CXCL10-Mediates Macrophage, but not Other Innate Immune Cells-Associated Inflammation in Murine Nonalcoholic Steatohepatitis

M1-type polarized macrophage contributes to brain damage through CXCR3.2/CXCL11 pathways after RGNNV infection in grouper

The vertebrate central nervous system (CNS) is the most complex system of the body. The CNS, especially the brain, is generally regarded as immune-privileged. However, the specialized immune strategies in the brain and how immune cells, specifically macrophages in the brain, respond to virus invasion remain poorly understood. Therefore, this study aimed to examine the potential immune response of macrophages in the brain of orange-spotted groupers (Epinephelus coioides) following red-spotted grouper nervous necrosis virus (RGNNV) infection. We observed that RGNNV induced macrophages to produce an inflammatory response in the brain of orange-spotted grouper, and the macrophages exhibited M1-type polarization after RGNNV infection. In addition, we found RGNNV-induced macrophage M1 polarization via the CXCR3.2- CXCL11 pathway. Furthermore, we observed that RGNNV triggered M1 polarization in macrophages, resulting in substantial proinflammatory cytokine production and subsequent damage to brain tissue. These findings reveal a unique mechanism for brain macrophage polarization, emphasizing their role in contributing to nervous tissue damage following viral infection in the CNS.

Role and therapeutic perspectives of extracellular vesicles derived from liver and adipose tissue in metabolic dysfunction-associated steatotic liver disease

The global epidemic of metabolic diseases has led to the emergence of metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH), which pose a significant threat to human health. Despite recent advances in research on the pathogenesis and treatment of MASLD/MASH, there is still a lack of more effective and targeted therapies. Extracellular vesicles (EVs) discovered in a wide range of tissues and body fluids encapsulate different activated biomolecules and mediate intercellular communication. Recent studies have shown that EVs derived from the liver and adipose tissue (AT) play vital roles in MASLD/MASH pathogenesis and therapeutics, depending on their sources and intervention types. Besides, adipose-derived stem cell (ADSC)-derived EVs appear to be more effective in mitigating MASLD/MASH. This review presents an overview of the definition, extraction strategies, and characterisation of EVs, with a particular focus on the biogenesis and release of exosomes. It also reviews the effects and potential molecular mechanisms of liver- and AT-derived EVs on MASLD/MASH, and emphasises the contribution and clinical therapeutic potential of ADSC-derived EVs. Furthermore, the future perspective of EV therapy in a clinical setting is discussed.

The hepatocyte epidermal growth factor receptor (EGFR) pathway regulates the cellular interactome within the liver fibrotic niche

Liver fibrosis is the consequence of chronic liver injury in the presence of an inflammatory component. Although the main executors of this activation are known, the mechanisms that lead to the inflammatory process that mediates the production of pro-fibrotic factors are not well characterized. Epidermal growth factor receptor (EGFR) signaling in hepatocytes is essential for the regenerative processes of the liver; however, its potential role in regulating the fibrotic niche is not yet clear. Our group generated a mouse model that expresses an inactive truncated form of the EGFR specifically in hepatocytes (ΔEGFR mice). Here, we have analyzed the response of WT and ΔEGFR mice to chronic treatment with carbon tetrachloride (CCl4), which induces a pro-inflammatory and fibrotic process in the liver. The results indicated that the hallmarks of liver fibrosis were attenuated in CCl4-treated ΔEGFR mice when compared with CCl4-treated WT mice, coinciding with a faster resolution of the fibrotic process and ameliorated damage. The absence of EGFR activity in hepatocytes induced changes in the pattern of immune cells in the liver, with a notable increase in the population of M2 macrophages, more related to fibrosis resolution, as well as in the population of lymphocytes related to eradication of the damage. Transcriptome analysis of hepatocytes, and secretome studies of extracellular media from in vitro experiments, allowed us to elucidate the specific molecular mechanisms regulated by EGFR that mediate hepatocyte production of both pro-fibrotic and pro-inflammatory mediators; these have consequences for the deposition of extracellular matrix proteins, as well as for the immune microenvironment. Overall, our study uncovered novel mechanistic insights regarding EGFR kinase-dependent actions in hepatocytes that reveal its key role in chronic liver damage. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Immunoregulatory mechanisms between epithelial clear cells and mononuclear phagocytes in the epididymis

INTRODUCTION

One of the most intriguing aspects of male reproductive physiology is the ability of the epididymis to prevent the mounting of immune responses against the onslaught of foreign antigens carried by spermatozoa while initiating very efficient immune responses versus stressors. Epithelial clear cells are strategically positioned to work in a concerted manner with region-specific heterogeneous subsets of mononuclear phagocytes to survey the epididymal barrier and regulate the balance between inflammation and immune tolerance in the post-testicular environment.

OBJECTIVE

This review aims to describe how clear cells communicate with mononuclear phagocytes to contribute to the unique immune environment in which sperm mature and are stored in the epididymis.

MATERIALS/METHODS

A comprehensive systematic review was performed. PubMed was searched for articles specific to clear cells, mononuclear phagocytes, and epididymis. Articles that did not specifically address the target material were excluded.

RESULTS

In this review, we discuss the unexpected roles of clear cells, including the transfer of new proteins to spermatozoa via extracellular vesicles and nanotubes as they transit along the epididymal tubule; and we summarize the immune phenotype, morphology, and antigen capturing, processing, and presenting abilities of mononuclear phagocytes. Moreover, we present the current knowledge of immunoregulatory mechanisms by which clear cells and mononuclear phagocytes may contribute to the immune-privileged environment optimal for sperm maturation and storage.

DISCUSSION AND CONCLUSION

Notably, we provide an in-depth characterization of clear cell-mononuclear phagocyte communication networks in the steady-state epididymis and in the presence of injury. This review highlights crucial concepts of mucosal immunology and cellcell interactions, all of which are critical but understudied facets of human male reproductive health.

Diosmetin as a promising natural therapeutic agent: In vivo, in vitro mechanisms, and clinical studies

Diosmetin, a natural occurring flavonoid, is primarily found in citrus fruits, beans, and other plants. Diosmetin demonstrates a variety of pharmacological activities, including anticancer, antioxidant, anti-inflammatory, antibacterial, metabolic regulation, cardiovascular function improvement, estrogenic effects, and others. The process of literature search was done using PubMed, Web of Science and ClinicalTrials databases with search terms containing Diosmetin, content, anticancer, anti-inflammatory, antioxidant, pharmacological activity, pharmacokinetics, in vivo, and in vitro. The aim of this review is to summarize the in vivo, in vitro and clinical studies of Diosmetin over the last decade, focusing on studies related to its anticancer, anti-inflammatory, and antioxidant activities. It is found that DIO has significant therapeutic effects on skin and cardiovascular system diseases, and its research in pharmacokinetics and toxicology is summarized. It provides the latest information for researchers and points out the limitations of current research and areas that should be strengthened in future research, so as to facilitate the relevant scientific research and clinical application of DIO.

Multicolor Two-Photon Microscopy Imaging of Lipid Droplets and Liver Capsule Macrophages In Vivo

Lipid droplets (LDs) store energy and supply fatty acids and cholesterol. LDs are a hallmark of chronic nonalcoholic fatty liver disease (NAFLD). Recently, studies have focused on the role of hepatic macrophages in NAFLD. Green fluorescent protein (GFP) is used for labeling the characteristic targets in bioimaging analysis. Cx3cr1-GFP mice are widely used in studying the liver macrophages such as the NAFLD model. Here, we have developed a tool for two-photon microscopic observation to study the interactions between LDs labeled with LD2 and liver capsule macrophages labeled with GFP in vivo. LD2, a small-molecule two-photon excitation fluorescent probe for LDs, exhibits deep-red (700 nm) fluorescence upon excitation at 880 nm, high cell staining ability and photostability, and low cytotoxicity. This probe can clearly observe LDs through two-photon microscopy (TPM) and enables the simultaneous imaging of GFP+ liver capsule macrophages (LCMs) in vivo in the liver capsule of Cx3cr1-GFP mice. In the NAFLD mouse model, Cx3cr1+ LCMs and LDs increased with the progress of fatty liver disease, and spatiotemporal changes in LCMs were observed through intravital 3D TPM images. LD2 will aid in studying the interactions and immunological roles of hepatic macrophages and LDs to better understand NAFLD.

Therapeutic Activity of Resolvin D1 (RvD1) in Murine MASH

Background and Aims

Recent studies have highlighted the beneficial effect of resolvin D1 (RvD1), a DHA-derived specialized pro-resolving mediator, on metabolic dysfunction-associated steatohepatitis (MASH), but the underlying mechanisms are not well understood. Our study aims to determine the mechanism by which RvD1 protects against MASH progression.

Methods

RvD1 was administered to mice with experimental MASH, followed by bulk and single-cell RNA sequencing analysis. Primary cells including bone marrow-derived macrophages (BMDMs), Kupffer cells, T cells, and primary hepatocytes were isolated to elucidate the effect of RvD1 on inflammation, cell death, and fibrosis regression genes.

Results

Hepatic tissue levels of RvD1 were decreased in murine and human MASH, likely due to an expansion of pro-inflammatory M1-like macrophages with diminished ability to produce RvD1. Administering RvD1 reduced inflammation, cell death, and liver fibrosis. Mechanistically, RvD1 reduced inflammation by suppressing the Stat1-Cxcl10 signaling pathway in macrophages and prevented hepatocyte death by alleviating ER stress-mediated apoptosis. Moreover, RvD1 induced Mmp2 and decreased Acta2 expression in hepatic stellate cells (HSCs), and promoted Mmp9 and Mmp12 expression in macrophages, leading to fibrosis regression in MASH.

Conclusions

RvD1 reduces Stat1-mediated inflammation, mitigates ER stress-induced apoptosis, and promotes MMP-mediated fibrosis regression in MASH. This study highlights the therapeutic potential of RvD1 to treat MASH.

The "Domino effect" in MASLD: The inflammatory cascade of steatohepatitis

Metabolic dysfunction-associated steatotic liver disease (MASLD) is an increasingly common complication of obesity, affecting over a quarter of the global adult population. A key event in the pathophysiology of MASLD is the development of metabolic-associated steatohepatitis (MASH), which greatly increases the chances of developing cirrhosis and hepatocellular carcinoma. The underlying cause of MASH is multifactorial, but accumulating evidence indicates that the inflammatory process in the hepatic microenvironment typically follows a pattern that can be roughly divided into three stages: (1) Detection of hepatocyte stress by tissue-resident immune cells including γδ T cells and CD4-CD8- double-negative T cells, followed by their secretion of pro-inflammatory mediators, most notably IL-17A. (2) Recruitment of pro-inflammatory cells, mostly of the myeloid lineage, and initiation of inflammation through secretion of effector-type cytokines such as TNF, TGF-β, and IL-1β. (3) Escalation of the inflammatory response by recruitment of lymphocytes including Th17, CD8 T, and B cells leading to chronic inflammation, hepatic stellate cell activation, and fibrosis. Here we will discuss these three stages and how they are consecutively linked like falling domino tiles to the pathophysiology of MASH. Moreover, we will highlight the clinical potential of inflammation as a biomarker and therapeutic target for the treatment of MASLD.

Anti-Inflammatory Properties of the Citrus Flavonoid Diosmetin: An Updated Review of Experimental Models

Inflammation is an essential contributor to various human diseases. Diosmetin (3',5,7-trihydroxy-4'-methoxyflavone), a citrus flavonoid, can be used as an anti-inflammatory agent. All the information in this article was collected from various research papers from online scientific databases such as PubMed and Web of Science. These studies have demonstrated that diosmetin can slow down the progression of inflammation by inhibiting the production of inflammatory mediators through modulating related pathways, predominantly the nuclear factor-κB (NF-κB) signaling pathway. In this review, we discuss the anti-inflammatory properties of diosmetin in cellular and animal models of various inflammatory diseases for the first time. We have identified some deficiencies in current research and offer suggestions for further advancement. In conclusion, accumulating evidence so far suggests a very important role for diosmetin in the treatment of various inflammatory disorders and suggests it is a candidate worthy of in-depth investigation.

The role of extracellular vesicles in non-alcoholic steatohepatitis: Emerging mechanisms, potential therapeutics and biomarkers

Non-alcoholic steatohepatitis (NASH), an emerging global healthcare problem, has become the leading cause of liver transplantation in recent decades. No effective therapies in the clinic have been proven due to the incomplete understanding of the pathogenesis of NASH, and further studies are expected to continue to delve into the mechanisms of NASH. Extracellular vesicles (EVs), which are small lipid membrane vesicles carrying proteins, microRNAs and other molecules, have been identified to play a vital role in cell-to-cell communication and are involved in the development and progression of various diseases. In recent years, there has been increasing interest in the role of EVs in NASH. Many studies have revealed that EVs mediate important pathological processes in NASH, and the role of EVs in NASH is distinct and variable depending on their origin cells and target cells. This review outlines the emerging mechanisms of EVs in the development of NASH and the preclinical evidence related to stem cell-derived EVs as a potential therapeutic strategy for NASH. Moreover, possible strategies involving EVs as clinical diagnostic, staging and prognostic biomarkers for NASH are summarized.

Diabetes Mellitus, Energy Metabolism, and COVID-19

Obesity, diabetes mellitus (mostly type 2), and COVID-19 show mutual interactions because they are not only risk factors for both acute and chronic COVID-19 manifestations, but also because COVID-19 alters energy metabolism. Such metabolic alterations can lead to dysglycemia and long-lasting effects. Thus, the COVID-19 pandemic has the potential for a further rise of the diabetes pandemic. This review outlines how preexisting metabolic alterations spanning from excess visceral adipose tissue to hyperglycemia and overt diabetes may exacerbate COVID-19 severity. We also summarize the different effects of SARS-CoV-2 infection on the key organs and tissues orchestrating energy metabolism, including adipose tissue, liver, skeletal muscle, and pancreas. Last, we provide an integrative view of the metabolic derangements that occur during COVID-19. Altogether, this review allows for better understanding of the metabolic derangements occurring when a fire starts from a small flame, and thereby help reducing the impact of the COVID-19 pandemic.

Enhancement of Tumorigenicity, Spheroid Niche, and Drug Resistance of Pancreatic Cancer Cells in Three-Dimensional Culture System

The three-dimensional (3D) cell culture technique has been applied comprehensively as a variable platform for medical research, biochemical signal pathway analysis, and evaluation of anti-tumor treatment response due to an excellent recapitulation of a tumor microenvironment (TME) in the in vitro cultured cancer cells. Pancreatic cancer (PaC) is one of the toughest malignancies with a complex TME and refractory treatment response. To comprehensively study the TME of PaC, there is an eager need to develop a 3D culture model to decompose the cellular components and their cross interactions. Herein, we establish a 3D PaC culture system with cancer stem cell (CSC) and scalability properties. To validate our model, we tested the individual PaC cell and the combined effects with cancer-associated fibroblasts (CAFs) on cancer tumorigenicity, the cellular interaction through the CXCR3/CXCL10 axis, and cellular responses reflection of anti-cancer treatments. With the help of our 3D technology, a simulated malignant spheroid with important stromal populations and TME physiochemical properties may be successfully recreated. It can be used in a wide range of preclinical research and helpful in advancing basic and translational cancer biology.

Key genes involved in nonalcoholic steatohepatitis improvement after bariatric surgery

Background

Nonalcoholic steatohepatitis (NASH) is the advanced stage of nonalcoholic fatty liver disease (NAFLD), one of the most prevalent chronic liver diseases. The effectiveness of bariatric surgery in treating NASH and preventing or even reversing liver fibrosis has been demonstrated in numerous clinical studies, but the underlying mechanisms and crucial variables remain unknown.

Methods

Using the GSE135251 dataset, we examined the gene expression levels of NASH and healthy livers. Then, the differentially expressed genes (DEGs) of patients with NASH, at baseline and one year after bariatric surgery, were identified in GSE83452. We overlapped the hub genes performed by protein-protein interaction (PPI) networks and DEGs with different expression trends in both datasets to obtain key genes. Genomic enrichment analysis (GSEA) and genomic variation analysis (GSVA) were performed to search for signaling pathways of key genes. Meanwhile, key molecules that regulate the key genes are found through the construction of the ceRNA network. NASH mice were induced by a high-fat diet (HFD) and underwent sleeve gastrectomy (SG). We then cross-linked the DEGs in clinical and animal samples using quantitative polymerase chain reaction (qPCR) and validated the key genes.

Results

Seven key genes (FASN, SCD, CD68, HMGCS1, SQLE, CXCL10, IGF1) with different expression trends in GSE135251 and GSE83452 were obtained with the top 30 hub genes selected by PPI. The expression of seven key genes in mice after SG was validated by qPCR. Combined with the qPCR results from NASH mice, the four genes FASN, SCD, HMGCS1, and CXCL10 are consistent with the biological analysis. The GSEA results showed that the 'cholesterol homeostasis' pathway was enriched in the FASN, SCD, HMGCS1, and SQLE high-expression groups. The high-expression groups of CD68 and CXCL10 were extremely enriched in inflammation-related pathways. The construction of the ceRNA network obtained microRNAs and ceRNAs that can regulate seven key genes expression.

Conclusion

In summary, this study contributes to our understanding of the mechanisms by which bariatric surgery improves NASH, and to the development of potential biomarkers for the treatment of NASH.

Inducible nitric oxide synthase accelerates nonalcoholic fatty liver disease progression by regulating macrophage autophagy

BACKGROUND

Cells and tissues, such as macrophages, express inducible nitric oxide synthase (INOS) after stimulation by certain factors. INOS helps mediate the macrophage inflammatory reaction, but few studies have explored how INOS affects macrophage function in nonalcoholic fatty liver disease (NAFLD).

OBJECTIVE

This study investigated the role of INOS-mediated macrophage activity in NAFLD.

METHODS

A high-fat diet was used to establish an NAFLD mouse model. After 12 weeks, blood was collected for immune cell and lipid analyses, and liver tissues were collected for pathological analyses with hematoxylin and eosin and Oil Red O staining. Peritoneal macrophages were extracted in situ, cultured in Dulbecco's modified Eagle's medium, and stimulated with palmitic acid to mimic in vivo conditions for further assays. Real-time polymerase chain reaction, western blot analysis, and immunofluorescence were used to verify the expression of target genes or proteins.

RESULTS

In the NAFLD model, INOS expression in macrophages increased, and INOS knockdown significantly decreased the number of macrophages. Pathological examinations confirmed that INOS knockdown slowed NAFLD progression and macrophage infiltration during inflammation. INOS knockdown also enhanced phagocytosis and lipid transport by macrophages, and increased the expression of autophagy-related molecules in macrophages, which improved the autophagy level, promoted apoptotic cell degradation, and maintained intracellular environment homeostasis.

CONCLUSIONS

These results indicate a correlation between INOS expression and macrophage function in NAFLD.

C-X-C domain ligand 14-mediated stromal cell-macrophage interaction as a therapeutic target for hand dermal fibrosis

Dupuytren's contracture, a superficial dermal fibrosis, causes flexion contracture of the affected finger, impairing hand function. Specific single-nucleotide polymorphisms within genes in the Wnt signalling pathway are associated with the disease. However, the precise role of Wnt signalling dysregulation in the onset and progression of Dupuytren's contracture remains unclear. Here, using a fibrosis mouse model and clinical samples of human Dupuytren's contractures, we demonstrate that the activation of Wnt/β-catenin signalling in Tppp3-positive cells in the dermis of the paw is associated with the development of fibrosis. Fibrosis development and progression via Wnt/β-catenin signalling are closely related to stromal cell-macrophage interactions, and Wnt/β-catenin signalling activation in Tppp3-positive stromal cells causes M2 macrophage infiltration via chemokine Cxcl14, resulting in the formation of a TGF-β-expressing fibrotic niche. Inhibition of Cxcl14 mitigates fibrosis by decreasing macrophage infiltration. These findings suggest that Cxcl14-mediated stromal cell-macrophage interaction is a promising therapeutic target for Wnt/β-catenin-induced fibrosis.

Immunometabolic Profile Associated with Progressive Damage of the Intestinal Mucosa in Adults Screened for Colorectal Cancer: Association with Diet

Environmental factors such as diet and lifestyle have been shown to influence the development of some intestinal mucosal lesions that may be precursors of colorectal cancer (CRC). The presence of these alterations seems to be associated with misbalanced immunological parameter levels. However, it is still unclear as to which immunological parameters are altered in each phase of CRC development. In this work, we aimed to study the potential relationships of immunological and metabolic parameters with diet in a CRC-related lesion context. Dietary information was obtained using an annual semi-quantitative food-frequency questionnaire (FFQ) from 93 volunteers classified via colonoscopy examination according to the presence of intestinal polyps or adenocarcinoma. Cytokines, chemokines, and adipokines were determined from serum samples. We observed a reduction in adiponectin according to the damage to the mucosa, accompanied by an increase and decrease in C-X-C motif chemokine ligand 10 (CXCL10) and resistin, respectively, in CRC cases. The presence of aberrant crypt foci (ACF) in the polyp group was associated with higher tumor necrosis factor-alpha (TNF-α) concentrations. Vegetables were directly correlated with adiponectin and resistin levels, while the opposite occurred with red meat. A bioactive compound, soluble pectin, showed a negative association with TNF-α. Future dietary strategies could be developed to modulate specific immunological parameters in the context of CRC.

Immune Features of Disparate Liver Transplant Outcomes in Female Hispanics With Nonalcoholic Steatohepatitis

Background

Nonalcoholic steatohepatitis (NASH) is a severe immune-mediated stage of nonalcoholic fatty liver disease that is rapidly becoming the most common etiology requiring liver transplantation (LT), with Hispanics bearing a disproportionate burden. This study aimed to uncover the underlying immune mechanisms of the disparities experienced by Hispanic patients undergoing LT for NASH.

Methods

We enrolled 164 LT recipients in our institutional review board-approved study, 33 of whom presented with NASH as the primary etiology of LT (20%), with 16 self-reported as Hispanic (48%). We investigated the histopathology of prereperfusion and postreperfusion biopsies, clinical liver function tests, longitudinal soluble cytokines via 38-plex Luminex, and immune cell phenotypes generated by prereperfusion and postreperfusion blood using 14-color flow cytometry and enzyme-linked immunosorbent assay.

Results

Hispanic LT recipients transplanted for NASH were disproportionately female (81%) and disproportionately suffered poor outcomes in the first year posttransplant, including rejection (26%) and death (38%). Clinically, we observed increased pro-inflammatory and apoptotic histopathological features in biopsies, increased AST/international normalized ratio early posttransplantation, and a higher incidence of presensitization to mismatched HLA antigens expressed by the donor allograft. Experimental investigations revealed that blood from female Hispanic NASH patients showed significantly increased levels of leukocyte-attracting chemokines, innate-to-adaptive switching cytokines and growth factors, HMGB1 release, and TLR4/TLR8/TLR9/NOD1 activation, and produced a pro-inflammatory, pro-apoptotic macrophage phenotype with reduced CD14/CD68/CD66a/TIM-3 and increased CD16/CD11b/HLA-DR/CD80.

Conclusions

A personalized approach to reducing immunological risk factors is urgently needed for this endotype in Hispanics with NASH requiring LT, particularly in females.

CXCL10 deficiency limits macrophage infiltration, preserves lung matrix, and enables lung growth in bronchopulmonary dysplasia

Preterm infants with oxygen supplementation are at high risk for bronchopulmonary dysplasia (BPD), a neonatal chronic lung disease. Inflammation with macrophage activation is central to the pathogenesis of BPD. CXCL10, a chemotactic and pro-inflammatory chemokine, is elevated in the lungs of infants evolving BPD and in hyperoxia-based BPD in mice. Here, we tested if CXCL10 deficiency preserves lung growth after neonatal hyperoxia by preventing macrophage activation. To this end, we exposed Cxcl10 knockout (Cxcl10-/-) and wild-type mice to an experimental model of hyperoxia (85% O2)-induced neonatal lung injury and subsequent regeneration. In addition, cultured primary human macrophages and murine macrophages (J744A.1) were treated with CXCL10 and/or CXCR3 antagonist. Our transcriptomic analysis identified CXCL10 as a central hub in the inflammatory network of neonatal mouse lungs after hyperoxia. Quantitative histomorphometric analysis revealed that Cxcl10-/- mice are in part protected from reduced alveolar. These findings were related to the preserved spatial distribution of elastic fibers, reduced collagen deposition, and protection from macrophage recruitment/infiltration to the lungs in Cxcl10-/- mice during acute injury and regeneration. Complimentary, studies with cultured human and murine macrophages showed that hyperoxia induces Cxcl10 expression that in turn triggers M1-like activation and migration of macrophages through CXCR3. Finally, we demonstrated a temporal increase of macrophage-related CXCL10 in the lungs of infants with BPD. In conclusion, our data demonstrate macrophage-derived CXCL10 in experimental and clinical BPD that drives macrophage chemotaxis through CXCR3, causing pro-fibrotic lung remodeling and arrest of alveolarization. Thus, targeting the CXCL10-CXCR3 axis could offer a new therapeutic avenue for BPD.

FABP4 in LSECs promotes CXCL10-mediated macrophage recruitment and M1 polarization during NAFLD progression

BACKGROUND AND AIMS

Non-alcoholic liver disease (NAFLD) is emerging as the leading cause of end-stage liver disease with a serious threat to global health burden. Fatty acid-binding protein 4 (FABP4) is closely associated with metabolic syndromes. We aimed to explore the potential mechanisms of FABP4 in NAFLD progression.

MATERIALS AND METHODS

For NAFLD mice, animals were fed with high fat diet (HFD) for 20 weeks. The assays of hematoxylin and eosin, Sirius Red, oil red O staining and immunohistology were performed to evaluate hepatic pathology. Flow cytometric analysis was used to distinguish macrophage subtypes.

RESULTS

Serum FABP4 level was positively correlate with the severity of hepatic steatosis in NAFLD patients. FABP4 expression was mainly distributed in liver sinusoidal endothelial cells (LSECs), which was significantly increased in HFD mice. The level of CXCL10 was positively correlated with FABP4 at mRNA and serum level. FABP4 inhibition resulted in decreased expression of CXCL10. The percentage of M1 macrophage and CXCR3⁺ cells in infiltrated macrophage was increased in liver of HFD mice. Inhibition of FABP4 ameliorated HFD-induced M1 macrophage polarization as well as CXCR3⁺ macrophages recruitment. Recombinant CXCL10 and co-culturing with TMNK-1 stimulated macrophage toward M1 polarization, which could be reversed by CXCR3 inhibitor. Palmitic acid treatment resulted in increased nuclear P65 expression, which could be reversed by inhibiting FABP4. Cxcl10 expression was dramatically suppressed by NF-κB inhibitor.

CONCLUSIONS

FABP4 in LSECs may play a pathogenic role in NAFLD course by promoting CXCL10-mediated macrophage M1 polarization and CXCR3⁺ macrophage infiltration via activating NF-κB/p65 signaling.

Rho-associated protein kinase 1 inhibition in hepatocytes attenuates nonalcoholic steatohepatitis

BACKGROUND

NASH is the progressive form of NAFLD characterized by lipotoxicity, hepatocyte injury, tissue inflammation, and fibrosis. Previously, Rho-associated protein kinase (ROCK) 1 has been implicated in lipotoxic signaling in hepatocytes in vitro and high-fat diet-induced lipogenesis in vivo. However, whether ROCK1 plays a role in liver inflammation and fibrosis during NASH is unclear. Here, we hypothesized that pathogenic activation of ROCK1 promotes murine NASH pathogenesis.

METHODS AND RESULTS

Patients with NASH had increased hepatic ROCK1 expression compared with patients with fatty liver. Similarly, hepatic ROCK1 levels and activity were increased in mice with NASH induced by a western-like diet that is high in fat, fructose, and cholesterol (FFC). Hepatocyte-specific ROCK1 knockout mice on the FFC diet displayed a decrease in liver steatosis, hepatic cell death, liver inflammation, and fibrosis compared with littermate FFC-fed controls. Mechanistically, these effects were associated with a significant attenuation of myeloid cell recruitment. Interestingly, myeloid cell-specific ROCK1 deletion did not affect NASH development in FFC-fed mice. To explore the therapeutic opportunities, mice with established NASH received ROCKi, a novel small molecule kinase inhibitor of ROCK1/2, which preferentially accumulates in liver tissue. ROCK inhibitor treatment ameliorated insulin resistance and decreased liver injury, inflammation, and fibrosis.

CONCLUSIONS

Genetic or pharmacologic inhibition of ROCK1 activity attenuates murine NASH, suggesting that ROCK1 may be a therapeutic target for treating human NASH.

A new NASH model in aged mice with rapid progression of steatohepatitis and fibrosis

Non-alcoholic fatty liver disease (NAFLD) has a high prevalence worldwide, with a significant proportion of patients progressing into non-alcoholic steatohepatitis (NASH) and further into cirrhosis and hepatocellular carcinoma (HCC). Most of the current animal models of NASH have limitations, such as incompatibility with human pathogenesis characteristics or long induction periods, which severely limit the development of new drugs and preclinical studies for NASH. We investigated the progression of NASH and fibrosis, as well as metabolic indicators, at different time points in aged mice induced by the Gubra Amylin NASH (GAN) diet, a high-fat, high-sugar, high-cholesterol diet, and attempted to establish a rapid and useful mouse model of NASH. Young and aged C57BL/6 mice were induced on a normal chow or GAN diet for 12 and 21 weeks, respectively. After 12 weeks of induction, aged mice developed NASH, including hepatic steatosis, lobular inflammation and hepatic ballooning, and the phenotype was more severe compared with young mice. After 21 weeks of induction, aged mice developed hepatic fibrosis, which greatly shortened the induction time compared with young mice. Furthermore, analysis of immune cell infiltration in the liver by flow cytometry elucidated the changes of multiple immune cells during the pathogenesis of NASH. These findings suggest that aged mice may develop NASH and fibrosis more rapidly under GAN diet induction, which may significantly shorten the period for preclinical studies of NASH.

Activation of Kupffer cells in NAFLD and NASH: mechanisms and therapeutic interventions

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are emerging as the leading causes of liver disease worldwide. These conditions can lead to cirrhosis, liver cancer, liver failure, and other related ailments. At present, liver transplantation remains the sole treatment option for end-stage NASH, leading to a rapidly growing socioeconomic burden. Kupffer cells (KCs) are a dominant population of macrophages that reside in the liver, playing a crucial role in innate immunity. Their primary function includes phagocytosing exogenous substances, presenting antigens, and triggering immune responses. Moreover, they interact with other liver cells during the pathogenesis of NAFLD, and this crosstalk may either delay or exacerbate disease progression. Stimulation by endogenous signals triggers the activation of KCs, resulting in the expression of various inflammatory factors and chemokines, such as NLRP3, TNF-α, IL-1B, and IL-6, and contributing to the inflammatory cascade. In the past 5 years, significant advances have been made in understanding the biological properties and immune functions of KCs in NAFLD, including their interactions with tissue molecules, underlying molecular mechanisms, signaling pathways, and relevant therapeutic interventions. Having a comprehensive understanding of these mechanisms and characteristics can have enormous potential in guiding future strategies for the prevention and treatment of NAFLD.

The diverse roles of macrophages in metabolic inflammation and its resolution

Macrophages are one of the most functionally diverse immune cells, indispensable to maintain tissue integrity and metabolic health. Macrophages perform a myriad of functions ranging from promoting inflammation, through inflammation resolution to restoring and maintaining tissue homeostasis. Metabolic diseases encompass a growing list of diseases which develop from a mix of genetics and environmental cues leading to metabolic dysregulation and subsequent inflammation. In this review, we summarize the contributions of macrophages to four metabolic conditions-insulin resistance and adipose tissue inflammation, atherosclerosis, non-alcoholic fatty liver disease and neurodegeneration. The role of macrophages is complex, yet they hold great promise as potential therapies to address these growing health concerns.

The contradictory roles of macrophages in non-alcoholic fatty liver disease and primary liver cancer-Challenges and opportunities

Chronic liver diseases from varying etiologies generally lead to liver fibrosis and cirrhosis. Among them, non-alcoholic fatty liver disease (NAFLD) affects roughly one-quarter of the world population, thus representing a major and increasing public health burden. Chronic hepatocyte injury, inflammation (non-alcoholic steatohepatitis, NASH) and liver fibrosis are recognized soils for primary liver cancer, particularly hepatocellular carcinoma (HCC), being the third most common cause for cancer-related deaths worldwide. Despite recent advances in liver disease understanding, therapeutic options on pre-malignant and malignant stages remain limited. Thus, there is an urgent need to identify targetable liver disease-driving mechanisms for the development of novel therapeutics. Monocytes and macrophages comprise a central, yet versatile component of the inflammatory response, fueling chronic liver disease initiation and progression. Recent proteomic and transcriptomic studies performed at singular cell levels revealed a previously overlooked diversity of macrophage subpopulations and functions. Indeed, liver macrophages that encompass liver resident macrophages (also named Kupffer cells) and monocyte-derived macrophages, can acquire a variety of phenotypes depending on microenvironmental cues, and thus exert manifold and sometimes contradictory functions. Those functions range from modulating and exacerbating tissue inflammation to promoting and exaggerating tissue repair mechanisms (i.e., parenchymal regeneration, cancer cell proliferation, angiogenesis, fibrosis). Due to these central functions, liver macrophages represent an attractive target for the treatment of liver diseases. In this review, we discuss the multifaceted and contrary roles of macrophages in chronic liver diseases, with a particular focus on NAFLD/NASH and HCC. Moreover, we discuss potential therapeutic approaches targeting liver macrophages.

Programmed cell death and lipid metabolism of macrophages in NAFLD

Non-alcoholic fatty liver disease (NAFLD) has now become the leading chronic liver disease worldwide with lifestyle changes. This may lead to NAFLD becoming the leading cause of end-stage liver disease in the future. To date, there are still no effective therapeutic drugs for NAFLD. An in-depth exploration of the pathogenesis of NAFLD can help to provide a basis for new therapeutic agents or strategies. As the most important immune cells of the liver, macrophages play an important role in the occurrence and development of liver inflammation and are expected to become effective targets for NAFLD treatment. Programmed cell death (PCD) of macrophages plays a regulatory role in phenotypic transformation, and there is also a certain connection between different types of PCD. However, how PCD regulates macrophage polarization has still not been systematically elucidated. Based on the role of lipid metabolic reprogramming in macrophage polarization, PCD may alter the phenotype by regulating lipid metabolism. We reviewed the effects of macrophages on inflammation in NAFLD and changes in their lipid metabolism, as well as the relationship between different types of PCD and lipid metabolism in macrophages. Furthermore, interactions between different types of PCD and potential therapeutic agents targeting of macrophages PCD are also explored.

Knee osteoarthritis phenotypes based on synovial fluid immune cells correlate with clinical outcome trajectories

BACKGROUND

Knee osteoarthritis (KOA) is a highly heterogeneous disease encompassing a wide range of clinical phenotypes. Phenotypes based on immune cells and protein pattern in synovial fluid (SF) and their relationship to clinical trajectories have not been described.

OBJECTIVE

To assess phenotypes based on immune cells and protein pattern of SF in KOA.

DESIGN

SF-derived immune cells were investigated in 119 patients with KOA using flow cytometry. Immune-phenotypes (iPhen) were determined by multivariate patient similarity network analysis and related to clinical trajectory (3-6 months post-sampling) along with protein pattern and macrophage chemokine receptors.

RESULTS

Four iPhen were detected based on the distribution of T-lymphocytes, monocyte-macrophage lineage cells and activated CD8+ T-lymphocytes. The 'activated' phenotype (n = 17) had high T-lymphocytes but low monocyte-macrophage lineage cells and neutrophils, all highly activated, and showed improved symptoms in 70% patients. The 'lymphoid progressive' phenotype (n = 31) had high neutrophils, low lymphocytes and monocyte-macrophage lineage cells, low activation and was associated with lower pain levels. The 'myeloid progressive' phenotype (n = 35) had high NK and monocyte-macrophage lineage cells but low T-lymphocytes and activation. The 'aggressive' phenotype (n = 36) had high lymphocytes, macrophages, NK cells and neutrophils and high activation, and only 39% of patients improved during follow-up. Low CXCR4 and CCR7 expression on macrophages and high CXCL10 in SF were linked to improved clinical trajectory.

CONCLUSION

We identified four immune-phenotypes that were associated with different clinical trajectories in KOA patients. How these phenotypes can be targeted therapeutically deserves further investigation.

Tryptamine, a Microbial Metabolite in Fermented Rice Bran Suppressed Lipopolysaccharide-Induced Inflammation in a Murine Macrophage Model

Fermentation is thought to alter the composition and bioavailability of bioactive compounds in rice bran. However, how this process affects the anti-inflammatory effects of rice bran and the bioactive compounds that might participate in this function is yet to be elucidated. This study aimed to isolate bioactive compounds in fermented rice bran that play a key role in its anti-inflammatory function. The fermented rice bran was fractionated using a succession of solvent and solid-phase extractions. The fermented rice bran fractions were then applied to lipopolysaccharide (LPS)-activated murine macrophages to evaluate their anti-inflammatory activity. The hot water fractions (FRBA), 50% ethanol fractions (FRBB), and n-hexane fractions (FRBC) were all shown to be able to suppress the pro-inflammatory cytokine expression from LPS-stimulated RAW 264.7 cells. Subsequent fractions from the hot water fraction (FRBF and FRBE) were also able to reduce the inflammatory response of these cells to LPS. Further investigation revealed that tryptamine, a bacterial metabolite of tryptophan, was abundantly present in these extracts. These results indicate that tryptamine may play an important role in the anti-inflammatory effects of fermented rice bran. Furthermore, the anti-inflammatory effects of FRBE and tryptamine may depend on the activity of the aryl hydrocarbon receptor.

Expression of HLA and Autoimmune Pathway Genes in Liver Biopsies of Young Subjects With Autoimmune Hepatitis Type 1

OBJECTIVES

To test the hypothesis that autoimmune hepatitis (AIH type I) in young subjects is due to genetic differences in proinflammatory genes responding to viral triggers in patients and controls.

METHODS

Intrahepatic gene expression was compared between AIH type I (n = 24, age 9-30 years) patients (hereafter referred to as the AIH group) and controls (n = 21, age 4-25 years). RNA sequencing was performed on complementary DNA (cDNA) libraries made from total RNA extracted from formalin-fixed paraffin-embedded (FFPE) liver biopsy samples. Gene expression levels were quantified, and differentially expressed genes were functionally analyzed. Pathway analysis was performed using the databases Kyoto Encyclopedia of Genes and Genomes (KEGG) and PANTHER. The remaining sequences were mapped to the RefSeq complete set of viral genomes.

RESULTS

Differential gene analysis identified 181 genes that were significantly differentially expressed (136 upregulated in the AIH group). Autoimmune pathway genes such as CD19 and CD20 which are important in B cell regulation and maturation as well as, CD8 and LY9 , which are T-cell related, were upregulated in our AIH group. Genes implicated in AIH pathogenesis including CXCL10 , which is thought to be associated with AIH severity and progression, complement genes ( C1QA, C1QB , and C1QC ), and human leucocyte antigen ( HLA ) genes ( HLA-DRB1, HLA-DRA, HLA-B , and HLA-C ) were upregulated in samples from the AIH group. Specific viral etiologies were not found.

CONCLUSIONS

Unbiased next-generation sequencing and differential gene expression analysis of the AIH group has not only added support for the role of B cells in the pathogenesis and treatment of AIH but also has introduced potential new therapeutic targets: CXCL10 (anti- CXCL10 ) and several complement system-related genes.

T-bet+ B cells accumulate in adipose tissue and exacerbate metabolic disorder during obesity

Obesity is accompanied by inflammation in adipose tissue, impaired glucose tolerance, and changes in adipose leukocyte populations. These studies of adipose tissue from humans and mice revealed that increased frequencies of T-bet⁺ B cells in adipose tissue depend on invariant NKT cells and correlate with weight gain during obesity. Transfer of B cells enriched for T-bet⁺ cells exacerbates metabolic disorder in obesity, while ablation of Tbx21 specifically in B cells reduces serum IgG2c levels, inflammatory cytokines, and inflammatory macrophages in adipose tissue, ameliorating metabolic symptoms. Furthermore, transfer of serum or purified IgG from HFD mice restores metabolic disease in T-bet⁺ B cell-deficient mice, confirming T-bet⁺ B cell-derived IgG as a key mediator of inflammation during obesity. Together, these findings reveal an important pathological role for T-bet⁺ B cells that should inform future immunotherapy design in type 2 diabetes and other inflammatory conditions.

Plasticity of monocytes and macrophages in cirrhosis of the liver

Cirrhosis of the liver is a systemic condition with raising prevalence worldwide. Patients with cirrhosis are highly susceptible to develop bacterial infections leading to acute decompensation and acute-on-chronic liver failure both associated with a high morbidity and mortality and sparse therapeutic options other than transplantation. Mononuclear phagocytes play a central role in innate immune responses and represent a first line of defence against pathogens. Their function includes phagocytosis, killing of bacteria, antigen presentation, cytokine production as well as recruitment and activation of immune effector cells. Liver injury and development of cirrhosis induces activation of liver resident Kupffer cells and recruitment of monocytes to the liver. Damage- and pathogen-associated molecular patterns promote systemic inflammation which involves multiple compartments besides the liver, such as the circulation, gut, peritoneal cavity and others. The function of circulating monocytes and tissue macrophages is severely impaired and worsens along with cirrhosis progression. The underlying mechanisms are complex and incompletely understood. Recent 'omics' technologies help to transform our understanding of cellular diversity and function in health and disease. In this review we point out the current state of knowledge on phenotypical and functional changes of monocytes and macrophages during cirrhosis evolution in different compartments and their role in disease progression. We also discuss the value of potential prognostic markers for cirrhosis-associated immuneparesis, and future immunotherapeutic strategies that may reduce the need for transplantation and death.

Induced CAR-Macrophages as a Novel Therapeutic Cell Type for Cancer Immune Cell Therapies

The Chimeric antigen receptor (CAR)-T cell therapy has made inroads in treating hematological malignancies. Nonetheless, there are still multiple hurdles in CAR-T cell therapy for solid tumors. Primary CAR-expressing macrophage cells (CAR-Ms) and induced pluripotent stem cells (iPSCs)-derived CAR-expressing macrophage cells (CAR-iMacs) have emerged as attractive alternatives in our quest for an efficient and inexpensive approach for tumor immune cell therapy. In this review, we list the current state of development of human CAR-macrophages and provide an overview of the crucial functions of human CAR-macrophages in the field of tumor immune cell therapy.

MyD88 in hepatic stellate cells enhances liver fibrosis via promoting macrophage M1 polarization

During liver fibrosis, quiescent HSCs (qHSCs) are activated to become activated HSCs (aHSCs)/myofibroblasts. The signal adapter MyD88, an essential component of TLR signaling, plays an important role in liver fibrosis. However, far less is known about the specific effects of MyD88 signaling in both qHSCs and aHSCs in the progress of liver fibrosis. Here, we used a CCl₄-induced mouse fibrosis model in which MyD88 was selectively depleted in qHSCs (GFAP^MyD88−/− mice) or aHSCs (α-SMA^MyD88−/− mice). MyD88 deficiency in qHSCs or aHSCs attenuated liver fibrosis in mice and inhibited α-SMA-positive cell activation. Inhibition of MyD88 in HSCs decreased α-SMA and collagen I levels, inflammatory cell infiltration, and pro-inflammatory gene expression. Furthermore, MyD88 signaling in HSCs increased the secretion of CXCL10, which promoted macrophage M1 polarization through CXCR3, leading to activation of the JAK/STAT1 pathway. Inhibition of CXCL10 attenuated macrophage M1 polarization and reduced liver fibrosis. Thus, MyD88 signaling in HSCs crucially contributes to liver fibrosis and provides a promising therapeutic target for the prevention and treatment of liver fibrosis.

Immune-related pathogenesis and therapeutic strategies of nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome and has become prevalent in the adult population worldwide, given the ongoing obesity pandemic. NAFLD comprises several hepatic disorders, ranging from fatty liver to nonalcoholic steatohepatitis (NASH), cirrhosis, and carcinoma. Excessive fat accumulation in the liver can induce the development of fatty liver, whereas the progression of fatty liver to NASH involves various complex factors. The crucial difference between fatty liver and NASH is the presence of inflammation and fibrosis, the emergence of which is closely associated with the action of immune cells and immunological factors, such as chemokines and cytokines. Thus, expanding our understanding of immunological mechanisms contributing to NASH pathogenesis will lead to the identification of therapeutic targets and the development of viable therapeutics against NASH.

Cxcl10 deficiency attenuates renal interstitial fibrosis through regulating epithelial-to-mesenchymal transition

IFN-γ-inducible protein 10 (IP-10, CXCL10) has been widely demonstrated to be involved in multiple kidney pathological processes. However, the role of CXCL10 in renal fibrosis remains unclear. In this study, Cxcl10-deficient (Cxcl10-/-) mice were used to generate the unilateral ureteral obstruction (UUO) model. The level of renal fibrosis and inflammatory cell infiltration was examined in vivo and the effects of CXCL10 on EMT process of HK-2 cells was investigated in vitro. We observed that the injury degree of renal tissue and the collagen deposition levels were lighter and the expression of α-SMA, collagen I and fibronectin was significantly reduced in Cxcl10-/- mice, while the expression of E-cadherin was increased. However, interstitial F4/80-positive macrophages and CD4-positive T lymphocytes were unaffected by knockout of Cxcl10. Furthermore, IFN-γ or CXCL10 stimulation could obviously promote the expression of α-SMA, collagen I, fibronectin and reduce the expression of E-cadherin in HK-2 cells, which could be inhibited by transfection of Cxcl10-siRNA. Our findings suggested Cxcl10 knockout could reduce renal dysfunction and inhibit renal fibrosis through regulating EMT process of renal tubular epithelial cells in murine UUO model. These results may provide a novel insight into the mechanism and a potential therapy target of renal fibrosis.

Lipopolysaccharide-Induced Transcriptional Changes in LBP-Deficient Rat and Its Possible Implications for Liver Dysregulation during Sepsis

Sepsis is an organ dysfunction caused by the dysregulated inflammatory response to infection. Lipopolysaccharide-binding protein (LBP) binds to lipopolysaccharide (LPS) and modulates the inflammatory response. A rare systematic study has been reported to detect the effect of LBP gene during LPS-induced sepsis. Herein, we explored the RNA sequencing technology to profile the transcriptomic changes in liver tissue between LBP-deficient rats and WT rats at multiple time points after LPS administration. We proceeded RNA sequencing of liver tissue to search differentially expressed genes (DEGs) and enriched biological processes and pathways between WT and LBP-deficient groups at 0 h, 6 h, and 24 h. In total, 168, 284, and 307 DEGs were identified at 0 h, 6 h, and 24 h, respectively, including Lrp5, Cyp7a1, Nfkbiz, Sigmar1, Fabp7, and Hao1, which are related to the inflammatory or lipid-related process. Functional enrichment analysis revealed that inflammatory response to LPS mediated by Ifng, Cxcl10, Serpine1, and Lbp was enhanced at 6 h, while lipid-related metabolism associated with C5, Cyp4a1, and Eci1 was enriched at 24 h after LPS administration in the WT samples. The inflammatory process was not found when the LBP gene was knocked out; lipid-related metabolic process and peroxisome proliferator-activated receptor (PPAR) signaling pathway mediated by Dhrs7b and Tysnd1 were significantly activated in LBP-deficient samples. Our study suggested that the invading LPS may interplay with LBP to activate the nuclear factor kappa B (NF-κB) signaling pathway and trigger uncontrolled inflammatory response. However, when inhibiting the activity of NF-κB, lipid-related metabolism would make bacteria removal via the effect on the PPAR signaling pathway in the absence of LBP gene. We also compared the serum lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) levels using the biochemistry analyzer and analyzed the expression of high mobility group box 1 (HMGB1) and cleaved-caspase 3 with immunohistochemistry, which further validated our conclusion.

Macrophage activation marker sCD163 is associated with liver injury and hepatic insulin resistance in obese patients before and after Roux-en-Y gastric bypass

BACKGROUND

Macrophages are associated with metabolic complications to obesity including fatty liver disease and impaired hepatic and muscle insulin sensitivity (IS). Bariatric surgery induces weight loss and improves IS. We investigated associations between the macrophage activation marker soluble (s)CD163, alanine-aminotransferase (ALT), and IS before and after Roux-en-Y Gastric Bypass (RYGB).

METHODS

We analyzed sCD163 from 10 type 2 diabetes (T2D) and 10 obese patients with normal glucose tolerance (NGT) undergoing RYGB for associations with hepatic, adipose tissue, and muscle IS and ALT after 1-week, 3, and 12 months postoperatively. IS was evaluated by hyperinsulinemic-euglycemic clamp in combination with glucose tracer technique.

RESULTS

Preoperative sCD163 correlated with ALT (r = 0.58, p = 0.007) and tended to associate inversely with hepatic (r = -0.39, p = 0.1) and adipose tissue (r = -0.39, p = 0.09), but not muscle IS. Following RYGB, sCD163 decreased significantly in all patients. The decrease in sCD163 during the first 3 months correlated inversely with the improvement of hepatic IS (r = -0.65, p = 0.01) and tended to be associated with changes in muscle IS (r = -0.45, p = 0.09). After 3 months sCD163 remained associated with ALT (r = 0.75, p < 0.001) and inversely with hepatic IS (r = -0.39, p = 0.1), but not muscle or adipose tissue IS. One year after RYGB, sCD163 correlated with ALT (r = 0.61, p = 0.007), but not with hepatic, adipose tissue, or muscle IS.

CONCLUSION

Macrophage activation is associated with liver injury and hepatic IS in obese patients. Improvements in these measures correlate during the first 3 months following RYGB, supporting a link between macrophages and hepatic IS in severe obesity and diabetes.

Cell Models and Omics Techniques for the Study of Nonalcoholic Fatty Liver Disease: Focusing on Stem Cell-Derived Cell Models

Nonalcoholic fatty liver disease (NAFLD) is now the leading cause of chronic liver disease in western countries. The molecular mechanisms leading to NAFLD are only partially understood, and effective therapeutic interventions are clearly needed. Therefore, preclinical research is required to improve knowledge about NAFLD physiopathology and to identify new therapeutic targets. Primary human hepatocytes, human hepatic cell lines, and human stem cell-derived hepatocyte-like cells exhibit different hepatic phenotypes and have been widely used for studying NAFLD pathogenesis. In this paper, apart from employing the different in vitro cell models for the in vitro assessment of NAFLD, we also reviewed other approaches (metabolomics, transcriptomics, and high-content screening). We aimed to summarize the characteristics of different cell types and methods and to discuss their major advantages and disadvantages for NAFLD modeling.

Identification of a 17-gene-signature in Non-alcoholic Steatohepatitis and Its Relationship with Immune Cell Infiltration

Background: Non-alcoholic steatohepatitis (NASH) is a risk factor for hepatocellular carcinoma, but the understanding of the regulatory mechanisms driving NASH is not comprehensive. Objectives: We aimed to identify the potential markers of NASH and explore their relationship with immune cell populations. Methods: Five gene expression datasets for NASH were downloaded from the Gene Expression Omnibus and European Bioinformatics Institute Array Express databases. Differentially expressed genes (DEGs) between NASH and controls were screened. Gene Ontology-Biological Process (GO-BP) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed for functional enrichment analysis of DEGs. Among the candidate genes selected from the protein-protein interaction (PPI) network and module analysis, DEG signatures were further identified using least absolute shrinkage and selection operator regression analysis. The Spearman correlation coefficient was calculated to assess the correlation between DEG signatures and immune cell abundance based on the CIBERSORT algorithm. Results: We screened 403 upregulated, and 158 downregulated DEGs for NASH, and they were mainly enriched in GO-BP, including the inflammatory response, innate immune response, signal transduction, and KEGG pathways, such as the pathways involved in cancer (e.g., the PI3K-Akt signaling pathway), and focal adhesion. We then screened 73 candidate genes from the PPI network and module analysis and finally identified 17 DEG signatures. By evaluating their relationship with immune cell populations, 12 DEG signatures were found to correlate with activated dendritic cells, resting dendritic cells, M2 macrophages, monocytes, neutrophils, and resting memory CD4 T cells, which were significantly different between the NASH and control tissues. Conclusions: We identified a 17-DEG-signature as a candidate biomarker for NASH and analyzed its relationship with immune infiltration in NASH.

Extracellular vesicles: mediators of intercellular communication in tissue injury and disease

Intercellular communication is a critical process that ensures cooperation between distinct cell types and maintains homeostasis. EVs, which were initially described as cellular debris and devoid of biological function, are now recognized as key components in cell-cell communication. EVs are known to carry multiple factors derived from their cell of origin, including cytokines and chemokines, active enzymes, metabolites, nucleic acids, and surface molecules, that can alter the behavior of recipient cells. Since the cargo of EVs reflects their parental cells, EVs from damaged and dysfunctional tissue environments offer an abundance of information toward elucidating the molecular mechanisms of various diseases and pathological conditions. In this review, we discuss the most recent findings regarding the role of EVs in the progression of cancer, metabolic disorders, and inflammatory lung diseases given the high prevalence of these conditions worldwide and the important role that intercellular communication between immune, parenchymal, and stromal cells plays in the development of these pathological states. We also consider the clinical applications of EVs, including the possibilities for their use as novel therapeutics. While intercellular communication through extracellular vesicles (EVs) is key for physiological processes and tissue homeostasis, injury and stress result in altered communication patterns in the tissue microenvironment. When left unchecked, EV-mediated interactions between stromal, immune, and parenchymal cells lead to the development of disease states Video Abstract.

Comprehensive Analysis of NAFLD and the Therapeutic Target Identified

Objective: Non-alcoholic fatty liver disease (NAFLD) is a serious health threat worldwide. The aim of this study was to comprehensively describe the metabolic and immunologic characteristics of NAFLD, and to explore potential therapeutic drug targets for NAFLD. Methods: Six NAFLD datasets were downloaded from the Gene Expression Omnibus (GEO) database, including GSE48452, GSE63067, GSE66676, GSE89632, GSE24807, and GSE37031. The datasets we then used to identify and analyze genes that were differentially expressed in samples from patients with NAFLD and normal subjects, followed by analysis of the metabolic and immunologic characteristics of patients with NAFLD. We also identified potential therapeutic drugs for NAFLD using the Connectivity Map (CMAP) database. Moreover, we constructed a prediction model using minimum depth random forest analysis and screened for potential therapeutic targets. Finally, therapeutic targets were verified in a fatty liver model stimulated by palmitic acid (PA). Results: A total of 1,358 differentially expressed genes (DEGs) were obtained, which were mainly enriched in carbohydrate metabolism, lipid metabolism, and other metabolic pathways. Immune infiltration analysis showed that memory B cells, regulatory T cells and M1 macrophage were significantly up-regulated, while T cells follicular helper were down regulated in NAFLD. These may provide a reference for the immune-metabolism interaction in the pathogenesis of NAFLD. Digoxin and helveticoside were identified as potential therapeutic drugs for NAFLD via the CMAP database. In addition, a five-gene prediction model based on minimum depth random forest analysis was constructed, and the receiver operating characteristic (ROC) curves of both training and validation set reached 1. The five candidate therapeutic targets were ENO3, CXCL10, INHBE, LRRC31, and OPTN. Moreover, the efficiency of hepatocyte adipogenesis decreased after OPTN knockout, confirming the potential use of OPTN as a new therapeutic target for NAFLD. Conclusion: This study provides a deeper insight into the molecular pathogenesis of NAFLD. We used five key genes to construct a diagnostic model with a strong predictive effect. Therefore, these five key genes may play an important role in the diagnosis and treatment of NAFLD, particularly those with increased OPTN expression.

Integrated analysis of mRNA and long non-coding RNA expression profiles reveals the potential roles of lncRNA-mRNA network in carp macrophage immune regulation

Long non-coding RNAs (lncRNAs) have emerged as a hot topic in research as mounting evidence has indicated their transcriptional or post-transcriptional regulatory potential in multiple biological processes. Previous studies have revealed the involvement of lncRNAs in the immunoregulation of mammalian macrophages by changing mRNA expression; however, studies on the lncRNAs in fish macrophages and their potential roles in the immune system remain unknown. Primary macrophages were isolated from the head kidney (HK) of red common carp (Cyprinus carpio) and high-throughput lncRNA-mRNA sequencing was performed using the Illumina HiSeq platform. The results revealed that the most highly expressed mRNAs in primary HK macrophages were mainly involved in immune-related signal pathways. Furthermore, the most enriched immune-related GO term and KEGG pathway of the mRNAs were "immune system development" and "chemokine signaling pathway," respectively. A total of 20,333 lncRNAs, composed of 10,512 known and 9821 novel lncRNAs, were identified, and functional enrichment analysis of the lncRNA-mRNA network indicated that the expressed lncRNAs in primary HK macrophages could be associated with the regulation of multiple immune-related signaling pathways. In addition, the expressions of several selected lncRNAs and their related mRNAs were determined in carp macrophages following a 6-h exposure to lipopolysaccharide (LPS) and Poly(I: C), the results of which confirmed the co-expression regulation of lncRNAs and target mRNAs in the immune response of carp macrophages. These results suggest the correlative of the lncRNA-mRNA network in fish macrophage immune response, which may further affect the cross-talk of various signaling pathways by interaction with other network genes. Here, we provided fundamental data about the transcriptome profiles of primary HK macrophages from red common carp by analysis of the lncRNA-mRNA network, and ultimately suggest the potential roles of lncRNA-mRNA networks in immune regulation in teleost fish.

Exosomes as mediators of intercellular crosstalk in metabolism

Exosomes are nanoparticles secreted by all cell types and are a large component of the broader class of nanoparticles termed extracellular vesicles (EVs). Once secreted, exosomes gain access to the interstitial space and ultimately the circulation, where they exert local paracrine or distal systemic effects. Because of this, exosomes are important components of an intercellular and intraorgan communication system capable of carrying biologic signals from one cell type or tissue to another. The exosomal cargo consists of proteins, lipids, miRNAs, and other RNA species, and many of the biologic effects of exosomes have been attributed to miRNAs. Exosomal miRNAs have also been used as disease biomarkers. The field of exosome biology and metabolism is rapidly expanding, with new discoveries and reports appearing on a regular basis, and it is possible that potential therapeutic approaches for the use of exosomes or miRNAs in metabolic diseases will be initiated in the near future.

Regulation and functional roles of chemokines in liver diseases

Inflammation is a major contributor to the pathogenesis of almost all liver diseases. Low-molecular-weight proteins called chemokines are the main drivers of liver infiltration by immune cells such as macrophages, neutrophils and others during an inflammatory response. During the past 25 years, tremendous progress has been made in understanding the regulation and functions of chemokines in the liver. This Review summarizes three main aspects of the latest advances in the study of chemokine function in liver diseases. First, we provide an overview of chemokine biology, with a particular focus on the genetic and epigenetic regulation of chemokine transcription as well as on the cell type-specific production of chemokines by liver cells and liver-associated immune cells. Second, we highlight the functional roles of chemokines in liver homeostasis and their involvement in progression to disease in both human and animal models. Third, we discuss the therapeutic opportunities targeting chemokine production and signalling in the treatment of liver diseases, such as alcohol-associated liver disease and nonalcoholic steatohepatitis, including the relevant preclinical studies and ongoing clinical trials.

Dynamic co-expression modular network analysis in nonalcoholic fatty liver disease

Background

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease affecting people’s health worldwide. Exploring the potential biomarkers and dynamic networks during NAFLD progression is urgently important.

Material and methods

Differentially expressed genes (DEGs) in obesity, NAFL and NASH were screened from GSE126848 and GSE130970, respectively. Gene set enrichment analysis of DEGs was conducted to reveal the Gene Ontology (GO) biological process in each period. Dynamic molecular networks were constructed by DyNet to illustrate the common and distinct progression of health- or obesity-derived NAFLD. The dynamic co-expression modular analysis was carried out by CEMiTool to elucidate the key modulators, networks, and enriched pathways during NAFLD.

Results

A total of 453 DEGs were filtered from obesity, NAFL and NASH periods. Function annotation showed that health-NAFLD sequence was mainly associated with dysfunction of metabolic syndrome pathways, while obesity-NAFLD sequence exhibited dysregulation of Cell cycle and Cellular senescence pathways. Nine nodes including COL3A1, CXCL9, CYCS, CXCL10, THY1, COL1A2, SAA1, CDKN1A, and JUN in the dynamic networks were commonly identified in health- and obesity-derived NAFLD. Moreover, CYCS, whose role is unknown in NAFLD, possessed the highest correlation with NAFLD activity score, lobular inflammation grade, and the cytological ballooning grade. Dynamic co-expression modular analysis showed that module 4 was activated in NAFL and NASH, while module 3 was inhibited at NAFLD stages. Module 3 was negatively correlated with CXCL10, and module 4 was positively correlated with COL1A2 and THY1.

Conclusion

Dynamic network analysis and dynamic gene co-expression modular analysis identified a nine-gene signature as the potential key regulator in NAFLD progression, which provided comprehensive regulatory mechanisms underlying NAFLD progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41065-021-00196-8.

Donor-derived M2 macrophages attenuate GVHD after allogeneic hematopoietic stem cell transplantation

Introduction

Graft‐versus‐host disease (GVHD) is frequent and fatal complication following allogeneic hematopoietic stem cell transplantation (HSCT) and characteristically involves skin, gut, and liver. Macrophages promote tissue regeneration and mediate immunomodulation. Macrophages are divided into two different phenotypes, classically activated M1 (pro‐inflammatory or immune‐reactive macrophages) and alternatively activated M2 (anti‐inflammatory or immune‐suppressive macrophages). The anti‐inflammatory effect of M2 macrophage led us to test its effect in the pathophysiology of GVHD.

Methods

GVHD was induced in lethally irradiated BALB/c mice. M2 macrophages derived from donor bone marrow (BM) were administered intravenously, while controls received donor BM‐mononuclear cells and splenocytes. Animals were monitored for clinical GVHD and analyzed.

Results

We confirmed that administering donor BM‐derived M2 macrophages attenuated GVHD severity and prolonged survival after HSCT. Moreover, donor BM‐derived M2 macrophages significantly suppressed donor T cell proliferation by cell‐to‐cell contact in vitro.

Conclusions

We showed the protective effects of donor‐derived M2 macrophages on GVHD and improved survival in a model of HSCT. Our data suggest that donor‐derived M2 macrophages offer the potential for cell‐based therapy to treat GVHD.

CXCL10/CXCR3 signaling contributes to an inflammatory microenvironment and its blockade enhances progression of murine pancreatic precancerous lesions

The development of pancreatic cancer requires recruitment and activation of different macrophage populations. However, little is known about how macrophages are attracted to the pancreas after injury or an oncogenic event, and how they crosstalk with lesion cells or other cells of the lesion microenvironment. Here, we delineate the importance of CXCL10/CXCR3 signaling during the early phase of murine pancreatic cancer. We show that CXCL10 is produced by pancreatic precancerous lesion cells in response to IFNγ signaling and that inflammatory macrophages are recipients for this chemokine. CXCL10/CXCR3 signaling in macrophages mediates their chemoattraction to the pancreas, enhances their proliferation, and maintains their inflammatory identity. Blocking of CXCL10/CXCR3 signaling in vivo shifts macrophage populations to a tumor-promoting (Ym1⁺, Fizz⁺, Arg1⁺) phenotype, increases fibrosis, and mediates progression of lesions, highlighting the importance of this pathway in PDA development. This is reversed when CXCL10 is overexpressed in PanIN cells.

Identification of transcriptomic signatures and crucial pathways involved in non-alcoholic steatohepatitis

PURPOSE

Our study aimed to uncover the crucial genes and functional pathways involved in the development of non-alcoholic steatohepatitis (NASH).

METHODS

Liver transcriptome datasets were integrated with Robust rank aggregation (RRA) method, and transcriptomic signatures for NASH progression and fibrosis severity in NAFLD were developed. The functions of transcriptomic signatures were explored by multiple bioinformatic analyses, and their diagnostic role was also evaluated.

RESULTS

RRA analyses of 12 transcriptome datasets comparing NASH with non-alcoholic fatty liver (NAFL) identified 116 abnormally up-regulated genes in NASH patients. RRA analyses of five transcriptome datasets focusing fibrosis severity identified 78 abnormally up-regulated genes in NAFLD patients with advanced fibrosis. The functions of those transcriptomic signatures of NASH development or fibrosis progression were similar, and were both characterized by extracellular matrix (ECM)-related pathways (Adjusted P < 0.05). The transcriptomic signatures could effectively differentiate NASH from NAFL, and could help to identify NAFLD patients with advanced fibrosis. Gene set enrichment analysis and weighted gene co-expression network analysis further validated the key role of ECM-related pathways in NASH development. The top 10 up-regulated genes in NASH patients were SPP1, FBLN5, CHI3L1, CCL20, CD24, FABP4, GPNMB, VCAN, EFEMP1, and CXCL10, and their functions were mainly related to either ECM-related pathways or immunity-related pathways. Single cell RNA-sequencing analyses revealed that those crucial genes were expressed by distinct cells such as hepatocytes, macrophages, and hepatic stellate cells.

CONCLUSIONS

Transcriptomic signatures related to NASH development and fibrosis severity of NAFLD patients are both characterized by ECM-related pathways, and fibrosis is a main player during NASH progression. This study uncovers some novel key genes involved in NASH progression, which may be promising therapeutic targets.

Sinusoidal endotheliopathy in nonalcoholic steatohepatitis: therapeutic implications

Liver sinusoidal endothelial cells (LSECs) are distinct subtypes of endothelial cells lining a low flow vascular bed at the interface of the liver parenchyma and the circulating immune cells and soluble factors. Emerging literature implicates LSEC in the pathogenesis and progression of nonalcoholic fatty liver disease (NAFLD). During the evolution of NAFLD, LSEC dysfunction ensues. LSECs undergo morphological and functional transformation known as "capillarization," as well as a pathogenic increase in surface adhesion molecules expression, referred to in this review as "endotheliopathy." LSECs govern the composition of hepatic immune cell populations in nonalcoholic steatohepatis (NASH) by mediating leukocyte subset adhesion through specific combinations of activated adhesion molecules and secreted chemokines. Moreover, extracellular vesicles released by hepatocyte under lipotoxic stress in NASH act as a catalyst for the inflammatory response and promote immune cell chemotaxis and adhesion. In the current review, we highlight leukocyte adhesion to LSEC as an initiating event in the sterile inflammatory response in NASH. We discuss preclinical studies targeting immune cells adhesion in NASH mouse models and potential therapeutic anti-inflammatory strategies for human NASH.

PKM2-dependent metabolic skewing of hepatic Th17 cells regulates pathogenesis of non-alcoholic fatty liver disease

Emerging evidence suggests a key contribution to non-alcoholic fatty liver disease (NAFLD) pathogenesis by Th17 cells. The pathogenic characteristics and mechanisms of hepatic Th17 cells, however, remain unknown. Here, we uncover and characterize a distinct population of inflammatory hepatic CXCR3+Th17 (ihTh17) cells sufficient to exacerbate NAFLD pathogenesis. Hepatic ihTh17 cell accrual was dependent on the liver microenvironment and CXCR3 axis activation. Mechanistically, the pathogenic potential of ihTh17 cells correlated with increased chromatin accessibility, glycolytic output, and concomitant production of IL-17A, IFNγ, and TNFα. Modulation of glycolysis using 2-DG or cell-specific PKM2 deletion was sufficient to reverse ihTh17-centric inflammatory vigor and NAFLD severity. Importantly, ihTh17 cell characteristics, CXCR3 axis activation, and hepatic expression of glycolytic genes were conserved in human NAFLD. Together, our data show that the steatotic liver microenvironment regulates Th17 cell accrual, metabolism, and competence toward an ihTh17 fate. Modulation of these pathways holds potential for development of novel therapeutic strategies for NAFLD.

Mechanisms and disease consequences of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the leading chronic liver disease worldwide. Its more advanced subtype, nonalcoholic steatohepatitis (NASH), connotes progressive liver injury that can lead to cirrhosis and hepatocellular carcinoma. Here we provide an in-depth discussion of the underlying pathogenetic mechanisms that lead to progressive liver injury, including the metabolic origins of NAFLD, the effect of NAFLD on hepatic glucose and lipid metabolism, bile acid toxicity, macrophage dysfunction, and hepatic stellate cell activation, and consider the role of genetic, epigenetic, and environmental factors that promote fibrosis progression and risk of hepatocellular carcinoma in NASH.