中介素抑制高肺血流性肺动脉高压大鼠肺组织胶原生成

 目的:研究中介素（IMD）对高肺血流性肺动脉高压大鼠肺组织胶原生成和沉积的调节作用及其机制。方法: 健康雄性SD大鼠20只,随机分为对照组（n=7）、分流组（n=7）和分流+IMD组（n=6）。对后2组大鼠行腹主动脉-下腔静脉分流术。8周后,对分流+IMD组大鼠,皮下埋微量渗透泵持续给予IMD 1.5 μg·kg-1·h-1。继续饲养2周后,比较各组大鼠肺动脉平均压（mPAP）、肺中、小动脉相对中膜厚度（RMT）,肺组织羟脯氨酸、Ⅰ和Ⅲ 型胶原、骨形成蛋白-2（BMP-2）含量和I、III型前胶原mRNA表达水平。结果: 与对照组相比,分流组大鼠mPAP明显上升,肺中、小动脉RMT明显增加,肺组织羟脯氨酸和Ⅰ、Ⅲ型胶原含量明显增多,Ⅰ、Ⅲ型前胶原mRNA表达上调,BMP-2含量明显增多。IMD则使分流大鼠肺动脉压力明显回降,肺血管结构改变缓解,胶原沉积减少,BMP-2含量降低,Ⅰ、Ⅲ 型前胶原mRNA表达下调。结论: IMD可通过抑制高肺血流大鼠肺组织胶原生成和沉积,缓解高肺血流性肺动脉高压和肺血管结构重构形成,该作用可能与BMP-2途径有关。     

Expression of human herpesvirus 8 in primary pulmonary hypertension

Severe pulmonary hypertension constitutes a group of diseases characterized by complex, lumen-occluding vascular lesions that develop in genetically susceptible persons. The only viral infection associated with severe pulmonary hypertension has been that due to human immunodeficiency virus type 1, but neither the viral genome nor viral antigens have been demonstrated in pathologic lesions.     

New findings in pulmonary arteries of rats with hypoxia-induced pulmonary hypertension.

Rats have been kept in a hypobaric chamber, and thus hypoxic, for up to 28 days in order to study the structural changes in the pulmonary arteries during the development of pulmonary hypertension. Rats were studied after 3, 5, 7, 10, 14, 21 and 28 days at a pressure of 380 mmHg. Right ventricular hypertrophy was demonstrated after 5 days in the hypoxic environment but increased up to 10 days. After pulmonary arterial injection microscopic counts of small arteries showed that vessels up to 200 mum external diameter were gradually "lost", reducing the ratio of arterial to alveolar number significantly by 14 days. No vestiges of these vessels were found with light microscopy. At the same time a gradual increase in arterial wall thickness was demonstrated and also progressive extension of muscle into smaller and more peripheral vessels than normal. In both these features maximum increase was reached by 14 days of exposure though changes were apparent after only 3. Similar changes have been found in patients with cystic fibrosis and chronic bronchitis using the same measuring techniques.     

Active macrophage-associated TGF-beta co-localizes with type I procollagen gene expression in atherosclerotic human pulmonary arteries.

Vascular remodeling in adult atherosclerotic pulmonary arteries is characterized by discrete areas of neointimal smooth muscle cell extracellular matrix gene expression in close proximity to non-foamy macrophages, suggesting regulation by local macrophage-associated factors. The purpose of these studies was to begin addressing the role of putative macrophage-associated factors such as transforming growth factor-beta (TGF-beta), by determining the spatial relationship between TGF-beta and neointimal matrix gene expression in human atherosclerotic pulmonary arteries. For example, the participation of TGF-beta in vascular remodeling could be inferred by its colocalization with non-foamy macrophages in areas of active matrix synthesis. In situ hybridization and immunohistochemistry demonstrated focal neointimal procollagen gene expression in close association with non-foamy but not foamy macrophages. Immunohistochemistry with isoform-specific anti-TGF-beta antibodies demonstrated all three isoforms of TGF-beta associated with non-foamy macrophages, but foamy macrophages were not immunoreactive. Neointimal and medial smooth muscle cells stained lightly. In contrast, intense TGF-beta immunoreactivity was also associated with medial smooth muscle cells in normal nonremodeling vessels. Immunohistochemistry with antibodies specific for latent TGF-beta was similar to immunohistochemistry for mature TGF-beta in both remodeling and nonremodeling vessels. Finally, using an antibody specific for active TGF-beta 1, immunoreactivity was only seen in non-foamy neointimal macrophages but not in foamy macrophages or medial smooth muscle cells from hypertensive or normal vessels. These observations suggest non-foamy macrophages may participate in modulating matrix gene expression in atherosclerotic remodeling via a TGF-beta-dependent mechanism.     

Regional heterogeneity of elastin and collagen gene expression in intralobar arteries in response to hypoxic pulmonary hypertension as demonstrated by in situ hybridization.

In situ hybridization was used to determine the morphologic distribution of tropoelastin and alpha 1(I) procollagen mRNA expression in elastic intralobar arteries from neonatal calves with hypoxic pulmonary hypertension induced by a 15-day exposure to a simulated altitude of 1500 m. In vessels from normotensive control animals, low levels of hybridizable tropoelastin mRNA were detected in smooth muscle cells (SMC) of the inner media associated with large elastic lamellae. Compared to control arteries, vessels from hypertensive animals demonstrated a markedly different pattern of hybridization. In these arteries, strong hybridization signals for tropoelastin mRNA were seen in SMC lying between the elastic lamellae of the outer media, and the density of labeling associated with these medial cells decreased progressively toward the lumen. Endothelial and adventitial cells in both control and hypertensive arteries were negative for tropoelastin mRNA. Type I procollagen mRNA was dispersed through the media of control arteries, and in hypertensive calves, the hybridization signal was more intense and was unevenly distributed through the media similarly to that for tropoelastin mRNA. Adventitial cells were strongly positive for procollagen mRNA, and the signal was equally intense for both control and hypertensive arteries. Cells that had no detectable tropoelastin mRNA were noted in the outer media of both control and hypertensive vessels. These cells occurred as broad circumferential bands in the normotensive artery and as nodular foci in the hypertensive artery. Immunocytochemical studies with antibodies to smooth muscle specific actin, desmin, and vimentin demonstrated that cells within these foci, as well as tropoelastin mRNA-positive cells, were SMC. These studies demonstrate that expression of tropoelastin and procollagen mRNA was differentially stimulated by pulmonary hypertension within specific regions and SMC populations of the vascular wall.     

Altered elastin and collagen synthesis associated with progressive pulmonary hypertension induced by monocrotaline. A biochemical and ultrastructural study

Changes in elastin and collagen synthesis in the pulmonary artery wall, assessed both biochemically and ultrastructurally, were related to the development of progressive pulmonary hypertension induced by the toxin monocrotaline. Male Sprague-Dawley rats (200 to 225 gm) were injected subcutaneously in the hind flank with either monocrotaline (60 mg/kg) or an equivalent volume of saline and studied 8, 16 and 28 days later. At each time point, the right ventricle and left ventricle with septum were separated and weighed to follow the development of right ventricular hypertrophy. The hilar pulmonary artery was assessed by light microscopy for medial hypertrophy and by electron microscopy for changes in the endothelium, subendothelium and media. The mainstem pulmonary artery was used to determine synthesis of elastin and collagen by in vitro incorporation of [14C]proline into nonelastin, [14C]hydroxyproline into collagen, and [3H]valine into cyanogen bromide-insoluble elastin. In addition, total content of insoluble elastin was determined by weight of the residue after cyanogen bromide digestion and of collagen by total hydroxyproline content in sodium dodecyl sulfate and cyanogen bromide extracts. Eight days after monocrotaline injection, there was pulmonary artery endothelial swelling and a significant decrease in the number of myoendothelial junctions (p less than 0.05) associated with a decreased proportion of amorphous elastin in the media (p less than 0.01). Sixteen days after monocrotaline injection, a decrease in the proportion of elastin in the media was still evident (p less than 0.01) despite an apparent increase in insoluble elastin synthesis. Moreover, the amorphous elastin was distributed preferentially in small islands rather than in laminae (p less than 0.05). Twenty-eight days after monocrotaline injection, medial and right ventricular hypertrophy had developed (p less than 0.05 and p less than 0.01, respectively). At the same time, there was a striking increase in both insoluble elastin synthesis and total insoluble elastin content (p less than 0.01 for both) and an increase in collagen synthesis and total collagen content (p less than 0.05 for both). In addition, the ratio of insoluble elastin synthesis to collagen synthesis was greater than in controls (p less than 0.01), whereas the ratio of total insoluble elastin to total collagen did not change. On ultrastructural analysis, the proportion of amorphous elastin in the vessel wall relative to other elements remained low (p less than 0.01) and was distributed throughout the media as increased numbers of small islands (p less than 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)     

Changes in the pulmonary arteries of the rat during recovery from hypoxia-induced pulmonary hypertension.

Pulmonary hypertension has been induced in rats by 2 weeks' exposure to hypoxia, equivalent to an altitude of approximately 5500 m, in a hypobaric chamber. The rats were removed from the chamber and allowed to recover for up to 8 weeks at atmospheric pressure. Precise quantitative microscopic techniques after injection of the pulmonary artery have been used to estimate the regression in the pulmonary artery of the structural changes associated with pulmonary hypertension. During recovery the degree of muscularization of the pulmonary arteries decreases by disappearance of muscle cells from the small arteries and a drop in arterial wall thickness of larger vessels. These changes do not seem to reflect pulmonary artery pressure directly, since right ventricular hypertrophy regresses at a faster rate. In hypertensive rats there is a "loss" of small arteries in the alveolar region and little filling of precapillary vessels. On recovery, some of the vessels fill, suggesting that encroachment on the lumen by muscle and endothelial cells has lessened. Even after 8 weeks' recovery, however, some arteries do not return, suggesting they have completely disappeared and that regions are left with relatively little perfusion. This reduction of vascular reserve presents without there being right ventricular hypertrophy.     

Remodelling of the pulmonary arteries during recovery from pulmonary hypertension induced by neonatal hypoxia

Little is understood of the mechanisms involved in reducing pulmonary arterial wall thickness on recovery from pulmonary hypertension and the present study sought to clarify the events that occur. Piglets were exposed to hypobaric hypoxia for 3 days, either from birth or from 3 days of age, and others were exposed for 11 days starting at 3 days. All recovered in room air for up to 6 days. Using light and electron microscopy, the pulmonary artery wall thickness, the relative contribution of smooth muscle and matrix, smooth muscle cell replication, and apoptosis were assessed after hypoxic exposure and during recovery from hypoxic exposure. In elastic arteries, after 6 days' recovery in room air, a reduction in wall thickness to normal was associated with a similar reduction in proportional area of smooth muscle cells and matrix (p < 0.05), increased apoptosis (p < 0.05), and an abnormally low replication rate (p < 0.05). In peripheral muscular arteries, an increase in external diameter, and wall thinning on recovery, was achieved by smooth muscle cell remodelling and a reduction in cell replication (p < 0.05). Apoptosis did not contribute. Thus, different mechanisms are involved in recovery from hypoxia-induced pulmonary hypertension in elastic and muscular pulmonary arteries. Recovery is slower in animals exposed from birth rather than from 3 days of age.     

Felodipine in primary pulmonary hypertension. Report of two cases

Two women with primary pulmonary hypertension were treated with felodipine, a vasodilating agent. A marked reduction in pulmonary artery pressure was noted in one, whereas the other showed no reduction in pressure but an increase in blood flow and a decrease in pulmonary vascular resistance.     

Modulation of collagen synthesis in human glomerular epithelial cells by interleukin 1.

Human glomerular epithelial cells produce matrix material e.g. collagen type IV. In vitro, the synthesis of collagen can be monitored by the incorporation of 3H-proline, a precursor molecule of the collagens. We report on the enhancement of collagen synthesis by glomerular epithelial cells with highly purified or recombinant I1-1. Since I1-1 is released from monocytes or glomerular mesangial cells by inflammatory mediators, our results point to a participation of I1-1 in the development of sclerosis, which is seen in many forms of chronic inflammatory diseases.     

Medial collagen organization in human arteries of the heart and brain by polarized light microscopy.

The mechanical properties of collagen as a biopolymer ensures that collagen has a significant influence on the mechanical behavior of the host tissue. Structural organization is a key to that influence. We have assessed this relationship quantitatively in the tunica media of arteries from the heart and brain, using the polarizing light microscope and Universal stage. Arteries from 22 autopsies were isolated, cannulated and fixed with 10% buffered formalin, at a distending pressure spanning normal values in vivo. We prepared the tissue for light microscopy, with paraffin embedding, sectioning at 7 microns, and staining with picrosirius red to enhance the natural birefringence of medial collagen. Individual measurements, 30 to 50 per arterial section, referenced against the central axis of the vessel segment, revealed a coherent organization, with an average orientation which was within 1 to 2 degrees of being perfectly concentric for all artery segments. Analysis was done with Lambert projections and circular statistics. We calculated the circular standard deviation, which was 5.2 degrees for 27 brain arteries (S.D. 1.9 degrees) and 5.6 degrees (S.D. 2.1 degrees), for 5 coronary arteries sectioned at less than 15 degrees. Our interpretation is that medial collagen can be strained even though highly aligned, revealing a mechanical property which contrasts that of type I collagen.     

Oxidative stress in patients with primary pulmonary hypertension

We studied the role of oxidative stress in the pathogenesis of primary pulmonary hypertension. In patients with primary pulmonary hypertension the content of malonic dialdehyde in the plasma was higher than in healthy volunteers (5.18±0.46 and 2.95±0.14 nmol/liter, respectively, p<0.01). However, glutathione peroxidase activity in the plasma decreased in these patients (0.50±0.17 vs. 1.19±0.14 U/ml in the control, p<0.05). By contrast, glutathione peroxidase activity in erythrocytes from patients surpassed the control (6.13±0.39 and 4.63±0.45 U/h hemoglobin, p<0.05). The increase in malonic dialdehyde content in the plasma and glutathione peroxidase activity in erythrocytes and the decrease in glutathione peroxidase activity in the plasma were most pronounced in patients with severe cardiac insufficiency and pulmonary hypertension. Our results indicate that antioxidant preparations improve the prognosis in patients with primary pulmonary hypertension.     

Pulmonary artery adventitial changes and venous involvement in primary pulmonary hypertension.

Primary pulmonary hypertension (PPH) is associated with a spectrum of structural changes in the pulmonary arteries: increased medial thickness, eccentric and concentric intimal thickening, obliteration and recanalization of arteries, and appearance of plexiform and dilatation lesions. The purpose of the present study was to further characterize these structural changes with particular emphasis on arterial adventitial thickness and alterations in the walls of the pulmonary veins. In addition, to determine whether the characteristic structural changes of PPH were size related, each was related to external diameter. With quantitative techniques, the pulmonary vasculature of 19 patients with PPH and 7 controls was examined by light microscopy. In all 19 patients, we found a striking increase in adventitial, as well as intimal and medial, thickness in arteries of all sizes when compared with controls (P < 0.05). In addition, we found intimal and adventitial thickening of pulmonary veins < 250 mu in diameter in approximately half of the PPH cases (P < 0.05). The frequency of arterial obliteration, concentric intimal thickening, and recanalization was 16, 18, and 11 of 19 cases, respectively. These changes were most prevalent in arteries less than 200 mu in diameter whereas eccentric intimal thickening and plexiform lesions occurred in 15 and 6 of the patients, respectively, and were most widespread in arteries > 200 mu. We conclude that remodeling of the pulmonary vasculature in PPH routinely includes thickening of the arterial adventitia and frequently also includes changes in the walls of the pulmonary veins. The finding that recanalization occurs predominantly in the smaller arteries whereas eccentric intimal thickening occurs mainly in the larger ones suggests that recanalization should not be considered a consequence of thromboemboli but may also occur at sites of more fibrotic intimal change.