Studies on blocking the JAK2/STAT3 signaling pathway with elastin peptides from skipjack tuna (Katsuwonus pelamis) bulbus cordis to alleviate osteoarthritis

Osteoarthritis (OA) is a chronic disease associated with bone and muscle degeneration that causes great disturbances to daily lives. Skipjack tuna elastin peptides (STEP) is a kind of small molecule mixed peptides extracted from skipjack tuna bulbus cordis that have multiple active functions, including anti-inflammatory activity. However, it is ambiguous whether STEP reduce OA inflammation. Zebrafish served as a model in the present research for verifying the anti-inflammatory efficacy of STEP. Then, the composition of STEP was figured out by LC-MS/MS analysis, and the potential anti-inflammatory peptides were screened by molecular docking and microscale thermophoresis (MST). Finally, in vitro experiments were conducted on the potential peptides. According to the in vivo findings, STEP protected the cartilage tissues of zebrafish and regulated the expression of inflammatory factors and the JAK2/STAT3 signaling pathway. The in vitro results showed that the potential peptides (LGVGSPPGK, GFDPSR and PGAPGGGFDI) positively regulated the inflammatory responses and the JAK2/STAT3 signaling pathway and were effective in inhibiting extracellular matrix (ECM) degeneration and chondrocyte apoptosis. As a consequence, STEP possess anti-inflammatory and chondroprotective effects and could be a functional product for the alleviation of OA.