Weissella confusa WiKim51 (Wilac D001) fermented mycelium extract attenuates joint inflammation through PGE2 regulation in collagen-induced arthritis rats

Rheumatoid arthritis (RA) is the state of joint inflammation, leading to cartilage and bone destruction. During rheumatoid arthritis progression, cyclooxygenase (COX) activity and its downstream production of prostaglandin E2 (PGE2) contribute to bone and cartilage erosion. WCF-ME was selected because its anti-inflammatory properties were confirmed <italic>in vitro</italic>. Therefore, this study aimed to evaluate the joint inflammation regulating capacities of <italic>Weissella confusa</italic> WiKim51 (Wilac D001) (WC), mycelium extract (ME), and WC-fermented ME (WCF-ME). In a collagen-induced arthritis (CIA) model, CIA-induced serum TNFα was normalized by WCF-ME treatment, while PGE2 was reduced by WC and WCF-ME treatment. ME had no effect in both serum markers. CIA-induced paw swelling and deformation was significantly lowered by WC and WCF-ME from the 21^st day after immunization, while ME had no effect. Furthermore, knee joint gene expressions of <italic>Il6</italic> and <italic>Mmp3</italic> gene expressions were normalized by all treatments, while <italic>Il1b</italic> gene expression was normalized only in the WC group. <italic>Mmp13</italic> gene expressions were normalized by WC and WCF-ME, while ME had no significant difference. Spearman’s correlation analysis showed that serum PGE2 was proportional to <italic>Il6</italic>, <italic>Il1b</italic>, and <italic>Mmp13</italic>. Overall, these results indicate that WC and WCF-ME ameliorated CIA-induced RA symptoms through inhibition of PGE2 activity, leading to reduced <italic>Il6</italic>, <italic>Mmp3</italic>, and <italic>Mmp13</italic> expressions in the knee. Therefore, WC and WCF-ME has potential as a novel RA treatment.