Cyclophilin C (CypC/PPIC) is a peptidyl-prolyl cis-trans isomerase that supports protein folding in the endoplasmic reticulum and binds cyclosporin A
[1][2]. Mechanistically, CypC acts with cyclophilin B in ER redox homeostasis, because combined depletion altered transferrin secretion, albumin oxidative folding, protein-disulfide isomerase oxidation, and oxidized glutathione balance
[2]. In an HCMV immune-evasion model, CypC co-isolated with US2 and HLA-A2, and either depletion or overexpression impaired US2-mediated MHC class I degradation
[3]. Compared with related isoforms, extracellular CypA and CypC increased IL-6, MCP-1, CD147, and NF-κB-p65 activation in pancreatic microendothelial cells, whereas extracellular CypB did not affect these pro-inflammatory markers
[4]. For experimental applications, cyclosporin A binds CypC, reversed extracellular CypC-driven endothelial responses, and induced ER depletion of cyclophilins B and C in redox studies
[1][2][4]. Serum CypC was also associated with coronary artery disease risk, supporting its use as a biomarker candidate rather than a validated therapeutic target
[5].