In a study in patients with CTD-IP (Interstitial pneumonia in connective tissue diseases), they reported a significant increase in TGF-β1 levels with a decrease in Tregs and a decrease in the ratio of TGF-β1 to IL-6, indicating an increase in endogenous TGF-β1 which is secreted by immune cells in response to the inflammatory microenvironment. Here, TGFB1 is linked to connective tissue disorder.