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Peripheral blood vessels are a niche for blood-borne meningococci.

ABSTRACT: Neisseria meningitidis is the causative agent of cerebrospinal meningitis and that of a rapidly progressing fatal septic shock known as purpura fulminans. Meningococcemia is characterized by bacterial adhesion to human endothelial cells of the microvessels. Host specificity has hampered studies on the role of blood vessels colonization in N. meningitidis associated pathogenesis. In this work, using a humanized model of SCID mice allowing the study of bacterial adhesion to human cells in an in vivo context we demonstrate that meningococcal colonization of human blood vessels is a prerequisite to the establishment of sepsis and lethality. To identify the molecular pathways involved in bacterial virulence, we performed transposon insertion site sequencing (Tn-seq) in vivo. Our results demonstrate that 36% of the genes that are important for growth in the blood of mice are dispensable when bacteria colonize human blood vessels, suggesting that human endothelial cells lining the blood vessels are feeding niches for N. meningitidis in vivo. Altogether, our work proposes a new paradigm for meningococcal virulence in which colonization of blood vessels is associated with metabolic adaptation and sustained bacteremia responsible for sepsis and subsequent lethality.

SUBMITTER: Capel E

PROVIDER: S-EPMC5810509 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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Peripheral blood vessels are a niche for blood-borne meningococci.

Capel Elena E Barnier Jean-Philippe JP Zomer Aldert L AL Bole-Feysot Christine C Nussbaumer Thomas T Jamet Anne A Lécuyer Hervé H Euphrasie Daniel D Virion Zoé Z Frapy Eric E Pélissier Philippe P Join-Lambert Olivier O Rattei Thomas T Bourdoulous Sandrine S Nassif Xavier X Coureuil Mathieu M

Virulence 20171127 8

Neisseria meningitidis is the causative agent of cerebrospinal meningitis and that of a rapidly progressing fatal septic shock known as purpura fulminans. Meningococcemia is characterized by bacterial adhesion to human endothelial cells of the microvessels. Host specificity has hampered studies on the role of blood vessels colonization in N. meningitidis associated pathogenesis. In this work, using a humanized model of SCID mice allowing the study of bacterial adhesion to human cells in an in vi ...[more]

PMID: 29099305

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Project description:BackgroundPolymyxin B-immobilized fiber column hemoperfusion (PMX) has been reported to be effective for patients with septic shock. It remains unclear, however, how the efficacy of PMX varies according to the characteristics and underlying conditions of the patients treated. The objective of the present study was to clarify the factors that result in clinical efficacy of PMX treatment.MethodsWe retrospectively investigated 78 consecutive patients with severe sepsis or septic shock who underwent PMX treatment. We reviewed the demographic data, routine biochemistry, microbiological data, infection focus, Acute Physiology and Chronic Health Evaluation (APACHE) II score, Sequential Organ Failure Assessment (SOFA) score, change in mean arterial pressure (MAP), inotropic score, vasopressor dependency index, plasma levels of endotoxin and lactate, PaO2/FIO2 ratio, and survival time. We also divided the patients into two groups for comparison, namely, those whose inotropic scores improved after PMX treatment (improvement group) and those whose inotropic scores did not improve (non-improvement group).ResultsThe inotropic score and the vasopressor dependency index significantly decreased from 18.1 to 9.9 (p < 0.05) and from 0.27 to 0.14 (p < 0.05), respectively, after PMX treatment in the overall study population, while no significant change in the PaO2/FIO2 ratio was observed (p = 0.96). The inotropic score at pre-PMX treatment was significantly higher in the improvement group than in the non-improvement group (p < 0.01). The improvement of the PaO2/FIO2 ratio after PMX treatment was significant in the improvement group (p < 0.05).ConclusionsThe improvement group's inotropic score was higher, because of peripheral blood vessels dilatation and requirement for more catecholamines. Therefore, our study suggests that PMX treatment is particularly useful for improving hemodynamics in septic shock patients with excessively dilated peripheral blood vessels.

Project description:ObjectiveThe human acellular vessel (HAV) was evaluated for surgical bypass in a phase II study. The primary results at 24 months after implantation have been reported, and the patients will be evaluated for ≤10 years.MethodsIn the present report, we have described the 6-year results of a prospective, open-label, single-treatment arm, multicenter study. Patients with advanced peripheral artery disease (PAD) requiring above-the-knee femoropopliteal bypass surgery without available autologous graft options had undergone implantation with the HAV, a bioengineered human tissue replacement blood vessel. The patients who completed the 24-month primary portion of the study will be evaluated for ≤10 years after implantation. The present mid-term analysis was performed at the 6-year milestone (72 months) for patients followed up for 24 to 72 months.ResultsHAVs were implanted in 20 patients at three sites in Poland. Seven patients had discontinued the study before completing the 2-year portion of the study: four after graft occlusion had occurred and three who had died of causes deemed unrelated to the conduit, with the HAV reported as functional at their last visit. The primary results at 24 months showed primary, primary assisted, and secondary patency rates of 58%, 58%, and 74%, respectively. One vessel had developed a pseudoaneurysm deemed possibly iatrogenic; no other signs of structural failure were reported. No rejections or infections of the HAV occurred, and no patient had required amputation of the implanted limb. Of the 20 patients, 13 had completed the primary portion of the study; however, 1 patient had died shortly after 24 months. Of the remaining 12 patients, 3 died of causes unrelated to the HAV. One patient had required thrombectomy twice, with secondary patency achieved. No other interventions were recorded between 24 and 72 months. At 72 months, five patients had a patent HAV, including four patients with primary patency. For the entire study population from day 1 to month 72, the overall primary, primary assisted, and secondary patency rate estimated using Kaplan-Meier analysis was 44%, 45%, and 60% respectively, with censoring for death. No patient had experienced rejection or infection of the HAV, and no patient had required amputation of the implanted limb.ConclusionsThe infection-resistant, off-the-shelf HAV could provide a durable alternative conduit in the arterial circuit setting to restore the lower extremity blood supply in patients with PAD, with remodeling into the recipient's own vessel over time. The HAV is currently being evaluated in seven clinical trials to treat PAD, vascular trauma, and as a hemodialysis access conduit.

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Peripheral blood vessels are a niche for blood-borne meningococci.

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Peripheral blood vessels are a niche for blood-borne meningococci.

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