| 1. |
- Bandaru, Manoj Kumar, 1987-
(författare)
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Zebrafish models for large-scale genetic screens in dyslipidemia and atherosclerosis : Validation and application
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hundreds of loci have been robustly associated with circulating lipids, atherosclerosis and coronary artery disease; but for most loci the causal genes and mechanisms remain uncharacterized. The overall aim of my thesis is to develop and validate novel in vivo model systems that are suitable for high-throughput, image-based genetic screens in coronary artery disease and related traits, and use these model systems to systematically characterize positional candidate genes.In Study I, I developed an experimental pipeline to validate the suitability of zebrafish larvae as a model system for systematic, large-scale characterization of drugs and genes associated with dyslipidemia and atherosclerosis. Using this pipeline, I showed that five days of overfeeding and cholesterol supplementation have independent pro-atherogenic effects in zebrafish larvae, which could be diminished by concomitant treatment with atorvastatin and ezetimibe. CRISPR-Cas9-induced mutations in orthologues of proof-of-concept genes resulted in higher LDL cholesterol levels (apoea), and more early stage atherosclerosis (apobb.1). Finally, the pipeline helped me to identify putative causal genes for circulating lipids and early-stage atherosclerosis (LPAR2 and GATAD2A).In Study II, I characterized cardiometabolic traits in apoc2 mutant zebrafish larvae and found that, similar to humans, larvae with two non-functional apoc2 alleles have higher whole-body levels of triglycerides and total cholesterol, and more vascular lipid deposition than larvae without mutations in apoc2. Interestingly, apoc2 mutant larvae also had lower glucose levels after adjusting for triglyceride levels, suggesting that therapeutic stimulation of apoc2 to prevent hypertriglyceridemia may result in hyperglycemia. Still, zebrafish larvae with mutations in apoc2 can be a useful model to identify and characterize additional causal genes for triglyceride metabolism.In Study III, I examined the effects of mutations in pcsk9 on atherosclerosis and diabetes-related traits in nearly 5,000 zebrafish larvae. Similar to the loss-of-function mutations in PCSK9 in humans, larvae with mutations in pcsk9 had lower LDLc levels and were protected from early-stage atherosclerosis. Interestingly, mutations in pcsk9 also resulted in fewer pancreatic β-cells in 10 days old larvae, which suggests the higher risk of diabetes in humans with mutations in PCSK9 may result from a direct effect on the beta cell.Based on these large-scale proof-of-concept studies, my thesis confirms that zebrafish larvae can be used for large-scale, systematic genetic screens in dyslipidemia and early-stage atherosclerosis.
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| 2. |
- Ingelsson, Erik, 1975-
(författare)
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Insulin Resistance and Inflammation as Risk Factors for Congestive Heart Failure
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Congestive heart failure (CHF) is a major cause of morbidity and mortality and the identification of modifiable risk factors is crucial in order to diminish suffering of this common disease. The primary aim of this thesis was to investigate novel metabolic risk factors for CHF, with a focus on insulin resistance and inflammation. The secondary aim was to examine the validity of the CHF diagnosis in the Swedish hospital discharge register.This thesis was based on the Uppsala Longitudinal Study of Adult Men (ULSAM) cohort, a community-based prospective study started in 1970. The participants were examined at age 50 and 70 and the data was completed with annual updates on mortality and in-hospital morbidity using national registers. We showed that insulin resistance predicts CHF incidence independently of established risk factors in both middle-aged and elderly men. The previously described association between obesity and subsequent CHF may be mediated partly by insulin resistance. Moreover, it was established that inflammation, measured as erythrocyte sedimentation rate is a significant predictor of CHF, independent of established risk factors including an interim myocardial infarction. Furthermore, a low beta-carotene level, as well as an increased apolipoprotein B/A-I-ratio was found to predict CHF independently of established risk factors.We also showed that the validity of the CHF diagnosis in the Swedish hospital discharge register appears less precise than for other recently investigated cardiovascular diagnoses. However, when including only cases from selected clinics or cases with a primary diagnosis of CHF, the validity is comparable to the above diagnoses. In conclusion, insulin resistance and inflammation are strong independent risk factors for the development of CHF, and seem to be involved in the early process leading to CHF. If confirmed, our observations could have large clinical implications as they may offer new approaches in the prevention of CHF.
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| 3. |
- Jobs, Elisabeth
(författare)
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Cathepsin S as a Biomarker of Low-grade Inflammation, Insulin Resistance, and Cardiometabolic Disease Risk
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cathepsin S is a protease important in major histocompatibility complex (MHC) class II antigen presentation and also in degrading the extracellular matrix. Studies, most of them experimental, have shown that cathepsin S is involved in different pathological conditions such as obesity, inflammation, atherosclerosis, diabetes, and cancer.The overall hypothesis of this report is that high levels of circulating cathepsin S, is a biomarker that reflects pathology induced by inflammation and obesity. The overall aim of this report was to investigate possible associations between circulating cathepsin S, inflammation, glucometabolic disturbance, and its associated diseases in the community. As cathepsin S appears to be a novel risk marker for several pathological conditions, we also wanted to examine the effect of dietary intervention on circulating cathepsin S concentrations.This thesis is based on data from three community-based cohorts, the Uppsala longitudinal study of adult men (ULSAM), the prospective investigation of the vasculature in Uppsala seniors (PIVUS), and a post-hoc study from the randomized controlled NORDIET trial.In the first study, we identified a cross-sectional positive association between serum cathepsin S and two markers of cytokine-mediated inflammation, CRP and IL-6. These associations were similar in non-obese individuals. In longitudinal analyses, higher cathepsin S at baseline was associated with higher CRP and IL-6 levels after six years of follow-up. In the second study, we identified a cross-sectional association between increased serum levels of cathepsin S and reduced insulin sensitivity. These associations were similar in non-obese individuals. No significant association was observed between cathepsin S and insulin secretion. In longitudinal analysis, higher cathepsin S levels were associated with an increased risk of developing diabetes during the six-year follow-up. In the third study, we found that higher serum levels of cathepsin S were associated with increased mortality risk. Moreover, in the ULSAM cohort, serum cathepsin S was independently associated with cause-specific mortality from cardiovascular disease and cancer. In the fourth study, we identified that adherence to an ad libitum healthy Nordic diet for 6 weeks slightly decreased the levels of plasma cathepsin S in normal or marginally overweight individuals, relative to the control group. Changes in circulating cathepsin S concentrations were correlated with changes in body weight, LDL-C, and total cholesterol.Conclusion: This thesis shows that circulating cathepsin S is a biomarker that independently reflects inflammation, insulin resistance, the risk of developing diabetes, and mortality risk. Furthermore, a Nordic diet moderately reduced cathepsin S levels in normal-weight and overweight men and women. This effect may be partially mediated by diet-induced weight loss and possibly by reduced LDL-C concentrations.
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| 4. |
- Mubanga, Mwenya
(författare)
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Dog Ownership and Cardiovascular Disease
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The relationship between pet ownership and human health has been studied extensively; however, the effect of dog ownership on human health has had conflicting results. The overall aim of this research project was to investigate the impact of dog ownership, and the death of the dog, on human cardiovascular health and all-cause mortality.Study I was a population-based study investigating the association between dog ownership with the risk of cardiovascular disease (CVD) and death. Of 3,432,153 individuals included, dog ownership (13.1%) was associated with a lower risk of CVD- and all-cause death by 23% and 20%, respectively. In single-person households, there was an inverse association between dog ownership and incident CVD, as well as a stronger inverse association with CVD-death and all-cause death.Study II was a population-based study investigating the association between dog ownership and initiation of treatment for cardiovascular risk factors in 2,026,865 adults. Dog ownership (14.6%) was associated with a slightly elevated risk of initiating treatment (2%) for hypertension and dyslipidaemia, but not for diabetes mellitus. However, some evidence for residual confounding was found.Study III investigated the risk of death after hospitalization for a first-ever acute myocardial infarction (n=181,696) or first-ever ischemic stroke (n=157,617) in two population-based cohorts. Dog ownership was associated with a 20% to 24% lower risk of all-cause mortality and CVD-death, respectively.In Study I-III, ownership of hunting breed dogs was associated with the lowest risk of the outcomes, while owning dogs of mixed pedigree was associated with worse cardiovascular health.Study IV found evidence of an increased risk of CVD after the loss of a life-insured pet (dog or cat; n=147,251) during the first week, 3-6 months after and 6-12 months after pet-loss.This thesis has used the Swedish population and health registers to investigate the relationship between various aspects of dog ownership and cardiovascular risk. By using defined, quantifiable end-points and robust statistical methods, this project has made an important contribution to the body of research underlying the positive relationship between dog ownership and cardiovascular health, paving the way for further research into causal mechanisms.
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| 5. |
- Nerpin, Elisabet, 1962-
(författare)
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The Kidney in Different Stages of the Cardiovascular Continuum
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Patients with chronic kidney disease are at higher risk of developing cardiovascular disease. The complex, interaction between the kidney and the cardiovascular system is incompletely understood, particularly at the early stages of the cardiovascular continuum.The overall aim of this thesis was to clarify novel aspects of the interplay between the kidney and the cardiovascular system at different stages of the cardiovascular continuum; from risk factors such as insulin resistance, inflammation and oxidative stress, via sub-clinical cardiovascular damage such as endothelial dysfunction and left ventricular dysfunction, to overt cardiovascular death.This thesis is based on two community-based cohorts of elderly, Uppsala Longitudinal Study of Adult Men (ULSAM) and Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS).The first study, show that higher insulin sensitivity, measured with euglycemic-hyperinsulinemic clamp technique was associated to improve estimated glomerular filtration rate (eGFR) in participants with normal fasting plasma glucose, normal glucose tolerance and normal eGFR. In longitudinal analyses, higher insulin sensitivity at baseline was associated with lower risk of impaired renal function during follow-up. In the second study, eGFR was inversely associated with different inflammatory markers (C-reactive protein, interleukin-6, serum amyloid A) and positively associated with a marker of oxidative stress (urinary F2-isoprostanes). In line with this, the urinary albumin/creatinine ratio was positively associated with these inflammatory markers, and negatively associated with oxidative stress.In study three, higher eGFR was associated with better endothelial function as assessed by the invasive forearm model. Further, in study four, higher eGFR was significantly associated with higher left ventricular systolic function (ejection fraction). The 5th study of the thesis shows that higher urinary albumin excretion rate (UAER) and lower eGFR was independently associated with an increased risk for cardiovascular mortality. Analyses of global model fit, discrimination, calibration, and reclassification suggest that UAER and eGFR add relevant prognostic information beyond established cardiovascular risk factors in participants without prevalent cardiovascular disease.Conclusion: this thesis show that the interaction between the kidney and the cardiovascular system plays an important role in the development of cardiovascular disease and that this interplay begins at an early asymptomatic stage of the disease process.
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| 6. |
- Nowak, Christoph, 1986-
(författare)
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Insulin Resistance : Causes, biomarkers and consequences
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The worldwide increasing number of persons affected by largely preventable diseases like diabetes demands better prevention and treatment. Insulin is required for effective utilisation of circulating nutrients. Impaired responsiveness to insulin (insulin resistance, IR) is a hallmark of type 2 diabetes and independently raises the risk of heart attack and stroke. The pathophysiology of IR is incompletely understood. High-throughput measurement of large numbers of circulating biomarkers may provide new insights beyond established risk factors.The aims of this thesis were to (i) use proteomics, metabolomics and genomics methods in large community samples to identify biomarkers of IR; (ii) assess biomarkers for risk prediction and insights into aetiology and consequences of IR; and (iii) use Mendelian randomisation analysis to assess causality.In Study I, analysis of 80 circulating proteins in 70-to-77-year-old Swedes identified cathepsin D as a biomarker for IR and highlighted a tentative causal effect of IR on raised plasma tissue plasminogen activator levels. In Study II, nontargeted fasting plasma metabolomics was used to discover 52 metabolites associated with glycaemic traits in non-diabetic 70-year-old men. Replication in independent samples of several thousand persons provided evidence for a causal effect of IR on reduced plasma oleic acid and palmitoleic acid levels. In Study III, nontargeted metabolomics in plasma samples obtained at three time points during an oral glucose challenge in 70-year-old men identified associations between a physiologic measure of IR and concentration changes in medium-chain acylcarnitines, monounsaturated fatty acids, bile acids and lysophosphatidylethanolamines. Study IV provided evidence in two large longitudinal cohorts for causal effects of type 2 diabetes and impaired insulin secretion on raised coronary artery disease risk.In conclusion, the Studies in this thesis provide new insights into the pathophysiology and adverse health consequences of IR and illustrate the value of combining traditional epidemiologic designs with recent molecular techniques and bioinformatics methods. The results provide limited evidence for the role of circulating proteins and small molecules in IR and require replication in separate studies and validation in experimental designs.
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| 7. |
- von der Heyde, Benedikt, 1988-
(författare)
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Translating Cardiac and Cardiometabolic GWAS Using Zebrafish
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Genome-wide association studies (GWAS) have identified thousands of loci associated with cardiac and cardiometabolic traits. However, the trait-associated variants usually do not clearly point to causal gene(s), mechanism(s) or tissue(s). Model systems that allow for a comprehensive and quick candidate gene screening are necessary, ideally in vivo. The overall objective of my thesis is to establish large-scale, imaged-based screens in zebrafish embryos and larvae to examine candidate genes for their effects on heart rate and rhythm, as well as on early-onset atherosclerosis and dyslipidemia.In Study 1, I prioritized 18 candidate genes in eight loci identified in a meta-analysis of GWAS for heart rate variability. Some of these genes were already known to be involved in cardiac pacemaking, whereas others require functional characterization.In Study 2, I established an experimental pipeline to examine genetic effects on cardiac rate and rhythm and used it to characterize orthologues of six human candidate genes for heart rate and rhythm. I confirmed known effects of rgs6 and hcn4, and established a role for KIAA1755 in HRV.In Study 3, I contributed to large-scale experiments to establish the zebrafish as a model system for early-onset atherosclerosis and dyslipidemia. Overfeeding and cholesterol-supplementation of the diet were shown to propel independent pro-atherogenic effects. Atherosclerotic burden was alleviated using commonly prescribed drugs in humans. Lastly, the effects of proof-of-concept genes known to be involved in lipid metabolism were examined and showed higher LDLc (apoea) and early-onset atherosclerosis (apobb1).In Study 4, I characterized genes in GWAS-identified loci for triglyceride levels for a role in lipid metabolism and early-stage atherosclerosis. I identified three previously unanticipated genes that influence triglyceride levels in zebrafish larvae. Several additional genes influence other cardiometabolic risk factors. Interestingly, two genes showed trends towards lower triglycerides levels (dock7 and lpar2a), with directionally opposite effects on vascular inflammation. This emphasizes that candidate genes need to be examined comprehensively to guide further mechanistic studies.
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| 8. |
- Åhman, Hanna Bozkurt, 1981-
(författare)
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Timed Up-and-Go Dual-Task Tests for Early Detection of Dementia Disorder
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dementia constitutes an important and growing public health concern. There is a need for new, simple, and inexpensive methods to detect dementia disorders early in the disease progression. For this purpose, dual-tasking, i.e., simultaneous performance of two tasks, has been proposed.The overall aim of this thesis was to explore if Timed Up-and-Go (TUG) dual-task (TUGdt) tests can be used for early detection of dementia disorder. Cross-sectional and longitudinal designs were used. Participants were recruited when undergoing memory assessment at memory clinics (patients) and through advertisements (controls). The TUGdt tests involved TUG combined with the cognitive tasks a) naming animals (TUGdt NA) and b) reciting months in reverse order (TUGdt MB). The tests were video recorded. Test outcomes were calculated using time scores and/or verbal performances. Additionally, the data collection comprised clinical tests and medical record reviews. Paper I included 90 patients who had carried out lumbar puncture as part of the memory assessment. By Spearman’s rank correlation, the TUGdt NA test outcomes “number of animals” and “animals/10 s” correlated negatively to the cerebrospinal fluid biomarkers t-tau and p-tau, suggesting that neurodegeneration is associated with dual-task performance. In Paper II, 298 patients and 166 controls participated. Logistic regression models showed that “animals/10 s” and “months/10 s” discriminated significantly between dementia, mild cognitive impairment (MCI), subjective cognitive impairment (SCI), and controls. Thus, TUGdt testing could be useful in diagnostic assessments. Paper III involved 172 patients, initially diagnosed with MCI or SCI, for whom diagnostic information was available after 2.5 years. Logistic regression showed inverse associations between “animals/10 s” and dementia incidence, particularly for patients <72 years (median age). For these younger patients, the predictive capacity of “animals/10 s” was excellent. Hence, TUGdt NA has potential for predicting dementia from SCI or MCI, particularly among younger patients. Paper IV included 166 controls for presenting TUGdt reference values in age- and sex-specific groups, and 43 controls for test-retest reliability. Reference values were calculated with quantile regression and may be useful in clinic and research. Intra-class correlation coefficients showed excellent reliability for time scores, while the other test outcomes were poor to good. “Animals/10 s” showed fair to good reliability despite being a ratio of other variables, which negatively affects reliability. In summary, TUGdt NA has the potential to be used for early detection of dementia disorder, and the test outcome “animals/10 s” merits further evaluation.
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