ARG1 and asthma: ARG1 was shown to contribute to asthma pathogenesis by inhibiting nitric oxide production, modulating fibrosis, regulating arginine metabolism and inhibiting T cell proliferation, and it involves the initiation of adaptive T helper 2 cell‐mediated allergic lung inflammation by regulating group 2 innate lymphoid cells 57, 58, 59, 60, whereas ARG1 ablation in the lung may enhance peripheral lung function but have little effect on airway inflammation 61.