Depletion of rat liver glucocorticoid receptor hormone-binding and its mRNA in sepsis

The Hepatic Glucocorticoid Receptor Is Crucial for Cortisol Homeostasis and Sepsis Survival in Humans and Male Mice

Sepsis is hallmarked by hypercortisolemia, a stress response essential for survival. This elevation in plasma cortisol is partially brought about by suppressed hepatic cortisol breakdown. We demonstrate that a controlled downregulation of the hepatic glucocorticoid receptor (hepatic GR) is crucial. In a mouse model of fluid-resuscitated, antibiotic-treated abdominal sepsis and in human intensive care unit patients, sepsis reduced hepatic GR expression and signaling but increased (free) plasma cortisol/corticosterone, explained by suppressed cortisol/corticosterone-binding proteins and A-ring reductases. However, further experimental inhibition of hepatic GR with short hairpin RNA (shRNA) in septic mice increased mortality fivefold. Acutely, this further hepatic GR suppression prevented the rise in total corticosterone but further reduced binding proteins, resulting in elevated free corticosterone. After 3 days of shRNA-GR inhibition in sepsis, both total and free corticosterone levels were elevated, now explained by an additional reduction in A-ring reductase expression. Hepatic GR inhibition blunted the hyperglycemic stress response without causing hypoglycemia but also markedly increased circulating and hepatic inflammation markers and caused liver destruction, the severity of which explained increased mortality. In human sepsis, glucocorticoid treatment further suppressed hepatic GR expression, which could directly predispose to worse outcomes. In conclusion, sepsis partially suppressed hepatic GR expression, which appeared crucial to upregulate free cortisol/corticosterone availability. However, further sustained hepatic GR suppression evoked lethal excessive liver and systemic inflammation, independent of systemic cortisol/corticosterone availability.

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.

TNF-alpha and glucocorticoid receptor interaction in L6 muscle cells: a cooperative downregulation of myosin heavy chain

Sepsis is associated with increased expression of TNF-alpha with subsequent activation of nuclear factor-kappa B (NF-kappaB). The glucocorticoid receptor (GR) and NF-kappaB function as mutual antagonists and induction of the latter is believed to play a major role in the acquired glucocorticoid resistance that occurs in some septic patients. GR expression and function has been reported to be elevated in septic muscle suggesting a limited effect of the activated NF-kappaB on GR function in this context. In this study, the L6 myocyte cell line was used as an in vitro model for a sepsis-like condition in skeletal muscle. While short or long term treatment with TNF-alpha had no effect on GR expression, glucocorticoid-dependent downregulation of GR occurred with a kinetic profile that is accelerated relative to that observed in most cells. This downregulation was not affected by co-treatment or prior priming of L6 cells with TNF-alpha. The synthetic glucocorticoid, dexamethasone (DEX) blunted TNF-alpha-stimulated NF-kappaB activation in L6 cells. However, although effective at activating an NF-kappaB transcriptional response, TNF-alpha treatment exerted a minimal effect in myoblasts and no effect in myotubes on GR transcriptional activity. This limited impact of TNF-alpha on GR activity was not universal as TNF-alpha and DEX exerted an additive effect on the reduction in myosin heavy chain (MHC) protein expression caused by either agent alone. Thus, the selective perseverance of GR function in the presence of increased levels of glucocorticoids and TNF-alpha during sepsis or other inflammatory states may exacerbate muscle protein breakdown.

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.

Role of glucocorticoids and glucocorticoid receptor in priming of macrophages caused by glucocorticoid receptor blockade

We previously reported that glucocorticoid receptor (GR) blockade (injected with GR antagonist RU486) primed the host responses to lipopolysaccharide. Since decrease of GR and elevated glucocorticoids (GCs) have been always reported as parallel responses, we hypothesize that both GCs and GR play important roles in GR blockade induced priming. We first confirm that the production of nitric oxide (NO), superoxide (O2-), and PKCalpha expression are all increased in peritoneal macrophages from GR blockade rats, indicating that macrophages are primed by GR blockade. Furthermore, using unilateral adrenalectomy rats, we find that the elevated GCs caused by a feedback mechanism following GR blockade may be involved in the process of priming. In vitro experiments in RAW264.7 cells show the inhibitory effect of GCs on NO production, which can be thoroughly blocked by RU486, indicating the increase of NO production in GR blockade rats is due to the elimination of GCs's anti-inflammatory function. In contrast, 10(-7) M corticosterone induces significant increases in O2- release, PKCalpha expression and phosphorylation, which cannot be reversed by RU486, demonstrating a previously unrecognized pro-inflammatory role of GCs in enhancing PM activation through a GR-independent pathway. The effect of GCs on PKCalpha expression even exists in GR deficient COS-7 cells as well as in GR knock-down RAW264.7 cells. In conclusion, both GR impairment and elevation of GCs are involved in the priming of macrophages caused by GR blockade. The findings of the divergent roles of GCs in modulation of inflammation may change therapeutic strategy for inflammatory diseases with GCs.

The hepatoadrenal syndrome: a common yet unrecognized clinical condition

OBJECTIVE

Adrenal failure is common in critically ill patients, particularly those with sepsis. As liver failure and sepsis are both associated with increased circulating levels of endotoxin and proinflammatory mediators and reduced levels of apoprotein-1/high-density lipoprotein, we postulated that adrenal failure may be common in patients with liver disease.

DESIGN

Clinical study.

SETTING

Liver transplant intensive care unit.

PATIENTS

The study cohort included 340 patients with liver disease.

INTERVENTIONS

Based on preliminary observational data, all patients admitted to our 28-bed liver transplant intensive care unit (LTICU) undergo adrenal function testing. An honest broker system was used to extract clinical, hemodynamic, medication, and laboratory data on patients admitted to the LTICU from March 2002 to March 2004. A random (stress) cortisol level <20 microg/dL in a highly stressed patient (respiratory failure, hypotension) was used to diagnose adrenal insufficiency. In all other patients, a random cortisol level <15 microg/dL or a 30-min level <20 microg/dL post-low-dose (1 microg) cosyntropin was considered diagnostic of adrenal insufficiency. Patients were grouped as follows: a) chronic liver failure; b) fulminant hepatic failure; c) patients immediately status post-orthotopic liver transplantation receiving a steroid-free protocol of immunosuppression; and d) patients status post-remote liver transplant (>/=6 months). The decision to treat patients with stress doses of hydrocortisone was at the discretion of the treating intensivist and transplant surgeon.

MEASUREMENTS AND MAIN RESULTS

Two-hundred and forty-five (72%) patients met our criteria for adrenal insufficiency (the hepatoadrenal syndrome). Eight (33%) patients with fulminant hepatic failure, 97 (66%) patients with chronic liver disease, 31(61%) patients with a remote history of liver transplantation, and 109 (92%) patients who had undergone liver transplantation under steroid-free immunosuppression were diagnosed with adrenal insufficiency. The high-density lipoprotein level at the time of adrenal testing was the only variable predictive of adrenal insufficiency (p < .0001). In vasopressor-dependent patients with adrenal insufficiency, treatment with hydrocortisone was associated with a significant reduction (p = .02) in the dose of norepinephrine at 24 hrs, whereas the dose of norepinephrine was significantly higher (p = .04) in those patients with adrenal failure not treated with hydrocortisone. In vasopressor-dependent patients without adrenal insufficiency, treatment with hydrocortisone did not affect vasopressor dose at 24 hrs. One hundred and forty-one patients (26.4%) died during their hospitalization. The baseline serum cortisol was 18.8 +/- 16.2 microg/dL in the nonsurvivors compared with 13.0 +/- 11.8 microg/dL in the survivors (p < .001). Of those patients with adrenal failure who were treated with glucocorticoids, the mortality rate was 26% compared with 46% (p = .002) in those who were not treated. In those patients receiving vasopressor agents at the time of adrenal testing, the baseline cortisol was 10.0 +/- 4.8 microg/dL in those with adrenal insufficiency compared with 35.6 +/- 21.2 microg/dL in those with normal adrenal function. Vasopressor-dependent patients who did not have adrenal failure had a mortality rate of 75%.

CONCLUSIONS

Patients with liver failure and patients post-liver transplantation have an exceedingly high incidence of adrenal failure, which may be pathophysiologically related to low levels of high-density lipoprotein. Treatment of patients with adrenal failure may improve outcome. High baseline serum cortisol levels may be a maker of disease severity and portend a poor prognosis.

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.

Expression and binding activity of the glucocorticoid receptor are upregulated in septic muscle

We examined the influence of sepsis, induced by cecal ligation and puncture in rats, on the protein and gene expression and hormone binding activity of the glucocorticoid receptor (GR) in skeletal muscle. Sepsis resulted in increased GR mRNA and protein levels and upregulated hormone binding activity in extensor digitorum longus and soleus muscles. Scatchard analysis suggested that the increased GR hormone binding activity reflected an increased number of hormone binding sites, whereas receptor affinity for glucocorticoids was unchanged. The GR antagonist RU-38486 blocked the sepsis-induced increase in GR expression and hormone binding activity, implicating a positive regulatory effect of glucocorticoids on GR expression and binding activity under the present experimental conditions. The results suggest that glucocorticoid-dependent metabolic changes in skeletal muscle during sepsis may reflect not only high circulating glucocorticoid levels but increased amounts and hormone binding activity of the GR as well.

Temperature-induced down-regulation of the glucocorticoid receptor in peripheral blood mononuclear leucocyte in patients with sepsis or septic shock

OBJECTIVE

Activation of the hypothalamic-pituitary-adrenal axis is of vital importance during critical illness. We have studied the adaptive mechanisms which occur at the level of the glucocorticoid receptor in glucocorticoid target tissues in patients with sepsis or septic shock.

DESIGN

The effects of hypercortisolaemia, hyperthermia and cellular composition on number of glucocorticoid receptors per cell and their affinity were evaluated, both in vitro and in vivo, in peripheral blood mononuclear leucocytes of control subjects and in patients with sepsis or septic shock.

SUBJECTS

Fifteen patients (age 25-79) with sepsis or septic shock who were admitted to an intensive care unit were studied. The control group consisted of 24 healthy laboratory employees.

MEASUREMENTS

The binding capacity and affinity of the glucocorticoid receptors were measured and compared to clinical data and the plasma cortisol concentrations.

RESULTS

Hypercortisolaemia, in vitro, resulted in a decreased affinity and a decreased binding capacity of the glucocorticoid receptor. In vitro, hyperthermia as well as variations in the cellular composition did not influence the glucocorticoid receptor. In vivo, there was no change in the number of receptors per cell in patients with sepsis or septic shock as compared to healthy controls. However, a decreased affinity of the glucocorticoid receptor was observed. There was a weak but significant negative correlation between body temperature and the number of glucocorticoid receptors in the patient group. There was no relation between circulating cortisol concentrations and glucocorticoid receptor affinity and number.

CONCLUSIONS

There is no obvious regulation of the number of glucocorticoid receptors by plasma cortisol concentrations in vivo. The decreased affinity of the glucocorticoid receptor together with the negative correlation between hyperthermia and the number of glucocorticoid receptors in patients with sepsis or septic shock suggest that hypothalamic-pituitary-adrenal axis activation during critical illness is accompanied by peripheral adaptation in glucocorticoid receptor number and affinity.

Glucocorticoid receptors in mononuclear cells of patients with sepsis

Glucocorticoid receptor (GR) hormone-binding activity was studied by a whole-cell method in mononuclear cells (MNC) from peripheral blood of 7 patients during the hemodynamic compensatory phase of sepsis. 4 patients were receiving dopamine, which did not affect the GR count. The patients' plasma cortisol concentrations were normal or slightly elevated. Despite a wide range, the mean GR count and affinity in MNC from septic patients did not differ from those in normal controls, suggesting that glucocorticoids could still be effective in the hemodynamic compensatory phase of sepsis.