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- Alkaissi, Hammoudi, 1983-
(författare)
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Identification of candidate genes involved in Mercury Toxicokinetics and Mercury Induced Autoimmunity
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- BACKGROUND: Autoimmune diseases require the involvement and activation of immune cells and occur when the body builds up an immune response against its own tissues. This process takes place due to the inability to distinguish self-antigen from foreign antigen. Systemic autoimmunity represents an important cause of morbidity and mortality in humans. The mechanisms triggering autoimmune responses are complex and involve a network of genetic factors. Genome wide association study (GWAS) is a powerful method, used to identify genetic risk factors in numerous diseases, such as systemic autoimmune diseases. The goal of GWAS is to identify these genetic risk factors in order to make predictions about who is at risk and investigate the biological process of disease susceptibility. There are several valuable mouse models to investigate the underlying mechanisms causing systemic autoimmune diseases in which mercury induced autoimmunity (HgIA) is a well- established and relevant model. HgIA in mice includes development of autoantibodies, immune complex glomerulonephritis, lymphocyte proliferation, hypergammaglobulinemia and polyclonal B cell activation. In humans, mercury exposure accumulates with considerable concentrations in kidney, liver, and brain. Toxicokinetics of Hg has been studied extensively but the key for inter-individual variation in humans are largely unclear. Differences in accumulation of renal Hg between inbred mouse strains suggest a genetic inter-strain variation regulating retention or/and excretion of Hg.OBJECTIVES: To find loci and candidate genes associated with phenotypes involved in the development of autoimmunity and find candidate genes involved in the regulation of renal Hg excretion.METHODS: MHC II (H-2s) mice were paired (A.SW x B10.S) to obtain F2 offspring exposed to 2.0 or 4.0 mg Hg in drinking water for 6 weeks. Mercury induced autoimmune phenotypes were studied with immunofluorescence (anti-nucleolar antibodies (ANoA)), ELISA anti-DNP/anti-ssDNA (polyclonal B cell activation), anti-chromatin antibodies (ACA) (4.0 mg Hg), and serum IgG1 concentrations. Mercury accumulation in kidney was performed previously and data was included as phenotype. F2 mice exposed to 2.0 mg Hg were genotyped with microsatellites for genome-wide scan with Ion Pair Reverse Phase High Performance Liquid Chromatography (IP RP HPLC). F2 mice exposed to 4.0 mg Hg were genotyped with single nucleotide polymorphisms for genomewide scan with SNP&SEQ technology platform. Quantitative trait loci (QTL) was established with R/QTL. Denaturing HPLC, next generation sequencing, conserved region analysis and genetic mouse strain comparison were used for haplotyping and fine mapping on QTLs associated with Hg concentration in kidney, development of ANoA and serum IgG1 hypergammaglobulinemia. Candidate genes (Pprc1, Bank1 and Nfkb1) verified by additional QTL were further investigated by real time polymerase chain reaction. Genes involved in the intracellular signaling together with candidate genes were included for gene expression analysis.RESULTS: F2 mice exposed to 2.0 mg Hg had low or no development of autoantibodies and showed no significant difference in polyclonal B cell activation in the B10.S and F2 strains. F2 mice exposed to 4.0 mg Hg developed autoantibodies and significantly increased IgG1 concentration and polyclonal B cell activation (anti-DNP). QTL analysis showed a logarithm of odds ratio (LOD) score between 2.9 – 4.36 on all serological phenotypes exposed to 4.0 mg Hg, and a LOD score of 5.78 on renal Hg concentration. Haplotyping and fine mapping associated the development of ANoA with Bank1 (B-cell scaffold protein with ankyrin repeats 1) and Nfkb1 (nuclear factor kappa B subunit 1). The serum IgG1 concentration was associated with a locus on chromosome 3, in which Rxfp4 (Relaxin Family Peptide/INSL5 Receptor 4) is a potential candidate gene. The renal Hg concentration was associated with Pprc1 (Peroxisome Proliferator-Activated Receptor Gamma, Co-activator-Related). Gene expression analysis revealed that the more susceptible A.SW strain expresses significantly higher levels of Nfkb1, Il6 and Tnf than the less susceptible B10.S strain. The A.SW strain expresses significantly lower levels of Pprc1 and cascade proteins than the B10.S strain. Development of ACA was associated with chromosomes 3, 6, 7 and 16 (LOD 3.1, 3.2, 3.4 and 6.8 respectively). Polyclonal B cell activation was associated with chromosome 2 with a LOD score of 2.9.CONCLUSIONS: By implementing a GWAS on HgIA in mice, several QTLs were discovered to be associated with the development of autoantibodies, polyclonal B cell activation and hypergammaglobulinemia. This thesis plausibly supports Bank1 and Nfkb1 as key regulators for ANoA development and HgIA seems to be initiated by B cells rather than T cells. GWAS on renal mercury excretion plausibly supports Pprc1 as key regulator and it seems that this gene has a protective role against Hg.
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| 2. |
- Dutta, Ravi Kumar, 1983-
(författare)
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Genetic and molecular alterations in aldosterone producing adenomas
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aldosterone producing tumors (APA, also known as Conn tumors) are adrenal tumors that overproduce aldosterone, a hormone that regulates the sodium levels in blood and contributes to blood pressure (BP) regulation. Excessive production of aldosterone causes hypertension and approximately 5-15% of hypertensive patients have hyperaldosteronism, known as primary aldosteronism (PA). Major causes of PA are bilateral adrenal hyperplasia (BAH) or aldosterone producing adenoma (APA) and about 30% of PA patients have APAs. In most cases, the disease is unilateral, in rare case bilateral. Patients with APA are often detected when they have elevated blood pressure (BP>160/100mmHg) or when BP cannot be controlled with drugs. Surgery dramatically normalizes or lowers BP in patients with APA.In this thesis, we first explored the mutation frequency in susceptibility genes in sporadic APAs. About 60% of APAs displayed complementary mutations in the KCNJ5, ATP1A1, ATP2B3, CTNNB1, CACNAID and CLCN2 genes (Paper I, II & III). Copy number variation analysis of 35 APAs identified amplification of chromosome 10q24.31 in two tumors, where CALHM1-3- genes encoding for potential calcium ion channels are located. Only CALHM2 is expressed in adrenals and sequencing of CALHM2 revealed three different heterozygous sequence variants; c.341_42delCT (CALHM2P114Rfs*12), c.286G>A (CALHM2A96T) and c.580G>A (CALHM2V194M) in 5 APAs. CALHM2 is expressed in the mitochondrial membranes and Ca2+ imaging revealed that CALHM2 has selection of another ion rather than Ca2+. The genetic variant CALHM2V194M converts CALHM2 into a non-selective channel and results in higher Ca2+ conductance in mitochondria. We further found that loss of CALHM2 function upregulates REELIN/LRP8 signaling activating β-catenin dependent transcription of target genes (Paper II). In Paper IV, we investigated Scandinavian APA cases (n=35) and Swedish controls (n=60) for GWAS and discovered a susceptibility locus on chromosome Xq13.3 in a 4 Mb region to be significantly associated with APAs. Significance level was still same after genotyping the sentinel SNP rs2224095 in a replication cohort of APAs (n=52) and controls (n=740). Sequencing of an adjacent gene of the sentinel SNP, MAGEE1, identified a rare variant in one APA, which is complementary to other mutations in our primary cohort. In Summary, our studies have increased the knowledge of molecular genetic events in APAs. The results may contribute to find future non-surgical treatments for APAs.
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| 3. |
- Lysiak, Malgorzata, 1989-
(författare)
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Biomarkers In Brain Tumors With Focus On Glioblastoma
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The primary brain tumors, gliomas, are not very common but they are deadly. Each year in Sweden around 500 patients will be diagnosed with a glioma and unfortunately most of them will have the most aggressive type, glioblastoma (GBM). Median survival, even if treated, is poor (14-17 months). Males are diagnosed up to 60% more often than females and they often have a worse prognosis. GBM affects mainly older patients and treatment includes radiochemotherapy with temozolomide (TMZ). The only known predictive biomarker for TMZ treatment is methylation of the O6-methylguanine DNA methyltransferase (MGMT) promoter and patients with methylated MGMT have better outcomes. There is a great need for biomarkers to decipher existing sex differences and others that identify patients that will benefit from radiotherapy (RT) or TMZ despite of unmethylated MGMT. Papers I-III are focused on investigating sex differences in GBM and in Paper IV we examined the methylation-based biomarkers used in diagnostics, on patients from the Nordic trial with exceptionally good and poor survival when treated with TMZ or RT. Loss of the Y chromosome (LOY) in male’s blood cells is associated with aging and, among other diseases, with cancer. We looked at 10 genes located on chromosome Y in 105 males with GBM treated with TMZ concomitant with RT and found that they are often deleted. Detected LOY, as well as deletion of the sex determining region Y (SRY) gene were associated with shorter overall survival. Low SRY gene expression analyzed in an additional cohort of 219 samples from The Cancer Genome Atlas (TCGA) was also associated with a shorter survival.In Paper II we re-analyzed data from three cohorts to compare the frequency of MGMT methylated tumors in males and females and investigated whether sex is an important factor associated with patient’s survival. This was done in a GBM cohort from the randomized, phase 3 Nordic trial, which included patients 60 years or older, treated with standard RT (60Gy) vs. hypofractionated RT vs. TMZ given in up to six 4 weekly cycles; in a population-based cohort, treated with TMZ concomitant with RT and an excerpt of the TCGA cohort of patients treated with different modalities. In all three cohorts there was a higher fraction of MGMT methylated tumors in females and MGMT methylation was predictive of longer survival for those treated with an alkylating agent, such as TMZ.The third study investigated the androgen receptor (AR), located on chromosome X as a potential sex susceptibility factor for GBM. We found that the gene encoding for AR can be amplified or deleted in GBM, and these changes are more common in females. The AR gene expression was enhanced in GBM but did not differ between sexes. At the same time, in a separate analysis for males and females, we found that high AR expression is associated with shorter survival in females and longer survival in males Also, the methylation sites in the AR promoter that correlated with gene expression are sex specific. In Paper IV we included 59 patients from the Nordic trial, equally divided by the treatment arms and MGMT methylation status, with good prognostic factors and with long or short survival. We performed genome-wide methylation analysis and identified differentially methylated sites between those with long and short survival for the TMZ treated, MGMT methylated samples, as well as the 60Gy, MGMT unmethylated and 34Gy MGMT methylated samples. This small pilot study was unable to discern any differentially methylated sites in TMZ treated samples with unmethylated MGMT, associated with long or short survival. By using a methylation-based diagnostic classifier, we were able to detect a misclassified sample that was not a GBM. Lastly, we calculated so called ‘epigenetic age’ of the tumor tissue based on the methylation data and using three different algorithms and found that in all treatment groups short-term survivors tended to have lower epigenetic age, though these results were not significant and need verification in a larger cohort.In summary, this thesis advances our knowledge on the molecular differences between male and female GBM and the association between these alterations and patients’ survival. Our results also suggest that there are potential methylation-based biomarkers apart from the MGMT promoter methylation, that can be used to distinguish between patients with good and poor prognosis, for instance, the epigenetic age.
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| 4. |
- Malmström, Annika, 1957-
(författare)
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Studies for Better Treatment of Patients with Glioma
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In Sweden annually over 500 people will be diagnosed with the malignant brain tumor glioma. They are graded from I-IV. The majority are glioblastoma (grade IV) (GBM), these being the most aggressive type. Median survival for those treated with standard of care is expected to be around 15 months. This tumor will mainly affect those 60 years or older.The studies in this thesis focus on treatment of patients with malignant gliomas grade III and IV. The aim of the studies is to improve the care of glioma patients. Papers I and II explored different therapeutic options in randomized trials, to facilitate individualized treatment recommendations. Findings from studies I and II, together with additional trials, demonstrated the importance of analyzing the tumor marker O6-methylguanine DNA methyltransferase (MGMT) methylation status for survival of GBM patients treated with Temozolomide (TMZ). The third paper investigated how the analysis of this marker is implemented internationally.The first study (paper I, Nordic trial) investigated treatment options for patients 60 years or older with GBM. The trial compared standard radiotherapy (SRT) over 6 weeks versus hypofractionated radiotherapy (HRT) over 2 weeks versus single agent TMZ administered in up to six 4 weekly cycles. In all, 342 patients were included in the trial. This study demonstrated that those randomized to TMZ had superior survival as compared to SRT. In addition, quality of life (QoL) data also suggested a better QoL for TMZ treatment than for radiotherapy. The benefit of TMZ treatment seemed to be limited to those with the tumor molecular marker MGMT methylated (inactivated).The second trial (paper II, Neoadjuvant trial) studied whether integrating TMZ treatment with SRT for patients younger than 60 years with GBM (grade IV) and astrocytoma grade III would confer a survival benefit, if administered postoperatively, before the start of SRT (neoadjuvant). TMZ was provided for 2-3 four weekly cycles followed by SRT to patients randomized to neoadjuvant treatment and was compared to postoperative SRT alone. Although this trial could not illustrate any advantage of delaying the start of SRT while administering TMZ for the study cohort in general, for those included as astrocytoma grade III the median survival was found to be superior by 5 years when randomized to neoadjuvant TMZ. This trial also confirmed the importance of MGMT promoter methylation for the efficacy of TMZ.The third study (paper III) investigated international practices for analyzing tumor MGMT promoter methylation status. MGMT analysis can be conducted by various laboratory methods, which in some cases can provide opposing results regarding the MGMT methylation status of the patient´s tumor. This can lead to incorrect treatment recommendations. To establish which methods and cut-offs that are regularly used to determine tumor MGMT status in the clinic, an international survey was provided to those working in the field. We also inquired about opinions regarding an international consensus on how MGMT should be tested. The 152 respondents reported several methodologies and different cut-off levels also for the same method. A majority of respondents warrant international guidelines.In conclusion, the results of the 2 randomized trials contribute to individualized treatment recommendations for patients affected by GBM or astrocytoma grade III. The results of the survey regarding analyses of MGMT clarify the current problematic situation. The request of the respondents regarding international guidelines might contribute to their future development, so that personalized treatment recommendations can be improved.
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| 5. |
- Nord, Maria
(författare)
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Levodopa pharmacokinetics -from stomach to brain : A study on patients with Parkinson’s disease
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Parkinson’s disease (PD) is one of the most common neurodegenerative disorders and it is caused by a loss of dopamine (DA) producing neurons in the basal ganglia in the brain. The PD patient suffers from motor symptoms such as tremor, bradykinesia and rigidity and treatment with levodopa (LD), the precursor of DA, has positive effects on these symptoms. Several factors affect the availability of orally given LD. Gastric emptying (GE) is one factor and it has been shown to be delayed in PD patients resulting in impaired levodopa uptake. Different enzymes metabolize LD on its way from the gut to the brain resulting in less LD available in the brain and more side effects from the metabolites. By adding dopa decarboxylase inhibitors (carbidopa or benserazide) or COMT-inhibitors (e.g. entacapone) the bioavailability of LD increases significantly and more LD can pass the blood-brain-barrier and be converted to DA in the brain. It has been considered of importance to avoid high levodopa peaks in the brain because this seems to induce changes in postsynaptic dopaminergic neurons causing disabling motor complications in PD patients. More continuously given LD, e.g. duodenal or intravenous (IV) infusions, has been shown to improve these motor complications. Deep brain stimulation of the subthalamic nucleus (STN DBS) has also been proven to improve motor complications and to make it possible to reduce the LD dosage in PD patients.In this doctoral thesis the main purpose is to study the pharmacokinetics of LD in patients with PD and motor complications; in blood and subcutaneous tissue and study the effect of GE and PD stage on LD uptake and the effect of continuously given LD (CDS) on LD uptake and GE; in blood and cerebrospinal fluid (CSF) when adding the peripheral enzyme inhibitors entacapone and carbidopa to LD infusion IV; in brain during STN DBSand during oral or IV LD treatment.To conclude, LD uptake is more favorable in PD patients with less severe disease and GE is delayed in PD patients. No obvious relation between LD uptake and GE or between GE and PD stage is seen and CDS decreases the LD levels. Entacapone increases the maximal concentration of LD in blood and CSF. This is more evident with additional carbidopa and important to consider in avoiding high LD peaks in brain during PD treatment. LD in brain increases during both oral and IV LD treatment and the DA levels follows LD well indicating that PD patients still have capacity to metabolize LD to DA despite probable pronounced nigral degeneration. STN DBS seems to increase putaminal DA levels and together with IV LD treatment also increases LD in brain possibly explaining why it is possible to decrease LD medication after STN DBS surgery.
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