Sepsis-induced Changes Research Articles

Sequential Actions of SIRT1-RELB-SIRT3 Coordinate Nuclear-Mitochondrial Communication during Immunometabolic Adaptation to Acute Inflammation and Sepsis

We reported that NAD(+)-dependent SIRT1, RELB, and SIRT6 nuclear proteins in monocytes regulate a switch from the glycolysis-dependent acute inflammatory response to fatty acid oxidation-dependent sepsis adaptation. We also found that disrupting SIRT1 activity during adaptation restores immunometabolic homeostasis and rescues septic mice from death. Here, we show that nuclear SIRT1 guides RELB to differentially induce SIRT3 expression and also increases mitochondrial biogenesis, which alters bioenergetics during sepsis adaptation. We constructed this concept using TLR4-stimulated THP1 human promonocytes, a model that mimics the initiation and adaptation stages of sepsis. Following increased expression, mitochondrial SIRT3 deacetylase activates the rate-limiting tricarboxylic acid cycle (TCA) isocitrate dehydrogenase 2 and superoxide dismutase 2, concomitant with increases in citrate synthase activity. Mitochondrial oxygen consumption rate increases early and decreases during adaptation, parallel with modifications to membrane depolarization, ATP generation, and production of mitochondrial superoxide and whole cell hydrogen peroxide. Evidence of SIRT1-RELB induction of mitochondrial biogenesis included increases in mitochondrial mass, mitochondrial-to-nuclear DNA ratios, and both nuclear and mitochondrial encoded proteins. We confirmed the SIRT-RELB-SIRT3 adaptation link to mitochondrial bioenergetics in both TLR4-stimulated normal and sepsis-adapted human blood monocytes and mouse splenocytes. We also found that SIRT1 inhibition ex vivo reversed the sepsis-induced changes in bioenergetics.

EMF-116 Platelet Mitochondrial Function in Early Severe Sepsis

The prognostic value of lactate in sepsis is well established, but evolving literature suggests that lactate elevation does not result solely from tissue hypoperfusion, but can also arise following sepsis-induced changes in aerobic metabolism, sometimes referred to as cytopathic hypoxia. Recent advances allow for the measurement of mitochondrial function in peripherally available cells such as platelets, and the degree of mitochondrial dysfunction from multiple cell lines is associated with mortality in sepsis. However, it remains unclear if these changes are present on emergency department (ED) presentation, and if the degree of dysfunction is associated with metabolic changes. We sought to determine the association between platelet mitochondrial function as measured by high resolution respirometry and 1) lactate and pyruvate levels and 2) severity of illness as measured by the Sequential Organ Failure Assessment (SOFA) score. Prospective observational cohort of ED patients presenting to a single, urban, tertiary care ED from November 2013 to present. Abbreviated inclusion criteria were age >17, 2 or more SIRS criteria, hypotension despite fluid resuscitation, and confirmed or suspected infection; exclusion criteria include established do not resuscitate order, transfer with resuscitation in progress, and inability to obtain informed consent. Blood was drawn and immediately processed to yield a platelet rich plasma which was placed in an O2k Oxygraph (Oroboros Instruments, Austria). Routine respiration rate was determined by measuring the rate of oxygen consumption in a chamber with a fixed volume of oxygen. Leak and oxidative phosphorylation (oxphos) rates were determined following serial additions of oligomycin and FCCP. Residual non-mitrochondrial oxygen consumption following the addition of rotenone and antimycin A was subtracted from these values, and all values were normalized to cell count. SOFA score, lactate and pyruvate were measured at enrollment. L/P ratio was calculated as the quotient of lactate/pyruvate. Descriptive statistics and simple linear regression were used to determine the association between mitochondrial measurements and lactate and pyruvate measurements, as well as SOFA score. All tests were two-sided and P values of <.05 were considered significant. Eight patients were enrolled to date. Median SOFA score was 7 (IQR 3.5, 9.5). Initial median lactate and pyruvate levels were 1.6 mmol/L (IQR 0.7, 3.2) and 0.09 mmol/L (IQR 0.04, 0.10); while median L/P ratio was 23 (IQR 16, 39). There were significant associations between routine and leak respiration and lactate value (P=.006 and .01), and a trend towards a linear association between routine, leak, and oxphos rates and SOFA score (P=.1, .36, and .12). Similar trends were not observed with pyruvate or L/P ratios. In the first study of platelet mitochondrial function in ED patients with sepsis to date, there is a suggestion of associations between several measures of mitochondrial function and both severity of illness and lactate levels, supportive of the hypothesis that elevated lactate may be partially due to changes in mitochondrial function. If validated in an ongoing study of a larger cohort of patients, these data suggest that novel therapeutics targeting mitochondrial function deserve further clinical investigation.

Sepsis-induced changes in amino acid transporters and leucine signaling via mTOR in skeletal muscle

The present study tested the hypothesis that sepsis-induced leucine (Leu) resistance in skeletal muscle is associated with a down-regulation of amino acid transporters important in regulating Leu flux or an impairment in the formation of the Leu-sensitive mTOR-Ragulator complex. Sepsis in adult male rats decreased basal protein synthesis in gastrocnemius, associated with a reduction in mTOR activation as indicated by decreased 4E-BP1 and S6K1 phosphorylation. The ability of oral Leu to increase protein synthesis and mTOR kinase after 1 h was largely prevented in sepsis. Sepsis increased CAT1, LAT2 and SNAT2 mRNA content two- to fourfold, but only the protein content for CAT1 (20 % decrease) differed significantly. Conversely, sepsis decreased the proton-assisted amino acid transporter (PAT)-2 mRNA by 60 %, but without a coordinate change in PAT2 protein. There was no sepsis or Leu effect on the protein content for RagA-D, LAMTOR-1 and -2, raptor, Rheb or mTOR in muscle. The binding of mTOR, PRAS40 and RagC to raptor did not differ for control and septic muscle in the basal condition; however, the Leu-induced decrease in PRAS40·raptor and increase in RagC·raptor seen in control muscle was absent in sepsis. The intracellular Leu concentration was increased in septic muscle, compared to basal control conditions, and oral Leu further increased the intracellular Leu concentration similarly in both control and septic rats. Hence, while alterations in select amino acid transporters are not associated with development of sepsis-induced Leu resistance, the Leu-stimulated binding of raptor with RagC and the recruitment of mTOR/raptor to the endosome-lysosomal compartment may partially explain the inability of Leu to fully activate mTOR and muscle protein synthesis.

Disruption of genes encoding eIF4E binding proteins-1 and -2 does not alter basal or sepsis-induced changes in skeletal muscle protein synthesis in male or female mice.

Sepsis decreases skeletal muscle protein synthesis in part by impairing mTOR activity and the subsequent phosphorylation of 4E-BP1 and S6K1 thereby controlling translation initiation; however, the relative importance of changes in these two downstream substrates is unknown. The role of 4E-BP1 (and -BP2) in regulating muscle protein synthesis was assessed in wild-type (WT) and 4E-BP1/BP2 double knockout (DKO) male mice under basal conditions and in response to sepsis. At 12 months of age, body weight, lean body mass and energy expenditure did not differ between WT and DKO mice. Moreover, in vivo rates of protein synthesis in gastrocnemius, heart and liver did not differ between DKO and WT mice. Sepsis decreased skeletal muscle protein synthesis and S6K1 phosphorylation in WT and DKO male mice to a similar extent. Sepsis only decreased 4E-BP1 phosphorylation in WT mice as no 4E-BP1/BP2 protein was detected in muscle from DKO mice. Sepsis decreased the binding of eIF4G to eIF4E in WT mice; however, eIF4E•eIF4G binding was not altered in DKO mice under either basal or septic conditions. A comparable sepsis-induced increase in eIF4B phosphorylation was seen in both WT and DKO mice. eEF2 phosphorylation was similarly increased in muscle from WT septic mice and both control and septic DKO mice, compared to WT control values. The sepsis-induced increase in muscle MuRF1 and atrogin-1 (markers of proteolysis) as well as TNFα and IL-6 (inflammatory cytokines) mRNA was greater in DKO than WT mice. The sepsis-induced decrease in myocardial and hepatic protein synthesis did not differ between WT and DKO mice. These data suggest overall basal protein balance and synthesis is maintained in muscle of mice lacking both 4E-BP1/BP2 and that sepsis-induced changes in mTOR signaling may be mediated by a down-stream mechanism independent of 4E-BP1 phosphorylation and eIF4E•eIF4G binding.

Apolipoprotein A-I mimetic peptide 4F attenuates kidney injury, heart injury, and endothelial dysfunction in sepsis.

Kidney injury, heart injury, and cytokine-induced vascular hyperpermeability are associated with high rates of morbidity and mortality in sepsis. Although the mechanism remains unknown, apolipoprotein A-I (apoA-I) mimetic peptide 4F reduces inflammation and protects HDL levels, which are reduced in sepsis. We hypothesized that 4F also protects kidneys and hearts in a rat model of cecal ligation and puncture (CLP). We divided Wistar rats into groups: sham-operated (control), CLP, and CLP+4F (10 mg/kg body wt ip, 6 h after CLP). At 24 h post-CLP, we evaluated cardiac function, mean arterial pressure (MAP), heart rate (HR), baroreflex sensitivity, total cholesterol, LDL, HDL, serum cytokines, and inulin clearance. We performed immunoblotting for protein regulators of vascular permeability (Slit2 and Robo4) and endothelial nitric oxide synthase (eNOS) in kidney tissue. We evaluated heart mitochondria with electron microscopy. Although there was no difference in MAP, the HR was significantly higher in CLP rats than in control and CLP+4F rats. In CLP+4F rats, baroreflex sensitivity and cardiac function were completely protected from the effects of CLP, as was glomerular filtration; heart mitochondria morphology was improved; sepsis-induced changes in serum cholesterol, LDL, HDL, and apoA-I were less common; all cytokines were lower than in CLP rats; and expression of Slit2, Robo4, and eNOS was completely restored. Administration of 4F inhibits inflammatory responses and strengthens the vascular barrier, protecting kidneys and hearts in an HDL-dependent manner. To determine the extent of the protective effect of 4F, further studies are needed.

Salutary Effect of Aurintricarboxylic Acid on Endotoxin- and Sepsis-Induced Changes in Muscle Protein Synthesis and Inflammation

Small molecule nonpeptidyl molecules are potentially attractive drug candidates as adjunct therapies in the treatment of sepsis-induced metabolic complications. As such, the current study investigates the use of aurintricarboxylic acid (ATA), which stimulates insulinlike growth factor 1 receptor and AKT signaling, for its ability to ameliorate the protein metabolic effects of endotoxin (lipopolysaccharide [LPS]) + interferon γ (IFN-γ) in C2C12 myotubes and sepsis in skeletal muscle. Aurintricarboxylic acid dose- and time-dependently increases mTOR (mammalian or mechanistic target of rapamycin)-dependent protein synthesis. Pretreatment with ATA prevents the LPS/IFN-γ-induced decrease in protein synthesis at least in part by maintaining mTOR kinase activity, whereas posttreatment with ATA is able to increase protein synthesis when added up to 6 h after LPS/IFN-γ. Aurintricarboxylic acid also reverses the amino acid resistance, which is detected in response to nutrient deprivation. Conversely, ATA decreases the basal rate of protein degradation and prevents the LPS/IFN-γ increase in proteolysis, and the latter change is associated reduced atrogin 1 and MuRF1 mRNA. The ability of ATA to antagonize LPS/IFN-γ-induced changes in protein metabolism was associated with its ability to prevent the increases in interleukin 6 and nitric oxide synthase 2 and decreases in insulinlike growth factor 1. In vivo studies indicate ATA acutely increases skeletal muscle, but not cardiac, protein synthesis and attenuates the loss of lean body mass over 5 days. These data suggest ATA and other small molecule agonists of endogenous anabolic hormones may prove beneficial in treating sepsis by decreasing the inflammatory response and improving muscle protein balance.

Mitochondrial changes in platelets are not related to those in skeletal muscle during human septic shock.

Platelets can serve as general markers of mitochondrial (dys)function during several human diseases. Whether this holds true even during sepsis is unknown. Using spectrophotometry, we measured mitochondrial respiratory chain biochemistry in platelets and triceps brachii muscle of thirty patients with septic shock (within 24 hours from admission to Intensive Care) and ten surgical controls (during surgery). Results were expressed relative to citrate synthase (CS) activity, a marker of mitochondrial density. Patients with septic shock had lower nicotinamide adenine dinucleotide dehydrogenase (NADH)/CS (p = 0.015), complex I/CS (p = 0.018), complex I and III/CS (p<0.001) and complex IV/CS (p = 0.012) activities in platelets but higher complex I/CS activity (p = 0.021) in triceps brachii muscle than controls. Overall, NADH/CS (r2 = 0.00; p = 0.683) complex I/CS (r2 = 0.05; p = 0.173), complex I and III/CS (r2 = 0.01; p = 0.485), succinate dehydrogenase (SDH)/CS (r2 = 0.00; p = 0.884), complex II and III/CS (r2 = 0.00; p = 0.927) and complex IV/CS (r2 = 0.00; p = 0.906) activities in platelets were not associated with those in triceps brachii muscle. In conclusion, several respiratory chain enzymes were variably inhibited in platelets, but not in triceps brachii muscle, of patients with septic shock. Sepsis-induced mitochondrial changes in platelets do not reflect those in other organs.

Polymicrobial Sepsis Alters Antigen-Dependent and -Independent Memory CD8 T Cell Functions

Mortality from sepsis frequently results from secondary infections, and the extent to which sepsis affects pathogen-specific memory CD8 T cell responses remains unknown. Using the cecal ligation and puncture model of polymicrobial sepsis, we observed rapid apoptosis of pre-existing memory CD8 T cells after sepsis induction that led to a loss in CD8 T cell-mediated protection. Ag sensitivity (functional avidity) and Ag-driven secondary expansion of memory CD8 T cells were decreased after sepsis, further contributing to the observed loss in CD8 T cell-mediated immunity. Moreover, Ag-independent bystander activation of memory CD8 T cells in response to heterologous infection was also significantly impaired early after sepsis induction. The reduced sensitivity of pre-existing memory CD8 T cells to sense inflammation and respond to heterologous infection by IFN-γ production was observed in inbred and outbred hosts and controlled by extrinsic (but not cell-intrinsic) factors, suggesting that sepsis-induced changes in the environment regulate innate functions of memory CD8 T cells. Taken together, the data in this study revealed a previously unappreciated role of sepsis in shaping the quantity and functionality of infection- or vaccine-induced memory CD8 T cells and will help further define the decline in T cell-mediated immunity during the sepsis-induced phase of immunosuppression.

Pharmakokinetische und pharmakodynamische Aspekte bei der Antibiotikatherapie

Severe sepsis and septic shock have a high mortality and, therefore require fast and effective antibiotic treatment with low toxicity. Because of sepsis-induced pathophysiological changes, pharmacokinetics of antimicrobial agents can be altered. Particularly water-soluble drugs display an enhanced volume of distribution during early sepsis. Therefore high loading doses are necessary. Renal clearance can also be increased at this time. Later on, organ damage frequently occurs resulting in delayed drug elimination which requires further dose adjustment. The different classes of antibiotics differ in their relevant pharmacokinetic-pharmacodynamic target parameters. Thus, the efficacy of an antimicrobial agent can depend on its concentration, on the exposure time, and on the total exposure as expressed by the area under the time-concentration curve. During treatment with time-dependent antibiotics (e.g. β-lactams), their concentration should be maintained above the minimal inhibitory concentration (MIC) warranting more frequent administration or continuous infusion. For concentration dependent agents (e.g. aminoglycosides), the single dose is pivotal, whereas the dosage interval can be extended. Drug-drug interactions involving antibiotics are mainly caused by inhibition of their metabolism, particularly of cytochrome P 450 iso-enzymes, or by additive toxic effects. They can result in severe complications such as renal failure or ventricular arrhythmias. Conversely, enzyme induction may lead to subtherapeutic drug levels. When continuous renal replacement therapy is required, the dosage of antibiotics has to be adapted according to the results of respective pharmacokinetic studies.

Orexinergic Activity Modulates Altered Vital Signs and Pituitary Hormone Secretion in Experimental Sepsis

Sepsis is a common, lethal poorly understood disorder affecting nearly a million Americans annually. The syndrome is characterized by altered cardiodynamics, respiration, metabolism, pituitary function, arousal, and impaired interaction among organ systems. The immunologic and endocrine systems, which are in part responsible for organ-organ communication, have been studied extensively in sepsis. However, little is known about sepsis-induced changes in central nervous system activity. A defect in hypothalamic neurons secreting the neurotransmitter orexin modulates physiologic derangements in sepsis. Animal study. University Research Laboratory. Male C57Bl6 mice were made septic using cecal ligation and puncture. Data were collected 24 or 48 hours later, blood was collected, animals were killed, and brain tissue was harvested, fixed, and sectioned. Hypothalamic sections were subjected to immunohistochemistry using antibodies to orexin and c-Fos, a marker of neuronal activity. In a separate cohort of mice, cannulas were placed in the right lateral cerebral ventricle. Cecal ligation and puncture was performed 1 week later. At 24 or 48 hours post-cecal ligation and puncture, vital signs were measured, and1 µL of saline with or without 3 nmol orexin-A was infused. Vital signs were repeated at 25 or 49 hours post-cecal ligation and puncture, blood was collected, animals were killed, and brains were removed, fixed, sectioned, and stained. Orexinergic activity decreased six-fold following cecal ligation and puncture. This change was associated with decreases in arousal, temperature, and heart and respiratory rates. Levels of selected pituitary hormones increased 24 hours post-cecal ligation and puncture but were significantly lower than baseline at 48 hours. Injection of orexin-A increased vital signs to baseline levels. Hormone levels were unaffected at 25 hours but increased to supranormal levels at 49 hours. Sepsis-induced changes in activity, vital signs, and pituitary hormones are modulated by the orexinergic system. This finding implicates central nervous system dysfunction in the pathogenesis of sepsis, suggesting further study of neurological dysfunction to identify novel approaches to management.

Sepsis-induced changes in behavioral stereotypy in rats; involvement of tumor necrosis factor-alpha, oxidative stress, and dopamine turnover

BackgroundSepsis-associated encephalopathy (SAE) is defined as a diffuse or multifocal cerebral dysfunction that generally occurs early during severe sepsis. The complete pathophysiology of SAE is unknown, but several mechanisms including endotoxins, inflammatory mediators, the alteration of amino acids and of neurotransmitters, apoptosis, oxidative stress, and blood-brain barrier dysfunction have been suggested. The aim of the present study was to explore the relationship between behavioral stereotypy and plasma levels of tumor necrosis factor-alpha (TNF-α) and malondialdehyde (a marker of lipid peroxidation), and brain homovanillic acid content (a marker of dopamine turnover) in a surgically induced sepsis model in rats. Materials and methodsTwenty-two adult male Sprague Dawley rats were included in the study. The cecal ligation and puncture procedure was performed to induce sepsis model. Apomorphine-induced stereotypy test was achieved 24 h after cecal ligation and puncture surgery and then, blood and brain samples were collected for biochemical measurements. ResultsSignificantly higher stereotypy score was found in sepsis group than in the sham group (P = 0.008). Furthermore, septic rats revealed significantly higher plasma TNF-α (P = 0.002) and malondialdehyde levels (P = 0.002), and brain homovanillic acid (P = 0.004) compared with sham rats. There was a significant and positive correlation between the behavioral and biochemical parameters. ConclusionsTaken together, these results demonstrate the association between inflammatory response, oxidative stress, and stereotypic behavior in an experimental sepsis model. More comprehensive experimental and clinical studies are required to clarify the specific mechanisms underlying SAE.

Effect of edaravone on permeability of blood-brain barrier in septic rats

Objective To evaluate the effects of edaravone on the permeability of blood-brain barrier in septic rats.Methods Ninety male Sprague-Dawley rats,weighing 200-250 g,were randomly divided into 3 groups (n=30 each):control group (group C),sepsis group (group lipopolysaccharide (LPS)) and edaravone group (group E).Sepsis was induced by injection of LPS 10 mg/kg via the femoral vein in LPS and E groups.After LPS injection,edaravone 3.0 mg/kg was injected intravenously every 2h for 7 times in group E.The equal volume of normal saline was administered instead of edaravone in C and LPS groups.At 2,6 and 12h after LPS injection,5 rats were chosen and Evan's blue (EB) was injected via the femoral vein,and then the rats were sacrificed and brain tissues were removed for determination of EB and water contents.Another 5 rats were chosen and blood samples were taken from the femoral artery for measurement of serum MDA concentration,and then the rats were sacrificed and the brain tissue was harvested for microscopic examination.Results Compared with group C,brain water and EB contents were significantly increased at 6 and 12h after LPS injection,and the serum MDA concentration was increased at 2,6 and 12h after LPS injection in LPS and E groups (P ＜ 0.05).Compared with group LPS,brain water and EB contents were significantly decreased at 6 and 12h after LPS injection,and serum MDA concentrations were decreased at 2,6 and 12h after LPS injection in group E (P ＜ 0.05).Sepsis-induced pathological changes were significantly attenuated in group E.Conclusion Edaravone can decrease the permeability of blood-brain barrier,attenuate brain edema and brain injury in septic rats,and reduction of oxygen free radical production may be involved in the mechanism. Key words: Free radical scavengers; Sepsis; Blood-brain barrier

Methylation metabolism in sepsis and systemic inflammatory response syndrome

We have recently shown that sepsis leads to alterations of methylation metabolism in a rodent model. In this study we analyzed methylation metabolism and DNA methylation in human sepsis. Patients treated in one of the Intensive Care Units (ICU) at the University Hospital Bonn diagnosed with sepsis or systemic inflammatory response syndrome (n = 12) and patients who were treated due to traumatic brain injury, or stroke without clinical or laboratory signs of sepsis or major inflammation (n = 22) were included. Blood samples were taken two times a week, until ICU treatment was discontinued. Deproteinized plasma was used for simultaneous determination of the ubiquitous methyl-group donor S-adenosylmethionine (SAM) and its demethylated residue, S-adenosylhomocysteine (SAH), by using stable isotope dilution tandem mass spectrometry. Homocysteine (Hcys), hydrolyzation product of SAH, was determined by fully automated particle-enhanced immunonephelometry, and global DNA-methylation was measured by liquid chromatography tandem mass spectrometry. SAM (p < 0.001) and SAH (p < 0.001) plasma levels were higher in septic patients suggesting an increased cellular release of SAM and SAH in septic patients. The SAM/SAH ratio was decreased in septic patients (p = 0.002). There were no differences in homocysteine plasma levels (p = 0.32) or global leukocyte DNA methylation between septic and non-septic patients (p = 0.21) suggesting that sepsis-induced changes in methylation metabolism do not affect homocysteine plasma levels or the availability of SAM-derived methyl groups for DNA methylation. Sepsis and systemic inflammatory response syndrome induce considerable changes of methylation metabolism without apparent functional consequences on homocysteine plasma levels or DNA methylation. Further studies may explore the clinical relevance of the observed changes.

Response to “HMGB1 Mediates Cognitive Impairment in Sepsis Survivors”

The letter from Dal-Pizzol et al.(1) addresses the question of brain cell activation in sepsis survivors. The data demonstrate that RAGE (receptor for advanced glycation end products) expression in the hippocampus and in the prefrontal cortex is significantly increased 4 wks after septic insult. This is an interesting observation because it indicates that altered expression of specific brain proteins can be sustained for weeks after sepsis. The significance of these findings can be considered in light of our recent report showing that HMGB1 (high mobility group box 1), one of the putative RAGE ligands, mediates memory loss in sepsis survivors (2). The novel findings by Dal-Pizzol et al.(1), combined with Chavan et al.(2), raise additional questions: What is the time course for the elevation of RAGE levels? Is it an immediate increase after septic insult, indicating a direct link between sepsis-mediated systemic inflammation and increased RAGE expression? Alternatively, is it a late effect, suggesting it is caused by sepsis-induced changes in brain physiology and not by the systemic inflammation? Which molecular cascade induces RAGE expression? What sustains the high expression of RAGE? Do receptors besides RAGE mediate HMGB1-dependent alteration of memory function, as suggested in a recent report by Mazarati et al.(3)? Which brain cells express RAGE? Is HMGB1 directly affecting neurons, or is it altering glial cell biology? A recent report by Pedrazzi et al.(4) shows that HMGB1 potentiates N-methyl-d-aspartate receptor activation, a process that might be critical for memory formation. This finding is consistent with the hypothesis that HMGB1 acts directly on neurons, but it may also activate glial cells, which in turn can modulate neuronal signaling via other cytokine networks. Finally, it is worth mentioning that HMGB1 may be deleterious to neurons or may function to compensate for previous injury. In sum, we agree with the authors of the letter that this is an important area of research with significant implications for medical practice.

Glutamine Modulates Sepsis-Induced Changes to Intestinal Intraepithelial γδT Lymphocyte Expression in Mice

This study investigated the effect of glutamine (GLN) on intestinal intraepithelial lymphocyte (IEL) γδT-cell cytokines and immune regulatory factor gene expressions in a mouse model of polymicrobial sepsis. Mice were randomly assigned to a normal group, a sepsis with saline (SS) group, or a sepsis with GLN (SG) group. All mice were fed a chow diet. Sepsis was induced by cecal ligation and puncture (CLP). The SS group was injected with saline, and the SG group was given 0.75 g GLN/kg body weight once via a tail vein 1 h after CLP. Septic mice were killed 12 h after CLP, and IEL γδT cells of the animals were isolated for further analysis. Results showed that compared with normal mice, sepsis resulted in lower IEL γδT-cell percentage and higher messenger RNA expressions of interferon γ, tumor necrosis factor α, interleukin 4 (IL-4), IL-13, IL-17, retinoid acid receptor-related orphan receptor γt, and complement 5a receptor by IEL γδT cells. These immunomodulatory mediator genes exhibited decreases, whereas IL-7 receptor expression increased in IEL γδT cells in septic mice with GLN administration. Annexin V/7-amino-actinomycin D stain revealed significantly lower rates of apoptosis, and IEL γδT-cell percentage was higher in the SG group. The histological findings also showed that damage to intestinal epithelial cells was less severe in the SG group. These results indicated that a single dose of GLN administered as treatment after the initiation of sepsis prevented apoptosis of IEL γδT cells and downregulated γδT cell-expressed inflammatory mediators that may consequently ameliorate the severity of sepsis-induced intestinal epithelial injury.

The effects of selenium and vitamin E on lung tissue in rats with sepsis

In this study we examined the ability of selenium and vitamin E to prevent sepsis-induced changes in lung tissue. Fifty rats were divided into five groups: Group 1: Control group; Group 2: Sepsis group. In this group only cecal ligation and perforation (CLP) was performed. Group 3: Selenium group. An intraperitoneal dose of 100 µg selenium was given for the first two days followed by a daily dose of 40 µg for the next five days. CLP was performed the following day. Group 4: Selenium and vitamin E group. In addition to selenium, vitamin E was given intramuscularly in a dose of 250 mg/kg/day for seven days. CLP was performed the following day. Group 5: Vitamin E group. Vitamin E was given intramuscularly in a dose of 250 mg/kg/day for seven days. CLP was performed the following day. There were significant differences between Group 2 and all other groups in terms of blood gas values (pH, pCO2, SaO2), and leukocyte, C-reactive protein (CRP) and glutathione peroxidase levels (p < 0.005). There was no statistically significant difference between groups 3, 4 and 5 in terms of histopathological changes in lung tissue (p > 0.05), but all groups were significantly different compared with Group 2 (p < 0.05). Sepsis-induced lung tissue damage can be reduced or prevented by pre-treatment with of selenium and/or vitamin E in a rat model.

Sepsis-Induced Adipokine Change with regard to Insulin Resistance

Background. Assessment of white adipose tissue has changed in recent years, with WAT now being considered as an active endocrine organ, secreting a large number of bioactive mediators, so-called adipokines. Besides other functions, these adipokines are involved in inflammatory response thereby exhibiting predominantly proinflammatory or anti-inflammatory properties and contribute to insulin resistance. Methods. Comprehensive review of the literature of the role of adipokines relevant to critical care medicine using PubMed search. Results. Adiponectin—the prototype of an anti-inflammatory and insulin-sensitizing adipokine—is diminished in sepsis, while resistin—a protein with proinflammatory properties—is elevated. Plasminogen activator inhibitor-1, interleukin (IL)-1, IL-6, IL-8, and IL-10, and tumor-necrosis-factor-alpha mediate insulin resistance and are elevated in sepsis, while retinol-binding protein-4 concentrations are significantly reduced in sepsis. Chemerin displays potent anti-inflammatory and insulin-resistance properties, while monocyte chemotactic protein-1—increased in sepsis—contributes to macrophage infiltration in adipose tissue and insulin resistance. Conclusions. The expression of adipokines in humans is altered as well in obese as in septic patients with elevated levels of proinflammatory adipokines. Changes in adipokine levels in acute sepsis could contribute to insulin resistance. Consequently, in critically ill patients, these alterations underline a possible contribution of adipokines in the development of hyperglycemia.

A Rat Model of Early Sepsis: Relationships between Gentamicin Pharmacokinetics and Systemic and Renal Effects of Bacterial Lipopolysaccharide Combined with Interleukin-2

A rat model of early sepsis induced by lipopolysaccharide (LPS) combined with interleukin-2 (IL-2) was developed. The primary aim was to assess the pharmacokinetics of gentamicin and sepsis-induced pathophysiological changes. Moreover, the effects on the glomerular filtration rate and tubular function were studied in septic and control rats. First, an intravenous (i.v.) bolus of LPSIL-2 (1 mg/kg-Pseudomonas aeruginosa, 15 µg/kg IL-2) or saline (controls, C) was administred. The Wistar rats were treated 30 min after LPSIL-2 with gentamicin as a 3 mg/kg i.v. bolus followed 10 min later by an i.v. 170-min infusion (GE, 0.09 mg/kg·min(-1)). The monitoring of vital functions, biochemistry and GE concentrations was performed. Creatinine clearance was 2-3 times lower and fractional urea excretion was 3-4 times less in septic rats as compared to controls(p<0.05), although urine flow was comparable. Capillary leakage caused a 55% elevation in the volume of distribution (V(c)) in the LPSIL+GE group vs. C+GE (p<0.05). The renal CL(ge) was less (2.2±0.59 vs. 3.8±0.53 mL/min·kg(-1), p<0.05), while the total CL(ge) was comparable (5.9±1.5 vs. 6.7±1.1 mL/min·kg(-1); p=0.30). In the LPSIL+GE group relative to C+GE, the half-life (t(1/2)) was 79% higher (p<0.05) and GE concentrations detected at the end of the study in the plasma and kidney were elevated 2.5-fold (p=0.09) and 2.2-fold (p<0.05), respectively. The model reproduced several consequences of early sepsis like in patients such as capillary leak, a decreased glomerular filtration rate (GFR) and the changes in pharmacokinetics of GE (increased values of V(c) and t(1/2) and a drop in renal CL(ge) proportional to that of CL(cr)). Nonrenal routes which, for the most part, compensate the reduced renal CL(ge) in septic rats deserve further study.

Comparison of Sepsis-Induced Transcriptomic Changes in a Murine Model to Clinical Blood Samples Identifies Common Response Patterns

Experimental models, mimicking physiology, and molecular dynamics of diseases in human, harbor the possibility to study the effect of interventions and transfer results from bench to bedside. Recent advances in high-throughput technologies, standardized protocols, and integration of knowledge from databases yielded rising consistency and usability of results for inter-species comparisons. Here, we explored similarities and dissimilarities in gene expression from blood samples of a murine sepsis model (peritoneal contamination and infection, PCI) and patients from the pediatric intensive care unit (PICU) measured by microarrays. Applying a consistent pre-processing and analysis workflow, differentially expressed genes (DEG) from PCI and PICU data significantly overlapped. A major fraction of DEG was commonly expressed and mapped to adaptive and innate immune response related pathways, whereas the minor fraction, including the chemokine (C–C motif) ligand 4, exhibited constant inter-species disparities. Reproducibility of transcriptomic observations was validated experimentally in PCI. These data underline, that inter-species comparison can obtain commonly expressed transcriptomic features despite missing homologs and different protocols. Our findings point toward a high suitability of an animal sepsis model and further experimental efforts in order to transfer results from animal experiments to the bedside.

Effect of LIdocaine on the expression of high mobility group box 1 mRNA in the lung tissue in septic rats

Objective To investigate the effect of lidocaine on expression of high mobility group box 1 ( HMGB1 ) mRNA in lung tissue in septic rats.Methods Fifty male Wistar rats weighing 200-250 g were randomly divided into 5 groups ( n ＝ 10 each):group sham operation( group S) ; group sepsis( group L) ; group low,medium and high dose lidocaine (groups LL1,LL2,LL3 ).Sepsis was induced by cecal ligation and puncture in groups L,LL1,LL2,LL3.Lidocaine 5,10 and 20 mg/kg were injected intraperitoneally at the end of operation,and at 1 and 2 h after operation in groups LL1,LL2 and LL3.Five animals in each group were sacrificed at 24 and 48 h after operation respectively.The lungs were removed for microscopic examination and determination of HMGB1 mRNA expression,MPO activity and activation of NF-cB.Results Sepsis up-regulated HMGB1 mRNA and increased MPO activity and activation of NF-κB and induced lung histo-pathological damage.Lidocaine attenuated the abovementioned sepsis-induced changes in a dose-dependent manner.Conclusion Lidocaine can attenuate sepsis-induced acute lung injury by down-regulating HMGB1 mRNA expression and inhibiting activation of NF-κB. Key words: Lidocaine; Sepsis; HMGB1 protein; RNA,messenger; Lung