What is intestinal lung disease?

From the Guidelines

Intestinal lung disease should be managed with a comprehensive approach that includes treatment of the underlying intestinal condition and specific lung manifestation, with corticosteroids as the first-line treatment, to improve morbidity, mortality, and quality of life. Intestinal lung disease, more accurately known as intestinal lung syndrome or pulmonary manifestations of intestinal diseases, refers to lung complications that can occur in patients with certain gastrointestinal disorders. These complications typically arise from inflammatory bowel diseases (IBD) like Crohn's disease and ulcerative colitis. According to the European evidence-based consensus on extra-intestinal manifestations in inflammatory bowel disease 1, different types of airway disease, involving different parts of the bronchial tree from the glottis to small airways, can occur as an extra-intestinal manifestation of IBD.

The most common pattern of respiratory involvement is airway inflammation, involving the bronchial tree from glottis to small airways, with bronchiectasis being most commonly reported 1. Interstitial lung diseases, including organising pneumonia, non-specific interstitial pneumonia, and usual interstitial pneumonia, have also been described in IBD patients. Treatment depends on the underlying intestinal condition and the specific lung manifestation. For IBD-related lung issues, corticosteroids are often the first-line treatment, with prednisone typically started at 40-60mg daily and tapered over several weeks. Immunomodulators like azathioprine (50-150mg daily) or methotrexate (15-25mg weekly) may be added for maintenance therapy. For severe cases, biological agents such as infliximab (5mg/kg IV at weeks 0,2, and 6, then every 8 weeks) might be necessary.

Key points to consider in the management of intestinal lung disease include:

• Regular pulmonary function tests to monitor for early lung involvement
• Treatment of the underlying intestinal disease to control gut inflammation and improve lung symptoms
• Exclusion of infections and adverse drug reactions as causes of parenchymal lung disease
• Consideration of the potential link between IBD and chronic obstructive pulmonary disease, as well as the association between IBD and interstitial pneumonia. As stated in the European evidence-based consensus on extra-intestinal manifestations in inflammatory bowel disease 1, infections or medication can cause parenchymal lung disease, and respiratory symptoms in patients receiving corticosteroids, immunomodulators, and/or anti-TNF therapy should not be ignored.

From the Research

Intestinal Lung Disease

• Intestinal lung disease is a condition where inflammatory bowel disease (IBD) affects the lungs, leading to various bronchopulmonary problems 2.
• The lung involvement in IBD can manifest as airway inflammation, interstitial lung disease, or other forms of involvement, and can be steroid-sensitive 2.
• Interstitial lung disease (ILD) is a group of pulmonary disorders characterized by inflammation and/or fibrosis of the lung parenchyma, and can be associated with IBD 2, 3, 4, 5.
• The diagnosis of ILD typically involves a multidisciplinary approach, including key history and examination features, blood panel, pulmonary function tests, high-resolution computed tomography imaging, and when required, bronchoalveolar lavage and lung biopsy results 4, 5.
• The management of ILD depends on the underlying cause, and can include antifibrotic therapy, immunomodulatory therapy, structured exercise therapy, oxygen therapy, and lung transplant 3, 4, 5.

Types of Intestinal Lung Disease

• Airway inflammation, including subglottic stenosis, chronic bronchitis, severe chronic bronchial suppuration, bronchiectasis, and chronic bronchiolitis 2.
• Interstitial lung disease, including bronchiolitis obliterans with organizing pneumonia, and pulmonary infiltrates and eosinophilia 2, 3, 4, 5.
• Miscellaneous other forms of involvement, including striking neutrophilic necrotic parenchymal nodules, and serositis 2.

Treatment of Intestinal Lung Disease

• Steroids, including inhaled steroids, oral steroids, and intravenous steroids, can be effective in treating intestinal lung disease 2.
• Antifibrotic therapy, including nintedanib and pirfenidone, can slow the decline in lung function in patients with ILD 3, 4.
• Immunomodulatory therapy, including tocilizumab, rituximab, and mycophenolate mofetil, can slow the decline in lung function in patients with connective tissue disease-associated ILD 3, 4.
• Lung transplant can improve symptoms and resolve respiratory failure in patients with end-stage ILD 3.