DNA Methylation and Transcription of HLA-F and Serum Cytokines Relate to Chinese Medicine Syndrome Classification in Patients with Chronic Hepatitis B

Abstract

Objective: To explore the molecular bases of Chinese medicine (CM) syndrome classification in chronic hepatitis B (CHB) patients in terms of DNA methylation, transcription and cytokines.

Methods: Genome-wide DNA methylation and 48 serum cytokines were detected in CHB patients (DNA methylation: 15 cases; serum cytokines: 62 cases) with different CM syndromes, including dampness and heat of Gan (Liver) and gallbladder (CHB1, DNA methylation: 5 cases, serum cytokines: 15 cases), Gan stagnation and Pi (Spleen) deficiency (CHB2, DNA methylation: 5 cases, serum cytokines: 15 cases), Gan and Shen (Kidney) yin deficiency (CHB3, DNA methylation: 5 cases, serum cytokines: 16 cases), CHB with hidden symptoms (HS, serum cytokines:16 cases) and healthy controls (DNA methylation: 6 cases). DNA methylation of a critical gene was further validated and its mRNA expression was detected on enlarged samples. Genome-wide DNA methylation was detected using Human Methylation 450K Assay and furthered verified using pyrosequencing. Cytokines and mRNA expression of gene were evaluated using multiplex biometric enzyme-linked immunosorbent assay (ELISA)-based immunoassay and reverse transcription-quantitative polymerase chain reaction (RT-qPCR), respectively.

Results: Totally 28,667 loci, covering 18,403 genes were differently methylated among CHB1, CHB2 and CHB3 (P<0.05 and |Δβ value| > 0.17). Further validation showed that compared with HS, the hg19 CHR6: 29691140 and its closely surrounded 2 CpG loci were demethylated and its mRNA expressions were significantly up-regulated in CHB1 (P<0.05). However, they remained unaltered in CHB2 (P>0.05). Levels of Interleukin (IL)-12 were higher in CHB3 and HS than that in CHB1 and CHB2 groups (P<0.05). Levels of macrophage inflammatory protein (MIP)-1α and MIP-1β were higher in CHB3 than other groups and leukemia inhibitory factor level was higher in CHB1 and HS than CHB2 and CHB3 groups (P<0.05). IL-12, MIP-1α and MIP-1β concentrations were positively correlated with human leukocyte antigen F (HLA-F) mRNA expression (R²=0.238, P<0.05; R²=0.224, P<0.05; R=0.447, P<0.01; respectively). Furthermore, combination of HLA-F mRNA and differential cytokines greatly improved the differentiating accuracy among CHB1, CHB2 and HS.

Conclusions: Demethylation of CpG loci in 5' UTR of HLA-F may up-regulate its mRNA expression and HLA-F expression was associated with IL-12, MIP-1α and MIP-1β levels, indicating that HLA-F and the differential cytokines might jointly involve in the classification of CM syndromes in CHB.

Registration no: ChiCTR-RCS-13004001.

Keywords: Chinese medicine syndrome; DNA methylation; chronic hepatitis B; cytokine; human leukocyte antigen F.