| 1. |
- Backteman, Karin, 1960-
(författare)
-
T Cells and NK Cells in Coronary Artery Disease : Longitudinal and methodological studies in humans
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Coronary artery disease (CAD) is the leading cause of death worldwide and most often due to atherosclerosis. Atherosclerosis is a chronic inflammatory process that involves the arteries, inclouding those that supply blood to the heart muscle. Although inflammation is an important contributing factor to atherosclerosis, the mechanisms are not fully understood. One mechanism contributing to atherogenesis may involve some infectious microorganisms such as cytomegalovirus (CMV). In atherosclerosis, the arterial wall becomes infiltrated with lipids followed by different types of leukocytes and inflammatory mediators (atherogenesis). Leukocytes recirculate continuously between the blood and lymphoid organs, such as lymph nodes, where the adaptive immune response is started and regulated.The general aim of this thesis was to increase the understanding of associations between lymphocyte populations and different conditions of CAD (unstable and stable). To assess changes over time, a longitudinal follow up design was mostly used. Therefore, also perspectives of longitudinal variation were included in the thesis.Paper I showed that flow cytometric evaluation of lymphocyte populations is a robust technique that can be used in longitudinal studies, both in clinical and research settings. It was also shown that the time of sampling over the year did not have a major impact on the findings.In paper II, thoracic lymph nodes were investigated to assess whether CAD-associated changes were more prominent in comparison with blood. As expected, there were several major differences in lymphocyte composition between lymph nodes and blood. However, the analysis of thoracic lymph nodes did not reveal any further changes that were not detected in blood. Thus, blood is still the most reliable compartment for studies of lymphocyte populations in CAD since it is not possible to examine the local findings in the artery wall.Natural killer (NK) cells are innate lymphocytes with both regulatory and effector functions. In paper II and III we confirmed previous findings that CAD patients have lower proportions of NK cells in blood. However, the NK subtype and cytokine profile (paper III, measured by subtype markers and intra-cellular cytokine staining) did not differ between patients and controls. During a 12-month follow-up, the proportions of NK cells increased, although not in all patients. Failure to reconstitute NK cell levels was associated with several components of the metabolic syndrome and with a persistent low-grade inflammation as measured by plasma IL-6 levels. The findings support the notion of a protective role for NK cells in inflammation.CD4+ but not CD8+ T cells were significantly increased in patients with both unstable and stable conditions compared with healthy individuals (paper IV). Subpopulations of CD4+ T cells (CD4+CD28null) have previously been associated with CAD. However, we show that CD28null and CD28null57+ cells within the CD4+ and CD8+ T cell populations were similar in CAD patients and healthy controls. Instead, CMV seropositivity was the major determinant of expanded CD28null and CD57+ T cell fractions in both patients and healthy individuals. During the 1 year follow up the proportion of CD4+CD28null and CD8+CD28null cells increased in patients, which may reflect an accelerated immunological ageing occurring after the cardiac event.
|
|
| 2. |
- Björk Wilhelms, Daniel
(författare)
-
Fever : Role of brain endothelial prostaglandins
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fever and loss of appetite are two of the most fundamental manifestations of disease. These disease symptoms, which lead to deviations from normal body temperature and food intake patterns, are seen in a vast array of infectious and inflammatory conditions. It is known that peripheral signals from the immune system are essential triggers for these responses, which are orchestrated by neuronal circuits in the brain. Due to the blood‐brain barrier, peripheral inflammatory signals require a specific mode of transmission into the brain. Such mechanisms have been proposed, but interventional studies of these mechanisms have never rendered conclusive results. In this thesis, we present the first functional evidence of cyclooxygenase 2 (COX‐2) and microsomal prostaglandin E synthase type 1 (mPGES‐1) mediated prostaglandin E2 synthesis in the blood‐brain barrier endothelial cells as a signaling mechanism in the initiation of inflammatory fever. We also show that one of the world’s most widely used antipyretics, paracetamol, acts by inhibition of COX‐2. Combined with the finding that COX‐2 and mPGES‐1 in brain endothelial cells play a key role in inflammatory fever, this finding suggests that paracetamol inhibits fever by specifically blocking prostaglandin E2 synthesis in blood‐brain barrier endothelium. In another symptom of inflammation, anorexia, the cellular origin of peripheral signals triggering acute anorexia are largely unknown. We show that the expression of myeloid differentiation primary response gene 88 (Myd88) in myeloid cells is important for the initiation of acute inflammatory anorexia and the maintenance of cancer anorexia‐cachexia.Taken together, these findings provide a significant advancement of our understanding of the mechanisms triggering acute inflammatory fever and anorexia and also explain the antipyretic effect of paracetamol.
|
|
| 3. |
- Hjorth, Maria, 1978-
(författare)
-
Immunological profile and aspects of immunotherapy in type 1 diabetes
- 2010
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Type 1 diabetes (T1D) is a chronic, autoimmune disease caused by a T cell mediated attack on the insulin producing pancreatic ß-cells. Even though reasonable quality of life can be acquired with modern insulin therapy, prevention of acute and late serious complications is facilitated by preservation of residual insulin secretion. Preventing β-cell destruction is therefore an important goal of T1D therapy. Characterisation of immunological changes in the course of T1D is essential for understanding the underlying pathogenic mechanisms and for evaluating the efficacy of therapeutic intervention. This thesis aimed to study the immune profile in individuals at increased risk of T1D and in patients diagnosed with the disease. In addition, the immunological effects of treatment with the B vitamin, Nicotinamide, and by antigen-specific immunotherapy using GAD65, have been studied in high-risk individuals and in T1D patients, respectively.We have found that individuals at high risk of T1D had an increased T helper (Th) 1 like immune profile, defined by high secretion of interferon (IFN) -γ. At the time of clinical onset of T1D, the Th1 dominance was diminished. We further demonstrate that children with newly diagnosed T1D had a suppressed Th1 like profile, detected by chemokine and chemokine receptor profile. This was accompanied by an induced population of CCR7+ and CD45RA+ naïve, CD8+cytotoxic T (Tc) cells and a reduced CD45RO+ memory Tc cell pool. It has previously been shown that oral Nicotinamide had no clinical effect in prevention of T1D. However, we found that the treatment was associated with a decreased secretion of IFN-γ. We have previously shown that subcutaneous injections with GAD-alum in T1D children induced a better preservation of endogenous insulin secretion compared with placebo. Here, we demonstrate that the treatment induced an early antigen-specific Th2 and regulatory immune profile. After a few months, and still after more than two years, the recall response to GAD65 was characterised by a broader range of cytokines. GAD-alum treatment also induced a GAD65-specific CD4+CD25highFOXP3+ cell population and reduced the levels of CD4+CD25+ cells. In conclusion, a Th1 like immune profile in pre-diabetic individuals indicates an imbalance of the immune system. At time of clinical onset, and in the period afterwards, reduction of the Th1 associated immune response could be an effect of a suppressed destructive process, selective recruitment of effector T cells to the pancreas or a defective immune regulation. The protective effect of GAD-alum in T1D children seems to be mediated by an early skewing of GAD65-induced responses towards a Th2 phenotype. Further, induction of GAD65-specific T cells with regulatory characteristics might be able to suppress autoreactive responses and inflammation in the pancreas.
|
|
| 4. |
- Karlsson, Markus
(författare)
-
Oxidative stress-related damage of retinal pigment epithelial cells : possible protective properties of autophagocytosed iron-binding proteins
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Oxidative stress is a major pathogenic factor in the development of age-related macular degeneration (AMD), which is the most common cause of severe central visual impairment in the elderly population in the western world.It is believed that the degenerative process starts in the retinal pigment epithelium (RPE). The post-mitotic RPE is a single layer of pigmented cells located behind the photoreceptors – rods and cones – of the retina. Daily, the RPE cells phagocytose and recycle the expended tips of the photoreceptor outer segments. This heavy phagocytic burden leads to substantial oxidative stress in the cells, which is further enhanced by intense illumination and a high oxygen tension. A hallmark of early AMD is a progressive build-up of the non-degradable age pigment lipofuscin (LF) in lysosomes of the RPE. LF accumulation hampers phagocytosis and autophagy in the RPE, resulting in increased amounts of cellular debris in and around the cells. This decreases the function and viability of both RPE cells and photoreceptors.Iron is known to accumulate in the retina with increasing age, particularly in AMDaffected eyes, and amplifies oxidative stress by acting as a potent catalyst in the generation of hydroxyl radicals. These highly reactive radicals contribute to LF formation and may, if abundantly present, also directly damage lysosomal membranes. The subsequent leakage of degrading enzymes to the cytosol initiates cell death via apoptosis or necrosis.In this thesis, we have investigated the oxidative stress response of human RPE (ARPE-19) cells compared to murine J774 cells, another type of lysosome-rich cells with a high phagocytic capacity. The ARPE-19 cells were found to be extremely resistant to oxidative stress and tolerated exposure to single doses of H2O2 in concentrations up to 150 times higher than the J774 cells before lysosomal rupture and ensuing cell death occurred. This resistance was increased even further when the cells were protected with a potent iron chelator that prevents redox-active iron to participate in hydroxyl radical generation. Both cell lines were shown to be equally effective in degrading H2O2 and seem to contain comparable amounts of total as well as intralysosomal iron. Therefore, we reasoned that the insensitivity of ARPE-19 cells to H2O2 exposure might be related to a mechanism which keeps their intralysosomal iron bound in a non redox-active form. This theory was supported by our finding of very high basal expression levels of metallothionein (MT), heat shock-protein 70 (HSP70) and ferritin (FT) in ARPE-19 cells compared to J774 cells. All of these proteins have previously been shown to possess potent iron-binding properties. The ARPE-19 cells were also shown to have a higher basal rate of autophagy. SiRNA-mediated attenuation of MT, HSP70 and FT levels in the ARPE-19 cells resulted, to some degree, in an increased sensitivity to H2O2 treatment. Furthermore, a human cell stress array showed several other stress-related proteins to be up-regulated in ARPE-19 cells.Additionally, we evaluated the commonly used, but frequently misinterpreted, H2DCF test for oxidative stress. It was demonstrated that oxidation of H2DCF into fluorescent DCF mainly reflects relocation to the cytosol of lysosomal iron and mitochondrial cytochrome c, rather than being the result of some poorly defined “general” oxidative stress.In conclusion, our results indicate that the extreme resistance to oxidative stress exhibited by the ARPE-19 cells might be related to a high continuous autophagic influx of iron-binding proteins into the lysosomal compartment. Before being degraded, such proteins will temporarily keep intralysosomal iron bound in a non redox-active form, thereby inhibiting hydroxyl radical formation. This may partly explain why RPE cells, in spite of their exposed location and heavy burden of phagocytosis, usually manage to survive and evade significant LF accumulation until late in life.
|
|
| 5. |
- Lahdenperä, Anne, 1974-
(författare)
-
Studies of Mucosal Immune Regulation in Celiac Disease and Type 1 Diabetes
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Celiac disease (CD) and type 1 diabetes (T1D) are two chronic autoimmune diseases with increasing incidence worldwide. A combination of genetic, environmental and immunological factors is considered to be involved in development of the diseases, even though the exact disease mechanisms still are unknown. CD and T1D are both believed to be associated with type 1 like immune responses. However, there is limited knowledge about the complex network of intestinal and peripheral immune responses associated with the diseases.Aims: The aim of this thesis was to explore intestinal and peripheral immune responses in children at different stages of CD and in children with T1D. Further, we studied peripheral immune responses in children at risk for T1D supplemented with probiotics during their first 6 months of life (PRODIA study).Results & Discussion: Children with untreated CD had up-regulated T-helper (Th)1, T-cytotoxic (Tc)1, Th17 and T-regulatory (Treg) responses, but down-regulated Th2 and Th3 responses in the small intestine. The type 1 response (Th1 and Tc1) seemed to remain elevated in CD children under gluten free diet (GFD)-treatment and thus seemed to be related to the disease itself rather than the gluten intake. The Th2, Th3, Th17 and Treg responses seemed to be gluten dependent, since they normalized upon GFD-treatment. The alterations in the intestinal biopsies did not seem to correlate with the alterations seen in the blood Children with potential CD had diminished levels of the Th17 cytokine IL-17, whereas children with untreated CD had elevated levels of IL-17, indicating that IL-17 immunity develops in the late phase of CD when villous atrophy has developed. Furthermore, stimulation of intestinal epithelial cells with IL-17 induced anti-apoptotic mechanisms. The low intestinal expression of Th1, Th17 and Treg markers was normal in children with T1D, whereas children with T1D and CD had the same pattern as children with untreated CD: high intestinal secretion of pro-inflammatory and Th17 cytokines. The immune responses in children with T1D were generally influenced by the degree of villous atrophy.As expected, the number of children in the PRODIA study developing T1D related autoantibodies during their first two years of life was low. No difference in the autoantibody emergence was seen between infants given probiotics compared to placebo. In the probiotic group, the number of circulating CD58+ monocytes was lower at 6 months of age. At 12 months of age the number of circulating CCR5+ monocytes was lower in the probiotic group, whereas the spontaneous expression of TLR9 on PBMCs was higher.Conclusion: Most of the intestinal T-cell associated immune alterations were generally gluten dependent, since they normalized on a GFD treatment, but the type 1 response seemed to be related to the disease itself, since it was still seen in GFD treated individuals. IL-17 immunity seemed to be induced in the late stage of CD, when villous atrophy has developed and it seemed to be involved in protection from tissue damage in the inflamed intestinal mucosa. The intestinal immune responses were generally not reflected in peripheral blood.Probiotic supplementation in infancy modulated the activation stage and stimulation response of monocytes. Thus, early exposure to microbes seemed to influence the function of the innate immune system in later life.
|
|
| 6. |
- Wang, Chunliang, 1980-
(författare)
-
Computer-Assisted Coronary CT Angiography Analysis : From Software Development to Clinical Application
- 2011
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Advances in coronary Computed Tomography Angiography (CTA) have resulted in a boost in the use of this new technique in recent years, creating a challenge for radiologists due to the increasing number of exams and the large amount of data for each patient. The main goal of this study was to develop a computer tool to facilitate coronary CTA analysis by combining knowledge of medicine and image processing, and to evaluate the performance in clinical settings.Firstly, a competing fuzzy connectedness tree algorithm was developed to segment the coronary arteries and extract centerlines for each branch. The new algorithm, which is an extension of the “virtual contrast injection” (VC) method, preserves the low-density soft tissue around the artery, and thus reduces the possibility of introducing false positive stenoses during segmentation. Visually reasonable results were obtained in clinical cases.Secondly, this algorithm was implemented in open source software in which multiple visualization techniques were integrated into an intuitive user interface to facilitate user interaction and provide good overviews of the processing results. An automatic seeding method was introduced into the interactive segmentation workflow to eliminate the requirement of user initialization during post-processing. In 42 clinical cases, all main arteries and more than 85% of visible branches were identified, and testing the centerline extraction in a reference database gave results in good agreement with the gold standard.Thirdly, the diagnostic accuracy of coronary CTA using the segmented 3D data from the VC method was evaluated on 30 clinical coronary CTA datasets and compared with the conventional reading method and a different 3D reading method, region growing (RG), from a commercial software. As a reference method, catheter angiography was used. The percentage of evaluable arteries, accuracy and negative predictive value (NPV) for detecting stenosis were, respectively, 86%, 74% and 93% for the conventional method, 83%, 71% and 92% for VC, and 64%, 56% and 93% for RG. Accuracy was significantly lower for the RG method than for the other two methods (p<0.01), whereas there was no significant difference in accuracy between the VC method and the conventional method (p = 0.22).Furthermore, we developed a fast, level set-based algorithm for vessel segmentation, which is 10-20 times faster than the conventional methods without losing segmentation accuracy. It enables quantitative stenosis analysis at interactive speed.In conclusion, the presented software provides fast and automatic coronary artery segmentation and visualization. The NPV of using only segmented 3D data is as good as using conventional 2D viewing techniques, which suggests a potential of using them as an initial step, with access to 2D reviewing techniques for suspected lesions and cases with heavy calcification. Combining the 3D visualization of segmentation data with the clinical workflow could shorten reading time.
|
|
