Cholecystokinin octapeptide inhibits the in vitro expression of CD14 in rat pulmonary interstitial macrophages induced by lipopolysaccharide

Objective. To study the effect of cholecystokinin octapeptide (CCK-8) on lipopolysaccharide (LPS)-stimulated pulmonary interstitial macrophages (PIM) in vitro. Methods. PIM were isolated and cultured in the presence or absence of LPS, CCK-8, proglumide (the antagonist of CCK receptors) and vehicle. The expression of membrane CD14 (mCD14) protein was assayed by flow cytometry and soluble CD14 (sCD14) in the supernatant was analyzed semi-quantitatively by Western blot. TNF-α in the supernatant was detected with ELISA. Results. CCK-8, at concentrations of 10^-7 mol/L and 10^-6 mol/L, significantly inhibited the expression of mCD14. Release of sCD14 and TNF-α in the supernatant was up-regulated by LPS (1 μg/ml) but reduced by CCK-8. The effect of CCK-8 was inhibited by proglumide. Conclusion. CCK-8 negatively modulated several functions of LPS-stimulated PIM through CCK receptors. This may be one of the mechanisms for CCK-8 to alleviate inflammation in lung tissue during endotoxemia.