Interference ofStaphylococcus aureus lipase with human granulocyte function

Abstract

The influence of purified Staphylococcus aureus lipase on granulocyte function and morphology was studied. The lipase itself was strongly chemotactic; in addition preincubation of granulocytes with low concentrations of lipase enhanced the directed movement, as assayed in the agarose system. Higher concentrations of lipase, in contrast, gave a progressive reduction of granulocyte chemotaxis; at 12 micrograms lipase per ml, cells were almost immobilized. Phagocytic killing of Staphylococcus aureus by granulocytes preincubated with lipase was reduced in a dose-dependent manner. At 12 micrograms lipase per ml almost no staphylococcal killing occurred. This was mainly accounted for by a reduction of bacterial uptake, but some decrease in intragranulocytic killing was also noted. These functional alterations, which can all be ascribed to an interference with membrane functions, were associated with marked changes of the granulocyte surface structure, which was denuded and lacked normal microvilli. The effects of lipase were partly retained after heat inactivation of lipase activity, indicating that the effects of staphylococcal lipase on granulocyte function are not due to enzymatic activity alone. These effects of lipase may be an important virulence factor and contribute to the preferential location of lipase-producing Staphylococcus aureus strains at deep sites of infection.

Glycerol Monolaurate Inhibits Lipase Production by Clinical Ocular Isolates Without Affecting Bacterial Cell Viability

“…26,38 Additionally, S. epidermidis lipases appear to play a role in limiting colonization by S. aureus, and S. aureus lipases interfere with phagocytosis of S. aureus by granulocytes. 39 Controlling lipase production that results from overgrowth of opportunistic pathogens could reduce overall fitness of these bacteria and assist in rebalancing the ocular microbiome.…”

Plesiomonas shigelloides Revisited

“…This was demonstrated by Č ižnár (175) in a study of 20 isolates from environmental sources, human cases of gastroenteritis, and animal sources. Here, the isolates belonged to 13 different serovars; the majority of strains were both hydrophobic, indicating their ability to interact with a wide variety of surfaces including mammalian cells, and had a relatively high level of flagellar motility to facilitate attachment; all produced triacylglycerol lipase, which is a virulence factor found in Staphylococcus aureus (177), Staphylococcus cohnii (178), and Pseudomonas (Burkholderia) cepacia (179). However, among these strains, there was significant variation in elastase, proteinase, histidine decarboxylase, and hemolysin activities.…”

Alternative Sigma Factors and Their Roles in Bacterial Virulence

“…These characteristics have all been associated with S. aureus virulence (61,67,98,131,150,184). It is likely that optimal levels of virulence factor expression and activity are required for efficient S. aureus infection and that too much or too little activity or expression at the wrong time is detrimental for the infection process.…”