Features of the metabolic syndrome and subclinical atherosclerosis in patients with cerebrotendinous xanthomatosis: An augmented risk for premature cardiovascular disease.

Background: Cerebrotendinous xanthomatosis (CTX) is a rare lipid storage disease, caused by deficiency of sterol-27-hydroxylase. Xanthomatous lesions in numerous tissues, and an elevation of cholestanol levels, characterize the disease. Its natural course is progressive neurologic deterioration, leading to premature death. Chronic treatment with oral chenodeoxycholic acid (CDCA) reduces cholestanol levels. Occurrence of premature atherosclerosis has been described in CTX in an unknown mechanism. Aim: The aim of the current work was to evaluate the potential metabolic abnormalities and preclinical vascular changes in Israeli CTX patients. Methods: Ten subjects with CTX were studied. Features of the metabolic syndrome were evaluated, and carotid intima media thickness (cIMT) was measured in the common carotid arteries. Results: All patients were diagnosed with CTX, and all received treatment with CDCA, which resulted in normalization of their plasma cholestanol levels. At the conclusion of the follow up, risk factors for CVD and features of MS were present in all the patients and in three patients, cIMT was higher compared to control subjects. Conclusion: Cardiovascular risk factors and premature vascular changes exist in young CTX patients and proper assessment should be implemented with preventive measures to reduce the risk of atherosclerotic cardiovascular disease in CTX patients.

The effect of α-linolenic acid enrichment in perinatal diets in preventing high fat diet-induced SCD1 increased activity and lipid disarray in adult offspring of low density lipoprotein receptor knockout (LDLRKO) mice.

The present study examined the effects of maternal perinatal dietary ALA enrichment on the high fat diet (HFD)-induced lipid disarray in the adult offspring of low density lipoprotein receptor knock-out (LDLRKO) mice. Female LDLRKO mice received, during pregnancy and lactation, isocaloric diets with either corn oil, RD, or flax oil, ALA. The weaning offspring was given a regular chow diet for a washout period of eight weeks, which was followed by HFD for eight weeks. Plasma and liver lipids and SCD1 activity were then analyzed. The HFD-fed RD adult offspring had substantially higher plasma cholesterol levels than the HFD-fed ALA offspring (15.7 versus 9.7 mmole/l, p<0.00001) and non-alcoholic fatty liver disease (NAFLD) (65.0 versus 23.9 mg/g lipids, p<0.00001). Liver lipids oleic acid (OA) content and monounsaturated to saturated fatty acids (MUFA/SAT) ratio, were two times lower in RD compared to ALA (p<0.0001). The threefold HFD-induced SCD1 raised activity (p<0.00001), and OA produced from SA, observed in RD adult offspring were prevented by perinatal ALA. In conclusion, the resilience of SCD1 to HFD- induced increased activity may account for the beneficial effects of perinatal ALA dietary enrichment in preventing NAFLD and hypercholesterolemia from occurring in adult LDLRKO offspring mice.

Nifedipine Treatment for Hypertension is Associated with Enhanced Lipolytic Activity and Accelerated Clearance of Postprandial Lipemia.

Hypertension, advanced age, postprandial hyperlipidemia, and insulin resistance are major risk factors for atherosclerosis. The calcium channel blocker nifedipine is reported to ameliorate insulin resistance possibly by activating PPARγ. This is expected to become accentuated in elderly individuals due to age-related insulin resistance. Insulin resistance modulates lipoprotein metabolism. Therefore, we reasoned that nifedipne offers the potential for improving postprandial lipemia in association with increasing age. We studied the effect of nifedipine on fasting lipids, postprandial lipemia, insulin sensitivity, and plasma lipolytic activity in 24 and 15 hypertensive subjects aged 70-75 years and 40-45 years, respectively. As expected, nifedipine significantly lowered systolic and diastolic blood pressure. Nifedipine decreased fasting triglyceride level (23%) and increased HDL-C (15%) in the elderly group. At baseline, postprandial triglyceride levels were remarkably elevated in elderly compared to younger patients (1 288±798 vs. 501±260 mg·dl(-1)·h, p<0.05), as was retinyl palmitate (surrogate marker for intestinally-derived cholesterol) in the chylomicrons (45.0±26.5 vs. 23.4±10.6 mg·l(-1)·h, p<0.05) and chylomicron remnant (15.2±5.4 vs. 11.7±4.7 mg·l(-1)·h, p<0.05) fractions. Importantly, while the level of chylomicron remnants in the group of younger subjects remained unchanged after treatment, nifedipine was associated with a significantly decreased chylomicron remnants retinyl palmitate in the elderly group, which dropped to levels, observed in younger subjects. This was accompanied by enhanced insulin sensitivity and augmented plasma lipolytic activity. The present work suggests that nifedipine has favorable metabolic effects that are beyond the known enhancement of insulin sensitivity. The improvement in postprandial lipidemia by nifedipine may add to its anti-atherogenic effects in hypertensive patients.

The Effect of Klotho Treatment on Atherogenesis, Blood Pressure, and Metabolic Parameters in Experimental Rodent Models.

Klotho is a transmembrane protein, expressed mainly in the kidneys and the choroid plexus. The extracellular domain of klotho is composed of 2 internal repeats, KL1 and KL2, which can be cleaved and act as hormones. Klotho-deficient mice develop a phenotype resembling human aging. Laboratory and clinical data suggest a favorable effect of klotho on atherosclerosis, high blood pressure, and metabolic syndrome. Therefore, we aimed to study the effect of klotho treatment on atherogenesis, blood pressure, and metabolic parameters in experimental rodent models. Fructose-fed Sprague-Dawley rats (metabolic syndrome model) and apolipoprotein E (apoE -/-) knock-out mice (atherosclerosis model) were treated with either klotho or its active domain KL1. In apoE -/- mice, klotho unexpectedly elevated plasma cholesterol and triglyceride levels compared to the control group. Yet, it did not increase the aortic sinus atherosclerotic lesion area. In fructose-fed Sprague-Dawley rats, klotho treatment did not lower blood pressure or plasma triglyceride levels. Although KL1 treatment did not lower blood pressure or plasma insulin levels, it significantly reduced the elevation of total plasma triglyceride levels (from 2.3-fold to 1.6-fold, p<0.05) due to lower triglyceride-rich VLDL levels. Klotho did not show any beneficial effects on atherosclerosis and components of the metabolic syndrome and was associated with increased plasma cholesterol levels. On the other hand, treatment with KL1 may lower plasma triglyceride levels independent of insulin. Additional studies are required in order to decipher the complex role of klotho and its active domains in the regulation of plasma lipid levels.

Specific induction of tumor neovasculature death by modified murine PPE-1 promoter armed with HSV-TK.

BACKGROUND: One strategy to increase tissue specificity of gene therapy is to use promoters or enhancers. OBJECTIVES: (1) To enhance the selectivity of a murine preproendothelin-1 (PPE-1) promoter in tumor angiogenesis by using a positive endothelial transcription-binding element. (2) To test the specificity and efficiency of the modified PPE-1 promoter [PPE-1(3X)] in vitro and in vivo by using reporter genes, and the therapeutic gene herpes simplex virus-thymidine kinase (HSV-TK) in a mouse model of Lewis lung carcinoma (LLC). RESULTS: The modified PPE-1 promoter specifically induced expression in the tumor angiogenic vascular bed with a 35-fold higher expression compared to the normal vasculare bed of the lung. Thus, when the HSV-TK gene controlled by the modified PPE-1 promoter was used systemically, it induced tumor-specific necrosis, apoptosis and mononuclear infiltrates, leading to massive destruction of the neovasculature of the pulmonary metastasis, which suppressed metastasis development. CONCLUSIONS: These results show that an adenoviral vector armed with HSV-TK controlled by the endothelial-selective murine PPE-1(3X) promoter is efficient and safe to target tumor neovasculature.

Antiangiogenic systemic gene therapy combined with doxorubicin administration induced caspase 8 and 9-mediated apoptosis in endothelial cells and an anti-metastasis effect.

Ad-PPE-Fas-c is an adenovector that expresses Fas-c under the control of the modified pre-proendothelin-1 (PPE-1) promoter. Fas-c is a chimeric death receptor containing the extracellular portion of tumour necrosis factor 1 receptor (TNFR1) and the transmembrane and intracellular portion of Fas. We recently demonstrated that Ad-PPE-Fas-c induced Fas-receptor-mediated endothelial cell apoptosis. Previously, doxorubicin was shown to enhance Fas-receptor clustering and the induction of its cascade. Therefore, the goal of this work was to test whether doxorubicin augments the capacity of Ad-PPE-Fas-c to induce endothelial cell apoptosis and to elucidate whether either the death-receptor-mediated apoptotic cascade or the mitochondria-associated apoptotic cascade is involved in the combined treatment effect. We found that a combined treatment of Ad-PPE-Fas-c and doxorubicin synergistically induced a reduction in endothelial cell viability and apoptosis. z-IETD-FMK, a caspase-8 inhibitor, and z-LEHD-FMK, a caspase-9 inhibitor, significantly decreased apoptosis induced by the combined treatment. Systemically administered combined therapy significantly reduced the lung metastases burden (70%) in mice as compared to each treatment alone. Thus, a combined treatment of Ad-PPE-Fas-c gene therapy and chemotherapy may be effective in the treatment of metastatic diseases and both the Fas cascade and the mitochondria-associated cascade are essential for this effect.

Rosiglitazone (PPARgamma-agonist) attenuates atherogenesis with no effect on hyperglycaemia in a combined diabetes-atherosclerosis mouse model.

BACKGROUND: The administration of peroxisome proliferator-activated receptor gamma (PPARgamma) agonists to low-density lipoprotein (LDL)-receptor-deficient mice resulted in a reduction in the atherosclerotic lesion area in male mice, but not in female mice. The male mice also exhibited reduction in insulin resistance while the female mice did not. To further examine the relationship between PPARgamma agonists, insulin resistance and atherosclerosis, we used the model of accelerated atherosclerosis in male apolipoprotein E (apoE)-deficient mice rendered diabetic by low-dose streptozotocin (STZ). METHODS: Male, apoE-deficient mice (n = 48) were randomly divided into four groups. To induce diabetes, two groups received low-dose STZ and two groups served as controls. After diabetes induction, rosiglitazone (a PPARgamma agonist) was administered by oral gavage to one of the diabetic and one of the non-diabetic groups. RESULTS: Rosiglitazone reduced significantly the atherosclerotic aortic plaque area in both diabetic and non-diabetic apoE-deficient mice: 340 +/- 54 vs. 201 +/- 27 micromol2 (p = 0.001) in diabetic mice; 243 +/- 22 vs. 158 +/- 27 micromol2 (p = 0.001) in non-diabetic mice. Also, rosiglitazone reduced the correlation coefficient between plasma glucose and the degree of atherosclerosis (p < 0.0025) without affecting plasma glucose levels. The rosiglitazone-treated mice, both diabetic and non-diabetic, had higher lipid levels. CONCLUSIONS: Rosiglitazone-treated animals showed less atherosclerosis despite higher lipid levels and similar glucose levels. These data suggest a direct anti-atherogenic effect of rosiglitazone on the arterial wall.

Fatty acid bile acid conjugates inhibit atherosclerosis in the C57BL/6 mouse model.

OBJECTIVE: The aim of the current research was to study whether fatty acid bile acid conjugates (FABACs) have a beneficial effect on atherosclerosis progression and blood lipid levels in mice. METHODS: C57BL/6 female mice, fed a high-fat Paigen diet, were administered an oral dose of FABAC or DDH2O daily. Quantification of atherosclerotic fatty-streak lesions at the aortic sinus was performed. RESULTS: The FABAC-treated mice showed a significant reduction in the atherosclerotic lesion areas as compared to the control group (p = 0.019). A significant elevation in total cholesterol levels was observed in both the FABAC and control groups. Higher FABAC levels were measured in the high-density lipoprotein fraction as compared to the very-low-density and low-density lipoprotein fractions. CONCLUSION: Our findings demonstrate that FABACs, given orally, reduce the development of atherosclerosis in mice fed a high-fat high-cholesterol diet, despite a lack of effect on plasma lipid levels.

12/15-Lipoxygenase gene disruption attenuates atherogenesis in LDL receptor-deficient mice.

BACKGROUND: Human 15-lipoxygenase (LO) and its murine analogue 12/15-LO are capable of directly oxidizing esterified fatty acids in lipoproteins and phospholipids. Because these oxidized products possess atherogenic properties, it was suggested that LOs may be involved in enhancing atherogenesis. Previous in vivo tests of the role of LOs in atherogenesis animal models, however, have yielded conflicting results. METHODS AND RESULTS: Aiming to study the role of the 12/15-LO in murine atherogenesis, we crossed LDL-receptor-deficient mice (LDL-R(-/-)) with 12/15-LO-knockout mice and evaluated plaque formation 3 to 18 weeks after initiation of a high-fat diet. Atherosclerotic lesions were considerably reduced in the LDL-R/12/15-LO-double-knockout mice compared with LDL-R(-/-) mice at 3, 9, 12, and 18 weeks, at the aortic root as well as throughout the aorta. The cellular composition of plaques from mice deficient in 12/15-LO did not differ with respect to macrophage and T-lymphocyte content compared with plaques from 12/15-LO littermates. CONCLUSIONS: 12/15-LO plays a dominant role in promoting atherogenesis in LDL-R(-/-) mice.

Mechanisms of action of the anti-atherogenic effect of magnesium: lessons from a mouse model.

Magnesium (Mg) fortification of drinking water succeeded in inhibition of atherogenesis development in a transgenic model of atherosclerosis-prone mice fed a high-cholesterol content diet. In order to delineate possible mechanisms of action of the anti-atherogenic effect of Mg, the involvement of LDL oxidation was studied. We determined the susceptibility of LDL to Cu+2 oxidation, anti-oxidized LDL antibody levels, and liver content of retinol and retinyl-palmitate. In order to study another possible mechanism we tested platelets interaction with extracellular matrix in both male and female mice with or without Mg fortification of drinking water. No difference was found in susceptibility of LDL to undergo oxidation. Female mice that received Mg had decreased anti-oxidized LDL antibody levels compared with control female mice, while there was no significant difference among male groups. On the other hand, only in the male group with Mg was a higher content of retinol and retinyl-palmitate found in the livers. Platelets coverage area on extracellular matrix was similar between groups. These results suggest that Mg might affect LDL oxidation, and thus atherogenesis.

Reduced reproduction with increased abortion rate in transgenic mice that overexpress 15-lipoxygenase.

15-Lipoxygenase (15-LOX) is a lipid-oxidizing enzyme that is involved in cell cycle regulation. To evaluate the effect of 15-LOX on reproduction, we studied transgenic mice that overexpress 15-LOX. The transgene was introduced over the genetic background of the low density lipoprotein receptor deficient mice (LDL-R(-/-)) and reproduction was compared to LDL-R(-/-) mice. We found a lower pregnancy rate in the 15-LOX/LDL-R(-/-) mice as compared to the LDL-R(-/-) mice (62.74 vs. 79.1%, p < 0.01). Additionally, a remarkably higher number of resorptions per pregnancy was found in the 15-LOX/LDL-R(-/-) mice (16.7 vs. 3.27%, p < 0.001) and it was accompanied by a significantly higher activity of the 15-LOX enzyme in these resorptions as compared to other tissues. These findings may implicate a role for 15-LOX in the development of spontaneous abortions.

Tissue-specific gene therapy directed to tumor angiogenesis.

Gene therapy directed specifically to the vascular wall, particularly to angiogenic endothelial cells is a prerequisite in vascular disease treatment. Angiogenesis is a major feature in many pathological conditions including wound healing, solid tumors, developing metastases, ischemic heart diseases and diabetic retinopathy. In the present study we developed a tissue-specific gene therapy to the angiogenic blood vessels of tumor metastasis using an adeno-based vector containing the murine preproendothelin-1 (PPE-1) promoter. Genes activated by the PPE-1 promoter were highly expressed in bovine aortic endothelial cells in vitro. Systemic injection of the adenoviral vectors AdPPE-1-luciferase and AdCMV-luciferase to normal C57BL/6 mice, resulted in higher activity of PPE-1 promoter compared with CMV promoter in the aorta and vascularized tissues such as heart, kidney, lung and pancreas. Systemic administration of the adenoviral vector, in mice bearing Lewis lung carcinoma, resulted in high and specific activity of PPE-1 in the new vasculature of primary tumors and lung metastasis. Cellular distribution of the delivered gene revealed highest expression of GFP in angiogenic endothelial cells of the metastasis. We expect that this approach of 'vascular-directed' gene therapy will be applicable to both vascular diseases and cancer.

Homocysteine elevation with fibrates: is it a class effect?

BACKGROUND: Case-control and prospective studies indicate that an elevated plasma homocysteine level is a powerful risk factor for atherosclerotic vascular diseases. Certain medications can induce hyperhomocystinemia, such as methotrexate, trimethoprim and anti-epileptic drugs. There are few reports indicating an interaction between lipid-lowering drugs (cholestyramine and niacin) and homocysteine. Recently, an interaction was shown between fenofibrate and benzafibrates (a fibric acid derivative) and homocysteine plasma levels. OBJECTIVES: To evaluate the effects of different fibrates on plasma homocysteine levels and to measure the reversibility of this effect. METHODS AND RESULTS: We investigated the effects of ciprofibrate and bezafibrate on homocysteine levels in patients with type IV hyperlipidemia and/or low high density lipoprotein levels. While a 57% increase in homocysteine was detected in the ciprofibrate-treated group (n = 26), a 17% reduction in homocysteine was detected in the group treated with bezafibrate (n = 12). The increase in homocysteine in the ciprofibrate-treated group was sustained for the 12 weeks of treatment and was partially reversible after 6 weeks of discontinuing the ciprofibrate therapy. CONCLUSIONS: These results indicate that an increase in plasma homocysteine levels following administration of fibrates is not a class effect, at least in its magnitude. Moreover, it is reversible upon discontinuation of the treatment.

Imaging of aortic atherosclerotic lesions by (125)I-LDL, (125)I-oxidized-LDL, (125)I-HDL and (125)I-BSA.

OBJECTIVE: The aim of the present study was to compare the accumulation of (125)I-labeled low-density lipoproteins (LDL), oxidized LDL (oxLDL), HDL and BSA in advanced atherosclerotic lesions of apoE-deficient mice. METHODS: (125)I-lipoproteins or (125)I-BSA were injected into the tail vein of apoE-deficient mice. Blood clearance of (125)I-lipoproteins and (125)I-BSA and their accumulation in atherosclerotic lesions were assayed. RESULTS: Blood clearance of (125)I-LDL and (125)I-HDL was moderate, and approximately 30% of the injected lipoproteins were present in plasma 24 h following injection. oxLDL was removed much faster from plasma, and less than 10% of (125)I-oxLDL was present in the circulation 30 min after (125)I-oxLDL injection. The clearance of (125)I-BSA from the circulation was slower than the lipoprotein clearance. The highest accumulation of LDL, oxLDL, HDL and BSA was detected in atherosclerotic lesions in the aortic arch and abdominal aorta, while lower accumulation was detected in the less atherosclerotic descending thoracic aorta. CONCLUSION: Our findings demonstrate that both (125)I-HDL and (125)I-BSA as well as (125)I-LDL are accumulated in atherosclerotic plaques and that they can be used for the detection of atherosclerotic lesions.

Adoptive transfer of beta(2)-glycoprotein I-reactive lymphocytes enhances early atherosclerosis in LDL receptor-deficient mice.

BACKGROUND: It has been proposed that autoimmune factors can influence the progression of atherosclerosis. We have previously shown that immunization of LDL receptor-deficient (LDL-RD mice) with beta(2)-glycoprotein I (beta2GPI; a principal target of "autoimmune" antiphospholipid antibodies) enhances early atherosclerosis. In the present study, we tested the hypothesis that adoptive transfer of beta2GPI-reactive T cells can accelerate fatty streak formation in LDL-RD mice. METHODS AND RESULTS: LDL-RD mice were immunized with human beta2GPI. An additional group of mice were immunized with beta2GPI and boosted with the same antigen 3 weeks later. Control mice with immunized with human serum albumin. Lymphocytes obtained from the draining lymph node cells or from splenocytes of beta2GPI- or human serum albumin-immunized mice were stimulated in vitro with beta2GPI or with the mitogen concavalin A, respectively. The cultured lymphocytes were transferred intraperitoneally to syngenic LDL-RD mice, and the mice were fed a high-fat "Western" diet for 5 weeks until death. Mice injected with lymphocytes from draining lymph nodes or spleens of beta2GPI-immunized animals displayed larger fatty streaks than those induced by control treated animals. T-cell-depleted splenocytes from beta2GPI were unable to promote lesion formation in the mice. CONCLUSIONS: The present study provides the first direct evidence for a role of antigen (beta2GPI)-reactive T cells in the promotion of fatty streaks in mice.

Overexpression of 15-lipoxygenase in vascular endothelium accelerates early atherosclerosis in LDL receptor-deficient mice.

To study the possible role of the human lipid-oxidizing enzyme 15-lipoxygenase (15-LO) in atherosclerosis, we overexpressed it specifically in the vascular wall of C57B6/SJL mice by using the murine preproendothelin-1 promoter. The mice overexpressing 15-LO were crossbred with low density lipoprotein (LDL) receptor-deficient mice to investigate atherogenesis. High levels of 15-LO were expressed in the atherosclerotic lesion in the double-transgenic mice as assessed by immunohistochemistry. The double-transgenic, 15-LO-overexpressing, LDL receptor-deficient mice (LDLR-/-/15LO) developed significantly larger atherosclerotic lesions at the aortic sinus compared with lesions in the LDL receptor-deficient (LDLR-/-) mice after 3 and 6 weeks (107,000 versus 28,000 microm(2) [P:<0.001] and 121,000 versus 87,000 microm(2) [P:<0.05], respectively) of an atherogenic diet. LDL from the LDLR-/-/15LO mice was more susceptible to oxidation than was the LDL from the control LDLR-/- mice, as shown by a shorter lag period for copper-induced conjugated diene formation. On the other hand, no differences were found in the levels of serum anti-oxidized LDL antibodies between the study groups. There were also no differences with respect to the density of macrophages and T lymphocytes infiltrating the lesions in both experimental groups. Taken together, these results support the hypothesis that 15-LO overexpression in the vessel wall is associated with enhanced atherogenesis.

Suppression of atherogenesis in female low-density lipoprotein receptor knockout mice following magnesium fortification of drinking water: the importance of diet.

OBJECTIVE: Magnesium (Mg) has previously been found to modulate blood lipid levels, atherogenesis and atherosclerosis in rabbits when used as a dietary supplement. In addition, we have reported that Mg fortification of drinking water can attenuate atherogenesis in male low-density lipoprotein (LDL)-receptor-deficient mice, but had a mild and nonsignificant effect on female mice fed a high-cholesterol diet supplemented with cholic acid. The aim of this study was to examine whether Mg has an antiatherogenic effect in female mice fed a high-cholesterol diet without cholic acid. METHODS: Two groups of female LDL-receptor-deficient mice were included. The mice received either distilled water or water with 50 g of Mg sulfate per liter. In the first (12 weeks) and second (6 weeks) stages of the experiment, the mice received low- and high-cholesterol diets, respectively, both without cholic acid. At the end of each stage of the experiment, blood was drawn for the determination of plasma Mg, calcium and lipid levels. In addition, the extent of atherosclerosis was determined at the aortic sinus level. RESULTS: Mg fortification was associated with higher levels of plasma Mg while the mice were on a high-cholesterol diet, and the extent of atherosclerosis at the aortic sinus was significantly decreased in the female mice that received high levels of Mg compared with the female mice that received distilled water. The female mice that received water fortified with Mg had lower levels of triglycerides after stage 2, whereas no differences regarding cholesterol levels were found. CONCLUSION: These results confirm that Mg fortification of drinking water is capable of inhibiting atherogenesis also in female LDL-receptor-deficient mice fed a high-cholesterol diet, and demonstrate the importance of the nutritional composition of diet in this experimental model.

Effect of hyperglycemia and hyperlipidemia on atherosclerosis in LDL receptor-deficient mice: establishment of a combined model and association with heat shock protein 65 immunity.

Diabetes and atherosclerosis have been proposed to be influenced by immune and autoimmune mechanisms. A common incriminated antigen in both disorders is the heat shock protein (HSP)-60/65. In the current study, we established a model combining hyperglycemia with hyperlipidemia in LDL receptor-deficient (LDL-RD) mice and assessed its possible influences on lipid profile, HSP60/65, and atherogenesis. LDL-RD mice were injected either with streptozotocin to induce hyperglycemia or with citrate buffer (control). When hyperglycemia was induced, both study groups were challenged with a high-fat (Western) diet for 6 weeks. Plasma fasting glucose, lipid profile, and antibody levels to HSP65 and oxidized LDL were assessed. At death, the spleens from both groups were evaluated for their proliferative response to HSP65 and the consequent cytokine production. The extent of atherosclerosis was assessed at the aortic sinus. Plasma glucose, cholesterol, and triglyceride levels were elevated in mice injected with streptozotocin compared with control mice. Atherosclerotic lesions were significantly larger in the streptozotocin-injected hyperglycemic LDL-RD mice (132 +/- 23 x 10(5) microm2) in comparison to their normoglycemic litter-mates (20 +/- 6.6 x 10(5) microm2; P < 0.0001). Both humoral and cellular immune response to HSP65 was more pronounced in streptozotocin-injected mice. When challenged with HSP65 in vitro, splenocytes from streptozotocin-injected mice favored the production of the T-helper (TH)-1 cytokine gamma-interferon. In conclusion, we have established a mouse model that combines hyperglycemia with diet-induced hyperlipidemia in LDL-RD mice and studied its effect on atherosclerosis progression. The accelerated atherosclerotic process is associated with heightened immune response to HSP65 and a shift to a TH1 cytokine profile.

Requisite role for interleukin-4 in the acceleration of fatty streaks induced by heat shock protein 65 or Mycobacterium tuberculosis.

Atherosclerotic lesions can be induced in rabbits and mice immunized with heat shock protein 65 (HSP65). In the current study, we investigated the role of interleukin (IL)-4 in the HSP65- and Mycobacterium tuberculosis (MT)-induced models that exhibit an inflammatory phenotype. Fatty streak formation in IL-4-knockout (IL-4 KO) mice immunized with HSP65 or MT was significantly reduced when compared with lesions in wild-type C57BL/6 mice. However, when injected with control (HSP-free) adjuvant, no differences were evident in the lesion size between wild-type and the IL-4 KO mice. Next, we studied comparatively the extent of humoral and cellular immune responses to HSP65 in the IL-4 KO and wild-type mice, as those are thought to be influential in murine atherosclerosis. Anti-HSP65 antibody levels were reduced in the HSP65-immunized IL-4 KO mice as compared with their wild-type littermates, whereas no differences were evident between the groups with respect to the primary cellular immune response to HSP65. Other than the absence of IL-4 in the knockout mice, the pattern of secreting cytokines interferon-gamma and IL-10 in concanavalin A-primed splenocytes was similar between the groups. HSP65-primed inguinal lymphocytes from IL-4 KO mice immunized with HSP65 secreted higher levels of interferon-gamma (previously shown to be proatherogenic in vivo) as compared with their wild-type controls. 12-/15-Lipoxygenase expression, known to be regulated by IL-4 and to contribute to murine atherosclerosis, in the lesions was not influenced by the immunization protocol used or by IL-4 disruption. Thus, IL-4 may prove a principal cytokine in the progression of early "inflammatory" atherosclerotic lesions and may serve as a target for immunomodulation.

Interleukin (IL)-4 deficiency does not influence fatty streak formation in C57BL/6 mice.

Abundant data is present to implicate oxidatively modified low-density lipoprotein (oxLDL) in enhanced atherogenesis. Among the factors involved in LDL oxidation, an important role has been attributed to human 15-lipoxygenase (LO) and its murine analog 12-LO. The expression of these peroxidizing enzymes is under the control of cytokines, the principal of which is IL-4. In the present study we tested the hypothesis that knocking out the IL-4 gene from C57BL/6 mice would result in suppression of fatty streaks. For this purpose, we have fed 45 female IL-4 transgenic knockout (IL-4T KO) and 45 wild-type (WT) mice an atherogenic diet for 15 weeks. Consecutive determinations of the lipid profile from both study groups were performed at monthly intervals, and fatty streak formation was assessed at the aortic sinus level, upon sacrifice. The two study groups did not differ significantly with respect to the lipid profile or the uptake and degradation of iodinated oxLDL by their peritoneal macrophages. We found that the endogenous deficiency of IL-4 did not confer protection from early atherosclerosis in the IL-4T KO as compared to their WT littermates (determined at the aortic sinus). Immunohistochemical studies, Western blots and 12/15-LO activity assays revealed the presence and activity of 12/15-LO in macrophages of WT mice as well as in IL-4T KO mice. Both did not differ significantly between the study groups. The data from this study imply that deficiency in IL-4 does not affect early atherosclerosis in C57BL/6 mice fed a high-cholesterol diet.