Kidney Injury by Unilateral Ureteral Obstruction in Mice Lacks Sex Differences

Abstract

Introduction: Renal fibrosis is a critical event in the development and progression of chronic kidney disease (CKD), and it is considered the final common pathway for all types of CKD. The prevalence of CKD is higher in females; however, males have a greater prevalence of end stage renal disease (ESRD). In addition, low birth weight and low nephron number are associated with increased risk for CKD. This study examined the development and severity of unilateral ureter obstruction (UUO) induced renal fibrosis in male and female wild-type (ROP +/+) and mutant (ROP Os/+) mice, a mouse model of low nephron number. Methods: Male and female ROP +/+ and ROP Os/+ mice were subjected to UUO, and kidney tissue collected at the end of the 10-day experimental period. Kidney histological analysis and mRNA expression determined renal fibrosis, tubular injury, collagen deposition, extracellular matrix proteins, and immune cell infiltration. Results: Male and female UUO mice demonstrated marked renal injury, kidney fibrosis, and renal extracellular matrix production. Renal fibrosis and α-smooth muscle actin were increased to a similar degree in ROP +/+ and ROP Os/+ mice with UUO of either sex. There were also no sex differences in renal tubular cast formation or renal infiltration of macrophage in ROP +/+ and ROP Os/+ UUO mice. Interestingly, renal fibrosis and α-smooth muscle actin was 1.5-3-fold greater in UUO ROP +/+ compared to UUO ROP Os/+ mice. Renal inflammation phenotypes following UUO were also 30-45% greater in ROP +/+ compared to ROP Os/+ mice. Likewise, expression of extracellular matrix and renal fibrotic genes was greater in UUO ROP +/+ mice compared to UUO ROP Os/+ mice. In contrast to these findings, ROP Os/+ mice with UUO demonstrated glomerular hypertrophy with 50% greater glomerular tuft area compared to ROP +/+ with UUO. Glomerular hypertrophy was not sex dependent in any of the genotypes of ROP mice. These findings provide evidence that low nephron number contributes to UUO-induced glomerular hypertrophy in ROP Os/+ mice but does not enhance renal fibrosis, inflammation and renal tubular injury. Conclusion: Taken together, we demonstrate that low nephron number contributes to enhanced glomerular hypertrophy but not kidney fibrosis and tubular injury. We also demonstrate that none of the changes caused by UUO was affected by sex in any of the ROP mice genotypes.

The secreted micropeptide C4orf48 enhances renal fibrosis via an RNA-binding mechanism

“…Female mice are resistant to STX-induced diabetes, and so this model was performed only in male mice. Both the UUO model ( 50 ) and the FA model ( 51 ) are induced equally in male and female mice; therefore, we performed studies in only male mice in order to minimize animal use (recognizing the goal of animal ethics for replacement, reduction and refinement), knowing that the results are highly likely to apply equally to both sexes.…”