M-SYFSF attenuates diabetic kidney disease by suppressing Piezo1-associated cGAS-STING signalling and tubular...

Diabetic kidney disease (DKD) is a major cause of chronic kidney disease (CKD) worldwide, characterised by tubular injury, inflammation, and fibrosis. Increasing evidence suggests that mechanotransduction and innate immune activation contribute to DKD progression. However, the mechanistic link between mechanosensitive ion channels, cGAS-STING signalling, and pyroptosis remains incompletely understood.

This study aimed to investigate whether the modified Shen-Yan-Fang-Shuai formula (M-SYFSF) attenuates DKD and to explore its potential regulatory effects on Piezo1-mediated Ca²⁺ signalling, cGAS-STING activation, and tubular pyroptosis.

DKD was induced in rats by unilateral nephrectomy combined with streptozotocin injection, with valsartan as a positive control, and HK-2 cells were stimulated with advanced glycation end products (AGEs). Renal function, histopathology and fibrosis were assessed by biochemical assays and histological staining. Renal transcriptome sequencing, network pharmacology and analysis of public human renal transcriptomic datasets were used to identify candidate pathways. Western blotting, immunohistochemistry, immunofluorescence, qRT-PCR, Fluo-4 AM calcium imaging, ELISA, serum LDH activity and renal caspase-1 activity assays were performed to evaluate Piezo1 expression, cGAS-STING signalling and pyroptosis. Piezo1 knockdown and pharmacological modulation were used to assess pathway ordering, and Co-IP was used to examine the cGAS-STING association. Molecular docking and molecular dynamics simulation were performed as exploratory, hypothesis-generating analyses.

DKD rats exhibited renal dysfunction, increased fibrosis, elevated Piezo1 expression, increased intracellular Ca²⁺ levels, activation of cGAS-STING signalling and upregulation of pyroptosis-associated proteins. Renal transcriptome sequencing and network pharmacology converged on mechanotransduction- and AGE-RAGE-associated pathways, and Piezo1 upregulation was further confirmed in db/db and HFD + STZ mice and in human tubulointerstitial datasets. M-SYFSF treatment improved renal function, attenuated fibrosis, reduced Piezo1 expression and intracellular Ca²⁺ accumulation, and suppressed cGAS-STING signalling and downstream inflammatory responses. Piezo1 knockdown attenuated STING and GSDMD-N upregulation, which was partially restored by Yoda1, whereas the STING inhibitor H-151 suppressed both STING and pyroptotic responses. Co-IP analysis showed an AGEs-induced cGAS-STING association that was reduced by M-SYFSF.

M-SYFSF attenuated experimental DKD in association with reduced Piezo1-associated Ca²⁺ signalling, cGAS-STING activation and tubular pyroptosis-associated responses, and Piezo1 upregulation was reproducible across three rodent models and in human renal tissue. The data support an upstream contribution of Piezo1 under AGEs stress but do not establish the genetic necessity of STING, the proposed mitochondrial DNA intermediate, or the occurrence of fully executed pyroptosis.