It is time to change primary biliary cirrhosis (PBC): New nomenclature from "cirrhosis" to "cholangitis", and upcoming treatment based on unveiling pathology

Animal models of primary biliary cholangitis: status and challenges

BACKGROUND

Primary biliary cholangitis (PBC) is an autoimmune liver disease. The aetiology of PBC remains unclear, and its pathogenesis is complex. Animal models are essential to clarify the pathogenesis of PBC and explore the occurrence of early events.

MAIN BODY

Herein, we review recent research progress in PBC animal models, including genetically modified, chemically inducible, biologically inducible, and protein-immunised models. Although these animal models exhibit several immunological and pathological features of PBC, they all have limitations that constrain further research and weaken their connection with clinical practice.

CONCLUSION

The review will benefit efforts to understand and optimise animal models in order to further clarify PBC pathogenesis and molecular targets for therapeutic interventions.

Endothelin receptor B enhances liver injury and pro-inflammatory responses by increasing G-protein-coupled receptor kinase-2 expression in primary biliary cholangitis

Severe diseases like cirrhosis and liver failure can be developed from primary biliary cholangitis (PBC). Endothelin-2 (EDN2) and endothelin receptor B (EDNRB) are related to the pathogenesis of PBC. However, the roles of EDN2 and EDNRB in PBC-related liver injury and inflammation along with molecular mechanisms are poorly defined. In this study, histopathologic alterations of liver tissues were assessed through hematoxylin-eosin staining. Alanine transaminase (ALT), alkaline phosphatase (ALP), aspartate transaminase (AST), and γ-Glutamyltranspetidase (GGT) (4 liver function indexes) serum levels were detected with corresponding activity assay kits. Also, we determined the levels of M2 subtype anti-mitochondrial antibody (AMA-M2), interferon-gamma (IFN-γ), and tumor-necrosis factor alpha (TNFα) in serum with ELISA assay. Later, RT-qPCR assay was used to measure the expression of genes at mRNA levels, while western blotting and immunohistochemical techniques were used to detect protein levels of genes. Our results showed that the liver tissues of PBC patients and mice presented with severe hepatocyte injury and inflammatory cell infiltration as well as destruction of intrahepatic small bile ducts. ALP, AST, ALT, GGT, AMA-M2, IFN-γ, and TNF-α serum levels were higher in PBC patients and mice. Besides, EDN2 and EDNRB were highly expressed in serums and livers of PBC patients and mice. EDNRB potentiated PBC-related liver injury and pro-inflammatory responses, as evidenced by observation of serious liver pathologic injury and increased serum levels of ALP, AST, ALT, AMA-M2, IFN-γ, and TNF-α in PBC mice following EDNRB overexpression. EDNRB overexpression or activation via its agonist IRL-1620 TFA triggered liver injury and pro-inflammatory responses, increased GRK2 expression and induced NF-κB expression and activation in wild-type mice. EDNRB knockdown or inhibition by Bosentan alleviated liver damage and inflammation, reduced GRK2 expression, and inhibited NF-κB in PBC mice. These findings suggested EDNRB loss or inhibition weakened liver injury and pro-inflammatory responses by down-regulating GRK2 and inhibiting the NF-κB pathway in PBC mice.

Galectin-3 in Inflammasome Activation and Primary Biliary Cholangitis Development

Primary biliary cholangitis (PBC) is a chronic inflammatory autoimmune liver disease characterized by inflammation and damage of small bile ducts. The NLRP3 inflammasome is a multimeric complex of proteins that after activation with various stimuli initiates an inflammatory process. Increasing data obtained from animal studies implicate the role of NLRP3 inflammasome in the pathogenesis of various diseases. Galectin-3 is a β-galactoside-binding lectin that plays important roles in various biological processes including cell proliferation, differentiation, transformation and apoptosis, pre-mRNA splicing, inflammation, fibrosis and host defense. The multilineage immune response at various stages of PBC development includes the involvement of Gal-3 in the pathogenesis of this disease. The role of Galectin-3 in the specific binding to NLRP3, and inflammasome activation in models of primary biliary cholangitis has been recently described. This review provides a brief pathogenesis of PBC and discusses the current knowledge about the role of Gal-3 in NLRP3 activation and PBC development.

Risk factors for recurrence of primary biliary cholangitis after liver transplantation in female patients: A Japanese multicenter retrospective study

Primary biliary cholangitis (PBC) is diagnosed mainly in female individuals, and risk factors for PBC recurrence (rPBC) after liver transplantation (LT) from cadaveric donors have been reported. We conducted a retrospective multicenter study of rPBC in female patients after living‐donor LT (LDLT). A total of 388 female patients undergoing LDLT for end‐stage PBC were enrolled, and the effects of preoperative and operative factors were evaluated. Postoperative factors were evaluated in 312 patients who survived for more than 1 year post‐LDLT. rPBC was defined as abnormal hepatic enzyme levels with typical histological findings in liver biopsies. Fifty‐eight patients (14.9%) developed rPBC with a median of 4.6 (0.8‐14.5) years post‐LT. Cox hazard analysis (P < 0.05) showed that younger recipient age (hazard ratio, 0.95; 95% confidence interval, 0.920‐0.982), shorter operative time (1.00; 0.995‐0.999), higher serum immunoglobulin M level (1.00; 1.001‐1.002), donor sex mismatch (2.45; 1.268‐4.736), human leukocyte antigen B60 (2.56; 1.336‐4.921) and DR8 (1.98; 1.134‐3.448), and initial treatment with cyclosporine A (3.14; 1.602‐6.138) were significantly associated with rPBC. The frequencies of Child‐Turcotte‐Pugh class C (0.46; 0.274‐0.775), the model of end‐stage liver disease score (0.96; 0.914‐0.998), and updated Mayo risk score (1.02; 1.005‐1.033) were significantly lower in rPBC. Posttransplantation use of steroids decreased and that of antimetabolites increased the frequency of rPBC. Conclusion: The timing of LT, recipient conditions, donor characteristics, and immunosuppressive medications may be associated with rPBC in LT recipients. (Hepatology Communications 2017;1:394–405)

Distinctive HLA-II association with primary biliary cholangitis on the Island of Sardinia

BACKGROUND

The HLA DRB1*08 allele associated with primary biliary cholangitis (PBC) among Caucasians is of low frequency in the Sardinian population.

OBJECTIVE

The aim of our study was to type a cohort of PBC patients from the island of Sardinia for HLA class II antigens.

METHODS

Twenty Sardinian patients affected by PBC, 14 with autoimmune hepatitis (AIH) and 89 healthy controls (HCs) were typed for HLA class II alleles by dot-blot analysis.

RESULTS

The PBC-associated HLA DRB1*08 allele was detected in none of the studied individuals. The DRB1*0301-DQB1*0201 was the prevalent HLA haplotype, detected in 19 (47.5%) out of 40 PBC haplotypes (OR = 3.0; 95% CI 1.5-6.2) and in 11 (39.3%) out of 28 AIH haplotypes (OR = 2.2; 95% CI 0.94-5.0), but in only 41 (23%) out of 178 HC haplotypes. Moreover, PBC patients showed an increased frequency of homozygosity for the DQB1*0201 allele (35% compared with 6.7% of the HCs; OR = 7.5; 95% CI 2.2-25.7). The frequency of the DRB1*11 allele in the PBC group was about half of that seen in the Sardinian HCs (7.5% vs 15.7%) (p = ns).

CONCLUSIONS

Our study confirmed the low frequency of the HLA DRB1*08 allele among Sardinians, either in the general population or PBC patients. The high prevalence of the HLA DRB1*0301-DQB1*0201 haplotype is a distinctive genetic feature of PBC among Sardinians. Our study strengthens the hypothesis that still unknown genetic, epigenetic, and environmental factors must be involved in the pathogenesis of different HLA-associated liver diseases, and it represents a pathfinder that warrants exploration in a future extensive study.