Mmp 2

Serum was separated from peripheral blood of healthy individuals or COPD patients within 24 hours of hospitalization. Collection of bronchoalveolar lavage fluid (BALF) was achieved by bronchoalveolar lavage with warm saline by a professional physician operating bronchoscope with a negative pressure of 100 mmHg. Supernatants were obtained by centrifugation in a centrifuge at 2500 rpm at 4°C after 20 minutes of rest at room temperature and stored at −80°C until use. TGF-β (SEA124Hu, Cloud-Clone Corp.) in serum and BALF, SP-A, SP-D (Jianglai Bio, China), MMP-2, MMP-9, and MMP-12 (MLbio, China) in blood were detected using the ELISA method. The steps of reagent addition, incubation, washing, color development and termination were completed according to the instructions, and the final determination was completed with a microplate reader (Bio Tek Instrument, USA) at a wavelength of 450 nm.

The target protein levels in corneal extracts were measured using commercially available ELISA kits in accordance with the manufacturer's protocols. The ELISA kits used in this study include MMP-2 (ml058669; Mlbio, Shanghai, China), TIMP-2 (E-EL-H1453c; Elabscience, Houston, USA), galectin-8 (CSB-EL012894HU; CUSABIO, Wuhan, China), VEGF-C (CSB-E04759h; CUSABIO, Wuhan, China), VEGF-A (CSB-E11718h; CUSABIO, Wuhan, China), COL8A2 (ml204018; Mlbio, Shanghai, China), Bcl-2 (E-EL-H0114c; Elabscience, Houston, USA), MMP-9 (CSB-E08006h; CUSABIO, Wuhan, China), COL12A1 (ml241608; Mlbio, Shanghai, China), fibronectin (ml023813; Mlbio, Shanghai, China), CD31 (E-EL-H1640c; Elabscience, Houston, USA), Bax (E-EL-H0562c; Elabscience, Houston, USA), neuropilin-2 (CSB-EL016092HU; CUSABIO, Wuhan, China), and total laminin (E-EL-H0128c; Elabscience, Houston, USA). The antibodies used in the total laminin ELISA kit were pAbs against all types of laminin α, laminin β, and laminin γ subunits.