Soluble CD163 serum levels are elevated and correlated with IL-12 and CXCL10 in patients with long-standing rheumatoid arthritis

Abstract

CD163, a membrane glycoprotein restricted to monocyte-macrophage cell lineage, is released in the terminal phase of acute inflammation and during chronic inflammation, with anti-inflammatory and antiangiogenic role. The proteolytically detached ectodomain of CD163 is the soluble component sCD163. A few studies were performed regarding circulating sCD163 in human diseases. Only two were accomplished in patients with rheumatoid arthritis (RA). Our concern was (1) to evaluate sCD163 serum concentrations in active RA patients with long-standing evolution, (2) to correlate them with clinical parameters, laboratory markers, disease activity, and (3) to search possible relationships with some cytokines (IL-12, IL-17) and chemokine (CXCL10), involved in RA pathogenesis. First and third topics were not achieved until now, and the second one points out discordant findings and unspecified aspects. It was achieved immunoassay of serum sCD163, IL-12, IL-17, CXCL10 and traditional methods for RA laboratory markers. The mean sCD163 level of 33 patients was significantly higher than in 20 normal controls (p = 0.0001), 59.3 % of them with concentrations above normal cut-off value. sCD163 levels were weakly correlated with CRP and RF but not with ERS and disease activity. IL-12 and CXCL10 serum levels strongly correlated with sCD163 concentrations, while IL-17 positively but insignificantly correlated. In conclusion, serum sCD163 levels are significantly elevated in long-standing RA patients, but sCD163 has no role as a biomarker of disease activity. High correlation of sCD163 with IL-12 and CXCL10 suggests the association of their well-known anti-inflammatory function in long-standing RA patients.