Renal histology

The removed kidneys were fixed in 4% phosphate-buffered formalin solution and embedded in paraffin. Three-micrometer-thick sections were stained with H&E, PAS, and PASM. The morphology and structure of the kidney tissue were visualized by H&E staining. PAS staining was used to demonstrate mesangial matrix deposition, and basement membrane thickening was assessed by PASM staining. The degree of glomerular damage was defined as the extent of extracellular matrix deposition and mesangial expansion [30]. Tubulointerstitial changes included tubular atrophy, casts, tubular dilation, interstitial mononuclear cell, and extracellular matrix accumulation [31]. All renal biopsies were examined by the same pathologist, who was blinded to the experimental groups.