Author(s): Ningyan Gu, Chao Luan, Xingfeng Wu, Yan Wang, Mingjun Jiang, Min Chen and Pangeng Cui
Background: It is unclear the metylation status of CpG islands within interleukin-12B (IL-12B) in psoriasis, although increasing evidence indicates that the abnormal DNA methylation is involved in the pathogenesis of psoriasis.
Objective: We investigated the methylation status of IL-12B gene in psoriatic epidermis.
Methods: The DNA specimens were obtained from the involved and uninvolved epidermis of 30 patients with plaque psoriasis and 28 healthy persons as the control group. Methylation of 26 CpG sites in the promoter within IL-12B gene was examined by bisulfite sequencing. The severity of disease was evaluated by psoriasis area and severity index (PASI).
Results: The mean methylation rate in the promoter of IL-12B in involved psoriatic epidermis, uninvolved psoriatic epidermis and healthy control is 0.0230 ± 0.0101, 0.0188 ± 0.0118 and 0.0105 ± 0.0114, respectively. The methylation rate of IL-12B in both involved psoriatic epidermis (p<0.001) and uninvolved psoriatic epidermis (p<0.05) is significantly higher than in healthy controls, respectively. The methylation rate of IL-12B in uninvolved psoriatic epidermis is lower than in involved psoriatic epidermis (p=0.031). The mean methylation rate in involved psoriatic epidermis was correlated to patient PASI scores (r=0.633, p<0.001).
Conclusions: Abnormal methylation in the promoter of IL-12B have been found in psoriatic epidermis, and is associated with severity of the disease, which suggests the promoter methylation of IL-12B may be involved to the pathogenesis of psoriasis.
