FREIBURG, Germany—Changes in the chemokine CCL18 in serum parallel those in bronchoalveolar lavage (BAL) fluid. These changes reflect pulmonary fibrotic activity and might be useful for monitoring disease course and response to therapy in patients with systemic sclerosis (SSc) or idiopathic interstitial pneumonias (IIPs), German researchers report. In data published in Arthritis & Rheumatism,¹ researchers led by Antje Prasse, MD, with the University Hospital, in Freiburg, Germany, show a close correlation between changes in predicted total lung capacity and changes in CCL18 serum concentrations in a cohort of 40 patients followed for at least 6 months.

"In contrast to an approach utilizing BAL neutrophil cell counts, serum CCL18 concentrations are easily determined and repeatable. Furthermore, in contrast to pulmonary function tests, no cooperation of the patient is needed for determinations of CCL18," Dr. Prasse writes.

The investigators measured CCL18 by enzyme-linked immunosorbent assay (ELISA) and expression of CCL18 by flow cytometry in supernatants of cultured BAL cells, in BAL fluid, and in serum samples from 43 patients with IIPs, 12 patients with SSc, and 23 healthy control subjects.

They found that:

• CCL18 production by BAL cells was negatively correlated with total lung capacity
  
• CCL18 concentrations correlated with BAL neutrophil and eosinophil cell counts
  
• the percentage of CCL18-positive macrophages was higher in patients with fibrotic lung diseases
  
• the CCL18 fluorescence intensity per cell increased in patients with fibrotic lung diseases, and
  
• in serial measurements, increases in CCL18 serum concentrations correlated with increases in predicted total lung capacity

"[I]n the course of disease in 40 patients with different IIPs or SSc, we observed a close negative correlation between changes in the total lung capacity and changes in the serum CCL18 concentrations. It therefore appears that the concentration of CCL18 in the serum may serve as an indicator of pulmonary disease activity in patients with pulmonary fibrosis, in both its idiopathic and its rheumatic forms," the authors write.

They conclude that increasing serum CCL18 concentrations reflect the level of fibrotic lung remodeling, regardless of the underlying cause of the pulmonary fibrosis. The investigators believe their findings might be useful in clinical trials of new antifibrotic approaches to treatment.

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Reference

1. Prasse A, Pechkovsky DV, Toews GB, et al. CCL18 as an indicator of pulmonary fibrotic activity in idiopathic interstitial pneumonias and systemic sclerosis. Arthritis Rheum. 2007;56:1685-1693.