ABSTRACT
Objective:To evaluate the role of interleukin-4 (IL-4) in renal fibrosis induced by acute kidney injury (AKI) in mice.Methods:Twenty-four male C57BL/6 mice, aged 8-10 weeks, weighing 20-30 g, were divided into 4 groups ( n =6 each) using a random number table method: control group (group CON), AKI group, control plus anti-IL-4 antibody group (group CON-A), and AKI plus anti-IL-4 antibody group (group AKI-A). In AKI-A and AKI groups, folic acid was intraperitoneally injected to induce AKI in anesthetized mice, and the anti-IL-4 antibody 40 mg/kg and the equal volume of PBS were intraperitoneally injected, respectively, at 3, 6, 9 and 12 days after injection. The equal volume of PBS and anti-IL-4 antibody was given at the corresponding time point in CON and CON-A groups, respectively.The orbital blood samples were taken on day 14 after injecting folic acid for determination of the serum blood urea nitrogen (BUN) and creatinine (Cr) concentrations.The animals were then sacrificed, and renal tissues were obtained for examination of the pathological changes (using Sirius red staining and Masson staining) and for determination of the expression of fibronectin(FN), collagen-Ⅰ(Col-Ⅰ) and α-smooth muscle actin (α-SMA) (by Western blot) and expression of CD206, Arg-1 and FIZZ1 mRNA (by real-time polymerase chain reaction). The area of renal fibrosis was measured. Results:Compared with group CON, the serum BUN and Cr concentrations were significantly increased, the area of renal fibrosis was increased, and the expression of FN, Col-Ⅰ, α-SMA and CD206, Arg-1 and FIZZ1 mRNA in renal tissues was up-regulated in group AKI ( P<0.05), and no significant change was found in the parameters mentioned above in group CON-A( P>0.05). Compared with group AKI, the serum BUN and Cr concentrations were significantly decreased, the area of renal fibrosis was reduced, and the expression of FN, Col-Ⅰ, α-SMA and CD206, Arg-1 and FIZZ1 mRNA in renal tissues was down-regulated in group AKI-A ( P<0.05). Conclusion:IL-4 is involved in the process of renal fibrosis following AKI, and the mechanism may be associated with the regulation of macrophage M2 polarization in mice.