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Macrophage-mediated inflammation plays an essential role in diabetes-associated nonalcoholic steatohepatitis (NASH) and atherosclerosis. Our previous study has shown that acid sphingomyelinase (ASMase) plays a key role in the synergistic stimulation of inflammatory signaling by saturated fatty acid palmitate and lipopolysaccharide (LPS) in macrophages. In the current study, we assessed the effect of ASMase inhibition on NASH and atherosclerosis induced by lard-based, high palmitate-containing high-fat diet (HP-HFD) in combination with LPS in LDL receptor-knockout (LDLR-/-) mice. LDLR-/- mice were fed HP-HFD for 20 weeks and treated with or without a low dose of LPS and amitriptyline, an inhibitor of ASMase. Metabolic assays showed that amitriptyline reduced bodyweight, lipids and insulin resistance induced by HP-HFD or HP-HFD plus LPS. Histological study and Oil Red O staining of livers showed that while mice fed HP-HFD without LPS treatment had hepatic steatosis and hepatocellular ballooning, LPS further increased steatosis and ballooning by 70%. However, amitriptyline attenuated the effect of HP-HFD or HP-HFD plus LPS by 66%. Immunohistochemistry study showed that while mice fed HP-HFD without LPS treatment had a marked immunostaining of F4/80, a biomarker for macrophages, LPS further enhanced F4/80 immunostaining. However, amitriptyline significantly reduced F4/80 immunostaining. Furthermore, results showed that amitriptyline also attenuated atherosclerosis induced by HP-HFD plus LPS. To elucidate the underlying mechanisms, we found that amitriptyline downregulated proinflammatory cytokines by potently reducing sphingosine 1 phosphate, a bioactive sphingolipid. Taken together, this study showed that ASMase inhibition attenuated both NASH and atherogenesis induced by HP-HFD plus LPS and one of the mechanisms potentially involved in the attenuation is inhibition of S1P production. Disclosure Z. Lu: None. Y. Li: None. M.F. Lopes-Virella: None. Y. Huang: None. Funding U.S. Department of Veterans Affairs (1I01CX001825-01); National Institutes of Health

The risk for preeclampsia (PE) is increased 4-fold in women with type 1 diabetes (T1D), in whom we previously demonstrated that elevated cholesterol-rich lipoproteins confer risk at the 1st trimester. Sphingolipids, including ceramides (Cer) and glycosphingolipids (hexosyl- (HexCer) and lactosyl-ceramides (LacCer)), are lipoprotein constituents that regulate cell signaling. We propose that these bio-active lipids could be modulators of PE risk. In a prospective T1D pregnancy cohort (studied at 12, 22, 32 weeks’ gestation), we used liquid chromatography/electrospray ionization-tandem mass spectrometry to determine plasma levels of 12 species of Cer, HexCer, and LacCer in 23 women with T1DM who did vs. 24 who did not develop PE, and in 19 normotensive nondiabetic pregnant women. All were free of microalbuminuria and hypertension at enrolment; all visits preceded clinical PE onset. Results: Plasma levels of C22-Cer (1st and 3rd study visits); C26:1-Cer (1st and 2nd visits); C26-Cer (1st visit); C18-Cer and C18:1-Cer (2nd visit) were significantly higher in women with T1DM who did vs. did not develop PE. C22-Cer and C26-Cer were significantly lower in T1DM vs. non-T1DM (1st visit). There were no overall PE- or diabetes-related differences in any HexCer- or LacCer species. Longitudinally, most Cer and HexCer species increased throughout pregnancy in all groups (except C14- and C18-Cer; and C14 and C26-HexCer). C16-LacCer increased, while C22:1-, C26-, and C26:1-LacCer decreased as pregnancy advanced, independent of PE status. Independent of LDL-C, total Cer increased throughout pregnancy in all groups. Conclusions: Maternal Cer species may serve as early biomarkers for PE in women with T1DM. T1DM was associated with lower levels of two Cer species. Like cholesterol-rich lipoproteins, Cer, HexCer and some LacCer species increase as pregnancy advances in all groups, but other LacCer species decrease: the significance of these findings requires further study. Disclosure C.B. Kelly: None. S.M. Hammad: None. R.L. Klein: None. M.F. Lopes-Virella: None. M.J. Leyva: None. J. Yu: None. A.J. Jenkins: Advisory Panel; Self; Abbott, Australian Diabetes Society, Medtronic. Research Support; Self; Abbott, GlySens Incorporated, Medtronic, Mylan. Speaker's Bureau; Self; Eli Lilly and Company, Novo Nordisk Inc. A.J. Nankervis: None. K.F. Hanssen: None. S.K. Garg: Advisory Panel; Self; Eli Lilly and Company, Roche Pharma, Sanofi-Aventis, Zealand Pharma A/S. Research Support; Self; Eli Lilly and Company, WebMD. J.A. Scardo: None. C.E. Aston: None. T. Lyons: None. Funding JDRF; Novo Nordisk; National Institutes of Health

Preeclampsia (PE) occurs four times more frequently in pregnant women with type 1 diabetes (T1D) than in nondiabetic women. We hypothesized that elevated plasma advanced glycoxidation products (AGEs) predict PE in T1D women. In a prospective T1D pregnancy cohort (study visits at 12, 22, 32 weeks' gestation), we used liquid chromatography/mass spectrometry, with internal stable heavy isotope substituted standards, to determine plasma levels of nine AGE and oxidation products (carboxymethyl-lysine [CML], carboxyethyl-lysine [CEL], methylglyoxal-hydroimidazolone [MGHI], 3-deoxyglucosone hydroimidazolones [3DGH], methionine sulfoxide [MetSO], glyoxal hydroimidazolone [GHI], 3-nitrotyrosine [3NT], dityrosine [DT], 2-aminoadipic acid [2AAA]) in 23 women with T1DM who developed PE vs. 24 who did not, and in 19 nondiabetic normotensive pregnant women. These products have been associated with CVD and renal failure in non-pregnant cohorts. All women were free of microalbuminuria and hypertension at enrolment, and all visits preceded clinical PE onset. GFR was estimated (Chronic Kidney Disease Epidemiology Collaboration equation). Results: Plasma CML, CEL, MGHI, 3DGH, MetSO, GHI, and 2AAA did not differ between the three groups at any study visit, and thus did not predict preeclampsia in T1D. In T1D women who later developed PE, eGFR was inversely associated at V3 with CML (p=0.008), CEL (p=0.03), MGH1 (p=0.03), 3DGH (p=0.03), GHI (p Conclusions: Plasma AGEs did not predict PE in well-controlled, previously healthy T1D women, and levels did not differ from healthy nondiabetic controls. Uniquely, in T1D women who developed PE, plasma AGEs were associated with renal function, consistent with the notion that subclinical alterations in renal function precede PE. Disclosure H. Karanchi: None. C.B. Kelly: None. S.M. Hammad: None. R.L. Klein: None. M.F. Lopes-Virella: None. M.J. Leyva: None. J. Yu: None. A.J. Jenkins: Advisory Panel; Self; Abbott, Australian Diabetes Society, Medtronic. Research Support; Self; Abbott, GlySens Incorporated, Medtronic, Mylan. Speaker’s Bureau; Self; Eli Lilly and Company, Novo Nordisk Inc. A.J. Nankervis: None. K.F. Hanssen: None. C.E. Aston: None. S. Howell: Employee; Self; PreventAGE Health Care, LLC. P.J. Beisswenger: Other Relationship; Self; PreventAGE Health Care, LLC. T. Lyons: None.

The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study reported that intensive glucose control as assessed by hemoglobin A1c (HbA1c) reduced the risk of diabetic peripheral neuropathy (DPN) and cardiovascular autonomic neuropathy (CAN) in type 1 diabetes (T1D), with long lasting benefits. We evaluated additional clinical parameters and risk factors that could contribute to the development of DPN and CAN in this cohort. DPN was assessed at three different times and defined as a composite of symptoms, signs, and abnormal nerve conduction studies in ≥2 nerves; CAN was assessed seven different times and defined based on R-R variation, Valsalva maneuver, and postural changes in blood pressure. Generalized estimating equation models were used to evaluate the association of DPN and CAN with individual risk factors over repeated time points spanning 30 years. Among 1,441 DCCT/EDIC participants, 32% developed DPN and 44% developed CAN. Higher mean HbA1c was the most significant risk factor for DPN (OR=1.56 per 1%, 95% CI 1.41,1.72). DPN was also associated with older age (1.43 per 5 years, 95% CI 1.31,1.55), longer duration of T1D, higher albuminuria, β-blocker use, higher mean diastolic blood pressure, and higher HbA1c at DCCT eligibility. CAN was associated (in order) with older age (1.51 per 5 years, 95% CI 1.40,1.63), longer duration of T1D (1.07 per 1 year, 95% CI 1.05,1.10), any sustained microalbuminuria (AER ≥30 mg/24 hour on two consecutive visits), higher mean HbA1c, higher mean and current pulse rate (likely as an indirect measure of CAN), higher mean systolic blood pressure, β-blocker use, any eGFR Disclosure B. Braffett: None. R. Gubitosi-Klug: None. J.W. Albers: Consultant; Self; Eli Lilly and Company. E.L. Feldman: None. C. Martin: None. N.H. White: None. T.J. Orchard: Consultant; Self; Boehringer Ingelheim International GmbH. M.F. Lopes-Virella: None. P. Raskin: Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Gan & Lee Pharmaceuticals, Novo Nordisk A/S. R. Pop-Busui: Consultant; Self; Novo Nordisk A/S. Research Support; Self; AstraZeneca. Other Relationship; Self; American Diabetes Association. Funding Division of Diabetes Endocrinology & Metabolic Diseases (U01DK094176, U01DK094157); National Eye Institute; National Institute of Neurologic Disorders and Stroke; General Clinical Research Centers Program; Clinical Translational Science Center

Statin therapy reduces cardiovascular risk in type 2 diabetes (T2DM), partly by improving dyslipidemia, and partly through ‘pleiotropic’ effects. Sphingolipids, including ceramides, are amphiphilic components of lipoprotein surface monolayers. Sphingolipids regulate lipoprotein surface fluidity, and include key signaling molecules: ceramides are specifically associated with apoptosis and risk for premature coronary heart disease. Effects of statins on the sphingolipid content of lipoproteins are poorly defined. Using liquid chromatography/electrospray ionization-tandem mass spectrometry, we determined fasting plasma concentrations of individual ceramides (Cer), sphingomyelins (SM), and glycosphingolipids (hexosyl- and lactosyl-Cer) in plasma from 19 men and 21 women with T2DM, before and after treatment with rosuvastatin (10 mg/day, 6 weeks). Exclusion criteria were use of ‘statins’ in the preceding 6 months, and any current use of lipid-modifying agents. Using existing lipoprotein compositional data, we calculated effects of rosuvastatin therapy on non-HDL sphingolipid content. Results: Rosuvastatin reduced total cholesterol (C) (by 33%), triglycerides (20%), LDL-C (49%), and non-HDL particle number (34%); HDL-C was unaffected. It decreased total SM (15%), Cer (29%), and hexosyl- (30%) and lactosyl- (34%) Cer, independent of gender. Assuming HDL composition was unaffected, rosuvastatin reduced non-HDL SM by 42% and Cer by 61%: these reductions remained significant after correction for non-HDL-C and/or non-HDL lipoprotein surface area. Conclusions: In T2DM, rosuvastatin lowers not only the number of non-HDL particles, but also the sphingolipid, and especially the Cer, content of each particle. This effect is independent of gender, potentially anti-atherogenic, and may represent a new pleiotropic effect of statins. Further studies are needed to confirm these findings in isolated lipoprotein classes, and to determine mechanism(s). Disclosure C.B. Kelly: None. S.M. Hammad: None. R.L. Klein: None. M.F. Lopes-Virella: None. A. Gosmanova: None. M.J. Leyva: None. C.E. Aston: None. T. Lyons: None.

We hypothesize in diabetes that augmented activity of the plasma kallikrein-kinin system reflect and contribute to vascular damage and inflammations. Our objective was to determine the role of plasma PK as a predictor of cardiovascular events in type 2 diabetes in the VADT cohort. Levels of plasma total prekallikrein (PK) were measured in 604 VADT patients, a median of 1.5 years after entry into the study. Participants were followed an average of 4.1 years. Hazard ratios (HRs) for CV endpoints in relation to PK tertiles and having a non-zero versus zero value for plasma active kallikrein (PAK) were calculated by Cox proportional hazard models. During follow-up, 4.9% had an MI and 7.4% had an MI or cardiovascular death. Because there was evidence that minority status modified the associations between PK and outcomes of interest, but there was very limited power in minorities, results are presented in the total population adjusting for minority status and limited to the non-Hispanic white (NHW) population (Table). After adjustments by conventional risk factors, in NHW individuals the hazard ratio comparing the middle to lowest tertile of PK levels was 3.94 (95% CI: 1.09, 14.2) for MI and 3.45 (95% CI: 1.25, 9.48) for MI combined with cardiovascular death. Our study indicates that plasma PK levels predict MI and cardiovascular death in NHW patients with type 2 diabetes. Disclosure K.J. Hunt: None. M.A. Jaffa: None. M. Sohn: None. M.F. Lopes-Virella: None. A.A. Jaffa: None. Funding National Heart, Lung, and Blood Institute

We have previously shown that high levels of oxidized LDL and AGE-LDL in circulating IC are strong predictors of atherosclerosis progression in 518 subjects with type 1 diabetes from the DCCT/EDIC cohort. In this study we investigated whether oxLDL, MDA-LDL and AGE-LDL in circulating IC measured in the same subjects at DCCT baseline were associated with acute CVD events. Three overlapping CVD outcomes were considered: any CVD events, major adverse cardiac and cerebrovascular events (MACE) and myocardial infarction (MI). Cox proportional hazards models assessed the association between IC biomarker values and the subsequent risk of CVD, using inverse probability weighting to obtain results representative of the full DCCT/EDIC cohort. Results: Levels of AGE-LDL, oxLDL and MDA-LDL in circulating IC, measured at baseline (Table) were significantly associated with the 3 CVD outcomes in unadjusted models and were minimally attenuated after adjustment for age and mean HbA1c. After adjustments for conventional CVD risk factors, including LDL-Chol, high levels of oxLDL-IC and MDA-LDL-IC remained independently associated with increased subsequent risk of any CVD, and higher oxLDL-IC with increased risk of MACE and MI events. Conclusions: High levels of oxLDL-IC measured more than one decade prior to the occurrence of CVD events identified patients at high risk, even after adjustment by LDL-C and conventional CVD risk factors. Disclosure M.F. Lopes-Virella: None. I. Bebu: None. K.J. Hunt: None. G. Virella: None. N.L. Baker: None. B. Braffett: None. J. Lachin: Board Member; Self; Tolerion, Inc. Funding National Institute of Diabetes and Digestive and Kidney Diseases

Preeclampsia (PE), a major cause of maternal and fetal morbidity and mortality worldwide, has significantly higher incidence in women with type 1 diabetes mellitus (T1DM) than in nondiabetic populations (∼20% vs. 5%, respectively). Sphingolipids are key signaling molecules, and have many roles in the structure and regulation of cellular functions. Sphingomyelin (SM) is the most abundant sphingolipid in plasma lipoproteins. There is evidence that altered SM metabolism may contribute to cardiovascular and renal complications in diabetes. We aimed to determine whether plasma concentrations of 12 SM species were associated with PE in T1DM in a prospective study of pregnancy of 23 T1DM women who developed PE and 24 T1DM who remained normotensive. Additionally, 19 normotensive nondiabetic pregnant women were included for reference. All subjects were free of microalbuminuria and hypertension at enrolment, and all visits (12, 22, 32 weeks’ gestation) preceded clinical PE onset. Results: There were no cross-sectional differences in total SM, or in any individual SM species, between diabetic women with and without PE, or between normotensive women with and without diabetes at any stage of gestation. With advancing gestation in all groups, C18-SM, C18:1-SM, C20-SM, C20:1-SM, C22-SM, C22:1-SM, C24-SM, and C24:1-SM increased (all p Conclusions: With advancing gestation, plasma concentrations of most SM species increased, as did LDL and VLDL; however, two long-chain and two very long-chain SM species decreased. Although there were no differences in SM according to diabetes or PE status at any time point, further studies should address the significance of differential changes of SM species during pregnancy. Disclosure C.B. Kelly: None. S.M. Hammad: None. R.L. Klein: None. M.F. Lopes-Virella: None. M.J. Leyva: None. J. Yu: None. A.J. Jenkins: Advisory Panel; Self; Abbott, Australian Diabetes Society, Medtronic. Research Support; Self; Abbott, GlySens Incorporated, Medtronic, Mylan. Speaker's Bureau; Self; Eli Lilly and Company, Novo Nordisk Inc. A.J. Nankervis: None. K.F. Hanssen: None. S.K. Garg: Advisory Panel; Self; Eli Lilly and Company, Roche Pharma, Sanofi-Aventis, Zealand Pharma A/S. Research Support; Self; Eli Lilly and Company, WebMD. J.A. Scardo: None. C.E. Aston: None. T. Lyons: None. Funding JDRF; Novo Nordisk; National Institutes of Health

BACKGROUND: To determine if serum pigment epithelium-derived factor (PEDF) levels predict cardiovascular events, renal dysfunction and mortality in the Veterans Affairs Diabetes Study (VADT). METHODS: PEDF was evaluated in relation to subsequent cardiovascular outcomes, mortality, and renal dysfunction (defined as urinary albumin creatinine ratio (ACR) ≥300 mg/g), or chronic kidney disease (CKD) stages 3 (eGFR

We investigated whether the composition of modified forms of LDL in circulating immune complexes (LDL-ICs) was associated with cardiovascular disease (CVD) outcomes, including any CVD, major adverse cardiac and cerebrovascular events (MACCE), myocardial infarction (MI), and coronary artery disease, in type 1 diabetes (T1D). Our results demonstrate that the baseline levels of oxidized LDL (oxLDL), MDA-modified LDL (MDA-LDL), and advanced glycosylation–modified LDL (AGE-LDL) in circulating ICs were associated with the four CVD outcomes in unadjusted models, and adjustment by age and mean HbA1c only resulted in minimal reduction of these associations. After adjustments were made for other cardiovascular risk factors, particularly LDL cholesterol, oxLDL-IC and MDA-LDL-IC remained independently associated with the risk of CVD, and oxLDL-IC was independently associated with the risk of MACCE and MI. In the majority of cases, the baseline levels of modified LDL-IC (measured many years before the occurrence of any CVD event) were associated with the risk of CVD over a 25-year period even after adjustment for other risk factors (including LDL cholesterol). Therefore, modified LDL biomarkers may help identify patients with T1D at high risk for MACCE and CVD events very early in the evolution of the disease, before other signals of disease are apparent.

Plasma deoxy-sphingoid bases are elevated in type 2 diabetes patients and correlate with the stage of diabetic distal sensorimotor polyneuropathy; however, associations between deoxy-sphingolipids (DSL) and neuropathy in type 1 diabetes have not been examined. The primary aim of this exploratory pilot study was to assess the associations between multiple sphingolipid species including DSL and free amino acids and the presence of symptomatic neuropathy in a DCCT/EDIC type 1 diabetes subcohort. Using mass spectroscopy, plasma levels of DSL and free amino acids in DCCT/EDIC type 1 diabetes participants (n = 80), with and without symptoms of neuropathy, were investigated. Patient-determined neuropathy was based on 15-item self-administered questionnaire (Michigan Neuropathy Screening Instrument) developed to assess distal symmetrical peripheral neuropathy in diabetes. Patients who scored ≥4, or reported inability to sense their feet during walking or to distinguish hot from cold water while bathing were considered neuropathic. Plasma levels of ceramide, sphingomyelin, hexosyl- and lactosylceramide species, and amino acids were measured and analyzed relative to neuropathy status in the patient. Deoxy-C24-ceramide, C24- and C26-ceramide were higher in patients with neuropathy than those without neuropathy. Cysteine was higher in patients with neuropathy. No differences in other sphingolipids or amino acids were detected. The covariate-adjusted Odds Ratios of positive patient-reported neuropathy was associated with increased levels of deoxy-C24-, and deoxy-C24:1-ceramide; C22-, C24-, and C26-ceramide; and cysteine. Plasma deoxy-ceramide and ceramide species may have potential diagnostic and prognostic significance in diabetic neuropathy.

Risk factors for cardiovascular disease (CVD) are well-established in type 2 but not type 1 diabetes (T1DM). We assessed risk factors in the long-term (mean 27 years) follow-up of the Diabetes Control and Complications Trial (DCCT) cohort with T1DM. Cox proportional hazards multivariate models assessed the association of traditional and novel risk factors, including HbA1c, with major atherosclerotic cardiovascular events (MACE) (fatal or nonfatal myocardial infarction [MI] or stroke) and any-CVD (MACE plus confirmed angina, silent MI, revascularization, or congestive heart failure). Age and mean HbA1c were strongly associated with any-CVD and with MACE. For each percentage point increase in mean HbA1c, the risk for any-CVD and for MACE increased by 31 and 42%, respectively. CVD and MACE were associated with seven other conventional factors, such as blood pressure, lipids, and lack of ACE inhibitor use, but not with sex. The areas under the receiver operating characteristics curves for the association of age and HbA1c, taken together with any-CVD and for MACE, were 0.70 and 0.77, respectively, and for the final models, including all significant risk factors, were 0.75 and 0.82. Although many conventional CVD risk factors apply in T1DM, hyperglycemia is an important risk factor second only to age.

Our objective is to define differences in circulating lipoprotein subclasses between intensive versus conventional management of type 1 diabetes during the randomization phase of the Diabetes Control and Complications Trial (DCCT). NMR-determined lipoprotein subclass profiles (NMR-LSPs), which estimate molar subclass concentrations and mean particle diameters, were determined in 1,294 DCCT subjects after a median of 5 years (interquartile range: 4–6 years) of randomization to intensive or conventional diabetes management. In cross-sectional analyses, we compared standard lipids and NMR-LSPs between treatment groups. Standard total, LDL, and HDL cholesterol levels were similar between randomization groups, while triglyceride levels were lower in the intensively treated group. NMR-LSPs showed that intensive therapy was associated with larger LDL diameter (20.7 vs. 20.6 nm, P = 0.01) and lower levels of small LDL (median: 465 vs. 552 nmol/l, P = 0.007), total IDL/LDL (mean: 1,000 vs. 1,053 nmol/l, P = 0.01), and small HDL (mean: 17.3 vs. 18.6 ¼mol/l, P < 0.0001), the latter accounting for reduced total HDL (mean: 33.8 vs. 34.8 ¼mol/l, P = 0.01). In conclusion, intensive diabetes therapy was associated with potentially favorable changes in LDL and HDL subclasses in sera. Further research will determine whether these changes contribute to the beneficial effects of intensive diabetes management on vascular complications.

Dyslipidemia has been linked to vascular complications of Type 1 diabetes (T1DM). We investigated the prospective associations of nuclear magnetic resonance-determined lipoprotein subclass profiles (NMR-LSP) and conventional lipid profiles with carotid intima-media thickness (IMT) in T1DM.NMR-LSP and conventional lipids were measured in a subset of Diabetes Control and Complications Trial (DCCT) participants (n = 455) at study entry ('baseline', 1983-89), and were related to carotid IMT determined by ultrasonography during the observational follow-up of the DCCT, the Epidemiology of Diabetes Interventions and Complications (EDIC) study, at EDIC Year 12 (2004-2006). Associations were defined using multiple linear regression stratified by gender, and following adjustment for HbA1c, diabetes duration, body mass index, albuminuria, DCCT randomization group, smoking status, statin use, and ultrasound devices.In men, significant positive associations were observed between some baseline NMR-subclasses of LDL (total IDL/LDL and large LDL) and common and/or internal carotid IMT, and between conventional total- and LDL-cholesterol and non-HDL-cholesterol and common carotid IMT, at EDIC Year 12; these persisted in adjusted analyses (p0.05). Large LDL particles and conventional triglycerides were positively associated with common carotid IMT changes over 12 years (p0.05). Inverse associations of mean HDL diameter and large HDL concentrations, and positive associations of small LDL with common and/or internal carotid IMT (all p0.05) were found, but did not persist in adjusted analyses. No significant associations were observed in women.NMR-LSP-derived LDL particles, in addition to conventional lipid profiles, may help in identifying men with T1DM at highest risk for vascular disease.

The hypothesis that plasma prekallikrein (PK) is a risk factor for the development of vascular complications was assessed in a study using the Diabetes Control and Complications Trial (DCCT)/Epidemiology and Diabetes Interventions and Complications (EDIC) cohort of subjects with type 1 diabetes. The circulating levels of plasma PK activity were measured in the plasma of 636 subjects with type 1 diabetes (EDIC years 3–5). Common and internal carotid intima-media thickness (IMT) were measured by B-mode ultrasonography in EDIC years 1 and 6. Plasma PK levels were positively and significantly associated with BMI, hemoglobin A1c, systolic blood pressure, total cholesterol, LDL cholesterol, and triglycerides but not with age, sex, duration of diabetes, or HDL cholesterol. Univariate and multivariable statistical models after controlling for other risk factors consistently demonstrated a positive association between plasma PK and progression of internal carotid IMT. Multivariate analysis using a general linear model showed plasma PK to be significantly associated with progression of both internal and combined IMT (Wilks Λ P value of 0.005). In addition, the mean internal carotid IMT levels were higher in subjects with plasma PK levels in the highest 10th percentile compared with subjects with plasma PK levels in the lower 10th percentile (P = 0.048). These novel findings implicate plasma PK as a risk factor for vascular disease in type 1 diabetes.

Background Glycosphingolipids are important components of cell membranes, modulators of cell-cell interactions and cell recognition, and have recently emerged as bioactive molecules and important players in nearly all cell biological processes. We previously have shown that decreased plasma levels of long and very long species of ceramides were able to predict the development of macroalbuminuria (MA) in type 1 diabetes. Objective This study proposed to examine whether plasma glycosphingolipids could predict development of diabetic nephropathy, assessed as MA or chronic kidney disease (CKD). Methods Measurement of plasma hexosylceramides (H) and lactosylceramides (L) were conducted in the Lipidomics Core Facility of our Institution in a subcohort of 432 patients from the DCCT/Epidemiology of Diabetes Interventions and Complications cohort in plasma collected at entry into the study. Inverse probability weighted Cox proportional hazards regression models were used to assess the effect of glycosphingolipids levels on the risk of developing MA (albumin excretion rate ≥300 mg/24 hours) or CKD (glomerular filtration rate Results Decreases of several long and very long chain lactosylceramides were significantly associated with increased risk of progression to MA but not CKD. Among the hexosylceramides, the only significant association observed was between one of its minor species C18:1–H and CKD. Conclusion Our findings showed that decreased levels of long and very long lactosylceramides were able to predict the development of MA in type 1 diabetes. This finding is similar to previous findings showing that low levels of long and very long ceramides were also able to predict development of MA in the same cohort. Further studies are needed to determine the changes in sphingolipid metabolism leading to the development of complications.

APOB, APOC3, and APOE and apolipoprotein-defined lipoprotein subclasses (ADLSs; based on qualitative apolipoprotein complement) have been associated with dyslipidemia and CVD. Our main objective was to define associations of serum apolipoproteins and ADLSs with "any CVD" and "major atherosclerotic cardiovascular events" (MACEs) in a prospective study of T1D. Serum apolipoproteins and ADLSs (14 biomarkers in total) were measured in sera (obtained between 1997 and 2000) from a subset (n = 465) of the Epidemiology of Diabetes Interventions and Complications cohort. Prospective associations of "any CVD" (myocardial infarction, stroke, confirmed angina, silent myocardial infarction, revascularization, or congestive heart failure) and MACEs (fatal or nonfatal myocardial infarction or stroke), over 5,943 and 6,180 patient-years follow-up, respectively, were investigated using Cox proportional hazards models that were unadjusted and adjusted for risk factors. During 15 years of follow-up, 50 "any CVD" events and 24 MACEs occurred. Nominally significant positive univariate associations with "any CVD" were APOB, APOC3 and its subfractions [heparin precipitate, heparin-soluble (HS)], and ADLS-defined Lp-B. In adjusted analyses, APOC3-HS remained nominally significant. Nominally significant positive univariate associations with MACEs were APOC3 and its subfractions and Lp-B:C; those with total APOC3 and APOC3-HS persisted in adjusted analyses. However, these associations did not reach significance after adjusting for multiple testing. There were no significant associations of APOA1, APOA2, APOE, or other ADLSs with either "any CVD" or MACEs. These hypothesis-generating data suggest that total serum APOC3 and APOC3 in HDL are potentially important predictive biomarkers for any CVD and MACEs in adults with T1D.

An elevation of serum inflammatory biomarkers in achalasia patients compared with controls recently was demonstrated. It has not been determined whether the elevation of inflammatory cytokines is unique to achalasia or occurs with other diseases involving the esophagus. The primary aim of our study was to compare the differences in plasma immunological profiles (TNF- α receptor, IL-6, IFN-γ, IL-12, IL-17, IL-22, and IL-23) of patients with achalasia, eosinophilic esophagitis (EoE), and gastroesophageal reflux disease (GERD). A secondary aim of this study was to classify these same plasma cytokine profiles in the three achalasia subtypes. Methods Plasma from 53 patients with achalasia, 22 with EoE, and 20 with GERD (symptoms plus esophagitis or + reflux study) were analyzed. Exclusion criteria: malignancy, autoimmune condition, immunodeficiency disorder, and treatment with steroids/immune modulating drugs. Cytokine levels were assayed via multiplex enzyme-linked immunosorbent assay (ELISA). Results Our key finding revealed significant elevations in IL- 6 (p = 0.0158) in achalasia patients compared with EoE patients. Overall, plasma inflammatory biomarker patterns were not different in the three subtypes of achalasia. Conclusion There were no differences between the cytokine levels of any of the measured biomarkers between the achalasia and GERD groups suggesting that luminal stasis does increase biomarker levels for any of the cytokines examined in our study. While these results are an early first step towards clarifying some aspects of the pathogenesis of achalasia, they bring about many more questions that require further investigation and expansion. Further investigation with a larger cohort and a broader panel of biomarkers is needed.

Connective tissue growth factor (CTGF) is a member of the CCN family of matricellular proteins that has been implicated in the inflammatory process, response to injury and wound healing. An emerging role of CTGF is that of a profibrotic factor implicated in the development of kidney disease. Our objective was to determine the role of CTGF as a predictor of macroalbuminuria (ACR ≥300µg/mg twice) and chronic kidney disease (CKD) stage 3 (GFR Disclosure K.J. Hunt: None. M.A. Jaffa: None. S.M. Garrett: None. D.K. Luttrell: None. K.E. Lipson: Employee; Self; FibroGen, Inc.. Stock/Shareholder; Self; AbbVie Inc., Abbott, Becton, Dickinson and Company, Bristol-Myers Squibb Company, General Electric, Gilead Sciences, Inc., Medtronic, Nestlé, Novartis AG, Oracle, Pfizer Inc., Quest Diagnostics. Consultant; Spouse/Partner; Diabesen. M.F. Lopes-Virella: None. L.M. Luttrell: None. A.A. Jaffa: None.

There is considerable interest in identifying biomarkers indicative of plaque instability and acute events. Previously we reported that MDA-LDL in circulating immune complex predicted acute myocardial infarction (MI) in the VADT study. Interleukin (IL)-6, Fas Ligand, tissue inhibitor of MMP (TIMP)-1 and monocyte chemotactic protein (MCP)-1 have been identified as potentially clinically relevant biomarkers related to plaque instability. Therefore, our objective was to examine the role of these biomarkers in conjunction with MDA-LDL in circulating immune complex as predictors of acute MI in type 2 diabetes. Biomarker levels were measured in 833 VADT patients, a median of 2.0 years after study entry and participants were subsequently followed a median of 3.7 years. Biomarkers were examined individually and as composite scores created by summing z scores across biomarkers. Hazard ratios (HRs) for acute MI were calculated by Cox proportional hazard models. During follow-up, 5.2% had an MI. After adjustment for conventional risk factors, results of composite biomarkers scores were promising with a hazard ratio for acute MI of 4.65 (95% CI: 1.56, 13.9) comparing the fourth to first quartile of our summary composite score which included MDA-LDL-IC, IL-6, Fas Ligand,TIMP-1 and MCP-1 (Table). Disclosure M.F.L. Lopes-Virella: None. K.J. Hunt: None. R. Agarwal: None. N.L. Baker: Research Support; Self; Bristol-Myers Squibb Company. G. Virella: None.

Background: Serum uric acid (UA) is associated with the pathogenesis of diabetes complications, including cardiovascular disease (CVD) and kidney injury. Current epidemiological evidence is limited regarding the association between UA and the development of CVD in type 1 diabetes mellitus (T1DM). Objective: To examine associations of serum UA with CVD and major atherosclerotic cardiovascular events (MACE) in T1DM. Methods: UA was measured in sera (1997-2000) from a subset of participants (n=973; males=540, females=433) in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study. Subsequent CVD events were adjudicated by a review committee masked to DCCT assignment and HbA1c levels, and defined as the time to the first of any of the following: non-fatal myocardial infarction (MI) or stroke, CVD death, silent MI on annual ECG, angina confirmed by ischemic changes with exercise tolerance testing, congestive heart failure, or revascularization; MACE were defined as a composite of CVD death, nonfatal MI, or stroke. Cox proportional hazards models were used to evaluate prospectively the effect of UA as a fixed covariate on CVD and MACE, separately by gender, and adjusted for age and HbA1c. Results: Over 15 years follow-up, there were 201 adjudicated CVD events among 110 participants (HR=1.10 per 1 mg/dl change in UA, 95% CI 0.93-1.30); 61 males experienced 96 events (HR=1.15, 95% CI 0.90-1.46) and 49 females, 105 events (HR=1.17, 95% CI 0.88-1.56). There were 62 adjudicated MACE among 53 participants (HR=1.18, 95% CI 0.93-1.49); 29 males experienced 31 events (HR=1.10, 95% CI 0.77-1.58) and 24 females, 31 events (HR=1.47, 95% CI 1.01-2.14). No significant associations between quartiles of UA and either CVD or MACE were observed in either sex. Conclusions: Our results show UA may not serve as a predictive biomarker for CVD events in T1DM adults. Sex-specific associations with MACE deserve further investigation. Disclosure A. Basu: None. B. Braffett: None. A. Jenkins: Research Support; Self; Medtronic, Mylan, Sanofi-Aventis. I. Bebu: None. R.L. Klein: None. M.F. Lopes-Virella: None. S. Dagogo-Jack: None. T.J. Orchard: None. A. Wallia: Research Support; Self; UnitedHealth Group. Consultant; Self; Glytec Systems, Lexicon Pharmaceuticals, Inc.. Research Support; Self; Eli Lilly and Company. J. Lachin: Board Member; Self; AbbVie Inc., Celgene Corporation. W. Garvey: Advisory Panel; Self; Novo Nordisk Inc., Merck & Co., Inc.. Research Support; Self; Sanofi, Pfizer Inc., Novo Nordisk Inc., AstraZeneca, Merck & Co., Inc., Elcelyx Therapeutics, Inc., Lexicon Pharmaceuticals, Inc., Eisai Inc.. T. Lyons: None.

Background: Apolipoproteins Apo-B, Apo-C-III, and Apo-E are atherogenic and are associated with diabetic dyslipidemia and cardiovascular disease (CVD). Apolipoprotein-defined lipoprotein subclasses (ADLS) also show associations with CVD, but prospective associations of these detailed metrics with CVD in people with type 1 diabetes (T1DM) have not been explored. Objective: Prospective associations of serum apolipoproteins and ADLS with CVD and major atherosclerotic cardiovascular events (MACE: composite of CVD death, nonfatal myocardial infraction or nonfatal stroke) in T1DM. Methods: Serum apolipoproteins and ADLS (14 biomarkers in total) measured in sera (1997-2000) in a subset (n=465) of the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications cohort. Prospective associations of CVD and MACE over 5942 and 6180 patient-years follow-up, respectively, were investigated using Cox proportional hazards models unadjusted and adjusted for risk factors. Results: During 15 years follow-up, 50 CVD and 24 MACE events occurred. Significant positive univariate associations for CVD were: Lp-B, Apo-B, Apo-C-III (total, heparin precipitate (HP), i.e., Apo-C-III in VLDL, and heparin soluble (HS), i.e., Apo-C-III in HDL) and Lp-B:C; for MACE: Apo-C-III sub fractions (total, Apo-C-III-HP, and Apo-C-III-HS). Adjusting for sex, age, HbA1c, systolic blood pressure, pulse rate, LDL-cholesterol, and triglycerides: for CVD, Apo-C-III-HS remained significant (HR (95% CI): 1.18 (1.03, 1.35); P=0.01). For MACE, total Apo-C-III and Apo-C-III-HS persisted when adjusted for age, HbA1c and LDL [1.11 (1.01, 1.22); P=0.02, and 1.22 (1.02, 1.45); P=0.02, respectively], but not for age, HbA1c and (log) triglycerides. No significant associations of other ADLS, Apo-A-I, A-II and Apo-E with CVD/MACE were observed. Conclusions: Total serum Apo-C-III and Apo-C-III in HDL and Apo-B-containing lipoproteins may serve as predictive biomarkers for CVD events in T1DM adults. Disclosure A. Basu: None. I. Bebu: None. A. Jenkins: Research Support; Self; Medtronic, Mylan, Sanofi-Aventis. J. Stoner: None. Y. Zhang: None. R.L. Klein: None. M.F. Lopes-Virella: None. W. Garvey: Advisory Panel; Self; Novo Nordisk Inc., Merck & Co., Inc.. Research Support; Self; Sanofi, Pfizer Inc., Novo Nordisk Inc., AstraZeneca, Merck & Co., Inc., Elcelyx Therapeutics, Inc., Lexicon Pharmaceuticals, Inc., Eisai Inc. M. Budoff: Speaker's Bureau; Self; Janssen Pharmaceuticals, Inc., Boehringer Ingelheim Pharmaceuticals, Inc., Amarin Corporation. T. Lyons: None.

OBJECTIVE There is considerable interest in identifying biomarkers that predict high risk for the development of macrovascular complications in patients with diabetes. Therefore, the longitudinal association between subclinical atherosclerosis as measured by internal carotid artery intima-media thickness (IMT) and acute-phase reactants, cytokines/adipokines, thrombosis, and adhesion molecules was examined. RESEARCH DESIGN AND METHODS Biomarkers were measured at four time points over 20 years in 886 DCCT/EDIC participants with type 1 diabetes. Four composite scores were created by combining z scores generated from within the data set of individual biomarkers: acute-phase reactants (fibrinogen, C-reactive protein), thrombosis (fibrinogen, active and total plasminogen activator inhibitor [PAI]-1), cytokines/adipokines (tumor necrosis factor receptor-1 and -2, active and total PAI-1, IL-6), and endothelial dysfunction (soluble intracellular adhesion molecule-1, soluble vascular cell adhesion molecule-1, and soluble E-selectin). Internal carotid IMT was measured at EDIC years 1, 6, and 12, with elevated IMT defined at each time point as being in the upper quintile of its distribution. RESULTS Logistic regression models indicate that while individual biomarkers were not predictive of or associated with subclinical atherosclerosis, composite scores of acute-phase reactants (odds ratio [OR] 2.78 [95% CI 1.42, 5.42]), thrombolytic factors (OR 2.83 [95% CI 1.45, 5.52]), and cytokines/adipokines (OR 2.83 [95% CI 1.48, 5.41]) measured at our final time point EDIC years 8–11 were associated with higher levels of atherosclerosis at EDIC year 12, but findings were not consistent at early time points. The endothelial dysfunction score was not appreciably predictive of or associated with subclinical atherosclerosis at any of the time points measured. CONCLUSIONS The pathophysiologic relationship between higher biomarker levels and progression of subclinical atherosclerosis remains unclear.

Aims This study was undertaken to determine whether levels of inflammation and endothelial dysfunction biomarkers in serum samples collected at baseline in the Diabetes Control and Complications Trial (DCCT) cohort could predict the development of retinopathy. Methods Levels of clotting/fibrinolysis, inflammation and endothelial dysfunction biomarkers were measured in 1391 subjects with type 1 diabetes to determine whether their levels predicted increased risk to develop or accelerate progression of retinopathy during 16 years of follow-up. Results Using regression models adjusted for DCCT treatment group, duration of diabetes, baseline retinopathy scores, HbA1c and albumin excretion rate, the baseline levels of sE-selectin and PAI-1 (active) were significantly associated with increased risk of a 3-step progression in retinopathy score in the primary prevention cohort (PPC). After adjusting for additional covariates (e.g., ACE/ARB and statin therapy), this association persisted. Levels of active and total PAI-1 in the same group were also significantly associated, after similar adjustments, with the time to progress to severe non-proliferative retinopathy during the follow-up period (54 and 29%, respectively of increased risk). No associations were observed in the secondary intervention cohort for any of the outcomes. Conclusions High levels of sE-selectin and PAI-1 are associated with the development of retinopathy in patients with uncomplicated type 1 diabetes.

Background: High-resolution MRI (HRMRI) is a promising tool for studying intracranial atherosclerotic disease (ICAD) in-vivo, but its use to understand the pathophysiology of ICAD has been limited by a lack of correlation between MRI signal characteristics and pathology in intracranial arteries. Description of case: A patient with symptomatic left cavernous carotid stenosis underwent 3T HRMRI and died 4 days later. In-vivo HRMRI and postmortem histopathology images were compared. MRI signal characteristics consistent with atherosclerotic plaque composed of lipid and loose matrix, fibrous tissue, and calcium were correlated with pathology findings. Intraplaque hemorrhage was not present on HRMRI or pathology. Conclusions: This report demonstrates correlation between atherosclerotic plaque components visualized on 3T HRMRI images obtained in-vivo and pathological specimens of a symptomatic ICAD plaque, providing an important step in developing HRMRI as an in-vivo research tool to understand ICAD pathology.

OBJECTIVE To determine whether biomarkers of inflammation and endothelial dysfunction are associated with the development of kidney dysfunction and the time frame of their association. RESEARCH DESIGN AND METHODS Biomarkers were measured at four time points during 28 years of treatment and follow-up in patients with type 1 diabetes in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) cohort. In addition to traditional biomarkers of inflammation (C-reactive protein and fibrinogen), we measured interleukin-6 (IL-6) and soluble tumor necrosis factor receptors 1 and 2 (sTNFR-1/2), markers of endothelial dysfunction (soluble intracellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin [sE-selectin]), and fibrinolysis (total and active plasminogen activator inhibitor-1 [PAI-1]). Renal outcomes were defined as progression to incident chronic kidney disease (stage 3 or more severe) or macroalbuminuria (albumin excretion rate ≥300 mg/24 h). Prospective multivariate event-time analyses were used to determine the association of each biomarker with each subsequent event within prespecified intervals (3-year and 10-year windows). RESULTS Multivariate event-time models indicated that several markers of inflammation (sTNFR-1/2), endothelial dysfunction (sE-selectin), and clotting/fibrinolysis (fibrinogen and PAI-1) are significantly associated with subsequent development of kidney dysfunction. Although some markers showed variations in the associations between the follow-up windows examined, the results indicate that biomarkers (sTNFR-1/2, sE-selectin, PAI-1, and fibrinogen) are associated with progression to chronic kidney disease in both the 3-year and the 10-year windows. CONCLUSIONS Plasma markers of inflammation, endothelial dysfunction, and clotting/fibrinolysis are associated with progression to kidney dysfunction in type 1 diabetes during both short-term and long-term follow-up.

Immune complexes (IC) containing predominantly malondialdehyde-LDL and the corresponding autoantibodies (MDA-LDL IC) predict acute cardiovascular events, while IC rich in oxidized LDL (oxLDL IC) predict cardiovascular disease progression. Our objective was to determine mechanisms that could explain these prognostic differences. We compared the effects of the interaction of oxLDL, MDA-LDL and the corresponding IC with human macrophages focusing on apoptosis, metalloproteinases, and proinflammatory cytokines. MDA-LDL IC induced higher degrees of apoptosis, higher levels of caspase-3 expression, and increased expression and release of MMP-1 and TNF compared to MDA-LDL, oxLDL, and oxLDL IC. The pro-apoptotic effects of MDA-LDL IC were inhibited by blocking TNFR 1 or FcγRI. Blocking FcγRI abrogated the induction and expression of MMPs and proinflammatory cytokines by MDA-LDL IC. In conclusion, the interaction of MDA-LDL IC with FcγRI triggers macrophage apoptosis and increased expression and release of TNF and MMP-1, which can lead to the rupture of unstable plaques.

Background We reported that high-fat diet (HFD)-induced metabolic syndrome (MetS) exacerbates lipopolysaccharide (LPS)-stimulated periodontitis and palmitate, the major saturated fatty acid in the HFD, amplified LPS-stimulated gene expression in vitro. Since CD36 is a major receptor for fatty acids, we investigated periodontal CD36 expression in mice with periodontitis and MetS, and the role of CD36 in inflammatory genes in macrophages stimulated by palmitate. Methods MetS and periodontitis were induced in mice by HFD and periodontal injection of LPS, respectively. The periodontal CD36 expression and its relationship with alveolar bone loss were studied using immunohistochemistry, real-time PCR, and correlation analysis. The role of CD36 in upregulation of inflammatory mediators by LPS and palmitate in macrophages was assessed using pharmacological inhibitor and small interfering RNA. Results Periodontal CD36 expression was higher in mice with both MetS and periodontitis than that in mice with periodontitis or MetS alone and was correlated with osteoclastogenesis and alveolar bone loss. In vitro studies showed that CD36 expression in macrophages was upregulated by LPS and palmitate, and targeting CD36 attenuated palmitate-enhanced gene expression. Conclusion CD36 expression is upregulated in mice with periodontitis and MetS, and involved in gene expression in macrophages stimulated by palmitate and LPS. This article is protected by copyright. All rights reserved.

Plasma total homocysteine (tHcy) has been positively associated with carotid intima-media thickness (IMT) in non-diabetic populations and in a few cross-sectional studies of diabetic patients. We investigated cross-sectional and prospective associations of a single measure of tHcy with common and internal carotid IMT over a 6-year period in type 1 diabetes.tHcy levels were measured once, in plasma obtained in 1997-1999 from patients (n = 599) in the Epidemiology of Diabetes Interventions and Complications (EDIC) study, the observational follow-up of the Diabetes Control and Complications Trial (DCCT). Common and internal carotid IMT were determined twice, in EDIC "Year 6" (1998-2000) and "Year 12" (2004-2006), using B-mode ultra-sonography.After adjustment, plasma tHcy [median (interquartile range): 6.2 (5.1, 7.5) μmol/L] was significantly correlated with age, diastolic blood pressure, renal dysfunction, and smoking (all p 0.05). In an unadjusted model only, increasing quartiles of tHcy correlated with common and internal carotid IMT, again at both EDIC time-points (p 0.01). However, multivariate logistic regression revealed no significant associations between increasing quartiles of tHcy and the 6-year change in common and internal carotid IMT (highest vs. lowest quintile) when adjusted for conventional risk factors.In a type 1 diabetes cohort from the EDIC study, plasma tHcy measured in samples drawn in 1997-1999 was associated with measures of common and internal carotid IMT measured both one and seven years later, but not with IMT progression between the two time-points. The data do not support routine measurement of tHcy in people with Type 1 diabetes.

Recently it has been shown that levels of circulating oxidized LDL immune complexes (ox-LDL-ICs) predict the development of diabetic retinopathy (DR). This study aimed to investigate whether ox-LDL-ICs are actually present in the diabetic retina, and to define their effects on human retinal pericytes versus ox-LDL. In retinal sections from people with type 2 diabetes, costaining for ox-LDL and IgG was present, proportionate to DR severity, and detectable even in the absence of clinical DR. In contrast, no such staining was observed in retinas from nondiabetic subjects. In vitro, human retinal pericytes were treated with native LDL, ox-LDL, and ox-LDL-IC (0–200 mg protein/l), and measures of viability, receptor expression, apoptosis, endoplasmic reticulum (ER) and oxidative stresses, and cytokine secretion were evaluated. Ox-LDL-IC exhibited greater cytotoxicity than ox-LDL toward retinal pericytes. Acting through the scavenger (CD36) and IgG (CD64) receptors, low concentrations of ox-LDL-IC triggered apoptosis mediated by oxidative and ER stresses, and enhanced inflammatory cytokine secretion. The data suggest that IC formation in the diabetic retina enhances the injurious effects of ox-LDL. These findings offer new insights into pathogenic mechanisms of DR, and may lead to new preventive measures and treatments.

Aims Dyslipoproteinemia has been associated with nephropathy in diabetes, with stronger correlations in men than in women. We aimed to characterize and compare plasma lipoprotein profiles associated with normal and increased albuminuria in men and women using apolipoprotein-defined lipoprotein subclasses and simple apolipoprotein measures. Methods This is a cross-sectional study in a subset (154 women and 282 men) of the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) cohort, using samples obtained in 1997–9. Immunochemical methods were used to quantify plasma apolipoprotein-based lipoprotein subclasses and individual apolipoprotein levels. Results In adjusted analyses, elevated Lipoprotein-B (Lp-B) was significantly associated with macroalbuminuria in men [odds ratios (OR) and 95% confidence interval (CI): 2.13 (1.15–3.97)] and women [3.01 (1.11–8.12)], while association with Lp-B:C was observed only in men [1.84 (1.19–2.86)]. For individual apolipoproteins the following significant associations with macroalbuminuria were observed in men only: Apolipoprotein B (ApoB) [1.97 (1.20–3.25)], Apo-AII [0.52 (0.29–0.93)], ApoC-III [1.95 (1.16–3.30)], “ApoC-III in VLDL” (heparin–manganese precipitate) [1.88 (1.16–3.04)], and “ApoCIII in HDL” (heparin–manganese supernatant) [2.03 (1.27–3.26)], all P Conclusions Atherogenic apolipoprotein-based profiles are associated with nephropathy in Type 1 diabetic men and to a lesser extent in women. The difference could result from the greater prevalence and severity of dyslipoproteinemia, and from the greater prevalence of renal dysfunction, in men vs women.

OBJECTIVE The current study aimed to determine in the Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications cohort whether or not abnormal levels of markers of inflammation and endothelial dysfunction measured in samples collected at DCCT baseline were able to predict the development of macroalbuminuria. RESEARCH DESIGN AND METHODS Levels of inflammation and endothelial cell dysfunction biomarkers were measured in 1,237 of 1,441 patients enrolled in the DCCT study who were both free of albuminuria and cardiovascular disease at baseline. To test the association of log-transformed biomarkers with albuminuria, generalized logistic regression models were used to quantify the association of increased levels of biomarkers and development of abnormal albuminuria. Normal, micro-, and macroalbuminuria were the outcomes of interest. RESULTS In the logistic regression models adjusted by DCCT treatment assignment, baseline albumin excretion rate, and use of ACE/angiotensin receptor blocker drugs, one unit increase in the standardized levels of soluble E-selectin (sE-selectin) was associated with an 87% increase in the odds to develop macroalbuminuria and one unit increase in the levels of interleukin-6 (IL-6), plasminogen activator inhibitor 1 (PAI-1; total and active), and soluble tumor necrosis factor receptors (TNFR)-1 and -2 lead to a 30–50% increase in the odds to develop macroalbuminuria. Following adjustment for DCCT baseline retinopathy status, age, sex, HbA1c, and duration of diabetes, significant associations remained for sE-selectin and TNFR-1 and -2 but not for IL-6 or PAI-1. CONCLUSIONS Our study indicates that high levels of inflammatory markers, mainly E-selectin and sTNRF-1 and -2, are important predictors of macroalbuminuria in patients with type 1 diabetes.

Our group has carried out pivotal clinical studies on large cohorts of type 1 and type 2 diabetes to determine the impact of modified LDL-IC as well as inflammatory cytokines/adipokines and acute-phase reactant proteins in the development of diabetic complications. We have demonstrated that high levels of specific LDL modifications in circulating ICs correlate with increased risk for the development and progression of macrovascular disease, nephropathy, and retinopathy, frequently exceeding conventional risk factors in their predictive power. In cardiovascular disease, differences in the type of LDL modification and the stage of disease seem to lead to/predict different outcomes. The differences observed with ICs containing different types of modified LDL raises interesting questions about the role of the predominant LDL modification in the ICs and the cellular patterns of macrophage activation, survival, and apoptosis that result from LDL-IC ingestion. The differences observed in the predictive power of modified LDL-ICs at different stages of CVD development strongly suggest that modified LDL-ICs are causally related with the development of atherosclerosis and/or plaque instability. The association of cytokines/adipokines and acute-phase reactant proteins with the development of complications in type 1 diabetes is less strong than that observed with modified LDL-ICs and occurs at a later phase of the development of complications. In conclusion, the human humoral autoimmune response to modified forms of LDL is a typical adaptive response, with a switch to IgG synthesis and increasing antibody affinity that leads to the release of proinflammatory mediators, and it has unquestionable pathogenic characteristics.

Considerable evidence is available supporting the atherogenic role of immune complexes (IC) formed by modified forms of LDL and their corresponding antibodies in humans and other species. In this study, we assessed the effect of IgG F(ab')

Aims/hypothesis Haptoglobin(Hp) 2–2 genotype has been shown to increase coronary artery disease (CAD) risk in numerous type 2 diabetes studies but in only one type 1 diabetes cohort. We assessed the association of Hp2–2 with incident CAD over 26 years of follow-up in 1303 Caucasian participants of the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study. Methods DCCT randomized volunteers with type 1 diabetes to intensive versus conventional therapy within two cohorts: ‘primary prevention’ with 1–5 years diabetes duration and ‘secondary intervention’ with 1–15 years diabetes duration and early retinopathy, with or without albuminuria, but no advanced complications. CAD was defined as myocardial infarction (MI) or death judged to be from CAD, silent MI, angina, coronary revascularization, or congestive heart failure due to CAD. Results In the entire DCCTcohort, Hp2–2 was not significantly associated with incident CAD or MI. However, in pre-specified exploratory subgroup analyses, an increased MI risk was suggested in the secondary cohort for those with Hp2–2. Conclusions/interpretation The analysis does not statistically confirm an overall association between Hp 2–2 and incident CAD, however, some suggestions of associations were observed in secondary analyses.

Type 1 diabetes (T1DM) is associated with increased risk of macrovascular complications. We examined longitudinal associations of serum conventional lipids and nuclear magnetic resonance (NMR)-determined lipoprotein subclasses with carotid intima-media thickness (IMT) in adults with T1DM (n=455) enrolled in the Diabetes Control and Complications Trial (DCCT). Data on serum lipids and lipoproteins were collected at DCCT baseline (1983–89) and were correlated with common and internal carotid IMT determined by ultrasonography during the observational follow-up of the DCCT, the Epidemiology of Diabetes Interventions and Complications (EDIC) study, at EDIC ‘Year 1’ (199–1996) and EDIC ‘Year 6’ (1998–2000). This article contains data on the associations of DCCT baseline lipoprotein profiles (NMR-based VLDL & chylomicrons, IDL/LDL and HDL subclasses and ‘conventional’ total, LDL-, HDL-, non-HDL-cholesterol and triglycerides) with carotid IMT at EDIC Years 1 and 6, stratified by gender. The data are supplemental to our original research article describing detailed associations of DCCT baseline lipids and lipoprotein profiles with EDIC Year 12 carotid IMT (Basu et al. in press) [1]. Keywords: Lipids and lipoproteins, Carotid intima-media thickness, Type 1 diabetes

Objective Circulating immune complexes (IC) containing modified forms of LDL (mLDL) are strongly pro-inflammatory and strong predictors of cardiovascular disease (CVD) progression in type 1 diabetes. The present study was undertaken to determine whether the levels of oxidized LDL (oxLDL), malondialdehyde-LDL (MDA-LDL) and advanced glycation end products-LDL (AGE-LDL) in IC predict incident CVD events in type 2 diabetes (VADT cohort). Methods and results Levels of mLDL in IC were measured in 907 patients of the VADT cohort, a median of two years after entry into the study. Participants were followed for an average of 3.7 years for vascular outcomes. Hazard ratios (HRs) for CV endpoints in relation to mLDL-IC quartiles were calculated by Cox proportional hazard models. The primary composite CVD endpoint included documented myocardial infarction (MI); stroke; death from CVD; congestive heart failure; cardiac, cerebrovascular, or peripheral VD surgical intervention; inoperable CVD; and amputation for ischemic gangrene. During follow-up, 4.7% and 16.8% of participants had an MI or a composite endpoint, respectively. After adjustments by conventional risk factors, individuals in the highest quartile of MDA-LDL-IC were at higher risk of MI [HR = 2.44 (95% CI: 1.03, 5.77)] and composite endpoint [HR = 1.71 (95% CI: 1.04, 2.80)], relative to individuals in the lowest quartile. Similar comparisons for oxLDL and AGE-LDL levels yielded HR values of 1.08 and 1.31 for MI and 0.91 and 1.34 for composite endpoint. Conclusions Our study indicates that high levels of MDA-LDL in isolated IC predict future MI and acute CV events in patients with type 2 diabetes.

Objective— It is known that toll-like receptor 4 (TLR4) plays an important role in atherosclerosis. Because both microvascular (MIC) and macrovascular (MAC) endothelial cells (ECs) are present in atherosclerotic lesions, the present study compared TLR4-triggered inflammatory response and cross talk with mononuclear cells between MIC and MAC ECs. Methods and Results— ELISA, real-time polymerase chain reaction, and gene expression profiling showed that TLR4 activation by lipopolysaccharide stimulated a much higher expression of inflammatory genes including cytokines, chemokines, growth factors, and adhesion molecules in MIC ECs than MAC ECs. Furthermore, coculture studies showed that TLR4 activation in MIC ECs, but not MAC ECs, induced a cross talk with U937 mononuclear cells through MIC EC-released interleukin-6 to upregulate matrix metalloproteinase-1 expression in U937 cells. To explore molecular mechanisms underlying the different responses to TLR4 activation between MIC and MAC ECs, we showed that MIC ECs had a higher expression of TLR4 and CD14 and a higher TLR4-mediated nuclear factor-kappaB activity than MAC ECs. Conclusion— The present study showed that TLR4 activation triggers a more robust inflammatory response in MIC ECs than MAC ECs. Given the importance of inflammatory cytokines and matrix metalloproteinases in plaque rupture, MIC ECs may play a key role in plaque destabilization through a TLR4-dependent mechanism.

To reduce connective tissue IL-6 level stimulated by LPS, it is essential to control IL-6 expression in both mononuclear cells and fibroblasts. However, it is unclear whether the regulatory mechanisms for both cells are similar or not. In this study, we found that signaling pathways mediating LPS-stimulated IL-6 in mononuclear U937 cells and fibroblasts were different. Furthermore, our studies showed that while LPS activated AP-1 and NFκB in U937 cells, it only activated NFκB in fibroblasts. Analysis of nuclear AP-1 subunits showed that LPS stimulated c-Fos, Fra-1 and Jun D activities in U937 cells, but not fibroblasts. The lack of ERK involvement in LPS-stimulated IL-6 in fibroblasts was further supported by the observations that simvastatin, which is known to target ERK-AP-1, failed to inhibit LPS-stimulated IL-6 by fibroblasts. Finally, we showed that targeting NFκB pathway was highly effective in inhibition of LPS-stimulated IL-6 in coculture of U937 cells and fibroblasts.

Oxidized low-density lipoprotein (oxLDL) and oxLDL-containing immune complexes (oxLDL-IC) contribute to the formation of lipid-laden macrophages (foam cells). Fcγ receptors mediate uptake of oxLDL-IC, whereas scavenger receptors internalize oxLDL. We have previously reported that oxLDL-IC, but not free oxLDL, activate macrophages and prolong their survival. Sphingomyelin is a major constituent of cell membranes and lipoprotein particles and acid sphingomyelinase (ASMase) hydrolyses sphingomyelin to generate the bioactive lipid ceramide. ASMase exists in two forms: lysosomal (L-ASMase) and secretory (S-ASMase). In this study we examined whether oxLDL and oxLDL-IC regulate ASMase differently, and whether ASMase mediates monocyte/macrophage activation and cytokine release. The oxLDL-IC, but not oxLDL, induced early and consistent release of catalytically active S-ASMase. The oxLDL-IC also consistently stimulated L-ASMase activity, whereas oxLDL induced a rapid transient increase in L-ASMase activity before it steadily declined below baseline. Prolonged exposure to oxLDL increased L-ASMase activity; however, activity remained significantly lower than that induced by oxLDL-IC. Further studies were aimed at defining the function of the activated ASMase. In response to oxLDL-IC, heat-shock protein 70B' (HSP70B') was up-regulated and localized with redistributed ASMase in the endosomal compartment outside the lysosome. Treatment with oxLDL-IC induced the formation and release of HSP70-containing and IL-1β-containing exosomes via an ASMase-dependent mechanism. Taken together, the results suggest that oxLDL and oxLDL-IC differentially regulate ASMase activity, and the pro-inflammatory responses to oxLDL-IC are mediated by prolonged activation of ASMase. These findings may contribute to increased understanding of mechanisms mediating macrophage involvement in atherosclerosis.

Background Circulating immune complexes (IC) containing modified forms of LDL (mLDL) are strongly pro-inflammatory and when present in high levels are associated with the development of diabetic complications. Objective We investigated whether levels of oxidized LDL (oxLDL), malondialdehyde-LDL (MDA-LDL) and advanced glycation end products-LDL (AGE-LDL) as well as IgG and IgM antibodies reacting with MDA-lysine epitopes expressed by oxLDL and MDA-LDL isolated from circulating IC were associated with progression to macroalbuminuria in type 2 diabetes (VADT cohort). Methods Levels of mLDL in IC were measured in 905 patients, a median of two years after entry into the study. Participants were followed for an average of 3.7 years for renal outcomes. Generalized logistic regression models were used to quantify the association of increased levels of biomarkers and development of abnormal albuminuria. Normal, persistent micro- (ACR ≥ 30), incident micro- (ACR ≥ 30) and incident macroalbuminuria (ACR ≥ 300) were the outcomes of interest. Results and conclusions Patients with macro (n = 78) or non-persistent microalbuminuria (n = 81) at baseline were excluded. Odds ratios for endpoints in relation to high versus low (defined using a median split) biomarker levels are found in Fig. 1 . Our study demonstrates that high levels of AGE-LDL as well as of IgG antibodies (but not IgM antibodies) reacting with MDA-LDL lysine epitopes in circulating IC predict the development of macroalbuminuria in patients with type 2 diabetes. These data support the pathogenic role of modified LDL IgG antibodies but not the protective role of modified LDL IgM antibodies.

Obesity is associated with increased monocyte infiltration into adipose tissue and hence increased interaction between adipocytes and monocytes. Although it has been shown that matrix metalloproteinases (MMP) play a critical role in adipose tissue development, the effect of adipocyte and monocyte interaction on MMP production remains largely unknown. Furthermore, although it has been shown that Toll-like receptor 4 (TLR4), a receptor mediating innate immune response, plays an important role in the obesity-associated inflammation and insulin resistance, the effect of TLR4 activation in coculture of adipocytes and monocytes on MMP production has not been investigated. In this study, we cocultured adipocytes with U937 mononuclear cells in a Transwell coculture system and activated TLR4 with lipopolysaccharide or palmitic acid. We found that TLR4 activation and the coculture had a synergistic effect on MMP-1 production. In our further investigation on the underlying mechanisms, it was indicated that adipocyte-derived IL-6 and TLR4 activation acted in concert to synergistically stimulate MMP-1 expression by U937 cells. Taken together, this study has uncovered a novel mechanism potentially involved in MMP-1 up-regulation in adipose tissue, which may facilitate adipose tissue development and obesity.

Patients with diabetes mellitus have increased mortality and morbidity of cardiovascular diseases compared with nondiabetic patients. Although clinical studies have shown that effective glycemic control with insulin treatment in patients with type 1 diabetes is associated with reduced cardiovascular events, the underlying mechanisms have not been well understood. In this study, we treated diabetic apolipoprotein E-deficient (apoE−/−) mice with insulin for 20 weeks and studied the effect of insulin treatment on intimal lesion size and matrix metalloproteinase (MMP) 9 expression known to be involved in plaque destabilization. Results showed that insulin treatment, which effectively reduced plasma glucose level in diabetic mice, attenuated diabetes-increased intimal lesion size and significantly inhibited diabetes-increased MMP9 expression, but had no effect on tissue inhibitor of metalloproteinase 1 in atherosclerotic plaques. Furthermore, we observed that insulin treatment did not reduce diabetes-increased macrophage content but inhibited interleukin 6 expression, a stimulator for MMP expression. Taken together, this study has shown for the first time that insulin treatment in diabetic apoE−/− mice changes atherosclerotic lesions and gene expression to a state that favors plaque stability.

OBJECTIVE High cholesterol levels in circulating immune complexes (IC), surrogate markers of modified LDL, are associated with increased carotid intima-media thickness (IMT) and cardiovascular events in type 1 diabetes. Different modifications of LDL are involved in IC formation, but which of these are predictive of vascular events is not known. Therefore, we measured oxidized LDL (oxLDL), advanced glycation end products–modified LDL (AGE-LDL), and malondialdehyde-modified LDL (MDA-LDL) in IC and determined their relationship with increased carotid IMT and compared the strength of the association with that observed with conventional risk factors. RESEARCH DESIGN AND METHODS Levels of oxLDL, AGE-LDL, and MDA-LDL were measured in circulating IC isolated from sera of 479 patients of the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) cohort, collected at baseline. Internal and common carotid IMT were measured 8 and 14 years later by DCCT/EDIC. RESULTS OxLDL, AGE-LDL, and MDA-LDL levels in circulating IC were significantly correlated with diabetes duration, BMI, and lipid and blood pressure, but not with age. Multivariate logistic regression models indicated that individuals in the highest versus lowest quartile of oxLDL and AGE-LDL in IC had a 6.11-fold [confidence interval (CI) 2.51–14.8] and a 6.4-fold (CI 2.53–16.2) increase in the odds of having high carotid IMT, respectively, after adjusting for conventional risk factors. Parallel analyses resulted in odds ratios of 2.62 (CI 1.24, 5.55) for LDL-C, 1.45 (CI 0.69, 3.03) for diastolic blood pressure, and 2.33 (CI 1.09, 4.99) for A1C. CONCLUSIONS OxLDL and AGE-LDL in circulating IC were significantly associated with progression and increased levels of carotid IMT in type 1 diabetes.

Sphingosine-1-phosphate (S1P) is a bioactive lysophospholipid that regulates numerous key cardiovascular functions. High-density lipoproteins (HDLs) are the major plasma lipoprotein carriers of S1P. Fibrinolysis is a physiological process that allows fibrin clot dissolution, and decreased fibrinolytic capacity may result from increased circulating levels of plasminogen activator inhibitor-1 (PAI-1). We examined the effect of S1P associated with HDL subfractions on PAI-1 secretion from 3T3 adipocytes. S1P concentration in HDL3 averaged twice that in HDL2. Incubation of adipocytes with increasing concentrations of S1P in HDL3, but not HDL2, or with S1P complexed to albumin stimulated PAI-I secretion in a concentration-dependent manner. Quantitative RT-PCR revealed that S1P(1-3) are expressed in 3T3 adipocytes, with S1P(2) expressed in the greatest amount. Treatment of adipocytes with the S1P(1) and S1P(3) antagonist VPC23019 did not block PAI-1 secretion. Inhibiting S1P(2) with JTE-013 or reducing the expression of the gene coding for S1P(2) using silencing RNA (siRNA) technology blocked PAI-1 secretion, suggesting that the S1P(2) receptor mediates PAI-1 secretion from adipocytes exposed to HDL3 or S1P. Treatment with the phospholipase C (PLC) inhibitor U73122, the protein kinase C (PKC) inhibitor RO-318425, or the Rho-associated protein kinase (ROCK) inhibitor Y27632 all significantly inhibited HDL3- and S1P-mediated PAI-1 release, suggesting that HDL3- and/or S1P-stimulated PAI-1 secretion from 3T3 cells is mediated by activation of multiple, downstream signaling pathways of S1P(2).

BACKGROUND The evidence for genetic susceptibility in the pathogenesis of diabetic nephropathy is well recognised, but the genes involved remain to be identified. It is hypothesised that mutations within the gene encoding connective tissue growth factor (CTGF/CCN2) will increase the propensity of diabetic subjects to develop nephropathy. METHODS AND RESULTS Genomic screening was performed for single nucleotide polymorphisms (SNPs) within the CTGF gene in 862 subjects from the DCCT/EDIC cohort of type 1 diabetes. A novel SNP was identified in the promoter region that changes a C-G at the position -20. The frequency of GG genotype in microalbuminuric patients (albumin excretion rate (AER)40 mg/24 h) is significantly greater than diabetics with AER40 mg/24 h, p0.0001. The relative risk (RR) to develop microalbuminuria in diabetic subjects with the polymorphism is 3X higher than diabetic subjects without the polymorphism (RR 3.142, 95% CI 1.9238 to 5.1249; p0.05). Kaplan-Meier survival curves demonstrated that the GG genotype group developed microalbuminuria and macroalbuminuria at a more rapid rate than the GC or CC genotypes. Functional studies demonstrated that the basal activity of the substituted allele/promoter (-20 GG allele) was significantly greater than that of the wild type promoter (-20 CC genotype). This higher level of basal activity of substituted allele CTGF/CCN2 promoter was abrogated upon suppression of Smad1 levels, indicating that SNP region in the CTGF/CCN2 promoter plays a vital role in the gene expression. CONCLUSIONS These findings provide the first evidence that variants within the promoter region of the CTGF/CCN2 gene predisposes diabetic subjects to develop albuminuria and demonstrate that Smad1 [corrected] controls the expression of CTGF/CCN2 promoter through this region.

Heat shock proteins (HSPs) have been implicated in the activation and survival of macrophages. This study examined the role of HSP70B′, a poorly characterized member of the HSP70 family, in response to oxidatively modified LDL (oxLDL) and immune complexes prepared with human oxLDL and purified human antibodies to oxLDL (oxLDL-IC) in monocytic and macrophage cell lines. Immunoblot analysis of cell lysates and conditioned medium from U937 cells treated with oxLDL alone revealed an increase in intracellular HSP70B′ protein levels accompanied by a concomitant increase in HSP70B′ extracellular levels. Fluorescence immunohistochemistry and confocal microscopy, however, demonstrated that oxLDL-IC stimulated the release of HSP70B′, which co-localized with cell-associated oxLDL-IC. In HSP70B′-green fluorescent protein-transfected mouse RAW 264.7 cells, oxLDL-IC-induced HSP70B′ co-localized with membrane-associated oxLDL-IC as well as the lipid moiety of internalized oxLDL-IC. Furthermore, the data demonstrated that HSP70B′ is involved in cell survival, and this effect could be mediated by sphingosine kinase 1 (SK1) activation. An examination of regularly implicated cytokines revealed a significant relationship between HSP70B′ and the release of the anti-inflammatory cytokine interleukin-10 (IL-10). Small interfering RNA knockdown of HSP70B′ resulted in a corresponding decrease in SK1 mRNA levels and SK1 phosphorylation as well as increased release of IL-10. In conclusion, these findings suggest that oxLDL-IC induce the synthesis and release of HSP70B′, and once stimulated, HSP70B′ binds to the cell-associated and internalized lipid moiety of oxLDL-IC. The data also implicate HSP70B′ in key cellular functions, such as regulation of SK1 activity and release of IL-10, which influence macrophage activation and survival.

It is well known that saturated fatty acids (SFAs) and unsaturated fatty acid, in particular omega-3 polyunsaturated fatty acids (n-3 PUFAs), have different effects on inflammatory signaling: SFAs are pro-inflammatory but n-3 PUFAs have strong anti-inflammatory properties. We have reported that palmitic acid (PA), a saturated fatty acid, robustly amplifies lipopolysaccharide (LPS) signaling to upregulate proinflammatory gene expression in macrophages. We also reported that the increased production of ceramide (CER) via sphingomyelin (SM) hydrolysis and CER de novo synthesis plays a key role in the synergistic effect of LPS and PA on proinflammatory gene expression. However, it remains unclear if n-3 PUFAs are capable of antagonizing the synergistic effect of LPS and PA on gene expression and CER production. In this study, we employed the above macrophage culture system and lipidomical analysis to assess the effect of n-3 PUFAs on proinflammatory gene expression and CER production stimulated by LPS and PA. Results showed that DHA strongly inhibited the synergistic effect of LPS and PA on proinflammatory gene expression by targeting nuclear factor kappa B (NFκB)-dependent gene transcription. Results also showed that DHA inhibited the cooperative effect of LPS and PA on CER production by targeting CER de novo synthesis, but not SM hydrolysis. Furthermore, results showed that myriocin, a specific inhibitor of serine palmitoyltransferase, strongly inhibited both LPS-PA-stimulated CER synthesis and proinflammatory gene expression, indicating that CER synthesis is associated with proinflammatory gene expression and that inhibition of CER synthesis contributes to DHA-inhibited proinflammatory gene expression. Taken together, this study demonstrates that DHA antagonizes the boosting effect of PA on LPS signaling on proinflammatory gene expression by targeting both NFκB-dependent transcription and CER de novo synthesis in macrophages.

Although it has been reported that osteopontin, a matrix glycoprotein and proinflammatory cytokine, mediates obesity-induced adipose tissue macrophage infiltration and insulin resistance, it remains unclear how osteopontin is up-regulated in adipose tissue in obese humans and animals. In this study, we incubated U937 mononuclear cells with adipocytes in a transwell system and studied how cell interaction regulated osteopontin expression. Results showed that coculture of U937 cells with adipocytes led to a marked increase in osteopontin production when compared with that released by independent cultures of U937 cells. Moreover, lipopolysaccharide or palmitic acid-induced TLR4 activation and high glucose further augmented the coculture-stimulated osteopontin secretion. Similar observations were made in the coculture of human primary monocytes and adipocytes. Real time PCR studies showed that coculture of U937 cells and adipocytes increased osteopontin mRNA in U937 cells, but not adipocytes, suggesting that adipocyte-derived soluble factor may stimulate osteopontin expression by U937 cells. In our studies to explore the underlying mechanism, we found that the neutralizing antibodies against interleukin (IL)-6 or IL-6 small interfering RNA transfection in adipocytes effectively inhibited coculture-stimulated osteopontin expression, suggesting that IL-6 released by adipocytes plays an essential role in the coculture-stimulated osteopontin expression by U937 cells. In conclusion, this study has demonstrated that cell interaction, TLR4 activation, and high glucose up-regulate osteopontin expression, and adipocyte-derived IL-6 played a major role in the up-regulation.