Adaptive immune responses in atherosclerosis - or how to prolong the use of your yellow socks

Abstract Atherosclerosis is a multifactorial disease, but an unbalanced immune system plays a critical role in the disease development. A common theory states that a continuous stress to the vascular vessel wall initiates a repair process that however is insufficient to completely heal the tissue. This imbalance is associated with accumulation of cholesterol, which is an essential component of cellular membranes, and inflammatory cells at the injury site. Since cholesterol particles are not normally accumulating extra-cellularly, they are affected by the inflammatory environment, which modifies the particle structure. Since this can be potentially dangerous an inflammatory response is initiated in order to remove the modified particles. However, the continuous stress leads to an imbalanced immune response, which aggravate the inflammation and leads to a larger wound. In this thesis I present two methods on how to balance the immune response in order to stabilize the wound and thereby reduce the risk of rupture. I also elucidate the role of CD8+ T lymphocytes in the development of atherosclerotic lesions and test the association between CD8+ T lymphocytes in blood and cardiovascular disease

CD8+ T cell activation predominate early immune responses to hypercholesterolemia in Apoe-/- mice

<p>Abstract</p> <p>Background</p> <p>It is well established that adaptive immune responses induced by hypercholesterolemia play an important role in the development of atherosclerosis, but the pathways involved remain to be fully characterized. In the present study we assessed immune responses to hypercholesterolemia induced by feeding <it>Apoe^-/-</it>mice a high-fat diet for 4 or 8 weeks.</p> <p>Results</p> <p>The primary immune response in lymph nodes draining the aortic root was an increased expression of interferon (IFN)-γ in CD8⁺CD28⁺T cells, while an activation of IFN-γ expression in CD4⁺T cells was observed only after 8 weeks of high-fat diet. Contrarily, spleen CD4⁺T cells responded with a higher expression of IL-10. Spleen CD8⁺T cells expressed both IFN-γ and IL-10 and showed enhanced proliferation when exposed to Concanavalin A. Plasma levels of IgG and IgM against oxidized LDL did not change, but the level of apolipoprotein B/IgM immune complexes was increased.</p> <p>Conclusion</p> <p>Hypercholesterolemia leads to unopposed activation of Th1 immune responses in lymph nodes draining atherosclerotic lesions, whereas Th1 activation in the spleen is balanced by a concomitant activation of Th2 cells. The activation of CD8⁺T cells implies that hypercholesterolemia is associated with formation of cell autoantigens.</p

Defining Natural History: Assessment of the Ability of College Students to Aid in Characterizing Clinical Progression of Niemann-Pick Disease, Type C

Niemann-Pick Disease, type C (NPC) is a fatal, neurodegenerative, lysosomal storage disorder. It is a rare disease with broad phenotypic spectrum and variable age of onset. These issues make it difficult to develop a universally accepted clinical outcome measure to assess urgently needed therapies. To this end, clinical investigators have defined emerging, disease severity scales. The average time from initial symptom to diagnosis is approximately 4 years. Further, some patients may not travel to specialized clinical centers even after diagnosis. We were therefore interested in investigating whether appropriately trained, community-based assessment of patient records could assist in defining disease progression using clinical severity scores. In this study we evolved a secure, step wise process to show that pre-existing medical records may be correctly assessed by non-clinical practitioners trained to quantify disease progression. Sixty-four undergraduate students at the University of Notre Dame were expertly trained in clinical disease assessment and recognition of major and minor symptoms of NPC. Seven clinical records, randomly selected from a total of thirty seven used to establish a leading clinical severity scale, were correctly assessed to show expected characteristics of linear disease progression. Student assessment of two new records donated by NPC families to our study also revealed linear progression of disease, but both showed accelerated disease progression, relative to the current severity scale, especially at the later stages. Together, these data suggest that college students may be trained in assessment of patient records, and thus provide insight into the natural history of a disease

Lymphocytes in atherosclerosis

It is well established that atherosclerosis is caused by an inflammatory process in the arterial intima. However, it is only in recent years that it has become clear that this inflammation is modulated by immune responses against plaque antigens. These antigens are primarily believed to be modified self-antigens such as oxidized LDL. The immune system is challenged to determine whether these antigens should be regarded self and tolerated or non-self and eliminated. The latter will result in plaque development while the first will be protective. T cells are key effectors of both types of responses. An activation of regulatory T cells inhibits auto-reactive T effector cells and is anti-inflammatory. In contrast, if Th1 cells become activated in the plaque this is associated with increased inflammation and disease progression. The role of B cells in atherosclerosis remains to be clarified but some species of athero-protective antibodies have been identified. The elucidation of role of immune system in atherosclerosis has revealed new targets for intervention and both vaccines and antibody-based therapies are presently in or due to enter clinical testing. (c) 2012 Elsevier B.V. All rights reserved

Association between CD8(+) T cell subsets and cardiovascular disease.

OBJECTIVES: The findings of experimental studies suggest that the immune system plays a key role in atherosclerosis but the clinical importance of different immune cells in cardiovascular disease remains poorly characterized. In this study we investigated the association between CD8(+) T cells and carotid disease as well as development of cardiovascular disease events. DESIGN: The study cohort comprised 700 subjects from the cardiovascular arm of the Malmö Diet and Cancer Study. Peripheral blood mononuclear cells, obtained at the 1991-1994 baseline investigation and stored at -140°C, were thawed and the different CD8(+) T cell populations analysed by flow cytometry. Baseline carotid intima-media thickness and stenosis were assessed by ultrasonography and clinical events were monitored through validated national registers. RESULTS: Subjects with a high fraction of CD8(+) T cells were characterized by decreased cytokine release from activated leukocytes, metabolic signs of insulin resistance and increased incidence of coronary events; hazard ratios (95% confidence intervals) for the second and third tertiles of CD8(+) T cells were 2.57 (1.16, 5.67) and 2.61 (1.19, 5,71), respectively, in a Cox proportional hazards regression model. Correlations were found between the fraction of CD8(+) CD25(+) T cells and the degree of carotid stenosis (r=0.11, P<0.01), and between the CD8(+) CD56(-) IFN-γ(+) T cell fraction and the degree of stenosis (r=-0.18, P<0.005). The association between CD8(+) CD56(-) IFN-γ(+) T cells and carotid stenosis remained significant after controlling for major cardiovascular disease risk factors. CONCLUSION: The present study provides prospective clinical evidence for a role of CD8(+) T cells in cardiovascular disease and suggests the existence of CD8(+) T cell subsets with different pathological functions. © 2013 The Association for the Publication of the Journal of Internal Medicine

Association between CD8+ T-cell subsets and cardiovascular disease

Background The findings of experimental studies suggest that the immune system plays a key role in atherosclerosis, but the clinical importance of different immune cells in cardiovascular disease remains poorly characterized. In this study we investigated the association between CD8+ T cells and carotid disease as well as development of cardiovascular disease events. Methods The study cohort comprised 700 subjects from the cardiovascular arm of the Malmö Diet and Cancer Study. Peripheral blood mononuclear cells, obtained at the 1991–1994 baseline investigation and stored at −140 °C, were thawed and the different CD8+ T-cell populations analysed by flow cytometry. Baseline carotid intima–media thickness and stenosis were assessed by ultrasonography and clinical events were monitored through validated national registers. Results Subjects with a high fraction of CD8+ T cells were characterized by decreased cytokine release from activated leucocytes, metabolic signs of insulin resistance and increased incidence of coronary events; hazard ratios (95% confidence intervals) for the second and third tertiles of CD8+ T cells were 2.57 (1.16, 5.67) and 2.61 (1.19, 5,71), respectively, in a Cox proportional hazards regression model. Correlations were found between the fraction of CD8+CD25+ T cells and the degree of carotid stenosis (r = 0.11, P < 0.01), and between the CD8+CD56−IFN-γ+ T-cell fraction and the degree of stenosis (r = −0.18, P < 0.005). The association between CD8+CD56−IFN-γ+ T cells and carotid stenosis remained significant after controlling for major cardiovascular disease risk factors. Conclusion This study provides prospective clinical evidence for a role of CD8+ T cells in cardiovascular disease and suggests the existence of CD8+ T-cell subsets with different pathological functions