Oxygen-independent intracellular and oxygen-dependent extracellular killing of Escherichia coli S15 by human polymorphonuclear leukocytes.

Weiss, Jerrold; Kao, L; Victor, Michael; Elsbach, Peter

doi:10.1172/jci111947

Cited by 82 publications

(46 citation statements)

References 28 publications

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“…The prolonged preservation of bacterial protein synthesis and incomplete phospholipid degradation seen when E. coli are ingested by PMN are also typical of BPI action (25). These remarkable similarities between the initial injuries inflicted by isolated BPI and by intact PMN, together with the evidence that BPI binds to ingested E. coli (42), are compatible with the hypothesis that BPI accounts for PLA activation during phagocytosis.…”

Section: Discussionsupporting

confidence: 77%

Bacterial phospholipid hydrolysis enhances the destruction of Escherichia coli ingested by rabbit neutrophils. Role of cellular and extracellular phospholipases.

Wright¹,

Weiss²,

Kim³

et al. 1990

J. Clin. Invest.

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IntroductionEscherichia coli ingested by PMN are promptly growth arrested but undergo limited destruction. We have studied bacterial phospholipid hydrolysis as a possible limiting factor in the disassembly of ingested E. coli, comparing the fates, during phagocytosis by rabbit peritoneal exudate PMN, of three isogenic strains, differing in their content of the pldA gene encoding the principal E. coli phospholipase A (PLA), i.e., pldA-, pldA+, pldA+++ (the latter strain bearing the pldA gene in a multicopy plasmid resulting in a 20-fold increase in PLA content). Ingestion and growth inhibition (> 99% within 15 min) were the same for the three strains, but phospholipid degradation differed according to bacterial PLA content: pldA+++ up to 60%, pldA+ up to 30%, and pidA-up to 20%. Since the pidA-strain has no activatable PLA, phospholipid degradation in this strain demonstrates the action of a PMN PLA. Added PLA2-rich ascitic fluid (AF) or purified AF PLA2 increased the rate and extent of degradation of the pldA-strain, provided the enzyme was added before ingestion was complete.125I-AF-PLA2 binds to both E. coli and PMN and thus can enter the vacuole during phagocytosis. Although up to 50-fold more AF-PLA2 than the PLA2 content of the PMN could be loaded into the PMN in this way, degradation of pldA-E. coli did not exceed 30%. Increased phospholipid degradation had no effect on the degradation of bacterial macromolecules. In contrast, bacterial disassembly manifest as structural disorganization, release of bacterial protein derived material, and inhibition of protein synthesis were markedly enhanced when > 50% of prelabelled bacterial phospholipids were degraded. These findings reveal a link between envelope phospholipid degradation and overall bacterial destruction, suggesting therefore that factors limiting PLA action limit the destruction of E. coli ingested by PMN. (J.

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Section: Discussionsupporting

confidence: 77%

Bacterial phospholipid hydrolysis enhances the destruction of Escherichia coli ingested by rabbit neutrophils. Role of cellular and extracellular phospholipases.

Wright¹,

Weiss²,

Kim³

et al. 1990

J. Clin. Invest.

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“…Thus, like PL, degradation of RNA and proteins in E. coli LCD25 is rapid, reaching an early plateau. Degradation of RNA by both cellular and extracellular components of the rabbit exudate was particularly extensive, as has been shown previously in different bacterial species (9,10,19). Therefore, deacylation of LPS by AF and PMN is slow and limited relative to degradation of other bacterial components.…”

Section: Lps and Pl Deacylation During Intracellular Killing By Inflasupporting

confidence: 61%

Deacylation of Lipopolysaccharide in Whole Escherichia coli during Destruction by Cellular and Extracellular Components of a Rabbit Peritoneal Inflammatory Exudate

Katz¹,

Weinrauch²,

Munford³

et al. 1999

Journal of Biological Chemistry

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Deacylation of purified lipopolysaccharides (LPS)markedly reduces its toxicity toward mammals. However, the biological significance of LPS deacylation during infection of the mammalian host is uncertain, particularly because the ability of acyloxyacyl hydrolase, the leukocyte enzyme that deacylates purified LPS, to attack LPS residing in the bacterial cell envelope has not been established. We recently showed that the cellular and extracellular components of a rabbit sterile inflammatory exudate are capable of extensive and selective removal of secondary acyl chains from purified LPS. We now report that LPS as a constituent of the bacterial envelope is also subject to deacylation in the same inflammatory setting. Using Escherichia coli LCD25, a strain that exclusively incorporates radiolabeled acetate into fatty acids, we quantitated LPS deacylation as the loss of radiolabeled secondary (laurate and myristate) and primary fatty acids (3-hydroxymyristate) from the LPS backbone. Isolated mononuclear cells and neutrophils removed 50% and 20 -30%, respectively, of the secondary acyl chains of the LPS of ingested whole bacteria. When bacteria were killed extracellularly during incubation with ascitic fluid, no LPS deacylation occurred. In this setting, the addition of neutrophils had no effect, but addition of mononuclear cells resulted in removal of >40% of the secondary acyl chains by 20 h. Deacylation of LPS was always restricted to the secondary acyl chains. Thus, in an inflammatory exudate, primarily in mononuclear phagocytes, the LPS in whole bacteria undergoes substantial and selective acyloxyacyl hydrolase-like deacylation, both after phagocytosis of intact bacteria and after uptake of LPS shed from extracellularly killed bacteria. This study demonstrates for the first time that the destruction of Gram-negative bacteria by a mammalian host is not restricted to degradation of phospholipids, protein, and RNA, but also includes extensive deacylation of the envelope LPS.The prominent role ascribed to LPS 1 in evoking beneficial as well as harmful mammalian host responses to invading Gramnegative bacteria has prompted intense scrutiny of host recognition, detoxification, and elimination of this bacterial product. Underacylated and underphosphorylated biosynthetic precursors and chemically synthesized analogs of lipid A (the endotoxic part of LPS) possess greatly diminished endotoxic activity and can act as antagonists in human cell bioassays (1, 2). Mammalian enzyme systems capable of removing acyl and phosphate groups from lipid A may therefore play an important role in host defense against Gram-negative bacteria and their LPS. Thus far, only one mammalian enzyme, acyloxyacyl hydrolase, has been shown to deacylate LPS (3, 4).We recently showed that both the cells and extracellular fluid of a sterile inflammatory exudate actively deacylate purified LPS ex vivo in an acyloxyacyl hydrolase-like fashion (5). It has been much more difficult to analyze LPS breakdown products when the LPS is presented in intact bacteria...

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“…Whereas our earlier studies have implicated a role for granule-associated BPI in intracellular killing of Gramnegative bacteria by PMN (30)(31)(32) and have revealed a potential role for secreted BPI in extracellular killing of phagocytosis-resistant encapsulated E. coli (12) and in regulation of Gram-negative bacterial (LPS)-mediated signaling (11,24), we now propose a role for BPI in disposal of Gram-negative bacteria via ingestion by phagocytes. Although the opsonic effects described in this study required BPI doses that produced antibacterial (growth-inhibitory) effects (compare Fig.…”

Section: Bpi-mediated Phagocytosis Doesmentioning

confidence: 62%

An opsonic function of the neutrophil bactericidal/permeability-increasing protein depends on both its N- and C-terminal domains

Iovine

Elsbach

Weiss

1997

Proc. Natl. Acad. Sci. U.S.A.

147

127

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The host response to Gram-negative bacterial infection is inf luenced by two homologous lipopolysaccharide (LPS)-interactive proteins, LPS-binding protein (LBP) and the bacteridical͞permeability-increasing protein (BPI). Both proteins bind LPS via their N-terminal domains but produce profoundly different effects: BPI and a bioactive N-terminal fragment BPI-21 exert a selective and potent antibacterial effect upon Gram-negative bacteria and suppress LPS bioactivity whereas LBP is not toxic toward Gramnegative bacteria and potentiates LPS bioactivity. The latter effect of LBP requires the C-terminal domain for delivery of LPS to CD14, so we postulated that the C-terminal region of BPI may serve a similar delivery function but to distinct targets. LBP, holoBPI, BPI-21, and LBP͞BPI chimeras were compared for their ability to promote uptake by human phagocytes of an encapsulated, phagocytosis-resistant strain of Escherichia coli. We show that only bacteria preincubated with holoBPI are ingested by neutrophils and monocytes. These findings suggest that, when extracellular holoBPI is bound via its N-terminal domain to Gram-negative bacteria, the C-terminal domain promotes bacterial attachment to neutrophils and monocytes, leading to phagocytosis. Therefore, analogous to the role of the C-terminal domain of LBP in delivery of LPS to CD14, the C-terminal domain of BPI may fulfill a similar function in BPI-specific disposal pathways for Gram-negative bacteria.

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Oxygen-independent intracellular and oxygen-dependent extracellular killing of Escherichia coli S15 by human polymorphonuclear leukocytes.

Cited by 82 publications

References 28 publications

Bacterial phospholipid hydrolysis enhances the destruction of Escherichia coli ingested by rabbit neutrophils. Role of cellular and extracellular phospholipases.

Bacterial phospholipid hydrolysis enhances the destruction of Escherichia coli ingested by rabbit neutrophils. Role of cellular and extracellular phospholipases.

Deacylation of Lipopolysaccharide in Whole Escherichia coli during Destruction by Cellular and Extracellular Components of a Rabbit Peritoneal Inflammatory Exudate

An opsonic function of the neutrophil bactericidal/permeability-increasing protein depends on both its N- and C-terminal domains

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