Gut and liver T-cells of common clonal origin in primary sclerosing cholangitis-inflammatory bowel disease

Background & Aims: Recruitment of gut-derived memory T-cells to the liver is believed to drive hepatic inflammation in primary sclerosing cholangitis (PSC). However, whether gut-infiltrating and liver-infiltrating T-cells share T cell receptors (TCRs) and antigenic specificities is unknown. We used paired gut and liver samples from PSC patients with concurrent inflammatory bowel disease (PSC-IBD), and normal tissue samples from colon cancer controls, to assess potential T cell clonotype overlap between the two compartments. Methods: High-throughput sequencing of TCR beta repertoires was applied on matched colon, liver and blood samples from patients with PSC-IBD (n = 10), and on paired tumor-adjacent normal gut and liver tissue samples from colon cancer patients (n = 10). Results: An average of 9.7% (range: 4.7-19.9%) memory T cell clonotypes overlapped in paired PSC-IBD affected gut and liver samples, after excluding clonotypes present at similar frequencies in blood. Shared clonotypes constituted on average 16.0% (range: 8.7-32.6%) and 15.0% (range: 5.9-26.3%) of the liver and gut memory T-cells, respectively. A significantly higher over lap was observed between paired PSC-IBD affected samples (8.7%, p = 0.0007) compared to paired normal gut and liver samples (3.6%), after downsampling to equal number of reads. Conclusion: Memory T-cells of common clonal origin were detected in paired gut and liver samples of patients with PSCIBD. Our data indicate that this is related to PSC-IBD pathogenesis, suggesting that memory T-cells driven by shared antigens are present in the gut and liver of PSC-IBD patients. Our findings support efforts to therapeutically target memory T cell recruitment in PSC-IBD. Lay summary: Primary sclerosing cholangitis (PSC) is a devastating liver disease strongly associated with inflammatory bowel disease (IBD). The cause of PSC is unknown, but it has been suggested that the immune reactions in the gut and the liver are connected. Our data demonstrate for the first time that a proportion of the T-cells in the gut and the liver react to similar triggers, and that this proportion is particularly high in patients with PSC and IBD. (C) 2016 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.