Prevalence and clinical significance of portal inflammation, portal plasma cells, interface hepatitis and biliary injury in liver biopsies from patients with non-alcoholic steatohepatitis.

The significance of portal tract histological changes in non-alcoholic fatty liver disease (NAFLD) remains unclear. In 2019, CymaBay Therapeutics halted clinical trials of seladelpar (a PPARδ agonist) because initial end-of-treatment liver biopsies of patients with non-alcoholic steatohepatitis (NASH) showed concerning features of portal inflammation with plasma cells, interface hepatitis and focal bile duct abnormalities. Adjudication concluded that these findings were present in the initial, as well as the subsequent biopsies. Thus, this study's aim was to determine the prevalence and clinical significance of portal inflammation, portal plasma cells, interface hepatitis and features of bile duct damage in liver biopsies of adult patients with NAFLD. The pathology database was searched for cases of NAFLD, including steatosis alone and NASH, from January 2016 to October 2020. Liver biopsies were selected from age and sex matched adult patients with diagnoses of steatosis alone (n=10), NASH fibrosis stage 1 (n=10), stage 2 (n=10), stage 3 (n=10), and stage 4 (n=10). There were 24 males and 26 females with a mean age of 48 years (range 20-79). Exclusion criteria included age <18 years, daily alcohol intake >14 drinks per week, elevation of alkaline phosphatase level, comorbid chronic liver disease, or liver biopsy performed as part of a clinical trial for NASH. Control liver biopsies were selected from age and sex matched persons without significant steatosis and normal liver biochemical tests (n=10). Histological parameters were evaluated in 10 portal tracts or 10 septal areas in each liver biopsy. Portal inflammation and interface hepatitis were graded on a scale of 0-4. Portal plasma cells and bile duct damage were scored from 0-3. Ductular proliferation was assessed by CK7 immunostain and graded from 0-4. NASH biopsies with advanced fibrosis (stage 3 and 4) showed portal inflammatory infiltrates (score 2-3) with readily identifiable plasma cells (score 2), and mild to moderate interface hepatitis (score 2-3). All cases and controls showed focal, mild cholangiocyte changes, characterised by cytoplasmic vacuolation, segmental loss of nuclei, nuclear disarray and apoptosis. NASH patients with advanced fibrosis had frequent and diffuse cholangiocyte changes, along with focal lymphocytic cholangitis and moderate to marked ductular reaction (score 3-4). Histopathological features of advanced NASH frequently include increased portal inflammation with plasma cells, interface hepatitis, cholangiocyte injury and prominent ductular reaction.