified ceramic hydroxyapatite (PDA-hydroxyapatite, PHA) and PDA-modified barium titanate (PDA-BaTiO₃, PBT) nanoparticles into a chitosan/gelatin (Cs/Gel) matrix. The physical and chemical properties of the Cs/Gel/PHA scaffold with 0-10 wt% PBT were analyzed. Cell and animal experiments were performed to characterize the immunomodulatory, angiogenic, and osteogenic capabilities of the piezoelectric hydrogel scaffold in vitro and in vivo.

RESULTS

The incorporation of BaTiO₃ into the scaffold improved its mechanical properties and increased self-generated electricity. Due to their endogenous piezoelectric stimulation and bioactive constituents, the as-prepared Cs/Gel/PHA/PBT hydrogels exhibited cytocompatibility as well as immunomodulatory, angiogenic, and osteogenic capabilities; they not only effectively induced macrophage polarization to M2 phenotype but also promoted the migration, tube formation, and angiogenic differentiation of human umbilical vein endothelial cells (HUVECs) and facilitated the migration, osteo-differentiation, and extracellular matrix (ECM) mineralization of MC3T3-E1 cells. The in vivo evaluations showed that these piezoelectric hydrogels with versatile capabilities significantly facilitated new bone formation in a rat large-sized cranial injury model. The underlying molecular mechanism can be partly attributed to the immunomodulation of the Cs/Gel/PHA/PBT hydrogels as shown via transcriptome sequencing analysis, and the PI3K/Akt signaling axis plays an important role in regulating macrophage M2 polarization.

CONCLUSION

The piezoelectric Cs/Gel/PHA/PBT hydrogels developed here with favorable immunomodulation, angiogenesis, and osteogenesis functions may be used as a substitute in periosteum injuries, thereby offering the novel strategy of applying piezoelectric stimulation in bone tissue engineering for the enhancement of combat effectiveness in grassroots troops.

Single-cell mass cytometry on peripheral cells in Myasthenia Gravis identifies dysregulation of innate immune cells

Myasthenia Gravis (MG) is a neurological autoimmune disease characterized by disabling muscle weaknesses due to anti-acetylcholine receptor (AChR) autoantibodies. To gain insight into immune dysregulation underlying early-onset AChR⁺ MG, we performed an in-depth analysis of peripheral mononuclear blood cells (PBMCs) using mass cytometry. PBMCs from 24 AChR⁺ MG patients without thymoma and 16 controls were stained with a panel of 37 antibodies. Using both unsupervised and supervised approaches, we observed a decrease in monocytes, for all subpopulations: classical, intermediate, and non-classical monocytes. In contrast, an increase in innate lymphoid cells 2 (ILC2s) and CD27^- γδ T cells was observed. We further investigated the dysregulations affecting monocytes and γδ T cells in MG. We analyzed CD27^- γδ T cells in PBMCs and thymic cells from AChR⁺ MG patients. We detected the increase in CD27^- γδ T cells in thymic cells of MG patients suggesting that the inflammatory thymic environment might affect γδ T cell differentiation. To better understand changes that might affect monocytes, we analyzed RNA sequencing data from CD14⁺ PBMCs and showed a global decrease activity of monocytes in MG patients. Next, by flow cytometry, we especially confirmed the decrease affecting non-classical monocytes. In MG, as for other B-cell mediated autoimmune diseases, dysregulations are well known for adaptive immune cells, such as B and T cells. Here, using single-cell mass cytometry, we unraveled unexpected dysregulations for innate immune cells. If these cells are known to be crucial for host defense, our results demonstrated that they could also be involved in autoimmunity.

Polarization of tumor-associated macrophages by TLR7/8 conjugated radiosensitive peptide hydrogel for overcoming tumor radioresistance

Radioresistance reduces the antitumor efficiency of radiotherapy and further restricts its clinical application, which is mainly caused by the aggravation of immunosuppressive tumor microenvironment (ITM). Especially tumor-associated macrophages (TAMs) usually display the tumor-promoting M2 phenotype during high-dose fractional radiotherapy mediating radiotherapy resistance. Herein, the toll like receptor agonist TLR7/8a was conjugated with radiosensitive peptide hydrogel (Smac-TLR7/8 hydrogel) to regulate TAMs repolarization from M2 type into M1 type, thus modulating the ITM and overcoming the radioresistance. The Smac-TLR7/8 hydrogel was fabricated through self-assembly with nanofibrous morphology, porous structure and excellent biocompatibility. Upon γ-ray radiation, Smac-TLR7/8 hydrogel effectively polarized the macrophages into M1 type. Notably, combined with radiotherapy, TAMs repolarization regulated by Smac-TLR7/8 hydrogel could increase tumor necrosis factor secretion, activate antitumor immune response and effectively inhibit tumor growth. Moreover, TAMs repolarization rebuilt the ITM and elicited the immunogenic phenotypes in solid tumors, thus enhanced the PD1-blockade efficacy through increasing tumor infiltrating lymphocytes (TILs) and decreasing Treg cells in two different immune activity tumor mice models. Overall, this study substantiated that recruiting and repolarization of TAMs were critical in eliciting antitumor immune response and overcoming radioresistance, thus improving the efficacy of radiotherapy and immunotherapy.

Effect of umbilical cord blood stem cell transplantation on restenosis after endovascular interventional therapy for diabetic hindlimb vascular disease

This study aimed to investigate the mechanism of human umbilical cord blood stem cell (HUCBSC) transplantation on restenosis after percutaneous transluminal angioplasty (PTA) for diabetic hindlimb vascular disease in rabbits. After successfully preparing a rabbit model of diabetic hindlimb vascular disease, 16 rabbits were randomly assigned to two groups. Of these, 8 rabbits received PTA surgery alone (PTA group), and the other 8 rabbits received PTA and HUCBSC (PTA+HUCBSC group) treatments. Five more healthy rabbits were set as healthy control (HC group). Samples were collected after 4 weeks of treatment. The expressions of regulator of calcineurin 1 (RCAN1) and calcineurin A (CnA) in the diseased artery were detected by immunofluorescence staining. The distribution of HUCBSCs was observed by pathological examination in transplanted artery, distal artery, and liver. Cytology experiments were applied to assess the levels of JAK and STAT3, and the migration and proliferation of human aortic vascular smooth muscle cells (HA-VSMC). In the rabbit model of diabetic vascular lesions in the hindlimbs, we found the stenosis of the femoral artery became more and more serious with time, and the expression level of PCNA positive cells was also gradually increased. The expression levels of RCAN1 and CnA in the PTA+HUCBSC group were significantly lower than those in PTA group. HUCBSC inhibited the migration and proliferation of HA-VSMC via JAK/STAT3 pathway. After HUCBSC local transplantation, HUCBSC had no distal tissue distribution. HUCBSC transplantation may prevent restenosis after PTA of diabetic hindlimb vascular disease through JAK/STAT3 pathway.

MiR-19a-3p Suppresses M1 Macrophage Polarization by Inhibiting STAT1/IRF1 Pathway

Macrophages, an important type of immune cells, are generally polarized to classically activated macrophage (M1) or alternatively activated macrophage (M2) to respond to environmental stimuli. Signal transducer and activator of transcription 1 (STAT1), a very important transcription factor, can promote M1 macrophage polarization. However, the mechanisms of regulating STAT1 in macrophage polarization remain unclear. In the present study, STAT1 was markedly elevated, however, miR-19a-3p was down-regulated in interferon (IFN)-γ and lipopolysaccharide (LPS) treated RAW264.7 cells, and dual-luciferase reporter assay identified that miR-19a-3p directly targeted STAT1 by binding to its 3′UTR. Up-regulated miR-19a-3p inhibited M1 polarization by targeting STAT1/interferon regulatory factor 1 (IRF1) and vice versa in vitro. Consistently, overexpression of miR-19a-3p in LPS treated mice by systemically administering agomiR-19a-3p effectively reduced the inflammation in mouse lung tissues, and inhibited M1 macrophage polarization via suppressing STAT1/IRF1 pathway. In summary, our study confirmed that miR-19a-3p, as a direct regulator of STAT1, inhibited M1 macrophages polarization. The miR-19a-3p/STAT1/IRF1 pathway can potentially be used to design novel immunotherapy for modulating macrophage polarization.

A narrative review of tumor-associated macrophages in lung cancer: regulation of macrophage polarization and therapeutic implications

Lung cancer is the deadliest malignancy worldwide. An inflammatory microenvironment is a key factor contributing to lung tumor progression. Tumor-Associated Macrophages (TAMs) are prominent components of the cancer immune microenvironment with diverse supportive and inhibitory effects on growth, progression, and metastasis of lung tumors. Two main macrophage phenotypes with different functions have been identified. They include inflammatory or classically activated (M1) and anti-inflammatory or alternatively activated (M2) macrophages. The contrasting functions of TAMs in relation to lung neoplasm progression stem from the presence of TAMs with varying tumor-promoting or anti-tumor activities. This wide spectrum of functions is governed by a network of cytokines and chemokines, cell-cell interactions, and signaling pathways. TAMs are promising therapeutic targets for non-small cell lung cancer (NSCLC) treatment. There are several strategies for TAM targeting and utilizing them for therapeutic purposes including limiting monocyte recruitment and localization through various pathways such as CCL2-CCR2, CSF1-CSF1R, and CXCL12-CXCR4, targeting the activation of TAMs, genetic and epigenetic reprogramming of TAMs to antitumor phenotype, and utilizing TAMs as the carrier for anti-cancer drugs. In this review, we will outline the role of macrophages in the lung cancer initiation and progression, pathways regulating their function in lung cancer microenvironment as well as the role of these immune cells in the development of future therapeutic strategies.

Blocking NHE1 stimulates glioma tumor immunity by restoring OXPHOS function of myeloid cells

Background: Immunosuppressive tumor microenvironment (TME) in glioblastoma (GBM) is one of the contributing factors for failed immunotherapies. Therefore, there is an urgent need to better understand TME and to identify novel modulators of TME for more effective GBM therapies. We hypothesized that H⁺ extrusion protein Na/H exchanger 1 (NHE1) plays a role in dysregulation of glucose metabolism and immunosuppression of GBM. We investigated the efficacy of blockade of NHE1 activity in combination with temozolomide (TMZ) therapy in increasing anti-tumor immunity. Methods: Mouse syngeneic intracranial glioma model was used to test four treatment regimens: DMSO (Vehicle-control), TMZ, NHE1 specific inhibitor HOE642, or TMZ+HOE642 (T+H) combination. Ex vivo ¹H/¹⁹Fluorine magnetic resonance imaging (MRI) with cell tracking agent Vsense was performed to monitor the infiltration of glioma-associated microglia/myeloid cells (GAMs). Glucose metabolism and transcriptome profiles were analyzed by Seahorse analyzer and bulk RNA-sequencing. The impact of selective Nhe1 deletion in GAMs on sensitivity to anti-PD-1 therapy was evaluated in transgenic NHE1 knockout (KO) mice. Results: Among the tested treatment regimens, the T+H combination therapy significantly stimulated the infiltration of GAMs and T-cells; up-regulated Th1 activation, and mitochondrial oxidative phosphorylation (OXPHOS) pathway genes, increased glucose uptake and mitochondrial mass, and decreased aerobic glycolysis in GAMs. Selective deletion of Nhe1 in Cx3cr1⁺ Nhe1 KO mice increased anti-tumor immunity and sensitivity to TMZ plus anti-PD-1 combinatorial therapy. Conclusions: NHE1 plays a role in developing glioma immunosuppressive TME in part by dysregulating glucose metabolism of GAMs and emerges as a therapeutic target for improving glioma immunity.

Transcriptomics uncovers substantial variability associated with alterations in manufacturing processes of macrophage cell therapy products

Gene expression plasticity is central for macrophages' timely responses to cues from the microenvironment permitting phenotypic adaptation from pro-inflammatory (M1) to wound healing and tissue-regenerative (M2, with several subclasses). Regulatory macrophages are a distinct macrophage type, possessing immunoregulatory, anti-inflammatory, and angiogenic properties. Due to these features, regulatory macrophages are considered as a potential cell therapy product to treat clinical conditions, e.g., non-healing diabetic foot ulcers. In this study we characterized two differently manufactured clinically relevant regulatory macrophages, programmable cells of monocytic origin and comparator macrophages (M1, M2a and M0) using flow-cytometry, RT-qPCR, phagocytosis and secretome measurements, and RNA-Seq. We demonstrate that conventional phenotyping had a limited potential to discriminate different types of macrophages which was ameliorated when global transcriptome characterization by RNA-Seq was employed. Using this approach we confirmed that macrophage manufacturing processes can result in a highly reproducible cell phenotype. At the same time, minor changes introduced in manufacturing resulted in phenotypically and functionally distinct regulatory macrophage types. Additionally, we have identified a novel constellation of process specific biomarkers, which will support further clinical product development.

Transcriptional, Epigenetic and Metabolic Programming of Tumor-Associated Macrophages

Macrophages are key innate immune cells in the tumor microenvironment (TME) that regulate primary tumor growth, vascularization, metastatic spread and tumor response to various types of therapies. The present review highlights the mechanisms of macrophage programming in tumor microenvironments that act on the transcriptional, epigenetic and metabolic levels. We summarize the latest knowledge on the types of transcriptional factors and epigenetic enzymes that control the direction of macrophage functional polarization and their pro- and anti-tumor activities. We also focus on the major types of metabolic programs of macrophages (glycolysis and fatty acid oxidation), and their interaction with cancer cells and complex TME. We have discussed how the regulation of macrophage polarization on the transcriptional, epigenetic and metabolic levels can be used for the efficient therapeutic manipulation of macrophage functions in cancer.

Myricetin Modulates Macrophage Polarization and Mitigates Liver Inflammation and Fibrosis in a Murine Model of Nonalcoholic Steatohepatitis

This study aimed to investigate the beneficial effects of myricetin in a diet-induced nonalcoholic steatohepatitis (NASH) model and the underlying mechanism. C57BL/6J mice were fed a standard chow or the choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) for 8 weeks with the treatment of myricetin (100 mg/kg) or vehicle by daily gavage. Hepatic inflammation, steatosis, fibrosis, and hepatic stellate cells (HSC) activation were assessed. We also analyzed M1 and M2 macrophages and its related markers in livers from NASH mice and in RAW264.7 macrophages stimulated by lipopolysaccharide (LPS) or interleukin 4 (IL-4) in vitro. Furthermore, we determined the effect of myricetin on the triggering receptor expressed on myeloid cells-1 (TREM-1), toll like receptor (TLR) 2 and 4, and myeloid differentiation factor 88 (MyD88) signaling both in livers from mice and in RAW264.7 cells stimulated by LPS. Our results revealed that myricetin remarkably ameliorated hepatic steatosis, inflammation, and inhibited hepatic macrophage infiltration in CDAHFD-fed mice. Myricetin-treated to CDAHFD-fed mice also inhibited liver fibrosis and HSC activation when compared with vehicle-treated to those mice. Moreover, myricetin inhibited M1 macrophage polarization and its relative markers in livers of NASH mice while induced M2 polarization. Similarly, in vitro study, myricetin inhibited the LPS-induced mRNA expression of M1 macrophages marker genes and induced IL-4-induced M2 macrophage marker genes in RAW264.7 macrophages. Mechanically, myricetin inhibited the expression of TREM-1 and TLR2/4-MyD88 signaling molecules in livers from NASH mice and in RAW264.7 macrophages stimulated by LPS in vitro. Additionally, myricetin inhibited the activation of nuclear factor (NF)-κB signaling and the phosphorylation of the signal transducer and activation of transcription 3 (STAT3) in LPS-stimulated RAW264.7 macrophages. Taken together, our data indicated that myricetin modulated the polarization of macrophages via inhibiting the TREM-1-TLR2/4-MyD88 signaling molecules in macrophages and therefore mitigated NASH and hepatic fibrosis in the CDAHFD-diet-induced NASH model in mice.