Altered chemokine receptor expression in the peripheral blood lymphocytes in polymyositis and dermatomyositis

To examine the expression of chemokine receptors in different peripheral blood T-cell subsets in patients with polymyositis (PM) and dermatomyositis (DM).

We used flow cytometry to measure the frequencies of chemokinereceptors CXCR3 and CCR4 expression in the CD4⁺ or CD8⁺ lymphocytes. Enzyme linked immunosorbent assays were also used to measure the concentrations of C-X-C motif chemokine 10 (CXCL10), thymus and activation regulated chemokine (TARC) and macrophage derived chemokine (MDC).

Comparing to 20 healthy controls, %CD4⁺CXCR3⁺ and %CD8⁺CXCR3⁺ T cells significantly decreased in 33DM patients, and %CD8⁺CXCR3⁺ cells decreased in 24PM patients, but %CD4⁺CCR4⁺ and %CD8⁺CCR4⁺ cells did not significantly change in both the PM and DM patients. Accordingly, the Th1/Th2 polarization, analyzed as the balance obtained after dividing %CD4⁺CXCR3⁺ cells by %CD4⁺CCR4⁺ cells, showed a significant reduction in DM. The serum concentration of CXCR3⁺ ligand, CXCL10, significantly increased and negatively correlated with circulating %CD4⁺CXCR3⁺ cells in DM patients. There was no significant change of TARC and MDC in PM and DM patients. Furthermore, %CD4⁺CXCR3⁺ cells decreased more severely in the patients with interstitial lung disease.

The present results indicate that the distributions of circulating CXCR3⁺ T-cells differ among the PM and DM cases. Our findings suggest a pathogenic difference between PM and DM.