Impaired CCR9/CCL25 signalling induced by inefficient dendritic cells contributes to intestinal immune imbalance in nonalcoholic steatohepatitis

State of CD8+ T cells in progression from nonalcoholic steatohepatitis to hepatocellular carcinoma: From pathogenesis to immunotherapy

With the obesity epidemic, nonalcoholic steatohepatitis (NASH) is emerging as the fastest growing potential cause of hepatocellular carcinoma (HCC). NASH has been demonstrated to establish a tumor-prone liver microenvironment where both innate and adaptive immune systems are involved. As the most typical anti-tumor effector, the cell function of CD8+ T cells is remodeled by chronic inflammation, metabolic alteration, lipid toxicity and oxidative stress in the liver microenvironment along the NASH to HCC transition. Unexpectedly, NASH may blunt the effect of immune checkpoint inhibitor therapy against HCC due to the dysregulated CD8+ T cells. Growing evidence has supported that NASH is likely to facilitate the state transition of CD8+ T cells with changes in cell motility, effector function, metabolic reprogramming and gene transcription according to single-cell sequencing. However, the mechanistic insight of CD8+ T cell states in the NASH-driven HCC is not comprehensive. Herein, we focus on the characterization of state phenotypes of CD8+ T cells with both functional and metabolic signatures in NASH-driven fibrosis and HCC. The NASH-specific CD8+ T cells are speculated to mainly have a dualist effect, where its aberrant activated phenotype sustains chronic inflammation in NASH but subsequently triggers its exhaustion in HCC. As the exploration of CD8+ T cells on the distribution and phenotypic shifts will provide a new direction for the intervention strategies against HCC, we also discuss the implications for targeting different phenotypes of CD8+ T cells, shedding light on the personalized immunotherapy for NASH-driven HCC.

Effects of microplastics and tetracycline on intestinal injury in mice

Microplastics (MPs) and tetracycline are both emerging environmental pollutants that threaten human health. The toxic impacts of their single and coexposure on the intestine and gut microbiota have not been well studied in mammals. Given the spatial functional characteristics of the intestine, it is important to know whether the toxicities of MPs and tetracycline in different intestinal segments are distinct. This study investigated the pathological and functional injuries of different intestinal segments and the microbial disorder upon exposure to polystyrene microplastics (PS-MPs) and/or tetracycline hydrochloride (TCH). Both PS-MPs and TCH altered the intestinal morphology and induced functional impairment. However, the PS-MPs primarily damaged the colon, while TCH mainly damaged the small intestine, especially the jejunum. Combined treatment evoked ameliorative adverse effects on the intestinal segments except for the ileum. Gut microbiota analysis revealed that PS-MPs and/or TCH decreased gut microbiota diversity, especially PS-MPs. In addition, PS-MPs and TCH affected the microflora metabolic processes, especially protein absorption and digestion. Gut microbiota dysbiosis could partly lead to the physical and functional damage induced by PS-MPs and TCH. These findings enhance our knowledge regarding the hazards of coexisting microplastics and antibiotics for mammalian intestinal health.

Detection of CCL25 and the correlation between CCL25, CCL28, IL-7, and TSLP in human breast milk

In this study, CCL25, a chemokine that contributes to the immunological function of the thymus and intestines, was detected in human breast milk (HBM) for the first time. We then focused on the correlations of CCL25 with CCL28, TSLP, and IL-7, which were predicted to interact with CCL25 in HBM. We also compared their levels between primiparous and multiparous women. A total of 53 parturient women were recruited. Their HBM was collected during 0-5 days and at 1 month after parturition and the CCL25, CCL28, IL-7, and TSLP levels in the HBM were analyzed using ELISA. The results showed that CCL25 and TSLP levels were significantly higher in colostrum than in mature milk. Moreover, CCL28 and IL-7 levels in colostrum showed a positive correlation. These results indicate that CCL28 and IL-7 in colostrum might interact positively with each other when produced in the mammary glands during lactation. The findings also suggest that the level of parity has no effect on their levels in HBM. In conclusion, our results clarify that CCL25 is present in HBM and that the concentrations of CCL25 and TSLP are higher in colostrum than in mature milk. Moreover, the production of CCL28 and IL-7 might be closely correlated in human colostrum.

Screening of Biomarkers in Liver Tissue after Bariatric Surgery Based on WGCNA and SVM-RFE Algorithms

As the most common chronic liver disease around the world, nonalcoholic fatty liver disease (NAFLD) has a close connection with obesity, diabetes, and metabolic syndrome. Bariatric surgery (BS) is considered to be the most effective treatment for NAFLD. However, the regulatory mechanism of hepatic lipid metabolism after BS remains poorly elucidated. By analyzing two transcriptome datasets regarding liver tissues after BS, namely, GSE83452 and GSE106737, we acquired 110 differentially expressed genes (DEGs). By further analysis of DEGs in terms of the weighted gene coexpression network analysis (WGCNA) and support vector machine-recursive feature elimination (SVM-RFE) algorithms, we identified four crucial genes participating in the regulation of hepatic lipid metabolism: SRGN, THEMIS2, SGK1, and FPR3. In addition, the results of gene set enrichment analysis (GSEA) showed that BS can activate immune-related regulatory pathways and change immune cell infiltration levels. Finally, through cellular level studies, we found that the silencing of SRGN affects the expression of SREBP-1, SIRT1, and FAS during adipogenesis in the liver and the formation of lipid droplets in the liver. In summary, the immune system in the liver is activated after BS, and SRGN participates in the regulation of hepatic lipid metabolism.

MiR-155-5p-SOCS1/JAK1/STAT1 participates in hepatic lymphangiogenesis in liver fibrosis and cirrhosis by regulating M1 macrophage polarization

BACKGROUND

The role and underlying mechanism of liver macrophages and their derived miR-155-5p in hepatic lymphangiogenesis in liver fibrosis remain unclear. Here, we investigated the mechanism by which macrophages and miR-155-5p were involved in lymphangiogenesis during liver fibrosis and cirrhosis.

METHODS

In vivo, hepatic lymphatic vessel expansion was evaluated; the liver macrophage subsets, proportion of peripherally-derived macrophages and expressions of CCL25, MCP-1, VAP-1 and MAdCAM-1 were documented; and miR-155-5p in the peripheral blood and liver was detected. In vitro, macrophages with miR-155-5p overexpression and inhibition were used to clarify the effect of miR-155-5p on regulation of macrophage polarization and the possible signalling pathway.

RESULTS

Hepatic lymphangiogenesis was observed in mice with liver fibrosis and cirrhosis challenged with carbon tetrachloride (CCl4). In the liver, the number of M1 macrophages was associated with lymphangiogenesis and the degree of fibrosis. The liver recruitment of peripherally-derived macrophages occurred during liver fibrosis. The levels of miR-155-5p in the liver and peripheral blood gradually increased with aggravation of liver fibrosis. In vitro, SOCS1, a target of miR-155-5p, regulated macrophage polarization into the M1 phenotype through the JAK1/STAT1 pathway.

CONCLUSION

MiR-155-5p-SOCS1/JAK1/STAT1 pathway participates in hepatic lymphangiogenesis in mice with liver fibrosis and cirrhosis induced by CCl4 by regulating the polarization of macrophages into the M1 phenotype.

Gut immune cell trafficking: inter-organ communication and immune-mediated inflammation

Immune cell trafficking is a complex and tightly regulated process that is indispensable for the body's fight against pathogens. However, it is also increasingly acknowledged that dysregulation of cell trafficking contributes to the pathogenesis of immune-mediated inflammatory diseases (IMIDs) in gastroenterology and hepatology, such as inflammatory bowel disease and primary sclerosing cholangitis. Moreover, altered cell trafficking has also been implicated as a crucial step in the immunopathogenesis of other IMIDs, such as rheumatoid arthritis and multiple sclerosis. Over the past few years, a central role of the gut in mediating these disorders has progressively emerged, and the partly microbiota-driven imprinting of particular cell trafficking phenotypes in the intestine seems to be crucially involved. Therefore, this Review highlights achievements in understanding immune cell trafficking to, within and from the intestine and delineates its consequences for immune-mediated pathology along the gut-liver, gut-joint and gut-brain axes. We also discuss implications for current and future therapeutic approaches that specifically interfere with homing, retention, egress and recirculation of immune cells.

The immune response as a therapeutic target in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a complex and heterogeneous disorder considered a liver-damaging manifestation of metabolic syndrome. Its prevalence has increased in the last decades due to modern-day lifestyle factors associated with overweight and obesity, making it a relevant public health problem worldwide. The clinical progression of NAFLD is associated with advanced forms of liver injury such as fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). As such, diverse pharmacological strategies have been implemented over the last few years, principally focused on metabolic pathways involved in NAFLD progression. However, a variable response rate has been observed in NAFLD patients, which is explained by the interindividual heterogeneity of susceptibility to liver damage. In this scenario, it is necessary to search for different therapeutic approaches. It is worth noting that chronic low-grade inflammation constitutes a central mechanism in the pathogenesis and progression of NAFLD, associated with abnormal composition of the intestinal microbiota, increased lymphocyte activation in the intestine and immune effector mechanisms in liver. This review aims to discuss the current knowledge about the role of the immune response in NAFLD development. We have focused mainly on the impact of altered gut-liver-microbiota axis communication on immune cell activation in the intestinal mucosa and the role of subsequent lymphocyte homing to the liver in NAFLD development. We further discuss novel clinical trials that addressed the control of the liver and intestinal immune response to complement current NAFLD therapies.

Polystyrene microplastics aggravate inflammatory damage in mice with intestinal immune imbalance

Microplastics (MPs) have been detected in drinking water, seafood, and commodities relevant to human daily life, causing widespread concern. Although there have been studies on the health risks of MPs to mammals, the impact of MPs on populations with intestinal immune imbalance has been greatly ignored. The vulnerability of the body with intestinal immune imbalance may increase the likelihood of its response to MPs, which is in urgent need of relevant research. Here, we compared the effects of 500 μg/L polystyrene microplastics (PSMPs) on healthy mice and mice with intestinal immune imbalance through colon photographs, histopathological analysis, expression of inflammatory cytokines, PSMPs distribution, microbial community analysis, and metabolomics analysis. The results demonstrated that intestinal immune imbalance aggravated the colonic response to PSMPs. PSMPs exposure significantly increased the expression of inflammation factors (TNF-α, IL-1β and IFN-γ) in mice with intestinal immune imbalance. In addition, the exposure of PSMPs aggravated the histopathological damage of colonic mucosa in mice with intestinal immune imbalance, and exerted great disturbance on the colonic microbial community and metabolism. This may be due to the significant increase of PSMPs accumulation owing to the damage of intestinal barrier in mice with intestinal immune imbalance. In addition, the increase of several pathogenic bacteria including Bacteroides caused by intestinal immune imbalance also increased the toxicity of PSMPs. Our results highlight that individual with intestinal immune imbalance could be more sensitive to environmental pollution, which should be considered during health risk assessment.

Non-alcoholic fatty liver disease and intestinal immune status: a narrative review

Background and objectives: Non-alcoholic fatty liver disease (NAFLD) interacts with the gut immunity. However, the mechanisms underlying alternations of intestinal immune system in NAFLD remains unclear. To date, no effective medical interventions exist that completely reverse the disease. In this review, we mainly elaborates on the impact of NAFLD on intestinal immune cells and briefly summarize the new treatment methods for NAFLD targeting at intestinal immune cells.Methods: We searched MEDLINE, EMBASE and Web of Science for English-language sources. The preferred citations were meta-analyses and systematic or narrative reviews. Citation tracking was completed for all identified studies included in the refined library, using Google Scholar. No restriction was placed on the year of publication for the included reports.Results: The intestinal immune imbalance promotes liver inflammation and fibrosis in the process of NAFLD, and meanwhile, NAFLD influences disorders of immune cells in the liver and intestinal tract. Biological agents targeting at intestinal immunity has been shown in preclinical studies to be an effective method for systemic immune modulation and alleviates immune-mediated injury.Conclusions: Intestinal immune disorder plays an important role in triggering and amplifying hepatic inflammation in NAFLD. Advances in knowledge of the gut-liver axis are driving the development of diagnostic, prognostic and therapeutic tools based on intestine immunity for the management of NAFLD.

Butyrate functions in concert with myeloid-derived suppressor cells recruited by CCR9 to alleviate DSS-induced murine colitis

Ulcerative colitis (UC) is a precancerous disease caused mainly by a combination of genetic susceptibility, environmental factors and microbiota dysbiosis. As a kind of short-chain fatty acid (SCFA), butyrate has been shown to be closely related to the progression of colitis. However, the exact regulatory mechanism of butyrate in colitis needs to be further elucidated. In our current research, the effects of butyrate were examined in a dextran sulfate sodium (DSS)-induced murine colitis model, which simulates human UC. The administration of butyrate significantly reversed the signs of colitis and alleviated colonic histological damage in DSS‑induced colitis. The transcription levels of the main proinflammatory mediators, including tumor necrosis factor-α, interleukin-6 and interleukin-12, were also reduced, as determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). This indicates that butyrate could alleviate DSS-induced colitis by inhibiting proinflammatory mediators. In addition, we found that myeloid-derived suppressor cells (MDSCs), which have an inflammation-relieving effect, did not effectively alleviate DSS‑induced colitis but showed a compensatory increase in the DSS group. However, the compensatory increase in MDSCs in the DSS group significantly decreased after butyrate treatment. Moreover, the chemokine receptor CCR9, which mediates the homing of intestinal immune cells, also showed consistent changes similar to MDSCs. Butyrate alone did not have the aforementioned effects on mice. Thus, butyrate may effectively relieve DSS‑induced colitis by synergistic regulatory effects with MDSCs, which migrate and gather through CCR9 recruitment.

Regulation of the Migration of Distinct Dendritic Cell Subsets

Dendritic cells (DCs), a class of antigen-presenting cells, are widely present in tissues and apparatuses of the body, and their ability to migrate is key for the initiation of immune activation and tolerogenic immune responses. The importance of DCs migration for their differentiation, phenotypic states, and immunologic functions has attracted widespread attention. In this review, we discussed and compared the chemokines, membrane molecules, and migration patterns of conventional DCs, plasmocytoid DCs, and recently proposed DC subgroups. We also review the promoters and inhibitors that affect DCs migration, including the hypoxia microenvironment, tumor microenvironment, inflammatory factors, and pathogenic microorganisms. Further understanding of the migration mechanisms and regulatory factors of DC subgroups provides new insights for the treatment of diseases, such as infection, tumors, and vaccine preparation.