Normal IgG downregulates the intracellular superoxide level and attenuates migration and permeability in human aortic endothelial cells isolated from a hypertensive patient

TNFα Induces DNA and Histone Hypomethylation and Pulmonary Artery Smooth Muscle Cell Proliferation Partly via Excessive Superoxide Formation

Objective: The level of tumor necrosis factor-α (TNF-α) is upregulated during the development of pulmonary vascular remodeling and pulmonary hypertension. A hallmark of pulmonary arterial (PA) remodeling is the excessive proliferation of PA smooth muscle cells (PASMCs). The purpose of this study is to investigate whether TNF-α induces PASMC proliferation and explore the potential mechanisms. Methods: PASMCs were isolated from 8-week-old male Sprague-Dawley rats and treated with 0, 20, or 200 ng/mL TNF-α for 24 or 48 h. After treatment, cell number, superoxide production, histone acetylation, DNA methylation, and histone methylation were assessed. Results: TNF-α treatment increased NADPH oxidase activity, superoxide production, and cell numbers compared to untreated controls. TNF-α-induced PASMC proliferation was rescued by a superoxide dismutase mimetic tempol. TNF-α treatment did not affect histone acetylation at either dose but did significantly decrease DNA methylation. DNA methyltransferase 1 activity was unchanged by TNF-α treatment. Further investigation using QRT-RT-PCR revealed that GADD45-α, a potential mediator of DNA demethylation, was increased after TNF-α treatment. RNAi inhibition of GADD45-α alone increased DNA methylation. TNF-α impaired the epigenetic mechanism leading to DNA hypomethylation, which can be abolished by a superoxide scavenger tempol. TNF-α treatment also decreased H3-K4 methylation. TNF-α-induced PASMC proliferation may involve the H3-K4 demethylase enzyme, lysine-specific demethylase 1 (LSD1). Conclusions: TNF-α-induced PASMC proliferation may be partly associated with excessive superoxide formation and histone and DNA methylation.

Transplantation of bone marrow cells from miR150 knockout mice improves senescence-associated humoral immune dysfunction and arterial stiffness

BACKGROUND AND PURPOSE

The senescence-accelerated mouse P1 (SAMP1) suffers from humoral immune deficiency, arterial stiffness and accelerated aging. In contrast, the microRNA-150 knockout (miR-150-KO) mice show enhanced humoral immune function including increased B cell population and elevated serum immunoglobulin levels and enjoy extended lifespan. The purpose of this study was to investigate whether transplantation of bone marrow cells (BMCs) from miR-150-KO mice affects immune deficiency and arterial stiffening in SAMP1 mice.

METHODS AND RESULTS

Pulse wave velocity and blood pressure were increased significantly in SAMP1 mice (10 months), indicating arterial stiffening and hypertension. Interestingly, transplantation of BMCs from miR-150-KO mice significantly attenuated arterial stiffening and hypertension in SAMP1 mice within eight weeks. BMC transplantation from miR-150-KO mice partially rescued the downregulation of B lymphocytes, largely restored serum IgG and IgM levels, decreased inflammatory cytokine and chemokine expression, and attenuated macrophage and T cell infiltration in aortas in SAMP1 mice. BMC transplantation nearly abolished the upregulation of collagen 1, TGFβ1, Scleraxis, MMP-2 and MMP-9 expression and the downregulation of elastin levels in aortas in SAMP1 mice. FISH staining confirmed existence of the transplanted BMCs at end of the experiment. In cultured endothelial cells, IgG-deficient medium invoked upregulation of inflammatory cytokine/chemokine expression which can be rescued by treatment with IgG.

CONCLUSIONS

Accelerated senescence caused arterial stiffening via impairing the humoral immune function in SAMP1 mice. BMC transplantation from miR-150-KO mice attenuated arterial matrix remodeling and stiffening and hypertension in SAMP1 mice partly via improving the humoral immune function which attenuates vascular inflammation.

Aging impairs arterial compliance via Klotho-mediated downregulation of B-cell population and IgG levels

OBJECTIVE

Aging is associated with compromised immune function and arterial remodeling and stiffness. The purpose of this study is to investigate whether in vivo AAV-based delivery of secreted Klotho (SKL) gene (AAV-SKL) improves aging- and senescence-associated immune dysfunction and arterial stiffness.

METHODS AND RESULTS

Senescence-accelerated mice prone strain 1 (SAMP1, 10 months) and old mice (20 months) were used. Serum SKL levels, B-cell population and serum IgG levels were markedly decreased in SAMP1 and old mice. Rescue of downregulation of serum SKL levels by in vivo AAV2-based delivery of SKL gene (AAV-SKL) increased B-cell population and serum IgG levels and attenuated arterial stiffness in SAMP1 and old mice. Thus, Klotho deficiency may play a role in senescence- and aging-associated humoral immune dysfunction and arterial stiffness. Vascular infiltration of inflammatory cells and expression of TGFβ1, collagen 1, scleraxis, MMP-2 and MMP-9 were increased while the elastin level was decreased in aortas of SAMP1 and old mice which can be rescued by AAV-SKL. Interestingly, treatment with IgG effectively rescued arterial inflammation and remodeling and attenuated arterial stiffness and hypertension in aging mice. In cultured B-lymphoblast cells, we further showed that SKL regulates B-cell proliferation and maturation partly via the NFkB pathway.

CONCLUSION

Aging-associated arterial stiffening may be largely attributed to downregulation of B-cell population and serum IgG levels. AAV-SKL attenuates arterial stiffness in aging mice partly via restoring B-cell population and serum IgG levels which attenuates aging-associated vascular inflammation and arterial remodeling.

In Vivo Cardiac-specific Expression of Adenylyl Cyclase 4 Gene Protects against Klotho Deficiency-induced Heart Failure

Klotho is an aging-suppressor gene. Klotho gene deficiency causes heart failure in Klotho-hypomorphic mutant (KL (-/-)) mice. RNA-seq and western blot analysis showed that adenylyl cyclase type IV (AC4) mRNA and protein expression was largely decreased in cardiomyocytes of KL (-/-) mice. The objective of this study was to investigate whether in vivo cardiac-specific expression of AC4 gene protects against Klotho deficiency-induced heart failure. Interestingly, in vivo AAV-based cardiac-specific AC4 gene expression increased left ventricular fractional shortening, ejection fraction, stroke volume, and left ventricular end-diastolic volume in KL (-/-) mice, suggesting that cardiac-specific AC4 gene expression improves Klotho deficiency-induced heart dysfunction. Cardiac-specific AC4 gene expression also decreased Klotho deficiency-induced cardiac hypertrophy. Cardiac-specific AC4 gene expression alleviated Klotho deficiency-induced cardiac fibrosis and calcification. Furthermore, cardiac-specific AC4 gene expression attenuated mitochondrial dysfunction, superoxide accumulation and cardiomyocyte apoptotic cell death. Thus, downregulation of AC4 may contribute to Klotho deficiency-induced heart failure. Mechanistically, AAV2/9-αMHC-AC4 increased cardiomyocytic cAMP levels and thus regulated the PKA-PLN-SERCA2 signal pathway, which is critical in modulating calcium flux and mitochondrial function. In conclusion, cardiac-specific AC4 gene expression protects against Klotho deficiency-induced heart failure through increasing cardiomyocytic cAMP levels, which alleviates cAMP-dependent mitochondrial dysfunction, superoxide accumulation and apoptotic cell death. AC4 regulates superoxide levels via the cAMP-PKA pathway. AC4 could be a potential therapeutic target for heart failure associated with Klotho deficiency. Heart failure is the major cause of mortality in patients with chronic kidney disease (CKD). A decrease in Klotho levels is linked to CKD.

Estrogen inhibits renal Na-Pi Co-transporters and improves klotho deficiency-induced acute heart failure

Objective and hypothesis

Klotho is an aging-suppressor gene. Mutation of Klotho gene causes hyperphosphatemia and acute heart failure. However, the relationship of hyperphosphatemia and acute heart failure is unclear. We hypothesize that hyperphosphatemia mediates Klotho deficiency-induced acute heart failure and further that therapeutic reduction of hyperphosphatemia prevents acute heart failure in Klotho mutant (KL(−/−)) mice.

Methods and results

A significant elevation of serum phosphorus levels and a large reduction of heart function were found in KL(−/−) mice by six weeks of age. Normalization of serum phosphorus levels by low phosphate diet (LPD) rescued Klotho deficiency-induced heart failure and extended lifespan in male mice. Klotho deficiency impaired cardiac mitochondrial respiratory enzyme function and increased superoxide production, oxidative stress, and cardiac cell apoptosis in male KL(−/−) mice which can be eliminated by LPD. LPD, however, did not rescue hyperphosphatemia or heart failure in female KL(−/−) mice. LPD did not affect estrogen depletion in female KL(−/−) mice. Normalization of serum estrogen levels by treatment with 17β-estradiol prevented hyperphosphatemia and heart failure in female KL(−/−) mice. Mechanistically, treatment with 17β-estradiol rescued hyperphosphatemia via inhibiting renal Na-Pi co-transporter expression. Normalization of serum phosphorus levels by treatment with 17β-estradiol also abolished cardiac mitochondrial respiratory enzyme dysfunction, ROS overproduction, oxidative stress and cardiac cell apoptosis in female KL(−/−) mice.

Conclusion

Klotho deficiency causes acute heart failure via hyperphosphatemia in male mice which can be prevented by LPD. 17β-estradiol prevents Klotho deficiency-induced hyperphosphatemia and heart failure by eliminating upregulation of renal Na-Pi co-transporter expression in female mice.

Timed synchronization of muscle contraction to heartbeat enhances muscle hyperemia

Blood flow (BF) to exercising muscles is susceptible to variations of intensity, and duration of skeletal muscle contractions, cardiac cycle, blood velocity, and vessel dilation. During cyclic muscle activity, these elements may change proportionally with or without direct optimal temporal alignment, likely influencing BF to active muscle. Ideally, the pulsed delivery of blood to active muscle timed with the inactive phase of muscle duty-cycle would enhance the peak and average BF. To investigate the phenomenon of muscle contraction and pulse synchronicity, electrically evoked muscle contractions (trains of 20 Hz, 200-ms duration) were synchronized with each systolic phase of the anterograde blood velocity spectrum (aBVS). Specifically, unilateral quadriceps contractions matched in-phase (IP) with the aBVS were compared with contractions matched out-of-phase (OP) with the aBVS in 10 healthy participants (26 ± 3 yr). During each trial, femoral BF of the contracting limb and central hemodynamics were recorded for 5 min with an ultrasound Doppler, a plethysmograph, and a cardioimpedance device. At steady state (5th min) IP BF (454 ± 30 mL/min) and vascular conductance (4.3 ± 0.2 mL·min^-1·mmHg^-1), and OP MAP (108 ± 2 mmHg) were significantly lower (P < 0.001) in comparison to OP BF (784 ± 25 mL/min) and vascular conductance (6.7 ± 0.2 mL·min^-1·mmHg^-1), and IP MAP (113 ± 3 mmHg). On the contrary, no significant difference (all, P > 0.05) was observed between IP and OP central hemodynamics (HR: 79 ± 10 vs. 76 ± 11 bpm, CO: 8.0 ± 1.6 vs. 7.3 ± 1.6 L/min), and ventilatory patterns (V̇e:14 ± 2 vs. 14 ± 1 L/min, V̇o₂:421 ± 70 vs. 397 ± 34 mL/min). The results suggest that muscle contractions occurring during OP that do not interfere with aBVS elicit a maximization of muscle functional hyperemia.NEW & NOTEWORTHY When muscle contraction is synchronized with the pulsed delivery of blood flow to active muscle, muscle functional hyperemia can be either maximized or minimized. This suggests a possibility to couple different strategies to enhance the acute and chronic effects of exercise on the cardiovascular system.

Alteration of the Gut Microbiota and Its Effect on AMPK/NADPH Oxidase Signaling Pathway in 2K1C Rats

Background

The purpose of this study was to evaluate the alteration of the gut microbiota and its effect on adenosine monophosphate-activated protein kinase (AMPK)/nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) signaling pathway in two-kidney one-clip (2K1C) rats.

Methods

The 2K1C rat models were established. The rats were randomly divided into the following 2 groups: 2K1C group and sham group. Alterations of the gut microbiota were analyzed based on the high throughput sequencing method. Plasma concentrations of short chain fatty acids (SCFAs) were measured by chromatography. The protein expression of phosphorylated AMPK and acetyl-CoA carboxylase (ACC) was determined by western blotting. NADPH oxidase activity was measured by a luminometer.

Results

Microbial community analyses revealed that the structure and composition of the gut microbiota were significantly disrupted in 2K1C rats when compared to sham rats. This disruption was associated with the drastic increase in relative abundance of the genera Prevotella and the decrease in SCFA-producing bacterial population. We further confirm that SCFAs produced by the gut microbiota influence NADPH oxidase activity through AMPK.

Conclusions

Our data implicated the important role of gut microbiota in the regulation of AMPK/NADPH oxidase signaling pathway.

Resveratrol regulates blood pressure by enhancing AMPK signaling to downregulate a Rac1-derived NADPH oxidase in the central nervous system

Resveratrol is a polyphenol with pleiotropic effects against oxidative damage that has been widely implicated in lowering hypertension risk. The purpose of this study was to determine whether improve nitric oxide (NO) release in the brain, either through the activation of AMP-activated protein kinase (AMPK) or reduced Ras-related C3 botulinum toxin substrate 1 (Rac1)-induced reactive oxygen species (ROS) generation, thereby reducing blood pressure (BP) in rats with fructose-induced hypertension. The rats were fed with 10% fructose or Crestor (rosuvastatin; 1.5 mg·kg−1·day−1) and resveratrol (10 mg·kg−1·day−1) treatment for 1 wk, then the systolic blood pressure of the rats was measured by tail-cuff method. Endogenous in vivo superoxide radical production in the nucleus tractus solitarii (NTS) was determined with dihydroethidium. Immunoblotting analyses were used to quantify protein expression levels. Oral resveratrol treatment for 1 wk decreased BP and increased NO production in the NTS of fructose-fed rats but not in the control Wistar-Kyoto rats. The effect of Crestor is opposite that of resveratrol. Fructose induced hypertension by inactivating AMPK, which in turn enhanced the generation of ROS and reduced manganese superoxide dismutase by increasing the activity of Rac1-induced NADPH oxidase, abolishing the activity of the extracellular signal-regulated kinases 1 and 2 (ERK1/2) and ribosomal protein S6 kinase (RSK) and neuronal nitric oxide synthase (nNOS) phosphorylation signaling pathway in the brain. However, resveratrol had the opposite effect in the fructose-fed rats. Overall, we show that the resveratrol decreased BP better than Crestor, abolished ROS generation, and enhanced the ERK1/2-RSK-nNOS pathway by activating AMPK to downregulate Rac1-induced NADPH oxidase levels in the NTS during oxidative stress–associated hypertension.

NEW & NOTEWORTHY 1) Evidence showed that the Ras-related C3 botulinum toxin substrate 1 (Rac1) augmented by Crestor (rosuvastatin) did not result in a significant change in blood pressure (BP) in fructose-induced hypertension. 2) Fructose induced hypertension by inactivating AMP-activated protein kinase (AMPK), which in turn enhanced the generation of reactive oxygen species (ROS) and reduced manganese superoxide dismutase in the brain. 3) Resveratrol decreased BP better than Crestor, abolished ROS generation, and enhanced the ERK1/2-ribosomal protein S6 kinase-neuronal nitric oxide synthase pathway by activating AMPK to negatively regulate Rac1-induced NADPH oxidase levels in the nucleus tractus solitarii during oxidative stress–associated hypertension.

Modulation of Immune-Inflammatory Responses in Abdominal Aortic Aneurysm: Emerging Molecular Targets

Abdominal aortic aneurysm (AAA), a deadly vascular disease in human, is a chronic degenerative process of the abdominal aorta. In this process, inflammatory responses and immune system work efficiently by inflammatory cell attraction, proinflammatory factor secretion and subsequently MMP upregulation. Previous studies have demonstrated various inflammatory cell types in AAA of human and animals. The majority of cells, such as macrophages, CD4+ T cells, and B cells, play an important role in the diseased aortic wall through phenotypic modulation. Furthermore, immunoglobulins also greatly affect the functions and differentiation of immune cells in AAA. Recent evidence suggests that innate immune system, especially Toll-like receptors, chemokine receptors, and complements are involved in the progression of AAAs. We discussed the innate immune system, inflammatory cells, immunoglobulins, immune-mediated mechanisms, and key cytokines in the pathogenesis of AAA and particularly emphasis on a further trend and application of these interventions. This current understanding may offer new insights into the role of inflammation and immune response in AAA.

Induction of anti-aging gene klotho with a small chemical compound that demethylates CpG islands

Klotho (KL) is described as an anti-aging gene because mutation of Kl gene leads to multiple pre-mature aging phenotypes and shortens lifespan in mice. Growing evidence suggests that an increase in KL expression may be beneficial for age-related diseases such as arteriosclerosis and diabetes. It remains largely unknown, however, how Kl expression could be induced. Here we discovered novel molecular mechanism for induction of Kl expression with a small molecule ‘Compound H’, N-(2-chlorophenyl)-1H-indole-3-caboxamide. Compound H was originally identified through a high-throughput screening of small molecules for identifying Kl inducers. However, how Compound H induces Kl expression has never been investigated. We found that Compound H increased Kl expression via demethylation in CpG islands of the Kl gene. The demethylation was accomplished by activating demethylases rather than inhibiting methylases. Due to demethylation, Compound H enhanced binding of transcription factors, Pax4 and Kid3, to the promoter of the Kl gene. Pax4 and Kid3 regulated Kl promoter activity positively and negatively, respectively. Thus, our results show that demethylation is an important molecular mechanism that mediates Compound H-induced Kl expression. Further investigation is warranted to determine whether Compound H demethylates the Kl gene in vivo and whether it can serve as a therapeutic agent for repressing or delaying the onset of age-related diseases.

Microvascular Vasodilator Plasticity After Acute Exercise

Endothelium-dependent vasodilation is reduced after acute exercise or after high intraluminal pressure in isolated arterioles from sedentary adults but not in arterioles from regular exercisers. The preserved vasodilation in arterioles from exercisers is hydrogen peroxide (H2O2) dependent, whereas resting dilation is nitric oxide (NO) dependent. We hypothesize chronic exercise elicits adaptations allowing for maintained vasodilation when NO bioavailability is reduced.

Regulation of S-formylglutathione hydrolase by the anti-aging gene klotho

Klotho is an aging-suppressor gene. The purpose of this study is to investigate the binding sites (receptors) and function of short-form Klotho (Skl). We showed that Skl physically bound to multiple proteins. We found physical and functional interactions between Skl and S-formylglutathione hydrolase (FGH), a key enzyme in the generation of the major cellular anti-oxidant GSH, using co-immunoprecipitation-coupled mass spectrometry. We further confirmed the colocalization of Skl and FGH around the nucleus in kidney cells using immunofluorescent staining. Skl positively regulated FGH gene expression via Kid3 transcription factor. Overexpression of Skl increased FGH mRNA and protein expression while silencing of Skl attenuated FGH mRNA and protein expression. Klotho gene mutation suppressed FGH expression in red blood cells and kidneys resulting in anemia and kidney damage in mice. Overexpression of Skl increased total GSH production and the GSH/GSSG ratio, an index of anti-oxidant capacity, leading to a decrease in intracellular H₂O₂ and superoxide levels. The antioxidant activity of Skl was eliminated by silencing of FGH, indicating that Skl increased GSH via FGH. Interestingly, Skl directly interacted with FGH and regulated its function. Site-directed mutagenesis of the N-glycan-modified residues in Skl abolished its antioxidant activity, suggesting that these N-glycan moieties are important features that interact with FGH. Specific mutation of Asp to Ala at site 285 resulted in a loss of anti-oxidant activity of Skl, suggesting that N-glycosylation at site 285 is the key mechanism that determines Skl activity. Therefore, this study demonstrates, for the first time, that Skl regulates anti-oxidant GSH generation via interaction with FGH through N-glycosylation.

AAV Delivery of Endothelin-1 shRNA Attenuates Cold-Induced Hypertension

Cold temperatures are associated with increased prevalence of hypertension. Cold exposure increases endothelin-1 (ET1) production. The purpose of this study is to determine whether upregulation of ET1 contributes to cold-induced hypertension (CIH). In vivo RNAi silencing of the ET1 gene was achieved by adeno-associated virus 2 (AAV2) delivery of ET1 short-hairpin small interfering RNA (ET1-shRNA). Four groups of male rats were used. Three groups were given AAV.ET1-shRNA, AAV.SC-shRNA (scrambled shRNA), and phosphate-buffered saline (PBS), respectively, before exposure to a moderately cold environment (6.7 ± 2°C), while the last group was given PBS and kept at room temperature (warm, 24 ± 2°C) and served as a control. We found that systolic blood pressure of the PBS-treated and SC-shRNA-treated groups increased significantly within 2 weeks of exposure to cold, reached a peak level (145 ± 4.8 mmHg) by 6 weeks, and remained elevated thereafter. By contrast, blood pressure of the ET1-shRNA-treated group did not increase, suggesting that silencing of ET1 prevented the development of CIH. Animals were euthanized after 10 weeks of exposure to cold. Cold exposure significantly increased the left ventricle (LV) surface area and LV weight in cold-exposed rats, suggesting LV hypertrophy. Superoxide production in the heart was increased by cold exposure. Interestingly, ET1-shRNA prevented cold-induced superoxide production and cardiac hypertrophy. ELISA assay indicated that ET1-shRNA abolished the cold-induced upregulation of ET1 levels, indicating effective silencing of ET1. In conclusion, upregulation of ET1 plays a critical role in the pathogenesis of CIH and cardiac hypertrophy. AAV delivery of ET1-shRNA is an effective therapeutic strategy for cold-related cardiovascular disease.

Monocrotaline-Induced Pulmonary Hypertension Involves Downregulation of Antiaging Protein Klotho and eNOS Activity

The objective of this study is to investigate whether stem cell delivery of secreted Klotho (SKL), an aging-suppressor protein, attenuates monocrotaline-induced pulmonary vascular dysfunction and remodeling. Overexpression of SKL in mesenchymal stem cells (MSCs) was achieved by transfecting MSCs with lentiviral vectors expressing SKL-green fluorescent protein (GFP). Four groups of rats were treated with monocrotaline, whereas an additional group was given saline (control). Three days later, 4 monocrotaline-treated groups received intravenous delivery of nontransfected MSCs, MSC-GFP, MSC-SKL-GFP, and PBS, respectively. Ex vivo vascular relaxing responses to acetylcholine were diminished in small pulmonary arteries (PAs) in monocrotaline-treated rats, indicating pulmonary vascular endothelial dysfunction. Interestingly, delivery of MSCs overexpressing SKL (MSC-SKL-GFP) abolished monocrotaline-induced pulmonary vascular endothelial dysfunction and PA remodeling. Monocrotaline significantly increased right ventricular systolic blood pressure, which was attenuated significantly by MSC-SKL-GFP, indicating improved PA hypertension. MSC-SKL-GFP also attenuated right ventricular hypertrophy. Nontransfected MSCs slightly, but not significantly, improved PA hypertension and pulmonary vascular endothelial dysfunction. MSC-SKL-GFP attenuated monocrotaline-induced inflammation, as evidenced by decreased macrophage infiltration around PAs. MSC-SKL-GFP increased SKL levels, which rescued the downregulation of SIRT1 (Sirtuin 1) expression and endothelial NO synthase (eNOS) phosphorylation in the lungs of monocrotaline-treated rats. In cultured endothelial cells, SKL abolished monocrotaline-induced downregulation of eNOS activity and NO levels and enhanced cell viability. Therefore, stem cell delivery of SKL is an effective therapeutic strategy for pulmonary vascular endothelial dysfunction and PA remodeling. SKL attenuates monocrotaline-induced PA remodeling and PA smooth muscle cell proliferation, likely by reducing inflammation and restoring SIRT1 levels and eNOS activity.

Resveratrol decreases fructose-induced oxidative stress, mediated by NADPH oxidase via an AMPK-dependent mechanism

BACKGROUND AND PURPOSE

Oxidative stress is an important pathogenic factor in the development of hypertension. Resveratrol, the main antioxidant in red wine, improves NO bioavailability and prevents cardiovascular disease. The aim of this study was to examine whether resveratrol decreases the generation of reactive oxygen species (ROS), thereby reducing BP in rats with fructose-induced hypertension.

EXPERIMENTAL APPROACH

Rats were fed 10% fructose with or without resveratrol (10 mg·kg(-1) ·day(-1) ) for 1 week or for 4 weeks with resveratrol treatment beginning at week 2; systolic BP (SBP) was measured by tail-cuff method. Endogenous in vivo O2 (-) production in the nucleus tractus solitarii (NTS) was determined with dihydroethidium. Real-time PCR and immunoblotting analyses were used to quantify RNA and protein expression levels.

KEY RESULTS

In fructose-fed rats, ROS levels in the NTS were higher, whereas the NO level was significantly decreased. Also, RNA and protein levels of NADPH oxidase subunits (p67, p22-phox) were elevated, superoxide dismutase 2 (SOD2) reduced and AMP-activated PK (AMPK) T172 phosphorylation levels in the NTS were lower in fructose-fed rats. Treatment with the AMPK activator resveratrol decreased levels of NADPH oxidase subunits and ROS, and increased NO and SOD2 levels in the NTS of fructose-fed rats. Administration of resveratrol, in combination with fructose at week 0 and later at week 2, significantly reduced the SBP of fructose-fed rats.

CONCLUSIONS AND IMPLICATIONS

Collectively, resveratrol decreased BP through the phosphorylation of AMPK, Akt and neuronal NOS in fructose-fed rats. These novel findings suggest that resveratrol may be a potential pharmacological candidate for the treatment of hypertension.

AAV delivery of tumor necrosis factor-α short hairpin RNA attenuates cold-induced pulmonary hypertension and pulmonary arterial remodeling

Cold temperatures are associated with increased mortality and morbidity of cardiovascular and pulmonary disease. Cold exposure causes lung inflammation, pulmonary hypertension (PH), and right ventricle hypertrophy, but there is no effective therapy because of unknown mechanism. Here, we investigated whether RNA interference silencing of tumor necrosis factor (TNF)-α decreases cold-induced macrophage infiltration, PH, and pulmonary arterial (PA) remodeling. We found for the first time that continuous cold exposure (5.0°C) increased TNF-α expression and macrophage infiltration in the lungs and PAs right before elevation of right ventricle systolic pressure. The in vivo RNA interference silencing of TNF-α was achieved by intravenous delivery of recombinant AAV-2 carrying TNF-α short hairpin small-interfering RNA 24 hours before cold exposure. Cold exposure for 8 weeks significantly increased right ventricle pressure compared with the warm controls (40.19±4.9 versus 22.9±1.1 mm Hg), indicating that cold exposure caused PH. Cold exposure increased TNF-α, interleukin-6, and phosphodiesterase-1C protein expression in the lungs and PAs and increased lung macrophage infiltration. Notably, TNF-α short hairpin small-interfering RNA prevented the cold-induced increases in TNF-α, interleukin-6, and phosphodiesterase-1C protein expression, abolished lung macrophage infiltration, and attenuated PH (26.28±1.6 mm Hg), PA remodeling, and right ventricle hypertrophy. PA smooth muscle cells isolated from cold-exposed animals showed increased intracellular superoxide levels and cell proliferation along with decreased intracellular cGMP. These cold-induced changes were prevented by TNF-α short hairpin small-interfering RNA. In conclusions, upregulation of TNF-α played a critical role in the pathogenesis of cold-induced PH by promoting pulmonary macrophage infiltration and inflammation. AAV delivery of TNF-α short hairpin small-interfering RNA may be an effective therapeutic approach for cold-induced PH and PA remodeling.