Serum matrix metalloproteinase-2 as a predictor of level of hypoxemia and severity of obstructive sleep apnea.

PURPOSE: Intermittent hypoxia in obstructive sleep apnea (OSA) resembles ischemia/reperfusion. Oxidative stress during ischemia/reperfusion increases matrix metalloproteinase-2 (MMP-2) activity and leads to adverse cardiovascular consequences in animal models, but there is scarce information about MMP-2 in humans with OSA. The aim of this study was to determine if serum MMP-2 levels of patients with OSA differ from controls and if MMP-2 activity correlates with the severity of OSA and level of hypoxemia. METHODS: Patients with OSA (n = 124) were recruited from the Sleep Disorders Center (Saskatoon City Hospital, Canada) after in-lab polysomnography (PSG). Controls (n = 26) were subjects referred for PSG who did not have OSA. Severity of OSA was categorized according to American Academy of Sleep Medicine criteria. Level of hypoxemia was expressed as oxygen desaturation index (ODI; 3% desaturation). Gelatin zymography was performed to measure serum MMP-2 activity. RESULTS: Serum MMP-2 activity was significantly higher in patients with OSA than in controls (p = 0.029). MMP-2 activity in patients with severe OSA was significantly higher than in those with mild/moderate OSA and controls (p = 0.002). Linear regression showed positive associations with MMP-2 activity in serum for AHI (p < 0.001) and ODI (p = 0.003). The associations persisted after adjustment for multiple confounders, including age, sex, BMI, and cardiovascular disease. CONCLUSIONS: Serum MMP-2 activity was associated with OSA severity, and level of hypoxemia in patients with OSA, suggesting MMP-2 is worth considering as a potential biomarker to be included in future studies on sets of biomarkers for hypoxemic insult in OSA.

Protection of the transplant kidney during cold perfusion with doxycycline: proteomic analysis in a rat model.

BACKGROUND: It has been previously shown that doxycycline (Doxy) protects the kidney from preservation injury by inhibition of matrix metalloproteinase. However, the precise molecular mechanism involved in this protection from injury is not known. We used a pharmaco-proteomics approach to identify potential molecular targets associated with kidney preservation injury. METHODS: Rat kidneys were cold perfused with or without doxycycline (Doxy) for 22 h. Kidneys perfusates were analyzed for the presence of injury markers such as lactate dehydrogenase (LDH), and neutrophil-gelatinase associated lipocalin (NGAL). Proteins extracted from kidney tissue were analyzed by 2-dimensional gel electrophoresis. Proteins of interest were identified by mass spectrometry. RESULTS: Triosephosphate isomerase, PGM, dihydropteridine reductase-2, pyridine nucleotide-disulfide oxidoreductase, phosphotriesterase-related protein, and aminoacylase-1A were not affected by cold perfusion. Perfusion with Doxy increased their levels. N(G),N(G)-dimethylarginine dimethylaminohydrolase and phosphoglycerate kinase 1 were decreased after cold perfusion. Perfusion with Doxy led to an increase in their levels. CONCLUSIONS: This study revealed specific metabolic enzymes involved in preservation injury and in the mechanism whereby Doxy protects the kidney against injury during cold perfusion.

Intravoxel incoherent motion magnetic resonance imaging: basic principles and clinical applications.

The purpose of this article was to show basic principles, acquisition, advantages, disadvantages, and clinical applications of intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI). IVIM MRI as a method was introduced in the late 1980s, but recently it started attracting more interest thanks to its applications in many fields, particularly in oncology and neuroradiology. This imaging technique has been developed with the objective of obtaining not only a functional analysis of different organs but also different types of lesions. Among many accessible tools in diagnostic imaging, IVIM MRI aroused the interest of many researchers in terms of studying its applicability in the evaluation of abdominal organs and diseases. The major conclusion of this article is that IVIM MRI seems to be a very auspicious method to investigate the human body, and that nowadays the most promising clinical application for IVIM perfusion MRI is oncology. However, due to lack of standardisation of image acquisition and analysis, further studies are needed to validate this method in clinical practice.

Cardioprotective effect of MMP-2-inhibitor-NO-donor hybrid against ischaemia/reperfusion injury.

Hypoxic injury of cardiovascular system is one of the most frequent complications following ischaemia. Heart injury arises from increased degradation of contractile proteins, such as myosin light chains (MLCs) and troponin I by matrix metalloproteinase 2 (MMP-2). The aim of the current research was to study the effects of 5-phenyloxyphenyl-5-aminoalkyl nitrate barbiturate (MMP-2-inhibitor-NO-donor hybrid) on hearts subjected to ischaemia/reperfusion (I/R) injury. Primary human cardiac myocytes and Wistar rat hearts perfused using Langendorff method have been used. Human cardiomyocytes or rat hearts were subjected to I/R in the presence or absence of tested hybrid. Haemodynamic parameters of heart function, markers of I/R injury, gene and protein expression of MMP-2, MMP-9, inducible form of NOS (iNOS), asymmetric dimethylarginine (ADMA), as well as MMP-2 activity were measured. Mechanical heart function, coronary flow (CF) and heart rate (HR) were decreased in hearts subjected to I/R Treatment of hearts with the hybrid (1-10 µmol/L) resulted in a concentration-dependent recovery of mechanical function, improved CF and HR. This improvement was associated with decreased tissue injury and reduction of synthesis and activity of MMP-2. Decreased activity of intracellular MMP-2 led to reduced degradation of MLC and improved myocyte contractility in a concentration-dependent manner. An infusion of a MMP-2-inhibitor-NO-donor hybrid into I/R hearts decreased the expression of iNOS and reduced the levels of ADMA. Thus, 5-phenyloxyphenyl-5-aminoalkyl nitrate barbiturate protects heart from I/R injury.

Association between FTO gene polymorphisms and HDL cholesterol concentration may cause higher risk of cardiovascular disease in patients with acromegaly.

INTRODUCTION: Cardiovascular diseases are main cause of morbidity and mortality in acromegaly. Polymorphisms of FTO gene are associated with obesity and increased risk of CVD (independently of BMI). Aim of this study was to investigate the allele frequencies of two FTO gene polymorphisms: rs9939609 and rs9930506 in patients with acromegaly and to examine the association of FTO gene polymorphisms with BMI and selected metabolic parameters. MATERIALS AND METHODS: Identification of two single nucleotide polymorphisms of FTO gene was carried out in 51 patients with acromegaly using the minisequencing method. RESULTS: The risk-allele frequencies of rs9939609 and rs9930506 polymorphisms were 0.471 and 0.529, respectively and they were higher than in general European population. There is no association of FTO gene polymorphisms with BMI, glucose, total cholesterol, LDL cholesterol and triglyceride. The risk alleles were associated with decreased HDL cholesterol concentration. Homozygotes for the rs9939609-risk allele had 1.25-fold lower HDL cholesterol concentration than carriers of the TT genotype (p = 0.0024). The estimated average decrease in HDL cholesterol concentration per risk allele for rs9930506 was 11.2%. Nevertheless, statistically significant differences were observed only between AG versus GG and AA versus GG genotypes. Homozygotes for the rs9930506-risk allele had 1.27-fold lower HDL cholesterol concentration than carriers of the AA genotype (p = 0.007). CONCLUSION: The risk-allele frequencies of studied polymorphisms in acromegaly were higher than in general European population. There is an association between FTO gene polymorphisms and HDL cholesterol concentration, suggesting FTO gene polymorphisms may be associated with higher CVD risk in patients with acromegaly.

Inhibition of platelet aggregation by activation of platelet intermediate conductance Ca2+ -activated potassium channels.

BACKGROUND: Within the vasculature platelets and endothelial cells play crucial roles in hemostasis and thrombosis. Platelets, like endothelial cells, possess intermediate conductance Ca2+ -activated K+ (IKCa ) channels and generate nitric oxide (NO). Although NO limits platelet aggregation, the role of IKCa channels in platelet function and NO generation has not yet been explored. OBJECTIVES: We investigated whether IKCa channel activation inhibits platelet aggregation, and per endothelial cells, enhances platelet NO production. METHODS: Platelets were isolated from human volunteers. Aggregometry, confocal microscopy, and a novel flow chamber model, the Quartz Crystal Microbalance (QCM) were used to assess platelet function. Flow cytometry was used to measure platelet NO production, calcium signaling, membrane potential, integrin αIIb /ß3 activation, granule release, and procoagulant platelet formation. RESULTS: Platelet IKCa channel activation with SKA-31 inhibited aggregation in a concentration-dependent manner, an effect reversed by the selective IKCa channel blocker TRAM-34. The QCM model along with confocal microscopy demonstrated that SKA-31 inhibited platelet aggregation under flow conditions. Surprisingly, IKCa activation by SKA-31 inhibited platelet NO generation, but this could be explained by a concomitant reduction in platelet calcium signaling. IKCa activation by SKA-31 also inhibited dense and alpha-granule secretion and integrin αIIb /ß3 activation, but maintained platelet phosphatidylserine surface exposure as a measure of procoagulant response. CONCLUSIONS: Platelet IKCa channel activation inhibits aggregation by reducing calcium-signaling and granule secretion, but not by enhancing platelet NO generation. IKCa channels may be novel targets for the development of antiplatelet drugs that limit atherothrombosis, but not coagulation.

The Association of Matrix Metalloproteinases With Acute Kidney Injury Following CPB-Supported Cardiac Surgery.

BACKGROUND: Cardiac surgery-associated acute kidney injury (AKI) is an adverse outcome that increases morbidity and mortality in patients undergoing cardiac surgical procedures. To date, the use of serum creatinine levels as an early indicator of AKI has limitations because of its slow rise and poor predictive accuracy for renal injury. This delay in diagnosis may lead to prolonged initiation in treatment and increased risk for adverse outcomes. OBJECTIVE: This pilot study explores serum and urine matrix metalloproteinases (MMPs)-2 and MMP-9 and their association, and potentially earlier detection of AKI in patients following cardiopulmonary bypass (CPB)-supported cardiac surgery. We hypothesize that increased activity of serum and urine levels MMP-2 and/ or MMP-9 are associated with AKI. Furthermore, MMP-2 and/ or MMP-9 may provide earlier identification of AKI as compared with serum levels of creatinine. METHODS: During the study period, there were 150 CPB-supported surgeries, 21 of which developed AKI according to the Kidney Disease Improving Global Outcomes criteria. We then selected a sample of 21 matched cases from those patients who went through the surgery without developing AKI. Primary outcomes were the measurement via gel zymography of the serum and urine activity of MMP-2 and MMP-9 drawn at the following intervals: pre-CPB; 10-minute post-CPB; and 4-hour post-CPB time points. Secondary variables were the measurement of serum creatinine, intensive care unit (ICU) fluid balance, and length of ICU stay. RESULTS: At the 10-minute and 4-hour post-CPB time points, the serum MMP-2 activity of AKI patients were significantly higher as compared with non-AKI patients (P < .001 and P = .004), respectively. Similarly, at the 10-minute and 4-hour post-CPB time points, the serum MMP-9 activity of AKI patients was significantly higher as compared with non-AKI patients (P = .001 and P = .014), respectively. The activity of urine MMP-2 and MMP-9 of AKI patients was significantly higher as compared with non-AKI patients at all 3 time points (P = .004, P < .001, P < .001), respectively. CONCLUSION: Although the pilot study may have limitations, it has demonstrated that the serum and urine levels of activity of MMP-2 and MMP-9 are associated with the clinical endpoint of AKI and appear to have earlier rising levels as compared with those of serum creatinine. Furthermore, in depth, exploration is underway with a larger sample size to attempt validation of the analytical performance and reproducibility of the assay for MMP-2 and MMP-9 to aid in earlier diagnosis of AKI following CPB-supported cardiac surgery.

CONTEXTE: L'insuffisance rénale aiguë (IRA) associée à la chirurgie cardiaque est un effet indésirable qui augmente la morbidité et la mortalité des patients qui subissent ce type d'intervention. La mesure de la créatinine sérique comme indicateur précoce de l'IRA continue à ce jour de présenter des limites en raison de sa lente augmentation et de l'imprécision de son pouvoir prédictif. Ce délai dans le diagnostic peut retarder l'initiation du traitement et accroître le risque d'effets indésirables. OBJECTIFS: Cette étude pilote explore les métalloprotéinases matricielles (MPM) -2 et -9 sériques et urinaires, leur association avec l'IRA et leur potentiel pour la détection plus précoce de la maladie chez les patients qui subissent une chirurgie cardiaque assistée par circulation extracorporelle. Nous émettons l'hypothèse qu'une hausse de l'activité des MMP-2 et/ou -9 et de leurs taux sériques et urinaires serait associée à l'IRA. Les MMP-2 et/ou -9 pourraient en outre permettre d'identifier la maladie plus précocement que le taux de créatinine sérique. MÉTHODOLOGIE: Au cours de la période de l'étude, 150 chirurgies cardiaques assistées par circulation extracorporelle ont été effectuées et 21 ont été associées à une IRA telle que définie par les critères du KDIGO (Kidney Disease Improving Global Outcomes). Nous avons sélectionné 21 cas appariés parmi les patients ayant subi l'intervention sans développer d'IRA. Le principal critère d'évaluation était une mesure de l'activité des MMP-2 et -9 obtenue par une zymographie sur gel d'échantillons de sérum et d'urine prélevés aux intervalles suivants: pré-circulation extracorporelle, 10 minutes après la circulation extracorporelle et 4 heures après la circulation extracorporelle. Les variables secondaires étaient la mesure de la créatinine sérique, la mesure de la balance liquidienne durant le séjour à l'unité de soins intensifs (USI) et de la durée du séjour à l'USI. RÉSULTATS: L'activité des MMP-2 sériques des patients atteints d'IRA était significativement plus élevée que celle des patients non atteints d'IRA 10 minutes et 4 heures post-circulation extracorporelle (p < 0,001 et p = 0,004 respectivement). Aux mêmes repères temporels, l'activité des MMP-9 sériques était elle aussi significativement plus élevée chez les patients atteints d'IRA (p = 0,001 [IRA]; p = 0,014 (non IRA). L'activité des MMP-2 et -9 urinaires, elle était elle aussi significativement plus élevée pour les patients atteints d'IRA, et ce, pour les trois points temporels (p = 0,004 [IRA); p < 0,001 [non IRA]). CONCLUSION: Bien que cette étude pilote comporte des limites, elle a tout de même démontré que l'activité des MMP-2 et -9 sériques et urinaires est associée aux paramètres cliniques de l'IRA, et que leurs taux augmentent plus rapidement que les taux de créatinine sérique. Des recherches plus approfondies sur un plus grand échantillon de patients sont en cours afin de valider la performance analytique et la reproductibilité du dosage des MMP-2 et -9 pour diagnostiquer plus rapidement l'IRA après une chirurgie cardiaque assistée par circulation extracorporelle.

Mixture of MMP-2, MLC, and NOS Inhibitors Affects NO Metabolism and Protects Heart from Cardiac I/R Injury.

OBJECTIVES: Coronary reperfusion procedure leads to ischemia/reperfusion injury of the heart (IRI). IRI arises from increased degradation of myosin light chains and increased activity of matrix metalloproteinase 2 (MMP-2). Increased production of toxic peroxynitrite (ONOO-) during oxidative stress is a source of increased nitration/nitrosylation of contractile proteins, which enhance their degradation through MMP-2. Hence, an imbalance in nitric oxide (NO) metabolism along with oxidative stress is an important factor contributing to pathophysiology of cardiovascular disorders, including myocardial infarction. The aim of the current study was to provide an important insight into understanding the interaction of iNOS, eNOS, and ADMA during oxidative stress and to propose the beneficial therapy to modulate this interaction. Material and Methods. Pathogen-free Wistar rats were used in this study as a surrogate heart model ex vivo. Rat hearts perfused using the Langendorff method were subjected to global no-flow ischemia with or without administration of DOXY (1 µM), ML-7 (0.5 µM), and L-NAME (2 µM) mixture. Haemodynamic parameters of heart function, markers of I/R injury, tissue expression of iNOS, eNOS, and phospho-eNOS, asymmetric dimethylarginine, and NO production as well as MMP-2 activity were measured. RESULTS: Mechanical heart function and coronary flow (CF) were decreased in the hearts subjected to I/R. Treatment of the hearts with the tested mixture resulted in a recovery of mechanical function due to decreased activity of MMP-2. An infusion of Doxy, ML-7, and L-NAME mixture into I/R hearts decreased the expression of iNOS, eNOS, and phospho-eNOS and in consequence reduced ADMA expression. Decreased ADMA production led to enhanced NO synthesis and improvement of cardiac function at 85% of aerobic control. CONCLUSIONS: Synergistic effect of the multidrug therapy with the subthreshold doses allows addressing a few pathways of I/R injury simultaneously to achieve protection of cardiac function during I/R.

Corrigendum to "The Biological Role of Klotho Protein in the Development of Cardiovascular Diseases".

[This corrects the article DOI: 10.1155/2018/5171945.].

Matrix metalloproteinases as possible biomarkers of obstructive sleep apnea severity - A systematic review.

Obstructive sleep apnea is an underdiagnosed sleep-related breathing disorder affecting millions of people. Recurrent episodes of apnea/hypopnea result in intermittent hypoxia leading to oxidative stress. Obstructive sleep apnea is considered an independent risk factor for cardiovascular disease but the exact pathophysiology of adverse cardiovascular outcomes of obstructive sleep apnea has not been fully elucidated. Matrix metalloproteinases (MMPs) have been associated with both oxidative stress and cardiovascular diseases. Hypoxic conditions were shown to influence MMP expression, secretion and activity. Moreover, matrix metalloproteinases contribute to ischemia/reperfusion injury. Therefore, action of matrix metalloproteinases can provide a possible molecular mechanism linking obstructive sleep apnea with oxidative stress and cardiovascular disease. The aim of this paper was to review the current evidence of association between matrix metalloproteinases and obstructive sleep apnea with focus on hypoxemia and severity of obstructive sleep apnea.

Pharmacological Protection of Kidney Grafts from Cold Perfusion-Induced Injury.

One of the greatest challenges facing the field of organ transplantation is the shortage of donor organs for transplantation. Renal transplantation increases quality of life and survival of patients suffering from end-stage renal disease. Although kidney transplantation has evolved greatly over the past few decades, a not insignificant amount of injury occurs to the kidney during recovery, preservation, and implantation and leads to the loss of function and loss of years of dialysis-free living for many patients. The use of kidneys from expanded criteria donors (ECD) and donation after circulatory determination of death (DCDD) has been adopted partly in response to the shortage of donor kidneys; however these kidneys are even more susceptible to ischemic injury. It has been shown that matrix metalloproteinases (MMPs) and reactive oxygen species (ROS) are involved in mechanisms of injury to the transplant kidney. There is also some evidence that inhibition of MMP activity and/or ROS production can protect the kidney from injury. We review possible pharmacological strategies for protection of kidney graft from injury during recovery, preservation, and implantation.

The Biological Role of Klotho Protein in the Development of Cardiovascular Diseases.

Klotho is a membrane-bound or soluble antiaging protein, whose protective activity is essential for a proper function of many organs. In 1997, an accidental insertion of a transgene led to creation of transgenic mice with several age-related disorders. In Klotho-deficient mice, the inherited phenotypes closely resemble human aging, while in an animal model of Klotho overexpression, the lifespan is extended. Klotho protein is detected mainly in the kidneys and brain. It is a coreceptor for fibroblast growth factor and hence is involved in maintaining endocrine system homeostasis. Furthermore, an inhibition of insulin/insulin-like growth factor-1 signaling pathway by Klotho regulates oxidative stress and reduces cell death. The association between serum Klotho and the classic risk factors, as well as the clinical history of cardiovascular disease, was also shown. There are a lot of evidences that Klotho deficiency correlates with the occurrence and development of coronary artery disease, atherosclerosis, myocardial infarction, and left ventricular hypertrophy. Therefore, an involvement of Klotho in the signaling pathways and in regulation of a proper cell metabolism could be a crucial factor in the cardiac and vascular protection. It is also well established that Klotho protein enhances the antioxidative response via augmented production of superoxide dismutase and reduced generation of reactive oxygen species. Recent studies have proven an expression of Klotho in cardiomyocytes and its increased expression in stress-related heart injury. Thus, the antioxidative and antiapoptotic activity of Klotho could be considered as the novel protective factor in cardiovascular disease and heart injury.

Multidrug prevention or therapy of ischemia-reperfusion injury of the heart-Mini-review.

Restoration of blood flow to myocardium previously subjected to ischemia leads to ischemia/reperfusion injury due to oxidative stress. An increased production of toxic peroxynitrite, an enhanced phosphorylation and nitration/nitrosylation of myocyte contractile proteins and overactivation of matrix metalloproteinases -are only one of the several causes of heart damage. Multifactorial basis of ischemia/reperfusion injury demands the use of multiple pharmacological agents, inhibiting several pathways of cardiac injury. Nevertheless, the use of these drugs in their therapeutic doses, apart from their role in the treatment of pathological events, may also disturb physiological processes leading to numerous side-effects. Therefore current preclinical studies focuses on multidrug therapies in their low concentration. Synergistic or additive effect of low multidrug therapy inhibit pathological processes while maintaining the proper cell function and avoid alteration of physiological role of important functional proteins. This study provides information about multidrug strategies for the prevention/treatment of cardiac injury induced by oxidative stress.