Increased frequency of CCR4+ and CCR6+ memory T-cells including CCR7+CD45RA medvery early memory cells in granulomatosis with polyangiitis (Wegener's)

Abstract

Introduction: Chemokine receptors play an important role in mediating the recruitment of T cells to inflammatory sites. Previously, small proportions of circulating Th1-type CCR5+ and Th2-type CCR3+ cells have been shown in granulomatosis with polyangiitis (GPA). Wondering to what extent CCR4 and CCR6 expression could also be implicated in T cell recruitment to inflamed sites in GPA, we investigated the expression of CCR4 and CCR6 on T cells and its association with T cell diversity and polarization.Methods: Multicolor flow cytometry was used to analyze CCR4, CCR6, and intracellular cytokine expression of T cells from whole blood of GPA-patients (n = 26) and healthy controls (n = 20). CCR7 and CD45RA were included for phenotypic characterization.Results: We found a significant increase in the percentages of circulating CCR4+ and CCR6+ cells within the total CD4+ T cell population in GPA. In contrast, there was no difference in the percentages of CD8+CCR4+ and CD8+CCR6+ T cells between GPA and healthy controls. CCR4 and CCR6 expression was largely confined to central (T CM) and effector memory T cells (T EM, T EMRA). A significant increase in the frequency of CCR4+ and CCR6+ T EMRAand CCR6+ T CMwas shown in GPA. Of note, we could dissect CCR4 and CCR6 expressing CCR7+CD45RA medvery early memory T cells (T VEM) from genuine CCR7+CD45RA highnaïve T cells lacking CCR4 and CCR6 expression for peripheral tissue-migration within the CCR7+CD45RA+ compartment. The frequencies of CCR4+ and CCR6+ T VEMwere also significantly increased in GPA. An increased percentage of IL-17+ and IL-22+ cells was detected in the CCR6+ cell subsets and IL-4+ cells in the CRR4+ cell subset when compared with CD4+ cells lacking CCR4 and CCR6 expression.Conclusions: Increased frequencies of circulating CCR4+ and CCR6+ memory T cell subsets including hitherto unreported T VEMsuggest persistent T cell activation with the accumulation of CCR4+ and CCR6+ cells in GPA. CCR4 and CCR6 could be involved in the recruitment of T cells including cytokine-producing subsets to inflamed sites in GPA. © 2012 Fagin et al.; licensee BioMed Central Ltd.