Corticosteroid-binding Globulin Deficiency Research Articles

Corticosteroid-Binding Globulin (SERPINA6) Consolidates Sexual Dimorphism of Adult Rat Liver.

Produced by the liver, corticosteroid-binding globulin (CBG) regulates the plasma distribution and actions of glucocorticoids. A sex difference in pituitary growth hormone secretion patterns established during puberty in rats results in increased hepatic CBG production and 2-fold higher plasma corticosterone levels in females. Glucocorticoids control hepatic development and metabolic activities, and we have therefore examined how disrupting the SerpinA6 gene encoding CBG influences plasma corticosterone dynamics, as well as liver gene expression in male and female rats before and after puberty. Comparisons of corticosterone plasma clearance and hepatic uptake in adult rats, with or without CBG, indicated that CBG limits corticosterone clearance by reducing its hepatic uptake. Hepatic transcriptomic profiling revealed minor sex differences (207 differentially expressed genes) and minimal effect of CBG deficiency in 30-day-old rats before puberty. While liver transcriptomes in 60-day-old males lacking CBG remained essentially unchanged, 2710 genes were differentially expressed in wild-type female vs male livers at this age. Importantly, ∼10% of these genes lost their sexually dimorphic expression in adult females lacking CBG, including those related to cholesterol biosynthesis, inflammation, and lipid and amino acid catabolism. Another 203 genes were altered by the loss of CBG specifically in adult females, including those related to xenobiotic metabolism, circadian rhythm, and gluconeogenesis. Our findings reveal that CBG consolidates the sexual dimorphism of the rat liver initiated by sex differences in growth hormone secretion patterns and provide insight into how CBG deficiencies are linked to glucocorticoid-dependent diseases.

ODP584 Corticosteroid-binding Globulin Deficiency Independently Predicts Mortality and is Associated with Norepinephrine Requirements in Septic Shock.

Abstract Context: Hydrocortisone administration in septic shock remains controversial. Corticosteroid-binding globulin (CBG) transports cortisol to inflammatory sites and is depleted in septic shock. Objective To determine if severely deficient plasma CBG <200 nmol/L (Ref range 269-641 nmol/L) independently predicts septic shock mortality. Methods A prospective observational study in patients with septic shock. Patients were categorised into two groups: mean plasma CBG concentrations <200 nmol/L and ≥200 nmol/L (day 1/2), with additional categorisation by nadir CBG. Primary outcome was Intensive Care Unit (ICU) mortality. Secondary outcomes were 28- and 90-day mortality, norepinephrine requirements, renal-replacement therapy, and clinician-instituted hydrocortisone. Results 135 patients were included. Mortality rates in ICU were higher in the CBG <200 nmol/L vs the CBG ≥200 nmol/L group: 32.4% vs 13.9%; Odds ratio (OR), 2.97, (95% confidence intervals (CI) 1.19,7.41); P=0. 02: 28-days; OR 2.25 (95% CI 0.99,5.11): 90-days; OR 2.21 (95% CI 0.99,4.91). Multivariate analysis revealed 4 factors independently associated with ICU mortality: CBG <200 nmol/L (OR 3.23, 95% CI 1. 06,9.88), Acute Physiology and Chronic Health Evaluation (APACHE) II >25 (OR 3.58, 95% CI 1.20,10.68); Sequential [Sepsis-related] Organ Failure Assessment (SOFA) liver score (OR 1.98, 95% CI 1. 04,3.72); and renal-replacement therapy (OR 6.59, 95% CI 2.17,20. 01). Nadir CBG levels were associated with higher SOFA cardiovascular scores, norepinephrine total dose (ug) P<0. 01 and duration (days) P<0. 01. Plasma cortisol concentrations and hydrocortisone administration did not relate to ICU mortality. Conclusion Septic shock patients with CBG <200 nmol/L had higher norepinephrine requirements and 3.2-fold higher ICU mortality. CBG concentration was the only directly reversible independent mortality risk factor. Presentation: No date and time listed

Corticosteroid-Binding Globulin Deficiency Independently Predicts Mortality in Septic Shock.

Hydrocortisone administration in septic shock remains controversial. Corticosteroid-binding globulin (CBG) transports cortisol to inflammatory sites and is depleted in septic shock. To determine whether severely deficient serum CBG < 200 nmol/L (reference range 269-641 nmol/L) independently predicts septic shock mortality. A prospective observational study in patients with septic shock. Patients were categorized into 2 groups: mean plasma CBG concentrations <200 nmol/L and ≥200 nmol/L (day 1/2), with additional categorization by nadir CBG. Primary outcome was intensive care unit (ICU) mortality. Secondary outcomes were 28- and 90-day mortality, norepinephrine requirements, renal replacement therapy, and clinician-instituted hydrocortisone. 135 patients were included. Mortality rates in ICU were higher in the CBG < 200 nmol/L vs the CBG ≥ 200 nmol/L group: 32.4% vs 13.9% [odds ratio (OR) 2.97 (95% CI 1.19, 7.41); P = 0.02] with 28-day mortality OR 2.25 (95% CI 0.99, 5.11) and 90-day mortality OR 2.21 (95% CI 0.99, 4.91). Multivariate analysis revealed 4 factors independently associated with ICU mortality: CBG < 200 nmol/L (adjusted OR 3.23, 95% CI 1.06, 9.88), Acute Physiology and Chronic Health Evaluation II > 25 (adjusted OR 3.58, 95% CI 1.20, 10.68), Sequential Organ Failure Assessment (SOFA) liver score (adjusted OR 1.98, 95% CI 1.04, 3.72), and renal replacement therapy (adjusted OR 6.59, 95% CI 2.17, 20.01). Nadir CBG levels were associated with higher SOFA cardiovascular scores and norepinephrine total dose (μg; P < 0.01) and duration (days; P < 0.01). Plasma cortisol concentrations and hydrocortisone administration did not relate to ICU mortality. Septic shock patients with CBG < 200 nmol/L had higher norepinephrine requirements and 3.2-fold higher ICU mortality. CBG concentration was the only directly reversible independent mortality risk factor.

Corticosteroid-binding-globulin (CBG)-deficient mice show high pY216-GSK3β and phosphorylated-Tau levels in the hippocampus.

Corticosteroid-binding globulin (CBG) is the specific carrier of circulating glucocorticoids, but evidence suggests that it also plays an active role in modulating tissue glucocorticoid activity. CBG polymorphisms affecting its expression or affinity for glucocorticoids are associated with chronic pain, chronic fatigue, headaches, depression, hypotension, and obesity with an altered hypothalamic pituitary adrenal axis. CBG has been localized in hippocampus of humans and rodents, a brain area where glucocorticoids have an important regulatory role. However, the specific CBG function in the hippocampus is yet to be established. The aim of this study was to investigate the effect of the absence of CBG on hippocampal glucocorticoid levels and determine whether pathways regulated by glucocorticoids would be altered. We used cbg-/- mice, which display low total-corticosterone and high free-corticosterone blood levels at the nadir of corticosterone secretion (morning) and at rest to evaluate the hippocampus for total- and free-corticosterone levels; 11β-hydroxysteroid dehydrogenase expression and activity; the expression of key proteins involved in glucocorticoid activity and insulin signaling; microtubule-associated protein tau phosphorylation, and neuronal and synaptic function markers. Our results revealed that at the nadir of corticosterone secretion in the resting state the cbg-/- mouse hippocampus exhibited slightly elevated levels of free-corticosterone, diminished FK506 binding protein 5 expression, increased corticosterone downstream effectors and altered MAPK and PI3K pathway with increased pY216-GSK3β and phosphorylated tau. Taken together, these results indicate that CBG deficiency triggers metabolic imbalance which could lead to damage and long-term neurological pathologies.

Corticosteroid-Binding Globulin is expressed in the adrenal gland and its absence impairs corticosterone synthesis and secretion in a sex-dependent manner

Corticosteroid-binding globulin (CBG) is synthesized by the liver and secreted into the bloodstream where binds to glucocorticoids. Thus CBG has the role of glucocorticoid transport and free hormone control. In addition, CBG has been detected in some extrahepatic tissues without a known role. CBG-deficient mice show decreased total corticosterone levels with missing of classical sexual dimorphism, increased free corticosterone, higher adrenal gland size and altered HPA axis response to stress. Our aim was to ascertain whether CBG deficiency could affect the endocrine synthetic activity of adrenal gland and if the adrenal gland produces CBG. We determined the expression in adrenal gland of proteins involved in the cholesterol uptake and its transport to mitochondria and the main enzymes involved in the corticosterone, aldosterone and catecholamine synthesis. The results showed that CBG is synthesized in the adrenal gland. CBG-deficiency reduced the expression of ACTH receptor, SRB1 and the main genes involved in the adrenal hormones synthesis, stronger in females resulting in the loss of sexual dimorphism in corticosteroid adrenal synthesis, despite corticosterone content in adrenal glands from CBG-deficient females was similar to wildtype ones. In conclusion, these results point to an unexplored and relevant role of CBG in the adrenal gland functionality related to corticosterone production and release.

Altered lipid partitioning and glucocorticoid availability in CBG-deficient male mice with diet-induced obesity.

To evaluate how deficiency in corticosteroid-binding globulin (CBG), the specific carrier of glucocorticoids, affects glucocorticoid availability and adipose tissue in obesity. C57BL/6 (WT) and CBG-deficient (KO) male mice were fed during 12 weeks with standard or hyperlipidic diet (HL). Glucocorticoid availability and metabolic parameters were assessed. Body weight and food intake were increased in KO compared with WT mice fed a standard diet and were similar when fed a HL diet. Expression of CBG was found in white adipose tissue by immunochemistry, real-time PCR, and Western blot. In obesity, the subcutaneous depot developed less in KO mice compared with WT, which was associated with a minor adipocyte area and peroxisome proliferator-activated receptor-γ expression. Conversely, the epididymal depot displayed higher weight and adipocyte area in KO than in WT mice. CBG deficiency caused a fall of hepatic 11β-hydroxysteroid dehydrogenase type 2 expression and an increase in epidymal adipose tissue, particularly in HL mice. Deficiency in CBG drives lipid partitioning from subcutaneous to visceral adipose depot under a context of lipid excess and differentially modulates 11β-hydroxysteroid dehydrogenase type 2 expression.

Chronic stress does not further exacerbate the abnormal psychoneuroendocrine phenotype of Cbg-deficient male mice

Chronic stress leads to a dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis which can constitute a base for pathophysiological consequences. Using mice totally deficient in Corticosteroid binding globulin (CBG), we have previously demonstrated the important role of CBG in eliciting an adequate response to an acute stressor. Here, we have studied its role in chronic stress situations. We have submitted Cbg ko and wild-type (WT) male mice to two different chronic stress paradigms – the unpredictable chronic mild stress and the social defeat. Then, their impact on neuroendocrine function – through corticosterone and CBG measurement – and behavioral responses – via anxiety and despair-like behavioral tests – was evaluated. Both chronic stress paradigms increased the display of despair-like behavior in WT mice, while that from Cbg ko mice – which was already high – was not aggravated. We have also found that control and defeated (stressed) Cbg ko mice show no difference in the social interaction test, while defeated WT mice reduce their interaction time when compared to unstressed WT mice. Interestingly, the same pattern was observed for corticosterone levels, where both chronic stress paradigms lowered the corticosterone levels of WT mice, while those from Cbg ko mice remained low and unaltered. Plasma CBG binding capacity remained unaltered in WT mice regardless of the stress paradigm. Through the use of the Cbg ko mice, which only differs genetically from WT mice by the absence of CBG, we demonstrated that CBG is crucial in modulating the effects of stress on plasma corticosterone levels and consequently on behavior. In conclusion, individuals with CBG deficiency, whether genetically or environmentally-induced, are vulnerable to acute stress but do not have their abnormal psychoneuroendocrine phenotype further affected by chronic stress.

Impact of Corticosteroid-Binding Globulin Deficiency on Pregnancy and Neonatal Sex

Plasma corticosteroid-binding globulin (CBG) transports cortisol but high progesterone levels at the maternal-fetal interface can displace cortisol from its steroid-binding site. A secretion-deficient CBG mutant (A51V) in ∼1 of 36 Chinese causes low circulating CBG levels. Assess the implications of a CBG deficiency on pregnancy outcomes. From 1978 Chinese women screened at 12-16 weeks' gestation, 50 A51V carriers were identified and 46 were followed with 60 controls throughout pregnancy. Blood samples from another 2051 pregnant women were obtained at term to determine the secondary sex ratio (SSR) of newborns in an extended cohort (n = 101) of A51V mothers. Among women recruited at 12-16 weeks' gestation, serum CBG increased progressively during pregnancy but was lower (P < .0001) in heterozygous A51V carriers than controls. Two women homozygous for A51V had very low serum CBG but their pregnancies progressed normally. The A51V mothers did not differ from controls in body mass index, gestational age at delivery, duration of parturition, blood pressure, gravidity, infant birth weight and size, or placental weights, and reported no unusual clinical symptoms. Peripheral CBG and progesterone levels correlated (r = 0.459) during first and second trimesters. Progesterone levels were much higher in intervillous blood and correlated (r = 0.637) with CBG levels. A female-skewed SSR in newborns of A51V mothers (0.77) differed (P < .05) from the SSR (1.17) in a reference cohort. CBG influences progesterone levels in peripheral blood and at the maternal-fetal interface. The female-skewed SSR suggests that male fetal survival is compromised in CBG-deficient mothers.

Critical Role of Plasma Corticosteroid-Binding-Globulin During Stress to Promote Glucocorticoid Delivery to the Brain: Impact on Memory Retrieval

We aimed at demonstrating that corticosteroid binding globulin (CBG), a plasma glycoprotein binding glucocorticoids with high affinity in blood, endorses a major role under stress conditions by regulating free glucocorticoid access to the brain and thereby influences glucocorticoid-dependent behaviors. Hence, we compared CBG-deficient mice (Cbg-/-) and their controls (Cbg+/+) in a specific memory task, i.e. the delayed alternation behavior, requiring memory retrieval both under stress and nonstress conditions and previously shown to be dependent on hippocampal glucocorticoid levels. Our results evidence that Cbg-/- mice, unlike controls, remain insensitive to stress applied before memory retrieval. Furthermore, under stress conditions, we observed a blunted surge of corticosterone (CORT) in plasma and no free CORT rise in the hippocampus of Cbg-/-. Moreover, intrahippocampal infusion of CORT through implanted cannulae was used to mimic stress CORT rise before memory retrieval. This infusion of CORT reproduced memory retrieval impairments in Cbg-/- as in Cbg+/+ controls. Finally, we provide evidence that Cbg-/- mice exhibit a normal adrenal response to stress and ACTH. Given that CBG deficiency is known to markedly impact on CORT clearance from plasma, our current article demonstrates that Cbg-/- insensitivity in memory retrieval after stress results from the blunted CORT response due to increased CORT clearance. Overall, our data suggest that the impact of CBG genetic deficiency on various behavioral patterns reported previously stems from a smaller CORT reservoir in blood. Inasmuch as CBG discloses interindividual variations, such a parameter ought to be taken into account when studying stress-induced glucocorticoid action in brain.

Novel Corticosteroid-Binding Globulin Variant That Lacks Steroid Binding Activity

Abstract Background: Corticosteroid-binding globulin (CBG) is the principal carrier for glucocorticoids in the circulation and a regulator of their bioavailability. Inherited CBG deficiencies are rarely reported, and only three causative mutations in four families have been described. Patients, Methods, and Results: In a 26-yr-old female with hypotension, fatigue, and undetectable serum cortisol at presentation, we have identified a novel homozygous c.776g&amp;gt;t transversion in exon 3 of the CBG (SERPINA6) gene. This results in a p.Gly237Val substitution that is predicted to influence the positioning of two β-sheets that constitute part of the CBG steroid-binding site. Two siblings were also homozygous for the variant, whereas her mother and an unaffected sibling were heterozygous. No other symptomatic family members were identified apart from the proband. Individuals homozygous for the variant had serum CBG levels below the reference range when measured by RIA, but CBG was unmeasurable in cortisol-binding capacity assays. In the same individuals, we observed very low baseline and stimulated serum cortisol levels but normal free serum and salivary cortisol and plasma ACTH. In a study of ultradian cortisol pulsatility, increased pulse frequency was only observed in the proband. Conclusion: We describe a novel CBG variant that lacks steroid binding. All mutant homozygotes have very low serum cortisol, but normal free cortisol levels. The only biochemical feature to distinguish the symptomatic subject was increased cortisol pulsatility, and we suggest that this may influence glucocorticoid signaling and contribute to symptoms previously associated with CBG deficiency.

Novel Corticosteroid-Binding Globulin Variant That Lacks Steroid Binding Activity

Corticosteroid-binding globulin (CBG) is the principal carrier for glucocorticoids in the circulation and a regulator of their bioavailability. Inherited CBG deficiencies are rarely reported, and only three causative mutations in four families have been described. In a 26-yr-old female with hypotension, fatigue, and undetectable total serum cortisol at presentation, we have identified a novel homozygous c.776g>t transversion in exon 3 of the CBG (SERPINA6) gene. This results in a p.Gly237Val substitution that is predicted to influence the positioning of two β-sheets that constitute part of the CBG steroid-binding site. Two siblings were also homozygous for the variant, whereas her mother and an unaffected sibling were heterozygous. No other symptomatic family members were identified apart from the proband. Individuals homozygous for the variant had serum CBG levels below the reference range when measured by RIA, but CBG was unmeasurable in cortisol-binding capacity assays. In the same individuals, we observed very low baseline and stimulated total serum cortisol levels but normal free serum and salivary cortisol and plasma ACTH. In a study of ultradian cortisol pulsatility, increased pulse frequency was only observed in the proband. We describe a novel CBG variant that lacks steroid binding activity. All mutant homozygotes have very low total serum cortisol, but normal free serum cortisol levels. The only biochemical feature to distinguish the symptomatic subject was increased cortisol pulsatility, and we suggest that this may influence glucocorticoid signaling and contribute to symptoms previously associated with CBG deficiency.

Haploinsufficiency of the SERPINA6 gene is associated with severe muscle fatigue: A de novo mutation in corticosteroid-binding globulin deficiency

Corticosteroid-binding globulin (SERPINA6) deficiency is an extremely rare hereditary disorder characterized by reduced corticosteroid-binding capacity with normal or low plasma corticosteroid-binding globulin concentration, and normal or low basal cortisol levels associated with hypo-/hypertension and muscle fatigue. Here, we present a patient with severe muscle fatigue, normal blood pressure, and abnormal high saliva cortisol levels following a standardized stress test. This patient was found heterozygous for a de novo 367 asparagine-encoding variant of the corticosteroid-binding globulin gene, previously described as "transcortin Lyon". Both parents were homozygous for the ("wildtype") 367 aspartate-encoding allele. To the best of our knowledge, this case represents the first de novo mutation reported for corticosteroid-binding globulin deficiency, implicating a pathogenic role of variants of SERPINA6 in some cases of muscle fatigue.

Plasma free cortisol fraction reflects levels of functioning corticosteroid-binding globulin

Background In normal plasma free cortisol accounts for less than 6% of the total with 80–90% bound to corticosteroid-binding globulin (CBG) and the remainder associated albumin. However little is known about the distribution of free cortisol in plasma where CBG is inactivated or in congenital CBG deficiency. Methods and results Here we describe ligand binding experiments revealing that while free cortisol in unstressed individuals is less than 6% of total cortisol this rises markedly to 25% when CBG is totally inactivated by heat. Similar elevations of the free cortisol fraction were noted in a patient with a rare genetically determined complete lack of CBG (mean 32% on frequent circadian sampling). Following heat inactivation of CBG or in the congenital absence of CBG, there is a shift in cortisol binding from CBG to albumin. That this shift occurs is further supported by experiments adding [ 3H]-cortisol to physiological human serum albumin solutions, where 25% of cortisol remained in the free fraction. Conclusion Taken together the data provide strong evidence that when CBG is inactivated or congenitally absent then more than 25% of the total cortisol appears in the free fraction with the remainder associated with albumin. The proportion of free cortisol measured in plasma thus reflects a simple measure of functional corticosteroid-binding globulin.

Greater replication and differentiation of preadipocytes in inherited corticosteroid-binding globulin deficiency.

Glucocorticoids are pivotal for adipose tissue development. Rodent studies suggest that corticosteroid-binding globulin (CBG) modulates glucocorticoid action in adipose tissue. In humans, both genetic CBG deficiency and suppressed CBG concentrations in hyperinsulinemic states are associated with obesity. We hypothesized that CBG deficiency in humans modulates the response of human preadipocytes to glucocorticoids, predisposing them to obesity. We compared normal preadipocytes with subcultured preadipocytes from an individual with the first ever described complete deficiency of CBG due to a homozygous null mutation. CBG-negative preadipocytes proliferated more rapidly and showed greater peroxisome proliferator-activated receptor-gamma-mediated differentiation than normal preadipocytes. CBG was not expressed in normal human preadipocytes. Glucocorticoid receptor number and binding characteristics and 11beta-hydroxysteroid dehydrogenase activity were similar for CBG-negative and normal preadipocytes. We propose that the increased proliferation and enhanced differentiation of CBG-negative preadipocytes may promote adipose tissue deposition and explain the obesity seen in individuals with genetic CBG deficiency. Furthermore, these observations may be relevant to obesity occurring with suppressed CBG concentrations associated with hyperinsulinemia.

Familial Corticosteroid-Binding Globulin Deficiency Due to a Novel Null Mutation: Association with Fatigue and Relative Hypotension

Familial Corticosteroid-Binding Globulin Deficiency Due to a Novel Null Mutation: Association with Fatigue and Relative Hypotension

A case of cyclical Cushing's disease associated with corticosteroidbinding globulin deficiency: a rare pitfall in the diagnosis of Cushing's disease

We experienced an extremely unusual combination of Cushing's disease and corticosteroid-binding globulin (CBG) deficiency that has been reported in only one similar case to date. A 53-year-old woman presented at a medical clinic with clinical Cushing's disease. However, her plasma levels of adrenocorticotropin (ACTH) and cortisol were in the normal range. Six months later, during a second visit, a high urinary excretion of 17-hydroxycorticosteroids was found, but plasma ACTH and cortisol levels were normal again. Further investigation revealed a decreased CBG concentration. Free plasma cortisol levels were clearly elevated. Furthermore, the Cushing's disease of our patient was complicated by periodic secretion of ACTH and cortisol, with high or normal outputs of corticosteroids occurring alternately every 1-3 days, which explained the occasionally normal plasma ACTH and cortisol levels. A combination of a decreased serum CBG concentration and periodic secretion of ACTH can be an important pitfall in the diagnosis of Cushing's disease.

Vitamin B-12 (cobalamin) deficiency: a heretofore undescribed control mechanism for plasma corticosteroid-binding globulin concentration in man.

Six of eight patients with Addisonian pernicious anemia were found to have diminished corticosteroid-binding globulin (CBG) concentrations, which returned within 2 weeks to normal after the im administration of cobalamin. T4-binding globulin was found to be completely normal before and after cobalamin replacement. Other estrogen-responsive proteins, i.e. ceruloplasmin, alpha 1-trypsin inhibitor, haptoglobin, transferrin, and alpha 2-macroglobulin, also did not follow CBG concentration in a parallel fashion. The immunoglobulins similarly did not follow a course parallel to that of CBG. The CBG concentration in two untreated patients had a normal increase in response to estrogen administration, similar to that described in CBG deficiency from other causes. No clue was found regarding the mechanism by which B12 influences the putative hepatic control of CBG concentration. It is speculated that at least two control points may be necessary for a normal CBG concentration. Patients with a genetic deficiency of CBG may also have to have cobalamin deficiency in order for them to reach a concentration approaching zero.