Overexpression of CD70 and overstimulation of IgG synthesis by lupus T cells and T cells treated with DNA methylation inhibitors.
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 enzyme-linked immunosorbent assay. The results were compared with those of T cells from lupus patients.


RESULTS
SLE T cells and T cells treated with DNA methylation inhibitors overexpressed CD70 and overstimulated B cell IgG production. The increase in IgG synthesis was abrogated by anti-CD70.


CONCLUSIONS
SLE T cells and T cells treated with DNA methyltransferase inhibitors and ERK pathway inhibitors overexpress CD70. This increased B cell costimulation and subsequent immunoglobulin overproduction may contribute to drug-induced and idiopathic lupus.
Oelke
Kurt
K
University of Michigan, Ann Arbor, 48109, USA.
Lu
Qianjin
Q
Richardson
Derek
D
Wu
Ailing
A
Deng
Chun
C
Hanash
Samir
S
Richardson
Bruce
B
D000328:Adult; D000368:Aged; D015703:Antigens, CD / Q000235:genetics*; D001374:Azacitidine / Q000494:pharmacology; D001402:B-Lymphocytes / Q000187:drug effects / Q000502:physiology; D053282:CD27 Ligand; D019175:DNA Methylation / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D015870:Gene Expression / Q000187:drug effects / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism*; D008180:Lupus Erythematosus, Systemic / Q000276:immunology* / Q000503:physiopathology*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D011342:Procainamide / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects / Q000502:physiology*
D015703:Antigens, CD; D053282:CD27 Ligand; C505771:CD70 protein, human; D004791:Enzyme Inhibitors; D007074:Immunoglobulin G; D008565:Membrane Proteins; D010975:Platelet Aggregation Inhibitors; D011342:Procainamide; D001374:Azacitidine