Carrageenan-induced Granulomas Research Articles

Galectin-3 Gene Inactivation Reduces Atherosclerotic Lesions and Adventitial Inflammation in ApoE-Deficient Mice

This study has examined the role of galectin-3 (GaL3), a multicompartmented N-acetyllactosamine-binding chimeric lectin, on atherogenesis in the ApoE-deficient mouse model of atherosclerosis. Pathological changes consisting of atheromatous plaques, atherosclerotic microaneurysms extending into periaortic vascular channels, and adventitial and periaortic inflammatory infiltrates were assessed in an equal number (n = 36) of apolipoprotein (Apo)E-deficient mice and ApoE-GaL3 double-knockout mice. These mice were divided into three age groups, 21 to 23 weeks, 25 to 31 weeks, and 36 to 44 weeks of age. Results of this morphological analysis have shown an age-related increase in the incidence of aorta atheromatous plaques and periaortic vascular channels in ApoE-deficient mice. By contrast ApoE/GaL3 double-knockout mice did not show an increase in pathological changes with age. The 36- to 44-week group of ApoE(-/-)/GaL3(-/-) mice had a significantly lower number of atherosclerotic lesions (P < 0.004) and fewer atheromatous plaques (P < 0.008) when compared with ApoE(-/-)/GaL3+/+ mice of the same age. ApoE(-/-)/GaL3(-/-) mice had a lower number of perivascular inflammatory infiltrates and mast cells than those found in ApoE(-/-)/GaL3+/+ mice. The reduced number of perivascular mast cells may have resulted in a low level of interleukin-4 that contributed to the reduction in the morphological parameters of atherogenesis correlated with the lack of GaL3 expression. The effect of GaL3 deficiency on atherogenesis decrease could be related to its function as a multifunctional protein implicated in macrophage chemotaxis, angiogenesis, lipid loading, and inflammation.

Protective Effect of Policosanol on Endothelium and Intimal Thickness Induced by Forceps in Rabbits

Policosanol is a cholesterol-lowering drug isolated from sugar cane wax with concomitant antiplatelet effects that prevents lipofundin-induced atherosclerotic lesions in rabbits and rats, including foam cell formation, and also reduces foam cell formation in carrageenan-induced granulomas in rats, while it inhibits proliferation of smooth muscle cells induced in rabbit cuffed artery. This study was undertaken to determine whether policosanol prevents endothelium damage and increase in arterial wall thickness in rabbits with arterial walls damaged with a forceps. Artery forceps were placed over the central artery of the right ear of all rabbits, and each artery was injured eight times. Animals were randomly distributed into four groups: a positive control group treated with Tween 20/H2O vehicle, two groups treated with policosanol (5 and 25 mg/kg, respectively), and a group treated with aspirin (8 mg/kg). Treatments were given for 30 days. Damaged arteries were examined by light and electron (transmission and scanning) microscopy. To evaluate intimal thickening, areas of intima were measured, and a significant reduction in policosanol-treated animals was observed. The endothelial surface, studied with scanning electron microscopy, revealed several types of damage. In control group, the endothelial surface was severely damaged. De-endothelialized areas were reduced in policosanol-treated animals. Platelet adhesion to subendothelium was seen in all animals of the control group, whereas policosanol-treated groups exhibited significantly reduced platelet adhesion. Policosanol also reduced, dose-dependently, the platelet sequestration induced in the damaged vessel wall, partially preventing the reduction in platelet count. It is concluded that policosanol prevents endothelium injury and reduces significantly intimal thickness of rabbit arteries damaged with forceps.

Protective Effect of Policosanol on Atherosclerotic Plaque on Aortas in Monkeys

Policosanol is a cholesterol-lowering drug isolated from sugar cane wax with concomitant antiplatelet effects. Previous studies have shown that policosanol prevents lipofundin-induced atherosclerotic lesions in rabbits and rats, including foam cell formation, as well as the development of foam cells in carrageenan-induced granulomas in rats. Policosanol also inhibits smooth muscle cells proliferation induced on rabbit cuffed artery and on forceps-induced arterial wall damage. Furthermore, policosanol administered long term lowered serum cholesterol and prevented the development of atherosclerotic lesions in Macaca arctoides monkeys. The present study was undertaken to determine whether policosanol could change some characteristic features of atherosclerotic lesions, such as macrophage number and immunohistochemical localization of apoA-1 and apoB in aortas of M. arctoides monkeys. Fourteen adult male monkeys weighing 6-10 kg and receiving a low fat, protein-rich diet were randomly distributed in three groups: control group (six monkeys) and two other groups (four monkeys/group) treated with policosanol (2.5 and 25 mg/kg) for 54 weeks. Samples of arteries were examined by light microscopy. Monoclonal antibodies were used to evaluate the presence of macrophage, apoA-1 and apoB. Policosanol reduced the presence of macrophages and the occurrence of apoB, whereas increased apoA-1 localization in aortic atherosclerotic lesions compared with control monkeys. These results suggest the policosanol potential benefit on plaque composition and stability and could explain the protective effects of policosanol on atherosclerosis development.

Comparison of lipid accumulation and metabolism in carrageenan-induced granulomas to aorta and blood monocytes of normal and cholesterol-fed rabbits

New Zealand rabbits (six each) were either maintained on a standard chow diet (ND) or the chow diet supplemented with cholesterol/peanut oil (HD) for 2 weeks. After 2 weeks, each animal had 15 ml of a 1% carrageenan gel injeccted subcutaneously into the midabdominal area. Rabbits were maintained on the diets for an additional 4 weeks. At sacrifice, blood was collected both for serum and for monocyte isolation and granulomas and aorta were excised. Tissues were assayed for lipid composition and lipid metabolism. Electron and light microscopies were performed on granuloma tissue. Granulomas from ND animals did not stain with oil red O. Granulomas from HD animals had homogenous oil red O staining indicating lipid accumulation. Granulomas from both ND and HD animals consisted of macrophages. Macrophages from ND rabbits accumulated follicular carrageenan but not lipid, while HD macrophages had the appearance of foam cells. Granuloma lipid content and metabolism closely paralleled the aorta and blood monocytes. The HD tissue had increased acylCoA:cholesterol acetyltransferase (ACAT) activity and lipid composition changes reflective of the atherosclerotic process. ND granulomas had no elevation of lipid content or ACAT. The carrageenan-induced granulomas provide a useful model for studying the biochemical and morphologic changes characteristic of arteries undergoing atherogenic change.

Inhibition of tumor metastasis by carrageenan-induced granulomas.

At -1, 0, +1 weeks from tumor inoculation, carrageenan-impregnated cotton sponges were subcutaneously implanted. Tumor BN472, a malignant adenocarcinoma, was transplanted in syngeneic Brown Norway female rats, either subcutaneously or intravenously. Plasma eicosanoid values (prostaglandin-E2, thromboxane-B2 and 6-keto-prostaglandin-F1 alpha) were determined as well as the cellular immune response (natural killer activity, concanavalin-A and phytohemagglutinin stimulation of spleen lymphocytes). Primary tumor growth and the number of tumor foci in the lungs were measured as parameters of tumor growth and dissemination. No statistically significant differences were observed in primary tumor growth. However, the number of metastatic foci in the lungs of rats in which the tumor was implanted subcutaneously, as well as those in which the tumor was inoculated intravenously, was significantly reduced in those that had carrageenan implanted one week after tumor inoculation. In all other carrageenan-treated groups only slightly reduced numbers of metastatic foci were seen. In those rats with a decreased number of tumor metastatic foci in the lungs, no correlation could be shown with either altered plasma prostaglandin levels, or cellular immune response.

Mononuclear phagocytes from carrageenan-induce granulomas. Isolation, cultivation, and characterization.

Stable cultures of mononuclear phagocytes from carrageenan-induced granulomas in mice have been established after enzymatic dispersion of these lesions. The cells can be maintained for up to 3 wk without division in serum-free media. The mononuclear phagocytes were identified by several criteria. The cells are adherent, phagocytic, contain lysosomal acid hydrolases at high specific activities, secrete lysozyme, and bind soluble aggregates of IgG. The activities of 5'-nucleotidase and leucine aminopeptidase in the cultured granuloma cells showed that they resembled macrophages from thioglycollate-stimulated mice but not unstimulated macrophages in these respects. Supernates from the cultured granuloma cells contain factor(s) which induce the proliferation of thymocytes; the release of such factors by the cells is stimulated by lipopolysaccharide.

Acid hydrolase activity in the resorbing carrageenan granuloma.

SummaryThe specific activities of the acid hydrolases cathepsin, β-glucuronidase, β-galactosidase, β-glucosaminidase, and acid phosphatase have been shown to increase dramatically during the resorption of carrageenan-induced granulomas. Since these degradative enzymes are of the type normally found in lysosomes, this is strong presumptive evidence that these subcellular particles and their enzymes play a major role in granuloma resorption.

Effect of Estrogen onin Vivoandin VitroCollagen Biosynthesis and Maturation in Old and Young Female Guinea Pigs1

Study of collagen composition and in vivo and in vitro collagen biosynthesis and maturation in 10-day-old carrageenan-induced granulomas from female guinea pigs demonstrated that old animals have decreased amounts of neutral salt and acid soluble collagen, decreased in vitro biosynthesis and turnover, and lower ratios of proline to hydroxyproline (P: OH-P) in all collagen fractions. At any age the P:OH-P ratios appeared to reflect the rate of synthesis and turnover of collagen in the tissue studied, the more soluble, more immature, less polymerized forms having higher ratios. Estradiol administration to old animals reversed the values toward those found in young animals. In both young and old, estradiol decreased total collagen content of skin and granuloma while increasing bone mass, bone collagen, and calcium content. In the granuloma, estrogen reduced the amount and content of soluble collagen, almost eliminating the acid soluble; P:OH-P ratios in all fractions were increased and proline content of the...

Vitamin C deficiency and connective tissue. V. Fractionation of acid mucopolysaccharides in carrageenan-granulomas.

SummaryThe influence of ascorbic acid deficiency on the production of acid mucopolysaccharides was studied on carrageenan-induced granulomas 5,7,10 and 14 days old. By column chromatography, using ECTEOLA cellulose, three fractions of acid mucopolysaccharides were separated, viz., a hyaluronic acid-like and a chondroitin sulfate-like fraction and besides, a residual fraction. By means of infrared spectrophotometry of 14-day-old scorbutic granulomas, absorption bands were revealed representing group frequencies characteristic of acid mucopolysaccharides. The early biochemical alterations in scorbutic granulomas were characterized by an increase in the concentration of acid mucopolysacharides, which was caused by higher concentrations both of a hyaluronic acid-like fraction and a chondroitin sulfate-like fraction.

Vitamin C deficiency and connective tissue. IV. Determinations of mucopolysaccharides and collagen in carrageenan-granulomas.

SummaryThe influence of ascorbic acid deficiency on the production of collagen and acid mucopolysaccharides in carrageenan-induced granulomas is studied. Ascorbic acid deficiency results in the formation of a granuloma, which is poor in hydroxyproline, an animo acid specific of the collagen molecule. Furthermore, the acid mucopolysaccharides of the ground substance are changed, both qualitatively and quantitatively. The concentration of hexosamine and uronic acid increases during development of granulomas in ascorbic acid-deficient animals, and in granulomas 10 and 14 days old the concentration is increased significantly as compared with control granulomas. At the same time a decrease in the fucose concentration is observed, which is indicative of a decrease in the glycoproteinbound hexosamine. Hence, the increase in the hexosamine content is presumably caused exclusively by an increase in the content of acid mucopolysaccharides. The carbazole to orcinol ratio falls significantly during the development of normal control granulomas, presumably as a manifestation of a relative increase in the content of chondroitin sulfate B. During ascorbic acid deficiency, acid mucopolysaccharides are formed with a higher carbazole to orcinol ratio than that found in animals adequately supplied with ascorbic acid.

Vitamin C deficiency and connective tissue. VI. Uptake of 35S-sulfate in carrageenan-granulomas.

SummaryThe influence of ascorbic acid deficiency on the uptake of 35S-sulfate was studied in carrageenan-induced granulomas 5,7,10, and 14 days old. The uptake of 35S-sulfate was found to be higher in scorbutic granulomas 5,7, and 10 days old than in corresponding control granulomas, although the difference did not become significant till 10 days had passed. The radioactivity in 14-day-old scorbutic granulomas did not differ significantly from that found in controls. The increased synthesis of sulfomucopolysaccharides is discussed in conjunction with changes in the biochemistry of the acid mucopolysacharides.