The tumor necrosis factor alpha -308 G/A polymorphism does not influence inflammation and coagulation response in human endotoxemia

The effects of genotype on inflammatory response in hippocampal progenitor cells: A computational approach

Cell culture models are valuable tools to study biological mechanisms underlying health and disease in a controlled environment. Although their genotype influences their phenotype, subtle genetic variations in cell lines are rarely characterised and taken into account for in vitro studies. To investigate how the genetic makeup of a cell line might affect the cellular response to inflammation, we characterised the single nucleotide variants (SNPs) relevant to inflammation-related genes in an established hippocampal progenitor cell line (HPC0A07/03C) that is frequently used as an in vitro model for hippocampal neurogenesis (HN). SNPs were identified using a genotyping array, and genes associated with chronic inflammatory and neuroinflammatory response gene ontology terms were retrieved using the AmiGO application. SNPs associated with these genes were then extracted from the genotyping dataset, for which a literature search was conducted, yielding relevant research articles for a total of 17 SNPs. Of these variants, 10 were found to potentially affect hippocampal neurogenesis whereby a majority (n=7) is likely to reduce neurogenesis under inflammatory conditions. Taken together, the existing literature seems to suggest that all stages of hippocampal neurogenesis could be negatively affected due to the genetic makeup in HPC0A07/03C cells under inflammation. Additional experiments will be needed to validate these specific findings in a laboratory setting. However, this computational approach already confirms that in vitro studies in general should control for cell lines subtle genetic variations which could mask or exacerbate findings.

Human lipopolysaccharide models provide mechanistic and therapeutic insights into systemic and pulmonary inflammation

Inflammation is a key feature in the pathogenesis of sepsis and acute respiratory distress syndrome (ARDS). Sepsis and ARDS continue to be associated with high mortality. A key contributory factor is the rudimentary understanding of the early events in pulmonary and systemic inflammation in humans, which are difficult to study in clinical practice, as they precede the patient's presentation to medical services. Lipopolysaccharide (LPS), a constituent of the outer membrane of Gram-negative bacteria, is a trigger of inflammation and the dysregulated host response in sepsis. Human LPS models deliver a small quantity of LPS to healthy volunteers, triggering an inflammatory response and providing a window to study early inflammation in humans. This allows biological/mechanistic insights to be made and new therapeutic strategies to be tested in a controlled, reproducible environment from a defined point in time. We review the use of human LPS models, focussing on the underlying mechanistic insights that have been gained by studying the response to intravenous and pulmonary LPS challenge. We discuss variables that may influence the response to LPS before considering factors that should be considered when designing future human LPS studies.

Effects and mechanism of the etanercept on pancreatic encephalopathy

Pancreatic encephalopathy (PE) is a common fatal complication of acute pancreatitis (AP). Proinflammatory cytokines such as tumor necrosis factor (TNF)‑α and interleukin (IL)‑6 are generated during AP, and act synergistically to promote PE and multisystem failure. Caerulein‑induced AP provides a convenient model to explore the role of proinflammatory cytokines in PE. The aim of the present study was to examine the effect of the TNF‑α inhibitor etanercept in PE models and elucidate the regulatory mechanisms. To model PE in vitro, rat hippocampal H19‑7/IGF‑IR neuronal cells were treated with 10 nmol/ml caerulein alone or in combination with etanercept (1, 10 or 100 µmol/ml). To model PE in vivo, rats were injected with 50 µg/kg caerulein alone or combined with 10 mg/kg etanercept. At 6 h after administration, it was noted that etanercept downregulated expression of TNF‑α, IL‑1β and IL‑6 by negatively regulating NF‑κB (a master regulator of cytokine expression) signaling, and prevented the accumulation of reactive oxygen species. Conversely, etanercept promoted the expression of the neurotrophic and anti‑inflammatory hypoxia‑inducible factor 1 α (HIF‑1α). In rat hippocampus, etanercept also reduced the levels of TNF‑α, IL‑1β and IL‑6, upregulated HIF‑1α expression and inhibited the inflammatory response to reduce edema and neural necrosis. Together, these data suggested that etanercept could attenuate caerulein‑induced PE, at least in part via suppression of NF‑κB signaling and alleviation of oxidative stress.

Review: From therapy to experimental model: a hundred years of endotoxin administration to human subjects

This article is a review of studies in which endotoxin has been administered to human subjects for experimental purposes. Data are presented in tabular form so the reader can better appreciate the objectives of individual studies. Although the original intention was to focus on the adverse events associated with these studies, unexpected serious adverse events rarely have been reported.

Association of tumor necrosis factor α -308G/A and interleukin-6 -174G/C gene polymorphism with pneumonia-induced sepsis

PURPOSE

Sepsis is a lethal outcome of the inflammation and coagulation process. Human interleukin (IL)-6 and tumor necrosis factor (TNF) α are well-known inflammation factors closely associated with sepsis. In the present study, we aim to investigate the association of promoter-region polymorphisms IL-6 (-174G/C) rs1800795 and TNF-α (-308G/A) rs1800629 with pneumonia-induced sepsis.

MATERIALS AND METHODS

A total of 277 Chinese patients with severe pneumonia-induced sepsis were recruited into this study. All study participants were admitted to the intensive care unit until discharge or death in the First Affiliated Hospital of Zhengzhou University from July 2010 to July 2014. The patients were classified as severely septic, septic shock, and mortality. Clinical data and demographic information were recorded. TaqMan genotyping was performed to detect single nucleotide polymorphism distribution.

RESULTS

The genotype results demonstrated that carriers of the TNF-α rs1800629 A allele had a 4.28-fold higher risk for septic shock (adjusted odds ratio [OR], 4.28; 95% confidence interval [CI], 2.24-8.18; P < .01) compared with severe sepsis, and carriers of the IL-6 rs1800795 C allele had a 2.42-fold higher risk for septic shock (OR, 2.42; 95% CI, 1.08-5.45; P < .01) compared with severe sepsis. No significant difference of SNP distribution was found between the survivors and the nonsurvivors. After the results were adjusted for age and the outcomes of blood cultures, a multivariate logistic regression analysis showed similar results. Individuals with the TNF-α 308 rs1800629 A allele (adjusted OR, 2.96; 95% CI, 1.30-7.87) or the IL-6 rs1800795 C allele (adjusted OR, 1.87; 95% CI, 1.03-3.61) had a higher prevalence of septic shock. However, these SNP distribution differences were not associated with mortality.

CONCLUSIONS

In intensive care unit patients, the TNF-α -308A allele and the IL-6 rs1800795 allele variants were susceptibility risk factors for septic shock induced by pneumonia.

Human experimental endotoxemia in modeling the pathophysiology, genomics, and therapeutics of innate immunity in complex cardiometabolic diseases

Inflammation is a fundamental feature of several complex cardiometabolic diseases. Indeed, obesity, insulin resistance, metabolic dyslipidemia, and atherosclerosis are all closely linked inflammatory states. Increasing evidence suggests that the infectious, biome-related, or endogenous activation of the innate immune system may contribute to the development of metabolic syndrome and cardiovascular disease. Here, we describe the human experimental endotoxemia model for the specific study of innate immunity in understanding further the pathogenesis of cardiometabolic disease. In a controlled, experimental setting, administration of an intravenous bolus of purified Escherichia coli endotoxin activates innate immunity in healthy human volunteers. During endotoxemia, changes emerge in glucose metabolism, lipoprotein composition, and lipoprotein functions that closely resemble those observed chronically in inflammatory cardiovascular disease risk states. In this review, we describe the transient systemic inflammation and specific metabolic consequences that develop during human endotoxemia. Such a model provides a controlled induction of systemic inflammation, eliminates confounding, undermines reverse causation, and possesses unique potential as a starting point for genomic screening and testing of novel therapeutics for treatment of the inflammatory underpinning of cardiometabolic disease.

Does clinically relevant temperature change miRNA and cytokine expression in whole blood?

Unintentional hypothermia is a well-described risk factor for death and complications after elective and emergency surgery. The molecular mechanisms by which hypothermia exerts its detrimental effects are not well understood. Differences in cytokine production and the overall cell function have been reported under hypothermic conditions. We investigated the effect of a range of clinically relevant temperatures on cytokine production and microRNA (miRNA) expression in a whole-blood model. We found that there was a wide variation in tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-10 production among different subjects, ranging from low to high TNF-α producers. The intersubject variation can also be found on the transcriptional level: high producers had higher upregulation of TNF-α messenger RNA than intermediate and low producers. This variation in TNF-α was reproducible in each individual. Temperature seems to modulate TNF-α production among these different groups. miRNA expression was modulated by temperature. miRNA-181a might control, or be a part of the mechanism which controls, TNF-α production. However, an analysis of whole-leukocyte RNA does not allow the investigation of mechanisms in a specific leukocyte subpopulation such as monocytes, because these changes may be concealed by miRNA expression changes in the other leukocyte subsets. In conclusion, TNF-α, IL-6, and IL-10 production is highly variable among different persons, but temperature affects the expression of miRNAs, which may consequently alter the production of TNF-α.

Genetic polymorphisms in sepsis

The number of genetic polymorphisms shown to play a role in sepsis continues to increase. At the same time, platforms for genetic sequencing and expression analysis are being refined, allowing unprecedented data generation. International databases may soon facilitate synchrony of genotypic and phenotypic data using enormous numbers of septic patients. If this occurs, 2 strategies for investigating polymorphisms in sepsis are likely to gain favor. In the first strategy, sepsis will continue to be viewed as a single entity. High-throughput genetic techniques will be used to evaluate numerous polymorphisms, each with fractional disease responsibility. Nongenetic variables, such as pathogen characteristics, underlying host medical conditions, and type and timing of resuscitation, will be considered cofactors. Using this approach, principal components that predict susceptibility to and outcomes during sepsis are likely to be identified. In the second strategy, sepsis will be divided into subtypes based on the concentration of specific variables. Categories will be based on features like the presence or absence of specific polymorphisms, gram-positive or gram-negative staining of causative organisms, age and comorbid conditions of the host, recent administration of chemotherapeutic agents, and hospital setting (ie, community vs teaching institution). Each category will be used to create homogenous sepsis subgroups for detailed evaluation. This approach will increase the odds of finding single dominant factors responsible for predilection and/or outcome within well-defined groups among those with sepsis. Several elements will be essential for the success of both these strategies. Firstly, databases that are extremely detailed will have to be generated. Secondly, better clinical information technology systems will be needed to facilitate large-scale phenotyping. Thirdly, standardization of protocols will need to take place to ensure uniformity of data sets. If the rapid advances in technology and informatics continue, they may catalyze paradigm shifts with regard to how clinicians address sepsis. Clinicians may change their focus from aggressive uniform treatment strategies to rapid stratification and subcategorization, with subsequent aggressive targeted therapeutic interventions. Advances in technology have the potential to change our primary goal in sepsis from rapid treatment to prevention for those most at risk. The cost savings to the US health care systems from such changes could be substantial.

Outcome prediction in sepsis combined use of genetic polymorphisms - A study in Japanese population

Genetic polymorphisms have recently been found to be related to clinical outcome in septic patients. The present study investigated to evaluate the influence of genetic polymorphisms in Japanese septic patients on clinical outcome and whether use of genetic polymorphisms as predictors would enable more accurate prediction of outcome. Effects of 16 genetic polymorphisms related to pro-inflammatory mediators and conventional demographic/clinical parameters (age, sex, past medical history, and APACHE II score) on ICU mortality as well as disease severity during ICU stay were examined in the septic patients (n=123) admitted to the ICU between October 2001 and November 2007 by multivariable logistic regression analysis. ICU mortality was significantly associated with TNF -308GA, IL1β -31CT/TT, and APACHE II score. Receiver-operating characteristics (ROC) analysis demonstrated that, compared with APACHE II score alone (ROC-AUC=0.68), use of APACHE II score and two genetic parameters (TNF -308 and IL1β -31) enabled more accurate prediction of ICU mortality (ROC-AUC=0.80). Significant association of two genetic polymorphisms, TNF -308 and IL1β -31, with ICU mortality was observed in septic patients. In addition, combined use of these genetic parameters with APACHE II score may enable more accurate prediction of outcome in septic patients.

Genetic polymorphisms and posttraumatic complications

Major trauma is the leading cause of death in young adults. Despite advances in prehospital system and treatment in hospital, mortality rates have not improved significantly over the past decades. Victims of severe injuries who survive the initial hours have great risk for additional life-threatening complicaitons, including uncontrollable infection (sepsis) and multiple organ dysfunction syndrome (MODS). Single nucleotide polymorphisms (SNPs) have been shown to affect susceptibility to the course of numerous diseases. Accumulating evidence suggests that genetic backgrounds also play important roles in posttraumatic complications. Genetic polymorphisms may become powerful biomarkers for diagnosis and prognosis of trauma-induced complications. Recent advances in studies on associations between genetic polymorphisms and sepsis or MODS have led to better understanding of posttraumatic complications. Here we summarise recent findings on genetic variations in molecules of the innate immune system and other systems as well as their connection with susceptibility to posttraumatic complications.

Blood cytokines as biomarkers of in vivo toxicity in preclinical safety assessment: considerations for their use

In the drive to develop drugs with well-characterized and clinically monitorable safety profiles, there is incentive to expand the repertoire of safety biomarkers for toxicities without routine markers or premonitory detection. Biomarkers in blood are pursued because of specimen accessibility, opportunity for serial monitoring, quantitative measurement, and the availability of assay platforms. Cytokines, chemokines, and growth factors (here referred to collectively as cytokines) show robust modulation in proximal events of inflammation, immune response, and repair. These are key general processes in many toxicities; therefore, cytokines are commonly identified during biomarker discovery studies. In addition, multiplexed cytokine immunoassays are easily applied to biomarker discovery and routine toxicity studies to measure blood cytokines. However, cytokines pose several challenges as safety biomarkers because of a short serum half-life; low to undetectable baseline levels; lack of tissue-specific or toxicity-specific expression; complexities related to cytokine expression with multiorgan involvement; and species, strain, and interindividual differences. Additional challenges to their application are caused by analytical, methodological, and study design-related variables. A final consideration is the strength of the relationship between changes in cytokine levels and the development of phenotypic or functional manifestations of toxicity. These factors should inform the integrated judgment-based qualification of novel biomarkers in preclinical, and potentially clinical, risk assessment. The dearth of robust, predictive cytokine biomarkers for specific toxicities is an indication of the significant complexity of these challenges. This review will consider the current state of the science and recommendations for appropriate application of cytokines in preclinical safety assessment.

Tumor necrosis factor alpha gene variants do not display allelic imbalance in circulating myeloid cells

Carriage of the TNF -308 A allele (rs1800629 A) has been associated with increased serum TNF-alpha levels, the development of sepsis syndrome, and fatal outcome, in severely traumatized patients (Menges et al., 2008 [1]). Herein, we analysed the putative allelic imbalance of TNF-alpha release from myeloid cells. Circulating peripheral blood cells from healthy human blood donors (n=104) and monocyte-derived macrophages (n=158) were analysed for their ex vivo capacity of TNF-alpha expression. Our findings indicate that carriage of the TNF -308 A allele is not associated with high TNF-alpha expression in circulating human leucocytes and monocyte-derived macrophages. Other cellular sources, e.g. tissue-resident cells like mast cells and/or tissue specific macrophages might be the cellular source of high TNF-alpha serum levels shortly after trauma.

Tumor necrosis factor gene variation and the risk of mortality after burn injury: a cohort study

Infection risk and mortality after burn trauma are primarily determined by patient age, burn size and depth, and associated inhalation injury. Whether genetic differences contribute to otherwise unexpected variability in outcomes is unknown. We sought to determine whether there was an association between genetic variation in inflammation-related genes and outcomes after burn trauma. We evaluated patients with burns >or=15% TBSA at a single regional burn center from October 2003 to December 2005. Blood was collected on admission and DNA genotyping was performed. We genotyped single nucleotide polymorphism (SNPs) in toll-like receptor 4 (TLR4) A896G, tumor necrosis factor alpha (TNF-alpha) G-308A, Interleukin-6 (IL-6) G-174C, interleukin-1beta (IL-1beta) T-31C, and cluster of differentiation marker 14 (CD14) C-159T. We compared SNP genotypes between survivors and nonsurvivors by chi analysis and logistic regression. Sixty-nine subjects with a median age of 38 years and mean TBSA of 34% were enrolled. The case fatality was 17%. Septic shock developed in 7 (10%) patients. After adjustment for age, percent full-thickness burns, and inhalation injury, carriage of the TNF-alpha -308 variant allele was associated with increased risk of mortality (OR 10.7, 95% CI = 1.2-95.5, P = .034). None of the other SNPs evaluated were associated with mortality. Mortality after burn trauma is primarily determined by clinical factors, but the TNF-alpha -308 A allele seems to contribute to an increased mortality risk.

Effects of the pan-selectin antagonist bimosiamose (TBC1269) in experimental human endotoxemia

Selectins mediate the adhesion of leukocytes to activated endothelial cells and activated platelets. In addition to these cell-to-cell interactions, they influence the fibrin content and size of venous thrombi in different animal models. However, the exact role of selectins in human endotoxemia still remains unclear. We aimed to investigate the effect of selectin inhibition in lipopolysaccharide (LPS)-induced tissue factor (TF)-dependent activation of coagulation in a well-standardized model of human endotoxemia. To explore whether selectin blockade attenuates LPS-induced coagulation in humans, we performed a randomized, double-bind placebo-controlled crossover trial in 16 healthy male volunteers. All subjects received 2 ng/kg of LPS and, 10 min thereafter, a 15-min infusion of either 30 mg/kg of the pan-selectin antagonist bimosiamose or equal volumes of placebo in random order, with a washout period of 6 weeks between both periods. Treatment with bimosiamose had no significant effect on LPS-induced TF expression, as quantified by TF mRNA levels, or on LPS-induced coagulation response, reflected by increases in plasma thrombin-antithrombin (TAT) complexes and prothrombin fragment (F1 + 2) levels. Furthermore, bimosiamose did not affect the LPS-dependent changes in leukocyte subpopulations or the increase in platelet-leukocyte aggregates, as determined in the level of CD41+ monocytes. Finally, neither the LPS-induced release of tumor necrosis factor, interleukin 6, leukocyte expression of CD11b, nor intercellular adhesion molecule 1 were affected by administration of bimosiamose. The pan-selectin antagonist bimosiamose does not attenuate TF-triggered coagulation or inflammation in human endotoxemia. This indicates a minor influence of this selectin antagonist in this model. In addition, infusion of bimosiamose was safe and well tolerated in human endotoxemia.

Characterization of tumour necrosis factor-alpha genetic variants and mRNA expression in patients with severe sepsis

Tumour necrosis factor-alpha (TNFalpha) has been implicated in the pathogenicity of severe sepsis by both genetic association studies and animal models. Conflicting functional data have emerged in relation to genetic variants and TNFalpha protein production. Therefore, we assessed the functionality of TNFalpha genetic variants in terms of mRNA production and their potential influence on outcome in the setting of severe sepsis. Sixty-two Irish Caucasian patients presenting with severe sepsis were recruited and TNFalpha mRNA and protein levels were quantified. Patient DNA was analysed for the presence of common promoter polymorphisms and haplotypes were inferred. An A allele at position -863 was associated with more TNFalpha mRNA on day 1 compared to C homozygotes (P = 0.037). There was a trend for G homozygotes at position -308 to produce more TNFalpha mRNA on day 1 than those carrying an A allele (P = 0.059). The presence of an A allele at -863 was associated with greater levels of TNFalpha mRNA in comparison with patients carrying the A allele at -308 on day 1 (P = 0.02). Patients homozygous for the A allele at position -308 had a higher mortality than those carrying the G allele (P = 0.01). Our data are consistent with recent reports suggesting that a deficient proinflammatory response may be harmful in human sepsis. This deficient inflammatory response may be mediated in part by polymorphisms in the TNFalpha promoter.