Changes in peroxisome proliferator-activated receptor-gamma activity in children with septic shock

Cyclopentenone Prostaglandins: Biologically Active Lipid Mediators Targeting Inflammation

Cyclopentenone prostaglandins (cyPGs) are biologically active lipid mediators, including PGA2, PGA1, PGJ2, and its metabolites. cyPGs are essential regulators of inflammation, cell proliferation, apoptosis, angiogenesis, cell migration, and stem cell activity. cyPGs biologically act on multiple cellular targets, including transcription factors and signal transduction pathways. cyPGs regulate the inflammatory response by interfering with NF-κB, AP-1, MAPK, and JAK/STAT signaling pathways via both a group of nuclear receptor peroxisome proliferator-activated receptor-gamma (PPAR-γ) dependent and PPAR-γ independent mechanisms. cyPGs promote the resolution of chronic inflammation associated with cancers and pathogen (bacterial, viral, and parasitic) infection. cyPGs exhibit potent effects on viral infections by repressing viral protein synthesis, altering viral protein glycosylation, inhibiting virus transmission, and reducing virus-induced inflammation. We summarize their anti-proliferative, pro-apoptotic, cytoprotective, antioxidant, anti-angiogenic, anti-inflammatory, pro-resolution, and anti-metastatic potential. These properties render them unique therapeutic value, especially in resolving inflammation and could be used in adjunct with other existing therapies. We also discuss other α, β -unsaturated carbonyl lipids and cyPGs like isoprostanes (IsoPs) compounds.

Electroacupuncture Pretreatment Alleviates LPS-Induced Acute Respiratory Distress Syndrome via Regulating the PPAR Gamma/NF-Kappa B Signaling Pathway

Electroacupuncture (EA) is reported to possess anti-inflammatory properties and has beneficial effects on acute respiratory distress syndrome (ARDS). However, the underlying mechanisms of the effects of EA on ARDS remain unclear. This study aims to investigate the protective effect of EA on LPS-induced ARDS. In this study, Sprague-Dawley male rats were treated with EA at Hegu (LI4) for 45 minutes before LPS instillation (0.4 mg/kg, 100 ul). H&E staining, wet-to-dry weight (W/D) ratio, PaO₂, and protein content in BALF were employed to determine the function of lung tissues. Inflammatory cytokines in serum and BALF were detected by enzyme-linked immunoassay assay (ELISA). The levels of oxidative stress markers were detected to determine the oxidative stress status. Cell apoptosis was observed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining and western blot. Here, we found that EA pretreatment effectively alleviated lung pathological damage. Moreover, EA suppressed the oxidative stress damage by upregulating glutathione and superoxide dismutase and downregulating malondialdehyde. EA pretreatment also regulated apoptosis-related proteins, such as Bax and Bcl-2. We found that peroxisome proliferators-activated receptors γ (PPARγ) play a critical role during ARDS, EA up-regulated the expression of PPARγ, which inhibited the activation of nuclear factor-kappa B (NF-κB) and decreased the inflammatory cytokines (interleukin-1β, interleukin-6, and tumor necrosis factor-α). When rats were treated with GW9662, a selective PPARγ antagonist, these effects of EA were reversed. Our study demonstrated that EA pretreatment had a beneficial effect on LPS-induced ARDS in rats by anti-inflammatory, antioxidative, and antiapoptotic properties which was regulated via PPARγ/NF-κB signaling pathway.

Adiponectin as a sepsis biomarker in dogs: Diagnostic and prognostic value

BACKGROUND

Adiponectin (ADPN) is an adipocytokine with insulin-sensitizing, vascular-protective, and anti-inflammatory properties for which concentration changes occur in response to inflammation. Little is known about the regulation of ADPN and the impact of this adipocytokine in septic dogs.

OBJECTIVE

We aimed to assess the diagnostic and prognostic value of ADPN vs other traditional acute-phase proteins (APPs), such as albumin (ALB), haptoglobin (HPT), fibrinogen (FBG), ferritin (FRT), and C-reactive protein (CRP) in dogs with naturally acquired sepsis.

METHODS

This prospective observational study included 20 dogs with sepsis, 27 with low-grade systemic inflammation (LGSI), and 18 clinically healthy dogs as controls. For method analyses, plasma samples were obtained from all dogs on admission and then every 24-48 hours until discharge or death in the septic group.

RESULTS

Septic dogs had lower ADPN (2.4 ± 0.46 vs 4.5 ± 0.41mg/L, P < .001) dand ALB (17 ± 1 vs 22 ± 0.8g/L, P = .002), and tended to have higher CRP (87 ± 4.8 vs 73 ± 4.1mg/L, P < .079) concentrations than dogs with LGSI on admission. Only ADPN and ALB were able to successfully discriminate animals with LGSI from those presenting with sepsis with areas under the curve (AUCs) for the receiver operating characteristic (ROC) curves of 0.811 and 0.789, respectively. In the septic group, ADPN concentration did not differ between survivors and non-survivors, either on admission or at discharge or death.

CONCLUSIONS

Although plasma ADPN can be used as a reliable negative APP in dogs with sepsis, further studies are warranted to confirm the usefulness of this biomarker in terms of disease progression and recovery.

Effects of DHA-enriched fish oil on gene expression levels of p53 and NF-κB and PPAR-γ activity in PBMCs of patients with T2DM: A randomized, double-blind, clinical trial

BACKGROUND AND AIMS

Omega-3 polyunsaturated fatty acids (PUFAs) are natural peroxisome proliferator-activated receptor gamma (PPAR-γ) ligands. Activated PPAR-γ protects the cardiovascular system against atherosclerotic lesion formation and exerts its anti-inflammatory role by suppressing cytokines induced by nuclear factor kappa-B (NF-κB) in endothelial cells (ECs), and it is hypothesized that apoptosis and cell cycle arrest induced by PPAR-γ ligands may be mediated by the p53-dependent pathway. The aim of our study was to investigate the effects of docosahexaenoic acid (DHA)-enriched fish oil supplement on PPAR-γ activity and mRNA expression levels of p53 and NF-κB.

METHODS AND RESULTS

Fifty patients with type 2 diabetes mellitus (T2DM) aged 30-70 years were randomly assigned to receive either 2400 mg/d DHA-rich fish oil or placebo for 8 weeks. Metabolic parameters were assessed at baseline and at the end of the intervention. PPAR-γ activity in the peripheral blood mononuclear cells (PBMCs) was measured using ELISA-based PPAR-γ Transcription Factor Assay Kit, and the gene expression levels of p53 and NF-κB were assessed using real-time quantitative reverse transcription polymerase chain reaction (RT-PCR). On the basis of our finding, 8 weeks of treatment with DHA-rich fish oil increased PPAR-γ activity in PBMCs of subjects with T2DM (p < 0.01) compared to that in placebo (p = 0.4). Between-group comparisons of mean PPAR-γ activity changes showed significant differences (p = 0.03), whereas mRNA expression levels of the p53 and NF-κB genes did not show significant differences between studied groups (p = 0.2 and p = 0.5, respectively).

CONCLUSION

Our findings indicated that short-term DHA-rich fish oil supplementation may modulate PPAR-γ activity in PBMCs.

Association of obesity with morbidity and mortality in critically ill children: a systematic review and meta-analysis of observational studies

Recent studies have suggested that obesity might be protective in specific conditions such as critical illness; however, there are controversial data in critically ill children with obesity. The aim of this study was to investigate the association of obesity with mortality and other outcomes in these patients. We conducted a systematic review of observational studies investigating obesity in critically ill children, published by August 2017 in PubMed and Scopus. After screening documents, 15 articles with 142119 patients were included in the systematic review and meta-analysis. The results were reported with odds ratio (OR) or standard mean difference (SMD). The primary outcome was mortality and the secondary outcomes were length of ICU stay (ICU LOS), length of hospital stay (hospital LOS), and duration of mechanical ventilation (MV). The analysis showed that critically ill children without obesity had lower risk of mortality compared to patients with obesity (OR 0.79, 95% CI 0.64 to 0.97, P = 0.025, I² = 35.2%). Hospital LOS was also significantly lower in children without obesity (pooled SMD -0.12, 95% CI -0.21 to -0.04, P = 0.004, I² = 8.1%). There were no differences in ICU LOS (95% CI -0.19 to 0.01, P = 0.083) and duration of MV (95% CI -0.22 to 0.03, P = 0.136) between critically ill children with and without obesity. In conclusion, the current systematic review and meta-analysis revealed that critically ill children with obesity have higher risk of mortality and length of hospital stay compared to the group without obesity. Further prospective studies are essential to elucidate the role of obesity and underlying mechanisms in predicting outcomes of critically ill children.

Adipokines in critical illness: A review of the evidence and knowledge gaps

Adipose tissue products or adipokines play a major role in chronic endocrine and metabolic disorders; however, little is known about critical conditions. In this article, the experimental and clinical evidence of alterations of adipokines, adiponectin, leptin, resistin, visfatin, asymmetric dimethylarginine (ADMA), and ghrelin in critical illness, their potential metabolic, diagnostic, and prognostic value, and the gaps in the field have been reviewed. The results showed considerable changes in the concentration of the adipokines; while the impact of adipokines on metabolic disorders such as insulin resistance and inflammation has not been well documented in critically ill patients. There is no consensus about the circulatory and functional changes of leptin and adiponectin. However, it seems that lower concentrations of adiponectin at admission with gradual consequent increase might be a useful pattern in determining better outcomes of critical illness. Some evidence has suggested the adverse effects of elevated resistin concentration, potential prognostic importance of visfatin, and therapeutic value of ghrelin. High ADMA levels and low arginine:ADMA ratio were also proposed as predictors of ICU mortality and morbidities. However, there is no consensus on these findings. Although primary data indicated the role of adipokines in critical illness, further studies are required to clarify whether the reason of these changes is pathophysiological or compensatory. The relationship of pathophysiological background, disease severity, baseline nutritional status and nutrition support during hospitalization, and variations in body fat percentage and distribution with adipokines, as well as the potential prognostic or therapeutic role of these peptides should be further investigated in critically ill patients.

T cells and their immunometabolism: A novel way to understanding sepsis immunopathogenesis and future therapeutics

Sepsis has always been considered as a big challenge for pharmaceutical companies in terms of discovering and designing new therapeutics. The pathogenesis of sepsis involves aberrant activation of innate immune cells (i.e. macrophages, neutrophils etc.) at early stages. However, a stage of immunosuppression is also observed during sepsis even in the patients who have recovered from it. This stage of immunosuppression is observed due to the loss of conventional (i.e. CD4⁺, CD8⁺) T cells, Th17 cells and an upregulation of regulatory T cells (Tregs). This process also impacts metabolic processes controlling immune cell metabolism called immunometabolism. The present review is focused on the T cell-mediated immune response, their immunometabolism and targeting T cell immunometabolism during sepsis as future therapeutic approach. The first part of the manuscripts describes an impact of sepsis on conventional T cells, Th17 cells and Tregs along with their impact on sepsis. The subsequent section further describes the immunometabolism of these cells (CD4⁺, CD8⁺, Th17, and Tregs) under normal conditions and during sepsis-induced immunosuppression. The article ends with the therapeutic targeting of T cell immunometabolism (both conventional T cells and Tregs) during sepsis as a future immunomodulatory approach for its management.

Pparγ Expression in T Cells as a Prognostic Marker of Sepsis

Translating murine data to the human situation, we proposed that the level of peroxisome proliferator-activated receptor γ (PPARγ) expression in T cells from septic patients correlates with clinical outcome. In this preliminary report, we analyzed PPARγ mRNA expression in CD3 T cells derived from blood of a very small number of septic patients (n = 18) on various days up to 2 weeks after the initial diagnosis. CD3 T cell count was determined by flow cytometry. T cells from n = 11 healthy donors were included as controls. Maximal PPARγ mRNA expression was observed on the day of sepsis diagnosis (day 0; 5,896 ± 1,523 copies PPARγ mRNA/25 ng mRNA, P < 0.05 vs. controls). In contrast, the number of CD3 T cells was significantly decreased in septic patients compared with healthy controls (296 ± 31 vs. 1,803 ± 134 T cells/μL blood, P < 0.001). Setting two arbitrary limits: patients with a PPARγ expression in T cells higher than 7,000 copies/25 ng mRNA, of whom five of six patients died during the ICU stay, and patients with a T cell count below 100 T cells/μL blood, of whom five of eight patients died, we identified a correlation between sepsis survival and low T cell number, paired with high T cell-specific PPARγ expression. Among all 18 sepsis patients, four fulfilled the criteria for both arbitrary settings and all four of these patients subsequently died. We suggest that both high PPARγ expression in T cells and low absolute T cell number in blood of septic patients may have the potential as a new prognostic marker for a poor sepsis outcome.

Longitudinal Profiles of Metabolism and Bioenergetics Associated with Innate Immune Hormonal Inflammatory Responses and Amino-Acid Kinetics in Severe Sepsis and Systemic Inflammatory Response Syndrome in Children

BACKGROUND

Experimental data indicate that sepsis influences the mitochondrial function and metabolism. We aim to investigate longitudinal bioenergetic, metabolic, hormonal, amino-acid, and innate immunity changes in children with sepsis.

METHODS

Sixty-eight children (sepsis, 18; systemic inflammatory response syndrome [SIRS], 23; healthy controls, 27) were enrolled. Plasma amino acids were determined by high-performance liquid chromatography (HPLC); flow-cytometry expressed as mean fluorescence intensity (MFI) of heat shock protein (HSP) levels from monocytes (m) and neutrophils (n); resistin, adiponectin, and extracellular (e) HSPs evaluated by ELISA; ATP levels in white blood cells by luciferase luminescent assay; lipid peroxidation products (TBARS) by colorimetric test; nitrite and nitrate levels by chemiluminescent assay; biliverdin reductase (BVR) activity by enzymatic assay; and energy-expenditure (EE) by E-COVX.

RESULTS

Resistin, eHSP72, eHSP90α, and nitrate were longitudinally higher in sepsis compared with SIRS (p<0.05); mHSP72, nHSP72, VO₂ , VCO₂ , EE, and metabolic pattern were repressed in sepsis compared with SIRS (p<0.05). Septic patients had lower ATP and TBARS compared with controls on day 1, lower ATP compared with SIRS on day 3 (p<0.05), but higher levels of BVR activity. Sepsis exhibited higher phenylalanine levels on day 1, serine on day 3; lower glutamine concentrations on days 3 and 5 (p<0.05). Resistin, inversely related to ATP, was independently associated with sepsis, along with mHSP72 and eHSP90α (p<0.05); TBARS and VO₂ were independently associated with organ failure (p<0.05)). Septic nonsurvivors had malnutrition, persistently repressed metabolism, mHSP72, and induced resistin and adiponectin (p<0.05).

CONCLUSIONS

A pattern of early longitudinal induction of metabolic-hormones and eHSP72/HSP90α, repression of bioenergetics and innate immunity, hypo-metabolism, and amino-acid kinetics changes discriminate sepsis from SIRS; malnutrition, hypo-metabolism, and persistently increased resistin and adiponectin are associated with poor outcome.

Similar Metabolic, Innate Immunity, and Adipokine Profiles in Adult and Pediatric Sepsis Versus Systemic Inflammatory Response Syndrome-A Pilot Study

OBJECTIVES

To examine whether the septic profiles of heat shock protein 72, heat shock protein 90α, resistin, adiponectin, oxygen consumption, CO2 production, energy expenditure, and metabolic pattern, along with illness severity, nutritional, and inflammatory indices, differ between adult and pediatric patients compared with systemic inflammatory response syndrome and healthy controls. To evaluate whether these biomolecules may discriminate sepsis from systemic inflammatory response syndrome in adult and pediatric patients.

DESIGN

Prospective cohort study.

SETTING

University ICU and PICU.

PATIENTS

Seventy-eight adults (sepsis/23; systemic inflammatory response syndrome/23; healthy controls/33), 67 children (sepsis/18; systemic inflammatory response syndrome/23; controls/27), mechanically ventilated.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Flow cytometry determined mean fluorescence intensity for monocyte or neutrophil heat shock protein expression. Resistin, adiponectin, and extracellular heat shock proteins were measured using enzyme-linked immunosorbent assay; energy expenditure by E-COVX (GE Healthcare). Genomic DNA was extracted with PureLink Genomic DNA kit (Invitrogen, Carlsbad, CA) to detect heat shock protein 72 single nucleotide polymorphisms. Similarly, in adult and pediatric patients, Acute Physiology and Chronic Evaluation-II/Acute Physiology and Pediatric Risk of Mortality-III, Simplified Acute Physiology Score-III, C-reactive protein, lactate, and resistin were higher and myocardial contractility, monocyte heat shock protein 72, oxygen consumption, CO2 production, energy expenditure, metabolic pattern, glucose, and albumin lower in sepsis compared with systemic inflammatory response syndrome or controls (p < 0.05). For discriminating sepsis from systemic inflammatory response syndrome, resistin, extracellular heat shock protein 90α, and lactate achieved a receiver operating characteristic curve greater than 0.80 in children and greater than 0.75 in adults (p < 0.05). In both, adults and children, genotype heat shock protein 72 analysis did not disclose any diagnosis or mortality group differences regarding either rs6457452 or rs1061581 haplotypes.

CONCLUSIONS

Sepsis presents with similar profiles in adult and pediatric patients, characterized by enhanced inflammatory hormonal response and by repressed innate immunity, metabolism, and myocardial contractility. These features early distinguish sepsis from systemic inflammatory response syndrome across all age groups.

Association between adipokines and critical illness outcomes

BACKGROUND

Adipose tissue is an endocrine organ that plays a critical role in immunity and metabolism by virtue of a large number of hormones and cytokines, collectively termed adipokines. Dysregulation of adipokines has been linked to the pathogenesis of multiple diseases, but some questions have arisen concerning the value of adipokines in critical illness setting. The objective of this review was to evaluate the associations between blood adipokines and critical illness outcomes.

METHODS

PubMed, CINAHL, Scopus, and the Cochrane Library databases were searched from inception through July 2016 without language restriction. Studies reporting the associations of adipokines, leptin, adiponectin, resistin, and/or visfatin with critical illness outcomes mortality, organ dysfunction, and/or inflammation were included.

RESULTS

A total of 38 articles were selected according to the inclusion/exclusion criteria of the study. Significant alterations of circulating adipokines have been reported in critically ill patients, some of which were indicative of patient outcomes. The associations of leptin and adiponectin with critical illness outcomes were not conclusive in that blood levels of both adipokines did not always correlate with the illness severity scores or risks of organ failure and mortality. By contrast, studies consistently reported striking increase of blood resistin and visfatin, independently of the critical illness etiology. More interestingly, increased levels of these adipokines were systematically associated with severe inflammation, and high incidence of organ failure and mortality.

CONCLUSIONS

There is strong evidence to indicate that increased levels of blood resistin and visfatin are associated with poor outcomes of critically ill patients, including higher inflammation, and greater risk of organ dysfunction and mortality.

LEVEL OF EVIDENCE

Systematic review, level III.

Kinetics of circulating fetuin-A may predict mortality independently from adiponectin, high molecular weight adiponectin and prognostic factors in critically ill patients with sepsis: A prospective study

PURPOSE

Fetuin-A and adiponectin, major hepatokine and adipokine respectively, have been implicated in systematic inflammation. Our aim was to jointly investigate whether kinetics of circulating fetuin-A, adiponectin and its isoform HMWA predict 28-day mortality in sepsis.

MATERIALS AND METHODS

In a prospective study, serum fetuin-A, adiponectin and HMWA were determined in 102 ICU patients fulfilling the diagnostic criteria of SEPSIS-3, at enrollment and one week after, and in 102 healthy controls matched on age and gender.

RESULTS

Serum fetuin-A was significantly lower in septic patients than controls (p<0.001). Among septic patients, those with septic shock and nonsurvivors presented lower fetuin-A, but higher adiponectin and HMWA compared to patients with sepsis and survivors respectively, both at baseline and day 7 (p<0.001). Fetuin-A exhibited negative correlations with APACHE II, CRP, procalcitonin, adiponectin and IL-6 but a positive one with albumin. Reduced fetuin-A as well as lower serum kinetics of fetuin-A (HR: 0.55, 95% C.I. 0.34-0.91, p=0.02), adiponectin but not HMWA were independently associated with 28-day mortality adjusting for age, gender, BMI, APACHE II, septic shock and laboratory biomarkers.

CONCLUSIONS

Circulating fetuin-A kinetics may be a prognostic biomarker in septic patients. More research is essential to elucidate fetuin-A's ontological role in sepsis pathophysiology.

Obesity enhances sepsis-induced liver inflammation and injury in mice

OBJECTIVE

How obesity affects the response to sepsis was not completely understood. It was hypothesized that obesity alters adipose and hepatic tissue inflammation through signal transducer and activator of transcription (STAT3) activation.

METHODS

Male C57BL/6 mice at 6 weeks of age were randomized to a high-fat diet (60% kcal fat) or normal diet (16% kcal fat) for 6 to 7 weeks. Sepsis was then induced by cecal ligation and puncture, and animals were monitored for survival or sacrificed and tissue collected.

RESULTS

High-fat diet-fed mice gained more weight, had increased fat mass, and were glucose intolerant compared with normal diet-fed mice. Obesity increased hepatic neutrophil infiltration and injury after sepsis. Mice with obesity had higher plasma leptin levels compared with mice without obesity. Adipose tissue expression of adiponectin receptor 2, tumor necrosis factor-α, and peroxisome proliferator activated receptor gamma was altered during sepsis and affected by obesity, but the greatest change in adipose tissue expression was in leptin. Septic mice with obesity had lower plasma interleukin-17a, interleukin-23, and tumor necrosis factor-α levels and increased hepatic STAT3 and activator protein-1 activation compared with septic mice without obesity. Ultimately, mice with obesity had a lower probability of survival following sepsis.

CONCLUSIONS

Mice with obesity are more susceptible to sepsis and have higher mortality, in part, through activation of the STAT3 signaling pathway and through activator protein-1 activation.

Alterations of dendritic cells in sepsis: featured role in immunoparalysis

Sepsis, the leading cause of mortality in intensive care unit, is characterized by hyperinflammatory response in the early stage and followed by a period of immunosuppression. This immune disorder is believed to be the potent factor that is tightly associated with high mortality in sepsis. Dendritic cells (DCs) serve as professional antigen-presenting cells that play a vital role in immune response by activating T lymphocytes. During the progression of sepsis, DCs have been reported to take part in the aberrant immune response and be necessary for survival. Therefore, a better understanding of the DCs pathology will be undoubtedly beneficial for resolving the problems occurring in sepsis. This review discusses effects of sepsis on DCs number and function, including surface molecules expression, cytokines secretion, and T cell activation, and the underlying mechanism as well as some potential therapeutic strategies.

Early and dynamic changes in gene expression in septic shock patients: a genome-wide approach

Background

As early and appropriate care of severe septic patients is associated with better outcome, understanding of the very first events in the disease process is needed. Pan-genomic analyses offer an interesting opportunity to study global genomic response within the very first hours after sepsis.

The objective of this study was to investigate the systemic genomic response in severe intensive care unit (ICU) patients and determine whether patterns of gene expression could be associated with clinical severity evaluated by the severity score.

Methods

Twenty-eight ICU patients were enrolled at the onset of septic shock. Blood samples were collected within 30 min and 24 and 48 h after shock and genomic response was evaluated using microarrays. The genome-wide expression pattern of blood leukocytes was sequentially compared to healthy volunteers and after stratification based on Simplified Acute Physiology Score II (SAPSII) score to identify potential mechanisms of dysregulation.

Results

Septic shock induces a global reprogramming of the whole leukocyte transcriptome affecting multiple functions and pathways (>71% of the whole genome was modified). Most altered pathways were not significantly different between SAPSII-high and SAPSII-low groups of patients. However, the magnitude and the duration of these alterations were different between these two groups. Importantly, we observed that the more severe patients did not exhibit the strongest modulation. This indicates that some regulation mechanisms leading to recovery seem to take place at the early stage.

Conclusions

In conclusion, both pro- and anti-inflammatory processes, measured at the transcriptomic level, are induced within the very first hours after septic shock. Interestingly, the more severe patients did not exhibit the strongest modulation. This highlights that not only the responses mechanisms by themselves but mainly their early and appropriate regulation are crucial for patient recovery. This reinforces the idea that an immediate and tailored aggressive care of patients, aimed at restoring an appropriately regulated immune response, may have a beneficial impact on the outcome.

Electronic supplementary material

The online version of this article (doi:10.1186/s40635-014-0020-3) contains supplementary material, which is available to authorized users.

Statins, fibrates, thiazolidinediones and resveratrol as adjunctive therapies in sepsis: could mitochondria be a common target?

Through their pleiotropic actions, statins, fibrates, thiazolidinediones and resveratrol can target multiple mechanisms involved in sepsis. Their actions on mitochondrial function are of interest in a pathological state where bioenergetic failure may play a key role in the development of organ dysfunction. We review these four drug groups as potential adjunctive therapies in sepsis with a particular focus upon mitochondria. Systematic review of clinical and experimental trials was done with a literature search using the PubMed database. Search terms included statins, fibrates, thiazolidinediones, resveratrol, mitochondria, sepsis, peroxisome proliferator-activated receptors, inflammation, oxidative stress and organ dysfunction. With the exception of statins, most of the compelling evidence for the use of these agents in sepsis comes from the experimental literature. The agents all exert anti-inflammatory and anti-oxidant properties, plus protective effects against mitochondrial dysfunction and stimulation of mitochondrial biogenesis. Improved outcomes (organ dysfunction, survival) have been reported in a variety of sepsis models. Notably, positive outcome effects were more commonly seen when the agents were given as pre- rather than post-treatment of sepsis. Statins, fibrates, thiazolidinediones and resveratrol prevent sepsis-induced injury to organs and organelles with outcome improvements. Their effects on mitochondrial function may be integral in offering this protection. Definitive clinical trials are needed to evaluate their utility in septic patients or those at high risk of developing sepsis.

Random measurements of adiponectin and IL-6 may not be indicative of the 24-h profile in critically ill patients

CONTEXT

The anti-inflammatory role of adiponectin has prompted interest in a potential role in acute inflammatory conditions associated with critical illness. It is unclear whether a random adiponectin measurement adequately reflects the 24-h profile in critically ill patients.

OBJECTIVE

To assess the temporal profile of total and high molecular weight (HMW) adiponectin and interleukin-6 (IL-6) in 15 critically ill patients.

DESIGN

A prospective, observational study.

SETTING

Level II intensive care unit in a metropolitan hospital.

PATIENTS OR OTHER PARTICIPANTS

Fifteen critically ill patients expected to stay in the ICU for longer than 48 h were eligible for enrolment.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Serial, hourly measurements of total and HMW adiponectin and IL-6.

RESULTS

Over a 24-h period, total and HMW adiponectin display considerable within-patient variability (coefficient of variation 34% and 87% respectively) and show no trend over time. Averaging 2 or 3 continuous measures reduced within-patient variability of both total and HMW adiponectin by up to 50% compared to one measure. There was a negative correlation between serum glucose and adiponectin (total P = 0·016, HMW P = 0·039). No relationship existed between adiponectin and IL-6 (total P = 0·62, HMW P = 0·35).

CONCLUSIONS

Marked within-patient, hourly variability in total and HMW adiponectin is evident in critically ill patients. A random measurement may not be reflective of the 24-h profile in these patients. A negative correlation exists between adiponectin and blood glucose levels and a positive correlation between adiponectin and oxygen saturation. No clear relationship exists between adiponectin and IL-6.

Pioglitazone reduces inflammation through inhibition of NF-κB in polymicrobial sepsis

The insulin sensitizing thiazolidinedione drugs, rosiglitazone and pioglitazone are specific peroxisome proliferator-activated receptor-gamma agonists and reduce pro-inflammatory responses in patients with type 2 diabetes and coronary artery disease, and may be beneficial in sepsis. Sepsis was induced in 8-10-wk-old C57BL/6 mice by cecal ligation and puncture (CLP) with a 22 -g double puncture technique. Mice received an i.p. injection of vehicle (DMSO:PBS) or pioglitazone (20 mg/kg) at 1 h and 6 h after CLP, and were sacrificed at various time points. In sepsis, vehicle-treated mice had hypoglycemia, increased lung injury and increased lung neutrophil infiltration. Pro-inflammatory plasma cytokines were increased, but the plasma adipokine, adiponectin, was decreased in vehicle-treated septic mice. This corresponded with inhibitor κB (IκBα) protein degradation and an increase in NF-κB activity in lung. Pioglitazone treatment improved plasma Glc and adiponectin levels, and decreased pro-inflammatory cytokines. Lung IκBα protein expression increased and corresponded with a decrease in NF-κB activity in the lung from pioglitazone-treated mice. Pioglitazone reduces the inflammatory response in polymicrobial sepsis in part through inhibition of NF-κB and may be a novel therapy in sepsis.

Immune aspects of sepsis and hope for new therapeutics

Marked alterations of the innate and adaptive immune response follow invasive infection and generalized inflammatory states. If left unchecked, this state of immune dysregulation contributes to a myriad of maladaptive cellular responses that culminate in multiple organ dysfunction, septic shock, and lethality. The molecular details of the cell-signaling networks that underlie the pathophysiology of systemic inflammation and sepsis are now increasingly well understood. While a vigorous and effective immune response to invasive pathogens is essential for microbial clearance and host survival, nonresolving, generalized inflammation can induce diffuse endovascular damage, increased capillary permeability, coagulopathy, and widespread tissue damage. Current evidence indicates that a state of relative immune suppression often accompanies sepsis and might provide novel therapeutic options in some patients. An expanding number of potential therapeutic options are now in clinical development to reestablish control and promote resolution over sepsis-induced systemic inflammation and organ dysfunction.

Serial changes in adiponectin and resistin in critically ill patients with sepsis: associations with sepsis phase, severity, and circulating cytokine levels

PURPOSE

The aim of the present study was to describe the variation in adiponectin and resistin levels, 2 adipokines with opposing effects on metabolism, in mechanically ventilated patients with sepsis and their relationships to disease severity and cytokine levels.

MATERIALS AND METHODS

An observational prospective study was conducted in a secondary/tertiary unit. Forty-one mechanically ventilated patients diagnosed as having sepsis were included in the study. The Acute Physiology and Chronic Health Evaluation II and Sequential Organ Failure Assessment scores were estimated. Adiponectin, resistin, and cytokines were measured upon sepsis diagnosis and every 3 to 4 days thereafter until day 30. Adiponectin and resistin were also measured in 40 controls.

RESULTS

The patients had higher adiponectin (10.9 ± 6.1 μg/mL vs 6.0 ± 2.9 μg/mL, P < .001) and resistin (24.7 ng/mL vs 3.8 ng/mL, P < .001) levels compared with the controls. Adiponectin increased and resistin decreased significantly over time in the entire cohort. Resistin correlated with Acute Physiology and Chronic Health Evaluation II, Sequential Organ Failure Assessment, interleukin (IL)-6, IL-8, and IL-10 and was significantly higher in severe sepsis/septic shock compared with sepsis. No correlations between adiponectin and clinical scores were noted.

CONCLUSIONS

Adiponectin and resistin change reciprocally during the course of sepsis. Resistin relates to the severity of sepsis and the degree of inflammatory response. Adiponectin and resistin may play a critical role in the metabolic adaptations observed in sepsis.

Novel biomarker combination improves the diagnosis of serious bacterial infections in Malawian children

Background

High throughput technologies offer insight into disease processes and heightens opportunities for improved diagnostics. Using transcriptomic analyses, we aimed to discover and to evaluate the clinical validity of a combination of reliable and functionally important biomarkers of serious bacterial infection (SBI).

Methods

We identified three previously reported biomarkers of infection (neutrophil gelatinase-associated lipocalin (NGAL), granulysin and resistin) and measured gene expression using quantitative real-time PCR. Protein products related to the three transcripts were measured by immunoassays.

Results

Relative gene expression values of NGAL and resistin were significantly increased, and expression of granulysin significantly decreased in cases compared to controls. Plasma concentrations of NGAL and resistin were significantly increased in children with confirmed SBI compared to children with no detectable bacterial infection (NBI), and to controls (287 versus 128 versus 62 ng/ml and 195 versus 90 versus 18 ng/ml, respectively, p < 0.05). Plasma protein concentrations of NGAL and resistin were significantly increased in non-survivors compared to survivors (306 versus 211 and 214 versus 150 ng/ml, p = 0.02). The respective areas under the curve (AUC) for NGAL, resistin and procalcitonin in predicting SBI were 0.79, 0.80 and 0.86, whilst a combination of NGAL, resistin and procalcitonin achieved an AUC of 0.90.

Conclusions

We have demonstrated a unique combination of diagnostic biomarkers of SBI using transcriptomics, and demonstrated translational concordance with the corresponding protein. The addition of NGAL and resistin protein measurement to procalcitonin significantly improved the diagnosis of SBI.

Arginine decreases peroxisome proliferator-activated receptor-γ activity via c-Jun

We have previously shown in the post ischemic gut that enteral arginine enhanced injury and inflammation via c-Jun/AP-1 and abrogated peroxisome proliferator-activated receptor (PPAR) γ activity. In the current study, we investigated the mechanism by which arginine inhibited PPARγ in vitro in rat small bowel epithelial IEC-6 cells. Arginine repressed PPARγ transcriptional activity in a time and dose-dependent fashion. Furthermore, downregulation of PPARγ by arginine involved phosphorylation of c-Jun that occurred before to changes in PPARγ transcriptional activity. Silencing of c-Jun increased PPARγ beyond that of nonsilenced cells and was not mitigated by arginine. Using a series of blocking studies, we found no relationship between arginine and the ligand-dependent binding site of PPARγ. In conclusion, arginine decreased PPARγ transcriptional activity in small bowel intestinal epithelial cells. These changes are due, in part, to phosphorylation of c-Jun and may explain the deleterious effects of enteral arginine in the post ischemic gut.

The metabolic syndrome in critically ill patients

Metabolic support in intensive care is a rapidly evolving field with new information being gathered almost on a daily basis. In endocrine practice, over the last 20 years, researchers have focussed on a new entity, termed the "metabolic syndrome". This describes the constellation of abnormalities which include central adiposity, insulin resistance and inflammation. All of these predispose the individual to a greater risk of cardiovascular events. Of interest is the observation that some of the metabolic abnormalities in sepsis and multiple organ dysfunction syndrome of critical illness share several common features with that of the metabolic syndrome. In this chapter we describe the features of the metabolic syndrome as is understood in endocrine parlance, the metabolic abnormalities of critical illness and explore the common threads underlying the pathophysiology and the treatment of the two syndromes. The role of adiponectin in the metabolic abnormalities in both the metabolic syndrome and in sepsis are reviewed. The potential role of the pleiotropic effects of statins in the therapy of sepsis is also discussed.

Clinical review: adiponectin biology and its role in inflammation and critical illness

Adiponectin is an adipokine first described just over a decade ago. Produced almost exclusively by adipocytes, adiponectin circulates in high concentrations in human plasma. Research into this hormone has revealed it to have insulin-sensitizing, anti-inflammatory and cardioprotective roles. This review discusses the history, biology and physiological role of adiponectin and explores its role in disease, with specific focus on adiponectin in inflammation and sepsis. It appears that an inverse relationship exists between adiponectin and inflammatory cytokines. Low levels of adiponectin have been found in critically ill patients, although data are limited in human subjects at this stage. The role of adiponectin in systemic inflammation and critical illness is not well defined. Early data suggest that plasma levels of adiponectin are decreased in critical illness. Whether this is a result of the disease process itself or whether patients with lower levels of this hormone are more susceptible to developing a critical illness is not known. This observation of lower adiponectin levels then raises the possibility of therapeutic options to increase circulating adiponectin levels. The various options for modulation of serum adiponectin (recombinant adiponectin, thiazolidinediones) are discussed.

Phosphorylation of extracellular signal-regulated kinase (ERK)-1/2 Is associated with the downregulation of peroxisome proliferator-activated receptor (PPAR)-γ during polymicrobial sepsis

Peroxisome proliferator-activated receptor (PPAR)-γ is a ligand-activated transcription factor and regulates inflammation. Posttranslational modifications regulate the function of PPARγ, potentially affecting inflammation. PPARγ contains a mitogen-activated protein kinase (MAPK) site, and phosphorylation by extracellular signal-regulated kinase (ERK)-1/2 leads to inhibition of PPARγ. This study investigated the kinetics of PPARγ expression and activation in parenchymal and immune cells in sepsis using the MAPK/ERK kinase (MEK)-1 inhibitor, an upstream kinase of ERK1/2. Adult male Sprague Dawley rats were subjected to polymicrobial sepsis by cecal ligation and puncture. Rats received intraperitoneal injection of vehicle or the MEK1 inhibitor PD98059 (5 mg/kg) 30 min before cecal ligation and puncture. Rats were euthanized at 0, 1, 3, 6 and 18 h after cecal ligation and puncture. Control animals used were animals at time 0 h. Lung, plasma and peripheral blood mononuclear cells (PBMCs) were collected for biochemical assays. In vehicle-treated rats, polymicrobial sepsis resulted in significant lung injury. In the lung and PBMCs, nuclear levels of PPARγ were decreased and associated with an increase in phosphorylated PPARγ and phosphorylated ERK1/2 levels. Treatment with the MEK1 inhibitor increased the antiinflammatory plasma adipokine adiponectin, restored PPARγ expression in PBMCs and lung, and decreased lung injury. The inflammatory effects of sepsis cause changes in PPARγ expression and activation, in part, because of phosphorylation of PPARγ by ERK1/2. This phosphorylation can be reversed by ERK1/2 inhibition, thereby improving lung injury.