Abstract:

Objective To investigate the changes and significances of histone 3 acetylation of IFN-γ gene in patients with acute Kawasaki disease(KD). Methods Children with KD were enrolled in Shenzhen Children's Hospital from February 2015 to June 2016, and sub-grouped as with or without coronary artery lesions (CAL). Age-matched healthy children attending routine physical examination were recruited as controls during the same period. Chromatin immunoprecipitation was performed to determine acetylation level of histone 3 of IFN-γ gene, and binding level of histone acetyltransferase p300 and deacetylase HDAC1/2 with IFN-γ gene. The proportion of CD4+IFN-γ+ cells (Th1) and protein levels of IFN-γ, pSTAT4, pSTAT5 and T-bet were analyzed by flow cytometry. Quantitative real-time PCR was used to evaluate the levels of IFN-γ, IL-2Rα/β, IL-12Rβ1/2, IL-18Rα/β and ITLR4 mRNA in CD4+ T cells. Plasma concentrations of IL-12, IL-2 and IL-18 were measured by enzyme-linked immunosorbent assay. Results ① Thirty-eight children with KD, including 16 children with CAL (KD-CAL+) and 22 children without CAL(KD-CAL－), aged from 1 to 5.2 years with a mean of 2.9 years were recruited. The KD group consisted 20 males and 18 females, and 32 age-matched healthy children with 17 males were recruited as controls. No difference of age or sex was found between the two groups(P>0.05). ② The proportion of Th1, levels of IFN-γ protein and mRNA, and acetylation levels of histone 3 of IFN-γ gene increased remarkably during acute KD(P<0.05), and restored after IVIG therapy(P<0.05). Meanwhile, all the four items aforementioned in KD-CAL+ subgroup were higher than those in KD-CAL－ subgroup (P<0.05). ③ During acute KD, binding level of p300 with IFN-γ gene was up-regulated significantly whereas binding level of HDAC1/2 with IFN-γ gene was down-regulated(P<0.05), resulting in the higher ratio of p300/HDAC1/2 that was positive correlated with the acetylation level of IFN-γ gene in patients in acute KD(r=0.52, P<0.05). Moreover, binding level of p300 with IFN-γ gene and the ratio of p300/HDAC1/2 in KD-CAL+ subgroup were higher than those in KD-CAL－ subgroup (P<0.05), while a lower binding level of HDAC1/2 with IFN-γ gene was found in KD-CAL+ subgroup (P<0.05). All the three items mentioned above restored remarkably after IVIG treatment(P<0.05). ④ In comparison with healthy controls, plasma concentration of inflammatory cytokines (IL-2, IL-12 and IL-18), levels of their receptors(IL-2Rα/β, IL-12Rβ1/2, IL-18Rα/β and TLR4) and downstream molecules (pSTAT5, pSTAT4, T-bet and MyD88) were elevated pronouncedly during acute KD(P<0.05), and restored to some extent after IVIG treatment (P<0.05). Simultaneously, all the items mentioned before in KD-CAL+ subgroup were higher than those in KD-CAL－ subgroup (P<0.05). Conclusion Hyper-acetylation of histone of IFN-γ gene might be one of the important factors contributing to immune dysfunction of KD.