OBJECTIVETo explore the mechanism of pulmonary involvement in ulcerative colitis (UC) patients by observing the correlation between pulmonary functions and levels of alpha1-antitrypsin (A1AT) in serum and colon tissue in UC patients.

METHODSTotally 90 patients with confirmed UC were assigned to different groups according to the extent of disease, the disease activity, the staging of severity, and course of disease. The serum level of A1AT in UC patients with different extent of disease, the disease activity, the staging of severity, and course of disease were compared. And 30 healthy volunteers were recruited as the control group. The serum renal and hepatic functions, pulmonary functions, and serum levels of A1AT were detected in the UC group and the control group. The correlation between A1AT and each pulmonary function index in UC patients was analyzed. The A1AT content in the colon tissue was detected with immunohistochemical assay in 20 UC patients as well as in 10 healthy volunteers.

RESULTSOf the 90 UC patients, 54 patients were accompanied with pulmonary function abnormality (60.0%), and 24 with extraintestinal manifestations (26.7%). Compared with the control group, the serum level of A1AT was significantly lower in the UC group (P < 0.05). The serum level of A1AT was significantly higher in those with proctitis than in those with distal colonitis and pancolitis (P < 0.05). The serum level of A1AT was lower in patients with the course of disease 5 years and more than 5 years than in those with the course of disease less than 5 years (P < 0.05). Vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1.0), total lung capacity (TLC), function residual volume (FRV), and the ratio of diffusion capacity for carbon monoxide of lung (DLCO) were much lower in those with proctitis than in those with distal colonitis and pancolitis (P < 0.05). The ratio of FVC was negatively linear correlated with the course of disease (r = -0.23, P = 0.018). There was a positive correlation between the serum level of A1AT and peak expiratory flow (PEF) (r = 0.22, P = 0.03). The level of A1AT in the colon tissue was obviously lower in the UC patients than in those of the control group (P < 0.05). Mild and moderate UC patients had increased levels of A1AT in the colon tissue, when compared with severe UC patients (P < 0.05). The level of A1AT in the colon tissue was higher in those with proctitis than in those with distal colonitis and pancolitis (P < 0.05).

CONCLUSIONSThe prevalence of pulmonary function impairment was higher than other extraintestinal manifestations in UC patients. The pulmonary function test was helpful to screen the pulmonary impairment of UC patients. The A1AT level in the serum and the colon tissue obviously decreased in UC patients, indicating the pulmonary function impairment of UC patients might manifest as decreased A1AT levels correlated chronic airway inflammation, remodeling of airway, and obstructive changes.