Objective To investigate the role of IL-6/STAT3 signaling in Th17/Tr imbalance of Kawasaki disease(KD). Methods Forty-eight children with KD and eighteen age-matched healthy children were consented to participate in this study. Protein concentration of IL-6 in plasma was measured by ELISA. Transcriptional levels of IL-17A, IL-17F, RORγt, Foxp3, SOCS1 and SOCS3 were assessed by real-time PCR. The proportion of CD4+CD25+Foxp3+ regulatory T(Tr) cells and mean fluorescence intensity(MFI) for phosphorylated-STAT3(pSTAT3) protein in CD4+ T cells was analyzed by flow cytometry. A quantitative methylation specific PCR based on SYBR Green was used to evaluate methylation status of CpG islands in SOCS1 exon2, three potential bind sites for STAT3 in 5'-untraslated region(5'-UTR) of SOCS3 in CD4+ T cells. Results (1)Compared with healthy volunteers, plasma IL-6 concentration and MFI for pSTAT3 in CD4+ T cells were elevated significantly during acute phase of KD[IL-6:(54.02±20.58) pg/ml vs (8.72±2.06) pg/ml, P<0.05;pSTAT3 MFI:(55.41±15.08) vs (9.35±3.76), P<0.05], and the two items in KD patients with coronary artery lesion (KD-CAL+) were found to be higher than those in KD patients without coronary artery lesion (KD-CAL-)[IL-6:(84.76±29.35) pg/ml vs (38.65±13.76) pg/ml, P<0.05;pSTAT3 MFI:(72.36±16.81) vs (46.93±13.57), P<0.05]. (2)Transcription levels of IL-17A, IL-17F and RORγt in patients with KD were significantly elevated (P<0.05) while the proportion of CD4+CD25+Foxp3+ Treg and expression levels of Foxp3 were detected to be lower than those in normal controls (P<0.05). The mRNA levels of IL-17A, IL-17F and RORγt in KD-CAL+ group were higher than those in KD-CAL- group(P<0.05), as well as expression level of Foxp3 were found to be lower in KD-CAL+ group(P<0.05). (3)The mRNA levels of SOCS1 and SOCS3 in CD4+ T cells increased significantly during acute phase of KD(P<0.05), while the two items in KD-CAL+ group were lower than those in KD-CAL- group(P<0.05). Furthermore, CpG islands in SOCS1 exon2 and the third potential bind site for STAT3 in SOCS3 5'-UTR were hypomethylated in acute KD, while those in healthy controls were fully demethylated(P<0.05). Demethylation levels of SOCS1 exon2 and the third potential bind site for STAT3 in SOCS3 5'-UTR in KD-CAL+ group were lower than those in KD-CAL- group(P<0.05). CpG islands in the other two bind sites for STAT3 in SOCS3 5'-UTR were fully demethylated among all the groups(P>0.05). ConclusionAberrant activation of IL-6/STAT3 signaling caused by hypomethylation of SOCS1 and SOCS3 might be one contributing factor to unbalance of Th17/Tr in KD.

Objective To investigate the effect of SOCS1 and SOCS3 hypomethylation on homeostasis of Th1/Th2 in Kawasaki disease(KD). Methods Thirty-six children with KD and sixteen age-matched healthy children consented to participate in this study. Protein concentration of IL-6 in plasma was measured by ELISA. Transcriptional levels of SOCS1, SOCS3, T-bet, IFN-γ, GATA3 and IL-4 were assessed by realtime PCR. The proportion of Th1 and Th2 cells, and mean fluorescence intensity(MFI)for phosphorylated STAT3(pSTAT3)protein in CD4+ T cells was analyzed by flow cytometry. A quantitative methylation specific PCR based on SYBR Green was used to evaluate methylation status of CpG islands in SOCSl exon2, and three potential binding sites for STAT3 in 5'-untraslated region(5'-UTR)of SOCS3 in CD4+T cells. Comparisons between groups were performed with t-test. Results ①Compared with healthy volunteers, plasma IL-6 concentration[(51.8±16.3)pg/ml vs(8.6±2.0)pg/ml, respectively]and MFI for pSTAT3[(52±14)vs(10±4), respectively]in CD4+ T cells were elevated significantly during acute phase of KD(P＜0.05), and the two items in KD patients with coronary artery lesion(KD-CAL+)were found to be higher than those in KD patients without coronary artery lesion(KD-CAL-)[IL-6:(87.2±27.4)pg/ml vs(36.2±12.8)pg/ml, P＜0.05; pSTAT3 MFI:(75±15)vs(42±11), P＜0.05]. ② The proportions of Th1 and Th2 cells and transcription levels of Th-associating factors(T-bet, IFN-γ, GATA3 and IL-4)in CD4+ T cells increased significantly in acute KD(P＜0.05), while the rate of Thl div Th2 in KD patients was found to be lower than that in normal controls(P＜0.05). In addition, the proportions of Th1 and Th2 cells and expressions levels of Th-associating factors in KD-CAL+ group were higher than those in KD-CAL-group, as well as the rate of Thl div Th2 cells in KD -CAL+ group were lower than that in KD-CAL- group(P＜0.05). ③ The mRNA levels of SOCSl and SOCS3 in CD4+ T cells increased significantly during acute phase of KD(P＜0.05), while the two items in KDCAL+ group were lower than those in KD-CAL- group(P＜0.05). Furthermore, CpG islands in SOCSl exon2 and the third potential binding site for STAT3 in SOCS3 5'-UTR were hypomethylated in acute KD, while those in healthy volunteers were fully demethylated(P＜0.05). Demethylation levels of the two items mentioned above in the KD-CAL+ group were lower than those in the KD-CAL-group(P＜0.05). CpG islands in the other two binding sites for STAT3 in SOCS3 5'-UTR were fully demethylated among all the groups(P＞0.05).Conclusion Relative insufficiency of SOCS1 and SOCS3 expression caused by hypomethylation may be one contributing factor for the imbalance of Th1/Th2 in KD.