Bax inhibitor 1 inhibits vascular calcification in mice by activating optic atrophy 1 expression / 南方医科大学学报

OBJECTIVE@#To investigate the effects of Bax inhibitor 1 (BI- 1) and optic atrophy protein 1 (OPA1) on vascular calcification (VC).@*METHODS@#Mouse models of VC were established in ApoE-deficient (ApoE-/-) diabetic mice by high-fat diet feeding for 12 weeks followed by intraperitoneal injections with Nε-carboxymethyl-lysine for 16 weeks. ApoE-/- mice (control group), ApoE-/- diabetic mice (VC group), ApoE-/- diabetic mice with BI-1 overexpression (VC + BI-1TG group), and ApoE-/- diabetic mice with BI-1 overexpression and OPA1 knockout (VC+BI-1TG+OPA1-/- group) were obtained for examination of the degree of aortic calcification using von Kossa staining. The changes in calcium content in the aorta were analyzed using ELISA. The expressions of Runt-related transcription factor 2 (RUNX2) and bone morphogenetic protein 2 (BMP-2) were detected using immunohistochemistry, and the expression of cleaved caspase-3 was determined using Western blotting. Cultured mouse aortic smooth muscle cells were treated with 10 mmol/L β-glycerophosphate for 14 days to induce calcification, and the changes in BI-1 and OPA1 protein expressions were examined using Western blotting and cell apoptosis was detected using TUNEL staining.@*RESULTS@#ApoE-/- mice with VC showed significantly decreased expressions of BI-1 and OPA1 proteins in the aorta (P=0.0044) with obviously increased calcium deposition and expressions of RUNX2, BMP-2 and cleaved caspase-3 (P= 0.0041). Overexpression of BI-1 significantly promoted OPA1 protein expression and reduced calcium deposition and expressions of RUNX2, BMP-2 and cleaved caspase-3 (P=0.0006). OPA1 knockdown significantly increased calcium deposition and expressions of RUNX2, BMP-2 and cleaved caspase-3 in the aorta (P=0.0007).@*CONCLUSION@#BI-1 inhibits VC possibly by promoting the expression of OPA1, reducing calcium deposition and inhibiting osteogenic differentiation and apoptosis of the vascular smooth muscle cells.

Tyrosine phosphorylation of Kv1. 5 is upregulated in intrauterine growth retardation rats with exaggerated pulmonary hypertension

Intrauterine growth retardation (IUGR) is associated with the development of adult-onset diseases, including pulmonary hypertension. However, the underlying mechanism of the early nutritional insult that results in pulmonary vascular dysfunction later in life is not fully understood. Here, we investigated the role of tyrosine phosphorylation of voltage-gated potassium channel 1.5 (Kv1.5) in this prenatal event that results in exaggerated adult vascular dysfunction. A rat model of chronic hypoxia (2 weeks of hypoxia at 12 weeks old) following IUGR was used to investigate the physiological and structural effect of intrauterine malnutrition on the pulmonary artery by evaluating pulmonary artery systolic pressure and vascular diameter in male rats. Kv1.5 expression and tyrosine phosphorylation in pulmonary artery smooth muscle cells (PASMCs) were determined. We found that IUGR increased mean pulmonary artery pressure and resulted in thicker pulmonary artery smooth muscle layer in 14-week-old rats after 2 weeks of hypoxia, while no difference was observed in normoxia groups. In the PASMCs of IUGR-hypoxia rats, Kv1.5 mRNA and protein expression decreased while that of tyrosine-phosphorylated Kv1.5 significantly increased. These results demonstrate that IUGR leads to exaggerated chronic hypoxia pulmonary arterial hypertension (CH-PAH) in association with decreased Kv1.5 expression in PASMCs. This phenomenon may be mediated by increased tyrosine phosphorylation of Kv1.5 in PASMCs and it provides new insight into the prevention and treatment of IUGR-related CH-PAH.

Lymphangioleiomyomatosis - Retroperitoneum.

Lymphangioleiomyomatosis (LAM) is a progressive disease affecting women of childbearing age. It is microscopically characterized by abnormal smooth muscle proliferation in the walls of lymphatics and lymph nodes. A 52-year old female presented with pain in left leg and bilateral pedal oedema. USG and CT abdomen revealed a retroperitoneal cystic mass suspicious of malignancy. Retroperitoneal exploration was done and the mass was excised which revealed milky contents within. On gross examination of the specimen, a spongy mass was noted . Histopathological examination led to a diagnosis of lymphangioleiomyomatosis. LAM is a rare disease unfamiliar to many physicians and may pose a diagnostic dilemma to the physician, possibly resulting in delayed or missed diagnosis . Many treatment modalities including corticosteroids, cytotoxic drugs, chemotherapy, radiation and hormonal therapy are suggested. The prognosis of LAM varies with the individual, but many patients respond well to intramuscular medroxyprogesterone injections.

Short-term exposure of mice to cigarette smoke and/or residual oil fly ash produces proximal airspace enlargements and airway epithelium remodeling

Chronic obstructive pulmonary disease (COPD) is associated with inflammatory cell reactions, tissue destruction and lung remodeling. Many signaling pathways for these phenomena are still to be identified. We developed a mouse model of COPD to evaluate some pathophysiological mechanisms acting during the initial stage of the disease. Forty-seven 6- to 8-week-old female C57/BL6 mice (approximately 22 g) were exposed for 2 months to cigarette smoke and/or residual oil fly ash (ROFA), a concentrate of air pollution. We measured lung mechanics, airspace enlargement, airway wall thickness, epithelial cell profile, elastic and collagen fiber deposition, and by immunohistochemistry transforming growth factor-β1 (TGF-β1), macrophage elastase (MMP12), neutrophils and macrophages. We observed regional airspace enlargements near terminal bronchioles associated with the exposure to smoke or ROFA. There were also increases in airway resistance and thickening of airway walls in animals exposed to smoke. In the epithelium, we noted a decrease in the ciliated cell area of animals exposed to smoke and an increase in the total cell area associated with exposure to both smoke and ROFA. There was also an increase in the expression of TGF-β1 both in the airways and parenchyma of animals exposed to smoke. However, we could not detect inflammatory cell recruitment, increases in MMP12 or elastic and collagen fiber deposition. After 2 months of exposure to cigarette smoke and/or ROFA, mice developed regional airspace enlargements and airway epithelium remodeling, although no inflammation or increases in fiber deposition were detected. Some of these phenomena may have been mediated by TGF-β1.

Transforming growth factor-β in graft vessels: histology and immunohistochemistry

OBJECTIVES: The biological functions of transforming growth factor-β signaling that involves Smad proteins have not been previously investigated with respect to coronary artery bypass grafts. The aim of the present study was to observe the immunostaining of proteins that are related to this signaling pathway. METHODS: Fifteen remnants of coronary artery bypass grafts, including nine saphenous veins, three radial arteries and three mammary arteries, were collected from 12 patients who were undergoing coronary artery bypass. Hematoxylin and eosin, Masson's trichrome, and immunohistochemical staining of transforming growth factor-β1, type I receptor of transforming growth factor-β, Smad2/3, Smad4, and Smad7 were performed. RESULTS: The saphenous veins showed more severe intimal degeneration, more severe smooth muscle cell proliferation and more collagen deposition than the arterial grafts, as evidenced by hematoxylin and eosin and Masson's trichrome stainings. Immunohistochemical assays demonstrated that the majority of the transforming growth factor-β1 signaling cytokines were primarily localized in the cytoplasm in the medial layers of all three types of grafts, whereas ectopic transforming growth factor-β1, type I receptor of transforming growth factor-β, and Smad7 overexpressions in the interstices were observed particularly in the saphenous vein and radial arterial grafts. CONCLUSION: Enhanced transforming growth factor-β1 signal transduction with medial smooth muscle cell proliferation and ectopic transforming growth factor-β1, the presence of the type I receptor of transforming growth factor-β, and Smad7 overexpressions in the extracellular matrix may provide primary evidence for early or late graft failure.

Abnormal proliferative response of the carotid artery of spontaneously hypertensive rats after angioplasty may be related to the depolarized state of its smooth muscle cells

Hypertension is one of the major precursors of atherosclerotic vascular disease, and vascular smooth muscle abnormal cell replication is a key feature of plaque formation. The present study was conducted to examine the relationship between hypertension and smooth muscle cell proliferation after balloon injury and to correlate neointima formation with resting membrane potential of uninjured smooth muscle cells, since it has been suggested that altered vascular function in hypertension may be related to the resetting of the resting membrane potential in spontaneously hypertensive rats (SHR). Neointima formation was induced by balloon injury to the carotid arteries of SHR and renovascular hypertensive rats (1K-1C), as well as in their normotensive controls, i.e., Wistar Kyoto (WKY) and normal Wistar (NWR) rats. After 14 days the animals were killed and the carotid arteries were submitted to histomorphometric and immunohistochemical analyses. Resting membrane potential measurements showed that uninjured carotid arteries from SHR smooth muscle cells were significantly depolarized (-46.5 + or - 1.9 mV) compared to NWR (-69 + or - 1.4 mV), NWR 1K-1C (-60.8 + or - 1.6 mV), WKY (-67.1 + or - 3.2 mV) and WKY 1K-1C (-56.9 + or - 1.2 mV). The SHR arteries responded to balloon injury with an enhanced neointima formation (neo/media = 3.97 + or - 0.86) when compared to arteries of all the other groups (NWR 0.93 + or - 0.65, NWR 1K-1C 1.24 + or - 0.45, WKY 1.22 + or - 0.32, WKY 1K-1C 1.15 + or - 0.74). Our results indicate that the increased fibroproliferative response observed in SHR is not related to the hypertensive state but could be associated with the resetting of the carotid smooth muscle cell resting membrane potential to a more depolarized state

Smooth muscle cell diversity and the extracellular matrix in a rat model of restenosis

Clear differences exist in the incidence and severity of atherosclerotic plaques that arise in different segments of the arterial tree. Aortic homograft transplant experiments in dogs showed that the greater incidence of plaque formation in the abdominal versus the thoracic aorta was due to intrinsic differences in the cell populations in these two segments rather than to hemodynamic factors. What is the basis for SMC diversity within a common vessel wall? Recent lineage analysis studies in the avian and mammalian embryo indicate that two distinct SMC lineages contribute to the formation of the major elastic outflow arteries including the aorta. A mixture of unique SMC types of diverse developmental lineages within a common vessel wall raises new questions about the potential for SMC type-specific responses to growth factors and cytokines involved in human atherosclerosis and restenosis

Células de músculo liso: organo blanco en cardiología

La proliferación rápida de células de músculo liso vascular (CMLV) es un fenómeno que ha sido reconocido como evento central de varias formas de enfermedad vascular: Aterosclerosis, hipertensión arterial, restenosis coronaria luego de angioplastia percutánea. Avances recientes en las últimas dos décadas, han generado hipótesis claras en cuanto a la génesis de estas tres patologías, donde la CMLV son común denominador. La presencia de múltiples factores que interactúan en el organismo (mecánicos, hemodinámicos, celulares, plasmáticos, nerviosos, hormonales, humorales, etc) sobre las CMLVs para su recambio constante de fenotipo, reflejan la complejidad en la fisiopatología vascular. La importancia en el conocimiento de la CMLV y su comportamiento ante el trauma es cada vez mayor y se refleja en el entendimiento de la enfermedad y en el gran adelanto de las diferentes formas terapéuticas

The role of cadmium in induction of atherosclerosis in rabbits.

Experiments were carried out in rabbits to determine the effects of prolonged treatment of cadmium (8 mg/kg/day) for a period of 6 months on histopathological changes and biochemical alterations of lipid profiles in various tissues compared to normal rabbits. No ECG changes were observed before and at the end of cadmium treatment. Histopathological studies of the coronary artery revealed atherosclerotic changes. Total lipids, cholesterol, free fatty acids and phospholipids were significantly increased in heart and kidney, but decreased in serum and liver. Triglyceride content was increased significantly in heart and kidney with a significant depletion in liver and serum. It is postulated that atherosclerotic changes in rabbits probably occurred through toxic effects of cadmium but the exact mechanism needs to be elucidated.