Rapamycin Improves Vascular Remodelling in a Controlled Rat Model of Monocrotaline-Induced Pulmonary Hypertension

ABSTRACT Background: Pulmonary arterial hypertension (PAH) is a serious disease characterized by the progressive elevation of the pulmonary arterial resistance, leading to the right ventricular failure and death. Objective: To evaluate the effect of rapamycin (RAPA), a potent cell-cycle inhibitor, on exercise capacity, right ventricular hypertrophy and pulmonary vascular remodelling on rats. Methods: A total of 39 nine-week-old male Wistar rats (160-240 g) were divided into three groups: the control (n = 10), PAH control (n = 15) and PAH-RAPA (n = 14) groups. On the 1st day, 60 mg/kg monocrotaline was injected intraperitoneally to induce PAH in the PAH control group and PAH-RAPA groups. On the 21st day, 3 mg/kg/day RAPA was started orally, and the animals were followed for 35 days. On the 35th day, the exercise capacity of the rats was analysed through a modified forced swimming test. After measuring their right ventricular systolic pressure using an open-chest method, their hearts and lungs were excised and analysed histopathologically for right ventricular hypertrophy and pulmonary vascular remodelling. Results: Rapamycin treatment provided limited and insignificant improvements in exercise capacity, right ventricular systolic pressure and right ventricular hypertrophy of the rats. However, there was significant recovery in the rats' pulmonary artery muscular layer thickness with the RAPA treatment (p < 0.049). On the 35th day, the mortality rate was 0% in the control group, 53.1% in the PAH control group and 42.9% in the PAH-RAPA group. No statistically significant decrease was observed in their mortality rates with the RAPA treatment (p > 0.16); however, a significant recovery was noted in terms of the rats' median life span (p < 0.006). Conclusion: Pulmonary artificial hypertension is a progressive disease that is not curable with current therapies. Rapamycin may have the potential to reverse vascular remodelling and prolong life expectancy in cases of pulmonary hypertension.

Passiflora quadrangularis L. prevents experimental hypertension and vascular remodelling in rats exposed to nitric oxide deficit / Passiflora quadrangularis L. previene la hipertensión experimental y el remodelado vascular en ratas expuestas a déficit de óxido nítrico

Background: Passiflora quadrangularis L. is among the species used in Colombian folk medicine for hypertension, but until now it has not been studied in experimental models. Objectives: To assess the capacity of P. quadrangularis L. EtOH extract to prevent the hypertension and vascular remodelling induced by nitric oxide (NO) deficit in Wistar rats. Methods: The nitric oxide (NO) synthase inhibitor L-NAME (10 mg/kg, i.p (intraperitoneal), every 48h) was administered for seven weeks to the following groups of rats: P. quadrangularis L.75, 150 and 300 mg/kg/d, p.o. (oral route); enalapril as reference agent, 10 mg/kg/d, p.o. and vehicle as control (mixture of propylene glycol 10%, glycerine 10% and polysorbate 2%). Arterial blood pressure (BP) and heart rate (HR) were measured twice a week. After sacrifice, the aortic rings were isolated, contraction was triggered with phenylephrine (PE 10-6 M) and then the relaxant response achieved with cumulative concentrations of acetylcholine (ACh, 10-10 ­ 10-5 M) or sodium nitroprusside (SNP, 10-10 ­ 10-5 M) was assessed. Histopathologic measures of thickness/lumen ratio from both the left ventricle and aorta walls, as well as phytochemical screening, were also performed. Results: As for enalapril, all doses of P. quadrangularis L. prevented the hypertension induced by L-NAME (122±1.2 versus 155±1.3 mmHg at seventh week). P. quadrangularis L. significantly increased the relaxant effect induced by ACh in isolated aorta and decreased the thickness/lumen ratio of aorta wall specimens. Conclusions: P. quadrangularis L. prevents experimental hypertension induced in rats with nitric oxide deficits improving the endothelium vasodilatation response and protecting against vascular remodelling.

Antecedentes: Passiflora quadrangularis L. es una de las especies utilizadas en medicina tradicional en Colombia para la hipertensión pero hasta el momento no se ha evaluado en modelos experimentales. Objetivos: Evaluar la capacidad del extracto etanólico de P. quadrangularis L. para prevenir la hipertensión y el remodelado vascular inducidos por déficit de óxido nítrico (NO) en ratas Wistar. Métodos: El inhibidor de la óxido nítrico (NO) sintasa L-NAME (10 mg/kg, i.p, cada 48 h) se administró durante siete semanas a los siguientes grupos de tratamiento: P. quadrangularis L. 75, 150 y 300 mg/kg/d, p.o; Enalapril como agente de referencia, 10 mg/kg/d, p.o., y vehículo como control (mezcla de propilenglicol 10%, glicerina 10% y polisorbato 2%). Se midió la presión arterial (BP) y la frecuencia cardiaca (HR) dos veces por semana. Después del sacrificio, se aislaron los anillos aórticos, se desencadenó la contracción con fenilefrina (PE 10-6 M) y la respuesta relajante con concentraciones acumulativas de acetilcolina (ACh, 10-10 ­ 10-5 M) o nitroprusiato de sodio (SNP, 10-10 ­ 10-5 M). También se realizaron estudios histopatológicos de la relación entre el espesor y el lumen tanto en el ventrículo izquierdo como en las paredes de la aorta, así como un cribado fitoquímico. Resultados: Enalapril y todas las dosis de P. quadrangularis L. evitaron la hipertensión inducida por L-NAME (122 ± 1,2 frente a 155 ± 1,3 mm Hg a la séptima semana). P. quadrangularis L. aumentó significativamente el efecto relajante inducido por ACh en la aorta aislada y disminuyó la relación entre el espesor y la luz de los especímenes en la pared de la aorta. Conclusiones: P. quadrangularis L. previene la hipertensión experimental inducida por déficit de óxido nítrico en ratas, mejorando la respuesta del endotelio y protegiendo frente al remodelado vascular.

Identification of MicroRNAs with Altered Expression Profiles in a Rat Model of Experimentally Induced Early Cerebral Aneurysms / 대한신경손상학회지

OBJECTIVE: Structural adaptation of the vascular wall may occur due to various factors, such as shear stress, pressure, injury or inflammation. The role of microRNAs (miRNAs) in the development of vascular remodeling has been investigated in several studies. Recently, the authors reported altered expression profiles of miRNAs in late stage of experimentally induced giant cerebral aneurysm (CA) in rat models. But, early biologic roles of miRNAs in CA formation have not been explained yet. We employed microarrays analysis to identify miRNA expression profiles in early stage of CA in rat model and to compare with those in late stage of giant CA. METHODS: Seventy, 7-week-old male Sprague-Dawley rats underwent a CA induction procedure. The control animals (n=11) were fed a regular diet, and the experimental animals (n=59) were fed a regular diet with 1% normal saline for two months. Then, the rats were killed, their cerebral arteries were dissected, and the 13 regions of early aneurysmal change on the right olfactory artery-anterior cerebral artery bifurcation were cut for miRNA microarrays analysis. Six miRNAs (miRNA-1, miRNA-448, miRNA-352, miRNA-551b, miRNA-431, and miRNA-485) were randomly chosen for validation using real-time quantitative polymerase chain reaction. RESULTS: Among a set of differentially expressed miRNAs, 15 miRNAs were up-regulated more than 200% and five miRNAs were down-regulated less than 50% in the early CA tissues. CONCLUSIONS: This study provides an overall view of miRNA expression profiles in experimentally induced early CAs and strongly supports the idea that some miRNAs, such as miR-31 and miR-27a, play an important role in pathological processes in early CA formation. Further investigations to detect their exact roles of these miRNAs in the pathogenesis of CA are needed.

Transforming growth factor-1 induces angiogenesis in vitro via VEGF production in human airway smooth muscle cells.

Increase in size and number of bronchial blood vessels as well as hyperaemia are factors that contribute to airway wall remodelling in patients with chronic airway diseases, such as asthma and chronic obstructive pulmonary diseases (COPD). Expression of transforming growth factor 1 (TGF-1), a multifunctional cytokine as well as vascular endothelial growth factor (VEGF), a key angiogenic molecule, has been shown in the inflammed airways in patients with chronic airway diseases. TGF-1 has been implicated in the regulation of extracellular matrix, leading to airway remodelling in patients with chronic airway diseases. However, the role of TGF-1 in regulating VEGF expression in patients with chronic airway diseases, as well as the underlying mechanisms are not yet well established. We investigated whether TGF-1 stimulates VEGF expression in vitro and hence could influence vascular remodelling. Cultured human airway smooth muscle cells (HASMC) were serum deprived for 60 h before incubation with 5ng/ml of TGF-1 for different time points. Control cells received serum-free culture medium. TGF‑1, treatment resulted in time dependent HASMC cell proliferation with maximal values for DNA biosynthesis at 24 h and cell number at 48 h. Northern blot analysis of VEGF mRNA expression showed increased levels in cells treated with TGF-1 for 4 to 8 h. TGF-1 also induced a time-dependent release of VEGF proteins in the conditioned medium after 48 h of treatment. Furthermore, the ability of HASMC-released VEGF proteins to induce human umbilical vein endothelial cells proliferation was inhibited by VEGF receptor antagonist, confirming that TGF-1 induced VEGF was biologically active. We conclude that TGF-1 in addition to an extracellular matrix regulator also could play a key role in bronchial angiogenesis and vascular remodelling via VEGF pathway in asthma.