Excessive Nitric Oxide Production Research Articles

ROLE OF NF-κB ACTIVATION IN CHANGES OF NITRIC OXIDE PRODUCTION IN SKELETAL MUSCLES DURING METABOLIC SYNDROME

Nitric oxide, as a signaling molecule, plays an ambiguous role in many pathological processes. On the one hand, nitric oxide is necessary for maintaining the tone of the vascular wall of arteries and prevents the development of ischemia in various organs and skeletal muscles in particular. On the other hand, excessive production of nitric oxide in the tissue can contribute to the formation of toxic metabolites, such as peroxynitrite that leads to the development of nitrosative damage to various organs and tissues. Metabolic syndrome is also one of the diseases accompanied by disturbances in the nitric oxide production system. Currently, the sources of nitric oxide production, the predominant ways of its metabolism, and the influence of the transcription factor NF-κB on these processes in skeletal muscles under the conditions of the metabolic syndrome are insufficiently studied. The purpose of this study is to study the effect of an inhibitor of the activation of the transcription factor NF-κB on the production of nitric oxide and the concentration of its metabolites in the biceps femoris muscle of rats under the conditions of modeling the metabolic syndrome. The experimental study was carried out on male Wistar rats weighing 200-260 g. The animals were randomly divided into 4 groups of 6 animals each. Animals of group 1 (control group) received a standard vivarium diet. In group 2 (metabolic syndrome), in addition to the standard diet, the animals received a 20% fructose solution as their sole source of drinking water for 60 days. In group 3, the animals were given a standard vivarium diet and were injected intraperitoneally with ammonium pyrrolidine dithiocarbamate at a dose of 76 mg/kg, three times a week for 60 days. Group 4 received the same diet as group 2 along with the injections administered in group 3. In 10% homogenate of the biceps femoris muscle, the following were determined: total NO-synthase activity, activity of constitutive and inducible isoforms of NO-synthase, arginase activity, aitrate- and nitrite reductase activity, concentrations of nitrite, peroxynitrite, nitrosothiols, and sulfides. The administration of ammonium pyrrolidinedithiocarbamate during metabolic syndrome simulation resulted in a reduction in total NO-synthase activity and inducible NO-synthase activity by 33.85% and 34.66%, respectively, compared to the metabolic syndrome group; arginase activity decreased by 37.56%, while nitrate and nitrite reductase activities were reduced by 19.29% and 47.71%, respectively; nitrite concentration increased by 21.77%, peroxynitrite concentration decreased by 32.05%, nitrosothiol concentration increased by 29.27%, and sulfide concentration decreased by 17.39% compared to the group with metabolic syndrome. Activation of the transcription factor NF-κB under metabolic syndrome conditions leads to increased nitric oxide production through both L-arginine-dependent and L-arginine-independent pathways in the biceps femoris muscle, enhances arginase activity, and results in elevated peroxynitrite formation.

Evaluation of In Vitro Antihypertensive and Anti-Inflammatory Properties of Dairy By-Products

Sweet whey (SW) and yogurt acid whey (YAW) are dairy by-products of the cheese-making process and Greek-style yogurt production, respectively. Both of them are considered pollutants with huge volumes of SW and YAW produced due to the growing demand for dairy products worldwide. Moreover, whey-derived peptides, resulting from fermentation as well as from further hydrolysis during digestion, have been associated with various biological activities. In the present study, the angiotensin-converting enzyme (ACE)-inhibitory activity of 48 SW samples and 33 YAW samples from bovine, ovine, caprine, and ovine/caprine milk obtained were evaluated. Additionally, the SW and YAW digestates and two of their fractions (smaller than 10 kDa, SW-D-P10 and YAW-D-P10, and smaller than 3 kDa, SW-D-P3 and YAW-D-P3), which were obtained after in vitro digestion and subsequent ultrafiltration, were also subjected to evaluation. Our data indicated that the D-P10 and D-P3 fractions exhibited higher ACE-inhibitory activity compared to the corresponding values before digestion. The ACE-inhibitory capacity after in vitro digestion was higher for the ovine SW samples compared to their bovine and caprine counterparts. The effect of the D-P3 fraction on the inhibition of nitric oxide (NO) production and the expression of a selected panel of immune-response-related genes in LPS-stimulated RAW 264.7 macrophages was also evaluated. Fractions from both dairy by-products inhibited NO production in LPS-stimulated RAW 264.7 cells. Especially, ovine SW-D-P3 showed a strong NO inhibitory activity and suppressed inducible nitric oxide synthase (Nos2) mRNA levels. However, YAW-D-P3 could not trigger neither the gene expression of inflammatory macrophage mediators Nos2 and cyclooxygenase-2 (Ptgs2) nor tumor necrosis factor-α (Tnf) and interleukin 6 (Il6) in LPS-stimulated murine macrophages regardless of animal origin. These findings suggest that in vitro digestion could enhance the production of ACE-inhibitory peptides in both dairy by-products, while SW from ovine origin displays higher potential as an anti-inflammatory agent, effectively preventing excessive NO production.

Revealing the anti-inflammatory activity of Euphorbia hirta extract: transcriptomic and nitric oxide production analysis in LPS-Induced RAW 264.7 cells

ABSTRACT Excessive production of nitric oxide (NO) dan pro-inflammatory cytokines can lead to tissue damage and chronic inflammation. Euphorbia hirta presents an interesting opportunity for plant-derived anti-inflammatory agents as it contains a range of compounds which have demonstrated anti-inflammatory effects. This study investigates the anti-inflammatory properties of E. hirta extract on gene expression and NO production in LPS-treated RAW 264.7 cells. The results demonstrate that E. hirta extracts effectively suppress NO production in RAW 264.7 cells. Furthermore, the extract inhibits iNOS protein expression and reduces the expression of pro-inflammatory cytokines TNF-α and IL−12. RNA sequencing revealed significant alterations in gene expression, including 167 upregulated and 56 downregulated genes-related inflammation pathways. The study concludes that E. hirta extract possesses anti-inflammatory activity by modulating gene expression and inhibiting NO production in LPS-treated RAW 264.7 cells. The extract influences genes associated with inflammation signalling pathways, including cytokine signalling, NF-κB, iNOS and JAK-STAT pathways.

Fish arginase constrains excessive production of nitric oxide and limits mitochondrial damage during Aeromonas hydrophila infection

Bacteria-enhanced inducible nitric oxide synthase (iNOS) overproduces nitric oxide (NO) leading to mitochondrial and cellular damage. In mammals, arginase (ARG), the enzyme consuming the same substrate l-arginine with iNOS, was believed to inhibit iNOS activity by competing the substrate. But in fish, this conception has been widely challenged. In this study, the gene expression using real-time quantitative PCR (RT-qPCR) technology showed that when stimulated by Aeromonas hydrophila (A. hydrophila), grass carp (gc) iNOS was up-regulated in head kidney monocytes/macrophages (M0/MФ), and its changes were not detected in the whole tissue of liver or spleen, showing a high degree of cell-specific expression pattern. At the same time, gcARG2 had a high basal expression in tissues and was up-regulated by A. hydrophila stimulation. Next, phthalaldehyde-primaquine reaction was first used in the determination of intracellular urea in fish cells. It was found that the induced gcARG2 led to an increase in the intracellular urea content. Moreover, urea and NO production in M0/MФ were increased in a substrate dose-dependent manner from 30 to 100 μM of l-arginine and reached the highest yield at 300 and 3000 μM of l-arginine, respectively. Furthermore, head kidney M0/MФ was cultured in RPMI1640 medium containing physiological concentration (500 μM) of l-arginine to evaluate the effect of ARG. Under A. hydrophila stimulation, treatment with the arginase inhibitor S-(2-boronoethyl)-l-cysteine (BEC) showed that inhibition of arginase could further enhance the NO production stimulated by A. hydrophila. This in turn led to a cumulation in peroxynitrite (ONOO-) content and an injury of the mitochondrial membrane potential. Our study showed for the first time that fish ARG in head kidney M0/MФ can limit excessive production of NO and harmful products by iNOS to maintain mitochondrial and cellular homeostasis.

GSNOR overexpression enhances CAR-T cell stemness and anti-tumor function by enforcing mitochondrial fitness

Chimeric antigen receptor T cell (CAR-T) has been developed as a promising agent for patients with refractory or relapsed lymphoma and leukemia, but not all the recipients could achieve a long-lasting remission. The limited capacity of in vivo expansion and memory differentiation post activation is one of the major reasons for suboptimal CAR-T therapeutic efficiency. Nitric oxide (NO) plays multifaceted roles in mitochondrial dynamics and T-cell activation, but its function on CAR-T cell persistence and anti-tumor efficacy remains unknown. Herein, we found the continuous signaling from CAR not only promotes excessive NO production, but also suppressed S-nitrosoglutathione reductase (GSNOR) expression in T cells, which collectively led to increased protein S-nitrosylation, resulting in impaired mitochondrial fitness and deficiency of T cell stemness. Intriguingly, enforced expression of GSNOR promoted memory differentiation of CAR-T cell after immune activation, rendered CAR-T better resistance to mitochondrial dysfunction, further enhanced CAR-T cell expansion and anti-tumor capacity in vitro and in mouse tumor model. Thus, we revealed a critical role of NO in restricting CAR-T cell persistence and functionality, and defined that GSNOR overexpression may provide a solution to combat NO stress and render patients with more durable protection from CAR-T therapy.

Nitric Oxide (NO) Synthase Inhibitors: Potential Candidates for the Treatment of Anxiety Disorders?

Close to 19% of the world population suffers from anxiety. Current medications for this chronic mental disorder have improved treatment over the last half century or more, but the newer anxiolytics have proved disappointing, and enormous challenges remain. Nitric oxide (NO), an intra- and inter-cellular messenger in the brain, is involved in the pathogenesis of anxiety. In particular, excessive NO production might contribute to its pathology. This implies that it might be useful to reduce nitrergic activity; therefore, molecules aiming to downregulate NO production such as NO synthase inhibitors (NOSIs) might be candidates. Here, it was intended to critically review advances in research on these emerging molecules for the treatment of anxiety disorders. Current assessment indicates that, although NOSIs are implicated in anxiety, their potential anti-anxiety action remains to be established.

Pharmacokinetics, biodistribution, and in vivo toxicity of 7-nitroindazole loaded in pegylated and non-pegylated nanoemulsions in rats

Sepsis is a life-threatening condition caused by a dysregulated host response to infection. The development of sepsis is associated with excessive nitric oxide (NO) production, which plays an important role in controlling vascular homeostasis. 7-nitroindazole (7-NI) is a selective inhibitor of neuronal nitric oxide synthase (NOS-1) with potential application for treating NO imbalance conditions. However, 7-NI exhibits a low aqueous solubility and a short plasma half-life. To circumvent these biopharmaceutical limitations, pegylated (NEPEG7NI) and non-pegylated nanoemulsions (NENPEG7NI) containing 7-NI were developed. This study evaluates the pharmacokinetic profiles and toxicological properties of 7-NI loaded into the nanoemulsions. After a single intravenous administration of the free drug and the nanoemulsions at a dose of 10 mg.kg−1 in Wistar rats, 7-NI was widely distributed in the organs. The pharmacokinetic parameters of Cmax, t1/2, and AUC0-t were significantly increased after administration of the NEPEG7NI, compared to both free 7-NI and NENPEG7NI (p < 0.05). No observable adverse effects were observed after administering the free 7-NI, NEPEG7NI, or NENPEG7NI in the animals after a single dose of up to 3.0 mg.kg−1. The results indicated that 7-NI-loaded nanoemulsions are safe, constituting a promising approach to treating sepsis.

Citrulline and ADI-PEG20 reduce inflammation in a juvenile porcine model of acute endotoxemia.

Arginine is a conditionally essential amino acid that is depleted in critically ill or surgical patients. In pediatric and adult patients, sepsis results in an arginine-deficient state, and the depletion of plasma arginine is associated with greater mortality. However, direct supplementation of arginine can result in the excessive production of nitric oxide (NO), which can contribute to the hypotension and macrovascular hypo-reactivity observed in septic shock. Pegylated arginine deiminase (ADI-PEG20, pegargiminase) reduces plasma arginine and generates citrulline that can be transported intracellularly to generate local arginine and NO, without resulting in hypotension, while maintaining microvascular patency. The objective of this study was to assess the efficacy of ADI-PEG20 with and without supplemental intravenous citrulline in mitigating hypovolemic shock, maintaining tissue levels of arginine, and reducing systemic inflammation in an endotoxemic pediatric pig model. Twenty 3-week-old crossbred piglets were implanted with jugular and carotid catheters as well as telemetry devices in the femoral artery to measure blood pressure, body temperature, heart rate, and respiration rate. The piglets were assigned to one of three treatments before undergoing a 5h lipopolysaccharide (LPS) infusion protocol. Twenty-four hours before LPS infusion, control pigs (LPS; n=6) received saline, ADI-PEG20 pigs (n=7) received an injection of ADI-PEG20, and seven pigs (ADI-PEG20 + CIT pigs [n=7]) received ADI-PEG20 and 250 mg/kg citrulline intravenously. Pigs were monitored throughout LPS infusion and tissue was harvested at the end of the protocol. Plasma arginine levels decreased and remained low in ADI-PEG20 + CIT and ADI-PEG20 pigs compared with LPS pigs but tissue arginine levels in the liver and kidney were similar across all treatments. Mean arterial pressure in all groups decreased from 90 mmHg to 60 mmHg within 1h of LPS infusion but there were no significant differences between treatment groups. ADI-PEG20 and ADI-PEG20 + CIT pigs had less CD45+ infiltrate in the liver and lung and lower levels of pro-inflammatory cytokines in the plasma. ADI-PEG20 and citrulline supplementation failed to ameliorate the hypotension associated with acute endotoxic sepsis in pigs but reduced systemic and local inflammation in the lung and liver.

ALZHEIMER HASTALIĞINDA iNOS İNHİBİTÖRLERİNİN UMUT VERİCİ ROLÜ

Objective: This study aims to explore the role of iNOS inhibitors in Alzheimer's disease (AD), a neurodegenerative disorder affecting millions worldwide. The main symptoms of AD include memory loss, cognitive decline, and behavioral changes. While the exact cause remains uncertain, both genetic and environmental factors are believed to contribute. Recent research has emphasized the significance of nitric oxide (NO) in AD development. Specifically, the upregulation of inducible nitric oxide synthase (iNOS) in AD patients leads to excessive NO production during neuronal inflammation, exacerbating AD and dementia. Therefore, the investigation focuses on the potential of iNOS inhibitors as a novel therapeutic approach for AD treatment. Result and Discussion: In this review, we present the current therapeutic strategies available for Alzheimer's disease (AD) and explore the promising potential of iNOS inhibitors in AD treatment. Specifically, we will focus on their capacity to mitigate NO production and examine their potential neuroprotective effects. Additionally, this review will offer an overview of both natural and synthetic iNOS inhibitors, emphasizing the importance of safety considerations during the development of iNOS inhibitors as therapeutic interventions for AD.

Comparison of Low-Intensity and High-Intensity Exercise in Salivary Nitric Oxide Response: A Pilot Study

Background: Excessive production of salivary nitric oxide (s-NO) is a risk factor for oral diseases such as Sjögren syndrome and periodontal disease. Although s-NO is known to be affected by exercise, it is unclear how the difference in exercise intensities affects the s-NO response. Objectives: The purpose of this study was to investigate the acute effect of different exercise intensities (high vs. low intensity) on s-NO production using a cross-over design. Methods: Five healthy male young adults (21.6 ± 0.9 years) performed two ergometer exercises for 30 min at different exercise intensities: 50% heart rate (HR)reserve (low-intensity condition) and 80% HRreserve (high-intensity condition). Saliva samples were collected before (pre) and after (post 0-h and post 1-h) exercises. Results: The s-NO concentration significantly increased (P &lt; 0.05) after the high-intensity exercise (∆changes in post 0-h; +244 ± 53 µmol/L, post 1-h; +352 ± 58 µmol/L), but the s-NO concentration did not change after the low-intensity exercise (∆changes in post 0-h; +11 ± 37 µmol/L, post 1-h; +64 ± 69 µmol/L). Conclusions: This study reveals that s-NO production is dependent on exercise intensities, suggesting that low-intensity exercise can be possible without increasing the risk of oral diseases.

Neuronal Nitric Oxide Synthase and Post-Translational Modifications in the Development of Central Nervous System Diseases: Implications and Regulation.

In the Central Nervous System (CNS), Nitric Oxide (NO) is mainly biosynthesized by neuronal Nitric Oxide Synthase (nNOS). The dysregulated activation of nNOS in neurons is critical in the development of different conditions affecting the CNS. The excessive production of NO by nNOS is responsible for a number of proteins' post-translational modifications (PTMs), which can lead to aberrant biochemical pathways, impairing CNS functions. In this review, we briefly revise the main implications of dysregulated nNOS in the progression of the most prevalent CNS neurodegenerative disorders, i.e., Alzheimer's disease (AD) and Parkinson's disease, as well as in the development of neuronal disorders. Moreover, a specific focus on compounds able to modulate nNOS activity as promising therapeutics to tackle different neuronal diseases is presented.

Argininosuccinate lyase deficiency causes blood-brain barrier disruption via nitric oxide-mediated dysregulation of claudin expression.

Nitric oxide (NO) is a critical signaling molecule that has been implicated in the pathogenesis of neurocognitive diseases. Both excessive and insufficient NO production have been linked to pathology. Previously, we have shown that argininosuccinate lyase deficiency (ASLD) is a novel model system to investigate cell-autonomous, nitric oxide synthase-dependent NO deficiency. Humans with ASLD are at increased risk for developing hyperammonemia due to a block in ureagenesis. However, natural history studies have shown that individuals with ASLD have multisystem disease including neurocognitive deficits that can be independent of ammonia. Here, using ASLD as a model of NO deficiency, we investigated the effects of NO on brain endothelial cells in vitro and the blood-brain barrier (BBB) in vivo. Knockdown of ASL in human brain microvascular endothelial cells (HBMECs) led to decreased transendothelial electrical resistance, indicative of increased cell permeability. Mechanistically, treatment with an NO donor or inhibition of Claudin-1 improved barrier integrity in ASL-deficient HBMECs. Furthermore, in vivo assessment of a hypomorphic mouse model of ASLD showed increased BBB leakage, which was partially rescued by NO supplementation. Our results suggest that ASL-mediated NO synthesis is required for proper maintenance of brain microvascular endothelial cell functions as well as BBB integrity.

Gastro‑oesophageal reflux disease in liver cirrhosis: Possible pathogenesis and clinical intervention (Review).

Oesophageal variceal bleeding is a common complication of decompensated liver cirrhosis (LC). Some studies have reported that reflux oesophagitis (RE) is a risk factor for upper gastrointestinal bleeding, and greatly impacts the quality of life. However, the frequency and mechanism of gastro-oesophageal reflux disease (GERD) in LC remain unclear. The present review explored the possible pathogenesis, and analysed the advantages and disadvantages of the interventional measures and the need for implementation of these measures. By combining the comprehensive terms associated with LC, GERD and RE, EMBASE, Medline/PubMed and the Cochrane Library were systematically searched. The underlying pathological mechanism of GERD in LC was summarized: Transient relaxation of the lower oesophageal sphincter, delayed gastric emptying, increased intra-abdominal pressure, increased intragastric pressure and excessive nitric oxide production destroyed the 'anti-reflux barrier', causing gastric content reflux. Proton pump inhibitors (PPIs) have been widely used empirically to lower the risk of oesophageal venous rupture and bleeding. However, long-term use of acid inhibitors in patients with LC may induce complications, such as spontaneous bacterial peritonitis. The metabolic half-life of PPIs is prolonged in patients with severe liver function impairment. Therefore, the indications for using acid inhibitors lack clarity. However, after endoscopic oesophageal variceal eradication, additional benefits may be gained from the long-term use of PPIs in small doses.

Metabolic Signature of Energy Metabolism Alterations and Excess Nitric Oxide Production in Culture Media Correlate with Low Human Embryo Quality and Unsuccessful Pregnancy.

Notwithstanding the great improvement of ART, the overall rate of successful pregnancies from implanted human embryos is definitely low. The current routine embryo quality assessment is performed only through morphological criteria, which has poor predictive capacity since only a minor percentage of those in the highest class give rise to successful pregnancy. Previous studies highlighted the potentiality of the analysis of metabolites in human embryo culture media, useful for the selection of embryos for implantation. In the present study, we analyzed in blind 66 human embryo culture media at 5 days after in vitro fertilization with the aim of quantifying compounds released by cell metabolism that were not present as normal constituents of the human embryo growth media, including purines, pyrimidines, nitrite, and nitrate. Only some purines were detectable (hypoxanthine and uric acid) in the majority of samples, while nitrite and nitrate were always detectable. When matching biochemical results with morphological evaluation, it was found that low grade embryos (n = 12) had significantly higher levels of all the compounds of interest. Moreover, when matching biochemical results according to successful (n = 17) or unsuccessful (n = 25) pregnancy, it was found that human embryos from the latter group released higher concentrations of hypoxanthine, uric acid, nitrite, and nitrate in the culture media. Additionally, those embryos that developed into successful pregnancies were all associated with the birth of healthy newborns. These results, although carried out on a relatively low number of samples, indicate that the analysis of the aforementioned compounds in the culture media of human embryos is a potentially useful tool for the selection of embryos for implantation, possibly leading to an increase in the overall rate of ART.

Berberine hydrochloride inhibits migration ability via increasing inducible NO synthase and peroxynitrite in HTR-8/SVneo cells

Ethnopharmacological relevanceInadequate trophoblasts migration and invasion is considered as an initial event resulting in preeclampsia, which is closely related to oxidative stress. Berberine hydrochloride (BBR), extracted from the traditional medicinal plant Coptis chinensis Franch., exerts a diversity of pharmacological effects, and the crude drug has been widely taken by most Chinese women to treat nausea and vomit during pregnancy. But there is no research regarding its effects on trophoblast cell function. Aim of the studyThis study aimed to investigate the effect of BBR on human-trophoblast-derived cell line (HTR-8/SVneo) migration ability and its mechanism. Materials and methodsCell viability was detected by CCK-8 assay. The effect of BBR on cells migration function was examined by scratch wound healing assay and transwell migration assay. Intracellular nitric oxide (NO), superoxide (O2−) and peroxynitrite (ONOO−) levels were measured by flow cytometry. The expression levels of inducible NO synthase (iNOS), eNOS, p-eNOS, MnSOD, CuZnSOD, Rac1, NOX1, TLR4, nuclear factor-κB (NF-κB), p-NFκB, pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) in cells were analyzed by Western blotting. Uric acid sodium salt (UA), the scavenger of ONOO−, PEG-SOD (a specific superoxide scavenger), L-NAME (a NOS inhibitor) and antioxidants (Vit E and DFO) were further used to characterize the pathway of BBR action. Results5 μM BBR decreased both the migration distance and the number of migrated cells without affecting cells viability in HTR-8/SVneo cells after 24 h treatment. BBR could increase the level of NO in HTR-8/SVneo cells, and the over-production of NO might be attributable to iNOS, but not eNOS. BBR could increase intracellular O2− levels, and the over-production of O2− is closely related with Rac1 in HTR-8/SVneo cells. The excessive production of NO and O2− further react to form ONOO−, and the increased ONOO− level induced by BBR was blunted by UA. Moreover, UA improved the impaired migration function caused by BBR in HTR-8/SVneo cells. The depressed migration function stimulated by BBR in HTR-8/SVneo cells was diminished by PEG-SOD and L-NAME. Furthermore, BBR increased the expression of IL-6 in HTR-8/SVneo cells, and antioxidants (Vit E and DFO) could decrease the expression of IL-6 and iNOS induced by BBR. ConclusionsBBR inhibits the cell migration ability through increasing inducible NO synthase and peroxynitrite in HTR-8/SVneo cells, indicating that BBR and traditional Chinese medicines containing a high proportion of BBR should be used with caution in pregnant women.

The Inhibition of the Inducible Nitric Oxide Synthase Enhances the DPSC Mineralization under LPS-Induced Inflammation

Nitric oxide (NO) is a key messenger in physiological and pathological processes in mammals. An excessive NO production is associated with pathological conditions underlying the inflammation response as a trigger. Among others, dental pulp inflammation results from the invasion of dentin by pathogenic bacteria. Vital functions of pulp mesenchymal stem cells (DPSCs, dental pulp stem cells), such as mineralization, might be affected by the inducible NOS (iNOS) upregulation. In this context, the iNOS selective inhibition can be considered an innovative therapeutic strategy to counteract inflammation and to promote the regeneration of the dentin-pulp complex. The present work aims at evaluating two acetamidines structurally related to the selective iNOS inhibitor 1400W, namely CM544 and FAB1020, in a model of LPS-stimulated primary DPSCs. Our data reveal that CM544 and even more FAB1020 are promising anti-inflammatory compounds, decreasing IL-6 secretion by enhancing CD73 expression-levels, a protein involved in innate immunity processes and thus confirming an immunomodulatory role of DPSCs. In parallel, cell mineralization potential is retained in the presence of compounds as well as VEGF secretion, and thus their angiogenetic potential. Data presented lay the ground for further investigation on the anti-inflammatory potential of acetamidines selectively targeting iNOS in a clinical context.

Redox imaging of dextran sodium sulfate-induced colitis mice treated with nitric oxide synthase inhibitors

Ulcerative colitis (UC) is an inflammatory bowel disease of unknown cause. Redox imbalance, as characterized by excessive production of reactive oxygen species (ROS) and nitric oxide (NO), and deficient levels of endogenous antioxidants, is associated with the pathogenesis of UC. Overhauser-enhanced magnetic resonance imaging (OMRI) combined with a spin-probe method produces high-resolution images of redox imbalance in disease states. We aimed to investigate the effect of NO synthase (NOS) inhibitors on colonic ROS generation in mice with colitis induced by dextran sodium sulfate (DSS) using the OMRI/spin-probe method. Symptoms of DSS-induced colitis were ameliorated by an inducible NOS (iNOS) inhibitor, aminoguanidine (AG), but not by a non-selective NOS inhibitor, NG-Nitro-L-arginine methyl ester (L-NAME). Intracellular ROS generation, observed as the enhancement of OMRI contrast decay rates of a 3-methoxy-2,2,5,5-tetramethylpyrrolidine-1-oxyl probe in the colons of DSS-induced colitis mice, was suppressed by AG, in agreement with the results of an in vivo electron spin resonance study. AG had an inhibitory effect on ROS production at the upper colon and rectum during the initiation stage of colitis, and at the upper and lower colon during the advanced stage. Additionally, there were partial differences in the localization of iNOS protein and nitrite/nitrate levels. L-NAME treatment showed a tendency for increased ROS generation at the upper colon during the advanced stage. The OMRI/spin-probe method provides a novel tool for screening ROS inhibitory activity in vivo in DSS-induced colitis mice.

Anti-inflammatory compounds from the mangrove endophytic fungus Amorosia sp. SCSIO 41026.

Three new chlorinated compounds, including two propenylphenol derivatives, chlorophenol A and B (1 and 2), and one benzofuran derivative, chlorophenol C (3), together with 16 known compounds, were isolated from the mangrove endophytic fungus Amorosia sp. SCSIO 41026. 7-Chloro-3,4-dihydro-6,8-dihydroxy-3-methylisocoumarine (4) and 2,4-dichloro-3-hydroxy-5-methoxy-toluene (5) were obtained as new natural products. Their structures were elucidated by physicochemical properties and extensive spectroscopic analysis. Compounds 1, 4, 7, 9, 13, 15, 16, and 19 possessed inhibitory effects against the excessive production of nitric oxide (NO) and pro-inflammatory cytokines in lipopolysaccharide (LPS)-challenged RAW264.7 macrophages without obvious cytotoxicity. Moreover, 5-chloro-6-hydroxymellein (13) further alleviated the pathological lung injury of LPS-administrated mice and protected RAW264.7 macrophages against LPS-induced inflammation through PI3K/AKT pathway in vivo. Our research laid the foundation for the application of compound 13 as a potential anti-inflammatory candidate.

Anti-Inflammatory Polyketides from an Alga-Derived Fungus Aspergillus ochraceopetaliformis SCSIO 41020.

A new linear polyketide, named aspormisin A (1), together with five known polyketides (2–6), were isolated from the alga-derived fungus Aspergillus ochraceopetaliformis SCSIO 41020. Their structures were elucidated through a detailed comprehensive spectroscopic analysis, as well as a comparison with the literature. An anti-inflammatory evaluation showed that compounds 2, 5, and 6 possessed inhibitory activity against the excessive production of nitric oxide (NO) and pro-inflammatory cytokines in LPS-treated RAW 264.7 macrophages in a dose-dependent manner without cytotoxicity. Further studies revealed that compound 2 was active in blocking the release of pro-inflammatory cytokines (IL-6, MCP-1, and TNF-α) induced by LPS both in vivo and in vitro. Our findings provide a basis for the further development of linear polyketides as promising anti-inflammatory agents.

ALDH2 mutation results in excessive basal nitric oxide production and a delayed response to nitroglycerin

Abstract Background and purpose: Nitroglycerin tolerance is a common phenomenon in patients with coronary artery disease (CAD). Aldehyde dehydrogenase 2 (ALDH2) is the enzyme that metabolizes nitroglycerin to its active form nitric oxide (NO). Previous studies showed altered nitroglycerin in subjects with ALDH2 mutation, but the functional impact on endothelial cells is not fully understood. Methods: In the first step of in vitro experiments, we examined functional properties of induced pluripotent stem cell-derived CD144+ endothelial cells (iPSC-ECs) that expressed wildtype (WT) vs ALDH2+/− variant. In the second step of human studies, diameter of the left anterior descending (LAD) coronary artery was determined using angiography in 151 adult volunteers (111 with WT ALDH2, 32 with ALDH2+/− and 8 with ALDH2−/− genotype) prior to as well as after intracoronary injection of 200-μg nitroglycerin. Results: Briefly, the ALDH2+/− iPSC-ECs demonstrated impaired low-density lipoprotein (LDL) uptake, proliferation, migration, tube formation, oxidative stress resistance, and viability. In comparison to the WT control, the ALDH2+/− iPSC-ECs had elevated NO production under baseline conditions, but exhibited a delayed NO release after nitroglycerin treatment. Exposure to 10-μg/mL nitroglycerin for 2 h increased NO production in WT iPSC-ECs but 4-h exposure was required to stimulate NO production in the ALDH2+/− iPSC-ECs. In comparison to the WT control, the subjects carrying the ALDH2+/− variants had seemingly larger LAD coronary artery diameter (3.5 and 3.8 mm vs 3.4 mm in the WT control), but attenuated vasodilatory response to nitroglycerin (ALDH2MUT group vs the WT control, 7.1 ± 0.6% vs 10.1 ± 0.8%, P = 0.024). Conclusion: These findings indicated elevated NO production by endothelia cells under basal conditions but attenuated response to nitroglycerin upon ALDH2 mutation.