Inability of encapsulated Klebsiella pneumoniae to assemble functional type 1 fimbriae on their surface

Matatov, Robert

doi:10.1016/s0378-1097(99)00402-4

Cited by 16 publications

(28 citation statements)

References 25 publications

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“…The unencapsulated derivatives of strain K21a and the K50 strain were obtained as described elsewhere (38,55). A spontaneous unencapsulated mutant, 50-30F, from the parent K50 strain was obtained by selecting nonmucoid colonies as described previously (38). For these experiments, bacteria were grown on Trypticase soy agar (Difco) for 24 h at 37°C and harvested by scraping the confluent growth.…”

Section: Methodsmentioning

confidence: 99%

“…Although the phenomenon of phase variation in capsular expression has been long appreciated for E. coli and many other bacterial organisms (45), it has been only recently documented for K. pneumoniae (38). Phase variation represents an apparently random, bidirectional, on-off control of bacterial genes that can take place at relatively high frequency, i.e., approximately 10,000 times more frequently than classical mutational events (44).…”

mentioning

confidence: 99%

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Surfactant Protein D Enhances Phagocytosis and Killing of Unencapsulated Phase Variants ofKlebsiella pneumoniae

et al. 2001

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Surfactant Protein D Enhances Phagocytosis and Killing of Unencapsulated Phase Variants ofKlebsiella pneumoniae

et al. 2001

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“…The virulence of CPS may derive from enhanced colonization in the airway spaces and reduced adhesion to host cells by transcriptional regulation (23). Previously, isogenic capsule-negative strains (DCPS) showed higher adhesion to airway cells (24).…”

Section: Raft-dependent Bacterial Internalization Is Enhanced By Delementioning

confidence: 99%

Lipid-Based Signaling Modulates DNA Repair Response and Survival against Klebsiella pneumoniae Infection in Host Cells and in Mice

Huang

Weaver

et al. 2013

Am J Respir Cell Mol Biol

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Klebsiella pneumoniae causes serious infections in the urinary tract, respiratory tract, and blood. Lipid rafts, also known as membrane microdomains, have been linked to the pathogenesis of bacterial infection. However, whether lipid rafts affect K. pneumoniae internalization into host cells remains unknown. Here, we show for the first time that K. pneumoniae was internalized into lung cells by activating lipid rafts. Disrupting lipid rafts by methyl-b-cyclodextrin inhibited pathogen internalization, impairing host defense. A deficient mutant of capsule polysaccharide (CPS) showed a higher internalization rate than a wild-type strain, indicating that CPS may inhibit bacterial entry to host cells. Furthermore, lipid rafts may affect the function of extracellular regulated kinase (ERK)-1/2, and knocking down ERK1/ 2 via short, interfering RNA increased apoptosis in both alveolar macrophages and epithelial cells after infection. To gain insights into bacterial pathogenesis, we evaluated the impact of lipid rafts on DNA integrity, and showed that raft aggregates also affect DNA damage and DNA repair responses (i.e., 8-oxoguanine DNA glycosylase [Ogg1]) through the regulation of reactive oxygen species. Importantly, cells overexpressing Ogg1 demonstrated reduced cytotoxicity during bacterial infection. Taken together, these results suggest that lipid rafts may modulate bacterial internalization, thereby affecting DNA damage and repair, which is critical to host defense against K. pneumoniae.Keywords: Klebsiella pneumoniae infection; internalization; alveolar epithelial cells; lipid rafts; capsule polysaccharide Klebsiella pneumoniae causes serious infections in multiorgan systems, and is the third most commonly isolated bacterium from the blood of patients with sepsis (1). Because K. pneumoniae rapidly develops multidrug-resistant strains, this "superbug" can also cause outbreaks in intensive care units, imposing significant financial burdens and dangerous health threats (2, 3). Despite intensive research during the past few decades, the pathogenesis of K. pneumoniae, including its internalization of alveolar cells, is incompletely understood. K. pneumoniae expresses two critical antigens on its cell surface, LPS (an O antigen) and capsule polysaccharide (CPS; a K antigen) (4). These two antigens contribute to pathogenicity through interactions with host cells in different manners (5). LPS is a major component of Gramnegative bacterial cell walls with high immunogenicity, but its role in pathogenesis remains elusive. Early studies suggest that LPS-deficient strains failed to show significantly different pathogenesis from the wild-type (WT) strain (5). By contrast, CPS demonstrates the most distinguished characteristic of virulence factors for K. pneumoniae, and is implicated in the internalization of pathogens into epithelial cells (6). The capsule may protect the bacterium from phagocytosis by macrophages, through an escape from bactericidal serum factors (6). Other studies also demonstrated that isogenic CPS mutant...

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“…Colonization of the upper respiratory tract by gram-negative bacteria precedes entry of the organisms into the lung. Because capsules can interfere with the expression or function of adhesins required for the colonization of epithelial cells by the organisms, it is likely that most of the bacteria colonizing the upper respiratory tract or other epithelial surfaces are in the noncapsulated phase (19,57,81,83). Lung collectin SP-D, which reacts with a conserved region of the LPS core, may provide early protection against all strains of noncapsulated phenotypes either by opsonizing the bacteria to enhance their phagocytosis or by agglutinating the bacteria, which may inhibit their adhesion to the upper respiratory epithelium (71,79).…”

Section: Integrative Model For Klebsiellamentioning

confidence: 99%

“…Polymannose-containing O serotypes can bind to SP-D, while those that lack such structures cannot. In vitro studies have shown that Klebsiella can undergo phase variation between capsulated and noncapsulated phenotypes (57). As a result, capsulated bacteria that emerge during the infection are prone to escape SP-D recognition.…”

Section: Integrative Model For Klebsiellamentioning

confidence: 99%

Recognition of Bacterial Surface Polysaccharides by Lectins of the Innate Immune System and Its Contribution to Defense against Infection: the Case of Pulmonary Pathogens

et al. 2008

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5Many pathogenic bacterial species are classified into serological types, distinguished by their carbohydrate-rich surface antigens. These antigens are referred to as serotypic epitopes or glycoepitopes. Glycoepitopes are most commonly associated with capsular polysaccharides (CPS) or the O-antigen domains of bacterial lipopolysaccharides (LPS).The association of specific bacterial serotypes of a given genus with defined clinical infections is a common phenomenon that applies to a variety of gram-negative bacteria and gram-positive bacteria. As discussed below, of the 77 distinct capsular serotypes in the species Klebsiella pneumoniae, only 25 account for most pulmonary and blood infections (12). Likewise, of the more than 90 capsular serotypes of Streptococcus pneumoniae, only 23 account for most infections, and these are included in the current capsular vaccine (25).The surfaces of the pulmonary pathogens Klebsiella pneumoniae and Streptococcus pneumoniae are coated with a variety of glycoconjugates that confer specific properties. For example, the polysaccharide capsules enable these pathogens to resist phagocytosis. In a few cases, it has been argued that serotype-associated differences in capsular size contribute to virulence and the high frequency of isolation. However, there is no satisfactory explanation why only a limited number of capsular serotypes are responsible for most infections (12,25).Because lectins are important components of the lung's innate immune system, it is reasonable to hypothesize that differences in the frequencies of isolation of specific serotypes in the setting of pneumonia are in part determined by the recognition, or the lack of recognition, of their corresponding glycoepitopes by lectins. We propose that the lack of recognition of glycoconjugates by one or more lectins of the lung contributes to the high frequency of isolation from pneumonia patients of the pulmonary pathogens bearing reactive glycoepitopes. Conversely, lectins that recognize serotype-specific glycoepitopes contribute to the eradication of these serotypes, resulting in a lower frequency of their isolation from clinical samples.In this review, we first correlate the sugar specificities of several types of lung lectins with the glycoconjugates on the surfaces of selected pulmonary pathogens. We then briefly describe in vitro data that suggest mechanisms through which the lung C-type lectins contribute to the elimination of specific glycoepitope-bearing serotypes. Finally, we review available evidence supporting our hypothesis that the high frequency of isolation of serotypes bearing a specific glycoepitope results from the ability of these serotypes to evade recognition by lectins of the innate immune system. PULMONARY LECTINS OF THE INNATE IMMUNE SYSTEMDuring the last 3 decades, there has been intensive research on animal lectins (59, 90). Although lung lectins play a variety of homeostatic roles (38, 89), considerable research has focused on the contributions of several lectins to the innate, natural defense s...

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Inability of encapsulated Klebsiella pneumoniae to assemble functional type 1 fimbriae on their surface

Cited by 16 publications

References 25 publications

Surfactant Protein D Enhances Phagocytosis and Killing of Unencapsulated Phase Variants ofKlebsiella pneumoniae

Surfactant Protein D Enhances Phagocytosis and Killing of Unencapsulated Phase Variants ofKlebsiella pneumoniae

Lipid-Based Signaling Modulates DNA Repair Response and Survival against Klebsiella pneumoniae Infection in Host Cells and in Mice

Recognition of Bacterial Surface Polysaccharides by Lectins of the Innate Immune System and Its Contribution to Defense against Infection: the Case of Pulmonary Pathogens

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