In vitro and in vivo down-regulation of regulatory T cell activity with a peptide inhibitor of TGF-beta1.

Down-regulation of CD4+CD25+ regulatory T (Treg) cell function might be beneficial to enhance the immunogenicity of viral and tumor vaccines or to induce breakdown of immunotolerance. Although the mechanism of suppression used by Treg cells remains controversial, it has been postulated that TGF-beta1 mediates their immunosuppressive activity. In this study, we show that P17, a short synthetic peptide that inhibits TGF-beta1 and TGF-beta2 developed in our laboratory, is able to inhibit Treg activity in vitro and in vivo.

Identification of peptide inhibitors of transforming growth factor beta 1 using a phage-displayed peptide library.

Pathologies such as liver fibrosis and scleroderma are characterized by harmful levels of transforming growth factor beta 1 (TGFbeta1). These levels could be neutralized if inhibitors of this cytokine were available. With this aim we searched for peptides with binding affinity for TGFbeta1 using a phage-displayed random 15-mer peptide library.