APLN and pulmonary arterial hypertension: Intriguingly, apelin has been shown to prevent and alleviate crystalline silica-induced pulmonary fibrosis through inhibition of transforming growth factor-β (Shen et al., 2023), suggesting that apelin agonists might have synergistic effects when used with the transforming growth factor-β ligand trapping therapy, sotatercept, which is on track for FDA approval in PAH (Torbic and Tonelli, 2024).