Epinephrine inhibits endotoxin-induced IL-1 beta production: roles of tumor necrosis factor-alpha and IL-10

Investigation of the potential of leukoreduction filters in the creation of anti-inflammatory compound

BACKGROUND

Some viruses such as SARS, SARS-CoV-2, and MERS cause an imbalance in immune responses and leads to an acute inflammatory reaction named cytokine storm. In this situation, an anti-inflammatory component can modulate the immune system and decrease mortality. The aim of this study was investigate the potential of leukoreduction filters (LRFs) in creating an anti-inflammatory compound.

MATERIALS AND METHODS

In this experimental study, firstly optimal dose of the anti-inflammatory drug was obtained through LRFs treatment with 0.1 mg, 0.4 mg, 0.6 mg of Betamethasone. Then inflammatory and anti-inflammatory cytokine in gene and protein level was evaluated. In the next step, LRFs were categorized into treatment 1, treatment 2, control assay, and control groups and treated with the optimal dose of the drug. Finally, the obtained compound was investigated for the concentration of IL1, IL6, and TNF-α as inflammatory and IL4, IL1Ra, and IL10 as anti-inflammatory cytokines.

RESULTS

The results of the current study showed that the concentration of 0.4 mg of Betamethasone lead to a significant increase of anti-inflammatory cytokine in gene and protein levels. The results also showed that the Betamethasone treated groups (treatment1) causes a significant increase in the secretion of anti-inflammatory cytokine compares to the control while inflammatory cytokine remained at the control level.

CONCLUSION

The results showed that under influence of anti-inflammatory drug treatments the production and secretion of anti-inflammatory cytokines can be induced in LRFs.

Epinephrine administration in venoarterial extracorporeal membrane oxygenation patients is associated with mortality: a retrospective cohort study

Aims

Knowledge about the impact of epinephrine on the outcome in venoarterial (VA) extracorporeal membrane oxygenation (ECMO) patients is limited, and existing data are conflicting.

Methods and results

We conducted a retrospective cohort study in a 1500 bed tertiary university hospital. Five hundred and eighty‐nine VA‐ECMO patients were analysed. The median age was 57 years [47–65], 68% of male. The major indications for ECMO were post‐cardiotomy cardiogenic shock (CS) (38%) and medical CS (36%). Two hundred and sixty‐two (44.5%) patients received epinephrine alone or associated with another catecholamine while on ECMO. Baseline factors significantly associated with epinephrine administration were younger age, higher sequential organ failure assessment score, cardiac arrest at implantation, and intra‐aortic balloon pump support at implantation, whereas medical CS and dobutamine administration were significantly associated with a lower risk of epinephrine administration. Epinephrine administration was independently associated with death [hazard ratio = 1.68 (1.44–2.23); P < 0.01]. A sensitivity analysis with propensity score inverse probability weighting in complete cases confirmed a significant association of epinephrine administration with death [hazard ratio = 1.69 (1.43–2.00); P < 0.001].

Conclusions

Among patients who required VA‐ECMO, epinephrine administration was associated with an increased risk for death.

Effects of epinephrine on heart rate variability and cytokines in a rat sepsis model

Catecholamines have both anti-inflammatory and vasoactive properties. A decreased cardiac response to catecholamines has been associated with a high risk of death in sepsis and septic shock. The aim of this study was to investigate the effects of epinephrine (EPI) on heart rate variability (HRV) and autonomic balance, as well as cytokine levels, in a rat sepsis model. Thirty-six male Sprague-Dawley rats were assigned to 4 experimental groups and 2 control groups of 6 rats each. The rats in the experimental groups were inoculated with a lipopolysaccharide (LPS, endotoxin) to establish a sepsis model. Group A received only LPS; group B received LPS, antecedent EPI and the nonselective β-blocker propranolol; group C received LPS and antecedent EPI; and group D received LPS, antecedent EPI and the selective β1-blocker esmolol. One control group received EPI and the other received saline placebo. Heart rate variability (HRV) was analyzed and tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) levels were measured. Measurements were carried out at baseline, at 0 hour after EPI infusion, and at 0.5, 2, and 4 hours after LPS inoculation. There were significant differences in HRV and cytokine levels between the groups, indicating that LPS infusion caused autonomic imbalance. Antecedent EPI significantly decreased the level of TNF-α in group C compared with group A in which TNF-α level peaked at 2 hours and then declined. Propranolol (group B) but not esmolol (group D) administration resulted in elevated TNF-α levels, comparable to those observed in group A. In conclusion, antecedent administration of EPI in a rat sepsis model inhibits the production of TNF-α possibly via the β2-adrenoceptor.

A Potential Mechanism for Immune Suppression by Beta-Adrenergic Receptor Stimulation following Traumatic Injury

BACKGROUND

β-Adrenergic agents suppress inflammation and may play an important role in posttraumatic infections. Mechanisms may include inhibition of MAP kinase signaling. We sought to determine whether MKP-1 contributed to catecholamine suppression of innate immunity and also wanted to know whether early catecholamine treatment after traumatic injury increases the risk of later nosocomial infection.

METHODS

We performed experiments using THP-1 cells and peripheral blood mononuclear cells from healthy individuals. We exposed cells to epinephrine and/or LPS and measured inflammatory gene transcription and MAP kinase activation. We inhibited MKP-1 activity to determine its role in catecholamine-induced immune suppression. Finally, we studied injured subjects to determine whether early catecholamine treatment was associated with nosocomial infection.

RESULTS

Epinephrine increases MKP-1 transcripts and protein and decreases LPS-induced p38 and JNK phosphorylation and TNF-α gene transcription. RNAi inhibition of MKP-1 at least partially restores LPS-induced TNF-α gene expression (p = 0.024). In the clinical cohort, subjects treated with β-adrenergic agents had an increased risk of ventilator-associated pneumonia (aOR = 1.9; 95% CI = 1.3-2.6) and bacteremia (aOR = 1.5; 95% CI = 1.1-2.3).

CONCLUSIONS

MKP-1 may have a role in catecholamine-induced suppression of innate immunity, and exogenous catecholamines might contribute to nosocomial infection risk.

Adrenergic Effect on Cytokine Release After Ex Vivo Healthy Volunteers' Whole Blood LPS Stimulation

Catecholamines are molecules with immunomodulatory properties in health and disease. Several studies showed the effect of catecholamines when administered to restore hemodynamic stability in septic patients. This study investigates the effect of norepinephrine and dobutamine on whole blood cytokine release after ex vivo lipopolysaccharide (LPS) stimulation. Whole blood collected from healthy individuals was stimulated with LPS, in the presence of norepinephrine or dobutamine at different concentrations, with or without metoprolol, a β1 receptor antagonist. Cytokine measurement was performed in isolated cell culture supernatants with ELISA. Results are expressed as mean ± SEM and compared with Mann-Whitney rank-sum test. Both norepinephrine and dobutamine significantly reduced TNF-α and IL-6 production after ex vivo LPS stimulation of whole blood in a dose-dependent manner, and this effect was partially reversed by the presence of metoprolol. Norepinephrine and dobutamine reduce the LPS-induced production of pro-inflammatory cytokines, thus possibly contributing to altered balance between the inflammatory and anti-inflammatory responses, which are vital for a successful host response to severe disease, shock, and sepsis.

Targeting the Innate Immune Response to Improve Cardiac Graft Recovery after Heart Transplantation: Implications for the Donation after Cardiac Death

Heart transplantation (HTx) is the ultimate treatment for end-stage heart failure. The number of patients on waiting lists for heart transplants, however, is much higher than the number of available organs. The shortage of donor hearts is a serious concern since the population affected by heart failure is constantly increasing. Furthermore, the long-term success of HTx poses some challenges despite the improvement in the management of the short-term complications and in the methods to limit graft rejection. Myocardial injury occurs during transplantation. Injury initiated in the donor as result of brain or cardiac death is exacerbated by organ procurement and storage, and is ultimately amplified by reperfusion injury at the time of transplantation. The innate immune system is a mechanism of first-line defense against pathogens and cell injury. Innate immunity is activated during myocardial injury and produces deleterious effects on the heart structure and function. Here, we briefly discuss the role of the innate immunity in the initiation of myocardial injury, with particular focus on the Toll-like receptors and inflammasome, and how to potentially expand the donor population by targeting the innate immune response.

Neuroendocrine regulation of inflammation

The interaction between the sympathetic nervous system and the immune system has been documented over the last several decades. In this review, the neuroanatomical, cellular, and molecular evidence for neuroimmune regulation in the maintenance of immune homeostasis will be discussed, as well as the potential impact of neuroimmune dysregulation in health and disease.

Induction of M2 regulatory macrophages through the β2-adrenergic receptor with protection during endotoxemia and acute lung injury

The main drivers of acute inflammation are macrophages, which are known to have receptors for catecholamines. Based on their function, macrophages are broadly categorized as having either M1 (proinflammatory) or M2 phenotypes (anti-inflammatory). In this study, we investigated catecholamine-induced alterations in the phenotype of activated macrophages. In the presence of lipopolysaccharide (LPS), mouse peritoneal macrophages acquired an M1 phenotype. However, the copresence of LPS and either epinephrine or norepinephrine resulted in a strong M2 phenotype including high levels of arginase-1 and interleukin-10, and a reduced expression of M1 markers. Furthermore, epinephrine enhanced macrophage phagocytosis and promoted type 2 T-cell responses in vitro, which are known features of M2 macrophages. Analysis of M2 subtype-specific markers indicated that LPS and catecholamine-cotreated macrophages were not alternatively activated but were rather of the regulatory macrophage subtype. Interestingly, catecholamines signaled through the β2-adrenergic receptor but not the canonical cAMP/protein kinase A signaling pathway. Instead, the M2 pathway required an intact phosphoinositol 3-kinase pathway. Blockade of the β2-adrenergic receptor reduced survival and enhanced injury in mouse models of endotoxemia and LPS-induced acute lung injury, respectively. These results demonstrate a role for the β2-adrenergic receptor in promoting the M2 macrophage phenotype.

Acute stress elicited by bungee jumping suppresses human innate immunity

Although a relation between diminished human immunity and stress is well recognized both within the general public and the scientific literature, the molecular mechanisms by which stress alters immunity remain poorly understood. We explored a novel model for acute human stress involving volunteers performing a first-time bungee jump from an altitude of 60 m and exploited this model to characterize the effects of acute stress in the peripheral blood compartment. Twenty volunteers were included in the study; half of this group was pretreated for 3 d with the β-receptor blocking agent propranolol. Blood was drawn 2 h before, right before, immediately after and 2 h after the jump. Plasma catecholamine and cortisol levels increased significantly during jumping, which was accompanied by significantly reduced ex vivo inducibility of proinflammatory cytokines as well as activation of coagulation and vascular endothelium. Kinome profiles obtained from the peripheral blood leukocyte fraction contained a strong noncanonical glucocorticoid receptor signal transduction signature after jumping. In apparent agreement, jumping down-regulated Lck/Fyn and cellular innate immune effector function (phagocytosis). Pretreatment of volunteers with propranolol abolished the effects of jumping on coagulation and endothelial activation but left the inhibitory effects on innate immune function intact. Taken together, these results indicate that bungee jumping leads to a catecholamine-independent immune suppressive phenotype and implicate noncanonical glucocorticoid receptor signal transduction as a major pathway linking human stress to impaired functioning of the human innate immune system.

Cardiac function and the proinflammatory cytokine response after recovery from cardiac arrest in swine

Increased levels of cytokines have been reported after resuscitation from cardiac arrest. We hypothesized that proinflammatory cytokines, released in response to ischemia/reperfusion, increase following resuscitation and play a role in post-cardiac arrest myocardial dysfunction. Ventricular fibrillation (VF) was induced by coronary occlusion in 20 swine. After 7 min of VF, resuscitation was performed as per guidelines. Plasma levels of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6 were measured 15 min after the start of resuscitation in all animals and at intervals of 6 h in resuscitated animals. Intravascular pressures and cardiac output (CO) were also recorded. TNF-alpha abruptly increased after resuscitation, peaking at 15 min following return of spontaneous circulation, and declined to baseline levels after 3 h. IL-1beta increased more slowly, reaching a maximum 2 h after reperfusion. IL-6 concentrations were not significantly different from control values at any time point. Males demonstrated greater elevations of TNF-alpha and IL-1beta than females. Stroke work was significantly depressed at all time points with a nadir at 15-30 min after reperfusion, corresponding to the peak TNF-alpha values. The anti-TNF-alpha antibody infliximab attenuated the decrease in myocardial function observed 30 min after reperfusion. TNF-alpha increases during recovery from cardiac arrest are associated with depression of left ventricle (LV) function. The effect of TNF-alpha can be attenuated by anti-TNF-alpha antibodies.

Multiscale model for the assessment of autonomic dysfunction in human endotoxemia

Severe injury and infection are associated with autonomic dysfunction. The realization that a dysregulation in autonomic function may predispose a host to excessive inflammatory processes has renewed interest in understanding the role of central nervous system (CNS) in modulating systemic inflammatory processes. Assessment of heart rate variability (HRV) has been used to evaluate systemic abnormalities and as a predictor of the severity of illness. Dissecting the relevance of neuroimmunomodulation in controlling inflammatory processes requires an understanding of the multiscale interplay between CNS and the immune response. A vital enabler in that respect is the development of a systems-based approach that integrates data across multiple scales, and models the emerging host response as the outcome of interactions of critical modules. Thus, a multiscale model of human endotoxemia, as a prototype model of systemic inflammation in humans, is proposed that integrates processes across the host from the cellular to the systemic host response level. At the cellular level interacting components are associated with elementary signaling pathways that propagate extracellular signals to the transcriptional response level. Further, essential modules associated with the neuroendocrine immune crosstalk are considered. Finally, at the systemic level, phenotypic expressions such as HRV are incorporated to assess systemic decomplexification indicative of the severity of the host response. Thus, the proposed work intends to associate acquired endocrine dysfunction with diminished HRV as a critical enabler for clarifying how cellular inflammatory processes and neural-based pathways mediate the links between patterns of autonomic control (HRV) and clinical outcomes.

In vivo endotoxin synchronizes and suppresses clock gene expression in human peripheral blood leukocytes

OBJECTIVES

The intravenous administration of a bolus dose of endotoxin to healthy human subjects triggers acute systemic inflammatory responses that include cytokine production and dynamic changes in gene expression in peripheral blood leukocytes. This study sought to determine the state of clock gene expression in human peripheral blood leukocytes, and leukocyte subpopulations, challenged with in vivo endotoxin at two circadian/diurnal phases of the clock.

DESIGN

Clinical and laboratory investigation.

SETTING

University-based research laboratory and clinical research center.

SUBJECTS

Human volunteers.

INTERVENTIONS

Human subjects were administered a standard dose of endotoxin (2 ng/kg) or saline at either 0900 or 2100 hrs. Blood samples were collected at selected time points pre- and postinfusion.

MEASUREMENTS AND MAIN RESULTS

Clock gene expression was determined in human peripheral blood leukocytes, neutrophils, and monocytes by quantitative real-time polymerase chain reaction. The fold change for each gene was determined by use of the 2 method. We show that endotoxin causes profound suppression of circadian clock gene expression, clearly manifested in human peripheral blood leukocytes, neutrophils, and monocytes. Clock, Cry1-2, Per3, CSNK1epsilon, Rora, and Rev-erb gene expression were all reduced by 80% to 90% with the nadir between 3 and 6 hrs postinfusion. Per1 and Per2 reached an expression nadir between 13 and 17 hrs postinfusion. The levels of plasma interleukin-6 and tumor necrosis factor peaked and then returned to baseline within 6 hrs. In contrast, clock gene expression remained suppressed for up to 17 hrs irrespective of the phase of the clock at the time of the endotoxin challenge. Endotoxin did not perturb the melatonin secretory rhythm.

CONCLUSIONS

Circadian clock gene expression in peripheral blood leukocytes is dramatically altered and possibly uncoupled from the activity of the central clock during periods of acute systemic inflammation. The realignment of the central and peripheral clocks may constitute a previously unappreciated key factor affecting recovery from disease in humans.

Pro-inflammatory responses in human monocytes are beta1-adrenergic receptor subtype dependent

Stress induced circulating catecholamines are hypothesized to selectively activate adrenergic receptors (ARs) on immunocompetent cells modulating their inflammatory response to trauma or environmental toxins. We characterized changes in expression of a pro-inflammatory cytokine modulated by beta-AR activation in human primary and immortalized monocytes that had been simultaneously stimulated with lipopolysaccharide (LPS). Results from cytokine antibody arrays demonstrated that half-maximal effective concentrations of the selective beta-AR agonist isoproterenol (Iso) qualitatively increased LPS-mediated expression of the soluble cytokine, interleukin-1beta (IL-1beta). Semi-quantitative immunoblot techniques confirmed a synergistic increase of IL-1beta production in both LPS stimulated THP-1 cells and primary human monocytes co-incubated with Iso. Immunoblot techniques as well as radioligand binding studies were also used to characterize the heterogeneous expression of beta(1)- and beta(2)-AR subtypes on THP-1 cells. beta-AR activation is classically associated with generation of cAMP in many tissues and cell types. Therefore, using the method of Schild, we generated Iso concentration-response curves in the presence of fixed subtype-selective beta-AR antagonist concentrations to demonstrate that beta(1)-AR activation was exclusively linked with the generation of cAMP in THP-1 cells. Furthermore, use of a selective kinase inhibitor demonstrated that Iso potentiated the expression of soluble IL-1beta through activation of cAMP-dependent protein kinase A. Finally, discriminating concentrations of subtype-selective beta-AR antagonists revealed that beta(1)-AR stimulation alone accounted for the synergistic production of IL-1beta in LPS stimulated monocytes co-incubated with Iso. These results demonstrate a unique synergistic pro-inflammatory response mediated through a beta(1)-AR cAMP-dependent mechanism in LPS-challenged monocytic cells.

Gender differences in stimulated cytokine production following acute psychological stress

Emerging evidence suggests that acute psychological stress modulates inflammatory competence; however, not all findings are consistent. Gender is one factor that may impact magnitude of response. To explore this possibility, we examined the effects of acute mental stress on lipopolysaccharide-induced production of pro-inflammatory cytokines interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha among a relatively healthy sample of midlife men (n=28) and women (n=34). Blood samples for the assessment of cytokine production were drawn before, immediately after, and 30min following subjects' performance of an evaluative speech task. Relative to baseline evaluations, the speech stressor elicited a significant increase in stimulated production of all 3 pro-inflammatory cytokines, as measured 30min following the end of the task. There were no gender differences in the magnitude of this effect. However, men showed a significant decrease in cytokine production from before to immediately following the stressor, whereas women showed no change across this period. Menopausal status partially accounted for these gender differences, with post-menopausal women displaying greater increases in IL-6 and TNF-alpha production from baseline-to-post-task when compared to men. These data provide further evidence that acute psychological stress primes the immune system to mount larger inflammatory responses and initial support for gender differences in the patterning of stress-related cytokine activity. In addition, this study presents novel evidence that post-menopausal women may be particularly susceptible to stress-related inflammatory responses. The possibility that this contributes to the increased risk of inflammatory disease observed among older women warrants investigation.

Metastatic-promoting effects of LPS: sexual dimorphism and mediation by catecholamines and prostaglandins

Inflammation is implicated in several medical conditions that are sexually dimorphic, including depression, cardiovascular diseases, autoimmunity, and presumably cancer progression. Here we studied the effects of the proinflammatory agent, LPS, on MADB106 lung tumor retention (LTR), and sought to elucidate underlying mechanisms and sexual dimorphism. F344 male and female rats were administered with LPS (0.001-1mg/kg i.v.) simultaneously with tumor cell inoculation, and treated with a beta-blocker (nadolol, 0.2-0.3mg/kg s.c.), a COX inhibitor (indomethacin, 4mg/kg s.c.) or both drugs. To study the role of NK cells, numbers and cytotoxicity of marginating-pulmonary NK cells were studied, and selective in vivo NK-depletion was employed. Serum levels of corticosterone, IL-6, and TNF-alpha were also assessed. The findings indicated that LPS increased LTR in both sexes, but 10-fold higher doses were needed in females to reach the increase evident in males. Additionally, nadolol and indomethacin reduced the effects of LPS, more so in males. In vivo NK-depletion and ex vivo NK activity studies suggested that LPS affected LTR through both NK-independent and NK-dependent mechanisms, the latter mediated through prostaglandin release in males. Corticosterone, IL-6, and TNF-alpha responses to LPS were sexually dimorphic, but were not associated with LPS or drugs' impacts on LTR. Overall, our findings demonstrate sexual dimorphism in LPS-induced elevated susceptibility to MADB106 experimental metastasis, and in potential humoral underlying mechanisms. Further studies are needed to elucidate additional immunological and non-immunological mediators of these dimorphisms, as well as to assess their involvement in other sexually dimorphic pathologies that are associated with inflammation.

Influence of acute epinephrine infusion on endotoxin-induced parameters of heart rate variability: a randomized controlled trial

OBJECTIVE

To determine whether the acute anti-inflammatory influence of epinephrine (EPI) extends to changes in heart rate variability (HRV) induced by the prototypical inflammatory stimulus, endotoxin (lipopolysaccharide [LPS]).

SUMMARY BACKGROUND DATA

HRV reflects fluctuating cardiac autonomic inputs and is acutely reduced during the systemic inflammation induced by LPS as well as during severe critical illnesses such as sepsis and traumatic injury. While EPI may diminish proinflammatory cytokine release, it is unknown whether this net anti-inflammatory activity extends to HRV.

METHODS

Healthy volunteers (n = 17) were randomized to either saline + LPS (2 ng/kg) or LPS + antecedent EPI infusion (30 ng/kg/min) from -3 to 6 hours relative to LPS. HRV and blood samples were obtained before EPI and LPS as well as hourly afterward. Plasma cytokines were measured by ELISA. Statistical analysis was by repeated measures analysis of variance. This study was registered at Clinicaltrials.gov and is listed under the following ID number: NCT00753402.

RESULTS

LPS acutely influenced all measured parameters of HRV including standard deviation of the average beat to beat intervals over a 5-minute period, percentage of interval differences of successive interbeat intervals greater than 50 milliseconds and square root of the mean squared differences, high frequency (HF), low frequency, low frequency/HF, and very low frequency (all P < 0.01). EPI infusion reduced the inflammatory cytokine response to LPS as measured by decreased TNFalpha, IL-6, and IL-8 (P < 0.01). Relative to the saline + LPS group, antecedent EPI infusion was associated with further reductions in parameters of HRV measuring vagal/parasympathetic activity including, percentage of interval differences of successive interbeat intervals greater than 50 milliseconds, square root of the mean squared differences, and HF (P < 0.05).

CONCLUSION

Prior EPI exposure exerts anti-inflammatory influences but also may reduce vagus nerve activity. Hence, acute EPI administration may be protective against early inflammatory challenges but diminish vagal nerve responsiveness to subsequent stimuli.

Beta-adrenergic blockade exacerbates sepsis-induced changes in tumor necrosis factor alpha and interleukin-6 in skeletal muscle and is associated with impaired translation initiation

BACKGROUND

Sepsis stimulates the sympathetic nervous system. The resultant elevation in plasma catecholamines, both norepinephrine and epinephrine (Epi), might be expected to alter the expression of inflammatory cytokines, which may directly or indirectly influence muscle protein balance. The purpose of this study was twofold: (1) determine whether Epi per se increases cytokine expression in skeletal muscle, and (2) determine whether beta-adrenergic blockade alters the sepsis-induced expression of inflammatory cytokines and mediators of protein balance in skeletal muscle.

METHODS

In the first study, rats were infused with Epi for 2 hour to increase the circulating Epi concentration to levels seen in septic animals. In the second study, sepsis was induced by cecal ligation and puncture and a nonspecific beta-adrenergic blockade produced with a continuous infusion of propranolol (PP). Tissues were obtained 24 after induction of sepsis and analyzed for tumor necrosis factor (TNF)-alpha interleukin (IL)-1beta, IL-6 mRNA and protein content. In addition, the tissue content of insulin-like growth factor (IGF)-I and various regulators of protein synthesis were assessed.

RESULTS

Epi acutely increased TNF-alpha IL-6 and IL-1beta mRNA content in muscle (3- to 40-fold). However, only the TNF-alpha and IL-6 protein content was increased in muscle by Epi. In the second study, beta-adrenergic blockade with PP exacerbated the sepsis-induced increase in muscle IL-6 and TNF-alpha mRNA but did not alter the increment in IL-1beta or HMGB1. Propranolol also accentuated the sepsis-induced increase in both IL-6 and TNF-alpha protein in muscle. The exaggerated muscle cytokine response in septic rats treated with PP was associated with a reduction in muscle IGF-I protein that was greater than detected in saline-infused septic rats. Finally, the combination of sepsis + PP also accentuated the sepsis-induced decrease in the phosphorylation of 4E-binding protein-1, ribosomal protein S6, and mTOR, which are key proteins controlling protein synthesis.

CONCLUSIONS

These results demonstrate that although Epi is capable of increasing tissue cytokines in naive rats, inhibition of the beta-adrenergic effects of catecholamines exacerbates the sepsis-induced increase of selected inflammatory cytokines. This exaggerated tissue response is associated with alterations in muscle IGF-I protein and translation initiation, which would be expected to impair tissue protein synthesis.

Nicotine exposure alters in vivo human responses to endotoxin

The alpha 7 nicotinic receptor is reportedly a key element in the cholinergic anti-inflammatory pathway. Because a prototypical ligand for this receptor is nicotine, we studied the in vivo human response to bacterial endotoxin or lipopolysaccharide (LPS) in the context of nicotine or placebo pretreatment. Twelve adult male normal subjects were studied prospectively. Six received overnight transcutaneous nicotine administration by application of a standard patch (7 mg). Six hours later, all subjects were given an intravenous dose of endotoxin (2 ng/kg) and were evaluated for an additional 24 h for circulating levels of inflammatory biomarkers, vital signs and symptoms. The nicotine subjects had elevated blood levels of the nicotine metabolite, continine, prior to and throughout the 24-h post-endotoxin exposure phase. Subjects receiving nicotine exhibited a significantly lower temperature response as well as attenuated cardiovascular responses for 2.5-6 h after LPS exposure. In addition, increased circulating interkeukin (IL)-10 and cortisol levels were also noted in nicotine subjects. These data indicate an alteration in LPS-induced systemic inflammatory responses in normal subjects exposed to transcutaneous nicotine. In this model of abbreviated inflammation, nicotine exposure attenuates the febrile response to LPS and promotes a more prominent anti-inflammatory phenotype.

Bench-to-bedside review: Is there a place for epinephrine in septic shock?

The use of epinephrine in septic shock remains controversial. Nevertheless, epinephrine is widely used around the world and the reported morbidity and mortality rates with it are no different from those observed with other vasopressors. In volunteers, epinephrine increases heart rate, mean arterial pressure and cardiac output. Epinephrine also induces hyperglycemia and hyperlactatemia. In hyperkinetic septic shock, epinephrine consistently increases arterial pressure and cardiac output in a dose dependent manner. Epinephrine transiently increases lactate levels through an increase in aerobic glycolysis. Epinephrine has no effect on splanchnic circulation in dopamine-sensitive septic shock. On the other hand, in dopamine-resistant septic shock, epinephrine has no effect on tonometric parameters but decreases fractional splanchnic blood flow with an increase in the gradient of mixed venous oxygen saturation (SVO₂) and hepatic venous oxygen saturation (SHO₂). In conclusion, epinephrine has predictable effects on systemic hemodynamics and is as efficient as norepinephrine in correcting hemodynamic disturbances of septic shock. Moreover, epinephrine is cheaper than other commonly used catecholamine regimens in septic shock. The clinical impact of the transient hyperlactatemia and of the splanchnic effects are not established.

Burn wounds infected with Pseudomonas aeruginosa triggers weight loss in rats

Background

Despite dramatic improvements in the management of burns, infection still remains a serious risk for the burn patient. The aim of this study was to shed light on the impact of acute burn injury with or without infection on cytokine profiles.

Methods

Sprague-Dawley rats (n = 21) were randomized into three groups: 1) burn only 2) burn and infection or 3) sham burn. Weight was monitored and blood was collected for cytokine ELISA, LPS quantification, and peripheral blood analysis. Animals were sacrificed either after 6 or 12 days.

Results

Infected animals showed substantial weight loss until day 6 post-burn as compared to burn alone. Endotoxin and TNF-α levels were elevated early in the infected burn group within 48 hours post-burn. In contrast, significant up-regulation of the anti-inflammatory cytokine IL-10 occurred later in the clinical course and was associated with the recovery from weight loss.

Conclusion

Our results suggest that in the presence of infection, you get a SIRS response possibly due to transient endotoxemia that is only seen in the infection group. In contrast, both burn and infection get a late IL-10 (CARS) response, which is then associated with a return to normal weight in the infection group.

Mechanisms of beta-receptor stimulation-induced improvement of acute lung injury and pulmonary edema

Acute lung injury (ALI) and the acute respiratory distress syndrome are complex syndromes because both inflammatory and coagulation cascades cause lung injury. Transport of salt and water, repair and remodeling of the lung, apoptosis, and necrosis are additional important mechanisms of injury. Alveolar edema is cleared by active transport of salt and water from the alveoli into the lung interstitium by complex cellular mechanisms. Beta-2 agonists act on the cellular mechanisms of pulmonary edema clearance as well as other pathways relevant to repair in ALI. Numerous studies suggest that the beneficial effects of beta-2 agonists in ALI include at least enhanced fluid clearance from the alveolar space, anti-inflammatory actions, and bronchodilation. The purposes of the present review are to consider the effects of beta agonists on three mechanisms of improvement of lung injury: edema clearance, anti-inflammatory effects, and bronchodilation. This update reviews specifically the evidence on the effects of beta-2 agonists in human ALI and in models of ALI. The available evidence suggests that beta-2 agonists may be efficacious therapy in ALI. Further randomized controlled trials of beta agonists in pulmonary edema and in acute lung injury are necessary.

On the selectivity of superoxide dismutase mimetics and its importance in pharmacological studies

The list of pathophysiological conditions associated with the overproduction of superoxide expands every day. Much of the knowledge compiled on the role of this radical in disease has been gathered using the native superoxide dismutase enzyme and, more recently, by the use of superoxide dismutase knockout models or transgenic models that overexpress the various isoforms of the enzyme. Although the native enzyme has shown promising anti-inflammatory properties in both preclinical and clinical studies, there were drawbacks and issues associated with its use as a therapeutic agent and pharmacological tool. Based on the concept that removal of superoxide modulates the course of inflammation, synthetic, low-molecular-weight mimetics of the superoxide dismutase enzymes that could overcome some of the limitations associated with the use of the native enzyme have been designed. In this review, we will discuss the advances made using various superoxide dismutase mimetics that led to the proposal that superoxide (and/or the product of its interaction with nitric oxide, peroxynitrite) is an important mediator of inflammation, and to the conclusion that superoxide dismutase mimetics can be utilized as therapeutic agents in diseases of various etiologies. The importance of the selectivity of such compounds in pharmacological studies will be discussed.

Sepsis-induced immunosuppression: from bad to worse

The sepsis syndrome is characterized by the acute release of a variety of inflammatory mediators, which often result in detrimental effects to the host. The release of these mediators is regulated and counterbalanced by the coordinated expression of antiinflammatory molecules. It is the balance between the expression of pro- and antiinflammatory mediators that often determines the magnitude of early tissue injury and subsequent risk of infectious complications. As our understanding of the pathophysiology of sepsis continues to evolve, we have gained a greater appreciation for the effects that sepsis and similar states of overwhelming stress have on host antimicrobial immunity. A number of functional defects in leukocytes isolated from sepsis patients have been characterized. These defects include diminished expression of important cell surface antigens, dysregulated cytokine production, alterations in antigen-presenting ability, and accelerated apoptosis. Impaired leukocyte function has important clinical ramifications, as high mortality rates have been observed in patients displaying evidence of sepsis-induced immune deactivation. In this article, we review the current literature supporting evidence of dysregulation of host immunity occurring during sepsis syndrome, characterize the underlying pathophysiology, and describe novel therapeutic interventions directed at augmenting host immunity during sepsis.

Present concepts on the inflammatory modulators with special reference to cytokines

The pro- and anti-inflammatory cytokines create a network of interactions between cells that lead to both stimulatory and inhibitory responses that maintain an effective homeostatic regulation. The anti-inflammatory cytokines are a family of peptides that modulate the pro-inflammatory cytokine response. Cytokines act in concert with non-cytokine mediators, such as prostaglandin E2, glucocorticosteroids, lipocortins, and catecholamines. This review highlights new developments in our understanding of the pathophysiology of inflammation and gives an example of a more recent approach to the modulation of acute systemic inflammatory disorders; activation of beta2-adrenergic receptors on macrophages. In this respect the potent beta2-adrenergic agonist clenbuterol seems of therapeutic interest.

Adrenaline suppression of the macrophage nitric oxide response to lipopolysaccharide is associated with differential regulation of tumour necrosis factor-alpha and interleukin-10

Adrenaline is a catecholamine hormone secreted by the adrenal medulla in response to acute stress. Previous studies have shown that adrenaline suppresses the nitric oxide (NO) response of murine macrophages (M phi s) stimulated in vitro with lipopolysaccharide (LPS). We have now extended these studies to examine the effects of adrenaline on the production of tumour necrosis factor alpha (TNF-alpha) and interleukin-10 (IL-10). Our results showed that NO, TNF-alpha and IL-10 were concurrently produced following in vitro LPS (10 micrograms/ml) stimulation of murine peritoneal M phi s. Adrenaline suppressed both NO and TNF-alpha with concomitant up-regulation of the IL-10 response above that seen with LPS alone. In this in vitro model of LPS stimulation we demonstrated that TNF-alpha was required for NO production, as the TNF-alpha neutralizing monoclonal antibody, TN3.19.12, abolished the response; in contrast, IL-10 suppressed NO. In order to determine any functional consequence of adrenaline-mediated IL-10 augmentation on NO production, M phi s were stimulated with LPS and specific neutralizing anti-IL-10 antibodies were added to the cultures. The LPS NO response was suppressed to 43% of the control value by adrenaline (10(-8) M) and an irrelevant control antibody had no effect on the adrenaline-mediated inhibition of NO, but anti-IL-10 treatment restored the NO response to levels similar to those observed with LPS alone. Furthermore, we demonstrated that exogenous TNF-alpha, at a dose range of 1.9-50 ng per ml, also restored the nitrite response to LPS in the presence of adrenaline. Together, the observations that neutralization of IL-10 and addition of TNF-alpha abrogate adrenaline's inhibition of NO, suggest that this hormone suppresses NO partly through up-regulation of IL-10 which, in turn, may suppress TNF-alpha that is required for NO production. Finally, we also observed that the M phi-activating cytokine, interferon-gamma (IFN-gamma), attenuated the inhibitory effect of adrenaline on the LPS NO response.

Tumor necrosis factor-alpha/interleukin-10 balance in normal and cystic fibrosis children

BACKGROUND

The balance between tumor necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10) is important for immune homeostasis maintenance. Exuberant production of TNF-alpha contributes to overwhelming inflammatory response and tissue damage. But, commonly, increase in TNF-alpha is counterbalanced by simultaneous synthesis of an anti-inflammatory cytokine IL-10, which suppresses production of many activating and regulatory mediators.

AIMS

In the present study, the relationships between TNF-alpha and IL-10 in the plasma of healthy school-children and cystic fibrosis (CF) patients have been investigated.

METHODS

Blood samples were obtained from 12 CF patients with chronic pulmonary disease and 18 healthy schoolchildren vaccinated with live attenuated rubella vaccine. IL-10 and TNF-alpha were determined in the plasma samples using commercially available enzyme-linked immunosorbent assay kits.

RESULTS

Before vaccination, most healthy children (13 of 18) demonstrated superiority of pro-inflammatory TNF-alpha over anti-inflammatory IL-10 (TNF-alpha/IL-10 > 1). In these subjects, a significant positive linear association between the cytokine values has been found. Vaccine challenge resulted in a marked reduction of TNF-alpha/IL-10 ratios. In addition, a disappearance of correlation between the cytokine values was observed. Such disturbance was related to exuberant elevation of the IL-10 levels after inoculation. On the contrary, in CF individuals, plasma cytokine values remained in strong linear association independently of TNF-alpha or IL-10 predominance. No spikes in the plasma levels of IL-10 in CF patients during a 6-month observation period have been revealed.

CONCLUSIONS

There were no fundamental differences between CF and healthy children in the regulation of TNF-alpha and IL-10 secretion. Thus, immune quiescence seemed to be associated with the predominance of TNF-alpha, whereas immune disturbance was characterized by IL-10 superiority. The only abnormality that was found in CF patients consisted of their inability to produce unlimitedly IL-10 in response to antigen stimuli.

Inactivation of catecholamines by superoxide gives new insights on the pathogenesis of septic shock

A major feature of septic shock is the development of a vascular crisis characterized by nonresponsiveness to sympathetic vasoconstrictor agents and the subsequent irreversible fall in blood pressure. In addition, sepsis, like other inflammatory conditions, results in a large increase in the production of free radicals, including superoxide anions (O(2)) within the body. Here we show that O(2) reacts with catecholamines deactivating them in vitro. Moreover, this deactivation would appear to account for the hyporeactivity to exogenous catecholamines observed in sepsis, because administration of a superoxide dismutase (SOD) mimetic to a rat model of septic shock to remove excess O(2) restored the vasopressor responses to norepinephrine. This treatment with the SOD mimetic also reversed the hypotension in these animals; suggesting that deactivation of endogenous norepinephrine by O(2) contributes significantly to this aspect of the vascular crisis. Indeed, the plasma concentrations of both norepinephrine and epinephrine in septic rats treated with the SOD mimetic were significantly higher than in untreated rats. Interestingly, the plasma concentrations for norepinephrine and epinephrine were inversely related to the plasma concentrations of adrenochromes, the product of the autoxidation of catecholamines initiated by O(2). We propose, therefore, that the use of a SOD mimetic represents a new paradigm for the treatment of septic shock. By removing O(2), exogenous and endogenous catecholamines are protected from autoxidation. As a result, both hyporeactivity and hypotension are reversed, generation of potentially toxic adrenochromes is reduced, and survival rate is improved.

Erythromycin inhibits tumor necrosis factor alpha and interleukin 6 production induced by heat-killed Streptococcus pneumoniae in whole blood

To determine the effects of penicillin and erythromycin on cytokine production induced by heat-killed Streptococcus pneumoniae (HKSP), we studied the effects of those drugs on cytokine production induced by S. pneumoniae in human whole blood in vitro and ex vivo. In whole blood in vitro, erythromycin, but not penicillin, caused a dose-dependent decrease in HKSP-induced production of tumor necrosis factor alpha (TNF) and interleukin 6 (IL-6), while the production of IL-10, IL-12, and gamma interferon was inhibited only at the highest erythromycin concentration tested (10(-3) M). The production of TNF and IL-6 in whole blood obtained from healthy subjects after a 30-min infusion of erythromycin (1,000 mg) was lower after ex vivo stimulation with HKSP than that in blood drawn before the infusion. Inhibition of TNF contributed to erythromycin-induced inhibition of IL-6 synthesis. Inhibition of TNF and IL-6 production by erythromycin may have a negative impact on host defense mechanisms during pneumococcal pneumonia.