Demethylation of ITGAL (CD11a) regulatory sequences in systemic lupus erythematosus

Abstract

Objective. Inhibition of T cell DNA methylation causes autoreactivity in vitro and a lupus-like disease in vivo, suggesting that T cell DNA hypomethylation may contribute to autoimmunity. The hypomethylation effects are due, in part, to overexpression of lymphocyte function-associated antigen 1 (LFA-1) (CD11a/CD18). Importantly, T cells from patients with active lupus have hypomethylated DNA and overexpress LFA-1 on an autoreactive subset, suggesting that the same mechanism could contribute to human lupus. The present study investigated the nature of the methylation change that affects LFA-1 expression in vitro and in human lupus.Methods. Bisulfite sequencing was used to determine the methylation status of the ITGAL promoter and flanking regions in T cells from lupus patients and healthy subjects, and in T cells treated with DNA methylation inhibitors. "Patch" methylation of promoter sequences in reporter constructs was used to determine the functional significance of the methylation changes.Results. Hypomethylation of specific sequences flanking the ITGAL promoter was seen in T cells from patients with active lupus and in T cells treated with 5-azacytidine and procainamide. Patch methylation of this region suppressed ITGAL promoter function.Conclusion. DNA methylation changes occur in specific sequences that regulate LFA-1 expression in lupus T cells and in the hypomethylation model, indicating that altered methylation of specific genes may play a role in the pathogenesis of lupus.The mechanisms initiating human systemic lupus erythematosus (SLE) remain unknown. The finding that exposure to certain drugs can induce a lupus-like disease has provided leads into the nature of biochemical alterations associated with lupus. The 2 drugs most frequently associated with lupus, procainamide and hydralazine, can cause a lupus-like disease through effects on T cell DNA methylation. Treating T cells with procainamide, hydralazine, or 5-azacytidine (5-azaC; the prototypic DNA methylation inhibitor) demethylates DNA, alters gene expression, and induces major histocompatibility complex-specific T cell autoreactivity (1-5). Adoptive transfer of the autoreactive cells causes a lupus-like disease in animal models (5-7). The autoimmune effects of the methylation inhibitors are due, in part, to overexpression of lymphocyte functionassociated antigen 1 (LFA-1) (CD11a/CD18), because increasing T cell LFA-1 by transfection causes an identical autoreactivity in vitro, and a similar autoimmune disease in vivo (4,8).Altered DNA methylation has also been implicated in human lupus. T cells from patients with active lupus have an ϳ17% decrease in genomic deoxymethylcytosine content and overexpress LFA-1 on an autoreactive subset (9-11). However, whether the DNA hypomethylation occurring in lupus affects transcriptionally relevant regions is not known. It is similarly unknown if the DNA hypomethylation induced by 5-azaC or procainamide affects the same sequences as those affected in SLE.DNA methylation inhibitors increase LFA-1 through thei...

Overexpression of CD70 and overstimulation of IgG synthesis by lupus T cells and T cells treated with DNA methylation inhibitors

“…In other studies, our group has used bisulfite sequencing and regional methylation of reporter constructs to characterize how DNA methylation inhibitors and lupus increase CD11a and perforin expression. We found that demethylation of sequences flanking the CD11a promoter increase CD11a expression in vitro and in lupus (12). Similarly, demethylation of a region linking an enhancer and minimal promoter, located 600-800 bp 5Ј of the perforin transcription start site, is responsible for the increase in perforin in vitro and in lupus, although methylation changes also occur elsewhere but are transcriptionally irrelevant (8,9).…”

“…Furthermore, the same LFA-1 and perforin regulatory sequences were shown to be demethylated in CD4ϩ T cells from patients with active SLE as in T cells treated with 5-azaC or procainamide (8,12). Together, these studies suggest that T cell DNA hypomethylation may be fundamental to the pathogenesis of autoimmunity in the adoptive transfer model (4,5) and in humans with drug-induced and idiopathic lupus.…”

“…have decreased levels of total genomic d m C (10), and the same CD11a and perforin sequences demethylate in lupus T cells as in T cells treated with 5-azaC (8,12). We therefore sought to determine whether CD70 is also overexpressed on lupus T cells.…”

Defective T-cell ERK signaling induces interferon-regulated gene expression and overexpression of methylation-sensitive genes similar to lupus patients

“…26 Further, CD4+ T cells from patients with active lupus demethylate the same regulatory sequences, overexpress the same genes, and display the same autoreactive Mø killing and B cell overstimulation as cells demethylated in vitro with 5-azacytidine, procainamide and hydralazine. 17,27,28 Together, these observations suggest that T-cell DNA demethylation may contribute to the development of idiopathic and some forms of drug-induced lupus.…”

The histone demethylase JARID1A is associated with susceptibility to ankylosing spondylitis

“…There is evidence that epigenetic mechanisms may have a role in autoimmune diseases, such as systemic lupus erythematosus where there is hypo-methylation of regulatory regions of pro-inflammatory genes, such as IL-6 and IL-4 in T cells. 13,14 Histone hypomethylation and hypoacetylation in CD4 þ cells from systemic lupus erythematosus patients has also been demonstrated. 15 DNA and histone H3K9 methyla- Odds Ratio (95% confidence interval) Figure 2 Odds ratio meta-analysis plot of rs11062385 in JARID1A (fixed effects).…”