The Bacteroides by-product XXXX inhibits neutrophil respiratory burst by reducing intracellular pH.

@entity4588 @entity26 @entity273 @entity281 @entity224 @entity4514 @entity1718
Short-chain @entity1718 , particularly @entity4588 , are major metabolic by-products of Bacteroides species. To determine their role as potential virulence factors in infections containing Bacteroides species, short-chain @entity1718 were examined for their effect on the neutrophil respiratory burst. @entity4588 (30 to 50 mM) irreversibly impaired @entity224 and @entity273 production in response to opsonized zymosan and @entity4514 when neutrophils were treated at pH 5.5 but not pH 6.0 or greater. Several other short-chain @entity1718 tested produced similar inhibition. Reversible inhibition of @entity26 consumption was found when neutrophils were incubated in @entity4588 -containing medium (pH 6.0) as well as control medium (pH 6.0 and 5.5). Neutrophil cytoplasmic pH was measured by fluorimetric techniques to determine whether the inhibition was mediated via a reduction in intracellular pH. The intracellular pH of cells in control medium (pH 6.5 or less) was significantly reduced compared with pH 7.4. The addition of succinate (30 mM) to these media caused a further significant reduction in cytoplasmic pH at each pH level. The reduction in intracellular pH was sufficient to account for both the irreversible and reversible impairment of the neutrophil respiratory burst. Thus, short-chain @entity1718 appear to exert their inhibition, at least in part, by reducing intracellular pH. These data also demonstrate the potential for interactions between Bacteroides species and their microenvironment to increase the virulence of an @entity281 .
