Exogenous (Pomegranate Juice) or Endogenous (Paraoxonase1) Antioxidants Decrease Triacylglycerol Accumulation in Mouse Cardiovascular Disease-Related Tissues

Paraoxonase 1 Ameliorates Renal Lipotoxicity by Activating Lipophagy and Inhibiting Pyroptosis

Several studies in recent years have shown that lipid overload causes lipotoxic damage to the kidney, and oxidative stress, inflammation, and autophagic arrest are all important mechanisms of renal lipotoxicity. However, effective measures with therapeutic effects on renal lipotoxicity are limited. The present study indicated the protective effect of the paraoxonase 1 (PON1) against renal lipotoxicity in high-fat diet-fed scavenger receptor class B type I-deficient (SR-BI-/-) mice. The results showed that SR-BI-/- mice exhibited significant renal pathologic characteristics, such as oxidative stress, inflammation, and fibrosis, under a normal chow diet, and were accompanied by dyslipidemia and reduced plasma PON1 activity and renal PON1 levels. PON1 overexpression significantly attenuated the above pathologic changes in the kidneys of SR-BI-/- mice fed with a high-fat diet. Mechanistically, PON1 may ameliorate renal oxidative stress by reducing reactive oxygen species production, reduce renal lipid accumulation by inhibiting AKT/mechanistic target of rapamycin kinase pathway to activate lipophagy, and reduce the occurrence of inflammation and cell death by inhibiting Nod-like receptor family protein 3 inflammasome-mediated pyroptosis. The present study is the first to show that PON1 overexpression can effectively alleviate renal lipotoxicity injury, and PON1 may be a promising therapeutic strategy for the treatment of renal lipotoxicity-related diseases.

Induction of glutathione biosynthesis by glycine-based treatment mitigates atherosclerosis

Lower circulating levels of glycine are consistently reported in association with cardiovascular disease (CVD), but the causative role and therapeutic potential of glycine in atherosclerosis, the underlying cause of most CVDs, remain to be established. Here, following the identification of reduced circulating glycine in patients with significant coronary artery disease (sCAD), we investigated a causative role of glycine in atherosclerosis by modulating glycine availability in atheroprone mice. We further evaluated the atheroprotective potential of DT-109, a recently identified glycine-based compound with dual lipid/glucose-lowering properties. Glycine deficiency enhanced, while glycine supplementation attenuated, atherosclerosis development in apolipoprotein E-deficient (Apoe^−/−) mice. DT-109 treatment showed the most significant atheroprotective effects and lowered atherosclerosis in the whole aortic tree and aortic sinus concomitant with reduced superoxide. In Apoe^−/− mice with established atherosclerosis, DT-109 treatment significantly reduced atherosclerosis and aortic superoxide independent of lipid-lowering effects. Targeted metabolomics and kinetics studies revealed that DT-109 induces glutathione formation in mononuclear cells. In bone marrow-derived macrophages (BMDMs), glycine and DT-109 attenuated superoxide formation induced by glycine deficiency. This was abolished in BMDMs from glutamate-cysteine ligase modifier subunit-deficient (Gclm^−/-) mice in which glutathione biosynthesis is impaired. Metabolic flux and carbon tracing experiments revealed that glycine deficiency inhibits glutathione formation in BMDMs while glycine-based treatment induces de novo glutathione biosynthesis. Through a combination of studies in patients with CAD, in vivo studies using atherosclerotic mice and in vitro studies using macrophages, we demonstrated a causative role of glycine in atherosclerosis and identified glycine-based treatment as an approach to mitigate atherosclerosis through antioxidant effects mediated by induction of glutathione biosynthesis.

Metabolic Syndrome in an Aging Society - Role of Oxidant-Antioxidant Imbalance and Inflammation Markers in Disentangling Atherosclerosis

INTRODUCTION

The prevalence of metabolic syndrome among the elderly population is growing. The elements of metabolic syndrome in an aging society are currently being researched. Atherosclerosis is a slow process in which the first symptoms may be observed after many years. The mechanisms underlying the progression of atherosclerosis are oxidative stress and inflammation. Inflammation and oxidative stress are associated with the increased incidence of metabolic syndrome. Taking the above into consideration, metabolic syndrome is thought to be a clinical equivalent of atherosclerosis.

AIM

The aim of this paper is to review the impact of the interplay of oxidant-antioxidant and inflammation markers in metabolic syndrome in general as well as its components in the pathophysiology which underlies development of atherosclerosis in elderly individuals.

METHODS

A systematic scan of online resources designed for elderly (≥65 years) published from 2005 to the end of 2020 were reviewed. This was supplemented with grey literature and then all resources were narratively analyzed. The analysis included the following terms: "atherosclerosis or metabolic syndrome" and "oxidative stress or inflammation" and "elderly" to find reports of atherosclerotic disease from asymptomatic to life-threatening among the elderly population with metabolic syndrome .

RESULTS

The work summarizes articles that were applicable to this study, including systematic reviews, qualitative studies and opinion pieces. Current knowledge focuses on monitoring the inflammation and oxidant-antioxidant imbalance in disentangling atherosclerosis in patients diagnosed with metabolic syndrome. The population-based studies described inflammation, increased oxidative stress and weak antioxidant defense systems as the mechanisms underlying atherosclerosis development. Moreover, there are discussions that these targets could potentially be a point of intervention to reduce the development of atherosclerosis in the elderly, especially those with altered glucose and lipid metabolism. Specific markers may be used as an approach for the prevention and lifestyle modification of atherosclerotic disease in such population.

CONCLUSION

Metabolic syndrome and its components are important contributors in the progression of atherosclerotic disease in the elderly population but constant efforts should be made to broaden our knowledge of elderly groups who are the most susceptible for the development of atherosclerosis complications.

Cynandione A Alleviates Neuropathic Pain Through α7-nAChR-Dependent IL-10/β-Endorphin Signaling Complexes

Cynandione A, an acetophenone isolated from Cynanchum Wilfordii Radix, exhibits antineuropathic pain effect. This study further explored the target molecule and signaling mechanisms underlying cynandione-A-induced antineuropathic pain. Intrathecal injection of cynandione A significantly attenuated mechanical allodynia in neuropathic rats and substantially increased spinal expression of IL-10 and β-endorphin but not dynorphin A. Cynandione A treatment also enhanced expression of IL-10 and β-endorphin but not α7 nicotinic acetylcholine receptors (nAChRs) in cultured microglia. The IL-10 antibody attenuated cynandione-A-induced spinal or microglial gene expression of β-endorphin and mechanical allodynia, whereas the β-endorphin antiserum blocked cynandione-A-induced mechanical antiallodynia but not spinal or microglial IL-10 gene expression. The α7 nAChR antagonist methyllycaconitine significantly reduced cynandione-A-induced mechanical antiallodynia and spinal or microglial expression of IL-10 and β-endorphin. Furthermore, cynandione A stimulated microglial phosphorylation of PKA, p38, and CREB in an α7-nAChR-dependent manner, and treatment with their inhibitors attenuated cynandione-A-induced mechanical antiallodynia and spinal or microglial expression of IL-10 and β-endorphin. In addition, cynandione A stimulated spinal phosphorylation of the transcription factor STAT3, which was inhibited by methyllycaconitine, the PKA activation inhibitor or IL-10 antibody. The STAT3 inhibitor NSC74859 also abolished cynandione-A-induced mechanical antiallodynia and spinal expression of β-endorphin. These findings suggest that cynandione A suppresses neuropathic pain through α7-nAChR-dependent IL-10/β-endorphin signaling pathway in spinal microglia.

Microencapsulated Pomegranate Reverts High-Density Lipoprotein (HDL)-Induced Endothelial Dysfunction and Reduces Postprandial Triglyceridemia in Women with Acute Coronary Syndrome

(1) Background: the composition of high-density lipoproteins (HDL) becomes altered during the postprandial state, probably affecting their functionality vis-à-vis the endothelium. Since acute coronary syndrome (ACS) in women is frequently associated with endothelial dysfunction, it is likely that HDL are unable to improve artery vasodilation in these patients. Therefore, we characterized HDL from women with ACS in fasting and postprandial conditions. We also determined whether microencapsulated pomegranate (MiPo) reverts the HDL abnormalities, since previous studies have suggested that this fruit improves HDL functionality. (2) Methods: Eleven women with a history of ACS were supplemented daily with 20 g of MiPo, for 30 days. Plasma samples were obtained during fasting and at different times, after a lipid load test to determine the lipid profile and paraoxonase–1 (PON1) activity. HDL were isolated by sequential ultracentrifugation to determine their size distribution and to assess their effect on endothelial function, by using an in vitro model of rat aorta rings. (3) Results: MiPo improved the lipid profile and increased PON1 activity, as previously reported, with fresh pomegranate juice. After supplementation with MiPo, the incremental area under the curve of triglycerides decreased to half of the initial values. The HDL distribution shifted from large HDL to intermediate and small-size particles during the postprandial period in the basal conditions, whereas such a shift was no longer observed after MiPo supplementation. Consistently, HDL isolated from postprandial plasma samples hindered the vasodilation of aorta rings, and this endothelial dysfunction was reverted after MiPo consumption. (4) Conclusions: MiPo exhibited the same beneficial effects on the lipid profile and PON1 activity as the previously reported fresh pomegranate. In addition, MiPo supplementation reverted the negative effects of HDL on endothelial function generated during the postprandial period in women with ACS.