The role of T cell differentiation in the immunopathogenesis of Kawasaki disease (KD) remains unclear. The aim of this study is to elucidate the role of T cell subsets in coronary artery lesion (CAL) of KD. Peripheral blood was obtained in 10 patients with acute KD before and 1 week after intravenous gamma-immunoglobulin (IVIG) treatment and in 20 patients with past history of KD for more than 5~20 years. Meanwhile, induction of coronary arteritis was performed on wild type BALB/c mice by Lactobacillus casei cell wall extract (LCWE). Human peripheral blood leukocytes were analyzed by using flow cytometric analysis and murine hearts were examined for immunofluorescence study and for RNA expression levels.
Results: Compared to the febrile controls, KD patients prior to IVIG treatment had increased percentage of CD3+/CD4+/interferon-γ+ (T helper 1, Th1) cells and CD3+/CD4+/interleukin-17A+ (Th17) cells (mean ± SD, 1.36% ± 1.39% and 0.51% ± 0.25%, respectively) among Th cells (CD3+/CD4+). Both increases declined after IVIG treatment (0.71% ± 0.74% and 0.33% ± 0.18%) despite no statistically difference by Mann-Whitney test. None of these 10 acute KD patients developed CAL after IVIG treatment. However, patients with previous KD and definite CALs (n= 11) seemed to have higher percentage of Th17 cells (0.50% ± .025% versus 0.35% ± 0.23%) but similar level of Th1 cells (0.93% ± 0.51% versus 1.05% ± 0.64%) when compared to those without CAL (n= 9). Murine cardiac tissues displayed the presence of Th1 (double-stained with CD3 and T-bet) and Th17 cells (double-stained with CD3 and RORγt) during days 7 and 14 after LCWE treatment but not in PBS-treated mice. Compatible with these, cardiac mRNA levels showed both increased levels of IFN-γ and IL17A mRNA in LCWE-treated mice.
Conclusions: Our initial data suggests that specific T cell differentiation into Th1 and Th17 cells occurred in both human KD and mice stimulated with LCWE. IVIG treatment was associated with the recovery of such T cell differentiation. However, the clinical application to predict IVIG responsiveness and future CAL development by such increase in the peripheral Th17 remains unclear. Further studies to elucidate the detailed immune regulation of these T subsets on CAL are warrant by using this LCWE murine model.