MCP-1 and RANTES are expressed in renal cortex of rats chronically treated with nitric oxide synthase inhibitor: Involvement in macrophage and monocyte recruitment

Long-term inhibition of nitric oxide synthase (NOS) in rats is known to cause systemic hypertension and renal parenchymal injury. We have previously reported that activation of intra-renal renin-angiotensin system was a major contributing factor for renal injury in chronically NOS-inhibited rats. Massive interstitial infiltration of monocytes/macrophages (M/M) was characteristically seen in this model. The present study was performed to elucidate the role of chemokines, RANTES and MCP-1, in promoting M/M recruitment into the renal cortex. The number of infiltrating ED-1-positive cells was examined in association with the level of expression of RANTES and MCP1 mRNAs in the renal cortex of rats treated orally for 12 weeks with L-NAME. Compared to controls rats, the number of infiltrating ED-1-positive cells was significantly higher in L-NAME-treated rats. The mRNA expressions of both RANTES and MCP-1 were significantly higher in L-NAME-treated rats than the control. In L-NAME-treated rats, the high number of ED-1-positive cells and increased expression of both RANTES and MCP-1 were suppressed by ACE inhibitor, but not by hydralazine. In contrast, neither ED-1 counts nor RANTES mRNA expression were affected by angiotensin (Ang) II type 1 receptor antagonist. These results suggest the likely involvement of RANTES and MCP-1 in the recruitment of M/M into the renal cortex of rats with chronic NOS inhibition. Furthermore, it is also indicated that Ang II stimulates MCP-1 expression via Ang II type 1 receptor, whereas RANTES expression is mediated via Ang II type 2 receptor.