Drug-induced liver injury (DILI) ascribed to non-steroidal anti-inflammatory drugs (NSAIDs) in the USA-Update with genetic correlations.

OBJECTIVE: To describe patients with NSAID-DILI, including genetic factors associated with idiosyncratic DILI. METHODS: In DILIN, subjects with presumed DILI are enrolled and followed for at least 6 months. Causality is adjudicated by a Delphic approach. HLA sequencing of multiethnic NSAID-DILI patients and HLA allele imputation of matching population controls were performed following overall, class and drug-based association analysis. Significant results were tested in a non-Hispanic White (NHW) case-control replication cohort. RESULTS: Between September 2004 and March 2022, causality was adjudicated in 2498, and 55 (41 [75%] women) were assessed as likely due to NSAIDs. Median age at onset was 55 y (range 22-83 y). Diclofenac was the causative drug in 29, celecoxib in 7, ibuprofen in 5, etodolac and meloxicam each in 4. Except for meloxicam and oxaprozin (n = 2), the liver injury was hepatocellular with median R 15-25. HLA-DRB1*04:03 and HLA-B*35:03 were significantly more frequent in NSAID-DILI patients than in non-NSAID DILI controls. Interestingly, 85% of the HLA-DRB1*04:03 carriers developed DILI due to the use of acetic acid derivative NSAIDs, supporting the hypothesis that HLA-DRB1*04:03 could be a drug and/or class risk factor. HLA-B*35:03 but not HLA-DRB1*04:03 association was confirmed in the independent NHW replication cohort, which was largely driven by diclofenac. CONCLUSIONS: Despite prevalent use, NSAID-DILI is infrequent in the United States. Diclofenac is the most commonly implicated, and adherence to warnings of risk and close observation are recommended. The increased frequency of HLA-B*35:03 and DRB1*04:03, driven by diclofenac, suggests the importance of immune-mediated responses.

Immune mechanisms linking metabolic injury to inflammation and fibrosis in fatty liver disease - novel insights into cellular communication circuits.

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease and is emerging as the leading cause of cirrhosis, liver transplantation and hepatocellular carcinoma (HCC). NAFLD is a metabolic disease that is considered the hepatic manifestation of the metabolic syndrome; however, during the evolution of NAFLD from steatosis to non-alcoholic steatohepatitis (NASH), to more advanced stages of NASH with liver fibrosis, the immune system plays an integral role. Triggers for inflammation are rooted in hepatic (lipid overload, lipotoxicity, oxidative stress) and extrahepatic (gut-liver axis, adipose tissue, skeletal muscle) systems, resulting in unique immune-mediated pathomechanisms in NAFLD. In recent years, the implementation of single-cell RNA-sequencing and high dimensional multi-omics (proteogenomics, lipidomics) and spatial transcriptomics have tremendously advanced our understanding of the complex heterogeneity of various liver immune cell subsets in health and disease. In NAFLD, several emerging inflammatory mechanisms have been uncovered, including profound macrophage heterogeneity, auto-aggressive T cells, the role of unconventional T cells and platelet-immune cell interactions, potentially yielding novel therapeutics. In this review, we will highlight the recent discoveries related to inflammation in NAFLD, discuss the role of immune cell subsets during the different stages of the disease (including disease regression) and integrate the multiple systems driving inflammation. We propose a refined concept by which the immune system contributes to all stages of NAFLD and discuss open scientific questions arising from this paradigm shift that need to be unravelled in the coming years. Finally, we discuss novel therapeutic approaches to target the multiple triggers of inflammation, including combination therapy via nuclear receptors (FXR agonists, PPAR agonists).

Single-cell atlas of hepatic T cells reveals expansion of liver-resident naive-like CD4+ T cells in primary sclerosing cholangitis.

BACKGROUND & AIMS: Little is known about the composition of intrahepatic immune cells and their contribution to the pathogenesis of primary sclerosing cholangitis (PSC). Herein, we aimed to create an atlas of intrahepatic T cells and thereby perform an in-depth characterization of T cells in inflamed human liver. METHODS: Different single-cell RNA sequencing methods were combined with in silico analyses on intrahepatic and peripheral T cells from patients with PSC (n = 11) and healthy donors (HDs, n = 4). Multi-parameter flow cytometry and functional in vitro experiments were conducted on samples from patients with PSC (n = 24), controls with other liver diseases and HDs. RESULTS: We identified a population of intrahepatic naive-like CD4+ T cells, which was present in all liver diseases tested, but particularly expanded in PSC. This population had a transcriptome and T cell receptor repertoire similar to circulating naive T cells but expressed a set of genes associated with tissue residency. Their periductal location supported the concept of tissue-resident naive-like T cells in livers of patients with PSC. Trajectory inference suggested that these cells had the developmental propensity to acquire a T helper 17 (TH17) polarization state. Functional and chromatin accessibility experiments revealed that circulating naive T cells in patients with PSC were predisposed to polarize towards TH17 cells. CONCLUSION: We report the first atlas of intrahepatic T cells in PSC, which led to the identification of a previously unrecognized population of tissue-resident naive-like T cells in the inflamed human liver and to the finding that naive CD4+ T cells in PSC harbour the propensity to develop into TH17 cells. LAY SUMMARY: The composition of intrahepatic immune cells in primary sclerosing cholangitis (PSC) and their contribution to disease pathogenesis is widely unknown. We analysed intrahepatic T cells and identified a previously uncharacterized population of liver-resident CD4+ T cells which are expanded in the livers of patients with PSC compared to healthy liver tissue and other liver diseases. These cells are likely to contribute to the pathogenesis of PSC and could be targeted in novel therapeutic approaches.

24-Norursodeoxycholic acid reshapes immunometabolism in CD8+ T cells and alleviates hepatic inflammation.

BACKGROUND & AIMS: 24-Norursodeoxycholic acid (NorUDCA) is a novel therapeutic bile acid used to treat immune-mediated cholestatic liver diseases, such as primary sclerosing cholangitis (PSC), where dysregulated T cells including CD8+ T cells contribute to hepatobiliary immunopathology. We hypothesized that NorUDCA may directly modulate CD8+ T cell function thus contributing to its therapeutic efficacy. METHODS: NorUDCA's immunomodulatory effects were first studied in Mdr2-/- mice, as a cholestatic model of PSC. To differentiate NorUDCA's immunomodulatory effects on CD8+ T cell function from its anticholestatic actions, we also used a non-cholestatic model of hepatic injury induced by an excessive CD8+ T cell immune response upon acute non-cytolytic lymphocytic choriomeningitis virus (LCMV) infection. Studies included molecular and biochemical approaches, flow cytometry and metabolic assays in murine CD8+ T cells in vitro. Mass spectrometry was used to identify potential CD8+ T cell targets modulated by NorUDCA. The signaling effects of NorUDCA observed in murine cells were validated in circulating T cells from patients with PSC. RESULTS: NorUDCA demonstrated immunomodulatory effects by reducing hepatic innate and adaptive immune cells, including CD8+ T cells in the Mdr2-/- model. In the non-cholestatic model of CD8+ T cell-driven immunopathology induced by acute LCMV infection, NorUDCA ameliorated hepatic injury and systemic inflammation. Mechanistically, NorUDCA demonstrated strong immunomodulatory efficacy in CD8+ T cells affecting lymphoblastogenesis, expansion, glycolysis and mTORC1 signaling. Mass spectrometry identified that NorUDCA regulates CD8+ T cells by targeting mTORC1. NorUDCA's impact on mTORC1 signaling was further confirmed in circulating PSC CD8+ T cells. CONCLUSIONS: NorUDCA has a direct modulatory impact on CD8+ T cells and attenuates excessive CD8+ T cell-driven hepatic immunopathology. These findings are relevant for treatment of immune-mediated liver diseases such as PSC. LAY SUMMARY: Elucidating the mechanisms by which 24-norursodeoxycholic acid (NorUDCA) works for the treatment of immune-mediated liver diseases, such as primary sclerosing cholangitis, is of considerable clinical interest. Herein, we uncovered an unrecognized property of NorUDCA in the immunometabolic regulation of CD8+ T cells, which has therapeutic relevance for immune-mediated liver diseases, including PSC.

Inter- and Intra-individual Variation, and Limited Prognostic Utility, of Serum Alkaline Phosphatase in a Trial of Patients With Primary Sclerosing Cholangitis.

BACKGROUND & AIMS: Serum alkaline phosphatase (ALP) and the enhanced liver fibrosis (ELF) score are used as endpoints in trials of patients with primary sclerosing cholangitis (PSC). We aimed to quantify inter- and intra-individual variation in levels of ALP and the ELF score over time, and evaluated their association with fibrosis progression. METHODS: We analyzed data from 234 patients with large-duct PSC enrolled in a 2-year, phase 2b placebo-controlled trial of simtuzumab. Participants were assessed by laboratory tests every 4 weeks, and liver biopsies collected at time of screening, week 48, and week 96. RESULTS: Serum levels of ALP and ELF scores did not differ significantly between simtuzumab and placebo groups, so the data were pooled. Median per-patient variations in ALP between clinic visits were approximately 12% over 12 weeks, 20% over 48 weeks, and 20% over 96 weeks. Reductions, unrelated to study intervention, of more than 40% in ALP were observed in 10.9% of patients with baseline activity greater than 2-fold the upper limit of normal (ULN) and 12.5% of patients with more than 3-fold the ULN at 1 year. At 2 years, reductions of more than 40% in ALP were observed in 15.8% of patients with baseline activity greater than 2-fold the ULN and 17.9% of patients with more than 3-fold the ULN. Among the 209 patients with Ishak fibrosis stage 0-4 at baseline, serum ALP activity did not associate with development of cirrhosis or with a 2-point increase in fibrosis stage at 2 years. In contrast, the median per-patient variation in ELF scores between clinic visits was approximately 3% over 12 weeks, 4% over 48 weeks, and 4% over 96 weeks. Elevated ELF scores at baseline and at weeks 12, 24 and 48, each associated with development of cirrhosis at 2 years (odds ratio >2.75; P < .01 for all timepoints). ELF scores at baseline and weeks 12, 24 and 48, also associated with a 2-point increase in fibrosis stage at 2 years (odds ratios all greater than 2; P < .01 for all timepoints). CONCLUSIONS: In an analysis of data from patients with large-duct PSC enrolled in a prospective trial, we found large interindividual and intraindividual variations in serum ALP activity. Serum ALP activity did not associate with disease progression over a 2-year period. Variations in ELF score were smaller, and scores determined at multiple timepoints associated with fibrosis progression and development of cirrhosis.

Patient Age, Sex, and Inflammatory Bowel Disease Phenotype Associate With Course of Primary Sclerosing Cholangitis.

BACKGROUND & AIMS: Primary sclerosing cholangitis (PSC) is an orphan hepatobiliary disorder associated with inflammatory bowel disease (IBD). We aimed to estimate the risk of disease progression based on distinct clinical phenotypes in a large international cohort of patients with PSC. METHODS: We performed a retrospective outcome analysis of patients diagnosed with PSC from 1980 through 2010 at 37 centers in Europe, North America, and Australia. For each patient, we collected data on sex, clinician-reported age at and date of PSC and IBD diagnoses, phenotypes of IBD and PSC, and date and indication of IBD-related surgeries. The primary and secondary endpoints were liver transplantation or death (LTD) and hepatopancreatobiliary malignancy, respectively. Cox proportional hazards models were applied to determine the effects of individual covariates on rates of clinical events, with time-to-event analysis ascertained through Kaplan-Meier estimates. RESULTS: Of the 7121 patients in the cohort, 2616 met the primary endpoint (median time to event of 14.5 years) and 721 developed hepatopancreatobiliary malignancy. The most common malignancy was cholangiocarcinoma (n = 594); patients of advanced age at diagnosis had an increased incidence compared with younger patients (incidence rate: 1.2 per 100 patient-years for patients younger than 20 years old, 6.0 per 100 patient-years for patients 21-30 years old, 9.0 per 100 patient-years for patients 31-40 years old, 14.0 per 100 patient-years for patients 41-50 years old, 15.2 per 100 patient-years for patients 51-60 years old, and 21.0 per 100 patient-years for patients older than 60 years). Of all patients with PSC studied, 65.5% were men, 89.8% had classical or large-duct disease, and 70.0% developed IBD at some point. Assessing the development of IBD as a time-dependent covariate, Crohn's disease and no IBD (both vs ulcerative colitis) were associated with a lower risk of LTD (unadjusted hazard ratio [HR], 0.62; P < .001 and HR, 0.90; P = .03, respectively) and malignancy (HR, 0.68; P = .008 and HR, 0.77; P = .004, respectively). Small-duct PSC was associated with a lower risk of LTD or malignancy compared with classic PSC (HR, 0.30 and HR, 0.15, respectively; both P < .001). Female sex was also associated with a lower risk of LTD or malignancy (HR, 0.88; P = .002 and HR, 0.68; P < .001, respectively). In multivariable analyses assessing the primary endpoint, small-duct PSC characterized a low-risk phenotype in both sexes (adjusted HR for men, 0.23; P < .001 and adjusted HR for women, 0.48; P = .003). Conversely, patients with ulcerative colitis had an increased risk of liver disease progression compared with patients with Crohn's disease (HR, 1.56; P < .001) or no IBD (HR, 1.15; P = .002). CONCLUSIONS: In an analysis of data from individual patients with PSC worldwide, we found significant variation in clinical course associated with age at diagnosis, sex, and ductal and IBD subtypes. The survival estimates provided might be used to estimate risk levels for patients with PSC and select patients for clinical trials.

Single-gene association between GATA-2 and autoimmune hepatitis: A novel genetic insight highlighting immunologic pathways to disease.

Background & Aims Autoimmune hepatitis (AIH), an immune-mediated liver disease, originates as a consequence of interacting genetic and environmental risk factors. Treatment remains non-specific and prone to side effects. Deficiencies in regulatory T cell (Treg) function are hypothesized to contribute to the pathogenesis of AIH. Methods We describe an adult patient who presented with AIH in the context of monocytopenia. The patient was characterized by GATA2 gene sequencing, flow cytometry of peripheral blood for leucocyte subsets, ELISA for serum Flt-3 ligand, and immunohistochemistry of liver biopsy tissue. Results Sequencing confirmed a GATA2 mutation. Peripheral Treg were absent in the context of a preserved total T cell count. Immunostaining for the Treg transcription factor FOXP3 was reduced in liver tissue as compared to a control AIH specimen. There were marked deficiencies in multiple antigen-presenting cell subsets and Flt-3 ligand was elevated. These findings are consistent with previous reports of GATA2 dysfunction. Conclusions The association of a GATA2 mutation with AIH is previously unrecognized. GATA2 encodes a hematopoietic cell transcription factor, and mutations may manifest as monocytopenia, dendritic and B cell deficiencies, myelodysplasia, and immunodeficiency. Tregs may be depleted as in this case. Our findings provide support for the role of Tregs in AIH, complement reports of other deficiencies in T cell regulation causing AIH-like syndromes, and support the rationale of attempting to modulate the Treg axis for the therapeutic benefit of AIH patients.

Intestinal CCL25 expression is increased in colitis and correlates with inflammatory activity.

CCL25-mediated activation of CCR9 is critical for mucosal lymphocyte recruitment to the intestine. In immune-mediated liver injury complicating inflammatory bowel disease, intrahepatic activation of this pathway allows mucosal lymphocytes to be recruited to the liver, driving hepatobiliary destruction in primary sclerosing cholangitis (PSC). However, in mice and healthy humans CCL25 expression is restricted to the small bowel, whereas few data exist on activation of this pathway in the inflamed colon despite the vast majority of PSC patients having ulcerative colitis. Herein, we show that colonic CCL25 expression is not only upregulated in patients with active colitis, but strongly correlates with endoscopic Mayo score and mucosal TNFα expression. Moreover, approximately 90% (CD4(+)) and 30% (CD8(+)) of tissue-infiltrating T-cells in colitis were identified as CCR9(+) effector lymphocytes, compared to <10% of T-cells being CCR9(+) in normal colon. Sorted CCR9(+) lymphocytes also demonstrated enhanced cellular adhesion to stimulated hepatic sinusoidal endothelium compared with their CCR9(-) counterparts when under flow. Collectively, these results suggest that CCR9/CCL25 interactions are not only involved in colitis pathogenesis but also correlate with colonic inflammatory burden; further supporting the existence of overlapping mucosal lymphocyte recruitment pathways between the inflamed colon and liver.

Autoimmune hepatitis: an approach to disease understanding and management.

INTRODUCTION: Autoimmune hepatitis is a chronic immune-mediated liver injury, frequently associated with progression to end-stage liver disease if untreated. Patients commonly present with hepatitis, positive immune serology, elevated immunoglobulins and compatible liver histology, in the absence of an alternative aetiology. SOURCES OF DATA: Data for this review were obtained using PubMed. AREAS OF AGREEMENT: Disease usually responds to steroids and azathioprine, and appears to be a manifestation of autoimmune predisposition triggered in genetically susceptible individuals exposed to likely environmental challenges. We provide an up-to-date approach to disease understanding and management along with the clinical approach to diagnosis and current treatment suggestions. AREAS OF CONTROVERSY: Controversies such as second line therapies and novel markers of disease activity are introduced. GROWING POINTS: Increased understanding of the immunoregulatory mechanisms behind autoimmune hepatitis has led to opportunities for new therapies. These are developed including a discussion of timely research studies relevant to future therapies for patients.

Interleukin-37 exacerbates liver inflammation and promotes IFN-γ production in NK cells.

Interleukin (IL)-37, a unique member of the IL-1 family, is known for its anti-inflammatory properties. However, its effects on immune-mediated liver diseases, such as primary biliary cholangitis (PBC) and acute immune-mediated hepatitis, remain unclear. Using mouse models of autoimmune cholangitis and hepatitis induced by 2-OA-OVA and concanavalin A (Con A) respectively, we introduced the human IL-37 gene via a liver-preferred adeno-associated virus vector (AAV-IL-37) to mice, as mice lack endogenous IL-37. Our findings reveal that IL-37 did not affect autoimmune cholangitis. Surprisingly, IL-37 exacerbated inflammation in Con A-induced hepatitis rather than mitigating it. Mechanistic insights suggest that this exacerbation involves the interferon (IFN)-γ pathway, supported by elevated serum IFN-γ levels in AAV-IL-37-treated Con A mice. Specifically, IL-37 heightened the number of hepatic NK and NKT cells, increased the production of the NK cell chemoattractant CCL5, and elevated the frequency of hepatic NK and NKT cells expressing IFN-γ. Moreover, IL-37 enhanced IFN-γ secretion from NK cells when combined with other proinflammatory cytokines, highlighting its synergistic effect in promoting IFN-γ production. These unexpected outcomes underscore a novel role for IL-37 in exacerbating liver inflammation during immune-mediated liver diseases, implicating its influence on NK cells and the production of IFN-γ by these cells.

Intergenic risk variant rs56258221 skews the fate of naive CD4+ T cells via miR4464-BACH2 interplay in primary sclerosing cholangitis.

Primary sclerosing cholangitis (PSC) is an immune-mediated liver disease of unknown pathogenesis, with a high risk to develop cirrhosis and malignancies. Functional dysregulation of T cells and association with genetic polymorphisms in T cell-related genes were previously reported for PSC. Here, we genotyped a representative PSC cohort for several disease-associated risk loci and identified rs56258221 (BACH2/MIR4464) to correlate with not only the peripheral blood T cell immunophenotype but also the functional capacities of naive CD4+ T (CD4+ TN) cells in people with PSC. Mechanistically, rs56258221 leads to an increased expression of miR4464, in turn causing attenuated translation of BACH2, a major gatekeeper of T cell quiescence. Thereby, the fate of CD4+ TN is skewed toward polarization into pro-inflammatory subsets. Clinically, people with PSC carrying rs56258221 show signs of accelerated disease progression. The data presented here highlight the importance of assigning functional outcomes to disease-associated genetic polymorphisms as potential drivers of diseases.

Recent Insights into Pediatric Primary Sclerosing Cholangitis.

This article reviews recent literature on the pathogenesis, presentation, diagnosis, comorbidities, natural history, and management of pediatric primary sclerosing cholangitis (PSC). The authors shed light on the role of genetic and environmental factors in PSC, although recognize the limitations in the understanding of PSC pathogenesis. They reflect on presenting disease phenotypes, including the association with inflammatory bowel disease and frequent histologic presence of autoimmune hepatitis features. The current lack of effective medications is discussed, and disease complications and prognosis are described. Finally, the authors highlight available evidence while acknowledging the paucity of prospective pediatric data.

Autoimmune hepatitis-is histology conclusive?

Liver biopsy is an essential and necessary element in the diagnosis and management of autoimmune hepatitis, and is of very special importance in the scoring system for diagnosis. Histopathology shows moderate to severe inflammatory infiltrates with abundant plasma cells in the enlarged portal tracts with interface hepatitis and moderate to severe necroinflammatory lesions in the lobules with lymphoplasmacytic reaction. Regeneration develops with rosette formation and regenerative nodules. One important issue is the differentiation between acute onset of autoimmune hepatitis and a flare up of chronic disease; this cannot be diagnosed in some cases clinically and therefore requires a biopsy to evaluate the stage of the disease. There are some variants of the disease with cholestatic features such as autoantibody negative autoimmune hepatitis and giant cell hepatitis as well as overlap syndromes with primary biliary cholangitis and primary sclerosing cholangitis. Clinically, three types of autoimmune hepatitis are differentiated according to autoantibody formation and the clinical picture, however, histopathologically there is no difference between these three types. Differential diagnosis of autoimmune hepatitis includes drug-induced liver injury with minocycline, alpha methyldopa, nitrofurantoin and checkpoint inhibitors such as infliximab. Wilson´s disease is also an important differential diagnosis especially in young adults. A liver biopsy is mandatory to confirm the diagnosis of autoimmune hepatitis but histopathology alone is not conclusive.

Characterization of gut-homing molecules in non-endstage livers of patients with primary sclerosing cholangitis and inflammatory bowel disease.

INTRODUCTION: The co-occurrence of inflammatory bowel disease (IBD) in up to 80% of patients with primary sclerosing cholangitis (PSC) suggests a relation between the gut and the liver in patients with both PSC and IBD. One hypothesis suggests that aberrantly expressed homing molecules in the liver drive infiltration of gut-homing memory T-cells that are originally primed in intestinal environment. One of the main findings supporting this hypothesis is the expression of mucosal addressin cell adhesion molecule 1 (MAdCAM-1) in PSC livers. Expression of homing molecules in early PSC remains unclear. The aim of this study was to investigate expression patterns of homing chemokines and adhesion molecules in PSC-IBD colons and livers, and to study whether changes are already present in early stages of PSC. METHODS: Needle biopsies from livers of 20 PSC patients with short-term PSC (PSC-IBDST) as well as explant liver biopsies of 8 patients with long-term PSC (PSC-IBDLT) were collected (median disease duration 0 and 22 years, respectively). Only patients with concomitant IBD were included (89% ulcerative colitis and 11% Crohn's disease). Expression and distribution of MAdCAM-1, VAP-1, integrin ß7, CCL25, CCL28, CXCL12, αE (CD103) and E-cadherin were assessed in both liver and colon tissue. Liver tissue collected from obstructive cholangitis in resection specimens for Klatskin tumors or resection specimens from hepatic metastasis, liver tissue of patients with hepatitis C virus (HCV) and of patients with primary biliary cholangitis (PBC) served as controls. RESULTS: MAdCAM-1 expression in livers of PSC-IBDLT patients was increased compared to controls. The proportion of CD3+ T-cells expressing integrin ß7 did not differ between PSC-IBDST and control groups, but was higher in liver tissue of PSC-IBDLT patients. There was no difference in αE+ T-cells between PSC-IBDLT and control groups. The chemokine CCL28 was highly expressed in biliary epithelial cells. This intense staining pattern was more pronounced in PSC-IBDST, but overall did not significantly differ from controls. CONCLUSIONS: We confirm that aberrant gut lymphocyte homing to the liver exists in PSC, linking gut and liver disease pathology in PSC-IBD. Our data suggests that this phenomenon increases over time in later stages of the disease, worsening ongoing inflammation.