The transcriptional coregulator GRIP1 controls macrophage polarization and metabolic homeostasis

HNF4A mitigates sepsis-associated lung injury by upregulating NCOR2/GR/STAB1 axis and promoting macrophage polarization towards M2 phenotype

Sepsis can trigger systemic inflammation and lead to detrimental effects on several organs, with particular emphasis on the lungs. In sepsis-associated lung injury, macrophages assume a pivotal role, as their overactivation could facilitate the secretion of inflammatory factors and the imbalance of polarization. Hepatocyte nuclear factor 4 alpha (HNF4A) has been reported its potential involvement in the regulation of inflammatory response and macrophage polarization. This study discusses the role and mechanism of HNF4A in sepsis-induced lung damage. HNF4A exhibits a decrease in expression by analyzing the differentially expressed genes in the lungs of septic mice from the Gene Expression Omnibus dataset GSE15379. Then, we established a mouse sepsis model through a cecal ligation and puncture method and observed that the expression of HNF4A was reduced in both lung tissues and alveolar macrophages. To evaluate the function of HNF4A, we overexpressed HNF4A mediated by adenovirus vectors, which were injected into mice. We found that HNF4A overexpression resulted in a higher survival rate in septic mice and an amelioration of pulmonary damage. Meanwhile, HNF4A overexpression mitigated the infiltration of inflammatory cells and impeded the M1 polarization but facilitated the M2 polarization of macrophages in the lung tissues or the alveolar lavage fluid. In vitro, we treated bone marrow-derived macrophages with interleukin-4. Consistent results were obtained that HNF4A overexpression promoted the M2 polarization of macrophages. Mechanistically, we found that HNF4A transcriptionally regulate the expression of nuclear receptor coactivator 2 (NCOA2) through binding to its promoter region. NCOA2 interacted with glucocorticoid receptor (GR). Stabilin 1 (STAB1) was selected as a possible target by transcriptome sequencing analysis. Functional experiments confirmed STAB1 as a downstream target of the HNF4A/NCOA2/GR axis. Overall, this research investigated the potential impact of HNF4A on pulmonary injury in sepsis. It is suggested that one of the regulatory mechanisms involved in this association may be the NCOR2/GR/STAB1 axis.

Disrupting the RNA polymerase II transcription cycle through CDK7 inhibition ameliorates inflammatory arthritis

Macrophages are key drivers of inflammation and tissue damage in autoimmune diseases including rheumatoid arthritis. The rate-limiting step for transcription of more than 70% of inducible genes in macrophages is RNA polymerase II (Pol II) promoter-proximal pause release; however, the specific role of Pol II early elongation control in inflammation, and whether it can be modulated therapeutically, is unknown. Genetic ablation of a pause-stabilizing negative elongation factor (NELF) in macrophages did not affect baseline Pol II occupancy but enhanced the transcriptional response of paused anti-inflammatory genes to lipopolysaccharide followed by secondary attenuation of inflammatory signaling in vitro and in the K/BxN serum transfer mouse model of arthritis. To pharmacologically disrupt the Pol II transcription cycle, we used two covalent inhibitors of the transcription factor II H-associated cyclin-dependent kinase 7 (CDK7), THZ1 and YKL-5-124. Both reduced Pol II pausing in murine and human macrophages, broadly suppressed induction of pro- but not anti-inflammatory genes, and rapidly reversed preestablished inflammatory macrophage polarization. In mice, CDK7 inhibition ameliorated both acute and chronic progressive inflammatory arthritis. Lastly, CDK7 inhibition down-regulated a pathogenic gene expression signature in synovial explants from patients with rheumatoid arthritis. We propose that interfering with Pol II early elongation by targeting CDK7 represents a therapeutic opportunity for rheumatoid arthritis and other inflammatory diseases.

Mechanisms of epigenomic and functional convergence between glucocorticoid- and IL4-driven macrophage programming

Macrophages adopt distinct phenotypes in response to environmental cues, with type-2 cytokine interleukin-4 promoting a tissue-repair homeostatic state (M2IL4). Glucocorticoids (GC), widely used anti-inflammatory therapeutics, reportedly impart a similar phenotype (M2GC), but how such disparate pathways may functionally converge is unknown. We show using integrative functional genomics that M2IL4 and M2GC transcriptomes share a striking overlap mirrored by a shift in chromatin landscape in both common and signal-specific gene subsets. This core homeostatic program is enacted by transcriptional effectors KLF4 and the glucocorticoid receptor, whose genome-wide occupancy and actions are integrated in a stimulus-specific manner by the nuclear receptor cofactor GRIP1. Indeed, many of the M2IL4:M2GC-shared transcriptomic changes were GRIP1-dependent. Consistently, GRIP1 loss attenuated phagocytic activity of both populations in vitro and macrophage tissue-repair properties in the murine colitis model in vivo. These findings provide a mechanistic framework for homeostatic macrophage programming by distinct signals, to better inform anti-inflammatory drug design.

Macrophage polarization: an important role in inflammatory diseases

Macrophages are crucial cells in the human body's innate immunity and are engaged in a variety of non-inflammatory reactions. Macrophages can develop into two kinds when stimulated by distinct internal environments: pro-inflammatory M1-like macrophages and anti-inflammatory M2-type macrophages. During inflammation, the two kinds of macrophages are activated alternatively, and maintaining a reasonably steady ratio is critical for maintaining homeostasis in vivo. M1 macrophages can induce inflammation, but M2 macrophages suppress it. The imbalance between the two kinds of macrophages will have a significant impact on the illness process. As a result, there are an increasing number of research being conducted on relieving or curing illnesses by altering the amount of macrophages. This review summarizes the role of macrophage polarization in various inflammatory diseases, including autoimmune diseases (RA, EAE, MS, AIH, IBD, CD), allergic diseases (allergic rhinitis, allergic dermatitis, allergic asthma), atherosclerosis, obesity and type 2 diabetes, metabolic homeostasis, and the compounds or drugs that have been discovered or applied to the treatment of these diseases by targeting macrophage polarization.

Mechanisms of Epigenomic and Functional Convergence Between Glucocorticoid- and IL4-Driven Macrophage Programming

Macrophages adopt distinct phenotypes in response to environmental cues, with type-2 cytokine interleukin-4 promoting a tissue-repair homeostatic state (M2IL4). Glucocorticoids, widely used anti-inflammatory therapeutics, reportedly impart a similar phenotype (M2GC), but how such disparate pathways may functionally converge is unknown. We show using integrative functional genomics that M2IL4 and M2GC transcriptomes share a striking overlap mirrored by a shift in chromatin landscape in both common and signal-specific gene subsets. This core homeostatic program is enacted by transcriptional effectors KLF4 and the GC receptor, whose genome-wide occupancy and actions are integrated in a stimulus-specific manner by the nuclear receptor cofactor GRIP1. Indeed, many of the M2IL4:M2GC-shared transcriptomic changes were GRIP1-dependent. Consistently, GRIP1 loss attenuated phagocytic activity of both populations in vitro and macrophage tissue-repair properties in the murine colitis model in vivo. These findings provide a mechanistic framework for homeostatic macrophage programming by distinct signals, to better inform anti-inflammatory drug design.

Xinyang tablet ameliorates sepsis-induced myocardial dysfunction by regulating Beclin-1 to mediate macrophage autophagy and M2 polarization through LncSICRNT1 targeting E3 ubiquitin ligase TRAF6

OBJECTIVE

Xinyang Tablet (XYT) has emerged as a potential intervention to counter sepsis-induced myocardial dysfunction (SMID) by influencing macrophage autophagy and M2 polarization. This study aimed to unravel the underlying mechanism of XYT in sepsis-induced myocardial dysfunction (SIMD).

METHODS

A microarray analysis was employed to explore sepsis-related changes, and bioinformatics analysis was used to predict lncRNAs binding to tumor necrosis factor receptor-associated factor 6 (TRAF6). This studio utilized SIMD mouse models induced by lipopolysaccharide (LPS) injection, followed by treatments involving varied doses of XYT, digoxin (positive control), or si-LncSICRNT1. After seven days, evaluations encompassing mouse hair/mental state/diet/weight were measured, and cardiac function via echocardiography were conducted. Myocardial tissue changes were observed using hematoxylin-eosin staining. Additionally, bone marrow-derived macrophages (BMDMs) subjected to LPS for M1 polarization were treated with oe-LncSICRNT1, si-TRAF6 and their negative control, XYT, or autophagy inhibitor 3-Methyladenine (3-MA) (positive control). RT-qPCR and Western blot analyses were employed to assess LncSICRNT1, TRAF6, Beclin-1, LC3II/LC3I, and p62 levels. Immunohistochemistry and flow cytometry were used for M1/M2 polarization markers, while enzyme-linked immunosorbent assay (ELISA) gauged inflammatory factor levels. Interaction between TRAF6 and LncSICRNT1 was probed using RNA pull-down and RNA immunoprecipitation (RIP) assays.

RESULTS

Chip analysis obtained 1463 differentially expressed lncRNAs, including LINC01550 (LncSICRNT1). Further prediction indicated that LncSICRNT1 was highly likely to directly bind to TRAF6. XYT treatment in LPS-induced SIMD mice led to notable enhancements in sleep/hair/diet/activity, increased weight/left ventricular end-diastolic diameter (LVEDd)/LV ejection fraction (LVEF)/LV fraction shortening (LVFS). These improvements were associated with elevated LncSICRNT1 expression and decreased TRAF6 protein levels, culminating in reduced myocardial inflammatory responses and improved cardiac function. Notably, XYT was found to suppress macrophage M1 polarization, while enhancing M2 polarization, ultimately benefitting cardiac function via LncSICRNT1 modulation. Furthermore, the study revealed LncSICRNT1 modulated Beclin-1 ubiquitination and restrained macrophage autophagy by targeting TRAF6 expression.

CONCLUSION

The study highlights XYT's potential to ameliorate LPS-induced SIMD by elevating LncSICRNT1 expression, influencing TRAF6 expression, and regulating Beclin-1 ubiquitination. These actions collectively inhibit macrophage autophagy and foster M1/M2 polarization, contributing to cardiac function improvement.

Modulating glucocorticoid receptor actions in physiology and pathology: Insights from coregulators

Glucocorticoids (GCs) are a class of steroid hormones that regulate key physiological processes such as metabolism, immune function, and stress responses. The effects of GCs are mediated by the glucocorticoid receptor (GR), a ligand-dependent transcription factor that activates or represses the expression of hundreds to thousands of genes in a tissue- and physiological state-specific manner. The activity of GR is modulated by numerous coregulator proteins that interact with GR in response to different stimuli assembling into a multitude of DNA-protein complexes and facilitate the integration of these signals, helping GR to communicate with basal transcriptional machinery and chromatin. Here, we provide a brief overview of the physiological and molecular functions of GR, and discuss the roles of GR coregulators in the immune system, key metabolic tissues and the central nervous system. We also present an analysis of the GR interactome in different cells and tissues, which suggests tissue-specific utilization of GR coregulators, despite widespread functions shared by some of them.

Early diagnosis for the onset of peri-implantitis based on artificial neural network

The aim of this study is to construct an artificial neural network (ANN) based on bioinformatic analysis to enable early diagnosis of peri-implantitis (PI). PI-related datasets were retrieved from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) and functional enrichment analyses were performed between PI and the control group. Furthermore, the infiltration of 22 immune cells in PI was analyzed using CIBERSORT. Hub genes were identified with random forest (RF) classification. The ANN model was then constructed for early diagnosis of PI. A total of 1,380 DEGs were identified. Enrichment analysis revealed the involvement of neutrophil-mediated immunity and the NF-kappa B signaling pathway in PI. Additionally, higher proportion of naive B cells, activated memory CD4 T cells, activated NK cells, M0 macrophages, M1 macrophages, and neutrophils were observed in the soft tissues surrounding PI. From the RF analysis, 13 hub genes (ST6GALNAC4, MTMR11, SKAP2, AKR1B1, PTGS2, CHP2, CPEB2, SYT17, GRIP1, IL10, RAB8B, ABHD5, and IGSF6) were selected. Subsequently, the ANN model for early diagnosis of PI was constructed with high performance. We identified 13 hub genes and developed an ANN model that accurately enables early diagnosis of PI.

A human model of asthma exacerbation reveals transcriptional programs and cell circuits specific to allergic asthma

Asthma is a chronic disease most commonly associated with allergy and type 2 inflammation. However, the mechanisms that link airway inflammation to the structural changes that define asthma are incompletely understood. Using a human model of allergen-induced asthma exacerbation, we compared the lower airway mucosa in allergic asthmatics and allergic non-asthmatic controls using single-cell RNA sequencing. In response to allergen, the asthmatic airway epithelium was highly dynamic and up-regulated genes involved in matrix degradation, mucus metaplasia, and glycolysis while failing to induce injury-repair and antioxidant pathways observed in controls. IL9-expressing pathogenic TH2 cells were specific to asthmatic airways and were only observed after allergen challenge. Additionally, conventional type 2 dendritic cells (DC2 that express CD1C) and CCR2-expressing monocyte-derived cells (MCs) were uniquely enriched in asthmatics after allergen, with up-regulation of genes that sustain type 2 inflammation and promote pathologic airway remodeling. In contrast, allergic controls were enriched for macrophage-like MCs that up-regulated tissue repair programs after allergen challenge, suggesting that these populations may protect against asthmatic airway remodeling. Cellular interaction analyses revealed a TH2-mononuclear phagocyte-basal cell interactome unique to asthmatics. These pathogenic cellular circuits were characterized by type 2 programming of immune and structural cells and additional pathways that may sustain and amplify type 2 signals, including TNF family signaling, altered cellular metabolism, failure to engage antioxidant responses, and loss of growth factor signaling. Our findings therefore suggest that pathogenic effector circuits and the absence of proresolution programs drive structural airway disease in response to type 2 inflammation.

Adipose tissue macrophages as potential targets for obesity and metabolic diseases

Macrophage infiltration into adipose tissue is a key pathological factor inducing adipose tissue dysfunction and contributing to obesity-induced inflammation and metabolic disorders. In this review, we aim to present the most recent research on macrophage heterogeneity in adipose tissue, with a focus on the molecular targets applied to macrophages as potential therapeutics for metabolic diseases. We begin by discussing the recruitment of macrophages and their roles in adipose tissue. While resident adipose tissue macrophages display an anti-inflammatory phenotype and promote the development of metabolically favorable beige adipose tissue, an increase in pro-inflammatory macrophages in adipose tissue has negative effects on adipose tissue function, including inhibition of adipogenesis, promotion of inflammation, insulin resistance, and fibrosis. Then, we presented the identities of the newly discovered adipose tissue macrophage subtypes (e.g. metabolically activated macrophages, CD9+ macrophages, lipid-associated macrophages, DARC+ macrophages, and MFehi macrophages), the majority of which are located in crown-like structures within adipose tissue during obesity. Finally, we discussed macrophage-targeting strategies to ameliorate obesity-related inflammation and metabolic abnormalities, with a focus on transcriptional factors such as PPARγ, KLF4, NFATc3, and HoxA5, which promote macrophage anti-inflammatory M2 polarization, as well as TLR4/NF-κB-mediated inflammatory pathways that activate pro-inflammatory M1 macrophages. In addition, a number of intracellular metabolic pathways closely associated with glucose metabolism, oxidative stress, nutrient sensing, and circadian clock regulation were examined. Understanding the complexities of macrophage plasticity and functionality may open up new avenues for the development of macrophage-based treatments for obesity and other metabolic diseases.

Steroid receptor coactivators - their role in immunity

Steroid Receptor Coactivators (SRCs) are essential regulators of transcription with a wide range of impact on human physiology and pathology. In immunology, SRCs play multiple roles; they are involved in the regulation of nuclear factor-κB (NF-κB), macrophage (MΦ) activity, lymphoid cells proliferation, development and function, to name just a few. The three SRC family members, SRC-1, SRC-2 and SRC-3, can exert their immunological function either in an independent manner or act in synergy with each other. In certain biological contexts, one SRC family member can compensate for lack of activity of another member, while in other cases one SRC can exert a biological function that competes against the function of another family counterpart. In this review we illustrate the diverse biological functionality of the SRCs with regard to their role in immunity. In the light of recent development of SRC small molecule inhibitors and stimulators, we discuss their potential relevance as modulators of the immunological activity of the SRCs for therapeutic purposes.

Physiological Convergence and Antagonism Between GR and PPARγ in Inflammation and Metabolism

Nuclear receptors (NRs) are transcription factors that modulate gene expression in a ligand-dependent manner. The ubiquitously expressed glucocorticoid receptor (GR) and peroxisome proliferator-activated receptor gamma (PPARγ) represent steroid (type I) and non-steroid (type II) classes of NRs, respectively. The diverse transcriptional and physiological outcomes of their activation are highly tissue-specific. For example, in subsets of immune cells, such as macrophages, the signaling of GR and PPARγ converges to elicit an anti-inflammatory phenotype; in contrast, in the adipose tissue, their signaling can lead to reciprocal metabolic outcomes. This review explores the cooperative and divergent outcomes of GR and PPARγ functions in different cell types and tissues, including immune cells, adipose tissue and the liver. Understanding the coordinated control of these NR pathways should advance studies in the field and potentially pave the way for developing new therapeutic approaches to exploit the GR:PPARγ crosstalk.

Areca catechu-(Betel-nut)-induced whole transcriptome changes in a human monocyte cell line that may have relevance to diabetes and obesity; a pilot study

BACKGROUND

Betel-nut consumption is the fourth most common addictive habit globally and there is good evidence linking the habit to obesity, type 2 diabetes (T2D) and the metabolic syndrome. The aim of our pilot study was to identify gene expression relevant to obesity, T2D and the metabolic syndrome using a genome-wide transcriptomic approach in a human monocyte cell line incubated with arecoline and its nitrosated products.

RESULTS

The THP1 monocyte cell line was incubated separately with arecoline and 3-methylnitrosaminopropionaldehyde (MNPA) in triplicate for 24 h and pooled cDNA indexed paired-end libraries were sequenced (Illumina NextSeq 500). After incubation with arecoline and MNPA, 15 and 39 genes respectively had significant changes in their expression (q < 0.05, log fold change 1.5). Eighteen of those genes have reported associations with T2D and obesity in humans; of these genes there was most marked evidence for CLEC10A, MAPK8IP1, NEGR1, NQ01 and INHBE genes.

CONCLUSIONS

Our preliminary studies have identified a large number of genes relevant to obesity, T2D and metabolic syndrome whose expression was changed significantly in human TPH1 cells following incubation with betel-nut derived arecoline or with MNPA. These findings require validation by further cell-based work and investigation amongst betel-chewing communities.

The development of novel glucocorticoid receptor antagonists: From rational chemical design to therapeutic efficacy in metabolic disease models

Glucocorticoids regulate numerous processes in human physiology, but deregulated or excessive glucocorticoid receptor (GR) signaling contributes to the development of various pathologies including metabolic syndrome. For this reason, GR antagonists have considerable therapeutic value. Yet, the only GR antagonist that is clinically approved to date - mifepristone - exhibits cross-reactivity with other nuclear steroid receptors like the progesterone receptor. In this study, we set out to identify novel selective GR antagonists by combining rational chemical design with an unbiased in vitro and in vivo screening approach. Using this pipeline, we were able to identify CORT125329 as the compound with the best overall profile from our octahydro series of novel GR antagonists, and demonstrated that CORT125329 does not exhibit cross-reactivity with the progesterone receptor. Further in vivo testing showed beneficial activities of CORT125329 in models for excessive corticosterone exposure and short- and long-term high-fat diet-induced metabolic complications. Upon CORT125329 treatment, most metabolic parameters that deteriorated upon high-fat diet feeding were similarly improved in male and female mice, confirming activity in both sexes. However, some sexually dimorphic effects were observed including male-specific antagonism of GR activity in brown adipose tissue and female-specific lipid lowering activities after short-term CORT125329 treatment. Remarkably, CORT125329 exhibits beneficial metabolic effects despite its lack of GR antagonism in white adipose tissue. Rather, we propose that CORT125329 treatment restores metabolic activity in brown adipose tissue by stimulating lipolysis, mitochondrial activity and thermogenic capacity. In summary, we have identified CORT125329 as a selective GR antagonist with strong beneficial activities in metabolic disease models, paving the way for further clinical investigation.

Chemical systems biology reveals mechanisms of glucocorticoid receptor signaling

Glucocorticoids display remarkable anti-inflammatory activity, but their use is limited by on-target adverse effects including insulin resistance and skeletal muscle atrophy. We used a chemical systems biology approach, ligand class analysis, to examine ligands designed to modulate glucocorticoid receptor activity through distinct structural mechanisms. These ligands displayed diverse activity profiles, providing the variance required to identify target genes and coregulator interactions that were highly predictive of their effects on myocyte glucose disposal and protein balance. Their anti-inflammatory effects were linked to glucose disposal but not muscle atrophy. This approach also predicted selective modulation in vivo, identifying compounds that were muscle-sparing or anabolic for protein balance and mitochondrial potential. Ligand class analysis defined the mechanistic links between the ligand-receptor interface and ligand-driven physiological outcomes, a general approach that can be applied to any ligand-regulated allosteric signaling system.

The corepressors GPS2 and SMRT control enhancer and silencer remodeling via eRNA transcription during inflammatory activation of macrophages

While the role of transcription factors and coactivators in controlling enhancer activity and chromatin structure linked to gene expression is well established, the involvement of corepressors is not. Using inflammatory macrophage activation as a model, we investigate here a corepressor complex containing GPS2 and SMRT both genome-wide and at the Ccl2 locus, encoding the chemokine CCL2 (MCP-1). We report that corepressors co-occupy candidate enhancers along with the coactivators CBP (H3K27 acetylase) and MED1 (mediator) but act antagonistically by repressing eRNA transcription-coupled H3K27 acetylation. Genome editing, transcriptional interference, and cistrome analysis reveals that apparently related enhancer and silencer elements control Ccl2 transcription in opposite ways. 4C-seq indicates that corepressor depletion or inflammatory signaling functions mechanistically similarly to trigger enhancer activation. In ob/ob mice, adipose tissue macrophage-selective depletion of the Ccl2 enhancer-transcribed eRNA reduces metaflammation. Thus, the identified corepressor-eRNA-chemokine pathway operates in vivo and suggests therapeutic opportunities by targeting eRNAs in immuno-metabolic diseases.

Transcription cofactor GRIP1 differentially affects myeloid cell-driven neuroinflammation and response to IFN-β therapy

Macrophages (MФ) and microglia (MG) are critical in the pathogenesis of multiple sclerosis (MS) and its mouse model, experimental autoimmune encephalomyelitis (EAE). Glucocorticoids (GCs) and interferon β (IFN-β) are frontline treatments for MS, and disrupting each pathway in mice aggravates EAE. Glucocorticoid receptor-interacting protein 1 (GRIP1) facilitates both GR and type I IFN transcriptional actions; hence, we evaluated the role of GRIP1 in neuroinflammation. Surprisingly, myeloid cell-specific loss of GRIP1 dramatically reduced EAE severity, immune cell infiltration of the CNS, and MG activation and demyelination specifically during the neuroinflammatory phase of the disease, yet also blunted therapeutic properties of IFN-β. MФ/MG transcriptome analyses at the bulk and single-cell levels revealed that GRIP1 deletion attenuated nuclear receptor, inflammatory and, interestingly, type I IFN pathways and promoted the persistence of a homeostatic MG signature. Together, these results uncover the multifaceted function of type I IFN in MS/EAE pathogenesis and therapy, and an unexpectedly permissive role of myeloid cell GRIP1 in neuroinflammation.

Typically inhibiting USP14 promotes autophagy in M1-like macrophages and alleviates CLP-induced sepsis

Macrophages, with diverse functions and variable phenotypes, are considered as an important executor of inflammatory diseases. And it has been proved that autophagy is deeply connected with the development of inflammation, while the exact regulatory mechanism still remains unclear, and the application of autophagy regulators in anti-inflammation needs to be further confirmed. Here, we firstly verified that neochromine S5 (hereinafter referred to as S5) significantly inhibited M1-like macrophage polarization with decrease of the proinflammatory cytokines and downregulation of NF-κB and STAT1 signals. Then, in vivo experiments demonstrated S5 improved cecal ligation and puncture (CLP)-induced sepsis specially based on the regulation of M1-like macrophages. Mechanistic studies indicated that S5 treatment dramatically upregulated cellular autophagy in M1-like macrophage. Furthermore, by multiple methods, S5 was revealed to directly bind with ubiquitin-specific proteases 14 (USP14) at Ser404, Phe405, and Cys414 by hydrogen bond to inhibit its deubiquitinating activity, and block USP14-TRAF6 (TNF receptor associated factor 6) interaction, subsequently promoting ubiquitination of Beclin1, interrupting Beclin1-Bcl2 interaction, and accumulating the autophagosome in macrophages, which finally resulted in the blockade of M1-like macrophage polarization. Animal experiments also confirmed the protection of S5 in CLP mice was dependent on activation of macrophage autophagy. What's more, as a novel USP14 inhibitor, S5 exhibited higher efficiency and safety than IU1, the known USP14 inhibitor. Therefore, this study has demonstrated that typically inhibiting USP14 promotes autophagy in M1-like macrophages and alleviates CLP-induced sepsis. Moreover, we provide a new candidate compound, S5, for sensitizing autophagy to interfere with the macrophage inflammation.

Regulations of Glycolytic Activities on Macrophages Functions in Tumor and Infectious Inflammation

Macrophages differentiated into a classically activated (M1) or alternatively activated phenotype (M2) in infection and tumor, but the precise effects of glycolysis and oxidative phosphorylation (OXPHOS) metabolic pathway remain unclear. Herein, the effects of glycolysis or OXPHOS on macrophage polarizations were investigated using a pharmacological approach in mice. 2-Deoxy-D-glucose (2-DG) treatments, which blocks the key enzyme hexokinase of glycolysis, efficiently inhibits a specific switch to M1 lineage, decreasing the secretion of pro-inflammatory cytokines and expressions of co-stimulatory molecules associated with relieving infectious inflammation in vitro and in vivo. Glycolytic activation through the hypoxia-inducible factor-1α (HIF-1α) pathway was required for differentiation to the M1 phenotype, which conferred protection against infection. Dimethyl malonate (DMM) treatment, which blocks the key element succinate of OXPHOS, efficiently inhibits a specific switch to M2 lineage when macrophages receiving M2 stimulation, decreasing the secretion of anti-inflammatory cytokine and CD206 expressions. Mitochondrial dynamic alterations including mitochondrial mass, mitochondrial membrane potential (Dym) and ROS productions were critically for differentiation to the M2 phenotype, which conferred protection against anti-tumor immunity. Glycolysis is also required for macrophage M2 differentiation. Thus, these data provide a basis for a comprehensively understanding the role of glycolysis and OXPHOS in macrophage differentiation during anti-infection and anti-tumor inflammation.

Adipose Tissue Hypertrophy, An Aberrant Biochemical Profile and Distinct Gene Expression in Lipedema

BACKGROUND

Lipedema is a common adipose tissue disorder affecting women, characterized by a symmetric subcutaneous adipose tissue deposition, particularly of the lower extremities. Lipedema is usually underdiagnosed, thus remaining an undertreated disease. Importantly, no histopathologic or molecular hallmarks exist to clearly diagnose the disease, which is often misinterpreted as obesity or lymphedema.

MATERIALS AND METHODS

The aim of the present study is to characterize in detail morphologic and molecular alterations in the adipose tissue composition of lipedema patients compared with healthy controls. Detailed histopathologic and molecular characterization was performed using lipid and cytokine quantification as well as gene expression arrays. The analysis was conducted on anatomically matched skin and fat tissue biopsies as well as fasting serum probes obtained from 10 lipedema and 11 gender and body mass index-matched control patients.

RESULTS

Histologic evaluation of the adipose tissue showed increased intercellular fibrosis and adipocyte hypertrophy. Serum analysis showed an aberrant lipid metabolism without changes in the circulating adipokines. In an adipogenesis gene array, a distinct gene expression profile associated with macrophages was observed. Histologic assessment of the immune cell infiltrate confirmed the increased presence of macrophages, without changes in the T-cell compartment.

CONCLUSIONS

Lipedema presents a distinguishable disease with typical tissue architecture and aberrant lipid metabolism, different to obesity or lymphedema. The differentially expressed genes and immune cell infiltration profile in lipedema patients further support these findings.

Negative elongation factor complex enables macrophage inflammatory responses by controlling anti-inflammatory gene expression

Studies on macrophage gene expression have historically focused on events leading to RNA polymerase II recruitment and transcription initiation, whereas the contribution of post-initiation steps to macrophage activation remains poorly understood. Here, we report that widespread promoter-proximal RNA polymerase II pausing in resting macrophages is marked by co-localization of the negative elongation factor (NELF) complex and facilitated by PU.1. Upon inflammatory stimulation, over 60% of activated transcriptome is regulated by polymerase pause-release and a transient genome-wide NELF dissociation from chromatin, unexpectedly, independent of CDK9, a presumed NELF kinase. Genetic disruption of NELF in macrophages enhanced transcription of AP-1-encoding Fos and Jun and, consequently, AP-1 targets including Il10. Augmented expression of IL-10, a critical anti-inflammatory cytokine, in turn, attenuated production of pro-inflammatory mediators and, ultimately, macrophage-mediated inflammation in vivo. Together, these findings establish a previously unappreciated role of NELF in constraining transcription of inflammation inhibitors thereby enabling inflammatory macrophage activation.

Macrophage activation is integral to innate immunity and inflammation, and involves transcriptome remodeling leading to the rapid upregulation of pro- and anti-inflammatory effector genes. Here the authors show that the negative elongation factor (NELF) complex controls the transcription of anti-inflammatory genes through Pol II pause release.

Mechanisms of Macrophage Polarization in Insulin Signaling and Sensitivity

Type-2 diabetes (T2D) is a disease of two etiologies: metabolic and inflammatory. At the cross-section of these etiologies lays the phenomenon of metabolic inflammation. Whilst metabolic inflammation is characterized as systemic, a common starting point is the tissue-resident macrophage, who's successful physiological or aberrant pathological adaptation to its microenvironment determines disease course and severity. This review will highlight the key mechanisms in macrophage polarization, inflammatory and non-inflammatory signaling that dictates the development and progression of insulin resistance and T2D. We first describe the known homeostatic functions of tissue macrophages in insulin secreting and major insulin sensitive tissues. Importantly we highlight the known mechanisms of aberrant macrophage activation in these tissues and the ways in which this leads to impairment of insulin sensitivity/secretion and the development of T2D. We next describe the cellular mechanisms that are known to dictate macrophage polarization. We review recent progress in macrophage bio-energetics, an emerging field of research that places cellular metabolism at the center of immune-effector function. Importantly, following the advent of the metabolically-activated macrophage, we cover the known transcriptional and epigenetic factors that canonically and non-canonically dictate macrophage differentiation and inflammatory polarization. In closing perspectives, we discuss emerging research themes and highlight novel non-inflammatory or non-immune roles that tissue macrophages have in maintaining microenvironmental and systemic homeostasis.

NCOA2 promotes lytic reactivation of Kaposi's sarcoma-associated herpesvirus by enhancing the expression of the master switch protein RTA

Reactivation of Kaposi’s sarcoma-associated herpesvirus (KSHV) is important for persistent infection in the host as well as viral oncogenesis. The replication and transcription activator (RTA) encoded by KSHV ORF50 plays a central role in the switch from viral latency to lytic replication. Given that RTA is a transcriptional activator and RTA expression is sufficient to activate complete lytic replication, RTA must possess an elaborate mechanism for regulating its protein abundance. Previous studies have demonstrated that RTA could be degraded through the ubiquitin-proteasome pathway. A protein abundance regulatory signal (PARS), which consists of PARS I and PARS II, at the C-terminal region of RTA modulates its protein abundance. In the present study, we identified a host protein named Nuclear receptor coactivator 2 (NCOA2), which can interact with RTA in vitro and in vivo. We further showed that NCOA2 binds to the PARS II domain of RTA. We demonstrated that NCOA2 enhances RTA stability and prevents the proteasome-mediated degradation of RTA by competing with MDM2, an E3 ubiquitin ligase of RTA that interacts with the PARS II domain. Moreover, overexpression of NCOA2 in KSHV-infected cells significantly enhanced the expression level of RTA, which promotes the expression of RTA downstream viral lytic genes and lytic replication. In contrast, silencing of endogenous NCOA2 downregulated the expression of viral lytic genes and impaired viral lytic replication. Interestingly, we also found that RTA upregulates the expression of NCOA2 during lytic reactivation. Taken together, our data support the conclusion that NCOA2 is a novel RTA-binding protein that promotes RTA-driven lytic reactivation by increasing the stability of RTA, and the RTA-NCOA2 positive feedback regulatory loop plays an important role in KSHV reactivation.

Reactivation of KSHV from latency to lytic replication plays an important role in viral spread, establishment of lifelong latent infection and disease progression. RTA, the lytic switch protein, is essential and sufficient for triggering the full viral lytic program. Here, we report a host protein named NCOA2 as a novel RTA-binding protein. Direct interaction of NCOA2 with RTA increased the expression level of RTA. Further study revealed that NCOA2 competes with the E3 ubiquitin ligase of RTA, MDM2, to interact with the PARS II domain of RTA, which inhibits RTA degradation and enhances the stability of RTA. In the context of KSHV-infected cells, we showed that NCOA2 plays an important role in promoting RTA-driven lytic reactivation.

Epigenetic Mechanisms of the Glucocorticoid Receptor

The glucocorticoid receptor (GR) has been shown to be important for mediating cellular responses to stress and circulating glucocorticoids. Ligand-dependent transcriptional changes induced by GR are observed across numerous tissues. However, the mechanisms by which GR achieves cell and tissue-specific effects are less clear. Epigenetic mechanisms have been proposed to explain some of these differences as well as some of the lasting, even transgenerational, effects of stress and glucocorticoid action. GR functions in tandem with epigenetic cellular machinery to coordinate transcription and shape chromatin structure. Here, we describe GR interactions with these effectors and how GR acts to reshape the epigenetic landscape in response to the environment.

Research Trends of Macrophage Polarization: A Bibliometric Analysis

Background:

Macrophage polarization is involved in the development of many diseases such as obesity, diabetes, and cancer. This study aimed to understand the trends and hotspots of macrophage polarization research.

Methods:

We searched through the Web of Science Core Collection database to obtain original articles in this research domain. CiteSpace, HistCite, and VOSviewer software were used to facilitate the analysis and visualization of scientific productivity and emerging trends.

Results:

The survey included 3064 articles, and the annual number of publications exhibited an exponential increase. These articles have received a total of 74,801 citations, and the number of annual citations grew from 68 to 18,074 in a decade. Research on macrophage polarization was performed in 76 countries, and the USA ranked first in terms of research output by contributing 1129 (36.8%) articles. The USA also had the highest H-index, total citations, and highly cited article number. PLOS One, Journal of Immunology, and Scientific Reports were the three journals that published the most articles. Interdisciplinary research areas involving macrophage polarization, such as biomaterials, cancer, and diabetes, were identified by journal citation analysis. The top 20 most productive institutions were located mainly in the USA, France, and China, and top authors originated mainly from the USA and Italy. Tumor biology, obesity, and infection were research hotspots and may be promising in the next few years.

Conclusions:

This study provides a comprehensive analysis that delineates the scientific productivity, collaboration, and research hotspots of macrophage polarization research.

Evaluation of Visceral Adipose Tissue Oxygenation by Blood Oxygen Level-Dependent MRI in Zucker Diabetic Fatty Rats

OBJECTIVE

This study aimed to investigate the feasibility of blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) to evaluate visceral adipose tissue (VAT) oxygenation in Zucker diabetic fatty (ZDF) rats and its associations with systemic metaflammation.

METHODS

Five-week-old ZDF rats and Zucker lean (ZL) rats were fed a high-fat diet (HFD) for 18 weeks. A baseline BOLD-MRI scan of perirenal adipose tissue was performed after 8 weeks of HFD feeding, and then the rats were randomized to receive pioglitazone or a vehicle for the following 10 weeks. At sacrifice, BOLD-MRI scan, Hypoxyprobe-1 injection, and circulating T helper 17 (Th17), regulatory T (Treg) cells, and monocyte subtype flow cytometry analysis were performed.

RESULTS

HFD feeding led to a significant increase in VAT BOLD-MRI R2* signals (20.14 ± 0.23 per second vs. 21.53 ± 0.20 per second; P = 0.012), an indicator for decreased oxygenation. R2* signal was significantly correlated with VAT pimonidazole adduct-positive area, insulin resistance, Th17 and Treg cells, CD43 + and CD43+ + monocyte subtypes, and VAT macrophage infiltration. Pioglitazone treatment improved the insulin resistance and was associated with a delayed progression of VAT oxygenation.

CONCLUSIONS

This work demonstrated the feasibility of BOLD-MRI for detecting the VAT oxygenation status in ZDF rats, and the BOLD-MRI signals were associated with insulin resistance and systemic metaflammation in ZDF rats during the development of obesity.

Gene-specific mechanisms direct glucocorticoid-receptor-driven repression of inflammatory response genes in macrophages

The glucocorticoid receptor (GR) potently represses macrophage-elicited inflammation, however, the underlying mechanisms remain obscure. Our genome-wide analysis in mouse macrophages reveals that pro-inflammatory paused genes, activated via global negative elongation factor (NELF) dissociation and RNA Polymerase (Pol)2 release from early elongation arrest, and non-paused genes, induced by de novo Pol2 recruitment, are equally susceptible to acute glucocorticoid repression. Moreover, in both cases the dominant mechanism involves rapid GR tethering to p65 at NF-kB-binding sites. Yet, specifically at paused genes, GR activation triggers widespread promoter accumulation of NELF, with myeloid cell-specific NELF deletion conferring glucocorticoid resistance. Conversely, at non-paused genes, GR attenuates the recruitment of p300 and histone acetylation, leading to a failure to assemble BRD4 and Mediator at promoters and enhancers, ultimately blocking Pol2 initiation. Thus, GR displays no preference for a specific pro-inflammatory gene class; however, it effects repression by targeting distinct temporal events and components of transcriptional machinery.

Glucocorticoid-induced phosphorylation by CDK9 modulates the coactivator functions of transcriptional cofactor GRIP1 in macrophages

The glucocorticoid (GC) receptor (GR) suppresses inflammation by activating anti-inflammatory and repressing pro-inflammatory genes. GR-interacting protein-1 (GRIP1) is a GR corepressor in macrophages, however, whether GRIP1 mediates GR-activated transcription, and what dictates its coactivator versus corepressor properties is unknown. Here we report that GRIP1 loss in macrophages attenuates glucocorticoid induction of several anti-inflammatory targets, and that GC treatment of quiescent macrophages globally directs GRIP1 toward GR binding sites dominated by palindromic GC response elements (GRE), suggesting a non-redundant GRIP1 function as a GR coactivator. Interestingly, GRIP1 is phosphorylated at an N-terminal serine cluster by cyclin-dependent kinase-9 (CDK9), which is recruited into GC-induced GR:GRIP1:CDK9 hetero-complexes, producing distinct GRE-specific GRIP1 phospho-isoforms. Phosphorylation potentiates GRIP1 coactivator but, remarkably, not its corepressor properties. Consistently, phospho-GRIP1 and CDK9 are not detected at GR transrepression sites near pro-inflammatory genes. Thus, GR restricts actions of its own coregulator via CDK9-mediated phosphorylation to a subset of anti-inflammatory genes.

Glucocorticoid reduces inflammation by both inducing anti-inflammatory genes and suppressing pro-inflammatory genes, but how these two functions are dictated is unclear. Here the authors show that phosphorylated glucocorticoid receptor-interacting protein 1 (GRIP1) serves as a coactivator for this response in macrophage.

Status of M1 and M2 type macrophages in keloid

Macrophages, differentiation from monocytes infiltrated in the wound, have been suggested to be involved and to play an important role in the pathogenesis of wound healing. Nevertheless, no evidence has been established regarding M1 and M2 type macrophages in Keloid. To understand the status of M1 and M2 type macrophages in keloid, immunohistochemistry was performed on 30 cases of Keloid tissues and normal controls, with CD68, typical surface marker for M1 and CD163, well-accepted marker for M2 being immunostained. Meanwhile, the glucocorticoid receptor NR3C1 was also detected. As further confirmation, quantitative real-time PCR was utilized to verify the expression of CD68, CD163 and NR3C1 on mRNA level. It was consistently shown that infiltrated M2 macrophages pronouncedly outnumbered M1 macrophages in the dermis of keloids; and that NR3C1 expression was significantly up-regulated in keloids than that in normal controls. In addition, there was a marked correlation between CD163 and NR3C1 expression. Our results suggest that the number of infiltrated M2 macrophages in the dermis of keloids may be linked to the responsiveness to glucocorticoids in the pathogenesis of keloid.

Plasmodium berghei NK65 in Combination with IFN-γ Induces Endothelial Glucocorticoid Resistance via Sustained Activation of p38 and JNK

Malaria-associated acute respiratory distress syndrome (MA-ARDS) is an often lethal complication of malaria. Currently, no adequate therapy for this syndrome exists. Although glucocorticoids (GCs) have been used to improve clinical outcome of ARDS, their therapeutic benefits remain unclear. We previously developed a mouse model of MA-ARDS, in which dexamethasone treatment revealed GC resistance. In the present study, we investigated GC sensitivity of mouse microvascular lung endothelial cells stimulated with interferon-γ (IFN-γ) and Plasmodium berghei NK65 (PbNK65). Upon challenge with IFN-γ alone, dexamethasone inhibited the expression of CCL5 (RANTES) by 90% and both CCL2 (MCP-1) and CXCL10 (IP-10) by 50%. Accordingly, whole transcriptome analysis revealed that dexamethasone differentially affected several gene clusters and in particular inhibited a large cluster of IFN-γ-induced genes, including chemokines. In contrast, combined stimulation with IFN-γ and PbNK65 extract impaired inhibitory actions of GCs on chemokine release, without affecting the capacity of the GC receptor to accumulate in the nucleus. Subsequently, we investigated the effects of GCs on two signaling pathways activated by IFN-γ. Dexamethasone left phosphorylation and protein levels of signal transducer and activator of transcription 1 (STAT1) unhampered. In contrast, dexamethasone inhibited the IFN-γ-induced activation of two mitogen-activated protein kinases (MAPK), JNK, and p38. However, PbNK65 extract abolished the inhibitory effects of GCs on MAPK signaling, inducing GC resistance. These data provide novel insights into the mechanisms of GC actions in endothelial cells and show how malaria may impair the beneficial effects of GCs.

Glucocorticoid receptors: finding the middle ground

Glucocorticoids (GCs; referred to clinically as corticosteroids) are steroid hormones with potent anti-inflammatory and immune modulatory profiles. Depending on the context, these hormones can also mediate pro-inflammatory activities, thereby serving as primers of the immune system. Their target receptor, the GC receptor (GR), is a multi-tasking transcription factor, changing its role and function depending on cellular and organismal needs. To get a clearer idea of how to improve the safety profile of GCs, recent studies have investigated the complex mechanisms underlying GR functions. One of the key findings includes both pro- and anti-inflammatory roles of GR, and a future challenge will be to understand how such paradoxical findings can be reconciled and how GR ultimately shifts the balance to a net anti-inflammatory profile. As such, there is consensus that GR deserves a second life as a drug target, with either refined classic GCs or a novel generation of nonsteroidal GR-targeting molecules, to meet the increasing clinical needs of today to treat inflammation and cancer.