Eupalinolide B Ameliorates Diabetic Kidney Disease via Inhibition of Cell Division Cycle 37–Mediated Inflammatory Pathways

KEY POINTS: A natural sesquiterpene lactone compound Eupalinolide B protected against diabetic kidney disease. Eupalinolide B targeted cell division cycle 37 protein and disrupted the interaction between cell division cycle 37 and heat shock protein 90. The renoprotective effects of Eupalinolide B were dependent on cell division cycle 37-mediated inflammatory pathways in diabetic kidney disease. BACKGROUND: Diabetic kidney disease (DKD) is a major complication of diabetes, driven by chronic inflammation throughout its initiation and progression. Developing effective novel therapeutics is urgently needed. Eupalinolide B, a natural small compound derived from Eupatorium lindleyanum DC ., has multiple bioactive properties, notably antitumor and anti-inflammatory activities. However, the therapeutic potential of Eupalinolide B for DKD remains unclear. This study was to investigate the potential effects, direct targets, and pharmacologic mechanisms of Eupalinolide B against DKD, and discover novel therapeutic targets in the progression of DKD. METHODS: The therapeutic effects of Eupalinolide B were assessed in high glucose-induced rat mesangial (HBZY-1) cells and db/db diabetic mice. Targeting and binding site engagement of Eupalinolide B was validated through activity-based protein profiling technology, pull-down assay, surface plasmon resonance analysis, and high-resolution mass spectrometry analysis. The target protein was knocked down to investigate its role in DKD-related inflammation and determine whether Eupalinolide B's renoprotective effects depend on the protein. The impact of Eupalinolide B on protein-protein interactions was examined using immunoblotting, immunohistochemistry, immunofluorescence, and coimmunoprecipitation assays. RESULTS: Eupalinolide B was observed to ameliorate the glomerular filtration dysfunction and histopathologic damage in db/db mice and suppress NF-κB and mitogen-activated protein kinase proinflammatory pathways in both high glucose-induced HBZY-1 cells and db/db mice. In addition, we found that Eupalinolide B directly bound to cysteine 64 and 234 residues of cell division cycle 37 (CDC37), the essential cochaperone of heat shock protein 90 (HSP90). Mechanistically, by targeting CDC37, Eupalinolide B disrupted the interaction between CDC37 and HSP90, consequently blocking downstream proinflammatory signaling upon high glucose induction in HBZY-1 cells. CONCLUSIONS: Eupalinolide B was identified as a novel CDC37-targeting agent with renoprotective and anti-inflammatory effects against DKD that functions by inhibiting CDC37-HSP90 interaction.