Impact of the factor V Leiden mutation on the outcome of pneumococcal pneumonia: a controlled laboratory study

Introduction: Streptococcus (S.) pneumoniae is the most common cause of community-acquired pneumonia. The factor V Leiden (FVL) mutation results in resistance of activated FV to inactivation by activated protein C and thereby in a prothrombotic phenotype. Human heterozygous FVL carriers have been reported to be relatively protected against sepsis-related mortality. We here determined the effect of the FVL mutation on coagulation, inflammation, bacterial outgrowth and outcome in murine pneumococcal pneumonia. Methods: Wild-type mice and mice heterozygous or homozygous for the FVL mutation were infected intranasally with 2*10(6) colony forming units of viable S. pneumoniae. Mice were euthanized after 24 or 48 hours or observed in a survival study. In separate experiments mice were treated with ceftriaxone intraperitoneally 24 hours after infection and euthanized after 48 hours or observed in a survival study. Results: The FVL mutation had no consistent effect on activation of coagulation in either the presence or absence of ceftriaxone therapy, as reflected by comparable lung and plasma levels of thrombin-antithrombin complexes and fibrin degradation products. Moreover, the FVL mutation had no effect on lung histopathology, neutrophil influx, cytokine and chemokine levels or bacterial outgrowth. Remarkably, homozygous FVL mice were strongly protected against death due to pneumococcal pneumonia when treated with ceftriaxone, which was associated with more pronounced FXIII depletion; this protective effect was not observed in the absence of antibiotic therapy. Conclusions: Homozygosity for the FVL mutation protects against lethality due to pneumococcal pneumonia in mice treated with antibiotic

Identification and Characterization of Ixodes scapularis Antigens That Elicit Tick Immunity Using Yeast Surface Display

Repeated exposure of rabbits and other animals to ticks results in acquired resistance or immunity to subsequent tick bites and is partially elicited by antibodies directed against tick antigens. In this study we demonstrate the utility of a yeast surface display approach to identify tick salivary antigens that react with tick-immune serum. We constructed an Ixodes scapularis nymphal salivary gland yeast surface display library and screened the library with nymph-immune rabbit sera and identified five salivary antigens. Four of these proteins, designated P8, P19, P23 and P32, had a predicted signal sequence. We generated recombinant (r) P8, P19 and P23 in a Drosophila expression system for functional and immunization studies. rP8 showed anti-complement activity and rP23 demonstrated anti-coagulant activity. Ixodes scapularis feeding was significantly impaired when nymphs were fed on rabbits immunized with a cocktail of rP8, rP19 and rP23, a hall mark of tick-immunity. These studies also suggest that these antigens may serve as potential vaccine candidates to thwart tick feeding

Collaborative care for depression and anxiety problems

This review is published as a Cochrane Review in the Cochrane Database of Systematic Reviews 2012, Issue 10. Cochrane Reviews are regularly updated as new evidence emerges and in response to comments and criticisms, and the Cochrane Database of Systematic Reviews should be consulted for the most recent version of the Review.Common mental health problems, such as depression and anxiety, are estimated to affect up to 15% of the UK population at any one time, and health care systems worldwide need to implement interventions to reduce the impact and burden of these conditions. Collaborative care is a complex intervention based on chronic disease management models that may be effective in the management of these common mental health problems

Keeping blood clots at bay in sepsis

Clearance of platelets by the liver can help counteract the dangerous blood coagulation that can occur during sepsis. The mechanism involves clearance of platelets through the liver's Ashwell receptor, which binds to platelet glycoproteins altered by sepsis-causing bacteria (pages 648-655

TLR4 inhibition impairs bacterial clearance in a therapeutic setting in murine abdominal sepsis

To investigate the therapeutic effect of E5564 (a clinically used TLR4 inhibitor) in murine abdominal sepsis elicited by intraperitoneal infection with a highly virulent Escherichia coli in the context of concurrent antibiotic therapy. Mice were infected with different doses (~2 × 10(4)-2 × 10(6) CFU) of E. coli O18:K1 and treated after 8 h with ceftriaxone 20 mg/kg i.p. combined with either E5564 10 mg/kg i.v. or vehicle. For survival studies this treatment was repeated every 12 h. Bacterial loads and inflammatory parameters were determined after 20 h in peritoneal lavage fluid, blood, liver and lung tissue. Plasma creatinin, AST, ALT and LDH were determined to assess organ injury. E5564 impaired bacterial clearance under the antibiotic regime after infection with a low dose E. coli (1.7 × 10(4) CFU) while renal function was slightly preserved. No differences were observed in bacterial load and organ damage after infection with a tenfold higher (1.7 × 10(5) E. coli) bacterial dose. While treatment with E5564 slightly attenuated inflammatory markers provoked by the sublethal doses of 104-105 E. coli under the antibiotic regime, it did not affect lethality evoked by infection with 1.7 × 106 E. coli. The impact of TLR4 inhibition during abdominal sepsis by virulent E. coli bacteria is only beneficial at low infection grade at cost of bactericidal activit

The receptor for advanced glycation end products promotes bacterial growth at distant body sites in Staphylococcus aureus skin infection

The receptor for advanced glycation endproducts (RAGE) has been implicated in the regulation of skin inflammation. We here sought to study the role of RAGE in host defense during skin infection caused by Staphylococcus (S.) aureus, the most common pathogen in this condition. Wild-type (Wt) and RAGE deficient (rage(-/-)) mice were infected subcutaneously with S. aureus and bacterial loads and local inflammation were quantified at regular intervals up to 8 days after infection. While bacterial burdens were similar in both mouse strains at the primary site of infection, rage(-/-) mice had lower bacterial counts in lungs and liver. Skin cytokine and chemokine levels did not differ between groups. In accordance with the skin model, direct intravenous infection with S. aureus was associated with lower bacterial loads in lungs and liver of rage(-/-) mice. Together these data suggest that RAGE does not impact local host defense during S. aureus skin infection, but facilitates bacterial growth at distant body site

Dialyzable leukocyte extract differentially regulates the production of TNFalpha, IL-6, and IL-8 in bacterial component-activated leukocytes and endothelial cells

OBJECTIVE: To investigate i) whether the Dialyzable Leukocyte Extract (DLE) modulates the production of proinflammatory cytokines in leukocytes activated by the bacterial cell wall components lipopolysaccharide (LPS), lipoteichoic acid (LTA), and peptidoglycan (PGN); ii) the effect of DLE on LPS-stimulated endothelial cells; and iii) whether the regulatory effect of DLE on inflammatory mediators is related to the modulation of Toll-like receptors (TLRs), NF-kappaB and cAMP signaling pathways. METHODS: Leukocytes were stimulated with LPS, LTA, and PGN in the presence of DLE. Endothelial cells were stimulated with LPS and treated with DLE. The levels of Tumor Necrosis Factor-alpha(TNFalpha), Interleukin-6 (IL-6), and IL-8 in culture supernatants were evaluated by ELISA. The expression of Toll-like receptor 2 (TLR2) and 4 (TLR4), NF-kappaB activity and cAMP levels were evaluated by flow cytometry, EMSA, and EIA, respectively. RESULTS: The addition of DLE to leukocytes stimulated with cell wall constituents suppressed the production of TNFalpha. However, DLE induced IL-8 release in monocytes and enhanced IL-6 and IL-8 production by activated monocytes and endothelial cells. Also, DLE induced TLR2 and TLR4 expression, and increased cAMP levels, whereas NF-kappaB activity was inhibited. CONCLUSIONS: The present data indicate the differential regulation by DLE of the production of TNFalpha, IL-6, and IL-8 cytokines, associated with effects on TLR2 and TLR4 expression and NF-kappaB and cAMP activities. We suggest a putative mechanism for the biological effects of DLE in activated leukocytes and endothelial cell

Toll-like receptor 4 deficiency and acute pancreatitis act similarly in reducing host defense during murine Escherichia coli peritonitis

Objective. Acute pancreatitis is frequently complicated by Gram-negative sepsis. Mammalian cells recognize lipopolysaccharide from Gram-negative bacteria via Toll-like receptor (TLR) 4. The objective of this study was to determine the role of TLR4 in the defense against Gram-negative sepsis in previously healthy mice and in animals with preexisting pancreatitis. Design: A controlled, in vivo laboratory study. Setting: Research laboratory of a health sciences university. Subjects: Female C3H/HeJ (nonfunctional TLR4 mutant) and C3H/HeN (wild-type) mice. Interventions. Abdominal sepsis was induced by the intraperitoneal injection of Escherichia coli. Pancreatitis was induced by 12 hourly intraperitoneal injections of cerulein. Measurements and Main Results: The following experiments were performed. First, healthy TLR4 mutant mice demonstrated an enhanced bacterial load and dissemination of the infection relative to wild-type mice after intraperitoneal injection with E coli, associated with a reduced early release of proinflammatory cytokines and an attenuated influx of neutrophils into the peritoneal fluid. Second, wild-type mice in which acute pancreatitis was induced by repeated cerulein injections showed an increased bacterial load and dissemination of E coli relative to wild-type mice without pancreatitis, which was accompanied by a blunted proinflammatory cytokine response by peritoneal macrophages ex vivo and a diminished early cytokine and neutrophil response in vivo. Third, whereas the severity of cerulein-induced pancreatitis was similar in TLR4 mutant and wild-type mice, the important contribution of TLR4 to an effective host defense against E coli sepsis observed in previously healthy mice was no longer present in mice with preexisting pancreatitis. Conclusions. These data suggest that TLR4 deficiency and acute pancreatitis act similarly in reducing host defense against E coli peritonitis and that the role of TLR4 in severe Gram-negative infection depends, at least in part, on the presence of preexisting critical illnes

DNAX-Activating Protein of 12 kDa Impairs Host Defense in Pneumococcal Pneumonia

Objectives: Streptococcus pneumoniae is the most common causative organism in community-acquired pneumonia responsible for millions of deaths every year. DNAX-activating protein of 12 kDa is an adaptor molecule for different myeloid expressed receptors involved in innate immunity. Design: Animal study. Setting: University research laboratory. Subjects: DNAX-activating protein of 12 kDa-deficient (dap12(-/-)) and wild-type mice. Interventions: Mice were intranasally infected with S. pneumoniae. In addition, ex vivo responsiveness of alveolar macrophages was examined. Measurements and Main Results: dap12(-/-) alveolar macrophages released more tumor necrosis factor-a upon stimulation with S. pneumoniae and displayed increased phagocytosis of this pathogen compared with wild-type cells. After infection with S. pneumoniae via the airways, dap12(-/-) mice demonstrated reduced bacterial outgrowth in the lungs together with delayed dissemination to distant body sites relative to wild-type mice. This favorable response in dap12(-/-) mice was accompanied by reduced lung inflammation and an improved survival. Conclusions: These data suggest that DNAX-activating protein of 12 kDa impairs host defense during pneumococcal pneumonia at the primary site of infection at least in part by inhibiting phagocytosis by alveolar macrophage