Cortisol, Stress, and Disease-Bidirectional Associations; Role for Corticosteroid-Binding Globulin?

Selye described stress as a unified neurohormonal mechanism maintaining homeostasis. Acute stress system activation is adaptive through neurocognitive, catecholaminergic, and immunomodulation mechanisms, followed by a reset via cortisol. Stress system components, the sympathoadrenomedullary system, hypothalamic-pituitary-adrenal axis, and limbic structures are implicated in many chronic diseases by establishing an altered homeostatic state, allostasis. Consequent "primary stress system disorders" were popularly accepted, with phenotypes based on conditions such as Cushing syndrome, pheochromocytoma, and adrenal insufficiency. Cardiometabolic and major depressive disorders are candidates for hypercortisolemic etiology, contrasting the "hypocortisolemic symptom triad" of stress sensitivity, chronic fatigue, and pain. However, acceptance of chronic stress etiology requires cause-and-effect associations, and practical utility such as therapeutics altering stress system function. Inherent predispositions to stress system perturbations may be relevant. Glucocorticoid receptor (GR) variants have been associated with metabolic/neuropsychological states. The SERPINA6 gene encoding corticosteroid-binding globulin (CBG), was the sole genetic factor in a single-nucleotide variation-genome-wide association study linkage study of morning plasma cortisol, a risk factor for cardiovascular disease, with alterations in tissue-specific GR-related gene expression. Studies showed genetically predicted high cortisol concentrations are associated with hypertension and anxiety, and low CBG concentrations/binding affinity, with the hypocortisolemic triad. Acquired CBG deficiency in septic shock results in 3-fold higher mortality when hydrocortisone administration produces equivocal results, consistent with CBG's role in spatiotemporal cortisol delivery. We propose some stress system disorders result from constitutional stress system variants rather than stressors themselves. Altered CBG:cortisol buffering may influence interstitial cortisol ultradian surges leading to pathological tissue effects, an example of stress system variants contributing to stress-related disorders.

Fabrication of an affordable and sensitive corticosteroid-binding globulin immunosensor based on electrodeposited gold nanoparticles modified glassy carbon electrode.

Herein, we fabricated an ultrasensitive electrochemical immunosensor for the quantitative detection of corticosteroid-binding globulin (CBG). CBG is a protein that regulates glucocorticoid levels and is an important biomarker for inflammation. A decrease in CBG levels is a key biomarker for inflammatory diseases, such as septic shock. To enhance the electrochemical performance and provide a large surface area for anti-CBG immobilization, we functionalized the glassy carbon electrode surface with AuNPs. Electrochemical characterization methods including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to examine the construction of the fabricated immunosensor. The electrochemical signal demonstrated a remarkable sensitivity to the CBG antigen, with a detection range from 0.01 to 100 µg/mL and a limit of detection of 0.012 µg/mL, making it suitable for both clinical and research applications. This label-free immunosensor offers significant advantages, including high sensitivity, low detection limits and excellent selectivity, making it a promising tool for detecting CBG in complex biological samples. Its potential applications include early disease diagnosis, treatment monitoring and studying CBG-related physiological processes.

Cortisol: mediciones de laboratorio y aplicación clínica / Cortisol: laboratory measurements and clinical application

Resumen: la medición del cortisol total en sangre ha sido parte fundamental en el estudio del eje hipotálamo-hipófisis-adrenal y de sus alteraciones, tales como el síndrome de Cushing y la insuficiencia adrenal. El cortisol circula en plasma en su mayoría unido a proteínas, pero su fracción libre es la biológicamente activa y se puede medir en sangre, orina y saliva. La secreción de cortisol no es homogéneadurante el día, por el contrario, está regida por un ritmo circadiano, que a su vez, se puede ver afectado por diferentes estresores físicos y psicológicos. Por esta razón, se cuenta con pruebas como el cortisol en orina de 24 horas que permiteevaluar la producción diaria de cortisol. También es posible realizar pruebas funcionales como la supresión de cortisol con dexametasona para el estudio del síndrome de Cushing y la prueba de estímulo con la hormona adrenocorticotropa(ACTH) como parte del estudio de la insuficiencia adrenal. Esta revisión tiene como objetivo realizar una puesta al día sobre los diferentes métodos para medir el cortisol como parte del estudio del eje hipotálamo-hipófisis-adrenal, haciendo énfasis en su utilidad para el diagnóstico de condiciones patológicas endocrinas.

Abstract: Total cortisol measurement in blood has been a fundamental part in the study of the hypothalamic-pituitary-adrenal axis, and of its disorders, such as Cushing syndrome and adrenal insufficiency. Cortisol circulates in the plasma mainly bound to proteins, but the free fraction is the biologically activeone, which can be measure in blood, urine, and saliva. Cortisol secretion is not homogeneous throughout the day; instead, secretion is governed by a circadian rhythm that also can be affected by different physical and psychologicalstressors. For this reason, other tests such as 24-hour urinary cortisol are available, which evaluates the daily production of cortisol. Functional tests such as cortisol suppression with dexamethasone for the Cushing’s syndrome study and the ACTH stimulation test as part of adrenal insufficiency study can also be performed. This review aims to perform an update on the different cortisol measuring methods as part of the study of hypothalamic – pituitary – adrenal axis, emphasizing in their use to endocrine diseases diagnosis.