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Immune Response Resetting in Ongoing Sepsis.

ABSTRACT: Cure of severe infections, sepsis, and septic shock with antimicrobial drugs is a challenge because morbidity and mortality in these conditions are essentially caused by improper immune response. We have tested the hypothesis that repeated reactivation of established memory to pathogens may reset unfavorable immune responses. We have chosen for this purpose a highly stringent mouse model of polymicrobial sepsis by cecum ligation and puncture. Five weeks after priming with a diverse Ag pool, high-grade sepsis was induced in C57BL/6j mice that was lethal in 24 h if left untreated. Antimicrobial drug (imipenem) alone rescued 9.7% of the animals from death, but >5-fold higher cure rate could be achieved by combining imipenem and two rechallenges with the Ag pool (p < 0.0001). Antigenic stimulation fine-tuned the immune response in sepsis by contracting the total CD3⁺ T cell compartment in the spleen and disengaging the hyperactivation state in the memory T subsets, most notably CD8⁺ T cells, while preserving the recovery of naive subsets. Quantitative proteomics/lipidomics analyses revealed that the combined treatment reverted the molecular signature of sepsis for cytokine storm, and deregulated inflammatory reaction and proapoptotic environment, as well as the lysophosphatidylcholine/phosphatidylcholine ratio. Our results showed the feasibility of resetting uncontrolled hyperinflammatory reactions into ordered hypoinflammatory responses by memory reactivation, thereby reducing morbidity and mortality in antibiotic-treated sepsis. This beneficial effect was not dependent on the generation of a pathogen-driven immune response itself but rather on the reactivation of memory to a diverse Ag pool that modulates the ongoing response.

SUBMITTER: Nowill AE

PROVIDER: S-EPMC6697741 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Immune Response Resetting in Ongoing Sepsis.

Nowill Alexandre E AE Fornazin Márcia C MC Spago Maria C MC Dorgan Neto Vicente V Pinheiro Vitória R P VRP Alexandre Simônia S S SSS Moraes Edgar O EO Souza Gustavo H M F GHMF Eberlin Marcos N MN Marques Lygia A LA Meurer Eduardo C EC Franchi Gilberto C GC de Campos-Lima Pedro O PO

Journal of immunology (Baltimore, Md. : 1950) 20190729 5

Cure of severe infections, sepsis, and septic shock with antimicrobial drugs is a challenge because morbidity and mortality in these conditions are essentially caused by improper immune response. We have tested the hypothesis that repeated reactivation of established memory to pathogens may reset unfavorable immune responses. We have chosen for this purpose a highly stringent mouse model of polymicrobial sepsis by cecum ligation and puncture. Five weeks after priming with a diverse Ag pool, high ...[more]

PMID: 31358659

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Project description:BACKGROUND/OBJECTIVES: Sepsis is one of the most important causes of mortality in the developed world, where almost two-thirds of the population suffer from obesity. Therefore, the coexistence of both conditions has become frequent in clinical practice and a growing number of clinical studies attempts to examine the potential effect of obesity on sepsis with controversial results up to now. The present study investigates how obesity influences the immune response of septic patients, by assessing the number and activation state of adipose tissue macrophages, serum and adipose tissue tumor necrosis factor-alpha (TNFα) levels and plasma oxidative stress markers. SUBJECTS/METHODS: The study included 106 patients, divided into four groups (control n=26, obesity n=27, sepsis n=27 and sepsis and obesity n=26). The number of macrophages in subcutaneous and visceral adipose tissue (SAT and VAT) and their subtypes (M1 and M2) were defined with immunohistochemical staining techniques under light microscopy. TNFα mRNA levels were determined in SAT and VAT using real-time reverse transcription-PCR. Serum levels of TNFα were determined with sandwich enzyme-linked immunosorbent assay. Plasma oxidative stress was evaluated using selective biomarkers (thiobarbituric acid-reactive substances (TBARS), protein carbonyls and total antioxidant capacity (TAC)). RESULTS: Sepsis increased the total number of macrophages and their M2 subtype in (VAT), whereas obesity did not seem to affect the concentration of macrophages in fat. Obesity increased TNFα mRNA levels (P<0.05) in VAT as well as the plasma TBARS (P<0.001) and protein carbonyls (P<0.001) in septic patients. The plasma TAC levels were decreased and the serum TNFα levels were increased in sepsis although they were not influenced by obesity. CONCLUSIONS: Obesity is associated with elevated TNFα adipose tissue production and increased oxidative stress biomarkers, promoting the proinflammatory response in septic patients.

Project description:BackgroundSepsis and septic shock kill over 270,000 patients per year in the United States. Sepsis transitions from a hyper-inflammatory to a hypo-inflammatory phase. Alcohol dependence is a risk factor for mortality from sepsis. Ethanol (EtOH) exposure impairs pathogen clearance through mechanisms that are not fully understood. Sirtuin 2 (SIRT2) interferes with pathogen clearance in immune cells but its role in the effects of EtOH on sepsis is unknown. We studied the effect of EtOH exposure on hyper- and hypo-inflammation and the role of SIRT2 in mice.MethodsWe exposed C57Bl/6 (WT) mice to EtOH via drinking water and used intraperitoneal cecal slurry (CS)-induced sepsis to study: (i) 7-day survival, (ii) leukocyte adhesion (LA) in the mesenteric microcirculation during hyper- and hypo-inflammation, (iii) peritoneal cavity bacterial clearance, and (iv) SIRT2 expression in peritoneal macrophages. Using EtOH-exposed and lipopolysaccharide (LPS)-stimulated RAW 264.7 (RAW) cell macrophages for 4 hours or 24 hours, we studied: (i) tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-10 (IL-10), and SIRT2 expression, and (ii) the effect of the SIRT2 inhibitor AK-7 on inflammatory response at 24 hours. Lastly, we studied the effect of EtOH on sepsis in whole body Sirt2 knockout (SIRT2KO) mice during hyper- and hypo-inflammation, bacterial clearance, and 7-day survival.ResultsWT EtOH-sepsis mice showed: (i) Decreased survival, (ii) Muted LA in the microcirculation, (iii) Lower plasma TNF-α and IL-6 expression, (iv) Decreased bacterial clearance, and (v) Increased SIRT2 expression in peritoneal macrophages versus vehicle-sepsis. EtOH-exposed LPS-stimulated RAW cells showed: (i) Muted TNF-α, IL-6, and increased IL-10 expression at 4 hours, (ii) endotoxin tolerance at 24 hours, and (iii) reversal of endotoxin tolerance with the SIRT2 inhibitor AK-7. EtOH-exposed SIRT2KO-sepsis mice showed greater 7-day survival, LA, and bacterial clearance than WT EtOH-sepsis mice.ConclusionEtOH exposure decreases survival and reduces the inflammatory response to sepsis via increased SIRT2 expression. SIRT2 is a potential therapeutic target in EtOH with sepsis.

Project description:ImportanceLong-term immune sequelae after sepsis are poorly understood.ObjectiveTo assess whether abnormalities in the host immune response during hospitalization for sepsis persist after discharge.Design, settings, and participantsThis prospective, multicenter cohort study enrolled and followed up for 1 year adults who survived a hospitalization for sepsis from January 10, 2012, to May 25, 2017, at 12 US hospitals.ExposuresCirculating levels of inflammation (interleukin 6 and high-sensitivity C-reactive protein [hs-CRP]), immunosuppression (soluble programmed death ligand 1 [sPD-L1]), hemostasis (plasminogen activator inhibitor 1 and D-dimer), endothelial dysfunction (E-selectin, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1), and oxidative stress biomarkers were measured at 5 time points during and after hospitalization for sepsis for 1 year. Individual biomarker trajectories and patterns of trajectories across biomarkers (phenotypes) were identified.Main outcomes and measuresOutcomes were adjudicated centrally and included all-cause and cause-specific readmissions and mortality.ResultsA total of 483 patients (mean [SD] age, 60.5 [15.2] years; 265 [54.9%] male) who survived hospitalization for sepsis were included in the study. A total of 376 patients (77.8%) had at least 1 chronic disease, and their mean (SD) Sequential Organ Failure Assessment score was 4.2 (3.0). Readmissions were common (485 readmissions in 205 patients [42.5%]), and 43 patients (8.9%) died by 3 months, 56 patients (11.6%) died by 6 months, and 85 patients (17.6%) died by 12 months. Elevated hs-CRP levels were observed in 23 patients (25.8%) at 3 months, 26 patients (30.2%) at 6 months, and 23 patients (25.6%) at 12 months, and elevated sPD-L1 levels were observed in 45 patients (46.4%) at 3 months, 40 patients (44.9%) at 6 months, and 44 patients (49.4%) at 12 months. Two common phenotypes were identified based on hs-CRP and sPDL1 trajectories: high hs-CRP and sPDL1 levels (hyperinflammation and immunosuppression phenotype [326 of 477 (68.3%)]) and normal hs-CRP and sPDL1 levels (normal phenotype [143 of 477 (30.0%)]). These phenotypes had similar clinical characteristics and clinical course during hospitalization for sepsis. Compared with normal phenotype, those with the hyperinflammation and immunosuppression phenotype had higher 1-year mortality (odds ratio, 8.26; 95% CI, 3.45-21.69; P < .001), 6-month all-cause readmission or mortality (hazard ratio [HR], 1.53; 95% CI, 1.10-2.13; P = .01), and 6-month readmission or mortality attributable to cardiovascular disease (HR, 5.07; 95% CI, 1.18-21.84; P = .02) or cancer (HR, 5.15; 95% CI, 1.25-21.18; P = .02). These associations were adjusted for demographic characteristics, chronic diseases, illness severity, organ support, and infection site during sepsis hospitalization and were robust in sensitivity analyses.Conclusions and relevanceIn this study, persistent elevation of inflammation and immunosuppression biomarkers occurred in two-thirds of patients who survived a hospitalization for sepsis and was associated with worse long-term outcomes.

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Immune Response Resetting in Ongoing Sepsis.

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Immune Response Resetting in Ongoing Sepsis.

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