Glycine inhibits the LPS-induced increase in cytosolic Ca2+ concentration and TNFalpha production in cardiomyocytes by activating a glycine receptor

Aqueous Fraction from Cucumis sativus Aerial Parts Attenuates Angiotensin II-Induced Endothelial Dysfunction In Vivo by Activating Akt

BACKGROUND

Endothelial dysfunction (ED) is a marker of vascular damage and a precursor of cardiovascular diseases such as hypertension, which involve inflammation and organ damage. Nitric oxide (NO), produced by eNOS, which is induced by pAKT, plays a crucial role in the function of a healthy endothelium.

METHODS

A combination of subfractions SF1 and SF3 (C4) of the aqueous fraction from Cucumis sativus (Cs-Aq) was evaluated to control endothelial dysfunction in vivo and on HMEC-1 cells to assess the involvement of pAkt in vitro. C57BL/6J mice were injected daily with angiotensin II (Ang-II) for 10 weeks. Once hypertension was established, either Cs-AqC4 or losartan was orally administered along with Ang-II for a further 10 weeks. Blood pressure (BP) was measured at weeks 0, 5, 10, 15, and 20. In addition, serum creatinine, inflammatory status (in the kidney), tissue damage, and vascular remodeling (in the liver and aorta) were evaluated. Cs-AqC4 was also tested in vitro on HMEC-1 cells stimulated by Ang-II to assess the involvement of Akt phosphorylation.

RESULTS

Cs-AqC4 decreased systolic and diastolic BP, reversed vascular remodeling, decreased IL-1β and TGF-β, increased IL-10, and decreased kidney and liver damage. In HMEC-1 cells, AKT phosphorylation and NO production were increased.

CONCLUSIONS

Cs-AqC4 controlled inflammation and vascular remodeling, alleviating hypertension; it also improved tissue damage associated with ED, probably via Akt activation.

Nutraceutical, Dietary, and Lifestyle Options for Prevention and Treatment of Ventricular Hypertrophy and Heart Failure

Although well documented drug therapies are available for the management of ventricular hypertrophy (VH) and heart failure (HF), most patients nonetheless experience a downhill course, and further therapeutic measures are needed. Nutraceutical, dietary, and lifestyle measures may have particular merit in this regard, as they are currently available, relatively safe and inexpensive, and can lend themselves to primary prevention as well. A consideration of the pathogenic mechanisms underlying the VH/HF syndrome suggests that measures which control oxidative and endoplasmic reticulum (ER) stress, that support effective nitric oxide and hydrogen sulfide bioactivity, that prevent a reduction in cardiomyocyte pH, and that boost the production of protective hormones, such as fibroblast growth factor 21 (FGF21), while suppressing fibroblast growth factor 23 (FGF23) and marinobufagenin, may have utility for preventing and controlling this syndrome. Agents considered in this essay include phycocyanobilin, N-acetylcysteine, lipoic acid, ferulic acid, zinc, selenium, ubiquinol, astaxanthin, melatonin, tauroursodeoxycholic acid, berberine, citrulline, high-dose folate, cocoa flavanols, hawthorn extract, dietary nitrate, high-dose biotin, soy isoflavones, taurine, carnitine, magnesium orotate, EPA-rich fish oil, glycine, and copper. The potential advantages of whole-food plant-based diets, moderation in salt intake, avoidance of phosphate additives, and regular exercise training and sauna sessions are also discussed. There should be considerable scope for the development of functional foods and supplements which make it more convenient and affordable for patients to consume complementary combinations of the agents discussed here. Research Strategy: Key word searching of PubMed was employed to locate the research papers whose findings are cited in this essay.

Cartilage repair in degenerative osteoarthritis mediated by squid type II collagen via immunomodulating activation of M2 macrophages, inhibiting apoptosis and hypertrophy of chondrocytes

Cartilage lesions in degenerative osteoarthritis (OA) are involved with pathological microenvironmental alterations induced by inflammatory macrophages, and apoptotic and/or hypertrophic chondrocytes. However, current non-operative therapies for cartilage repair in OA can rarely achieve long-term and satisfactory outcomes. This study aims to evaluate a newly developed squid type II collagen (SCII) for repairing OA-induced cartilage lesions. Our in vitro data show that SCII induces M2 polarization of macrophages, and activates macrophages to express pro-chondrogenic genes (TGF-β and IGF), which greatly improves the microenvironment around chondrocytes to produce type II collagen and glycosaminoglycan. In addition, glycine in SCII activates glycine receptors on inflammatory chondrocytes to decrease intracellular calcium concentration, leading to effective inhibition of chondrocyte apoptosis and hypertrophy. The in vitro effects of SCII are further confirmed in vivo. In a rat model of OA, SCII increases the ratio of M2 macrophages, elevates the levels of pro-chondrogenic cytokines (TGF-β1 and TGF-β3) in synovial fluid, and inhibits chondrocyte apoptosis and MMP13 production. Our findings show that SCII immunomodulates M2 activation of macrophages to skew the local OA microenvironment towards a pro-chondrogenic atmosphere, and promotes cartilage repair under inflammatory condition. It shows great potential for SCII to be a novel biomaterial for cartilage repair in OA.

Cucumis sativus Aqueous Fraction Inhibits Angiotensin II-Induced Inflammation and Oxidative Stress In Vitro

Inflammation and oxidative stress play major roles in endothelial dysfunction, and are key factors in the progression of cardiovascular diseases. The aim of this study was to evaluate in vitro the effect of three subfractions (SFs) from the Cucumis sativus aqueous fraction to reduce inflammatory factors and oxidative stress induced by angiotensin II (Ang II) in human microvascular endothelial cells-1 (HMEC-1) cells. The cells were cultured with different concentrations of Ang II and 0.08 or 10 μg/mL of SF1, SF2, or SF3, or 10 μmol of losartan as a control. IL-6 (Interleukin 6) concentration was quantified. To identify the most effective SF combinations, HMEC-1 cells were cultured as described above in the presence of four combinations of SF1 and SF3. Then, the effects of the most effective combination on the expression of adhesion molecules, the production of reactive oxygen species (ROS), and the bioavailability of nitric oxide (NO) were evaluated. Finally, a mass spectrometry analysis was performed. Both SF1 and SF3 subfractions decreased the induction of IL-6 by Ang II, and C4 (SF1 and SF3, 10 μg/mL each) was the most effective combination to inhibit the production of IL-6. Additionally, C4 prevented the expression of adhesion molecules, reduced the production of ROS, and increased the bioavailability of NO. Glycine, arginine, asparagine, lysine, and aspartic acid were the main components of both subfractions. These results demonstrate that C4 has anti-inflammatory and antioxidant effects.

Dietary Glycine Is Rate-Limiting for Glutathione Synthesis and May Have Broad Potential for Health Protection

BACKGROUND

Glutathione is a key scavenging antioxidant that opposes the proinflammatory signaling of hydrogen peroxide. Boosting cellular glutathione levels may have broad utility in the prevention and treatment of disorders driven by oxidative stress. Supplemental N-acetylcysteine has been employed for this purpose. Could supplemental glycine likewise promote glutathione synthesis?

METHODS

We conducted a review of the pertinent literature using PubMed.

RESULTS

Tissue glycine levels are lower than the glutathione synthase Michaelis constant (K_m) for glycine. When glycine availability is too low to sustain a normal rate of glutathione synthesis, the consequent rise in tissue levels of gamma-glutamylcysteine leads to an increase in urinary excretion of its alternative metabolite 5-L-oxoproline. The fact that urinary excretion of this metabolite is elevated in vegetarians and others consuming relatively low-protein diets strongly suggests that dietary glycine can be rate-limiting for glutathione synthesis in normally fed humans. Moreover, supplemental glycine has been reported to increase tissue glutathione levels in several animal studies. Glycine is a biosynthetic precursor for porphyrins, purines, creatine, sarcosine, and bile salts; is an agonist for glycine-gated chloride channels and a coagonist for N-methyl-D-aspartate receptors; inhibits protein glycation; and increases hepatic production of pyruvate, an effective scavenger of hydrogen peroxide. Supplemental glycine may have the potential for improving endothelial function, preventing cardiac hypertrophy, aiding control of metabolic syndrome, preventing the complications of diabetes, dampening inflammation, protecting the liver, and promoting effective sleep.

CONCLUSION

Clinical research is warranted to evaluate the impact of supplemental glycine on glutathione levels and on various health disorders.

Amelioration by glycine of brain damage in neonatal rat brain following hypoxia-ischemia

BACKGROUND

Glycine protected adult brains against injury in an experimental model of stroke, but, because the ischemic response of neonatal brains differs from that of adult brains, we examined the neuroprotective efficacy of glycine and associated mechanisms in an experimental model of neonatal hypoxic-ischemic (HI) encephalopathy.

METHODS

Neonatal (postnatal day 7) Wistar rats were randomly divided into an untreated group (non-HI) and two HI groups that were treated with left common carotid artery ligation and saline control or glycine. After recovery, pups that received surgery were injected i.p. with saline or glycine (800 mg/kg; optimal dose determined in pilot experiments) and were placed in a controlled 8% O₂ chamber for 120 min. Brains were harvested at various times after return to normoxia (several hours-days after HI) for analysis of infarct area, glial activation, cell apoptosis, and tumor necrosis factor-α (TNF-α) expression on histology and reverse transcription-polymerase chain reaction.

RESULTS

Glycine injections induced large (approx. 15-fold) but brief (approx. 2 h) increases in cerebrospinal fluid concentrations. In particular, the glycine group had a >70% decrease in infarct areas compared with controls at 7 days after HI. Glycine also significantly reduced astrocyte reactive transformation, microglia activation, and terminal deoxynucleotidyl transferase dUTP nick end labeling-positive (apoptotic) cell numbers in peri-lesional areas at 3 days after HI, and TNF-α mRNA expression in the injured hemisphere at 12 and 24 h after HI.

CONCLUSION

Glycine protected neonatal rat brains against HI, in part by inhibiting TNF-α-induced inflammation and gliosis. Hence, systemic glycine infusions may have clinical utility for the treatment of HI injury in human newborns.

The effects of verapamil and its combinations with glutamate and glycine on cardiodynamics, coronary flow and oxidative stress in isolated rat heart

The role of N-methyl-D-aspartate receptor (NMDA-R) in heart is still unclear. For these ionotropic glutamate receptors is characteristic the necessity of both co-agonists, glutamate and glycine, for their activation, which primarily allows influx of calcium. The aim of the present study was to examine the effects of verapamil, as a calcium channel blocker, alone and its combination with glycine and/or glutamate on cardiac function, coronary flow, and oxidative stress in isolated rat heart or to examine the effects of potential activation of NMDA-R in isolated rat heart. The hearts of male Wistar albino rats were excised and perfused according to Langendorff technique, and cardiodynamic parameters and coronary flow were determined during the administration of verapamil and its combinations with glutamate and/or glycine. The oxidative stress biomarkers, including thiobarbituric acid-reactive substances, nitrites, superoxide anion radical, and hydrogen peroxide, were each determined spectrophotometrically from coronary venous effluent. The greatest decline in parameters of cardiac contractility and systolic pressure was in the group that was treated with verapamil only, while minimal changes were observed in group treated with all three tested substances. Also, the largest changes in coronary flow were in the group treated only with verapamil, and at least in the group that received all three tested substances, as well as the largest increase in oxidative stress parameters. Based on the obtained results, it can be concluded that NMDA-R activation allows sufficient influx of calcium to increase myocardial contractility and systolic pressure, as well as short-term increase of oxidative stress.

Lipopolysaccharide Compromises Human Sperm Function by Reducing Intracellular cAMP

A worldwide decline in the quality of human semen is currently occurring. In mammals, sperm are produced from diploid stem-cell spermatogonia by spermatogenesis in testes and become mature in epididymis. Nevertheless, these biological processes can be affected by Gram-negative bacterial infection mediated by lipopolysaccharide (LPS), the major endotoxin of Gram-negative bacteria. It is well known that LPS can disturb spermatogenesis and affect sperm maturation and quality in vivo. However, the effect of LPS on the ejaculated mature sperm in vitro remains unclear. Thus, this study aimed to assess the in vitro toxicity of LPS on human sperm function and to elucidate the underlying mechanism. Human sperm were incubated with LPS (0.1-100 μg/ml) for 1-12 h in vitro and, subsequently, sperm viability, motility and capacitation, and the acrosome reaction were examined. LPS dose-dependently inhibited total and progressive motility and the ability to move through a viscous medium of the sperm but did not affect sperm viability, capacitation, and the acrosome reaction. To explore the underlying mechanism of LPS's actions, we examined the effects of LPS on the intracellular concentrations of cyclic adenosine monophosphate (cAMP) and calcium ([Ca(2+)]i) and protein-tyrosine phosphorylation of human sperm, which are key regulators of human sperm function. LPS decreased intracellular cAMP dose-dependently but had no effect on [Ca(2+)]i and protein-tyrosine phosphorylation of human sperm. These findings suggest that LPS inhibits human sperm motility by decreasing intracellular cAMP.

The role of glycine in regulated cell death

The cytoprotective effects of glycine against cell death have been recognized for over 28 years. They are expressed in multiple cell types and injury settings that lead to necrosis, but are still not widely appreciated or considered in the conceptualization of cell death pathways. In this paper, we review the available data on the expression of this phenomenon, its relationship to major pathophysiologic pathways that lead to cell death and immunomodulatory effects, the hypothesis that it involves suppression by glycine of the development of a hydrophilic death channel of molecular dimensions in the plasma membrane, and evidence for its impact on disease processes in vivo.

Role of endogenous TNF-α in cardiomyocyte apoptosis induced by bacteria lipoprotein and the protective effect of IL-10

Cardiomyocyte apoptosis is thought to play an important role in sepsis-induced cardiodepression. Previous studies mainly focused on the role of exogenous TNF-α in sepsis-induced cardiac damage, however, the role of endogenous TNF-α is rarely known. Therefore, we hypothesized that endogenous TNF-α also contributed to sepsis-induced cardiomyocyte apoptosis. Primary neonatal rat cardiomyocytes were time- and dose-dependently stimulated with BLP and TNF-α. In separate experiments, cells were treated with TNF-α antagonist and IL-10, respectively, to determine effects of endogenous TNF-α and exogenous IL-10 on BLP-induced cardiomyocyte apoptosis. After treatment, apoptosis was evaluated by nuclear condensation, membrane permeability change, caspase-3 activation, and pro- to anti-apoptotic protein (bax to bcl-2) expression. Treatment of cardiomyocytes with BLP and TNF-α both significantly induced caspase-3 activation in a time- and dose-dependent manner and caused apparent nuclear condensation and increased membrane permeability. TNF-α antagonist pretreatment attenuated BLP-induced caspase-3 activation, and downregulated bax/bcl-2 ratio. In addition, administration of IL-10 inhibited TNF-α production and suppressed cardiomyocyte apoptosis induced by BLP. Our data suggest that endogenous TNF-α play an important role in BLP-induced cardiomyocyte apoptosis and IL-10 protect cardiomyocytes from BLP-induced apoptosis, an effect partially through inhibition of endogenous TNF-α production.

Hydrolyzed tilapia fish collagen modulates the biological behavior of macrophages under inflammatory conditions

This is the first study showing that HFC can inhibit the excessive production of inflammatory mediators in RAW264.7 macrophages.

Glycine attenuates myocardial ischemia-reperfusion injury by inhibiting myocardial apoptosis in rats

Glycine is a well-documented cytoprotective agent. However, whether it has a protective effect against myocardial ischemia-reperfusion injury in vivo is still unknown. By using an open-chest anesthetized rat model, we found that glycine reduced the infarct size by 21% in ischemia-reperfusion injury rats compared with that in the vehicle-treated MI/R rats. The left ventricular ejection fraction and fractional shortening were increased by 19.11% and 30.98%, respectively, in glycine-treated rats. The plasma creatine kinase levels in ischemia-reperfusion injury rats decreased following glycine treatment. Importantly, administration of glycine significantly inhibited apoptosis in post-ischemia-reperfusion myocardium, which was accompanied by suppression of phosphorylated p38 mitogen-activated protein kinase and c-Jun NH2-terminal kinase, as well as the Fas ligand. These results suggest that glycine attenuates myocardial ischemia-reperfusion injury in vivo by inhibiting cardiomyocytes apoptosis.