The identification of a small molecule inhibitor that specifically reduces T cell-mediated adaptive but not LPS-mediated innate immunity by T cell membrane–monocyte contact bioassay

Proinflammatory cytokines such as TNFalpha and IL-1beta are produced in lesional skin of chronic plaque psoriasis patients, and at other sites of chronic inflammation such as arthritic joints. They play vital roles in maintaining inflammation. It has recently been suggested that activated T cell contact-mediated monocyte activation, leading to the production of proinflammatory cytokines, contributes to the pathogenesis of psoriasis and other chronic inflammatory diseases such as psoriatic arthritis and rheumatoid arthritis. Using a T cell membrane-monocyte contact bioassay, we have identified small molecule antagonists that differentially block anti-CD3/anti-CD28 activated T cell-mediated, but not LPS-stimulated, TNFalpha production from monocytes. We selected several kinase inhibitors from the Berlex/Schering kinase library and tested the effect of these compounds in blocking TNFalpha production in the T cell membrane-monocyte contact bioassay. We have demonstrated that one compound BLX-1, from a p38 MAP kinase inhibitor project, inhibited T cell-mediated TNFalpha production from monocytes by about 80%, without any effect on TNFalpha production from LPS-stimulated monocytes. Other BLX-1 analogs showed 32-83% inhibition of TNFalpha production with LPS stimulation as compared to almost 100% inhibition of T cell-mediated TNFalpha production. In contrast, PKC inhibitors BLX-5, Go6983, and Ro-31-8220, inhibited TNFalpha production from both activated T cell membrane- and LPS-stimulated monocytes to the same extent (in the range of 50-100% inhibition). Therefore, the activated T cell membrane-monocyte contact bioassay can be used to screen small molecule antagonists that specifically target adaptive but not LPS-mediated innate immunity. Small molecule TNFalpha inhibitors interfering specifically with activated T cell contact-mediated TNFalpha production from monocytes, but not with LPS-mediated TNFalpha production of myeloid cells, are predicted to have an improved side-effect profile and thus may provide more favorable therapeutics for the treatment of T cell-mediated inflammatory diseases.