Suramin Attenuates Renal Fibrosis suramin on these processes, we first conducted ED-1 staining, which detects active monocytes/macrophages. Figure 3A showed that monocyte/macrophage infiltration was increased in the remnant kidney compared with the sham-operated kidney (Fig. 3A). Suramin treatment significantly reduced the number of monocytes/macro- phages (Fig. 3A). Next, we determined the expression levels of ED-1 in the kidney tissue by immunoblot analysis. ED1 was detected in the normal kidney, and its levels were increased in the remnant kidney. Suramin treatment also reduced ED1 expression to the basal level in the tissue of the remnant kidney. This data, together with our recent observation that neutrophil numbers are reduced in the obstructed kidney treated with suramin [12], suggest that suramin is also able to suppress infiltration of inflammatory cells into the damaged kidney in chronic injury. Suramin attenuates the expression of MCP-1 and RANTES after renal ablation MCP-1 and RANTES are two chemokines that play an important role in attracting inflammatory cells including mono- cytes/macrophages to sites of inflammation, and contributes to renal interstitial fibrosis [33,34]. In the kidney, tubular epithelial cells (TEC) are considered a prominent source of chemokines [21]. Thus, we examined their expression by immuohistochemistry. A low level of MCP-1 was detected in the sham-operated with or without treatment with suramin (Fig. 4A). However, abundant expression of MCP-1 was detected in the remnant kidney, primarily localized in tubular cells (Fig. 4B). Administration of suramin significantly decreased MCP-1 expression levels (Fig. 4A,B). A basal level of RANTES protein was observed in Figure 3. Effect of suramin on monocytes/microphage accumulation in rat remnant kidney. (A) Photomicrographs (4006) illustrating ED1-stained sections of kidney tissue on week 4 after various treatments as indicated. (B) Kidney tissue lysates were subjected to immunoblot analysis with specific antibodies against ED1 and GAPDH. (C) ED1 staining graphic presentation of quantitative data. (D) Expression levels of ED1 was quantified by densitometry and normalized with GAPDH. Data are represented as the mean 6 S.E.M (n = 6). Means with different superscript letters are significantly different from one another (P,0.05). doi:10.1371/journal.pone.0036194.g003 PLoS ONE | www.plosone.org 4 April 2012 | Volume 7 | Issue 4 | e36194