Role Of A1AR In Cisplatin-mediated Acute Kidney Injury

BackgroundAs a chemotherapy drug, Cisplatin is highly effective for many types of solid tumors. However, its nephrotoxicity, one of its main adverse effects, limits the clinical use. Recently, the incidence of acute kidney injury (AKI) keeps increasing as the rise of tumors and aging. In cancer patients, the frequency of AKI is known about 12-16%. Cisplatin induces AKI through cell death, inflammation and the change of kidney blood flow. How to prevent and treat cisplatin-induced AKI has drawn the attention of many researchers. Adenosine A1 receptor could contract the afferent arteriole to change the vessel tone in kidney. It also regulates the inflammation reaction, necrosis and apoptosis. But its role in cisplatin-induced AKI is controversial. The underlying mechanisms are still largely unknown. Our hypothesis is that A1AR may exacerbate the kidney through the classic hemodynamic regulation role or the cell apoptosis pathway.Propose1. Retrospectively analyze the incidence rate,correlated clinical factors of AKI in lung cancer patients with chemotherapy and the relationship between AKI and in-hospital mortality.2. Establish the cisplatin-induced AKI mice model to observe the expression level of cell apoptosis markers and explore whether adenosine and A1AR have a role in it.3. Establish the cisplatin-induced AKI model in A1AR-/- mice to observe the effects of A1AR and possible mechanisms.Method1.479 lung cancer patients with chemotherapy in Peking Union Medical College Hospital from May 1,2012 to April 30,2013 were included. Their clinical and pathological information was collected to analyze the incidence rate and correlated clinical factors of AKI. We followed up them 3 months to observe in-hospital mortality and the effect of AKI. 2.8-to 10-week A1AR-/- mice and wild type C57BL/6J male mice were used to establish the cisplatin-induced AKI model through a single intraperitoneal injection of cisplatin(25mg/kg). Monitor the change of systolic blood pressure(SBP), heart rate(HR) and weight. Mice were euthanized 24h,72h after the cisplatin injection. Blood was collected for measurement of serum creatinine. kidney tissue were used to assess the expression of renin, CD73, A1AR, A2bAR and Bax through immunohistochemistry staining, western blot or real-time PCR.3. Statistics:Continuous variables are displayed as mean±standard deviation. Groups were compared with a t-test or Mann-Whitney rank test as appropriate. Logistic regression analyses were performed to test the association between variables. A P-value of<0.05 was considered significant. Statistical analysis was performed with the SPSS software (version 19.0 for Windows).Result4. AKI was the independent risk factor for in-hospital mortality in lung cancer patients with chemotherapyThe incidence rate of AKI in lung cancer patients with chemotherapy was 9.19%, Significantly higher than the diagnosis rate. Hyponatremia and use of antibiotics before chemotherapy were related with the happening of AKI. The in-hospital mortality of AKI patients were 18.18%, almost 6 times of that of non-AKI patients (P<0.01).5. The characteristic of AKI miceAfter cisplatin injection, the SBP, HR and weight of mice had a down-going trend. Their serum creatinine and BUN elevated significantly. Mice euthanized 72h after cisplatin injection had severer kidney injury than mice euthanized 24h after injection.6. The A1AR expression in mice kidneyThe injection of cisplatin caused the up-regulation of A1AR expression in mice kidney (0.929±0.036 vs.0.717±0.079, P<0.01).7. The renin, CD73, A2bAR, Bax expression in mice kidneyThe expression level of A2bAR and Bax were higher in mice receiving cisplatin injection than control mice(A2bAR:0.985±0.084 vs.0.787±0.088, P<0.05; Bax: 1.138±0.702 vs.8.045±7.561, P<0.01). Renin and CD73 expression had no obvious change between two groups.8. The kidney injury in A1AR-/- mice and probable underlying mechanisms1) 24h after cisplatin injection, the serum creatinine and ATN score ofA1AR-/- mice were higher than those of control mice(Scr:29.2±19.86μmol/L vs. 13.8±2.61μmol/L,P<0.01;ATN score:2.0±0.66 vs.0.75±0.05, P<0.05).2) Compared with control mice, the expression of CD73 and Bax were similar in Al AR-/- mice. But the expression of A2bAR was significantly decreased(0.693 ±0.118 vs.0.979±0.081, P<0.01).3) The expression of renin in A1AR-/- mice were obviously up-regulated than control mice(0.070±0.042 %vs. O.015±0.008%, P<0.01).Conclusion1. Acute kidney Injury is the independent risk factor of in-hospital mortality in lung cancer patients with chemotherapy.2. The expression of A2bAR and Bax, the markers of cell apoptosis, elevated significantly in wild type mice with AKI indicates the role of cell apoptosis in cisplatin-induced AKI.3. The kidney injury of A1AR-/- mice is severer than wide type mice, which elucidates A1AR could ameliorate cisplatin-induced AKI. It may be related with the up-regulation of renin expression in A1AR-/- mice.