IL10RA signaling deficiency change the anti-inflammatory signature of Ccr2-independent resident macrophages

In adult mice the majority of intestinal macrophages exhibit a mature phenotype and are derived from blood monocytes. In the steady state replenishment of these cells is reduced in the absence of the chemokine receptor Ccr2. Within the intestine of mice with colitis there is marked increase in the accumulation of immature macrophages that demonstrate an inflammatory phenotype. However, whether Ccr2 is necessary for the accumulation of these immature macrophages and further for the development of colitis in susceptible mouse models is incompletely defined. Here, we ask whether Ccr2 is necessary for the development of colitis in mice lacking the receptor for IL10. We compared the development of intestinal inflammation in mice lacking IL10RA or both IL10RA and Ccr2. The absence of Ccr2 interfered with the accumulation of immature macrophages in IL10R-deficien mice, including a novel population of rounded submucosal Iba1+ cells and reduced the severity of colitis in these mice. In contrast, the absence of Ccr2 did not reduce augmented inflammatory gene expression observed in mature intestinal macrophages isolated from mice lacking IL10RA. These data suggest that both newly recruited Ccr2-dependent immature macrophages and Ccr2-independent residual mature macrophages contribute to the development of intestinal inflammation observed in IL10R-deficient mice. Overall design: colonic mRNA profile comparisons of 5 week-old wild type (WT), Il10ra -/- and Il10ra -/-, Ccr2 -/- mice