Long-term effects of photobiomodulation therapy on blood pressure in obese rats induced by a high-fat diet

The main cardiovascular disease risk associated with obesity is hypertension. The therapeutic use of photobiomodulation therapy (PBM) is suggested for the treatment of wound healing, osteoarthritis, and arterial diseases. However, few studies have measured how red laser (at 660 nm) acts over hypertension, and any of those studies used experimental obesity model. The aim of the study was an attempt to evaluate the long-term effect of PBM on systolic blood pressure in an animal model of obesity, induced by a high-fat diet (HFD). Our results indicate that PBM carried out 3 days a week was able to prevent the increase in blood pressure (133.75 ± 4.82 mmHg, n = 8) induced by a high-fat diet (150.00 ± 4.57 mmHg, n = 8; p < 0.05), restore nitric oxide levels (control: 31.7 ± 5.5 μM, n = 8; HFD + PBM: 29.9 ± 3.7 μM, n = 8 > HFD: 22.2 ± 2.9 μM, n = 8, p < 0.05), decrease lipoperoxidation (control: 1.65 ± 0.25 nM, n = 8; HFD + PBM: 2.05 ± 0.55 nM, n = 8 < HFD: 3.20 ± 0.47 nM, n = 8; p < 0.05), and improve endothelial function (pD2 control: 7.39 ± 0.08, n = 8 > pD2 HFD + PBM: 7.15 ± 0.07, n = 8 > HFD: 6.94 ± 0.07, n = 8; p < 0.05). Our results indicate that PBM prevents the elevation of blood pressure in an obese animal model by a mechanism that involves improvement of endothelial function through an antioxidant effect.

Chronic red laser treatment induces hypotensive effect in two-kidney one-clip model of renovascular hypertension in rat

To evaluate whether the chronic effect of photobiomodulation therapy (PBM) on systolic arterial pressure (SAP) from two kidneys one clip (2 K-1C) hypertension animal models can cause a hypotensive effect. Serum levels of nitric oxide were also analyzed and the assessment of lipid peroxidation of the thoracic aorta artery. Male Wistar rats were used. Hypertensive animals (2 K-1C) with Systolic arterial pressure (SAP) greater than or equal to 160 mmHg were used. Systolic arterial pressure (SAP) was determined by the tail plethysmography technique. Normotensive (2 K) and hypertensive (2 K-1C) rats were treated to PBM for 4 weeks using a laser whose irradiation parameters were: red wavelength (λ) = 660 nm: operating continuously; 56 s per point (3 points) spot size = 0.0295 cm2; average optical power of 100 mW; energy of 5.6 J per point; irradiance of 3.40 W/cm2; fluency of 190 J/cm2 per point. The application was on the animals tails, at 3 different points simultaneously, in contact with the skin. To assess serum nitrite and nitrate (NOx) levels, blood collection was performed after chronic PBM treatment, 24 h after the last laser application. The evaluation of the lipid peroxidation of the thoracic aorta artery was performed by measuring the concentration of hydroperoxide by the FOX method. Chronic photobiomodulation therapy (PBM) by red laser (660 nm) can induce a hypotensive effect in 64% of 2 K-1C hypertensive animals, which we say responsive animals. There was no difference in serum NO levels 24 h after the last red laser application, between treated and non-treated groups. Aortic rings from 2 K-1C hypertensive animals present a higher lipid peroxidation. The chronic PBM treatment by red laser decreased aortic rings lipid peroxidation in hypertensive responsive groups, compared to control. our results indicate that chronic PBM made by red laser has an important hypotensive effect in renovascular hypertensive models, by a mechanism that involves decrease in oxidative stress from vascular beds.

Ontogenetic scaling of the baroreflex function in the green iguana (Iguana iguana)

Large body mass (M_b) in vertebrates is associated with longer pulse intervals between heartbeats (PI) and thicker arterial walls. Longer PI increases the time for diastolic pressure decay, possibly resulting in loss of cardiac energy as "oscillatory power", whereas thicker arterial walls may affect the transmission of impulses and sensing of pressure fluctuations thus impairing baroreflex function. We aimed to investigate the effect of growth on the relative cardiac energy loss and baroreflex function. We predicted that i) the relative use of cardiac energy should be preserved with increased time constant for pressure decay (τ = vascular resistance × compliance); ii) if arterial circumferential distensibility does not change, baroreflex function should be unaltered with M_b. To test these hypotheses, we used green iguanas (Iguana iguana) weighing from 0.03 to 1.34 kg (43-fold increment in M_b). PI (P=0.037) and τ (P=0.354) increased with M_b whereas the oscillatory power fraction (P=0.245) was unrelated to it. Thus, the concomitant alterations of τ and PI allowed the conservation of cardiac energy in larger lizards. Larger animals had thicker arterial walls (P=0.0007) and greater relative collagen content (P=0.022). Area compliance scaled positively to M_b (P=0.045), though circumferential distensibility (P=0.155) and elastic modulus (P=0.762) were unaltered. Additionally, baroreflex sensitivity measured by both the pharmacological (P=0.152) and sequence methods (P=0.088), and the baroreflex effectiveness index (P=0.306) were also unrelated to M_b. Therefore, changes in arterial morphology did not affect circumferential distensibility and presumably sensing of pressure fluctuation, and the cardiovagal baroreflex is preserved across different M_b.

Profile of IL-6 and TNF in Foam Cell Formation: An Improved Method Using Fluorescein Isothiocyanate (FITC) Probe

BACKGROUND

The formation of foam cells occurs due to the increase in low-density plasma lipoprotein (LDL) and dysregulation of inflammation, which is important for the development of atherosclerosis.

OBJECTIVE

To evaluate the profile of tumor necrosis factor-alpha (TNF-α) and Interleukin-6 (IL-6) in the existing foam cell formation method, optimizing this protocol.

METHODS

The LDL was isolated, oxidized, and labeled with a Fluorescein isothiocyanate (FITC) probe. Foam cells were generated from THP-1 human monocyte-derived cells and incubated in the absence (control) or presence of FITC-ox-LDL (10, 50, 100, 150, or 200 μg/mL), for 12, 24, 48, or 72 hours. The accumulated FITC-ox-LDL in the cell was quantified by microscopy. The enzyme-linked immunosorbent assay was evaluated to quantify the IL-6 and TNF-α, with p < 0.05 considered significant.

RESULTS

All the FITC-ox-LDL concentrations tested showed a higher fluorescence when compared to the control, showing a greater accumulation of lipoprotein in cells. The higher the concentration of FITC-ox-LDL, the greater the production of TNF-α and IL-6. The production of IL-6 by foam cells was detected up to the value of 150 µg/mL of the maximum stimulus for LDL. Concentrations above 50 μg/mL LDL stimulated greater release of TNF-α compared to control.

CONCLUSIONS

Our model contributes to the understanding of the release of IL-6 and TNF-α in response to different concentrations of ox-LDL, using an optimized method for the formation of foam cells.

The Rationale for "Laser-Induced Thermal Therapy (LITT) and Intratumoral Cisplatin" Approach for Cancer Treatment

Cisplatin is one of the most widely used anticancer drugs in the treatment of various types of solid human cancers, as well as germ cell tumors, sarcomas, and lymphomas. Strong evidence from research has demonstrated higher efficacy of a combination of cisplatin and derivatives, together with hyperthermia and light, in overcoming drug resistance and improving tumoricidal efficacy. It is well known that the antioncogenic potential of CDDP is markedly enhanced by hyperthermia compared to drug treatment alone. However, more recently, accelerators of high energy particles, such as synchrotrons, have been used to produce powerful and monochromatizable radiation to induce an Auger electron cascade in cis-platinum molecules. This is the concept that makes photoactivation of cis-platinum theoretically possible. Both heat and light increase cisplatin anticancer activity via multiple mechanisms, generating DNA lesions by interacting with purine bases in DNA followed by activation of several signal transduction pathways which finally lead to apoptosis. For the past twenty-seven years, our group has developed infrared photo-thermal activation of cisplatin for cancer treatment from bench to bedside. The future development of photoactivatable prodrugs of platinum-based agents injected intratumorally will increase selectivity, lower toxicity and increase efficacy of this important class of antitumor drugs, particularly when treating tumors accessible to laser-based fiber-optic devices, as in head and neck cancer. In this article, the mechanistic rationale of combined intratumor injections of cisplatin and laser-induced thermal therapy (CDDP-LITT) and the clinical application of such minimally invasive treatment for cancer are reviewed.

Nitric oxide storage levels modulate vasodilation and the hypotensive effect induced by photobiomodulation using an aluminum gallium arsenide (AlGaAs) diode laser (660 nm)

The aim of this study was to evaluate the participation of nitric oxide (NO) in the hypotensive and vasorelaxation effect induced by PBM using an aluminum gallium arsenide (AlGaAs) diode laser (660 nm). Male Wistar rats were treated with the inhibitor of nitric oxide synthase (L-NAME). A red laser (660 nm; 63 J/cm²; 56 s/point) was applied to the abdominal region at six different points. Thoracic aorta was dissected for vascular reactivity study, and a laser (660 nm; 96 J/cm²; 56 s) was applied after incubation with the NO donor DETA-NO, PBS, or hydroxicobalamin. Endothelial cells (HUVEC) were treated with DETA-NO or CuSO₄, and then, PBM (63 J/cm²) was applied, and the nitric oxide was detected. Hypertensive L-NAME rats did not exhibit a decrease in blood pressure after PBM. PBM promoted vasodilation in the aorta isolated from normotensive rats, and less effect in the aorta of L-NAME rats and the addition of the NO donor, DETA-NO, promoted greater vasodilation by PBM in the aorta of L-NAME rats. In endothelial cells, an increase in NO, after PBM, was detected; however, with the addition of CuSO₄, which catalyzes the decomposition of NO storage, there was no detection of NO after PBM. The results of this study demonstrate that the hypotensive and vasodilatory effect of PBM with a red laser at 660 nm is modulated by the release of nitric oxide from the storage.

Multidrug-resistant protein inhibitor and phosphodiesterase inhibitor potentiate the vasodilator effect induced by photobiomodulation in isolated aortic rings

A previous work indicates that the red LASER (660 nm) induces vascular relaxation by nitric oxide (NO)-dependent mechanism. NO activates soluble guanylate cyclase (sGC) which produces cGMP, the main effector in the vasodilation pathway. An interesting pharmacological strategy is to control the levels of intracellular cGMP, preventing its efflux (with multidrug-resistant protein blockers, such as MK-571), or preventing its degradation (such as sildenafil, which inhibits the enzyme responsible for cGMP degradation, the phosphodiesterase-5 PDE5). This study aimed to look for pharmacological strategies to improve vasodilation LASER effect in normotensive and hypertensive rats (L-NAME model). The vascular reactivity study was performed in isolated aortic rings from normotensive and hypertensive rats, with a single LASER application and sodium nitroprusside (SNP) treatment. In aortic rings from normotensive rats, MK-571 and sildenafil potentiated the relaxation induced by LASER, compared to control. The vasodilation induced by SNP was potentiated by MK-571 and sildenafil, compared to control. In aortic rings from hypertensive rats, vasodilation effect induced by LASER and by SNP was potentiated just by MK-571, compared to control, with no potentiation by sildenafil. In addition, it was seen that the withdrawal of nitric oxide stocks carried out by L-cysteine is capable of being reversed with the use of the SNP. The results support the evidence that the vasodilation induced by red LASER is potentiated by MK-571 and sildenafil in aortic rings from normotensive rats. However, in aortic rings from L-NAME hypertensive rats, the potentiation in vasodilation was induced just by MK-571.

Violet LED induces vasodilation in rat aortic rings by soluble guanylate cyclase-dependent mechanism and increases SOD activity

We found several studies that have used the aortic rings as an experimental model, mainly for the testing of new drugs or new therapies that try to reverse or prevent endothelial dysfunction or characterize its mechanism of action in a biological system, creating the knowledge necessary to obtain the treatment of those several diseases, where many of these treatments involve photobiomodulation therapies. We also found numerous wavelengths represented by different colors of LASER or LED in which frequently, the mechanism of action in biological systems is unknown. This study has as main objective to investigate the effects of the Violet LED Light (405 nm) by using isolated aortic rings, looking for nitric oxide (NO) release, and evaluating if Violet LED Light can modulate the superoxide dismutase (SOD) activity. We performed a vascular reactivity study in isolated aortic rings from normotensive rats with a single LED application. Besides it, the rings were pre-incubated with soluble guanylate cyclase (sGC) inhibitor or endothelial NO synthase inhibitor and subsequently underwent the application of the Violet LED. The cell viability and nitric oxide release in cell culture of human umbilical codon vein cells (HUVEC) were analyzed. In the vascular reactivity experiment, we observed a peak of vasodilation when applying light to the aortic rings. The soluble guanylate cyclase inhibitor abolished the relaxation induced by the Violet LED Light. However, the NO synthase inhibitor did not modify the Violet LED effect. In an isolated system, we verified that the Violet LED Light can increase SOD activity. Our results suggest that Violet LED Light induces vasodilation by a mechanism dependent on sGC activation, and not by NOS activation, and part of this effect could be due to the increase of SOD activity.

Energy-dependent effect trial of photobiomodulation on blood pressure in hypertensive rats

The main purpose of this work was to construct an energy-dependent response curve of photobiomodulation on arterial pressure in hypertension animal model. To reach this objective, we have used a two-kidney one clip (2K-1C) rat model. Animals received acute laser light irradiation (660 nm) on abdominal region using different energy (0.6, 1.8, 3.6, 7.2, 13.8, 28.2, 55.8, and 111.6 J), the direct arterial pressure was measured by femoral cannulation, and systolic arterial pressure (SAP), diastolic arterial pressure (DAP), heart rate (HR), and time of effect were obtained. Our results indicated that 660 nm laser light presents an energy-dependent hypotensive effect, and 28.2 J energy irradiation reached the maximum hypotensive effect, inducing a decreased SAP, DAP, and HR (decrease in SAP: - 19.23 ± 1.82 mmHg, n = 11; DAP: - 9.57 ± 2.23 mmHg, n = 11; HR: - 39.15 ± 5.10 bpm, n = 11; and time of hypotensive effect: 3068.00 ± 719.00 s, n = 11). The higher energy irradiation evaluated (111.6 J) did not induce a hypotensive effect and induced an increase in HR (21.69 ± 7.89 bpm, n = 7). Taken together, our results indicate that red laser energy irradiation from 7.2 to 55.8 J is the effective therapeutic window to reduce SAP, DAP, MAP, and HR and induce a long-lasting hypotensive effect in rats, with effect loss at higher energy irradiation (111.6 J).

In Endothelial Cells, the Activation or Stimulation of Soluble Guanylyl Cyclase Induces the Nitric Oxide Production by a Mechanism Dependent of Nitric Oxide Synthase Activation

PURPOSE

In endothelial cells, investigate if the soluble guanylate cyclase (sGC) activation or stimulation is able to potentiate the relaxation in vessels.

METHODS

Aortic and coronary rings with and without endothelium were placed in a myograph and cumulative concentration-effect curves for DETA-NO or ataciguat were performed. Nitric oxide (NO) were measured by fluorescence or by selective electrode in human umbilical endothelial cells (HUVECs) in response to some treatments, including ataciguat, 8-Br-cGMP and A23187.

RESULTS

The presence of the endothelium potentiated the relaxation induced by DETA-NO in aortic and coronary rings. In addition, in aortic rings the endothelium potentiated the relaxation induced by ataciguat. In the presence of nitric oxide synthase (NOS) inhibitor, the endothelium effect was abolished to DETA-NO or ataciguat, in both vessels. Ataciguat, 8-Br-cGMP and A23187 were able to induce NO production in HUVECs cells. In the presence of NOS inhibitor, the NO production induced by ataciguat and 8-Br-cGMP was abolished.

CONCLUSIONS

Our results suggest that in aortic and coronary rings the endothelium potentiates the relaxation induced by activation or stimulation of sGC through a mechanism dependent of NOS activation. This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.

Endothelial Dysfunction and Inflammation Precedes Elevations in Blood Pressure Induced by a High-Fat Diet

Background

Obesity leads to a chronic inflammatory state, endothelial dysfunction and hypertension.

Objective

To establish the time-course of events regarding inflammatory markers, endothelial dysfunction, systolic blood pressure (SBP) in obesity in only one experimental model.

Methods

We fed male Wistar rats (eight-week age) with a standard diet (Control - CT, n = 35), or palatable high-fat diet (HFD, n = 35) for 24 weeks. Every six weeks, 7 animals from each group were randomly selected for euthanasia. SBP and serum levels of interleukin-6, tumor necrosis factor-α, C-reactive protein, adiponectin and nitric oxide were determined. Endothelial and vascular smooth muscle functions were determined in dissected aorta and lipid peroxidation was measured. Statistical significance was set at p < 0.05.

Results

Levels of pro-inflammatory cytokines began to increase after six weeks of a high-fat diet, while those of the anti-inflammatory cytokine adiponectin decreased. Interestingly, the endothelial function and serum nitric oxide began to decrease after six weeks in HFD group. The SBP and lipid peroxidation began to increase at 12 weeks in HFD group. In addition, we showed that total visceral fat mass was negatively correlated with endothelial function and positively correlated with SBP.

Conclusion

Our results show the time-course of deleterious effects and their correlation with obesity.

Resistance training and caloric restriction prevent systolic blood pressure rise by improving the nitric oxide effect on smooth muscle and morphological changes in the aorta of ovariectomized rats

In this study, we investigated the effects of resistance training (RT), caloric restriction (CR), and the association of both interventions in aortic vascular reactivity and morphological alterations, matrix metalloproteinase-2 (MMP-2) activity, insulin resistance and systolic blood pressure (SBP) in ovariectomized rats. Fifty female Holtzman rats were subjected to ovariectomy and Sham surgery and distributed into the following groups: Sham-sedentary, ovariectomized-sedentary, ovariectomized-resistance training, ovariectomized-caloric restriction, and ovariectomized-resistance training and caloric restriction groups. RT and 30% CR protocols were performed for 13 weeks. Analyses were conducted to evaluate the following: acetylcholine and sodium nitroprusside-induced relaxation of aortic rings, MMP-2 activity, insulin tolerance test, highlighting of the aorta wall cross-sectional area by hematoxylin-eosin stain, aorta vessel remodeling and SBP. We observed that ovariectomy decreased the potency of dependent and independent endothelium relaxation and MMP-2 activity, prevented insulin resistance, promoted aorta vessel remodeling in the cross-sectional area, and promoted the media-to-lumen ratio, the collagen content, and the alteration of the structure and elastic fibers of the vessel. The effects of the ovariectomy could contribute to SBP increases. However, the association of exercise and diet improved the relaxation potency in dependent and independent endothelium relaxation, elevated MMP-2 activity, ameliorate insulin sensitivity, increased the aorta cross-sectional area and media-to-lumen ratio, decreased collagen content and promoted histological parameters of the aorta vessel wall, preventing the increase of SBP.

CONCLUSION

Our study revealed that the RT and CR separately, and even associatively, improved vascular function, activated MMP-2, and produced a beneficial hypertrophic remodeling, preventing the elevation of SBP in ovariectomized rats.

Brain Stimulation Differentially Modulates Nociception and Inflammation in Aversive and Non-aversive Behavioral Conditions

Inflammation and pain are major clinical burdens contributing to multiple disorders and limiting the quality of life of patients. We previously reported that brain electrical stimulation can attenuate joint inflammation in experimental arthritis. Here, we report that non-aversive electrical stimulation of the locus coeruleus (LC), the paraventricular hypothalamic nucleus (PVN) or the ventrolateral column of the periaqueductal gray matter (vlPAG) decreases thermal pain sensitivity, knee inflammation and synovial neutrophilic infiltration in rats with intra-articular zymosan. We also analyzed the modulation of pain and inflammation during aversive neuronal stimulation, which produces defensive behavioral responses such as freezing immobility to avoid predator detection. Electrical stimulation with higher intensity to induce freezing immobility in rats further reduces pain but not inflammation. However, tonic immobility further reduces pain, knee inflammation and synovial neutrophilic infiltration in guinea pigs. The duration of the tonic immobility increases the control of pain and inflammation. These results reveal survival behavioral and neuromodulatory mechanisms conserved in different species to control pain and inflammation in aversive life-threatening conditions. Our results also suggest that activation of the LC, PVN, or vlPAG by non-invasive methods, such as physical exercise, meditation, psychological interventions or placebo treatments may reduce pain and joint inflammation in arthritis without inducing motor or behavioral alterations.

Cortical stimulation in conscious rats controls joint inflammation

The neuronal control of the immune system is fundamental to the development of new therapeutic strategies for inflammatory disorders. Recent studies reported that afferent vagal stimulation attenuates peripheral inflammation by activating specific sympathetic central and peripheral networks, but only few subcortical brain areas were investigated. In the present study, we report that afferent vagal stimulation also activates specific cortical areas, as the parietal and cingulate cortex. Since these cortical structures innervate sympathetic-related areas, we investigate whether electrical stimulation of parietal cortex can attenuate knee joint inflammation in non-anesthetized rats. Our results show that cortical stimulation in rats increased sympathetic activity and improved joint inflammatory parameters, such as local neutrophil infiltration and pro-inflammatory cytokine levels, without causing behavioral disturbance, brain epileptiform activity or neural damage. In addition, we superposed the areas activated by afferent vagal or cortical stimulation to map common central structures to depict a brain immunological homunculus that can allow novel therapeutic approaches against inflammatory joint diseases, such as rheumatoid arthritis.

Resveratrol Treatment Normalizes the Endothelial Function and Blood Pressure in Ovariectomized Rats

Background:

Despite knowing that resveratrol has effects on blood vessels, blood pressure and that phytostrogens can also improve the endothelium-dependent relaxation/vasodilation, there are no reports of reveratrol's direct effect on the endothelial function and blood pressure of animals with estrogen deficit (mimicking post-menopausal increased blood pressure).

Objective:

To verify the effect of two different periods of preventive treatment with resveratrol on blood pressure and endothelial function in ovariectomized young adult rats.

Methods:

3-month old female Wistar rats were used and distributed in 6 groups: intact groups with 60 or 90 days, ovariectomized groups with 60 or 90 days, and ovariectomized treated with resveratrol (10 mg/kg of body weight per day) for 60 or 90 days. The number of days in each group corresponds to the duration of the experimental period. Vascular reactivity study was performed in abdominal aortic rings, systolic blood pressure was measured and serum nitric oxide (NO) concentration was quantified.

Results:

Ovariectomy induced blood pressure increase 60 and 90 days after surgery, whereas the endothelial function decreased only 90 days after surgery, with no difference in NO concentration among the groups. Only longer treatment (90 days) with resveratrol was able to improve the endothelial function and normalize blood pressure.

Conclusion:

Our results suggest that 90 days of treatment with resveratrol is able to improve the endothelial function and decrease blood pressure in ovariectomized rats.

Fundamentos:

Apesar de se saber que o resveratrol apresenta efeitos sobre a pressão arterial e os vasos sanguíneos, e que os fitoestrógenos podem melhorar o relaxamento/vasodilatação dependente do endotélio, não há relatos do efeito direto do resveratrol sobre a pressão arterial e a função endotelial em animais com deficiência de estrógeno (mimetizando a pressão arterial aumentada pós-menopausa).

Objetivo:

Verificar o efeito de dois diferentes períodos de tratamento preventivo com resveratrol sobre a pressão arterial e a função endotelial em ratas adultas jovens ovariectomizadas.

Métodos:

Foram utilizadas ratas Wistar com 3 meses de idade, distribuídas em 6 grupos: grupos intactas com 60 ou 90 dias, grupos ovariectomizadas com 60 ou 90 dias, grupos ovariectomizadas e tratadas com resveratrol na dose de 10mg/kg de massa corporal por dia, durante 60 ou 90 dias, sendo o número de dias em cada grupo relativo à duração do período experimental. Foi realizado um estudo de reatividade vascular em anéis da aorta abdominal, mensurada a pressão arterial sistólica e quantificada a concentração sérica de óxido nítrico (NO).

Resultados:

A ovariectomia induziu aumento da pressão arterial 60 e 90 dias após a cirurgia, enquanto a função endotelial decaiu apenas após 90 dias, e não houve diferença na concentração de NO entre os grupos. Apenas o tratamento prolongado com resveratrol (90 dias) foi capaz de melhorar a função endotelial e normalizar a pressão arterial.

Conclusão:

Nossos resultados sugerem que o tratamento por 90 dias com resveratrol é capaz de melhorar a função endotelial e diminuir a pressão sanguínea em ratas ovariectomizadas.

Ruthenium Complex Improves the Endothelial Function in Aortic Rings From Hypertensive Rats

BACKGROUND:

The endothelium is a monolayer of cells that extends on the vascular inner surface, responsible for the modulation of vascular tone. By means of the release of nitric oxide (NO), the endothelium has an important protective function against cardiovascular diseases.

OBJECTIVE:

Verify if cis- [Ru(bpy)2(NO2)(NO)](PF6)2 (BPY) improves endothelial function and the sensibility of conductance (aorta) and resistance (coronary) to vascular relaxation induced by BPY.

METHODS:

Normotensive (2K) and hypertensive (2K-1C) Wistar rats were used. For vascular reactivity study, thoracic aortas were isolated, rings with intact endothelium were incubated with: BPY(0.01 to10 µM) and concentration effect curves to acetylcholine were performed. In addition, cumulative concentration curves were performed to BPY (1.0 nM to 0.1 µM) in aortic and coronary rings, with intact and denuded endothelium.

RESULTS:

In aorta from 2K-1C animals, the treatment with BPY 0.1µM increased the potency of acetylcholine-induced relaxation and it was able to revert the endothelial dysfunction. The presence of the endothelium did not modify the effect of BPY in inducing the relaxation in aortas from 2K and 2K-1C rats. In coronary, the endothelium potentiated the vasodilator effect of BPY in vessels from 2K and 2K-1C rats.

CONCLUSION:

Our results suggest that 0.1 µM of BPY is able to normalize the relaxation endothelium dependent in hypertensive rats, and the compound BPY induces relaxation in aortic from normotensive and hypertensive rats with the same potency. The endothelium potentiate the relaxation effect induced by BPY in coronary from normotensive and hypertensive rats, with lower effect on coronary from hypertensive rats.

FUNDAMENTO:

O endotélio é uma monocamada de células que se estende sobre a superfície interna vascular, responsável pela modulação do tônus vascular. Por meio da liberação de óxido nítrico (NO), o endotélio tem uma função protetora importante contra doenças cardiovasculares.

OBJETIVO:

Verificar se o cis- [Ru (BPY)2 (NO2) (NO)] (PF6) 2 (BPY) melhora a função endotelial e a sensibilidade da condutância (aorta) e da resistência (coronária) ao relaxamento vascular induzido por BPY.

MÉTODOS:

Foram utilizados ratos Wistar normotensos (2K) e hipertensos (2K-1C). Para o estudo de reatividade vascular, as aortas torácicas foram isoladas, os anéis com endotélio intacto foram incubados com: BPY (0,01 a 10 µM) e se realizaram curvas de efeito de concentração para acetilcolina. Adicionalmente, foram feitas curvas de concentração cumulativas para BPY (1,0 nM a 0,1 µM) nos anéis aórticos e coronários, com endotélio intacto e nu.

RESULTADOS:

Na aorta de animais 2K-1C, o tratamento com BPY 0,1 µM aumentou a potência do relaxamento induzido pela acetilcolina e foi capaz de reverter a disfunção endotelial. A presença do endotélio não modificou o efeito da BPY na indução do relaxamento em aortas de ratos 2K e 2K-1C. Na coronária, o endotélio potencializou o efeito vasodilatador do BPY em vasos de ratos 2K e 2K-1C.

CONCLUSÃO:

Nossos resultados sugerem que 0,1 µM de BPY é capaz de normalizar o relaxamento dependente do endotélio em ratos hipertensos, e o composto BPY induz relaxamento na aorta de ratos normotensos e hipertensos com a mesma potência. O endotélio potencializa o efeito de relaxamento induzido pela BPY em coronárias de ratos normotensos e hipertensos, com menor efeito em coronárias de ratos hipertensos.

Metabolic profiling of human endothelial cells during autophagy assessed in a biomimetic microfluidic device model

AIMS

Autophagy is critical to endothelial function. We explored the effects of autophagy induced by serum deprivation on Human Umbilical Vascular Endothelial Cells (HUVEC) metabolome profile and its inhibition by the antimalarial drug chloroquine (CLQ) using a microfluidic biomimetic model.

MAIN METHODS

The metabolites secreted by HUVEC into the circulating microfluidics were determined by liquid chromatography mass spectrometry (LC-MS) and further analyzed using Metaboanalyst 3.0 multivariate and pathway analysis tools.

KEY FINDINGS

Principal component analysis showed the discrimination of metabolites between treated and control groups. The results also identified alterations in metabolites relevant to endothelial function such as arginine, glutamate and energy metabolism pathways. Interestingly, CLQ mostly reversed the changes induced by serum deprivation.

SIGNIFICANCE

The knowledge of endothelial metabolic profile during autophagy may contribute to the identification of clinical biomarkers and potential therapeutic approaches based on the regulation of autophagy.

In vitro Treatment with cis-[Ru(H-dcbpy-)2(Cl)(NO)] Improves the Endothelial Function in Aortic Rings with Endothelial Dysfunction

PURPOSE

The ruthenium complex cis-[Ru(H-dcbpy-)2(Cl)(NO)] (DCBPY) is a nitric oxide (NO) donor and studies suggested that the ruthenium compounds can inactivate O2-. The aim of this study is to test if DCBPY can revert and/or prevent the endothelial dysfunction.

METHODS

Normotensive (2K) and hypertensive (2K-1C) wistar rats were used. To vascular reactivity study, thoracic aortas were isolated, rings with intact endothelium were incubated with: DCBPY: 0.1; 1 and 10μM, DCBPY plus hydroxocobalin (NO scavenger) or tempol during 30 minutes, and concentration effect curves to acetylcholine were performed. The potency values (pD2) and maximum effect (ME) were analyzed. The O2- was generated using hypoxantine xantine oxidase and the reduction of cytochrome c, NO consumption by O2- and the effect in avoid NO consumption was measured.

RESULTS

In 2K-1C DCBPY at 0.1; 1 or 10μM improved the relaxation endothelium dependent induced by acetylcholine in aortic rings compared to control 2K-1C, and also improved ME. In rings from 2K incubation with DCBPY (0.1; 1.0 and 10 μM) did not change pD2 or ME. Incubation with 0.1 μM of DCBPY plus hydroxocobalamin did not modify the potency and ME in 2K-1C compared to DCBPY (0.1 μM). DCBPY and SOD inhibits the reduction of cytochrome c and inhibited the NO consumption by O2-, showing that O2- has been removed from the solution.

CONCLUSION

Our results suggest that DCBPY at a lower concentration (0.1 µM) is not an NO generator, but can inactivate superoxide and improves the endothelial function.

Inhibition of autophagy by chloroquine stimulates nitric oxide production and protects endothelial function during serum deprivation

BACKGROUND/AIMS

Autophagy plays a fundamental role in cell survival under stress conditions such as nutrient deprivation. Decreased nitric oxide (NO) production, which may contribute to vascular dysfunction, is one of the consequences of autophagy in endothelial cells. The antimalarial drug chloroquine (CLQ) inhibits autophagy by blocking autophagosome formation and has been proposed as adjuvant chemotherapy in other diseases.

METHODS

Autophagy was induced by serum deprivation in Human Umbilical Vascular Endothelial Cells (HUVEC) as demonstrated by formation of Acidic Vesicular Organelles (AVOs), conversion of Microtubule-associated protein 1 light chain (LC3), and Sequestosome-1 (SQTM1/p62) degradation. Using endothelium-dependent vasorelaxation assays, intracellular NO production in an ex vivo rat aortic ring model pre-constricted with phenylephrine was estimated along with DAF-2 DA cell membrane-permeable NO sensitive fluorescent dye.

RESULTS

The inhibition of autophagy by CLQ restored NO levels, protected against superoxide generation and preserved morphology as well as proliferation of HUVEC under serum deprivation. Interestingly, the incubation of rat aortic rings with CLQ resulted in endothelium-dependent relaxation mediated by the increase of NO.

CONCLUSION

These findings emphasize the importance of autophagy in endothelial function and demonstrate the potential use of autophagy inhibitors to protect vascular function during nutrient deprivation.

Deficient regulatory T cell activity and low frequency of IL-17-producing T cells correlate with the extent of cardiomyopathy in human Chagas' disease

Background

Myocardium damage during Chagas' disease results from the immunological imbalance between pro- and production of anti-inflammatory cytokines and has been explained based on the Th1–Th2 dichotomy and regulatory T cell activity. Recently, we demonstrated that IL-17 produced during experimental T. cruzi infection regulates Th1 cells differentiation and parasite induced myocarditis. Here, we investigated the role of IL-17 and regulatory T cell during human Chagas' disease.

Methodology/Principal Findings

First, we observed CD4⁺IL-17⁺ T cells in culture of peripheral blood mononuclear cells (PBMC) from Chagas' disease patients and we evaluated Th1, Th2, Th17 cytokine profile production in the PBMC cells from Chagas' disease patients (cardiomyopathy-free, and with mild, moderate or severe cardiomyopathy) cultured with T. cruzi antigen. Cultures of PBMC from patients with moderate and severe cardiomyopathy produced high levels of TNF-α, IFN-γ and low levels of IL-10, when compared to mild cardiomyopathy or cardiomyopathy-free patients. Flow cytometry analysis showed higher CD4⁺IL-17⁺ cells in PBMC cultured from patients without or with mild cardiomyopathy, in comparison to patients with moderate or severe cardiomyopathy. We then analyzed the presence and function of regulatory T cells in all patients. All groups of Chagas' disease patients presented the same frequency of CD4⁺CD25⁺ regulatory T cells. However, CD4⁺CD25⁺ T cells from patients with mild cardiomyopathy or cardiomyopathy-free showed higher suppressive activity than those with moderate and severe cardiomyopathy. IFN-γ levels during chronic Chagas' disease are inversely correlated to the LVEF (P = 0.007, r = −0.614), while regulatory T cell activity is directly correlated with LVEF (P = 0.022, r = 0.500).

Conclusion/Significance

These results indicate that reduced production of the cytokines IL-10 and IL-17 in association with high levels of IFN-γ and TNF-α is correlated with the severity of the Chagas' disease cardiomyopathy, and the immunological imbalance observed may be causally related with deficient suppressor activity of regulatory T cells that controls myocardial inflammation.

Dilated cardiomyopathy is one of the clinical forms of Chagas' disease (CD) after the infection caused by the parasite Trypanosoma cruzi. Even though strategies adopted in most Latin-American countries in the last decades towards vector control have been effective in reducing the incidence of CD, active transmission is maintained in some regions, and secondary prevention approaches are still required for the infected patients, mostly because the specific anti-parasitic medications are toxic and perhaps of limited efficacy in chronically infected individuals. Moreover, there are no markers to predict the risk of developing dilated cardiomyopathy in asymptomatic, chronically infected patients, although the failure in the mechanisms that control the immune response can be involved in the development of Chagas' heart disease. In this study we show that preserved activity of regulatory T cells and the production of the cytokine IL-17 are connected with a more benign evolution of the disease, which brings a new understanding on the mechanisms associated with progression of CD.

Caveolae Dysfunction Contributes to Impaired Relaxation Induced by Nitric Oxide Donor in Aorta from Renal Hypertensive Rats

Relaxation induced by nitric oxide (NO) donors is impaired in renal hypertensive two kidney-one clip (2K-1C) rat aortas. It has been proposed that caveolae are important in signal transduction and Ca2+ homeostasis. Therefore, in the present study we investigate the integrity of caveolae in vascular smooth muscle cells (VSMCs), as well as their influence on the effects produced by NO released from both the new NO donor [Ru(NH.NHq) (terpy)NO+]3+ (TERPY) and sodium nitroprusside (SNP) on 2K-1C rat aorta. The potency of both TERPY and SNP was lower in the 2K-1C aorta that in the normotensive aorta [two kidney (2K)], whereas the maximal relaxant effect (ME) was similar in both 2K-1C and 2K aortas. In the 2K aorta, methyl-beta-cyclodextrin (CD) reduced both the potency of TERPY and SNP, and their ME compared with the control, but it had no effect on the potency and ME of these NO donors in 2K-1C aortas. The decrease in cytosolic Ca2+ concentration ([Ca2+]c) induced by TERPY was larger in 2K than in 2K-1C cells, and this effect was inhibited by CD in 2K cells only. Aortic VSMCs from 2K rats presented a larger number of caveolae than those from 2K-1C rats. Treatment with CD reduced the number of caveolae in both 2K and 2K-1C aortic VSMCs. Our results support the idea that caveolae play a critical role in the relaxant effect and in the decrease in [Ca2+]c induced by NO, and they could be responsible for impaired aorta relaxation by NO in renal hypertensive rats.