Modification and significance of histone acetylation associated with interleukin-4 gene in pediatric Kawasaki disease

Objective To investigate the histone acetylation of interleukin-4(IL-4) gene and its roles in immunological pathogenesis of Kawasaki disease (KD). Methods Thirty-six children with KD and 28 age-matched healthy children in Shenzhen Children′s Hospital from October 2016 to December 2018 were recruited in this study.Peripheral venous blood samples were collected from healthy controls (28 cases) and patients with KD during acute phase and 4 to 5 days after effective intravenous immunoglobulin (IVIG) treatment.Co-immunoprecipitation followed by real-time PCR was used to assess histone H4 acetylation levels of IL-4 promoter and Va enhancer, and binding abilities of p300 and CREB-binding protein (CBP) with promoter and Va enhancer of IL-4 gene in peripheral blood CD4+ T cells.Flow cytometry was performed to analyze the proportion of CD4+ IL-4+ T cells (Th2) and protein le-vels of phosphorylated signal transducer and activator of transcription 6 (pSTAT6), GATA binding protein 3 (GATA3), nuclear factor 1 of activated T cells(NFAT1), transforming growth factor-β receptor Ⅱ (TGF-βRⅡ), and phosphorylated L-type amino acid transporter 1(pLAT1). Quantitative real-time PCR was used to evaluate the transcription levels of IL-4, IL-5, IL-13, IL-4 receptor α (IL-4Rα), transforming growth factor-β receptor Ⅰ (TGF-βRⅠ) and sex-determining region Y(SRY)-box 4 (SOX4) in CD4+ T cells.Plasma concentrations of IL-4 and transforming growth factor-β(TGF-β) were measured by enzyme-linked immunosorbent assay. Results (1)Compared with control group, the proportion of Th2 cells, expression levels of Th2-associated cytokines (IL-4, IL-5 and IL-13) and histone H4 acetylation levels associating with IL-4 promoter and Va enhancer, increased remarkably during acute KD(all P<0.05), and restored after IVIG therapy(all P<0.05). Meanwhile, all the former items in KD patients with coronary artery lesions (CAL) were higher than those in patients with non-coronary artery lesions (NCAL) (all P<0.05). (2) Compared with control group, binding abilities of p300 and CBP with IL-4 promoter and Va enhancer in CD4+ T cells were up-regulated significantly during acute KD (all P<0.05), and decreased in varying degrees after IVIG treatment (all P<0.05). Positive correlations between binding abilities of p300 with IL-4 (promoter and Va enhancer) and the expression of IL-4 promoter and Va enhancer were detected in patients with acute KD (r=0.72, 0.43, all P<0.05). Furthermore, binding abilities of p300 and CBP with IL-4 promoter and Va enhancer in CAL group were higher than those in NCAL group (all P<0.05). (3) Compared with control group, patients with acute KD had remarkably increased plasma concentration of IL-4, and expression levels of IL-4Rα/STAT6/GATA-3 and pLAT1/NFAT1 in CD4+ T cells (all P<0.05), and significantly down-regulated plasma concentration of TGF-β and expression level of TGF-βRⅡ/TGF-βRⅠ/SOX4 (all P<0.05). All the items mentioned above restored in varying degrees after IVIG treatment (all P<0.05). Simultaneously, the 6 items aforementioned in CAL group were found to be higher than those in NCAL group (all P<0.05), while the latter four items were lower than those in NCAL group (all P<0.05). Conclusion Histone hyperacetylation of IL-4 gene may be related to immune dysfunction in patients with KD. Key words: Kawasaki disease; Type Ⅱ helper T cells; Cytokine; Histone acetylation; Immune