Matrix metalloproteinase 2 improves the transplanted adipocyte survival in mice.

BACKGROUND: Fat tissue is a common material for autologous transplantation in plastic and reconstructive surgery. Basic fibroblast growth factor (bFGF) ameliorates the fat graft survival. A transplantation model has shown the gene expression of matrix metalloproteinases (MMPs) to increase in adipocytes. The aim of this study is to investigate the role of MMPs in the amelioration of survival by bFGF. MATERIALS AND METHODS: 3T3-L1 adipocytes were incubated with or without 10 microg mL(-1) bFGF for 8 h in the presence or absence of the MMP inhibitor GM6001, vascular endothelial growth factor (VEGF), MMP-2 or anti-bFGF antibody to study the effect of bFGF on MMP-2 mRNA expression, MMP-2 activity, fat accumulation or 2-deoxyglucose uptake. Collagen sheets containing l x l0(7) adipocytes with or without bFGF in the presence or absence of GM6001 were subcutaneously transplanted into mice, and the appearance, histology, mRNA expression and fat accumulation of the grafts were analysed 4 weeks after transplantation. RESULTS: The MMP-2 expression was drastically induced by bFGF among MMPs in 3T3-L1 adipocytes. MMP-2 accelerated fat accumulation, peroxisome proliferator-activated receptor gamma (PPAR gamma) mRNA expression, and glucose uptake to an extent similar to those induced by bFGF, respectively. The bFGF-induced increases were inhibited by the blocking of MMP-2. The transplantation of adipocytes into mice showed that bFGF ameliorates the appearance and fat accumulation, as well as mRNA expression in grafts. These effects were almost or partly inhibited by a MMP blockade. CONCLUSIONS: MMP-2 may be involved in the mechanism by which bFGF ameliorates the survival of fat grafts.

Macrophages regulate tumor necrosis factor-alpha expression in adipocytes through the secretion of matrix metalloproteinase-3.

OBJECTIVE: Adipocytes accumulated in the visceral area change their function to induce tumor necrosis factor-alpha (TNF-alpha) secretion with concomitant matrix metalloproteinase (MMP)-3 induction in mice. This study was performed to clarify the role of macrophages (Mphi)-secreted MMP on the functional changes in adipocytes using a culture system. DESIGN: Cultures of 3T3-L1 adipocytes with THP-1 Mphi or the Mphi-conditioned medium were used to investigate the role of Mphi-MMP on the TNF-alpha gene in 3T3-L1 adipocytes by the addition of MMP inhibitors. For animal experiments, male C57BL/6J mice were rendered insulin resistant by feeding a high-fat diet, and the expression of an Mphi marker F4/80, and MMP-3 genes in mesenteric and subcutaneous fat tissue specimens were examined. RESULTS: Mphi-conditioned media (Mphi-CM) increased the levels of TNF-alpha mRNA expression in 3T3-L1 adipocytes, and these adipocyte responses were abolished by treatment with GM6001, a broad-spectrum MMP inhibitor, or NNGH (N-isobutyl-N-(4-methoxyphenylsulfonyl)-glycylhydroxamic acid), an MMP-3 inhibitor. The activated form of MMP-3 enhanced glycerol release as well as TNF-alpha protein secretion from 3T3-L1 adipocytes. The incubation of adipocytes with MMP-3 inhibited insulin-induced glucose uptake in adipocytes. Furthermore, a high-fat intake increased the expression of MMP-3, decreased the insulin-induced glucose uptake of adipocytes and induced expression of F4/80 in mesenteric fat tissue of C57BL/6 mice. CONCLUSION: Mphi may cause a pathological link with surrounding adipocytes through the secretion of MMP-3 followed by TNF-alpha expression in adipocytes in visceral fat tissue.

Catalytically inactive lipoprotein lipase overexpression increases insulin sensitivity in mice.

Abnormalities in lipoprotein lipase (LPL) function contribute to the development of hypertriglyceridemia, one of the characteristic disorders observed in the metabolic syndrome. In addition to the hydrolyzing activity of triglycerides, LPL modulates various cellular functions via its binding ability to the cell surface. Here we show the effects of catalytically inactive LPL overexpression on high-fat diet (HFD)-induced decreased systemic insulin sensitivity in mice. The binding capacity of catalytically inactive G188E-LPL to C2C12 skeletal muscle cells was not significantly different from that of wild type LPL. Insulin-stimulated IRS-1 phosphorylation and glucose uptake were increased by addition of wild type or mutant LPL in C2C12 cells. After 10 weeks' of HFD feeding, mice had significantly higher blood glucose levels than chow-fed mice in insulin tolerance tests. The blood glucose levels after insulin injection was significantly decreased in mutated LPL-overexpressing mice (G188E mice), as well as in wild type LPL-overexpressing mice (WT mice). Overexpression of catalytically inactive LPL, as well as wild type LPL, improved impaired insulin sensitivity in mice. These results show that decreased expression of LPL possibly causes the insulin resistance, in addition to hypertriglyceridemia, in metabolic syndrome.

Overexpression of lipoprotein lipase in transgenic rabbits inhibits diet-induced hypercholesterolemia and atherosclerosis.

Lipoprotein lipase (LPL) is a key enzyme in the hydrolysis of TG-rich lipoproteins. To elucidate the physiological roles of LPL in lipid and lipoprotein metabolism, we generated transgenic rabbits expressing human LPL. In postheparinized plasma of transgenic rabbits, the human LPL protein levels were about 650 ng/ml, and LPL enzymatic activity was found at levels up to 4-fold greater than that in nontransgenic littermates. Increased LPL activity in transgenic rabbits was associated with as much as an 80% decrease in plasma triglycerides and a 59% decrease in high density lipoprotein-cholesterol. Analysis of the lipoprotein density fractions revealed that increased expression of the LPL transgene resulted in a remarkable reduction in the level of very low density lipoproteins as well as in the level of intermediate density lipoproteins. In addition, LDL cholesterol levels in transgenic rabbits were significantly increased. When transgenic rabbits were fed a cholesterol-rich diet, the development of hypercholesterolemia and aortic atherosclerosis was dramatically suppressed in transgenic rabbits. These results demonstrate that systemically increased LPL activity functions in the metabolism of all classes of lipoproteins, thereby playing a crucial role in plasma triglyceride hydrolysis and lipoprotein conversion, and that overexpression of LPL protects against diet-induced hypercholesterolemia and atherosclerosis.

Can we identify genes for susceptibility to diabetic microangiopathies using stroke-prone spontaneously hypertensive rat models?

The aortic biochemical properties are reported to be altered in stroke-prone spontaneously hypertensive rats (SHR-SPs) as a result not only of the accelerated accumulation of advanced glycation end products (AGEs) in thoracic aortae but also of primary defects. There is a growing body of evidence that reactive oxygen species (ROS) are involved in the formation of AGEs. We propose here a novel hypothesis that SHR-SPs are the strain that genetically produce more ROS generations. Since ROS formations and AGE accumulations play central roles in the pathogenesis of diabetic microvascular complications, SHR-SPs might be more susceptible to vascular complications when induced to be diabetic. To reveal new genes involved in susceptibility to diabetic microangiopathies through the study of these animal models might be a valuable strategy to develop novel therapeutic approaches.

Enhanced atherosclerosis in Lp(a) WHHL transgenic rabbits.

High lipoprotein(a) [Lp(a)] levels form a major risk factor for the development of atherosclerosis. The risk of elevated Lp(a) concentrations is significantly increased in patients who also have high levels of LDL cholesterol. Although the relation between Lp(a) and atherosclerosis has been reported in numerous studies, little is known about whether Lp(a) would exacerbate the complicated lesion formation in vivo. To test the hypothesis that increased plasma levels of Lp(a) may enhance the development of atherosclerosis in the setting of hypercholesterolemia, we generated WHHL transgenic rabbits expressing human apolipoprotein (a) and compared the atherosclerotic lesions with those of nontransgenic WHHL rabbits.

Role of endothelin-1 in atherosclerosis.

Increased evidence has shown that endothelin-1 (ET-1) derived from the arterial cells is involved in the development of atherosclerosis. ET-1 and ET receptors are upregulated in both human and experimental animal atherosclerotic lesions. Plasma ET-1 levels are significantly elevated in hypercholestolemic subjects and cholesterol-fed animals. We hypothesized that plasma lipoproteins such as LDL and HDL retained in the arterial wall can affect ET-1 production and secretion, thereby sustaining vascular functions. Using a two-chamber culture system, we have demonstrated that endothelial cells (ECs) show a polar secretion of ET-1; the majority of ET-1 are secreted toward the basal side of the vessels. Furthermore, we found that LDL enhances whereas HDL inhibits the ET-1 secretion from ECs in a polarized pattern. In order to demonstrate ET receptor distribution in the lesion, we recently studied both human and apoE-KO mice. Our study showed that there is an increased expression of ETB receptors in foamy macrophages in the lesions. More importantly, medial smooth muscle cells (SMCs) beneath the foam cell lesions exhibited a higher intensity of ETB receptor immunoreactivity than those located in foam cell-free areas. In such an area, ET-1 immunoreactivity is also increased. These results suggest that accumulation of foamy macrophages may modulate the shift of ET receptor subtypes from ETA to ETB in SMCs and an enhanced ET system mediated by ETB receptors may play a pivotal role in the progression of atherosclerosis. This notion has been further supported by a recent finding that administration of ET receptor antagonists resulted in a significant reduction of atherosclerosis in apoE-KO mice.

Roles of the AGE-RAGE system in vascular injury in diabetes.

This study concerns whether advanced glycation endproducts (AGE) are related to microvascular derangement in diabetes, exemplified by pericyte loss and angiogenesis in retinopathy and by mesangial expansion in nephropathy. AGE caused a decrease in viable pericytes cultivated from bovine retina. On the other hand, AGE stimulated the growth and tube formation of human microvascular endothelial cells (EC), this being mediated by autocrine vascular endothelial growth factor. In AGE-exposed rat mesangial cells, type IV collagen synthesis was induced. Those AGE actions were dependent on a cell surface receptor for AGE (RAGE), because they were abolished by RAGE antisense or ribozyme. The AGE-RAGE system may thus participate in the development of diabetic microangiopathy. This proposition was supported by experiments with animal models; several indices characteristic of retinopathy were correlated with circulating AGE levels in OLETF rats. The predisposition to nephropathy was augmented in RAGE transgenic mice when they became diabetic.

Plasma nitrite/nitrate concentrations as a tumor marker for hepatocellular carcinoma.

Since plasma concentrations of nitrite/nitrate, the stable end-products of nitric oxide, increase in patients with hepatocellular carcinoma (HCC) correlatively to tumor volume, we examined the ability of plasma nitrite/nitrate to discriminate between those patients with HCC and those without and compared the diagnostic performance of the parameter with that of serum alpha-fetoprotein (AFP) concentrations. Plasma nitrite/nitrate and serum AFP concentrations were measured using a Griess reaction and a solid phase enzyme immunoassay, respectively. Eighty-nine patients with chronic liver diseases (CLD) with (n=39) or without HCC (n=50) and 50 healthy control subjects participated in the study. A receiver operating characteristic (ROC) curve was used to determine the optimal cut-off value and accuracy. The areas under ROC curves for nitrite/nitrate and AFP were calculated to be 0.758 and 0.812, respectively, which were not significantly different. There was no correlation between the concentrations of plasma nitrite/nitrate and serum AFP. The sensitivity, the specificity, and diagnostic efficiency were 79.5, 72.0, and 75.3%, respectively, for nitrite/nitrate, and 74.4, 76.0, and 75.3%, respectively, for AFP. Based on a partial ROC curve, the clinical utility of plasma nitrite/nitrate as a tumor marker approximated that of serum AFP, but exceeded in AFP-negative patients. Indeed, nitrite/nitrate was positive in 70% of AFP-negative HCC patients. The simultaneous determinations of serum AFP and plasma nitrite/nitrate concentrations gave significant improvement in detection of HCC in CLD patients compared with that of serum AFP alone.

Placenta growth factor and vascular endothelial growth factor B and C expression in microvascular endothelial cells and pericytes. Implication in autocrine and paracrine regulation of angiogenesis.

We have shown previously that vascular endothelial growth factor (VEGF) synthesized by the cellular constituents of small vessels per se, viz. endothelial cells and pericytes, participates in the hypoxia-driven proliferation of both cell types (Nomura, M., Yamagishi, S., Harada, S., Hayashi, Y., Yamashima, T., Yamashita, J., Yamamoto, H. (1995) J. Biol. Chem. 270, 28316-28324; Yamagishi, S., Yonekura, H., Yamamoto, Y., Fujimori, H., Sakurai, S., Tanaka, N., and Yamamoto, H. (1999) Lab. Invest. 79, 501-509). In this study, we examined the expression of the recently isolated VEGF gene family members (placenta growth factor (PlGF), VEGF-B, and VEGF-C) in human dermal microvascular endothelial cells and bovine retinal pericytes cultured under various oxygen tensions. Quantitative reverse transcription-polymerase chain reaction analyses demonstrated that the two cell types possess not only VEGF (VEGF-A) mRNA, but also VEGF-B, VEGF-C, and PlGF mRNAs. Among them, only VEGF-A mRNA was induced under hypoxia. Competitive reverse transcription-polymerase chain reaction showed that, under normoxic conditions, the rank order of mRNA content in endothelial cells was PlGF > VEGF-B > VEGF-C > VEGF-A and that mRNA coding for PlGF was expressed at >100-fold higher levels than VEGF-A mRNA. In pericytes, the rank order was VEGF-C > VEGF-A > VEGF-B > PlGF, and approximately 7-fold higher levels of VEGF-C mRNA compared with VEGF-A mRNA were noted in this cell type. Furthermore, antisense inhibition of PlGF protein production lowered the endothelial cell synthesis of DNA under hypoxic conditions. The results suggest that these VEGF family members may also take active parts in angiogenesis.

Low-density lipoproteins modulate endothelial cells to secrete endothelin-1 in a polarized pattern: a study using a culture model system simulating arterial intima.

We investigated the structural and functional properties of human umbilical vein endothelial cells (HUVECs) cultured on a two-chamber culture model system using an amnion membrane. Compared to HUVECs cultured on a plastic dish, HUVECs cultured on the model system exhibited several features similar to those of in vivo vessels, including formation of the intercellular junctional devices and expression of tight junction-associated protein ZO-1 and adherence junction-associated protein alpha-catenin. Furthermore, we found that HUVECs had a property of polar secretion of endothelin-1 (ET-1). About 90% of the total amount of synthesized ET-1 was found in the lower well, designated as the basal side. When HUVECs were incubated with either native low-density lipoproteins (nLDLs) or oxidized LDLs (oxLDLs) at a concentration of 100 microgram/ml, ET-1 secretion was significantly increased, dependent on the cell side (apical vs basal) on which the nLDLs or oxLDLs were loaded. When the LDLs were loaded on the apical side, the secretion of ET-1 from HUVECs on the apical side was increased by 48% (nLDL) and 61% (oxLDL), whereas it was accompanied by a concomitant decrease of ET-1 on the basal side (45% by nLDLs and 38% by oxLDLs). When loaded on the basal side, however, ET-1 was increased by 23% (nLDLs) and 53% (oxLDLs) on the basal side, with a 26% simultaneous decrease of ET-1 on the opposite side for both nLDLs and oxLDLs. On the contrary, high-density lipoproteins (HDLs) inhibited ET-1 secretion from HUVECs on the opposite side of the well on which HDLs were loaded; there was a 57% decrease on the basal side when HDLs were loaded on the apical side, and a 46% decrease on the apical side when loaded on the basal side. These results indicate that modulation of ET-1 secretion from ECs by lipoproteins is virtually dependent on the place (apical vs basal) where these proteins are present. The finding that nLDLs and oxLDLs enhance ET-1 secretion by ECs in a polarized pattern suggests that ET-1 may be involved in pathophysiological processes such as atherogenesis.

High plasma concentrations of nitrite/nitrate in patients with hepatocellular carcinoma.

OBJECTIVES: Nitric oxide (NO) is considered to play a central role in macrophage or Kupffer cell-induced tumor cytotoxicity. Hepatocytes also produce NO in response to several inflammatory stimuli. Thus, there is a possibility that NO production by hepatic tissue is accelerated in patients with hepatocellular carcinoma (HCC). We, therefore, measured plasma nitrite/nitrate levels as an index of in vivo NO production in patients with HCC. METHODS: Plasma nitrite/nitrate levels were measured using Griess reaction in 95 patients with chronic hepatitis (CH) and compensated liver cirrhosis (LC) with (n = 48) or without HCC (n = 47), as well as 45 healthy control subjects. Possible factors related to nitrite/nitrate levels were evaluated for each subject. RESULTS: Plasma nitrite/nitrate levels in patients with HCC based on CH (mean +/- SD, 71.7 +/- 23.1 microM) and LC (52.4 +/- 20.2 microM) were significantly higher than those without HCC (CH, 31.1 +/- 15.0 microM; LC, 34.6 +/- 16.1 microM) (p < 0.01). Plasma nitrite/nitrate levels in patients with HCC based on CH were significantly higher than those in patients with HCC based on LC (p < 0.05). Simple regression analysis showed that plasma nitrite/nitrate levels significantly correlated with both tumor surface area (r = 0.577, p = 0.001) and tumor volume (r = 0.532, p = 0.003). CONCLUSION: Patients with HCC have elevated plasma nitrite/nitrate levels correlating to tumor volume as well as tumor surface area.

Safe and effective treatment of diabetes mellitus associated with chronic liver diseases with an alpha-glucosidase inhibitor, acarbose.

Glucose intolerance and diabetes mellitus are both prevalent in patients with chronic liver diseases. We examined the efficacy and systemic safety of therapy with an alpha-glucosidase inhibitor, acarbose, in diabetes mellitus associated with chronic liver diseases. Twenty patients with chronic hepatitis or liver cirrhosis and overt diabetes mellitus received acarbose (taken orally) for 8 weeks. The initial dosage of acarbose was 50 mg three times daily, taken before meals; this was increased to 100 mg three times daily after 2 weeks. The mean fasting plasma glucose level was 173.7 +/- 18.6 mg/dl (mean +/- SE) at entry, and was significantly decreased to 132.9 +/- 7.5 mg/dl (P < 0.05) after 8 weeks of acarbose treatment. The improved glycemic control was reflected by a significant decrease in glycosylated hemoglobin (HbA1c) from 7.2 +/- 0.3% at entry to 6.3 +/- 0.2% (P < 0.05) after 8 weeks. Serum levels of both aspartate and alanine aminotransferases fluctuated during acarbose treatment, probably due to the natural course of chronic liver diseases, but the mean values had decreased after 8 weeks of treatment. Plasma ammonia levels increased, from 61.3 +/- 10.7 micrograms/dl to 71.1 +/- 9.6 micrograms/dl after 8 weeks of acarbose treatment but the increase was not significant. Clinically significant elevation of plasma ammonia concentration was seen in 2 cirrhotic patients (121 and 124 micrograms/dl); this was asymptomatic and gradually returned to the normal range despite continuous acarbose treatment in one patient, and was reversed after the withdrawal of acarbose with the concomitant administration of lactulose in the other patient. No other blood tests results, including albumin, cholinesterase, and prothrombin time, or lipid profile and nutritional status, in terms of rapid turnover proteins, prealbumin, retinol binding protein, and transferin, were altered throughout the study period. These results indicate that diabetes mellitus associated with chronic liver diseases may be safely and effectively treated with acarbose. However, clinicians must be aware of the possibility of hyperammonemia when they prescribe acarbose for patients with diabetes mellitus and advanced liver cirrhosis.

[Effect of high dose interferon alpha-2b therapy for chronic hepatitis C].

We evaluated the efficacy of high dose interferon therapy in 122 patients with chronic hepatitis C between 1992 and 1995. They received 612 to 836 mega-units (MU) of recombinant interferon alpha-2b as a total dose during a 6-month treatment in our hospital. Fifty one patients (41.8%) achieved complete response (CR) which was defined as persistent normalization of serum aminotransferase levels and disappearance of serum HCV-RNA for more than 6 months after the end of interferon administration. However, there were no CR in patients with genotype II and in those with serum HCV-RNA levels above 1.5 Meq/ml, quantified by branched DNA probe assay. The rate of CR was not increased even if a total dose of IFN administration was increased from 612 MU to 836 MU. These results indicate that some new regimen of interferon therapy is necessary for these cases with high titer of serum HCV-RNA and genotype II to increase the rate of CR.

Development of Sjögren's syndrome during treatment with recombinant human interferon-alpha-2b for chronic hepatitis C.

A 63-year-old woman with type C chronic active hepatitis developed Sjögren's syndrome after being treated with recombinant interferon-alpha-2b. After 3 months' interferon-alpha administration, serum levels of gamma-globulin (4.5 g/dl) and titers of antinuclear and anti-SS-A antibodies were greatly increased, anti-SS-B antibody appeared, and the erythrocyte sedimentation rate was elevated. Although no xerostomia was exhibited, the patient experienced conjunctival dryness. Schirmer's test showed reduced lacrimal gland function and a gum test showed reduced salivary gland function. Sialography revealed scattered pools of retained contrast media with a diameter of around 1-2 mm. Based on these findings, a diagnosis of Sjögren's syndrome was made. This present case may provide important information regarding the pathogenesis of Sjögren's syndrome.

[Sarcomatoid liver carcinoma diagnosed clinically as hemangioma].

This is a case report of a 69-year-old woman with sarcomatoid hepatocellular carcinoma (HCC), which was diagnosed clinically as hemangioma. She was first admitted to our university hospital, complaining of general fatigue in December, 1988, and cholelithiasis and liver cirrhosis with hepatic tumor in Segment 8 were diagnosed. The serum AFP level was within normal range, and the tumor was diagnosed as hemangioma radiologically. She underwent only cholecystectomy and was well without any therapy for the liver tumor up until March in 1991 when she was readmitted to our university hospital due to rapidly progressive liver dysfunction. The size of the liver tumor was unchanged. Despite intensive care, she died of hepatic failure due to cirrhosis in a decompensation state. At autopsy, a well defined yellowish white tumor of 3 cm in maximum diameter was seen in the cirrhotic liver. Although the largest part of the tumor revealed necrosis and hyalinization, a sarcomatoid part composed of spindle-shaped cells was noted in the peripheral portion. In addition, some necrotic ghost cells, probably hepatocellular carcinoma, were also noted. Low molecular cytokeratin, which is always found in HCCs, was seen in spindle-shaped sarcomatoid cells. The liver tumor was diagnosed as sarcomatoid HCC from these pathological findings. We report this histologically unusual HCC with an immunohistochemical study.