Enhanced antigen cross-presentation in human colorectal cancer-associated fibroblasts through upregulation of the lysosomal protease Cathepsin S
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ABSTRACT: Cross-presentation of exogenous antigens in HLA-class I molecules by professional antigen presenting cells (APCs) is crucial for CD8+ T cell function. Recent murine studies show that several non-professional APCs, including cancer-associated fibroblasts (CAFs) also possess this capacity. It is currently unknown whether human CAFs are able to cross-present exogenous antigen, which molecular pathways are involved in this process and how this ultimately affects tumor-specific CD8+ T cell function. Here we show that human colorectal cancer (CRC)-derived CAFs display an enhanced capacity to cross-present neoantigen-derived synthetic long peptides (SLPs) when compared to normal colonic fibroblasts. Importantly, cross-presentation of antigens required the lysosomal protease Cathepsin S. Cathepsin S expression by CAFs was detected in situ in human CRC tissue, was upregulated in ex vivo cultured CRC-derived CAFs and showed increased expression in normal fibroblasts after exposure to CRC-conditioned medium. Cognate interaction between CD8+ T cells and cross-presenting CAFs suppressed T cell function, reflected by decreased cytotoxicity, reduced activation (CD25, CD137) and increased exhaustion (TIM3) marker expression. Our data indicate that CAFs may directly suppress tumor-specific T cell function in an antigen-dependent fashion in human CRC.
INSTRUMENT(S): Orbitrap Fusion Lumos
ORGANISM(S): Homo Sapiens (human)
TISSUE(S): Cell Culture
SUBMITTER: G Janssen
LAB HEAD: P.A. van Veelen
PROVIDER: PXD029507 | Pride | 2022-03-03
REPOSITORIES: Pride
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