Skip to main content
. Author manuscript; available in PMC: 2009 Jun 26.
Published in final edited form as: Nat Rev Immunol. 2004 Aug;4(8):583–594. doi: 10.1038/nri1412

Figure 2. Opposing roles for TH1 and TH2 cytokines in fibrosis.

Figure 2

The T helper 1 (TH1)-cell cytokine interferon-γ (IFN-γ) directly suppresses collagen synthesis by fibroblasts. It achieves this through regulating the balance of matrix metalloproteinase (MMP) and tissue inhibitor of matrix metalloproteinase (TIMP) expression, thereby controlling the rates of collagen degradation and synthesis, respectively, in the extracellular matrix. IFN-γ and/or interleukin-12 (IL-12) might also indirectly inhibit fibrosis by reducing pro-fibrotic cytokine expression by TH2 cells. The main TH2 cytokines (IL-4, IL-5 and IL-13) enhance collagen deposition by various mechanisms; however, IL-13 seems to be the crucial mediator.