Thyroid Hormone Signaling in Retinal Development and Function: Implications for Diabetic Retinopathy and Age-Related Macular Degeneration.

Thyroid Hormones (THs) play a central role in the development, cell growth, differentiation, and metabolic homeostasis of neurosensory systems, including the retina. The coordinated activity of various components of TH signaling, such as TH receptors (THRs) and the TH processing enzymes deiodinases 2 and 3 (DIO2, DIO3), is required for proper retinal maturation and function of the adult photoreceptors, Müller glial cells, and pigmented epithelial cells. Alterations of TH homeostasis, as observed both in frank or subclinical thyroid disorders, have been associated with sight-threatening diseases leading to irreversible vision loss i.e., diabetic retinopathy (DR), and age-related macular degeneration (AMD). Although observational studies do not allow causal inference, emerging data from preclinical models suggest a possible correlation between TH signaling imbalance and the development of retina disease. In this review, we analyze the most important features of TH signaling relevant to retinal development and function and its possible implication in DR and AMD etiology. A better understanding of TH pathways in these pathological settings might help identify novel targets and therapeutic strategies for the prevention and management of retinal disease.

LOX-1 variants modulate the severity of cardiovascular disease: state of the art and future directions.

Atherosclerosis is one of the major causes of cerebral infarction and many other ischemic cardio-cerebrovascular diseases. Although large randomized clinical trials have highlighted the impressive benefits of lipid-lowering therapies, the 50-70% of patients who have achieved their lipid-lowering goal remain at high cardiovascular disease risk. For this reason, there is a need to investigate other markers of atherosclerosis progression. LOX-1 is a scavenger receptor that accepts oxidized low-density lipoproteins as major ligand and internalizes it by endocytosis favoring its retention in subendothelial layer and triggering a wide variety of proatherogenic events. However, other factors such as cytokines, shear stress, and advanced glycation end-products can upregulate LOX-1. LOX-1 is encoded by the OLR1 gene, located in the p12.3-p13 region of chromosome 12. OLR1 gene has different isoforms induced by splicing, or single-nucleotide polymorphisms (SNPs). According to some authors, the expression of these isoforms induces a different effect on atherosclerosis and cardiovascular disease. In particular, LOXIN, an isoform lacking part of the functional domain, exerts an important role in atherosclerosis protection. In other cases, studies on SNPs showed an association with more severe forms, like in the case of 3'UTR polymorphisms. The knowledge of these variants can give rise to the development of new preventive therapies and can lead to the identification of subjects at greater risk of cardiovascular event. In this review, we reported the state of the art regarding SNPs with known effects on OLR1 splicing and how LOX-1 variants modulate the severity of cardiovascular disease.

Classes of Lipid Mediators and Their Effects on Vascular Inflammation in Atherosclerosis.

It is commonly believed that the inactivation of inflammation is mainly due to the decay or cessation of inducers. In reality, in connection with the development of atherosclerosis, spontaneous decay of inducers is not observed. It is now known that lipid mediators originating from polyunsaturated fatty acids (PUFAs), which are important constituents of all cell membranes, can act in the inflamed tissue and bring it to resolution. In fact, PUFAs, such as arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), are precursors to both pro-inflammatory and anti-inflammatory compounds. In this review, we describe the lipid mediators of vascular inflammation and resolution, and their biochemical activity. In addition, we highlight data from the literature that often show a worsening of atherosclerotic disease in subjects deficient in lipid mediators of inflammation resolution, and we also report on the anti-proteasic and anti-thrombotic properties of these same lipid mediators. It should be noted that despite promising data observed in both animal and in vitro studies, contradictory clinical results have been observed for omega-3 PUFAs. Many further studies will be required in order to clarify the observed conflicts, although lifestyle habits such as smoking or other biochemical factors may often influence the normal synthesis of lipid mediators of inflammation resolution.

Role of miR-133/Dio3 Axis in the T3-Dependent Modulation of Cardiac mitoK-ATP Expression.

The opening of the ATP-sensitive mitochondrial potassium channel (mitok-ATP) is a common goal of cardioprotective strategies in the setting of acute and chronic myocardial disease. The biologically active thyroid hormone (TH), 3-5-3-triiodothyronine (T3), has been indicated as a potential activator of mitoK-ATP but the underlying mechanisms are still elusive. Here we describe a novel role of T3 in the transcriptional regulation of mitoK and mitoSur, the recently identified molecular constituents of the channel. To mimic human ischemic heart damage, we used a rat model of a low T3 state as the outcome of a myocardial ischemia/reperfusion event, and neonatal rat cardiomyocytes (NRCM) challenged with hypoxia or H2O2. Either in the in vivo or in vitro models, T3 administration to recover the physiological concentrations was able to restore the expression level of both the channel subunits, which were found to be downregulated under the stress conditions. Furthermore, the T3-mediated transcriptional activation of mitoK-ATP in the myocardium and NRCM was associated with the repression of the TH-inactivating enzyme, deiodinase 3 (Dio3), and an up-regulation of the T3-responsive miR-133a-3p. Mechanistically, the loss and gain of function experiments and reporter gene assays performed in NRCM, have revealed a new regulatory axis whereby the silencing of Dio3 under the control of miR-133a-3p drives the T3-dependent modulation of cardiac mitoK and mitoSur transcription.

Status of biomarkers for the identification of stable or vulnerable plaques in atherosclerosis.

Atherosclerosis is a systemic inflammation of the arteries characterized by atherosclerotic plaque due to the accumulation of lipids, inflammatory cells, apoptotic cells, calcium and extracellular matrix (ECM) proteins. Stable plaques present a chronic inflammatory infiltration, whereas vulnerable plaques present an 'active' inflammation involved in the thinning of the fibrous cap that predisposes to plaque rupture. Several complex biological cellular processes lead plaques to evolve from stable to vulnerable predisposing them to rupture and thrombosis. In this review, we analyze some emerging circulating biomarkers related to inflammation, ECM and lipid infiltration, angiogenesis, metalloproteinases and microRNA (miRNA), as possible diagnostic and prognostic indicators of plaque vulnerability.

Role of oxidative stress-related biomarkers in heart failure: galectin 3, α1-antitrypsin and LOX-1: new therapeutic perspective?

Heart failure (HF) is considered one of the most common diseases and one of the major causes of death. The latest studies show that HF is associated with an increase in oxidative stress. The use of antioxidants as therapy is effective in animal models, but not in humans. In this review, we analyse some emerging markers related to oxidative stress, evaluating their possible use as therapeutic targets: galectin-3, a ß galactoside associated with myocardial fibrosis, α1-antitrypsin, an antiprotease and lectin-like oxidized low-density-lipoprotein receptor-1, the major receptor for ox-LDL. The up-regulation of galectin-3 appears to be associated with HF, atrial fibrillation, dilated cardiomyopathy, fibrogenesis and mortality, while in other cases it seems that galectin-3 may be protective in ischaemia-reperfusion injury. Serum α1-antitrypsin protein levels may increase in the presence of high concentrations of serum proteases, which are over expressed during reperfusion. The overexpression of α1-antitrypsin or the exogenous α1-antitrypsin treatment exhibits an anti-oxidative stress role, evaluated by increased eNOS expression and by decreased MMP9 expression, implicated in HF. The cardiac lectin-like oxidized low-density-lipoprotein receptor-1 is activated by oxidative stress in ischaemia-reperfusion injury, inducing apoptosis in cardiomyocytes through the deleterious NF-kB pathway, while the administration of anti-lectin-like oxidized low-density-lipoprotein receptor-1 antibody suppresses apoptosis and reduces the extent of myocardial infarction. In conclusion, α1-antitrypsin and lectin-like oxidized low-density-lipoprotein receptor-1 seem to represent two good markers in HF and therapeutic targets, whereas galectin-3 does not.

Modification of gene expression profiling related to renin-angiotensin system in an ischemia/reperfusion rat model after T3 infusion.

Triiodothyronine (T3) and renin-angiotensin system (RAS) are functionally related in cardiovascular system. Recently, in an in vivo myocardial ischemia/reperfusion (I/R) model in rats, we showed that T3 treatment improved the post-ischemic recovery of cardiac function. In the present study, we used the same experimental model of regional I/R, obtained by 30 min occlusion of the left descending coronary artery, followed by 3-days of reperfusion, to investigate the effect of 48-h treatment (started 1 day after ischemia) with 6 µg/kg/day T3 or vehicle. T3 was delivered by constant subcutaneous infusion via miniosmotic pump. In particular, aim of this work is to evaluate the effects of T3 on the gene expression of the main receptors and enzymes involved in the two cardiac arms of RAS in an in vivo rat model of I/R: AT1R-ACE (detrimental arm) and AT2R/MAS1-ACE2 (protective arm). Gene expression was evaluated by Real-Time PCR in infarct zone (Area-At-Risk: AAR) and in tissues distant from ischemic wound (Remote Zone: RZ). Three different rat groups were used: sham-operated; I/R and I/R + T3. Main result of the study is the opposite response of AT1R and AT2R/MAS1 expression to I/R procedure and to T3 administration after I/R in both AAR and RZ. Moreover, T3 significantly increased ACE and ACE2 enzyme expression in AAR and RZ. This study reveals that T3 stimulates the expression of protective genes related to RAS such as AT2R/MAS1-ACE2 mainly in BZ, suggesting that, at least in part, T3 could be involved in the local cardiac ameliorative response to I/R procedure.

Evidence for persistent organochlorine pollutants in the human adrenal cortex.

Environmental pollutants may act as endocrine disruptors in animals. Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) enter the food chain and may accumulate in the fatty animal tissues, including adrenals. To our knowledge, no previous study has investigated their presence in the human normal adrenal (NA) cortex and aldosterone-producing adenomas (APA). Surgical fragments of APA from 11 patients and NA from 8 kidney donors were analyzed for 16 PCBs congeners and 10 OCPs. A Matrix Solid-Phase Dispersion (MSPD) method for simultaneous determination of the target compounds in cortex homogenates was developed. A gas-chromatography triple quadrupole mass spectrometry (Triple Quad GC-MS) system was used for the analysis. Data were analyzed using Random Forest and Wilcoxon's rank-sum test. OCPs and PCBs were found in specimens from both types. A subset of pollutants characterized APA more than NA. Higher concentrations (µg g-1 ) in APA were observed for α-, ß-, and γ- Hexachlorocyclohexane (HCH) (1.48 ± 3.32 vs. 0.17 ± 0.19, P = 0.028; 2.81 ± 2.10 vs. 0.96 ± 0.98, P = 0.011; 2.16 ± 4.85 vs. 0.17 ± 0.26, P = 0.004, respectively), as well as for Hexachlorobenzene (HCB) and for PCBs 28, 52 and 101 (3.41 ± 3.11 vs. 0.97 ± 1.06, P = 0.021; 2.34 ± 4.68 vs. 0.25 ± 0.22, P = 0.039; 0.58 ± 1.19 vs. 0.06 ± 0.02, P = 0.002; 0.26 ± 0.43 vs. 0.05 ± 0.00, P = 0.001, respectively). Environmental organochlorine pollutants were shown to be present in the human normal and abnormal adrenal cortex, deserving future investigation on their possible role as adrenal endocrine disruptors in human disease. Copyright © 2017 John Wiley & Sons, Ltd.

Roles of LOX-1 in microvascular dysfunction.

Studies from human and animal models with metabolic disease and hypertension highlight atrophic remodeling, reduced lumen size and thinner vascular walls of microvessels with profound density reduction. This impaired vascular response limits the perfusion of peripheral tissues inducing organ damage. These conditions are strongly associated with oxidative stress and in particular with the up-regulation of lectin-like oxidized low density lipoprotein receptor-1 (LOX-1). Several factors such as cytokines, shear stress, and advanced glycation end-products, especially oxLDL, can up-regulate LOX-1. The activation of this receptor induces the production of adhesion molecules, cytokines and the release of reactive oxygen species via NADPH oxidase. LOX-1 is considered a potent mediator of endothelial dysfunction and it is significantly associated with reduced microvascular endothelium NO-dependent vasodilation in hypercholesterolemia and hypertension. Microvascular endothelial cells increased the expression of IL-6 in association with the increased concentration of LDL and its degree of oxidation. Moreover, increased IL-6 levels are associated with up-regulation of LOX-1 in a dose-dependent manner. Another consequence of microvascular inflammation is the generation of small amounts of ROS, similar to those induced by low concentration of oxLDL (<5 µg/mL) which induces capillary tube formation of endothelial cells, through LOX-1 up-regulation. In light of its central role, LOX-1 represents an attractive therapeutic target for the treatment of human atherosclerotic diseases and microvascular disorders.

Thyroid hormone deiodinases D1, D2, and D3 are expressed in human endothelial dermal microvascular line: effects of thyroid hormones.

Endothelial system acts as a large endocrine organ in the human body; however, little is still known about the regulative role of THs on endothelial cells. Aim of the present study was to investigate the expression of the TH deiodinases (D1, D2, and D3) and TH receptors (TRα1, TRα2, and TRß1) in an endothelial microvascular cultured cell model (HMEC-1), after stimulation with triiodothyronine (T3, 10-100 nM), thyroxine (T4, 10-100 nM), and reverse T3 (rT3, 1-10 nM). DIO1 was significantly inhibited by T4 at 10 and 100 nM (p < 0.001). rT3 significantly inhibited DIO1 at 1 nM concentration (p < 0.01) and stimulated DIO1 at 10 nM dosage (p < 0.001). T4 and rT3 significantly inhibited DIO2 at all concentrations. DIO3 was induced at 100 nM T3 (p < 0.05) and 100 nM rT3 (p < 0.01), and TRα1 and TRα2 mRNAs were significantly increased after 100 nM T3 treatment (p < 0.05) and decreased after 1 and 10 nM rT3 (p < 0.05). TRß1 was significantly increased by all THs at different concentrations: 10 nM T3 and 100 nM T3 (p < 0.05), 1 nM rT3 (p < 0.001), and 100 nM T4 (p < 0.01). D1 and D2 protein levels were evaluated, but no significant difference was observed for any hormonal treatment. For the first time, we found that the TH deiodinases and receptors are expressed in endothelial HMEC-1 cells. These findings might be of significant clinical relevance, given the important regulatory role of the endothelium as first barrier to the bloodstream.

LOX-1, a new marker of risk and prognosis in coronary artery disease?

The development of atherosclerosis is caused by the accumulation of lipid, inflammatory cytokine production, and the large amount of inflammatory cells in the arterial wall. It is now established that the presence of oxidized low-density lipoproteins (ox-LDL) has an important role in the pathogenesis of the disease. There are many scavenger receptors for ox-LDL, among which LOX-1 seems to be important for the induction of endothelial dysfunction and the other subsequent events that lead to the formation of atheromatous plaque. Our findings indicate the presence of a regulatory role induced by the presence of ox-LDL on LOX-1 through the amplification of IL-6 synthesis. This mechanism contributes to the upregulation of the ORL-1 gene expression in presence of risk factors. Many authors have shown the possibility to use LOX-1 as a good marker for the diagnosis and prognosis of coronary artery disease because it is easy to measure and more sensitive than other markers commonly used in the routine of laboratory medicine.

Activated fibroblasts in cardiac and cancer fibrosis: An overview of analogies and new potential therapeutic options.

Heart disease and cancer are two major causes of morbidity and mortality in the industrialized countries, and their increasingly recognized connections are shifting the focus from single disease studies to an interdisciplinary approach. Fibroblast-mediated intercellular crosstalk is critically involved in the evolution of both pathologies. In healthy myocardium and in non-cancerous conditions, resident fibroblasts are the main cell source for synthesis of the extracellular matrix (ECM) and important sentinels of tissue integrity. In the setting of myocardial disease or cancer, quiescent fibroblasts activate, respectively, into myofibroblasts (myoFbs) and cancer-associated fibroblasts (CAFs), characterized by increased production of contractile proteins, and by a highly proliferative and secretory phenotype. Although the initial activation of myoFbs/CAFs is an adaptive process to repair the damaged tissue, massive deposition of ECM proteins leads to maladaptive cardiac or cancer fibrosis, a recognized marker of adverse outcome. A better understanding of the key mechanisms orchestrating fibroblast hyperactivity may help developing innovative therapeutic options to restrain myocardial or tumor stiffness and improve patient prognosis. Albeit still unappreciated, the dynamic transition of myocardial and tumor fibroblasts into myoFbs and CAFs shares several common triggers and signaling pathways relevant to TGF-ß dependent cascade, metabolic reprogramming, mechanotransduction, secretory properties, and epigenetic regulation, which might lay the foundation for future antifibrotic intervention. Therefore, the aim of this review is to highlight emerging analogies in the molecular signature underlying myoFbs and CAFs activation with the purpose of identifying novel prognostic/diagnostic biomarkers, and to elucidate the potential of drug repositioning strategies to mitigate cardiac/cancer fibrosis.

Cardiovascular risk in COVID-19 infection.

A few months ago a new coronavirus was identified in Cina officially named by the WHO as COVID-19. The thousands of patients who died showed pneumonia and alveolar damage, but actually, according to several authors in addition to the acute respiratory distress syndrome the virus can give rise to multiorgan failure. In fact, many people died equally despite being intubated and treated for respiratory failure. In this review, we especially wanted to describe the virus effects on the cardiovascular system, probably the leading cause of death of thousands of deceased patients. Therefore, mortality is indirectly induced by the virus through vascular inflammation and cardiovascular damage and patients with severe COVID-19 infection showed significantly increased levels of cardiac troponin I and inflammatory cytokines. The main activation of the signal pathways for the production of inflammatory cytokines are the toll-like receptors that recognize the presence of viral nucleic acids and the ACE-2 receptors, that the virus uses to infect the cells. The binding to ACE-2 also allows to promote high levels of angiotensin II by promoting high levels of blood pressure. High levels of IL-6, IL-1B and IL-8 have been associated with plaque instability and increased thrombotic risk. Furthermore IL-6 is involved in the stimulation of matrix-degrading enzymes such as matrix metalloproteinases, and may contribute to the development of acute coronary syndrome. In addition, TNF-α, IL-1 and IL-6 present in patients with severe COVID-19 are associated with coagulation activation and thrombin generation resulting in disseminated intravascular coagulation or thrombotic microangiopathy. Considering these pathological effects of the virus, anti-inflammatory and anticoagulant treatments are to be considered to avoid cardiovascular events. In this regard, heparin, in addition to its anticoagulant characteristics, has been shown to have good control over inflammation and to be a good anti-viral drug.

TSH induces co-localization of TSH receptor and Na/K-ATPase in human erythrocytes.

Thyroid stimulating hormone (TSH) binds to a specific TSH receptor (TSHR) which activates adenylate cyclase and increases cAMP levels in thyroidal cells. Recent studies have reported the presence of TSH receptor in several extra-thyroidal cell types, including erythrocytes. We have previously suggested that TSH is able to influence the erythrocyte Na/K-ATPase ouabain binding properties through a receptor mediated mechanism. The direct interaction of TSH receptor with the Na/K-pump and a functional role of TSHR in erythrocytes was not demonstrated. The interaction of TSH receptor with Na/K-pump and a TSHR functional role are not yet demonstrated in erythrocytes. In this study, we examined the interaction between the two receptors after TSH treatment using immunofluorescence coupled to confocal microscopy and a co-immunoprecipitation technique. The cAMP dependent signalling after TSH treatment was measured to verify TSHR functionality. We found that TSH receptor and Na/K-ATPase are localized on the membranes of both erythrocytes and erythrocyte ghosts; TSH receptor responds to TSH treatment by increasing intracellular cAMP levels from two to tenfold. In ghost membranes TSH treatment enhances up to three fold co-localization of TSHR with Na/K-ATPase and co-immunoprecipitation confirms their direct physical interaction. In conclusion our results are compatible with the existence, in erythrocytes, of a functional TSHR that interacts with Na/K-ATPase after TSH treatment, thus suggesting a novel cell signalling pathway, potentially active in local circulatory control.

Angiopoietin 2 signal complexity in cardiovascular disease and cancer.

The angiopoietin signal transduction system is a complex of vascular-specific kinase pathways that plays a crucial role in angiogenesis and maintenance of vascular homeostasis. Angiopoietin1 (Ang1) and 2 (Ang2), the ligand proteins of the pathway, belong to a family of glycoproteins that signal primarily through the transmembrane Tyrosine-kinase-2 receptor. Despite a considerable sequence homology, Ang1 and Ang2 manifest antagonistic effects in pathophysiological conditions. While Ang1 promotes the activation of survival pathways and the stabilization of the normal mature vessels, Ang2 can either favor vessel destabilization and leakage or promote abnormal EC proliferation in a context-dependent manner. Altered Ang1/Ang2 balance has been reported in various pathological conditions in association with inflammation and deregulated angiogenesis. In particular, increased Ang2 levels have been documented in human cancer and cardiovascular disease (CVD), including ischemic myocardial injury, heart failure and other cardiovascular complications secondary to diabetes, chronic renal damage and hypertension. Despite the obvious phenotypic differences, CVD and cancer share some common Ang2-dependent etiopathological mechanisms such as inflammation, epithelial (or endothelial) to mesenchymal transition, and adverse vascular network remodeling. Interestingly, both cancer and CVD are negatively affected by thyroid hormone dyshomeostasis. This review provides an overview of the complex Ang2-dependent signaling involved in CVD and cancer, as well as a survey of the related clinical literature. Moreover, on the basis of recent molecular acquisitions in an experimental model of post ischemic cardiac disease, the putative novel role of the thyroid hormone in the regulation of Ang1/Ang2 balance is also briefly discussed.

LOX-1 receptor: A potential link in atherosclerosis and cancer.

Altered production of reactive oxygen species (ROS), causing lipid peroxidation and DNA damage, contributes to the progression of atherosclerosis and cancer. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a lectin-like receptor for oxidized low-density lipoproteins (ox-LDL) primarily expressed in endothelial cells and vasculature-rich organs. LOX-1 receptors is a marker for atherosclerosis, and once activated by ox-LDL or other ligands, stimulates the expression of adhesion molecules, pro-inflammatory signaling pathways and proangiogenic proteins, including NF-kB and VEGF, in vascular endothelial cells and macrophages. Several different types of cancer reported LOX-1 gene upregulation, and numerous interplays exist concerning LOX-1 in atherosclerosis, metabolic diseases and cancer. One of them involves NF-kB, an oncogenic protein that regulates the transcription of several inflammatory genes response. In a model of cellular transformation, the MCF10A ER-Src, inhibition of LOX-1 gene reduces NF-kB activation and the inflammatory and hypoxia pathways, suggesting a mechanistic connection between cellular transformation and atherosclerosis. The remodeling proteins MMP-2 and MMP-9 have been found increased in angiogenesis in atherosclerotic plaque and also in human prostate cancer cells. In this review, we outlined the role of LOX-1 in atherogenesis and tumorigenesis as a potential link in these diseases, suggesting that LOX-1 inhibition could represent a promising strategy in the treatment of atherosclerosis and tumors.

Neutrophyl to lymphocyte ratio and c reactive protein are indipendent predictors of severe coronary artery disease: comparison with hydroperoxides and consolidated inflammatory markers.

Several inflammatory factors have been determined as indicators of coronary artery disease (CAD) and recently some studies showed neutrophyl to lymphocyte ratio (NLR) as a powerful predictor. The aim of this study was to evaluate NLR, comparing it with the consolidate inflammatory and oxidative stress marker in a group of control and CAD patients. Twenty healthy subjects and 47 patients, that were affected by 1-4 compromised coronary arteries, were enrolled in the study. All subjects were classified into 3 groups on the base of NLR tertile. The efficacy of NLR as indicator of the severity of CAD and its association with inflammatory markers were analyzed. According to the tertile of NLR, patients in the high NLR value had higher % of males, number of compromise coronary arteries, CRP levels, neutrophyl count, and low lymphocyte count. Moreover NLR and CRP levels showed to be independent predictors of 3-4 compromised coronary arteries. The ROC curve analysis showed that CRP and NLR markers had the largest area under the curve (AUC = 0,85, 95% CI: 0,74-0,96, p = 0,000; AUC = 0,81, 95% CI: 0,66-0,96, p = 0,001). In conclusion our data indicate that only NLR and CRP are independent predictors for 3-4 compromised coronary arteries.

Angiopoietin-2: a biomarker in hyperthyroidism.

Serum angiopoietin-2 level is elevated in several diseases suggesting its possible role as a mediator of angiogenesis and vascular network remodeling. Triiodothyronine and thyroxine have well documented effects on angiogenesis in vitro, but only few reports have studied angiopoietin-2 in thyroid-disease patients. The aim of the present study was to measure soluble angiopoietin-2 serum levels in a group of thyroid-disease patients with different levels of free triiodothyronine and thyroxine. Angiopoietin- 2 were quantified by ELISA in sera of fifteen healthy volunteers and forty-two thyroid ambulatory patients: nine with hyperthyroidism, four in therapy for hyperthyroidism, seven with subclinal hyperthyroidism, twelve with hypothyroidism, five with thyroiditis and five in therapy for thyroiditis. Median angiopoietin-2 level was significantly elevated in hyperthyroid patients (p < 0.01) and it was significantly increased vs all the other groups (p < 0.0001). In hyperthyroid patients anti thyroid therapy seems to reduce angiopoietin-2 level. A significant positive correlation was observed between Log angiopoietin-2 levels and serum concentration of Log free triiodothyronine (r = 0.4, P < 0.001) and Log free thyroxine (r = 0.4, P < 0.001) respectively. In conclusion, increased levels of angiopoietin-2 are present in hyperthyroid patients, and seems to correlate with free triiodothyronine and free thyroxine levels but not with anti-thyroid antibodies. These findings suggest angiopoietin-2 as a mediator of angiogenesis and vascular network remodeling in this disease, but further studies will be needed to determine the role of this biomarker in the pathophysiology and progression of hyperthyroidism.

Renin-Angiotensin System Responds to Prolonged Hypotensive Effect Induced by Mandibular Extension in Spontaneously Hypertensive Rats.

There is an ongoing interest in the renin-angiotensin system (RAS) contribution either to pathological mechanisms leading to hypertension (mainly regarding the ACE/AngII/AT1R axis), or, to RAS protective and pro-regenerative actions, primarily ascribed to the mediation of the AT2R and the MAS1 receptor. In the present study, we evaluated the modulation of gene expression and protein levels of "deleterious" (ACE/AngII/AT1R) and "protective" [ACE/AngII/AT2R and ACE2/Ang(1-7)/MAS1 arms] RAS components in parietal and frontal areas of cerebral cortex of spontaneously hypertensive rats (SHRs), after two periods of mandibular extensions (MEs). Blood pressure, BP and heart rate, HR were also measured. While no significant changes in BP and HR were present in the sham operated (SO) group, in rats after two MEs (2-ME rats), BP displayed a marked decrease (p < 0.001) at ME2, and remained then stably low for the subsequent observation period. In gene expression analysis, in SHRs undergoing two MEs, either in parietal or frontal cortex, we did not observe any significant variation of AT2R and ACE2 with respect to SO rats. In contrast, we observed a decrease in Mas1 gene expression in parietal area (p < 0.01) and an increase in frontal region (p < 0.01). AT1R and ACE gene expression was significantly higher in 2-ME rats than SO in parietal cortex (p < 0.05) but no difference was observed in the frontal area. Concerning protein levels, in parietal area, AT1R and AT2R did not change whereas MAS1 significantly decreased in 2-ME rats (p < 0.05). In frontal area, both AT1R and AT2R significantly decreased in 2-ME rats (p < 0.05), whereas MAS1 did not significantly change. Gene expression analysis in normotensive (NT) rats revealed the non-detectability of AT1R in both parietal and frontal zone. In parietal area, AT2R (p < 0.0001) and Mas1 (p < 0.01) were significantly decreased in 2-ME NT rats, when compared to SO, and ACE and ACE2 resulted not detectable whereas there was some expression of these genes after 2-ME procedure. In conclusion, our data in rat models indicated that a 2-ME procedure induced a hypotensive response and that a modulation of gene expression and protein levels of RAS components occurred in different cerebral cortex areas.

Presence of a functional TSH receptor on human erythrocytes.

The presence of thyrotropin receptors (TSHR) has been reported in some extrathyroidal tissues but its physio-pathological role still remains unclear. TSH (seems to) affects the human erythrocytes Na(+)/K(+)-ATPase in vitro, however receptors on erythrocytes have not yet been described. In this work the effect of recombinant human TSH (rhTSH) on sites number and activity of erythrocyte Na(+)/K(+)-ATPase was investigated in a group of thyroidectomized patient enrolled for rhTSH test. As detected by (3)H-ouabain binding, rhTSH administration induced a significant increase in the number of sites (p=0.005) and in the Kd (p=0.006) of Na(+)/K(+)-ATPase. rhTSH did not induce significant difference in Na(+)/K(+)-ATPase activity measured by (86)Rb uptake. (125)I-TSH binding studies and Western blotting data showed the existence of TSHR in the erythrocytes of healthy donors. In conclusion The TSH action on Na(+)/K(+)-ATPase of human erythrocytes can be explained by the presence of TSHR.