Expressions of CD70 mRNA and protein and methylation status of CD70 gene promoter in T cells from patients with systemic lupus erythematosus / 中华皮肤科杂志

ABSTRACT

Objective To detect the expressions of CD70 mRNA and protein and to determine the methylation status of CD70 gene promoter in T cells from patients with systemic lupus erythematosus (SLE).Methods Peripheral blood CD4+ and CD8+ T cells were isolated from 15 patients with active SLE,15 patients with inactive SLE and 15 healthy control subjects.Real-time quantitative reverse transcription-PCR was carried out to quantify the mRNA expression of CD70,flow cytometry to determine the frequency of CD4+CD70+ and CD8+ CD70+ T cells,and bisulfite sequencing to evaluate the methylation status of CD70 gene promoter in CD4+ and CD8+ T cells.Differences in these parameters among these groups were analyzed by one-factor analysis of variance and SNK-q test.Results Compared with the healthy controls,the patients with active SLE and inactive SLE showed a significant increase in CD70 mRNA expression in CD4+ T cells (0.82 ± 0.12 and 0.73 ± 0.11 vs.0.45 ±0.09,F =53.017,P ＜ 0.01) and in the frequency of CD70+CD4+ T cells (80.30％ ± 11.04％ and 66.80％ ± 3.98％ vs.12.48％ ± 3.45％,F =311.517,P ＜ 0.01).Also,the expression of CD70 mRNA in CD4+ T cells and the frequency of CD70+CD4+ T cells were significantly higher in patients with active SLE than in patients with inactive SLE (both P ＜ 0.05).There was a positive correlation between the frequency of peripheral CD70+CD4+ T cells and disease activity in SLE in these patients (r =0.792,P ＜ 0.01).The average methylation index of the region between-600 bp and-300 bp of CD70 gene promoter in CD4+ T cells was 0.32 ± 0.05 and 0.36 ± 0.05 respectively in the patients with active and inactive SLE,significantly lower than that in the healthy controls (0.62 ± 0.05,F =152.64,P ＜ 0.01),and the patients with active SLE showed a significantly lower methylation index than those with inactive SLE (P ＜ 0.05).Conclusions The CD70 gene promoter in CD4+ T cells is significantly hypomethylated in patients with SLE,which may directly lead to the overexpression of CD70.