Coming dissertations at Uppsala university
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Effects of mast cell proteases on lung structural cells : Implications for asthma
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-524961
Asthma is a prevalent chronic inflammatory condition that impacts the airways of the lungs. Its hallmark symptoms include wheezing, difficulty of breathing, chest tightness and coughing. Allergic asthma represents the most common form of this condition. While previous investigations have established a pivotal role of mast cells in asthma, the precise underlying mechanisms remain unclear. Mast cells are immune cells with a high content of secretory granules, containing a diverse array of bioactive substances such as histamine, cytokines, proteoglycans, and mast cell-restricted proteases such as tryptase, chymase, and carboxypeptidase A3. This thesis aims to investigate the regulatory role of mast cell-restricted proteases in modulating airway responses across the three layers of the airway wall, including human lung fibroblasts (HLF), human small airway epithelial cells (HSAEC), and human bronchial/tracheal smooth muscle cells (SMC).
In Paper I, primary HLFs were subjected to in vitro challenges with two distinct mast cell proteases: human β-tryptase and recombinant human chymase. The chymase-treated group exhibited significant morphological alterations compared to minimal effects observed in the tryptase-treated group. Additionally, chymase demonstrated the ability to modulate the extracellular matrix (ECM), cytokine, and chemokine output from primary HLFs. Transcriptome analysis revealed that chymase induced a proinflammatory gene transcription profile in HLFs, whereas tryptase had minimal effects.
In Paper II, the effect of mast cell proteases on primary HSAEC monolayers was evaluated. The HSAECs were relatively refractory to tryptase. In contrast, chymase was found to suppress the expression of ECM-related genes, degrade fibronectin, and reduce the migratory capacity of HSAECs. Chymase also degraded the cell-cell contact protein E-cadherin on the epithelial cell surface.
In Paper III, the impact of mast cell proteases on primary human SMCs was investigated. Chymase induced a profound reduction in SMC metabolic activity and cell proliferation, while tryptase had minimal effects. Our findings also revealed that chymase partially suppressed SMC contractility and enhanced the migratory capacity of airway SMCs. Chymase also caused reorganization of major cytoskeletal components and degraded tight junction proteins expressed by SMCs.
Our investigations increased the current knowledge of the effects of mast cell proteases on lung structural cells. These findings have the potential to unravel novel mechanisms of relevance in the pathology of asthma.
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Aspects of improving and maintaining physical activity in patients with hip or knee osteoarthritis
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-526506
Aim: This thesis aims to enhance knowledge of how people with osteoarthritis should be managed and supported in order to increase and maintain physical activity in the long-term.
Method: Study I and study II was based on a randomised controlled study (RCT) including 141 osteoarthritis patients. The short and long-term effect of an individualised physical activity on prescription intervention compared with individualised advice about physical activity were evaluated. The primary outcome was physical activity and secondary outcomes were fitness/performance, pain and quality of life, evaluated at 6, 12 and 24 months. In Study III, 7-day diaries were evaluated regarding which forms of physical activity i.e. walking, swimming, cycling, gardening etc. the patients chose themselves and maintained after one and two years. In addition were evaluated, which category these activities belonged to: aerobic, muscle strength, mind-body or everyday activity, and whether there were differences in characteristic of the patients in the different forms. In study IV responsiveness of function, how well instruments captured an improvement, one year after a physical activity intervention was measured. Two unilateral performance-based tests were compared with a bilateral performance-based test and with questionnaires about function.
Results: The RCT provided no evidence that individualised physical activity on prescription differ from individualised advice on physical activity in improving short and long-term physical activity, function, pain and quality of life (Study I and II). Walking was the form of physical activity performed most frequently and best maintained after 12 and 24 months. Walking were preferred by women, older individuals and individuals with weak legs while men also preferred everyday activity and cycling. Few patients preferred strength training (Study III). The maximal step-up test (one-leg testing) was more responsive to change in physical function (SMD effect size 0.57) compare to the bilateral 30-second chair-stand test (0.48) (Study IV).
Conclusion: There is still absence of evidence for any particular physical activity intervention to effectively increase physical activity in the long-term in osteoarthritis patients. Individual counselling with support to choose preferred physical activities that are easy to perform in daily life may be a beneficial approach for long-term maintenance.
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Unveiling the Mechanisms for Statin-Associated Sleep Problems and Myopathy : Statin Medication, Sleep Problems and Myopathy Mechanisms
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-525998
Statins (3-hydroxy-3-methylglutaryl-CoA reductase, HMGCR, inhibitors) comprise the gold standard for the management of hypercholesterolaemia and prevention of cardiovascular disease (CVDs). However, they are accompanied by potential adverse effects, notably muscle pain and sleep disturbance. These side effects can significantly impact patient adherence to statin therapy and thus increase the risk for CVDs. Despite extensive research, the underlying mechanisms of statin-associated myopathy and sleep disturbance are poorly understood.
In Paper I, we conducted a cross-sectional cohort study to investigate the association between statin use and genetic variants for HMGCR with the risk for insomnia and chronotype using UK biobank cohort data. Statin use, insomnia and chronotype were assessed by a self-report touchscreen questionnaire. Statin treatment was associated with an increased risk of insomnia compared to controls, while genetic variants for HMGCR inhibition were associated with a reduced risk for insomnia. No association with late evening chronotype were observed with statin use or genetic variants for HMGCR.
In Paper II, we employed Drosophila melanogaster to examine the effect of statins and the role of central inhibition of Hmgcr on sleep behaviour. Flies were treated with fluvastatin for five days and Hmgcr was knocked down in pan neurons and pars intercerebralis (PI), equivalent to the mammalian hypothalamus. Sleep patterns were recorded and analysed. Pan-neuronal- as well as PI inhibition of Hmgcr recapitulates fluvastatin-induced enhanced sleep latency and reduced sleep duration.
In Paper III, we deciphered the underlying mechanisms for statin-induced myopathy using D. melanogaster. We found that fluvastatin treatment induced muscular damage, mitochondrial phenotypes, lowered locomotion, reduced climbing activity and was associated with lipotoxicity, impaired muscle differentiation and regeneration, and lowered expression of skeletal muscle chloride channels. Interestingly, selective inhibition of skeletal muscle chloride channels recapitulates fluvastatin-induced myofibrillar damage and lowered climbing activity, while selective Hmgcr inhibition in the skeletal muscles recapitulates fluvastatin-induced mitochondrial round-shape and reduced locomotion activity.
In Paper IV, we explored the sequential events of myofibril damage and mitochondrial phenotypes associated with fluvastatin and examined whether inhibition of Hmgcr in the skeletal muscles recapitulates fluvastatin effects on mitochondrial respiratory parameters using D. melanogaster. Acute fluvastatin treatment was associated with reduced mitochondrial content and roundness of the mitochondria without noticeable myofibrillar damage. Intriguingly, chronic fluvastatin treatment was associated with stronger mitochondrial phenotypes along with severe myofibrillar damage, which suggests that mitochondrial phenotypes precede myofibrillar damage. Moreover, selective Hmgcr inhibition did not impact mitochondrial respiratory functions.