Bumetanide‑blocked SLC12A2 exerts a protective effect in experimental diabetic retinopathy

Diabetic retinopathy (DR) is a common microvascular complication that leads to vision loss in patients with diabetes. The SLC12A2/SLC12A4 inhibitor, bumetanide, has been reported to alleviate hypoxia‑induced retinopathy. It was hypothesized that it may exert the same effect in DR. DR cell types and SLC12A2/SLC12A4 expression at the cell level were analyzed using single cell RNA‑sequencing (scRNA‑seq) data. Next, cell [high glucose (HG) stimulation] and animal (mice injected with streptozotocin) DR models were constructed. The protective effects and possible mechanisms of bumetanide and SLC12A2 were investigated through a series of experiments, including Cell Counting Kit‑8, TUNEL, Transwell, tube formation, ELISA, immunofluorescence staining, western blot and reverse transcription‑quantitative PCR assays. Bumetanide reduced HG‑induced cell apoptosis by suppressing the expression of SLC12A2 and SLC12A4. Second, scRNA‑seq analysis revealed that SLC12A2 was predominantly expressed in endothelial cells, which are the main targets of hyperglycemic damage. Endothelial cell‑related markers were involved in angiogenesis and adhesion molecule‑related pathways. Third, in HG‑stimulated cells, SLC12A2 knockdown efficiently reduced the inflammatory response and angiogenesis, while maintaining endothelial barrier integrity. This protective process involved reduced release of inflammatory factors (IL‑1β and IL‑6) and growth factors (vascular endothelial growth factor), suppression of adhesion molecule expression (VCAM1, ICAM1, E‑Selectin and P‑Selectin), activation of tight junction protein (ZO‑1), and decreased matrix metalloproteinases (MMP2 and MMP9). Furthermore, SLC12A2 deficiency ameliorated DR progression in streptozotocin‑induced diabetic mice by improving retinal thickness and pathological changes. The present study elucidates the crucial role of bumetanide in DR treatment and suggests that targeting SLC12A2 may represent a novel therapeutic strategy for the prevention of DR.