Hypomethylation of perforin regulatory elements in CD4+ T cells from rat spleens contributes to the development of autoimmune emphysema.

BACKGROUND AND OBJECTIVE

It is widely accepted that perforin regulatory elements are hypomethylated in CD4+ T cells from patients with active lupus, but whether this is the case in autoimmune emphysema is not known.

METHODS

Twenty rats were randomly divided into a normal control group and an emphysema group. Rat models of emphysema were established by intraperitoneal injection with xenogeneic endothelial cells. The levels of tumour necrosis factor-α, interleukin-8 and matrix metalloproteinase (MMP)-9 in bronchoalveolar lavage fluid (BALF) were measured, lung mean linear intercept and destructive index measured. Mean methylation of perforin gene promoter in CD4+ T cells and the expression of perforin were investigated. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling methods were used to examine the percentage of apoptotic cells in the alveolar septa.

RESULTS

The levels of MMP-9 in BALF were higher in emphysema group than in control group (P < 0.05). The mean linear intercept and destructive index were higher in emphysema group than in control group (P < 0.05). The mean perforin gene promotor methylation of emphysema group was significantly decreased as compared with control group, while the expression levels of perforin gene were relatively higher (P < 0.05). There were more terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling-positive cells in the alveolar septa in control group than in emphysema group.

CONCLUSIONS

Hypomethylation of perforin regulatory elements in CD4+ T cells may result in the lung septal cell apoptosis associated with the development of experimental autoimmune emphysema. MMP-9 may play an important role in the pathogenesis of this kind of disease.