TGF-β in Inflammatory Bowel Diseases: A Tale of the Janus-Like Cytokine

Transforming growth factor-β (TGF-β) is a pleiotropic cytokine that controls an immense number of cellular responses and plays a prominent role in maintaining homeostasis of most human organs. In the intestine, the TGF-β is involved in mucosal defense, immune tolerance, inhibition of acute inflammation, promoting the wound-healing process, and suppressing tumor initiation. However, TGF-β exhibits Janus-like features under certain physiologic conditions and chronic inflammation (e.g., inflammatory bowel diseases [IBDs]). Excessive TGF-β in IBDs favors chronic inflammation, incurs pathologic remolding, and facilitates the progression of colitis-associated inflammation (CAC). Considering the increasingly crucial roles of TGF-Β in the development of IBDs, we overview its pathways and multifaceted effects at the steady-state and IBD conditions of the gut, respectively. In addition, we present potential therapeutic strategies aimed at restoring normal TGF-β signaling in IBDs.