The stimulating effect of interleukin-33 on proliferation of the primary human lung fibroblasts

Abstract

Interleukin (IL)-33 is a multifunctional cytokine that belongs to the IL-1 cytokine family and expressed by multiple organs and cell types. Recent studies have showed that IL-33 plays an etiological role in several fibrotic disorders and may be involved in the pathogenesis of chronic respiratory diseases. It has been reported that IL-33–induced cutaneous fibrosis is associated with the increased fibroblast proliferation and altered expression of extracellular matrix-modifying genes. However, the role of IL-33 in regulating of functions of lung fibroblasts remains unclear. In the present study we examined the effect of IL-33 on proliferation of human lung fibroblasts. Five primary lines of normal adult human lung fibroblasts were cultured for 3-7 days in the presence of increasing concentrations of IL-33. We have observed that normal human lung fibroblasts responded in a dose-dependent manner to treatment with recombinant human IL-33 by increasing proliferation rates 1.5- to 2.3 fold compared to the non-stimulated control. The maximum effect of IL-33 on fibroblast proliferation was observed in the cytokine concentrations range from 2 ng/ml to 100 ng/ml. These results suggest that IL-33 may play an important role in the regulation of the human lung fibroblast proliferation. Human lung fibroblasts activated by IL-33 may act as effector cells not only in the pathogenesis of lung diseases, but also in lung remodeling processes.