Autoimmune hepatitis: From mechanisms to therapy

Nuezhenoside G13 from Osmanthus fragrans fruit ameliorates Concanavalin A-induced autoimmune hepatitis by regulating the NF-κB/MAPK pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Osmanthus fragrans fruit (OFF) exhibits hepatoprotective function, and it is consumed as food and used in traditional medicine in China. Nuezhenoside G13 (G13) is present in the highest levels in OFF. Autoimmune hepatitis (AIH) is a manifestation of liver disease and seriously endangers health. However, it remains unclear whether G13 affects AIH.

AIM OF THE STUDY

To clarify the effect of G13 on AIH and its exact underlying mechanism from a new perspective.

MATERIALS AND METHODS

We used a Concanavalin A-induced AIH mouse model and lipopolysaccharide-treated Raw264.7 cells to quantify serum biochemical indicators and confirm whether G13 exhibited protective effects in the AIH mice. Furthermore, we evaluated the effect of G13 via hematoxylin and eosin and immunohistochemical staining. We used enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction to quantify the inflammatory factors. We confirmed that G13 inhibited apoptosis via terminal deoxynucleotidyl transferase dUTP nick end labeling staining. Molecular docking, immunofluorescence, and western blotting experiments of G13 and key proteins of the NF-κB/MAPK pathway revealed that G13 alleviated inflammation. In addition, Cell Counting Kit-8, ELISA, NO detection, and western blotting assays were performed. Finally, we used an inhibitor of the p38 MAPK to verify that G13 reduced inflammation through the NF-κB/MAPK pathway in Raw264.7 cells.

RESULTS

The in vivo experiments revealed that G13 improved oxidative stress and apoptosis. In addition, G13 decreased the expression levels of CD4+, CD8+, F4/80+, and Ly6G and the secretion of inflammatory factors. Interestingly, G13 reduced the phosphorylation levels of IκBα, NF-κB, JNK, ERK1/2, and p38. Additionally, the in vitro experiments revealed that G13 alleviated inflammation through the NF-κB/MAPK pathway in lipopolysaccharide-treated Raw264.7 cells. Furthermore, molecular docking demonstrated that the binding fraction of G13 with these proteins was high.

CONCLUSION

G13 suppressed oxidative stress, apoptosis, and inflammation in a Concanavalin A-induced AIH mouse model. Furthermore, G13 exerted its effect through the NF-κB/MAPK pathway.

Autoimmune Extrahepatic Disorders in Patients With Autoimmune Liver Disease

BACKGROUND

Autoimmune liver diseases (ALDs) (primary biliary cholangitis, primary sclerosing cholangitis [PSC], autoimmune hepatitis [AIH]) can present extrahepatic autoimmune manifestations, the most frequent being inflammatory bowel disease (IBD), autoimmune thyroid disease, and Sjögren syndrome (SS).

METHODS

Retrospective study of patients who have undergone liver transplant (LT) with post-LT follow-up of at least 2 years. Descriptive analysis of clinical variables and overall and graft survival.

RESULTS

ALD was an infrequent indication for LT (68 of 835, 8%), 39 primary biliary cholangitis, 17 AIH, and 12 PSC; 56 were women. The mean (standard deviation [SD]) pre-LT Model for End-Stage Liver Disease score was 17 (5.4). The mean (SD) age of LT recipients at LT was 40 (21) years. A total of 27 patients presented extrahepatic autoimmune diseases. The most frequent was IBD in 7 patients, preferentially in patients with PSC (10/12), followed by Sjögren syndrome and autoimmune thyroid disease. IBD was present in 12 patients: 8 ulcerative colitis (6 PSC and 2 AIH overlap syndrome), 2 Crohn disease both PSC, and another 2 PSC and IBD without conclusive diagnosis (neither for ulcerative colitis nor Crohn disease). Five presented IBD de novo post-LT; the other 7 debuted before LT. In 3 of these 7 patients with pre-LT IBD, the disease went into remission after LT. Colectomy was necessary in 3 patients. No statistically significant findings were found in the survival analysis.

CONCLUSIONS

ALD is an infrequent reason for LT. Extrahepatic autoimmune diseases are associated in these patients, with IBD being the most frequent. IBD presents a torpid course but does not impact overall survival.

Autoimmune Hepatitis and Stellate Cells: An Insight into the Role of Autophagy

Autoimmune hepatitis is a necroinflammatory process of liver, featuring interface hepatitis by T cells, macrophages and plasma cells that invade to periportal parenchyma. In this process, a variety of cytokines are secreted and liver tissues undergo fibrogenesis, resulting in the apoptosis of hepatocytes. Autophagy is a complementary mechanism for restraining intracellular pathogens to which the innate immune system does not provide efficient endocytosis. Hepatocytes with their particular regenerative features are normally in a quiescent state, and, autophagy controls the accumulation of excess products, therefore the liver serves as a basic model for the study of autophagy. Impairment of autophagy in the liver causes the accumulation of damaged organelles, misfolded proteins and exceeded lipids in hepatocytes as seen in metabolic diseases. In this review, we introduce autoimmune hepatitis in association with autophagy signaling. We also discuss some genes and proteins of autophagy, their regulatory roles in the activation of hepatic stellate cells and the importance of lipophagy and tyrosine kinase in hepatic fibrogenesis. In order to provide a comprehensive overview of the regulatory role of autophagy in autoimmune hepatitis, the pathway analysis of autophagy in autoimmune hepatitis is also included in this article.

Examining pathogenic concepts of autoimmune hepatitis for cues to future investigations and interventions

BACKGROUND

Multiple pathogenic mechanisms have been implicated in autoimmune hepatitis, but they have not fully explained susceptibility, triggering events, and maintenance or escalation of the disease. Furthermore, they have not identified a critical defect that can be targeted. The goals of this review are to examine the diverse pathogenic mechanisms that have been considered in autoimmune hepatitis, indicate investigational opportunities to validate their contribution, and suggest interventions that might evolve to modify their impact. English abstracts were identified in PubMed by multiple search terms. Full length articles were selected for review, and secondary and tertiary bibliographies were developed. Genetic and epigenetic factors can affect susceptibility by influencing the expression of immune regulatory genes. Thymic dysfunction, possibly related to deficient production of programmed cell death protein-1, can allow autoreactive T cells to escape deletion, and alterations in the intestinal microbiome may help overcome immune tolerance and affect gender bias. Environmental factors may trigger the disease or induce epigenetic changes in gene function. Molecular mimicry, epitope spread, bystander activation, neo-antigen production, lymphocytic polyspecificity, and disturbances in immune inhibitory mechanisms may maintain or escalate the disease. Interventions that modify epigenetic effects on gene expression, alter intestinal dysbiosis, eliminate deleterious environmental factors, and target critical pathogenic mechanisms are therapeutic possibilities that might reduce risk, individualize management, and improve outcome. In conclusion, diverse pathogenic mechanisms have been implicated in autoimmune hepatitis, and they may identify a critical factor or sequence that can be validated and used to direct future management and preventive strategies.

Chloroquine Is Effective for Maintenance of Remission in Autoimmune Hepatitis: Controlled, Double-Blind, Randomized Trial

Between 50% and 86% of patients with autoimmune hepatitis (AIH) relapse after immunosuppression withdrawal; long-term immunosuppression is associated with increased risk of neoplasias and infections. Chloroquine diphosphate (CQ) is an immunomodulatory drug that reduces the risk of flares in rheumatologic diseases. Our aims were to investigate the efficacy and safety of CQ for maintenance of biochemical remission of AIH in a double-blind randomized trial and to define a subgroup that obtained a greater benefit from its use. A total of 61 patients with AIH in histologic remission (90.1% AIH type 1 [AIH-1]) were randomized to receive CQ 250 mg/day or placebo for 36 months. Of the 61 patients, 31 received CQ and 30 placebo. At baseline, clinical, laboratory, histologic findings, and human leukocyte antigen (HLA) profile were similar between the two groups. Relapse-free survival was significantly higher in the CQ group compared to the placebo group (59.3% and 19.9%, respectively P = 0.039). For those patients completing 3-year treatment, relapse rates were 41.6% and 0% after CQ and placebo withdrawal, respectively. Factors associated with a higher risk of relapse in multiple Cox regression were placebo use (hazard ratio, 2.4; 95% confidence interval [CI], 1.055.5; P = 0.039) and anti-soluble liver antigen/liver-pancreas (anti-SLA/LP) seropositivity (hazard ratio, 5.4; 95% CI, 1.91-15.3; P = 0.002). Although it was not possible to define a subgroup that obtained a greater benefit from CQ according to anti-SLA/LP reactivity or HLA profile, 100% of patients who were anti-SLA/LP-positive (+) relapsed with placebo compared to 50% with CQ (P = 0.055). In the CQ group, 54.8% had side effects and 19.3% interrupted the drug regimen. Conclusion: CQ safely reduced the risk of relapse of AIH, but it was not possible to define a subgroup that obtained a greater benefit with CQ use, probably because of sample size.

Autoimmune Hepatitis in the Liver Transplant Graft

Recurrent autoimmune hepatitis (AIH) and de novo AIH are 2 important causes of late graft failure after liver transplantation (LT). Recurrent AIH occurs in patients who undergo LT for AIH. De novo AIH occurs in patients who are transplanted for etiologies other than AIH. Although typically treated with standard treatment for AIH, including corticosteroids and azathioprine, both recurrent and de novo AIH may progress to end-stage liver disease requiring retransplantation.

Innumerable Liver Masses in a Patient with Autoimmune Hepatitis and Primary Sclerosing Cholangitis Overlap Syndrome

BACKGROUND In patients with the diagnosis of autoimmune hepatitis (AIH), the presence of cholestatic features raise the possibility of an overlap syndrome with primary sclerosing cholangitis (PSC). Here, we present a unique case with AIH-PSC overlap syndrome and innumerable liver masses. CASE REPORT A 26-year-old man presented with generalized icterus. Based on the serological findings of hypergamainmunoglobulinemia and positive anti-nuclear antibody tests, together with an abnormal cholangiogram, he was diagnosed with overlap syndrome (AIH-PSC). Liver imaging revealed innumerable liver masses with a benign appearance in the pathological evaluation. To rule out the colon abnormalities that usually coexist with such liver masses, colonoscopy was performed and showed no significant changes. The liver masses were nonmalignant and were resolved after immunosuppressant therapy. CONCLUSIONS Because AIH-PSC overlap syndrome is rare, it is suggested that radiological evaluation of the biliary tree should be performed routinely in adults diagnosed with AIH to reduce the missed diagnosis of overlap syndrome and liver masses.

Dysfunction of phagocytosis and lysosome activities of intraperitoneal macrophages in autoimmune hepatitis mice

AIM: To evaluate the phagocytic function and lysosome activities of intraperitoneal macrophages in autoimmune hepatitis (AIH) mice.

METHODS: Eighty C57BL/680 mice were divided into an AIH group and a control group. AIH was induced by intraperitoneal injection of liver-specific antigen S-100 and Freund's complete adjuvant. Intraperitoneal macrophages were obtained through peritoneal washing. Macrophages were co-cultured with fluorescein isothiocyanate (FITC) labeled Escherichia coli (E. coli) and lysotracker red. The phagocytic rate/index and lysotracker fluorescence intensities were analyzed by fluorescence microscopy or flow cytometry.

RESULTS: Both the phagocytic rate (24.07% ± 10.21% vs 47.27% ± 15.57%, t = -7.899, P < 0.05) and index (0.36 ± 0.19 vs 0.89 ± 0.34, t = -6.793, P < 0.05) of macrophages from AIH mice were lower than those from control mice. Most of FITC-labeled E. coli bacteria were transported into lysosomes after phagocytosis, which enhanced the activities of lysosomes. No matter before or after co-culture with FITC-labeled E. coli, the activities of lysosome in the AIH group were less than those of control mice (before co-culture: 5.85 ± 0.35 vs 15.39 ± 0.72, t = -5.296, P < 0.05; after co-culture: 9.45 ± 0.84 vs 30.00 ± 1.36, t = -7.889, P < 0.05).

CONCLUSION: The phagocytic and lysosome functions of macrophages in AIH mice are reduced, which may be pathogenic factors in AIH.