High dietary taurine reduces apoptosis and atherosclerosis in the left main coronary artery: association with reduced CCAAT/enhancer binding protein homologous protein and total plasma homocysteine but not lipidemia

Decoding interaction between mitochondria and endoplasmic reticulum in ischemic myocardial injury: targeting natural medicines

Ischemic cardiomyopathy (ICM) is a special type or end stage of coronary heart disease or other irreversible ischemic myocardial injury. Inflammatory damage to coronary vessels is a crucial factor in causing stenosis or occlusion of coronary arteries, resulting in myocardial ischemia and hypoxia, but it is also an aspect of cardioprotection that is often overlooked. This review discusses the mechanisms of vascular injury during ICM, in which inflammation and oxidative stress interact and trigger cell death as the cause of coronary microvascular injury. Imbalances in endoplasmic reticulum function and mitochondrial quality control are important potential drivers of inflammation and oxidative stress. In addition, many studies have confirmed the therapeutic effects of Chinese herbal medicines and their natural monomeric components on vascular injuries. Their mitochondrial quality control and endoplasmic reticulum protection mechanisms as well as their role in combating improvements in vascular endothelial function and attenuating vascular injury are also summarized, with a perspective to provide a reference for pathologic understanding, drug research, and clinical application of ICM-associated coronary microvascular injury.

Taurine exhibits antioxidant, anti-inflammatory, and antiapoptotic effects against pyraclostrobin exposure in rats

Pyraclostrobin, a strobilurin-derived fungicide, causes oxidative stress and DNA damage in the organism. Taurine plays an important role in metabolic processes such as osmoregulatory, cytoprotective, and antioxidant effects. The study aimed to investigate the protective effect of taurine in Sprague Dawley male rats exposed to pyraclostrobin. The rats were separated into 6 groups and were found 8 animals in each group. Rats were given 30 mg/kg pyraclostrobin and pyraclostrobin together with three different taurine concentrations (50, 100, and 200 mg/kg) via oral gavage for 28 days. While pyraclostrobin increased biochemical parameters, lipid peroxidation, and DNA damage, it decreased glutathione levels and enzyme activities of catalase and superoxide dismutase. Pyraclostrobin increased apoptotic, proinflammatory, and CYP2E1 mRNA expression levels, whereas antiapoptotic gene Bcl-2 mRNA expression levels decreased in liver tissue. Additionally, pyraclostrobin caused histopathological alterations in tissues. Taurine in a dose-dependent manner reversed the changes caused by pyraclostrobin. As a result, taurine exhibited a cytoprotective effect by showing antioxidant, anti-inflammatory, and antiapoptotic activities against oxidative damage caused by pyraclostrobin.

The role of taurine through endoplasmic reticulum in physiology and pathology

Taurine is a sulfur-containing amino acid found in many cell organelles that plays a wide range of biological roles, including bile salt production, osmoregulation, oxidative stress reduction, and neuromodulation. Taurine treatments have also been shown to ameliorate the onset and development of many diseases, including hypertension, fatty liver, neurodegenerative diseases and ischemia-reperfusion injury, by exerting antioxidant, anti-inflammatory, and antiapoptotic effects. The endoplasmic reticulum (ER) is a dynamic organelle involved in a wide range of cellular functions, including lipid metabolism, calcium storage and protein stabilization. Under stress, the disruption of the ER environment leads to the accumulation of misfolded proteins and a characteristic stress response called the unfolded protein response (UPR). The UPR protects cells from stress and helps to restore cellular homeostasis, but its activation promotes cell death under prolonged ER stress. Recent studies have shown that ER stress is closely related to the onset and development of many diseases. This article reviews the beneficial effects and related mechanisms of taurine by regulating the ER in different physiological and pathological states, with the aim of providing a reference for further research and clinical applications.

Functional Role of Taurine in Aging and Cardiovascular Health: An Updated Overview

Taurine, a naturally occurring sulfur-containing amino acid, has attracted significant attention in recent years due to its potential health benefits. Found in various foods and often used in energy drinks and supplements, taurine has been studied extensively to understand its impact on human physiology. Determining its exact functional roles represents a complex and multifaceted topic. We provide an overview of the scientific literature and present an analysis of the effects of taurine on various aspects of human health, focusing on aging and cardiovascular pathophysiology, but also including athletic performance, metabolic regulation, and neurological function. Additionally, our report summarizes the current recommendations for taurine intake and addresses potential safety concerns. Evidence from both human and animal studies indicates that taurine may have beneficial cardiovascular effects, including blood pressure regulation, improved cardiac fitness, and enhanced vascular health. Its mechanisms of action and antioxidant properties make it also an intriguing candidate for potential anti-aging strategies.

Combination of Taurine and Black Pepper Extract as a Treatment for Cardiovascular and Coronary Artery Diseases

The shift in modern dietary regimens to "Western style" and sedentary lifestyles are believed to be partly responsible for the increase in the global burden of cardiovascular diseases. Natural products have been used throughout human history as treatments for a plethora of pathological conditions. Taurine and, more recently, black pepper have gained attention for their beneficial health effects while remaining non-toxic even when ingested in excess. Taurine, black pepper, and the major terpene constituents found in black pepper (i.e., β-caryophyllene; α-pinene; β-pinene; α-humulene; limonene; and sabinene) that are present in PhytoCann BP^® have been shown to have cardioprotective effects based on anti-inflammatory, antioxidative, anti-hypertensive and anti-atherosclerotic mechanisms. This comprehensive review of the literature focuses on determining whether the combination of taurine and black pepper extract is an effective natural treatment for reducing cardiovascular diseases risk factors (i.e., hypertension and hyperhomocysteinemia) and for driving anti-inflammatory, antioxidative and anti-atherosclerotic mechanisms to combat coronary artery disease, heart failure, myocardial infarction, and atherosclerotic disease.

Arsenic-induced toxicity and the ameliorative role of antioxidants and natural compounds

Arsenic (As) poisoning has proven to be a major threat worldwide because of its toxic effects on the human body. As toxicity through drinking water is a global health concern. The toxicity of As is known to affect the liver, kidney, lungs, muscles, cardiovascular system, and nervous system and can even induce diabetes. Further As can cause skin lesions leading to notable diseases in the skin like Bowen's disease. Chronic exposure to As has caused many tragedies in Eastern, and several Southeast Asian and Latin American countries. Long-term exposure to As makes it an immediate threat that should be dealt with as a priority, and one of the ways to handle it may be with the use of antioxidants. In this review, we have discussed the natural and anthropogenic sources of As, its metabolism, pathophysiology, and mechanism of toxicity. Besides, we have also discussed some of the synthetic chelators and the ameliorative role of antioxidants and natural compounds in reducing As toxicity.

Taurine and Its Derivatives: Analysis of the Inhibitory Effect on Platelet Function and Their Antithrombotic Potential

Taurine is a semi-essential, the most abundant free amino acid in the human body, with a six times higher concentration in platelets than any other amino acid. It is highly beneficial for the organism, has many therapeutic actions, and is currently approved for heart failure treatment in Japan. Taurine has been repeatedly reported to elicit an inhibitory action on platelet activation and aggregation, sustained by in vivo, ex vivo, and in vitro animal and human studies. Taurine showed effectiveness in several pathologies involving thrombotic diathesis, such as diabetes, traumatic brain injury, acute ischemic stroke, and others. As human prospective studies on thrombosis outcome are very difficult to carry out, there is an obvious need to validate existing findings, and bring new compelling data about the mechanisms underlying taurine and derivatives antiplatelet action and their antithrombotic potential. Chloramine derivatives of taurine proved a higher stability and pronounced selectivity for platelet receptors, raising the assumption that they could represent future potential antithrombotic agents. Considering that taurine and its analogues display permissible side effects, along with the need of finding new, alternative antithrombotic drugs with minimal side effects and long-term action, the potential clinical relevance of this fascinating nutrient and its derivatives requires further consideration.

Aging and Hypercholesterolemia Differentially Affect the Unfolded Protein Response in the Vasculature of ApoE-/- Mice

Background Persistent activation of endoplasmic reticulum stress and the unfolded protein response (UPR) induces vascular cell apoptosis, contributing to atherogenesis. Aging and hypercholesterolemia are 2 independent proatherogenic factors. How they affect vascular UPR signaling remains unclear. Methods and Results Transcriptome analysis of aortic tissues from high fat diet-fed and aged ApoE-/- mice revealed 50 overlapping genes enriched for endoplasmic reticulum stress- and UPR-related pathways. Aortae from control, Western diet (WD)-fed, and aged ApoE-/- mice were assayed for (1) 3 branches of UPR signaling (pancreatic ER eIF2-alpha kinase /alpha subunit of the eukaryotic translation initiation factor 1/activating transcription factor 4, inositol-requiring enzyme 1 alpha/XBP1s, activating transcription factor 6); (2) UPR-mediated protective adaptation (upregulation of immunoglobulin heavy chain-binding protein and protein disulfide isomerase); and (3) UPR-mediated apoptosis (induction of C/EBP homologous transcription factor, p-JNK, and cleaved caspase-3). Aortic UPR signaling was differentially regulated in the aged and WD-fed groups. Consumption of WD activated all 3 UPR branches; in the aged aorta, only the ATF6α arm was activated, but it was 10 times higher than that in the WD group. BiP and protein disulfide isomerase protein levels were significantly decreased only in the aged aorta despite a 5-fold increase in their mRNA levels. Importantly, the aortae of aged mice exhibited a substantially enhanced proapoptotic UPR compared with that of WD-fed mice. In lung tissues, UPR activation and the resultant adaptive/apoptotic responses were not significantly different between the 2 groups. Conclusions Using a mouse model of atherosclerosis, this study provides the first in vivo evidence that aging and an atherogenic diet activate differential aortic UPR pathways, leading to distinct vascular responses. Compared with dietary intervention, aging is associated with impaired endoplasmic reticulum protein folding and increased aortic apoptosis.

Plasma Metabolomic Profiles in Recovered COVID-19 Patients without Previous Underlying Diseases 3 Months After Discharge

BACKGROUND

It remains unclear whether discharged COVID-19 patients have fully recovered from severe complications, including the differences in the post-infection metabolomic profiles of patients with different disease severities.

METHODS

COVID-19-recovered patients, who had no previous underlying diseases and were discharged from Wuhan Union Hospital for 3 months, and matched healthy controls (HCs) were recruited in this prospective cohort study. We examined the blood biochemical indicators, cytokines, lung computed tomography scans, including 39 HCs, 18 recovered asymptomatic (RAs), 34 recovered moderate (RMs), and 44 recovered severe/ critical patients (RCs). A liquid chromatography-mass spectrometry-based metabolomics approach was employed to profile the global metabolites of fasting plasma of these participants.

RESULTS

Clinical data and metabolomic profiles suggested that RAs recovered well, but some clinical indicators and plasma metabolites in RMs and RCs were still abnormal as compared with HCs, such as decreased taurine, succinic acid, hippuric acid, some indoles, and lipid species. The disturbed metabolic pathway mainly involved the tricarboxylic cycle, purine, and glycerophospholipid metabolism. Moreover, metabolite alterations differ between RMs and RCs when compared with HCs. Correlation analysis revealed that many differential metabolites were closely associated with inflammation and the renal, pulmonary, heart, hepatic, and coagulation system functions.

CONCLUSION

We uncovered metabolite clusters pathologically relevant to the recovery state in discharged COVID-19 patients which may provide new insights into the pathogenesis of potential organ damage in recovered patients.

Protective role of taurine against oxidative stress (Review)

Taurine is a fundamental mediator of homeostasis that exerts multiple roles to confer protection against oxidant stress. The development of hypertension, muscle/neuro‑​associated disorders, hepatic cirrhosis, cardiac dysfunction and ischemia/reperfusion are examples of some injuries that are linked with oxidative stress. The present review gives a comprehensive description of all the underlying mechanisms of taurine, with the aim to explain its anti‑oxidant actions. Taurine is regarded as a cytoprotective molecule due to its ability to sustain normal electron transport chain, maintain glutathione stores, upregulate anti‑oxidant responses, increase membrane stability, eliminate inflammation and prevent calcium accumulation. In parallel, the synergistic effect of taurine with other potential therapeutic modalities in multiple disorders are highlighted. Apart from the results derived from research findings, the current review bridges the gap between bench and bedside, providing mechanistic insights into the biological activity of taurine that supports its potential therapeutic efficacy in clinic. In the future, further clinical studies are required to support the ameliorative effect of taurine against oxidative stress.

The molecular targets of taurine confer anti-hyperlipidemic effects

Hyperlipidemia, an independent risk factor for atherosclerosis, is regarded as a lipid metabolism disorder associated with elevated plasma triglyceride and/or cholesterol. Genetic factors and unhealthy lifestyles, such as excess caloric intake and physical inactivity, can result in hyperlipidemia. Taurine, a sulfur-containing non-essential amino acid, is abundant in marine foods and has been associated with wide-ranging beneficial physiological effects, with special reference to regulating aberrant lipid metabolism. Its anti-hyperlipidemic mechanism is complex, which is related to many enzymes in the process of fat anabolism and catabolism (e.g., HMGCR, CYP7A1, LDLR, FXR, FAS and ACC). Anti-inflammatory and antioxidant molecular targets, lipid autophagy, metabolic reprogramming and gut microbiota will also be reviewed.

The long and winding road to target protein misfolding in cardiovascular diseases

BACKGROUND

In the last decades, cardiovascular diseases (CVD) have remained the first leading cause of mortality and morbidity in the world. Although several therapeutic approaches have been introduced in the past, the development of novel treatments remains an important research goal, which is hampered by the lack of understanding of key mechanisms and targets. Emerging evidences in recent years indicate the involvement of misfolded proteins aggregation and the derailment of protein quality control in the pathogenesis of cardiovascular diseases. Several potential interventions targeting protein quality control have been translated from the bench to the bedside to effectively employ the misfolded proteins as promising therapeutic targets for cardiac diseases, but with trivial results.

DESIGN

In this review, we describe the recent progresses in preclinical and clinical studies of protein misfolding and compromised protein quality control by selecting and reporting studies focusing on cardiovascular diseases including cardiomyopathies, cardiac amyloidosis, atherosclerosis, atrial fibrillation and thrombosis.

RESULTS

In preclinical models, modulators of several molecular targets (eg heat shock proteins, unfolded protein response, ubiquitin protein system, autophagy and histone deacetylases) have been tested in various conditions with promising results although lacking an adequate transition towards clinical setting.

CONCLUSIONS

At present, no therapeutic strategies have been reported to attenuate proteotoxicity in patients with CVD due to a lack of specific biomarkers for pinpointing upstream events in protein folding defects at a subclinical stage of the diseases requiring an intensive collaboration between basic scientists and clinicians.

Osteoporosis and the effect of dysregulation of the transsulfuration pathway via taurine on intracellular calcium homeostasis, vitamin D absorption and vitamin K absorption

BACKGROUND & AIMS

In this article we connect the dysregulation of the transsulfuration pathway to bone dysregulations and propose a novel treatment for osteoporosis. Current treatments for osteoporosis are very frequently inadequate. In osteoporosis, the risk of fractures increases with increased homocysteine (Hcy).

METHODS

Here, we conduct a review on the relationship between osteoporosis and the dysregulation of the transsulfuration pathway.

RESULTS

we show that the transsulfuration pathway metabolizes Hcy to L-cysteine. Increased Hcy levels point to the transsulfuration pathway being dysregulated. With the transsulfuration pathway dysregulated, there will be decreased levels of L-cysteine and decreased levels of taurine, which is synthesized from L-cysteine. Taurine levels are decreased in patients with osteoporosis. Taurine regulates intracellular calcium homeostasis. Taurine, also, when conjugated with bile acids assists with absorption of fats and fat-soluble vitamins such as vitamin D and vitamin K. Dysregulated calcium homeostasis, decreased calcium absorption and decreased absorption of vitamin D and vitamin K due to low levels of taurine negatively affect bone mineral density (BMD) leading to osteoporosis and fractures.

CONCLUSIONS

In this article, we propose that a combination of taurine, calcium, vitamin D and vitamin K, could increase BMD reducing number of years spent in disability and reducing deaths due to fractures in patients with osteoporosis.

The Anti-Inflammatory Effect of Taurine on Cardiovascular Disease

Taurine is a non-protein amino acid that is expressed in the majority of animal tissues. With its unique sulfonic acid makeup, taurine influences cellular functions, including osmoregulation, antioxidation, ion movement modulation, and conjugation of bile acids. Taurine exerts anti-inflammatory effects that improve diabetes and has shown benefits to the cardiovascular system, possibly by inhibition of the renin angiotensin system. The beneficial effects of taurine are reviewed.

The Effect of an Atherogenic Diet and Acute Hyperglycaemia on Endothelial Function in Rabbits Is Artery Specific

Hyperglycaemia has a toxic effect on blood vessels and promotes coronary artery disease. It is unclear whether the dysfunction caused by hyperglycaemia is blood vessel specific and whether the dysfunction is exacerbated following an atherogenic diet. Abdominal aorta, iliac, and mesenteric arteries were dissected from New Zealand White rabbits following either a 4-week normal or atherogenic diet (n = 6–12 per group). The arteries were incubated ex vivo in control or high glucose solution (20 mM or 40 mM) for 2 h. Isometric tension myography was used to determine endothelial-dependent vasodilation. The atherogenic diet reduced relaxation as measured by area under the curve (AUC) by 25% (p < 0.05), 17% (p = 0.06) and 40% (p = 0.07) in the aorta, iliac, and mesenteric arteries, respectively. In the aorta from the atherogenic diet fed rabbits, the 20 mM glucose altered EC₅₀ (p < 0.05). Incubation of the iliac artery from atherogenic diet fed rabbits in 40 mM glucose altered EC₅₀ (p < 0.05). No dysfunction occurred in the mesentery with high glucose incubation following either the normal or atherogenic diet. High glucose induced endothelial dysfunction appears to be blood vessel specific and the aorta may be the optimal artery to study potential therapeutic treatments of hyperglycaemia induced endothelial dysfunction.

Fat from dairy foods and 'meat' consumed within recommended levels is associated with favourable serum cholesterol levels in institutionalised older adults

CVD is common in older adults. Consumption of ‘meat’ (beef, pork, lamb, game, poultry, seafood, eggs) and dairy foods (milk, cheese, yoghurt) is encouraged in older adults as these foods provide protein and nutrients such as essential fatty acids, Ca, Fe, Zn and vitamins A, D and B₁₂ required for healthy ageing. However, these foods also contain saturated fats considered detrimental to cardiovascular health. To determine the effect of their consumption on CVD risk we assessed associations between fat intake from ‘meat’ and dairy foods and serum cholesterol levels in 226 aged-care residents (mean age 85·5 years, 70 % female). Dietary intake was determined over 2 d using visual estimation of plate waste. Fat content of foods was determined using nutrition analysis software (Xyris, Australia). Fasting serum total cholesterol (TC), LDL-cholesterol and HDL-cholesterol were measured, and the TC:HDL-cholesterol ratio calculated. Associations were determined using random-effect models adjusted for CVD risk factors using STATA/IC 13.0. Total fat and saturated fat from ‘meat’ and dairy foods were associated with higher serum HDL-cholesterol levels, and dairy fat intake and number of servings were associated with a lower TC:HDL-cholesterol ratio. Every 10 g higher intake of fat and saturated fat from dairy products, and each additional serving was associated with a −0·375 (95 % CI −0·574, −0·175; P = 0·0002), a −0·525 (95 % CI −0·834, −0·213; P = 0·001) and a −0·245 (95 % CI −0·458, −0·033; P = 0·024) lower TC:HDL-cholesterol ratio, respectively. Provision of dairy foods and ‘meat’ in recommended amounts to institutionalised older adults potentially improves intakes of key nutrients with limited detriment to cardiovascular health.

Effects of Cervical Rotatory Manipulation (CRM) on Carotid Atherosclerosis Plaque in Vulnerability: A Histological and Immunohistochemical Study Using Animal Model

Background

The safety of cervical rotatory manipulation (CRM) is still controversial, especially in patients with carotid artery atherosclerosis (CAS). The study aimed to investigate the effects of CRM on carotid plaques in vulnerability.

Methods

50 rabbits were randomly divided into four groups: model rabbits with CRM [CAS-CRM (n=15)]; model rabbits without CRM [CAS (n=15)]; normal rabbits with CRM [Normal-CRM (n=10)]; and Blank-control group (n=10). CAS disease models were induced by carotid artery balloon injury combined with a high-fat diet for 12 weeks. Then, CRM technique was performed in CAS-CRM and Normal-CRM groups for 3 weeks. In the end, determination of serum level of hs-CRP and Lp-PLA2, histological analysis under HE and Masson trichromic staining, and immunohistochemical analysis with CD34 and CD68 antibody were completed in order.

Results

Carotid stenosis rates on successful model rabbits ranged from 70% to 98%. The CAS-CRM group had an increased level of hs-CRP (P<0.05), in comparison with the CAS group, whereas effects were not significant between the Normal-CRM group and Blank-control group. In comparison with the CAS group, the positive expression of CD34 and CD68 in the CAS-CRM group increased significantly (P<0.05).

Conclusion

CRM therapy may increase the vulnerability of carotid plaque in rabbits with severe CAS.

Taurine Improves Lipid Metabolism and Skeletal Muscle Sensitivity to Insulin in Rats Fed with High Sugar and High Fat Diet

Metabolic syndrome is a lifestyle-related disease caused by high nutrient condition and lack of exercise. The insulin resistance due to obesity has attracted attention as an underlying mechanism of metabolic syndrome. Insulin resistance refers to reduced insulin sensitivity in insulin target tissues. In this case, in order to maintain normal blood glucose levels, a compensatory large amount of insulin is released, leading to the occurrence of hyperinsulinemia. Taurine is widely distributed in animal tissues. Although it is not involved in protein synthesis, taurine plays an important role in maintaining the body's physiological function. In this experiment, insulin resistance model was induced by high fat and high sugar diet. Two percent taurine was added in drinking water to explore the mechanism of taurine in insulin resistance and to provide theoretical basis for using taurine to improve insulin resistance. The result showed that high-fat and high-sugar diet could decrease insulin sensitivity, and taurine could improve it by oral glucose tolerance test. Moreover, serum TG, TC were higher, while HDL-C in rats fed with high sugar and high fat diet was lower than normal rats, the changes of which can be significantly relieved by 2% taurine administration. mRNA and protein expressions of IRS1, and GLUT4 which were significantly changed by high sugar and high fat diet can also be regulated by 2% taurine. The results indicated that taurine can improve insulin sensitivity through remediating lipid metabolism disorder and regulating the expressions of IRS and GLUT4.

Abd Elwahab A. Ameliorative effect of taurine-chloramine in azathioprine-induced testicular damage; a deeper insight into the mechanism of protection

BACKGROUND

The male reproductive system is a sensitive and intricate process that can be distressed following exposure to various toxicants. Therapeutic drugs, especially chemotherapeutics, can also adversely affect male fertility by instigating hormonal changes leading to testicular cells injury. Azathioprine (AZA) is an effective anticancer drug, but some cases of testicular toxicity have been reported. The aim of this work was to investigate the protective effects of taurine chloramine (TAU-Cl), a reported antioxidant and antiinflammtory peptide, against AZA-induced testicular dysfunction in male rats and ascertain the contributing mechanisms.

METHODS

Forty male rats were allocated into four equal groups; (i) normal control rats, (ii) TAU-Cl group (100 mg/kg b.w/day for 10 weeks, (iii) AZA group (5 mg/day for 4 weeks); (iv) TAU-Cl/AZA group.

RESULTS

AZA caused increased DNA damage in the testes, and alterations in sex hormones and sperm quality, including sperm count, viability, and motility. Moreover, testicular tissue from the AZA-treated group had increased levels of oxidative stress indicator, MDA, and decreased activity of the antioxidant enzymes as superoxide dismutase (SOD), reduced glutathione (GSH) and catalase (CAT) levels. These deleterious events were accompanied by upregulated levels of the pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-α), and protein expression of iNOS and NFκB-p65, interleukin-1beta (IL-1β), and proapoptotic marker; caspase-9, together with decreased Bcl-2, NrF2 and hemeoxygenase (HO-1) expression. In contrast, TAU-Cl pretreatment significantly abrogated these toxic effects which were confirmed histologically.

CONCLUSION

Pretreatment with TAU-Cl exerts a protective effect against AZA-induced male reproductive testicular atrophy. This finding could open new avenues for the use of TAU-Cl as a complementary approach to chemotherapy supportive care.

Effects and Mechanisms of Taurine as a Therapeutic Agent

Taurine is an abundant, β-amino acid with diverse cytoprotective activity. In some species, taurine is an essential nutrient but in man it is considered a semi-essential nutrient, although cells lacking taurine show major pathology. These findings have spurred interest in the potential use of taurine as a therapeutic agent. The discovery that taurine is an effective therapy against congestive heart failure led to the study of taurine as a therapeutic agent against other disease conditions. Today, taurine has been approved for the treatment of congestive heart failure in Japan and shows promise in the treatment of several other diseases. The present review summarizes studies supporting a role of taurine in the treatment of diseases of muscle, the central nervous system, and the cardiovascular system. In addition, taurine is extremely effective in the treatment of the mitochondrial disease, mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), and offers a new approach for the treatment of metabolic diseases, such as diabetes, and inflammatory diseases, such as arthritis. The review also addresses the functions of taurine (regulation of antioxidation, energy metabolism, gene expression, ER stress, neuromodulation, quality control and calcium homeostasis) underlying these therapeutic actions.

Impact of high cholesterol and endoplasmic reticulum stress on metabolic diseases: An updated mini-review

Endoplasmic reticulum (ER) is the major site of protein folding and calcium storage. Beside the role of ER in protein homeostasis, it controls the cholesterol production and lipid-membrane biosynthesis as well as surviving and cell death signaling mechanisms in the cell. It is well-documented that elevated plasma cholesterol induces adverse effects in cardiovascular diseases (CVDs), liver disorders, such as non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatosis hepatitis (NASH), and metabolic diseases which are associated with oxidative and ER stress. Recent animal model and human studies have showed high cholesterol and ER stress as an emerging factors involved in the development of many metabolic diseases. In this review, we will summarize the crucial effects of hypercholesterolemia and ER stress response in the pathogenesis of CVDs, NAFLD/NASH, diabetes and obesity which are major health problems in western countries.

•

Endoplasmic reticulum stress involves in various metabolic disease development.

•

Altered cholesterol metabolism is a well-documented inducer of ER stress.

•

ER stress mediated apoptosis leads many cardiovascular disorders.

•

UPR might lead NAFLD/NASH progression by enhancing inflammation and fibrosis.

Role of Nox inhibitors plumbagin, ML090 and gp91ds-tat peptide on homocysteine thiolactone induced blood vessel dysfunction

Antioxidants have not reduced the burden of cardiovascular disease, and current evidence suggests a beneficial role of oxidative stress, via NADPH oxidase (Nox) upregulation, in endothelial function. Homocysteine thiolactone (HcyT) induces blood vessel dysfunction and this correlates with increased vascular oxidative stress. This study aimed to determine if pharmacological inhibition of Nox could impair HcyT induced blood vessel dysfunction. Abdominal aorta were excised from New Zealand White rabbits (n = 6), cut into rings and sequentially mounted in organ baths. Rings were preincubated with 0.55 μmol/L homocysteine thiolactone for 1 h, or combinations of putative Nox inhibitors (plumbagin for Nox4, gp91ds-tat for Nox2, and ML090 for Nox1), 30 min prior to the addition of HcyT, followed by a dose response curve to acetylcholine on phenylephrine preconstricted rings. Plumbagin, ML090 + gp91ds-tat and HcyT reduced responses to acetylcholine, and Plumbagin + Hcyt caused constriction to acetylcholine, which was normalised to plumbagin by ML090. Plumbagin + ML090 or plumbagin + gp91ds-tat completely impaired the effect of acetylcholine. ML090 inhibited the effect of HcyT on reduced response to acetylcholine, whereas gp91ds-tat had no effect. This study concludes that inhibition of Nox1 prevents, whereas inhibition of Nox4 worsens, acetylcholine induced blood vessel relaxation caused by HcyT, while Nox2 inhibition has no effect. However combinations of Nox inhibitors worsen acetylcholine induced blood vessel relaxation. These results suggest that there is cross-talk between Nox isoforms during physiological and pathophysiological processes.

Evidence for CD34/SMA positive cells in the left main coronary artery in atherogenesis

Regression of atherosclerosis is a key aspect of preventing further coronary artery disease and understanding which cell type forms smooth muscle cells in atherosclerotic fibrous caps will aid in reducing CAD. Atherogenesis is a complex interplay of cells migrating and proliferating into the vascular wall. CD34 positive hemapoetic stem cells are believed to not transform into vascular smooth muscle cells (SMC). The current study hypothesised that there would be no evidence for CD34(+)/α SMC actin(+) cells in atherosclerotic coronary arteries.

AIMS

To identify CD34+/α actin positive cells in the fibrous cap and wall of atherosclerotic plaques in the coronary artery.

METHODS

Male New Zealand White rabbits were fed a diet containing 0.5% cholesterol and 1% methionine for 4 weeks, then 9 weeks of normal diet to induce regression. Immunohistochemistry was used to detect CD34(+) haematopoietic progenitor cells and α SMC actin.

RESULTS

In the fibrous cap, the majority of cells were CD34(-)/α SMC actin(+) spindle shaped cells. However very rare populations of CD34(+)/α SMC actin(+) and CD34(+)/α SMC actin(-) cells were also present but these cells were not spindle shaped.

CONCLUSION

Our study found that CD34(+)/α SMC actin(-) spindle shaped cells were absent from the fibrous cap. Moreover, the predominant cell population were the vascular smooth muscle cells (CD34(-)/α SMC actin(+)) but (CD34(+)/α SMC actin(+)) cells were also present. This model could be used to understand the role of each SMC population subtype to hasten atherosclerotic regression in the coronary artery.

Modulatory Effect of Taurine on 7,12-Dimethylbenz(a)Anthracene-Induced Alterations in Detoxification Enzyme System, Membrane Bound Enzymes, Glycoprotein Profile and Proliferative Cell Nuclear Antigen in Rat Breast Tissue

The modulatory effect of taurine on 7,12-dimethylbenz(a)anthracene (DMBA)-induced breast cancer in rats was studied. DMBA (25 mg/kg body weight) was administered to induce breast cancer in rats. Protein carbonyl levels, activities of membrane bound enzymes (Na(+) /K(+) ATPase, Ca(2+) ATPase, and Mg(2+) ATPase), phase I drug metabolizing enzymes (cytochrome P450, cytochrome b5, NADPH cytochrome c reductase), phase II drug metabolizing enzymes (glutathione-S-transferase and UDP-glucuronyl transferase), glycoprotein levels, and proliferative cell nuclear antigen (PCNA) were studied. DMBA-induced breast tumor bearing rats showed abnormal alterations in the levels of protein carbonyls, activities of membrane bound enzymes, drug metabolizing enzymes, glycoprotein levels, and PCNA protein expression levels. Taurine treatment (100 mg/kg body weight) appreciably counteracted all the above changes induced by DMBA. Histological examination of breast tissue further supported our biochemical findings. The results of the present study clearly demonstrated the chemotherapeutic effect of taurine in DMBA-induced breast cancer.

The Role of Endoplasmic Reticulum Stress and Unfolded Protein Response in Atherosclerosis

Pathogenesis of atherosclerosis is a complex process involving several metabolic and signalling pathways. Accumulating evidence demonstrates that endoplasmic reticulum stress and associated apoptosis can be induced in the pathological conditions of atherosclerotic lesions and contribute to the disease progression. Notably, they may play a role in the development of vulnerable plaques that induce thrombosis and are therefore especially dangerous. Endoplasmic reticulum stress response is regulated by several signaling mechanisms that involve protein kinases and transcription factors. Some of these molecules can be regarded as potential therapeutic targets to improve treatment of atherosclerosis. In this review we will discuss the role of endoplasmic reticulum stress and apoptosis in atherosclerosis development in different cell types and summarize the current knowledge on potential therapeutic agents targeting molecules regulating these pathways and their possible use for anti-atherosclerotic therapy.

Taurine Supplementation Lowers Blood Pressure and Improves Vascular Function in Prehypertension: Randomized, Double-Blind, Placebo-Controlled Study

Taurine, the most abundant, semiessential, sulfur-containing amino acid, is well known to lower blood pressure (BP) in hypertensive animal models. However, no rigorous clinical trial has validated whether this beneficial effect of taurine occurs in human hypertension or prehypertension, a key stage in the development of hypertension. In this randomized, double-blind, placebo-controlled study, we assessed the effects of taurine intervention on BP and vascular function in prehypertension. We randomly assigned 120 eligible prehypertensive individuals to receive either taurine supplementation (1.6 g per day) or a placebo for 12 weeks. Taurine supplementation significantly decreased the clinic and 24-hour ambulatory BPs, especially in those with high-normal BP. Mean clinic systolic BP reduction for taurine/placebo was 7.2/2.6 mm Hg, and diastolic BP was 4.7/1.3 mm Hg. Mean ambulatory systolic BP reduction for taurine/placebo was 3.8/0.3 mm Hg, and diastolic BP was 3.5/0.6 mm Hg. In addition, taurine supplementation significantly improved endothelium-dependent and endothelium-independent vasodilation and increased plasma H2S and taurine concentrations. Furthermore, changes in BP were negatively correlated with both the plasma H2S and taurine levels in taurine-treated prehypertensive individuals. To further elucidate the hypotensive mechanism, experimental studies were performed both in vivo and in vitro. The results showed that taurine treatment upregulated the expression of hydrogen sulfide-synthesizing enzymes and reduced agonist-induced vascular reactivity through the inhibition of transient receptor potential channel subtype 3-mediated calcium influx in human and mouse mesenteric arteries. In conclusion, the antihypertensive effect of chronic taurine supplementation shows promise in the treatment of prehypertension through improvement of vascular function.

Cancer prevention and therapy through the modulation of the tumor microenvironment

Cancer arises in the context of an in vivo tumor microenvironment. This microenvironment is both a cause and consequence of tumorigenesis. Tumor and host cells co-evolve dynamically through indirect and direct cellular interactions, eliciting multiscale effects on many biological programs, including cellular proliferation, growth, and metabolism, as well as angiogenesis and hypoxia and innate and adaptive immunity. Here we highlight specific biological processes that could be exploited as targets for the prevention and therapy of cancer. Specifically, we describe how inhibition of targets such as cholesterol synthesis and metabolites, reactive oxygen species and hypoxia, macrophage activation and conversion, indoleamine 2,3-dioxygenase regulation of dendritic cells, vascular endothelial growth factor regulation of angiogenesis, fibrosis inhibition, endoglin, and Janus kinase signaling emerge as examples of important potential nexuses in the regulation of tumorigenesis and the tumor microenvironment that can be targeted. We have also identified therapeutic agents as approaches, in particular natural products such as berberine, resveratrol, onionin A, epigallocatechin gallate, genistein, curcumin, naringenin, desoxyrhapontigenin, piperine, and zerumbone, that may warrant further investigation to target the tumor microenvironment for the treatment and/or prevention of cancer.

Endothelial endoplasmic reticulum and nitrative stress in endothelial dysfunction in the atherogenic rabbit model

Oxidative stress causes endothelial dysfunction which ultimately leads to atherogenesis, yet anti-oxidant therapy has failed to reduce human clinical outcomes. We hypothesise that endoplasmic reticulum stress and oxidative stress are both present in the endothelial layer of aorta with atherosclerosis. Rabbits were fed for 4 weeks a diet supplemented with 1% methionine +0.5% cholesterol (MC). Control animals received a normal diet. The endothelial function of the abdominal aorta was examined using organ bath techniques. Semi-quantitative immunohistochemistry was used to determine endothelial nitrotyrosine (for nitrative/oxidative stress) and glucose regulated protein 78 (GRP 78) and CHOP to determine endoplasmic reticulum stress. Endothelium dependent relaxation in response to acetylcholine significantly decreased in MC. Stress markers were significantly elevated in endothelia in MC compared to control. The total endothelial area examined for GRP78 increased by 8.4±0.25% in MC vs control (p=0.026) and C/EBP homologous protein (CHOP) increased by 21.9±0.05% in MC vs control (p=0.014). Nitrotyrosine increased by 13.3±0.03% in MC vs control (p=0.012).

CONCLUSIONS

Both endoplasmic reticulum stress and nitrative stress are present during endothelial dysfunction. Treatment directed at both stresses might be beneficial in the prevention of atherosclerosis.

Simvastatin impairs the induction of pulmonary fibrosis caused by a western style diet: a preliminary study

The role of an atherogenic diet in causing pulmonary fibrosis has received little attention and simvastatin has been shown to reduce pulmonary fibrosis in animal models. To determine if an atherogenic diet can induce pulmonary fibrosis and whether simvastatin treatment is beneficial by up-regulating heat shock protein 70 and 90. New Zealand white rabbits (n = 15) were divided: Group 1 (control); Group 2 (MC) received a normal rabbit diet with 1% methionine plus 0.5% cholesterol (atherogenic diet). Group 3 received the same diet as the MC group plus 5 mg/kg/day simvastatin orally (MCS). After 4 weeks, the lungs were collected and analysed. Picrosirus red staining of lung interstitial collagen content showed that the atherogenic diet increased fibrosis 2.9-fold (P < 0.05), bronchiole adventitial collagen was increased 2.3-fold (P < 0.05) and bronchiole epithelium was increased 34-fold (P < 0.05), and simvastatin treatment severely reduced this effect (P < 0.05). Western blot analysis showed that the atherogenic diet significantly reduced lung Hsp70 protein by 22% (P < 0.05) and Hsp90 protein by 18% (P < 0.05) and simvastatin treatment did not affect this result. However, aortic hyper-responsiveness to vasoconstrictors (angiotensin II and phenylephrine) were markedly reduced by simvastatin treatment. We report that an atherogenic diet stimulates pulmonary fibrosis and reduces lung Hsp70/Hsp90 protein concentration. Simvastatin impairs this by mechanisms unrelated to Hsp70/Hsp90, but possibly a reduction in angiotensin II receptor or alpha adrenergic receptor pathways. These results could have implications in idiopathic pulmonary fibrosis.

Basic mechanisms in endoplasmic reticulum stress and relation to cardiovascular diseases

The folding process is an important step in protein synthesis for the functional shape or conformation of the protein. The endoplasmic reticulum (ER) is the main organelle for the correct folding procedure, which maintains the homeostasis of the organism. This process is normally well organized under unstressed conditions, whereas it may fail under oxidative and ER stress. The unfolded protein response (UPR) is a defense mechanism that removes the unfolded/misfolded proteins to prevent their accumulation, and two main degradation systems are involved in this defense, including the proteasome and autophagy. Cells decide which mechanism to use according to the type, severity, and duration of the stress. If the stress is too severe and in excess, the capacity of these degradation mechanisms, proteasomal degradation and autophagy, is not sufficient and the cell switches to apoptotic death. Because the accumulation of the improperly folded proteins leads to several diseases, it is important for the body to maintain this balance. Cardiovascular diseases are one of the important disorders related to failure of the UPR. Especially, protection mechanisms and the transition to apoptotic pathways have crucial roles in cardiac failure and should be highlighted in detailed studies to understand the mechanisms involved. This review is focused on the involvement of the proteasome, autophagy, and apoptosis in the UPR and the roles of these pathways in cardiovascular diseases.

Taurine supplementation reduces blood pressure and prevents endothelial dysfunction and oxidative stress in post-weaning protein-restricted rats

INTRODUCTION

Taurine is a sulfur-containing amino acid that exerts protective effects on vascular function and structure in several models of cardiovascular diseases through its antioxidant and anti-inflammatory properties. Early protein malnutrition reprograms the cardiovascular system and is linked to hypertension in adulthood. This study assessed the effects of taurine supplementation in vascular alterations induced by protein restriction in post-weaning rats.

METHODS AND RESULTS

Weaned male Wistar rats were fed normal- (12%, NP) or low-protein (6%, LP) diets for 90 days. Half of the NP and LP rats concomitantly received 2.5% taurine supplementation in the drinking water (NPT and LPT, respectively). LP rats showed elevated systolic, diastolic and mean arterial blood pressure versus NP rats; taurine supplementation partially prevented this increase. There was a reduced relaxation response to acetylcholine in isolated thoracic aortic rings from the LP group that was reversed by superoxide dismutase (SOD) or apocynin incubation. Protein expression of p47phox NADPH oxidase subunit was enhanced, whereas extracellular (EC)-SOD and endothelial nitric oxide synthase phosphorylation at Ser 1177 (p-eNOS) were reduced in aortas from LP rats. Furthermore, ROS production was enhanced while acetylcholine-induced NO release was reduced in aortas from the LP group. Taurine supplementation improved the relaxation response to acetylcholine and eNOS-derived NO production, increased EC-SOD and p-eNOS protein expression, as well as reduced ROS generation and p47phox expression in the aortas from LPT rats. LP rats showed an increased aortic wall/lumen ratio and taurine prevented this remodeling through a reduction in wall media thickness.

CONCLUSION

Our data indicate a protective role of taurine supplementation on the high blood pressure, endothelial dysfunction and vascular remodeling induced by post-weaning protein restriction. The beneficial vascular effect of taurine was associated with restoration of vascular redox homeostasis and improvement of NO bioavailability.

Taurine supplementation does not decrease homocysteine levels and liver injury induced by a choline-deficient diet

AIMS

The aim of this study is to examine the effects of taurine supplementation on homocysteine (Hcy) metabolism and liver injury in rats fed a choline-deficient diet.

MAIN METHODS

Thirty rats were divided into three groups (n=10), to receive one of the following diets for 4 weeks: control diet (C), choline-deficient diet (CDD), or choline-deficient diet supplemented with taurine (CDDT). The CDD and the CDDT consisted of AIN-93 without the recommended choline content of 2.5%, and the CDDT was supplemented by the addition of 2.5% taurine.

KEY FINDINGS

Four weeks of ingesting a CDD resulted in a significant increase in plasma Hcy (50%) as well as a decrease in liver S-adenosylmethionine (SAM) concentration and S-adenosylmethionine/S-adenosylhomocysteine ratio. No changes were found in plasma methionine and cysteine plasma levels compared to control group. Four weeks of ingesting a CDD also caused a significant (P<0.05) increase in hepatic total fat, hepatic malondialdehyde (MDA), and plasma alanine aminotransferase (ALT) levels. In addition, reduced hepatic glutathione (GSH) levels and reduced/oxidized glutathione ratios (GSH/GSSG) were found in rats fed a CDD compared to controls. Taurine supplementation of the CDD normalized genes involved in the remethylation pathway, BHMT and CHDH, which were impaired by CDD alone. However, taurine supplementation failed to prevent CDD-induced Hcy metabolism disturbances and hepatic injury. Also, taurine added to CDD caused decreased expression of PEMT, CHKa, and CHKb, key genes involved in phosphatidylcholine (PC) synthesis and liver fat accumulation.

SIGNIFICANCE

Taurine supplementation failed to ameliorate impaired Hcy metabolism and liver injury caused by CDD intake.

High dietary taurine inhibits myocardial apoptosis during an atherogenic diet: association with increased myocardial HSP70 and HSF-1 but not caspase 3

BACKGROUND AND AIM

Apoptosis is a major cause of myocyte death, and taurine is anti-apoptotic. Heat shock protein 70 (HSP70) (which is regulated by heat shock factor-HSF-1) is also anti-apoptotic, and caspase 3 stimulates the apoptotic pathway. This study investigated whether taurine affects atherogenic diet-induced myocardial apoptosis, and whether HSP70, HSF-1 and caspase 3 are involved.

METHODS

New Zealand white rabbits were divided into 3 groups for 4 weeks according to their diet. Group 1 (control) was fed a normal rabbit diet; Group 2 (MC) received a normal rabbit diet with 1% methionine plus 0.5% cholesterol. Group 3 received MC diet + 2.5% taurine (MCT).

RESULTS

The atherogenic diet did not affect myocardial HSP70 or HSF-1 protein, but increased myocardial apoptotic nuclei to 40% (p < 0.01) versus 7% in con and 12% in MCT (p < 0.01). However, in MCT, myocardial HSP70 expression increased by 42.7% versus con and MC (p = 0.016), HSF-1 by 12% versus con and MC (p < 0.05), and total nuclei count increased by 37% versus MC (p < 0.05). Caspase 3 subunits remained unchanged in all groups, and HSP70 was increased approximately twofold in endothelial layer of arterioles (p = 0.01).

CONCLUSION

This study shows that taurine could reduce myocardial apoptotic nuclei and thus confer myocardial cytoprotection via stimulating myocardial HSP70 via HSF-1 and caspase 3-independent mechanisms.

The UPR in atherosclerosis

Multiple systemic factors and local stressors in the arterial wall can disturb the functions of endoplasmic reticulum (ER), causing ER stress in endothelial cells (ECs), smooth muscle cells (SMCs), and macrophages during the initiation and progression of atherosclerosis. As a protective response to restore ER homeostasis, the unfolded protein response (UPR) is initiated by three major ER sensors: protein kinase RNA-like ER kinase (PERK), inositol-requiring protein 1α (IRE1α), and activating transcription factor 6 (ATF6). The activation of the various UPR signaling pathways displays a temporal pattern of activation at different stages of the disease. The ATF6 and IRE1α pathways that promote the expression of protein chaperones in ER are activated in ECs in athero-susceptible regions of pre-lesional arteries and before the appearance of foam cells. The PERK pathway that reduces ER protein client load by blocking protein translation is activated in SMCs and macrophages in early lesions. The activation of these UPR signaling pathways aims to cope with the ER stress and plays a pro-survival role in the early stage of atherosclerosis. However, with the progression of atherosclerosis, the extended duration and increased intensity of ER stress in lesions lead to prolonged and enhanced UPR signaling. Under this circumstance, the PERK pathway induces expression of death effectors, and possibly IRE1α activates apoptosis signaling pathways, leading to apoptosis of macrophages and SMCs in advanced lesions. Importantly, UPR-mediated cell death is associated with plaque instability and the clinical progression of atherosclerosis. Moreover, UPR signaling is linked to inflammation and possibly to macrophage differentiation in lesions. Therapeutic approaches targeting the UPR may have promise in the prevention and/or regression of atherosclerosis. However, more progress is needed to fully understand all of the roles of the UPR in atherosclerosis and to harness this information for therapeutic advances.

Taurine and atherosclerosis

Taurine is abundantly present in most mammalian tissues and plays a role in many important physiological functions. Atherosclerosis is the underlying mechanism of cardiovascular disease including myocardial infarctions, strokes and peripheral artery disease and remains a major cause of morbidity and mortality worldwide. Studies conducted in laboratory animal models using both genetic and dietary models of hyperlipidemia have demonstrated that taurine supplementation retards the initiation and progression of atherosclerosis. Epidemiological studies have also suggested that taurine exerts preventive effects on cardiovascular diseases. The present review focuses on the effects of taurine on the pathogenesis of atherosclerosis. In addition, the potential mechanisms by which taurine suppress the development of atherosclerosis will be discussed.

The effect of taurine on cholesterol metabolism

The elevated plasma cholesterol level, in particular, LDL cholesterol is regarded as an important risk factor for the development of atherosclerosis and coronary artery disease. A number of studies provide the evidence that taurine has the efficient action to reduce plasma and liver cholesterol concentrations, especially to decrease VLDL and LDL cholesterol in hypercholesterolemia animal induced by high cholesterol diet. Cholesterol lowering effect of taurine is actually involved in the regulatory mechanism of cholesterol and bile acid homeostasis that mediated by CYP7A1, which has become a biomarker for cholesterol metabolism and itself is also regulated by several factors and nuclear receptors. This review summarizes the change of cholesterol concentration in metabolism observed in feeding studies of hypercholesterolemia animal dealing with taurine, and then, addresses the possible metabolic and molecular mechanisms of cholesterol lowering effect by taurine in three aspects, cholesterol clearance from blood circulation, bioconversion of cholesterol to bile acid in liver, and excretion of cholesterol and bile acid from intestine.

Taurine attenuates apoptosis in primary liver cells isolated from Atlantic salmon (Salmo salar)

One of the many functions of taurine is to protect cells against oxidation, by protecting mitochondrial integrity and respiration. Taurine metabolism has attracted much attention in fish nutrition due to the fact that as plant ingredients replace fishmeal, dietary taurine has declined. As the endogenous synthesis of taurine might be too low to protect cells against oxidative stress and apoptosis, the present study aimed to test whether taurine may protect liver cells from apoptosis. Liver cells isolated from Atlantic salmon (Salmo salar) were grown in media supplemented with a physiological concentration of taurine (25 (se0·5) mm) or without any taurine supplementation (14 (se3) μm) for 3 d. To increase oxidation in the mitochondria and maximise any cellular response of taurine supplementation, 100 μm-CdCl2was added or not added to the cells at day 3. At day 4, cells were harvested and assessed for viability. As expected, the addition of CdCl2decreased cell viability without showing any interaction with taurine supplementation. Cells grown in the taurine-supplemented media had lower protein abundance of active caspase-3. In addition, the protein abundance of phosphorylated mitogen-activating phosphokinase (P-p63, P-p42/44 and P-p38) as well as cytochrome P450 were reduced when taurine was added to the media. Cells grown without taurine supplementation had a more condensed chromatin and more smeared DNA, also pointing to a higher apoptosis in these cells. In conclusion, taurine attenuated apoptosis in primary liver cells isolated from Atlantic salmon, and as such, taurine may be conditionally indispensable in Atlantic salmon.

Effect of 9p21.3 coronary artery disease locus neighboring genes on atherosclerosis in mice

BACKGROUND

The human 9p21.3 chromosome locus has been shown to be an independent risk factor for atherosclerosis in multiple large-scale genome-wide association studies, but the underlying mechanism remains unknown. We set out to investigate the potential role of the 9p21.3 locus neighboring genes, including Mtap, the 2 isoforms of Cdkn2a, p16Ink4a and p19Arf, and Cdkn2b, in atherosclerosis using knockout mice models.

METHODS AND RESULTS

Gene-targeted mice for neighboring genes, including Mtap, Cdkn2a, p19Arf, and Cdkn2b, were each bred to mice carrying the human APO*E3 Leiden transgene that sensitizes the mice for atherosclerotic lesions through elevated plasma cholesterol. We found that the mice heterozygous for Mtap developed larger lesions compared with wild-type mice (49623±21650 versus 18899±9604 μm(2) per section [mean±SD]; P=0.01), with morphology similar to that of wild-type mice. The Mtap heterozygous mice demonstrated changes in metabolic and methylation profiles and CD4(+) cell counts. The Cdkn2a knockout mice had smaller lesions compared with wild-type and heterozygous mice, and there were no significant differences in lesion size in p19Arf and Cdkn2b mutants compared with wild type. We observed extensive, tissue-specific compensatory regulation of the Cdkn2a and Cdkn2b genes among the various knockout mice, making the effects on atherosclerosis difficult to interpret.

CONCLUSIONS

Mtap plays a protective role against atherosclerosis, whereas Cdkn2a appears to be modestly proatherogenic. However, no relation was found between the 9p21 genotype and the transcription of 9p21 neighboring genes in primary human aortic vascular cells in vitro. There is extensive compensatory regulation in the highly conserved 9p21 orthologous region in mice.

Hydrogen sulfide in the pathogenesis of atherosclerosis and its therapeutic potential

Hydrogen sulfide (H(2)S) was the third gaseous transmitter to be discovered, along with nitric oxide and carbon monoxide, and has been proposed to be involved in numerous physiological processes and pathology of various diseases. Hyperhomocysteinemia is an independent risk factor for cardiovascular disease, including atherosclerosis. Atherosclerosis is characterized by multiple key events including endothelial dysfunction, monocyte infiltration and their differentiation into macrophages, conversion of lesion-resident macrophages into foam cells, and smooth muscle cell proliferation. Increasing evidence has indicated that H(2)S plays a potentially significant role in all of these biological processes and that malfunction of H(2)S homeostasis may contribute to the pathogenesis of atherosclerosis. Experiments have demonstrated that H(2)S supplementation ameliorated many of these atherogenic processes and hence, such supplementation potentially may prove to be of therapeutic benefit in the prevention or treatment of atherosclerosis. H(2)S levels may be induced by the administration of H(2)S or H(2)S donors, or alternatively be reduced by the administration of specific cystathionine β-synthase or cystathionine γ-lyase inhibitors. However, issues remain with the potential use of currently available H(2)S-modulating agents in a clinical setting. This review will provide a description of the current literature on the involvement of H(2)S in these key aspects of vascular biology that contribute to the development of atherosclerosis, as well as the therapeutic potential of currently available H(2)S-modulating agents.