Kidney Week

Abstract: SA-PO610

Cell Non-Autonomous Origin of Renal Fibroblasts in Autosomal Dominant Tubulointerstitial Kidney Disease (ADTKD)

Session Information

• Noncystic Mendelian Diseases
  November 04, 2017 | Location: Hall H, Morial Convention Center
  Abstract Time: 10:00 AM - 10:00 AM

Category: Genetic Diseases of the Kidney

• 802 Non-Cystic Mendelian Diseases

Authors

• Shao, Annie, University of Minnesota, Minneapolis, Minnesota, United States

Annie Shao,

• Chan, Siu Chiu, University of Minnesota, Minneapolis, Minnesota, United States

Siu Chiu Chan,

• Mickelson, Alan, University of Minnesota, Minneapolis, Minnesota, United States

Alan Mickelson,

• Igarashi, Peter, University of Minnesota, Minneapolis, Minnesota, United States

Peter Igarashi,

Background

Autosomal dominant tubulointerstitial kidney disease (ADTKD) is an uncommon disorder that is characterized by slowly progressive CKD and autosomal dominant inheritance. Renal histology shows tubular cysts and interstitial fibrosis. ADTKD is genetically heterogeneous and can arise from mutations in at least four different genes. ADTKD-HNF1B is caused by mutations of the transcription factor hepatocyte nuclear factor-1β (HNF-1β). The mechanism whereby mutations of HNF-1β, an epithelial-specific protein, produce renal interstitial fibrosis is not known. Here, we performed lineage analysis to determine whether renal fibroblasts originate from HNF-1β-deficient tubular epithelial cells or via a cell non-autonomous process.

Methods

Ksp/Cre;Hnf1b^F/F mice were generated to specifically ablate HNF-1β in renal tubular cells. These mice were crossed with RYFP mice to introduce an EYFP reporter gene that is permanently activated upon Cre/loxP recombination, thereby enabling us to follow the fate of HNF-1β mutant cells. Kidneys were harvested from Ksp/Cre;Hnf1b^F/F;RYFP (HNF-1β KO) mice at P16 and P28. Hnf1b^F/+;RYFP littermates were used as negative controls.

Results

Histological staining with trichrome, PAS, and H&E showed that HNF-1β KO kidneys developed cysts and had increased extracellular matrix compared to control kidneys at P16. Costaining of HNF-1β KO kidney sections with antibodies against HNF-1β and EYFP showed that HNF-1β was absent in EYFP-positive cyst epithelial cells, confirming that expression of EYFP marks HNF-1β mutant cells. Costaining of HNF-1β KO kidney sections at P28 with antibodies against EYFP and entactin revealed that HNF-1β mutant cells remained on the luminal side of the tubular basement membrane. Costaining of HNF-1β KO kidney sections with antibodies against EYFP and smooth muscle α-actin revealed that myofibroblasts accumulated in the renal interstitium but did not express EYFP.

Conclusion

We conclude that HNF-1β-deficient kidneys develop fibrosis as early as P16. Lineage tracing demonstrates that HNF-1β mutant epithelial cells do not migrate out of renal tubules. Fibroblasts in the interstitium are not of tubular origin, indicating that fibrosis in ADTKD-HNF1B is due to a cell non-autonomous mechanism.

Funding

• NIDDK Support