NOS2 and pulmonary emphysema: CS-induced emphysema mice showed increased NOX2 (smoke group: 3.76-fold higher; P<0.001), ARG1 (smoke group: 1.54-fold higher; P<0.001), and INOS (smoke group: 2.68-fold higher; P<0.001) expression than the control group in the small intestine (Figure 6A); however, decreased NOX2 (smoke group: 0.48-fold higher; P<0.001) and ARG1 (smoke group: 0.61-fold higher; P<0.001) in the colon (Figure 6B).