Transcription factor T-bet regulates skin sclerosis through its function in innate immunity and via IL-13

Proc Natl Acad Sci U S A. 2007 Feb 20;104(8):2827-30. doi: 10.1073/pnas.0700021104. Epub 2007 Feb 16.

Abstract

Tissue remodeling with fibrosis is a predominant pathophysiological mechanism of many human diseases. Systemic sclerosis is a rare, often lethal, disorder of unknown etiology manifested by dermal fibrosis (scleroderma) and excessive connective tissue deposition in internal organs. Currently, there are no available antifibrotic therapeutics, a reflection of our lack of understanding of this process. Animal models of scleroderma are useful tools to dissect the transcription factors and cytokines that govern fibrosis. A disproportionate increase of type 2 cytokines, like TGF-beta and IL-4, more than type 1 cytokines, like IFN-gamma, is thought to underlie the pathogenesis of scleroderma. In this study, we show that mice deficient in the transcription factor T-box expressed in T cells (T-bet), a master regulator of type 1 immunity, display increased sensitivity to bleomycin-induced dermal sclerosis. Despite the well-established role of T-bet in adaptive immunity, we also show that RAG2(-/-) mice, which lack T and B cells, are vulnerable to bleomycin-induced scleroderma and that RAG2/T-bet double-deficient mice maintain the increased sensitivity to bleomycin observed in T-bet(-/-) mice. Furthermore, overexpression of T-bet in T cells does not affect the induction of skin sclerosis in this model. Lastly, we show that IL-13 is the profibrotic cytokine regulated by T-bet in this model. Together, we conclude that T-bet serves as a repressor of dermal sclerosis through an IL-13-dependent pathway in innate immune cells. T-bet, and its transcriptional network, represent an attractive target for the treatment of systemic sclerosis and other fibrosing disorders.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bleomycin
  • Cytokines / metabolism
  • Fibrosis
  • Immune System
  • Immunity, Innate / immunology*
  • Interleukin-13 / deficiency
  • Interleukin-13 / metabolism*
  • Mice
  • Mice, Inbred BALB C
  • Mice, Knockout
  • Scleroderma, Systemic / chemically induced
  • Scleroderma, Systemic / pathology
  • Sclerosis
  • Skin / pathology*
  • T-Box Domain Proteins / deficiency
  • T-Box Domain Proteins / metabolism*

Substances

  • Cytokines
  • Interleukin-13
  • T-Box Domain Proteins
  • T-box transcription factor TBX21
  • Bleomycin