The Late Inhibition of IκB Kinase Attenuates Acute Kidney Injury and the Subsequent Development of Renal Fibrosis in Animal Models of Ischaemia-Reperfusion Injury and Unilateral Ureteral Obstruction
Acute kidney injury (AKI) is a major risk factor for chronic kidney disease (CKD). For patients who recover from AKI, there is a 25% increase in the risk of CKD, and a mortality rate of up to 50% after 10 years. Nuclear factor kappa-B (NF-κB) is a family of transcription factors that regulates the transcription of many proteins that play a key role in inflammation. Inhibitor of IκB kinase (IKK) is directly upstream of NF-κB. My aim was to investigate a) the role of IKK in the progression of AKI to CKD, and b) whether its inhibition attenuates renal fibrosis. In this thesis I used a model of unilateral renal ischaemia-reperfusion injury with contralateral nephrectomy, to firstly map the acute time course of AKI. From the data generated from the time course, I decided to treat the animals at 24 h post reperfusion with the IKK inhibitor, IKK16, as i) this was at the peak of renal dysfunction (24 h post reperfusion), and ii) prior to the activation of NF-κB (48 h post reperfusion). The inhibition of IKK at 24 hours post reperfusion, as a delayed treatment, successfully attenuated renal dysfunction, NF-κB activation and renal structural damage. I subsequently increased the recovery time after ischaemia-reperfusion in my rat model to 28 days to study the development of fibrosis post AKI. The inhibition of IKK at 24 hours post reperfusion successfully attenuated the development of fibrosis, formation of myofibroblasts, macrophage infiltration, the expression of pro-fibrotic markers and the deposition of extracellular matrix components at 28 days post reperfusion. In addition, the delayed inhibition of IKK at days 7-13 post unilateral ureteral obstruction in a rat model, successfully attenuated the development of fibrosis, formation of myofibroblasts, macrophage infiltration, the expression of pro-fibrotic markers and the deposition of extracellular matrix components. These data indicate that the activation of the IKK complex drives tubulointerstitial fibrosis, and suggests that the inhibition of IKK could be a useful pharmacological tool for the creation of therapies to combat AKI and the subsequent development of fibrosis, via the reduction of both inflammation and the prevention of the expression of pro-fibrotic markers.
- Theses