Protective role of Cav-1 in pneumolysin-induced endothelial barrier dysfunction.

Pneumolysin (PLY) is a bacterial pore forming toxin and primary virulence factor of Streptococcus pneumonia, a major cause of pneumonia. PLY binds cholesterol-rich domains of the endothelial cell (EC) plasma membrane resulting in pore assembly and increased intracellular (IC) Ca2+ levels that compromise endothelial barrier integrity. Caveolae are specialized plasmalemma microdomains of ECs enriched in cholesterol. We hypothesized that the abundance of cholesterol-rich domains in EC plasma membranes confers cellular susceptibility to PLY. Contrary to this hypothesis, we found increased PLY-induced IC Ca2+ following membrane cholesterol depletion. Caveolin-1 (Cav-1) is an essential structural protein of caveolae and its regulation by cholesterol levels suggested a possible role in EC barrier function. Indeed, Cav-1 and its scaffolding domain peptide protected the endothelial barrier from PLY-induced disruption. In loss of function experiments, Cav-1 was knocked-out using CRISPR-Cas9 or silenced in human lung microvascular ECs. Loss of Cav-1 significantly enhanced the ability of PLY to disrupt endothelial barrier integrity. Rescue experiments with re-expression of Cav-1 or its scaffolding domain peptide protected the EC barrier against PLY-induced barrier disruption. Dynamin-2 (DNM2) is known to regulate caveolar membrane endocytosis. Inhibition of endocytosis, with dynamin inhibitors or siDNM2 amplified PLY induced EC barrier dysfunction. These results suggest that Cav-1 protects the endothelial barrier against PLY by promoting endocytosis of damaged membrane, thus reducing calcium entry and PLY-dependent signaling.

Atorvastatin protects against liver and vascular damage in a model of diet induced steatohepatitis by resetting FXR and GPBAR1 signaling.

Farnesoid-x-receptor (FXR) agonists, currently trialed in patients with non-alcoholic steatosis (NAFLD), worsen the pro-atherogenic lipid profile and might require a comedication with statin. Here we report that mice feed a high fat/high cholesterol diet (HFD) are protected from developing a pro-atherogenic lipid profile because their ability to dispose cholesterol through bile acids. This protective mechanism is mediated by suppression of FXR signaling in the liver by muricholic acids (MCAs) generated in mice from chenodeoxycholic acid (CDCA). In contrast to CDCA, MCAs are FXR antagonists and promote a CYP7A1-dependent increase of bile acids synthesis. In mice feed a HFD, the treatment with obeticholic acid, a clinical stage FXR agonist, failed to improve the liver histopathology while reduced Cyp7a1 and Cyp8b1 genes expression and bile acids synthesis and excretion. In contrast, treating mice with atorvastatin mitigated liver and vascular injury caused by the HFD while increased the bile acids synthesis and excretion. Atorvastatin increased the percentage of 7α-dehydroxylase expressing bacteria in the intestine promoting the formation of deoxycholic acid and litocholic acid, two GPBAR1 agonists, along with the expression of GPBAR1-regulated genes in the white adipose tissue and colon. In conclusion, present results highlight the central role of bile acids in regulating lipid and cholesterol metabolism in response to atorvastatin and provide explanations for limited efficacy of FXR agonists in the treatment of NAFLD.

Intestinal pathophysiological and microbial changes in sickle cell disease: Potential targets for therapeutic intervention.

There is a large therapeutic gap in the treatment of sickle cell disease (SCD). Recent studies demonstrated the presence of pathophysiological and microbial changes in the intestine of patients with SCD. The intestinal microbes have also been found to regulate neutrophil ageing and possible basal activation of circulating neutrophils. Both aged and activated neutrophils are pivotal for the pathogenesis of vaso-occlusive crisis in SCD. In this paper, we will provide an overview of the intestinal pathophysiological and microbial changes in SCD. Based on these changes, we will propose therapeutic approaches that could be investigated for treating SCD.

Proteomic atlas of organ vasculopathies triggered by Staphylococcus aureus sepsis.

Sepsis is a life-threatening condition triggered by a dysregulated host response to microbial infection resulting in vascular dysfunction, organ failure and death. Here we provide a semi-quantitative atlas of the murine vascular cell-surface proteome at the organ level, and how it changes during sepsis. Using in vivo chemical labeling and high-resolution mass spectrometry, we demonstrate the presence of a vascular proteome that is perfusable and shared across multiple organs. This proteome is enriched in membrane-anchored proteins, including multiple regulators of endothelial barrier functions and innate immunity. Further, we automated our workflows and applied them to a murine model of methicillin-resistant Staphylococcus aureus (MRSA) sepsis to unravel changes during systemic inflammatory responses. We provide an organ-specific atlas of both systemic and local changes of the vascular proteome triggered by sepsis. Collectively, the data indicates that MRSA-sepsis triggers extensive proteome remodeling of the vascular cell surfaces, in a tissue-specific manner.

Pivotal Pathogenic and Biomarker Role of Chlamydia Pneumoniae in Neurovascular Diseases.

Chlamydia Pneumoniae (C. Pn) is an obligatory intracellular bacterium that is associated with respiratory tract infections like pneumonia, pharyngitis and bronchitis. It has also been implicated in cerebrovascular (stroke) as well as cardiovascular diseases. The most possible pathway via which C. Pn elicits its pathogenesis could be via activation of Human Vascular Smooth Muscle Cells (VSMCs) proliferation resulting in the stimulation of Toll-Like Receptor-4 (TLR-4) and/or phospho-44/42(p44/p42) Mitogen-Activated Protein Kinases (MAPK). It is also established that tyrosine phosphorylation of IQ domain GTPase-activating protein 1 (IQGAP1) also contributed to C. Pn infection-triggered Vascular Endothelial Cell (VEC) movements via the SRC tyrosine kinase inhibitor PP2 (4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine) resulting in angiogenesis. It is also proven that restricted inflammatory cell infiltrates as well as apoptosis have been linked to C. Pn or C. Pn-specific proteins in atherosclerotic plaques of patients with stroke. It is further an evidence that C. Pn enters the cerebral vasculature during the initial infection and worsen atherosclerosis either directly or indirectly. Chronic, persistent C. Pn infection is also capable of triggering the secretion of Chlamydial Heat Shock Protein 60 (cHSP60) in the vessel wall resulting in augmentation of inflammation. C. Pn also aids in the activation of explicit cell-intermediated immunity within plaques. Macrophages in the carotid plaques co-exist with CD4+ lymphocytes which are capable of triggering the release of pro-inflammatory cytokines resulting in the augmentation of atherogenic development during C. Pn infection. C. Pn actively participated in the modification of both histones H3 and H4 during chromatin analysis via the interleukin 8(IL-8) gene facilitator as well as conscription of nuclear factor kappa-B(NF-κB) or NF- κB/p65 complex and polymerase II (Pol II). This review, therefore, focuses on the crucial involvement of C. Pn in the pathogenesis of cerebrovascular events.

Fluorescence In Situ Hybridization (FISH) and Peptide Nucleic Acid Probe-Based FISH for Diagnosis of Q Fever Endocarditis and Vascular Infections.

Endocarditis and vascular infections are common manifestations of persistent localized infection due to Coxiella burnetii, and recently, fluorescence in situ hybridization (FISH) was proposed as an alternative tool for their diagnosis. In this study, we evaluated the efficiency of FISH in a series of valve and vascular samples infected by C. burnetii We tested 23 C. burnetii-positive valves and thrombus samples obtained from patients with Q fever endocarditis. Seven aneurysms and thrombus specimens were retrieved from patients with Q fever vascular infections. Samples were analyzed by culture, immunochemistry, and FISH with oligonucleotide and PNA probes targeting C. burnetii-specific 16S rRNA sequences. The immunohistochemical analysis was positive for five (17%) samples with significantly more copies of C. burnetii DNA than the negative ones (P = 0.02). FISH was positive for 13 (43%) samples and presented 43% and 40% sensitivity compared to that for quantitative PCR (qPCR) and culture, respectively. PNA FISH detected C. burnetii in 18 (60%) samples and presented 60% and 55% sensitivity compared to that for qPCR and culture, respectively. Immunohistochemistry had 38% and 28% sensitivity compared to that for FISH and PNA FISH, respectively. Samples found positive by both immunohistochemistry and PNA FISH contained significantly more copies of C. burnetii DNA than the negative ones (P = 0.03). Finally, PNA FISH was more sensitive than FISH (60% versus 43%, respectively) for the detection of C. burnetii We provide evidence that PNA FISH and FISH are important assays for the diagnosis of C. burnetii endocarditis and vascular infections.

Severe Hemoptysis Associated with Bacterial Pulmonary Infection: Clinical Features, Significance of Parenchymal Necrosis, and Outcome.

PURPOSE: Severe hemoptysis (SH) associated with non-tuberculosis bacterial lower respiratory tract infection (LRTI) is poorly described, and the efficacy of the usual decision-making process is unknown. This study aimed at describing the clinical, radiological patterns, mechanism, and microbiological spectrum of SH related to bacterial LRTI, and assessing whether the severity of hemoptysis and the results of usual therapeutic strategy are influenced by the presence of parenchymal necrosis. METHODS: A single-center analysis of patients with SH related to bacterial LRTI from a prospective registry of consecutive patients with SH admitted to the intensive care unit of a tertiary referral center between November 1996 and May 2013. RESULTS: Of 1504 patients with SH during the study period, 65 (4.3%) had SH related to bacterial LRTI, including non-necrotizing infections (n = 31), necrotizing pneumonia (n = 23), pulmonary abscess (n = 10), and excavated nodule (n = 1). The presence of parenchymal necrosis (n = 34, 52%) was associated with a more abundant bleeding (volume: 200 ml [70-300] vs. 80 ml [30-170]; p = 0.01) and a more frequent need for endovascular procedure (26/34; 76% vs. 9/31; 29%; p < 0.001). Additionally, in case of parenchymal necrosis, the pulmonary artery vasculature was involved in 16 patients (47%), and the failure rate of endovascular treatment was up to 25% despite multiple procedures. CONCLUSIONS: Bacterial LRTI is a rare cause of SH. The presence of parenchymal necrosis is more likely associated with bleeding severity, pulmonary vasculature involvement, and endovascular treatment failure.

Epidemiology of Methicillin-Resistant Staphylococcus aureus Bacteremia in Children.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia is associated with high rates of treatment failure in adults. The epidemiology, clinical outcomes, and risk factors for treatment failure associated with MRSA bacteremia in children are poorly understood. METHODS: Multicenter, retrospective cohort study of children ≤18 years hospitalized with MRSA bacteremia across 3 tertiary care children's hospitals from 2007 to 2014. Treatment failure was defined as persistent bacteremia >3 days, recurrence of bacteremia within 30 days, or attributable 30-day mortality. Potential risk factors for treatment failure, including the site of infection, vancomycin trough concentration, critical illness, and need for source control, were collected via manual chart review and evaluated using multivariable logistic regression. RESULTS: Of 232 episodes of MRSA bacteremia, 72 (31%) experienced treatment failure and 23% developed complications, whereas 5 (2%) died within 30 days. Multivariable analysis of 174 children treated with vancomycin with steady-state vancomycin concentrations obtained found that catheter-related infections (odds ratio [OR], 0.36; 95% confidence interval [CI]: 0.13-0.94) and endovascular infections (OR, 4.35; 95% CI: 1.07-17.7) were associated with lower and higher odds of treatment failure, respectively, whereas a first vancomycin serum trough concentration <10 µg/mL was not associated with treatment failure (OR, 1.34; 95% CI, 0.49-3.66). Each additional day of bacteremia was associated with a 50% (95% CI: 26%-79%) increased odds of bacteremia-related complications. CONCLUSIONS: Hospitalized children with MRSA bacteremia frequently suffered treatment failure and complications, but mortality was low. The odds of bacteremia-related complications increased with each additional day of bacteremia, emphasizing the importance of achieving rapid sterilization.

Usefulness of scintigraphy with labelled leucocytes and SPECT/CT in vascular graft infection. / Utilidad de la gammagrafía con leucocitos marcados y SPECT/TC en la infección de injertos vasculares.

Vascular graft infections are a rare complication in this type of procedure. However, when they do occur, they usually have high morbidity, and even a high mortality. Proper identification and location is crucial for the appropriate and early management, whether medical or surgical, thus knowledge of the right tools is paramount. Nuclear medicine studies play an important role in this regard, either by using labelled white blood cells scintigraphy or 18F-FDG. The choice, among other factors, will depend on the experience with both techniques by the different groups, their knowledge of them, as well as their availability. Two cases are presented in which 99mTc-HMPAO-white blood cells SPECT/CT scintigraphy was very useful in the diagnosis and location of the suspected infectious compromise, which led to the subsequent appropriate and guided management. Both cases were confirmed clinically and microbiologically.

The effects of ozone on bacterial growth and thiol-disulphide homeostasis in vascular graft infection caused by MRSA in rats.

PURPOSE:: To investigate the microbiological, inflammatory and oxidant effects of adjuvant ozone administration in experimental rat vascular graft infection model which has not been previously investigated. METHODS:: Forty adult Wistar rats were divided into Sham, Control, Vancomycin, Ozone, Vancomycin+Ozone groups. Grafts were inoculated with Methicillin-resistant Staphylococcus aureus (MRSA) strain and implanted subcutaneously. Rats were treated intraperitoneally with ozone and /or intramuscularly with vancomycin for 10 days. Grafts were evaluated by quantitative bacterial cultures. Blood samples were harvested for determination of thiol-disulphide and cytokine profiles. RESULTS:: There was no significant difference in bacterial counts between Control and Ozone Groups. In the Ozone Group median colony count was significantly higher than the Vancomycin and Vancomycin+Ozone Groups. Total thiol and disulphide levels increased and disulphide/native thiol and disulphide/total thiol ratios decreased in Ozone Group significantly. Albumin levels decreased significantly in Vancomycin and Vancomycin+Ozone Groups compared to the Sham Group. IL-1 and TNF-alpha levels significantly increased in infected rats. Decreased levels of VEGF due to infection reversed by ozone therapy in control and vancomycin groups. CONCLUSIONS:: We didn't observe any benefit of the agent on MRSA elimination in our model. Likewise, effects of ozone on thiol-disulphide homeostasis and inflammatory cytokines were contradictory.

The effects of ozone on bacterial growth and thiol-disulphide homeostasis in vascular graft infection caused by MRSA in rats

Abstract: Purpose: To investigate the microbiological, inflammatory and oxidant effects of adjuvant ozone administration in experimental rat vascular graft infection model which has not been previously investigated. Methods: Forty adult Wistar rats were divided into Sham, Control, Vancomycin, Ozone, Vancomycin+Ozone groups. Grafts were inoculated with Methicillin-resistant Staphylococcus aureus (MRSA) strain and implanted subcutaneously. Rats were treated intraperitoneally with ozone and /or intramuscularly with vancomycin for 10 days. Grafts were evaluated by quantitative bacterial cultures. Blood samples were harvested for determination of thiol-disulphide and cytokine profiles. Results: There was no significant difference in bacterial counts between Control and Ozone Groups. In the Ozone Group median colony count was significantly higher than the Vancomycin and Vancomycin+Ozone Groups. Total thiol and disulphide levels increased and disulphide/native thiol and disulphide/total thiol ratios decreased in Ozone Group significantly. Albumin levels decreased significantly in Vancomycin and Vancomycin+Ozone Groups compared to the Sham Group. IL-1 and TNF-alpha levels significantly increased in infected rats. Decreased levels of VEGF due to infection reversed by ozone therapy in control and vancomycin groups. Conclusions: We didn't observe any benefit of the agent on MRSA elimination in our model. Likewise, effects of ozone on thiol-disulphide homeostasis and inflammatory cytokines were contradictory.

Gut Microbiota in Vascular Disease: Therapeutic Target?

BACKGROUND: Gut microbiota is increasingly recognized as a powerful regulator of host physiology. Most of its effects are mediated through metabolites acting as energy sources, signaling receptor ligands and substrates for host enzymes. Owing to the meta-stability and high amenability of the gut microbiota to modification by diet and environment predicting specific gut microbes or its metabolites responsible for different host metabolic states is often confounded. METHODS: The Pubmed was searched for research articles on gut microbiota and cardiovascular disease. RESULTS: The searched articles reported a direct role of gut microbes in cardiovascular disorders (CVD). The interaction among gut microbial metabolism (through breakdown of certain dietary nutrients like choline), host immune system and lipid metabolism generate conditions that promote atherosclerosis development. Importantly, components of this interactive system can be explored to identify points of intervention in the path of disease development. Based on this strategies targeting gut microbial composition and activity are being explored as therapies against CVD. Use of archaebiotics and 3,3-dimethyl- 1-butanol aiming to reduce TMA (trimethylamine) conversion to TMAO (trimethylamine-N-oxide) and high fibre diets to reduce TMA precursors while simultaneously selecting for beneficial gut bacteria are attractive anti-atherogenic approaches. CONCLUSION: Success of these approaches in humans however, requires extensive research.

Sickle cell vaso-occlusive crisis: it's a gut feeling.

Insights in the pathogenesis of vaso-occlusive crisis in patients with sickle cell disease have changed significantly in the last decade. Various laboratory and clinical evidence have provided support to the pivotal role of activated neutrophils in this process. A recent study in murine sickle cell disease indicated that the intestinal microbiota is responsible for regulating the number of aged neutrophils, a subset of neutrophils that are overly activated. Reduction of these neutrophils in vivo protected the mice from fatal TNFα-induced vaso-occlusive crisis. In this paper, we discuss the reasons why patients with sickle cell disease may have an abnormal intestinal microbiota and how this could contribute to the development of vaso-occlusive crisis. We also highlight the recent interest in studying the intestinal microbiota of patients with sickle cell disease and suggest that the next therapeutic approach for these patients may well be in the manipulation of the intestinal microbiota to restore the individual's microbial landscape.

18F-FDG PET/CT as a central tool in the shift from chronic Q fever to Coxiella burnetii persistent focalized infection: A consecutive case series.

Because Q fever is mostly diagnosed serologically, localizing a persistent focus of Coxiella burnetii infection can be challenging. F-fluorodeoxyglucose positron emission tomography/computed tomography (F-FDG PET/CT) could be an interesting tool in this context.We performed a retrospective study on patients diagnosed with C burnetii infection, who had undergone F-FDG PET/CT between 2009 and 2015. When positive F-FDG PET/CT results were obtained, we tried to determine if it changed the previous diagnosis by discovering or confirming a suspected focus of C burnetii infection.One hundred sixty-seven patients benefited from F-FDG PET/CT. The most frequent clinical subgroup before F-FDG PET/CT was patients with no identified focus of infection, despite high IgG1 serological titers (34%). For 59% (n = 99) of patients, a hypermetabolic focus was identified. For 62 patients (62.6%), the positive F-FDG PET/CT allowed the diagnosis to be changed. For 24 of them, (38.7%), a previously unsuspected focus of infection was discovered. Forty-two (42%) positive patients had more than 1 hypermetabolic focus. We observed 21 valvular foci, 34 vascular foci, and a high proportion of osteoarticular localizations (n = 21). We also observed lymphadenitis (n = 27), bone marrow hypermetabolism (n = 11), and 9 pulmonary localizations.We confirmed thatF-FDG PET/CT is a central tool in the diagnosis of C burnetii focalized persistent infection. We proposed new diagnostic scores for 2 main clinical entities identified using F-FDG PET/CT: osteoarticular persistent infections and lymphadenitis.

Value of 18F-FDG PET/CT in diagnosing chronic Q fever in patients with central vascular disease.

BACKGROUND: The aim of this study is to describe the value of 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) in diagnosing chronic Q fever in patients with central vascular disease and the added value of 18F-FDG PET/CT in the diagnostic combination strategy as described in the Dutch consensus guideline for diagnosing chronic Q fever. METHODS: 18F-FDG PET/CT was performed in patients with an abdominal aortic aneurysm or aorto-iliac reconstruction and chronic Q fever, diagnosed by serology and positive PCR for Coxiella burnetii DNA in blood and/or tissue (PCR-positive study group). Patients with an abdominal aortic aneurysm or aorto-iliac reconstruction without clinical and serological findings indicating Q fever infection served as a control group. Patients with a serological profile of chronic Q fever and a negative PCR in blood were included in additional analyses (PCR-negative study group). RESULTS: Thirteen patients were evaluated in the PCR-positive study group and 22 patients in the control group. 18F-FDG PET/CT indicated vascular infection in 6/13 patients in the PCR-positive study group and 2/22 patients in the control group. 18F-FDG PET/CT demonstrated a sensitivity of 46% (95% CI: 23-71%), specificity of 91% (95% CI: 71-99%), positive predictive value of 75% (95% CI:41-93%) and negative predictive value of 74% (95% CI: 55-87%). In the PCR-negative study group, 18F-FDG PET/CT was positive in 10/20 patients (50%). CONCLUSION: The combination of 18F-FDG PET/CT, as an imaging tool for identifying a focus of infection, and Q fever serology is a valid diagnostic strategy for diagnosing chronic Q fever in patients with central vascular disease.

Invasive pulmonary aspergillosis presenting as thoracic mass causing obstruction of the superior and inferior vena cava in an immunocompetent patient: a diagnostic dilemma.

Invasive pulmonary aspergillosis (IPA) is a disease of immunocompromised patients, but its prevalence is increasing in immunocompetent persons. Patients usually present with non-specific symptoms, sometimes consistent with bronchopneumonia. We discuss the case of a 19-year-old boy who presented with constitutional respiratory symptoms along with signs of obstruction of the superior and inferior vena cava. A chest radiograph was suggestive of a thoracic mass raising suspicion of bronchogenic carcinoma/ benign mass, sarcoidosis and tuberculosis, but a diagnosis of invasive aspergillosis was established. The patient showed excellent clinico-radiological improvement with administration of voriconazole. Invasive pulmonary aspergillosis may also present with atypical findings and should be considered in differentials when investigating a case even if the patient does not have a risk factor.