A single injection of 10(5) U/kg of recombinant rat IFN-gamma increases the amount of tissue dendritic cells up to sixfold, and concomitantly induces the (capillary) endothelial cells to express class II MHC antigens. Both responses peak on the third day after IFN-gamma injection, and the antigen expression returns to basic levels on day 7. Simultaneous administration of 1 mg/kg/d of methylprednisolone entirely abolishes both responses. These observations demonstrate, for the first time, that IFN-gamma and steroids have antagonistic effects on class II MHC antigen presentation in tissue, and suggest that one immunosuppressive mechanism of glucocorticosteroids in organ transplantation is downregulation of graft antigenicity.

Animals↗

PubMed1986

Estrone sulfate: a potential source of estradiol in human breast cancer tissues.

Local formation of estradiol in human breast tumors could provide a more important source of estrogen than is delivered from plasma. Prior studies have suggested that estrone is primarily synthesized from estrone sulfate. The enzyme 17 beta-hydroxysteroid dehydrogenase (HSD) would be required to convert estrone to estradiol. This study characterized HSD in 1000 X g supernatants from human breast tumors. Estradiol synthesis was linearly related to tissue concentration or time over the range studied. Cofactor requirements varied with estrone concentration. High and low affinity sites were found in 50% of tissues studied, while the remainder contained only low affinity sites. Screen assays showed measurable activity in all 42 samples tested. This activity ranged from 0.73- greater than 100 nmol estrone synthesized/g protein/hr, with a median activity of 5.9 nmol/g/hr. We evaluated the biological relevance of the sulfatase-HSD pathway by testing the ability of estrone sulfate to stimulate colony formation in soft agar cultures of nitrosomethylurea-induced rat mammary tumors. The maximally effective concentration ranged from 10(-7) to 10(-4)M. Significant stimulation of colony formation was observed in 7 of 8 experiments. The estrone sulfate stimulation pattern was similar to that previously observed with estradiol. Of the 3H-estrone sulfate added to the dishes, 20-98% was recovered as estrone and 0.2-6% as estradiol. These studies suggest that the requisite enzymes are present in human breast tumors for conversion of estrone sulfate to estradiol, and that this pathway may be biologically significant.

17-Hydroxysteroid Dehydrogenases↗

PubMed1986

Enzymatic control of estrogen production in human breast cancer: relative significance of aromatase versus sulfatase pathways.

One-third of the cases of breast cancer in postmenopausal women are hormone-dependent and the lesions regress upon treatment with antiestrogens or inhibition of estrogen biosynthesis. In these patients, estrogens are synthesized in extraglandular tissues from adrenal precursors and re-enter plasma to produce estrone levels of 52 +/- 6.5 pg/ml (mean +/- SEM) and estradiol concentrations of 13.1 +/- 0.7 pg/ml. However, the fact that the levels of estrogen in breast tumor tissue are an order of magnitude higher than plasma levels suggested the possibility of in situ estrogen production. To address this possibility, we measured several enzymes involved in estradiol biosynthesis in human tumors. Forty-eight of 61 tumors contained aromatase (estrogen synthetase) activity ranging from 5-80 pg/gm protein per hour. By comparison, the levels of estrone sulfatase were 10(6) higher, ranging from 0.8-125 micrograms/gm protein per hour. Because the sulfatase enzyme was of lower affinity (i.e., Km = 27 microM) than that of aromatase (i.e., 0.027 microM), the amount of estrogen formed under conditions of similar substrate concentrations was compared and found to be 10-fold higher via the sulfatase enzyme. In 41 additional tumors, the 17 beta-hydroxysteroid dehydrogenase enzyme, catalyzing the conversion of estrone to estradiol, was uniformly present. To test the biologic relevance of the estrone sulfate to estrone to estradiol pathway, estrogen-dependent nitrosomethylurea rat mammary tumors were grown in soft agar in the presence of estrone sulfate. Concentrations of estrone sulfate of 10(-6) microM significantly (p less than 0.01) stimulated colony formation in this system in which 75.5-98.6% of estrone sulfate was converted to estrone and 0.2 to 6% to estradiol. These data support the hypothesis that mammary carcinomas can synthesize estradiol in situ from circulating estrogen precursor and that local conversion is biologically important. On the basis of comparative data, the estrone sulfate to estrone to estradiol pathway is quantitatively more important than that involving androstenedione to estrone to estradiol.

17-Hydroxysteroid Dehydrogenases↗

PubMed1985

Localization and turnover rate of rat renal 'dendritic' cells.

The turnover rate of rat renal dendritic cells was analysed by irradiation and bone marrow transplantation and by visualizing the dendritic cells in frozen sections of renal tissue via double indirect immunofluorescence and peroxidase assays. Interstitial dendritic cells disappear from rat renal tissue shortly after irradiation; after 7 days they can be seen again. However, since the renal proximal tubular cells also simultaneously lose and regain their class II contents, we assume that irradiation has resulted in the disappearance of the Ia antigen, not the dendritic cells proper. After allogeneic bone marrow transplantation, bone marrow-derived dendritic cells appear in renal tissue between days 7 and 10, indicating a relatively fast turnover rate of these cells in vivo.

Animals↗

PubMed1985

Turnover of dendritic cells in rat heart.

Taking advantage of the high class II (I-region-associated) antigen content of the tissue dendritic cells and monoclonal antibodies directed to the backbone determinants of the bone marrow donor strain, we have investigated the location and analysed the turnover rate of tissue dendritic cells in rat heart. Low numbers of class II-expressing, factor VIII-negative, non-phagocytic cells with dendritic appearance were observed between the heart muscle fibres. After irradiation with 960 rad, these cells were no longer visible but they reappeared (in lower numbers) on day 20, indicating that they are relatively radioresistant but the antigen expression is radiosensitive. Transplantation of allogeneic bone marrow demonstrated that similar cells appeared from the transplanted bone marrow on day 10, and that these cells populated the heart at a maximum of 20-25 days after transplantation. This indicates a relatively rapid turnover rate, comparable with the turnover rate of dendritic cells in rat kidney and mouse lymphoid tissue.

Animals↗

PubMed1985

Ultrastructure of human umbilical artery and vein. Characterization and quantification of lipid laden cells.

Intimal thickening and lipid accumulation, which occur in atherosclerosis, were observed in fifteen human umbilical vessels. Quantification of lipid laden cells was done electron-microscopically. Within 1 month after birth, lipid laden cells originating from macrophages were observed in the umbilical artery, while those originating from smooth muscle cells were seen in the umbilical artery and vein. Lipid droplet formation appeared to be independent and different in macrophages and smooth muscle cells; the latter cells were stimulated to produce lipid droplets by hypoxia and the former cells by blood components.

Age Factors↗

PubMed1985

Bone marrow transplantation in the rat. III. Structure of the liver inflammatory lesion in acute graft-versus-host disease.

The liver is a major parenchymal target organ of acute graft-versus-host disease (aGVHD) after bone marrow transplantation in the rat. The authors have analyzed the nature of cellular infiltrates in the liver using monoclonal antibodies against white cell subsets and investigated the anatomic distribution of the inflammatory cell subsets inside the liver parenchyma. Several types of white cells are present in a normal control liver: In the portal area the T-helper (Th) cells predominate, (surface) immunoglobulin-expressing B cells are present in ample numbers, and most of the phagocytes are Ia-positive. In the central vein area the T-suppressor/killer cells (Tsk) dominate, no B cells are present, and most of the phagocytes are Ia-negative. During aGVHD the number of T cells increases rapidly in the portal area; and after an initial strong increase, the Th/Tsk ratio decreases but remains still above 1. In the central vein area there is also an increase in the number of T cells, compared with that in the syngeneic recipient, but the Th/Tsk ratio rapidly decreases and remains uniformly below 1. During aGVHD the B cells entirely disappear from the portal area, whereas a small but distinct number of mature plasma cells with intracellular immunoglobulin appear in the central vein area. Following irradiation the Ia-positive phagocytic cells entirely disappear from the portal area and decrease distinctly in number in the central vein area. During aGVHD the number of Ia-positive phagocytes increases again in both locations. In the central vein area the positive phagocytes are seen over the background level, and, concomitantly, the Ia-negative phagocytes disappear.

Animals↗

PubMed1984

Ultrastructure of newly formed vessels in thrombi. Endothelium formation in human umbilical artery.

Thrombi with newly formed vessels in thirteen human umbilical arteries were studied. Red blood cells formed masses which were covered by fibrin within twelve hours after birth. By the second day, the intima including endothelial cells was denuded. In the junctional area between the thrombi and the original intima on the sixth day, red blood cells were surrounded by endothelial-like cells, which displayed junctional complexes and did not show any connection with intact endothelial cells. These cells also exhibited filaments with fusiform densities, suggesting a probable origin from vascular smooth muscle cells. Examination of older specimens indicated that these were precursor structures of functional capillaries found in mature thrombi.

Age Factors↗

PubMed1984

Ultrastructure of aging human umbilical artery and vein.

Qualitative and quantitative changes in the human umbilical artery and vein were observed in 15 human specimens at different stages of development. Features such as intimal thickening and cellular lipid accumulation were found in umbilical vasculature. Cellular origin and quantification of lipid-containing cells were determined by electron microscopy. Within 1 month after birth, lipid-containing cells originating from macrophages were observed in the umbilical artery, while those originating from smooth muscle cells were observed in both the umbilical artery and vein. Lipid droplet formation appeared to be independent and different in macrophages and smooth muscle cells; the former cells were stimulated to produce lipid droplets primarily by plasma insudation and the latter cells primarily by hypoxia. These findings indicate that ultrastructural changes observed in closing umbilical vasculature may closely parallel and serve as a model for atherosclerotic changes which occur in mature vessels.

Aging↗

PubMed1981

Vasculotoxic effects of dietary testosterone, estradiol, and cholesterol on chick artery.

Five-day-old female chicks were fed diets containing testosterone, estradiol, and cholesterol for 2 months. Cholesterol supplementation of 1 per cent. resulted in production of lipid vacuoles in the interlamellar connective tissue cells and to a lesser extent in the smooth muscle cells in the aorta; cholesterol had no effect on the coronary artery. The vasculo-toxic nature of estrogen was indicated when 0.05 per cent. dietary estradiol produced more accumulations of lipid vacuoles in smooth muscle cells, more extracellular lipid, and more smooth muscle cell death than cholesterol feeding. A dietary combination of cholesterol plus estradiol produced severe lipid deposition throughout the entire thickness of ascending aorta, and degenerative atherosclerotic changes in the coronary artery. Combined testosterone and estradiol supplementation resulted in peculiar dwarf chickens which exhibited increased vascular smooth muscle cell mitosis and degeneration.

Animals↗

PubMed1981

Angiotoxic effects of dietary 7-ketocholesterol in chick aorta.

Although dietary 1-ketocholesterol treatment had little effect on plasma and liver lipid metabolism, aortas from chickens treated with 7-ketocholesterol contained numerous dead and dying smooth muscle cells. Chicks receiving dietary cholesterol, in amounts equal to or greater than the amount of 7-ketocholesterol, did not demonstrate significant smooth muscle cell degeneration. After eight weeks, a combined diet of 1% cholesterol plus 10-20 mg/day 1-ketocholesterol produced no larger amounts of aortic lipid deposition, and no greater increases in smooth muscle cell degeneration than a comparable group receiving 7-ketocholesterol alone. The abdominal aorta was always more severely damaged than the ascending arch or thoracic aorta in chicks fed 7-ketocholesterol. The results demonstrate a potent angiotoxic effect of 7-ketocholesterol.

Animals↗

PubMed1980

Coronary arterial lesions in sexually mature non-layers, layers, and roosters.

The effects of hereditary hyperlipidemia on coronary artery atherosclerosis were studied in 77 White Leghorn (DeKalb strain) chickens ranging from 4 to 13 months in age. After pubescence, the plasma levels of triglyceride and cholesterol in non-laying hens ranged 2- to 3-fold and 2- to 7-fold higher compared to layers. Serial sectioning revealed that most lesions were found in the proximal portions of both the left and right coronary arteries. Ultrastructurally, lesions in the roosters contained no foam cells, whereas some foam cells and small amounts of stainable lipid were observed in the thickened intima of layers. Half of the non-layers had stenotic lesions characterized by many foam cells, necrotic foci, and heavy stromal lipid deposits. Continuous permeation of excess plasma lipids into the arterial wall appeared to be an important factor in the development of coronary lesions.

Animals↗

PubMed1980

Ultrastructure of developing human ductus arteriosus.

Histological and ultrastructural studies were made of 25 specimens of human ductus arteriosus obtained from abortion of autopsy, and ranging in age from 15 weeks of gestation to 7 years. Samples of ductus with normal muscular type structure exhibited active intimal thickening as early as 15 weeks' gestational age when the internal elastic lamina was found to be focally discontinuous. At the same time, intimal smooth muscle cells were closely arranged, and often intimately connected to cells of the tunica media. Ultrastructurally, both smooth muscle cells and endothelial cells at 15 weeks' gestational age contained abundant glycogen deposits. From 18-32 weeks' gestational age, glycogen deposits gradually disappeared, collagen fibres began to appear in the extracellular space and the first signs of smooth collagen fibres began to appear in the extracellular space and the first signs of smooth muscle cell degeneration became apparent. After birth, intimal thickening and degeneration of smooth muscle cells was much more pronounced. The ultrastructure of intimal smooth muscle cells indicated that intimal thickening was caused by smooth muscle cell migration as opposed to rapid proliferation; and both intracellular and extracellular membrane-bound lipid-filled vacuoles were commonly seen in the more advanced stages of degeneration. Of the ductus specimens examined, three were rich in elastic fibres. Two of these three specimens were from a group of 10 abortion cases, and the third was from a 2 weeks old full term infant who had been exposed to maternal rubella. The 2 weeks old infant had a widely patent ductus arteriosus; whether the two fetal specimens with ductus elastosis would have eventually developed into clinical patent ductus arteriosus was not clear.

Ductus Arteriosus↗

PubMedDate not supplied

17 Beta-hydroxysteroid dehydrogenase in human breast cancer: analysis of kinetic and clinical parameters.

In this study, we assessed the rate of estradiol degradation via the 17 beta-hydroxysteroid dehydrogenase (HSD) enzyme in breast tumors from postmenopausal women. We initially studied the effects of time, level of enzyme activity, amount of tissue assayed, and substrate concentration on the linearity of conversion of estradiol to estrone in breast tumor homogenates. The reaction was demonstrated to be linear when less than 15% conversion of estradiol to estrone occurred over 30 min with homogenates produced from 2.5 mg of tissue. Detailed kinetic experiments demonstrated the presence of two classes of enzyme activity, one with high affinity and the other with low affinity. In 83% of the tumors examined, the high affinity form was present and had a median Km of 0.62 microM and Vmax of 82 nmol/g protein/h. In 29 tumors, HSD activity could be precisely quantified and correlated with clinical parameters. No statistically significant correlation of enzyme activity with estrogen receptor (r2 = 0.06) or progesterone receptor (r2 = 0.006) or with patient age could be detected (r2 = 0.001). In 12 additional tumors, activity exceeded 15% conversion of estradiol to estrone at 30 min and precise quantitation was not possible. The average content of progesterone receptor was similar for these 12 tumors as for the 19 with lower HSD activity. However, estrogen receptor content and patient age were lower in the group with high HSD activity. The finding of a high affinity form of HSD in this study provides support for the biological importance of this enzyme in breast cancer tissues.

17-Hydroxysteroid Dehydrogenases↗