The beta-adrenoceptor antagonist propranolol counteracts anti-inflammatory effects of isoflurane in rat endotoxemia

Anaesthesia in Veterinary Oncology: The Effects of Surgery, Volatile and Intravenous Anaesthetics on the Immune System and Tumour Spread

Throughout the course of oncological disease, the majority of patients require surgical, anaesthetic and analgesic intervention. However, during the perioperative period, anaesthetic agents and techniques, surgical tissue trauma, adjuvant drugs for local pain and inflammation and other non-pharmacological factors, such as blood transfusions, hydration, temperature and nutrition, may influence the prognosis of the disease. These factors significantly impact the oncologic patient's immune response, which is the primary barrier to tumour progress, promoting a window of vulnerability for its dissemination and recurrence. More research is required to ascertain which anaesthetics and techniques have immunoprotective and anti-tumour effects, which will contribute to developing novel anaesthetic strategies in veterinary medicine.

Magnetic resonance imaging under isoflurane anesthesia alters cortical cyclooxygenase-2 expression and glial cell morphology during sepsis-associated neurological dysfunction in rats

Background

Magnetic resonance imaging (MRI) of rodents combined with histology allows to determine what mechanisms underlie functional and structural brain changes during sepsis-associated encephalopathy. However, the effects of MRI performed in isoflurane-anesthetized rodents on modifications of the blood-brain barrier and the production of vasoactive prostaglandins and glia cells, which have been proposed to mediate sepsis-associated brain dysfunction, are unknown.

Methods

This study addressed the effect of MRI under isoflurane anesthesia on blood-brain barrier integrity, cyclooxygenase-2 expression, and glial cell activation during cecal ligature and puncture-induced sepsis-associated brain dysfunction in rats.

Results

Cecal ligature and puncture reduced food intake and the righting reflex. MRI under isoflurane anesthesia reduced blood-brain barrier breakdown, decreased circularity of white matter astrocytes, and increased neuronal cyclooxygenase-2 immunoreactivity in the cortex 24 hours after laparotomy. In addition, it annihilated cecal ligature and puncture-induced increased circularity of white matter microglia. MRI under isoflurane anesthesia, however, did not alter sepsis-associated perivascular cyclooxygenase-2 induction.

Conclusion

These findings indicate that MRI under isoflurane anesthesia of rodents can modify neurovascular and glial responses and should, therefore, be interpreted with caution.

General Anesthetics on Immune System Cytokines: A Narrative Review Article

Context

According to the previous studies, general anesthesia influences the immune system. Evaluating such impacts on the immune system helps to improve the management of anesthesia.

Evidence Acquisition

The current review aimed to summarize the literature related to the effects of general anesthesia agents on the cytokines. Google Scholar, PubMed, and ISI/Web of Sciences databases were searched using the following keywords: cytokine, general anesthesia, immune response, intravenous anesthetics, volatile anesthetics, opioids, benzodiazepines, and controlled ventilation.

Results

Long-term administration of general anesthesia drugs, due to their effects on cytokines, can lead to disease progression in patients with immune deficiency. Due to the conflicting results of various studies and the increasing number of patients with immune deficiency, the choice of the appropriate general anesthesia agents facilitates achieving the more favorable function of the cytokines.

Conclusions

It seems that the effect of general anesthesia on the immune system in healthy patients and short-term surgeries is not considerable and changes in the immune system are related to surgical trauma, particularly in major surgery.

The splanchnic anti-inflammatory pathway: could it be the efferent arm of the inflammatory reflex?

What is the topic of this review? We review the current literature on the neural reflex termed the 'inflammatory reflex' that inhibits an excessive release of inflammatory mediators in response to an immune challenge. What advances does it highlight? The original model proposed that the inflammatory reflex is a vago-vagal reflex that controls immune function. We posit that, in the endotoxaemic animal model, the vagus nerves do not appear to play a role. The evidence suggests that the efferent motor pathway, termed here the 'splanchnic anti-inflammatory pathway', is purely sympathetic, travelling via the greater splanchnic nerves to regulate the ensuing inflammatory response to immune challenges. Exposure to immune challenges results in the development of inflammation. An insufficient inflammatory response can be life-threatening, whereas an exaggerated response is also detrimental because it causes tissue damage and, in extreme cases, septic shock that can lead to death. Hence, inflammation must be finely regulated. It is generally accepted that the brain inhibits inflammation induced by an immune challenge in two main ways: humorally, by activating the hypothalamic-pituitary-adrenal axis to release glucocorticoids; and neurally, via a mechanism that has been termed the 'inflammatory reflex'. The efferent arm of this reflex (the neural-to-immune link) was thought to be the 'cholinergic anti-inflammatory pathway'. Here, we discuss data that support the hypothesis that the vagus nerves play no role in the control of inflammation in the endotoxaemic animal model. We have shown and posit that it is the greater splanchnic nerves that are activated in response to the immune challenge and that, in turn, drive postganglionic sympathetic neurons to inhibit inflammation.

Desflurane preconditioning protects human umbilical vein endothelial cells against anoxia/reoxygenation by upregulating NLRP12 and inhibiting non-canonical nuclear factor-κB signaling

Volatile anesthetics modulate endothelial cell apoptosis and inhibit nuclear factor-κB (NF-κB) signaling. In this study, we aimed to assess whether desflurane preconditioning protects human umbilical vein endothelial cells (HUVECs) agaist anoxia/reoxygenation (A/R) injury. HUVECs were pre-conditioned with desflurane (1.0 MAC) for 30 min, followed by a 15-min washout, then exposed to 60 min anoxia and 60 min reoxygenation (A/R), and incubated with 10 ng/ml tumor necrosis factor (TNF)-α for 60 min. HUVEC viability and apoptosis were measured by MTT assay and annexin V staining, and immunoblot analysis was used to measure the levels of Smac and cellular inhibitor of apoptosis 1 (cIAP1). NF-κB activation was assessed using the NF-κB signaling pathway real‑time PCR array, and the levels of NF-κB inducing kinase (NIK), p52, IκB kinase (IKK)α, p100, RelB and NLR family, pyrin domain containing 12 (NLRP12) were assessed by immunoblot analysis. Desflurane preconditioning attenuated the effects of A/R and/or A/R plus TNF-α on cell viability, decreasing the levels of Smac and enhancing the levels of of cIAP1 (P<0.05). Preconditioning with desflurane also enhanced the mRNA levels of interleukin (IL)-10 and NLRP12 in the cells exposed to A/R by 2.40- and 2.16‑fold, respectively. The HUVECs exposed to A/R had greater levels of NIK and p100 and reduced levels of p52 and IKKα. Desflurance preconditioning further increased p100 levels, decreased the level of NIK, further decreased p52 levels and further reduced IKKα levels. A/R in combination with TNF-α increased the NIK, IKKα, p100 and RelB levels, and this increase was significantly attenuated by desflurance preconditioning (all P<0.05). Desflurane preconditioning enhanced HUVEC survival and protected the cells against A/R injury, and our results suggested that this process involved the upregulation of NLRP12 and the inhibition of non-canonical NF-κB signaling.

Clinical implication of perioperative inflammatory cytokine alteration

Cytokines are key modulators of inflammatory responses, and play an important role in the defense and repair mechanisms following trauma. After traumatic injury, an immuno-inflammatory response is initiated immediately, and cytokines rapidly appear and function as a regulator of immunity. In pathologic conditions, imbalanced cytokines may provide systemic inflammatory responses or immunosuppression. Expression of perioperative cytokines vary by different intensities of surgical trauma and types of anesthesia and anesthetic agents. Inflammatory cytokines play important roles in postoperative organ dysfunction including central nervous system, cardiovascular, lung, liver, and kidney injury. Inhibition of cytokines could protect against traumatic injury in some circumstances, therefore cytokine inhibitors or antagonists might have the potential for reducing postoperative tissue/organ dysfunction. Cytokines are also involved in wound healing and post-traumatic pain. Application of cytokines for the improvement of surgical wound healing has been reported. Anesthesia-related immune response adjustment might reduce perioperative morbidity because it reduces proinflammatory cytokine expression; however, the overall effects of anesthetics on postoperative immune-inflammatory responses needs to be further investigated.

Reflex control of inflammation by the splanchnic anti-inflammatory pathway is sustained and independent of anesthesia

Following an immune challenge, there is two-way communication between the nervous and immune systems. It is proposed that a neural reflex--the inflammatory reflex--regulates the plasma levels of the key proinflammatory cytokine TNF-α, and that its efferent pathway is in the splanchnic sympathetic nerves. The evidence for this reflex is based on experiments on anesthetized animals, but anesthesia itself suppresses inflammation, confounding interpretation. Here, we show that previous section of the splanchnic nerves strongly enhances the levels of plasma TNF-α in conscious rats 90 min after they received intravenous LPS (60 μg/kg). The same reflex mechanism, therefore, applies in conscious as in anesthetized animals. In anesthetized rats, we then determined the longer-term effects of splanchnic nerve section on responses to LPS (60 μg/kg iv). We confirmed that prior splanchnic nerve section enhanced the early (90 min) peak in plasma TNF-α and found that it reduced the 90-min peak of the anti-inflammatory cytokine IL-10; both subsequently fell to low levels in all animals. Splanchnic nerve section also enhanced the delayed rise in two key proinflammatory cytokines IL-6 and interferon γ. That enhancement was undiminished after 6 h, when other measured cytokines had subsided. Finally, LPS treatment caused hypotensive shock in rats with cut splanchnic nerves but not in sham-operated animals. These findings demonstrate that reflex activation of the splanchnic anti-inflammatory pathway has a powerful and sustained restraining influence on inflammatory processes.

Functional β-adrenoceptors are important for early muscle regeneration in mice through effects on myoblast proliferation and differentiation

Muscles can be injured in different ways and the trauma and subsequent loss of function and physical capacity can impact significantly on the lives of patients through physical impairments and compromised quality of life. The relative success of muscle repair after injury will largely determine the extent of functional recovery. Unfortunately, regenerative processes are often slow and incomplete, and so developing novel strategies to enhance muscle regeneration is important. While the capacity to enhance muscle repair by stimulating β₂-adrenoceptors (β-ARs) using β₂-AR agonists (β₂-agonists) has been demonstrated previously, the exact role β-ARs play in regulating the regenerative process remains unclear. To investigate β-AR-mediated signaling in muscle regeneration after myotoxic damage, we examined the regenerative capacity of tibialis anterior and extensor digitorum longus muscles from mice lacking either β₁-AR (β₁-KO) and/or β₂-ARs (β₂-KO), testing the hypothesis that muscles from mice lacking the β₂-AR would exhibit impaired functional regeneration after damage compared with muscles from β₁-KO or β₁/β₂-AR null (β₁/β₂-KO) KO mice. At 7 days post-injury, regenerating muscles from β₁/β₂-KO mice produced less force than those of controls but muscles from β₁-KO or β₂-KO mice did not exhibit any delay in functional restoration. Compared with controls, β₁/β₂-KO mice exhibited an enhanced inflammatory response to injury, which delayed early muscle regeneration, but an enhanced myoblast proliferation later during regeneration ensured a similar functional recovery (to controls) by 14 days post-injury. This apparent redundancy in the β-AR signaling pathway was unexpected and may have important implications for manipulating β-AR signaling to improve the rate, extent and efficacy of muscle regeneration to enhance functional recovery after injury.

Analgesic and anti-inflammatory effects of honey: the involvement of autonomic receptors

The use of honey for therapeutic purposes is on the increase and many studies have shown that honey has the ability to influence biological systems including pain transmission. Therefore, this study was designed to investigate the analgesic and anti-inflammatory effects of honey and the effects of concurrent administration of autonomic nervous system blocking drugs. Studies on analgesic activities was carried out using hotplate and formalin-induced paw licking models while the anti-inflammatory activity was by the carrageenan paw oedema method. Animals were distributed into six groups consisting of five animals each. They were administered saline, honey (600 mg/kg), indomethacin (5 mg/kg), autonomic blockers (3 μg/kg of tamsulosin, 20 mg/kg (intraperitoneally) of propranolol, 2 ml/kg of atropine or 10 mg/kg (intra muscularly) of hexamethonium) or honey (200 and 600 mg/kg) with one of the blockers. The results showed that honey reduced pain perception especially inflammatory pain and the administration of tamsulosin and propranolol spared the effect of honey. Hexamethonium also spared the effects of honey at the early and late phases of the test while atropine only inhibited the early phase of the test. However, atropine and hexamethonium spared the anti-inflammatory effects of honey but tamsulosin abolished the effects while propranolol only abolished the anti-inflammatory effects at the peak of the inflammation. The results suggest the involvement of autonomic receptors in the anti-nociceptive and anti-inflammatory effects of honey although the level of involvement depends on the different types of the receptors.

Adrenal hormone deprivation affects macrophage catecholamine metabolism and β2-adrenoceptor density, but not propranolol stimulation of tumour necrosis factor-α production

Catecholamines modulate the production of inflammatory mediators by macrophages in an autocrine/paracrine manner. They also tune β2-adrenoceptor expression. Glucocorticoids influence catecholamine metabolism and adrenoceptor expression in many cell types. We hypothesized that adrenal hormones affect the production of tumour necrosis factor-α (TNF-α) and NO by macrophages by altering the modulatory influence of catecholamines. To prove the hypothesis, peritoneal exudate macrophages from propranolol-treated non-operated and adrenalectomized rats and from corticosterone-supplemented adrenalectomized rats were examined for lipopolysaccharide-stimulated NO and TNF-α production in vitro and for expression of β2-adrenoceptors and major catecholamine-metabolizing enzymes. Glucocorticoid deprivation increased NO production by macrophages, whereas 4 days of propranolol treatment was ineffective in this respect. However, propranolol treatment, via β2-adrenoceptor blockade, increased production of TNF-α by macrophages in both non-operated and adrenalectomized rats (showing dramatically enhanced TNF-α production due to a lack of circulating glucocorticoids) for the same value. The expression of β2-adrenoceptor was increased in peritoneal macrophages that were freshly isolated from non-operated, propranolol-treated and adrenalectomized rats (due to adrenal catecholamine deficiency). Propranolol did not affect macrophage β2-adrenoceptor expression in adrenalectomized rats. Given that propranolol increased the density of macrophage tyrosine hydroxylase expression only in non-operated rats and affected the mRNA expression of monoamine oxidase-A in neither non-operated nor adrenalectomized animals, a significant influence of propranolol on peritoneal exudate cell noradrenaline content was found only in non-operated rats. A lack of circulating adrenal hormones also affected noradrenaline metabolism and content in peritoneal exudate cells including macrophages. Collectively, despite differences in the abundance of macrophage catecholamine-β2-adrenoceptor system components and in the TNF-α response to lipopolysaccharide between adrenalectomized and non-operated rats, propranolol increased TNF-α production by the same amount in macrophages from these two groups of animals.

Effects of electroacupuncture pretreatment on inflammatory response and acute kidney injury in endotoxaemic rats

This study investigated the effect of electroacupuncture pretreatment on the lipopolysaccharide (LPS)-induced inflammatory response and on acute kidney injury in adult male pathogen-free Wistar rats. Rats received electroacupuncture at the Zusanli (ST36) and Neiguan (PC6) acupoints, or electrical stimulation at sham points, for 30 min before stimulation with either 5 mg/kg LPS intravenously or normal saline. Plasma cytokines, plasma nitrite, renal inducible nitric oxide synthase (iNOS) and nuclear factor κB (NF-κB) activity were assessed 240 min after LPS or normal saline injection. Blood urea nitrogen (BUN), creatinine (Cr) and histopathological score for renal tubular damage were also measured. Electroacupuncture pretreatment significantly decreased LPS-induced plasma tumour necrosis factor-α and interleukin (IL)-1β, increased plasma IL-10, and decreased plasma nitrite, renal iNOS and NF-κB activity. It also significantly decreased LPS-induced BUN, Cr and the renal histopathological score. These findings suggest that electroacupuncture pretreatment at the ST36 and PC6 acupoints attenuated the LPS-induced inflammatory response and mitigated acute kidney injury.

Immunological modifications induced from products used during the perioperative period

Anesthetics and other products used during the perioperative period may influence immune function not only merely by reducing the HPA-axis stress response but also by directly modulating innate and adaptive immune responses. Most of the literature on the immune effects of anesthetics has been derived from in vitro or animal studies, due to the number of confounding variables in real life surgical settings. These immunosuppressive effects might not normally have clinical consequences for an immune-competent patient, but may act as important modifiers in postoperative morbidity and mortality. Furthermore, some inhibitory effects on neutrophil functions may provide a therapeutically beneficial effect under specific surgical clinical conditions, such as ischemia-reperfusion injury.

Contribution of α - and β -Adrenergic Mechanisms to the Development of Pulmonary Edema

Endogenous or exogenous catecholamines can induce pulmonary edema (PE). This may occur in human pathologic conditions such as in pheochromocytoma or in neurogenic pulmonary edema (NPE) but can also be provoked after experimental administration of adrenergic agonists. PE can result from stimulation with different types of adrenergic stimulation. With α-adrenergic treatment, it develops more rapidly, is more severe with abundant protein-rich fluid in the alveolar space, and is accompanied by strong generalized inflammation in the lung. Similar detrimental effects of α-adrenergic stimulation have repeatedly been described and are considered to play a pivotal role in NPE or in PE in patients with pheochromocytoma. Although β-adrenergic agonists have often been reported to prevent or attenuate PE by enhancing alveolar fluid clearance, PE may also be induced by β-adrenergic treatment as can be observed in tocolysis. In experimental models, infusion of β-adrenergic agonists induces less severe PE than α-adrenergic stimulation. The present paper addresses the current understanding of the possible contribution of α- and β-adrenergic pathways to the development of PE.

Comparing hemodynamics, blood gas analyses and proinflammatory cytokines in endotoxemic and severely septic rats

Lipopolysaccharide (LPS) is often used in short-term models of inflammation. Since endotoxemia and sepsis are different entities we have recently established a short-term sepsis model in rats induced by cecal ligation and incision (CLI). This retrospective study was conducted in order to identify similarities and differences between both experimental approaches. 32 anesthetized/ventilated male rats from the following four groups were analysed (each n=8): CTRL-group (0.9% NaCl i.v.); LPS-group (5mg/kg i.v.); SHAM-group (laparotomy); CLI-group (1.5 cm blade incision). Mean arterial blood pressure (MAP) and blood gas parameters (arterial base excess (BE) and pH) were continuously recorded. Total observation time was 300 min. Plasma samples were obtained afterwards. LPS and CLI induced significant arterial hypotension and metabolic acidosis compared to CTRL- or SHAM-group, respectively. Yet, between the LPS- and CLI-groups, there were no differences in MAP, BE and pH. LPS significantly induced IL-1β, IL-6 and TNF-α in the plasma. In contrast, CLI showed a clear tendency towards increased IL-1β and IL-6 plasma levels and did not affect TNF-α. Our results indicate that the CLI sepsis model is suitable for short-term investigations on hemodynamic alterations and blood gas analyses during sepsis. 300 min after the proinflammatory insult, plasma concentrations of IL-1β and IL-6 in the plasma remain considerably lower after CLI compared to endotoxemia. Low TNF-α concentrations 300 min after sepsis induction could be interpreted as considerable immunosuppression during CLI sepsis.

Levosimendan cardioprotection in acutely beta-1 adrenergic receptor blocked open chest pigs

BACKGROUND

Levosimendan and volatile anesthetics have myocardial pre-conditioning effects. beta-1 adrenergic receptor antagonists may inhibit the protective effect of volatile anesthetics. No information exists as to whether this also applies to the pre-conditioning effect of levosimendan. We therefore investigated whether levosimendan added to metoprolol would demonstrate a cardioprotective effect.

METHODS

Three groups of anesthetized open chest pigs underwent 30 min of myocardial ischemia and 90 min of reperfusion by temporary occlusion of the largest side branch from the circumflex artery or the left anterior descending artery. One group (CTRL) served as a control, in another group (BETA), a metoprolol-loading dose was intravenously injected 30 min before ischemia, and in a third group (BETA+L), a levosimendan infusion was added to metoprolol. Myocardial tissue concentrations of glucose, glycerol, and lactate/pyruvate ratio as the primary end-points were investigated with microdialysis in ischemic and non-ischemic tissues.

RESULTS

At the end of the ischemic period, statistically significant differences were only found between CTRL and BETA+L in the ischemic myocardium, with a lower lactate/pyruvate ratio, lower glycerol, and higher glucose concentrations in BETA+L as compared with CTRL. There were no differences in non-ischemic myocardium. From 10 to 90 min of reperfusion, no more differences were found between groups.

CONCLUSION

The cardioprotective effect of levosimendan on ischemic metabolism with a reduction in the myocardial lactate/pyruvate ratio, less glycerol accumulation, and better preserved glucose concentration does not seem to be prevented by beta-1 adrenergic receptor antagonism with metoprolol.

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.

Isoflurane attenuates pulmonary interleukin-1beta and systemic tumor necrosis factor-alpha following mechanical ventilation in healthy mice

BACKGROUND

Mechanical ventilation (MV) induces an inflammatory response in healthy lungs. The resulting pro-inflammatory state is a risk factor for ventilator-induced lung injury and peripheral organ dysfunction. Isoflurane is known to have protective immunological effects on different organ systems. We tested the hypothesis that the MV-induced inflammatory response in healthy lungs is reduced by isoflurane.

METHODS

Healthy C57BL6 mice (n=34) were mechanically ventilated (tidal volume, 8 ml/kg; positive end-expiratory pressure, 4 cmH(2)O; and fraction of inspired oxygen, 0.4) for 4 h under general anesthesia using a mix of ketamine, medetomidine and atropine (KMA). Animals were divided into four groups: (1) Unventilated control group; (2) MV group using KMA anesthesia; (3) MV group using KMA with 0.25 MAC isoflurane; (4) MV group using KMA with 0.75 MAC isoflurane. Cytokine levels were measured in lung homogenate and plasma. Leukocytes were counted in lung tissue.

RESULTS

Lung homogenates: MV increased pro-inflammatory cytokines. In mice receiving KMA+ isoflurane 0.75 MAC, no significant increase in interleukin (IL)-1beta was found compared with non-ventilated control mice. PLASMA: MV induced a systemic pro-inflammatory response. In mice anesthetized with KMA+ isoflurane (both 0.25 and 0.75 MAC), no significant increase in tumor necrosis factor (TNF)-alpha was found compared with non-ventilated control mice.

CONCLUSIONS

The present study is the first to show that isoflurane attenuates the pulmonary IL-1beta and systemic TNF-alpha response following MV in healthy mice.

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.

Chronic propranolol treatment affects expression of adrenoceptors on peritoneal macrophages and their ability to produce hydrogen peroxide and nitric oxide

Using both immunocytochemical and flow cytometric analyses of rat peritoneal exudate cells constitutive expression of tyrosine hydroxylase and both beta(2)- and alpha(1)- adrenoceptors on macrophages was revealed. Furthermore, according to the characteristic assemblage of tyrosine hydroxylase and adrenoceptor subtype expression different macrophage subsets were identified. In vitro treatment of macrophages with the non-selective alpha,beta-adrenoceptor agonist arterenol and/or the beta-adrenoceptor antagonist propranolol indicated that beta-adrenoceptors potentiated nitric oxide (NO) production and suggested alpha-adrenoceptor-mediated suppression of hydrogen peroxide (H(2)O(2)) production. An increase in H(2)O(2) production in the presence of the alpha(1)-adrenoceptor antagonist ebrantil provided support for this. Chronic propranolol treatment in vivo led to increased NO and H(2)O(2) production by peritoneal macrophages. Furthermore, this treatment resulted in opposing effects on the expression of beta(2)- and alpha(1)-adrenoceptors on peritoneal macrophages (a stimulatory effect on beta(2)-adrenoceptors and a suppressive effect on alpha(1)-adrenoceptors). In conclusion, a subset of resident peritoneal macrophages synthesizes catecholamines, which may exert differential effects on H(2)O(2) and NO production via distinct adrenoceptors. Finally, chronic propranolol treatment affected adrenoceptor expression on peritoneal macrophages and altered their capacity to generate NO and H(2)O(2).

Synergistic IL-10 induction by LPS and the ceramide-1-phosphate analog PCERA-1 is mediated by the cAMP and p38 MAP kinase pathways

Expression of the anti-inflammatory cytokine IL-10 can be induced either by TLR agonists such as lipopolysaccharide (LPS), or by various endogenous stimuli, in particular those acting via a cAMP-dependent signaling pathway. We have previously reported that the synthetic phospho-ceramide analogue-1 (PCERA-1) increases cAMP level and subsequently down-regulates production of TNFalpha and up-regulates production of IL-10 in LPS-stimulated macrophages. The objective of this study was to determine the mechanism of activity of PCERA-1 and the role of cAMP in LPS-induced IL-10 production. We show here that PCERA-1 induces IL-10 production in synergism with various TLR agonists in mouse RAW264.7 macrophages. Cooperativity is evident both at the mRNA and protein levels. IL-10 production by LPS and PCERA-1 is mediated by the cAMP pathway and by the p38 MAP kinase. Phosphorylation of p38 is cooperatively accomplished by LPS and PCERA-1 or other cAMP inducers. Furthermore, the activity of PCERA-1 can be partially mimicked by a cell-permeable analog of cAMP, and blocked by the protein kinase A (PKA) inhibitor H89. Finally, in the absence of PCERA-1, the residual IL-10 induction by LPS depends on the basal cAMP level as it can be largely elevated by the phosphodiesterase (PDE)-4 inhibitor rolipram. Our results thus indicate that IL-10 induction by LPS critically depends on basal cAMP level, and that a co-stimulus by a TLR agonist and a cAMP-elevating agent results in synergistic PKA-dependent and p38-dependent IL-10 production.

Anesthetics, immune cells, and immune responses

General anesthesia accompanied by surgical stress is considered to suppress immunity, presumably by directly affecting the immune system or activating the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system. Along with stress such as surgery, blood transfusion, hypothermia, hyperglycemia, and postoperative pain, anesthetics per se are associated with suppressed immunity during perioperative periods because every anesthetic has direct suppressive effects on cellular and neurohumoral immunity through influencing the functions of immunocompetent cells and inflammatory mediator gene expression and secretion. Particularly in cancer patients, immunosuppression attributable to anesthetics, such as the dysfunction of natural killer cells and lymphocytes, may accelerate the growth and metastases of residual malignant cells, thereby worsening prognoses. Alternatively, the anti-inflammatory effects of anesthetics may be beneficial in distinct situations involving ischemia and reperfusion injury or the systemic inflammatory response syndrome (SIRS). Clinical anesthesiologists should select anesthetics and choose anesthetic methods with careful consideration of the clinical situation and the immune status of critically ill patients, in regard to long-term mortality, morbidity, and the optimal prognosis.