Mineralocorticoid receptor antagonists in kidney transplantation

BACKGROUND

The fundamental role of the renin-angiotensin-aldosterone system in the pathophysiology of chronic kidney disease, congestive heart failure, hypertension and proteinuria is well established in pre-clinical and clinical studies. Mineralocorticoid receptor antagonists are among the primary options for renin-angiotensin-aldosterone system blockage, along with angiotensin-converting enzyme inhibitors and angiotensin receptor blockers.

METHODS

In this narrative review, we aim to evaluate the efficiency and safety of mineralocorticoid receptor antagonists in kidney transplant recipients, including the potential underlying pathophysiology.

RESULTS

The efficiency and safety of mineralocorticoid receptor antagonists in managing chronic kidney disease and proteinuria, either non-nephrotic or nephrotic range, have been demonstrated among nontransplanted patients, though studies investigating the role of mineralocorticoid receptor antagonists among kidney transplant recipients are scarce. Nevertheless, promising results have been reported in pre-clinical and clinical studies among kidney transplant recipients regarding the role of mineralocorticoid receptor antagonists in terms of ischaemia-reperfusion injury, proteinuria, or calcineurin inhibitor-mediated nephrotoxicity without considerable adverse events such as hypotension, hyperkalaemia or worsening renal functions.

CONCLUSION

Even though initial results regarding the role of mineralocorticoid receptor antagonist therapy for kidney transplant recipients are promising, there is clear need for large-scale randomized clinical trials with long-term follow-up data.

The Critical Role of Cannabinoid Receptor 2 in URB602-Induced Protective Effects Against Renal Ischemia-Reperfusion Injury in the Rat

Renal ischemia-reperfusion injury (IRI) is a major cause of acute kidney injury (AKI) and even induces remote organ damage. Accumulating proofs demonstrates that the endocannabinoid system may provide a promising access for treatment strategy of renal IRI associated AKI. In the current study, using the established renal IRI model of rat, we tested the hypothesis that pretreatment of URB602, 30 min before renal IRI, alleviates kidney injury and relevant distant organ damage via limiting oxidative stress and inflammation. Using Western blot analysis and LC-MS/MS, renal IRI showed to increase the levels of 2-arachidonoylglycerol (2-AG) in kidneys as well as COX-2, PGE2, TXA2, and decrease N-arachidonoylethanolamine (anandamide, AEA); the expressions of renal cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2) were unchanged. The URB602 pretreatment in renal IRI, further enhanced renal 2-AG which is high affinity to both CB1 and CB2, and reduced renal COX-2 which is involved in the regulation of renal perfusion and inflammation. AM630 (CB2 antagonist) almost blocked all the antioxidant, anti-inflammatory and nephroprotective effects of URB602, whereas AM251 (CB1 antagonist) showed limited influence, and parecoxib (COX-2 inhibitor) slightly ameliorated renal function at the dose of 10 mg/kg. Taken together, our data indicate that URB602 acts as a reactive oxygen species scavenger and anti-inflammatory media in renal IRI mainly depending on the activation of CB2.