iTRAQ-Based Proteomic Analysis of Spontaneous Achilles Tendon Rupture.

Spontaneous Achilles tendon rupture (SATR) predominantly affects middle-aged and elderly individuals with chronic injuries. However, the exact cause and mechanism of SATR remain elusive, and potential therapeutic intervention or prevention is still insufficient. The present study aimed to uncover the key pathological molecules by using iTRAQ proteomics. The results identified 2432 candidate proteins in SATR patients using iTRAQ proteomic analysis. A total of 307 differentially expressed proteins (DEPs) were identified and linked to 211 KEGG signaling pathways including Coronavirus disease (COVID-19), focal adhesion, and ribosomes. GO enrichment analysis highlighted significant enrichment in processes such as biological adhesion, ossification, lipid (APOA4) processes, and extracellular matrix (ECM) organization (collagen). PPI network analysis identified hub genes such as serum albumin (ALB), fibronectin (FN1), and actin cytoplasmic 1. The WB analysis confirmed that FN1 and the receptor for activated C kinase (RACK1) were downregulated in the SATR tendon. Immunohistochemical staining revealed that collagen I and III were suppressed, while collagen II and APOA4 expression were higher in the SATR pathological tissue (P < 0.05). However, the primary cultured tenocytes (PCTs) from SATR patients showed enhanced proliferation and, consistent with tissue staining, reduced collagen I and III and increased collagen II. Our findings reveal vital targets and pathways in SATR's etiological progression, offering a new perspective on the diagnosis, treatment, and prognosis of this complex disorder.