Labedipinedilol-A prevents lysophosphatidylcholine-induced vascular smooth muscle cell death through reducing reactive oxygen species production and anti-apoptosis

Arrhythmia onsets triggered by acute myocardial ischemia are not mediated by lysophosphoglycerides accumulation in ventricular myocardium

Lysophosphoglycerides (LPLs) have been reported to accumulate in myocardium and serve as a cause of arrhythmias in acute myocardial ischemia. However, in this study we found that LPLs level in the ventricular myocardium was decreased by the onset of acute myocardial ischemia in vivo in rats. Decreasing of LPLs level in left ventricular myocardium, but not right, was observed within 26 min of left myocardial ischemia, regardless of whether arrhythmias were triggered. Lower LPLs level in the ventricular myocardium was also observed in aconitine-simulated ventricular fibrillation (P < 0.0001) and ouabain-simulated III° atrioventricular block (P < 0.0001). Shot-lasting electric shock, e.g., ≤ 40 s, decreased LPLs level, while long-lasting, e.g., 5 min, increased it (fold change = 2.27, P = 0.0008). LPLs accumulation was observed in long-lasting myocardial ischemia, e.g., 4 h (fold change = 1.20, P = 0.0012), when caspase3 activity was elevated (P = 0.0012), indicating increased cell death, but not coincided with higher frequent arrhythmias. In postmortem human ventricular myocardium, differences of LPLs level in left ventricular myocardium was not observed among coronary artery disease- and other heart diseases-caused sudden death and non-heart disease caused death. LPLs level manifested a remarkable increasing from postmortem 12 h on in rats, thus abolishing the potential for serving as biomarkers of sudden cardiac death. Token together, in this study we found that LPLs in ventricular myocardium were initially decreased by the onset of ischemia, LPLs accumulation do not confer arrhythmogenesis during acute myocardial ischemia. It is necessary to reassess the roles of LPLs in myocardial infarction.

Research Advance of Chinese Medicine in Treating Atherosclerosis: Focus on Lipoprotein-Associated Phospholipase A2

As a serious cardiovascular disease, atherosclerosis (AS) causes chronic inflammation and oxidative stress in the body and poses a threat to human health. Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a member of the phospholipase A2 (PLA2) family, and its elevated levels have been shown to contribute to AS. Lp-PLA2 is closely related to a variety of lipoproteins, and its role in promoting inflammatory responses and oxidative stress in AS is mainly achieved by hydrolyzing oxidized phosphatidylcholine (oxPC) to produce lysophosphatidylcholine (lysoPC). Moreover, macrophage apoptosis within plaque is promoted by localized Lp-PLA2 which also promotes plaque instability. This paper reviews those researches of Chinese medicine in treating AS via reducing Lp-PLA2 levels to guide future experimental studies and clinical applications related to AS.

Vitamin D Receptor Activation Targets ROS-Mediated Crosstalk Between Autophagy and Apoptosis in Hepatocytes in Cholestasic Mice

BACKGROUND & AIMS

Observational epidemiologic studies have associated vitamin D deficiency with cholestasis. We reported previously that activation of the vitamin D/vitamin D receptor (VDR) axis in cholangiocytes mitigates cholestatic liver injury by remodeling the damaged bile duct. However, the function of VDR in hepatocytes during cholestasis remains unclear.

METHODS

Paricalcitol (VDR agonist, 200 ng/kg) was injected intraperitoneally into bile duct-ligated mice every other day for 5 days. Primary hepatocytes and HepG2 hepatoma cells were transfected with Vdr short hairpin RNA, control short hairpin RNA, Vdr plasmid, control vector, Atg5 small interfering RNA (siRNA), and control siRNA. Liver histology, cell proliferation, and autophagy were evaluated.

RESULTS

Treatment with the VDR agonist paricalcitol improved liver injury in bile duct-ligated mice by up-regulating VDR expression in hepatocytes, which in turn reduced hepatocyte apoptosis by inhibiting reactive oxygen species (ROS) generation via suppressing the Ras-related C3 botulinum toxin substrate 1/reduced nicotinamide adenine dinucleotide phosphate oxidase 1 pathway. Mechanistically, upon exposure to an ROS-inducing compound, Vdr siRNA contributed to apoptosis, whereas the Vdr overexpression caused resistance to apoptosis. Interestingly, up-regulated VDR expression also increased the generation of autophagosomes and macroautophagic/autophagic flux, which was the underlying mechanism for reduced apoptosis following VDR activation. Autophagy depletion impaired the positive effects of VDR overexpression, whereas autophagy induction was synergystic with VDR overexpression. Importantly, up-regulation of VDR promoted autophagy activation by suppressing the activation of the extracellular signal-regulated kinase (ERK)/p38 mitogen-activated protein kinase (p38MAPK) pathway. Thus, a p38MAPK inhibitor abrogated the Vdr siRNA-induced decrease in autophagy and the Vdr siRNA-induced increase in apoptosis. In contrast, a Mitogen-activated protein kinase kinase (MEK)/ERK activator prevented the enhancement of autophagy and decreased apoptosis following Vdr overexpression. Moreover, the ROS inhibitor N-acetylcystein (NAC) blocked Vdr siRNA-enhanced activation of the ERK/p38MAPK pathway.

CONCLUSIONS

VDR activation mitigated liver cholestatic injury by reducing autophagy-dependent hepatocyte apoptosis and suppressing the activation of the ROS-dependent ERK/p38MAPK pathway. Thus, VDR activation may be a potential target for the treatment of cholestatic liver disease.

Role of autophagy in lysophosphatidylcholine-induced apoptosis in mouse Leydig cells

Lysophosphatidylcholine (LPC), a major class of glycerophospholipids ubiquitously present in most tissues, plays a dominant role in many diseases, while it is still unknown about the potential mechanism of LPC affecting the testicular Leydig cells. In the present study, mouse TM3 Leydig cells in vitro were treated with LPC for 48 h. LPC was found to significantly induce apoptosis and oxidative stress of mouse TM3 Leydig cells; while inhibition of oxidative stress by N-acetyl-L-cysteine, an inhibitor of oxidative stress, could rescue the induction of apoptosis, indicating that LPC induced apoptosis of mouse TM3 Leydig cells via oxidative stress. Interestingly, LPC was showed to inhibit autophagy; however, induction of autophagy by rapamycin significantly alleviated the induction of apoptosis by LPC. Taken together, oxidative stress was involved in LPC-induced apoptosis of mouse TM3 Leydig cells, and autophagy might play a protective role in LPC-induced apoptosis.

Role of Autophagy in Lysophosphatidylcholine-Induced Apoptosis of Mouse Ovarian Granulosa Cells

Lysophosphatidylcholine (LPC), also known as lysolecithin, is one of the major components of oxidized low-density lipoproteins (ox-LDL). In the pathogenetic process of diverse diseases, LPC acts as a significant lipid mediator. However, no evidence shows that LPC can affect the female reproductive system. In our study, we found that LPC inhibited the cell viability of primary mouse ovarian granulosa cells. Meanwhile, LPC was shown to induce apoptosis, which is accompanied by an increase in apoptosis-related protein levels, such as cleaved caspase-3, cleaved caspase-8 and Bax, as well as a decrease in Bcl-2. The total numbers of early and late apoptotic cells also increased in the LPC-treated cells. These results indicated that LPC could induce apoptosis of mouse ovarian granulosa cells. Furthermore, the increase in autophagy-related protein levels and the number of autophagic vesicles suggested that LPC could induce autophagy. The inhibition of oxidative stress by N-acetyl-L-cysteine (NAC) could rescue the induction of apoptosis and autophagy by LPC, which indicated that oxidative stress was involved in LPC-induced apoptosis and autophagy. Interestingly, the inhibition of autophagy by 3-MA could reserve the inhibition of cell viability and the induction of apoptosis by LPC. In conclusion, oxidative stress was involved in LPC-induced apoptosis, whileautophagy of mouse ovarian granulosa cells and the inhibition of autophagy could alleviate LPC-induced apoptosis.

Cinaciguat Prevents Postnatal Closure of Ductus Arteriosus by Vasodilation and Anti-remodeling in Neonatal Rats

Closure of the ductus arteriosus (DA) involves vasoconstriction and vascular remodeling. Cinaciguat, a soluble guanylyl cyclase (sGC) activator, was reported with vasodilatory and anti-remodeling effects on pulmonary hypertensive vessels. However, its effects on DA are not understood. Therefore, we investigated whether cinaciguat regulated DA patency and examined its underlying mechanisms. In vivo, we found that cinaciguat (10 mg/kg, i.p. at birth) prevented DA closure at 2 h after birth with luminal patency and attenuated intimal thickening. These anti-remodeling effects were associated with enhanced expression of cyclic guanosine monophosphate (cGMP) in DA. Ex vivo, cinaciguat dilated oxygen-induced DA constriction dose-dependently. Such vasodilatory effect was blunted by KT-5823, a PKG inhibitor. In DA smooth muscle cells (DASMCs), we further showed that cinaciguat inhibited angiotensin II (Ang II)-induced proliferation and migration of DASMCs. In addition, cinaciguat inhibited Ang II-induced mitochondrial reactive oxygen species (ROS) production. Finally, Ang II-activated MAPKs and Akt were also inhibited by cinaciguat. In conclusion, cinaciguat prevents postnatal DA closure by vasodilation and anti-remodeling through the cGMP/PKG pathway. The mechanisms underlying anti-remodeling effects include anti-proliferation and anti-migration, with attenuation of mitochondrial ROS production, MAPKs, and Akt signaling. Thus, this study implicates that sGC activation may be a promising novel strategy to regulate DA patency.

Untargeted and targeted metabolomics profiling reveals the underlying pathogenesis and abnormal arachidonic acid metabolism in laying hens with fatty liver hemorrhagic syndrome

As a metabolic disease, fatty liver hemorrhagic syndrome (FLHS) has become the major factor responsible for the noninfectious cause of mortality in laying hens, which lead to huge economic losses to poultry industry. However, the pathogenesis of FLHS remains unclear. The aim of present study was to identify novel liver metabolites associated with FLHS. Twenty healthy Chinese commercial Jing Fen laying hens aged 90 d were used in present study. After acclimatization for 2 wk, the hens were divided into 2 treatments (n = 10): control group (normal diet) and FLHS group (high-energy low-protein diet). The experiment lasted for 48 d, and the laying hens were killed for blood and liver sampling at the end of the experiment. Blood biochemical indicators and liver pathological changes were examined. Meanwhile, the changes in liver metabolic profile were investigated with the application of metabolomics approach. Significant increased levels of alanine aminotransferase, aspartate aminotransferase, low density lipoprotein, total cholesterol and triglycerides, decreased high density lipoprotein (P < 0.01), and hepatic steatosis were observed in hens of FLHS group, which suggested FLHS was successfully established in this study. Distinct changes in metabolite patterns in liver between control and FLHS group were observed by partial least-squares discriminant analysis. In total, 42 liver metabolites including tyrosine, glutathione, carnitine, linoleic acid, uric acid, arachidonic acid (ARA), lactate and lysophosphatidylcholine (14: 0) were identified and considered to be related with pathogenesis of FLHS. Pathway analysis revealed that these metabolites were mainly involved in amino acid metabolism, fatty acid metabolism, ARA metabolism, glucose metabolism and glycerophospholipid metabolism. Furthermore, targeted metabolomics found that ARA metabolites such as prostaglandins and hydroxyeicosatetraenoic acids were significantly increased in FLHS group (P < 0.05). In conclusion, our data showed that liver metabolites and ARA metabolism were linked to the pathophysiology of FLHS, which provided a basis for understanding the pathogenesis of FLHS in laying hens.

Extracellular heat shock protein HSC70 protects against lipopolysaccharide-induced hypertrophic responses in rat cardiomyocytes

We have recently shown that exogenous administration of extracellular heat shock protein HSC70, a previously recognized intracellular chaperone protein, can protect against LPS-induced cardiac dysfunction through anti-inflammatory actions. However, whether it can also exert anti-hypertrophic effect is unknown. The present study was aimed to investigate the efficacy of HSC70 against cardiac hypertrophy and its underlying molecular mechanisms. Cardiomyocytes were isolated from the cardiac ventricles of neonatal Wistar rats and LPS (1 μg/mL) was used to induce the hypertrophic responses. We found that HSC70 (0.1, 1 and 5 μg/mL) pretreatment attenuated LPS-induced cardiomyocyte hypertrophy dose-dependently. In addition, HSC70 mitigated LPS-induced inflammatory mediators including TNF-α, IL-6, NO, iNOS and COX-2, with down-regulated protein expression of MMP-2 and MMP-9. Moreover, HSC70 repressed LPS-induced signaling of MAPK and Akt. Finally, HSC70 inhibited NF-κB subunit p65, and the DNA binding activity of NF-κB. Taken together, these findings suggest that in vitro HSC70 can exert anti-hypertrophic effects through inhibition of pro-inflammatory mediators, which are potential mediated by the down-regulation of MAPK, Akt and NF-κB signaling pathways. In conclusion, extracellular HSC70 may be a novel pharmacologic strategy in the management of cardiac hypertrophy.

B-type natriuretic peptide prevents postnatal closure of ductus arteriosus by both vasodilation and anti-remodeling in neonatal rats

The physiologic process of postnatal ductus arteriosus (DA) closure consists of vasoconstriction followed by vascular remodeling. We have recently reported that B-type natriuretic peptide (BNP), a potent vasodilator, also has anti-remodeling effects in pulmonary vasculature. However, its effects on DA have not been elucidated. We investigated whether BNP can prevent DA closure, and if so, the underlying mechanisms. Using in vivo studies, we examined effects of BNP (10 mg/kg, ip at birth) on DA closure in neonatal rats within 4 h after birth. We found that in control rats, the DA spontaneously closed at 4 h with a decreased DA diameter, enhanced intimal thickening, and luminal occlusion. BNP prevented DA closure at 4 h with a preserved DA diameter, attenuated intimal thickening, and preserved luminal patency. Ex vivo, BNP attenuated oxygen-induced vasoconstriction of isolated DA rings of newborn rats. These vasodilating effects were blunted by Rp-8-Br-PET-cGMPS, a cGMP inhibitor. In vitro, BNP inhibited angiotensin II (Ang II)-induced proliferation and migration of DA smooth muscle cells (DASMCs). BNP inhibited Ang II-induced mitochondrial reactive oxygen species (ROS) production and calcium overload in DASMCs. Finally, BNP inhibited Ang II-induced ERK1/2 activation. These in vitro effects were antagonized by Rp-8-Br-PET-cGMPS. In conclusion, BNP prevents postnatal DA closure by both vasodilation and anti-remodeling through the cGMP pathway. The mechanisms underlying anti-remodeling effects include anti-poliferation and anti-migration, with attenuation of mitochondrial ROS production and intracellular calcium and ERK1/2 signaling. Therefore, the BNP/cGMP pathway can be a promising therapeutic target for clinical management of DA patency.

TRPC1/TRPC3 channels mediate lysophosphatidylcholine-induced apoptosis in cultured human coronary artery smooth muscles cells

The earlier study showed that lysophosphatidylcholine (lysoPC) induced apoptosis in human coronary artery smooth muscle cells (SMCs); however, the related molecular mechanisms are not fully understood. The present study investigated how lysoPC induces apoptosis in cultured human coronary artery SMCs using cell viability assay, flow cytometry, confocal microscopy, and molecular biological approaches. We found that lysoPC reduced cell viability in human coronary artery SMCs by eliciting a remarkable Ca2+ influx. The effect was antagonized by La3+, SKF-96365, or Pyr3 as well as by silencing TRPC1 or TRPC3. Co-immunoprecipitation revealed that TRPC1 and TRPC3 had protein-protein interaction. Silencing TRPC1 or TRPC3 countered the lysoPC-induced increase of Ca2+ influx and apoptosis, and the pro-apoptotic proteins Bax and cleaved caspase-3 and decrease of the anti-apoptotic protein Bcl-2 and the survival kinase pAkt. These results demonstrate the novel information that TRPC1/TRPC3 channels mediate lysoPC-induced Ca2+ influx and apoptosis via activating the pro-apoptotic proteins Bax and cleaved caspase-3 and inhibiting the anti-apoptotic protein Bcl-2 and the survival kinase pAkt in human coronary artery SMCs, which implies that TRPC1/TRC3 channels may be the therapeutic target of lysoPC-induced disorders such as atherosclerosis.

A study on effect of curcumin on anticerebral aneurysm in the male albino rats

INTRODUCTION

This study investigated the curcumin effect on the cerebral aneurysm. Apoptosis is known to play a fundamental role in the pathogenesis of a cerebral aneurysm. Therefore, we investigated the effect of curcumin on apoptosis of smooth muscle cells of a cerebral aneurysm-induced male albino rats.

METHODS

In this study, the cerebral aneurysm has been induced in the male albino rats by the CaCl₂ administration. After cerebral aneurysm induction, smooth muscle cells were isolated. Cells were treated with curcumin (25 & 50 mg/kg bwt) for 48 hr.

RESULTS

Curcumin reduced altered mitochondrial morphology significantly, evidenced through fluorescence and confocal study. Curcumin treatment reduced the expression of p53, caspase-3, and bax/bxl-2 ratio significantly. Curcumin treatment also reversed the cellular architecture of smooth muscle cell wall significantly. Fluorescence and the confocal study confirmed the reduction in apoptosis in a cerebral aneurysm-induced smooth muscle cells of male albino rats.

CONCLUSION

Taking all these data together, it may suggest that the curcumin could significantly reduce the CaCl₂-induced cerebral aneurysm through the inhibition of cell apoptosis in the cells.

Lysophosphatidylcholine activates the Akt pathway to upregulate extracellular matrix protein production in human aortic valve cells

BACKGROUND

Overproduction of extracellular matrix (ECM) protein by aortic valve interstitial cells (AVICs) plays an important role in valvular sclerosis (thickening) associated with the early pathobiology of aortic stenosis. Accumulation of oxidized low-density lipoprotein (oxLDL) is observed in sclerotic aortic valve and may have a mechanistic role in valvular disease progression. Lysophosphatidylcholine (LysoPC) is a component of oxLDL and has multiple biological activities. This study was to test the hypothesis that oxLDL and LysoPC upregulate ECM protein production in human AVICs.

METHODS AND RESULTS

AVICs were isolated from normal human aortic valves. Cells were treated with oxLDL (40 μg/mL) or LysoPC (40 μmol/L). Immunoblotting was applied to analyze ECM proteins (collagens I and III and biglycan) in cell lysate and Picrosirius red staining was used to examine collagen deposition. Both oxLDL and LysoPC upregulated the production of biglycan and collagen I. The upregulation of ECM proteins by LysoPC was preceded by the phosphorylation of Akt and ERK1/2. Inhibition of Akt markedly reduced the effect of LysoPC on ECM protein production and collagen deposition. However, inhibition of ERK1/2 had no effect.

CONCLUSIONS

LysoPC upregulates the production of biglycan and collagen I in human AVICs and may mediate the effect of oxLDL on ECM protein production. The Akt pathway appears to be critical in mediating the effect of LysoPC. oxLDL accumulation and generation of LysoPC in the aortic valve tissue may contribute to the mechanism of valvular sclerosis associated with the development and progression of aortic stenosis.

Gamma-secretase Inhibitor Prevents Proliferation and Migration of Ductus Arteriosus Smooth Muscle Cells through the Notch3-HES1/2/5 Pathway

Patent ductus arteriosus (PDA) can cause morbidity and mortality in neonates. Vascular remodeling, characterized by proliferation and migration of smooth muscle cells (SMCs), is an essential process for postnatal DA closure. Notch signaling is an important mediator of vascular remodelling but its role in DA is unkonwn. We investigated the effects and underlying mechanisms of γ-secretase inhibitor DAPT, a Notch signaling inhibitor on angiotensin II (Ang II)-induced proliferation and migration of DASMCs. Proliferation and migration of DASMCs cultured from neonatal Wistar rats were induced by Ang II, with or without DAPT pre-treatment. In addition, potential underlying mechanisms including cell cycle progression, Ca(2+) influx, reactive oxygen species (ROS) production, signal transduction of MAPK and Akt, and Notch receptor with its target gene pathway were examined. We found that DAPT inhibited Ang II-induced DASMCs proliferation and migration dose dependently. DAPT also arrested the cell cycle progression in the G0/G1-phase, and attenuated calcium overload and ROS production caused by Ang II. Moreover, DAPT inhibited nuclear translocation of Notch3 receptor intracellular domain, with decreased expression of its down-stream genes including HES1, HES2 and HES5. Finally, Ang II-activated ERK1/2, JNK and Akt were also counteracted by DAPT. In conclusion, DAPT inhibits Ang II-induced DASMCs proliferation and migration. These effects are potentially mediated by decreased calcium influx, reduced ROS production, and down-regulation of ERK1/2, JNK and Akt, through the Notch3-HES1/2/5 pathway. Therefore, Notch signaling has a role in DA remodeling and may provide a target pathway for therapeutic intervention of PDA.

Lysophosphatidylcholine increases the neurotoxicity of Alzheimer's amyloid β1-42 peptide: role of oligomer formation

Oligomer formation is considered as a critical process for the neurotoxic effects of Alzheimer's amyloid β (Aβ) peptide. Previously we have demonstrated that lysophosphatidylcholine (LPC) increases the oligomer formation of Aβ1-42, the major Aβ peptide found Alzheimer's disease (AD) lesions. In this study, we have investigated whether LPC affects the neurotoxic effects of Aβ1-42 in a neuronal cell line (A1) culture. Dimethyl thiazolyl diphenyl tetrazolium (MTT) assay revealed that up to 10μM concentration, LPC did not affect A1 cell viability. Aβ1-42 decreased the cell viability, and such effect was dose dependently enhanced by LPC. However, neither LPC nor Aβ1-42, alone or in combination increased lactate dehydrogenase (LDH) release from A1 cells after 24-h treatment. Terminal deoxynucleotidyl transferase dUTP-biotin nick-end-labeling (TUNEL) assay showed that LPC increased Aβ1-42-induced apoptotic cell number. To determine the underlying mechanisms, the proteins implicated in apoptosis pathways including Bcl-2- and caspase-family were analyzed by Western blotting. The results demonstrated that Aβ1-42 decreased Bcl-2 in A1 cells at 24h, whereas LPC had no effect at any time point. Both LPC and Aβ1-42 increased Bax level at 24h, and their combined stimulation showed a synergistic effect. Similar synergistic effect of LPC and Aβ1-42 on caspase9 activation was observed. Dot blot immunoassay and Western blotting showed that LPC augmented Aβ1-42 oligomer formation in cell culture medium. Removing LPC-induced early-formed Aβ1-42 oligomer from the culture medium by immunoprecipitation decreased active caspase9 level and neurotoxicity, as revealed by Western blotting and MTT assay. Furthermore, dihydroethidium (DHE) assay showed that Aβ1-42 increased reactive oxygen species level in A1 cells, such effect was further enhanced by LPC. Thus, our results demonstrated that LPC increased the oligomer formation process of Aβ1-42 peptide in culture condition, and consequently increased apoptotic neuronal death. Such process might be important for the pathogenesis of AD, and inhibition of LPC generation could be a therapeutic target for the disease.

B-type natriuretic peptide inhibits angiotensin II-induced proliferation and migration of pulmonary arterial smooth muscle cells

Pulmonary vascular remodeling, characterized by disordered proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs), is a pathognomonic feature of pulmonary arterial hypertension. Thus, pharmacologic strategy targeting on anti-proliferation and anti-migration of PASMCs may have therapeutic implications for PAH. Here we investigated the effects and underlying mechanisms of B-type natriuretic peptide (BNP) on angiotensin II (Ang II)-induced proliferation and migration of PASMCs. Proliferation and migration of PASMCs cultured from Wistar rats were induced by Ang II, with or without BNP treatment. In addition, potential underlying mechanisms including cell cycle progression, Ca(2+) overload, reactive oxygen species (ROS) production, signal transduction of MAPK and Akt, and the cGMP/PKG pathway were examined. We found that BNP inhibited Ang II-induced PASMCs proliferation and migration dose dependently. BNP could also arrest the cell cycle progression in the G0/G1-phase. In addition, BNP attenuated intracellular calcium overload caused by Ang II. Moreover, Ang II-induced ROS production was mitigated by BNP, with associated down-regulation of NAD(P)H oxidase 1 (Nox1) and reduced mitochondrial ROS production. Finally, Ang II-activated MAPKs and Akt were also counteracted by BNP. Of note, all these effects of BNP were abolished by a PKG inhibitor (Rp-8-Br-PET-cGMPS). In conclusion, BNP inhibits Ang II-induced PASMCs proliferation and migration. These effects are potentially mediated by decreased calcium influx, reduced ROS production by Nox1 and mitochondria, and down-regulation of MAPK and Akt signal transduction, through the cGMP/PKG pathway. Therefore, this study implicates that BNP may have a therapeutic role in pulmonary vascular remodeling.

Baicalein Inhibits HMGB1 Release and MMP-2/-9 Expression in Lipopolysaccharide-Induced Cardiac Hypertrophy

Myocardial dysfunction, a common complication after sepsis, significantly contributes to the death of patients with septic shock. In the search for potentially effective drugs to decrease mortality from sepsis, we investigated the cardioprotective effects of baicalein, a flavonoid present in the root of Scutellaria baicalensis, on lipopolysaccharide (LPS)-induced pro-inflammatory cytokine production and matrix metalloproteinase-2 and -9 (MMP-2/-9) expression. We found that baicalein significantly attenuated LPS-induced cardiac hypertrophy and counteracted reactive oxygen species (ROS) generation in neonatal rat cardiomyocytes. In addition, pretreatment with baicalein inhibited LPS-induced early (e.g., tumor necrosis factor-α (TNF-α) and interleukin-6) and late (e.g., high mobility group box 1 (HMGB1) pro-inflammatory cytokine release, inducible nitric oxide synthase (iNOS) expression and NO production. Finally, baicalein also significantly down-regulated the expression of MMP-2/-9 and attenuated HMGB1 translocation from the nucleus to the cytoplasm. These results suggest that baicalein can protect cardiomyocytes from LPS-induced cardiac injury via the inhibition of ROS and inflammatory cytokine production. These cardioprotective effects are possibly mediated through the inhibition of the HMGB1 and MMP-2/-9 signaling pathways.

Baicalein, an active component of Scutellaria baicalensis Georgi, prevents lysophosphatidylcholine-induced cardiac injury by reducing reactive oxygen species production, calcium overload and apoptosis via MAPK pathways

Background

Lysophosphatidylcholine (lysoPC), a metabolite from membrane phospholipids, accumulates in the ischemic myocardium and plays an important role in the development of myocardial dysfunction ventricular arrhythmia. In this study, we investigated if baicalein, a major component of Huang Qui, can protect against lysoPC-induced cytotoxicity in rat H9c2 embryonic cardiomyocytes.

Methods

Cell viability was detected by the MTT assay; ROS levels were assessed using DCFH-DA; and intracellular free calcium concentrations were assayed by spectrofluorophotometer. Cell apoptosis and necrosis were evaluated by the flow cytometry assay and Hoechst staining. Mitogen-Activated Protein Kinases (MAPKs), which included the ERK, JNK, and p38, and the apoptotic mechanisms including Bcl-2/Bax, caspase-3, caspase-9 and cytochrome c pathways were examined by Western blot analysis. The activation of MAPKs was examined by enzyme-linked immunosorbent assay.

Results

We found that lysoPC induced death and apoptosis of H9c2 cells in a dose-dependent manner. Baicalein could prevent lysoPC-induced cell death, production of reactive oxygen species (ROS), and increase of intracellular calcium concentration in H9c2 cardiomyoctes. In addition, baicalein also inhibited lysoPC-induced apoptosis, with associated decreased pro-apoptotic Bax protein, increased anti-apoptotic Bcl-2 protein, resulting in an increase in the Bcl-2/Bax ratio. Finally, baicalein attenuated lysoPC-induced the expression of cytochrome c, casapase-3, casapase-9, and the phosphorylations of ERK1/2, JNK, and p38. LysoPC-induced ERK1/2, JNK, and p38 activations were inhibited by baicalein.

Conclusions

Baicalein protects cardiomyocytes from lysoPC-induced apoptosis by reducing ROS production, inhibition of calcium overload, and deactivations of MAPK signaling pathways.

Lysophosphatidylcholine-induced cytotoxicity in osteoblast-like MG-63 cells: involvement of transient receptor potential vanilloid 2 (TRPV2) channels

Epidemiological studies indicate that patients suffering from atherosclerosis are predisposed to develop osteoporosis. Accordingly, atherogenic determinants such as oxidized low density lipoprotein (OxLDL) particles have been shown to alter bone cell functions. In this work, we investigated the cytotoxicity of lysophosphatidylcholine (lysoPC), a major phospholipid component generated upon LDL oxidation, on bone-forming MG-63 osteoblast-like cells. Cell viability was reduced by lysoPC in a concentration-dependent manner with a LC50 of 18.7±0.7 μM. LysoPC-induced cell death was attributed to induction of both apoptosis and necrosis. Since impairment of intracellular calcium homeostasis is often involved in mechanism of cell death, we determined the involvement of calcium in lysoPC-induced cytotoxicity. LysoPC promoted a rapid and transient increase in intracellular calcium attributed to mobilization from calcium stores, followed by a sustained influx. Intracellular calcium mobilization was associated to phospholipase C (PLC)-dependent mobilization of calcium from the endoplasmic reticulum since inhibition of PLC or calcium depletion of reticulum endoplasmic with thapsigargin prevented the calcium mobilization. The calcium influx induced by lysoPC was abolished by inhibition of transient receptor potential vanilloid (TRPV) channels with ruthenium red whereas gadolinium, which inhibits canonical TRP (TRPC) channels, was without effect. Accordingly, expression of TRPV2 and TRPV4 were shown in MG-63 cells. The addition of TRPV2 inhibitor Tranilast in the incubation medium prevent the calcium influx triggered by lysoPC and reduced lysoPC-induced cytotoxicity whereas TRPV4 inhibitor RN 1734 was without effect, which confirms the involvement of TRPV2 activation in lysoPC-induced cell death.

Betaine attenuates lysophosphatidylcholine-mediated adhesion molecules in aged rat aorta: modulation of the nuclear factor-κB pathway

We previously reported that lysophosphatidylcholine (LPC) is a mediator of endothelial dysfunction in the expression of adhesion molecules (AMs) during aging. This study aimed at investigating the effects of betaine on LPC-related expression of AMs and the molecular modulation of nuclear factor-κB (NF-κB) activation in the aorta of aged rats and rat endothelial YPEN-1 cells. The experiment was performed on young (7 months) and old (21 months) rats; 2 groups of old rats were fed betaine (3 or 6 mg · kg(-1) · day(-1) for 10 days). Betaine inhibited the expression of LPC-related AMs in the serum and tissue of aged rats, without affecting the elevated levels of serum LPC. Betaine also prevented the generation of reactive species, thereby maintaining the redox status via the enhancement of the thiol status during aging. Furthermore, betaine attenuated NF-κB activation via the dephosphorylation of IκB kinase (IKK) and mitogen-activated protein kinases (MAPKs) in aged aorta and LPC-treated YPEN-1 cells. Thus, betaine suppressed the LPC-related AM expression associated with NF-κB activation via the upregulation of IKK/MAPKs. Our findings provide insights into the prevention of vascular disorders and the development of interventions based on natural compounds, such as betaine.

Curcumin attenuates rat thoracic aortic aneurysm formation by inhibition of the c-Jun N-terminal kinase pathway and apoptosis

OBJECTIVE

Recent studies have suggested that c-Jun N-terminal kinase (JNK) plays an important role in the formation of abdominal aortic aneurysms, and that direct blockade of JNK by specific inhibitors can effectively prevent the progression of aortic aneurysms. A study has demonstrated that curcumin can suppress the development of experimental abdominal aortic aneurysms by inhibiting inflammation. We sought to investigate whether curcumin could inhibit JNK pathways and apoptosis in thoracic aortic aneurysms.

METHODS

We used a rat model of a CaCl₂-induced thoracic aortic aneurysm followed by daily oral gavage with curcumin 100 mg/kg or vehicle alone. After treatment for 4 wk, tissue specimens were obtained for histologic assessments, and tissue composition was evaluated using immunohistochemistry, western blotting, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling.

RESULTS

Curcumin significantly suppressed the CaCl₂-induced expansion of the thoracic aortic diameter and the structural preservation of medial elastin fibers. Most importantly, curcumin treatment significantly inhibited the phosphorylation of JNK and c-Jun, accompanied by less cell apoptosis in thoracic aortic aneurysm tissues. Furthermore, the expression levels of caspase-3 and the Bax/Bcl-2 ratio were significantly decreased in the aortic walls of curcumin-treated rats.

CONCLUSION

The present study indicates that the beneficial effect of curcumin on degenerative aortic aneurysms is related to the inhibition of JNK and apoptosis in the walls of thoracic aortic aneurysms.