About one-third of Type 2 Diabetic (T2D) patients develop diabetic kidney disease (DKD), which is the leading cause of end-stage renal disease. A high-fat Western diet (HFD) promotes metabolic dysfunction and inflammation, accelerating T2D and its complications. However, molecular mechanisms through which HFD exacerbates DKD, particularly in a sex- and age-dependent manner, remain incompletely defined. Therefore, the objective of this study was to define the molecular pathways underlying DKD in young and aged male and female rats with T2D fed HFD. Young (12 weeks old) and aged ( >40 weeks old) male and female Type 2 Diabetic Nephropathy (T2DN) rats, an established non-obese T2D model, were placed on a normal-fat diet (NFD) or HFD for 12 weeks. Kidney injury was assessed by biochemical analysis of urine and plasma, and by protein levels of kidney injury molecule-1 (Kim-1). Masson’s Trichrome and Oil red-O staining were used to assess cellular damage, fibrosis, and lipid deposits in renal tissue. RNA-sequencing analysis was performed on kidney samples to assess mRNA expression levels across genes and pathways. An unpaired t-test or ANOVA was used for statistical comparisons; data was represented as ± standard error of the mean with n=5 for all groups. We found that both young and aged T2DN females were more susceptible and showed significant kidney injury after chronic HFD feeding, whereas males of both age groups showed minimal kidney damage, as assessed by albuminuria, Kim-1 levels, histopathology, and RNA sequencing. Further analysis showed increased cortical fibrosis in the young T2DN females fed HFD as compared to young females on NFD (3.7 ± 0.5 vs 6.7 ± 0.8 % area, p=0.03). However, in addition to an increase in urinary albumin creatinine ratio when compared to their NFD controls, aged HFD-fed females also presented a higher level of Kim-1 protein, medullary casts, and lipid deposits in renal tissue (1.9 ± 0.7 vs 4.8 ± 0.8, p=0.02, 0.8 ± 0.2 vs 1.8 ± 0.2, p=0.01, and 0.3 ± 0.0 vs 0.6 ± 0.1 % area, p=0.01, respectively). RNA-sequencing further revealed a marked age-dependent difference in gene expression and associated molecular responses among females. Specifically, in the young HFD-fed group, there was a significant increase in fibrotic signaling, as indicated by the high expression of genes associated with fibrosis, including fibronectin 1 (Fn1), matrix metallopeptidase 11 (Mmp11), and transforming growth factor beta 1 (Tgfb1). In contrast, aged HFD-fed females displayed pronounced metabolic dysregulation, with significant alterations in genes and pathways related to glucose and lipid metabolism. Further studies to identify the factors associated with the observed sex-specific difference in kidney damage revealed Serine Protease Inhibitor B12 (Serpinb12) as a candidate gene specific to female, but not male T2DN rats. Ongoing in vivo and in vitro mechanistic studies are investigating the role of Serpinb12 in inflammation and fibrosis in HFD-driven DKD in T2D. In summary, our study demonstrated a sex-dependent progression of HFD-exacerbated DKD in T2D and suggests that more sex-specific approaches are needed for better treatment of male and female DKD patients. Furthermore, our studies identified Serpinb12 as a novel candidate gene potentially mediating female-specific pathways that link HFD exposure to DKD progression. Funding: This work is supported by National Institutes of Health Grants R01 DK129227 (to AS), and T32 HL160529 (to RB), Department of Veteran Affairs grant I01 BX004024 and IK6 RD001204 (to A.S.), and USF Hypertension and Kidney Research Center Early Investigator Awards (to LVD and RT). This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
Lowe et al. (Fri,) studied this question.