REGULATION OF STAPHYLOCOCCUS-AUREUS CAPSULAR POLYSACCHARIDE TYPE-5 - CO2 INHIBITION IN-VITRO AND IN-VIVO

Staphylococcus aureus capsular polysaccharide-type 5 (CP5) expression was investigated in lung tissue and nasal polyps of two cystic fibrosi s (CF) patients, in rats, and in vitro using ELISA and IFA. In CF tiss ues, S. aureus expressed protein A and teichoic acid but only 1%-5% of cells expressed CP5. When rats were challenged with CP5-positive S. a ureus in the granuloma pouch model, only 1%-5% of CPS-positive cells w ere detectable in pouch exudates. CF and pouch isolates, however, reex pressed CP5 (70%-90% of cells) when grown in vitro with air. Addition of greater than or equal to 1% CO2 to air or to O-2/N-2 gas mixtures r educed CP5 expression significantly (P<.001) in a dose-dependent manne r (6%-1% CP5-positive cells), The results show that S. aureus does not produce CP5 in CF airways and in rat granuloma pouches and that CO2 i s an environmental signal that regulates CP5 expression.