Increasing Tetrahydrobiopterin in Cardiomyocytes Adversely Affects Cardiac Redox State and Mitochondrial Function Independently of Changes in NO Production

Tetrahydrobiopterin (BH4) represents a potential strategy for the treatment of cardiac remodeling, fibrosis and/or diastolic dysfunction. The effects of oral treatment with BH4 (Sapropterin™ or Kuvan™) are however dose-limiting with high dose negating functional improvements. Cardiomyocyte-specific overexpression of GTP cyclohydrolase I (mGCH) increases BH4 several-fold in the heart. Using this model, we aimed to establish the cardiomyocyte-specific responses to high levels of BH4. Quantification of BH4 and BH2 in mGCH transgenic hearts showed age-based variations in BH4:BH2 ratios. Hearts of mice (\u3c6 \u3emonths) have lower BH4:BH2 ratios than hearts of older mice while both GTPCH activity and tissue ascorbate levels were higher in hearts of young than older mice. No evident changes in nitric oxide (NO) production assessed by nitrite and endogenous iron–nitrosyl complexes were detected in any of the age groups. Increased BH4 production in cardiomyocytes resulted in a significant loss of mitochondrial function. Diminished oxygen consumption and reserve capacity was verified in mitochondria isolated from hearts of 12-month old compared to 3-month old mice, even though at 12 months an improved BH4:BH2 ratio is established. Accumulation of 4-hydroxynonenal (4-HNE) and decreased glutathione levels were found in the mGCH hearts and isolated mitochondria. Taken together, our results indicate that the ratio of BH4:BH2 does not predict changes in neither NO levels nor cellular redox state in the heart. The BH4 oxidation essentially limits the capacity of cardiomyocytes to reduce oxidant stress. Cardiomyocyte with chronically high levels of BH4 show a significant decline in redox state and mitochondrial function

ПОВЫШЕНИЕ УРОВНЯ ПРОВОСПАЛИТЕЛЬНЫХ ЦИТОКИНОВ В ПЛАЗМЕ КРОВИ У ПАЦИЕНТОВ С ХРОНИЧЕСКОЙ ТРОМБОЭМБОЛИЧЕСКОЙ ЛЕГОЧНОЙ ГИПЕРТЕНЗИЕЙ

HighlightsIL-8 and MCP-1 have a significant role in the CTEPH pathogenesis, which indicates the importance of nonspecific immunity in the formation and progression of CTEPH. The coupling between cytokines and hemodynamic parameters, cardiac structural changes and plasma biochemical parameters were determined. AbstractBackground. Chronic thromboembolic pulmonary hypertension (CTEPH) pathogenesis is complex and not fully understood. Particular attention to the microvascular damage genesis in CTEPH is given to aseptic inflammation, which in turn could be mediated through various molecular mechanisms. According to the conflicting and incomplete data on changes in the profile of factors controlling inflammation in CTEPH, research in this field would identify new therapeutic targets for the prevention and treatment of CTEPH.Aim. To study the profile of plasma proinflammatory cytokines in patients with chronic thromboembolic pulmonary hypertension (CTEPH) and evaluate the coupling of these cytokines with the main morphofunctional and laboratory values of the disease severity.Methods. 34 patients with CTEPH were included in this study. To characterize the group, the following methods were used: echocardiographic examination, catheterization of the right cardiac chambers. Biomarkers of heart failure, systemic inflammation, as well as erythropoiesis and iron metabolism were assessed in all patients. The control group included 10 donors. To study the proinflammatory cytokine profile in plasma, interleukins (IL) 6, 8, 18, monocyte chemoattractant protein-1 (MCP-1) and matrix metalloproteinase 9 were determined using standard enzyme-linked immunosorbent assay (ELISA) kits.Results. Hemodynamic and morphofunctional changes in the pulmonary circulation specific to pulmonary hypertension were determined with catheterization of the right cardiac chambers and echocardiography. During plasma proinflammatory cytokines analysis, a significant increase in the level of IL-8 (p = 0.030) and MCP-1 (p = 0.031) in CTEPH group compared to the control group was observed. No significant differences for other analyzed markers were found. In the elaboration of the correlation analysis, moderate inverse coupling between proinflammatory markers and hemodynamic parameters characterizing the CTEPH severity were revealed, as well as positive correlations with parameters of remodeling of the right cardiac chambers and iron metabolism.Conclusion. The increased levels of IL-8 and MCP-1 in patients with CTEPH identified in the present study indicate a significant role of nonspecific immunity in the formation and progression of CTEPH. The coupling between cytokines and hemodynamic parameters, structural cardiac changes and plasma biochemical parameters were determined. Based on the obtained data, it is possible to develop new medicinal substances, targeting towards proinflammatory cytokines, their receptors and signaling pathways.Основные положенияИЛ-8 и MCP-1 играют существенную роль в патогенезе хронической тромбоэмболической легочной гипертензии, что указывает на важное значение неспецифического иммунитета в формировании и прогрессировании данного заболевания. Определена связь цитокинов с показателями гемодинамики, структурными изменениями сердца и биохимическими показателями плазмы крови. РезюмеАктуальность. Патогенез хронической тромбоэмболической легочной гипертензии (ХТЭЛГ) сложен и до конца не изучен. Особое внимание в генезе микрососудистого поражения при ХТЭЛГ уделяют асептическому воспалению, которое в свою очередь может быть опосредовано различными молекулярными механизмами. Учитывая противоречивые и неполные данные об изменении профиля факторов, контролирующих воспаление при ХТЭЛГ, исследования в этой области позволят определить новые терапевтические мишени для профилактики и лечения ХТЭЛГ.Цель. Изучить профиль провоспалительных цитокинов в плазме крови у пациентов с ХТЭЛГ и оценить связь этих цитокинов с основными морфофункциональными и лабораторными показателями тяжести течения заболевания.Материалы и методы. В исследование включены 34 пациента с верифицированным диагнозом ХТЭЛГ. Для характеризации группы использованы эхокардиографическое исследование и катетеризация правых камер сердца. У всех больных оценены биомаркеры сердечной недостаточности, системного воспаления, а также эритропоэза и обмена железа. В группу контроля вошли 10 человек-доноров. Для изучения профиля провоспалительных цитокинов в плазме крови определены интерлейкины (ИЛ) 6, 8, 18, моноцитарный хемоаттрактантный белкок 1 (MCP-1) и матриксная металлопротеиназа 9 с помощью стандартных наборов для иммуноферментного анализа.Результаты. По данным катетеризации правых камер сердца и эхокардиографии определены гемодинамические и морфофункциональные изменения малого круга кровообращения, характерные для легочной гипертензии. При анализе уровня провоспалительных цитокинов в плазме крови в группе ХТЭЛГ по сравнению с группой контроля отмечено значимое повышение ИЛ-8 (p = 0,030) и MCP-1 (p = 0,031). По другим проанализированным маркерам значимых различий не получено. В результате корреляционного анализа выявлены умеренные обратные взаимосвязи провоспалительных маркеров с гемодинамическими параметрами, характеризующими тяжесть ХТЭЛГ, а также положительные корреляционные связи с показателями ремоделирования правых камер сердца и обмена железа.Заключение. Установленное в настоящем исследовании повышение уровней ИЛ-8 и MCP-1 у пациентов с ХТЭЛГ указывает на значительную роль неспецифического иммунитета в формировании и прогрессировании ХТЭЛГ. Определены взаимосвязи цитокинов с показателями гемодинамики, структурными изменениями сердца и биохимическими показателями плазмы крови. На основе полученных данных возможна разработка новых лекарственных субстанций, мишенями для которых будут провоспалительные цитокины, их рецепторы и сигнальные пути

Phase Diagram of Ternary Cholesterol/Palmitoylsphingomyelin/Palmitoyloleoyl-Phosphatidylcholine Mixtures: Spin-Label EPR Study of Lipid-Raft Formation

AbstractFor canonical lipid raft mixtures of cholesterol (chol), N-palmitoylsphingomyelin (PSM), and 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), electron paramagnetic resonance (EPR) of spin-labeled phospholipids—which is insensitive to domain size—is used to determine the ternary phase diagram at 23°C. No phase boundaries are found for binary POPC/chol mixtures, nor for ternary mixtures with PSM content <24 mol %. EPR lineshapes indicate that conversion from the liquid-disordered (Lα) to liquid-ordered (Lo) phase occurs continuously in this region. Two-component EPR spectra and several tie lines attributable to coexistence of gel (Lβ) and fluid phases are found for ternary mixtures with low cholesterol or low POPC content. For PSM/POPC alone, coexistence of Lα and Lβ phases occurs over the range 50−95.5 mol % PSM. A further tie line is found at 3 mol % chol with endpoints at 50 and ≥77 mol % PSM. For PSM/chol, Lβ−Lo coexistence occurs over the range 10−38 mol % chol and further tie lines are found at 4.5 and 7 mol % POPC. Two-component EPR spectra indicative of fluid-fluid (Lα−Lo) phase separation are found for lipid compositions: 25%<PSM<65%, 5%<chol<30–35%, 65%>POPC>10%, and confirmed by nonlinear EPR. Tie lines are identified in the Lα−Lo coexistence region, indicating that the fluid domains are of sufficient size to obey the phase rule. The three-phase triangle is bounded approximately by the compositions 40 and 75 mol % PSM with 10 mol % chol, and 60 mol % PSM with 25 mol % chol. These studies define the compositions of raft-like Lo phases for a minimal realistic biological lipid mixture

Polyphenylenepyridines Based on Acetylaromatic Compounds

Nitrogen-containing polyphenylene type polymers containing pyridine rings were synthesized. The polymer-forming reaction is based on the interaction of diacetylarylene and triethylorthoformate with the formation of a pyrylium salt and subsequent treatment of the intermediate product with ammonia. The optimal ratios of the reagents for the formation of the pyridine fragment were determined. The mechanism of the main reaction is discussed. The formation of the pyridine ring and phentriyl (1,3,5-triphenylsubstituted benzene) fragments was confirmed using 1H NMR data of the example of model reactions. After heating at a temperature of 450 °C, when a more complete polycondensation process occurs, the polymers reach high values of thermal characteristics—10% weight loss in an inert atmosphere corresponds to 600 °C. The structure of the synthesized polymers was confirmed using elemental analysis, IR, XPS, and EPR spectroscopy. The conjugation length in cross-linked polyphenylene pyridines can be controlled by varying the arylene bridge groups between the phentriyl fragments, which opens up opportunities for the development of new composite materials for electrical applications

Deficient BH4 production via de novo and salvage pathways regulates NO responses to cytokines in adult cardiac myocytes

Adult rat cardiac myocytes typically display a phenotypic response to cytokines manifested by low or no increases in nitric oxide (NO) production via inducible NO synthase (iNOS) that distinguishes them from other cell types. To better characterize this response, we examined the expression of tetrahydrobiopterin (BH4)-synthesizing and arginine-utilizing genes in cytokine-stimulated adult cardiac myocytes. Intracellular BH4 and 7,8-dihydrobiopterin (BH2) and NO production were quantified. Cytokines induced GTP cyclohydrolase and its feedback regulatory protein but with deficient levels of BH4 synthesis. Despite the induction of iNOS protein, cytokine-stimulated adult cardiac myocytes produced little or no increase in NO versus unstimulated cells. Western blot analysis under nonreducing conditions revealed the presence of iNOS monomers. Supplementation with sepiapterin (a precursor of BH4) increased BH4 as well as BH2, but this did not enhance NO levels or eliminate iNOS monomers. Similar findings were confirmed in vivo after treatment of rat cardiac allograft recipients with sepiapterin. It was found that expression of dihydrofolate reductase, required for full activity of the salvage pathway, was not detected in adult cardiac myocytes. Thus, adult cardiac myocytes have a limited capacity to synthesize BH4 after cytokine stimulation. The mechanisms involve posttranslational factors impairing de novo and salvage pathways. These conditions are unable to support active iNOS protein dimers necessary for NO production. These findings raise significant new questions about the prevailing understanding of how cytokines, via iNOS, cause cardiac dysfunction and injury in vivo during cardiac inflammatory disease states since cardiac myocytes are not a major source of high NO production

Sepiapterin Decreases Acute Rejection and Apoptosis in Cardiac Transplants Independently of Changes in Nitric Oxide and Inducible Nitric-Oxide Synthase Dimerization

Tetrahydrobiopterin (BH4), a cofactor of inducible nitric-oxide synthase (iNOS), is an important post-translational regulator of NO bioactivity. We examined whether treatment of cardiac allograft recipients with sepiapterin [S-(-)-2-amino-7,8-dihydro-6-(2-hydroxy-1-oxopropyl)-4-(1H)-pteridinone], a precursor of BH4, inhibited acute rejection and apoptosis in cardiac transplants. Heterotopic cardiac transplantation was performed in Wistar-Furth donor to Lewis recipient strain rats. Recipients were treated daily after transplantation with 10 mg/kg sepiapterin. Grafts were harvested on post-transplant day 6 for analysis of BH4 (high-performance liquid chromatography), expression of inflammatory cytokines (reverse transcription- and real-time polymerase chain reaction), iNOS (Western blots), and NO (Griess reaction and NO analyzer). Histological rejection grade was scored, and graft function was determined by echocardiography. Apoptosis, protein nitration, and oxidative stress were determined by immunohistochemistry. Treatment of allografts with sepiapterin increased cardiac BH4 levels by 3-fold without changing protein levels of GTP cyclohydrolase, the enzyme that regulates de novo BH4 synthesis. Sepiapterin decreased inflammatory cell infiltrate and significantly inhibited histological rejection scores and apoptosis similar in magnitude to cyclosporine. Sepiapterin also decreased nitrative and oxidative stress. Sepiapterin caused a smaller increase in left ventricular mass versus untreated allografts but without improving fractional shortening. Sepiapterin did not alter tumor necrosis factor-α and interferon-γ expression, whereas it decreased interleukin (IL)-2 expression. Sepiapterin did not change total iNOS protein or monomer levels, or plasma and tissue NO metabolites levels. It is concluded that the mechanism(s) of antirejection are due in part to decreased apoptosis, protein nitration, and oxidation of cardiomyocytes, which seems to be mediated at the immune level by limiting inflammatory cell infiltration via decreased IL-2-mediated T-lymphocyte expansion

The Biological Traumatization of Crops Due to the Enzyme Stage of Enzyme-Mycotic Seed Depletion

In the light of Vavilov&rsquo;s Law, grain traumatization in the standing crop of wheat and other crops due to the enzyme stage of enzyme-mycotic seed depletion (EMSD) was confirmed, the parameters of open and hidden harmfulness were detected, and a scale of plant resistance to such traumatization was developed. The current study demonstrates that pathogen contamination in grains occurs before harvesting and its degree is determined by favorable humidity and temperature conditions and by the open and hidden grain traumatization due to the enzyme stage of EMSD, i.e., the grain&rsquo;s hydrolytic enzymes providing a growth substrate for a fungal spread that is later substituted by pathogen enzymes leading to grain spoiling and self-warming. The most common technique to preserve grain quality is to support a moisture level that prevents further spreading of the fungi. The grains that are contaminated with very low temperature and humidity levels facilitate the germinability and high quality of the grain. The new ways to withstand EMSD should, first of all, include a selection of activities. Using biological, biochemical and physical (X-ray) methods, genetic sources of resistance towards EMSD were found in the VIR world collection that is recommended for further selection. These sources have become a basis for the varieties, such as Moskovskaya 39, Ilot (winter wheat), Gremme and Gremme 2U (hulless spelt), Alcoran (winter spelt) and Kanysh (spring wheat)