ITIH5 (inter-alpha-trypsin inhibitor heavy chain 5) is an extracellular matrix protein with diverse regulatory functions across multiple physiological and pathological contexts. As a tumor suppressor, ITIH5 expression is frequently decreased in various cancers including melanoma, bladder cancer, and pancreatic ductal adenocarcinoma, where its loss correlates with poor prognosis and enhanced metastatic potential 123. The protein functions through multiple mechanisms: in melanoma, p53 directly promotes ITIH5 transcription, which then inhibits cell growth and metastasis by downregulating KLF4 transcriptional activity 1. Notably, ITIH5's metastasis suppression can occur through intracellular mechanisms independent of secretion 3. Beyond cancer, ITIH5 plays important roles in cardiovascular and metabolic health. In myocardial infarction, ITIH5 promotes cardiac fibrotic remodeling by enhancing fibroblast-macrophage interactions through hyaluronan stabilization and CD44 receptor binding, ultimately activating STAT3 signaling pathways 4. In adipose tissue, ITIH5 acts as a homeostatic regulator, inhibiting proliferation and differentiation of adipose stem cells while reducing inflammatory cytokine secretion 5. The protein also shows promise as a diagnostic biomarker for ischemic cardiomyopathy and early-onset Alzheimer's disease 46.