Cytokine production profile of CD4+ T cells from patients with active Churg-Strauss syndrome tends toward Th17.

BACKGROUND

Churg-Strauss syndrome (CSS) is a rare systemic necrotizing vasculitis that develops in some asthma patients. What types of asthma make patients prone to develop this condition remains unknown. We found that inhibition of regulatory T cells (Treg) differentiation, especially by Tr1 cells, due to a decreased ability of responder T cells to generate IL-2, is associated with the onset and pathogenesis of CSS. In contrast, recent evidence suggests that IL-17-producing Th17 cells play a crucial role in autoimmune inflammation. However, few studies have addressed the role of Th17 in the pathogenesis of CSS.

METHODS

Mononuclear leukocytes were obtained from healthy subjects, patients with bronchial asthma (BA), asthma-accompanying chronic eosinophilic pneumonia (BA+CEP) and CSS. The cells were stimulated for 4-5 h with PMA and ionomycin in the presence of brefeldin A to generate and accumulate cytokines. Intracellular cytokines were detected after fixation and permeabilization of these cells. Tr1 cells were evaluated as CD4+CD25+ T cells dominantly producing IL-10 and TGF-beta, nTreg as CD4+CD25+ T cells expressing Foxp3, a master transcriptional factor, and Th17 were also evaluated as CD4+ T cells mainly producing IL-17. Patients with CSS were classified into an active group and an inactive group in accordance with the disease state after treatment.

RESULTS

The frequency of Th17 in peripheral blood was significantly higher in active CSS patients than in healthy subjects, BA, BA+CEP, and inactive CSS patients. In contrast, the Tr1 cell detection frequency was remarkably decreased in active CSS in comparison with BA, BA+CEP, and inactive CSS patients. Also, there was a significant relation between the condition of a given CSS patient and the detection frequencies of both CD4+ helper T cells when CSS cases were divided into inactive and active stages. The Th17 detection frequency was increased in the active stage of CSS, while the Tr1 frequency decreased sharply but then reversed in the inactive stage of CSS.

CONCLUSION

Active CSS patients have elevated intracellular IL-17 and decreased IL-10 levels, which correlate with measures of disease activity, suggesting that Th17 and Tr1 may play important roles in the pathogenesis of CSS.