Tissue-resident memory (T
RM
) T cells are a unique subset of memory T cells that are critical for the first line of defense against pathogens or antigens in peripheral non-lymphoid tissues such as ...liver, gut, and skin. Generally, T
RM
cells are well adapted to the local environment in a tissue-specific manner and typically do not circulate but persist in tissues, distinguishing them from other memory T cell lineages. There is strong evidence that liver T
RM
cells provide a robust adaptive immune response to potential threats. Indeed, the potent effector function of hepatic T
RM
cells makes it essential for chronic liver diseases, including viral and parasite infection, autoimmune liver diseases (AILD), nonalcoholic fatty liver disease (NAFLD), hepatocellular carcinoma (HCC) and liver transplantation. Manipulation of hepatic T
RM
cells might provide novel promising strategies for precision immunotherapy of chronic liver diseases. Here, we provide insights into the phenotype of hepatic T
RM
cells through surface markers, transcriptional profiles and effector functions, discuss the development of hepatic T
RM
cells in terms of cellular origin and factors affecting their development, analyze the role of hepatic T
RM
cells in chronic liver diseases, as well as share our perspectives on the current status of hepatic T
RM
cell research.
T helper cells that produce IL-17 (Th17 cells) have recently been identified as the third distinct subset of effector T cells. Emerging data suggests that Th17 cells play an important role in the ...pathogenesis of many liver diseases by regulating innate immunity, adaptive immunity, and autoimmunity. In this study, we examine the role and mechanism of Th17 cells in the pathogenesis of autoimmune hepatitis (AIH). The serum levels of IL-17 and IL-23, as well as the frequency of IL-17+ cells in the liver, were significantly elevated in patients with AIH, compared to other chronic hepatitis and healthy controls. The hepatic expressions of IL-17, IL-23, ROR-γt, IL-6 and IL-1β in patients with AIH were also significantly increased and were associated with increased inflammation and fibrosis. IL-17 induces IL-6 expression via the MAPK signaling pathway in hepatocytes, which, in turn, may further stimulate Th17 cells and forms a positive feedback loop. In conclusion, Th17 cells are key effector T cells that regulate the pathogenesis of AIH, via induction of MAPK dependent hepatic IL-6 expression. Blocking the signaling pathway and interrupting the positive feedback loop are potential therapeutic targets for autoimmune hepatitis.
Genome-wide association studies have identified 19p13.3 locus associated with primary biliary cholangitis (PBC). Here we aim to identify causative variant(s) and initiate efforts to define the ...mechanism by which the 19p13.3 locus variant(s) contributes to the pathogenesis of PBC. A genome-wide meta-analysis of 1931 PBC subjects and 7852 controls in two Han Chinese cohorts confirms the strong association between 19p13.3 locus and PBC. By integrating functional annotations, luciferase reporter assay and allele-specific chromatin immunoprecipitation, we prioritize rs2238574, an AT-Rich Interaction Domain 3A (ARID3A) intronic variant, as a potential causal variant at 19p13.3 locus. The risk allele of rs2238574 shows higher binding affinity of transcription factors, leading to an increased enhancer activity in myeloid cells. Genome-editing demonstrates the regulatory effect of rs2238574 on ARID3A expression through allele-specific enhancer activity. Furthermore, knock-down of ARID3A inhibits myeloid differentiation and activation pathway, and overexpression of the gene has the opposite effect. Finally, we find ARID3A expression and rs2238574 genotypes linked to disease severity in PBC. Our work provides several lines of evidence that a non-coding variant regulates ARID3A expression, presenting a mechanistic basis for association of 19p13.3 locus with the susceptibility to PBC.
Tetraspanin proteins are closely related to the functional changes of B cells, including antigen presentation, production of cytokines, and transduction. We aim to explore the potential role of ...Tetraspanin 1 (TSPAN1) in the biological activities of B cells in AIH.
Herein, this study found that numbers of cells expressing TSPAN1 were significantly increased in AIH patients compared to PBC, chronic hepatitis B, and healthy control (P < 0.0001). Moreover, there was a positive correlation between numbers of TSPAN1+ cells and AIH disease severity (P < 0.0001). Immunofluorescence staining further confirmed that TSPAN1 was primarily expressed on CD19+ B cells. Flow-cytometric analysis showed that TSPAN1+ B cells secreted more inflammatory cytokines and expressed higher level of CD86 than TSPAN1- B cells. Furthermore, compared with TSAPN1- cells, the expression of CXCR3 on TSPAN1+ cells was also higher. Meanwhile, CXCL10, the ligand of CXCR3, was significantly elevated in the liver of AIH (P < 0.01) and had positive correlation with the quantities of TSPAN1 (P < 0.05). Interestingly, the numbers of TSPAN1+ B cells were decreased in AIH patients after immunosuppressive therapy.
TSPAN1
B cells in the liver may promote the progression of AIH
secreting cytokines and presenting antigens. The chemotactic movement of TSPAN1
B cells toward the liver of AIH was possibly due to CXCR3 - CXCL10 interaction.
The key role of tissue-resident memory T (T
) cells in the immune regulation of hepatocellular carcinoma (HCC) has been investigated and reported, but the regulatory mechanism of tumor ...microenvironment on T
cells is still unclear. Lymphocyte activating gene 3 (LAG-3) is a promising next-generation immune checkpoint that is continuously expressed due to persistent antigen exposure in the tumor microenvironment. Fibrinogen-like protein 1 (FGL1) is a classical ligand of LAG-3 and can promote T cell exhaustion in tumors. Here, we excavated the effect of FGL1-LAG3 regulatory axis on T
cells in HCC.
The function and phenotype of intrahepatic CD8
T
cells in 35 HCC patients were analyzed using multicolor flow cytometry. Using a tissue microarray of 80 HCC patients, we performed the prognosis analysis. Moreover, we investigated the suppressive effect of FGL1 on CD8
T
cells both in
induction model and
orthotopic HCC mouse model.
There was an increase in LAG3 expression in CD8
T
cells in end-stage HCC; moreover, FGL1 levels were negatively correlated with CD103 expression and related to poor outcomes in HCC. Patients with high CD8
T
cell proportions have better outcomes, and FGL1-LAG3 binding could lead to the exhaustion of CD8
T
cells in tumors, indicating its potential as a target for immune checkpoint therapy of HCC. Increased FGL1 expression in HCC may result in CD8
T
cell exhaustion, causing tumor immune escape.
We identified CD8
T
cells as a potential immunotherapeutic target and reported the effect of FGL1-LAG3 binding on CD8
T
cell function in HCC.
Autoimmune hepatitis (AIH) is characterized by interface hepatitis, elevated serum alanine aminotransferase and aspartate aminotransferase levels, circulating autoantibodies, and elevated ...predominantly immunoglobulin G (IgG) levels. The goal in the treatment of autoimmune hepatitis (AIH) is complete disease remission. Here we took advantage of a large cohort of AIH patients to clarify predictors associated with biochemical and histological remission. Of 705 patients with complete follow-up, 569 (80.7%) patients achieved complete biochemical remission. Lower IgG levels (17.8 vs. 25 g/L,
p
< 0.001) and less liver cirrhosis (19.3% vs. 33.1%,
p
< 0.001) at diagnosis were observed in these patients. They also had lower serum IgG levels (13 vs. 18.9 g/L,
p
< 0.001) after 3 months of treatment. Histological remission was achieved in 69.4% of 160 patients with complete biochemical remission after 3 years of treatment. Patients with histological remission had lower IgG levels (16.2 vs. 20.1 g/L,
p
= 0.006) and Ishak fibrosis scores (3.4 vs. 4.1,
p
= 0.010) at diagnosis, and they appeared to achieve biochemical remission more rapidly (1 vs. 3 months,
p
< 0.001). Of note, patients with histological remission had higher frequency of fibrosis regression than those with persisting histological activity (87.5% vs. 60%,
p
= 0.004). In conclusion, lower serum IgG levels, less fibrosis in liver histology at diagnosis, and rapid response to immunosuppressive therapy are reliable predictors of biochemical and histological remission. Our study underscores the importance of early diagnosis and appropriate treatment.
Primary biliary cholangitis (PBC) is a chronic autoimmune liver disease with an immunopathogenesis that includes highly differentiated cytotoxic T cell infiltration in portal areas. We have taken ...advantage of a large and well-defined cohort of patients with PBC, AIH, chronic hepatitis virus, and healthy controls to study for the presence of highly differentiated T cells which express the killer cell lectin-like receptor G1 (KLRG1). Such studies were performed using both liver and peripheral blood mononuclear cells. In particular, gene expression data (GSE79850) from 16 PBC patients stratified according to future risk of liver transplantation were analyzed for markers of highly differentiated cytotoxic T cells. Liver biopsy samples from 44 PBC patients were studied by immunohistochemistry and a separate cohort of PBC blood samples were studied by flow cytometry. Gene expression data demonstrated correlation of increased KLRG1 and cytotoxic lymphocyte molecules, such as granzyme B (GZMB) and perforin (PRF1), to disease severity as measured by future risk of liver transplantation. Immunohistochemistry demonstrated abundant infiltration of KLRG1+ cells into liver portal areas (mean of 45% of infiltrating cells, range 25–75%) positively correlated with hepatic inflammatory (r = 0.47, p = 0.001) and hepatic fibrosis (r = 0.34, p = 0.021) scores. KLRG1+ lymphocyte liver portal area infiltration was positively correlated with serum alkaline phosphatase (r = 0.45, p = 0.005) and GGT (r = 0.40, p = 0.014), and AST (r = 0.35, p = 0.033) levels. Mononuclear blood flow cytometry studies showed KLRG1+ lymphocytes had greater levels of cytotoxic molecules (granzyme B and perforin), inflammatory cytokines (IFN-γ and TNF-α) and inflammatory chemokine receptors (CCR5 and CX3CR1) than KLRG1-counterparts. However, clearly the most significant data was that found in liver with the intense portal infiltrates that are unique to PBC. Conclusion: Highly cytotoxic KLRG1+ lymphocytes have invaded PBC liver portal areas. Liver KLRG1 gene expression and the abundance of KLRG1+ lymphocytes are positively correlated with disease biomarkers used as clinical trial outcome measures (liver transplantation and serum alkaline phosphatase), suggesting the targeting of KLRG1+ lymphocytes as a rational approach for PBC therapeutic drug development.
•Expression of liver KLRG1 is correlated to future risk of liver transplantation in PBC.•Hepatic infiltrated KLRG1+ cells are correlated with disease severity in PBC.•Circulating KLRG1+ lymphocytes are highly inflammatory cells.•E-cadherin partially disappears in intrahepatic small bile ducts of PBC patients.
Background: Increasing data suggests an interaction between bile acids and intestinal microbiota in the pathogenesis of primary biliary cholangitis (PBC). Bile acid sequestrants are widely used to ...bind bile acids in the intestinal lumen and are therefore posited to impact gut bacteria. Herein we aimed to investigate the effects of cholestyramine on the bile acid profile and gut microbiome in a cohort of icteric PBC patients.
Results: Thirty-three PBC patients were treated with cholestyramine, serum and stool samples were collected at baseline, 4 and 16 weeks. Shotgun metagenomic sequencing and targeted metabolomic profiling were performed. Following cholestyramine administration, patients exhibited a high interpersonal variability in remission of cholestasis, and were therefore dichotomized according to the decrease of total bilirubin. Gut microbial co-abundance networks showed distinct taxa interactions between subjects with superior remission (SR) and those with inferior remission (IR) at baseline. After treatment, compositional shifts of the microbiome in the SR group were characterized with enrichment of two Lachnospiraceae species, typically producing short-chain fatty acids (SCFAs). In contrast, Klebsiella pneumonia, a commensal pathobiont, was only increased in the IR group. Correspondingly, metabolome analysis demonstrated that patients with SR, but not IR, were marked by elevations of SCFAs including valeric acid and caproic acid. Finally, integrative analysis identified robust associations between the variations of microbiota, metabolites, and inflammatory cytokines in SR group, indicating potential mechanistic links.
Conclusions: Beneficial responses caused by cholestyramine were closely related with compositional and functional alterations in gut commensal, highlighting the possibility of exploring bile acid-microbiota interactions for treating PBC.
Our objective was to investigate the potential roles of CCN1 in the inflammation and macrophage infiltration of nonalcoholic fatty liver disease (NAFLD). The regulation of hepatic CCN1 expression was ...investigated in vitro with murine primary hepatocytes treated with free fatty acids or lipopolysaccharide (LPS) and in vivo with high-fat (HF) diet-fed mice or ob/ob mice. CCN1 protein and a liver-specific CCN1 expression plasmid were administered to mice fed a normal diet (ND) or HF diet. Myeloid-derived macrophages and RAW264.7 cells were also treated with CCN1 in vitro to determine the chemotactic effects of CCN1 on macrophages. LPS treatment significantly increased hepatic CCN1 expression in HF diet-fed mice and ob/ob mice. LPS and FFAs induced CCN1 expression in primary murine hepatocytes in vitro through the TLR4/MyD88/AP-1 pathway. CCN1 protein and overexpression of CCN1 in the liver induced more severe hepatic inflammation and macrophage infiltrates in HF mice than in ND mice. CCN1 recruited macrophages through activation of the Mek/Erk signaling pathway in myeloid-derived macrophages and RAW264.7 cells in vitro. Endotoxin and FFA-induced CCN1 expression in hepatocytes is involved in the hepatic proinflammatory response and macrophage infiltration in murine NAFLD.
IgG4-related disease (IgG4-RD) is characterized by intense infiltration of IgG4-positive plasma cells in affected organs. However, the mechanisms acting in the immune responses in IgG4-RD are not ...fully understood. The aim of this study was to dissect the mechanism underlying the immunoglobulin class switch in IgG4-RD by addressing the crosstalk between IL-35-producing and Th9 cells. The expression level of IL-35 was examined in plasma samples from patients with hepatobiliary and/or pancreatic manifestations of IgG4-RD. Our data demonstrate that IgG4-RD patients exhibit significantly high-level productions of IL-35 as compared to disease and healthy controls. We detected the two subunits of IL-35, EBI3 and IL-12p35, in the two major affected organs, liver and pancreatic tissue, from IgG4-RD. The EBI3- and IL-12p35-positive cells were significantly higher in affected organs in IgG4-RD as compared to disease controls. The colocalization of EBI3 with CD19 and CD38, markers for B cells, suggest the presence of IL-35-producing B cells in affected organs in IgG4-RD. The effects of IL-35 in Th9 differentiation and IL-9 in production of immunoglobulin were then assessed. Surprisingly, IL-35 treatment promoted naïve CD4 T cell differentiating towards Th9 cells through IRF4 signaling. As a consequence, IL-9 secreted by Th9 cells promoted the differentiation of plasma cells and production of IgG1 and IgG4, predominantly IgG4. In conclusion, our data demonstrate that IL-35 actively participates in the process of inflammation and plays an important role in Th9 differentiation resulting in an immunoglobulin class switch towards IgG4.
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