Expression of ST2, an interleukin-1 receptor homologue, is induced by proinflammatory stimuli.

ST2/T1 is an orphan receptor highly homologous to the IL-1 receptor. Using ST2 cDNA, ST2 specific primers, and a polyclonal antibody generated against ST2, the expression of mRNA and protein corresponding to both the soluble and membrane anchored forms of ST2 was studied. ST2 mRNAs were ubiquitously expressed in all the human tissues examined and were induced by cytokines and phorbol esters. Three different species of mRNAs were observed in different human cells and tissues. In contrast, only two species of ST2 mRNAs were observed in murine Balb/c-3T3 cells and no ST2 mRNA was seen in most tissues of normal mice. However, in a murine model where mouse ears are exposed to UVB irradiation leading to inflammation, ST2 mRNA was expressed 48 h post UV exposure. Similarly, in Balb/c-3T3 cells, the expression of soluble ST2 mRNA and protein was induced by pro-inflammatory stimuli such as TNF, IL-1alpha, IL-1beta and PMA in both exponentially growing and quiescent cells. The expression of the membrane ST2, however, remained constant. These data suggest a role for ST2 in inflammation.