Contractile activity of human decidual stromal cells. II. Effect of interleukin-10

CONTEXT: Human decidual stromal cells (DSC) are myofibroblast-like cells that express alpha-smooth muscle (alpha-SM) actin, a protein associated with cell contractility. Several lines of experimental evidence in humans and mice show that antiinflammatory cytokines favor normal pregnancy, whereas Th1 and inflammatory cytokines play a role in abortion. We previously demonstrated that IL-2, a Th1 cytokine, increased the contractility of human DSC. OBJECTIVE: We studied the effect of the antiinflammatory cytokines IL-10 and IL-4 on the contractility of DSC from first-trimester pregnancy. SETTING AND PATIENTS: We studied 10 healthy women who underwent elective vaginal termination of first-trimester pregnancy at Clínica El Sur, Málaga, and Clínica Ginegranada, Granada. MAIN OUTCOME MEASURE(S): After isolation of DSC, cell contractility was measured with the collagen gel contraction assay. alpha-SM actin was detected with Western blotting and immunofluorescence. RESULTS: We found that IL-10, but not IL-4, increased the volume of the collagen gel matrixes in which the cytokine-treated DSC were cultured, showing that IL-10 decreased DSC contractility. By Western blotting we demonstrated that this effect was not related to an alteration in the synthesis of alpha-SM actin. Nevertheless, we observed by immunofluorescence microscopy that DSC treated with IL-10 exhibited stress fibers with a lower content of alpha-SM actin than untreated control DSC. CONCLUSIONS: IL-10 relaxes DSC by reducing the incorporation of alpha-SM actin into their stress fibers. This relaxing activity may be of relevance for the maintenance of pregnancy.