Dynamic pituitary-adrenal interactions in response to cardiac surgery

Peri-operative Replacement of Exogenous Steroids (PREdS): a national audit of current peri-operative prescribing for patients taking therapeutic steroids

INTRODUCTION

Approximately 1% of the UK population take oral corticosteroids for ≥ 28 days each year, for broadly two reasons: deficiency in corticosteroid requiring replacement; or therapeutic corticosteroid for inflammatory conditions. Acute deficiency can occur at times of physiological stress (e.g. surgery), potentially leading to major complications. The Association of Anaesthetists' 2020 consensus guideline provides detailed advice for the management of glucocorticoids during the peri-operative period for patients with adrenal insufficiency. This national audit aimed to assess compliance with this guideline.

METHODS

Data were collected from 59 Trusts over 14 consecutive days for all eligible patients undergoing procedures under the care of an anaesthetist. Patients who were prescribed ≥ 5 mg oral prednisolone equivalents pre-operatively, in whom supplementary corticosteroid would be indicated, were compared with those prescribed < 5 mg oral prednisolone equivalents.

RESULTS

Operations for 21,731 patients were audited: 277 (1.3%) patients were taking therapeutic corticosteroids. Detailed peri-operative data were collected for all patients receiving therapeutic corticosteroids: 201/277 (73%) were ASA physical status ≥ 3; 184/277 (66%) underwent elective procedures; and 252/277 (91%) were prescribed prednisolone pre-operatively, of whom 219/277 (79%) were prescribed ≥ 5 mg oral prednisolone equivalents. In the patients who were prescribed ≥ 5 mg oral prednisolone equivalents, 186/219 (85%) received pre-operative glucocorticoid supplementation and 97/219 (42%) received it postoperatively; however, only 67/219 (31%) and 43/219 (20%) respectively received glucocorticoid supplementation according to the guidelines. Overall, peri-operative prescribing was compliant in 19/219 (9%) patients. A similar proportion, 30/219 (14%), received no supplementation. In the patients taking < 5 mg oral prednisolone equivalents pre-operatively, 28/58 (48%) received inappropriate supplementation.

CONCLUSIONS

Despite 125/277 (45%) of anaesthetists reporting Association of Anaesthetists' guidelines use, compliance remained low, with adherence in only 27/125 (22%) patients. Further research is required to identify the correct peri-operative strategy for patients taking therapeutic corticosteroids.

The effect of pectointercostal fascial block on stress response in open heart surgery

Background

Activation of the hypothalamus-pituitary-adrenal (HPA) axis and inflammatory processes are common forms of stress response. The increased stress response is associated with a higher chance of complications. Open hearth surgery is one of the procedures with a high-stress response. Pectointercostal fascial block (PIFB), as a new pain management option in sternotomy, has the potential to modulate the stress response.

Objective

To determine the effect of PIFB on stress response in open heart surgery.

Methods

This study was a Randomized Controlled Trial on 40 open heart surgery. Patients were divided into two groups, control (20 patients) and PIFB (20 patients). Primary parameters included basal and postoperative TNF-α, basal and post sternotomy ACTH, and basal, 0, and 24 hours postoperative NLR. Secondary parameters include the amount of opioid use, length of the post-operative ventilator, length of ICU stay, and Numeric Rating Scale (NRS) 6, 12, 24, and 48 hours postoperative.

Results

The PIFB group had a decrease in ACTH levels with an average change that was not significantly different from the control group (-57.71 ± 68.03 vs. -129.78 ± 140.98). The PIFB group had an average change in TNFα levels and an average increase in NLR 0 hours postoperative that was not significantly lower than the control group (TNFα: -0.52 ± 1.31 vs. 0.54 ± 1.76; NLR: 12.80 ± 3.51 vs. 14.82 ± 4.23). PIFB significantly reduced the amount of opioid use during surgery, NRS at 6, 12, and 24 hours, and the length of post-operative ventilator use (P < 0.05, CI: 95%).

Conclusion

PIFB has a good role in reducing the stress response of open heart surgery and producing good clinical outcomes.

The Hypothalamus-pituitary-adrenocortical Response to Critical Illness: A Concept in Need of Revision

Based on insights obtained during the past decade, the classical concept of an activated hypothalamus-pituitary-adrenocortical axis in response to critical illness is in need of revision. After a brief central hypothalamus-pituitary-adrenocortical axis activation, the vital maintenance of increased systemic cortisol availability and action in response to critical illness is predominantly driven by peripheral adaptations rather than by an ongoing centrally activated several-fold increased production and secretion of cortisol. Besides the known reduction of cortisol-binding proteins that increases free cortisol, these peripheral responses comprise suppressed cortisol metabolism in liver and kidney, prolonging cortisol half-life, and local alterations in expression of 11βHSD1, glucocorticoid receptor-α (GRα), and FK506 binding protein 5 (FKBP51) that appear to titrate increased GRα action in vital organs and tissues while reducing GRα action in neutrophils, possibly preventing immune-suppressive off-target effects of increased systemic cortisol availability. Peripherally increased cortisol exerts negative feed-back inhibition at the pituitary level impairing processing of pro-opiomelanocortin into ACTH, thereby reducing ACTH-driven cortisol secretion, whereas ongoing central activation results in increased circulating pro-opiomelanocortin. These alterations seem adaptive and beneficial for the host in the short term. However, as a consequence, patients with prolonged critical illness who require intensive care for weeks or longer may develop a form of central adrenal insufficiency. The new findings supersede earlier concepts such as "relative," as opposed to "absolute," adrenal insufficiency and generalized systemic glucocorticoid resistance in the critically ill. The findings also question the scientific basis for broad implementation of stress dose hydrocortisone treatment of patients suffering from acute septic shock solely based on assumption of cortisol insufficiency.

Characterizing Alterations in Cortisol Secretion During Cardiac Surgery

Cortisol is a neuroendocrine hormone of the hypothalamus-pituitary-adrenal (HPA) axis secreted from adrenal glands in response to stimulation by adrenocorticotropic hormone (ACTH) from the anterior pituitary and corticotropin releasing hormone (CRH) from the hypothalamus. Cortisol has multiple functionalities in maintaining bodily homeostasis - including anti-inflammatory influences - through its diurnal secretion pattern (which has been studied extensively); its secretion is also increased in response to major traumatic events such as surgery. Due to the adverse health consequences of an abnormal immune response, it is crucial to understand the effect of cortisol in modulating inflammation. To address this physiological issue, we characterize the secretion of cortisol using a high temporal resolution dataset of ten patients undergoing coronary arterial bypass grafting (CABG) surgery, in comparison with a control group not undergoing surgery. We find that cortisol exhibits different pulsatile dynamics in those undergoing cardiac surgery compared to the control subjects. We also summarize the causality of cortisol's relationship with different cytokines (which are one type of inflammatory markers) by performing Granger causality analysis.Clinical relevance- This work documents time-varying patterns of the HPA axis hormone cortisol in the inflammatory response to cardiac surgery and may eventually help improve patients' prognosis post-surgery (or in other conditions) by enabling early detection of an abnormal cortisol or inflammatory response and enabling patient specific remedial interventions.

Evaluation of the stress-reducing effect of trace mineral injection in beef calves

BACKGROUND

Little is known about the effects of trace mineral supplementation on the stress response in beef calves.

OBJECTIVES

To investigate the effect of injectable trace mineral supplementation (ITM) on the stress response in beef calves exposed to different types of stress.

ANIMALS

Thirty weaned Angus and Angus crossbred calves.

METHODS

The enrolled calves were randomly assigned to 2 groups: ITM, 15 calves received modified-live virus vaccine (MLV) and ITM SC and 15 calves received MLV and saline SC (CONT). The calves were exposed to 3 types of stress: the stress of MLV vaccination (d0), nasal aerosol with bovine viral diarrhea virus-2 (BVDV-2) challenge (d5), and liver biopsy (d26). The calves' body weights and health status were monitored. Leukocyte counts, serum cortisol concentration ([cort]), BVDV-2 serum neutralizing antibodies (SNA), and percentages of CD4⁺ , CD8⁺ , WC1⁺ _, and CD25⁺ T-lymphocytes were measured.

RESULTS

Serum cortisol concentration ([cort]) showed strong associations with the percentage of CD8⁺ (r_s  = .50), BVDV2-SNA (r_s  = -.43), and WC1CD25⁺ (r_s  = .41) cells, and rectal temperature (r_s  = .40). The highest [cort] was reported 3 days after aerosol BVDV-2 challenge. Serum [cort] was decreased in ITM-treated calves 3 days post-BVDV-2 challenge, compared with CONT calves, with an average decrease of 18.5 ng/μL (95% confidence interval [CI], -6.07 to -31.3). The ITM-treated calves were heavier and healthier (P < .01) than the CONT calves.

CONCLUSIONS AND CLINICAL IMPORTANCE

Trace mineral supplementation appears to have stress mitigation effects in beef cattle that may reflect positively on growth and health performance. Viral exposure is associated with a high degree of stress, which is considered a major welfare concern.

Ouabain Reverts CUS-Induced Disruption of the HPA Axis and Avoids Long-Term Spatial Memory Deficits

Ouabain (OUA) is a cardiotonic steroid that modulates Na+, K+ -ATPase activity. OUA has been identified as an endogenous substance that is present in human plasma, and it has been shown to be associated with the response to acute stress in both animals and humans. Chronic stress is a major aggravating factor in psychiatric disorders, including depression and anxiety. The present work investigates the effects of the intermittent administration of OUA (1.8 μg/kg) during the chronic unpredictable stress (CUS) protocol in a rat's central nervous system (CNS). The results suggest that the intermittent OUA treatment reversed CUS-induced HPA axis hyperactivity through a reduction in (i) glucocorticoids levels, (ii) CRH-CRHR1 expression, and by decreasing neuroinflammation with a reduction in iNOS activity, without interfering with the expression of antioxidant enzymes. These changes in both the hypothalamus and hippocampus may reflect in the rapid extinction of aversive memory. The present data demonstrate the ability of OUA to modulate the HPA axis, as well as to revert CUS-induced long-term spatial memory deficits.

Postoperative systemic inflammatory dysregulation and corticosteroids: a narrative review

In some patients, the inflammatory-immune response to surgical injury progresses to a harmful, dysregulated state. We posit that postoperative systemic inflammatory dysregulation forms part of a pathophysiological response to surgical injury that places patients at increased risk of complications and subsequently prolongs hospital stay. In this narrative review, we have outlined the evolution, measurement and prediction of postoperative systemic inflammatory dysregulation, distinguishing it from a healthy and self-limiting host response. We reviewed the actions of glucocorticoids and the potential for heterogeneous responses to peri-operative corticosteroid supplementation. We have then appraised the evidence highlighting the safety of corticosteroid supplementation, and the potential benefits of high/repeated doses to reduce the risks of major complications and death. Finally, we addressed how clinical trials in the future should target patients at higher risk of peri-operative inflammatory complications, whereby corticosteroid regimes should be tailored to modify not only the a priori risk, but also further adjusted in response to markers of an evolving pathophysiological response.

Perioperative Evaluation and Management of Patients on Glucocorticoids

Myriad questions regarding perioperative management of patients on glucocorticoids (GCs) continue to be debated including which patients are at risk for adrenal insufficiency (AI), what is the correct dose and duration of supplemental GCs, or are they necessary for everyone? These questions remain partly unanswered due to the heterogeneity and low quality of data, studies with small sample sizes, and the limited number of randomized trials. To date, we know that although all routes of GC administration can result in hypothalamic-pituitary-adrenal (HPA) axis suppression, perioperative adrenal crisis is rare. Correlation between biochemical testing for AI and clinical events is lacking. Some of the current perioperative management recommendations based on daily GC dose and duration of therapy may be difficult to follow in clinical practice. The prospective and retrospective studies consistently report that continuing the daily dose of GCs perioperatively is not associated with a higher risk for adrenal crises in patients with GC-induced AI. Considering that oral GC intake may be unreliable in the early postoperative period, providing the daily GC plus a short course of IV hydrocortisone 25 to 100 mg per day based on the degree of surgical stress seems reasonable. In patients who have stopped GC therapy before surgery, careful assessment of the HPA axis is necessary to avoid an adrenal crisis. In conclusion, our literature review indicates that lower doses and shorter duration of supplemental GCs perioperatively are sufficient to maintain homeostasis. We emphasize the need for well-designed randomized studies on this frequently encountered clinical scenario.

Novel insights in endocrine and metabolic pathways in sepsis and gaps for future research

Sepsis is defined as any life-threatening organ dysfunction caused by a dysregulated host response to infection. It remains an important cause of critical illness and has considerable short- and long-term morbidity and mortality. In the last decades, preclinical and clinical research has revealed a biphasic pattern in the (neuro-)endocrine responses to sepsis as to other forms of critical illness, contributing to development of severe metabolic alterations. Immediately after the critical illness-inducing insult, fasting- and stress-induced neuroendocrine and cellular responses evoke a catabolic state in order to provide energy substrates for vital tissues, and to concomitantly activate cellular repair pathways while energy-consuming anabolism is postponed. Large randomized controlled trials have shown that providing early full feeding in this acute phase induced harm and reversed some of the neuro-endocrine alterations, which suggested that the acute fasting- and stress-induced responses to critical illness are likely interlinked and benefical. However, it remains unclear whether, in the context of accepting virtual fasting in the acute phase of illness, metabolic alterations such as hyperglycemia are harmful or beneficial. When patients enter a prolonged phase of critical illness, a central suppression of most neuroendocrine axes follows. Prolonged fasting and central neuroendocrine suppression may no longer be beneficial. Although pilot studies have suggested benefit of fasting-mimicking diets and interventions that reactivate the central neuroendocrine suppression selectively in the prolonged phase of illness, further study is needed to investigate patient-oriented outcomes in larger randomized trials.

Forgetting the Unforgettable: Transient Global Amnesia Part I: Pathophysiology and Etiology

Transient global amnesia (TGA) is a clinical syndrome characterized by the sudden onset of a temporary memory disorder with a profound anterograde amnesia and a variable impairment of the past memory. Since the first description, dating back over 60 years, several cases have beenreported in the literature. Nevertheless, TGA remains one of the most mysterious diseases in clinical neurology. The debate regarding the etiology of this disease has focused mainly on three different mechanisms: vascular (due to venous flow changes or focal arterial ischemia), epileptic, and migraine related. However, to date there is no scientific proof of any of these mechanisms. Furthermore, the demonstration by diffusion-weighted MRI of lesions in the CA1 field of the hippocampus cornu ammonis led us to hypothesize that the selective vulnerability of CA1 neurons to metabolic stress could play a role in the pathophysiology of TGA. In this review, we summarize current knowledge on the anatomy, vascularization and function of the hippocampus. Furthermore, we discuss the emerging theories on the etiology and the pathophysiological cascade leading to an impairment of hippocampal function during the attacks.

Tumor regionalization after surgery: Roles of the tumor microenvironment and neutrophil extracellular traps

Surgery is unanimously regarded as the primary strategy to cure solid tumors in the early stages but is not always used in advanced cases. However, tumor surgery must be carefully considered because the risk of metastasis could be increased by the surgical procedure. Tumor surgery may result in a deep wound, which induces many biological responses favoring tumor metastasis. In particular, NETosis, which is the process of forming neutrophil extracellular traps (NETs), has received attention as a risk factor for surgery-induced metastasis. To reduce cancer mortality, researchers have made efforts to prevent secondary metastasis after resection of the primary tumor. From this point of view, a better understanding of surgery-induced metastasis might provide new strategies for more effective and safer surgical approaches. In this paper, recent insights into the surgical effects on metastasis will be reviewed. Moreover, in-depth opinions about the effects of NETs on metastasis will be discussed.

Therapies that limit the formation of web-like structures formed by white cells known as neutrophils may lower the risk of cancer spread (metastasis) following surgical tumor removal. Removing solid tumors remains a key cancer treatment, but in some cases surgery itself increases the risk of metastasis. Jong-Wan Park at Seoul National University, South Korea, and co-workers reviewed current understanding of metastasis following surgery. Surgical removal destroys the architecture supporting cancer cells but this can release tumor cells into blood vessels. The stress of deep wounds also affects immune responses, most notably neutrophil extracellular traps (NETs), web-like structures formed by neutrophils to trap and kill pathogens. NETs have previously been implicated in metastasis. In a post-surgical environment enriched in neutrophils and pro-inflammatory cytokines, NET formation may help cancer cells thrive, promoting metastasis.

Characterization of a paradoxical post-operative increase in serum cortisol in Cushing disease

PURPOSE

In Cushing disease, early post-operative serum cortisol fluctuations have not been adequately characterized, and their association with initial remission and recurrence is unclear.

METHODS

A retrospective cohort study of patients with Cushing disease was conducted at two institutions. A "riser" was defined a priori as a paradoxical increase in serum cortisol with an immediate incremental increase in serum cortisol over three consecutive cortisol draws separated by roughly 6-h (definition 1). Post hoc analyses used a definition of two consecutive increases (definition 2). Risers were compared to non-risers for initial remission and time-to-recurrence.

RESULTS

A total of 505 patients with Cushing disease were screened, and 469 had adequate data for group assignment. Analysis of post-operative cortisol showed a subgroup of "risers" with a frequency of 3.6% for definition 1 and 42.6% for definition 2. In these patients, cortisol levels were significantly higher until approximately 36 h post-operatively, and cortisol had a significantly longer mean serum half-life. In the post hoc analysis, definition 2 risers had a lower remission rate compared to non-risers (162/196, 82.7%, versus 243/264, 92.0%) with an odds ratio of 0.41 (0.23-0.73; p = 0.003). For both definitions, recurrence was similar between groups.

CONCLUSIONS

We found that almost half of Cushing disease patients experienced a temporary increase in serum cortisol level during the early post-operative period. Serum cortisol half-life was longer, and the remission rates were lower, however, recurrence rates were similar to non-risers.

Modelling the dynamic interaction of systemic inflammation and the hypothalamic-pituitary-adrenal (HPA) axis during and after cardiac surgery

Major surgery and critical illness produce a potentially life-threatening systemic inflammatory response. The hypothalamic-pituitary-adrenal (HPA) axis is one of the key physiological systems that counterbalances this systemic inflammation through changes in adrenocorticotrophic hormone (ACTH) and cortisol. These hormones normally exhibit highly correlated ultradian pulsatility with an amplitude modulated by circadian processes. However, these dynamics are disrupted by major surgery and critical illness. In this work, we characterize the inflammatory, ACTH and cortisol responses of patients undergoing cardiac surgery and show that the HPA axis response can be classified into one of three phenotypes: single-pulse, two-pulse and multiple-pulse dynamics. We develop a mathematical model of cortisol secretion and metabolism that predicts the physiological mechanisms responsible for these different phenotypes. We show that the effects of inflammatory mediators are important only in the single-pulse pattern in which normal pulsatility is lost-suggesting that this phenotype could be indicative of the greatest inflammatory response. Investigating whether and how these phenotypes are correlated with clinical outcomes will be critical to patient prognosis and designing interventions to improve recovery.

Patterns and Determinants of Change in Cortisol Levels and Thyroid Function as a Function of Cardiac Risk in Children Undergoing Cardiac Surgery

Background

Children undergoing cardiac surgery with cardiopulmonary bypass (CPB) are exposed to the risk of hormonal imbalances resulting from acute stress, which may eventually result in high postoperative mortality and morbidity.

Objective

We assessed adrenal and thyroid hormonal changes and their determinants following cardiac surgery in children and explored their prognostic value in predicting cardiac outcomes. Study Design and Methods. A prospective cohort study was conducted at King Abdulaziz University Hospital (KAUH), between 2017 and 2018. The study involved 46 children aged 14 years or younger who underwent elective cardiac surgery with cardiopulmonary bypass. Serum levels of cortisol, TSH, fT3, and fT4 were measured preoperatively and 24, 48, and 72 hours after surgery. The cardiac risk was assessed using the risk adjustment for congenital heart surgery (RACHS) scale. A composite cardiovascular outcome was analyzed as a numerical variable and calculated as the number of cardiovascular events.

Results

Overall, the changes in thyroid function parameters resulted in a U-shaped curve, while cortisol levels yielded a bell-shaped curve. The most significant changes occurred at 24 hours postop, including a decrease in mean TSH by 2.08 μIU/L (p < 0.001), fT3 by 2.39 pmol/L (p < 0.001), and fT4 by 2.45 pmol/L (p < 0.001) and an increase in cortisol levels by 406.48 nmol/L (p < 0.001) with respect to the baseline. Cortisol concentration peaked higher and recovered slower among patients with high cardiac risk than their counterparts. Cardiovascular outcomes were independently predicted by the extent of the decline in fT4 and TSH at 48 and 72 hours postop, with reference to the baseline, and by the cortisol level at 24 h postop, independent of the baseline, besides the RACHS category.

Conclusion

Cardiac surgery among children yields a high adrenocortical response and a high incidence of nonthyroidal illness syndrome, increasing cardiovascular risk. A preventive management strategy involves improving surgical techniques to minimize trauma-related stress.

Weekday and outcomes of elective cardiac surgery in the UK: a large retrospective database analysis

OBJECTIVES

Several studies have shown worse outcomes in patients operated on later in the week. We tested this hypothesis in a large UK national audit database in elective patients undergoing adult cardiac surgery.

METHODS

We used a generalized additive model to evaluate the effect of the day of the week on the following postoperative outcomes: 30-day mortality, stroke, need for dialysis and return to theatre for bleeding. We have adjusted for the relevant European System for Cardiac Operative Risk Evaluation (EuroSCORE) II covariates, plus responsible consultant, hospital and year of operation and performed subgroup analysis for isolated coronary artery bypass grafting (CABG) procedures.

RESULTS

Out of 371 500 patients, 60 555 (16.3%) underwent AVR, 36 553 (9.8%) AVR plus CABG, 238 812 (64.3%) isolated CABG, 26 517 (7.1%) isolated mitral valve repair or replacement and 9063 (2.4%) mitral valve plus CABG. A total of 13 997 (3%) had surgery over the weekend. After covariate adjustment, we found no effect of day of surgery on mortality (P = 0.081), stroke (P = 0.137) and need for postop dialysis (P = 0.732). However, across all operations, there was evidence of a lower rate of return to theatre for bleeding/tamponade at the weekend (P = 0.039). In subgroup analysis of isolated CABG, the day of the week did not affect any outcomes.

CONCLUSIONS

We found no effect of the day of the week on risk-adjusted short-term mortality, stroke, and the requirement for postoperative dialysis after elective cardiac surgery. Overall, the patients operated on during the weekdays were less likely to return to theatre for bleeding. In isolated CABG, the day of the week did not affect any outcomes.

Chronobiology of transient global amnesia

INTRODUCTION

The etiology of transient global amnesia (TGA) is still a matter of debate. Based, among others, on the observation of a close temporal relation between certain events and subsequent TGA episodes, recent proposals discuss the relevance of stress-associated processes impacting on hippocampal functioning. Circadian, infra- and ultradian rhythmicity has been found to play a relevant role in the multifactorial pathomechanisms of various disorders but has not been thoroughly studied in TGA.

METHODS

Data of patients with a final diagnosis of TGA were collected in Mannheim, Germany (06/1999-01/2018, n = 404), and in the Kansai district, Japan (04/2006-03/2018, n = 261). Chronological patterns of TGA occurrence were determined.

RESULTS

Significant circadian rhythmicity of TGA occurrence with bimodal peaks (mid-morning, late afternoon) was found for the entire population (p = 0.002) and for either sub-cohort (Mannheim: p = 0.003, Kansai: p = 0.007). This finding was confirmed for either sex (women: p = 0.004, men: p = 0.004) and different age groups (< 65 years: p = 0.0009, ≥ 65 years: p = 0.003). There was no variation according to day of the week, month or season, but the proportion of patients with a weekday episode was significantly higher in the Mannheim cohort (p = 0.002).

DISCUSSION

We identified a robust circadian rhythm in TGA occurrence which remarkably applied to either of the two study sites located on different continents and which was independent of sex and age. In light of abundant evidence of circadian rhythmicity of both, components of the human stress response system and memory, chronobiological analyses may provide an opportunity to further uncover the mechanisms underlying TGA.

Proteomic and metabolomic profiling of acute and chronic stress events associated with military exercises

By characterizing physiological changes that occur in warfighters during simulated combat, we can start to unravel the key biomolecular components that are linked to physical and cognitive performance. Viable field-based sensors for the warfighter must be rapid and noninvasive. In an effort to facilitate this, we applied a multiomics pipeline to characterize the stress response in the saliva of warfighters to correlate biomolecular changes with overall performance and health. In this study, two different stress models were observed - one of chronic stress and one of acute stress. In both models, significant perturbations in the immune, metabolic, and protein manufacturing/processing systems were observed. However, when differentiating between stress models, specific metabolites associated with the "fight or flight" response and protein folding were seen to be discriminate of the acute stress model.

Endocrine interventions in the intensive care unit

Following the onset of any life-threatening illness that requires intensive medical care, alterations within the neuroendocrine axes occur which are thought to be essential for survival, as they postpone energy-consuming anabolism, activate energy-producing catabolic pathways, and optimize immunological and cardiovascular functions. The hormonal changes present in the acute phase of critical illness at least partially resemble those of the fasting state, and recent evidence suggests that they are part of a beneficial, evolutionary-conserved adaptive stress response. However, a fraction of patients who survive the acute phase of critical illness remain dependent on vital organ support and enter the prolonged phase of critical illness. In these patients, the hypothalamic-pituitary-peripheral axes are functionally suppressed, which may have negative consequences by which recovery may be hampered and the risk of morbidity and mortality in the long-term increased. Most randomized controlled trials of critically ill patients that investigated the impact on the outcome of treatment with peripheral hormones did not reveal a robust morbidity or mortality benefit. In contrast, small studies of patients in the prolonged phase of critical illness documented promising results with the infusion of hypothalamic-releasing hormones. The currently available data corroborate the need for well-designed and adequately powered RCTs to further investigate the impact of these releasing factors on patient-centered outcomes.

Co-culture of monocytes and zona fasciculata adrenal cells: An in vitro model to study the immune-adrenal cross-talk

The hypothalamic-pituitary-adrenal axis is the primary neuroendocrine system activated to re-establish homeostasis during periods of stress, including critical illness and major surgery. During critical illness, evidence suggests that locally induced inflammation of the adrenal gland could facilitate immune-adrenal cross-talk and, in turn, modulate cortisol secretion. It has been hypothesized that immune cells are necessary to mediate the effect of inflammatory stimuli on the steroidogenic pathway that has been observed in vivo. To test this hypothesis, we developed and characterized a trans-well co-culture model of THP1 (human monocytic cell)-derived macrophages and ATC7 murine zona fasciculata adrenocortical cells. We found that co-culture of ATC7 and THP1 cells results in a significant increase in the basal levels of IL-6 mRNA in ATC7 cells, and this effect was potentiated by treatment with LPS. Addition of LPS to co-cultures of ATC7 and THP1 significantly decreased the expression of key adrenal steroidogenic enzymes (including StAR and DAX-1), and this was also found in ATC7 cells treated with pro-inflammatory cytokines. Moreover, 24-h treatment with the synthetic glucocorticoid dexamethasone prevented the effects of LPS stimulation on IL-6, StAR and DAX-1 mRNA in ATC7 cells co-cultured with THP1 cells. Our data suggest that the expression of IL-6 and steroidogenic genes in response to LPS depends on the activation of intra-adrenal immune cells. Moreover, we also show that the effects of LPS can be modulated by glucocorticoids in a time- and dose-dependent manner with potential implications for clinical practice.

The relationship between early post-operative ACTH / cortisol following pituitary surgery and long-term glucocorticoid requirement - Do ultradian rhythms matter?

OBJECTIVE

To determine whether early (4-8h) post-operative ACTH after trans-sphenoidal surgery (TSS) predicts long-term hypothalamic-pituitary-adrenal (HPA) axis function and to investigate early morning day 1 ACTH/cortisol variability using rapid sampling.

DESIGN

Prospective observational study.

METHODS

Participants undergoing TSS were included; those treated with glucocorticoids pre-operatively received 100 mg intravenous hydrocortisone on anaesthetic induction. ACTH and cortisol were measured post-operatively at + 4h and + 8h after induction and on day 1 every 10 minutes between 0700h and 0900h.

PRIMARY OUTCOME

glucocorticoid requirement at 6 months.

RESULTS

Nineteen participants (10F, 9M): 6/19 (32%) were treated with replacement glucocorticoids pre-operatively; 4 had ceased by 6 weeks post-operatively. One patient developed new hypopituitarism post-operatively meaning 3/19 (16%) required glucocorticoids at 6 months. Post-operative + 4h ACTH < 14.3 pmol/L (65 ng/L) predicted secondary adrenal insufficiency (SAI) (sensitivity 100%, specificity 75%), whilst no participant with a post-operative + 4h ACTH ≥ 14.3 pmol/L (65 ng/L) required glucocorticoids at 6 months. Day 1 ACTH and cortisol showed a significant circadian fall between 0700h-0900h; ACTH 4.2 pmol/L (IQR 2.9-5.9) to 3.7 pmol/L (IQR 2.9-5.1) P = .006 and cortisol 549 nmol/L (IQR 337-618) to 439 nmol/L (IQR 315-606) P < .001, with clinically insignificant ultradian secretory pulses.

CONCLUSIONS

No participant with a post-operative + 4h ACTH ≥ 14.3 pmol/L (65 ng/L) required glucocorticoids at 6 months; however, given only 3/19 participants had the primary outcome of interest, this must be confirmed in a larger cohort. The timing of a day 1 morning cortisol between 0700h and 0900h influences the accuracy of a single cut-off to diagnose SAI after pituitary surgery.

Hormonal responsiveness in the Trier Social Stress Test and the dexamethasone-corticotropin releasing hormone test in healthy individuals

A number of different laboratory procedures investigate the hormonal response in a standardized pharmacological challenge test (dexamethasone-corticotropin releasing hormone; DEX-CRH) or in a psychosocial stress induction on the hypothalamic-pituitary-adrenocortical axis by the Trier Social Stress Test (TSST). However, the magnitude of the response related to the different stressors and the interaction of the responsiveness between the two tests is still unclear. Fifty-two participants underwent both the DEX-CRH test and the TSST on two separate days. The cortisol and the plasma adrenocorticotropic hormone (ACTH) release were assessed before and after the stress tests. For a specification of the cortisol response to both conditions, subgroups of high- and low-cortisol responders to the TSST and the DEX-CRH test were formed. The healthy participants showed a substantial increase in the ACTH and the cortisol concentration after the two tests. This increase was 3 times greater in the TSST than the DEX-CRH test. High responders in both tests demonstrated a higher factor of the cortisol reactivity ratio (TSST/DEX-CRH test). Psychosocial stress as induced by the TSST was associated with a significantly greater increase in cortisol compared to the DEX-CRH test, even though the ACTH response displayed no differences. Our findings indicate an interaction of the hormonal responsiveness between the two tests with regard to the cortisol patterns.

Activation and expression of endogenous CREB-regulated transcription coactivators (CRTC) 1, 2 and 3 in the rat adrenal gland

The activation and nuclear translocation of cAMP-response element binding protein (CREB)-regulated transcription coactivator (CRTC)2 occurs in the rat adrenal gland, in response to adrenocorticotrophic hormone (ACTH) and stressors, and has been implicated in the transcriptional regulation of steroidogenic acute regulatory protein (StAR). We have recently demonstrated the activation of CRTC isoforms, CRTC1 and CRTC3, in adrenocortical cell lines. In the present study, we aimed to determine the activation and expression of the three CRTC isoforms in vivo in relation to Star transcription, under basal conditions and following a robust endotoxic stress challenge. Rat adrenal glands and blood plasma were collected following i.v. administration of either an ultradian-sized pulse of ACTH or administration of lipopolysaccharide, as well as under unstressed conditions across the 24-hour period. Plasma ACTH and corticosterone (CORT) were measured and the adrenal glands were processed for measurement of protein by western immunoblotting, RNA by a quantitative reverse transcriptase-polymerase chain reaction and association of CRTC2 and CRTC3 with the Star promoter by chromatin immunoprecipitation. An increase in nuclear localisation of CRTC2 and CRTC3 followed increases in both ultradian and endotoxic stress-induced plasma ACTH, and this was associated with increased CREB phosphorylation and corresponding increases in Star transcription. Both CRTC2 and CRTC3 were shown to associate with the Star promoter, with the dynamics of CRTC3 binding corresponding to that of nuclear changes in protein levels. CRTC isoforms show little variation in ultradian expression or variation across 24 hours, although evidence of long-term down-regulation following endotoxic stress was found. We conclude that co-transcription factors CRTC2 and, more clearly, CRTC3 appear to act alongside phosphorylated CREB in the generation of ultradian pulses of Star transcription, essential for the maintenance of basal StAR expression. Similarly, our findings suggest CRTC2 and CRTC3 mediate Star transcriptional initiation following an endotoxic stressor; however, other transcription factors are likely to be responsible for the long-term up-regulation of adrenal Star transcription.

Emerging roles of melanocortin receptor accessory proteins (MRAP and MRAP2) in physiology and pathophysiology

Melanocortin-2 receptor accessory protein (MRAP) has an unusual dual topology and influences the expression, localisation, signalling and internalisation of the melanocortin receptor 2 (MC₂); the adrenocorticotropic hormone (ACTH) receptor. Mutations in MRAP are associated with familial glucocorticoid deficiency type-2 and evidence is emerging of the importance of MRAP in adrenal development and ACTH signalling. Human MRAP has two functional splice variants: MRAP-α and MRAP-β, unlike MRAP-β, MRAP-α has little expression in brain but is highly expressed in ovary. MRAP2, identified through whole human genome sequence analysis, has approximately 40% sequence homology to MRAP. MRAP2 facilitates MC2 localisation to the cell surface but not ACTH signalling. MRAP and MRAP2 have been found to regulate the surface expression and signalling of all melanocortin receptors (MC_1-5). Additionally, MRAP2 moderates the signalling of the G-protein coupled receptors (GCPRs): orexin, prokineticin and GHSR1a; the ghrelin receptor. Whilst MRAP appears to be mainly involved in glucocorticoid synthesis, an important role is emerging for MRAP2 in regulating appetite and energy homeostasis. Transgenic models indicate the importance of MRAP in adrenal gland formation. Like MC3R and MC4R knockout mice, MRAP2 knockout mice have an obese phenotype. In vitro studies indicate that MRAP2 enhances the MC3 and MC4 response to the agonist αMSH, which, like ACTH, is produced through precursor polypeptide proopiomelanocortin (POMC) cleavage. Analysis of cohorts of individuals with obesity have revealed several MRAP2 genetic variants with loss of function mutations which are causative of monogenic hyperphagic obesity with hyperglycaemia and hypertension. MRAP2 may also be associated with female infertility. This review summarises current knowledge of MRAP and MRAP2, their influence on GPCR signalling, and focusses on pathophysiology, particularly familial glucocorticoid deficiency type-2 and obesity.

An integrated PK-PD model for cortisol and the 17-hydroxyprogesterone and androstenedione biomarkers in children with congenital adrenal hyperplasia

Aims

The aim of this study was to characterize the pharmacokinetic/pharmacodynamic relationships of cortisol and the adrenal biomarkers 17‐hydroxyprogesterone and androstenedione in children with congenital adrenal hyperplasia (CAH).

Methods

A nonlinear mixed‐effect modelling approach was used to analyse cortisol, 17‐hydroxyprogesterone and androstenedione concentrations obtained over 6 hours from children with CAH (n = 50). A circadian rhythm was evident and the model leveraged literature information on circadian rhythm in untreated children with CAH. Indirect response models were applied in which cortisol inhibited the production rate of all three compounds using an I_max model.

Results

Cortisol was characterized by a one‐compartment model with apparent clearance and volume of distribution estimated at 22.9 L/h/70 kg and 41.1 L/70 kg, respectively. The IC₅₀ values of cortisol concentrations for cortisol, 17‐hydroxyprogesterone and androstenedione were estimated to be 1.36, 0.45 and 0.75 μg/dL, respectively. The inhibitory effect was found to be more potent on 17OHP than D4A, and the IC₅₀ values were higher in salt‐wasting subjects than simple virilizers. Production rates of cortisol, 17‐hydroxyprogesterone and androstenedione were higher in simple‐virilizer subjects. Half‐lives of cortisol, 17‐hydroxyprogesterone and androstenedione were 60, 47 and 77 minutes, respectively.

Conclusion

Rapidly changing biomarker responses to cortisol concentrations highlight that single measurements provide volatile information about a child's disease control. Our model closely captured observed cortisol, 17‐hydroxyprogesterone and androstenedione concentrations. It can be used to predict concentrations over 24 hours and allows many novel exposure metrics to be calculated, e.g., AUC, AUC‐above‐threshold, time‐within‐range, etc. Our long‐range goal is to uncover dose–exposure–outcome relationships that clinicians can use in adjusting hydrocortisone dose and timing.

Dynamics of ACTH and Cortisol Secretion and Implications for Disease

The past decade has seen several critical advances in our understanding of hypothalamic-pituitary-adrenal (HPA) axis regulation. Homeostatic physiological circuits need to integrate multiple internal and external stimuli and provide a dynamic output appropriate for the response parameters of their target tissues. The HPA axis is an example of such a homeostatic system. Recent studies have shown that circadian rhythmicity of the major output of this system-the adrenal glucocorticoid hormones corticosterone in rodent and predominately cortisol in man-comprises varying amplitude pulses that exist due to a subhypothalamic pulse generator. Oscillating endogenous glucocorticoid signals interact with regulatory systems within individual parts of the axis including the adrenal gland itself, where a regulatory network can further modify the pulsatile release of hormone. The HPA axis output is in the form of a dynamic oscillating glucocorticoid signal that needs to be decoded at the cellular level. If the pulsatile signal is abolished by the administration of a long-acting synthetic glucocorticoid, the resulting disruption in physiological regulation has the potential to negatively impact many glucocorticoid-dependent bodily systems. Even subtle alterations to the dynamics of the system, during chronic stress or certain disease states, can potentially result in changes in functional output of multiple cells and tissues throughout the body, altering metabolic processes, behavior, affective state, and cognitive function in susceptible individuals. The recent development of a novel chronotherapy, which can deliver both circadian and ultradian patterns, provides great promise for patients on glucocorticoid treatment.

The Peacock study: feasibility of the dynamic characterisation of the paediatric hypothalamic-pituitary-adrenal function during and after cardiac surgery

BACKGROUND

Cortisol is the main stress hormone mobilised during surgery to establish homeostasis. Our current understanding of the hypothalamic-pituitary-adrenal axis physiology in children undergoing cardiopulmonary bypass is very limited due to: (1) very few cortisol time point measurements over long periods (2) difficulties of sampling in low weight babies and (3) the concomitant use of glucocorticoids at anaesthesia induction. This lack of understanding is reflected in a lack of consensus on the utility of glucocorticoids perioperatively in cardiac surgery with the use of cardiopulmonary bypass.

METHODS

The Peacock Study is a prospective, two-centre, observational cohort study of 78 children (undergoing cardiopulmonary bypass procedures and non-surgical procedures - split by age/cyanosis) that aims to characterise in detail the hypothalamic-pituitary-adrenal axis physiology of children using the stress model of paediatric cardiac surgery. Also, we aim to correlate cortisol profiles with clinical outcome data. We herein describe the main study design and report the full cortisol profile of one child undergoing heart surgery, thus proving the feasibility of the method.

RESULTS

We used an automated, 24-h tissue microdialysis system to measure cortisol and cortisone, every 20 min. We herein report one cortisol profile of a child undergoing heart surgery. Besides, we measured serum cortisol and adrenocorticotrophic hormone at seven-time points for correlation. Tissue concentrations of cortisol increased markedly several hours after the end of surgery. We also noted an increase in the tissue cortisol/cortisone ratio during this response.

CONCLUSION

We report for the first time, the use of an automated microdialysis sampling system to evaluate the paediatric adrenal response in children. Changes in cortisol and cortisone could be measured, and the concentration of cortisol in the tissues increased after the end of cardiac surgery. The method has wide application to measure other hormones dynamically and frequently without the limitation of the circulating blood volume. The data from the main study will clarify how these cortisol profiles vary with age, pathology, type of procedure and correlation to clinical outcomes.

TRIAL REGISTRATION

ISCRTN registry, number: 982586.

Dynamic Pituitary-Adrenal Interactions in the Critically Ill after Cardiac Surgery

CONTEXT

Patients with critical illness are thought to be at risk of adrenal insufficiency. There are no models of dynamic hypothalamic-pituitary-adrenal (HPA) axis function in this group of patients and thus current methods of diagnosis are based on aggregated, static models.

OBJECTIVE

To characterize the secretory dynamics of the HPA axis in the critically ill (CI) after cardiac surgery.

DESIGN

Mathematical modeling of cohorts.

SETTING

Cardiac critical care unit.

PATIENTS

20 male patients CI at least 48 hours after cardiac surgery and 19 healthy (H) male volunteers.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Measures of hormone secretory dynamics were generated from serum adrenocorticotrophic hormone (ACTH) sampled every hour and total cortisol every 10 min for 24 h.

RESULTS

All CI patients had pulsatile ACTH and cortisol profiles. CI patients had similar ACTH secretion (1036.4 [737.6] pg/mL/24 h) compared to the H volunteers (1502.3 [1152.2] pg/mL/24 h; P = .20), but increased cortisol secretion (CI: 14 447.0 [5709.3] vs H: 5915.5 [1686.7)] nmol/L/24 h; P < .0001). This increase in cortisol was due to nonpulsatile (CI: 9253.4 [3348.8] vs H: 960 [589.0] nmol/L/24 h, P < .0001), rather than pulsatile cortisol secretion (CI: 5193.1 [3018.5] vs H: 4955.1 [1753.6] nmol/L/24 h; P = .43). Seven (35%) of the 20 CI patients had cortisol pulse nadirs below the current international guideline threshold for critical illness-related corticosteroid insufficiency, but an overall secretion that would not be considered deficient.

CONCLUSIONS

This study supports the premise that current tests of HPA axis function are unhelpful in the diagnosis of adrenal insufficiency in the CI. The reduced ACTH and increase in nonpulsatile cortisol secretion imply that the secretion of cortisol is driven by factors outside the HPA axis in critical illness.

The association of systemic inflammatory markers with indicators of stress and cardiac necrosis in patients undergoing aortic valve replacement and revascularization surgeries

The aim was to investigate: changes of inflammatory, stress and cardiac response in patients undergoing open heart surgeries up to five days after the procedure; the association between inflammatory, stress and cardiac response and whether changes in a certain marker can predict short-term patient outcome. Ninety patients were divided into three groups, 30 participants each (on-pump,off-pump revascularization and valve replacement group). The following markers were measured:complete blood count, CRP, IL-6, IL-10, leptin, resistin, monocyte chemoattractant protein-1 (MCP-1), cortisol, CK and hsTnT in 5 points. Resistin increased in all three groups. Lower IL-10 levels were found after the surgery and higher levels of leptin and MCP-1 in the off-pump than in the on-pump group. Off-pump group had higher values of IL-6, IL-10, leptin, resistin and MCP-1 and lower levels of CK and hsTnT 24 after surgery than the on-pump group. We found significant correlation between MCP-1 and resistin. The difference between resistin at time points 2 and 3 significantly predicted transfusion needs; while the difference between CRP and resistin before and at the end of the surgery together with the difference between leukocytes at the end and 24 hours after the surgery predicted the use of inotropic agents/vasopressors. Cardiac surgeries cause an increase of inflammatory, stress and cardiac markers. Only resistin correlated with MCP-1 which confirms the link between resistin secreted form infiltrated macrophages and enhanced release of MCP-1.

Continuous Free Cortisol Profiles-Circadian Rhythms in Healthy Men

CONTEXT

The pituitary-adrenal axis had historically been considered a representative model for circadian rhythms. A recently developed portable collection device has provided the opportunity to evaluate free cortisol profiles using the microdialysis approach in individuals free to conduct their day-to-day activities in their own surroundings.

METHODS

Two separate experiments were conducted in healthy male volunteers. The total and subcutaneous (SC) free cortisol levels were measured at 10-minute intervals for a 24-hour period in one experiment, and the SC free cortisol levels were measured at 20-minute interval for 72 consecutive hours in free-living individuals in the second experiment.

RESULTS

The characteristic circadian rhythm was evident in both serum total and SC free cortisol, with the lowest levels achieved and maintained in the hours surrounding sleep onset and the peak levels occurring in every individual around waking. In all free-living individuals, the circadian rhythm was consistent across the 72-hour period, despite a wide range of activities. All the participants also showed increased cortisol after the consumption of lunch. The lowest levels during all 24-hour periods were observed during the hours after lights off, at the onset of sleep.

CONCLUSIONS

To the best of our knowledge, the present study is the first to report up to three consecutive 24-hour measurements of SC free cortisol in healthy individuals. We believe our study is a landmark study that paves the way for ambulatory monitoring of free cortisol profiles continuously for a period of 72 hours in free-living individuals performing their day-to-day activities whether healthy or with diseases involving the hypothalamic-pituitary-adrenal axis.

Redefining the perioperative stress response: a narrative review

The systemic stress response triggered by surgical trauma is characterised by sterile inflammation preceding metabolic and neuroendocrine dysregulation. However, the relevance of the classically described 'stress response' is now highly questionable in an era where profound physiological deconditioning is common in older, frail surgical patients. Commonly used assessment techniques do not accurately reflect hypothalamic-pituitary-adrenal axis integrity after major surgery. Clinical interpretation of plasma concentrations of cortisol, the prototypical stress hormone, is rarely accurate, because of study heterogeneity, the inherently dynamic characteristics of cortisol production, and assay variability. Before surgery, chronic psychosocial stress and common cardiorespiratory co-morbidities are clinically relevant modifiers of neuroendocrine activation to acute stress/inflammation. The frequent development of multi-morbidity after major surgery further clouds the compartmentalised, discrete model of neuroendocrine activation after initial tissue injury. Starvation, impaired mobility, and sepsis after surgery generate distinct neuroendocrine profiles that challenge the conventional model of neuroendocrine activation. Basic science studies suggest that high circulating levels of cortisol may directly cause organ injury. Conversely, randomised controlled clinical trials investigating glucocorticoid supplementation have delivered contrasting results, with some suggesting a protective effect in the perioperative period. Here, we consider many of the confounding factors that have emerged to challenge the conventional model of the surgical stress response, and suggest that a more nuanced understanding of changes in hypothalamic-pituitary-adrenal axis physiology is warranted to advance perioperative medicine. Re-examining the perioperative stress response presents opportunities for improving outcomes through enhancing the understanding of the neuroendocrine aspects of preparation for and recovery from surgery.

The human stress response

The human stress response has evolved to maintain homeostasis under conditions of real or perceived stress. This objective is achieved through autoregulatory neural and hormonal systems in close association with central and peripheral clocks. The hypothalamic-pituitary-adrenal axis is a key regulatory pathway in the maintenance of these homeostatic processes. The end product of this pathway - cortisol - is secreted in a pulsatile pattern, with changes in pulse amplitude creating a circadian pattern. During acute stress, cortisol levels rise and pulsatility is maintained. Although the initial rise in cortisol follows a large surge in adrenocorticotropic hormone levels, if long-term inflammatory stress occurs, adrenocorticotropic hormone levels return to near basal levels while cortisol levels remain raised as a result of increased adrenal sensitivity. In chronic stress, hypothalamic activation of the pituitary changes from corticotropin-releasing hormone-dominant to arginine vasopressin-dominant, and cortisol levels remain raised due at least in part to decreased cortisol metabolism. Acute elevations in cortisol levels are beneficial to promoting survival of the fittest as part of the fight-or-flight response. However, chronic exposure to stress results in reversal of the beneficial effects, with long-term cortisol exposure becoming maladaptive, which can lead to a broad range of problems including the metabolic syndrome, obesity, cancer, mental health disorders, cardiovascular disease and increased susceptibility to infections. Neuroimmunoendocrine modulation in disease states and glucocorticoid-based therapeutics are also discussed.

Improving glucocorticoid replacement profiles in adrenal insufficiency

There is an increased mortality associated with adrenal insufficiency despite glucocorticoid replacement therapy with a standardized mortality ratio greater than two. The cause of the increased mortality is yet to be definitively elucidated, but may be due to excess steroid exposure, or replacement regimens that are uncoupled from the normal physiological cortisol profile. Cortisol secretion follows an ultradian pattern which is not possible to reproduce using oral replacement. With the advent of new pumps, it is now possible to mimic the pulsatility of the adrenal glands. While the cognitive and emotional benefits of reproducing the ultradian rhythm are known, the presence of long-term benefits is not yet clear. There is a dearth of evidence and high-quality studies to underline our current understanding of the pathophysiology of adrenal insufficiency and replacement therapy. There is a particular lack of research comparing objective outcomes between patients receiving hydrocortisone replacement (either standard therapy or new sustained release preparations), prednisolone replacement and ultradian pumps. Direct comparative studies are now warranted to understand the optimal approach.

Adrenal function and dysfunction in critically ill patients

Critical illnesses are characterized by increased systemic cortisol availability, which is a vital part of the stress response. Relative adrenal failure (later termed critical-illness-related corticosteroid insufficiency (CIRCI)) is a condition in which the systemic availability of cortisol is assumed to be insufficiently high to face the stress of the illness and is most typically thought to occur in the acute phase of septic shock. Researchers suggested that CIRCI could be diagnosed by a suppressed incremental cortisol response to an injection of adrenocorticotropic hormone, irrespective of the baseline plasma cortisol. This concept triggered several randomized clinical trials on the impact of large stress doses of hydrocortisone to treat CIRCI, which gave conflicting results. Recent novel insights into the response of the hypothalamic-pituitary-adrenal axis to acute and prolonged critical illnesses challenge the concept of CIRCI, as currently defined, as well as the current practice guidelines for diagnosis and treatment. In this Review, these novel insights are integrated within a novel conceptual framework that can be used to re-appreciate adrenocortical function and dysfunction in the context of critical illness. This framework opens new avenues for further research and for preventive and/or therapeutic innovations.

Cortisol Response in Children After Second Cardiopulmonary Bypass

A surge in cortisol levels is seen after surgery with cardiopulmonary bypass (CPB). Based on evidence of attenuation of the cortisol response to repeated stress in other settings, we hypothesized that the magnitude of cortisol increase in children after a second exposure to CPB would be reduced. Serial cortisol levels were measured at three time points after each CPB: immediately (day 0), on the first morning (day 1), and second morning (day 2). Forty-six children underwent two surgeries with CPB during the study period. The mean age (standard deviation) at first and second surgery was 3.5 (6.3) months and 10.4 (9.9) months, respectively. Cortisol levels at the first surgery were 109 (105) µg/dl, 29 (62) µg/dl, and 17 (12) µg/dl on day 0, 1, and 2, respectively; similarly at second surgery, it was 61 (57) µg/dl on day 0 to 20 (16) µg/dl and 11 (10) µg/dl on day 1 and 2, respectively. After log-transformation and adjusting for time interval between surgeries, cortisol levels at the second surgery were lower by 42% on day 0 (p = 0.02), and 46% lower on day 2 (p = 0.02). A second exposure to CPB in children with congenital heart disease is associated with an attenuated cortisol release.

Stability and Turnover of the ACTH Receptor Complex

Glucocorticoid production in mammals is principally regulated by the action of the pituitary hormone adrenocorticotropin (ACTH) acting on its cognate membrane receptor on the zona fasciculata cells of the adrenal cortex. The receptor for ACTH consists of two essential components, a small seven transmembrane domain G protein-coupled receptor of the melanocortin receptor subgroup known as the melanocortin 2 receptor (MC2R) and a small single transmembrane domain protein that adopts a antiparallel homodimeric form and which is known as the melanocortin 2 receptor accessory protein (MRAP). MRAP is essential for the trafficking of the MC2R to the cell surface as well as being required for receptor responsiveness to ACTH at physiological concentrations-probably by facilitating ACTH binding, but possibly also by supporting G protein interaction with the MC2R. A number of studies have shown that ACTH stimulates the expression of functional receptor at the cell surface and the transcription of both MC2R and MRAP mRNA. However, the time course of these transcriptional effects differs such that MRAP is expressed relatively rapidly whereas MC2R transcription responds much more slowly. Furthermore, recent data suggests that MRAP protein is turned over with a short half-life whereas MC2R has a significantly longer half-life. These findings imply that these two ACTH receptor proteins have distinct trajectories and that it is likely that MRAP-independent MC2R is present at the cell surface. In such a situation newly transcribed and translated MRAP could enable the rapid recruitment of functional receptor at the plasma membrane without the need for new MC2R translation. This may be advantageous in circumstances of significant stress in that the potentially complex and perhaps inefficient process of de novo MC2R translation, folding, post-translational modification and trafficking can be avoided.

Genetic variation in the glucocorticoid receptor and psychopathology after dexamethasone administration in cardiac surgery patients

The glucocorticoid receptor (GR) agonist dexamethasone is frequently used for its anti-inflammatory properties. We recently showed that a single high-dose of dexamethasone had long-lasting protective effects on the development of psychopathology after cardiac surgery and postoperative intensive care unit stay. In this study, we investigated whether common genetic variation in the hypothalamic-pituitary-adrenal (HPA)-axis would influence the susceptibility for PTSD and depression after dexamethasone administration. Participants (n = 996) of the Dexamethasone for Cardiac Surgery (DECS) randomized clinical trial were followed after receiving a single high intraoperative dose of dexamethasone (1 mg/kg), a GR agonist, or placebo. PTSD and depressive symptoms were assessed up to four years after cardiac surgery. We focused primarily on five common single nucleotide polymorphisms (SNPs) in the glucocorticoid receptor (GR). Secondarily, we comprehensively assessed common genetic variation in the FK506 binding protein (FKBP5) and the mineralocorticoid receptor (MR). The protective effects of dexamethasone on postoperative PTSD symptoms were dependent on the GR polymorphisms rs41423247 (p = .009), rs10052957 (p = .003), and rs6189 (p = .002), but not on rs6195 (p = .025) or rs6198, (p = .026) after Bonferroni correction. No genotype-dependent effects were found for postoperative depressive symptoms. Also, no associations of FKBP5 and MR polymorphisms were found on PTSD and depression outcomes. Protective effects of dexamethasone on PTSD symptoms after cardiac surgery and ICU stay seem to depend on common genetic variation in its target receptor, the GR. These effects indicate that pre-operative genetic screening could potentially help in stratifying patients for their vulnerability for developing PTSD symptoms after surgery.

High-throughput profiling of the circulating proteome suggests sexually dimorphic corticosteroid signaling following ischemic stroke

Increasing evidence suggests that there are innate differences between sexes with respect to stroke pathophysiology; however, the molecular mechanisms underlying these differences remain unclear. In this investigation, we employed a shotgun approach to broadly profile sex-associated differences in the plasma proteomes of a small group of male ( n = 6) and female ( n = 4) ischemic stroke patients. Peripheral blood was sampled during the acute phase of care, and liquid chromatography electrospray ionization mass spectrometry was used to quantify plasma proteins. We observed widespread differences in plasma composition, as 77 out of 294 detected proteins were significantly differentially expressed between sexes. Corticosteroid-binding globulin (CBG), a negative acute-phase reactant that inversely regulates levels of bioactive free cortisol, was the most dramatically differentially regulated, exhibiting 16-fold higher abundance in plasma from women relative to men. Furthermore, functional annotation analysis revealed that the remaining differentially expressed proteins were significantly enriched for those involved in response to corticosteroid signaling. Plasma CBG levels were further examined in an additional group of male ( n = 19) and female ( n = 28) ischemic stroke patients, as well as a group of male ( n = 13) and female ( n = 18) neurologically normal controls. CBG levels were significantly reduced in male stroke patients relative to male controls; however, no differences were observed between female stroke patients and female controls, suggesting that women may exhibit an attenuated cortisol response to stroke. Collectively, our findings reinforce the idea that there are sex-associated differences in stroke pathophysiology and suggest that cortisol signaling should be investigated further as a potential molecular mediator.

Corticosteroids and Other Anti-Inflammatory Strategies in Pediatric Heart Surgery: A National Survey of Practice

BACKGROUND

The role of steroids to mitigate the deleterious effects of pediatric cardiopulmonary bypass (CPB) remains a matter of debate; therefore, we aimed to assess preferences in administering corticosteroids (CSs) and the use of other anti-inflammatory strategies in pediatric cardiac surgery.

METHODS

A 19-question survey was distributed to consultants in pediatric cardiac anesthesia from 12 centers across the United Kingdom and Ireland.

RESULTS

Of the 37 respondents (37/60, 62%), 24 (65%) use CSs, while 13 (35%) do not use steroids at all. We found variability within 5 (41%) of the 12 centers. Seven consultants (7/24, 29%) administer CSs in every case, while 17 administer CSs in selected cases only (17/24, 71%). There was variability in the dose of steroid administration. Almost all consultants (23/24, 96%) administer a single dose at induction, and one administers a two-dose regimen (1/24, 4%). There was variability in CS indications. Most consultants (24/37, 66%) use modified ultrafiltration at the conclusion of CPB. Fifteen consultants (15/32, 47%) report the use of aprotinin, while only 3 use heparin-coated circuits (3/24, 9%).

CONCLUSIONS

We found wide variability in practice in the administration of CSs for pediatric cardiac surgery, both within and between units. While most anesthetists administer CSs in at least some cases, there is no consensus on the type of steroid, the dose, and at which patient groups this should be directed. Modified ultrafiltration is still used by most of the centers. Almost half of consultants use aprotinin, while heparin-coated circuits are infrequently used.

Involvement of adenosine monophosphate activated kinase in interleukin-6 regulation of steroidogenic acute regulatory protein and cholesterol side chain cleavage enzyme in the bovine zona fasciculata and zona reticularis

In bovine adrenal zona fasciculata (ZF) and NCI-H295R cells, interleukin-6 (IL-6) increases cortisol release, increases expression of steroidogenic acute regulatory protein (StAR), cholesterol side chain cleavage enzyme (P450scc), and steroidogenic factor 1 (SF-1) (increases steroidogenic proteins), and decreases the expression of adrenal hypoplasia congenita-like protein (DAX-1) (inhibits steroidogenic proteins). In contrast, IL-6 decreases bovine adrenal zona reticularis (ZR) androgen release, StAR, P450scc, and SF-1 expression, and increases DAX-1 expression. Adenosine monophosphate (AMP) activated kinase (AMPK) regulates steroidogenesis, but its role in IL-6 regulation of adrenal steroidogenesis is unknown. In the present study, an AMPK activator (AICAR) increased (P < 0.01) NCI-H295R StAR promoter activity, StAR and P450scc expression, and the phosphorylation of AMPK (PAMPK) and acetyl-CoA carboxylase (PACC) (indexes of AMPK activity). In ZR (decreased StAR, P450scc, SF-1, increased DAX-1) (P < 0.01) and ZF tissues (increased StAR, P450scc, SF-1, decreased DAX-1) (P < 0.01), AICAR modified StAR, P450scc, SF-1 and DAX-1 mRNAs/proteins similar to the effects of IL-6. The activity (increased PAMPK and PACC) (P < 0.01) of AMPK in the ZF and ZR was increased by AICAR and IL-6. In support of an AMPK role in IL-6 ZF and ZR effects, the AMPK inhibitor compound C blocked (P < 0.01) the effects of IL-6 on the expression of StAR, P450scc, SF-1, and DAX-1. Therefore, IL-6 modification of the expression of StAR and P450scc in the ZF and ZR may involve activation of AMPK and these changes may be related to changes in the expression of SF-1 and DAX-1.

Corticosteroids in Pediatric Heart Surgery: Myth or Reality

Background: Corticosteroids have been administered prophylactically for more than 60 years in pediatric heart surgery, however, their use remains a matter of debate. There are three main indications for corticosteroid use in pediatric heart surgery with the use of cardiopulmonary bypass (CPB): (1) to blunt the systemic inflammatory response (SIRS) induced by the extracorporeal circuit; (2) to provide perioperative supplementation for presumed relative adrenal insufficiency; (3) for the presumed neuroprotective effect during deep hypothermic circulatory arrest operations. This review discusses the current evidence behind the use of corticosteroids in these three overlapping areas. Materials and Methods: We conducted a structured research of the literature using PubMed and MEDLINE databases to November 2017 and additional articles were identified by cross-referencing. Results: The evidence suggests that there is no correlation between the effect of corticosteroids on inflammation and their effect on clinical outcome. Due to the limitations of the available evidence, it remains unclear if corticosteroids have an impact on early post-operative outcomes or if there are any long-term effects. There is a limited understanding of the hypothalamic-pituitary-adrenal axis function during cardiac surgery in children. The neuroprotective effect of corticosteroids during deep hypothermic circulatory arrest surgery is controversial. Conclusions: The utility of steroid administration for pediatric heart surgery with the use of CPB remains a matter of debate. The effect on early and late outcomes requires clarification with a large multicenter randomized trial. More research into the understanding of the adrenal response to surgery in children and the effect of corticosteroids on brain injury is warranted.

Ultradian rhythmicity of plasma cortisol is necessary for normal emotional and cognitive responses in man

Glucocorticoids (GCs) are secreted in an ultradian, pulsatile pattern that emerges from delays in the feedforward-feedback interaction between the anterior pituitary and adrenal glands. Dynamic oscillations of GCs are critical for normal cognitive and metabolic function in the rat and have been shown to modulate the pattern of GC-sensitive gene expression, modify synaptic activity, and maintain stress responsiveness. In man, current cortisol replacement therapy does not reproduce physiological hormone pulses and is associated with psychopathological symptoms, especially apathy and attenuated motivation in engaging with daily activities. In this work, we tested the hypothesis that the pattern of GC dynamics in the brain is of crucial importance for regulating cognitive and behavioral processes. We provide evidence that exactly the same dose of cortisol administered in different patterns alters the neural processing underlying the response to emotional stimulation, the accuracy in recognition and attentional bias toward/away from emotional faces, the quality of sleep, and the working memory performance of healthy male volunteers. These data indicate that the pattern of the GC rhythm differentially impacts human cognition and behavior under physiological, nonstressful conditions and has major implications for the improvement of cortisol replacement therapy.

A Prospective Cohort Evaluation of the Cortisol Response to Cardiac Surgery with Occurrence of Early Postoperative Cognitive Decline

BACKGROUND A recent study reported that patients with higher cortisol levels on the 1st postoperative morning after cardiac surgery exhibited an increased risk of early postoperative cognitive decline (POCD). Therefore, we conducted the current study to gain further insight into the stress response to a surgical procedure as a potential risk factor for early POCD after cardiac surgery. MATERIAL AND METHODS This prospective cohort study enrolled 125 patients undergoing elective cardiac surgery with or without cardiopulmonary bypass (CPB). Patient serum cortisol levels were determined 1 day before surgery (at 08: 00) and on the 1st (at 08: 00, 16: 00 and 24: 00), 3rd (at 08: 00), and 5th (at 08: 00) postoperative days. A battery of 9 neuropsychological tests were used to assess the participants 2 days before the surgical procedure and on the 6th postoperative day. POCD was defined as a decrease in performance of 1 SD or greater between the postoperative and preoperative z scores on at least 1 neuropsychological test. A mixed-design ANOVA was used to determine the correlations of the perioperative cortisol levels with the occurrence of POCD and with the surgical technique performed. RESULTS Mixed-design ANOVA showed no statistically significant differences in the cortisol levels between non-POCD and POCD patients (F=0.52, P=0.690) or between patients with and without CPB (F=2.02, P=0.103) at the 6 perioperative time points. CONCLUSIONS The occurrence of early POCD and the use of CPB were not associated with significantly higher cortisol levels in the repeated measurement design.

The impact of peri-operative dexamethasone administration on the normal hypothalamic pituitary adrenal response to major surgical procedures

BACKGROUND

Surgical procedures are associated with activation of the hypothalamic-pituitary-adrenal axis (HPA). Studies examining HPA dynamics peri-operatively are limited and the modulating influence of peri-operatively administered glucocorticoids on that is not well established. This investigation examined alterations in HPA function and the impact of dexamethasone (DEX) administration during the peri-operative period.

METHODS

We examined HPA function in 297 patients with normal function who had surgical procedures including pituitary mass resection (n = 191), craniotomy (n = 17) and other thoracic/ abdominal/ pelvic surgeries (n = 89). HPA function was assessed by frequent measurements of parameters defining adrenal function: ACTH, cortisol, DHEA and DHEA-S levels for 48 h. DEX was administered as a single dose (2-10 mg) to 30 and as multiple doses (12-36 mg) to 21 patients. The data of DEX-treated subjects within each group were similar and were combined together.

RESULTS

Pre-operative data were similar for patients having different surgical procedures. Without DEX exposure, ACTH increased to 225 ± 100 ng/L at 2-4 h and gradually declined to baseline values by 36 h while cortisol levels peaked (39.2 ± 13.2 ug/dL) at 6-8 h declining gradually thereafter. Cortisol rise was paralleled by an equimolar increase in DHEA and a subsequent increase in DHEA-S levels. Single doses of DEX did not influence ACTH or cortisol secretion but suppressed the expected rise in DHEA and DHEA-S levels. Multiple doses of DEX suppressed ACTH and cortisol after the 15th postoperative hour and completely blocked the expected rise in DHEA and DHEA-S levels.

CONCLUSIONS

The data provide a detailed overview of HPA function in a large number of subjects who had major surgical procedures. Single and large doses of DEX did not suppress ACTH or cortisol secretion but suppressed adrenal androgen secretion. It took multiple doses of DEX to partially suppress ACTH and cortisol secretion in the peri-operative period.

Dynamic responses of the adrenal steroidogenic regulatory network

The hypothalamic-pituitary-adrenal axis is a dynamic system regulating glucocorticoid hormone synthesis in the adrenal glands. Many key factors within the adrenal steroidogenic pathway have been identified and studied, but little is known about how these factors function collectively as a dynamic network of interacting components. To investigate this, we developed a mathematical model of the adrenal steroidogenic regulatory network that accounts for key regulatory processes occurring at different timescales. We used our model to predict the time evolution of steroidogenesis in response to physiological adrenocorticotropic hormone (ACTH) perturbations, ranging from basal pulses to larger stress-like stimulations (e.g., inflammatory stress). Testing these predictions experimentally in the rat, our results show that the steroidogenic regulatory network architecture is sufficient to respond to both small and large ACTH perturbations, but coupling this regulatory network with the immune pathway is necessary to explain the dissociated dynamics between ACTH and glucocorticoids observed under conditions of inflammatory stress.

Corticosteroids in septic shock: a systematic review and network meta-analysis

Background

Multiple corticosteroids and treatment regimens have been used as adjuncts in the treatment of septic shock. Qualitative and quantitative differences exist at cellular and tissular levels between the different drugs and their patterns of delivery. The objective of this study was to elucidate any differences between the drugs and their treatment regimens regarding outcomes for corticosteroid use in adult patients with septic shock.

Methods

Network meta-analysis of the data used for the recently conducted Cochrane review was performed. Studies that included children and were designed to assess respiratory function in pneumonia and acute respiratory distress syndrome, as well as cross-over studies, were excluded. Network plots were created for each outcome, and all analyses were conducted using a frequentist approach assuming a random-effects model.

Results

Complete data from 22 studies and partial data from 1 study were included. Network meta-analysis provided no clear evidence that any intervention or treatment regimen is better than any other across the spectrum of outcomes. There was strong evidence of differential efficacy in only one area: shock reversal. Hydrocortisone boluses and infusions were more likely than methylprednisolone boluses and placebo to result in shock reversal.

Conclusions

There was no clear evidence that any one corticosteroid drug or treatment regimen is more likely to be effective in reducing mortality or reducing the incidence of gastrointestinal bleeding or superinfection in septic shock. Hydrocortisone delivered as a bolus or as an infusion was more likely than placebo and methylprednisolone to result in shock reversal.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1659-4) contains supplementary material, which is available to authorized users.