Plasma levels of the proprotein convertase furin and incidence of diabetes and mortality

Background. Diabetes mellitus is linked to premature mortality of virtually all causes. Furin is a proprotein convertase broadly involved in the maintenance of cellular homeostasis; however, little is known about its role in the development of diabetes mellitus and risk of premature mortality. Objectives. To test if fasting plasma concentration of furin is associated with the development of diabetes mellitus and mortality. Methods. Overnight fasted plasma furin levels were measured at baseline examination in 4678 individuals from the population-based prospective Malmo Diet and Cancer Study. We studied the relation of plasma furin levels with metabolic and hemodynamic traits. We used multivariable Cox proportional hazards models to investigate the association between baseline plasma furin levels and incidence of diabetes mellitus and mortality during 21.3-21.7 years follow-up. Results. An association was observed between quartiles of furin concentration at baseline and body mass index, blood pressure and plasma concentration of glucose, insulin, LDL and HDL cholesterol (vertical bar 0.11 vertical bar Conclusion. Individuals with high plasma furin concentration have a pronounced dysmetabolic phenotype and elevated risk of diabetes mellitus and premature mortality.Peer reviewe

Cardiac Actions of a Small Molecule Inhibitor Targeting GATA4–NKX2-5 Interaction

Transcription factors are fundamental regulators of gene transcription, and many diseases, such as heart diseases, are associated with deregulation of transcriptional networks. In the adult heart, zinc-finger transcription factor GATA4 is a critical regulator of cardiac repair and remodelling. Previous studies also suggest that NKX2-5 plays function role as a cofactor of GATA4. We have recently reported the identification of small molecules that either inhibit or enhance the GATA4–NKX2-5 transcriptional synergy. Here, we examined the cardiac actions of a potent inhibitor (3i-1000) of GATA4–NKX2-5 interaction in experimental models of myocardial ischemic injury and pressure overload. In mice after myocardial infarction, 3i-1000 significantly improved left ventricular ejection fraction and fractional shortening, and attenuated myocardial structural changes. The compound also improved cardiac function in an experimental model of angiotensin II -mediated hypertension in rats. Furthermore, the up-regulation of cardiac gene expression induced by myocardial infarction and ischemia reduced with treatment of 3i-1000 or when micro- and nanoparticles loaded with 3i-1000 were injected intramyocardially or intravenously, respectively. The compound inhibited stretch- and phenylephrine-induced hypertrophic response in neonatal rat cardiomyocytes. These results indicate significant potential for small molecules targeting GATA4–NKX2-5 interaction to promote myocardial repair after myocardial infarction and other cardiac injuries.Peer reviewe

Cardiac Actions of a Small Molecule Inhibitor Targeting GATA4-NKX2-5 Interaction

Transcription factors are fundamental regulators of gene transcription, and many diseases, such as heart diseases, are associated with deregulation of transcriptional networks. In the adult heart, zinc-finger transcription factor GATA4 is a critical regulator of cardiac repair and remodelling. Previous studies also suggest that NKX2-5 plays function role as a cofactor of GATA4. We have recently reported the identification of small molecules that either inhibit or enhance the GATA4-NKX2-5 transcriptional synergy. Here, we examined the cardiac actions of a potent inhibitor (3i-1000) of GATA4-NKX2-5 interaction in experimental models of myocardial ischemic injury and pressure overload. In mice after myocardial infarction, 3i-1000 significantly improved left ventricular ejection fraction and fractional shortening, and attenuated myocardial structural changes. The compound also improved cardiac function in an experimental model of angiotensin II-mediated hypertension in rats. Furthermore, the up-regulation of cardiac gene expression induced by myocardial infarction and ischemia reduced with treatment of 3i-1000 or when micro-and nanoparticles loaded with 3i-1000 were injected intramyocardially or intravenously, respectively. The compound inhibited stretch- and phenylephrine-induced hypertrophic response in neonatal rat cardiomyocytes. These results indicate significant potential for small molecules targeting GATA4-NKX2-5 interaction to promote myocardial repair after myocardial infarction and other cardiac injuries

Gene expression profiling in experimental models of cardiac load

Abstract Cardiac hypertrophy provides an adaptive mechanism to maintain cardiac output in response to increased workload, and although initially beneficial, hypertrophy eventually leads to heart failure, a major cause of morbidity and mortality in Western countries. The hypertrophic response in cardiac myocytes is accompanied by e.g. activation of signal transduction pathways, such as mitogen-activated protein kinases (MAPKs), and complex changes in gene programming. The purpose of this study was to characterize gene expression patterns in experimental models of cardiac load by using high-throughput DNA microarray technologies. In the present study, changes in gene expression were evaluated in response to acute pressure overload and prolonged hypertension as well as during the development of left ventricular hypertrophy (LVH) and the transition to diastolic heart failure in an animal model of genetic hypertension, the spontaneously hypertensive rat (SHR). Increased expression of several immediate early genes was seen in response to acute hemodynamic overload in vivo. The transition from LVH to diastolic hypertensive heart failure was almost exclusively associated with changes in genes encoding extracellular matrix proteins and their regulatory processes showing the importance of progressive extracellular matrix remodeling. The effect of p38 MAPK activation on gene expression patterns in vivo was elucidated. Cardiac-specific overexpression of p38 MAPK resulted in upregulation of genes controlling cell division and inflammation as well as cell signaling and adhesion. Accordingly, the functional role of p38 MAPK was related to myocardial cell proliferation, inflammation and fibrosis. Finally, temporal analysis of mechanical stretch induced gene expression changes in neonatal rat cardiomyocyte cultures in vitro indicated that mechanical stretch induced complex gene expression profiles, demonstrating that both positive and negative regulators are involved in the hypertrophic process. Many novel stretch responsive genes were identified, and a subset of them may be putative downstream targets of p38 MAPK. In conclusion, in the present study a number of well-established gene expression changes of cardiac hypertrophy were observed and novel modulators associated with increased cardiac load, such as thrombospondin-4, were identified. The study provides a better understanding of molecular mechanisms associated with increased cardiac load, and may indicate potential targets for novel therapeutic interventions

Adverse outcome pathway for pregnane X receptor-induced hypercholesterolemia

Abstract Pharmaceuticals and environmental contaminants contribute to hypercholesterolemia. Several chemicals known to cause hypercholesterolemia, activate pregnane X receptor (PXR). PXR is a nuclear receptor, classically identified as a sensor of chemical environment and regulator of detoxification processes. Later, PXR activation has been shown to disrupt metabolic functions such as lipid metabolism and recent findings have shown PXR activation to promote hypercholesterolemia through multiple mechanisms. Hypercholesterolemia is a major causative risk factor for atherosclerosis and greatly promotes global health burden. Metabolic disruption by PXR activating chemicals leading to hypercholesterolemia represents a novel toxicity pathway of concern and requires further attention. Therefore, we constructed an adverse outcome pathway (AOP) by collecting the available knowledge considering the molecular mechanisms for PXR-mediated hypercholesterolemia. AOPs are tools of modern toxicology for systematizing mechanistic knowledge to assist health risk assessment of chemicals. AOPs are formalized and structured linear concepts describing a link between molecular initiating event (MIE) and adverse outcome (AO). MIE and AO are connected via key events (KE) through key event relationships (KER). We present a plausible route of how PXR activation (MIE) leads to hypercholesterolemia (AO) through direct regulation of cholesterol synthesis and via activation of sterol regulatory element binding protein 2-pathway

Tiatsididiureettien käyttö suurentaa luuntiheyttä ja pienentää murtumariskiä:järjestelmällinen kirjallisuuskatsaus ja meta-analyysi

Tiivistelmä Verenpainetaudin hoidossa käytettävät tiatsididiureetit estävät natriumin ja kloridin takaisinimeytymistä munuaisissa, jolloin natriumin, kloridin ja veden eritys virtsaan lisääntyy. Lisäksi tiatsidit vähentävät kalsiumin ja lisäävät kaliumin eritystä. Koska tiatsidit vähentävät kalsiumin eritystä, on pohdittu tiatsididiureettien suotuisaa vaikutusta luuntiheyteen ja murtumariskiin. Teimme järjestelmällisen kirjallisuuskatsauksen tiatsididiureettien vaikutuksesta luuntiheyteen ja murtumariskiin pohjautuen satunnaistettuihin ja kontrolloituihin lääketutkimuksiin. Lisäksi teimme meta-analyysin tiatsididiureettien vaikutuksesta murtumariskiin. Järjestelmällisen kirjallisuuskatsauksen perusteella tiatsididiureettien käyttäjillä luuntiheys on suurentunut verrattuna lähtötilaan tai lume-/kontrollilääkettä käyttäneisiin. Meta-analyysin perusteella tiatsidiryhmän lääkkeet pienensivät suhteellista murtumariskiä 25 prosenttia valtaosin iäkkäistä potilaista koostuneissa tutkimuksissa. Puolessa meta-analyysiin valituista tutkimuksista ei kuitenkaan käytetty Suomessa yleisimmin käytettyä hydroklooritiatsidia. Kirjallisuuskatsauksessa ja meta-analyysissä saatiin tukea oletukselle, että tiatsididiureettien käyttö suurentaa luuntiheyttä ja pienentää murtumariskiä. Verenpainetaudin hoidossa tiatsidit näyttäisivät tuovan iäkkäillä potilailla lisähyötyä murtumariskin pienenemisen muodossa. Tiatsidien tunnetut haittavaikutukset tulee huomioida hoitopäätöstä tehdessä. Koska tiatsidien murtumavaikutuksia selvittävät tutkimukset on tehty pääosin verenpainetautia sairastavilla, ei tiatsideja voida suositella normotensiivisten potilaiden murtumariskin pienentämiseen.Summary Thiazide diuretics increase bone mineral density and lower fracture risk : systematic review and meta-analysis Thiazide diuretics exert their antihypertensive effect by inhibiting the reabsorption of sodium and chloride in kidneys, leading to increases in urinary sodium, chloride and water excretion. In addition, thiazides decrease urinary calcium excretion while increasing that of potassium. Since thiazides reduce the excretion of calcium, it has been hypothesized that thiazides could exert a beneficial effect on bone mineral density and reduce the risk of fractures. We conducted a systematic review of randomized controlled trials to determine if thiazide diuretics have any beneficial effect on bone mineral density and the risk of fractures. We also performed a meta-analysis on the effect of thiazides on the risk of fractures. The systematic literature review demonstrated that the use of thiazides was associated with an increased bone mineral density. A 25% lower risk of fractures was demonstrated in the meta-analysis of the studies with mostly elderly patients. However, hydrochlorothiazide, the most widely used thiazide in Finland, was used only in half of the studies included in the meta-analysis. Thiazide diuretics are useful in the treatment of hypertension, and the lower fracture risk is an additional benefit in older patients. However, one should take into consideration the widely recognized adverse effect of thiazides before starting the treatment. Finally, since the studies reporting on thiazide use and hip fractures were conducted in hypertensive patients, the thiazides cannot be recommended to prevent fractures in normotensive individuals

Menaquinone 4 increases plasma lipid levels in hypercholesterolemic mice

Abstract In calcific aortic valve disease (CAVD) progressive valvular calcification causes aortic valve dysfunction. CAVD has several risk factors such as age and dyslipidemia. Vitamin K was shown to inhibit vascular calcification in mice and valvular calcification in patients with CAVD. We studied the effect of menaquinone 4 (MK4/vitamin K2) on valvular calcification in the hypercholesterolemic mouse model of CAVD. LDLr−/− ApoB100/100 male mice were fed with a Western diet for 5 months, with (n = 10) or without (n = 10) added 0.2 mg/g MK4. Body weight gain was followed weekly. Morphology of aortic valves and liver was assessed with immunohistochemistry. Plasma cholesterol levels and cytokines from hepatic tissue were assessed in the end of the study. Hepatic gene expression of lipid metabolism regulating genes were assessed after 18 h diet. MK4 exacerbated the lipoprotein lipid profile without affecting aortic valve morphology in hypercholesterolemic LDLr−/− ApoB100/100 mice. The MK4-containing WD diet increased plasma levels of LDL and triglycerides, hepatic steatosis, and mRNA expression of genes required for triglyceride and cholesterol synthesis. MK4 diminished levels of several cytokines and chemokines in liver, including IL-6, TNFα and MCP1, as measured by hepatic cytokine array. Consequently, MK4 may exert non-beneficial effects on circulating lipid levels, especially in hypercholesterolemic individuals

Nutritional status modifies pregnane X receptor regulated transcriptome

Abstract Pregnane X receptor (PXR) regulates glucose and lipid metabolism, but little is known of the nutritional regulation of PXR function. We investigated the genome wide effects of the nutritional status on the PXR mediated gene regulation in the liver. Mice were treated with a PXR ligand pregnenolone 16α-carbonitrile (PCN) for 4 days and subsequently either fasted for 5 hours or after 4-hour fast treated with intragastric glucose 1 hour before sample collection. Gene expression microarray study indicated that PCN both induced and repressed much higher number of genes in the glucose fed mice and the induction of multiple well-established PXR target genes was potentiated by glucose. A subset of genes, including bile acid synthesis gene Cyp8b1, responded in an opposite direction during fasting and after glucose feeding. PXR knockout abolished these effects. In agreement with the Cyp8b1 regulation, PCN also modified the bile acid composition in the glucose fed mice. Contribution of glucose, insulin and glucagon on the observed nutritional effects was investigated in primary hepatocytes. However, only mild impact on PXR function was observed. These results show that nutritional status modifies the PXR regulated transcriptome both qualitatively and quantitatively and reveal a complex crosstalk between PXR and energy homeostasis

Pregnane X receptor activator rifampin increases blood pressure and stimulates plasma renin activity

Abstract We conducted a clinical trial with 22 healthy volunteers to investigate the effects of pregnane X receptor (PXR) agonist rifampin on blood pressure (BP). The study was randomized, crossover, single‐blind, and placebo‐controlled. Rifampin 600 mg or placebo once daily was administered for a week and the 24‐hour ambulatory BP was monitored at the end of each arm on the eighth day. Rifampin elevated the mean systolic and diastolic 24‐hour BP (4.7 mmHg, P < 0.0001, and 3.0 mmHg, P < 0.001, respectively) as well as the mean heart rate (3.5 bpm, P = 0.038). The serum renin concentration and the plasma renin activity were increased. Although rifampin increased circulating 4β‐hydroxycholesterol (4βHC) as expected, the plasma 4βHC concentration strongly negatively correlated with 24‐hour BP, especially systolic, in both rifampin and placebo arms (rifampin systolic BP, r = −0.69, P < 0.001; placebo systolic BP, r = −0.70, P < 0.001). The 4βHC, an agonist for liver X receptor (LXR), induced renin expression modestly in LXR‐α expressing Calu‐6 cells but only at unphysiologically high 4βHC concentrations. In conclusion, rifampin stimulates renin activity and has a hypertensive effect. This finding should be considered when designing interaction studies involving rifampin or other PXR agonists. Furthermore, PXR may represent a putative therapeutic target for the treatment of hypertension

Rifampicin induces the bone form of alkaline phosphatase in humans

Abstract Pregnane X receptor (PXR) is a xenobiotic-sensing nuclear receptor that regulates drug metabolism in the liver and intestine. In our clinical trials on healthy volunteers to discover novel metabolic functions of PXR activation, we observed that rifampicin, a well-established ligand for human PXR, 600 mg daily for a week, increased the plasma alkaline phosphatase (ALP) significantly compared with the placebo. Further analysis with lectin affinity electrophoresis revealed that especially the bone form of ALP was elevated. To investigate the mechanism(s) of bone ALP induction, we employed osteoblast lineage differentiated from human primary bone marrow–derived mesenchymal stromal cells. Rifampicin treatment increased ALP activity and mRNA level of bone biomarker genes (ALP, MGP, OPN and OPG). PXR expression was detected in the cells, but the expression was very low compared with the human liver. To further investigate the potential role of PXR in the ALP induction, we treated mice and rats with a rodent PXR ligand pregnenolone 16α-carbonitrile (PCN). However, PCN treatment did not increase plasma ALP activity or bone ALP mRNA expression. In conclusion, rifampicin treatment induces the bone form of ALP in the serum of healthy human volunteers. Further studies are required to establish the mechanism of this novel finding