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Kidney Week

Abstract: SA-PO779

CFTR Absence Affects Kidney Structure and Function

Session Information

Category: Genetic Diseases of the Kidneys

  • 1201 Genetic Diseases of the Kidneys: Cystic

Authors

  • Miszczuk, Mateusz, University of Virginia School of Medicine, Charlottesville, Virginia, United States
  • Charlton, Jennifer R., University of Virginia, Charlottesville, Virginia, United States
  • Swiatecka-Urban, Agnieszka, University of Virginia, Charlottesville, Virginia, United States
Background

Cystic fibrosis (CF) is an autosomal recessive disorder arising from mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene and leads to impaired ion transport across epithelial cells. CFTR plays a critical role in renal progenitor self-renewal during nephrogenesis suggesting that altered CFTR expression could impair nephron endowment and predispose to renal hypodysplasia. During aging, chronic kidney disease (CKD) is morecommon in people with cystic fibrosis (PwCF) than in non-CF individuals. Here, we evaluated the effect of the absence of CFTR on the kidney structure in young mice.

Methods

Kidneys from 7–9 week old C57BL/6J mice expressing wild-type (WT) CFTR or G542X CFTR (CFTR KO; N=2/group/sex) were formalin-fixed and paraffin-embedded. We performed morphometric analysis of glomerular and tubular structures using PAS staining. Glomerular density was assessed by counting the number of glomeruli using light microscopy (n=3/kidney). Cortical area of the kidney was measured using Amira software. Glomerular density was expressed as the number of glomeruli per unit area (glomeruli/mm2). Lotus tetragonolobus lectin staining of proximal tubules was performed to evaluate presence of the functional glomerulo-tubular junctions (GTJ). Absence of Lotus positive cells in Bowman’s capsule defined the loss of GTJ.

Results

The mean renal cortical area was 31% smaller in KO male, compared to WT male. Thecorresponding kidney weight was 25% lower in KO male. The mean cortical area was 8% biggerdespite 20% lower kidney weight in KO female, compared to WT female. Glomerular densitywas 40% and 33% higher in KO male and female, compared to WT male and female, respectively. The loss of GTJ connections was higher in the KO groups (49% and 65% in KO males and females, compared to 27% and 40% in the WT counterparts).

Conclusion

Decreased kidney weight, smaller mean cortical area, higher glomerular density, and loss of GTJ connections in KO groups support the critical role of CFTR in the kidney and suggest that CFTR dysfunction may predispose PwCF to CKD. Increased mean cortical volume despite a lower kidney weight and loss of GTJ connections in KO females emphasize that the impact of CFTR absence is modulated by sex-specific factors.

Funding

  • Other NIH Support