Cyclooxygenase-2 inhibition lacks immunomodulatory effects on T cells

In T cells, cyclooxygenase-1 is constitutively expressed, and cyclooxygenase-2 is induced during activation but their functions are not well known. Although exogenous prostaglandins are potent inhibitors of T cell activation, both immunoactivation and immunosuppression have been attributed to cyclooxygenases inhibitors (NSAIDs). Understanding the functions of the cyclooxygenases on T cells is relevant to the therapeutic use of NSAIDs on T cell mediated rheumatic diseases such as rheumatoid arthritis. In this study, we analyze whether cyclooxygenases play a significant role in T cell functions.

Activation, proliferation, and Fas induced apoptosis were analyzed in T cells treated with non-selective (indomethacin) or cyclooxygenase-2 selective (dimethyl-furanone) inhibitors. Intracellular peroxidation was studied in activated T cells by dihydrorhodamine 123 fluorescence analysis of cells treated with COX-2 antisense or control oligonucleotides. COX-2 expression was analyzed by RT-PCR analysis.

Our data show that neither non-selective or selective cyclooxygenase-2 inhibition modify T cell activation, proliferation or apoptosis susceptibility. Furthermore, inhibition of cyclooxygenase-2 expression by antisense oligonucleotides lacks significant effects on T lymphocytes and does not modify their peroxydative capacity.

According to these data, cyclooxygenases do not seem to play a relevant role in T cells functions in vitro. Therefore, the use of either cyclooxygenase-2 selective or non-selective NSAIDs in patients with autoimmune inflammatory diseases is not expected to induce direct immunomodulatory effects through direct effects on T cells.