Post-Transcriptional and Epigenetic Regulation of Estrogen Signaling.

Post-translational and epigenetic regulation are important mechanisms controlling functions of genes and proteins. Although the "classic" estrogen receptors (ERs) have been acknowledged to function in mediating estrogen effects via transcriptional mechanisms, estrogenic agents modulate the turnover of several proteins via post-transcriptional and post-translational pathways including epigenetics. For instance, the metabolic and angiogenic action of G-protein coupled estrogen receptor (GPER) in vascular endothelial cells has been recently elucidated. By interacting with GPER, 17ß-estradiol and the GPER agonist G1 enhance endothelial stability of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) and capillary tube formation by increasing ubiquitin-specific peptidase 19 levels, thereby reducing PFKFB3 ubiquitination and proteasomal degradation. In addition to ligands, the functional expression and trafficking of ERs can be modulated by post-translational modification, including palmitoylation. MicroRNAs (miRNAs), the most abundant form of endogenous small RNAs in humans, regulate multiple target genes and are at the center of the multi-target regulatory network. This review also discusses the emerging evidence of how miRNAs affect glycolytic metabolism in cancer, as well as their regulation by estrogens. Restoring dysregulated miRNA expression represents a promising strategy to counteract the progression of cancer and other disease conditions. Accordingly, estrogen post-transcriptional regulatory and epigenetic mechanisms represent novel targets for pharmacological and nonpharmacological intervention for the treatment and prevention of hormone-sensitive noncommunicable diseases, including estrogen-sensitive cancers of the reproductive system in women. SIGNIFICANCE STATEMENT: The effects of estrogen are mediated by several mechanisms that are not limited to the transcriptional regulation of target genes. Slowing down the turnover of master regulators of metabolism by estrogens allows cells to rapidly adapt to environmental cues. Identification of estrogen-targeted microRNAs may lead to the development of novel RNA therapeutics that disrupt pathological angiogenesis in estrogen-dependent cancers.

Targeting of PFKFB3 with miR-206 but not mir-26b inhibits ovarian cancer cell proliferation and migration involving FAK downregulation.

Few studies explored the role of microRNAs (miRNAs) in the post-transcriptional regulation of glycolytic proteins and downstream effectors in ovarian cancer cells. We recently showed that the functional activation of the cytoskeletal regulator FAK in endothelial cells is fostered by the glycolytic enhancer 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3). We tested the hypothesis that miR-206 and mir-26b, emerging onco-suppressors targeting PFKFB3 in estrogen-dependent tumors, would regulate proliferation and migration of serous epithelial ovarian cancer (EOC) cells via common glycolytic proteins, i.e., GLUT1 and PFKFB3, and downstream FAK. PFKFB3 was overexpressed in SKOV3, and its pharmacological inhibition with 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO) significantly reduced cell proliferation and motility. Both miR-206 and miR-26b directly targeted PFKFB3 as evaluated by a luciferase reporter assay. However, endogenous levels of miR-26b were higher than those of miR-206, which was barely detectable in SKOV3 as well as OVCAR5 and CAOV3 cells. Accordingly, only the anti-miR-26b inhibitor concentration-dependently increased PFKFB3 levels. While miR-206 overexpression impaired proliferation and migration by downregulating PFKFB3 levels, the decreased PFKFB3 protein levels related to miR-26 overexpression had no functional consequences in all EOC cell lines. Finally, consistent with the migration outcome, exogenous miR-206 and miR-26b induced opposite effects on the levels of total FAK and of its phosphorylated form at Tyr576/577. 3PO did not prevent miR-26b-induced SKOV3 migration. Overall, these results support the inverse relation between endogenous miRNA levels and their tumor-suppressive effects and suggest that restoring miR-206 expression represents a potential dual anti-PFKFB3/FAK strategy to control ovarian cancer progression.

Sex-oriented perspectives in immunopharmacology.

Several immunopharmacological agents are effective in the treatment of cancer and immune-mediated conditions, with a favorable impact on life expectancy and clinical outcomes for a large number of patients. Nevertheless, response variation and undesirable effects of these drugs represent major issues, and overall efficacy remains unpredictable. Males and females show a distinct difference in immune system responses, with females generally mounting stronger responses to a variety of stimuli. Therefore, exploring sex differences in the efficacy and safety of immunopharmacological agents would strengthen the practice of precision medicine. As a pharmacological target highlight, programmed cell death 1 ligand 1 (PD-L1) is the first functionally characterized ligand of the coinhibitory programmed death receptor 1 (PD-1). The PD-L1/PD-1 crosstalk plays an important role in the immune response and is relevant in cancer, infectious and autoimmune disease. Sex differences in the response to immune checkpoint inhibitors are well documented, with male patients responding better than female patients. Similarly, higher efficacy of and adherence to tumor necrosis factor inhibitors in chronic inflammatory conditions including rheumatoid arthritis and Crohn's disease have been reported in male patients. The pharmacological basis of sex-specific responses to immune system modulating drugs is actively investigated in other settings such as stroke and type 1 diabetes. Advances in therapeutics targeting the endothelium could soon be wielded against autoimmunity and metabolic disorders. Based on the established sexual dimorphism in immune-related pathophysiology and disease presentation, sex-specific immunopharmacological protocols should be integrated into clinical guidelines.

LDL-cholesterol control in the primary prevention of cardiovascular diseases: An expert opinion for clinicians and health professionals.

AIMS: Although adequate clinical management of patients with hypercholesterolemia without a history of known cardiovascular disease is essential for prevention, these subjects are often disregarded. Furthermore, the scientific literature on primary cardiovascular prevention is not as rich as that on secondary prevention; finally, physicians often lack adequate tools for the effective management of subjects in primary prevention and have to face some unsolved relevant issues. This document aims to discuss and review the evidence available on this topic and provide practical guidance. DATA SYNTHESIS: Available algorithms and risk charts represent the main tool for the assessment of cardiovascular risk in patients in primary prevention. The accuracy of such an estimate can be substantially improved considering the potential contribution of some additional risk factors (C-reactive protein, lipoprotein(a), family history of cardiovascular disease) and conditions (environmental pollution, sleep quality, socioeconomic status, educational level) whose impact on the cardiovascular risk has been better understood in recent years. The availability of non-invasive procedures to evaluate subclinical atherosclerosis may help to identify subjects needing an earlier intervention. Unveiling the presence of these conditions will improve cardiovascular risk estimation, granting a more appropriate intervention. CONCLUSIONS: The accurate assessment of cardiovascular risk in subjects in primary prevention with the use of algorithms and risk charts together with the evaluation of additional factors will allow physicians to approach each patient with personalized strategies, which should translate into an increased adherence to therapy and, as a consequence, a reduced cardiovascular risk.

Non-genomic mechanisms in the estrogen regulation of glycolytic protein levels in endothelial cells.

Few studies have explored the mechanisms coupling estrogen signals to metabolic demand in endothelial cells. We recently showed that 17ß-estradiol (E2) triggers angiogenesis via the membrane G-protein coupled estrogen receptor (GPER) and the key glycolytic protein PFKFB3 as a downstream effector. We herein investigated whether estrogenic agents regulate the stability and/or degradation of glycolytic proteins in human umbilical vein endothelial cells (HUVECs). Similarly to E2, the GPER selective agonist G1 rapidly increased PFKFB3 protein amounts, without affecting mRNA levels. In the presence of cycloheximide, E2 and G1 treatment counteracted PFKFB3 degradation over time, whereas E2-induced PFKFB3 stabilization was abolished by the GPER antagonist G15. Inhibitors of selective SCF E3 ubiquitin ligase (SMER-3) and proteasome (MG132) rapidly increased PFKFB3 protein levels. Accordingly, ubiquitin-bound PFKFB3 was lower in E2- or G1-treated HUVECs. Both agents increased deubiquitinase USP19 levels through GPER signaling. Notably, USP 19 siRNA decreased PFKFB3 levels and abolished E2- and G1-mediated HUVEC tubularization. Finally, E2 and G1 treatments rapidly enhanced glucose transporter GLUT1 levels via GPER independent of transcriptional activation. These findings provide new evidence on mechanisms coupling estrogen signals with the glycolytic program in endothelium and unravel the role of USP19 as a target of the pro-angiogenic effect of estrogenic agents.

Pharmacotherapy of obesity: An update.

Several pharmacological approaches to controlling body weight have been developed over the last decades, albeit with limited success. Currently available agents include centrally acting appetite suppressants and peripherally acting compounds. Efficacy and safety of these agents in the clinical setting require a difficult balance. Further strategies including multiagonists able to simultaneously target multiple actors involved in obesity initiation and expansion such as the glucagon receptor family are under investigation. The results of recent clinical trials are encouraging and highlight emerging compounds as potential game changers. In view of the rising prevalence of obesity and the associated burden of comorbidities worldwide, and compared with other areas of pharmacological intervention, we feel that the field of obesity has been affected by therapeutic inertia. Of note, obesity may also affect the response to concomitant medications such as low-dose aspirin. Lessons from withdrawn agents such as the cannabinoid receptor antagonist rimonabant include developing compounds with a more targeted action profile (i.e., central vs peripheral, or antagonist versus inverse agonist) as well as careful selection of patients based on individual risk factors. We anticipate that the expanding knowledge base and clinical testing will result in improved outcomes for patients with obesity in the near future.

Sex-tailored pharmacology and COVID-19: Next steps towards appropriateness and health equity.

Making gender bias visible allows to fill the gaps in knowledge and understand health records and risks of women and men. The coronavirus disease 2019 (COVID-19) pandemic has shown a clear gender difference in health outcomes. The more severe symptoms and higher mortality in men as compared to women are likely due to sex and age differences in immune responses. Age-associated decline in sex steroid hormone levels may mediate proinflammatory reactions in older adults, thereby increasing their risk of adverse outcomes, whereas sex hormones and/or sex hormone receptor modulators may attenuate the inflammatory response and provide benefit to COVID-19 patients. While multiple pharmacological options including anticoagulants, glucocorticoids, antivirals, anti-inflammatory agents and traditional Chinese medicine preparations have been tested to treat COVID-19 patients with varied levels of evidence in terms of efficacy and safety, information on sex-targeted treatment strategies is currently limited. Women may have more benefit from COVID-19 vaccines than men, despite the occurrence of more frequent adverse effects, and long-term safety data with newly developed vectors are eagerly awaited. The prevalent inclusion of men in randomized clinical trials (RCTs) with subsequent extrapolation of results to women needs to be addressed, as reinforcing sex-neutral claims into COVID-19 research may insidiously lead to increased inequities in health care. The huge worldwide effort with over 3000 ongoing RCTs of pharmacological agents should focus on improving knowledge on sex, gender and age as pillars of individual variation in drug responses and enforce appropriateness.

Phagocytosis and inflammation in crystal-induced arthritis: a synovial fluid and in vitro study.

OBJECTIVES: The aim of this study was to investigate the relationship between the degree of crystal phagocytosis and the magnitude of the local inflammatory process using fresh synovial fluid (SF) collected from patients with crystal-induced arthritis. In parallel, an in vitro model of crystal-induced inflammation was used to assess the effect of cell priming on crystal phagocytosis and IL-1ß production. METHODS: SF was collected from 20 patients with gout and 20 with pyrophosphate crystal-induced arthritis and examined under ordinary and polarised light microscopy for total and differential white blood cell (WBC) count and crystal search. The total phagocytosis index was determined in SF along with IL-1ß, IL-8, IL-10, and TGFß levels. The in vitro studies were performed using primed or unprimed THP-1 cells stimulated with calcium pyrophosphate (CPP) crystals, monosodium urate (MSU) crystals and/or cytochalasin D. RESULTS: We demonstrated that the phagocytosis index calculated on the total number of cells was independent from the inflammatory local indices such as WBC and the percentage of polymorphonuclear cells but showed a positive correlation with pro-inflammatory cytokines. By contrast, the local inflammatory indices (WBC and IL-1ß) showed a strong positive correlation with the percentage of polymorphonuclear cells with crystals internalised and a negative correlation with the percentage of mononuclear cells with crystals internalised. The in vitro study showed that phagocytosis represents a fundamental step in the induction of the inflammatory response to MSU and CPP crystals, but it also occurs in absence of cell priming. CONCLUSIONS: The results of this study indicate a possible role of non-inflammatory phagocytosis in limiting the acute attack of crystal-induced arthritis.

Mild polypharmacy and MCI progression in older adults: the mediation effect of drug-drug interactions.

BACKGROUND: Polypharmacy has been associated with worse cognitive performance, but its impact on mild cognitive impairment (MCI) progression to dementia has not been explored. AIMS: The aims of the study were to investigate the association between multidrug regimens and MCI progression, and the possible mediation of drug-drug interactions and drugs' anticholinergic effect in such association. METHODS: This work included 342 older adults with MCI, who were involved in an Italian multicenter population-based cohort study. Information on drugs taken was derived from general practitioners' records and data on drug-drug interactions and anticholinergic burden [evaluated through the Anticholinergic Cognitive Burden and the Anticholinergic Risk Scale (ARS)] were extracted. Multinomial logistic regressions assessed the associations between mild polypharmacy (≥ 3 drugs/day), drug-drug interactions, and anticholinergic burden with MCI changes after 1-year follow-up. Mediation analysis evaluated potential mediators of that relationship. RESULTS: Approximately, 50% of participants took ≥ 3 drugs/day. During the follow-up, 4.1% of MCI patients progressed to dementia. The odds of developing dementia was sixfold higher in those who took ≥ 3drugs/day (OR = 6.04, 95% CI 1.19-30.74), eightfold higher in those with ≥ 1 drug-drug interaction/s (OR = 8.45, 95% CI 1.70-41.91), and fivefold higher in those with ARS ≥ 1 (OR = 5.10, 95% CI 1.04-24.93). Drug-drug interactions mediated 70.4% of the association between medication number and MCI progression to dementia (p = 0.07). DISCUSSION: Our study suggests that even mild polypharmacy may increase the risk of MCI progression to dementia, probably due to the presence of drug-drug interactions, which often occur in multidrug regimens. CONCLUSIONS: Older people require careful management of pharmacological treatments, with special attention to drug-drug interactions and drug-related anticholinergic effects.

Estrogen Receptor Functions and Pathways at the Vascular Immune Interface.

Estrogen receptor (ER) activity mediates multiple physiological processes in the cardiovascular system. ERα and ERß are ligand-activated transcription factors of the nuclear hormone receptor superfamily, while the G protein-coupled estrogen receptor (GPER) mediates estrogenic signals by modulating non-nuclear second messengers, including activation of the MAP kinase signaling cascade. Membrane localizations of ERs are generally associated with rapid, non-genomic effects while nuclear localizations are associated with nuclear activities/transcriptional modulation of target genes. Gender dependence of endothelial biology, either through the action of sex hormones or sex chromosome-related factors, is becoming increasingly evident. Accordingly, cardiometabolic risk increases as women transition to menopause. Estrogen pathways control angiogenesis progression through complex mechanisms. The classic ERs have been acknowledged to function in mediating estrogen effects on glucose metabolism, but 17ß-estradiol also rapidly promotes endothelial glycolysis by increasing glucose transporter 1 (GLUT1) and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) levels through GPER-dependent mechanisms. Estrogens alter monocyte and macrophage phenotype(s), and induce effects on other estrogen-responsive cell lineages (e.g., secretion of cytokines/chemokines/growth factors) that impact macrophage function. The pharmacological modulation of ERs for therapeutic purposes, however, is particularly challenging due to the lack of ER subtype selectivity of currently used agents. Identifying the determinants of biological responses to estrogenic agents at the vascular immune interface and developing targeted pharmacological interventions may result in novel improved therapeutic solutions.

Pharmacological Approaches to Controlling Cardiometabolic Risk in Women with PCOS.

Polycystic ovary syndrome (PCOS) is characterized by elevated androgen production and subclinical changes in cardiovascular and metabolic risk markers. Total cholesterol, high-density lipoprotein (HDL) cholesterol, fasting glucose, and fasting insulin appear to increase specifically in PCOS compared with fertile women. PCOS also confers an increased risk of cardiometabolic disease in later life. Novel biomarkers such as serum's cholesterol efflux capacity and blood-derived macrophage activation profile may assist in more accurately defining the cardiometabolic risk profile in these women. Aldosterone antagonists, androgen receptor antagonists, 5α-reductase inhibitors, and synthetic progestogens are used to reduce hyperandrogenism. Because increased insulin secretion enhances ovarian androgen production, short-term treatment with metformin and other hypoglycemic agents results in significant weight loss, favorable metabolic changes, and testosterone reduction. The naturally occurring inositols display insulin-sensitizing effects and may be also used in this context because of their safety profile. Combined oral contraceptives represent the drug of choice for correction of androgen-related symptoms. Overall, PCOS management remains focused on specific targets including assessment and treatment of cardiometabolic risk, according to disease phenotypes. While new options are adding to established therapeutic approaches, a sometimes difficult balance between efficacy and safety of available medications has to be found in individual women.

Interplay between gut microbiota and p66Shc affects obesity-associated insulin resistance.

The 66 kDa isoform of the mammalian Shc gene promotes adipogenesis, and p66Shc-/- mice accumulate less body weight than wild-type (WT) mice. As the metabolic consequences of the leaner phenotype of p66Shc-/- mice is debated, we hypothesized that gut microbiota may be involved. We confirmed that p66Shc-/- mice gained less weight than WT mice when on a high-fat diet (HFD), but they were not protected from insulin resistance and glucose intolerance. p66Shc deletion significantly modified the composition of gut microbiota and their modification after an HFD. This was associated with changes in gene expression of Il-1b and regenerating islet-derived protein 3 γ ( Reg3g) in the gut and in systemic trimethylamine N-oxide and branched chain amino acid levels, despite there being no difference in intestinal structure and permeability. Depleting gut microbiota at the end of HFD rendered both strains more glucose tolerant but improved insulin sensitivity only in p66Shc-/- mice. Microbiota-depleted WT mice cohoused with microbiota-competent p66Shc-/- mice became significantly more insulin resistant than WT mice cohoused with WT mice, despite no difference in weight gain. These findings reconcile previous inconsistent observations on the metabolic phenotype of p66Shc-/- mice and illustrate the complex microbiome-host-genotype interplay under metabolic stress.-Ciciliot, S., Albiero, M., Campanaro, S., Poncina, N., Tedesco, S., Scattolini, V., Dalla Costa, F., Cignarella, A., Vettore, M., Di Gangi, I. M., Bogialli, S., Avogaro, A., Fadini, G. P. Interplay between gut microbiota and p66Shc affects obesity-associated insulin resistance.

Mitochondrial Calcium Uptake Is Instrumental to Alternative Macrophage Polarization and Phagocytic Activity.

Macrophages are highly plastic and dynamic cells that exert much of their function through phagocytosis. Phagocytosis depends on a coordinated, finely tuned, and compartmentalized regulation of calcium concentrations. We examined the role of mitochondrial calcium uptake and mitochondrial calcium uniporter (MCU) in macrophage polarization and function. In primary cultures of human monocyte-derived macrophages, calcium uptake in mitochondria was instrumental for alternative (M2) macrophage polarization. Mitochondrial calcium uniporter inhibition with KB-R7943 or MCU knockdown, which prevented mitochondrial calcium uptake, reduced M2 polarization, while not affecting classical (M1) polarization. Challenging macrophages with E. coli fragments induced spikes of mitochondrial calcium concentrations, which were prevented by MCU inhibition or silencing. In addition, mitochondria remodelled in M2 macrophages during phagocytosis, especially close to sites of E. coli internalization. Remarkably, inhibition or knockdown of MCU significantly reduced the phagocytic capacity of M2 macrophages. KB-R7943, which also inhibits the membrane sodium/calcium exchanger and Complex I, reduced mitochondria energization and cellular ATP levels, but such effects were not observed with MCU silencing. Therefore, phagocytosis inhibition by MCU knockdown depended on the impaired mitochondrial calcium buffering rather than changes in mitochondrial and cellular energy status. These data uncover a new role for MCU in alternative macrophage polarization and phagocytic activity.

Bisdemethoxycurcumin and Its Cyclized Pyrazole Analogue Differentially Disrupt Lipopolysaccharide Signalling in Human Monocyte-Derived Macrophages.

Several studies suggest that curcumin and related compounds possess antioxidant and anti-inflammatory properties including modulation of lipopolysaccharide- (LPS-) mediated signalling in macrophage cell models. We here investigated the effects of curcumin and the two structurally unrelated analogues GG6 and GG9 in primary human blood-derived macrophages as well as the signalling pathways involved. Macrophages differentiated from peripheral blood monocytes for 7 days were activated with LPS or selective Toll-like receptor agonists for 24 h. The effects of test compounds on cytokine production and immunophenotypes evaluated as CD80+/CCR2+ and CD206+/CD163+ subsets were examined by ELISA and flow cytometry. Signalling pathways were probed by Western blot. Curcumin (2.5-10 µM) failed to suppress LPS-induced inflammatory responses. While GG6 reduced LPS-induced IκB-α degradation and showed a trend towards reduced interleukin-1ß release, GG9 prevented the increase in proinflammatory CD80+ macrophage subset, downregulation of the anti-inflammatory CD206+/CD163+ subset, increase in p38 phosphorylation, and increase in cell-bound and secreted interleukin-1ß stimulated by LPS, at least in part through signalling pathways not involving Toll-like receptor 4 and nuclear factor-κB. Thus, the curcumin analogue GG9 attenuated the LPS-induced inflammatory response in human blood-derived macrophages and may therefore represent an attractive chemical template for macrophage pharmacological targeting.

Estrogen, Angiogenesis, Immunity and Cell Metabolism: Solving the Puzzle.

Estrogen plays an important role in the regulation of cardiovascular physiology and the immune system by inducing direct effects on multiple cell types including immune and vascular cells. Sex steroid hormones are implicated in cardiovascular protection, including endothelial healing in case of arterial injury and collateral vessel formation in ischemic tissue. Estrogen can exert potent modulation effects at all levels of the innate and adaptive immune systems. Their action is mediated by interaction with classical estrogen receptors (ERs), ERα and ERß, as well as the more recently identified G-protein coupled receptor 30/G-protein estrogen receptor 1 (GPER1), via both genomic and non-genomic mechanisms. Emerging data from the literature suggest that estrogen deficiency in menopause is associated with an increased potential for an unresolved inflammatory status. In this review, we provide an overview through the puzzle pieces of how 17ß-estradiol can influence the cardiovascular and immune systems.

The Glycolytic Enzyme PFKFB3 Is Involved in Estrogen-Mediated Angiogenesis via GPER1.

The endogenous estrogen 17ß-estradiol (E2) is a key factor in promoting endothelial healing and angiogenesis. Recently, proangiogenic signals including vascular endothelial growth factor and others have been shown to converge in endothelial cell metabolism. Because inhibition of the glycolytic enzyme activator phosphofructokinase-2/fructose-2,6-bisphosphatase 3 (PFKFB3) reduces pathologic angiogenesis and estrogen receptor (ER) signaling stimulates glucose uptake and glycolysis by inducing PFKFB3 in breast cancer, we hypothesized that E2 triggers angiogenesis in endothelial cells via rapid ER signaling that requires PFKFB3 as a downstream effector. We report that treatment with the selective G protein-coupled estrogen receptor (GPER1) agonist G-1 (10-10 to 10-7 M) mimicked the chemotactic and proangiogenic effect of E2 as measured in a number of short-term angiogenesis assays in human umbilical vein endothelial cells (HUVECs); in addition, E2 treatment upregulated PFKFB3 expression in a time- and concentration-dependent manner. Such an effect peaked at 3 hours and was also induced by G-1 and abolished by pretreatment with the GPER1 antagonist G-15 or GPER1 siRNA, consistent with engagement of membrane ER. Experiments with the PFKFB3 inhibitor 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one showed that PFKFB3 activity was required for estrogen-mediated HUVEC migration via GPER1. In conclusion, E2-induced angiogenesis was mediated at least in part by the membrane GPER1 and required upregulation of the glycolytic activator PFKFB3 in HUVECs. These findings unravel a previously unrecognized mechanism of estrogen-dependent endocrine-metabolic crosstalk in HUVECs and may have implications in angiogenesis occurring in ischemic or hypoxic tissues.

Upregulation of inducible NO synthase by exogenous adenosine in vascular smooth muscle cells activated by inflammatory stimuli in experimental diabetes.

BACKGROUND: Adenosine has been shown to induce nitric oxide (NO) production via inducible NO synthase (iNOS) activation in vascular smooth muscle cells (VSMCs). Although this is interpreted as a beneficial vasodilating pathway in vaso-occlusive disorders, iNOS is also involved in diabetic vascular dysfunction. Because the turnover of and the potential to modulate iNOS by adenosine in experimental diabetes have not been explored, we hypothesized that both the adenosine system and control of iNOS function are impaired in VSMCs from streptozotocin-diabetic rats. METHODS: Male Sprague-Dawley rats were injected with streptozotocin once to induce diabetes. Aortic VSMCs from diabetic and nondiabetic rats were isolated, cultured and exposed to lipopolysaccharide (LPS) plus a cytokine mix for 24 h in the presence or absence of (1) exogenous adenosine and related compounds, and/or (2) pharmacological agents affecting adenosine turnover. iNOS functional expression was determined by immunoblotting and NO metabolite assays. Concentrations of adenosine, related compounds and metabolites thereof were assayed by HPLC. Vasomotor responses to adenosine were determined in endothelium-deprived aortic rings. RESULTS: Treatment with adenosine-degrading enzymes or receptor antagonists increased iNOS formation in activated VSMCs from nondiabetic and diabetic rats. Following treatment with the adenosine transport inhibitor NBTI, iNOS levels increased in nondiabetic but decreased in diabetic VSMCs. The amount of secreted NO metabolites was uncoupled from iNOS levels in diabetic VSMCs. Addition of high concentrations of adenosine and its precursors or analogues enhanced iNOS formation solely in diabetic VSMCs. Exogenous adenosine and AMP were completely removed from the culture medium and converted into metabolites. A tendency towards elevated inosine generation was observed in diabetic VSMCs, which were also less sensitive to CD73 inhibition, but inosine supplementation did not affect iNOS levels. Pharmacological inhibition of NOS abolished adenosine-induced vasorelaxation in aortic tissues from diabetic but not nondiabetic animals. CONCLUSIONS: Endogenous adenosine prevented cytokine- and LPS-induced iNOS activation in VSMCs. By contrast, supplementation with adenosine and its precursors or analogues enhanced iNOS levels in diabetic VSMCs. This effect was associated with alterations in exogenous adenosine turnover. Thus, overactivation of the adenosine system may foster iNOS-mediated diabetic vascular dysfunction.

Macrophage function and polarization in cardiovascular disease: a role of estrogen signaling?

Macrophages are plastic and versatile cells adapting their function/phenotype to the microenvironment. Distinct macrophage subpopulations with different functions, including classically (M1) and (M2) activated macrophages, have been described. Reciprocal skewing of macrophage polarization between the M1 and M2 state is a process modulated by transcription factors, such as the nuclear peroxisome proliferator-activated receptors. However, whether the estrogen/estrogen receptor pathways control the balance between M1/M2 macrophages is only partially understood. Estrogen-dependent effects on the macrophage system may be regarded as potential targets of pharmacological approaches to protect postmenopausal women from the elevated risk of cardiovascular disease.

Sex and sex steroids as determinants of cardiovascular risk.

There are considerable sex differences regarding the risk of cardiovascular disease (CVD), including arterial hypertension, coronary artery disease (CAD) and stroke, as well as chronic renal disease. Women are largely protected from these conditions prior to menopause, and the risk increases following cessation of endogenous estrogen production or after surgical menopause. Cardiovascular diseases in women generally begin to occur at a later age than in men (on average with a delay of 10 years). Cessation of estrogen production also impacts metabolism, increasing the risk of developing obesity and diabetes. In middle-aged individuals, hypertension develops earlier and faster in women than in men, and smoking increases cardiovascular risk to a greater degree in women than it does in men. It is not only estrogen that affects female cardiovascular health and plays a protective role until menopause: other sex hormones such as progesterone and androgen hormones generate a complex balance that differentiates heart and blood vessel function in women compared to men. Estrogens improve vasodilation of epicardial coronary arteries and the coronary microvasculature by augmenting the release of vasodilating factors such as nitric oxide and prostacyclin, which are mechanisms of coronary vasodilatation that are more pronounced in women compared to men. Estrogens are also powerful inhibitors of inflammation, which in part explains their protective effects on CVD and chronic renal disease. Emerging evidence suggests that sex chromosomes also play a significant role in shaping cardiovascular risk. The cardiovascular protection conferred by endogenous estrogens may be extended by hormone therapy, especially using bioidentical hormones and starting treatment early after menopause.