Response of cartilage explants to LPS cultured in normoxic and hypoxic conditions is modulated by Spirulina: implications for exercise recovery in vivo

Exercise-induced inflammation and free radical production are crucial for recovery, yet excess inflammation poses risks to equine athletes, leading to conditions like arthritis. Spirulina, recognized for its antioxidant and anti-inflammatory properties, could mitigate degenerative diseases without hindering post-exercise recovery. This study investigates Spirulina's direct impact on cartilage responses to LPS-induced inflammation in normoxic and hypoxic conditions, focusing on outcomes relevant to cartilage matrix turnover and exercise-induced inflammation. Spirulina underwent simulated digestion and liver metabolism, yielding a simulated biological extract (SP_sim). In the normoxic experiment, porcine cartilage explants were cultured with SP_sim (0, 30, or 90 μg/mL) for 72 h after 24 h in basal media, with LPS (0 or 10 μg/mL) added for the final 48 h. The hypoxic experiment mirrored this, with explants transferred to a hypoxia chamber for the final 48 h. Media samples collected at 0, 24, and 48 h were analyzed for biomarkers related to cartilage turnover (GAG), and exercise-induced inflammation (IL-6 and NO). Cell viability, assessed by live:dead staining, remained > 97% and unaffected by oxygen tension. In normoxic conditions, SP_sim (30 μg/mL) significantly reduced GAG release at 48 h. Under hypoxia, SP_sim (30 and 90 μg/mL) inhibited LPS-induced GAG release. SP_sim (90 μg/mL) increased IL-6 and NO production in LPS-stimulated explants in normoxia, and a similar effect was observed with the lower SP_sim dose (30 μg/mL) in hypoxic conditions. These results suggest that Spirulina may enhance cartilage mediators, potentially promoting healthy cartilage turnover during exercise recovery.