Biomedical subjects

M Takeya

Publications and source records attributed to M Takeya.

At least 19 recordsLinked to original sources

PubMed2001

Glycoxidation and lipid peroxidation of low-density lipoprotein can synergistically enhance atherogenesis.

OBJECTIVE: The purpose of this study was to clarify the role of glycoxidation and lipid peroxidation of low-density lipoprotein (LDL) in atherogenesis. METHODS AND RESULTS: We examined the formation of N(epsilon)-(carboxymethyl) lysine (CML), a glycoxidation product, and malondialdehyde (MDA), a lipid peroxidation product, in vitro and their co-localization in human atherosclerotic lesions. Immunochemical analysis revealed that CML was formed in a time-dependent manner by human LDL incubated with copper ions and glucose, i.e. an in vitro model of glycoxidation of LDL. When LDL was exposed to copper ions alone, a small amount of CML was formed, however this was significantly less in oxidized LDL than glycoxidative LDL. In contrast, MDA formation was observed in both oxidation and glycoxidation of LDL, but not in glycation of LDL. Hexitol-lysine (HL), an Amadori product, was formed by both glycation and glycoxidation of LDL, but not by oxidation of LDL. Immunohistochemical analysis showed that CML and MDA accumulated mainly in macrophage/foam cells, while pyrraline, a non-oxidative product of glycation, and apolipoprotein B were localized in the extracellular matrix in atherosclerotic lesions. Atheromas were positive for CML and MDA, but negative for pyrraline. Macrophage/foam cells in atherosclerotic lesions exhibited co-localization of macrophage scavenger receptor-A with CML and MDA, but not with pyrraline. CONCLUSION: Our results suggest that glycoxidation and lipid peroxidation of LDL synergistically promote the development of atherosclerotic lesions through interaction with macrophage scavenger receptor-A.

Adult↗

PubMed2001

Expression of monocyte chemoattractant protein-1 in peritoneal endometriotic cells.

It is well known that the number of peritoneal macrophages is increased in patients with pelvic endometriosis. We measured the concentration of monocyte chemoattractant protein-1 (MCP-1) using an enzyme-linked immunosorbent assay (ELISA) in the peritoneal fluid of women with and without endometriosis. The expression of MCP-1 in pelvic endometriotic lesions obtained from the peritoneum was also examined using immunohistochemistry and nonradioactive in situ hybridization. The mean concentration of MCP-1 in the peritoneal fluid was significantly higher in the patients with endometriosis (P<0.05). The most significant elevation, compared with non-endometriosis patients, was found in stage I of the disease (P<0.05). However, no statistically significant difference was found among endometriosis stages I, II, III, and IV. Immunohistochemical staining revealed that MCP-1-positive cells were localized in the glandular epithelium of the endometriotic lesions and in the stromal macrophages distributed in those lesions, but normal peritoneal cells were negative. The in situ hybridization method demonstrated expression of MCP-1 mRNA on the endometriotic glandular epithelium and stromal macrophages. These findings suggest that MCP-1 may be involved in the histogenesis and early development of peritoneal endometriosis.

Ascitic Fluid↗

PubMed2001

Role of granulocyte/macrophage colony-stimulating factor in zymocel-induced hepatic granuloma formation.

To examine the role of granulocyte/macrophage colony-stimulating factor (GM-CSF) in inflammatory granuloma formation, we injected GM-CSF-deficient (GM-CSF(-/-)) mice and wild-type (GM-CSF(+/+)) mice intravenously with 2 mg of zymocel, and mice were killed at various intervals for examination. In GM-CSF(-/-) mice, we demonstrated a marked delay of zymocel-induced hepatic granuloma formation until 5 days after zymocel injection with a rapid reduction in numbers of granulomas at 10 days until their disappearance. In the early phase of granuloma formation, monocyte infiltration and differentiation of monocytes into macrophages were impaired in GM-CSF(-/-) mice compared with GM-CSF(+/+) mice. The percentages of [(3)H]thymidine-labeled macrophages at 2 days after zymocel injection were lower in the GM-CSF(-/-) mice than in the GM-CSF(+/+) mice. The DNA nick-end-labeling method demonstrated increased numbers of apoptotic cells in and around hepatic granulomas of GM-CSF(-/-) mice from 8 days after zymocel injection, and electron microscopy detected apoptotic bodies. Granuloma macrophage digestion of glucan particles and activation of macrophages were similar in the two types of mice. In situ hybridization demonstrated expression of GM-CSF mRNA in the endothelial cells, hepatocytes, and some granuloma cells in the GM-CSF(+/+) mice but not in the GM-CSF(-/-) mice. These results provide evidence that GM-CSF is important for the influx of monocytes into hepatic granulomas, for differentiation of monocytes into macrophages, and for proliferation and survival of macrophages within hepatic granulomas.

Animals↗

PubMed2001

Immunohistochemical distribution and quantitative biochemical detection of advanced glycation end products in fetal to adult rats and in rats with streptozotocin-induced diabetes.

SUMMARY: We used immunohistochemical methods and four monoclonal antibodies for specific molecular structures of advanced glycation end products (AGE)-6D12, KNH-30, 1F6, and 2A2-to examine localization of AGE in fetal, young, and adult rats, and rats with streptozotocin-induced diabetes. 6D12 recognized N(epsilon)-(carboxymethyl)lysine (CML); KNH-30, N(epsilon)-(carboxyethyl)lysine (CEL); and 1F6, fluorolink. The epitope of 2A2 is as yet unknown. Immunoreactivities for these monoclonal antibodies were found in various organs and tissues in postnatal and adult rats, and accumulation increased with aging. In the fetuses, AGE structures were detected at 10 fetal days, and their accumulation increased during ontogeny. Reversed-phase high-performance liquid chromatography revealed CML in fetuses at 13 fetal days and in lungs of 28-week-old rats. In various organs and tissues of fetal, young, and adult rats, CML, CEL, 2A2-positive AGE, and fluorolink accumulated, in that order, which suggests that the accumulation of CML, a nonfluorescent/noncross-linked AGE, occurs earlier than accumulation of fluorolink, a fluorescent/cross-linked AGE. In diabetic rats, hepatocytes, splenic macrophages, renal glomerular endothelial and mesangial cells, testicular Leydig cells, and erythrocytes showed excessive accumulation of AGE, leading to the pathologic changes characteristic of diabetes mellitus. For the induction of these changes, persistent hyperglycemia and hyperketonemia might be important for acceleration of intracellular AGE accumulation in diabetic rats. Thus, AGE accumulation in tissues and cells occurs not only during aging and in diabetes mellitus but also from an early stage of ontogeny.

Aging↗

PubMed2001

Familial amyloidotic polyneuropathy (ATTR Val30Met) with widespread cerebral amyloid angiopathy and lethal cerebral hemorrhage.

We report an autopsy case of familial amyloidotic polyneuropathy (FAP) with cerebral hemorrhage. A 38-year-old woman with a typical FAP pedigree started developing severe diarrhea and sensori-motor polyneuropathy at the age of 28 years; autonomic nervous system, heart and renal dysfunction manifested themselves in the following years. Genetic analysis revealed a single amino acid substitution at codon 30 of transthyretin (ATTR Val30Met). Ten years after her initial symptoms, the patient died of a sudden convulsive attack and respiratory failure. Autopsy revealed lethal cerebral hemorrhages and uremic lungs. Histochemical and immunohistochemical analyses revealed TTR-derived amyloid protein in every tissue examined, particularly in glomeruli and peripheral vessels. Severe meningo-cerebrovascular amyloidosis was also detected. Because uremia causes oxidative damage to the vascular system and amyloid formation is closely associated with oxidative stress, it is possible that uremic endothelial damage facilitated an unusual cerebral amyloid deposition. In typical FAP (ATTR Val30Met), cerebral amyloid angiopathy does not usually have clinical manifestations. However, cerebral amyloid angiopathy should be considered to explain FAP symptoms when some risk factors such as uremic vascular damage are accompanying features.

Adult↗

PubMed2001

Glycoxidation-modified macrophages and lipid peroxidation products are associated with the progression of human diabetic nephropathy.

The aim of this study is to investigate the role of glomerular macrophages activated by glycoxidation and lipid peroxidation products in the progression of glomerular lesions in diabetic nephropathy. Renal biopsy samples from 43 patients with diabetes (age, 54 +/- 14 years) and 10 control cases were immunohistochemically examined for the expression of carboxymethyllysine (CML), a representative glycoxidative product; oxidized phosphatidylcholine (Ox-PC), a representative lipid peroxidation product; leukocyte common antigen (LCA); CD68; and macrophage scavenger receptor (MSR) class A. The severity of the diffuse lesions in each glomerulus was histologically graded from 0 to IV. When grade II and III lesions had Kimmelstiel-Wilson (KW) nodules, they were placed in a new category called grade III with KW nodules. The number of cells positive for CML, Ox-PC, LCA, CD68, and MSR was compared in different grades. The number of macrophages per glomerulus increased with the glomerular lesion grade and was highest in grade III with KW nodules. Conversely, the number of lymphocytes did not parallel the grade of glomerular lesions. Almost 50% of macrophages contained CML, and more than 40% of those were observed in exudative lesions, tuft adhesions, and at the periphery of KW nodules. Ox-PC accumulated in 50% of CML-positive macrophages, which coexpress MSR. Macrophages positive for CML and Ox-PC increased with the grade. Glomerular macrophages may be activated by glycoxidative and lipid peroxidation products through MSR and may have a role in the development of human diabetic glomerulosclerosis.

Adolescent↗

PubMed2001

Immunohistochemical analysis of macrophages and myofibroblasts appearing in hepatic and renal fibrosis of dogs.

Some peptide growth factors produced by macrophages play a role in fibrosis following tissue injury, through the induction of myofibroblasts. In the present study, the appearance of macrophages and myofibroblast development in hepatic and renal fibrosis was determined by immunohistochemical analysis of tissue from 15 dogs. The hepatic and renal fibrosis was classified as grade I, II or III, depending on the extent (percentage) of fibrotic areas per unit area measured by morphometry with Azan-stained sections. The presence of alpha-smooth muscle actin-immunolabelled myofibroblasts was directly related to advancing grade of both hepatic and renal fibrosis. Lysozyme-immunolabelled macrophages also increased in number with increasing grade of hepatic and renal fibrosis. These findings indicate that myofibroblasts and lysozyme-positive macrophages may contribute to progressive fibrosis in canine liver and kidney disease. Interestingly, the number of macrophages recognized by AM-3K, a newly generated monoclonal antibody capable of labelling exuded macrophages and resident tissue macrophages in dogs, fell significantly in grades II and III of renal fibrosis. By contrast, in hepatic fibrosis there were no marked differences in the number of AM-3K-positive macrophages between grades. These findings suggest that there are functional differences between lysozyme- and AM-3K-positive macrophages.

Actins↗

PubMed2001

Rho-kinase mediates angiotensin II-induced monocyte chemoattractant protein-1 expression in rat vascular smooth muscle cells.

Recently, it was shown that Rho-kinase plays an important role in blood pressure regulation. However, it is not known whether Rho-kinase is involved in atherogenesis. Monocyte chemoattractant protein-1 (MCP-1) is an important chemokine that regulates monocyte recruitment and atherogenesis. Therefore, we examined the role of Rho and Rho-kinase in the angiotensin (Ang) II-induced expression of MCP-1. Ang II dose- and time-dependently enhanced the expression of MCP-1 mRNA and the protein production in vascular smooth muscle cells. CV11974, an Ang II type 1 receptor (AT(1)-R) specific antagonist inhibited the enhancement of MCP-1 expression by Ang II, suggesting that the effect of Ang II is mediated by the AT(1)-R. Botulinum C3 exotoxin, a specific inhibitor of Rho, suppressed Ang II-induced MCP-1 production. To examine the role of Rho-kinase in Ang II-induced MCP-1 expression, we used adenovirus-mediated overexpression of the dominant negative mutant of Rho-kinase (AdDNRhoK) or Y-27632, a specific inhibitor of Rho-kinase. Both AdDNRhoK and Y-27632 strongly inhibited Ang II-induced MCP-1 expression. Although inhibition of extracellular signal-regulated protein kinase (ERK) by PD 098,059 also inhibited Ang II-induced MCP-1 expression, Y-27632 did not affect Ang II-induced activation of ERK. These results indicate that Rho-kinase plays a critical role in Ang II-induced MCP-1 production independent of ERK. The Rho-Rho-kinase pathway may be a novel target for the inhibition of Ang II signaling and the treatment of atherosclerosis.

Amides↗

PubMed2001

In vivo complex formation of oxidized alpha(1)-antitrypsin and LDL.

An inactivated form of alpha(1)-antitrypsin (AT) and LDL coelutes in gel permeation chromatography. To characterize and to quantify the amount of this fraction of AT, a monoclonal antibody was established against chloramine T-oxidized AT and named OxAT-4. OxAT-4 recognized the oxidatively modified AT, including hexylaldehyde- or 4-hydroxy-2-nonenal-modified AT, but neither normal active AT nor trypsin/AT complex. Comigration of apoB and oxidized AT was demonstrated by Western blotting analysis of AT-LDL by means of anti-apoB monoclonal antibody and OxAT-4. A complex of oxidized AT and LDL (AT-LDL) was isolated from human plasma LDL by affinity column with an OxAT-4 antibody-coated carrier. AT-LDL was degraded 4 times more effectively by mouse peritoneal macrophages, but this was not mediated by scavenger receptor class A type I. Localization of AT-LDL was detected in human atherosclerotic lesions of the coronary artery, but distribution of it was not completely identical to that of macrophages. In situ hybridization revealed AT expression by macrophages, which were present in intimal layers of the coronary artery. From these findings, we concluded that AT is produced and oxidized by macrophages, then attached to LDL in the intimal layer of the arterial wall. Although AT-LDL that escapes into the blood stream can be cleared by hepatocytes, the remaining AT-LDL may be taken up by macrophages and contribute to the lipid accumulation in arterial wall cells as the early stage of atherogenesis.

Animals↗

PubMed2001

Glomerular endothelial cells are maintained by vascular endothelial growth factor in the adult kidney.

Vascular endothelial growth factor (VEGF) is known to maintain endothelial cells of immature vessels and is constitutively expressed in the kidney from the embryo to adult. We tested the hypothesis that VEGF activity is needed to maintain glomerular endothelial cells in the adult. Neutralizing antibody to VEGF165 was intraperitoneally administered to mice for 3 days to strongly suppress its intrinsic activity. On the fourth day, mice were sacrificed and tissues were examined by light and electron microscopies. Vascular casts of renal vessels were observed by a scanning electron microscopy. Distribution of the administered antibody and expressions of VEGF and Flk-1 were examined immunohistochemically. The suppression of endogenous VEGF activity caused swelling and vacuolation of endothelial cells and obstruction of capillaries in the glomerulus. Other tissues were not impaired significantly. The administered antibody was specifically localized to the glomerulus, and was found more predominantly in the juxta-medullary than in the cortical glomerulus. This pattern of antibody deposition was similar to that of Flk-1. VEGF expression in the glomerulus was compensatively elevated by the antibody treatment. These results show that demand for VEGF signaling in the glomerulus is much higher than in other tissues, probably to protect its endothelial cells against high tension for blood filtration. This demand may be fulfilled by enriched signaling through the Flk-1 in the glomerulus.

Animals↗

PubMed2001

Optical recording of the spatiotemporal propagation of neuronal excitation in the rat hippocampal CA2-CA1 pathway.

Changes in the membrane potential of neurons in the hippocampal CA2 and CA1 regions were recorded by optical recording techniques. After stimulation of the Schaffer collaterals at the hippocampal CA2 region, excitatory optical signals first occurred adjacent stimulus electrode and then flamed-up signals spread toward the hippocampal CA1 region. The optical signal was blocked by tetrodotoxin (TTX) (1 microM). Propagation of the optical signal was blocked in an artificial cerebrospinal fluid (ACSF) containing 0 mM Ca2+ and 6 mM Mg2+. 6,7-Dinitroquinoxaline-2,3 (1H,4H)-dione (DNQX) (20 microM) also blocked the optical signals that spread to the hippocampal CA1 region. The time course of the optical signal recorded at a unit area (49 pixels) on the propagation pathway was characterized by fast and slow components. TTX (1 microM) blocked both fast and slow components of the optical signal. The slow component of the optical signal was preferentially depressed by either removal of external Ca2+ or by bath-application of DNQX (20 microM). When bicuculline (15 microM) was applied to the bath-solution, the intensity and propagation area of the optical signal were increased. The results indicate that stimulation of the Schaffer collaterals in the hippocampal CA2 region produces the propagation of the optical signal to the hippocampal CA1 region, and that the optical signal involves the action potential and excitatory and inhibitory postsynaptic potentials.

Action Potentials↗

PubMed2001

Intrinsic factors involved in the depression of neuronal activity induced by temperature increase in rat hippocampal neurons.

The intrinsic factors involved in the temperature-dependent impairment of neuronal activity in hippocampal CA2-CA1 regions were investigated using optical recording techniques. At 32 degrees C, stimulation of the Schaffer collaterals in the hippocampal CA2 region evoked depolarizing optical responses that spread toward the CA1 region. The optical response was characterized by fast and slow components that were mainly related to the presynaptic action potentials and excitatory postsynaptic response, respectively. The increase of the temperature to 38 degrees C was associated with a reversible depression of the neuronal activity in the hippocampal brain preparations. The depression of neuronal activity was irreversible when the temperature was increased to 40 degrees C. In the presence of 22 mM glucose, the depression of the neuronal activity at 38 degrees C was significantly attenuated. Pyruvate (22 mM), but not lactate (22 mM), also improved the depression of neuronal activity induced by the temperature increase. Adenosine (200 microM) strongly depressed the excitatory postsynaptic response, but not presynaptic action potentials. 8-Cyclopentyl-1,3-dimethylxanthine (8-CPT) (10 microM), an adenosine A1 receptor blocker, attenuated the adenosine-induced depression of the excitatory postsynaptic response. 8-CPT (10 microM) prevented the impairment of the excitatory postsynaptic response induced by the increase of the temperature to 38 degrees C. In contrast, the depression of presynaptic action potential at 38 degrees C was not prevented by 8-CPT (10 microM). N omega-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase (NOS) inhibitor, and methylcobalamin (10 microM), a vitamin B12 analogue, attenuated the inhibition of pre- and postsynaptic activities induced by the increase of the temperature to 38 degrees C. Glibenclamide, a KATP channel blocker, did not protect neuronal activity from the effects of the increase of the temperature. These results suggest that the heat-induced depression of neuronal activity is mediated by multiple factors, such as impairment of energy metabolism and increase in extracellular adenosine and nitric oxide (NO) levels in hippocampal neurons.

Adenosine↗

PubMed2000

Role of monocyte chemoattractant protein-1 in cardiovascular remodeling induced by chronic blockade of nitric oxide synthesis.

BACKGROUND: Chronic inhibition of endothelial nitric oxide (NO) synthesis by the administration of N:(omega)-nitro-L-arginine methyl ester (L-NAME) to rats induces early vascular inflammatory changes (monocyte infiltration into coronary vessels and monocyte chemoattractant protein-1 [MCP-1] expression) as well as subsequent arteriosclerosis (medial thickening and perivascular fibrosis) and cardiac fibrosis. However, the role of MCP-1 in this process is not known. METHODS AND RESULTS: We investigated the effect of a specific monoclonal anti-MCP-1 neutralizing antibody in rats treated with L-NAME to determine the role of monocytes in the regulation of cardiovascular remodeling. We found increased expression of MCP-1 mRNA in vascular endothelial cells and monocytes in inflammatory lesions. Cotreatment with an anti-MCP-1 antibody, but not with control IgG, prevented the L-NAME-induced early inflammation and reduced late coronary vascular medial thickening. In contrast, the anti-MCP-1 antibody did not decrease the development of perivascular fibrosis, the expression of transforming growth factor (TGF)-beta(1) mRNA, or systolic pressure overload induced by L-NAME administration. CONCLUSIONS: These results suggest that MCP-1 is necessary for the development of medial thickening as well as monocyte recruitment. In contrast, the pathogenesis of fibrosis may involve other factors, such as TGF-beta(1).

Animals↗

PubMed2000

Important role of local angiotensin II activity mediated via type 1 receptor in the pathogenesis of cardiovascular inflammatory changes induced by chronic blockade of nitric oxide synthesis in rats.

BACKGROUND: The chronic inhibition of NO synthesis by N(omega)-nitro-L-arginine methyl ester (L-NAME) upregulates the cardiovascular tissue angiotensin II (Ang II)-generating system and induces cardiovascular inflammatory changes in rats. METHODS AND RESULTS: We used a rat model to investigate the role of local Ang II activity in the pathogenesis of such inflammatory changes. Marked increases in monocyte infiltration into coronary vessels and myocardial interstitial areas, monocyte chemoattractant protein-1 (MCP-1) expression, and nuclear factor-kappaB (NF-kappaB, an important redox-sensitive transcriptional factor that induces MCP-1) activity were observed on day 3 of L-NAME administration. Along with these changes, vascular superoxide anion production was also increased. Treatment with an Ang II type 1 receptor antagonist or with a thiol-containing antioxidant, N-acetylcysteine, prevented all of these changes. CONCLUSIONS: Increased Ang II activity mediated via the type 1 receptor may thus be important in the pathogenesis of early cardiovascular inflammatory changes in this model. Endothelium-derived NO may decrease MCP-1 production and oxidative stress-sensitive signals by suppressing localized activity of Ang II.

Angiotensin II↗

PubMed2000

Suppressed urinary excretion of aquaporin-2 in an infant with primary polydipsia.

We observed severe overhydration in an 18-month-old Japanese girl with primary polydipsia. The secretion of antidiuretic hormone (ADH) was decreased, and urinary excretion of aquaporin-2, a vasopressin-sensitive water channel protein, was suppressed under basal conditions, but the response of aquaporin-2 to ADH was essentially preserved. These findings suggest that the water channel itself was intact and that overhydration resulting from polydipsia was responsible for the decreased ADH secretion and suppression of the water channel protein.

Aquaporin 2↗

PubMed2000

Localization of human acyl-coenzyme A: cholesterol acyltransferase-1 (ACAT-1) in macrophages and in various tissues.

To investigate the distribution of acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT-1) in various human tissues, we examined tissues of autopsy cases immunohistochemically. ACAT-1 was demonstrated in macrophages, antigen-presenting cells, steroid hormone-producing cells, neurons, cardiomyocytes, smooth muscle cells, mesothelial cells, epithelial cells of the urinary tracts, thyroid follicles, renal tubules, pituitary, prostatic, and bronchial glands, alveolar and intestinal epithelial cells, pancreatic acinar cells, and hepatocytes. These findings showed that ACAT-1 is present in a variety of human tissues examined. The immunoreactivities are particularly prominent in the macrophages, steroid hormone-producing cells, followed by hepatocytes, and intestinal epithelia. In cultured human macrophages, immunoelectron microscopy revealed that ACAT-1 was located mainly in the tubular rough endoplasmic reticulum; immunoblot analysis showed that the ACAT-1 protein content did not change with or without cholesterol loading; however, on cholesterol loading, about 30 to 40% of the total immunoreactivity appeared in small-sized vesicles. These vesicles were also enriched in 78-kd glucose-regulated protein (GRP 78), a specific marker for the endoplasmic reticulum. Immunofluorescent microscopy demonstrated extensive colocalization of ACAT-1 and GRP 78 signals in both the tubular and vesicular endoplasmic reticulum before and after cholesterol loading. These results raise the possibility that foam cell formation may activate an endoplasmic reticulum vesiculation process, producing vesicles enriched in the ACAT-1 protein.

Adult↗

PubMed2000

Retrovirus-mediated, stable scavenger-receptor gene transfer leads to functional endocytotic receptor expression, foam cell formation, and increased susceptibility to apoptosis in rabbit aortic smooth muscle cells.

The type II, class A macrophage scavenger receptor (SR-A) plays an important role in the pathogenesis of atherosclerosis and foam cell formation. However, its role in nonmacrophage cell lines remains unknown. To test the hypothesis that SR-A activity leads to proatherogenic changes in nonmacrophage cell lines, we generated Moloney murine leukemia virus- and vesicular stomatitis virus G protein-pseudotyped retroviruses containing SR-A type II cDNA, which were used for stable transfection of SR-A activity into mouse fibroblasts and rabbit aortic smooth muscle cells (SMCs). beta-Galactosidase-transfected cell lines were used as controls. Transfected cell lines expressed functional SR-A mRNA and protein. Expression of SR-A activity was stable for at least 9 months. By electron microscopy, transfected receptors were located in coated pits and in intracellular structures resembling endocytotic vesicles. Expression of SR-A on the cell surface was verified by flow cytometry and by uptake and degradation of (125)I-labeled acetylated low density lipoprotein (LDL). Increases of 5- to 25-fold and of 6- to 8-fold in the rate of acetylated LDL degradation were observed in transfected fibroblasts and SMCs, respectively, compared with beta-galactosidase-transfected control cell lines. Incubation of the transfected SMCs and fibroblasts with acetylated or oxidized LDL led to foam cell formation. Incubation with oxidized LDL also led to increased apoptosis and cell death. An altered morphology with increased cell size and granularity was observed in the most active SR-A SMC clones. It is concluded that stable overexpression of SR-A leads to foam cell formation and other proatherogenic changes in nonmacrophage cell lines. Stable SMC and fibroblast cell lines can be used as models for foam cell formation. The results also suggest that increased SR activity may play an important role in SMC-related pathology in atherosclerotic arteries.

Animals↗

PubMed2000

Distribution of cells immunopositive for AM-3K, a novel monoclonal antibody recognizing human macrophages, in normal and diseased tissues of dogs, cats, horses, cattle, pigs, and rabbits.

The monoclonal antibody AM-3K, which was developed using human pulmonary macrophages as the immunogen, immunocytochemically labels most human macrophages except for blood monocytes and dendritic cell populations. AM-3K also shows cross-reactivity in some animal species. To evaluate the usefulness of AM-3K, the present study investigated the detailed distribution of AM-3K-immunopositive macrophages in normal and diseased tissues of dogs, cats, horses, cattle, pigs, and rabbits. Zamboni's solution-fixed, paraffin-embedded sections were the most available for the immunocytochemistry with AM-3K. In all animal species examined, AM-3K labeled most macrophages in splenic red pulp, lymph node sinuses and thymus, and tissue macrophages in the interstitium of various organs and sites such as the kidneys, lungs, heart, pancreas, intestines, and skin. Alveolar macrophages and perivascular microglial cells were also immunoreactive for AM-3K. Interestingly, Kupffer cells of dogs, cats, and horses were labeled for AM-3K, but those of cattle, pigs, and rabbits were not. Furthermore, in tumor tissues and inflammatory lesions such as liver fibrosis and encephalomalacia that were obtained from dogs, infiltrating macrophages were stained with AM-3K, but not all infiltrating macrophages reacted to AM-3K. In addition, only 30-50% of pulmonary and peritoneal macrophages obtained from cats and dogs were reactive for AM-3K. AM-3K did not react with blood monocytes, dendritic cell populations, and osteoclasts. These observations indicate that AM-3K specifically labels most exudate and tissue macrophages in the animal species examined. However, the expression of antigens recognized by AM-3K on macrophages may be dependent on differential maturation stages or different functions evoked by some conditions. AM-3K immunoreaction products were seen on the cytoplasmic membrane of macrophages by immunoelectron microscopy. AM-3K would be useful for detection of macrophage populations in the animal species examined here.

Animals↗