Glucocorticoids reduce ischemia-reperfusion-induced myocardial apoptosis in immature hearts

A review of the interplay between Takotsubo cardiomyopathy and adrenal insufficiency: Catecholamine surge and glucocorticoid deficiency

BACKGROUND

Takotsubo Cardiomyopathy (TCM) is a transient heart condition often precipitated by stress and characterized by atypical ventricular ballooning. The interplay between TCM and Adrenal Insufficiency (AI), particularly the influence of catecholamine excess and glucocorticoid deficiency on TCM's pathogenesis in individuals with AI, warrants comprehensive exploration for a better understanding of TCM pathophysiology and establishment of potential therapeutic strategies.

METHODS

We conducted an extensive literature search via PubMed and Google Scholar, targeting reports on AI, heart failure, and cardiomyopathy, supplemented by forward and backward citation tracing. We analyzed 46 cases from 45 reports, assessing the clinical presentation and outcomes in the context of AI categorization.

RESULTS

In patients with AI, a glucocorticoid deficit appears to exacerbate the myocardial vulnerability to catecholamine toxicity, precipitating TCM. Most conditions were reversible; however, three pre-1990 cases resulted in irreversible outcomes.

CONCLUSIONS

The investigation into the AI and TCM intersection highlights the pathogenic significance of catecholamines in the absence of glucocorticoids. The data consolidates the hypothesis that glucocorticoid scarcity exacerbates the cardiac susceptibility to catecholaminergic toxicity, potentially triggering TCM. The study affirms glucocorticoids' cardioprotective roles and elucidates how catecholamine surges contribute to TCM pathogenesis, suggesting strategic clinical management adjustments for AI patients to reduce TCM incidence.

Cardiac Hypertrophy and Related Dysfunctions in Cushing Syndrome Patients-Literature Review

The survival rate of adrenal Cushing syndrome patients has been greatly increased because of the availability of appropriate surgical and pharmacological treatments. Nevertheless, increased possibility of a heart attack induced by a cardiovascular event remains a major risk factor for the survival of affected patients. In experimental studies, hypercortisolemia has been found to cause cardiomyocyte hypertrophy via glucocorticoid receptor activation, including the possibility of cross talk among several hypertrophy signals related to cardiomyocytes and tissue-dependent regulation of 11β-hydroxysteroid dehydrogenase type 1. However, the factors are more complex in clinical cases, as both geometric and functional impairments leading to heart failure have been revealed, and their associations with a wide range of factors such as hypertension are crucial. In addition, knowledge regarding such alterations in autonomous cortisol secretion, which has a high risk of leading to heart attack as well as overt Cushing syndrome, is quite limited. When considering the effects of treatment, partial improvement of structural alterations is expected, while functional disorders are controversial. Therefore, whether the normalization of excess cortisol attenuates the risk related to cardiac hypertrophy has yet to be fully elucidated.

Case report: Changes in the levels of stress hormones during Takotsubo syndrome

Background

Takotsubo syndrome is an acute cardiac condition usually involving abnormal regional left ventricular wall motion and impaired left ventricular contractility. It is due mainly to hyper-stimulation of the sympathetic nerve system, inducing an excess of catecholamines, usually triggered by intense psychological or physiological stress. The relationship between Takotsubo syndrome and the circulating stress hormones cortisol and copeptin (a surrogate marker of arginine vasopressin) has not been well documented.

Case summary

Here, we describe the dynamic changes in circulating cortisol and copeptin during an entire episode of Takotsubo syndrome in a post-partum woman after spontaneous vaginal delivery. The patient was diagnosed with inverted Takotsubo syndrome accompanied by HELLP syndrome. We found qualitative and quantitative changes in cortisol: a loss of circadian rhythm and a three-fold elevation in the plasma concentration of the hormone with a peak appearing several hours before circulating cardiac biomarkers began to rise. By contrast, levels of copeptin remained normal during the entire episode.

Discussion

Our findings indicate that the levels of cortisol change during Takotsubo syndrome whereas those of copeptin do not. This association between elevated cortisol and Takotsubo syndrome suggests that aberrant levels of this stress hormone may contribute to the observed cardiac pathology. We conclude that biochemical assays of circulating cortisol and cardiac biomarkers may be a useful complement to the diagnosis of Takotsubo syndrome by non-invasive cardiac imaging.

New insights into the roles of glucocorticoid signaling dysregulation in pathological cardiac hypertrophy

Pathological cardiac hypertrophy is a process of abnormal remodeling of the myocardium in response to stress overload or ischemia that results in myocardial injury, which is an independent risk factor for the increased morbidity and mortality of heart failure. Elevated circulating glucocorticoids (GCs) levels are associated with an increased risk of pathological cardiac hypertrophy, but the exact role remains unclear. In the heart, GCs exerts physiological and pharmacological effects by binding the glucocorticoid receptor (GR, NR3C1). However, under the state of tissue damage or oxidative stress, GCs can also bind the closely related mineralocorticoid receptor (MR, NR3C2) to exert a detrimental effect on cardiac function. In addition, the bioavailability of GCs at the cellular level is mainly regulated by tissue-specific metabolic enzymes 11β-hydroxysteroid dehydrogenases (11β-HSDs), including 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) and type 2 (11β-HSD2), which catalyze the interconversion of active GCs. In this paper, we provide an overview of GC signaling and its physiological roles in the heart and highlight the dynamic and diverse roles of GC signaling dysregulation, mediated by excessive ligand GCs levels, GR/MR deficiency or overexpression, and local GCs metabolic disorder by 11β-HSDs, in the pathology of cardiac hypertrophy. Our findings will provide new ideas and insights for the search for appropriate intervention targets for pathological cardiac hypertrophy.

Takotsubo Cardiomyopathy Secondary to Adrenal Insufficiency: A Case Report and Literature Review

We report a case of a middle-aged female who presented with altered mental status, hypotension, and hypoglycemia and was diagnosed with secondary adrenal insufficiency. She was also found to have elevated troponin I on initial evaluation with diffuse T wave inversions on electrocardiogram. Transthoracic echocardiogram revealed ejection fraction of 38% with apical akinesia. Subsequent left heart catheterization revealed clean coronary arteries. She was diagnosed with typical Takotsubo cardiomyopathy secondary to adrenal insufficiency. She was managed with IV hydrocortisone with resolution of symptoms. This article adds to the select few cases in the literature of the association of Takotsubo cardiomyopathy resulting from secondary adrenal insufficiency.

Acute reversible cardiomyopathy and heart failure in a child with acute adrenal crisis

Acute adrenal crisis is a life-threatening disorder. Cardiovascular complications of the condition are usually limited to hypovolaemic hypotension and shock. An acute reversible cardiomyopathy and heart failure in association with acute adrenal crisis is rarely reported, particularly in children. A 6-year-old girl with adrenal crisis which was complicated by acute reversible cardiomyopathy is reported. Inotropic and ventilatory support in addition to intravenous hydrocortisone and furosemide therapy were required to achieve cardiovascular stability. The cardiomyopathy resolved over 5 days and she was discharged with normal cardiac and intellectual functions. Cardiomyopathy should be considered in patients with acute adrenal crisis demonstrating any symptoms or signs of heart failure.

Glucocorticoid signaling in the heart: A cardiomyocyte perspective

Heart failure is one of the leading causes of death in the Western world. Glucocorticoids are primary stress hormones that regulate a vast array of biological processes, and synthetic derivatives of these steroids have been mainstays in the clinic for the last half century. Abnormal levels of glucocorticoids are known to negatively impact the cardiovascular system; however, surprisingly little is known about the direct role of glucocorticoid signaling in the heart. The actions of glucocorticoids are mediated classically by the glucocorticoid receptor (GR). In certain cells, such as cardiomyocytes, glucocorticoid occupancy and activation of the mineralocorticoid receptor (MR) may also contribute to the observed response. Recently, there has been a surge of reports investigating the in vivo function of glucocorticoid signaling in the heart using transgenic mice that specifically target GR or MR in cardiomyocytes. Results from these studies suggest that GR signaling in cardiomyocytes is critical for the normal development and function of the heart. In contrast, MR signaling in cardiomyocytes participates in the development and progression of cardiac disease. In the following review, we discuss these genetic mouse models and the new insights they are providing into the direct role cardiomyocyte glucocorticoid signaling plays in heart physiology and pathophysiology. This article is part of a Special Issue entitled 'Steroid Perspectives'.

Tissue-specific actions of glucocorticoids on apoptosis: a double-edged sword

First described for their metabolic and immunosuppressive effects, glucocorticoids are widely prescribed in clinical settings of inflammation. However, glucocorticoids are also potent inducers of apoptosis in many cell types and tissues. This review will focus on the established mechanisms of glucocorticoid-induced apoptosis and outline what is known about the apoptotic response in cells and tissues of the body after exposure to glucocorticoids. Glucocorticoid-induced apoptosis affects the skeletal system, muscular system, circulatory system, nervous system, endocrine system, reproductive system, and the immune system. Interestingly, several cell types have an anti-apoptotic response to glucocorticoids that is cytoprotective. Lastly, we will discuss the pro- and anti-apoptotic effects of glucocorticoids in cancers and their clinical implications.

Dual role for glucocorticoids in cardiomyocyte hypertrophy and apoptosis

Glucocorticoids and their synthetic derivatives are known to alter cardiac function in vivo; however, the nature of these effects and whether glucocorticoids act directly on cardiomyocytes are poorly understood. To explore the role of glucocorticoid signaling in the heart, we used rat embryonic H9C2 cardiomyocytes and primary cardiomyocytes as model systems. Dexamethasone (100 nm) treatment of cardiomyocytes caused a significant increase in cell size and up-regulated the expression of cardiac hypertrophic markers, including atrial natriuretic factor, β-myosin heavy chain, and skeletal muscle α-actin. In contrast, serum deprivation and TNFα exposure triggered cardiomyocyte apoptosis, and these apoptotic effects were inhibited by dexamethasone. Both the hypertrophic and anti-apoptotic actions of glucocorticoids were abolished by the glucocorticoid receptor (GR) antagonist RU486 and by short hairpin RNA-mediated GR depletion. Blocking the activity of the mineralocorticoid receptor had no effect on these glucocorticoid-dependent cardiomyocyte responses. Aldosterone (1 μm) activation of GR also promoted cardiomyocyte hypertrophy and cell survival. To elucidate the mechanism of the dual glucocorticoid actions, a genome-wide microarray was performed on H9C2 cardiomyocytes treated with vehicle or dexamethasone in the absence or presence of serum. Serum dramatically influenced the transcriptome regulated by GR, revealing potential glucocorticoid signaling mediators in both cardiomyocyte hypertrophy and apoptosis. These studies reveal a direct and dynamic role for glucocorticoids and GR signaling in the modulation of cardiomyocyte function.

Modulation of 11β-hydroxysteroid dehydrogenase 1 by β2-adrenoceptor in the ischaemia-reperfused rat kidney

BACKGROUND

11β-Hydroxysteroid dehydrogenase Type 1 (11βHSD-1) amplifies intracellular levels of active glucocorticoids which possess protective effects against organ ischaemia and reperfusion (I/R). However, the mechanisms by which 11βHSD-1 is modified after a renal I/R challenge remain unclear. This study investigated the effect of β(2)-adrenoceptor (β(2)-AR) activation and the subsequent signalling pathways on renal 11βHSD-1 gene expression following renal I/R.

METHODS

Renal I/R was induced using 25 min of bilateral renal artery occlusion in 4-week-old Wistar rats followed by an intraperitoneal injection of various doses of adeno-β(2)-AR gene. Following renal I/R, kidneys, plasma and urine were collected to assay 11βHSD messenger RNA (mRNA) levels, β(2)-AR signalling cascades and renal function.

RESULTS

On the second day after the renal I/R challenge, there was a reduction in renal 11βHSD-1 mRNA levels associated with a decrease in stimulatory G protein α (Gsα) and adenylate cyclase-1 (ACY-1) in the kidney. The addition of the adeno-β(2)-AR gene resulted in greater increases in 11βHSD-1 mRNA and β(2)-AR-Gsα-ACY-cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) activity in the kidney but had no effect on 11βHSD-2 mRNA or protein kinase C levels in the kidney.

CONCLUSIONS

Over-expression of β(2)-AR resulting from the gene delivery improved renal function and 11βHSD-1 production following renal I/R, which were actions exerted through the cAMP-PKA pathway. The stimulatory effect of functional β(2)-AR activation on renal 11βHSD-1 expression may offer a means of protection from renal I/R injury.

The neuroprotective effects of lidocaine and methylprednisolone in a rat model of retinal ischemia-reperfusion injury

Retinal ischemia is a common cause of visual impairment for humans and animals. The neuroprotective effects of lidocaine (LDC) and methylprednisolone (MP) upon retinal ischemic injury were investigated in a rat model. Sprague-Dawley rats were divided into 3 groups, the IR control, LDC and MP. A very high intraocular pressure (HIOP) and retinal ischemia were induced. In LDC group, LDC bolus (1.5 mg/kg) was i.v. injected 30 min before ischemia and then a constant rate infusion (CRI) with 2 mg/kg/hr was given until 60 min after reperfusion. In MP group, MP bolus (30 mg/kg) was i.v. administered twice at 2 min before and immediately after ischemia, respectively. The HIOP damage to retina was evaluated by electroretinogram (ERG) and morphometrical histology. The functional analysis of the retina by ERG revealed a 35.2% reduction of a-wave in the IR group, 49.7% reduction in the LDC group but no significant change in the MP group compared to normal controls. An 81.0% reduction of b-wave was observed in the IR group, 80.7% reduction in the LDC group and 17.6% reduction in the MP group. In the morphometrical histology, the retinal inner plexiform layer/outer nuclear layer (IPL/ONL) ratio was reduced to 48.8% in the IR group, 80.1% in the LDC group and 96.2% in MP group. In conclusion, the MP showed significantly good neuroprotective effects on retinal IR injury, and the LDC showed moderate neuroprotective effects demonstrated in retinal structure but not in retinal function.

Corticosteroid effects on ventilator-induced diaphragm dysfunction in anesthetized rats depend on the dose administered

BACKGROUND

High dose of corticosteroids has been previously shown to protect against controlled mechanical ventilation (CMV)-induced diaphragmatic dysfunction while inhibiting calpain activation. Because literature suggests that the calpain inhibiting effect of corticosteroid depends on the dose administered, we determined whether lower doses of corticosteroids would also provide protection of the diaphragm during CMV. This may be important for patients undergoing mechanical ventilation and receiving corticosteroids.

METHODS

Rats were assigned to controls or to 24 hours of CMV while being treated at the start of mechanical ventilation with a single intramuscular administration of either saline, or 5 mg/kg (low MP) or 30 mg/kg (high MP) of methylprednisolone.

RESULTS

Diaphragmatic force was decreased after CMV and this was exacerbated in the low MP group while high MP rescued this diaphragmatic dysfunction. Atrophy was more severe in the low MP group than after CMV while no atrophy was observed in the high MP group. A significant and similar increase in calpain activity was observed in both the low MP and CMV groups whereas the high dose prevented calpain activation. Expression of calpastatin, the endogenous inhibitor of calpain, was decreased in the CMV and low MP groups but its level was preserved to controls in the high MP group. Caspase-3 activity increased in all CMV groups but to a lesser extent in the low and high MP groups. The 20S proteasome activity was increased in CMV only.

CONCLUSIONS

Administration of 30 mg/kg methylprednisolone during CMV protected against CMV-induced diaphragm dysfunction while 5 mg/kg was more deleterious. The protective effect is due mainly to an inhibition of the calpain system through preservation of calpastatin levels and to a lesser extent to a caspase-3 inhibition.

Glucocorticoid signaling in cardiac disease

As major mediators of stress regulation, glucocorticoids have an essential role in maintaining cardiovascular homeostasis under both physiological and pathological conditions. The release of glucocorticoids into the peripheral circulation is adjusted by the hypothalamic-pituitary-adrenal axis in response to various pathological challenges such as sepsis, starvation, and psychological stress. Clinically, dysregulation of the glucocorticoid-mediated signaling as a result of either excess ligand or receptor hypersensitivity is connected with the progression of unfavorable cardiovascular events such as cardiac hypertrophy, atherosclerosis, and coronary artery disease. The direct effects of glucocorticoids on cardiac tissues are mediated by two steroid receptors, the glucocorticoid receptor and mineralocorticoid receptor, which are both expressed by cardiomyocytes. Although each receptor has some shared responses to glucocorticoids, each receptor also has unique effects on cardiac functions. Elucidating the selective actions of each receptor is critical for determining the proper pharmaceutical targets in cardiovascular diseases.

Glucocorticoids Activate Cardiac Mineralocorticoid Receptors During Experimental Myocardial Infarction

Myocardial ischemia-reperfusion leads to significant changes in redox state, decreased postischemic functional recovery, and cardiomyocyte apoptosis, with development and progression of heart failure. Ischemia-reperfusion in the isolated perfused rat heart has been used as a model of heart failure. Clinically, mineralocorticoid receptor blockade in heart failure decreases morbidity and mortality versus standard care alone. The effects of corticosteroids on infarct area and apoptosis were determined in rat hearts subjected to 30 minutes of ischemia and 2.5 hours of reperfusion. Both aldosterone and cortisol increased infarct area and apoptotic index, an effect half-maximal between 1 and 10 nM and reversed by spironolactone. Dexamethasone and mifepristone aggravated infarct area and apoptotic index, similarly reversed by spironolactone. Spironolactone alone reduced infarct area and apoptotic index below ischemia-reperfusion alone, in hearts from both intact and adrenalectomized rats. The present study shows that cardiac damage is aggravated by activation of mineralocorticoid receptors by aldosterone or cortisol or of glucocorticoid receptors by dexamethasone. Mifepristone unexpectedly acted as a glucocorticoid receptor agonist, for which there are several precedents. Spironolactone protected cardiomyocytes via inverse agonist activity at mineralocorticoid receptors, an effect near maximal at a relatively low dose (10 nM). Spironolactone acts not merely by excluding corticosteroids from mineralocorticoid receptors but as a protective inverse agonist at low concentration. Mineralocorticoid receptor antagonists may, thus, provide an additional therapeutic advantage in unstable angina and acute myocardial infarction.

Molecular Biology of Apoptosis in Ischemia and Reperfusion

This study reviews the current understanding of the mechanisms that mediate the complex processes involved in apoptosis secondary to ischemia and reperfusion (I/R) and is not intended as a complete literature review of apoptosis. Several biochemical reactions trigger a cascade of events, which activate caspases. These caspases exert their effect through downstream proteolysis until the final effector caspases mediate the nuclear features characteristic of apoptosis, DNA fragmentation and condensation. Within the context of ischemia, the hypoxic environment initiates the expression of several genes involved in inflammation, the immune response, and apoptosis. Many of these same genes are activated during reperfusion injury in response to radical oxygen species generation. It is plausible that inhibition of specific apoptotic pathways via inactivation or downregulation of those genes responsible for the initiation of inflammation, immune response, and apoptosis may provide promising molecular targets for ameliorating reperfusion injury in I/R-related processes. Such inhibitory mechanisms are discussed in this review. Important targets in I/R-related pathologies include the brain during stroke, the heart during myocardial infarction, and the organs during harvesting and/or storage for transplantation. In addition, we present data from our ongoing research of specific signal transduction-related elements and their role in ischemia/reperfusion injury. These data address the potential therapeutic application of anti-inflammatory and anti-ischemic compounds in the prevention of I/R damage.

Glucocorticoids improve calcium cycling in cardiac myocytes after cardiopulmonary bypass

BACKGROUND

Glucocorticoids can reduce myocardial dysfunction associated with ischemia and reperfusion injury following cardiopulmonary bypass (CPB) and circulatory arrest. The hypothesis was that maintenance of cardiac function after CPB with methylprednisolone therapy results, in part, from preservation of myocyte calcium cycling.

METHODS

Piglets (5-7 kg) underwent CPB and 120 min of hypothermic circulatory arrest with (CPB-GC) or without (CPB) methylprednisolone (30 mgkg(-1)) administered 6h before and at CPB. Controls (No-CPB) did not undergo CPB or receive glucocorticoids (n=6 per treatment). Myocardial function was monitored in vivo for 120 min after CPB. Calcium cycling was analyzed using rapid line-scan confocal microscopy in isolated, fluo-3-AM-loaded cardiac myocytes. Phospholamban phosphorylation and sarco(endo)plasmic reticulum calcium-ATPase (SERCA2a) protein levels were determined by immunoblotting of myocardium collected 120 min after CPB. Calpain activation in myocardium was measured by fluorometric assay.

RESULTS

Preload recruitable stroke work in vivo 120 min after reperfusion decreased from baseline in CPB (47.4±12 versus 26.4±8.3 slope of the regression line, P<0.05), but was not different in CPB-GC (41±8.1 versus 37.6±2.2, P=0.7). In myocytes isolated from piglets, total calcium transient time remained unaltered in CPB-GC (368±52.5 ms) compared with controls (434.5±35.3 ms; P=0.07), but was prolonged in CPB myocytes (632±83.4 ms; P<0.01). Calcium transient amplitude was blunted in myocytes from CPB (757±168 nM) compared with controls (1127±126 nM, P<0.05) but was maintained in CPB-GC (1021±155 nM, P>0.05). Activation of calpain after CPB was reduced with glucocorticoids. Phospholamban phosphorylation and SERCA2a protein levels in myocardium were decreased in CPB compared with No-CPB and CPB-GC (P<0.05).

CONCLUSIONS

The glucocorticoid-mediated improvement in myocardial function after CPB might be due, in part, to prevention of calpain activation and maintenance of cardiac myocyte calcium cycling.

Modulation of nuclear factor-kappaB improves cardiac dysfunction associated with cardiopulmonary bypass and deep hypothermic circulatory arrest

OBJECTIVE

The hypothesis is that partial nuclear factor-kappaB (NF-kappaB) inhibition can alleviate cardiopulmonary dysfunction associated with ischemia and reperfusion injury following cardiopulmonary bypass and deep hypothermic circulatory arrest (CPB/DHCA) in a pediatric model.

DESIGN

Animal case study.

SUBJECTS

Two-week-old piglets (5-7 kg).

INTERVENTIONS

Piglets received 100 microg/kg of SN50, a peptide inhibitor of NF-kappaB translocation and activation, 1 hour before CPB. The control group received saline. Animals were cooled to 18 degrees C with CPB, the piglets were in DHCA for 120 minutes, and the piglets were then rewarmed on CPB to 38 degrees C and maintained for 120 minutes after CPB/DHCA.

MEASUREMENTS

Sonomicrometry and pressure catheters collected hemodynamic data. Transmural left and right ventricular tissues were obtained at the terminal time point for determination of NF-kappaB activity by enzyme-linked immunosorbent assay. Data are expressed as mean +/- sd.

MAIN POINTS

Oxygen delivery was maintained at 76 +/- 13 mL/min at baseline and 75 +/- 5 mL/min at 120 minutes after CPB/DHCA (p = 0.75) in SN50-treated animals vs. 99 +/- 26 mL/min at baseline and 63 +/- 20 mL/min at 120 minutes in the untreated group (p = 0.0001). Pulmonary vascular resistance (dynes.sec.cm) increased from 124 +/- 59 at baseline to 369 +/- 104 at 120 minutes in the untreated piglets (p = 0.001) compared with SN50-treated animals (100 +/- 24 at baseline and 169 +/- 88 at 120 minutes, p = 0.1). NF-kappaB activity was reduced by 74% in left ventricles of SN50-treated compared with SN50-untreated animals (p < 0.001). Plasma endothelin-1 (pg/mL), an important vasoconstrictor regulated by NF-kappaB, increased from 2.1 +/- 0.4 to 14.2 +/- 5.7 in untreated animals (p = 0.004) but was elevated to only 4.5 +/- 2 with SN50 treatment (p = 0.005).

CONCLUSIONS

Improvement of cardiopulmonary function after ischemia/reperfusion was associated with the reduction of NF-kappaB activity in piglet hearts. Maintenance of systemic oxygen delivery and alleviation of pulmonary hypertension after CPB/DHCA in piglets administered SN50, possibly through a reduction of circulating endothelin-1, suggest that selective inhibition of NF-kappaB activity may reduce ischemia and reperfusion injury after pediatric cardiac surgery.

Apoptosis in cardiac myocytes during the early stage after severe burn

BACKGROUND

Cardiac dysfunction after severe burn is associated with postburn myocardial injury. We hypothesize that myocyte apoptosis is triggered and presented as the pathologic basis of postburn myocardial injury during the early stage after severe burn, and that apoptosis may be related to inflammatory responses in the postburn myocardium.

METHODS

Rats with 40% total body surface area full-thickness burn were used. The following functions were measured at several time points after the burn injury: myocyte apoptosis (TUNEL staining, DNA ladder, and caspase-3 activity assay); mRNA levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (reverse transcriptase-polymerase chain reaction [RT-PCR]); activities of myeloperoxidase and p38 mitogen activated protein (MAP) kinase (Western blots); and left cardiac function.

RESULTS

TUNEL positive myocytes appeared as early as 6-hour and their numbers showed further increases at 12-hour and 24-hour postburn; DNA fragmentation was clearly observed, and caspase-3 activity was significantly increased in the myocardium after burn. Infiltration of neutrophils, evidenced by the levels of myeloperoxidase activity, expression of TNF-alpha, and p38 MAP kinase activity in the heart, were all significantly increased within 24-hour after burn. Cardiac function was decreased after burn, which approximately paralleled the increased amount of cardiac apoptosis.

CONCLUSION

These results demonstrate that cardiomyocyte apoptosis progressively develops during the early stage after severe burn, which may in part contribute to burn-induced cardiac dysfunction. Myocardial inflammatory responses, evidenced by the increased infiltration of neutrophils, as well as production of TNF-alpha probably because of the activation of p38 MAP kinase, may be involved in burn-induced cardiomyocyte apoptosis.

Ampulla (Takotsubo) cardiomyopathy caused by secondary adrenal insufficiency in ACTH isolated deficiency

We describe here a case of reversible ampulla (takotsubo) cardiomyopathy caused by secondary adrenal insufficiency in ACTH isolated deficiency. A 53-year-old woman was referred to our department for evaluation and treatment of unconsciousness. On admission, her plasma glucose level was 34 mg/dL, suggesting loss of consciousness due to hypoglycemia. Basal levels of ACTH, cortisol, and dehydroepiandrosterone sulfate in blood, and urinary free cortisol levels were all decreased. ACTH and cortisol levels were not adequately increased in response to CRH administration and the insulin tolerance test. Electrocardiography showed ST segment elevation and T wave inversion in leads V 1-6. The coronary arteries were free of organic stenosis, and a left ventriculogram revealed severe hypokinesis, particularly in the anterior and posterior walls. Based on a diagnosis of adrenocortical insufficiency caused by ACTH isolated deficiency, hydrocortisone was administered. Two weeks after treatment, ultrasound studies of the heart showed recovery of left ventricular wall motion. Activation of the sympathetic nervous system, adrenocortical failure, and hypoglycemic attack were considered to be triggering factors for the takotsubo cardiomyopathy. Careful monitoring of cardiac function and appropriate treatments for both cardiomyopathy and adrenocortical failure are required to recover cardiac dysfunction.

Regulation of differential pro- and anti-apoptotic signaling by glucocorticoids

More than a quarter of a century ago, the phenomenon of glucocorticoid-induced apoptosis in the majority of hematological cells was first recognized. More recently, glucocorticoid-induced antiapoptotic signaling associated with apoptosis resistance has been identified in cells of epithelial origin, most of malignant solid tumors and some other tissues. Despite these huge amount of data demonstrating differential pro- and anti-apoptotic effects of glucocorticoids, the underlying mechanisms of cell type specific glucocorticoid signaling are just beginning to be described. This review summarizes our present understanding of cell type-specific pro- and anti-apoptotic signaling induced by glucocorticoids. In the first section we give a summary and update of known glucocorticoid-induced pathways mediating apoptosis in hematological cells. We shortly introduce mechanisms of glucocorticoid resistance of hematological cells. We highlight and discuss the emerging molecular evidence of a general induction of survival signaling in epithelial cells and carcinoma cells by glucocorticoids. We provide a model for glucocorticoid-induced resistance in cells growing in a tissue formation. Thus, attachment to the extracellular matrix and cell-cell contacts typical for e.g. epithelial and tumor cells may be crucially involved in switching the balance of several interacting pathways to survival upon treatment with glucocorticoids.

Glucocorticoids Alter the Balance Between Pro- and Anti-inflammatory Mediators in the Myocardium in a Porcine Model of Brain Death

BACKGROUND

Cardiac dysfunction after brain death (BD) limits donors for cardiac transplantation. Glucocorticoids ameliorate brain death-induced donor heart dysfunction. We hypothesized that glucocorticoid therapy alleviates myocardial depression through altering the balance between pro- and anti-inflammatory mediators via the nuclear factor-kappaB (NF-kappaB)/inhibitor of kappaB-alpha (IkappaBalpha) pathway and/or by preserving beta-adrenergic receptor (betaAR) signaling in the heart.

METHODS

Crossbred pigs (25 to 35 kg) were randomly assigned to the following groups (n = 5/treatment): sham (Group 1); BD (Group 2); and BD with glucocorticoids (30 mg/kg methylprednisolone), either 2 hours before (Group 3) or 1 hour after BD (Group 4). Tumor necrosis factor-alpha (TNF-alpha) levels were measured in plasma at baseline and 1 hour and 6 hours after BD. Protein levels were measured in left ventricular homogenates procured 6 hours after BD.

RESULTS

Pro-inflammatory proteins (TNF-alpha) and interleukin-6 were lower in Group 3 and Group 4 compared with Group 2 at 6 hours after BD (p < 0.01). Intracellular adhesion molecule-1 was also lower in Group 4 compared with Group 2 (p = 0.001). Interleukin-10, an anti-inflammatory mediator, was lower in Group 4 than in Group 2 (p < 0.001), but not different between Groups 2 and 3. At 6 hours after BD, neither NF-kappaB activity nor basal adenylate cyclase activity differed between Groups 3 and 4 compared with Group 2.

CONCLUSIONS

Glucocorticoids maintained myocardial function and shifted the balance of pro- and anti-inflammatory mediators after BD. The mechanisms by which glucocorticoids preserve myocardial function, however, do not appear to involve the NF-kappaB pathway or betaAR signaling.

Cobalt Chloride Pretreatment Attenuates Myocardial Apoptosis After Hypothermic Circulatory Arrest

BACKGROUND

Deep hypothermic circulatory arrest (DHCA) causes myocyte injury as a consequence of ischemia and reperfusion. Previous studies have shown that hypoxia or hypoxia-mimetic agents (cobalt chloride [CoCl2] or deferoxamine [DFX]) limit myocyte necrosis by upregulating the transcription factor hypoxia-inducible factor. However, it remains unknown whether these agents attenuate myocardial apoptosis after DHCA. This study tested the hypotheses (1) that hypoxia, DFX, or CoCl2 preconditioning attenuates myocardial apoptosis during DHCA; and (2) that the protective mechanism involves the altered expression of apoptosis regulatory proteins pAkt (antiapoptotic), Bcl-2 (antiapoptotic), and Bax (proapoptotic).

METHODS

Anesthetized neonatal piglets were randomly assigned to four groups (n = 6 in a group): control (NaCl injection); hypoxia (pO2 of 30 to 40 mm Hg for 3 hours); DFX injection; or CoCl2 injection. Twenty-four hours later, the animals underwent cardiopulmonary bypass (CPB) and 110 minutes of DHCA. One week after CPB, percentage of apoptotic myocytes (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling [TUNEL] assay) and expression of the pAKT, Bcl-2, and Bax were assessed by Western blot.

RESULTS

Although preconditioning with hypoxia and DFX failed to show a protective benefit, CoCl2 pretreatment significantly attenuated myocardial apoptosis (9.3% +/- 4.1%) versus controls (33.8% +/- 9.7%, p = 0.042). That was associated with increased myocardial pAkt expression (0.19 +/- 0.006 in CoCl2 versus 0.12 +/- 0.008 in control, p < 0.001). The expression of Bcl-2 was also significantly higher in the CoCl2 group (0.15 +/- 0.02) versus control (0.11 +/- 0.01, p = 0.007), whereas Bax expression was lower (0.34 +/- 0.04 versus 0.54 +/- 0.03 for control, p < 0.001).

CONCLUSIONS

Preconditioning with CoCl2 before prolonged DHCA in neonatal piglets attenuates myocardial apoptosis by mechanisms involving phosphorylation of Akt, upregulation of the antiapoptotic protein Bcl-2, and decreased expression of the proapoptotic protein Bax.

The acute cardioprotective effect of glucocorticoid in myocardial ischemia–reperfusion injury occurring during cardiopulmonary bypass

The purpose of this study was to evaluate the acute cardioprotective effect of high-dose methylprednisolone (25 mg/kg) in the controlled in vivo model of myocardial ischemia-reperfusion injury occurring during cardiopulmonary bypass. Forty nondiabetic male patients with three-vessel disease undergoing first-time bypass surgery were enrolled for this double-blind prospective study. Patients were randomized to be given 25 mg/kg methylprednisolone (Group I) and saline (Group II) 1 h before cardiopulmonary bypass. The levels of cardiac troponin-I (cTnI) were used as a marker of myocardial tissue damage in myocardial ischemia-reperfusion injury. The cTnI levels were measured before surgery, at the second hour after cardiopulmonary bypass, at the 6th and 24th hours, and 5th day postoperatively. There was no significant difference between the two groups in respect to the duration of ischemia and reperfusion. The preoperative cTnI levels were 0.22+/-0.29 ng/ml in Group I and 0.23+/-0.28 ng/ml in Group II. cTnI levels increased to 2.40+/-1.0 ng/ml in Group I and 3.19+/-0.88 ng/ml in Group II at the 2nd hour after cardiopulmonary bypass. When the differences between T1 and T0 level that showed the amount of troponin release occurring due to ischemia-repefusion injury was calculated and then compared, there was a significant difference between Groups I and II (P=0.024). The cTnI levels measured at 6 h after CPB were 1.98+/-0.63 ng/ml in Group I and 2.75+/-1.15 ng/ml in Group II (P=0.049). cTnI levels decreased to 0.22+/-0.10 ng/ml in Group I and 0.49+/-0.25 ng/ml in Group II on the postoperative day 5 (P=0.0001). Univalent regression analysis showed that preoperative high-dose corticosteroid usage decreased the troponin release in about 12% and this effect was statistically significant (R2=0.12, P<0.05). A single dose of intravenous methylpredisolone (25 mg/kg) given 1 h before ischemia reduced myocardial ischemia-reperfusion injury. These results demonstrated that the acute cardioprotective effect of corticosteroids has much potential in the future for reducing ischemia-reperfusion injury occurring during cardiopulmonary bypass when it is inevitable.

Glucocorticoid use in prostate cancer and other solid tumours: implications for effectiveness of cytotoxic treatment and metastases

Glucocorticoids have been used widely in conjunction with other treatment for patients with cancer because they have potent proapoptotic properties in lymphoid cells, can reduce nausea, and alleviate acute toxic effects in healthy tissue. However, glucocorticoids are used in a supportive-care role, even though to our knowledge no prospective clinical studies have assessed the effect of these steroids on the growth of solid tumours. Data from preclinical and, to some extent, clinical studies, suggest that glucocorticoids induce treatment resistance in solid tumours, including prostate cancer. Research has focussed on disseminated cells that have been shed by the tumour: the potential of glucocorticoids to render these cells resistant to apoptosis--and to downregulate the immune response--might contribute to tumour metastasis. Here, we review the benefits of glucocorticoids and their negative effects, such as induction of resistance in tumour cells and concomitant induction of apoptosis in immune cells, with particular emphasis on prostate cancer.

Reactive oxygen species as mediators of cardiac injury and protection: the relevance to anesthesia practice

Reactive oxygen species (ROS) are central to cardiac ischemic and reperfusion injury. They contribute to myocardial stunning, infarction and apoptosis, and possibly to the genesis of arrhythmias. Multiple laboratory studies and clinical trials have evaluated the use of scavengers of ROS to protect the heart from the effects of ischemia and reperfusion. Generally, studies in animal models have shown such effects. Clinical trials have also shown protective effects of scavengers, but whether this protection confers meaningful clinical benefits is uncertain. Several IV anesthetic drugs act as ROS scavengers. In contrast, volatile anesthetics have recently been demonstrated to generate ROS in the heart, most likely because of inhibitory effects on cardiac mitochondria. ROS are involved in the signaling cascade for cardioprotection induced by brief exposure to a volatile anesthetic (termed "anesthetic preconditioning"). ROS, therefore, although injurious in large quantities, can have a paradoxical protective effect within the heart. In this review we provide background information on ROS formation and elimination relevant to anesthetic and adjuvant drugs with particular reference to the heart. The sources of ROS, the means by which they induce cardiac injury or activate protective signaling pathways, the results of clinical studies evaluating ROS scavengers, and the effects of anesthetic drugs on ROS are each discussed.

Glucocorticoid administration reduces cardiac dysfunction after brain death in pigs

BACKGROUND

Traumatic brain injury and subsequent brain death (BD) account for nearly half of all organ donors, yet only 33% of available hearts are transplanted. Alterations in multiple physiologic pathways after BD can lead to cardiac dysfunction and exclusion from transplantation. Triple hormone resuscitation with methylprednisolone, thyroid hormone and vasopressin has had inconsistent results in the effort to reduce cardiac dysfunction associated with BD, but individual analysis of these agents is limited. The hypothesis was that glucocorticoid administration alone could reduce BD-associated cardiac dysfunction.

METHODS

Crossbred pigs (25 to 35 kg) had BD induced by sub-dural balloon inflation. Hemodynamics were measured for 360 minutes after BD. Negative cerebral perfusion pressures and decreased laser Doppler cerebral blood flow confirmed BD. Animals (n = 5/treatment group) received: saline (Group 1); 30 mg/kg methylprednisolone 2 hours before BD (Group 2); or 30 mg/kg methylprednisolone 1 hour after BD (Group 3). Repeated measures analysis of variance and unpaired t-tests were used for appropriate comparisons.

RESULTS

Left ventricular (LV) pre-load recruitable stroke work (PRSW) decreased in untreated Group 1 over time (p < 0.001), whereas PRSW in animals treated with glucocorticoids, Groups 2 and 3, was not different from baseline at 360 minutes after BD. Diastolic function measured as LV -dP/dt (minimum derivative of the change in pressure over time) and tau (time constant of isovolumic relaxation) was also preserved 360 minutes after brain death by glucocorticoids in Groups 2 and 3 (p > 0.05). Oxygen delivery 360 minutes after BD was higher in Group 2 compared with Group 1 (p = 0.02) and Group 3 (p = 0.006).

CONCLUSIONS

Glucocorticoid therapy before or after BD preserved LV systolic and diastolic function. Glucocorticoids administered after brain death might increase the number of hearts available for transplant by reducing brain death-associated cardiac dysfunction.

Toxic epidermal necrolysis: current evidence, practical management and future directions

Toxic epidermal necrolysis (TEN) is a rare disorder characterized by extensive epidermal death. Almost all cases appear to be caused by an idiosyncratic drug reaction. Proposed pathogenic mechanisms are conflicting, and the evidence for the benefits of individual treatments is inadequate, and in some cases contradictory. The mortality rate remains high. We review the literature pertaining to the pathogenesis of TEN and drug reactions in general. The rationale for therapeutic interventions, together with reported evidence of efficacy, are considered. We present a composite model of TEN, based on previous work and suggested pathogeneses of TEN, mechanisms of drug reactions and reported cytotoxic lymphocyte (CTL) cytolytic pathways. In this system, TEN, like some other cutaneous drug eruptions, is an HLA class I-restricted, specific drug sensitivity, resulting in clonal expansion of CD8+ CTLs. Cytotoxicity is mediated by CTL granzyme and possibly death receptor (DR) ligand (DR-L), probably Fas ligand (FasL). Particular to TEN, there is then an amplification sequence involving further DR-L expression. FasL is likely to be particularly important but tumour necrosis factor (TNF) may well contribute, via the TNF receptor 1 (TNF-R1) death pathway. Alternatively, we suggest the possibility of upregulation of an antiapoptotic TNF-R1-nuclear factor kappaB pathway, which would proscribe treatments which downregulate this pathway. None of the published data on individual treatment efficacies is sufficiently strong to suggest a definitive single treatment. Currently a multifaceted regimen appears indicated, targeting various likely intermediary mechanisms, including elimination of residual drug, immunosuppression, inhibition of DR pathways, general antiapoptotic strategies, and aggressive supportive care. Particular attention has been directed at avoiding potential conflicts between different treatments and avoiding agents that theoretically might have a net proapoptotic rather than antiapoptotic effect. Nursing on a specialized unit is of paramount importance.

Calpain inhibition decreases endothelin-1 levels and pulmonary hypertension after cardiopulmonary bypass with deep hypothermic circulatory arrest*

OBJECTIVE

Cardiopulmonary bypass in infants and children can result in cardiopulmonary dysfunction through ischemia and reperfusion injury. Pulmonary hypertension and injury are particularly common and morbid complications of neonatal cardiac surgery. Inhibition of calpain, a cysteine protease, has been shown to inhibit reperfusion injury in adult organ systems. The hypothesis is that calpain inhibition can alleviate the cardiopulmonary dysfunction seen in immature animals following ischemia and reperfusion with cardiopulmonary bypass.

DESIGN

Animal case study.

SETTING

Medical laboratory.

SUBJECTS

Crossbred piglets (5-7 kg).

INTERVENTIONS

Piglets were cooled with cardiopulmonary bypass to 18 degrees C followed by deep hypothermic circulatory arrest for 120 mins. Animals were rewarmed to 38 degrees C on cardiopulmonary bypass and maintained for 120 mins. Six animals were administered calpain inhibitor (Z-Leu-Leu-Tyr-fluoromethyl ketone; 1 mg/kg, intravenously) 60 mins before cardiopulmonary bypass. Nine animals were administered saline as a control. Plasma endothelin-1, pulmonary and hemodynamic function, and markers of leukocyte activity and injury were measured.

MEASUREMENTS AND MAIN RESULTS

Calpain inhibition prevented the increased pulmonary vascular resistance seen in control animals (95.7 +/- 39.4 vs. 325.3 +/- 83.6 dyne.sec/cm, respectively, 120 mins after cardiopulmonary bypass and deep hypothermic circulatory arrest, p = .05). The attenuation in pulmonary vascular resistance was associated with a blunted plasma endothelin-1 response (4.91 +/- 1.72 pg/mL with calpain inhibition vs. 10.66 +/- 6.21 pg/mL in controls, p < .05). Pulmonary function after cardiopulmonary bypass was better maintained after calpain inhibition compared with controls: Po2/Fio2 ratio (507.2 +/- 46.5 vs. 344.7 +/- 140.5, respectively, p < .05) and alveolar-arterial gradient (40.0 +/- 17.2 vs. 128.1 +/- 85.2 mm Hg, respectively, p < .05). Systemic oxygen delivery was higher after calpain inhibition compared with controls (759 +/- 171 vs. 277 +/- 46 mL/min, respectively, p < .001). In addition, endothelial nitric oxide synthase activity in lung tissue was maintained with calpain inhibition.

CONCLUSIONS

The reduction in plasma endothelin-1 and maintenance of lung endothelial nitric oxide levels after cardiopulmonary bypass and deep hypothermic circulatory arrest with calpain inhibition were associated with reduced pulmonary vascular resistance. Improved gas exchange and higher systemic oxygen delivery suggest that calpain inhibition may be advantageous for reducing postoperative cardiopulmonary dysfunction commonly associated with pediatric heart surgery and cardiopulmonary bypass.

Inhibition of ischemia/reperfusion-induced damage by dexamethasone in isolated working rat hearts: the role of cytochrome c release

We investigated the contribution of dexamethasone treatment on the recovery of postischemic cardiac function and the development of reperfusion-induced arrhythmias in ischemic/reperfused isolated rat hearts. Rats were treated with 2 mg/kg of intraperitoneal injection of dexamethasone, and 24 hours later, hearts were isolated according to the 'working' mode, perfused, and subjected to 30 min global ischemia followed by 120 min reperfusion. Cardiac function including heart rate, coronary flow, aortic flow, and left ventricular developed pressure were recorded. After 60 min and 120 min reperfusion, 2 mg/kg of dexamethasone significantly improved the postischemic recovery of aortic flow and left ventricular developed pressure from their control values of 10.7 +/- 0.3 ml/min and 10.5 +/- 0.3 kPa to 22.2 +/- 0.3 ml/min (p < 0.05) and 14.3 +/- 0.5 kPa (p < 0.05), 19.3 +/- 0.3 ml/min (p < 0.05) and 12.3 +/- 0.5 kPa (p < 0.05), respectively. Heart rate and coronary flow did not show a significant change in postischemic recovery after 60 or 120 min reperfusion. In rats treated with 0.5 mg/kg of actinomycin D injected i.v., one hour before the dexamethasone injection, suppressed the dexamethasone-induced cardiac protection. Electrocardiograms were monitored to determine the incidence of reperfusion-induced ventricular fibrillation. Dexamethasone pretreatment significantly reduces the occurrence of ventricular fibrillation. Cytochrome c release was also observed in the cytoplasm. The results suggest that the inhibition of cytochrome c release is involved in the dexamethasone-induced cardiac protection.

Apoptosis-related mitochondrial dysfunction in the early postoperative neonatal lamb heart

BACKGROUND

In the early postoperative period, the neonatal myocardium undergoes sparse apoptotic cell loss ( approximately 1% of myocytes). Because apoptosis is preceded by events associated with mitochondrial dysfunction, the fraction of myocytes with preapoptotic mitochondrial changes has important clinical implications (eg, postoperative myocardial dysfunction). My colleagues and I therefore hypothesized that postoperative apoptotic myocytes represent a tip of the iceberg, with more myocytes upstream with apoptosis-related mitochondrial dysfunction (ARMD).

METHODS

Neonatal lambs underwent cardiopulmonary bypass, 60 minutes of cardioplegic arrest, and 6 hours of recovery (cardiopulmonary bypass with cardioplegic arrest [CPB+CP]; n = 5) and were compared with nonbypass controls (non-CPB; n = 5). Myocardium (left ventricle [LV] and right ventricle [RV]) was examined by using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) staining, electron microscopy, immunohistochemistry, Western blot, and isolated mitochondrial oxygen consumption measurement.

RESULTS

TUNEL-positive nuclei and electron microscopy-confirmed mitochondrial structural changes were more common in CPB+CP than non-CPB myocardium and were more common in the LV than RV (p = 0.0016). Bax (a proapoptotic mediator) translocated from the cytosol to the mitochondria (LV > RV; p < 0.05). Immunohistochemistry demonstrated diffuse mitochondrial loss of cytochrome c that was consistent with outer mitochondrial membrane permeabilization (LV > RV > non-CPB). Permeabilization was further demonstrated by augmentation of oxygen consumption in isolated mitochondria after administration of exogenous cytochrome c. The mitochondrial oxygen consumption boost was 57% for CPB+CP:LV; 23% for CPB+CP:RV; and 18% and 17% for non-CPB:LV and non-CPB:RV, respectively (p < 0.01, CPB+CP:LV vs other groups).

CONCLUSIONS

ARMD is much greater than the prevalence of TUNEL-positive myocytes in postoperative neonatal myocardium. Greater LV vulnerability may represent a relationship between increased afterload and ARMD. These changes are consistent with the early postoperative myocardial dysfunction commonly reported after neonatal cardiac operations.

Preoperative glucocorticoids decrease pulmonary hypertension in piglets after cardiopulmonary bypass and circulatory arrest

BACKGROUND

Glucocorticoids during cardiopulmonary bypass benefit pediatric patients undergoing repair of congenital heart defects and are routine therapy, but underlying mechanisms have not been fully examined. The hypothesis was that glucocorticoids could improve cardiopulmonary recovery after cardiopulmonary bypass and deep hypothermic circulatory arrest.

METHODS

Crossbred piglets (5 to 7 kg) were cooled with cardiopulmonary bypass, followed by 120-min deep hypothermic circulatory arrest. Animals were then warmed to 38 degrees C, removed from bypass, and maintained for 120 min. Methylprednisolone (60 mg/kg) was administered in the cardiopulmonary bypass pump prime (intraoperative glucocorticoids) or 6 hours before bypass (30 mg/kg) in addition to the intraoperative dose (30 mg/kg; preoperative and intraoperative glucocorticoids). Controls (no glucocorticoids) received saline.

RESULTS

Pulmonary vascular resistance in controls increased from a baseline of 152 +/- 40 to 364 +/- 29 dynes. s/cm(5) at 2 hours of recovery (p < 0.001). Intraoperative glucocorticoids did not alleviate the increase in pulmonary vascular resistance (301 +/- 55 dynes. s/cm(5) at 2 hours of recovery, p < 0.001). However, animals receiving pre and intraoperative glucocorticoids had no increase in pulmonary vascular resistance (155 +/- 54 dynes. s/cm(5)). Plasma endothelin-1 in controls increased from 1.3 +/- 0.2 at baseline to 9.9 +/- 2.0 pg/mL at 2 hours recovery (p < 0.01), whereas glucocorticoid-treated animals had lower endothelin-1 levels (4.5 +/- 2.1 pg/ml, preoperative and intraoperative glucocorticoids; 4.9 +/- 1.7 pg/mL, intraoperative glucocorticoids) at the end of recovery (p < 0.05). Intracellular adhesion molecule-1 in lung tissue was lower in animals receiving pre and intraoperative glucocorticoids (p < 0.05). Myeloperoxidase activity was elevated in control lungs at 2 hours of recovery compared with glucocorticoid-treated groups (p < 0.05). Inhibitor kappaBalpha, the inhibitor of nuclear factor-kappaB, was higher in lungs of animals receiving glucocorticoids compared with controls (p < 0.05).

CONCLUSIONS

Glucocorticoids prevented pulmonary hypertension after cardiopulmonary bypass and deep hypothermic circulatory arrest, which was associated with reduced plasma endothelin-1. Glucocorticoids also reduced pulmonary intercellular adhesion molecule-1 and myeloperoxidase activity. Inhibition of nuclear factor-kappaB, along with reduced neutrophil activation, contributed to glucocorticoid alleviation of pulmonary hypertension after cardiopulmonary bypass and deep hypothermic circulatory arrest.

Glucocorticoids reduce cardiac dysfunction after cardiopulmonary bypass and circulatory arrest in neonatal piglets

OBJECTIVE

The hypotheses were that glucocorticoid administration could improve ventricular recovery by reducing cardiopulmonary bypass (CPB)-induced inflammatory response and that presurgical administration might be more effective than intraoperative dosing.

DESIGN

Animal case study.

SUBJECTS

Crossbred piglets (5-7 kg).

INTERVENTIONS

Piglets were cooled with CPB, followed by 120 mins of deep hypothermic circulatory arrest (DHCA). Animals were rewarmed to 38 degrees C, removed from CPB, and maintained for 120 mins. Methylprednisolone (60 mg/kg) was administered in the CPB pump prime (intraoperative glucocorticoid [intraop GC]) or 6 hrs before CPB (30 mg/kg) in addition to the intraoperative dose (30 mg/kg; pre- and intraop GC). Controls (no GC) received saline.

MEASUREMENTS AND MAIN RESULTS

In no GC, left ventricle (LV) positive change in pressure in time (+dP/dt) (mm Hg/sec) had a mean +/- SD of 1555 +/- 194 at baseline vs. 958 +/- 463 at 120 mins after CPB, p=.01). LV +dP/dt was maintained in glucocorticoid-treated animals (1262 +/- 229 at baseline vs. 1212 +/- 386 in intraop GC and 1471 +/- 118 vs. 1393 +/- 374 in pre-intraop GC). Glucocorticoids reduced myocardial interleukin-6 messenger RNA expression, measured by ribonuclease protection assay, at 120 mins after CPB compared with animals receiving saline (p<.05), although interleukin-6 plasma and LV protein concentrations were not affected. Interleukin-10 myocardial protein concentrations were elevated after CPB-DHCA with higher concentrations in glucocorticoid-treated animals (p<.05). Glucocorticoid treatment maintained myocardial concentrations of the inhibitor of nuclear factor-kappaB in the cytosol and decreased nuclear factor-kappaB concentrations detected in the nucleus in a DNA/protein interaction array.

CONCLUSIONS

Glucocorticoids improved recovery of LV systolic function in neonatal animals undergoing CPB-DHCA. Animals receiving glucocorticoids before CPB had better postoperative oxygen delivery than those receiving only intraoperative treatment. Maintenance of cardiac function after glucocorticoids might be due, in part, to alterations in the balance of pro- and anti-inflammatory proteins, possibly through nuclear factor-kappaB-dependent pathways.

Combined steroid treatment for congenital heart surgery improves oxygen delivery and reduces postbypass inflammatory mediator expression

BACKGROUND

Steroid administration during cardiopulmonary bypass is thought to improve cardiopulmonary function by modulating bypass-related inflammation. This study was designed to compare preoperative and intraoperative methylprednisolone (MP) to intraoperative MP alone with respect to postbypass inflammation and clinical outcome.

METHODS AND RESULTS

Twenty-nine pediatric patients undergoing bypass procedures were randomly assigned to receive preoperative and intraoperative MP (30 mg/kg 4 hours before bypass and in bypass prime, n=14) or intraoperative MP only (30 mg/kg, n=15). Myocardial inflammatory mediator mRNA expression was determined in paired atrial biopsies (before and after bypass) by ribonuclease protection. Before and after bypass, serum IL-6 and IL-10 were measured by ELISA. Postoperative outcome was assessed by intubation time, CICU length of stay, fluid balance, arterio-venous O2 difference (DeltaA-VO2), and inotrope requirements. Compared with intraoperative MP alone, combined preoperative and intraoperative MP was associated with reduced myocardial mRNA expression for IL-6, MCP-1, and ICAM-1 both before and after bypass (P<0.05). Patients who received combined steroids had lower serum IL-6 and increased IL-10 at end-bypass (P<0.05), although differences were negligible by 24 hours. Combined MP treatment was associated with reduced fluid requirements, lower body temperature, and lower DeltaA-VO2 for the first 24 hours after surgery (P<0.05), along with trends toward improvement in other clinical outcomes.

CONCLUSIONS

Compared with intraoperative steroid treatment, combined preoperative and intraoperative steroid administration attenuates inflammatory mediator expression more effectively and is associated with improved indexes of O2 delivery in the first 24 hours after congenital heart surgery. These findings need to be confirmed in a larger multicenter trial.

The administration of alpha-melanocyte-stimulating hormone protects the ischemic/reperfused myocardium

The contribution of alpha-melanocyte-stimulating hormone (alpha-MSH) treatment, an active fragment of adrenocorticotropic hormone (ACTH), to the recovery of postischemic cardiac function, infarct size, the incidence of reperfusion-induced ventricular fibrillation and apoptotic cell death was studied in ischemic/reperfused isolated rat hearts. Rats were subcutaneously injected with 40, 200 and 400 microg/kg of alpha-MSH, and 12 h later, hearts were isolated, perfused and subjected to 30 min of ischemia followed by 120 min of reperfusion. Thus, after 120 min of reperfusion, with the concentration of 200 microg/kg alpha-MSH, coronary flow, aortic flow and left ventricular developed pressure were significantly improved from their control values of 14.6+/-0.6 ml/min, 7.5+/-0.5 ml/min and 9.1+/-0.4 kPa to 20.2+/-0.4 ml/min (p<0.05), 31.5+/-0.9 ml/min (p<0.05) and 15.9+/-0.6 (p<0.05) kPa, respectively. With the doses of 40, 200 and 400 microg/kg of alpha-MSH, infarct size was reduced from its control value of 38+/-5% to 33+/-6% (NS), 17+/-3% (p<0.05) and 19+/-4% (p<0.05), respectively. The reduction in the incidence of reperfusion-induced ventricular fibrillation followed the same pattern. It is reasonable to assume that a reduction in infarct size, in the alpha-MSH-treated myocardium, resulted in a reduction as well in apoptotic cell death. Although we did not specifically study the exact mechanism(s) of alpha-MSH-afforded postischemic protection, we assume that this protection may be related to alpha-MSH-induced corticosterone release and corticosterone-induced de novo protein synthesis, which reflected in the recovery of postischemic cardiac function in isolated hearts. Thus, interventions that are able to increase plasma corticosterone or glucocorticoid release may prevent the development of ischemia/reperfusion-induced damage.