Expression of Chitinase-like 3 Protein 1 (CHI3L1) in Buffalo Cumulus-oocyte Complexes during in vitro Maturation

Background: Buffaloes (Bubalus bubalis) are a vital livestock species in South Asia, significantly contributing to milk production and agricultural sustainability. However, reproductive inefficiency remains a significant challenge, adversely impacting productivity. In vitro maturation (IVM) of oocytes is a critical technique for improving reproductive efficiency in buffaloes. Chitinase-3-like Protein 1 (CHI3L1), known for its roles in tissue remodelling and inflammation, has emerged as a potential regulator in reproductive processes. This study investigates the expression of CHI3L1 in buffalo cumulus-oocyte complexes (COCs) during IVM to explore its role in oocyte maturation. Methods: Buffalo ovaries were collected post-slaughter and COCs were retrieved and cultured in TCM 199 medium supplemented with FSH, LH and estradiol. The COCs were classified into immature and mature groups based on morphological criteria after 24 hours of culture. Total RNA was extracted from both groups and CHI3L1 expression was quantified using quantitative real-time PCR (qRT-PCR). Western blot analysis was performed to assess CHI3L1 protein levels in both immature and mature oocytes. Result: The study found a significant upregulation of CHI3L1 expression in mature COCs, with a 3-fold increase compared to immature COCs (p less than 0.05). Western blot analysis confirmed the higher intensity of CHI3L1 protein in mature oocytes, correlating with the qRT-PCR results. These findings suggest that CHI3L1 plays a crucial role in the maturation of buffalo oocytes, potentially through its involvement in tissue remodelling and inflammatory responses within the COCs.