Regulation of ACTH-induced steroidogenesis in human fetal adrenals by rTNF-alpha

Critical Illness-Related Corticosteroid Insufficiency (CIRCI): A Narrative Review from a Multispecialty Task Force of the Society of Critical Care Medicine (SCCM) and the European Society of Intensive Care Medicine (ESICM)

OBJECTIVE

To provide a narrative review of the latest concepts and understanding of the pathophysiology of critical illness-related corticosteroid insufficiency (CIRCI).

PARTICIPANTS

A multi-specialty task force of international experts in critical care medicine and endocrinology and members of the Society of Critical Care Medicine and the European Society of Intensive Care Medicine.

DATA SOURCES

Medline, Database of Abstracts of Reviews of Effects (DARE), Cochrane Central Register of Controlled Trials (CENTRAL) and the Cochrane Database of Systematic Reviews.

RESULTS

Three major pathophysiologic events were considered to constitute CIRCI: dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, altered cortisol metabolism, and tissue resistance to glucocorticoids. The dysregulation of the HPA axis is complex, involving multidirectional crosstalk between the CRH/ACTH pathways, autonomic nervous system, vasopressinergic system, and immune system. Recent studies have demonstrated that plasma clearance of cortisol is markedly reduced during critical illness, explained by suppressed expression and activity of the primary cortisol-metabolizing enzymes in the liver and kidney. Despite the elevated cortisol levels during critical illness, tissue resistance to glucocorticoids is believed to occur due to insufficient glucocorticoid alpha-mediated anti-inflammatory activity.

CONCLUSIONS

Novel insights into the pathophysiology of CIRCI add to the limitations of the current diagnostic tools to identify at-risk patients and may also impact how corticosteroids are used in patients with CIRCI.

Hypothalamic-Pituitary-Adrenal Hypofunction in Myalgic Encephalomyelitis (ME)/Chronic Fatigue Syndrome (CFS) as a Consequence of Activated Immune-Inflammatory and Oxidative and Nitrosative Pathways

There is evidence that immune-inflammatory and oxidative and nitrosative stress (O&NS) pathways play a role in the pathophysiology of myalgic encephalomyelitis (ME)/chronic fatigue syndrome (CFS). There is also evidence that these neuroimmune diseases are accompanied by hypothalamic-pituitary-adrenal (HPA) axis hypoactivity as indicated by lowered baseline glucocorticoid levels. This paper aims to review the bidirectional communications between immune-inflammatory and O&NS pathways and HPA axis hypoactivity in ME/CFS, considering two possibilities: (a) Activation of immune-inflammatory pathways is secondary to HPA axis hypofunction via attenuated negative feedback mechanisms, or (b) chronic activated immune-inflammatory and O&NS pathways play a causative role in HPA axis hypoactivity. Electronic databases, i.e., PUBMED, Scopus, and Google Scholar, were used as sources for this narrative review by using keywords CFS, ME, cortisol, ACTH, CRH, HPA axis, glucocorticoid receptor, cytokines, immune, immunity, inflammation, and O&NS. Findings show that activation of immune-inflammatory and O&NS pathways in ME/CFS are probably not secondary to HPA axis hypoactivity and that activation of these pathways may underpin HPA axis hypofunction in ME/CFS. Mechanistic explanations comprise increased levels of tumor necrosis factor-α, T regulatory responses with elevated levels of interleukin-10 and transforming growth factor-β, elevated levels of nitric oxide, and viral/bacterial-mediated mechanisms. HPA axis hypoactivity in ME/CFS is most likely a consequence and not a cause of a wide variety of activated immune-inflammatory and O&NS pathways in that illness.

Review: Endotoxin and the hypothalamo-pituitary-adrenal (HPA) axis

Endotoxin is considered to be a systemic (immunological) stressor eliciting a prolonged activation of the hypothalamo-pituitary-adrenal (HPA) axis. The HPA-axis response after an endotoxin challenge is mainly due to released cytokines (IL-1, IL-6 and TNF-α) from stimulated peripheral immune cells, which in turn stimulate different levels of the HPA axis. Controversy exists regarding the main locus of action of endotoxin on glucocorticoid secretion, since the effect of endotoxin on this neuro-endocrine axis has been observed in intact animals and after ablation of the hypothalamus; however, a lack of LPS effect has been described at both pituitary and adrenocortical levels. The resulting increase in adrenal glucocorticoids has well-documented inhibitory effects on the inflammatory process and on inflammatory cytokine release. Therefore, immune activation of the adrenal gland by endotoxin is thought to occur by cytokine stimulation of corticosteroid-releasing hormone (CRH) production in the median eminence of the hypothalamus, which, in turn stimulates the secretion of ACTH from the pituitary. Acute administration of endotoxin stimulates ACTH and cortisol secretion and the release of CRH and vasopressin (AVP) in the hypophysial portal blood. During repeated endotoxemia, tolerance of both immune and HPA function develops, with a crucial role for glucocorticoids in the modulation of the HPA axis. A single exposure to a high dose of LPS can induce a long-lasting state of tolerance to a second exposure of LPS, affecting the response of plasma TNF-α and HPA hormones. Although there are gender differences in the HPA response to endotoxin and IL-1, these responses are enhanced by castration and attenuated by androgen and estrogen replacement. Estrogens attenuate the endotoxin-induced stimulation of IL-6, TNF-α and IL-1ra release and subsequent activation in postmenopausal women. There appears to be a temporal and functional relation between the HPA-axis response to endotoxin and nitric oxide formation in the neuro-endocrine hypothalamus, suggesting a stimulatory role for nitric oxide in modulating the HPA response to immune challenges.

The Role of ACTH and Corticosteroids for Sepsis and Septic Shock: An Update

Sepsis is a common disorder associated with high morbidity and mortality. It is now defined as an abnormal host response to infection, resulting in life-threatening dysfunction of organs. There is evidence from in vitro and in vivo experiments in various animal models and in patients that endotoxin or sepsis may directly and indirectly alter the hypothalamic-pituitary-adrenal response to severe infection. These alterations may include necrosis or hemorrhage or inflammatory mediator-mediated decreased ACTH synthesis, steroidogenesis, cortisol delivery to tissues, clearance from plasma, and decreased sensitivity of tissues to cortisol. Disruption of the hypothalamic-pituitary-adrenal axis may translate in patients with sepsis into cardiovascular and other organ dysfunction, and eventually an increase in the risk of death. Exogenous administration of corticosteroids at moderate dose, i.e., <400 mg of hydrocortisone or equivalent for >96 h, may help reversing sepsis-associated shock and organ dysfunction. Corticosteroids may also shorten the duration of stay in the ICU. Except for increased blood glucose and sodium levels, treatment with corticosteroids was rather well tolerated in the context of clinical trials. The benefit of treatment on survival remains controversial. Based on available randomized controlled trials, the likelihood of survival benefit is greater in septic shock versus sepsis patients, in sepsis with acute respiratory distress syndrome or with community-acquired pneumonia versus patients without these conditions, and in patients with a blunted cortisol response to 250 μg of ACTH test versus those with normal response.

A single nucleotide polymorphism in the corticotropin receptor gene is associated with a blunted cortisol response during pediatric critical illness

OBJECTIVES

The cortisol response during critical illness varies widely among patients. Our objective was to examine single nucleotide polymorphisms in candidate genes regulating cortisol synthesis, metabolism, and activity to determine if genetic differences were associated with variability in the cortisol response among critically ill children.

DESIGN

This was a prospective observational study employing tag single nucleotide polymorphism methodology to examine genetic contributions to the variability of the cortisol response in critical illness. Thirty-one candidate genes and 31 ancestry markers were examined.

SETTING

Patients were enrolled from seven pediatric critical care units that constitute the Eunice Kennedy Shriver Collaborative Pediatric Critical Care Research Network.

SUBJECTS

Critically ill children (n = 92), age 40 weeks gestation to 18 years old, were enrolled.

INTERVENTIONS

Blood samples were obtained from all patients for serum cortisol measurements and DNA isolation. Demographic and illness severity data were collected.

MEASUREMENTS AND MAIN RESULTS

Single nucleotide polymorphisms were tested for association with serum free cortisol concentrations in context of higher illness severity as quantified by Pediatric Risk of Mortality III score greater than 7. A single nucleotide polymorphism (rs1941088) in the MC2R gene was strongly associated (p = 0.0005) with a low free cortisol response to critical illness. Patients with the AA genotype were over seven times more likely to have a low free cortisol response to critical illness than those with a GG genotype. Patients with the GA genotype exhibited an intermediate free cortisol response to critical illness.

CONCLUSIONS

The A allele at rs1941088 in the MC2R gene, which encodes the adrenocorticotropic hormone (corticotropin, ACTH) receptor, is associated with a low cortisol response in critically ill children. These data provide evidence for a genetic basis for a portion of the variability in cortisol production during critical illness. Independent replication of these findings will be important and could facilitate development of personalized treatment for patients with a low cortisol response to severe illness.

[Interaction between hypnotic agents and the hypothalamic-pituitary-adrenocorticotropic axis during surgery]

During stress, the relationship between the central nervous system and the immune system is essential to maintain homeostasis. The main neuroendocrine system involved in this interaction is the hypothalamic-pituitary-adrenal axis (HPA), which via the synthesis of glucocorticoids will modulate the intensity of the inflammatory response. Anaesthetic agents could be interacting with the HPA axis during surgery. Although etomidate currently remains in the center of the discussions, it seems, at least experimentally, that most hypnotics have the capacity to modulate the synthesis of adrenal steroids. Nevertheless, with the large literature on this subject, etomidate seems to be the most deleterious hypnotic agent on the HPA axis function. Its use should be limited when HPA axis is already altered.

Cytokine interactions with adrenal medullary chromaffin cells

It is generally accepted that a bi-directional or reciprocal interaction occurs between the immune and neuroendocrine systems, and that this relationship is important for the appropriate physiological functioning of both systems. Similarly, an imbalance in this relationship may contribute to a number of pathologies, most notably those relating to stress. The aim of this article is to consider the interaction of cytokines with the adrenal medulla, a potentially important player in this relationship. The chromaffin cells of the adrenal medulla release catecholamines and a range of biologically active peptides in response to a wide variety of stress-related signals. A growing body of evidence indicates that this stress response is influenced by, and in turn has influence upon, immune signalling. This brief review will focus primarily on the best-described adrenal medullary active cytokines, namely interferon-α, interleukin-6, interleukin-1α/β and tumour necrosis factor-α. In each case, three key issues will be addressed: the physiologically relevant source of the cytokine; the intracellular signalling events arising from activation of its receptor and finally the cellular consequences of such activation in terms of modulation of gene expression and the secretory output of the chromaffin cells.

Decreased cytosolic glucocorticoid receptor levels in critically ill patients

The immune system and the hypothalamic-pituitary-adrenal axis are linked by several mechanisms. Intracellular glucocorticoid receptors represent one important connection. The aim of this study was to examine the coherence between the number of glucocorticoid receptors, activation of the hypothalamic-pituitary-adrenal axis, inflammatory cytokine levels and the severity of illness in critically ill patients. In a prospective study, blood was collected from 20 healthy members of the hospital staff (control group) and 50 ventilated patients (sample group) within the first 24 hours after intubation and within three days of extubation. 3H-dexamethasone-binding assay was used to assess cytoplasmatic free glucocorticoid receptors levels. ACTH, cortisol, IL-6 and TNFa levels were measured by ELISA. In the sample group, specific binding of 3H-dexamethasone was significantly decreased compared to the control group. Glucocorticoid receptor levels tended to be lower in more severely ill patients. Plasma cortisol and ACTH levels were significantly different from the control group after extubation but not at intubation. Severe illness is associated with rapid down-regulation of 3H-dexamethasone binding. This decrease occurs before elevation of plasma cortisol. Therefore, down-regulation of cortisol binding may be directly associated with the stress response and not due to feedback regulation following increase in plasma cortisol levels.

Impaired hypothalamo-pituitary-adrenal axis in patients with ankylosing spondylitis

BACKGROUND

To investigate the hypothalamic-pituitary- adrenal (HPA) axis in patients with ankylosing spondylitis (AS) and healthy controls.

METHODS

Forty-nine AS patients and 20 healthy controls were included. Lowdose ACTH test (LDST) was used to assess the HPA axis. Basal cortisol, stimulated peak cortisol levels, and acutephase reactants [C-reactive protein (CRP), erythrocyte sedimentation rate, and fibrinogen] were studied. Bath Ankylosing Spondylitis Functional Index, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), and Bath Ankylosing Spondylitis Metrology Index were also evaluated.

RESULTS

Patient and control groups were not different regarding age, sex, body mass index and waist circumference (WC). Basal cortisol levels did not show a significant difference between groups. However, cortisol increment after low-dose ACTH was significantly impaired in AS subjects with respect to controls (20.0+/-4.4 vs 24+/-2.2 microg/dl, p<0.001). Eleven AS patients had impaired cortisol peak after LDST when a cortisol cut-off is accepted as 500 nmol/l (18 microg/dl) and none of the controls exhibited a peak cortisol responses to LDST<500 nmol/l. Comparison of AS subjects who were receiving anti-tumor necrosis factor (TNF) (no.=23), and conventional therapy (no.=26) yielded similar basal and peak cortisol concentrations. Peak cortisol concentrations were associated with basal cortisol, impaired cortisol response, CRP, and fibrinogen. Impaired cortisol response (subjects with peak cortisol levels <18 microg/dl) was significantly correlated with basal and peak cortisol concentrations and BASDAI.

CONCLUSION

Our results indicate an increased prevalence of subclinical glucocorticoid deficiency in AS patients. Anti-TNF treatment seems not to have effect on HPA axis.

The relation of adiponectin and tumor necrosis factor alpha levels between endothelial nitric oxide synthase, angiotensin-converting enzyme, transforming growth factor beta, and tumor necrosis factor alpha gene polymorphism in adrenal incidentalomas

OBJECTIVE

The aim of our study was to demonstrate demographic characteristics, presence of inflammatory markers, distribution of angiotensin-converting enzyme (ACE), tumor necrosis factor (TNF), endothelial nitric oxide synthase (eNOS) genotypes and relations among these parameters in these patients and control subjects.

RESEARCH DESIGN AND METHODS

Study samples were collected from 50 patients with adrenal mass and 30 control groups. The eNOS, ACE, TNF-alpha, transforming growth factor (TGF)-beta genes polymorphisms, TNF-alpha, adiponectin levels were analysed in 50 unrelated Turkish patients with a diagnosis of adrenal incidentaloma (AI).

RESULTS

There was statistically significant difference between TNF-alpha levels of patient and controls (p=0.048). We have not detected the connection between TGF-beta, TNF-alpha, ACE, eNOS gene polymorphism with serum TNF-alpha and adiponectin levels. In this study, we demonstrated that there were significant differences for ACE genotypes in the patients when compared to the controls (p<0.05). The percentages of the ID, DD, II genotypes for ACE gene polymorphism in the patients group were 30.0, 13.0, 7.0%, respectively.

CONCLUSIONS

According to different cases of eNOS, TGF-beta, ACE, and TNF-alpha gene genotypes; no statistical significant difference was found between basal cortisol, ACTH, DHEAS, metanephrine, renin, aldosterone, normetanephrine, 17-hydroxyprogesterone, 1 mg low-dose dexamethasone suppression test-cortisol response and AI size. In this study, I/D genotype was determined to be statistically higher in ACE gene in patients with AI (p=0.014).

Experimental therapeutic strategies for severe sepsis: mediators and mechanisms

Severe sepsis is the leading cause of mortality in intensive care units. The limited ability of current therapies to reduce sepsis mortality rates has fueled research efforts for the development of novel treatment strategies. Through the close collaboration between clinicians and scientists, progress can be seen in the struggle to develop effective therapeutic approaches for the treatment of sepsis and other immune and inflammatory disorders. Indeed, significant advances in intensive care, such as lung protective mechanical ventilation, improved antibiotics, and superior monitoring of systemic perfusion, are improving patient survival. Nonetheless, specific strategies that target the pathophysiological disorders in sepsis patients are essential to further improve clinical outcomes. This article reviews current clinical management approaches and experimental interventions that target pleiotropic or late-acting inflammatory mediators like caspases, C5a, MIF, and HMGB1, or the body's endogenous inflammatory control mechanisms such as the cholinergic anti-inflammatory pathway. These inflammatory mediators and anti-inflammatory mechanisms, respectively, show significant potential for the development of new experimental therapies for the treatment of severe sepsis and other infectious and inflammatory disorders.

Critical illness-related corticosteroid insufficiency

The diagnosis of adrenal failure and the indications for corticosteroid therapy in critically ill patients are controversial. This controversy is fueled by the complexity of the issues and the paucity of data from high quality clinical trials. Nevertheless, while the use of high-dose corticosteroids in patients with severe sepsis and ARDS failed to improve outcome and was associated with increased complications, an extended course of stress-dose corticosteroids has been reported to increase the occurrence of ventilator-free days and survival in select groups of ICU patients. These patients typically have an exaggerated proinflammatory response. Until recently the exaggerated proinflammatory response that characterizes critically ill patients with systemic inflammation has focused on suppression of the hypothalamic-pituitary-adrenal axis and adrenal failure. However, experimental and clinical data suggest that glucocorticoid tissue resistance may also play an important role. This complex syndrome is referred to as critical illness-related corticosteroid insufficiency (CIRCI) and is defined as inadequate corticosteroid activity for the severity of the illness of a patient. The paper reviews cortisol physiology, CIRCI, and the role of corticosteroid therapy in critically ill patients.

Mechanisms and clinical consequences of critical illness associated adrenal insufficiency

PURPOSE OF REVIEW

Adrenal insufficiency is being diagnosed with increasing frequency in critically ill patients. There exists, however, much controversy in the literature as to the nature of this entity, including its pathophysiology, epidemiology, diagnosis and treatment. The review summarizes our current understanding of the causes and consequences of adrenal insufficiency in critically ill patients.

RELEVANT FINDINGS

Activation of the hypothalamic-pituitary-adrenal axis with the production of cortisol is a fundamental component of the stress response and is essential for survival of the host. Dysfunction of the hypothalamic-pituitary-adrenal axis with decreased glucocorticoid activity is being increasingly recognized in critically ill patients, particularly those with sepsis. This condition is best referred to as 'critical illness-related corticosteroid insufficiency'. Critical illness-related corticosteroid insufficiency may occur due to dysfunction at any point in the hypothalamic-pituitary-adrenal axis including tissue glucocorticoid resistance. Critical illness-related corticosteroid insufficiency leads to an exaggerated proinflammatory response with increased tissue injury and organ dysfunction.

SUMMARY

Critical illness-related corticosteroid insufficiency is common in critically ill patients, particularly those with sepsis. Supplemental corticosteroids may restore the balance between the pro-and anti-inflammatory mediators in patients with severe sepsis, septic shock and acute respiratory distress syndrome, and thereby improve the outcome of patients with these conditions.

A rationale for using steroids in the treatment of severe cases of H5N1 avian influenza

Acute hypercytokinaemia represents an imbalance of pro-inflammatory and anti-inflammatory cytokines, and is believed to be responsible for the development of acute respiratory distress syndrome and multiple organ failure in severe cases of avian (H5N1) influenza. Although neuraminidase inhibitors are effective in treating avian influenza, especially if given within 48 h of infection, it is harder to prevent the resultant hypercytokinaemia from developing if the patient does not seek timely medical assistance. Steroids have been used for many decades in a wide variety of inflammatory conditions in which hypercytokinaemia plays a role, such as sepsis and viral infections, including severe acquired respiratory syndromes and avian influenza. However, to date, the results have been mixed. Part of the reason for the discrepancies might be the lack of understanding that low doses are required to prevent mortality in cases of adrenal insufficiency. Adrenal insufficiency, as defined in the sepsis/shock literature, is a plasma cortisol rise of at least 9 μg dl−1 following a 250 μg dose of adrenocorticotropin hormone (ACTH), or reaching a plasma cortisol concentration of >25 μg dl−1 following a 1–2 μg dose of ACTH. In addition, in the case of hypercytokinaemia induced by potent viruses, such as H5N1, systemic inflammation-induced, acquired glucocorticoid resistance is likely to be present. Adrenal insufficiency can be overcome, however, with prolonged (7–10 or more days) supraphysiological steroid treatment at a sufficiently high dose to address the excess activation of NF-κB, but low enough to avoid immune suppression. This is a much lower dose than has been typically used to treat avian influenza patients. Although steroids cannot be used as a monotherapy in the treatment of avian influenza, there might be a potential role for their use as an adjunct treatment to antiviral therapy if appropriate dosages can be determined. In this paper, likely mechanisms of adrenal insufficiency are discussed, drawing from a broad background of literature sources.

Functional adrenal insufficiency among critically ill patients with human immunodeficiency virus in a resource-limited setting

BACKGROUND

Functional adrenal insufficiency (FAI) is associated with increased mortality and is defined as subnormal cortisol production during acute severe illness.

METHODS

After screening 200 adult patients admitted in the medical emergency unit of Mulago Hospital, Kampala, Uganda, 113 critically ill HIV-infected adults not receiving corticosteroids were enrolled after obtaining informed consent to determine the prevalence and factors associated with FAI.

RESULTS

Functional adrenal insufficiency, defined in this study as morning total serum cortisol level of 3%) occurred in 52% (11 of 21) patients with FAI compared to 24% (22 of 92) patients with normal adrenal function (p= 0.01). Factors predicting FAI on multivariate analysis were use of rifampicin and eosinophilia. The mortality rate among patients with FAI (19%) was not significantly different when compared to that among patients with a normal cortisol response (33%) (p=0.221). Hyponatremia, hypoglycemia, hyperkalemia, postural hypotension and the use of ketoconazole were not associated with FAI in this study.

CONCLUSION

The diagnosis of FAI should be considered in severely ill patients with stage IV HIV disease using rifampicin or those found to have unexplained eosinophilia. Further studies to determine benefits of corticosteroids in critically ill HIV patients are needed in this setting.

Tumor necrosis factor-alpha regulates steroidogenesis, apoptosis, and cell viability in the human adrenocortical cell line NCI-H295R

TNF-alpha regulates the hypothalamo-pituitary-adrenal axis at several levels. It has been shown to modify adrenal steroidogenesis in many species, and it is supposed to act as an auto/paracrine factor. However, its significance in human adrenocortical function remains unclear. Therefore, we investigated the effect of TNF-alpha on adrenal steroidogenesis, expression of the key steroidogenic genes, apoptosis, and cell viability in the human adrenocortical cell line NCI-H295R. TNF-alpha treatment (1 nM for 48 h) decreased the basal production of cortisol, androstenedione, dehydroepiandrosterone sulfate (DHEAS), and aldosterone (14, 18, 35, and 52%, respectively), and the 8-bromo-cAMP-induced production of cortisol, androstenedione, dehydroepiandrosterone (DHEA), and DHEAS (44, 66, 58, and 48%, respectively). However, when the steroid production data were normalized by the cell number, TNF-alpha increased the basal production of cortisol, androstenedione, DHEA, DHEAS, and aldosterone (137, 121, 165, 73, and 28%, respectively), and the 8-bromo-cAMP-induced production of cortisol, DHEAS, and aldosterone (122, 121, and 256%, respectively). This was accompanied by a parallel increase in the expression of the genes encoding for the steroidogenic acute regulatory protein, 3beta-hydroxysteroid dehydrogenase 2, and 17-hydroxylase/17,20-lyase (74, 200, and 50%, respectively; quantitative real-time RT-PCR analysis). TNF-alpha increased caspase 3/7 activity (an indicator of apoptosis) and decreased cell viability dose and time dependently. The effect of TNF-alpha on apoptosis was neutralized by a monoclonal TNF-alpha antibody. These findings indicate that TNF-alpha is a potent regulator of steroidogenesis and cell viability in adrenocortical cells. TNF-alpha may have physiological and/or pathophysiological significance as an endocrine and/or paracrine/autocrine regulator of adrenocortical function.

Adrenal insufficiency in the critically ill: a new look at an old problem

Stress from many sources, including pain, fever, and hypotension, activates the hypothalamic-pituitary-adrenal (HPA) axis with the sustained secretion of corticotropin and cortisol. Increased glucocorticoid action is an essential component of the stress response, and even minor degrees of adrenal insufficiency can be fatal in the stressed host. HPA dysfunction is a common and underdiagnosed disorder in the critically ill. We review the risk factors, pathophysiology, diagnostic approach, and management of HPA dysfunction in the critically ill.

Adrenal insufficiency in critically ill patients with human immunodeficiency virus

OBJECTIVE

The adrenal gland is the endocrine organ most commonly involved in patients infected with human immunodeficiency virus (HIV). It is important to recognize patients with adrenal insufficiency, because this disorder may be fatal if untreated. The incidence of adrenal insufficiency in critically ill HIV-infected patients is unclear, partly because different criteria are used to diagnose adrenal insufficiency. To help clarify the incidence of adrenal insufficiency in HIV-infected critically ill patients, we compared the incidence based on the stress cortisol concentration, low-dose corticotropin stimulation test, and high-dose corticotropin stimulation test.

SETTING

Medical intensive care unit.

PATIENTS

Twenty-eight critically ill patients with HIV, mean age 43 +/- 9 years; 20 were male; 54% died.

INTERVENTIONS

We performed a 1-microg (low-dose adrenocorticotropic hormone; LD-ACTH) and 249 microg (high-dose; HD-ACTH) corticotropin stimulation test in HIV-infected critically ill patients not receiving corticosteroids. According to results of the stress serum cortisol concentration and LD-ACTH and HD-ACTH tests, patients were classified as having adrenal insufficiency or as normal. The results of newly revised diagnostic criteria for adrenal insufficiency (i.e., stress cortisol concentration and cortisol response to LD-ACTH <25 microg/dL) were compared with the traditional criteria (i.e., stress cortisol level and response to HD-ACTH <18 microg/dL). In addition, the associations between adrenal insufficiency and the CD4 count, human cytomegalovirus antigenemia, and other risk factors for adrenal insufficiency were determined.

MEASUREMENTS AND MAIN RESULTS

When we used a stress cortisol concentration <18 microg/dL as the sole diagnostic threshold for diagnosis of adrenal insufficiency, 50% (14 of 28) of patients had adrenal insufficiency. The incidence was 75% (21 of 28) when we used a diagnostic threshold of <25 microg/dL for the stress cortisol concentration. When we used both the stress cortisol concentration and LD-ACTH test with a diagnostic cortisol threshold concentration <18 microg/dL, 21% (six of 28) had adrenal insufficiency. The incidence was 46% (13 of 28) when we used a cortisol diagnostic threshold concentration of <25 microg/dL. When we used both the stress cortisol concentration and the HD-ACTH stimulation test with a diagnostic cortisol threshold of <18 microg/dL, 7% (two of 28) had adrenal insufficiency. The incidence of adrenal insufficiency was 21% (six of 28) with a cortisol diagnostic threshold value of <25 microg/dL. Human cytomegalovirus antigenemia was the only variable assessed that was associated with adrenal insufficiency.

CONCLUSION

There is a high incidence of adrenal insufficiency in critically ill HIV-infected patients that varies with the criteria used to diagnose adrenal insufficiency. The LD-ACTH stimulation test is more sensitive than the high-dose test for diagnosing adrenal insufficiency in this population. Because of the high incidence of inadequate adrenal function, all critically ill HIV-infected patients should undergo an evaluation for adrenal insufficiency with the stress cortisol concentration and LD-ACTH stimulation tests.

Neuroimmunoregulation of androgens in the adrenal gland and the skin

Human adrenals produce large quantities of androgens, especially DHEA which is the most abundant circulating hormone in the human body. Adrenal androgens are regulated by several factors, including pituitary ACTH and an intricate intraadrenal network involving immune cells, cytokines and neuroendocrine factors. The skin is a major target of androgens and androgen receptors are expressed in the epidermis, dermis, sebaceous glands and hair. In addition, the skin has the capacity to metabolize androgens into more powerful compounds. Similar to the adrenal gland, there is an intradermal neuro-immune network involving the local expression of cytokines and neuropeptides. Dysregulation of androgens in the adrenals and/or the skin is associated with acne, hirsutism and androgenic alopecia. Therefore, understanding the mechanisms of these intricate networks is of both basic and clinical relevance and may help to develop new strategies for the treatment of androgen-dependent skin disorders.

Possible function of IL-6 and TNF as intraadrenal factors in the regulation of adrenal steroid secretion

Interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF alpha) and their mRNAs are present in the human, rat, and bovine adrenal cortex. The release of these cytokines from adrenal cells is regulated by factors that alter adrenal function (e.g., ACTH, angiotensin II, interleukin-1). IL-6 and TNF type 1 receptors are also present on adrenocortical cells. Exposure to IL-6 increases cortisol or corticosterone release from human, bovine, and rat adrenal cells. IL-6 increases basal and ACTH-stimulated aldosterone release, but inhibits angiotensin II-stimulated aldosterone secretion from bovine adrenal cells. IL-6 increases dehydroepiandrosterone (DHEA) release from human cells, but decreases DHEA secretion from bovine cells. TNF alpha inhibits corticosterone release from normal rat adrenal cells or fragments, but increases corticosterone release from cholestatic rat adrenal slices. TNF alpha decreases cortisol release from bovine and fetal human adrenal cells, but increases cortisol release from adult human adrenal cells. TNF alpha inhibits aldosterone secretion from rat and bovine adrenocortical cells. TNF alpha does not affect DHEA secretion from fetal human adrenocortical cells, but inhibits basal and ACTH-stimulated DHEA release from bovine adrenal cell. Because IL-6 and TNF alpha are produced in the adrenal gland and modify adrenal steroid secretion, these cytokines may function as intraadrenal factors in the regulation of adrenal steroid secretion.

Hypothalamic-pituitary-adrenal insufficiency

Adrenal insufficiency is a common and underdiagnosed disorder that develops in critically ill patients. Most forms are acquired and will resolve with treatment of the underlying disease. Hypotension that is refractory to fluids and requires vasopressors is the most common presentation of adrenal insufficiency in the ICU. It is important to make the diagnosis of adrenal insufficiency, because current data suggest that treatment with glucocorticoids improves outcome. Diagnosis usually can be made on the basis of a stress cortisol level. Occasionally, when the level of stress is uncertain, the low-dose corticotropin stimulation test will be required for definitive diagnosis. A therapeutic trial with hydrocortisone should be started in patients with suspected adrenal insufficiency pending results of diagnostic testing.

Stimulation by interleukin-6 and inhibition by tumor necrosis factor of cortisol release from bovine adrenal zona fasciculata cells through their receptors

Interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) are synthesized and released from adrenal cells. Therefore, the effects of TNF-alpha and IL-6 on cortisol release from bovine zona fasciculata (ZF) cells were investigated. IL-6 (10-1000 pg/mL) significantly increased basal and adrenocorticotropic hormone (ACTH)-stimulated cortisol release in a concentration-dependent manner. This stimulatory effect of IL-6 became apparent at intervals as short as 4 h and continued through 24 h. IL-6 also potentiated the cortisol release stimulated by the adenylyl cyclase activator forskolin. By contrast, TNF-alpha (0.1-10 ng) inhibited basal and ACTH-stimulated cortisol release in a concentration-dependent manner. The inhibitory effects of TNF-alpha on cortisol release were significant at time intervals as short as 4 h and continued through 24 h. TNF-alpha inhibited forskolin-stimulated cortisol release. Binding studies demonstrated that ZF cells have IL-6 receptors (100 receptors/cell, Kd of 7.5 x 10(-11)) and TNF receptors (200 receptors/cell, Kd of 2.4 x 10(-9) M). Immunohistochemical analysis provided evidence that the majority of ZF cells have IL-6 receptors, TNF type 1 receptors, and TNF type 2 receptors. Because IL-6 and TNF-alpha are released from the adrenal cortex and these cytokines modify the release of cortisol from the ZF, IL-6 and TNF-alpha may play a paracrine or autocrine role in the regulation of adrenal function.

Bovine adrenal cells secrete interleukin-6 and tumor necrosis factor in vitro

Interleukin-6 (IL-6) and tumor necrosis factor (TNF) are secreted and/or synthesized by the rat and human adrenal cortex. In this study, the release of IL-6 and TNF from bovine adrenal cells was determined. Bovine adrenal glands were collected from an abattoir and dissected into the zona glomerulosa (ZG), zona fasciculata (ZF), zona reticularis (ZR), and medulla. The tissues were enzymatically dispersed to single cells and cultured for 4-6 days. The cells were then exposed (4 h) to angiotensin II (AII), adrenocorticotrophic hormone (ACTH), phorbol dibutyrate (PDB), interleukin-1beta (IL-1beta), interleukin-1alpha (IL-1alpha), and endotoxin (LPS). The IL-6 and TNF content of the incubation medium was determined by bioassays. The release of IL-6 and TNF from the ZG, ZF, ZR, and medulla was increased by PDB, IL-1alpha, IL-1beta, and LPS. In contrast, ACTH and AII increased IL-6 release from the ZG, ZF, and ZR but had no effect on IL-6 release from the medulla. ACTH decreased TNF release from all adrenal cortical zones but had no effect on TNF release from the medulla. Immunohistochemistry utilizing antibodies against TNFalpha demonstrated TNFalpha-containing cells throughout the adrenal gland. The majority of the cells of the ZG, ZF, and ZR contained TNFalpha. However, the cells of the ZG contained more TNFalpha than the cells of the ZR or ZF. Small patches of TNFalpha-containing cells were also found in the adrenal medulla and capsule. These findings support the hypothesis that IL-6 and TNF may have autocrine/paracrine effects on the adrenal gland.

Regulation of the hypothalamic-pituitary-adrenal axis by cytokines: actions and mechanisms of action

Glucocorticoids are hormone products of the adrenal gland, which have long been recognized to have a profound impact on immunologic processes. The communication between immune and neuroendocrine systems is, however, bidirectional. The endocrine and immune systems share a common "chemical language," with both systems possessing ligands and receptors of "classical" hormones and immunoregulatory mediators. Studies in the early to mid 1980s demonstrated that monocyte-derived or recombinant interleukin-1 (IL-1) causes secretion of hormones of the hypothalamic-pituitary-adrenal (HPA) axis, establishing that immunoregulators, known as cytokines, play a pivotal role in this bidirectional communication between the immune and neuroendocrine systems. The subsequent 10-15 years have witnessed demonstrations that numerous members of several cytokine families increase the secretory activity of the HPA axis. Because this neuroendocrine action of cytokines is mediated primarily at the level of the central nervous system, studies investigating the mechanisms of HPA activation produced by cytokines take on a more broad significance, with findings relevant to the more fundamental question of how cytokines signal the brain. This article reviews published findings that have documented which cytokines have been shown to influence hormone secretion from the HPA axis, determined under what physiological/pathophysiological circumstances endogenous cytokines regulate HPA axis activity, established the possible sites of cytokine action on HPA axis hormone secretion, and identified the potential neuroanatomic and pharmacological mechanisms by which cytokines signal the neuroendocrine hypothalamus.

Immune-endocrine interactions in the mammalian adrenal gland: facts and hypotheses

Several cytokines, which are the major mediators of the inflammatory responses, are well-known to stimulate the hypothalamopituitary corticotropin-releasing hormone (CRH)/adrenocorticotropic hormone (ACTH) system, thereby evoking secretory responses by the adrenal cortex. Many of these cytokines, including interleukin-1 (IL-1), IL-2, IL-6, tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (INF-gamma) are synthesized in the adrenal gland by both parenchymal cells and resident macrophages, and the release of some of them (e.g., IL-6 and TNF-alpha) is regulated by the main agonists of steroid hormone secretion (e.g., ACTH and angiotensin-II) and bacterial endotoxins. Adrenocortical and adrenomedullary cells are provided with specific receptors for IL-1, IL-2, and IL-6. IL-1 and TNF-alpha directly inhibit aldosterone secretion of zona glomerulosa cells, whereas IL-6 enhances it. IL-2, IL-3, IL-6, and INF-alpha are able to directly stimulate glucocorticoid production by zona fasciculata and zona reticularis cells, whereas IL-1 exerts an analogous effect through an indirect mechanism involving the stimulation of catecholamine release by chromaffin cells and/or the activation of the intramedullary CRH/ACTH system; again, TNF-alpha depresses glucocorticoid synthesis. IL-6 raises androgen secretion by inner adrenocortical layers. IL-1 enhances the proliferation of adrenocortical cells, and findings suggest that cytokines may control the apoptotic deletion of senescent zona reticularis cells. The relevance of the intraadrenal cytokine system in the fine-tuning of the secretion and growth of the adrenal cortex under normal conditions remains to be explored. However, indirect proof is available that local immune-endocrine interactions may play an important role in modulating adrenal responses to inflammatory and immune challenges and stresses.

Serotonin increases interleukin-6 release and decreases tumor necrosis factor release from rat adrenal zona glomerulosa cells in vitro

Interleukin-6 (IL-6) and tumor necrosis factor (TNF) are secreted by rat adrenal zona glomerulosa cells. Serotonin increases the release of aldosterone, corti-costerone, and cortisol from the adrenal cortex. Therefore, the effects of serotonin on IL-6 and TNF release from rat adrenal zona glomerulosa cells were investigated. Cultures of rat adrenal zona glomerulosa cells were enzymatically prepared and cultured for 4-6 d. The cells were then exposed to serum-free RPMl-1640 medium containing vehicle (RPMl medium alone), serotonin, and/or endotoxin, interleukin-1β, or adrenocorticotrophic hormone (ACTH). Following a 5-h incubation, medium was removed from the cells, and IL-6 and TNF content of this medium determined with bioassays. Serotonin (1-1000 nM) increased basal IL-6 release from zona glomerulosa cells, but inhibited basal TNF release from these cells. Endotoxin and interleukin-1β (IL-1β) increased IL-6 and TNF release from zona glomerulosa cells. Serotonin potentiated IL-6 release stimulated by endotoxin and IL-1β, but inhibited TNF release stimulated by these agents. Serotonin potentiated ACTH-stimulated IL-6 release. Serotonin had no effect on IL-6 release from rat anterior pituitary cells. Because IL-6, TNF, and serotonin modify the release of aldosterone and glucocorticoids from adrenal cells, the stimulatory effects of serotonin on aldosterone and glucocorticoid release may be mediated in part by the effects of serotonin on IL-6 and TNF release from adrenal cells.

Tumor necrosis factor increases interleukin-6 release from adrenal zona glomerulosa cellsin vitro

Rat adrenal zone glomerulosa cells secrete tumor necrosis factor (TNF) and interleukin-6 (IL-6). We have extended previous studies to determine if TNFα can modify the release of adrenal IL-6. Primary cultures of rat adrenal zone glomerulosa cells were prepared by enzymatic techniques and cultured for 4-6 days. The cells were then exposed to serum-free RPMI 1640 incubation medium containing vehicle (RPMI-1640 medium alone), TNFα and/or selected agents known to stimulate adrenal IL-6 release. Following a 5 h incubation, the incubation medium was removed from the cells and the IL-6 content of the medium measured with the 7TD1 bioassay. TNFα (0.5-50 ng/mL) increased basal adrenal IL-6 release in a concentration-dependent manner. Furthermore, TNFα potentiated in a more than additive manner the adrenal IL-6 release stimulated by lipopolysac-charide (LPS), interleukin-1β, angiotensin II and ACTH. TNFα potentiated the IL-6 release stimulated by a wide range of concentration of IL-lβ (0.01-100 ng/mL) and ACTH (0.1-100 nM). Because IL-6 and TNFα modify the steroid secretion from adrenal cells, these cytokines may interact together to regulate the function of the adrenal cortex.

Differential release of tumor necrosis factor and IL-6 from adrenal zona glomerulosa cells in vitro

In previous studies, rat adrenal zona glomerulosa (ZG) cells were demonstrated to release interleukin-6 (IL-6). In the current study, cultures of ZG cells and bioassays for tumor necrosis factor (TNF) and IL-6 were used to determine if ZG cells release TNF and to define more fully the factors that regulate ZG IL-6 release. ZG cells released IL-6 and TNF, and this release was stimulated by lipopolysaccharide, interleukin-1 alpha, interleukin-1 beta, a protein kinase C activator, and a calcium ionophore without affecting intracellular adenosine 3', 5'-cyclic monophosphate (cAMP) content. In contrast, adrenocorticotropic hormone (ACTH) increased the intracellular cAMP content, increased basal and secretagogue-stimulated IL-6 release but decreased basal and secretagogue-stimulated TNF release. The effects of ACTH on IL-6 and TNF release may be mediated by increases in intracellular cAMP because ACTH and dibutyryl cAMP modified IL-6 and TNF release in an identical manner. Therefore, IL-6 and TNF release from ZG cells can be differentially regulated. Because IL-6 and TNF modify adrenal steroid release, the adrenal production of these cytokines may have a role in the stress response.

Tumor necrosis factor-alpha and interferon-gamma inhibit insulin-like growth factor II gene expression in human fetal adrenal cell cultures

Insulin-like growth factor-II (IGF-II) gene expression is induced by adrenocorticotropic hormone (ACTH) in human fetal adrenals (HFA), which suggests an important role for IGF-II in HFA growth and differentiation. Many cytokines have different regulatory actions in the endocrine glands. In the present study we have investigated the effects of two cytokines, tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma), on the regulation of IGF-II gene expression in cultured HFA cells. Both TNF-alpha and IFN-gamma inhibited basal and ACTH-induced accumulation of IGF-II mRNA dose-dependently. Cell viability was not altered by treatment with TNF-alpha or IFN-gamma. In addition, the combination of TNF-alpha and IFN-gamma decreased ACTH-induced IGF-II mRNAs more potently than each cytokine alone. Our results suggest that TNF-alpha and IFN-gamma may be involved in the regulation of HFA growth and differentiation via local IGF-II production.