Epigallocatechin gallate (EGCG) protects against aluminum-induced bone damage via NLRP3 inflammasome modulation.

Environmental aluminum (Al) exposure is increasing, posing a significant risk to bone health by inhibiting bone formation and contributing to osteoporosis. Current interventions often fall short in preventing this specific type of damage. Epigallocatechin gallate (EGCG), a major green tea polyphenol, has shown promise for bone health, but its therapeutic potential against Al-induced bone damage, particularly through the NLRP3 inflammasome pathway, remains largely unexplored. This pathway is a critical mediator of inflammation and has been implicated in various bone diseases.

To investigate EGCG's role, rats were exposed to AlCl₃ to induce bone damage, then treated with EGCG at different doses. Researchers assessed bone and serum mineral levels using biochemical analyses. Relative mRNA expression levels of NLRP3, caspase-1, IL-1β, OPN, and OCN in bone tissue were quantified by RT-PCR analysis. Bone IL-1β levels were also determined using ELISA to confirm inflammatory responses.

Exposure to AlCl₃ significantly increased aluminum accumulation and serum Ca levels in rat bones, while simultaneously decreasing bone Ca levels. This Al exposure also induced substantial bone damage, primarily through the activation of the NLRP3/caspase-1/IL-1β pathway. Treatment with EGCG resulted in a dose-dependent recovery across these parameters. Specifically, AlCl₃ exposure significantly increased OPN mRNA expression, a marker of osteoclast activity, while OCN mRNA expression, a marker of osteoblast activity, showed a non-significant decreasing tendency. > EGCG treatment was associated with reduced OPN mRNA expression and a tendency toward increased OCN mRNA expression, indicating a shift towards improved bone remodeling. These findings strongly suggest that EGCG's protective effects are mediated by its modulation of the NLRP3 inflammasome pathway.