Procyanidin B2 attenuates microvascular dysfunction in diabetic retinopathy via inhibition of caspase-1/GSDMD mediated pyroptosis

Abstract

Ethnopharmacological relevance: In traditional Chinese medicine (TCM), grape seeds (Vitis vinifera) are believed to nourish the liver and kidney and improve blood circulation, which aligns with the pathophysiological needs of conditions characterized by microvascular dysfunction. Procyanidin B2 (PB2), a major active compound in grape seeds, has shown potent anti-inflammatory and vascular-protective effects. However, the specific role of PB2 in diabetic retinal microvasculature and its underlying molecular mechanisms remain unexplored.

Aims of the study: This study aimed to evaluate the therapeutic potential of Procyanidin B2 (PB2) in alleviating microvascular damage in diabetic retinopathy and the possible mechanisms.

Materials and methods: Pyroptosis in endothelial cells was analyzed under high glucose conditions and in the retinas of diabetic mice. The effects of PB2 on pyroptosis and endothelial dysfunction were examined through in vitro assays evaluating cell proliferation, migration, and tube formation. In vivo experiments using diabetic mouse models were conducted to assess retinal vascular integrity, with a focus on PB2's impact on endothelial pyroptosis and its associated molecular mechanisms.

Results: PB2 significantly suppressed pyroptosis in endothelial cells exposed to high glucose by inhibiting the caspase-1/GSDMD signaling pathway. This suppression enhanced endothelial cell proliferation, migration, and tube formation. In diabetic mice, PB2 treatment effectively alleviated retinal microvascular dysfunction by reducing pyroptosis and preserving retinal vascular integrity.

Conclusion: These findings provide a molecular basis for PB2's therapeutic potential in DR and support its further development as an intervention for diabetic vascular complications.

Keywords: Diabetic retinopathy; Endothelial cells; GSDMD; Procyanidin B2; Pyroptosis.