Adrenergic modulation of survival and cellular immune functions during polymicrobial sepsis

Blockade of sympathetic ganglia improves vascular dysfunction in septic shock

Sepsis/septic shock activates the sympathetic nervous system (SNS) to deal with the infection stress. However, an imbalanced or maladaptive response due to excessive or uncontrolled activation characterizes autonomic dysfunction. Our hypothesis was that reducing this excessive activation of the autonomic nervous system would impact positively in sepsis. Using ganglionic blockers as a pharmacological approach, the main aim of the present report was to assess the role of ganglionic transmission in the vascular dysfunction associated with sepsis.Sepsis was induced in rats by cecal ligation and puncture (CLP). One hour after CLP surgery, rats were treated subcutaneously with hexamethonium (15 mg/kg; ganglionic blocker), pentolinium (5 mg/kg; a blocker with a higher selectivity for sympathetic ganglia compared to hexamethonium), or vehicle (PBS). Basal blood pressure and the response to adrenergic agonists were evaluated at 6 and 24 h after CLP surgery. Reactivity to vasoconstrictors, nitric oxide (NO) synthase 2 (NOS-2) expression, IL-1 and TNF plasma levels, and density of α1 adrenergic receptors were evaluated in the aorta 24 h after CLP.Septic shock resulted in hypotension and hyporesponsiveness to norepinephrine and phenylephrine, increased plasma cytokine levels and NOS-2 expression in the aorta, and decreased α1 receptor density in the same vessel. Pentolinium but not hexamethonium recovered responsiveness and α1 adrenergic receptor density in the aorta. Both blockers normalized the in vivo response to vasoconstrictors, and reduced plasma IL-1 and NOx levels and NOS-2 expression in the aorta.Blockade of ganglionic sympathetic transmission reduced the vascular dysfunction in experimental sepsis. This beneficial effect seems to be, at least in part, due to the preservation of α1 adrenergic receptor density and to reduced NOS-2 expression and may lead to adjuvant ways to treat human sepsis.

The immunomodulatory effects of antihypertensive therapy: A review

Hypertension remains the leading preventable risk factor for stroke and coronary artery disease, significantly contributing to all-cause global mortality and predisposing patients to renal and heart failure, as well as peripheral vascular disease. Due to the widespread usage of antihypertensive drugs, global mean blood pressure has remained unchanged or even slightly decreased over the past four decades. However, considering the broad spectrum of mechanisms involved in the action of antihypertensive drugs and the prevalence of their target receptors on immune cells, possible immunomodulatory effects which may exert beneficial effects of lowering blood pressure but also potentially alter immune function should be considered. In this review, we attempt to assess the consequences to immune system function of administering the five most commonly prescribed groups of antihypertensive drugs and to explain the mechanisms behind those interactions. Finally, we show potential gaps in our understanding of the effects of antihypertensive drugs on patient health. With regard to the widespread use of these drugs in the adult population worldwide, the discussed results may be of vital importance to evidence-based decision-making in daily clinical practice.

The Effect of β-Blockers for Burn Patients on Clinical Outcomes: Systematic Review and Meta-Analysis

OBJECTIVES

To assess the effects and safety of β-blockers in hospitalized patients with burns.

METHODS

A systematic review and meta-analysis of the literature. A broad search was conducted to identify all randomized controlled trials (RCTs) comparing β-blockers to control in hospitalized patients with burns. The primary outcome was 3-month all-cause mortality. Secondary outcomes were clinical patient-relevant end points. We subgrouped results by children/adults and burn severity. Risk of bias was assessed using the individual domain approach.

RESULTS

Four RCTs reported in 11 publications were included. Primary outcome of mortality was assessed in children (2 trials, n = 424) and adults (2 trials, n = 148) with severe burns. No significant difference was found between propranolol and control for mortality (risk ratio [RR] = 0.82, 95% CI = 0.48-1.39, 4 trials with broad confidence intervals in adults and children), sepsis (RR = 0.81, 95% CI = 0.46-1.43, 2 trials), and survivors' length of stay (absolute mean difference = 2.53, 95% CI = -2.58-7.63, 3 trials). There was no significant difference in bradycardia (RR = 1.33, 95% CI = 0.77-2.3, 2 trials), hypotension (RR = 1.26, 95% CI = 0.73-2.17, 3 trials), or cardiac arrhythmia (RR: 2.97, 95% CI: 0.12-71.87, 1 trial). The evidence was graded as very low certainty, due to trial's internal risk of bias, imprecision, and possible selective reporting.

CONCLUSIONS

No sufficient evidence was found to support or refute an advantage for β-blocker use in children or adults after burns. Additional studies are needed to create a consensus and formulate practice guidelines on the optimal β-blocker to use, indications for initiation, and duration of treatment.

Targeting of G-protein coupled receptors in sepsis

The Third International Consensus Definitions (Sepsis-3) define sepsis as life-threatening multi-organ dysfunction caused by a dysregulated host response to infection. Sepsis can progress to septic shock-an even more lethal condition associated with profound circulatory, cellular and metabolic abnormalities. Septic shock remains a leading cause of death in intensive care units and carries a mortality of almost 25%. Despite significant advances in our understanding of the pathobiology of sepsis, therapeutic interventions have not translated into tangible differences in the overall outcome for patients. Clinical trials of antagonists of various pro-inflammatory mediators in sepsis have been largely unsuccessful in the past. Given the diverse physiologic roles played by G-protein coupled receptors (GPCR), modulation of GPCR signaling for the treatment of sepsis has also been explored. Traditional pharmacologic approaches have mainly focused on ligands targeting the extracellular domains of GPCR. However, novel techniques aimed at modulating GPCR intracellularly through aptamers, pepducins and intrabodies have opened a fresh avenue of therapeutic possibilities. In this review, we summarize the diverse roles played by various subfamilies of GPCR in the pathogenesis of sepsis and identify potential targets for pharmacotherapy through these novel approaches.

The Central Role of the Inflammatory Response in Understanding the Heterogeneity of Sepsis-3

In sepsis-3, in contrast with sepsis-1, the definition "systemic inflammatory response" has been replaced with "dysregulated host response", and "systemic inflammatory response syndrome" (SIRS) has been replaced with "sequential organ failure assessment" (SOFA). Although the definition of sepsis has changed, the debate regarding its nature is ongoing. What are the fundamental processes controlling sepsis-induced inflammation, immunosuppression, or organ failure? In this review, we discuss the heterogeneity of sepsis-3 and address the central role of inflammation in the pathogenesis of sepsis. An unbalanced pro- and anti-inflammatory response, inflammatory resolution disorder, and persistent inflammation play important roles in the acute and/or chronic phases of sepsis. Moreover, powerful links exist between inflammation and other host responses (such as the neuroendocrine response, coagulation, and immunosuppression). We suggest that a comprehensive evaluation of the role of the inflammatory response will improve our understanding of the heterogeneity of sepsis.

Cervical Spinal Cord Injury Shows Markedly Lower than Predicted Mortality (>72 Hours After Multiple Trauma) From Sepsis and Multiple Organ Failure

BACKGROUND

Sepsis and multiple organ failure (MOF) remain one of the main causes of death after multiple trauma. Trauma- and infection-associated immune reactions play an important role in the pathomechanism of MOF, but the exact pathways remain unknown. Spinal cord injury (SCI) may lead to an altered immune response, and some studies suggest a prognostic advantage for such patients having sepsis or multiple trauma. Yet these findings need to be evaluated in larger cohorts of trauma patients.

METHODS

Retrospective, multicenter study, using the data of the TraumaRegister DGU. Patients with and without SCI surviving the initial first 72 hours after trauma were matched according to injury pattern and age. Comparative analysis considered morbidity (sepsis, MOF) and hospital mortality.

RESULTS

The study population included 800 matched pairs. As intended by the matching process, patients with cervical SCI had an otherwise comparable injury pattern but a higher severity of trauma (mean Injury Severity Score: 36 vs 29, mean number of diagnosis: 5.6 vs 4.4). They had a higher rate of sepsis (15.9% vs 10.9%, P = .005) and MOF (35.9% vs 24.1%, P < .001) while mortality revealed no significant difference (9.5% vs 9.9%, P = .866).

CONCLUSIONS

Cervical SCI leads to an increased rate of sepsis and MOF but appears to be favorable with respect to outcome of sepsis and MOF following multiple trauma. Further research should focus on the pathomechanisms and the possible arising therapeutic options.

β-Blocker use is associated with a higher relapse risk of inflammatory bowel disease: a Dutch retrospective case-control study

OBJECTIVE

Inflammatory bowel disease (IBD) is a multifactorial disease and many factors may influence the disease course, like the concomitant use of medication. An example thereof is the use of β-blockers, antagonizing β-adrenergic receptors. β-adrenergic receptor activation has potent anti-inflammatory effects on the immune system. We addressed whether an association exists between the use of beta-blockers and the course of IBD, defined by the risk of a disease relapse in patients with IBD.

PATIENTS AND METHODS

In this retrospective case-control study, we used a population-based cohort of patients with IBD. We identified colitis relapses using IBD medication prescriptions as a proxy. We calculated the number of relapses per 100 person-years and compared this between patients with IBD using β-blockers and patients with IBD not using β-blockers. We used Cox proportional hazards models with shared frailty to compare the relative relapse risk between both groups.

RESULTS

A total of 250 patients with IBD were included, of which 30 patients used a β-blocker for at least 3 months. With the Cox proportional hazards model with shared frailty, adjusted for age and sex, we observed a 54% (hazard ratio: 1.54; 95% confidence interval: 1.05-2.25; P=0.03) higher risk of a relapse in the group of patients with IBD using β-blockers versus the group not using β-blockers.

CONCLUSION

Even in this limited cohort study, we show that patients with IBD using β-blockers have an increased relapse risk. Indeed, concomitant medication use seems to be a factor that can influence the course of IBD, and this should be acknowledged while making decisions about treatment of IBD and follow-up.

The neuroendocrine immunomodulatory axis-like pathway mediated by circulating haemocytes in pacific oyster Crassostrea gigas

The neuroendocrine-immune (NEI) regulatory network is a complex system, which plays an indispensable role in the immunity of host. In this study, a neuroendocrine immunomodulatory axis (NIA)-like pathway mediated by the nervous system and haemocytes was characterized in the oyster Crassostrea gigas. Once invaded pathogen was recognized by the host, the nervous system would temporally release neurotransmitters to modulate the immune response. Instead of acting passively, oyster haemocytes were able to mediate neuronal immunomodulation promptly by controlling the expression of specific neurotransmitter receptors on cell surface and modulating their binding sensitivities, thus regulating intracellular concentration of Ca²⁺. This neural immunomodulation mediated by the nervous system and haemocytes could influence cellular immunity in oyster by affecting mRNA expression level of TNF genes, and humoral immunity by affecting the activities of key immune-related enzymes. In summary, though simple in structure, the ‘nervous-haemocyte’ NIA-like pathway regulates both cellular and humoral immunity in oyster, meaning a world to the effective immune regulation of the NEI network.

Neuroendocrine Modulation of IL-27 in Macrophages

Heterodimeric IL-27 (p28/EBV-induced gene 3) is an important member of the IL-6/IL-12 cytokine family. IL-27 is predominantly synthesized by mononuclear phagocytes and exerts immunoregulatory functional activities on lymphocytic and nonlymphocytic cells during infection, autoimmunity or neoplasms. There is a great body of evidence on the bidirectional interplay between the autonomic nervous system and immune responses during inflammatory disorders, but so far IL-27 has not been defined as a part of these multifaceted neuroendocrine networks. In this study, we describe the role of catecholamines (as mediators of the sympathetic nervous system) related to IL-27 production in primary mouse macrophages. Noradrenaline and adrenaline dose-dependently suppressed the release of IL-27p28 in LPS/TLR4-activated macrophages, which was independent of α₁ adrenoceptors. Instead, β₂ adrenoceptor activation was responsible for mediating gene silencing of IL-27p28 and EBV-induced gene 3. The β₂ adrenoceptor agonists formoterol and salbutamol mediated suppression of IL-27p28 production, when triggered by zymosan/TLR2, LPS/TLR4, or R848/TLR7/8 activation, but selectively spared the polyinosinic-polycytidylic acid/TLR3 pathway. Mechanistically, β₂ adrenergic signaling reinforced an autocrine feedback loop of macrophage-derived IL-10 and this synergized with inhibition of the JNK pathway for limiting IL-27p28. The JNK inhibitors SP600125 and AEG3482 strongly decreased intracellular IL-27p28 in F4/80⁺CD11b⁺ macrophages. In endotoxic shock of C57BL/6J mice, pharmacologic activation of β₂ adrenoceptors improved the severity of shock, including hypothermia and decreased circulating IL-27p28. Conversely, IL-27p28 was 2.7-fold increased by removal of the catecholamine-producing adrenal glands prior to endotoxic shock. These data suggest a novel role of the sympathetic neuroendocrine system for the modulation of IL-27-dependent acute inflammation.

Safety and effectiveness of propranolol in severely burned patients: systematic review and meta-analysis

BACKGROUND

The objective of this systematic review was to determine the effectiveness and safety of propranolol compared to placebo or usual care for improving clinical relevant outcomes in severely burned patients (TBSA >20%).

METHODS

Relevant articles from randomized controlled trials were identified by a literature search in MEDLINE, EMBASE, and CENTRAL. We included trials involving patients with a severe burn (>20% of total body surface area affected). Trials were eligible if they evaluated propranolol and compared to usual care or placebo. Two investigators independently assessed articles for inclusion and exclusion criteria and selected studies for the final analysis. We conducted a meta-analysis using a random-effects model.

RESULTS

We included ten studies in our systematic review. These studies randomized a total of 1236 participants. There were no significant differences between propranolol and placebo with respect to mortality (RD -0.02 [95% CI -0.06 to 0.02]), sepsis (RD -0.03 [95% CI -0.09 to 0.04]), and the overall hospital stay (MD -0.37 [-4.52 to 3.78]). Propranolol-treated adults had a decrease in requirements of blood transfusions (MD -185.64 [95% CI -331.06 to -40.43]) and a decreased heart rate (MD -26.85 [95% CI -39.95 to -13.75]).

CONCLUSIONS

Our analysis indicates that there were no differences in mortality or sepsis in severely burned patients treated with propranolol compared with those who had usual care or placebo. However, the use of propranolol in these patients resulted in lower requirements of blood transfusion and lower values of heart rate. The evidence synthesized in this systematic review is limited to conclude that propranolol reduces the length of hospital stay among severely burned patients. Future trials should assess the impact of propranolol on clinically relevant outcomes such as mortality and adverse events.

Adjunctive treatment in septic shock: What's next?

Sepsis is a leading cause of death and long-term sequels worldwide. For more than a decade, the scientific community is providing physicians, patients and policy makers with regularly updated guidelines. There is some evidence that implementation of the Surviving Sepsis Campaign guidelines is associated with improved patients outcomes. Though there were major advances in the understanding of sepsis, the management of sepsis mainly relies on anti-infective treatments and restoration of cardiovascular and respiratory function according to quantitative protocolized care. Except some hormonal interventions such as insulin to maintain blood glucose levels of less than 180mg/dL and low doses of corticosteroids and vasopressin in highly selected patients, there is no adjunct therapy for the routine management of sepsis. Recent years have shown some interest in revolutionary concepts such as selective beta-1 receptor antagonists or interventions to boost the immune system. These provocative approaches yielded promising results in various experimental models of sepsis and in preliminary data in humans. The current narrative review summarized some of the numerous adjunct therapies that are currently being investigated in sepsis.

The sympathetic nervous response in inflammation

Over the past decades evidence has accumulated clearly demonstrating a pivotal role for the sympathetic nervous system (SNS) and its neurotransmitters in regulating inflammation. The first part of this review provides the reader with an overview showing that the interaction of the SNS with the immune system to control inflammation is strongly context-dependent (for example, depending on the activation state of the immune cell or neuro-transmitter concentration). In the second part we focus on autoimmune arthritis as a well investigated example for sympathetically controlled inflammation to show that the SNS and catecholamines play a differential role depending on the time point of ongoing disease. A model will be developed to explain the proinflammatory effects of the SNS in the early phase and the anti-inflammatory effects of catecholamines in the later phase of autoimmune arthritis. In the final part, a conceptual framework is discussed that shows that a major purpose of increased SNS activity is nourishment of a continuously activated immune system at a systemic level using energy-rich fuels (glucose, amino acids, lipids), while uncoupling from central nervous regulation occurs at sites of inflammation by repulsion of sympathetic fibers and local adrenoceptor regulation. This creates zones of ‘permitted local inflammation’. However, if this ‘inflammatory configuration’ persists and is strong, as in autoimmunity, the effects are detrimental because of the resultant chronic catabolic state, leading to cachexia, high blood pressure, insulin resistance, and increased cardiovascular mortality, and so on. Today, the challenge is to translate this conceptual knowledge into clinical benefit.

Is It Time to Beta Block the Septic Patient?

Beta blockers are some of the most studied drugs in the pharmacopoeia. They are already widely used in medicine for treating hypertension, chronic heart failure, tachyarrhythmias, and tremor. Whilst their use in the immediate perioperative patient has been questioned, the use of esmolol in the patients with established septic shock has been recently reported to have favourable outcomes. In this paper, we review the role of the adrenergic system in sepsis and the evidence for the use of beta stimulation and beta blockers from animal models to critically ill patients.

Do β-Blockers Decrease the Hypermetabolic State in Critically Ill Children With Severe Burns?

BACKGROUND AND OBJECTIVES

Severe burns result in a hypermetabolic state that is associated with increased morbidity and mortality. We reviewed the literature to determine if there is strong evidence that short-term β-blockers reduce the hypermetabolic state or mortality and length of stay (LOS) compared with no therapy in patients with severe burns.

METHODS

A literature search of PubMed, Embase, the Cochrane Database of Systematic Reviews, and BestBETs was conducted on the use of adrenergic β-antagonists in burn patients.

RESULTS

Six randomized controlled trials met the inclusion criteria. Five pediatric trials found that β-blockers reduced the hypermetabolic state (as defined by reduction of cardiac work, rate pressure product, resting energy expenditure, central deposition of fat, and bone mineral loss) and were associated with an improvement in lean muscle mass in patients with severe burns. However, there was no change in LOS or mortality in these children. One adult study in burn patients found shorter LOS in patients treated with β-blockers but no difference in mortality rate. β-blockers were relatively well tolerated, with no differences in adverse effects reported.

CONCLUSIONS

β-blockers seem to reduce the hypermetabolic state in pediatric patients with burns, but there is insufficient evidence to suggest they have an impact on mortality rates or LOS.

Chlorisondamine, a sympathetic ganglionic blocker, moderates the effects of whole-body irradiation (WBI) on early host defense to a live bacterial challenge

There is a growing consensus that long-term deficits in the brain are due to dynamic interactions between multiple neural and immune cell types. Specifically, radiation induces an inflammatory response, including changes in neuromodulatory pro- and anti-inflammatory cytokine secretion. The purpose of this study was to establish that there is sympathetic involvement in radiation-induced decrements early in in vivo immune function host defense. Female, 8-9 week-old C57BL/6J mice were exposed to whole-body irradiation (WBI). There were 8 groups with radiation (0 vs. 3 Gy protons), immune challenge (Escherichia coli) and exposure to the sympathetic ganglionic blocker, chlorisondamine (1 mg/kg weight, i.p.), as independent variables. Ten days post-irradiation, mice were inoculated with E. coli intraperitoneally and sacrificed 90-120 min later. The data suggest that radiation-induced changes in immune function may in part be mediated by the sympathetic nervous system. Briefly, we found that radiation augments the bacteria-induced inflammatory cytokine response, particularly those cytokines involved in innate immunity. However, this augmentation can be reduced by the ganglionic blockade.

Beta-blockers in septic shock: a review

In septic shock, high adrenergic stress is associated with cardiovascular and systemic adverse effects, which can negatively affect the results. Beta-adrenergic receptor block has been shown to be effective in controlling the disproportionate increase in heart rate, maintaining a favorable hemodynamic profile and apparently improving the efficiency of the cardiovascular system in order to maintain tissue perfusion. They have also been shown to modulate favorably catecholamine-induced immunosuppression and to decrease insulin resistance, protein catabolism, and proinflammatory cytokine expression associated with cardiovascular dysfunction. Selective beta-1 blockers appear to provide better results than non-selective blockers, even suggesting a positive impact on mortality. Future clinical trials are still needed to confirm these findings and define the scope of their benefits.

Beta-blocker use in severe sepsis and septic shock: a systematic review

OBJECTIVE

Recent growing evidence suggests that beta-blocker treatment could improve cardiovascular dynamics and possibly the outcome of patients admitted to intensive care with severe sepsis or septic shock.

DESIGN

Systematic review.

DATA SOURCES

MEDLINE and EMBASE healthcare databases.

REVIEW METHODS

To investigate this topic, we conducted a systematic review of the above databases up to 31 May 2015. Due to the clinical novelty of the subject, we also included non-randomized clinical studies. We focused on the impact of beta-blocker treatment on mortality, also investigating its effects on cardiovascular, immune and metabolic function. Evidence from experimental studies was reviewed as well.

RESULTS

From the initial search we selected 10 relevant clinical studies. Five prospective studies (two randomized) assessed the hemodynamic effects of the beta1-blocker esmolol. Heart rate decreased significantly in all, but the impact on other parameters differed. The imbalance between prospective studies' size (10 to 144 patients) and the differences in their design disfavor a meta-analysis. One retrospective study showed improved hemodynamics combining metoprolol and milrinone in septic patients, and another retrospective study found no association between beta-blocker administration and mortality. We also found three case series. Twenty-one experimental studies evaluated the hemodynamic, immune and/or metabolic effects of selective and/or non-selective beta-blockers in animal models of sepsis (dogs, mice, pigs, rats, sheep), yielding conflicting results.

CONCLUSIONS

Whilst there is not enough prospective data to conduct a meta-analysis, the available clinical data are promising. We discuss the ability of beta blockade to modulate sepsis-induced alterations at cardiovascular, metabolic, immunologic and coagulation levels.

Role of p53 in cAMP/PKA pathway mediated apoptosis

Deregulated β-adrenoceptor/cAMP-PKA pathway is implicated in a range of human diseases, such as neuronal loss during aging, cardiomyopathy and septic shock. The molecular mechanism of this process is, however, only poorly understood. We recently had demonstrated that the β-adrenoceptor/cAMP-PKA pathway triggers apoptosis through the transcriptional induction of the pro-apoptotic BH3-only Bcl-2 family member BIM in tissues, such as the thymus and the heart. Induction of BIM is driven by the transcriptional co-activator CBP (CREB Binding Protein) together with the proto-oncogene c-Myc. Association of CBP with c-Myc leads to altered histone acetylation and methylation pattern at the BIM promoter site [Lee et al., Cell Death Difference 20(7):941-952 (2013)]. However since CBP is a co-factor for multiple transcription factors, BH-3 only proteins other than Bim could also contribute to this apoptosis pathway. Here we provide evidence for the involvement of p53-CBP axis in apoptosis through Puma/Noxa induction, in response to β-adrenoceptor activation. Our findings highlight the molecular complexity of pathophysiology associated with a deregulated neuro-endocrine system and for developing novel therapeutic strategies for these diseases.

Dobutamine pretreatment improves survival, liver function, and hepatic microcirculation after polymicrobial sepsis in rat

Dobutamine is recommended for the treatment of sepsis-related circulatory failure in international guidelines. Furthermore, dobutamine has been demonstrated to improve liver function and hepatic perfusion after experimental hemorrhagic shock. Yet, it is unknown whether dobutamine may also induce hepatoprotective effects in sepsis. This study was designed to investigate the effect of dobutamine on survival, hepatic function, and microcirculation after polymicrobial sepsis in rat. Under general anesthesia, male Sprague-Dawley rats (n = 25/group) underwent pretreatment with dobutamine (10 μg/kg per minute) in the presence or absence of β1-receptor antagonist esmolol (500 μg/kg per minute), esmolol alone, or vehicle for 6 h, before induction of sepsis (cecal ligation and incision [CLI]). Sham-operated animals were treated likewise but underwent no CLI. Five hours after CLI, either liver function was assessed by plasma disappearance rate of indocyanine green (n = 5/group), or intravital microscopy was performed (n = 5/group) for evaluation of hepatic perfusion index and hepatic integrity (as propidium iodide-stained cells per field). Alternatively, survival time after induction of CLI was monitored under general anesthesia (n = 15/group). Compared with controls, dobutamine pretreatment significantly improved plasma disappearance rate of indocyanine green (13.8% ± 4.1% vs. 20.6% ± 4.6%; P = 0.029), hepatic perfusion index (275.0 ± 126.1 vs. 703.5 ± 177.4 pL/s per mm; P < 0.001), hepatocellular injury (22.2 ± 6.7 vs. 6.4 ± 3.1 cells per field; P < 0.001), and survival time (326 ± 20 vs. 603 ± 41 min; P < 0.001). Coadministration of esmolol abolished the protective effect of dobutamine completely. Our results indicate that pretreatment with dobutamine may improve survival, liver function, and hepatic microcirculation after polymicrobial sepsis in rat via β1-adrenoceptor activation. Dobutamine could therefore play a relevant role for hepatoprotection under septic conditions.

Hospital-acquired infections and thermally injured patients: chlorhexidine gluconate baths work

BACKGROUND

Thermally injured patients are at high risk for infections, including hospital acquired infections (HAIs). We modeled a twice-daily chlorhexidine gluconate (CHG) bath protocol aimed at decreasing HAIs.

METHODS

Bathing with a 0.9% CHG solution in sterile water was provided twice daily as part of routine care. Institutional HAI prevention bundles were in place and did not change during the study. Baseline HAI rates were collected for 12 months before the quality study implementation. Centers for Disease Control and Prevention definitions for HAIs were used; our blinded Infection Control physician made each determination. This was an Institutional Review Board-exempt protocol.

RESULTS

The study cohort included 203 patients before the quality trial and 277 patients after the quality trial. The median burn area was 25% of total body surface area. Baseline HAI rates were as follows: ventilator-associated pneumonia, 2.2 cases/1,000 ventilator-days; cathether-associated urinary tract infection, 2.7 cases/1,000 catheter-days; central line-associated bloodstream infection, 1.4 cases/1,000 device-days. With implementation of this protocol, the rates dropped to zero and have stayed at that level with the exception of 1 cathether-associated urinary tract infection. There were no untoward effects or observed delays in wound healing with this protocol. All of these changes were clinically significant, although not statistically significant; the study was not powered for statistical significance.

CONCLUSIONS

Using this nurse-driven protocol, we decreased, in a sustainable manner, the HAI rate in our intensive care unit to zero. No integumentary difficulties or wound healing delays were related to this protocol.

The endocrine response to severe burn trauma

The endocrine system is frequently altered after a major burn trauma. Besides the endocrine response to stress characterized by hypercortisolism, several hypothalamus-hypophysis-target gland axes are rapidly perturbed within a few days. These alterations can persist in the long term and deserve an appropriate treatment. Disturbances in water clearance and glucidic metabolism are also common and need to be diagnosed and corrected to decrease morbidity in such patients. Bone and mineral metabolism is deeply compromised and requires correction of mineral abnormalities in order to improve symptoms and prevent bone loss. No large prospective and/or intervention trials are available to date to elaborate age-related, evidence-based recommendations to monitor and treat burn-related endocrine alterations.

CREB-binding protein (CBP) regulates β-adrenoceptor (β-AR)-mediated apoptosis

Catecholamines regulate the β-adrenoceptor/cyclic AMP-regulated protein kinase A (cAMP/PKA) pathway. Deregulation of this pathway can cause apoptotic cell death and is implicated in a range of human diseases, such as neuronal loss during aging, cardiomyopathy and septic shock. The molecular mechanism of this process is, however, only poorly understood. Here we demonstrate that the β-adrenoceptor/cAMP/PKA pathway triggers apoptosis through the transcriptional induction of the pro-apoptotic BH3-only Bcl-2 family member Bim in tissues such as the thymus and the heart. In these cell types, the catecholamine-mediated apoptosis is abrogated by loss of Bim. Induction of Bim is driven by the transcriptional co-activator CBP (CREB-binding protein) together with the proto-oncogene c-Myc. Association of CBP with c-Myc leads to altered histone acetylation and methylation pattern at the Bim promoter site. Our findings have implications for understanding pathophysiology associated with a deregulated neuroendocrine system and for developing novel therapeutic strategies for these diseases.

Burns: an update on current pharmacotherapy

INTRODUCTION

The worldwide occurrence of burn injuries remains high despite efforts to reduce injury incidence through public awareness campaigns and improvements in living conditions. In 2004, almost 11 million people experienced burns severe enough to warrant medical treatment. Advances over the past several decades in aggressive resuscitation, nutrition, excision and grafting have reduced morbidity and mortality. Incorporation of pharmacotherapeutics into treatment regimens may further reduce complications of severe burn injuries.

AREAS COVERED

Severe burn injuries, as well as other forms of stress and trauma, trigger a hypermetabolic response that, if left untreated, impedes recovery. In the past two decades, use of anabolic agents, β-adrenergic receptor antagonists and anti-hyperglycemic agents has successfully counteracted post-burn morbidities including catabolism, the catecholamine-mediated response and insulin resistance. Here, the authors review the most up-to-date information on currently used pharmacotherapies in the treatment of these sequelae of severe burns and the insights that have expanded the understanding of the pathophysiology of severe burns.

EXPERT OPINION

Existing drugs offer promising advances in the care of burn injuries. Continued gains in the understanding of the molecular mechanisms driving the hypermetabolic response will enable the application of additional existing drugs to be broadened to further attenuate the hypermetabolic response.

Long-term propranolol use in severely burned pediatric patients: a randomized controlled study

OBJECTIVE

To determine the safety and efficacy of propranolol given for 1 year on cardiac function, resting energy expenditure, and body composition in a prospective, randomized, single-center, controlled study in pediatric patients with large burns.

BACKGROUND

Severe burns trigger a hypermetabolic response that persists for up to 2 years postburn. Propranolol given for 1 month postburn blunts this response. Whether propranolol administration for 1 year after injury provides a continued benefit is currently unclear.

METHODS

One-hundred seventy-nine pediatric patients with more than 30% total body surface area burns were randomized to control (n = 89) or 4 mg/kg/d propranolol (n = 90) for 12 months postburn. Changes in resting energy expenditure, cardiac function, and body composition were measured acutely at 3, 6, 9, and 12 months postburn. Statistical analyses included techniques that adjusted for non-normality, repeated-measures, and regression analyses. P < 0.05 was considered significant.

RESULTS

Long-term propranolol treatment significantly reduced the percentage of the predicted heart rate and percentage of the predicted resting energy expenditure, decreased accumulation of central mass and central fat, prevented bone loss, and improved lean body mass accretion. There were very few adverse effects from the dose of propranolol used.

CONCLUSIONS

Propranolol treatment for 12 months after thermal injury, ameliorates the hyperdynamic, hypermetabolic, hypercatabolic, and osteopenic responses in pediatric patients. This study is registered at clinicaltrials.gov: NCT00675714.

Sedation & immunomodulation

As the armamentarium for sedation in the critically ill expands, opportunities will develop to modulate the immune responses of patients by way of the direct immune and neural-immune interactions of the sedatives. Control of autonomic activity through the use of appropriate sedation may be critical in this matter. Likewise analgesic-based sedation, with increased opioid dosage, may not prove beneficial in the setting of infection; whether avoidance of morphine in preference for a fentanyl derivative will help is unclear. However, as the immune effects seem dependent on the m receptor, it is improbable that a significant difference would be uncovered. Similarly, the present evidence suggests benzodiazepines are deleterious in infection; further studies are required urgently to evaluate this evidence. As an alternative to benzodiazepine-based sedation, dexmedetomidine has shown a remarkable 70% mortality benefit in a small secondary analysis of septic patients from the MENDS trial. Further powered clinical studies should now be undertaken to investigate the potential benefit of the α2-adrenoceptor agonist in this setting, with comparisons with propofol.

Bench-to-bedside review: Beta-adrenergic modulation in sepsis

Sepsis, despite recent therapeutic progress, still carries unacceptably high mortality rates. The adrenergic system, a key modulator of organ function and cardiovascular homeostasis, could be an interesting new therapeutic target for septic shock. β-Adrenergic regulation of the immune function in sepsis is complex and is time dependent. However, β₂ activation as well as β₁ blockade seems to downregulate proinflammatory response by modulating the cytokine production profile. β₁ blockade improves cardiovascular homeostasis in septic animals, by lowering myocardial oxygen consumption without altering organ perfusion, and perhaps by restoring normal cardiovascular variability. β-Blockers could also be of interest in the systemic catabolic response to sepsis, as they oppose epinephrine which is known to promote hyperglycemia, lipid and protein catabolism. The role of β-blockers in coagulation is less clear cut. They could have a favorable role in the septic pro-coagulant state, as β₁ blockade may reduce platelet aggregation and normalize the depressed fibrinolytic status induced by adre-nergic stimulation. Therefore, β₁ blockade as well as β₂ activation improves sepsis-induced immune, cardiovascular and coagulation dysfunctions. β₂ blocking, however, seems beneficial in the metabolic field. Enough evidence has been accumulated in the literature to propose β- adrenergic modulation, β₁ blockade and β₂ activation in particular, as new promising therapeutic targets for septic dyshomeostasis, modulating favorably immune, cardiovascular, metabolic and coagulation systems.

In vitro sensitivity of leukemia cells to propranolol

Background

Propranolol, as a beta-adrenergic blocker is used for treatment of a large number of cardiovascular diseases such as hypertension and arrhythmias. The inhibitory effects of propranolol on tumor cells growth and also its cytotoxicity on cancerous cells have been revealed by several studies. In this study the sensitivity of a number of human leukemic cell lines to propranolol was evaluated in vitro.

Methods

Two human leukemic T cells (Molt-4 and Jurkat) and a monocyte (U937) cell line were used in this study. The cells were cultured in complete RPMI medium and then incubated with different concentrations of propranolol (0.0004 -0.4 mM) in the presence or absence of phytoheamagglutinin (20 μg/ml) for 12, 24 and 48 hours. The cytotoxic effect of the drug was then assessed by trypan blue dye exclusion and also 3-(4,5-dimethyl thiazol-2,5-diphenyltetrazoliumbromide) (MTT) reduction methods.

Results

Propranolol induced a significant dose dependent cytotoxic effect at ≥ 0.2 mM concentration on all three human cell lines (Molt-4, Jurkat and U937) used in this study, after 12 hours incubation onwards, compared to untreated control cells.

Conclusions

Our results demonstrated that leukemic cell lines used in this study were sensitive to propranolol at ≥ 0.2 mM concentration of the drug. These results suggest that propranolol may have potential implication in chemoprevention of lymphoproliferative disorders along with its chronic long-term usage in cardiac problems.

Keywords

Propranolol; Leukemia; Cell lines; Sensitivity

Sedation & immunomodulation

The management of critically ill patients necessitates the use of sedatives and analgesics to provide patient comfort and cooperation. These drugs exert profound effects on all organ systems, not only the central nervous system, and this article describes the immunologic effects of the commonly used critical care sedatives: propofol, the benzodiazepines, opioids, and alpha(2)-adrenoceptor agonists. Benzodiazepines, opioids, and possibly even propofol worsen outcome in animal models of infection, whereas preliminary evidence suggests that the alpha(2)-adrenoceptor agonist, dexmedetomidine, may improve outcomes in the setting of infection. Given the burden of sepsis and secondary infections in critical care, choice of sedation may need to be carefully considered to preserve immune responses in critically ill patients.

beta-Blockers in sepsis: reexamining the evidence

Sepsis remains the leading cause for noncardiac intensive care unit deaths in the United States. Despite recent advances in the treatment of this devastating condition, mortality and morbidity remain unacceptably high. Sepsis is characterized by a multitude of pathophysiological changes that include inflammation, metabolic derangements, hemodynamic alterations, and multiorgan dysfunction. Unfortunately, several studies of treatment modalities aimed at correcting one or more of the underlying derangements have led to disappointing results. New treatment modalities are needed. beta-Receptor blockers have long been used for a variety of conditions such as coronary artery disease, congestive heart failure, and arterial hypertension. Recent data suggest that beta-blocker effects on metabolism, glucose homeostasis, cytokine expression, and myocardial function may be beneficial in the setting of sepsis. Although treating a potentially hypotensive condition with a drug with antihypertensive properties may initially seem counterintuitive, the metabolic and immunomodulatory properties of beta-blockers may be of benefit. It is the purpose of this review to discuss the effects of beta-blockers on the following: (1) metabolism, (2) glucose regulation, (3) the inflammatory response, (4) cardiac function, and (5) mortality in sepsis.

Harmful molecular mechanisms in sepsis

Sepsis and sepsis-associated multi-organ failure are major challenges for scientists and clinicians and are a tremendous burden for health-care systems. Despite extensive basic research and clinical studies, the pathophysiology of sepsis is still poorly understood. We are now beginning to understand that sepsis is a heterogeneous, dynamic syndrome caused by imbalances in the 'inflammatory network'. In this Review, we highlight recent insights into the molecular interactions that occur during sepsis and attempt to unravel the nature of the dysregulated immune response during sepsis.

Catecholamines-crafty weapons in the inflammatory arsenal of immune/inflammatory cells or opening pandora's box?

It is well established that catecholamines (CAs), which regulate immune and inflammatory responses, derive from the adrenal medulla and from presynaptic neurons. Recent studies reveal that T cells also can synthesize and release catecholamines which then can regulate T cell function. We have shown recently that macrophages and neutrophils, when stimulated, can generate and release catecholamines de novo which, then, in an autocrine/paracrine manner, regulate mediator release from these phagocytes via engagement of adrenergic receptors. Moreover, regulation of catecholamine-generating enzymes as well as degrading enzymes clearly alter the inflammatory response of phagocytes, such as the release of proinflammatory mediators. Accordingly, it appears that phagocytic cells and lymphocytes may represent a major, newly recognized source of catecholamines that regulate inflammatory responses.

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.

Effect of restraint stress on the population of intestinal intraepithelial lymphocytes in mice

The impact of restraint stress on the intestinal immune system, particularly on intestinal intraepithelial lymphocytes (i-IEL), has not been described in detail. Thus, the purpose of this study was to assess the effects of restraint stress, including those produced by increases in glucocorticoids and catecholamines, on the population of i-IEL. Mice were exposed to 1 or 4h restraint stress for 4 day, and the number of IEL in the mucosa of the proximal small intestine was determined by immunohistochemistry. The effects of restraint were also analyzed in mice submitted to different procedures: adrenalectomy, chemical sympathectomy, and treatment with a glucocorticoid antagonist (RU486), dexamethasone, and epinephrine. The main findings were that: (1) chronic restraint-stress reduced the i-IEl population in the small intestine; (2) adrenalectomy, treatment with RU-486 and chemical sympathectomy decreased the number of gammadelta, CD4+ and CD8+ T cells in non-stressed groups; (3) dexamethasone reduced the number of gammadelta and CD8+ T cells, and (4) epinephrine reduced the number of gammadelta, CD4+ and CD8+ T cells. These results demonstrated that restraint stress decreased the number of i-IEL in the proximal small intestine of mice, mainly by the combined action of higher concentrations of catecholamines and glucocorticoids, and that lower concentrations of glucocorticoids and catecholamines in unstressed mice preserved the population of i-IEL.

Propranolol does not increase inflammation, sepsis, or infectious episodes in severely burned children

BACKGROUND

Propranolol, a nonselective beta1-2 antagonist, attenuates hypermetabolism and catabolism in severely burned patients. However, recent data suggest that propranolol impairs immune function and enhances inflammation. The purpose of the present study was to determine the effect of propranolol administration on infection, sepsis, and inflammation in severely burned pediatric patients.

PATIENTS

A prospective, intent-to-treat study was performed; patient demographics (age, gender, burn size, and mortality); infectious episodes (colony count greater then 10); and sepsis (guidelines by the society of critical care medicine) were determined. Hypermetabolic response was determined by resting energy expenditure (REE), and the inflammatory response was determined by measuring serum cytokine expression.

RESULTS

Two hundred forty-five patients (143 controls, 102 propranolol) were included into the study. There were no differences between the control and propranolol groups for age, gender distribution, burn size, third degree burn, and length of stay. Mortality was 6% in the control group and 5% in the propranolol group. Propranolol significantly decreased REE and predicted REE during acute hospital stay. Forty-three patients developed infections in the control group (30%), whereas 21 developed infections in the propranolol group (21%). The incidence of sepsis was 10% for controls and 7% for propranolol. Analysis of the cytokine expression profile in 20 patients in each group revealed that propranolol significantly decreased serum tumor necrosis factor and interleukin-1beta compared with controls (p < 0.05).

CONCLUSION

Propranolol treatment attenuates hypermetabolism and does not cause increased incidence of infection and sepsis.

Myocardial lactate deprivation is associated with decreased cardiovascular performance, decreased myocardial energetics, and early death in endotoxic shock

OBJECTIVE

We examined whether lactate availability is a limiting factor for heart function during endotoxic shock, and whether lactate deprivation thus induces heart energy depletion, thereby altering cardiovascular performance. The study goals were to determine whether muscle lactate production is linked to beta(2)-stimulation and to ascertain the effects of systemic lactate deprivation on hemodynamics, lactate metabolism, heart energetics, and outcome in a lethal model of rat's endotoxic shock.

INTERVENTIONS

We modulated the adrenergic pathway in skeletal muscle using microdialysis with ICI-118551, a selective beta(2)-blocker. Muscle lactate formation in endotoxic shock was further inhibited by intravenous infusion of ICI-118551 or dichloroacetate (DCA), an activator of pyruvate dehydrogenase (DCA) and their combination.

RESULTS

Muscle lactate formation was decreased by ICI-118551. During endotoxic shock both ICI-118151 and DCA decreased circulating and heart lactate concentrations in parallel with a decrease in tissue ATP content. The combination ICI-118551-DCA resulted in early cardiovascular collapse and death. The addition of molar lactate to ICI-1185111 plus DCA blunted the effects of ICI-118551+DCA on hemodynamics. Survival was markedly less with ICI-118551 than with endotoxin alone.

CONCLUSION

Systemic lactate deprivation is detrimental to myocardial energetics, cardiovascular performance, and outcome.

Neural regulation of innate immunity: a coordinated nonspecific host response to pathogens

The central nervous system (CNS) regulates innate immune responses through hormonal and neuronal routes. The neuroendocrine stress response and the sympathetic and parasympathetic nervous systems generally inhibit innate immune responses at systemic and regional levels, whereas the peripheral nervous system tends to amplify local innate immune responses. These systems work together to first activate and amplify local inflammatory responses that contain or eliminate invading pathogens, and subsequently to terminate inflammation and restore host homeostasis. Here, I review these regulatory mechanisms and discuss the evidence indicating that the CNS can be considered as integral to acute-phase inflammatory responses to pathogens as the innate immune system.

β2-Adrenoceptor blockade partially restores ex vivo TNF production following hemorrhagic shock

The aim of the study was to assess the mechanisms through which leukocyte deactivation occurs upon hemorrhagic shock. In particular, the influence of beta-adrenergic tone was evaluated. BALB/c mice were hemorrhaged and resuscitated 60 min after hemorrhage. Animals were sacrificed 60 min later by exsanguination. Blood from exsanguination was cultured ex vivo with lipopolysaccharide (LPS) and heat-killed Staphylococcus aureus Cowan I (SAC). Hemorrhage resulted in a major decrease of LPS-induced TNF production whereas IL-10 production was significantly enhanced. Selective beta(2)-adrenoceptor antagonists (ICI 118,551) attenuated the decrease in TNF production and further enhanced IL-10 production. Hemorrhage did not alter SAC-induced TNF production levels whereas IL-10 production was increased. ICI 118,551 further increased the production of both TNF and IL-10. These data suggest that leukocyte deactivation after LPS stimulation is not a generalized phenomenon since TNF production was maintained when another microbial activator was used. IL-10 production was enhanced after hemorrhagic shock, independently of the nature of the triggering agent. Finally, this study demonstrates that beta(2)-adrenoceptor ligands play an important role in blood leukocyte deactivation to LPS after hemorrhagic shock.

Dopamine affects cellular immune functions during polymicrobial sepsis

OBJECTIVE

To determine whether infusion of dopamine modulates cellular immune functions and survival during systemic inflammation.

DESIGN AND SETTING

Randomized animal study, university research laboratory, Level I trauma center.

SUBJECTS

Male NMRI mice.

INTERVENTIONS

Mice were subjected to laparotomy (sham intervention, LAP) or polymicrobial sepsis induced by cecal ligation and puncture (CLP). Mice in each of these conditions received either an intraperitoneal infusion of 0.9% saline (CLP/saline; LAP/saline) or an intraperitoneal infusion of dopamine (1.0 microg/kg/min i.p., CLP/DOP; LAP/DOP). Metabolic data and survival were monitored 24 h and 48 h after onset of sepsis, and animals were terminated 48 h after induction of sepsis to determine splenocyte apoptosis (Annexin V binding capacity), splenocyte proliferation (3H-Thymidine incorporation assay), splenocyte IL-2, IL-6 and IFN-gamma release (ELISA) and leukocyte distribution (WBC; CD3, CD4, CD8, B220, F4/80, NK1.1).

MEASUREMENTS AND RESULTS

Infusion of dopamine in septic mice increased splenocyte apoptosis and decreased splenocyte proliferation and IL-2 release of septic mice. Furthermore, an inhibitory effect of dopamine infusion on splenocyte proliferation and the release of the TH1-cytokines IL-2 and IFN-gamma was observed in sham operated control mice. These effects were paralleled by a decreased survival of dopamine-treated septic animals (47% vs. 67%). Treatment with DOP did not affect sepsis-induced changes of leukocyte distribution.

CONCLUSIONS

We conclude that dopamine is capable of modulating cellular immune functions in a murine model of sepsis.

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.