132 - EPIGENOME-WIDE DNA METHYLATION PROFILING OF PERIPHERAL BLOOD SHOWS LYMPHOCYTE DYSFUNCTION IN CHILDREN WITH KAWASAKI DISEASE

Background: Kawasaki disease (KD) is an acute childhood vasculitis, commonly seen in children under the age of 5. Despite the extensive research over the last five decades, the pathogenesis of KD remains elusive.  The objective of this epigenetic re-analysis study is to delineate common pathways involved in KD using a bioinformatic approach.

Methods: Array datasets from the Gene Expression Omnibus repository (NCBI GEO) were extracted and subjected to analysis using the Chip Analysis Methylation Pipeline (ChAMP) in R statistical tool for the identification of differential methylation probes and differential methylation regions. The proportion of granulocytes (neutrophils), macrophages, CD4 T cells, CD8 T cells, B cells, and NK Cells in these datasets were estimated using three deconvolution methods viz. mini, EpiDISH (Epigenetic Dissection of Intra-Sample Heterogeneity), Enmix packages in R statistical tool.

Results: Adaptive immune genes, CD8B, RAG1, IL-7R, STAT1, and CCR7 were significantly hypermethylated in acute KD as compared to healthy controls (figure 1). Gene enrichment analysis showed genes involved in T-cell receptor activation and differentiation, antigen processing and presentation of major histocompatibility complex (MHC) class I were hypermethylated in the acute phase of KD compared to healthy controls. Genes involved in neutrophil degranulation were hypomethylated in acute KD compared to healthy controls. Proportions of neutrophils were significantly increased, while proportions of CD4 T cells and CD8 T cells were decreased in the peripheral blood of children with acute KD as compared to healthy controls (figure 2).  No difference in the proportions of neutrophils, CD8 T cells, and B cells between convalescent KD and healthy subjects except for CD4 T cells. This showed that CD4 T-cells remain at low levels in both the acute and convalescent phases of KD as compared to healthy subjects.

Conclusions: Our findings suggest reduced proportions of CD4 T cells, CD8 T cells, and NK cells, along with hypermethylation of their genes in the peripheral blood of patients with acute KD.