Integrins: The culprit in acute kidney injury?

ABSTRACT NUMBER: NESTAC_07

AUTHORS
Raiyyan Aftab, Dr Rishab Kapoor, Professor Neil Sheerin

AFFILIATIONS
Institute of Cellular Medicine, Newcastle University
Kidney Research UK

CORRESPONDING AUTHOR CONTACT EMAIL
ku.ca.eltsacwen@batfa.r

MAIN ABSTRACT TEXT

Background
Acute Kidney Injury (AKI) is associated with increased mortality amongst patients. One of the most common causes of AKI is ischaemia which leads to tissue hypoxia; ultimately causing significant damage to the kidney and resulting in fibrosis. TGF-β and integrin αvβ6, which activates latent TGF-β, have also been implicated in the development of renal fibrosis.

Methods
This project studied the relationship between hypoxia in renal tubules and integrin αvβ6.
An in-vitro model of hypoxia was established using a human proximal tubular epithelial cell line (PTECS), HKC8. HKC8 cells were cultured in 1% O2, using 100µM CoCl2 as a positive control. Protein expression was quantified using immunofluorescence, western blots and flow cytometry. TGF-β activity was assessed using a SMAD-luciferase reporter line.

Results
Culturing HKC8 cells in 1% O2 led to decreased expression of epithelial marker E-Cadherin and increased expression of fibrotic marker alpha smooth muscle actin (p≤0.05). Furthermore, hypoxia also increased the cell surface expression of integrin αvβ6. Silencing the integrin αvβ6 led to a decrease in the availability of active TGF-β as well as stabilisation of the epithelial phenotype.

Conclusion
HKC8 cells cultured in 1% O2 develop a fibrotic phenotype, thus implicating hypoxia in the pathophysiology of renal fibrosis. This is most likely driven by increased TGF-β production in the kidney following hypoxia. Hypoxia increased expression of integrin αvβ6 and knockdown reduced bioactive TGF-β production and protected the epithelial phenotype. αvβ6 is a potential target for reducing the impact of ischaemia induced hypoxic kidney injury.