Journal of leukocyte biology
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Neutrophil extracellular traps are associated with a unique form of cell death distinct from apoptosis or necrosis, whereby invading microbes are trapped and killed. Neutrophil extracellular traps can contribute to autoimmunity by exposing autoantigens, inducing IFN-α production, and activating the complement system. The association of neutrophil extracellular traps with autoimmune diseases, particularly systemic lupus erythematosus, will be reviewed. ⋯ In addition to anti-IFN-α therapies, other novel agents, such as N-acetyl-cysteine, DNase I, and peptidylarginine deiminase inhibitor 4, target neutrophil extracellular traps. Neutrophil extracellular traps offer insight into the pathogenesis of autoimmune diseases and provide promise in developing disease markers and novel therapeutic agents in systemic lupus erythematosus. Priority areas for basic research based on clinical research insights will be identified, specifically the potential role of neutrophil extracellular traps as a biomarker and therapeutic target in systemic lupus erythematosus.
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In addition to being key elements in hemostasis and thrombosis, platelets amplify neutrophil function. We aimed to gain further insight into the stimuli, mediators, molecular pathways, and regulation of neutrophil extracellular trap formation mediated by human platelets. Platelets stimulated by lipopolysaccharide, a wall component of gram-negative bacteria, Pam3-cysteine-serine-lysine 4, a mimetic of lipopeptide from gram-positive bacteria, Escherichia coli, Staphylococcus aureus, or physiologic platelet agonists promoting neutrophil extracellular trap formation and myeloperoxidase-associated DNA activity under static and flow conditions. ⋯ Signaling through extracellular signal-regulated kinase, phosphatidylinositol 3-kinase, and Src kinases, but not p38 or reduced nicotinamide adenine dinucleotide phosphate oxidase, was involved in platelet-triggered neutrophil extracellular trap release. Platelet-mediated neutrophil extracellular trap formation was inhibited by prostacyclin. Our results support a role for stimulated platelets in promoting neutrophil extracellular trap formation, reveal that an endothelium-derived molecule contributes to limiting neutrophil extracellular trap formation, and highlight platelet inhibition as a potential target for controlling neutrophil extracellular trap cell death.
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Inflammation is induced because of interplay among multiple signaling pathways and molecules during infectious and noninfectious tissue injuries. Crosstalk between Toll-like receptor-4 signaling and the neuronal apoptosis inhibitor protein, major histocompatibility class 2 transcription activator, incompatibility locus protein from Podospora anserina, and telomerase-associated protein (NACHT), leucine-rich repeat (LRR), and pyrin domain-containing protein 3 (NLRP3) inflammasome against pathogen- or damage-associated molecular patterns can cause exaggerated inflammation. We previously established that the Toll-like receptor-4-interacting SPA4 peptide suppresses gram-negative bacterial lipopolysaccharide (Toll-like receptor-4 ligand)-induced nuclear factor-κB and inflammatory response. ⋯ We also found that the SPA4 peptide inhibits mRNA and cellular protein levels of pro-interleukin-1β and NLRP3, formation of the NLRP3 inflammasome, caspase activity, and release of interleukin-1β. Furthermore, the SPA4 peptide treatment reduced the secreted levels of interleukin-1β from cells overexpressing Toll-like receptor-4 compared with cells expressing the dominant-negative form of Toll-like receptor-4. Together our results suggest that the SPA4 peptide exerts its anti-inflammatory activity by suppressing Toll-like receptor-4-priming of the NLRP3 inflammasome.
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Recent comparisons of the murine and human transcriptome in health and disease have called into question the appropriateness of the use of murine models for human sepsis and trauma research. More specifically, researchers have debated the suitability of mouse models of severe inflammation that is intended for eventual translation to human patients. This mini-review outlines this recent research, as well as specifically defines the arguments for and against murine models of sepsis and trauma research based on these transcriptional studies. In addition, we review newer advancements in murine models of infection and injury and define what we envision as an evolving but viable future for murine studies of sepsis and trauma.
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Severe septic syndromes deeply impair innate and adaptive immunity and are responsible for sepsis-induced immunosuppression. Although neutrophils represent the first line of defense against infection, little is known about their phenotype and functions a few days after sepsis, when the immunosuppressive phase is maximal (i.e., between d 3 and 8). The objective of the present study was to perform, for the first time, a global evaluation of neutrophil alterations in immunosuppressed septic patients (at d 3-4 and d 6-8) using phenotypic and functional studies. ⋯ These dysfunctions might participate in the deleterious role of sepsis-induced immunosuppression. The present results open new perspectives in the mechanisms favoring nosocomial infections after septic shock. They deserve to be further investigated in a larger clinical study and in animal models recapitulating these alterations.