SIRT1 and pulmonary arterial hypertension: In pulmonary arterial hypertension (PAH), miR-663 b in M1-Exos inhibits the AMPK/Sirt1 signalling pathway in pulmonary artery smooth muscle cells (PASMCs), inducing proliferation, inflammation, oxidative stress, and migration, thereby worsening the disease condition (Ma et al., 2023) (Table 1).