Clara cell secretory protein (CC16): characteristics and perspectives as lung peripheral biomarker

Clara cell protein (CC16) is a 15.8-kDa homodimeric protein secreted in lar ge amounts in airways by the non-ciliated bronchiolar Clara cells. This pro tein increasingly appears to protect the respiratory tract against oxidativ e stress and inflammation. In vitro, CC16 has been shown to modulate the pr oduction and/or the activity of various mediators of the inflammatory respo nse including PLA(2), interferon-gamma and tumour necrosis factor-alpha. CC 16 has also been found to inhibit fibroblast migration or to bind various e ndogenous or exogenous substances such as polychlorobiphenyls (PCBs). This protective role is confirmed by studies on transgenic mice, showing that CC 16 deficiency is associated with an increased susceptibility of the lung to viral infections and oxidative stress. In humans, a polymorphism of the CC 16 gene, localized to a region linked to airway diseases, has recently been discovered in association with an increased risk of developing childhood a sthma. Finally, CC16 also presents a major interest as a peripheral marker for assessing the integrity of the lung epithelium. The determination of CC 16 in serum is a new non-invasive test to detect Clara cell damage or an in creased epithelial permeability in various acute and chronic lung disorders .