The delayed administration of IKK-16, a specific IKKβ inhibitor, attenuates acute kidney injury in rat recovery model of unilateral renal ischaemia

Florence Johnson1,2, Massimo Collino3, Elisa Benetti3, Christoph Thiemermann1, Nimesh Patel1. 1Queen Mary, University of London, London, UK, 2King\'s College London, London, UK, 3University of Turin, Turin, Italy

Acute kidney injury (AKI) caused by ischaemia-reperfusion injury (IRI) is being increasingly regarded as a risk factor for chronic kidney disease (CKD) (Hsu, 2012). Post-inflammatory renal scarring due to AKI might be an important contributor to the development of CKD. Activation of nuclear factor-κB (NF-κB) is known to play a key role in the production of various cytokines and chemokines, and seen to be a significant contributor to injury following ischaemia-reperfusion. NF-κB is a diverse family of transcription factors that can be activated by IκB kinase (IKK), a multi-subunit of which IKKβ is the most critical. Recent studies have indicated that inhibition of IKK with siRNA prior to renal IRI attenuates kidney injury and inflammation (Wan et al., 2011). We have, therefore, hypothesised that the specific inhibition of IKK with N-(4-Pyrrolidin-1-yl-piperidin-1-yl)-[4-(4-benzo[b]thiophen-2-yl-pyrimidin-2-ylamino) phenyl]carboxamide hydrochloride (IKK-16) (Waelchli et al., 2006) will aid in the attenuation of renal, glomerular and tubular dysfunction. Fifty-three male Wistar rats were anaesthetised with a ketamine (100 mg/ml) and xylazine (20 mg/ml) (2:1; 1.5 ml/kg, i.p.) mixture and underwent a right nephrectomy followed by unilateral renal ischaemia for 30 minutes by clamping the left renal artery with non-traumatic vascular clips. The rats were randomised into five groups; sham (no clamping of renal artery) (n=12), control (n=17), 0.1mg/kg IKK-16 (n=5), 0.3mg/kg IKK-16 (n=8), 1mg/kg IKK-16 (n=11). IKK-16 was dissolved in 10% DMSO and administered i.v. 24 h after the onset of reperfusion. Rats were allowed to recover for 48 h. Twenty-four hours prior to termination of the experiment, rats were placed into metabolic cages for the collection of urine at 48 h. The experiment was terminated 48 h after the commencement of reperfusion for the collection of serum. Data are expressed as mean ± s.e.m and analysed by a one-way ANOVA followed by Dunnett’s post-hoc test. When compared to rats subjected to sham-operation, rats subjected to unilateral renal IRI (control) demonstrated a significant increase in serum creatinine (P<0.05), creatinine clearance (P<0.05) and fractional excretion of sodium (P<0.05) indicating the development of renal, glomerular and tubular dysfunction, respectively. The administration of IKK-16 demonstrated a dose dependant attenuation of dysfunction, which was seen to be significant in all three parameters when administered at a dose of 1mg/kg 24 h into reperfusion (P<0.05). We have shown here, for the first time, that the late administration of an IKK inhibitor accelerates the rate of recovery of renal, glomerular and tubular dysfunction. The late inhibition of IKK may, therefore, have therapeutic potential in the recovery of AKI and the prevention of CKD. Further investigations are required to determine the exact role of IKK in the development of CKD.

References:

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Wan X, Fan L, Hu B, Yang J, Li X, Chen X, Cao C. Small Interfering RNA targeting IKKβ prevents renal ischemia-reperfusion injury in rats. Am J Physiol Renal Physiol 2011; 300: 857-63.