Nonsteroidal anti-inflammatory drugs suppress T-cell activation by inhibiting p38 MAPK induction.

In addition to antagonizing inflammation by inhibiting the activity of cyclooxygenases (COX), nonsteroidal anti-inflammatory drugs (NSAID) block T-cell activation. The immunosuppressant activity of NSAID correlates with their ability to block transcription factors required for the expression of inducible response genes triggered by T-cell antigen receptor (TCR) engagement. Whereas the inhibition of nuclear factor-kappaB by aspirin and sodium salicylate can be partly accounted for by their binding to IkappaB kinase-beta, the broad range of transcriptional targets of NSAID suggests that the products of COX activity might affect one or more among the early steps in the TCR-signaling cascade. Here we show that the inhibition of NF-AT activation by NSAID correlates with a selective inhibition of p38 MAP kinase induction. The suppression of TCR-dependent p38 activation by NSAID can be fully overcome by prostaglandin E(2), underlining the requirement for COX activity in p38 activation. Furthermore, the inhibition of COX-1 results in defective induction of the COX-2 gene, which behaves as an early TCR responsive gene. The data identify COX-1 and COX-2 as integral and sequential components of TCR signaling to p38 and contribute to elucidate the molecular basis of immunosuppression by NSAID.