Clara cell protein in nasal lavage fluid and nasal nitric oxide - biomarkers with anti-inflammatory properties in allergic rhinitis

The levels of CC16 in nasal lavage fluids, achieved from subjects with persistent allergic rhinitis (n = 13), intermittent allergic rhinitis in an allergen free interval (n = 5) and healthy controls (n = 7), were analyzed by Western blot. The levels of nNO were measured by the subtraction method using NIOX？. The occurrences of effector cells in allergic inflammation, i.e. metachromatic cells (MC, mast cells and basophiles) and eosinophils (Eos) were analyzed by light microscopy in samples achieved by nasal brushing.The levels of CC16 correlated with nNO levels (r2 = 0.37; p = 0.02) in allergic subjects.The levels of both biomarkers showed inverse relationships with MC occurrence, as higher levels of CC16 (p = 0.03) and nNO (p = 0.05) were found in allergic subjects with no demonstrable MC compared to the levels in subjects with demonstrable MC. Similar relationships, but not reaching significance, were observed between the CC16 and nNO levels and Eos occurrence. The levels of CC16 and nNO did not differ between the allergic and the control groups.The correlation between nasal CC16 and nNO levels in patients with allergic rhinitis, along with an inverse relationship between their levels and the occurrences of MC in allergic inflammation, may indicate that both biomarkers have anti-inflammatory effects by suppression of cell recruitment. The mechanisms behind these observations warrant further analyses.Clara cell protein (CC16, identical to CC10 and uteroglobin) is a biomarker of high interest in airway diseases. The protein, initially described in the epithelium of the tracheobronchial tree as a secretory product from non-ciliated Clara cells, diffuses passively from the respiratory tract into serum and is excreted via the urinary tract [1]. CC16 is ascribed a protective role against oxidative stress and inflammation in the respiratory tract [2]. Due to a particular vulnerability of Clara cells to lung toxicants CC16 has also been evaluated as a useful biomarker of r