scholarly journals Acidosis exacerbates in vivo IL-1-dependent inflammatory responses and neutrophil recruitment during pulmonaryPseudomonas aeruginosainfection

2018 ◽  
Vol 314 (2) ◽  
pp. L225-L235 ◽  
Author(s):  
Iviana M. Torres ◽  
Yash R. Patankar ◽  
Brent Berwin
Keyword(s):  
Inflammatory Responses ◽  
Neutrophil Recruitment

Circulating platelet-neutrophil complexes are important for subsequent neutrophil activation and migration

2010 ◽  
Vol 109 (3) ◽  
pp. 758-767 ◽  
Author(s):  
Kristin N. Kornerup ◽  
Gary P. Salmon ◽  
Simon C. Pitchford ◽  
Wai L. Liu ◽  
Clive P. Page
Keyword(s):  
Inflammatory Responses ◽  
Functional Expression ◽  
Neutrophil Activation ◽  
Neutrophil Recruitment ◽  
Current Therapy ◽  
Adequate Treatment ◽  
Relative Contribution ◽  
Inflammatory Conditions ◽  
Inflammatory Stimuli

Previous studies in our laboratory have shown that platelets are essential for the migration of eosinophils into the lungs of allergic mice, and that this is dependent on the functional expression of platelet P-selectin. We sought to investigate whether the same is true for nonallergic, acute inflammatory stimuli administered to distinct anatomic compartments. Neutrophil trafficking was induced in two models, namely zymosan-induced peritonitis and LPS-induced lung inflammation, and the platelet dependence of these responses investigated utilizing mice rendered thrombocytopenic. The relative contribution of selectins was also investigated. The results presented herein clearly show that platelet depletion (>90%) significantly inhibits neutrophil recruitment in both models. In addition, we show that P-selectin glycoprotein ligand-1, but not P-selectin, is essential for neutrophil recruitment in mice in vivo, thus suggesting the existence of different regulatory mechanisms for the recruitment of leukocyte subsets in response to allergic and nonallergic stimuli. Further studies in human blood demonstrate that low-dose prothrombotic and pro-inflammatory stimuli (CCL17 or CCL22) synergize to induce platelet and neutrophil activation, as well as the formation of platelet-neutrophil conjugates. We conclude that adhesion between platelets and neutrophils in vivo is an important event in acute inflammatory responses. Targeting this interaction may be a successful strategy for inflammatory conditions where current therapy fails to provide adequate treatment.

scholarly journals Neutrophil recruitment inhibitory factor: a possible candidate for a novel cytokine

1992 ◽  
Vol 1 (1) ◽  
pp. 49-54 ◽  
Author(s):  
W. M. S. C. Tamashiro ◽  
B. M. Tavares-Murta ◽  
F. Q. Cunha ◽  
M. C. Roque-Barreira ◽  
R. M. D. Nogueira ◽  
...  
Keyword(s):  
Inhibitory Activity ◽  
Inflammatory Responses ◽  
Neutrophil Migration ◽  
Gel Filtration ◽  
Inhibitory Effect ◽  
Neutrophil Recruitment ◽  
Tnf Α ◽  
Inflammatory Stimuli

Inhibitory effect upon neutrophil migration to the inflammatory focus was previously detected in the cell-free incubation fluid of lipopolysaccharide (LPS)-stimulated macrophage monolayers. In the present study we showed that the neutrophil recruitment inhibitory activity from this supernatant was mainly detected in a fraction (P2) obtained by gel filtration chromatography on Sephacryl S-300. P2 fraction was able to inhibit ‘in vivo’ neutrophil emigration induced by different inflammatory stimuli, but it did not affect ‘in vitro’ neutrophil chemotaxis induced by FMLP. When injected intravenously, P2 inhibited oedema induced by carrageenin or immunological stimulus but not the oedema induced by dextran, thus affecting cell-dependent inflammatory responses. It was observed that P2 also induced neutrophil migration when injected locally in peritoneal cavities. This activity was significantly reduced by pretreatment of the animals with dexamethasone. Cytokines, such as IL-8 and TNF-α that are known to exhibit inhibitory effect upon neutrophil migration, were not detected in P2 fraction by highly sensitive assays. Overall the results suggest the existence of a novel cytokine exhibiting ‘in vivo’ neutrophil inhibitory activity, referred as NRIF.

INTERACTION OF CD44 AND HYALURONAN IS THE DOMINANT MECHANISM FOR NEUTROPHIL ADHESION IN INFLAMED LIVER SINUSOIDS

2008 ◽  
Vol 31 (4) ◽  
pp. 16
Author(s):  
Braedon McDonald ◽  
Erin F McAvoy ◽  
Florence Lam ◽  
Varinder Gill ◽  
Paul Kubes
Keyword(s):  
Adhesion Molecules ◽  
Intravital Microscopy ◽  
Inflammatory Responses ◽  
Flow Chamber ◽  
Neutrophil Recruitment ◽  
Neutrophil Adhesion ◽  
Antibody Technique ◽  
Liver Sinusoids

Background: Previous studies have been unable to identify adhesion molecules that mediate neutrophil recruitment within the liver sinusoids. We hypothesise that involved adhesion molecules may represent novel therapeutic targets for combating pathologic liver inflammation. Methods: Candidate adhesion molecules were identified using a novel in vivo biopanning approach (dual radiolabelled antibody technique) to quantify endothelial expression levels within the liver compared to other organs. Spinning disk intravital microscopy demonstrated the localization of adhesion molecule expression withinthe liver microvasculature. Using knockout mice, bone marrow chimeric mice, and blocking antibodies, candidate adhesion molecules were systematically investigated for a role in neutrophil recruitment in the liver sinusoids of endotoxemic mice using intravital microscopy and in vitro flow chamber assays. Results: Hyaluronan was identified as disproportionately expressed in the liver versus other organs, and hyaluronan expression was restricted to liver sinusoids. Blocking CD44-hyaluronan interactions reduced neutrophil adhesion in the sinusoids of endotoxemic mice, but had no effect on neutrophil rolling or adhesion in post-sinusoidal venules. Neutrophil but not endothelial CD44 was required for adhesionin sinusoids. Surprisingly, neutrophil CD44 avidity for hyaluronan was not increased in endotoxemia. Instead, activation of CD44-hyaluronan engagement was the result of qualitative modification of hyaluronan by a dramatic induction of serum-derived hyaluronan-associated protein (SHAP) in sinusoids in response to lipopolysaccharide. Lipopolysaccharide-induced hepatic injury was significantly reduced by inhibiting CD44-hyaluronan interactions. Therapeutic administration of anti-CD44 antibody to endotoxemic mice rapidly detached adherent neutrophils and improved sinusoidal perfusion. Conclusion: These findings reveal CD44 as a potential therapeutic target in systemic inflammatory responses involving liver.

Anti-β2 Glycoprotein I Antibodies Cause Inflammation and Recruit Dendritic Cells in Platelet Clearance

2001 ◽  
Vol 86 (11) ◽  
pp. 1257-1263 ◽  
Author(s):  
Attilio Bondanza ◽  
Angelo Manfredi ◽  
Valérie Zimmermann ◽  
Matteo Iannacone ◽  
Angela Tincani ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Inflammatory Responses ◽  
Glycoprotein I ◽  
Activated Platelets ◽  
Tnf Α ◽  
Per Se ◽  
Antigen Presenting ◽  
Antiinflammatory Cytokine

SummaryScavenger phagocytes are mostly responsible for the in vivo clearance of activated or senescent platelets. In contrast to other particulate substrates, the phagocytosis of platelets does not incite pro-inflammatory responses in vivo. This study assessed the contribution of macrophages and dendritic cells (DCs) to the clearance of activated platelets. Furthermore, we verified whether antibodies against the β2 Glycoprotein I (β2GPI), which bind to activated platelets, influence the phenomenon. DCs did not per se internalise activated platelets. In contrast, macrophages efficiently phagocytosed platelets. In agreement with the uneventful nature of the clearance of platelets in vivo, phagocytosing macrophages did not release IL-1β, TNF-α or IL-10. β2GPI bound to activated platelets and was required for their recognition by anti-ββ2GPI antibodies. DCs internalised platelets opsonised by anti-ββ2GPI antibodies. The phagocytosis of opsonised platelets determined the release of TNF-α and IL-1β by DCs and macrophages. Phagocytosing macrophages, but not DCs, secreted the antiinflammatory cytokine IL-1β0. We conclude that anti-ββ2GPI antibodies cause inflammation during platelet clearance and shuttle platelet antigens to antigen presenting DCs.

scholarly journals AMPK activates Parkin independent autophagy and improves post sepsis immune defense against secondary bacterial lung infections

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nathaniel B. Bone ◽  
Eugene J. Becker ◽  
Maroof Husain ◽  
Shaoning Jiang ◽  
Anna A. Zmijewska ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Pathogenic Bacteria ◽  
Inflammatory Responses ◽  
Abdominal Sepsis ◽  
Immune Defense ◽  
Bacterial Killing ◽  
Lung Infections ◽  
Sepsis Survivors ◽  
The Impact

AbstractMetabolic and bioenergetic plasticity of immune cells is essential for optimal responses to bacterial infections. AMPK and Parkin ubiquitin ligase are known to regulate mitochondrial quality control mitophagy that prevents unwanted inflammatory responses. However, it is not known if this evolutionarily conserved mechanism has been coopted by the host immune defense to eradicate bacterial pathogens and influence post-sepsis immunosuppression. Parkin, AMPK levels, and the effects of AMPK activators were investigated in human leukocytes from sepsis survivors as well as wild type and Park2−/− murine macrophages. In vivo, the impact of AMPK and Parkin was determined in mice subjected to polymicrobial intra-abdominal sepsis and secondary lung bacterial infections. Mice were treated with metformin during established immunosuppression. We showed that bacteria and mitochondria share mechanisms of autophagic killing/clearance triggered by sentinel events that involve depolarization of mitochondria and recruitment of Parkin in macrophages. Parkin-deficient mice/macrophages fail to form phagolysosomes and kill bacteria. This impairment of host defense is seen in the context of sepsis-induced immunosuppression with decreased levels of Parkin. AMPK activators, including metformin, stimulate Parkin-independent autophagy and bacterial killing in leukocytes from post-shock patients and in lungs of sepsis-immunosuppressed mice. Our results support a dual role of Parkin and AMPK in the clearance of dysfunctional mitochondria and killing of pathogenic bacteria, and explain the immunosuppressive phenotype associated Parkin and AMPK deficiency. AMPK activation appeared to be a crucial therapeutic target for the macrophage immunosuppressive phenotype and to reduce severity of secondary bacterial lung infections and respiratory failure.

scholarly journals Lipoproteins Are Responsible for the Pro-Inflammatory Property of Staphylococcus aureus Extracellular Vesicles

2021 ◽  
Vol 22 (13) ◽  
pp. 7099
Author(s):  
Pradeep Kumar Kopparapu ◽  
Meghshree Deshmukh ◽  
Zhicheng Hu ◽  
Majd Mohammad ◽  
Marco Maugeri ◽  
...  
Keyword(s):  
Extracellular Vesicles ◽  
Inflammatory Responses ◽  
Surface Proteins ◽  
Host Cells ◽  
Immune Stimulation ◽  
Domains Of Life ◽  
Major Surface ◽  
Staphylococcal Aureus

Staphylococcal aureus (S. aureus), a Gram-positive bacteria, is known to cause various infections. Extracellular vesicles (EVs) are a heterogeneous array of membranous structures secreted by cells from all three domains of life, i.e., eukaryotes, bacteria, and archaea. Bacterial EVs are implied to be involved in both bacteria–bacteria and bacteria–host interactions during infections. It is still unclear how S. aureus EVs interact with host cells and induce inflammatory responses. In this study, EVs were isolated from S. aureus and mutant strains deficient in either prelipoprotein lipidation (Δlgt) or major surface proteins (ΔsrtAB). Their immunostimulatory capacities were assessed both in vitro and in vivo. We found that S. aureus EVs induced pro-inflammatory responses both in vitro and in vivo. However, this activity was dependent on lipidated lipoproteins (Lpp), since EVs isolated from the Δlgt showed no stimulation. On the other hand, EVs isolated from the ΔsrtAB mutant showed full immune stimulation, indicating the cell wall anchoring of surface proteins did not play a role in immune stimulation. The immune stimulation of S. aureus EVs was mediated mainly by monocytes/macrophages and was TLR2 dependent. In this study, we demonstrated that not only free Lpp but also EV-imbedded Lpp had high pro-inflammatory activity.

scholarly journals Involvement of HECTD1 in LPS-induced astrocyte activation via σ-1R-JNK/p38-FOXJ2 axis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ying Tang ◽  
Mengchun Zhou ◽  
Rongrong Huang ◽  
Ling Shen ◽  
Li Yang ◽  
...  
Keyword(s):  
Inflammatory Responses ◽  
Astrocyte Activation ◽  
Hect Domain ◽  
P38 Inhibitor ◽  
Ubiquitin Protein Ligase ◽  
Primary Mouse ◽  
Lps Treatment

Abstract Background Astrocytes participate in innate inflammatory responses within the mammalian central nervous system (CNS). HECT domain E3 ubiquitin protein ligase 1 (HECTD1) functions during microglial activation, suggesting a connection with neuroinflammation. However, the potential role of HECTD1 in astrocytes remains largely unknown. Results Here, we demonstrated that HECTD1 was upregulated in primary mouse astrocytes after 100 ng/ml lipopolysaccharide (LPS) treatment. Genetic knockdown of HECTD1 in vitro or astrocyte-specific knockdown of HECTD1 in vivo suppressed LPS-induced astrocyte activation, whereas overexpression of HECTD1 in vitro facilitated LPS-induced astrocyte activation. Mechanistically, we established that LPS activated σ-1R-JNK/p38 pathway, and σ-1R antagonist BD1047, JNK inhibitor SP600125, or p38 inhibitor SB203580 reversed LPS-induced expression of HECTD1, thus restored LPS-induced astrocyte activation. In addition, FOXJ2 functioned as a transcription factor of HECTD1, and pretreatment of primary mouse astrocytes with BD1047, SB203580, and SP600125 significantly inhibited LPS-mediated translocation of FOXJ2 into the nucleus. Conclusions Overall, our present findings suggest that HECTD1 participates in LPS-induced astrocyte activation by activation of σ-1R-JNK/p38-FOXJ2 pathway and provide a potential therapeutic strategy for neuroinflammation induced by LPS or any other neuroinflammatory disorders.

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