The novel iron chelator, DIBI, attenuates inflammation and improves outcome in colon ascendens stent peritonitis-induced experimental sepsis

BACKGROUND: Sepsis is the result of a dysregulated host immune response to an infection. An ideal therapy would target both the underlying infection and the dysregulated immune response. DIBI, a novel iron-binding polymer, was specifically developed as an antimicrobial agent and has also demonstrated in vivo anti-inflammatory properties. OBJECTIVE: This study aimed to further investigate the effects of DIBI with and without the antibiotic imipenem (IMI) in colon ascendens stent peritonitis (CASP)-induced experimental sepsis. METHODS: Vehicle, DIBI and/or IMI were administered in C57BL/6 mice after CASP surgery. Intestinal leukocyte activation and capillary perfusion was evaluated by intravital microscopy. Moreover, bacterial load in peritoneal lavage fluid and blood, and plasma cytokine levels were assessed. In a second series of experiments, surgery to repair the colon was performed at 5 hr and these mice were followed for long-term survival over 7 days. RESULTS: DIBI reduced leukocyte adhesion, improved capillary blood flow, and decreased key plasma cytokines levels. DIBI also improved survival of infected mice and greatly improved IMI efficacy. Survivors treated with IMI and DIBI were found to be free of systemic infection. CONCLUSIONS: DIBI has promising potential for sepsis treatment including its use as a sole or an adjunct therapeutic with antibiotics.

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Dexmedetomidine Attenuates the Microcirculatory Derangements Evoked by Experimental Sepsis

Anesthesiology ◽

10.1097/aln.0000000000000491 ◽

2015 ◽

Vol 122 (3) ◽

pp. 619-630 ◽

Cited By ~ 31

Author(s):

Marcos L. Miranda ◽

Michelle M. Balarini ◽

Eliete Bouskela

Keyword(s):

Blood Gases ◽

Capillary Density ◽

Sepsis Syndrome ◽

In Vivo Studies ◽

Experimental Sepsis ◽

Leukocyte Rolling ◽

Capillary Perfusion ◽

Arterial Blood ◽

Baseline Values

Abstract Background: Dexmedetomidine, an α-2 adrenergic receptor agonist, has already been used in septic patients although few studies have examined its effects on microcirculatory dysfunction, which may play an important role in perpetuating sepsis syndrome. Therefore, the authors have designed a controlled experimental study to characterize the microcirculatory effects of dexmedetomidine in an endotoxemia rodent model that allows in vivo studies of microcirculation. Methods: After skinfold chamber implantation, 49 golden Syrian hamsters were randomly allocated in five groups: (1) control animals; (2) nonendotoxemic animals treated with saline; (3) nonendotoxemic animals treated with dexmedetomidine (5.0 μg kg−1 h−1); (4) endotoxemic (lipopolysaccharide 1.0 mg/kg) animals treated with saline; and (5) endotoxemic animals treated with dexmedetomidine. Intravital microscopy of skinfold chamber preparations allowed quantitative analysis of microvascular variables and venular leukocyte rolling and adhesion. Mean arterial blood pressure, heart rate, arterial blood gases, and lactate concentrations were also documented. Results: Lipopolysaccharide administration increased leukocyte rolling and adhesion and decreased capillary perfusion. Dexmedetomidine significantly attenuated these responses: compared with endotoxemic animals treated with saline, those treated with dexmedetomidine had less leukocyte rolling (11.8 ± 7.2% vs. 24.3 ± 15.0%; P < 0.05) and adhesion (237 ± 185 vs. 510 ± 363; P < 0.05) and greater functional capillary density (57.4 ± 11.2% of baseline values vs. 45.9 ± 11.2%; P < 0.05) and erythrocyte velocity (68.7 ± 17.6% of baseline values vs. 54.4 ± 14.8%; P < 0.05) at the end of the experiment. Conclusions: Dexmedetomidine decreased lipopolysaccharide-induced leukocyte–endothelial interactions in the hamster skinfold chamber microcirculation. This was accompanied by a significant attenuation of capillary perfusion deficits, suggesting that dexmedetomidine yields beneficial effects on endotoxemic animals’ microcirculation.

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Priming programed Mucosal-Associated Invariant T cells protect against systemic or local bacterial infection

10.21203/rs.3.rs-39302/v1 ◽

2020 ◽

Author(s):

Zhe Zhao ◽

Mai Shi ◽

Tianyuan Zhu ◽

Huimeng Wang ◽

Troi Pediongco ◽

...

Keyword(s):

Respiratory Infections ◽

Bacterial Load ◽

Critical Role ◽

Systemic Infection ◽

Live Vaccine Strain ◽

Protective Capacity ◽

Mait Cells ◽

Synthetic Ligand ◽

Stable Memory

Abstract Mucosal-Associated Invariant T (MAIT) cells have potent antibacterial functions. Their protective capacity, in vivo, has been demonstrated in mouse models, particularly of respiratory infections. We now show that during systemic infection of mice with Francisella tularensis Live Vaccine Strain (LVS), MAIT cell expansion was evident in the liver, lungs, kidney, spleen and blood. MAIT cells manifested a polarised Th1-like (termed “MAIT-1”) phenotype and cytokine profile that conferred a critical role in controlling bacterial load. After resolution of the primary infection, the expanded MAIT cells developed to a stable memory-like MAIT-1 cell population, suggesting a basis for vaccination and protection against subsequent challenge. Indeed, a systemic vaccination with synthetic ligand (5-OP-RU) in combination with CpG adjuvant boosted MAIT-1 cells and resulted in enhanced protection against systemic and local infections with F. tularensis and Legionella longbeachae. Our study highlights the potential utility of targeting MAIT cells to combat multiple bacterial pathogens.

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Argatroban administration reduces leukocyte adhesion and improves capillary perfusion within the intestinal microcirculation in experimental sepsis

Thrombosis and Haemostasis ◽

10.1160/th10-04-0241 ◽

2010 ◽

Vol 104 (11) ◽

pp. 1022-1028 ◽

Cited By ~ 8

Author(s):

Christian Fuchs ◽

Elena Ladwig ◽

Juan Zhou ◽

Dragan Pavlovic ◽

Kristina Behrend ◽

...

Keyword(s):

Leukocyte Adhesion ◽

Capillary Density ◽

Functional Capillary Density ◽

Experimental Sepsis ◽

Capillary Perfusion ◽

Vascular Contractility ◽

Intestinal Microcirculation ◽

Sham Surgery ◽

The Impact

SummaryCo-activation of pro-coagulatory pathways in sepsis may result in disseminated intravascular coagulation and contributes to microvascular dysfunction. We investigated the effects of the direct thrombin inhibitor, argatroban (ARG), on the sepsis-induced impairment of the intestinal microcirculation (capillary perfusion, leukocyte adhesion) and the vascular contractility in rats. Forty male Lewis rats were randomly assigned to one of four groups: sham surgery (SHAM), experimental sepsis (colon ascendens stent peritonitis – CASP), CASP+ARG, and SHAM+ARG. At 16 hours after colon stent insertion (or sham surgery), 2 mg/kg argatroban or buffer were given intravenously, and 1 hour thereafter, intravital microscopy was performed. In addition, experiments to study the impact of ARG on vascular contractility were conducted in vitro. ARG administration in CASP rats significantly increased functional capillary density in mucosal (+128%) and muscular layers (longitudinal: +42%; circular: +64%) and decreased the number of firmly adhering leukocytes in the intestinal submucosa compared to untreated animals. In vitro findings indicated a vasodilating effect of ARG. ARG administration during experimental sepsis improved intestinal microcirculation by preserving functional capillary density, an indicator of microvascular perfusion, and by reducing leukocyte adherence to the endothelium in submucosal venules.

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Thrombomodulin mutant mice with a strongly reduced capacity to generate activated protein C have an unaltered pulmonary immune response to respiratory pathogens and lipopolysaccharide

Blood ◽

10.1182/blood-2002-05-1380 ◽

2004 ◽

Vol 103 (5) ◽

pp. 1702-1709 ◽

Cited By ~ 65

Author(s):

Anita W. Rijneveld ◽

Sebastiaan Weijer ◽

Sandrine Florquin ◽

Charles T. Esmon ◽

Joost C. M. Meijers ◽

...

Keyword(s):

Immune Response ◽

Protein C ◽

Activated Protein C ◽

Protein S ◽

Lavage Fluid ◽

Respiratory Pathogens ◽

Pulmonary Response ◽

Inflammatory Infiltrates

AbstractThe thrombomodulin–protein C–protein S (TM-PC-PS) pathway exerts anticoagulant and anti-inflammatory effects. We investigated the role of TM in the pulmonary immune response in vivo by the use of mice with a mutation in the TM gene (TMpro/pro) that was earlier found to result in a minimal capacity for activated PC (APC) generation in the circulation. We here demonstrate that TMpro/pro mice also display a strongly reduced capacity to produce APC in the alveolar compartment upon intrapulmonary delivery of PC and thrombin. We monitored procoagulant and inflammatory changes in the lung during Gram-positive (Streptococcus pneumoniae) and Gram-negative (Klebsiella pneumoniae) pneumonia and after local administration of lipopolysaccharide (LPS). Bacterial pneumonia was associated with fibrin(ogen) depositions in the lung that colocalized with inflammatory infiltrates. LPS also induced a rise in thrombin-antithrombin complexes in bronchoalveolar lavage fluid. These pulmonary procoagulant responses were unaltered in TMpro/pro mice, except for enhanced fibrin(ogen) deposition during pneumococcal pneumonia. In addition, TMpro/pro mice displayed unchanged antibacterial defense, neutrophil recruitment, and cytokine/chemokine levels. These data suggest that the capacity of TM to generate APC does not play a role of importance in the pulmonary response to respiratory pathogens or LPS.

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Colonization and immune modulation properties of Klebsiella pneumoniae biofilm-dispersed cells

npj Biofilms and Microbiomes ◽

10.1038/s41522-019-0098-1 ◽

2019 ◽

Vol 5 (1) ◽

Cited By ~ 6

Author(s):

Cyril Guilhen ◽

Sylvie Miquel ◽

Nicolas Charbonnel ◽

Laura Joseph ◽

Guillaume Carrier ◽

...

Keyword(s):

Immune Response ◽

Klebsiella Pneumoniae ◽

Immune Modulation ◽

Bacterial Load ◽

Phenotypic Properties ◽

Planktonic Bacteria ◽

Initial Adhesion ◽

Sessile Cells ◽

Dispersed Cells

Abstract Biofilm-dispersal is a key determinant for further dissemination of biofilm-embedded bacteria. Recent evidence indicates that biofilm-dispersed bacteria have transcriptional features different from those of both biofilm and planktonic bacteria. In this study, the in vitro and in vivo phenotypic properties of Klebsiella pneumoniae cells spontaneously dispersed from biofilm were compared with those of planktonic and sessile cells. Biofilm-dispersed cells, whose growth rate was the same as that of exponential planktonic bacteria but significantly higher than those of sessile and stationary planktonic forms, colonized both abiotic and biotic surfaces more efficiently than their planktonic counterparts regardless of their initial adhesion capabilities. Microscopy studies suggested that dispersed bacteria initiate formation of microcolonies more rapidly than planktonic bacteria. In addition, dispersed cells have both a higher engulfment rate and better survival/multiplication inside macrophages than planktonic cells and sessile cells. In an in vivo murine pneumonia model, the bacterial load in mice lungs infected with biofilm-dispersed bacteria was similar at 6, 24 and 48 h after infection to that of mice lungs infected with planktonic or sessile bacteria. However, biofilm-dispersed and sessile bacteria trend to elicit innate immune response in lungs to a lesser extent than planktonic bacteria. Collectively, the findings from this study suggest that the greater ability of K. pneumoniae biofilm-dispersed cells to efficiently achieve surface colonization and to subvert the host immune response confers them substantial advantages in the first steps of the infection process over planktonic bacteria.

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Dectin-1 Is Required for Resistance to Coccidioidomycosis in Mice

mBio ◽

10.1128/mbio.00597-12 ◽

2013 ◽

Vol 4 (1) ◽

Cited By ~ 42

Author(s):

Suganya Viriyakosol ◽

Maria del Pilar Jimenez ◽

Michael A. Gurney ◽

Mark E. Ashbaugh ◽

Joshua Fierer

Keyword(s):

Immune Response ◽

Pathogenic Fungus ◽

Lavage Fluid ◽

Dependent Manner ◽

Coccidioides Immitis ◽

Necrosis Factor Alpha ◽

Cell Immunity ◽

Th17 Cytokines

ABSTRACTWe assessed the role of Dectin-1 in the immune response to the pathogenic fungusCoccidioides, bothin vitroandin vivo, using mice with a targeted mutation inClec7a. Elicited peritoneal macrophages responded to formalin-killed spherules (FKS) and alkali-treated FKS by secreting proinflammatory cytokines in a Dectin-1- and β-glucan-dependent manner. The responses of bone marrow-derived dendritic cells (BMDC) to the same stimulants were more complex; interleukin 1β (IL-1β) and tumor necrosis factor alpha (TNF-α) secretion was independent of Dectin-1, while IL-6, IL-10, and granulocyte-macrophage colony-stimulating factor (GM-CSF) were largely but not entirely dependent on Dectin-1. After intranasal infection, Dectin-1−/−mice had lower concentrations of IL-12p70, gamma interferon (IFN-γ), IL-1β, and the Th17 cytokines IL-22, IL-23, and 17A in the lung lavage fluid, which may explain why they were significantly more susceptible to pulmonary coccidioidomycosis two weeks after infection. The Dectin-1 mutation was even more deleterious in (B6 × DBA/2)F2mice, which are more resistant to coccidioidomycosis than B6 mice by virtue of protective genes from DBA/2, a genetically resistant strain. We also found that two susceptible strains of mice (B6 and BALB/c) expressed much less Dectin-1 in their lungs than did resistant DBA/2 mice. We conclude that Dectin-1 is necessary for resistance toCoccidioides immitis, that Dectin-1 promotes both Th1 and Th17 protective immune responses to this infection, and that there is a correlation between expression of Dectin-1 by the inflammatory infiltrate and resistance to coccidioidomycosis.IMPORTANCECoccidioidomycosis is a fungal infection endemic in the southwestern United States and neighboring Mexico, causing ~150,000 lung infections in people and resulting in ~17,000 hospitalizations annually in California alone. Very little is known about innate immunity to this fungus. This paper shows that Dectin-1, the primary β-glucan receptor on myeloid cells, is required for resistance to this pathogen. Dectin-1 is part of the innate immune system, and it is needed to direct the acquired immune response toward into a pathway that will lead to macrophage activation. Lungs from infected mice lacking Dectin-1 had lower concentrations of Th1 and Th17 cytokines, two cytokine pathways that are very important for acquired T cell immunity toCoccidioidesspp. This is the first demonstration that Dectin-1 is required for host resistance to a dimorphic, primary pathogenic fungus.

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Yersinia-induced Apoptosis In Vivo Aids in the Establishment of a Systemic Infection of Mice

Journal of Experimental Medicine ◽

10.1084/jem.188.11.2127 ◽

1998 ◽

Vol 188 (11) ◽

pp. 2127-2137 ◽

Cited By ~ 173

Author(s):

Denise M. Monack ◽

Joan Mecsas ◽

Donna Bouley ◽

Stanley Falkow

Keyword(s):

Mutant Strain ◽

Yersinia Pseudotuberculosis ◽

Bacterial Load ◽

Systemic Infection ◽

Wild Type ◽

Mesenteric Lymph Nodes ◽

Induced Apoptosis ◽

Factor Α

Pathogenic Yersinia cause a systemic infection in mice that is dependent on the presence of a large plasmid encoding a number of secreted virulence proteins called Yops. We previously demonstrated that a plasmid-encoded Yop, YopJ, was essential for inducing apoptosis in cultured macrophages. Here we report that YopJ is a virulence factor in mice and is important for the establishment of a systemic infection. The oral LD50 for a yopJ mutant Yersinia pseudotuberculosis increases 64-fold compared with wild-type. Although the yopJ mutant strain is able to reach the spleen of infected mice, the mutant strain seldom reaches the same high bacterial load that is seen with wild-type Yersinia strain and begins to be cleared from infected spleens on day 4 after infection. Furthermore, when in competition with wild-type Yersinia in a mixed infection, the yopJ mutant strain is deficient for spread from the Peyer's patches to other lymphoid tissue. We also show that wild-type Yersinia induces apoptosis in vivo of Mac-1+ cells from infected mesenteric lymph nodes or spleens, as measured by quantitative flow cytometry of TUNEL (Tdt-mediated dUTP–biotin nick-end labeling)-positive cells. The levels of Mac-1+, TUNEL+ cells from tissue infected with the yopJ mutant strain were equivalent to the levels detected in cells from uninfected tissue. YopJ is necessary for the suppression of TNF-α production seen in macrophages infected with wild-type Yersinia, based on previous in vitro studies (Palmer, L.E., S. Hobbie, J.E. Galan, and J.B. Bliska. 1998. Mol. Microbiol. 27:953–965). We conclude here that YopJ plays a role in the establishment of a systemic infection by inducing apoptosis and that this is consistent with the ability to suppress the production of the proinflammatory cytokine tumor necrosis factor α.

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