Klebsiella pneumoniae O antigen loss alters the outer membrane protein composition and the selective packaging of proteins into secreted outer membrane vesicles

Cahill, Bethaney K.; Seeley, Kent W.; Gutel, Dedra; Ellis, Terri N.

doi:10.1016/j.micres.2015.06.012

Cited by 46 publications

(48 citation statements)

References 66 publications

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“…The protein composition of OMVs is known to differ from that of the source outer membrane. The contents of OMVs are known to be selectively packaged, enriching in molecules that may impact inflammation (20,34). Therefore, we tested the proinflammatory cytokine responses of macrophages exposed to enriched total outer membrane from strains expressing neither porin, either porin, or both porins to determine if the responses were similar.…”

Section: Resultsmentioning

confidence: 99%

“…Studies in a number of Gram-negative species have demonstrated that proteins are selectively packaged and concentrated into outer membrane vesicles (16,20,37). This enrichment effect is central to OMVs' role in bacterial pathogenesis.…”

Section: Figmentioning

confidence: 99%

“…Vesicles have also been shown to inhibit macrophage phagosome-lysosome fusion, modify host cell secretion, and stimulate intense inflammatory responses. The production of vesicles has been shown across a broad range of Gram-negative pathogens to be an essential physiological function of bacteria, including survival within infected human tissues (17,18).It has been demonstrated by our lab and others that K. pneumoniae strains produce vesicles that are laden with gene products associated with virulence and are capable of triggering a potent inflammatory response (19,20). Lee et al were the first to broadly characterize Klebsiella OMV protein composition.…”

mentioning

confidence: 98%

“…It has been demonstrated by our lab and others that K. pneumoniae strains produce vesicles that are laden with gene products associated with virulence and are capable of triggering a potent inflammatory response (19,20). Lee et al were the first to broadly characterize Klebsiella OMV protein composition.…”

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confidence: 99%

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Porin Loss Impacts the Host Inflammatory Response to Outer Membrane Vesicles of Klebsiella pneumoniae

Turner

Cahill

Dilello

et al. 2016

Antimicrob Agents Chemother

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Antibiotic-resistant strains of Klebsiella pneumoniae often exhibit porin loss. In this study, we investigated how porin loss impacted the composition of secreted outer membrane vesicles as well as their ability to trigger proinflammatory cytokine secretion by macrophages. We hypothesize that porin loss associated with antibiotic resistance will directly impact both the composition of outer membrane vesicles and their interactions with phagocytic cells. Using clonally related clinical isolates of extended-spectrum beta-lactamase (ESBL)-positive Klebsiella pneumoniae with different patterns of porin expression, we demonstrated that altered expression of OmpK35 and OmpK36 results in broad alterations to the protein profile of secreted vesicles. Additionally, the level of OmpA incorporation was elevated in strains lacking a single porin. Porin loss significantly impacted macrophage inflammatory responses to purified vesicles. Outer membrane vesicles lacking both OmpK35 and OmpK36 elicited significantly lower levels of proinflammatory cytokine secretion than vesicles from strains expressing one or both porins. These data demonstrate that antibiotic resistance-associated porin loss has a broad and significant effect on both the composition of outer membrane vesicles and their interactions with phagocytic cells, which may impact bacterial survival and inflammatory reactions in the host.K lebsiella pneumoniae is a nosocomial pathogen responsible for as many as 20% of all cases of culture-positive blood cultures and bacterial sepsis (1). Alarmingly, up to 50% of these infections are resistant to most current antibiotics (2, 3). The majority of resistant Klebsiella isolates exhibit both expression of an extendedspectrum beta-lactamase (ESBL) and halted expression of at least one outer membrane porin (4, 5). Porin loss has been clearly shown to enhance levels of antibiotic resistance, and ESBL-positive K. pneumoniae isolates commonly exhibit loss of OmpK35 and OmpK36, which both function in nonspecific transport across the outer membrane (6-8).While changes to the porin profile of bacteria are well documented to be associated with enhanced antibiotic resistance (9, 10), the role that these porins play in pathogenesis has not been fully investigated. In vitro experiments using mutants of K. pneumoniae lacking OmpK36 have demonstrated that loss of OmpK36 results in increased phagocytic killing of the bacteria, and in vivo experiments have demonstrated decreased virulence and bacterial survival of strains lacking OmpK36 in a mouse model (11)(12)(13)(14). Data from these studies consistently indicate that loss of OmpK36 results in an increase in antibiotic resistance paired with a decrease in fitness and ability to survive host immune responses. It is unclear how resistant strains of Klebsiella are able to persist in host tissues when porin loss renders the bacteria more susceptible to phagocytic clearance.The capsule is the best understood of the virulence factors of Klebsiella, cloaking the bacterial outer surface from immu...

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Section: Resultsmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

mentioning

confidence: 98%

mentioning

confidence: 99%

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Porin Loss Impacts the Host Inflammatory Response to Outer Membrane Vesicles of Klebsiella pneumoniae

Turner

Cahill

Dilello

et al. 2016

Antimicrob Agents Chemother

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“…In several bacterial genera, such as Klebsiella and Porphyromonas, mutations that modify the O antigen have been reported to affect OMVs by altering the protein content and reducing OMV production, respectively (41,42). Similarly, while Pseudomonas O-antigen mutants have no effect on the rate of OMV release, they do affect both their contents and size (43).…”

Section: Discussionmentioning

confidence: 99%

Rotation of Vibrio fischeri Flagella Produces Outer Membrane Vesicles That Induce Host Development

et al. 2016

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Using the squid-vibrio association, we aimed to characterize the mechanism through which Vibrio fischeri cells signal morphogenesis of the symbiotic light-emitting organ. The symbiont releases two cell envelope molecules, peptidoglycan (PG) and lipopolysaccharide (LPS) that, within 12 h of light organ colonization, act in synergy to trigger normal tissue development. Recent work has shown that outer membrane vesicles (OMVs) produced by V. fischeri are sufficient to induce PG-dependent morphogenesis; however, the mechanism(s) of OMV release by these bacteria has not been described. Like several genera of both beneficial and pathogenic bacteria, V. fischeri cells elaborate polar flagella that are enclosed by an extension of the outer membrane, whose function remains unclear. Here, we present evidence that along with the well-recognized phenomenon of blebbing from the cell's surface, rotation of this sheathed flagellum also results in the release of OMVs. In addition, we demonstrate that most of the development-inducing LPS is associated with these OMVs and that the presence of the outer membrane protein OmpU but not the LPS O antigen on these OMVs is important in triggering normal host development. These results also present insights into a possible new mechanism of LPS release by pathogens with sheathed flagella. IMPORTANCEDetermining the function(s) of sheathed flagella in bacteria has been challenging, because no known mutation results only in the loss of this outer membrane-derived casing. Nevertheless, the presence of a sheathed flagellum in such host-associated genera as Vibrio, Helicobacter, and Brucella has led to several proposed functions, including physical protection of the flagella and masking of their immunogenic flagellins. Using the squid-vibrio light organ symbiosis, we demonstrate another role, that of V. fischeri cells require rotating flagella to induce apoptotic cell death within surface epithelium, which is a normal step in the organ's development. Further, we present evidence that this rotation releases apoptosis-triggering lipopolysaccharide in the form of outer membrane vesicles. Such release may also occur by pathogens but with different outcomes for the host.

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Lipid A in outer membrane vesicles shields bacteria from polymyxins

Burt,

Angelidou,

Mais

et al. 2024

J of Extracellular Vesicle

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The continuous emergence of multidrug‐resistant bacterial pathogens poses a major global healthcare challenge, with Klebsiella pneumoniae being a prominent threat. We conducted a comprehensive study on K. pneumoniae’s antibiotic resistance mechanisms, focusing on outer membrane vesicles (OMVs) and polymyxin, a last‐resort antibiotic. Our research demonstrates that OMVs protect bacteria from polymyxins. OMVs derived from Polymyxin B (PB)‐stressed K. pneumoniae exhibited heightened protective efficacy due to increased vesiculation, compared to OMVs from unstressed Klebsiella. OMVs also shield bacteria from different bacterial families. This was validated ex vivo and in vivo using precision cut lung slices (PCLS) and Galleria mellonella. In all models, OMVs protected K. pneumoniae from PB and reduced the associated stress response on protein level. We observed significant changes in the lipid composition of OMVs upon PB treatment, affecting their binding capacity to PB. The altered binding capacity of single OMVs from PB stressed K. pneumoniae could be linked to a reduction in the lipid A amount of their released vesicles. Although the amount of lipid A per vesicle is reduced, the overall increase in the number of vesicles results in an increased protection because the sum of lipid A and therefore PB binding sites have increased. This unravels the mechanism of the altered PB protective efficacy of OMVs from PB stressed K. pneumoniae compared to control OMVs. The lipid A‐dependent protective effect against PB was confirmed in vitro using artificial vesicles. Moreover, artificial vesicles successfully protected Klebsiella from PB ex vivo and in vivo. The findings indicate that OMVs act as protective shields for bacteria by binding to polymyxins, effectively serving as decoys and preventing antibiotic interaction with the cell surface. Our findings provide valuable insights into the mechanisms underlying antibiotic cross‐protection and offer potential avenues for the development of novel therapeutic interventions to address the escalating threat of multidrug‐resistant bacterial infections.

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Klebsiella pneumoniae O antigen loss alters the outer membrane protein composition and the selective packaging of proteins into secreted outer membrane vesicles

Cited by 46 publications

References 66 publications

Porin Loss Impacts the Host Inflammatory Response to Outer Membrane Vesicles of Klebsiella pneumoniae

Porin Loss Impacts the Host Inflammatory Response to Outer Membrane Vesicles of Klebsiella pneumoniae

Rotation of Vibrio fischeri Flagella Produces Outer Membrane Vesicles That Induce Host Development

Lipid A in outer membrane vesicles shields bacteria from polymyxins

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