No abstract

About 13% of the Japanese adult population-approximately 13.3 million people-were predicted to have CKD in 2005.

Fibrocytes are a distinct population of bloodborne cells that share markers of leukocytes as well as mesenchymal cells. We hypothesized that CCR7-positive fibrocytes migrate into the kidney in response to secondary lymphoid tissue chemokine (SLC͞CCL21) and contribute to renal fibrosis. To investigate this hypothesis, renal fibrosis was induced by unilateral ureteral obstruction in mice. A considerable number of fibrocytes dual-positive for CD45 and type I collagen (ColI) or CD34 and ColI infiltrated the interstitium, reaching a peak on day 7. Most fibrocytes were positive for CCR7, and CCL21͞CCR7 blockade reduced the number of infiltrating fibrocytes. CCL21 and MECA79 dual-positive vessels were also detected in the interstitium. The blockade of CCL21͞CCR7 signaling by anti-CCL21 antibodies reduced renal fibrosis, which was confirmed by a decrease in fibrosis in CCR7-null mice with concomitant reduction in renal transcripts of pro ␣1 chain of ColI and TGF-␤1. The number of F4͞80-positive macrophages decreased along with renal transcripts of monocyte chemoattractant protein 1 (MCP-1͞ CCL2) after the blockade of CCL21͞CCR7 signaling. These findings suggest that CCR7-positive fibrocytes infiltrate the kidney via CCL21-positive vessels, thereby contributing to the pathogenesis of renal fibrosis. Thus, the CCL21͞CCR7 signaling of fibrocytes may provide therapeutic targets for combating renal fibrosis.kidney ͉ CD45

Fibrosis is a hallmark of progressive organ diseases. Monocyte chemoattractant protein (MCP)-1, also termed as macrophage chemotactic and activating factor (MCAF/CCL2) and its receptor, CCR2 are presumed to contribute to progressive fibrosis. However, the therapeutic efficacy of MCP-1/CCR2 blockade in progressive fibrosis remains to be investigated. We hypothesized that blockade of CCR2 may lead to the improvement of fibrosis. To achieve this goal, we investigated renal interstitial fibrosis induced by a unilateral ureteral obstruction in CCR2 gene-targeted mice and mice treated with propagermanium or RS-504393, CCR2 inhibitors. Cell infiltrations, most of which were F4/80-positive, were reduced in CCR2 knockout mice. In addition, dual staining revealed that CCR2-positive cells were mainly F4/80-positive macrophages. Importantly, CCR2 blockade reduced renal interstitial fibrosis relative to wild-type mice. Concomitantly, renal transcripts and protein of MCP-1, transforming growth factor-␤, and type I collagen were decreased in CCR2-null mice. Further, this CCR2-dependent loop for renal fibrosis was confirmed by treatment with CCR2 antagonists in a unilateral ureteral obstruction model. These findings suggest that the therapeutic strategy of blocking CCR2 may prove beneficial for progressive fibrosis via the decrease in infiltration and activation of macrophages in the diseased kidneys. Fibrosis is characteristic in progressive diseases, resulting in organ failure. Monocyte chemoattractant protein (MCP)-1 (also termed as monocyte chemotactic and activating factor/CCL2) is presumed to be a key molecule in chemotaxis and activation of macrophages.

These observations suggest that locally produced MCP-1 may be involved in the development of advanced diabetic nephropathy, especially in the formation of tubulointerstitial lesions possibly through Mphi recruitment and activation. Moreover, up-regulation of MCP-1 may be a common pathway involved in the progressive tubulointerstitial damage in diabetic nephropathy as well as inflammatory renal diseases.