Background Interstitial lung disease (ILD) is a major complication of the rheumatic diseases systemic sclerosis (SSc), rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE).

ILD is the consequence of tissue remodelling with increased collagen production in the interstitium and around blood vessels.

The laminin LAMA4 is involved in tissue remodelling. LAMA4 mutant mice develop myocardial and renal fibrosis. The authors studied LAMA4 expression in lung tissue of ILD patients suffering from SLE, SSc and RA.

Material and methods Lung biopsy specimens were obtained from ILD patients who fulfilled the criteria for SLE (n=7), SSc (n=4) and RA (n=5). As negative controls lung tissue from patients without any signs of ILD and a single metastasis of colon cancer (n=5) were used. Immunohistochemistry on paraffin embedded slides was performed for LAMA4 using the monoclonal antibody 2A3. Intensity of staining was scored semiquantitatively.

Results LAMA4 was overexpressed in lung tissue from SLE, SSc and RA patients with ILD. The LAMA4 staining was enhanced in areas around the vessels and around the peripheral alveolar cells. In normal lung tissue LAMA4 expression was hardly detectable.

Conclusion LAMA 4 is expressed in lung tissue from patients with ILD secondary to SLE, SSC and RA. LAMA4 may be a major player in the development of fibrosis. It also may be important for the development of pulmonary arterial hypertension.