Background & Aims: The role of transforming growth factor (TGF)-β in inhibiting T cell function in the normal gut has been studied in animal models. However, the impact of TGF-β inhibition on T cells in the normal human gut remains poorly understood. We have therefore tested the effect of TGF-β blockade in normal intestinal biopsies grown ex vivo and lamina propria mononuclear cells (LPMCs) on T-bet, a T-box transcription factor required for T helper cell type (Th)1 differentiation, interferon (IFN)-γ production, T-cell apoptosis, and matrix metalloproteinase (MMP)-3 production.
Methods: TGF-β transcripts were determined by qRT-PCR in laser-captured gut epithelium and lamina propria. Biopsies and LPMCs were cultured with anti-TGF-β neutralizing antibody. After 24-h culture, T-bet was determined by immunoblotting and T-cell apoptosis was assessed by flow cytometry. IFN-γ, tumor necrosis factor-α, interleukin (IL)-2, IL-8, IL-10, IL-12p70 and IL-17 were measured by ELISA. MMP-3 and tissue inhibitor of matrix metalloproteinase (TIMP)-1 were assessed by immunoblotting.
Results: A higher number of TGF-β transcripts was found in the lamina propria than epithelium in normal gut. T-bet expression was significantly higher in biopsies and LPMCs cultured with anti-TGF-β antibody than with control antibody. TGF-β blockade down-regulated T-cell apoptosis, and induced a significant increase in IFN-γ, TNF-α, IL-2, IL-6, IL-8, and IL-17 production. A higher expression of MMP-3, but not TIMP-1, was observed in the tissue and supernatant of biopsies treated with anti-TGF-β antibody.
Conclusions: Our findings support a crucial role for TGF-β in dampening T cell-mediated tissue-damaging responses in the human gut.
- Th1 cytokine