Shock : molecular, cellular, and systemic pathobiological aspects and therapeutic approaches : the official journal the Shock Society, the European Shock Society, the Brazilian Shock Society, the International Federation of Shock Societies
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Since the definition of systemic inflammatory response syndrome/sepsis was originally proposed, a large amount of new information has been generated showing a much more complex scenario of inflammatory and counterinflammatory responses during sepsis. Moreover, some fundamental mechanisms of sensing and destroying invading microorganisms have been uncovered, which include the discovery of TLR4 as the lipopolysaccharide (LPS) gene, implications of innate immune cells as drivers of the adaptive response to infection, and the modulation of multiple accessory molecules that stimulate or inhibit monocyte/macrophage and lymphocyte interactions. ⋯ In this review, we discuss aspects of bacterial recognition and induced cellular activation during sepsis. Because of the relevance of endotoxin (LPS) research in the field, we focus on LPS and host interactions as a clue to understand microorganisms sensing and cell signaling, then we discuss how this response is modulated in septic patients.
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Randomized Controlled Trial
Continuous enteral and parenteral feeding each reduces heart rate variability but differentially influences monocyte gene expression in humans.
Enteral (EN) or parenteral (PN) nutrition is used to support critically ill patients until oral feeding resumes. Enteral nutrition is assumed preferable to PN, but the differential influence on immune function is not well defined. Autonomic nervous activity is known to influence innate immune responses, and we hypothesized that EN and PN could influence both autonomic signaling and gene activation in peripheral blood monocytes (PBMs). ⋯ However, PN feeding had a much greater influence on PBM gene expression compared with baseline than EN, including genes important to innate immunity. Continuous EN and PN are both associated with decreasing vagal tone over time, yet contribute differently to PBM gene expression, in humans. These preliminary findings support assumptions that PN imposes a systemic inflammatory risk but also imply that continuous feeding, independent of route, may impart additional risk through different mechanisms.
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Sepsis is still a leading cause of death on intensive care units. Despite intensive research, only few new therapies have been developed and used in the clinical setting. The fibrin fragment Bβ15-42 was already shown to preserve endothelial barrier function by binding to VE-cadherin and thus stabilize the interendothelial junctions. ⋯ Analysis alanine aminotransferase and aspartate aminotransferase further indicated reduced liver damage following polymicrobial sepsis. In vitro experiments using endothelial cells and macrophages further revealed that Bβ15-42 had no direct effect on Toll-like receptor-mediated inflammation. Therefore, we assume that attenuated inflammation is rather due to sustained vascular integrity and thus suppresses vascular leakage and subsequently leukocyte infiltration during sepsis.
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Clinical deterioration among hemodynamically stable sepsis patients occurs frequently, and patients with intermediate lactate levels (between 2.0 and 4.0 mmol/L) are particularly at risk for mortality. The aim of this study was to identify factors for predicting early deterioration in sepsis patients with intermediate levels of serum lactate. A retrospective cohort study of adult sepsis patients with lactate levels between 2.0 and 4.0 mmol/L was conducted in the emergency department of a tertiary care hospital between August 2008 and July 2010. ⋯ In patients with a Sequential Organ Failure Assessment score of 5 or greater, the predicted rate of progression to tissue hypoperfusion was 38.9%. Our study demonstrates potential risk factors, including organ failure, for progression to sepsis-induced tissue hypoperfusion in patients with intermediate levels of serum lactate. We suggest that an early aggressive treatment strategy is needed in patients with these risk factors.
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Nicotinic stimulation of the α7 acetylcholine receptors (α7AChRs) mitigates the lipopolysaccharide (LPS)-induced tumor necrosis factor α (TNF-α) and other cytokines release in macrophages. This effect is blocked by α7AChR antagonist, α-bungarotoxin (BTX). We tested and confirmed the hypotheses that LPS upregulates α7AChRs, and the prototypical α7AChR antagonists, vecuronium and BTX, do not block the effects of GTS-21, a specific α7AChR agonist, on TNF-α release. ⋯ Moreover, GTS-21 reduced mortality after burn injury in mice. These results indicate that (i) LPS upregulates α7AChRs; (ii) the therapeutic beneficial effects of GTS-21 on cytokine release are specifically mediated via α7AChRs and are preserved even when cotreated with prototypical antagonist, BTX, or clinically used muscle nicotinic antagonist, vecuronium; (iii) activation of α7AChRs by GTS-21 partially reverses the LPS-induced proliferation arrest; and (iv) GTS-21 reduces mortality in mice with burn injury. The in vivo beneficial effects of GTS-21 in burn injury warrant further studies.