Basic Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Nephrol. Jul 6, 2016; 5(4): 339-357
Published online Jul 6, 2016. doi: 10.5527/wjn.v5.i4.339
Constitutive renal Rel/nuclear factor-κB expression in Lewis polycystic kidney disease rats
Michelle H T Ta, Kristina G Schwensen, David Liuwantara, David L Huso, Terry Watnick, Gopala K Rangan
Kristina G Schwensen, David Liuwantara, Gopala K Rangan, Michelle HT Ta, Centre for Transplant and Renal Research, Westmead Institute for Medical Research, the University of Sydney, Sydney 2145, Australia
David L Huso, Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
Terry Watnick, Division of Nephrology, University of Maryland School of Medicine, Baltimore, MD 21201, United States
Gopala K Rangan, Department of Renal Medicine, Westmead Hospital, Western Sydney Local Health District, Sydney 2145, Australia
Author contributions: Schwensen KG conducted the animal study, performed sample collection and histological staining; Ta MHT performed the immunofluorescence, Western blotting, and qPCR experiments, analyzed data and drafted the manuscript; Huso DL and Watnick T developed the Pkd2 knockout mouse model and provided paraffin embedded sections that were utilized for staining; Liuwantara D assisted with data interpretation and provided technical guidance with experimental methods; Rangan GK conceived of the study, conducted the animal study, performed sample collection and histological staining and reviewed and edited the manuscript; all authors read and approved of the final manuscript.
Supported by Funding from the National Health and Medical Research Council of Australia, Nos. 457575 and 632647 to Rangan GK; the Baltimore Polycystic Kidney Disease Research and Clinical Core Center, No. P30DK090868; DK095036 to Watnick T; Ta MHT was supported by an Australian Postgraduate Award (University of Sydney) and the Michael Stern Polycystic Kidney Disease Research Fellowship.
Institutional review board statement: The study was reviewed and approved by the Western Sydney Local Health District (WSLHD) Animal Ethics Committee and the WSLHD Human Research Ethics Committee.
Institutional animal care and use committee statement: All procedures involving Lewis and Lewis polycystic kidney (LPK) rats were approved by the Western Sydney Local Health District (WSLHD) Animal Ethics Committee (Protocol number 4100).
Conflict-of-interest statement: The authors have no conflicts of interest to disclose.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Gopala K Rangan, MBBS, PhD, Associate Professor of Medicine, Centre for Transplant and Renal Research, Westmead Institute for Medical Research, the University of Sydney, Level 5, 176 Hawkesbury Road (PO Box 412), Westmead, Sydney 2145, Australia. g.rangan@sydney.edu.au
Telephone: +61-2-86273502 Fax: +61-2-94751146
Received: February 10, 2016
Peer-review started: February 14, 2016
First decision: March 21, 2016
Revised: March 31, 2016
Accepted: April 14, 2016
Article in press: April 18, 2016
Published online: July 6, 2016
Abstract

AIM: To determine the temporal expression and pattern of Rel/nuclear factor (NF)-κB proteins in renal tissue in polycystic kidney disease (PKD).

METHODS: The renal expression of Rel/NF-κB proteins was determined by immunohistochemistry, immunofluorescence and immunoblot analysis in Lewis polycystic kidney rats (LPK, a genetic ortholog of human nephronopthsis-9) from postnatal weeks 3 to 20. At each timepoint, renal disease progression and the mRNA expression of NF-κB-dependent genes (TNFα and CCL2) were determined. NF-κB was also histologically assessed in human PKD tissue.

RESULTS: Progressive kidney enlargement in LPK rats was accompanied by increased renal cell proliferation and interstitial monocyte accumulation (peaking at weeks 3 and 10 respectively), and progressive interstitial fibrosis (with α smooth muscle actin and Sirius Red deposition significantly increased compared to Lewis kidneys from weeks 3 to 6 onwards). Rel/NF-κB proteins (phosphorylated-p105, p65, p50, c-Rel and RelB) were expressed in cystic epithelial cells (CECs) of LPK kidneys as early as postnatal week 3 and sustained until late-stage disease at week 20. From weeks 10 to 20, nuclear p65, p50, RelB and cytoplasmic IκBα protein levels, and TNFα and CCL2 expression, were upregulated in LPK compared to Lewis kidneys. NF-κB proteins were consistently expressed in CECs of human PKD. The DNA damage marker γ-H2AX was also identified in the CECs of LPK and human polycystic kidneys.

CONCLUSION: Several NF-κB proteins are consistently expressed in CECs in human and experimental PKD. These data suggest that the upregulation of both the canonical and non-canonical pathways of NF-κB signaling may be a constitutive and early pathological feature of cystic renal diseases.

Keywords: Inflammation, Nuclear factor-κB, Polycystic kidney disease, Tumour necrosis factor alpha, Chemokine CCL2

Core tip: Until now, there has been limited information regarding the specific nuclear factor (NF)-κB proteins involved in polycystic kidney disease (PKD) and their expression throughout disease progression. Our study demonstrated that a diverse array of NF-κB proteins is expressed in the renal cyst-lining cells of a chronic rodent model of PKD, and that NF-κB expression is constitutive over time. NF-κB was also identified in human PKD, suggesting that NF-κB upregulation is common to renal cystic disease models. Our data suggest that components of both the canonical and non-canonical NF-κB pathway are upregulated in PKD. Future studies should be directed at verifying whether specific NF-κB inhibition can attenuate interstitial inflammation and cyst growth, and slow the decline in renal function in in vivo models of PKD.