Autoantibodes to GP210 are a metric for UDCA responses in primary biliary cholangitis.

Objectives: Antibodies to gp210 and sp100 are specific and unique anti-nuclear autoantibodies (ANAs) associated with primary biliary cholangitis (PBC). Importantly the presence of anti-gp210 and anti-sp100 responses is indicative of poor clinical outcomes. However, the utility of measuring titers of these antibodies remains unclear. Materials and methods: Using the in-house purified gp210 (HSA108-C18) and sp100 (amino acid position 296-386), we quantitatively measured serum autoantibodies to gp210 and sp100 using chemiluminescence immunoassay (CLIA) in a very large cohort of 390 patients with PBC, including 259 cases with no prior ursodesoxycholic acid (UDCA) treatment and 131 cases with UDCA treatment. We also analyzed serial changes in anti-gp210 and anti-sp100 levels in 245 sequential samples from 88 patients. Results: In our cross-sectional analysis, we detected anti-gp210 immunoglobulin G (IgG) and anti-sp100 IgG autoantibodies in 129 out of 390 (33.1%) and 80 out of 390 (20.5%) PBC patients, respectively. Multivariate analysis revealed that serum IgG (st.ß = 0.35, P = 0.003) and gamma-glutamyltransferase (GGT) (st.ß = 0.23, P = 0.042) levels at baseline were independently associated with anti-gp210 concentrations. In serial testing, we observed significant fluctuations in anti-gp210 antibody levels. These fluctuations reflected responsiveness to UDCA therapy, particularly in anti-gp210-positive patients with initially lower concentrations in the stages of disease. Conclusions: Our study reflects that quantitative changes of anti-gp210 antibody are indicative of UDCA responses. There is a great need for newer metrics in PBC and we suggest that a more detailed and longer study of these unique ANAs is warranted.

Association of CCR6 functional polymorphisms with Primary Biliary Cholangitis.

The biliary epithelial cells release CC chemokine receptor 6 (CCR6) ligand 20 (CCL20), leading to recruitment of CCR6+ T cells and subsequent infiltration into the biliary epithelium in primary biliary cholangitis patients. Previous genome-wide multi-national meta-analysis, including our Han Chinese cohort, showed significant association of CCR6 and CCL20 single nucleotide polymorphisms (SNP) with PBC. We report here that significantly associated SNPs, identified in the CCR6 locus based on our Han Chinese genome-wide association study, can be separated into "protective" and "risk" groups, but only "risk" SNPs were confirmed using a separate Han Chinese PBC cohort. Only weak association of CCL20 SNPs was observed in Han Chinese PBC cohorts. Fine-mapping and logistical analysis identified a previously defined functional variant that, leads to increased CCR6 expression, which contributed to increased genetic susceptibility to PBC in Han Chinese cohort.