Therapeutic effect of a peptide inhibitor of TGF-ß on pulmonary fibrosis.

Pulmonary fibrosis encompasses several respiratory diseases characterized by epithelial cell injury, inflammation and fibrosis. Transforming growth factor (TGF)-ß1 is one of the main profibrogenic cytokines involved in the pathogenesis of lung fibrosis. It induces fibroblast differentiation into myofibroblasts, which produce high levels of collagen and concomitantly loss of lung elasticity and reduction of the respiratory function. In the present study, we have investigated the effects of P17 (a TGF-ß inhibitor peptide) on IMR-90 lung fibroblast differentiation in vitro, as well as on the inhibition of the development of bleomycin-induced pulmonary fibrosis in mice. It was found that in IMR-90 cells, P17 inhibited TGF-ß1-induced expression of connective tissue growth factor and α-smooth muscle actin. In vivo, treatment of mice with P17 2days after bleomycin administration decreased lung fibrosis, areas of myofibroblast-like cells and lymphocyte infiltrate. P17 also reduced mRNA expression of collagen type I, fibronectin and the fibronectin splice isoform EDA in the lung, and increased the expression of IFN-γ mRNA. Finally, therapeutic treatment with P17 in mice with already established fibrosis was able to significantly attenuate the progression of lung fibrosis. These results suggest that P17 may be useful in the treatment of pulmonary fibrosis.

Induction of monocyte chemoattractant protein-1 and interleukin-10 by TGFbeta1 in melanoma enhances tumor infiltration and immunosuppression.

Melanoma progression is associated with the expression of different growth factors, cytokines, and chemokines. Because TGFß1 is a pleiotropic cytokine involved not only in physiologic processes but also in cancer development, we analyzed in A375 human melanoma cells, the effect of TGFß1 on monocyte chemoattractant protein-1 (MCP-1) and interleukin-10 (IL-10) expression, two known factors responsible for melanoma progression. TGFß1 increased the expression of MCP-1 and IL-10 in A375 cells, an effect mediated by the cross-talk between Smad, PI3K (phosphoinositide 3-kinase)/AKT, and BRAF-MAPK (mitogen activated protein kinase) signaling pathways. Supernatants from TGFß1-treated A375 cells enhanced MCP-1-dependent migration of monocytes, which, in turn, expressed high levels of TGF,ß1, bFGF, and VEGF mRNA. Moreover, these supernatants also inhibited functional properties of dendritic cells through IL-10-dependent mechanisms. When using in vitro, the TGFß1-blocking peptide P144, TGFß1-dependent Smad3 phosphorylation, and expression of MCP-1 and IL-10 were inhibited. In vivo, treatment of A375 tumor-bearing athymic mice with P144 significantly reduced tumor growth, associated with a lower macrophage infiltrate and decreased intratumor MCP-1 and VEGF levels, as well as angiogenesis. Finally, in C57BL/6 mice with B16-OVA melanoma tumors, when administered with immunotherapy, P144 decreased tumor growth and intratumor IL-10 levels, linked to enhanced activation of dendritic cells and natural killer cells, as well as anti-OVA T-cell responses. These results show new effects of TGFß1 on melanoma cells, which promote tumor progression and immunosuppression, strongly reinforcing the relevance of this cytokine as a molecular target in melanoma.