In particular, classical CD4+ Th cell activation can take part in various phases of selleck inhibitor these diseases 1, 2. The main forms of IBD, Crohn’s disease and ulcerative colitis are characterized by a dysregulated mucosal T-cell response to one or more antigens from the mucosal microflora resulting in chronic inflammation of the intestinal tract. Typically, Crohn’s disease is the consequence of a T helper type 1 lymphocyte-driven immune response characterized by interferon-γ (IFN-γ) and interleukin-17 (IL-17) release 3–5. Despite the emergence of biologicals such as anti-tumor necrosis factor-α (TNF-α) treatment, current treatment of these diseases often involves the use of potent immunosuppressants

such as corticosteroids 6. This treatment strategy has proven very successful to inhibit proliferation and activation

of the inflammatory T cells but is accompanied by a range of side effects. Amongst these side effects are Cushing’s syndrome, stunted growth in children, osteoporosis, diabetes, skin problems and suppression of the hypothalamus–pituitary–adrenal axis, leading to reduction of endogenous cortisol production. In consequence, these side effects warrant the search for a more physiological inhibitor that acts through processes similar to those that daily restrict inflammatory responses under homeostatic conditions. Ideally, physiological inhibitors may exert less toxicity. In the healthy individual, control of inflammation find more involves limitation of responses with respect to location as well as duration. These physiological processes may be

initiated upon apoptosis, cellular damage and subsequent release of tissue-derived molecules that prevent overt damage to the host 7. One class of tissue-derived molecules that has been reported to have regulatory activities is that of the phospholipids. As such, the anionic phospholipid phosphatidylserine that is exposed upon cellular apoptosis was shown to inhibit macrophage-derived release of reactive oxygen intermediates and cytokine production 8. Another phospholipid, phosphatidylcholine, prevented stricture formation in a rat model of colitis when given in a polyunsaturated form 9. In the search for a novel phospholipid immunosuppressant we investigated the immunoregulatory capacities of the natural phospholipid phosphatidylinositol (PI). In our in vivo studies, PI was identified as a potent science inhibitor of a mouse model of colitis. PI is an acidic phospholipid consisting of a phosphatidic acid backbone, linked via the phosphate group to inositol (hexahydroxycyclohexane). Characteristically, the fatty acid of mammalian-derived PI consists of stearic and arachidonic acids. In this study, we pursued to unravel the immunomodulating effect of PI on T cells in light of its potent inhibition of murine colitis. The suppressive capacity of PI was assessed in the classical model of 2,4,6-trinitrobenzene sulfonic acid (TNBS) colitis. Thereto, mice with TNBS-induced colitis were treated with i.p.