Induced sputum eosinophilia in ulcerative colitis patients: The lung as a mirror image of intestine?

Summary 

Background

Ulcerative colitis (UC) is a systemic disease of unknown etiology with extra-intestinal manifestation. Induced sputum (IS) non-invasively assesses extrapulmonary involvement in Crohn's disease. We sought to determine whether there is a cellular marker of lung injury in UC patients detectable by IS.

Methods

Nineteen UC patients (mean age 46.4±11.3 years, disease duration 8.6±7.5 years [range 1–25 years] 68.4% males) were studied, 6 with active disease and 13 in remission. Eleven received 5-ASA, 5 received steroids and/or azathioprine and 3 patients were untreated. UC patients were compared with 27 healthy non-smoker controls. IS was recovered after 20 min inhalation of 3% saline with an ultrasonic nebulizer by the selecting plugs method, and 300 cells were differentially cell counted in cytospin Giemsa-stained slides. CD4/CD8 subsets were identified by FACS. Pulmonary function tests were performed by the Jaeger Masterlab spirometer.

Results

UC patients' IS contained higher %eosinophils than controls (p=0.05) and lower FEV₁/FVC ratios (p=0.001). Steroid- and/or azathioprine-treated patients had significantly lower FEV₁/FVC ratios than only 5-ASA-treated patients (p=0.019). Eosinophil infiltration in airways was high in 5-ASA-treated patients compared to those receiving steroids and/or azathioprine (p=0.046) and those with less extensive disease (p=0.05). Using a cutoff of 3% eosinophils, IS had a sensitivity of 67% and specificity of 73% to differentiate patients with a cutoff of 70eosinophils/mm² in biopsy.

Conclusions

The percentage of sputum eosinophils is significantly different between UC patients with proctitis and pancolitis. These immune abnormalities may be a common pattern that is present throughout the mucosae.

Keywords: Eosinophils, Induced sputum, Ulcerative colitis