Glucocorticoid Receptor in Health and Disease

Glucocorticoid Receptor β Induces Hepatic Steatosis by Augmenting Inflammation and Inhibition of the Peroxisome Proliferator-activated Receptor (PPAR) α

Glucocorticoids (GCs) regulate energy supply in response to stress by increasing hepatic gluconeogenesis during fasting. Long-term GC treatment induces hepatic steatosis and weight gain. GC signaling is coordinated via the GC receptor (GR) GRα, as the GRβ isoform lacks a ligand-binding domain. The roles of the GR isoforms in the regulation of lipid accumulation is unknown. The purpose of this study was to determine whether GRβ inhibits the actions of GCs in the liver, or enhances hepatic lipid accumulation. We show that GRβ expression is increased in adipose and liver tissues in obese high-fat fed mice. Adenovirus-mediated delivery of hepatic GRβ overexpression (GRβ-Ad) resulted in suppression of gluconeogenic genes and hyperglycemia in mice on a regular diet. Furthermore, GRβ-Ad mice had increased hepatic lipid accumulation and serum triglyceride levels possibly due to the activation of NF-κB signaling and increased tumor necrosis factor α (TNFα) and inducible nitric-oxide synthase expression, indicative of enhanced M1 macrophages and the development of steatosis. Consequently, GRβ-Ad mice had increased glycogen synthase kinase 3β (GSK3β) activity and reduced hepatic PPARα and fibroblast growth factor 21 (FGF21) expression and lower serum FGF21 levels, which are two proteins known to increase during fasting to enhance the burning of fat by activating the β-oxidation pathway. In conclusion, GRβ antagonizes the GC-induced signaling during fasting via GRα and the PPARα-FGF21 axis that reduces fat burning. Furthermore, hepatic GRβ increases inflammation, which leads to hepatic lipid accumulation.

Correlation between cytokine levels in nasal fluid and scored clinical parameters in patients with nasal polyposis

The aim of this study was to compare the cytokine levels in nasal fluid in subjects with nasal polyposis (NP) and co-morbid asthma and NP patients without asthma and to correlate these levels with clinical parameters of severity of disease. Forty NP patients (20 asthmatic and 20 nonasthmatic) were enrolled. Nasal secretion samples were collected from nasal cavities of all 40 subjects. The levels of Th1 cytokines IL-2, IL-12 and IFN-γ, Th2 cytokines IL-4, IL-5, IL-6, and IL-10, chemokine IL-8, and proinflammatory cytokines IL-1β, TNF-α and TNF-β were measured using flow cytometric method. Each of the 40 patients was staged clinically according to global nasal symptom score, endoscopic score, and Lund-Mackay computed tomography (CT) score. The concentrations of Th2 cytokines IL-5, IL-6 and IL-10 were significantly higher (P < 0.01, P < 0.01, P < 0.05) in patients with NP and asthma compared with NP patients without asthma. Positive correlations were observed between concentration of IL-2 in nasal secretions and global nasal symptom score, endoscopic score, and Lund-Mackay score only in NP patients without asthma. We also found positive correlation between CT score and the levels of IL-8, IL-4, and IL-1β in nonasthmatic patients. Finally, our results showed a positive correlation between IL-5 levels in nasal fluid and endoscopic score only in asthmatic patients. NP in asthmatic patients have different immunological patterns compared to those without asthma. We also concluded that concentrations of cytokines measured in nasal fluid were not sensitive enough to determine the severity of disease.

Morphofunctional Characteristics of Pituitary Adrenocorticotropes in An Animal Model of Heat Stress

As a result of the global warming, the average ambient temperature during summertime has increased in regions with moderate continental cli mate. The effects of 24 h exposure to heat stress (35±1 °C) on the morphology and function of pituitary adrenocorticotropes were examined in adult male Wistar rats. Significant changes in the morphofunctional features of adrenocorticotropes were found after the heat stress, with no differences noted in the cell shape or localization, compared to controls. The adrenocorticotropes cell volume, as well as the volume density, were significantly decreased (p<0.05) by 12.3% and 26.7%, respectively, in comparison with controls. The concentration of plasma adrenocorticotropic hormone and serum corticosterone in the heat stressed group were significantly decreased (p<0.05) by 21.9% and 27.2%, respectively, compared to controls. These findings suggest that 24 h exposure of adult male rats to heat stress has an inhibitory effect on the morphofunctional characteristics of adrenocorticotropes.

Neuroendocrine Tumors — Laboratory Diagnosis

Neuroendocrine tumors (NETs) are a heterogeneous group of neoplasms originating from endocrine cells, which are characterized by the presence of secretory granules as well as the ability to produce biogenic amines and polypeptide hormones. These tumors originate from endocrine glands such as the adrenal medulla, the pituitary, and the parathyroids, as well as endocrine islets within the thyroid or the pancreas, and dispersed endocrine cells in the respiratory and gastrointestinal tract. The clinical behavior of NETs is extremely variable; they may be functioning or not functioning, ranging from very slow-growing tumors (well-differentiated NETs), which are the majority, to highly aggressive and very malignant tumors (poorly differentiated NETs). Classically, NETs of the gastrointestinal tract are classified into 2 main groups: (1) carcinoids and (2) endocrine pancreatic tumors (EPTs). Most neuroendocrine tumors produce and secrete a multitude of peptide hormones and amines. Some of these substances cause a specific clinical syndrome: carcinoid, Zollinger-Ellison, hyperglycemic, glucagonoma and WDHA syndrome. Specific markers for these syndromes are basal and/or stimulated levels of urinary 5-HIAA, serum or plasma gastrin, insulin, glucagon and vasoactive intestinal polypeptide, respectively. Some carcinoid tumors and about one third of endocrine pancreatic tumors do not present any clinical symptoms and are called ‘nonfunctioning’ tumors. Therefore, general tumor markers such as chromogranin A, pancreatic polypeptide, serum neuron-specific enolase and subunits of glycoprotein hormones have been used for screening purposes in patients without distinct clinical hormone-related symptoms. Among these general tumor markers chromogranin A, although its precise function is not yet established, has been shown to be a very sensitive and specific serum marker for various types of neuroendocrine tumors. This is because it may also be elevated in many cases of less well-differentiated tumors of neuroendocrine origin that do not secrete known hormones. At the moment, chromogranin A is considered the best general neuroendocrine serum or plasma marker available both for diagnosis and therapeutic evaluation, and is increased in 50-100% of patients with various neuroendocrine tumors. Chromogranin A serum or plasma levels reflect tumor load, and it may be an independent marker of prognosis in patients with midgut carcinoids.