PPIC (peptidylprolyl isomerase C) is a peptidyl-prolyl cis-trans isomerase that catalyzes protein folding by facilitating the isomerization of proline residues in peptide bonds 1. The protein functions as a molecular chaperone, with all cyclophilin family members, including PPIC, demonstrating the ability to prevent tau aggregation in vitro, with PPIC showing particularly strong inhibitory effects 1. In cellular models, PPIC reduces both soluble and insoluble tau levels and uniquely protects cells from tau seeding, suggesting neuroprotective potential in tauopathies 1. However, PPIC also exhibits pathological roles in multiple diseases. In hepatic fibrosis, PPIC expression is upregulated and promotes hepatic stellate cell activation and extracellular matrix deposition, with knockdown significantly improving liver damage in mouse models 2. PPIC expression is regulated by miR-137-3p, forming a regulatory axis that modulates hepatic fibrosis progression 2. In cancer contexts, PPIC serves as a prognostic biomarker, with upregulation associated with poor outcomes in high-grade gliomas 3 and cutaneous melanoma, where it promotes tumor progression and drug resistance while suppressing CD8+ T cell activation 4. PPIC is also identified as a key predictive gene in idiopathic pulmonary fibrosis, potentially co-regulating NOTCH and autophagy pathways 5.