Neuregulin-1 as a potentially novel biomarker in acute respiratory distress syndrome.

T he investigation of biomarkers in clinical studies can provide insights into mechanistic pathways about a disease or condition, and may help identify potentially novel therapeutic strategies or inform about prognosis or disease progression. In this issue of the European Respiratory Journal, FINIGAN et al. [1] show that high levels of neuregulin-1, a potentially novel biomarker for lung injury, are found in both bronchoalveolar lavage and plasma during the inflammatory phase of acute respiratory distress syndrome (ARDS) in humans. The authors examined levels of neuregulin-1 in bronchoalveolar lavage and plasma in a group of 23 adults with ARDS obtained at day 3 after meeting consensus criteria for ARDS [2] and in five healthy volunteers free of lung disease. They were able to further examine whether levels of neuregulin-1 correlated with markers of inflammation (epidermal growth factor (EGF), interleukin (IL)1b, IL-6, IL-8 and tumour necrosis factor (TNF)-a) and with clinical outcomes such as ventilator-free days. Specifically, they found that levels of neuregulin-1 in bronchoalveolar lavage (187 versus 86 pg?mL, p50.001) and plasma (612 versus 25 pg?mL, p,0.001) were higher in patients with ARDS than in healthy controls. Moreover, they found that levels of neuregulin-1 in bronchoalveolar lavage were positively correlated with TNF-a (p50.03), IL-6 (p50.05) and IL-1b (p50.06), and negatively correlated with ventilator-free days (p50.02). Finally, levels of neuregulin-1 in plasma were also negatively associated with ventilator-free days (p50.04). While the sample size of this study is too small to definitively determine the utility of neuregulin-1 as a biomarker in ARDS, these data provide important preliminary evidence for an association between neuregulin-1 and ARDS, and suggest potential therapeutic targets upstream or downstream of neuregulin-1 shedding.