Inhibition of Transglutaminase 2 by a Selective Small Molecule Inhibitor Reduces Fibrosis and Improves Pulmonary Function in a Bleomycin Mouse Model

This paper investigates the ability of our selective small molecule TG2 inhibitor 1-155 in reducing fibrosis in a bleomycin-induced pulmonary fibrosis mouse model. Formulated as a fine stable suspension, 1-155 was delivered intranasally (IN) at 3 mg/kg via IN delivery once daily. It significantly inhibited collagen deposition in the lungs in the bleomycin-challenged mice. Compared to its vehicle control treatment, a significant reduction in a key myofibroblast marker α smooth muscle actin and TG2 was also detected in the 1-155-treated animals. Most importantly, 1-155 treatment significantly improved several key lung function parameters, such as cord compliance, vital capacity, and dynamic compliance, which are comparable to that found for the positive control nintedanib at a much higher dosage of 60 mg/kg twice daily via oral delivery. The 1-155-treated mice showed a trend in improvement of average body weight. For the first time, our study demonstrates the effectiveness of a selective small molecule TG2 inhibitor in reducing pulmonary fibrosis in a pre-clinical model. Importantly, we were able to correlate this effect of 1-155 with the improvement of animal lung function showing the potential of the use of TG2 inhibitors as a therapeutic treatment for fibrotic lung conditions like IPF.