Alvespimycin is identified as a novel therapeutic agent for diabetic kidney disease by chemical screening targeting extracellular vesicles.

Extracellular vesicles (EVs) are important mediators of intercellular communication and play key roles in the regulation of pathophysiological processes. In diabetic kidney disease (DKD), it has been reported that macrophages recruited in the mesangial region may play pathogenic roles through inducing local inflammation in glomeruli. We focused on EV-mediated crosstalk between mesangial cells (MC) and macrophages as a novel therapeutic target for DKD. EVs released from MC induced inflammation in macrophages and the effect was enhanced under high-glucose conditions. For discovering novel therapeutic agents which can inhibit such EV-mediated mechanisms, drug repositioning is considered as an effective tool. We established a unique screening strategy and screened agents to aim at maximizing their specificity and potency to inhibit EV mechanisms, along with minimizing their toxicity. We succeeded in identifying alvespimycin, an HSP90 inhibitor. Treatment of diabetic rats with alvespimycin significantly suppressed mesangial expansion, inflammatory gene activation including macrophage markers, and proteinuria. The inhibitory effect on EV uptake was specific to alvespimycin compared with other known HSP90 inhibitors. MC-derived EVs are crucial for inflammation by intercellular crosstalk between MC and macrophages in DKD, and alvespimycin effectively ameliorated the progression of DKD by suppressing EV-mediated actions, suggesting that EV-targeted agents can be a novel therapeutic strategy.