MMP9 and pemphigus foliaceus: ELISA analysis showed that AAV9-Tspyl2 treatment significantly decreased the concentrations of hydroxyproline and matrix metalloproteinase-9 (MMP-9) in the lung tissues and TGF-β1 in the bronchoalveolar lavage fluid (BALF) of mice in the BLM-induced PF model (Fig. 8C).