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

Abstract

Objective. Generalized DNA hypomethylation contributes to altered T cell function and gene expression in systemic lupus erythematosus (SLE). Some of the overexpressed genes participate in the disease process, but the full repertoire of genes affected is unknown. Methylation-sensitive T cell genes were identified by treating T cells with the DNA methyltransferase inhibitor 5-azacytidine and comparing gene expression with oligonucleotide arrays. CD70, a costimulatory ligand for B cell CD27, was one gene that reproducibly increased. We then determined whether CD70 is overexpressed on T cells treated with other DNA methylation inhibitors and on SLE T cells, and determined its functional significance.Methods. Oligonucleotide arrays, real-time reverse transcription-polymerase chain reaction, and flow cytometry were used to compare CD70 expression in T cells treated with 2 DNA methyltransferase inhibitors (5-azacytidine and procainamide) and 3 ERK pathway inhibitors known to decrease DNA methyltransferase expression (U0126, PD98059, and hydralazine). The consequences of CD70 overexpression were tested by coculture of autologous T and B cells with and without anti-CD70 and measuring IgG production by enzymelinked immunosorbent assay. The results were compared with those of T cells from lupus patients. Results. SLE T cells and T cells treated with

Unchecked CD70 Expression on T Cells Lowers Threshold for T Cell Activation in Rheumatoid Arthritis

“…DNMT inhibition increased CD70 expression in both cell types; however, the relative difference between CD4 ϩ CD28 Ϫ and CD4 ϩ CD28 ϩ T cells was maintained. In contrast, inhibition of the ERK pathway, which has recently been implicated in modifying methylation patterns of CD4 T cells in SLE patients (29), did not have any effects.…”

“…CD70 overexpression is not only seen in RA patients; it has also been described in SLE (29,48). The mechanisms are different, but the functional consequences appear to be very similar.…”

DNA methylation regulates the expression of CXCL12 in rheumatoid arthritis synovial fibroblasts

“…30 Similar to the approach of our current study it was shown that normal T cells treated with 5-azaC upregulated LFA1, CD70 and perforin and that the CpG islands in the promoters of these genes were hypomethylated in T cells of systemic lupus erythematosus patients. [31][32][33] DNA methylation of promoter sequences can change the binding of transcription factors. …”

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

“…The overexpression of these methylation-sensitive genes such as CD11a, and CD70 is also observed in patients with active lupus as well as in human T cells treated with DNA methylation inhibitors. 15,18 Microarray expression experiments performed on spleen RNA from mice with T-cell ERK signaling defect revealed differential expression of 60 genes. Interestingly, eight genes that are differentially expressed are interferon-regulated genes ( Figure 7).…”

“…[15][16][17] The hypomethylated cells also overstimulate autologous B-cell antibody production, due to demethylation and overexpression of the genes encoding CD70 (TNFSF7), and CD40L (CD40LG). 18,19 Importantly, procainamide and hydralazine, which cause anti-nuclear antibodies in a majority of people and a lupus-like disease in a subset, are DNA methylation inhibitors. 20 Procainamide is a competitive Dnmt1 inhibitor, 21,22 whereas hydralazine inhibits ERK pathway signaling, thereby decreasing Dnmt1 expression.…”