RELEASE OF ENDOTOXIN IN THE FORM OF CELL WALL BLEBS DURING IN VITRO GROWTH OF <i>NEISSERIA MENINGITIDIS </i>

DeVoe, I W; Gilchrist, J. E.

doi:10.1084/jem.138.5.1156

Cited by 281 publications

(165 citation statements)

References 17 publications

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“…LPS is released by growing N. meningitidis (36); thus, the structure recognized by TLR2 and TLR1 in the Neisseria supernatants might be LPS. Therefore, the stimulatory effect of soluble factors released from mid-log phase wild-type N. meningitidis strain H44/76 and from its LPS-free isogenic mutant pLAK33 (31), prepared as described in Materials and Methods, were compared.…”

Section: Dependency Of Tlr2 Stimulation On N Meningitidis Lpxa Genementioning

confidence: 99%

Evidence for an Accessory Protein Function for Toll-Like Receptor 1 in Anti-Bacterial Responses

Wyllie

Kiss-Tóth

Visintin

et al. 2000

The Journal of Immunology

245

151

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Members of the Toll-like receptor (TLR) family are components of the mammalian anti-microbial response, signaling with a domain closely related to that of IL-1 receptors. In this report the expression and function of TLR1, a TLR of unknown function, are examined. TLR1 is expressed by monocytes, as demonstrated using a novel mAb. Monocytes also express TLR2. TLR1 transfection of HeLa cells, which express neither TLR1 nor TLR2, was not sufficient to confer responsiveness to several microbial extracts. However, cotransfection of TLR1 and TLR2 resulted in enhanced signaling by HeLa cells to soluble factors released from Neisseria meningitidis relative to the response with either TLR alone. This phenomenon was also seen with high concentrations of some preparations of LPS. The N. meningitidis factors recognized by TLR1/TLR2 were not released by N. meningitidis mutant in the LpxA gene. Although LpxA is required for LPS biosynthesis, because cooperation between TLR1 and TLR2 was not seen with all LPS preparations, the microbial component(s) TLR1/2 recognizes is likely to be a complex of LPS and other molecules or a compound metabolically and chemically related to LPS. The functional IL-1R consists of a heterodimer; this report suggests a similar mechanism for TLR1 and TLR2, for certain agonists. These data further suggest that mammalian responsiveness to some bacterial products may be mediated by combinations of TLRs, suggesting a mechanism for diversifying the repertoire of Toll-mediated responses.

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Section: Dependency Of Tlr2 Stimulation On N Meningitidis Lpxa Genementioning

confidence: 99%

Evidence for an Accessory Protein Function for Toll-Like Receptor 1 in Anti-Bacterial Responses

Wyllie

Kiss-Tóth

Visintin

et al. 2000

The Journal of Immunology

245

151

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“…These observations were explained by the reports that LT was associated with ETEC vesicles (21,22,40,41). Most Gram-negative bacteria shed portions of their outer membrane into the cell culture supernatant (41)(42)(43)(44)(45)(46)(47)(48)(49). These spherical outer membrane fragments termed "vesicles" are composed of LPS, lipids, proteins, and toxins.…”

mentioning

confidence: 98%

Bacterial Surface Association of Heat-labile Enterotoxin through Lipopolysaccharide after Secretion via the General Secretory Pathway

Horstman

Kuehn

2002

Journal of Biological Chemistry

135

164

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Heat-labile enterotoxin (LT) is an important virulence factor expressed by enterotoxigenic Escherichia coli.The route of LT secretion through the outer membrane and the cellular and extracellular localization of secreted LT were examined. Using a fluorescently labeled receptor, LT was found to be specifically secreted onto the surface of wild type enterotoxigenic Escherichia coli. The main terminal branch of the general secretory pathway (GSP) was necessary and sufficient to localize LT to the bacterial surface in a K-12 strain. LT is a heteromeric toxin, and we determined that its cell surface localization was mediated by the its B subunit independent of an intact G M1 ganglioside binding site and that LT binds lipopolysaccharide and G M1 concurrently. The majority of LT secreted into the culture supernatant by the GSP in E. coli associated with vesicles. Only a mutation in hns, not overexpression of the GSP or LT, caused an increase in vesicle yield, supporting a specific vesicle formation machinery regulated by the nucleoidassociated protein HNS. We propose a model in which LT is secreted by the GSP across the outer membrane, secreted LT binds lipopolysaccharide via a G M1 -independent binding region on its B subunit, and LT on the surface of released outer membrane vesicles interacts with host cell receptors, leading to intoxication. These data explain a novel mechanism of vesicle-mediated receptor-dependent delivery of a bacterial toxin into a host cell. Enterotoxigenic Escherichia coli (ETEC)1 is an important pathogen responsible for traveler's diarrhea and Ͼ700,000 childhood deaths annually because of diarrhea in third world countries (1-4). ETEC produces two toxins implicated in the etiology of diarrhea, heat stabile toxin and heat-labile enterotoxin (LT) (1, 5). LT, which is encoded on a relatively uncharacterized 60-kb virulence plasmid (1), is one of a group of AB 5 toxins (6, 7) that also includes Shiga toxin, pertussis toxin, and cholera toxin (CT). These heteromeric toxins consist of a catalytic A subunit (LTA) and a pentamer of receptor-binding B subunits (LTB) (8, 9). In addition to structural homology, LT shares 80% sequence homology with the Vibrio cholerae toxin CT (10, 11). The ring-shaped B pentamer of both LT and CT mediates binding to the host epithelial receptor G M1 (12)(13)(14). LT is more promiscuous than CT in that it can also bind other receptors containing a terminal galactose (13). After binding, the receptor/toxin complex is internalized, and LTA is trafficked to the cytosol (13,15,16). Upon entry into the cytosol, the catalytic subunit constitutively activates adenylate cyclase, resulting in water and electrolyte efflux from the host cells (17).One major difference between the CT and LT lies in the fact that although CT is secreted from the cell, LT reportedly remains periplasmic (5, 18 -20). Some studies have also found LT to be associated with membranes extracellularly (3,21,22). Despite the equivalent activity that CT and LT exhibit in bioassays, disease caused by ETEC is much...

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“…In many bacteria, endotoxin is released in the form of blebs (9). Moreover, the DNAs of Neisseria gonorrhoeae were associated with blebs (11).…”

Section: Discussionmentioning

confidence: 99%

Neutrophil Response to Nontypable Haemophilus influenzae in Respiratory Infections

Ahmed

Ichinose

Dai

et al. 1993

Microbiology and Immunology

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Sputa from patients with respiratory infections by nontypable Haemophilus influenzae (H. influenzae) were investigated by electron microscopy. The cell wall of H. influenzae appeared wavy and nonwavy. In the cell wall the peptidoglycan layer was ill-defined. These patients had adequate IgG response in the serum against H. influenzae. However neither capsule nor fimbriae were found. Different stages of phagocytosis and destruction of the bacteria by polymorphonuclear neutrophils (PMN) were observed. PMNs were also found to phagocytose the debris. Evidences were found that the debris is formed mainly by the destruction of polymorphonuclear neutrophil. Extracellular lysosomes were also observed, which may have a role in destruction of both bacteria and host tissue. It was concluded that nontypable H. influenzae are nonfimbriated and noncapsulated during infection. Debris are the end product of PMN destruction, and phagocytosis of debris by PMNs has a role in the pathogenesis of chronic respiratory diseases.

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RELEASE OF ENDOTOXIN IN THE FORM OF CELL WALL BLEBS DURING IN VITRO GROWTH OF NEISSERIA MENINGITIDIS

Cited by 281 publications

References 17 publications

Evidence for an Accessory Protein Function for Toll-Like Receptor 1 in Anti-Bacterial Responses

Evidence for an Accessory Protein Function for Toll-Like Receptor 1 in Anti-Bacterial Responses

Bacterial Surface Association of Heat-labile Enterotoxin through Lipopolysaccharide after Secretion via the General Secretory Pathway

Neutrophil Response to Nontypable Haemophilus influenzae in Respiratory Infections

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