The Experts below are selected from a list of 7431 Experts worldwide ranked by ideXlab platform
Pyong Woo Park - One of the best experts on this subject based on the ideXlab platform.
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syndecan 1 promotes streptococcus pneumoniae Corneal Infection by facilitating the assembly of adhesive fibronectin fibrils
Mbio, 2020Co-Authors: Akiko Jinno, Pyong Woo Park, Atsuko Hayashida, Howard F JenkinsonAbstract:ABSTRACT Subversion of heparan sulfate proteoglycans (HSPGs) is thought to be a common virulence mechanism shared by many microbial pathogens. The prevailing assumption is that pathogens co-opt HSPGs as cell surface attachment receptors or as inhibitors of innate host defense. However, there are few data that clearly support this idea in vivo. We found that deletion of syndecan-1 (Sdc1), a major cell surface HSPG of epithelial cells, causes a gain of function in a mouse model of scarified Corneal Infection, where Sdc1−/− corneas were significantly less susceptible to Streptococcus pneumoniae Infection. Administration of excess Sdc1 ectodomains significantly inhibited S. pneumoniae Corneal Infection, suggesting that Sdc1 promotes Infection as a cell surface attachment receptor. However, S. pneumoniae did not interact with Sdc1 and Sdc1 was shed upon S. pneumoniae Infection, indicating that Sdc1 does not directly support S. pneumoniae adhesion. Instead, Sdc1 promoted S. pneumoniae adhesion by driving the assembly of fibronectin (FN) fibrils in the Corneal basement membrane to which S. pneumoniae attaches when infecting injured corneas. S. pneumoniae specifically bound to Corneal FN via PavA, and PavA deletion significantly attenuated S. pneumoniae virulence in the cornea. Excess Sdc1 ectodomains inhibited S. pneumoniae Corneal Infection by binding to the Hep II domain and interfering with S. pneumoniae PavA binding to FN. These findings reveal a previously unknown virulence mechanism of S. pneumoniae where key extracellular matrix (ECM) interactions and structures that are essential for host cell homeostasis are exploited for bacterial pathogenesis. IMPORTANCE Bacterial pathogens have evolved several ingenious mechanisms to subvert host cell biology for their pathogenesis. Bacterial attachment to the host ECM establishes a niche to grow and is considered one of the critical steps of Infection. This pathogenic mechanism entails coordinated assembly of the ECM by the host to form the ECM structure and organization that are specifically recognized by bacteria for their adhesion. We serendipitously discovered that epithelial Sdc1 facilitates the assembly of FN fibrils in the Corneal basement membrane and that this normal biological function of Sdc1 has detrimental consequences for the host in S. pneumoniae Corneal Infection. Our studies suggest that bacterial subversion of the host ECM is more complex than previously appreciated.
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2 o sulfated domains in syndecan 1 heparan sulfate inhibit neutrophil cathelicidin and promote staphylococcus aureus Corneal Infection
Journal of Biological Chemistry, 2015Co-Authors: Atsuko Hayashida, Shiro Amano, Richard L Gallo, Robert J Linhardt, Pyong Woo ParkAbstract:Abstract Ablation of syndecan-1 in mice is a gain of function mutation that enables mice to significantly resist Infection by several bacterial pathogens. Syndecan-1 shedding is induced by bacterial virulence factors, and inhibition of shedding attenuates bacterial virulence, whereas administration of purified syndecan-1 ectodomain enhances virulence, suggesting that bacteria subvert syndecan-1 ectodomains released by shedding for their pathogenesis. However, the pro-pathogenic functions of syndecan-1 ectodomain have yet to be clearly defined. Here, we examined how syndecan-1 ectodomain enhances Staphylococcus aureus virulence in injured mouse corneas. We found that syndecan-1 ectodomain promotes S. aureus Corneal Infection in an HS-dependent manner. Surprisingly, we found that this pro-pathogenic activity is dependent on 2-O-sulfated domains in HS, indicating that the effects of syndecan-1 ectodomain are structure-based. Our results also showed that purified syndecan-1 ectodomain and heparan compounds containing 2-O-sulfate motifs inhibit S. aureus killing by antimicrobial factors secreted by degranulated neutrophils, but does not affect intracellular phagocytic killing by neutrophils. Immunodepletion of antimicrobial factors with staphylocidal activities demonstrated that CRAMP, a cationic antimicrobial peptide, is primarily responsible for S. aureus killing among other factors secreted by degranulated neutrophils. Furthermore, we found that purified syndecan-1 ectodomain and heparan compounds containing 2-O-sulfate units potently and specifically inhibit S. aureus killing by synthetic CRAMP. These results provide compelling evidence that a specific subclass of sulfate groups, and not the overall charge of HS, permits syndecan-1 ectodomains to promote S. aureus Corneal Infection by inhibiting a key arm of neutrophil host defense.
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role of glycosaminoglycans in infectious disease
Methods of Molecular Biology, 2015Co-Authors: Akiko Jinno, Pyong Woo ParkAbstract:Glycosaminoglycans (GAGs) have been shown to bind to a wide variety of microbial pathogens, including viruses, bacteria, parasites, and fungi in vitro. GAGs are thought to promote pathogenesis by facilitating pathogen attachment, invasion, or evasion of host defense mechanisms. However, the role of GAGs in infectious disease has not been extensively studied in vivo and therefore their pathophysiological significance and functions are largely unknown. Here we describe methods to directly investigate the role of GAGs in Infections in vivo using mouse models of bacterial lung and Corneal Infection. The overall experimental strategy is to establish the importance and specificity of GAGs, define the essential structural features of GAGs, and identify a biological activity of GAGs that promotes pathogenesis.
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syndecan 1 promotes staphylococcus aureus Corneal Infection by counteracting neutrophil mediated host defense
Journal of Biological Chemistry, 2011Co-Authors: Atsuko Hayashida, Shiro Amano, Pyong Woo ParkAbstract:Many microbial pathogens subvert cell surface heparan sulfate proteoglycans (HSPGs) to infect host cells in vitro. The significance of HSPG-pathogen interactions in vivo, however, remains to be determined. In this study, we examined the role of syndecan-1, a major cell surface HSPG of epithelial cells, in Staphylococcus aureus Corneal Infection. We found that syndecan-1 null (Sdc1−/−) mice significantly resist S. aureus Corneal Infection compared with wild type (WT) mice that express abundant syndecan-1 in their Corneal epithelium. However, syndecan-1 did not bind to S. aureus, and syndecan-1 was not required for the colonization of cultured Corneal epithelial cells by S. aureus, suggesting that syndecan-1 does not mediate S. aureus attachment to Corneal tissues in vivo. Instead, S. aureus induced the shedding of syndecan-1 ectodomains from the surface of Corneal epithelial cells. Topical administration of purified syndecan-1 ectodomains or heparan sulfate (HS) significantly increased, whereas inhibition of syndecan-1 shedding significantly decreased the bacterial burden in Corneal tissues. Furthermore, depletion of neutrophils in the resistant Sdc1−/− mice increased the Corneal bacterial burden to that of the susceptible WT mice, suggesting that syndecan-1 moderates neutrophils to promote Infection. We found that syndecan-1 does not affect the infiltration of neutrophils into the infected cornea but that purified syndecan-1 ectodomain and HS significantly inhibit neutrophil-mediated killing of S. aureus. These data suggest a previously unknown bacterial subversion mechanism where S. aureus exploits the capacity of syndecan-1 ectodomains to inhibit neutrophil-mediated bacterial killing mechanisms in an HS-dependent manner to promote its pathogenesis in the cornea.
David J Evans - One of the best experts on this subject based on the ideXlab platform.
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contact lens related Corneal Infection intrinsic resistance and its compromise
Progress in Retinal and Eye Research, 2020Co-Authors: Suzanne M J Fleiszig, Abby R Kroken, Vincent Nieto, Melinda R Grosser, Stephanie Wan, Matteo M E Metruccio, David J EvansAbstract:Abstract Contact lenses represent a widely utilized form of vision correction with more than 140 million wearers worldwide. Although generally well-tolerated, contact lenses can cause Corneal Infection (microbial keratitis), with an approximate annualized incidence ranging from ~2 to ~20 cases per 10,000 wearers, and sometimes resulting in permanent vision loss. Research suggests that the pathogenesis of contact lens-associated microbial keratitis is complex and multifactorial, likely requiring multiple conspiring factors that compromise the intrinsic resistance of a healthy cornea to Infection. Here, we outline our perspective of the mechanisms by which contact lens wear sometimes renders the cornea susceptible to Infection, focusing primarily on our own research efforts during the past three decades. This has included studies of host factors underlying the constitutive barrier function of the healthy cornea, its response to bacterial challenge when intrinsic resistance is not compromised, pathogen virulence mechanisms, and the effects of contact lens wear that alter the outcome of host-microbe interactions. For almost all of this work, we have utilized the bacterium Pseudomonas aeruginosa because it is the leading cause of lens-related microbial keratitis. While not yet common among Corneal isolates, clinical isolates of P. aeruginosa have emerged that are resistant to virtually all currently available antibiotics, leading the United States CDC (Centers for Disease Control) to add P. aeruginosa to its list of most serious threats. Compounding this concern, the development of advanced contact lenses for biosensing and augmented reality, together with the escalating incidence of myopia, could portent an epidemic of vision-threatening Corneal Infections in the future. Thankfully, technological advances in genomics, proteomics, metabolomics and imaging combined with emerging models of contact lens-associated P. aeruginosa Infection hold promise for solving the problem - and possibly life-threatening Infections impacting other tissues.
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DMBT1 purified from saliva protects against P. aeruginosa Corneal Infection.
2017Co-Authors: Matteo M E Metruccio, David J Evans, Suzanne M J FleiszigAbstract:(A) Representative images of C57BL/6 murine corneas at 24 and 48 h and post-Infection with P. aeruginosa PAO1 in PBS or DMBT1 (150 ng/μL). (B) Schematic for grading disease severity of infected murine corneas. Effect of DMBT1 on Corneal Infection disease severity scores at 24 and 48 h comparing (C) area of Infection, (D) density of opacity, (E) Corneal surface irregularity, and (F) total disease severity, the sum of values shown in (C), (D), and (E). Data are reported as the mean ± SEM per group over three independent experiments (6 mice per group in total). Significance of differences between groups was determined using the Mann-Whitney U test. **, P < 0.01; *, P < 0.05; ns, not significant.
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surfactant protein d contributes to ocular defense against pseudomonas aeruginosa in a murine model of dry eye disease
PLOS ONE, 2013Co-Authors: Suzanne M J Fleiszig, David J Evans, Susan R Heimer, James J Mun, Michael E SternAbstract:Dry eye disease can cause ocular surface inflammation that disrupts the Corneal epithelial barrier. While dry eye patients are known to have an increased risk of Corneal Infection, it is not known whether there is a direct causal relationship between these two conditions. Here, we tested the hypothesis that experimentally-induced dry eye (EDE) increases susceptibility to Corneal Infection using a mouse model. In doing so, we also examined the role of surfactant protein D (SP-D), which we have previously shown is involved in Corneal defense against Infection. Scopolamine injections and fan-driven air were used to cause EDE in C57BL/6 or Black Swiss mice (wild-type and SP-D gene-knockout). Controls received PBS injections and were housed normally. After 5 or 10 days, otherwise uninjured corneas were inoculated with 10(9) cfu of Pseudomonas aeruginosa strain PAO1. Anesthesia was maintained for 3 h post-inoculation. Viable bacteria were quantified in ocular surface washes and Corneal homogenates 6 h post-inoculation. SP-D was measured by Western immunoblot, and Corneal pathology assessed from 6 h to 4 days. EDE mice showed reduced tear volumes after 5 and 10 days (each by ∼75%, p<0.001) and showed fluorescein staining (i.e. epithelial disruption). Surprisingly, there was no significant difference in Corneal pathology between EDE mice and controls (∼10-14% incidence). Before bacterial inoculation, EDE mice showed elevated SP-D in ocular washes. After inoculation, fewer bacteria were recovered from ocular washes of EDE mice (<2% of controls, p = 0.0004). Furthermore, SP-D knockout mice showed a significant increase in P. aeruginosa Corneal colonization under EDE conditions. Taken together, these data suggest that SP-D contributes to Corneal defense against P. aeruginosa colonization and Infection in EDE despite the loss of barrier function to fluorescein.
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twitching motility contributes to the role of pili in Corneal Infection caused by pseudomonas aeruginosa
Infection and Immunity, 2003Co-Authors: I Zolfaghar, David J Evans, Suzanne M J FleiszigAbstract:Twitching motility is a form of surface-associated bacterial movement mediated by type IV pili of Pseudomonas aeruginosa. Others have shown that pilT and pilU mutants, which are piliated but defective in twitching motility, display reduced cytotoxic capacity towards epithelial cells in vitro. Although these mutants efficiently infected lungs in vivo, they were defective in dissemination to the liver. In this study the role of twitching motility in P. aeruginosa epithelial cell invasion and Corneal disease pathogenesis was explored. pilU and pilT mutants of P. aeruginosa strain PAK were compared to a nonpiliated pilA mutant and to wild-type bacteria in their ability to associate with and to invade Corneal epithelial cells in vitro and to cause disease in a murine model of Corneal Infection. As expected, the pilA mutant demonstrated reduced association and invasion of Corneal epithelial cells (P < 0.05 in both cases). The pilT mutant, but not the pilU mutant, was less invasive than wild-type PAK was (P < 0.05 versus P = 0.43), while both pilU and pilT mutants exhibited association levels similar to those of the wild type (P = 0.31 and 0.52, respectively). In vivo, all mutants were markedly attenuated in virulence and showed reduced ability to colonize the cornea at 4 and 48 h (all P values < 0.02). Thus, twitching motility contributed to the role of pili in Corneal disease but was not involved in the role of pili in adherence to or invasion of Corneal epithelial cells.
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contribution of exsa regulated factors to Corneal Infection by cytotoxic and invasive pseudomonas aeruginosa in a murine scarification model
Investigative Ophthalmology & Visual Science, 2003Co-Authors: Ellen J Lee, David J Evans, Brigitte A Cowell, Suzanne M J FleiszigAbstract:PURPOSE The exoenzyme S regulatory protein ExsA regulates a type III secretion system in Pseudomonas aeruginosa. In vitro, cytotoxic strains use this system to secrete exotoxin (Exo)U and ExoT causing cytotoxicity and inhibiting their phagocytosis by epithelial cells. Invasive P. aeruginosa secrete ExoT and ExoS, but exsA mutation has little impact on their short-term interactions with epithelia. In the present study, the contribution of these ExsA-regulated proteins toward Corneal Infections in vivo was investigated. METHODS After anesthesia, the left cornea of C57BL/6 mice was scratch injured and then inoculated with cytotoxic (PA103) or invasive (PAK) P. aeruginosa or with isogenic mutants in exsA-related genes. Inocula of 10(3) to 10(6) bacteria/5 micro L were used, and at least five animals were assigned to each experimental group. Corneal disease was quantified at regular intervals for 14 days in masked fashion with two different scoring systems. RESULTS For the cytotoxic strain, mutation of either exoU or exoT alone had little effect on virulence, whereas simultaneous mutation of both exoT and exoU or of exsA resulted in a significantly reduced capacity to cause Corneal disease. Complementation of the double exoUexoT mutant with exoU alone restored bacterial colonization levels (>3-log increase) and disease severity to wild-type levels. Complementation with exoT alone increased colonization ( approximately 3-log increase) and increased virulence to almost the same levels as wild-type or exoU-complemented Infections. Virulence of the invasive strain was not reduced by mutation of exsA or of genes encoding the ExsA-regulated secreted proteins. CONCLUSIONS ExsA contributed to Corneal virulence of only cytotoxic P. aeruginosa, with contributions made by both ExoU and ExoT to bacterial survival and disease severity. This differs from cytotoxic P. aeruginosa virulence in the lung, which is ExoU-dependent.
Suzanne M J Fleiszig - One of the best experts on this subject based on the ideXlab platform.
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contact lens related Corneal Infection intrinsic resistance and its compromise
Progress in Retinal and Eye Research, 2020Co-Authors: Suzanne M J Fleiszig, Abby R Kroken, Vincent Nieto, Melinda R Grosser, Stephanie Wan, Matteo M E Metruccio, David J EvansAbstract:Abstract Contact lenses represent a widely utilized form of vision correction with more than 140 million wearers worldwide. Although generally well-tolerated, contact lenses can cause Corneal Infection (microbial keratitis), with an approximate annualized incidence ranging from ~2 to ~20 cases per 10,000 wearers, and sometimes resulting in permanent vision loss. Research suggests that the pathogenesis of contact lens-associated microbial keratitis is complex and multifactorial, likely requiring multiple conspiring factors that compromise the intrinsic resistance of a healthy cornea to Infection. Here, we outline our perspective of the mechanisms by which contact lens wear sometimes renders the cornea susceptible to Infection, focusing primarily on our own research efforts during the past three decades. This has included studies of host factors underlying the constitutive barrier function of the healthy cornea, its response to bacterial challenge when intrinsic resistance is not compromised, pathogen virulence mechanisms, and the effects of contact lens wear that alter the outcome of host-microbe interactions. For almost all of this work, we have utilized the bacterium Pseudomonas aeruginosa because it is the leading cause of lens-related microbial keratitis. While not yet common among Corneal isolates, clinical isolates of P. aeruginosa have emerged that are resistant to virtually all currently available antibiotics, leading the United States CDC (Centers for Disease Control) to add P. aeruginosa to its list of most serious threats. Compounding this concern, the development of advanced contact lenses for biosensing and augmented reality, together with the escalating incidence of myopia, could portent an epidemic of vision-threatening Corneal Infections in the future. Thankfully, technological advances in genomics, proteomics, metabolomics and imaging combined with emerging models of contact lens-associated P. aeruginosa Infection hold promise for solving the problem - and possibly life-threatening Infections impacting other tissues.
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DMBT1 purified from saliva protects against P. aeruginosa Corneal Infection.
2017Co-Authors: Matteo M E Metruccio, David J Evans, Suzanne M J FleiszigAbstract:(A) Representative images of C57BL/6 murine corneas at 24 and 48 h and post-Infection with P. aeruginosa PAO1 in PBS or DMBT1 (150 ng/μL). (B) Schematic for grading disease severity of infected murine corneas. Effect of DMBT1 on Corneal Infection disease severity scores at 24 and 48 h comparing (C) area of Infection, (D) density of opacity, (E) Corneal surface irregularity, and (F) total disease severity, the sum of values shown in (C), (D), and (E). Data are reported as the mean ± SEM per group over three independent experiments (6 mice per group in total). Significance of differences between groups was determined using the Mann-Whitney U test. **, P < 0.01; *, P < 0.05; ns, not significant.
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surfactant protein d contributes to ocular defense against pseudomonas aeruginosa in a murine model of dry eye disease
PLOS ONE, 2013Co-Authors: Suzanne M J Fleiszig, David J Evans, Susan R Heimer, James J Mun, Michael E SternAbstract:Dry eye disease can cause ocular surface inflammation that disrupts the Corneal epithelial barrier. While dry eye patients are known to have an increased risk of Corneal Infection, it is not known whether there is a direct causal relationship between these two conditions. Here, we tested the hypothesis that experimentally-induced dry eye (EDE) increases susceptibility to Corneal Infection using a mouse model. In doing so, we also examined the role of surfactant protein D (SP-D), which we have previously shown is involved in Corneal defense against Infection. Scopolamine injections and fan-driven air were used to cause EDE in C57BL/6 or Black Swiss mice (wild-type and SP-D gene-knockout). Controls received PBS injections and were housed normally. After 5 or 10 days, otherwise uninjured corneas were inoculated with 10(9) cfu of Pseudomonas aeruginosa strain PAO1. Anesthesia was maintained for 3 h post-inoculation. Viable bacteria were quantified in ocular surface washes and Corneal homogenates 6 h post-inoculation. SP-D was measured by Western immunoblot, and Corneal pathology assessed from 6 h to 4 days. EDE mice showed reduced tear volumes after 5 and 10 days (each by ∼75%, p<0.001) and showed fluorescein staining (i.e. epithelial disruption). Surprisingly, there was no significant difference in Corneal pathology between EDE mice and controls (∼10-14% incidence). Before bacterial inoculation, EDE mice showed elevated SP-D in ocular washes. After inoculation, fewer bacteria were recovered from ocular washes of EDE mice (<2% of controls, p = 0.0004). Furthermore, SP-D knockout mice showed a significant increase in P. aeruginosa Corneal colonization under EDE conditions. Taken together, these data suggest that SP-D contributes to Corneal defense against P. aeruginosa colonization and Infection in EDE despite the loss of barrier function to fluorescein.
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twitching motility contributes to the role of pili in Corneal Infection caused by pseudomonas aeruginosa
Infection and Immunity, 2003Co-Authors: I Zolfaghar, David J Evans, Suzanne M J FleiszigAbstract:Twitching motility is a form of surface-associated bacterial movement mediated by type IV pili of Pseudomonas aeruginosa. Others have shown that pilT and pilU mutants, which are piliated but defective in twitching motility, display reduced cytotoxic capacity towards epithelial cells in vitro. Although these mutants efficiently infected lungs in vivo, they were defective in dissemination to the liver. In this study the role of twitching motility in P. aeruginosa epithelial cell invasion and Corneal disease pathogenesis was explored. pilU and pilT mutants of P. aeruginosa strain PAK were compared to a nonpiliated pilA mutant and to wild-type bacteria in their ability to associate with and to invade Corneal epithelial cells in vitro and to cause disease in a murine model of Corneal Infection. As expected, the pilA mutant demonstrated reduced association and invasion of Corneal epithelial cells (P < 0.05 in both cases). The pilT mutant, but not the pilU mutant, was less invasive than wild-type PAK was (P < 0.05 versus P = 0.43), while both pilU and pilT mutants exhibited association levels similar to those of the wild type (P = 0.31 and 0.52, respectively). In vivo, all mutants were markedly attenuated in virulence and showed reduced ability to colonize the cornea at 4 and 48 h (all P values < 0.02). Thus, twitching motility contributed to the role of pili in Corneal disease but was not involved in the role of pili in adherence to or invasion of Corneal epithelial cells.
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contribution of exsa regulated factors to Corneal Infection by cytotoxic and invasive pseudomonas aeruginosa in a murine scarification model
Investigative Ophthalmology & Visual Science, 2003Co-Authors: Ellen J Lee, David J Evans, Brigitte A Cowell, Suzanne M J FleiszigAbstract:PURPOSE The exoenzyme S regulatory protein ExsA regulates a type III secretion system in Pseudomonas aeruginosa. In vitro, cytotoxic strains use this system to secrete exotoxin (Exo)U and ExoT causing cytotoxicity and inhibiting their phagocytosis by epithelial cells. Invasive P. aeruginosa secrete ExoT and ExoS, but exsA mutation has little impact on their short-term interactions with epithelia. In the present study, the contribution of these ExsA-regulated proteins toward Corneal Infections in vivo was investigated. METHODS After anesthesia, the left cornea of C57BL/6 mice was scratch injured and then inoculated with cytotoxic (PA103) or invasive (PAK) P. aeruginosa or with isogenic mutants in exsA-related genes. Inocula of 10(3) to 10(6) bacteria/5 micro L were used, and at least five animals were assigned to each experimental group. Corneal disease was quantified at regular intervals for 14 days in masked fashion with two different scoring systems. RESULTS For the cytotoxic strain, mutation of either exoU or exoT alone had little effect on virulence, whereas simultaneous mutation of both exoT and exoU or of exsA resulted in a significantly reduced capacity to cause Corneal disease. Complementation of the double exoUexoT mutant with exoU alone restored bacterial colonization levels (>3-log increase) and disease severity to wild-type levels. Complementation with exoT alone increased colonization ( approximately 3-log increase) and increased virulence to almost the same levels as wild-type or exoU-complemented Infections. Virulence of the invasive strain was not reduced by mutation of exsA or of genes encoding the ExsA-regulated secreted proteins. CONCLUSIONS ExsA contributed to Corneal virulence of only cytotoxic P. aeruginosa, with contributions made by both ExoU and ExoT to bacterial survival and disease severity. This differs from cytotoxic P. aeruginosa virulence in the lung, which is ExoU-dependent.
Atsuko Hayashida - One of the best experts on this subject based on the ideXlab platform.
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syndecan 1 promotes streptococcus pneumoniae Corneal Infection by facilitating the assembly of adhesive fibronectin fibrils
Mbio, 2020Co-Authors: Akiko Jinno, Pyong Woo Park, Atsuko Hayashida, Howard F JenkinsonAbstract:ABSTRACT Subversion of heparan sulfate proteoglycans (HSPGs) is thought to be a common virulence mechanism shared by many microbial pathogens. The prevailing assumption is that pathogens co-opt HSPGs as cell surface attachment receptors or as inhibitors of innate host defense. However, there are few data that clearly support this idea in vivo. We found that deletion of syndecan-1 (Sdc1), a major cell surface HSPG of epithelial cells, causes a gain of function in a mouse model of scarified Corneal Infection, where Sdc1−/− corneas were significantly less susceptible to Streptococcus pneumoniae Infection. Administration of excess Sdc1 ectodomains significantly inhibited S. pneumoniae Corneal Infection, suggesting that Sdc1 promotes Infection as a cell surface attachment receptor. However, S. pneumoniae did not interact with Sdc1 and Sdc1 was shed upon S. pneumoniae Infection, indicating that Sdc1 does not directly support S. pneumoniae adhesion. Instead, Sdc1 promoted S. pneumoniae adhesion by driving the assembly of fibronectin (FN) fibrils in the Corneal basement membrane to which S. pneumoniae attaches when infecting injured corneas. S. pneumoniae specifically bound to Corneal FN via PavA, and PavA deletion significantly attenuated S. pneumoniae virulence in the cornea. Excess Sdc1 ectodomains inhibited S. pneumoniae Corneal Infection by binding to the Hep II domain and interfering with S. pneumoniae PavA binding to FN. These findings reveal a previously unknown virulence mechanism of S. pneumoniae where key extracellular matrix (ECM) interactions and structures that are essential for host cell homeostasis are exploited for bacterial pathogenesis. IMPORTANCE Bacterial pathogens have evolved several ingenious mechanisms to subvert host cell biology for their pathogenesis. Bacterial attachment to the host ECM establishes a niche to grow and is considered one of the critical steps of Infection. This pathogenic mechanism entails coordinated assembly of the ECM by the host to form the ECM structure and organization that are specifically recognized by bacteria for their adhesion. We serendipitously discovered that epithelial Sdc1 facilitates the assembly of FN fibrils in the Corneal basement membrane and that this normal biological function of Sdc1 has detrimental consequences for the host in S. pneumoniae Corneal Infection. Our studies suggest that bacterial subversion of the host ECM is more complex than previously appreciated.
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2 o sulfated domains in syndecan 1 heparan sulfate inhibit neutrophil cathelicidin and promote staphylococcus aureus Corneal Infection
Journal of Biological Chemistry, 2015Co-Authors: Atsuko Hayashida, Shiro Amano, Richard L Gallo, Robert J Linhardt, Pyong Woo ParkAbstract:Abstract Ablation of syndecan-1 in mice is a gain of function mutation that enables mice to significantly resist Infection by several bacterial pathogens. Syndecan-1 shedding is induced by bacterial virulence factors, and inhibition of shedding attenuates bacterial virulence, whereas administration of purified syndecan-1 ectodomain enhances virulence, suggesting that bacteria subvert syndecan-1 ectodomains released by shedding for their pathogenesis. However, the pro-pathogenic functions of syndecan-1 ectodomain have yet to be clearly defined. Here, we examined how syndecan-1 ectodomain enhances Staphylococcus aureus virulence in injured mouse corneas. We found that syndecan-1 ectodomain promotes S. aureus Corneal Infection in an HS-dependent manner. Surprisingly, we found that this pro-pathogenic activity is dependent on 2-O-sulfated domains in HS, indicating that the effects of syndecan-1 ectodomain are structure-based. Our results also showed that purified syndecan-1 ectodomain and heparan compounds containing 2-O-sulfate motifs inhibit S. aureus killing by antimicrobial factors secreted by degranulated neutrophils, but does not affect intracellular phagocytic killing by neutrophils. Immunodepletion of antimicrobial factors with staphylocidal activities demonstrated that CRAMP, a cationic antimicrobial peptide, is primarily responsible for S. aureus killing among other factors secreted by degranulated neutrophils. Furthermore, we found that purified syndecan-1 ectodomain and heparan compounds containing 2-O-sulfate units potently and specifically inhibit S. aureus killing by synthetic CRAMP. These results provide compelling evidence that a specific subclass of sulfate groups, and not the overall charge of HS, permits syndecan-1 ectodomains to promote S. aureus Corneal Infection by inhibiting a key arm of neutrophil host defense.
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syndecan 1 promotes staphylococcus aureus Corneal Infection by counteracting neutrophil mediated host defense
Journal of Biological Chemistry, 2011Co-Authors: Atsuko Hayashida, Shiro Amano, Pyong Woo ParkAbstract:Many microbial pathogens subvert cell surface heparan sulfate proteoglycans (HSPGs) to infect host cells in vitro. The significance of HSPG-pathogen interactions in vivo, however, remains to be determined. In this study, we examined the role of syndecan-1, a major cell surface HSPG of epithelial cells, in Staphylococcus aureus Corneal Infection. We found that syndecan-1 null (Sdc1−/−) mice significantly resist S. aureus Corneal Infection compared with wild type (WT) mice that express abundant syndecan-1 in their Corneal epithelium. However, syndecan-1 did not bind to S. aureus, and syndecan-1 was not required for the colonization of cultured Corneal epithelial cells by S. aureus, suggesting that syndecan-1 does not mediate S. aureus attachment to Corneal tissues in vivo. Instead, S. aureus induced the shedding of syndecan-1 ectodomains from the surface of Corneal epithelial cells. Topical administration of purified syndecan-1 ectodomains or heparan sulfate (HS) significantly increased, whereas inhibition of syndecan-1 shedding significantly decreased the bacterial burden in Corneal tissues. Furthermore, depletion of neutrophils in the resistant Sdc1−/− mice increased the Corneal bacterial burden to that of the susceptible WT mice, suggesting that syndecan-1 moderates neutrophils to promote Infection. We found that syndecan-1 does not affect the infiltration of neutrophils into the infected cornea but that purified syndecan-1 ectodomain and HS significantly inhibit neutrophil-mediated killing of S. aureus. These data suggest a previously unknown bacterial subversion mechanism where S. aureus exploits the capacity of syndecan-1 ectodomains to inhibit neutrophil-mediated bacterial killing mechanisms in an HS-dependent manner to promote its pathogenesis in the cornea.
Nerida Cole - One of the best experts on this subject based on the ideXlab platform.
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evaluation of synergistic activity of bovine lactoferricin with antibiotics in Corneal Infection
Journal of Antimicrobial Chemotherapy, 2010Co-Authors: Nerida Cole, Mark D P Willcox, Linda Garthwaite, Hua ZhuAbstract:Objectives The objectives of this study were to determine whether a synergistic effect could be obtained in vitro between bovine lactoferricin (B-LFcin) and antibiotics against Pseudomonas aeruginosa and Staphylococcus aureus isolates from ocular Infections, and to evaluate the use of B-LFcin as an adjunct to the antibiotic treatment of Corneal Infection in vivo. Methods Chequerboard and time-kill assays were performed to investigate the combined effects of B-LFcin and conventional antibiotics, including ciprofloxacin, ceftazidime and gentamicin, against 17 strains of P. aeruginosa (8) and S. aureus (9) isolated from ocular Infection and inflammation, and 1 reference strain of S. aureus. Corneas of C57BL/6 mice were topically challenged with a multidrug-resistant strain of P. aeruginosa. Nine hours post-challenge, mice were treated topically and hourly with either vehicle, B-LFcin, ciprofloxacin or ciprofloxacin containing B-LFcin for 8 h. Corneas were then clinically examined, and bacterial numbers and levels of myeloperoxidase (MPO) evaluated. Results Synergy between B-LFcin and ciprofloxacin or ceftazidime was identified in most P. aeruginosa isolates, including multidrug-resistant strains, whereas no synergistic effect was seen between B-LFcin and gentamicin. Synergy was only observed with B-LFcin and ciprofloxacin against 2/10 S. aureus strains, and there was no synergy between B-LFcin and any of the other antibiotics tested. Combined B-LFcin and ciprofloxacin treatment significantly improved the clinical outcome, and reduced bacterial numbers and MPO in infected mouse corneas. B-LFcin alone was also able to reduce levels of MPO in infected corneas. Conclusions These findings indicate that B-LFcin may have advantages as an adjunct therapy with both antimicrobial and anti-inflammatory properties in the treatment of Corneal Infection.
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The epidemiology of contact lens related infiltrates
Optometry and Vision Science, 2007Co-Authors: Fiona Stapleton, Lisa Keay, Isabelle Jalbert, Nerida ColeAbstract:With estimated numbers of contact lens wearers worldwide exceeding 140 million, even complications with a low incidence will affect a significant number of individuals. Although contact lenses clearly have many advantages for wearers, certain risks have been associated with their use. Differences in risk for different types of contact lenses and wearing patterns have been demonstrated for both rare and common lens related complications. This review particularly focuses on the incidence and etiology of contact lens related Corneal Infection and inflammation. An understanding of the risks and contributory factors to these conditions is important for practitioners and will enable an informed choice of safer lens wear modalities, wear schedules, and hygiene regimes to be made.