Regulation of TGFβ in the immune system: An emerging role for integrins and dendritic cells

Regulation of an immune response requires complex crosstalk between cells of the innate and adaptive immune systems, via both cell-cell contact and secretion of cytokines. An important cytokine with a broad regulatory role in the immune system is transforming growth factor-beta (TGF-beta). TGF-beta is produced by and has effects on many different cells of the immune system, and plays fundamental roles in the regulation of immune responses during homeostasis, infection and disease. Although many cells can produce TGF beta, it is always produced as an inactive complex that must be activated to bind to the TGF beta receptor complex and promote downstream signalling. Thus, regulation of TGF beta activation is a crucial step in controlling TGF beta function. This review will discuss how TGF beta controls diverse immune responses and how TGF beta function is regulated, with a focus on recent work highlighting a critical role for the integrin alpha v beta 8 expressed by dendritic cells in activating TGF beta. (C) 2012 Elsevier GmbH. All rights reserved.