SIRT5 desuccinylates PRDX3 to promote its chaperone-mediated autophagy and mitigate mitochondrial dysfunction in MSU crystal-induced inflammation

Background: Gout is triggered by monosodium urate (MSU) crystals and is closely linked to mitochondrial dysfunction and oxidative stress. However, the role of the desuccinylase SIRT5 in this process remains unclear. Here, we identify SIRT5 as a key negative regulator of MSU crystal-induced inflammation.

Methods: Macrophages were challenged with MSU crystals to assess mitochondrial membrane potential (ΔΨm), Reactive Oxygen Species (ROS), and IL-1β secretion. The interaction between SIRT5 and PRDX3, as well as PRDX3 succinylation, was examined by co-immunoprecipitation (co-IP) and anti-succinyllysine immunoblotting. Co-IP coupled with mass spectrometry (MS) identified HSC70 as a PRDX3-interacting protein, and the interactions of PRDX3 with HSC70 and LAMP2A were validated by co-IP to assess chaperone-mediated Autophagy (CMA). In vivo, inflammatory responses in MSU-induced peritonitis and arthritis models were evaluated in SIRT5-deficient mice.

Results: SIRT5 preserved mitochondrial homeostasis and restrained NLRP3 inflammasome activation in macrophages in response to MSU crystals. Mechanistically, MSU crystal exposure reduced the SIRT5-PRDX3 interaction, increasing PRDX3 succinylation. This modification stabilized PRDX3 and impaired its chaperone-mediated Autophagy (CMA)-dependent degradation, leading to PRDX3 accumulation and subsequent mitochondrial dysfunction. In vivo, SIRT5 deficiency exacerbated MSU crystal-induced inflammation and upregulated PRDX3 protein levels.

Conclusions: Our findings reveal that SIRT5 desuccinylates PRDX3 to promote its CMA-dependent degradation, thereby preventing PRDX3 accumulation and mitochondrial dysfunction in MSU crystal-induced gouty inflammation.