Targeting Hsp90α to inhibit HMGB1-mediated renal inflammation and fibrosis

Renal fibrosis, a terminal manifestation of chronic kidney disease, is characterized by uncontrolled inflammatory responses, increased oxidative stress, tubular cell death, and imbalanced deposition of extracellular matrix. 5,2'-Dibromo-2,4',5'-trihydroxydiphenylmethanone (LM49), a polyphenol derivative synthesized by our group with excellent anti-inflammatory pharmacological properties, has been identified as a small-molecule inducer of extracellular matrix degradation. Nonetheless, the protective effects and mechanisms of LM49 on renal fibrosis remain unknown. Here, we report LM49 could effectively alleviate renal fibrosis and improve filtration function. Furthermore, LM49 significantly inhibited macrophage infiltration, pro-inflammatory cytokine production and oxidative stress. Interestingly, in HK-2 cells induced by tumour necrosis factor alpha under oxygen-glucose-serum deprivation conditions, LM49 treatment similarly yielded a reduced inflammatory response, elevated cellular viability and suppressed cell necrosis and epithelial-to-mesenchymal transition. Notably, LM49 prominently suppressed the high-mobility group box 1 (HMGB1) expression, nucleocytoplasmic translocation and activation. Mechanistically, drug affinity responsive target stability and cellular thermal shift assay confirmed that LM49 could interact with the target heat shock protein 90 alpha family class A member 1 (Hsp90α), disrupting the direct binding of Hsp90α to HMGB1 and inhibiting the nuclear export of HMGB1, thereby suppressing the inflammatory response, cell necrosis and fibrogenesis. Furthermore, molecular docking and molecular dynamic simulation revealed that LM49 occupied the N-terminal ATP pocket of Hsp90α. Collectively, our findings show that LM49 treatment can ameliorate renal fibrosis through inhibition of HMGB1-mediated inflammation and necrosis via binding to Hsp90α, providing strong evidence for its anti-inflammatory and anti-fibrotic actions.