Potentiation of NETs release is novel characteristic of TREM-1 activation and the pharmacological inhibition of TREM-1 could prevent from the deleterious consequences of NETs release in sepsis.
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ABSTRACT:
SUBMITTER: Boufenzer A
PROVIDER: S-EPMC8026640 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Sepsis is a deadly inflammatory syndrome caused by an exaggerated immune response to infection. Much has been focused on host response to pathogens mediated through the interaction of pathogen-associated molecular patterns (PAMPs) and pattern recognition receptors (PRRs). PRRs are also activated by host nuclear, mitochondrial, and cytosolic proteins, known as damage-associated molecular patterns (DAMPs) that are released from cells during sepsis. Some well described members of the DAMP family are extracellular cold-inducible RNA-binding protein (eCIRP), high mobility group box 1 (HMGB1), histones, and adenosine triphosphate (ATP). DAMPs are released from the cell through inflammasome activation or passively following cell death. Similarly, neutrophil extracellular traps (NETs) are released from neutrophils during inflammation. NETs are webs of extracellular DNA decorated with histones, myeloperoxidase, and elastase. Although NETs contribute to pathogen clearance, excessive NET formation promotes inflammation and tissue damage in sepsis. Here, we review DAMPs and NETs and their crosstalk in sepsis with respect to their sources, activation, release, and function. A clear grasp of DAMPs, NETs and their interaction is crucial for the understanding of the pathophysiology of sepsis and for the development of novel sepsis therapeutics.
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Project description:Recent work has implicated spreading depolarization (SD) as a key contributor the progression of acute brain injuries, however development of interventions selectively targeting SD has lagged behind. Initial clinical intervention efforts have focused on observations that relatively high doses of the sedative agent ketamine can completely suppress SD. However, blocking propagation of SD could theoretically prevent beneficial effects of SD in surrounding brain regions. Selective targeting of deleterious consequences of SD (rather than abolition) could be a useful adjunct approach, and be achieved with lower ketamine concentrations. We utilized a brain slice model to test whether deleterious consequences of SD could be prevented by ketamine, using concentrations that did not prevent the initiation and propagation of SD. Studies were conducted using murine brain slices, with focal KCl as an SD stimulus. Consequences of SD were assessed with electrophysiological and imaging measures of ionic and synaptic recovery. Under control conditions, ketamine (up to 30??M) did not prevent SD, but significantly reduced neuronal Ca2+ loading and the duration of associated extracellular potential shifts. Recovery of postsynaptic potentials after SD was also significantly accelerated. When SD was evoked on a background of mild metabolic compromise, neuronal recovery was substantially impaired. Under compromised conditions, the same concentrations of ketamine reduced ionic and metabolic loading during SD, sufficient to preserve functional recovery after repetitive SDs. These results suggest that lower concentrations of ketamine could be utilized to prevent damaging consequences of SD, while not blocking them outright and thereby preserving potentially protective effects of SD.
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Project description:ObjectiveTo explore the expression feature and biological functions of TREM-1 on tumor-associated macrophages (TAMs) in lung cancer.ResultsThe levels of TREM-1 on tissue-infiltrating monocytes/macrophage from tumor nest were significantly lower than those from nonturmor tissue or peripheral blood samples. Clinical analysis indicated that the levels of TREM-1-related TAMs were significantly decreased during cancer stages progression. The tumor-bearing mouse model further confirmed that the expression of TREM-1 on TAMs was significantly decreased with tumor growth. In addition, we found the activation of TREM-1 could significantly enhance the secretion of IL-1β by TAM in vitro. Furthermore, T-bet but not Eomes was found to be the key transcription factor for the TREM-1 expression on monocytes/macrophage.MethodsA total of 40 patients with non-small cell lung cancer (NSCLC) were enrolled in this study. The expression characteristics of TREM-1 in blood and tissue-infiltrating monocytes/macrophage were examined by flow cytometry analysis. After the treatment of TREM-1 antibody, which is an agonist of TREM-1, cytokines secreted by TAM were then analyzed. In LLC-tumor bearing mouse model, we further investigated the dynamic expression feature of TREM-1 on macrophage with tumor growth. Moreover, we explored the transcription factor for regulating TREM-1 expression on monocyes/macrophage with wildtype, T-bet Ko or Eomes Ko mice.ConclusionThe levels of TREM-1 were remarkably decreased during tumor progression. The low expression level of TREM-1 might be a characteristic for TAMs in lung cancer.
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Project description:Parasitic nematodes pose a serious threat to agriculture, livestock, and human health. Increasing resistance to antiparasitic agents underscores the need to replenish our anthelmintic arsenal. The nonpathogenic Caenorhabditis elegans, which serves as an effective model of parasitic helminths, has been used to search for new anthelmintic leads. We previously reported small-molecule inhibitors of the essential C. elegans protein UDP-galactopyranose mutase (UGM or Glf). This enzyme is required for the generation of galactofuranose (Galf)-containing glycans and is needed in nematodes for proper cuticle formation. Though our first-generation inhibitors were effective in vitro, they elicited no phenotypic effects. These findings are consistent with the known difficulty of targeting nematodes. C. elegans is recalcitrant to pharmacological modulation; typically, less than 0.02% of small molecules elicit a phenotypic effect, even at 40 ?M. We postulated that the lack of activity of the UGM inhibitors was due to their carboxylic acid group, which can be exploited by nematodes for detoxification. We therefore tested whether replacement of the carboxylate with an N-acylsulfonamide surrogate would result in active compounds. UGM inhibitors with the carboxylate mimetic can phenocopy the deleterious consequences of UGM depletion in C. elegans. These findings support the use of UGM inhibitors as anthelmintic agents. They also outline a strategy to render small-molecule carboxylates more effective against nematodes.
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Project description:BackgroundNeutrophil extracellular traps (NETs) are innate defense mechanisms that are also implicated in the pathogenesis of organ dysfunction. However, the role of NETs in pediatric sepsis is unknown.MethodsInfant (2 weeks old) and adult (6 weeks old) mice were submitted to sepsis by intraperitoneal (i.p.) injection of bacteria suspension or lipopolysaccharide (LPS). Neutrophil infiltration, bacteremia, organ injury, and concentrations of cytokine, NETs, and DNase in the plasma were measured. Production of reactive oxygen and nitrogen species and release of NETs by neutrophils were also evaluated. To investigate the functional role of NETs, mice undergoing sepsis were treated with antibiotic plus rhDNase and the survival, organ injury, and levels of inflammatory markers and NETs were determined. Blood samples from pediatric and adult sepsis patients were collected and the concentrations of NETs measured.ResultsInfant C57BL/6 mice subjected to sepsis or LPS-induced endotoxemia produced significantly higher levels of NETs than the adult mice. Moreover, compared to that of the adult mice, this outcome was accompanied by increased organ injury and production of inflammatory cytokines. The increased NETs were associated with elevated expression of Padi4 and histone H3 citrullination in the neutrophils. Furthermore, treatment of infant septic mice with rhDNase or a PAD-4 inhibitor markedly attenuated sepsis. Importantly, pediatric septic patients had high levels of NETs, and the severity of pediatric sepsis was positively correlated with the level of NETs.ConclusionThis study reveals a hitherto unrecognized mechanism of pediatric sepsis susceptibility and suggests that NETs represents a potential target to improve clinical outcomes of sepsis.
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Project description:Early prognostic prediction of sepsis is essential in adjusting therapeutic protocols to prevent deterioration and reduce mortality. We compared the predictive value of the serum concentration of the soluble triggering receptor expressed on myeloid cells 1 (sTREM-1) for 28-day mortality and for the development of severe sepsis or septic shock on the third day with the levels of interleukin (IL)-6, C-reactive protein (CRP) and procalcitonin (PCT). The study was conducted on 85 patients with sepsis. sTREM-1, CRP, PCT and IL-6 concentrations were measured upon study inclusion (day 0) and on days 1, 2, 3 and 5. APACHE II, SAPS II and SOFA scores were analyzed. The sTREM-1 levels (pg/ml) were higher in non-survivors than in survivors at admission (773 vs. 391, p < 0.001) and on days 1, 2, 3 and 5. In predicting the development of severe sepsis, the highest AUCs were found for PCT (0.744, 95% CI 0.638-0.85) and sTREM-1 (0.664, 95% CI 0.55-0.778); and in septic shock prediction, for PCT (0.766, 95% CI 0.665-0.867) and IL-6 (0.707, 95% CI 0.595-0.819). sTREM-1 positively correlated with APACHE II, SAPS II and SOFA scores. At inclusion, significant AUC for predicting 28-day mortality was 0.772 for the sTREM-1 (95% CI 0.672-0.871), 0.858 for APACHE II (95% CI 0.768-0.948), 0.847 for SAPS II (95% CI 0.733-0.96), 0.806 for SOFA score (95% CI 0.698-0.915). sTREM-1 can early predict the 28-day sepsis mortality, although its effectiveness is lower in comparison with clinical severity scores.
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