In the pathogenesis of usual interstitial pneumonia (UIP) / idiopathic pulmonary fibrosis (IPF), the central mechanism involves abnormal re-epithelialization after repetitive alveolar injury. The key growth factor released by injured alveolar epithelial cells that drives fibroblast activation and myofibroblast differentiation is:
- A IL-13 and IL-4 via Th2-mediated fibrosis
- B TNF-alpha causing direct fibroblast activation
- C VEGF stimulating angiogenesis rather than fibroblast activation
- D TGF-beta1 (transforming growth factor-beta 1) ✓
Explanation
IPF/UIP is now understood as an epithelial-driven fibrotic disorder. Repetitive microscopic alveolar injury leads to aberrant activation of type II alveolar epithelial cells, which secrete TGF-beta1 as the dominant pro-fibrotic mediator. TGF-beta1 drives fibroblast proliferation, myofibroblast differentiation (alpha-smooth muscle actin expression), and ECM production (collagen deposition). Nintedanib and pirfenidone (current therapies) both inhibit aspects of TGF-beta and related signaling. IL-4/IL-13 drive Th2-type fibrosis in conditions like eosinophilic lung disease. TNF-alpha primarily mediates inflammation.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.