Role of immune mediators in metabolic syndrome and atherosclerosis

Obesity is increasingly becoming a problem worldwide. Both location and metabolic activity of visceral and subcutaneous white adipose tissue (WAT) differ. Visceral fat is highly vascularized resulting in increased blood supply and increased infiltration of inflammatory immune cells such as macrophages, T cells and even B cells. Together with adipocytes these cells secrete adipokines/cytokines that propagate an inflammatory milieu locally as well as systemically. Obesity is strongly associated with the risk of cardiovascular disease (CVD) – diseases affecting the heart and the blood vessels. The underlying pathology of most CVDs is termed atherosclerosis, a chronic inflammatory condition of the arterial wall. The fatty streak formation is the first step in atherogenesis and is an accumulation of lipid-containing cells under the endothelial cell layer, which might progress to atheroma formation. Atherosclerotic lesions develop silently without symptoms over many years. This can change dramatically when a plaque raptures. Occlusion of the artery obstructing the blood flow may cause stroke, myocardial infarction or other life-threatening events. We demonstrate that inflammation of WAT can occur even in the absence of obesity. T cell-driven WAT inflammation and obesity-associated inflammation is characterized by increased T cell infiltration and expression of pro-inflammatory cytokines. Interestingly, IL-6 expression differs in the 2 forms of WAT (paper I). We further show the impact of liver-residing inflammatory iNKT cells on lipid metabolism, controlling metabolic processes distally in WAT (paper III). We also demonstrated the impact of the innate receptor TLR-3 on insulin secretion and lipid metabolism (paper IV). Changes in lipid metabolism and inflammation contribute to lesion development. Different strategies, including immune-modulation and even vaccination, are conceivable to prevent, stop or slow down lesion development. The project in my thesis that demonstrate the impact of FoxP3+ Tregs on lipid metabolism and atherosclerosis (paper II) encourages such work. Altogether, the findings in my thesis are based on in vitro and in vivo models of obesity and atherosclerosis, diseases that can promote each other’s development. We broke down the complex processes to study the involvement of single cell types (iNKT, FoxP3+ Tregs), receptors (TLR-3), and cytokines (IL-6). Together these approaches contribute to the understanding of the molecular mechanisms driving these diseases and will hopefully contribute to new therapeutic approaches

New trends in globalization of science and engineering education

Three decades ago most research and design were conducted in each country independently. But the world has become quite different since then. Global changes in technology and society changed the concept of an engineer. There is the need for engineers who can work effectively in changing global and technical environments. Less interest has been paid to the globalization of science and technology. This article reviews the stimulus, that impact the engineering profession and gives the recommendations concerning the profession of engineering, the technology and innovation

Inhibition of T cell response to native low-density lipoprotein reduces atherosclerosis

Immune responses to oxidized low-density lipoprotein (oxLDL) are proposed to be important in atherosclerosis. To identify the mechanisms of recognition that govern T cell responses to LDL particles, we generated T cell hybridomas from human ApoB100 transgenic (huB100tg) mice that were immunized with human oxLDL. Surprisingly, none of the hybridomas responded to oxidized LDL, only to native LDL and the purified LDL apolipoprotein ApoB100. However, sera from immunized mice contained IgG antibodies to oxLDL, suggesting that T cell responses to native ApoB100 help B cells making antibodies to oxLDL. ApoB100 responding CD4+ T cell hybridomas were MHC class II–restricted and expressed a single T cell receptor (TCR) variable (V) β chain, TRBV31, with different Vα chains. Immunization of huB100tgxLdlr−/− mice with a TRBV31-derived peptide induced anti-TRBV31 antibodies that blocked T cell recognition of ApoB100. This treatment significantly reduced atherosclerosis by 65%, with a concomitant reduction of macrophage infiltration and MHC class II expression in lesions. In conclusion, CD4+ T cells recognize epitopes on native ApoB100 protein, this response is associated with a limited set of clonotypic TCRs, and blocking TCR-dependent antigen recognition by these T cells protects against atherosclerosis

Subcutaneous immunization with heat shock protein-65 reduces atherosclerosis in Apoe⁻/⁻ mice

OBJECTIVE: To modulate atherosclerosis by combining subcutaneous immunization with heat shock protein 65 (hsp65) in alum adjuvant and anti-CD45RB monoclonal antibodies (mAb). METHODS: 8 week old Apoe⁻/⁻ mice on normal chow were treated for 12 weeks: group A received hsp65-alum immunization combined with anti-CD45RB mAb, group B hsp65-alum immunization combined with isotype control antibody, and group C mock vaccine combined with isotype control antibody. RESULTS: Unexpectedly, atherosclerotic lesions in the aortic root were significantly reduced in both hsp65-alum immunization groups (A and B) compared with the control group (C). Significantly elevated antibody titers against hsp65 were detected in both groups along with a significant increase in MHC class II expression on B cells. Body weight, total cholesterol and triglyceride levels were not different between groups. Treatment with anti-CD45RB antibody mediated a shift on CD4⁺ T cells from the CD45RB(high) to CD45RB(low) isoform with a relative increase in CD4⁺Foxp3⁺ regulatory T cells (Treg) in an overall reduced T cell pool. Furthermore, anti-CD45RB treatment mediated a transient reduction of peripheral leukocytes and increased IFN-γ and IL-17A plasma levels. CONCLUSIONS: Subcutaneous immunization with hsp65-alum protects Apoe⁻/⁻ mice against progression of early atherosclerosis. Administration of anti-CD45RB antibody provided no incremental benefit to the athero-protective effects of hsp65-alum treatment alone

Alterations in systemic levels of Th1, Th2, and Th17 cytokines in overweight adolescents and obese mice

BackgroundObesity represents a major problem for patients and health care systems in most industrialized countries. A chronic inflammatory state in obese individuals leads to disease conditions associated with activation of cellular immune mechanisms. Here, we sought to investigate the role of Th1-, Th2-, and Th17-related cytokines in overweight adolescents and mice on a high-fat diet. MethodsPlasma samples were obtained from 79 male adolescents aged 13-17 years. Thirty-seven of them had a body mass index (BMI) above the 90th age-specific percentile. Th1, Th2, and Th17 cytokines were measured using Bio-Plex multiplex technology (Bio-Rad, Hercules, USA). In an experimental approach, mice were fed with high-fat (HFD) or normal chow for 15 weeks. ResultsInterleukin (IL)-17 concentrations were significantly decreased in overweight adolescents compared to lean controls [99.8 7.3 pg/mL standard error of the mean (SEM) vs 146.6 +/- 11.5 pg/mL SEMP = .001]. Levels of IL-17 correlated significantly with anthropometrical parameters of obesity. A concordant response was found in mice consuming a HFD for 15 weeks compared to controls (861 +/- 165 pg/mL SEM vs 1575 +/- 187 pg/ml SEM, P = .0183). However, a biphasic response was evident for most Th1, Th2, and Th17 cytokines as levels initially increased within the first 5 weeks on HFD and showed a decline afterwards. Conclusions In contrast to previous studies showing elevated levels of IL-17 in obese adults, we found a decreasing trend in overweight adolescents. This difference could possibly be related to the fact that disease conditions associated with obesity such as hypertension, vascular pathologies, diabetes, and a triggering of the Th1/Th17 axis were not yet present in overweight teenager

Lack of Invariant Natural Killer T Cells Affects Lipid Metabolism in Adipose Tissue of Diet-Induced Obese Mice

Objective-Obesity promotes a chronic inflammatory condition in adipose tissue (AT). Impairment of insulin sensitivity coincides with infiltration of T cells into AT in early stages of obesity, when macrophages are not yet present. Here, we examine the role of invariant natural killer T (iNKT) cells, a subtype of T cells activated by lipid antigens, on glucose and lipid metabolism in obesity. Approach and Results-J alpha 18(-/-) mice, specifically lacking iNKT cells, and wild-type mice consumed a chow or high-fat diet for 10 weeks. One third of all T lymphocytes in the liver of wild-type mice were iNKT cells, whereas few were detected in AT. Diet-induced obesity increased blood glucose in both genotypes of mice, whereas glucose tolerance test revealed similar kinetics of glucose clearance in J alpha 18(-/-) and wild-type mice. Under obese conditions, expression of inflammatory cytokines in AT did not differ between the groups, although the number of T cells and macrophages was lower in J alpha 18(-/-) mice. Nonetheless, AT homeostasis in J alpha 18(-/-) mice was altered evidenced by lower AT weight, smaller adipocytes, accelerated lipogenesis, increased expression of hormone-sensitive lipase, and accelerated basal lipolysis. Conclusions-iNKT cells do not affect glucose clearance but rather modulate lipid metabolism in both liver and AT. Only few iNKT cells are found in AT under lean and obese conditions, suggesting that their effects on lipid metabolism are mainly mediated in the liver, their primary host orga

Toll-like receptor 3 influences glucose homeostasis and β-cell insulin secretion

Toll-like receptors (TLRs) have been implicated in the pathogenesis of type 2 diabetes. We examined the function of TLR3 in glucose metabolism and type 2 diabetes–related phenotypes in animals and humans. TLR3 is highly expressed in the pancreas, suggesting that it can influence metabolism. Using a diet-induced obesity model, we show that TLR3-deficient mice had enhanced glycemic control, facilitated by elevated insulin secretion. Despite having high insulin levels, Tlr3−/− mice did not experience disturbances in whole-body insulin sensitivity, suggesting that they have a robust metabolic system that manages increased insulin secretion. Increase in insulin secretion was associated with upregulation of islet glucose phosphorylation as well as exocytotic protein VAMP-2 in Tlr3−/− islets. TLR3 deficiency also modified the plasma lipid profile, decreasing VLDL levels due to decreased triglyceride biosynthesis. Moreover, a meta-analysis of two healthy human populations showed that a missense single nucleotide polymorphism in TLR3 (encoding L412F) was linked to elevated insulin levels, consistent with our experimental findings. In conclusion, our results increase the understanding of the function of innate receptors in metabolic disorders and implicate TLR3 as a key control system in metabolic regulation