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Many patients with primary biliary cholangitis have an inadequate response to first-line therapy with ursodeoxycholic acid. Seladelpar is a potent, selective agonist for the peroxisome proliferator-activated receptor-delta (PPAR-δ), which is implicated in bile acid homoeostasis. This first-in-class study evaluated the anti-cholestatic effects and safety of seladelpar in patients with an inadequate response to ursodeoxycholic acid.

Idiosyncratic drug-induced liver injury (DILI) from prescription medications and herbal and dietary supplements has an annual incidence rate of approximately 20 cases per 100,000 per year. However, the risk of DILI varies greatly according to the drug. In the United States and Europe, antimicrobials are the commonest implicated agents, with amoxicillin/clavulanate the most common, whereas in Asian countries, herbal and dietary supplements predominate. Genetic analysis of DILI is currently limited, but multiple polymorphisms of human leukocyte antigen genes and genes involved in drug metabolism and transport have been identified as risk factors for DILI.

Primary sclerosing cholangitis (PSC) is a rare progressive disorder leading to bile duct destruction; ∼75% of patients have comorbid inflammatory bowel disease (IBD). We undertook the largest genome-wide association study of PSC (4,796 cases and 19,955 population controls) and identified four new genome-wide significant loci. The most associated SNP at one locus affects splicing and expression of UBASH3A, with the protective allele (C) predicted to cause nonstop-mediated mRNA decay and lower expression of UBASH3A. Further analyses based on common variants suggested that the genome-wide genetic correlation (rG) between PSC and ulcerative colitis (UC) (rG= 0.29) was significantly greater than that between PSC and Crohn's disease (CD) (rG= 0.04) (P = 2.55 × 10−15). UC and CD were genetically more similar to each other (rG= 0.56) than either was to PSC (P < 1.0 × 10−15). Our study represents a substantial advance in understanding of the genetics of PSC.

In the present study, we demonstrate that a human homologue of Ufd2p (a yeast protein that catalyses the formation of long polyubiquitin chains, and is implicated in responses to environmental stress), UFD2 (ubiquitin fusion degradation protein-2), is cleaved during apoptosis induced by multiple stimuli, including UVB irradiation, Fas ligation, staurosporine treatment and cytotoxic lymphocyte granule-induced death. Caspase 6 and granzyme B efficiently cleave UFD2 [kcat/Km = (4–5)×104 M−1·s−1] at Asp123, whereas caspases 3 and 7 cleave UFD2 approx. 10-fold less efficiently immediately upstream at Asp109. Thus UFD2 is added to the growing list of proteins with closely spaced caspase and granzyme B cleavage sites, suggesting the presence of a previously unrecognized, conserved motif. Both cleavage sites are contained and conserved within a novel 300-amino-acid N-terminal domain present in apparent UFD2 orthologues in mice and zebrafish, but absent in all UFD2 family members in lower eukaryotes. Full-length recombinant UFD2 exhibited ubiquitin—protein ligase ('E3')-like ubiquitination activity in vitro, but this activity was abolished in recombinant UFD2 truncated at the granzyme B/caspase 6 cleavage site. Cleavage of UFD2 by caspases or granzyme B within this putative regulatory N-terminal domain might have important functional consequences within the apoptotic cascade.

The lateral mobility of membrane proteins can reflect the extent of various protein-protein interactions. Using the fluorescence recovery after photobleaching technique, we have studied the lateral mobility of human FcγRIIa and some FcγRIIa mutants expressed in either P388D1 cells, a mouse macrophagelike cell line, or in Chinese hamster ovary (CHO) cells [1]. After treatment with phorbol myristate acetate (PMA), only the FcγRIIa molecules capable of mediating rapid endocytosis of immune complexes exhibited a reduced lateral diffusion coefficient with respect to untreated controls. Wild type FcγRIIa expressed in CHO cells, and nonfunctional FcγRIIa mutants expressed in P388D1 cells did not show any differences upon PMA treatment. This finding suggests that protein kinase C activation evokes additional protein-protein interactions with the cytoplasmic domain of functional FcγRIIa, which reduced receptor lateral mobility. The identity of these putative interacting proteins and the nature of the interactions remain to be elucidated.

The lateral mobility of membrane proteins can reflect the extent of various protein‐protein interactions. Using the fluorescence recovery after photobleaching technique, we have studied the lateral mobility of human FcγRIIa and some FcγRIIa mutants expressed in either P388D1 cells, a mouse macrophagelike cell line, or in Chinese hamster ovary (CHO) cells [1]. After treatment with phorbol myristate acetate (PMA), only the FcγRIIa molecules capable of mediating rapid endocytosis of immune complexes exhibited a reduced lateral diffusion coefficient with respect to untreated controls. Wild type FcγRIIa expressed in CHO cells, and nonfunctional FcγRIIa mutants expressed in P388D1 cells did not show any differences upon PMA treatment. This finding suggests that protein kinase C activation evokes additional protein‐protein interactions with the cytoplasmic domain of functional FcγRIIa, which reduced receptor lateral mobility. The identity of these putative interacting proteins and the nature of the interactions remain to be elucidated.

Primary biliary cirrhosis (PBC) is an autoimmune disease characterized by intrahepatic bile duct destruction and the production of anti-mitochondrial antibodies (AMA). The absence of an animal model has been a striking impedance in defining the molecular basis of disease. Previous work has suggested that SJL/J mice immunize with the pyruvate dehydrogenase complex (PDC-E2), the major mitochondrial autoantigen of PBC, leads to the development of lymphoid cell infiltration in portal tracts and a model system coined autoimmune cholangitis. We hypothesized that this pathology would be augmented if immunization occurred in the presence of IFN-γ injections. Accordingly, SJL/J mice were immunized with PDC-E2 and, for purpose of control, α-casein. Subgroups of mice were also treated with exogenous IFN-γ. As expected, mice immunized with PDC-E2, with or without IFN-γ, developed high titer AMAs. In contrast, mice immunized with α-casein, develop antinuclear antibodies. More importantly, the livers from mice immunized with PDC-E2 and/or those immunized with α-casein all displayed lymphoid cell infiltration to the portal tracts, irrespective of bile duct size. Indeed, there was no significant difference between the experimental and the control groups by histologic analysis. Thus, autoimmune cholangitis in these mice is antigen non-specific.