IL-6 promotes PD-L1 expression in monocytes and macrophages by decreasing protein tyrosine phosphatase receptor type O expression in human hepatocellular carcinoma

Research Overview

This group had previously linked low expression of protein tyrosine phosphatase receptor type O (PTPRO) in tumor-infiltrating T cells to immunosuppression. Here they asked whether decreased PTPRO is tied to increased programmed death ligand 1 (PD-L1) in peripheral monocytes and tumor-infiltrating macrophages of human hepatocellular carcinoma (HCC).

Expression and correlation of these markers were examined in monocytes and tumor-associated macrophages from both human and mouse HCC, with mechanisms probed in vitro and in vivo. PTPRO was significantly decreased in HCC peripheral monocytes, and that decrease was associated with increased PD-L1 expression in both peripheral monocytes and tumor-associated macrophages.