Antler base (Cervus nippon Temminck) peptides modulate the NLRP3 inflammatory pyroptosis and Nrf2/HO-1/NQO1 signaling pathways to ameliorate osteoarthritis: a structural and mechanistic study.

ETHNOPHARMACOLOGICAL RELEVANCE: Antler base (Cervus nippon Temminck), a traditional Chinese medicine, is categorized as deer antler. Antler base extracts can delay osteoarthritis (OA); however, the underlying molecular pathways and effective substances remain unclear.

AIM OF THE STUDY: to clarify the potential mechanism of action and effective substance structure of Cervus nippon Temminck antler base peptides (CNCPs) in improving OA.

MATERIALS AND METHODS: The physicochemical properties, including functional groups, amino acid composition, and molecular weight of CNCPs were characterized using FTIR and HPLC. The protective effect and potential mechanism of action of CNCPs in a papain-induced OA rat model were investigated through histopathological examinations, Elisa kit, western boltting, qRT-PCR, and immunofluorescence. CNCPs were isolated and purified using SephadexG-15, and the purified fractions were screened for bioactivity by IL-1β-induced in vitro model, and LC-MS/MS identified the component with the best activity.

RESULTS: CNCPs significantly alleviated the superficial cartilage erosion, protected cartilage surface integrity, regulated OA-related phenotypic proteins expression, and modulated the serum levels of related pro-inflammatory cytokines and oxidative stress-related factors in OA rats. CNCPs inhibited the activation of the NLRP3 inflammatory pyroptosis pathway triggered and upregulated the Nrf2 pathway. The best active fraction, CNCPs-III, contained a notable amount of hydrophobic amino acid residues, including AGPAGA, VGPV, and LLGDV, and had a molecular mass of <1.5 kDa.

CONCLUSIONS: CNCPs improve OA-induce inflammation and oxidative stress induced with OA by regulating the NLRP3 inflammatory pyroptosis and Nrf2/HO-1/NQO1 signaling pathways, thereby delaying OA progression.