Porphyromonas gingivalis-nucleoside-diphosphate-kinase inhibits ATP-induced reactive-oxygen-species via P2X7 receptor / NADPH-oxidase signaling and contributes to persistence

Ligation of P2X7 receptors with a \u27danger signal\u27, extracellular ATP (eATP), has recently been shown to result in production of intracellular reactive-oxygen-species (ROS) in macrophages. We show that primary gingival epithelial cells (GECs) produce sustained, robust cellular ROS upon stimulation by eATP. The induction of ROS was mediated by P2X7 receptor signalling coupled with NADPH-oxidase activation, as determined by pharmacological inhibition and RNA interference. Furthermore, Porphyromonas gingivalis, an oral opportunistic pathogen, upregulated the antioxidant glutathione response, modulated eATP-induced cytosolic and mitochondrial ROS generated through P2X7 /NADPH-oxidase interactome, and subsequently blocked oxidative stress in GECs via temporal secretion of a P. gingivalis effector, nucleoside-diphosphate-kinase (Ndk). An ndk-deficient P. gingivalis mutant lacked the ability to inhibit ROS production and persist intracellularly following eATP stimulation. Treatment with recombinant Ndk significantly diminished eATP-evoked ROS production. P. gingivalis infection elicited a strong, time-dependent increase in anti-oxidativemitochondrial UCP2 levels, whereas ndk-deficient mutant did not cause any change. The results reveal a novel signalling cascade that is tightly coupled with eATP signalling and ROS regulation. Ndk by P. gingivalis counteracts these antimicrobial signalling activities by secreting Ndk, thus contributing to successful persistence of the pathogen

ATP-dependent activation of an inflammasome in primary gingival epithelial cells infected by Porphyromonas gingivalis

Production of IL-1 beta typically requires two-separate signals. The first signal, from a pathogen-associated molecular pattern, promotes intracellular production of immature cytokine. The second signal, derived from a danger signal such as extracellular ATP, results in assembly of an inflammasome, activation of caspase-1 and secretion of mature cytokine. The inflammasome component, Nalp3, plays a non-redundant role in caspase-1 activation in response to ATP binding to P2X(7) in macrophages. Gingival epithelial cells (GECs) are an important component of the innate-immune response to periodontal bacteria. We had shown that GECs express a functional P2X(7) receptor, but the ability of GECs to secrete IL-1 beta during infection remained unknown. We find that GECs express a functional Nalp3 inflammasome. Treatment of GECs with LPS or infection with the periodontal pathogen, Porphyromonas gingivalis, induced expression of the il-1 beta gene and intracellular accumulation of IL-1 beta protein. However, IL-1 beta was not secreted unless LPS-treated or infected cells were subsequently stimulated with ATP. Conversely, caspase-1 is activated in GECs following ATP treatment but not P. gingivalis infection. Furthermore, depletion of Nalp3 by siRNA abrogated the ability of ATP to induce IL-1 beta secretion in infected cells. The Nalp3 inflammasome is therefore likely to be an important mediator of the inflammatory response in gingival epithelium

Rotavirus gastroenteritis in a neonatal unit of a Greek tertiary hospital: Clinical characteristics and genotypes

Introduction Rotavirus (RV) infection in neonatal age can be mild or even asymptomatic. Several studies have reported that RV is responsible for 31%-87% of pediatric nosocomial diarrhea and causes gastroenteritis outbreaks in pediatric and neonatal units. Objectives Study clinical characteristics, genotypes and risk factors of RV infection in neonatal age. Methods A prospective study was conducted from April 2009 till April 2013 in the neonatal special care unit of the largest tertiary pediatric hospital of Greece. Fecal samples and epidemiological data were collected from each neonate with gastrointestinal symptoms. RV antigen was detected with a rapid immunochromatography test. RV positive samples were further genotyped with RT PCR and sequencing using specific VP7 and VP4 primers. Results Positive for RV were 126/415 samples (30.4%). Mean age of onset was 18 days. Seventy four cases (58%) were hospital acquired. Seasonality of RV infection did not differ significantly throughout the year with the exception of 4 outbreaks. Genotypes found during the study period were G4P[8] (58.7%), G1P[8] (14.7%), G12P[8] (9.3%), G3P[8] (9.3%), G12P [6] (5.3%), G9P[8] (1.3%) and G2P[4] (1.3%). RV cases presented with: diarrhea (81%), vomiting (26.2%), fever (34.9%), dehydration (28.6%), feeding intolerance (39.7%), weight loss (54%), whilst 19% of cases were asymptomatic. Comparing community with hospital acquired cases differences in clinical manifestations were found. Conclusions Significant incidence of nosocomially transmitted RV infection in neonatal age including asymptomatic illness exists. Genotypes causing nosocomial outbreaks are not different from community strains. Circulating vaccines can be effective in prevention of nosocomial RV infection through herd immunity. © 2015 Koukou et al

Trends of Antithrombotic Treatment in Atrial Fibrillation Patients Undergoing Percutaneous Coronary Intervention: Insights from the GReek-AntiPlatElet Atrial Fibrillation (GRAPE-AF) Registry

Purpose: Patients with atrial fibrillation (AF) undergoing percutaneous coronary intervention (PCI) are a high-risk subset of patients, whose optimal antithrombotic treatment strategy, involving a combination of anticoagulant and antiplatelet agents, has not been well defined. Our study aims to investigate contemporary “real-world” trends of antithrombotic treatment strategies in AF patients undergoing PCI, as well as identify factors affecting decision-making at hospital discharge. Methods: “Real-world” data were retrieved from the GReek-AntiPlatElet Atrial Fibrillation (GRAPE-AF) registry, a contemporary, nationwide, multicenter, observational study of AF patients undergoing PCI. Characteristics of patients discharged on triple antithrombotic therapy (TAT) or dual antithrombotic therapy (DAT) were compared in order to identify factors that could influence treatment decisions. Results: A total of 654 patients were enrolled (42% with stable coronary artery disease, 58% with acute coronary syndrome). TAT was adopted in 49.9% and DAT in 49.2% of patients at discharge. Regarding anticoagulants, the vast majority of patients (92.9%) received non-vitamin K antagonist oral anticoagulants (NOACs) and only 7.1% received vitamin K antagonists (VKAs). Dyslipidemia, insulin-dependent diabetes mellitus, prior myocardial infarction, acute coronary syndrome at presentation, and regional variations were predictive of TAT adoption, whereas the use of NOACs or ticagrelor was predictive of DAT adoption. Conclusion: Contemporary “real-world” data concerning antithrombotic treatment in AF patients undergoing PCI indicate a strong shift towards the use of NOACs instead of VKAs, along with a large subset of patients adopting an aspirin-free strategy early after index PCI, with clinical as well as treatment characteristics affecting decision-making. Trial registration: ClinicalTrials.gov Identifier: NCT03362788 (First Posted: December 5, 2017) © 2020, Springer Science+Business Media, LLC, part of Springer Nature