*4.6. Kidney Histopathology*

Histological kidney assessment was performed as previously reported [39]. Formalinfixed, paraffin-embedded sections (2 μm) of kidneys were subjected to periodic acid–Schiff (PAS) and Sirius red (SR) staining. The PAS reaction visualized the basement membranes of the capillary loops of the glomeruli, through which the glomerular damage can be evaluated [7]. In each group, 10 fields of view were randomly selected from each kidney sample section under a 400× magnification, and the average ratio of glomerular section area to total area within the view was calculated using the software ImageJ. SR staining allows for a quantification of interstitial fibrosis. The severity of tubule interstitial fibrosis was graded from 0 to 3 according to the distribution of lesions: 0, no lesion; 1, less than 20%; 2, 20–50%; 3, more than 50% [40]. Semi-quantitative glomerular damage and renal fibrotic scoring were performed in a blinded manner at 400× magnification per sample. All measurements were repeated three times.
