Sphingosine-1 phosphate prevents monocyte/endothelial interactions in type 1 diabetic NOD mice through activation of the S1P1 receptor

Monocyte recruitment and adhesion to vascular endothelium are key early events in atherosclerosis. We examined the role of sphingosine-1-phosphate (S1P) on modulating monocyte/endothelial interactions in the NOD/LtJ (NOD) mouse model of type 1 diabetes. Aortas from nondiabetic and diabetic NOD mice were incubated in the absence or presence of 100 nmol/L S1P. Fluorescently labeled monocytes were incubated with the aortas. Aortas from NOD diabetic mice bound 7-fold more monocytes than nondiabetic littermates (10+/-1 monocytes bound/field for nondiabetic mice vs 74+/-12 monocytes bound/field for diabetic mice, P<0.0001). Incubation of diabetic aortas with 100 nmol/L S1P reduced monocyte adhesion to endothelium by 90%. We found expression of S1P1, S1P2, and S1P3 receptors on NOD aortic endothelial cells. The S1P1 receptor-specific agonist SEW2871 inhibited monocyte adhesion to diabetic aortas. Studies in diabetic S1P3-deficient mice revealed that the S1P3 receptor did not play a pivotal role in this process. S1P reduced endothelial VCAM-1 induction in type 1 diabetic NOD mice, most likely through inhibition of nuclear factor kappaB translocation to the nucleus. Thus, S1P activation of the S1P1 receptor functions in an antiinflammatory manner in type 1 diabetic vascular endothelium to prevent monocyte/endothelial interactions. S1P may play an important role in the prevention of vascular complications of type 1 diabetes.     

Lipoxygenase products increase monocyte adhesion to human aortic endothelial cells

The development of atherosclerosis is accelerated in individuals with type 2 diabetes. Adhesion of monocytes to the vascular endothelium is a key initial step in atherogenesis. We have previously shown that monocyte adhesion to human aortic endothelial cells (HAECs) cultured long-term in high-glucose medium (25 mmol/L, 2 passages) is increased compared with cells grown in normal glucose (5 mmol/L). One potential mechanism for increased monocyte adhesion to HAECs under hyperglycemic conditions is via the 12-lipoxygenase (12-LO) pathway. In this study, we demonstrated in HAECs that the major LO metabolite of arachidonic acid was the 12-LO product, 12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE], which was increased severalfold in HAECs cultured under high-glucose conditions. Furthermore, treatment of HAECs with 12(S)-HETE induced monocyte, but not neutrophil, adhesion an average of 3-fold (range of 1.5- to 5-fold) compared with untreated cells (75+/-5 versus 26+/-1 monocytes per field, respectively, P<0.001). Expression of the adhesion molecules vascular cell adhesion molecule-1, E-selectin, and intercellular adhesion molecule-1 was not significantly increased. However, both glucose and 12(S)-HETE induced a 60% increase in HAEC surface expression of connecting segment-1 (ie, CS-1) fibronectin, a ligand for very late-acting antigen-4 (VLA-4). The antibodies used to block monocyte integrin VLA-4 and leukocyte function-related antigen-1, a monocytic counterreceptor for intercellular adhesion molecule-1, inhibited the ability of both 12-LO products and high glucose to induce monocyte adhesion. These results definitively demonstrate for the first time in HAECs that the 12-LO pathway can induce monocyte-endothelial cell interaction and that the effects of glucose may be mediated, at least in part, through this pathway. Thus, these results suggest that the 12-LO pathway may play a role in the increased susceptibility of diabetics to atherosclerosis.     

Monocyte adhesion to human saphenous vein in vitro.

Monocyte adhesion to endothelium is believed to be an initiating event in atherosclerosis both in arteries and in saphenous vein coronary artery bypass grafts. We have developed a method to quantify adhesion of 51Cr-labelled human blood monocytes to saphenous vein. Adhesion to the intimal surface was measured to uniform 6 mm diameter discs, the adventitia of which was embedded in a layer of inert silicone grease. The identity, number and location of bound cells was further defined by scanning electron microscopy. The proportion of monocytes adhering to discs of freshly-isolated vein was 7.1 +/- 1.2% (SE, n = 8), which was equivalent to 500 +/- 80 monocytes/mm2. The percentage of monocytes adhering was independent of the number of monocytes added in the range 5-50 x 10(4). Scanning micrographs showed 80% endothelial coverage with monocytes adhering preferentially but not exclusively to subendothelium. Endothelial removal increased monocyte adhesion by 1.60 +/- 0.15-fold (n = 8, P less than 0.01). Vein surgically prepared for use in coronary bypass surgery, had a 50% reduction in endothelial coverage and a small but non significant (1.14 +/- 0.13-fold, n = 8) increase in monocyte adhesion. Treatment of freshly-isolated vein for 4 h at 37 degrees C with 1 micrograms/ml of E. Coli endotoxin followed by extensive washing did not remove endothelium but increased monocyte adherence by 1.46 +/- 0.18-fold (n = 8, P less than 0.05). The proportion of monocytes adhering to veins which had been cultured for 14 days was similar to freshly isolated veins (6.4 +/- 0.8%, n = 7), but in cultured veins, monocytes adhered preferentially to cells with typical endothelial morphology. Endotoxin treatment of cultured freshly-isolated veins increased monocyte adhesion by 1.77 +/- 0.23-fold (n = 8, P less than 0.05). The data show that both endothelial activation, and exposure of subendothelium promote monocyte adhesion to human saphenous vein.     

Intercellular adhesion molecule-1 (ICAM-1) expression is necessary for monocyte adhesion to the placental bed endothelium and is increased in type 1 diabetic human pregnancy

BACKGROUND: That adhesion molecule expression is upregulated in endothelial cells of the placental bed in pregnancies complicated by type 1 diabetes mellitus, and that this is associated with increased adherence of peripheral blood monocytes, which can be reversed by reduction in activity or expression of relevant adhesion molecules. Specific aims were to compare the adherence of monocytes from normal pregnancies to decidual endothelial cells from both normal and diabetic pregnancies, and to examine the involvement of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in regulation of such adhesion. METHODS: We examined adhesion of peripheral blood monocytes (isolated by density gradient centrifugation) of normal third trimester pregnant women, to cultured endothelial cells (isolated from decidual biopsies collected at elective caesarean section) from both normal women and those with type 1 diabetes. Adhesion molecule expression was determined by flow cytometry. The role of ICAM-1 was further investigated by monoclonal antibody-blocking experiments and gene-silencing methodology. RESULTS: There was a significant increase in monocyte adhesion to decidual endothelial cells from diabetic pregnancies, associated with increased endothelial cell expression of ICAM-1, but not VCAM-1. ICAM-1 expression in normal decidual endothelial cells was stimulated by pro-atherogenic and pro-inflammatory stimuli. Following ICAM-1 antibody blockade, monocyte adhesion was decreased by > 70%. ICAM-1 silencing by small interfering RNAs also inhibited monocyte adhesion and ICAM-1 expression. CONCLUSIONS: These findings implicate upregulation of ICAM-1 in decidual endothelial cells in the development of placental bed vascular pathology in diabetic pregnancy.     

Effects of the angiotensin II type 1 receptor antagonist telmisartan on monocyte adhesion and activation in patients with essential hypertension.

Circulating monocytes from hypertensive patients show elevated secretion patterns of pro-inflammatory cytokines, an increased expression of adhesion molecules, and an increased adhesion to vascular endothelial cells. We tested the hypothesis that telmisartan, an angiotensin II type 1 (AT(1)) receptor antagonist, reduces the activation of circulating monocytes from hypertensive patients and diminishes the monocyte-endothelial cell adhesion. Monocytes of 20 hypertensive patients and 20 normotensive controls were isolated by density gradient centrifugation and Dynabeads, and the monocyte adhesion to human aortic endothelial cell monolayers was measured by adhesion assays. To characterize monocyte activation we assessed the expression of activity-related cell surface markers that are also involved in monocyte adhesion to endothelial cells, such as CD11a/b and CD54, as well as the chemokine receptors CCR1, CCR2 and CCR5 before and after telmisartan therapy using flow cytometry. Spontaneous adhesion of monocytes from hypertensive patients and the adhesion after stimulation with angiotensin II were significantly increased compared with those in normotensive controls (p<0.05). Treatment of hypertensive patients with the AT(1) receptor antagonist telmisartan significantly diminished the adhesion of circulating monocytes to human endothelial cells (p=0.02) despite the increase in the expressions of CD11b, CD54 and CCR5 after telmisartan therapy. Reducing monocyte adhesion may be a novel beneficial effect of the AT(1) receptor antagonist telmisartan helping to prevent vascular alterations in hypertension. The mechanism of action remains to be elucidated, since reduction in monocyte adhesion was not attributable to changes in adhesion molecule expression.     

The ��-Specific Protein Kinase C Inhibitor Ruboxistaurin (LY333531) Suppresses Glucose-Induced Adhesion of Human Monocytes to Endothelial Cells in Vitro

Aims

Strong evidence shows that late diabetic complications in diabetes mellitus are substantially related to an increased synthesis of diacylglycerol with a subsequent activation of protein kinase C (PKC) β. Several studies have shown that specific inhibition of the PKC isoform β by ruboxistaurin is able to attenuate the development of microvascular complications under diabetic conditions. The aim of this in vitro study was to investigate the effect of ruboxistaurin on glucose-induced adhesion of monocytes to endothelial cells, representing one of the first pivotal steps in the course of atherogenesis.

Methods

Human umbilical venous endothelial cells were isolated and cultured to confluence in microtiter plates. After coincubation with monocytes in the presence of 0, 10, or 400 ng ruboxistaurin to achieve PKC β-specific and -unspecific PKC inhibition, cells were fixed and monocyte adhesion was determined by means of a standardized chemiluminescence assay. Expression of adhesion molecules (intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin) was also measured by chemiluminescence methods.

Results

Adhesion of monocytes to endothelial cells cultured under hyperglycemic conditions (27.7 mM glucose) was increased by 30.9 ± 5.1% (p < 0.001) versus endothelial cells cultured under normoglycemic (NG) conditions (5.5 mM). Pretreatment of endothelial cells with 10 nM (PKC β-specific concentration) and 400 nM (PKC β-unspecific concentration) led to a significant reduction of glucose-induced adhesion of monocytes to endothelial cells that was statistically not different from endothelial adhesion under NG conditions (−7.2 ± 3.1 and −8.1 ± 2.6%, respectively; not significant vs NG). A nonsignificant tendency to lower the expression of adhesion molecules was seen with 10 ng of ruboxistaurin.

Conclusions

We conclude that monocyte adhesion to endothelial cells under hyperglycemic conditions is at least mediated by PKC β activation. Ruboxistaurin is able to suppress this monocyte adhesion even in a PKC β-specific concentration. Further studies should evaluate these potential effects of ruboxistaurin in vivo.     

Cholesterol-induced upregulation of angiotensin II and its effects on monocyte-endothelial interaction and superoxide production.

Atherogenesis involves an early endothelial dysfunction hallmarked by elevated free radical production and increased adhesiveness for monocytes. It was hypothesized that activation of the tissue renin angiotensin system may contribute to the endothelial alteration. To test this hypothesis, thoracic aortae were isolated from normocholesterolemic (NC; n = 6) and hypercholesterolemic (HC; n = 6; diet: 0.5% cholesterol; 6 weeks) New Zealand white rabbits, and incubated for 2 h with the angiotensin II (Ang II) receptor antagonist Sar-1,Ile-8-Ang II, the antioxidant pyrolidine dithiocarbamate (PDTC) and the protein kinase C (PKC) antagonist staurosporin. Superoxide production from aortic segments was measured by lucigenin-enhanced chemiluminescence. In comparison to the normocholesterolemic state, hypercholesterolemia led to a significant increase in superoxide production (221 +/- 44%, p < 0.02); this was reduced by ex vivo treatment of the vessel segment with Ang II-antagonist (to 130 +/- 29%; p < 0.04 vs HC), or PKC-antagonist (to 86 +/- 26%; p < 0.001 vs HC), or PDTC (to 103 +/- 27%; p < 0.02 vs HC). Monocyte-endothelial interaction was assessed by functional binding assay. When compared to normocholesterolemic rabbits, hypercholesterolemia led to a twofold increase in monocyte binding (74 +/- 13 vs 37 +/- 4 monocytoid cells per high power field (m/hpf); p < 0.03). The Ang II-antagonist and the PKC-antagonist led to a normalization of monocyte-endothelial binding (Ang II-antagonist: 37 +/- 9 m/hpf; PKC-antagonist: 41 +/- 17 m/hpf; p < 0.05). In conclusion, these results indicate that hypercholesterolemia activates the tissue renin angiotensin system, which results in an increased endothelial production of superoxide and monocyte adhesiveness. Ang II-antagonist inhibits free radical production and monocyte adhesion through a mechanism which may include PKC.     

Urokinase receptor surface expression regulates monocyte adhesion in acute myocardial infarction

The urokinase receptor (urokinase plasminogen activator receptor; uPAR) regulates monocyte adhesion by direct binding to vitronectin and by forming complexes with integrins. Therefore, possible up-regulation of uPAR in acute myocardial infarction (AMI) may affect monocyte adhesion. In 20 patients with AMI, uPAR surface expression (measured by flow cytometry) was increased compared with that in patients with chronic stable angina (mean +/- SD fluorescence, 179 +/- 96 vs 80 +/- 53; P =.002). Expression of uPAR correlated with activation of beta(2)-integrins lymphocyte function-associated antigen 1 (LFA-1) and macrophage antigen 1 (Mac-1), measured by using monoclonal antibodies (mAbs) 24 and CBRM1/5. Isolated mononuclear cells (MNCs) from patients with AMI showed enhanced adhesiveness to human umbilical vein endothelial cells (HUVECs), to fibrinogen (Mac-1 ligand), and to vitronectin (uPAR ligand). Excessive adhesion of MNCs to HUVECs was inhibited by mAbs anti-CD18 (84%), anti-CD11a (51%), and anti-CD11b (57%), indicating a major contribution of LFA-1 and Mac-1. The mAb anti-uPAR R3 blocked adhesion of cells from patients with AMI to vitronectin (95%) but also beta(2)-integrin-mediated adhesion to fibrinogen (79%) and HUVECs (66%). Incubation of monocytic MonoMac6 cells with plasma from patients with AMI enhanced uPAR messenger RNA expression and cell adhesion to HUVECs. Thus, released soluble factors may contribute to enhanced monocyte adhesion in AMI. Mouse pre-B lymphocytes (BAF3 cells) transfected with various amounts of uPAR complementary DNA showed a strong correlation of uPAR expression with beta(2)-integrin-dependent adhesion to intercellular adhesion molecule 1, thus providing evidence for the functional relevance of uPAR up-regulation in an isolated in vitro system. In conclusion, we found that uPAR expression is elevated on monocytes in AMI and contributes to enhanced cell adhesion. Thus, uPAR may be a novel target for prevention of unwanted monocyte recruitment as part of inflammatory cardiovascular processes.     

Endothelial dysfunction in a family with familial combined hyperlipidemia

Familial Combined Hyperlipidemia is the most frequent familial hyperlipidemia with a high risk a early manifestation of arteriosclerosis. Endothelial dysfunction is the first step in the development of arteriosclerosis. The aim of our investigation was to examine selected markers of endothelial dysfunction in hyperlipidemic members of families with familial combined hyperlipidemia and their normolipidemia first-line relatives and to compare them with healthy individuals. The study includes non-smoking members of the affected families (probands and first-line relatives), who have not suffered from clinical manifestations of arteriosclerosis and/or hypertension during the start of the study. The cohort was divided into hyperlipidemic individuals (N = 25) and normolipidemic individuals (N = 21). Both groups were compared with control groups of healthy individuals (two groups, N = 17 each), who were adjusted by age and sex. The following markers of endothelial dysfunction were examined: 1. ultrasound--flow mediated dilatation of brachial artery and 2. humoral--serum levels of von Willebrand factor, inhibitor of activator of plasminogen-1 and vasoadhesive molecules (vascular cell adhesion molecule-1, intercellular adhesion molecule-1). The members of families with familial combined hyperlipidemia displayed symptoms of endothelial dysfunction. In comparison with healthy controls the endothelial dysfunction was more expressed in hyperlipidemic individuals. They displayed a significantly lower flow-mediated dilatation of brachial artery (3.6 +/- 3.3% versus 6.6 +/- 2.8%, P < 0.01), higher levels of von Willebrand factor (152.8% +/- 79.1% versus 110.4% +/- 24.8%, P < 0.05), inhibitor of activator of plasminogen-1 (94.6 +/- 30.8 ng/ml versus 60.4 +/- 38.0 ng/ml, P < 0.01) and vasoadhesive molecules: vascular cell adhesion molecule-1 (927.0 +/- 167.7 ng/ml versus 814.7 +/- 171.1 ng/ml, P < 0.05), intercellular adhesion molecule-1 (601.7 +/- 89.5 ng/ml versus 544.8 +/- 59.8 ng/ml, P < 0.05). The normolipidemic individuals displayed only a significantly lower flow-mediated dilatation of brachial artery (5.6 +/- 2.6% versus 7.5 +/- 2.8%, P < 0.05) and higher levels of von Willebrand factor (136.8 +/- 40.32% versus 104.1 +/- 24.9%, P < 0.05). No significant difference was found in the levels of inhibitor of activator of plasminogen-1 and vasoadhesive molecules. The results indicated that members of families with familial combined hyperlipidemia represent a high-risk group from the standpoint of early manifestation of arteriosclerosis.     

Patients with combined hypercholesterolemia-hypertriglyceridemia show an increased monocyte-endothelial cell adhesion in vitro: triglyceride level as a major determinant

Hypercholesterolemia (HC) is one of the primary risk factors for atherosclerosis. Patients with familial hypercholesterolemia (FH) or combined hypercholesterolemia-hypertriglycerinemia (CHH) are at risk to develop premature atherosclerosis. Animal models have revealed that diet-induced HC in vivo leads to an increased adhesion of monocytes to the endothelium of the vessel wall. Changes in the monocytes, endothelial cells, or serum components may lead to the increased monocyte adhesion that results in atherosclerotic plaque formation. In the present study, we investigated the binding of the monocyte in an in vitro system. Incubation of freshly isolated monocytes from CHH patients with cultured human umbilical vein endothelial cells (HUVEC) gave a significant 60% increase in monocyte adhesion when compared with monocytes from healthy subjects. No such increase was observed using monocytes from nontreated FH patients. These data suggest that CHH results in in vivo alterations of the monocytes that lead to an increased in vitro adhesion to HUVEC, and that an increased level of plasma triglycerides is the major determinant, since HC alone does not induce this alteration.     

Monocyte phagocytic activity in sickle cell disease

The phagocytic activity of peripheral blood monocytes from sickle cell disease patients and normal controls was studied using a monocyte monolayer assay. Phagocytosis of antibody-coated red cells by monocytes from patients in stable condition and in normal controls did not differ significantly (7.1 +/- 1.5 vs. 5.3 +/- 0.9%). However, monocytes from sickle cell disease patients during vasoocclusive crises demonstrated increased phagocytic activity compared to the normal controls (11.0 +/- 2.7 vs. 5.3 +/- 0.9%, p less than 0.025). Numerous defects in immune response have been described in association with sickle cell disease. However, monocyte phagocytic activity is not deficient and is not a factor in the predisposition to infections.     

2型糖尿病患者糖耐量正常一级亲属血管内皮功能及炎症因子的研究

目的研究2型糖尿病患者一级亲属糖耐量正常者(FDR)的血管内皮功能、炎症因子水平及其影响因素。方法测定31例正常人、57例FDR的血管内皮功能、血浆纤溶酶原激活物抑制物1(PAI1)及血清可溶性血管细胞黏附分子1(VCAM1)水平,同时测定胰岛素水平,计算胰岛素敏感性(IAI)。结果与正常对照组比较,FDR内皮依赖性血管舒张功能减低[(1245±337)%比(503±034)%],IAI降低[(-379±057)比(-411±046)],血浆PAI1水平升高[(3046±1228)μg/L比(3925±654)μg/L],血清VCAM1水平升高[(63731±10732)μg/L比(74239±12431)μg/L],差异均有统计学意义(P值均<005)。结论糖耐量正常的2型糖尿病患者一级亲属胰岛素敏感指数下降、血管内皮功能受损、纤溶活性降低,且血管内皮功能失调与胰岛素抵抗密切相关。     

Do glucose and lipids exert independent effects on atherosclerotic lesion initiation or progression to advanced plaques?

It is becoming increasingly clear that suboptimal blood glucose control results in adverse effects on large blood vessels, thereby accelerating atherosclerosis and cardiovascular disease, manifested as myocardial infarction, stroke, and peripheral vascular disease. Cardiovascular disease is accelerated by both type 1 and type 2 diabetes. In type 1 diabetes, hyperglycemia generally occurs in the absence of elevated blood lipid levels, whereas type 2 diabetes is frequently associated with dyslipidemia. In this review article, we discuss hyperglycemia versus hyperlipidemia as culprits in diabetes-accelerated atherosclerosis and cardiovascular disease, with emphasis on studies in mouse models and isolated vascular cells. Recent studies on LDL receptor-deficient mice that are hyperglycemic, but exhibit no marked dyslipidemia compared with nondiabetic controls, show that diabetes in the absence of diabetes-induced hyperlipidemia is associated with an accelerated formation of atherosclerotic lesions, similar to what is seen in fat-fed nondiabetic mice. These effects of diabetes are masked in severely dyslipidemic mice, suggesting that the effects of glucose and lipids on lesion initiation might be mediated by similar mechanisms. Recent evidence from isolated endothelial cells demonstrates that glucose and lipids can induce endothelial dysfunction through similar intracellular mechanisms. Analogous effects of glucose and lipids are also seen in macrophages. Furthermore, glucose exerts many of its cellular effects through lipid mediators. We propose that diabetes without associated dyslipidemia accelerates atherosclerosis by mechanisms that can also be activated by hyperlipidemia.     

Human monocyte characteristics are altered in hypercholesterolaemia

Peripheral blood monocytes are involved during atherogenesis in adhering to endothelium, migrating into the subendothelial space and taking-up lipoproteins to become macrophage/foam cells. We have assessed whether peripheral blood monocyte characteristics are altered in human hyperlipidaemia in age/sex/smoking status matched pairs of patients and controls. Monocytes from the hypercholesterolaemic patients, as opposed to the controls, were more sensitive to stimulation by the agonist, N-formylmethionyl-leucyl-phenylalanine, with respect to chemokinesis (stimulation index 1.48 ± 0.17 vs. 1.10 ± 0.14), chemotaxis (4.05 ± 0.55 vs. 2.72 ± 0.24) and adhesion to porcine aortic endothelial monolayers (1.26 ± 0.05 vs. 1.17 ± 0.06). The patients' monocyte total surface expression of the adhesion glycoprotein CD11b/CD18 (37.5 ± 7.1 vs. 36.0 ± 7.1), but not CD11c/CD18 (31.6 ± 7.2 vs. 31.4 ± 6.8), was increased; however, the monocytes in hyperlipidaemia were larger (9.15 ± 0.11 μm vs. 8.98 ± 0.11 μm) such that the surface density of CD11b/CD18 was not altered (0.144 ± 0.029 vs. 0.142 ± 0.029). The data suggest that circulating monocytes are functionally different in hypercholesterolaemia. This may explain the increased involvement by monocytes in hypercholesterolaemia-related atherogenesis.     

Circulating adhesion molecules levels in type 2 diabetes mellitus and hypertension

BACKGROUND: Risk factors for atherosclerosis such as hypertension, type 2 diabetes, obesity and dyslipidemia affect endothelial function and stimulate adhesion molecules expression. The aim of the study was to examine endothelial activation in type 2 diabetes and hypertension as indicated by adhesion molecule levels and further to investigate whether the coexistence of the above conditions has a different effect. METHODS: Serum levels of soluble E-selectin, ICAM-1 and VCAM-1 were measured in 17 hypertensive type 2 diabetic patients (DM-HY), 32 normotensive type 2 diabetic patients (DM), 11 hypertensive nondiabetic patients (HY) and 15 healthy subjects. RESULTS: In diabetic patients (either DM-HY or DM), soluble E-selectin levels were significantly increased compared to healthy subjects (p<0.001). In HY patients, both sE-selectin (66.44+/-71.59 vs. 29.42+/-15.56 ng/ml, p=0.033) and sVCAM-1 (1529+/-433.33 vs. 1027+/-243.56 ng/ml, p=0.03) levels were found significantly higher compared to healthy subjects (p<0.05). The coexistence of diabetes and hypertension (DM-HY) did not have an additive effect on circulating adhesion molecules levels compared with the levels observed in either diabetes or hypertension. Systolic and diastolic blood pressure (BP) were independent factors correlated respectively with sE-selectin and sVCAM-1 levels (R=0.454, p=0.034 and R=0.578, p=0.005) in nondiabetic subjects (hypertensive and normotensive). CONCLUSIONS: Type 2 diabetes mellitus and hypertension induce endothelial activation as indicated by elevated levels of soluble adhesion molecules. This effect is not different when comorbidity is present.     

Role of vascular cell adhesion molecule-1 and fibronectin connecting segment-1 in monocyte rolling and adhesion on early atherosclerotic lesions

Atherosclerotic lesion development seems to be inflammatory in nature and involves the recruitment of monocytes to the vessel wall. In this study, we investigated the role of vascular cell adhesion molecule-1 (VCAM-1) and fibronectin (FN) connecting segment-1 containing the amino acid sequence ILDV as functional ligands for alpha(4)beta(1) integrin (VLA-4) in monocyte rolling and adherence to early atherosclerotic lesions. Carotid arteries of apolipoprotein E-deficient mice were isolated and perfused with monocytes or U937 cells. Cell adhesion was reduced 95+/-4% by monoclonal antibodies HP1/2 and HP2/1, which block VLA-4 binding to both VCAM-1 and FN connecting segment-1. mAb HP1/3 preferentially blocked interaction of VLA-4 with FN but not VCAM-1 and decreased adhesion by 30+/-8%. In contrast, blocking VCAM-1 by perfusing the isolated carotid artery with mAb MK-2.7 reduced adhesion by 75+/-12%. Mononuclear cell adhesion to the early atherosclerotic endothelium was inhibited by 68+/-10% in the presence of EILDVPST but not in the presence of control peptide EIDVLPST. When VLA-4 or VCAM-1 was blocked, more mononuclear cells rolled on early lesions at significantly higher (approximately doubled) rolling velocities. These data demonstrate that (1) blockade of VCAM-1 can abrogate the majority (75+/-12%) of VLA-4-dependent monocyte adhesion on early atherosclerotic endothelia and (2) ILDV peptide interferes with VLA-4 binding to both VCAM-1 and FN and may be useful in limiting monocyte adhesion to atherosclerotic lesions.     

Expression of monocyte and lymphocyte adhesion molecules is increased in isolated coronary artery ectasia

BACKGROUND: Coronary artery ectasia is defined as localized or diffuse dilation of the coronary arteries exceeding the 1.5-fold of normal adjacent segment. Scarce data are available about the role of inflammation in coronary artery ectasia. In the present study, we aimed to evaluate the expression of CD11b and CD45 adhesion molecules in peripheral blood granulocytes, monocytes and lymphocytes from the patients with coronary artery ectasia as possible indicators of inflammation. METHOD: The study consisted of 14 patients who had angiographically normal coronary arteries with coronary artery ectasia and 13 age and sex-matched controls without coronary artery ectasia. Cell surface adhesion molecules were detected by direct immunofluorescence evaluated by flow cytometry using monoclonal antibodies tagged with fluorescent markers. Venous blood samples were taken after coronary angiography. RESULTS: Mean fluorescence intensity of CD45 (33.8+/-3.1 vs. 13.0+/-0.7, P<0.001) and CD11b (39.1+/-13.5 vs. 19.5+/-1.32, P<0.001) on the monocyte surface of patients with coronary artery ectasia were higher than those of controls. Similarly in patients with coronary artery ectasia, the expression of CD11b (7.5+/-0.61 vs. 5.6+/-0.2, P=0.009) and CD45 (47.5+/-3.6 vs. 36.2+/-2.5, P=0.02) on lymphocytes was also significantly higher than those of controls. CONCLUSION: Increased levels of cellular adhesion molecules in patients with coronary artery ectasia may be an indicator of endothelial activation and inflammation and are likely to be in the causal pathway leading to coronary artery ectasia.     

Increased Expression of Monocyte CD11b (Mac-1) in Overweight Recent-Onset Type 1 Diabetic Children

AIM: Compelling evidence implicates inflammation in the pathogenesis of type 1 diabetes mellitus (T1DM) and associated vascular complications. Obesity is also characterized by low-grade systemic inflammation. In this study, we characterized the inflammatory response in diabetes by analyzing the expression of a panel of activation markers on the surface of peripheral blood monocytes in recently-diagnosed T1DM patients. The potential effects of glycemic control and body mass index (BMI) on monocyte phenotype were also investigated. METHODS: Using flow cytometry, we analyzed the expression of CD11b, CD49d, CD54, CD62L and CD64 antigens on monocytes in a cohort of 51 T1DM patients (≤ 2 months after diagnosis). To test whether phenotype change in monocytes was associated with abnormal cellular function, we studied the adhesive capacity of monocytes to human umbilical vein endothelial cells (HUVEC). RESULTS: We found that circulating monocytes from T1DM patients tested at the clinical onset of the disease (i.e. within 1 week of diagnosis) had higher CD11b expression compared to patients analyzed 2 months after diagnosis (p = 0.02). The highest CD11b levels were detected in patients with HbA1c < 8% (p = 0.04 vs. patients with HbA1c < 8%). In T1DM children analyzed 2 months after diagnosis, we found that those who were overweight (BMI ≥ 85th percentile) had higher levels of monocyte activation than those who were not (BMI ≤ 85th percentile) (p = 0.03). CD11b and HbA1c were significantly correlated (correlation coefficient 0.329, p = 0.02). Finally, monocytes from T1DM patients showed higher adhesion to HUVEC compared to controls. CONCLUSIONS: Circulating immune cells from T1DM patients display many aspects of a proinflammatory state, as indicated by primed or activated monocytes. Obesity is an important factor in monocyte activation during diabetes.