Lääketieteellinen tiedekunta


Recent Submissions

  • Mölsä, Markos (Maanpuolustuskorkeakoulu, 2016)
    Rapid and accurate detection and diagnosis of infectious agents is crucial in preparedness for diseases and biothreats. Due to a lack of rapid diagnostic capabilities, diseases and outbreaks may remain undetected. Currently available point-of-care tests often lack the sensitivity to directly detect pathogens in samples, thus there is a need for quick and robust solutions for identification of pathogens in order to mount appropriate responses. The spread of infectious diseases is a global challenge and outbreaks and epidemics place great strains to healthcare and economy. Several of the pathogens causing these diseases are not only major public health issues but pose also potential biothreats. This thesis describes the performance of field-capable gene amplification methods in the detection of three bacterial pathogens (Francisella tularensis, Bacillus anthracis, and Yersinia pestis) and a viral pathogen causing respiratory infections (influenza A virus). The methods include on-site nucleic-acid extraction and rapid real-time PCR amplification of selected gene regions in these pathogens occurring in animal tissue and human nasopharyngeal samples. Results confirm that currently-available portable thermocyclers can generate highly accurate diagnostic results in field. Furthermore, genetic characterization of a common respiratory pathogen, adenovirus is presented by investigating adenoviruses circulating in Finnish garrisons with molecular sequence analysis. Genetic characterization of a pathogen is also an important tool in investigations of alleged use of biological weapons. The presented methodology and workflow serves as an effective tool for decision makers in biothreat preparedness and in case of deliberate spread of pathogens.
  • Lampinen, Anita (Helsingin yliopisto, 2016)
    Angiogenesis, the growth of new blood vessels, is essential during embryonic development, but it is also involved in numerous human diseases, including cancer. Vascular endothelial growth factors (VEGFs) and their receptors (VEGFRs), as well as angiopoietin growth factors (Ang1, Ang2) together with their Tie1 and Tie2 tyrosine kinase receptors are essential regulators of angiogenesis and lymphangiogenesis. These endothelial specific pathways also control vascular permeability. Ang1 stimulates the translocation of Tie receptors into endothelial cell-cell contacts resulting in endothelial stabilization, while Ang2 stimulates tumor angiogenesis, metastasis and vascular leakage, and Ang2 expression is elevated in several diseases, including cancer. VEGF-targeted therapies have been in clinical use for more than a decade, whereas Ang-Tie targeted drugs are in clinical development for cancer. However, problems with anti-angiogenic therapies are associated with drug related resistance, and biomarkers that would predict patient responses are lacking. In this study, we focused to discover molecular mechanisms that regulate the Ang-Tie signalling system, and how this pathway functions during tumor metastasis and endotoxemia. Second, we sought to investigate Ang2 expression in human metastatic renal cell carcinoma (mRCC), and its potential as a biomarker for anti-angiogenic therapies. In summary, our results demonstrate that Tie1 is essential for angiopoietin signalling and vascular remodelling, by interacting with Tie2, within a distance of 10 nm, and regulating the subcellular trafficking of Tie2. Tie1-Tie2 interaction is dependent on the EC-extracellular matrix (ECM) adhesion receptor, alpha5beta1-integrin, and silencing of alpha5beta1-integrin inhibited also Tie receptor activation and downstream signalling. Second, a therapeutic anti-Ang2 antibody was found to promote vessel integrity and inhibit tumor metastasis, by inhibiting Ang2 binding to Tie2 and inducing internalization of the Ang2-Tie2 signalling complexes in ECs. Third, Ang2 expression was determined in the vasculature of RCC tumors, and correlated with clinical parameters, including response to anti-angiogenic therapy and survival. These results advance the current understanding of the function of the Ang-Tie pathway in the vasculature, and call for more thorough studies of Ang2 in human RCC.
  • Kumpu, Minna (Helsingin yliopisto, 2016)
    Respiratory tract infections account for significant part of total illness episodes, physician consultations and days off from day care, school or work, thus incurring a significant personal and socio-economic burden. Viruses cause most of the acute infections of the respiratory tract, and there is lack of effective preventive and treatment options available against almost all of the over 200 different viral pathogens. Nutritional interventions are an increasingly researched option for reducing the infection burden, and of these probiotics are among the ones shown most promise. The aim of this work, consisting of three double-blind randomized controlled clinical trials in children and adults, was to investigate whether probiotic Lactobacillus rhamnosus GG would reduce the symptoms of respiratory tract infections and nasopharyngeal presence of respiratory viruses, as well as to explore factors hypothesized to have an impact on probiotic efficacy: the pharyngeal colonization of L. rhamnosus GG and the viability of the probiotic strain. In young adult tonsillectomy patients, L. rhamnosus GG was analysed from palatine tonsil samples and results compared to the faecal recovery of GG after three weeks daily consumption of placebo or L. rhamnosus GG as a single strain or as a part of a multispecies combination. L. rhamnosus GG was recovered in the tonsil tissue of 40% of the subjects in the GG group, 41% in the multispecies group and 30% in the placebo group. The results suggest that individual variation exists in the ability of the probiotic to adhere to the tonsil tissue, as the compliance of study product consumption was confirmed by the analysis of the faecal recovery of the strain and counting of leftover study products. Most of the subjects in the control group with L. rhamnosus GG harboured from the tonsil tissue had the strain recovered from the faecal sample already at the start of the intervention, indicating that persistent colonization could be a factor behind positive tonsillar recoveries in the control group. In a 28-week prospective trial on children aged 2 6 years attending day care in Finland, milk supplemented with L. rhamnosus GG was not able to reduce respiratory tract infections compared to the control group. Analysis on the completed cases subgroup, excluding subjects with intestinal L. rhamnosus GG colonization originating from outside the trial, suggested that children in the probiotic group had one day less per month with respiratory symptoms compared to the control group, but this exploratory finding warrants further research for confirmation. In a subgroup of children who visited the study physician due to an infection during the trial, the presence of 14 respiratory viruses was analysed from nasopharyngeal swab samples. L. rhamnosus GG did not reduce the occurrence of respiratory viruses, or the number of infection symptoms observed at the time of the viral findings. In this subgroup of more symptomatic children, subjects in the probiotic group had fewer days with respiratory symptoms than children in the control group, but number of study physician visits was not different between the groups, thus suggesting that L. rhamnosus GG might be able to reduce only the symptoms of the less severe infections treated at home in the more symptomatic subjects. The potential of the experimental rhinovirus challenge model in studying probiotic efficacy in viral infections was tested in a 6-week trial on live and inactivated L. rhamnosus GG in adults. In this pilot study, the subjects were intranasally inoculated with experimental rhinovirus mid-intervention. Occurrence and severity of cold symptoms and number of subjects with positive rhinovirus culture and rhinovirus infection were the lowest in the group receiving live L. rhamnosus GG, but differences were not statistically significant. Taken together, L. rhamnosus GG was overall not effective in reducing the symptoms of respiratory tract infections, or occurrence of respiratory viruses in the nasopharynx of symptomatic children, but appeared to reduce symptoms in specific subgroups within the study cohort. It was demonstrated that L. rhamnosus GG can be recovered from the tonsil tissue of some but not all subjects after oral consumption, thus warranting future research on the role of the probiotic recovery in infection outcomes. The experimental rhinovirus model was demonstrated a potential controlled approach to studying the efficacy of probiotics, and the pilot study on the model indicated that live L. rhamnosus GG was more promising than the inactivated strain in reducing respiratory infections, but further research is needed to confirm the preliminary findings.
  • Ryhänen, Eeva (Unigrafia, 2016)
    The aim of this thesis on primary hyperparathyroidism (PHPT) was to improve preoperative imaging, to evaluate the effect of parathyroidectomy on health-related quality of life, and to investigate parathyroid carcinoma and its incidence in Finland. PHPT is due to a parathyroid adenoma (in 80%), hyperplasia in two or more glands (15 20%) or, rarely, to parathyroid carcinoma. The only definitive treatment is an operation, which is indicated if surgical criteria are met. Preoperative imaging localizing the pathological gland(s) in the neck allows 70% of parathyroidectomies to be targeted. Otherwise, all four parathyroid glands are explored. In our retrospective study of 269 PHPT patients who have undergone primary operation, the planar 123iodine/99mTechnetium(Tc)-sestamibi scintigraphy and 99mTc-sestamibi scintigraphies were accurate in 61% and 34% of patients, respectively. The cure rate was 93%, but 61% in those with multigland disease (16% of the cohort). Before reoperation, preoperative imaging decreases the risk of surgery complications is higher. In our prospective study of 21 PHPT patients planned for reoperation, the imaging results were accurate in 59% of 123iodine/99mTc-sestamibi scintigraphies, in 19% of 99mTc-sestamibi-SPECT/CT, in 65% of 11C-methionine-PET/CT, and in 40% of selective venous sampling studies (SVS). False positives were present in nearly half (9 out of 20) of SVSs but only in one PET/CT study. In our prospective study of 124 PHPT patients, the preoperative health-related quality of life (HRQoL) studied with the 15D- instrument was lower than in a comparable sample of the general Finnish population (n=4295). It increased after surgery and was sustained in a one-year follow-up. Serum calcium and parathormone concentrations did not correlate with the preoperative level or the postoperative change of HRQoL. Parathyroid carcinoma (PC) is an extremely rare endocrine cancer. Our national research group collected and re-evaluated all 32 PC cases and their tissue specimen diagnosed in Finland between 2000 and 2011. We compared these to 28 atypical adenoma and 72 age- and gender-adjusted parathyroid adenoma cases. We noticed that the incidence of PC has markedly increased in recent decades, with one case in 1 000 000 persons per year between 2010 and 2013. Tissue Micro Array (TMA) analysis was performed on all tissue samples. Mutation analysis of the CDC73 gene related to PC, performed on 56% and 57% PC and atypical adenomas respectively, was positive in 6% in both groups. PC patients had more severe clinical presentation of the disease compared to other subgroups. The presence of lymph node metastasis at diagnosis, negative parafibromin staining, and a proliferation index of over 5% seemed to be related to a more aggressive disease. At the seven-year follow-up, 21% had a recurrence of PC, and half of the patients were operated on 2-4 times. The mortality of the PC group did not differ from other subgroups. In the atypical adenoma group, one had a recurrence and two had a persistent disease, all requiring reoperations. In conclusion, the use of a thyroid-specific tracer like 123Iodine improves the accuracy of planar 99mTc-MIBI scintigraphy. Before reoperation, if ultrasound and scintigraphy findings are discordant or negative, 11C-methionine-PET/CT is recommended. The HRQoL in PHPT patients is reduced compared to healthy controls, but it improves significantly after operation. The incidence of parathyroid carcinoma is increased and it is often related to a severe PHPT. Although PC patients need reoperations, the prognosis of our cohort seems better than previously reported.
  • Salonsalmi, Aino (Helsingin yliopisto, 2016)
    Alcohol drinking is a major potentially preventable risk factor for health and wellbeing worldwide. Alcohol drinking has increased markedly from the late 1960s in Finland until 2007. Alcohol-related causes of death and morbidity are common, especially among the working-age population. The majority of Finnish heavy drinkers are employed and there is a need to assess the contribution of alcohol drinking to health-related functioning and work disability using longitudinal data including several drinking habits. The aim of this study was to examine the associations between alcohol drinking, health-related functioning and work disability among ageing municipal employees. This study is part of the Helsinki Health Study. The baseline data were collected in 2000-02 among 40- to 60-year-old employees of the City of Helsinki (n=8960, response rate 67%). A follow-up survey was conducted in 2007 (n=7332, response rate 83%). The survey data were linked with sickness absence data, derived from the employer s personnel register, and with data on disability retirement, derived from the Finnish Centre for Pensions, among 78% and 74% of participants consenting to internal and external data linkages. Alcohol drinking was measured by weekly average drinking, frequency of drinking, binge drinking and problem drinking assessed by the CAGE scale. Logistic regression, Poisson regression and Cox regression were used in analysing the data. Heavy weekly average drinking, binge drinking and problem drinking were all associated with poor mental functioning, whereas concerning physical functioning associations were found for problem drinking only and non-drinkers also had an increased risk. Heavy weekly average drinking, binge drinking and problem drinking were associated with both self-certified and medically confirmed sickness absence from work with the exception of binge drinking among men. The association between weekly average drinking and medically confirmed sickness absence was U-shaped, both non-drinkers and heavy drinkers having increased risks compared to moderate drinkers. Working conditions had no major contributions to the associations, although psychosocial working conditions somewhat attenuated the associations, especially among men. When studying changes in alcohol drinking, associations were found for self-certified sickness absence more often than for medically confirmed sickness absence, as associations for the latter were mainly explained by health and other health behaviours. Also, reduced alcohol drinking and previous problem drinking increased the risk of sickness absence. Alcohol drinking was strongly associated with disability retirement due to mental disorders, whereas no associations were found for musculoskeletal diseases. Throughout the study, alcohol drinking showed the strongest associations with poor mental health. Problem drinking was the drinking habit with the most widespread associations with poor health-related functioning and work disability. The results of the study indicate that alcohol drinking is a risk factor for poor health-related functioning and work disability in the middle-aged working population. Heavy drinking, binge drinking and problem drinking were all associated with poor health-related functioning and work disability, but problem drinking showed the strongest and most widespread associations. The study suggests that problem drinking should be assessed in addition to the overall amount of drinking in future studies and clinical settings. The study highlights the importance of alcohol drinking for poor mental health and calls for recognition and early prevention of heavy alcohol drinking among both the occupational and primary health care systems.
  • Hu, Yizhou (Helsingin yliopisto, 2016)
    Netrin-4 is a secreted laminin-related protein, which was originally observed to guide neuronal axons during neuronal development. Although netrin-4 has been detected in various tumor types, its biological function and the underlying molecular mechanism in tumor cells has remained largely unknown. Glioblastoma multiforme (GBM) is the most common primary tumor of central nervous system. So far, there is no remedy to cure this fatal disease, but the efficacy of temozolomide (TMZ) - an orally taken alkylating agent - has been demonstrated in the treatment of GBM. We confirmed a physical association between β4 integrin and netrin-4. This association contributed to both mitogenic effects and the activation of AKT-mTOR signaling. These observations suggest that integrin β4 is involved in the stimulatory effect of netrin-4 on cell proliferation, possibly via AKT- mTOR pathway. TMZ induces GBM cell senescence via triggering DNA damage and mismatch repair. The sensitivity of GBM cells to TMZ is interfered by many factors including O-6-methylguanine-DNA methyltransferase (MGMT) expression and AKT activation. In two GBM cell lines devoid of MGMT expression, we found that netrin-4/ITGB4 protects GBM cells from TMZ induced senescence, probably via rescuing TMZ triggered AKT inactivation. In addition, we observed interfering netrin-4/neogenin interaction disturbed activation of integrin downstream signaling, inhibited cytoskeleton rearrangement, and attenuated GBM cell invasion. Current results suggest that netrin-4/ITGB4 interplay regulates cell proliferation and enhances TMZ resistance in GBM cells via activating AKT pathway. Furthermore, my current results reveal a pivotal role of netrin-4 in the signaling crosstalk of laminin-binding integrins and netrin receptors. These findings reveal a non-canonical crosstalk between netrin and integrin signaling, and suggest that blocking netrin-4 may become a promising therapy in GBM treatment.
  • Videman, Mari (Helsingin yliopisto, 2016)
    Background: In utero exposure to antiepileptic drugs (AEDs) or to serotonin reuptake inhibitors (SRIs) is associated with structural and functional teratogenesis. The aim of this thesis was to investigate whether prenatal SRI or AED exposure changes newborn brain activity. In addition, we wanted to evaluate the effects of prenatal AED exposure on visual attention and emotion-related attention in infancy and to characterize functional connectivity in healthy term newborns. Material and Methods: A prospective cohort of infants with in utero AED exposure (n=56) and similar cohort with in utero SRI exposure (n=22) were compared to infants without drug exposure (n=67). Background information, exposure data, pregnancy outcome, neuropsychological evaluation of the mothers (AED), mood and anxiety of mothers (SRI), and neurological status of the infants were assessed at neonatal age and at 7 months-of-age. Electroencephalography (EEG) was used to evaluate newborn cortical function and an eye-tracking-based test to assess the infants visual attention and orienting to faces. Results: Neurological assessment showed subtle abnormalities in both the AED- and the SRI-exposed newborns. Early language abilities were impaired at 7 month-of-age in infants with in utero carbamazepine, oxcarbazepine, and valproate exposure. The general speed of visuospatial orienting or attentional bias for faces did not differ between AED-exposed and control infants. Computational EEG analyses demonstrated several differences between the exposed and control newborns. AED-exposed newborns had lower amplitudes at multiple frequencies, higher interhemispheric synchrony in frontal versus posterior parts of the brain, more even distribution of interhemispheric interval durations, and fewer frontal alpha bouts of typical duration. In the SRI-exposed newborns, interhemispheric connectivity was reduced, cross-frequency integration was lower, and frontal activity at low-frequency oscillations was reduced. These effects were unrelated to maternal depression or anxiety. In unexposed newborns, functional connectivity was shown to vary significantly between vigilance states and to mature rapidly after normal birth. Conclusions: The results suggest that prenatal AED and SRI treatment may change newborn brain function and affect early neonatal neurologic status. In addition, AED exposure may impair verbal abilities in a way that can be detected already in infancy. Early development of visual attention as well as orienting and face perception were spared after in utero AED exposure. Results in the newborn connectivity study support the view that emerging functional connectivity exhibits fundamental differences between sleep states during the neonatal period. The findings suggest that interference in the development of an activity-dependent network may be a possible mechanism to explain the link from prenatal AED and SRI exposure to later adverse functional effects.
  • Peltola, Erno (Helsingin yliopisto, 2016)
    The main purpose of this thesis was to evaluate the incidence, injury patterns and MRI and MDCT findings of the acute trauma patients with knee dislocation, patellar dislocation, Segond fracture and reverse Segond fracture, and also to examine dual-energy computed tomography in evaluating cruciate ligament injuries. At a level 1 trauma center, emergency department acute trauma patients MDCT or MRI examinations were retrospectively evaluated and surgical findings or MRI served as the reference standard for intra-articular injuries. The annual incidence of knee dislocation due to low energy trauma in overweight patients was found to be significant, about 1.0 per million, and these patients had no injuries to the popliteal tendon and no irreversible peroneal nerve injuries, otherwise, the patients injuries were in agreement with previous knee dislocation studies. Of the bony fragments that were seen on MDCT images in patellar dislocation patients 59% were not seen on AP and lateral views of the conventional radiographs. The location, size and donor site of the bony fragments was similar between first-time and recurrent patellar dislocators. Patients with a Segond fracture associated with a tibial plateau fracture had significantly fewer ACL ruptures and more avulsion fractures of the ACL than patients with isolated Segond fractures. In approximately one of every 32 tibial plateau fractures, a Segond fracture also coexists. In 0.64 % of the emergency room acute knee trauma MDCT examinations a reverse Segond fracture were found. Of the operated reverse Segond fracture patients 43% had an avulsion fracture of the ACL, and 14% had a PCL rupture. DECT s sensitivity and specificity to detect ACL rupture were 79 % and 100 %, respectively, and the intra- and interobserver proportions of agreement for ACL rupture were excellent and good. The radiologist should be aware that even after a simple fall, overweight patients may have a knee dislocation. Patients with a Segond fracture combined with a tibial plateau fracture have a high risk of avulsion fracture of the ACL. In previous reports, reverse Segond fracture have been associated with PCL injury, but our results do not support this association. DECT is a usable method to evaluate ACL in acute knee trauma patients with rather good sensitivity and high specificity.
  • Wennman, Heini (Helsingin yliopisto, 2016)
    Physical activity (PA) is a well established behavioral risk factor for cardiovascular diseases (CVD), a leading cause of death globally. Also poor sleep and sedentary behaviors associate with higher CVD risk. Despite decreased CVD mortality in Finland, many people do not get enough PA, sleep-related problems are common in the working aged population and sedentary behaviors take up large parts of the time spent awake. Health behaviors tend to cluster and epidemiological literature suggest interrelationships also between PA and sleep. Associations between PA and sleep can be modified by qualitative factors, such as domain of PA, sleep quality and timing of sleep, as well as sociodemographic characteristics. The existing literature is sparse on interactions between PA and sleep with CVD and actual clustering of the behaviors has seldom been modeled in large-scale population data. The aim of this thesis was to study the interrelationship between PA and sleep and their joint association with CVD risk and mortality. The focus was on modelling inter-individual variation in the behaviors and on studying cardiometabolic risk factors and total CVD risk based on the clustering of the behaviors. Furthermore, the interrelationships between a history of sports, PA, sleep and all-cause and CVD mortality was studied in a population of former elite athletes. This study comprises data from the National FINRISK 2012 Study (n=6424, men=3041; women=3383) and the Finnish former elite athlete cohort (n=2141, all men). In the FINRISK 2012 Study, a sample of the Finnish general population aged 25 to 74-years underwent a health examination and filled in health questionnaires. The former athletes (n=1364) and non-athletic referents (n=777) of the Finnish former elite athlete cohort provided information about health behaviors on a questionnaire in 1985 and were then followed-up for mortality until 31 December 2011 from national registers. This study showed that differences in clustering of PA and sleep behaviors characterized underlying groups of men and women among the initially CVD-free, Finnish general population. Low PA, high screen time sitting, short and insufficient self-reported sleep made up a Profile, in which membership among women associated with unfavorable levels in several cardiometabolic risk factors and a higher total CVD risk. In men, membership in the Physically inactive, poor sleepers Profile showed only one statistically significant association (out of 10) with unfavorable levels in cardiometabolic risk factors, but was associated with a high estimated 10-year CVD risk. Different chronotypes in the population were strongly characterized by evening preference, but also by morning tiredness. Both evening types and tired, more evening types had low leisure time PA (LTPA) compared to morning types and evening type also had high sitting. There was a significant joint association of insufficient LTPA level and short sleep with a higher mortality, especially CVD mortality, in a cohort of former elite athletes and non-athletic referents. This study supports the importance of PA and sleep as health behaviors related to CVD risk, and provide evidence particularly for a joint association with CVD risk. Not only the duration of sleep, but also the quality and self-estimated sufficiency of sleep, as well as a person s chronotype contribute to the clustering of PA and sleep and consequent CVD risk. The results of this study are generalizable to the general adult population in Finland, apart from the mortality results that apply to a more selected male population.
  • Frilander, Heikki (Helsingin yliopisto, 2016)
    Low back and knee pain are common and often cause discomfort and disability as well as burdening the health care services. Chronic musculoskeletal disorders (MSDs) tend to develop over long time periods, suggesting an importance of early-life exposures in disease onset. There is insufficient understanding of early indicators of knee and low back problems as well as of those predicting disability retirement (DR). The main aim of this thesis was to increase the knowledge on the role of early health-related and lifestyle factors in musculoskeletal health and permanent work disability by applying a life course approach and examining the impact of obesity and other lifestyle factors on back and knee problems over time. The study base comprised a nationally representative random sample of 2843 men aged 18-50 years. The military records of these men were searched from the register of the Finnish Defence Forces. The first study assessed temporal trends in seeking healthcare during military service over a 40 year period. In studies II and III the military records were linked with data from the Health 2000 Study: weight-related measures at follow up and during life course, information on low back and knee symptoms and disorders, as well as information on other lifestyle and health-related factors. In the fourth study data on care seeking during military service was linked with information on all DR events and their diagnoses from the national registers of the Social Insurance Institution and the Finnish Centre for Pensions. During 1967-2006, there has been a marked increase in healthcare seeking due to any reason as well as due to musculoskeletal problems among Finnish conscripts. Most conscripts visited healthcare at least once due to MSDs, most frequently due to problems in the lower extremities and the lower back. Both baseline and life course BMI predicted one-month radiating low back pain (LBP), knee pain as well as functional limitations due to a knee problem at follow-up. Men who were borderline obese at baseline and became severely obese during the follow-up had an increased risk of radiating LBP and functional knee limitations, while the risk of knee pain was increased already for those who had normal BMI at baseline and became overweight during follow-up. Baseline borderline obesity doubled the risk of both traumatic and non-traumatic knee injuries during military service. Cross-sectionally both general and abdominal obesity were associated in a similar manner with radiating LBP and unilateral knee pain. Functional limitations of the knee were associated only with general obesity. Men who did not complete military service had a clearly higher cumulative incidence of DR, particularly due to mental disorders, in comparison with their counterparts who completed military service. Visiting military health care due to both musculoskeletal and mental problems clearly increased the overall risk of DR, in particular DR due to mental disorders. In men, health behaviours in early adulthood as well as during life course, seem to increase the likelihood of low back and knee problems, functional knee limitations and work disability later in life. Health-related problems, particularly mental ones and comorbidity of musculoskeletal and mental problems, in early adulthood are important predictors of DR. Encouraging young people from becoming overweight and avoiding further weight gain during the life course may prevent radiating LBP as well as knee pain and associated disability. Risk indicators for work disability could be identified and preventive measures initiated in call-up examinations and military service as well as in school healthcare and in occupational health services for those young adults entering working life.
  • Suvanto, Maija (Helsingin yliopisto, 2016)
    The nephrotic syndrome (NS) is characterized by massive proteinuria, edema and hypertriglyceridemia. It can appear as a primary or a secondary disease, idiopathic or familial, monogenic or complex, responsive to medication or progressing inevitably towards end-stage renal disease. As the manifestations of the disease are varied so is the etiologies behind it and still much remains to be discovered. However, structural compromise can be observed in the glomeruli of the NS patients, especially in podocytes, specialized epithelial cells of the glomerular filtration barrier. When causative genetic variants are found they are predominantly in the genes coding proteins involved in the structure and function of the podocytes. To date, over thirty podocyte protein-coding genes have been implicated. In this study we looked into genetic and cellular mechanisms in the podocyte underlying different forms of NS: congenital nephrotic syndrome of the Finnish type (CNF), steroid sensitive nephrotic syndrome (SSNS) and steroid resistant nephrotic syndrome (SRNS). Specifically, we used CNF kidney samples to study how the different compartments of the podocyte are affected by the lack of nephrin, characteristic structural component of the unique cellular junction of the podocytes (slit diaphragm (SDs)). We also looked into genetic variation in the podocyte protein coding genes in the Finnish SRNS patients to map out the variant spectrum and to see if this population shows difference to other populations. In addition, we aimed to find genetic and clinical markers predicting the course and severity of SSNS, which would have significant clinical value. The analyses were carried out using an array of molecular biological methods. Protein expression was studied using immunohistochemistry and light microscopy, genetic variants with PCR and sequence analysis. In addition, immunoprecipitation and western blot analyses were carried out to study the functionality of a particular variant. Genome wide sequencing analysis was carried out to gain wider perspective on the variant spectrum in NS patients. Our results showed that the lack of nephrin leads to widespread effects in the podocyte on protein level, especially on the expression of other proteins of the SD. In other compartments of the cell (basal membrane, actin cytoskeleton, apical membrane) the effect was clear but considering the profound structural damage seen in CNF the orders of magnitude of the observed changes were modest. We also showed that the analyzed clinical features or variants in these key genes coding podocyte proteins cannot reliably predict severity of SSNS. Children with difficult disease (multiple relapses, dependence on steroids) are more likely to suffer from NS in adulthood but other correlations between early patient features and prognosis could not be made. Single nucleotide polymorphisms (SNP) analysis of children with idiopathic NS revealed that variants in some genes (e.g. MDR1) may be useful in predicting responsiveness to steroids but the correlation is not sufficiently strong to warrant routine clinical testing. We found few causative variants in patients with idiopathic SRNS but did uncover a de novo NPHS2 variant co-segregating with familial dominant SRNS and unusual course of the disease. Healthy function of the podocyte relies on interaction and communication between multitudes of protein components in the different compartments of the cell. If any of these components are faulty it may cascade into widespread podocyte damage and proteinuria. The precise nature of the defect may play a significant role in the disease phenotype and not only the function of the damaged gene but also the nature of the variant ought to be considered when carrying out genetic analysis. Not in all cases causative variants or precise faulty structures can be identified. The genetic factors behind complex traits remain elusive, and even though some pieces of the puzzle have been found, in small part by this study, much is still to be discovered.
  • Li, Zhilin (Helsingin yliopisto, 2016)
    Neurological disorders and related illnesses are leading causes of disability and suffering, and are major health problems and economic burdens to modern society. There are currently no cures or satisfactory disease-modifying treatments for the majority of neurological diseases and associated comorbid neuropsychiatric symptoms. This is partly due to still limited knowledge of the cellular and molecular mechanisms underlying the etiology and progression of neurological and neuropsychiatric disorders. A substantial body of evidence indicates the involvement of innate or adaptive immune cells and the inflammatory mediators they secrete in various neurological or neuropsychiatric disorders. However, the precise roles that immune cells play and the underlying molecular mechanisms that regulate immune cell functions in these disorders remain largely unknown. The purpose of this thesis work is to explore the role of immune cell inflammatory polarization and their molecular regulatory mechanisms in neurological and comorbid anxiety disorders using several rodent experimental models. First, we discovered that microglia/macrophages in the brain and spinal cord of naïve rats are different from each other, in terms of their abundancy, inflammatory polarization states, and expression of multiple microglia/macrophage-related immune molecules. Such region-specificity under the steady-state condition may underlie their subsequent opposite inflammatory responses to peripheral nerve injury and the analgesic effect of the microglial/macrophage inhibitor minocycline in chronic neuropathic pain. Since anxiety disorders are frequently observed in patients with neurological disorders, we further explored the association of brain microglial inflammatory polarization with anxiety traits in mice. We characterized microglia in the brains of four inbred mouse strains (C57BL/6J, FVB/N, DBA/2J, and 129S2/Sv) and discovered a strong positive correlation between brain microglial pro- versus anti-inflammatory (M1/M2) ratio and anxiety-like behaviors in mice. Hence, microglial M1/M2 ratio in the brain may be utilized as an index of anxiety or its regulatory genes as potential drug candidates for treating anxiety disorders. Finally, we discovered that a cell adhesion molecule AMIGO2 is critically involved in the modulation of T cell and microglial/macrophage functions, particularly T-cell homing and T-helper cell polarization. We also observed that Amigo2 knockout (AMG2KO) mice exhibited ameliorated EAE. We further demonstrated that Amigo2-deficiency in T-helper cells promoted Akt activation and NF-kB and NFAT1 transcriptional activities, thereby leading to elevated T-bet and GATA-3, resulted in increased IFN-γ and IL-10 but decreased IL-17A productions. Therefore, AMIGO2 may be harnessed as a potential diagnostic and therapeutic target for multiple sclerosis. Taken together, utilizing several naturally existing, surgically, or immunologically induced rodent experimental models for neurological and neuropsychiatric disorders, we discovered that inflammatory polarizations of innate and adaptive immune cells are critically involved in these modeled disorders. Our data suggest that disease-modifying approaches targeting inflammatory polarization of microglia/macrophages or molecules that regulate T-cell polarization (e.g. AMIGO2), may be beneficial for tackling these neurological or neuropsychiatric disorders in the future.
  • Kämpjärvi, Kati (Helsingin yliopisto, 2016)
    Mediator complex subunit 12 (MED12) is a component of the conserved Mediator complex and an important player in the regulation of general and gene specific transcription. Somatic MED12 mutations were associated with human tumorigenesis for the first time when exome sequencing of uterine leiomyomas identified highly specific mutations affecting exon 2 in as many as 70% of the tumors. Uterine leiomyomas are benign smooth muscle tumors estimated to affect up to 77% of reproductive-age women. Most of the tumors are sporadic, but uterine leiomyomas are also a feature of hereditary leiomyomatosis and renal cell cancer syndrome (HLRCC), where biallelic inactivation of fumarate hydratase (FH) is driving the tumorigenesis. The overall aim of this thesis project was to take forward the finding of MED12 as a novel driver gene in myomagenesis and to analyze its role in other tumor types. Comprehensive MED12 exon 2 mutation screening in various tumor types identified mutations recurrently in uterine leiomyosarcoma and rarely in colorectal cancer. Findings demonstrate that these specific mutations are not restricted to benign tumors and suggest a possibility of some leiomyosarcomas to develop via benign leiomyoma precursor. Mutation analysis of MED12 exon 1 from tumor types where mutations in exon 2 have previously been reported revealed small in-frame deletions only in conventional uterine leiomyomas. Mutations in exon 1 led to similar global expression profile and mechanistic effects as previously observed with exon 2 mutations further emphasizing the role of MED12 in leiomyomagenesis. Assessment of the FH status and MED12 exon 1/2 mutation screening confirmed that biallelic FH inactivation and MED12 mutations are mutually exclusive both within HLRCC syndrome-associated and sporadic uterine leiomyomas. These results and the gene expression profiling of the tumors show that there are at least two distinct molecular mechanisms behind the development of uterine leiomyomas in HLRCC patients: biallelic FH inactivation and somatic MED12 mutations. A systematic database search identified few MED12 mutations affecting the leiomyoma-linked mutation hotspots in chronic lymphocytic leukemia (CLL), the most common form of leukemia in adults. Mutation screening of more than 700 samples revealed CLL as the first extrauterine cancer where specific MED12 exon 1 and 2 mutations have been observed at significant frequency. Furthermore, MED12 mutations associated with unmutated status of immunoglobulin heavy chain variable genes and elevated expression of 70 kD zeta-associated protein; well-characterized markers of poor prognosis in CLL. Functional analysis of the unusual MED12 exon 1 nonsense mutation identified in a patient with T cell acute lymphoblastic leukemia showed that mutant messenger ribonucleic acid escapes nonsense mediated decay and produces an N-terminally truncated protein. Mutation prevented protein s nuclear localization and prohibited its interactions with other Mediator complex components, which led to an identification of a nuclear localization signal occurring at the highly conserved N-terminal region of MED12. The results of this study further strengthen the role of MED12 in the pathogenesis of uterine leiomyomas. These findings demonstrate that MED12 mutations are not restricted to benign hormone-dependent solid tumors, but can be found also in malignant tumors and in hematological diseases. Our results also provide new knowledge about the structure and normal functions of the MED12 protein.
  • Heinonen, Sini (Helsingin yliopisto, 2016)
    ABSTRACT Obesity is a major health problem and is increasing rapidly both in developed and developing countries worldwide. Treatment of obesity is difficult, expensive and often fails. Obesity increases the likelihood for many diseases, such as type 2 diabetes, coronary heart disease, metabolic syndrome, hyperlipidemia and some types of cancer. We still lack a meaningful understanding of the factors behind this complex disease and therefore any proper means to battle it. Only lately, adipose tissue and especially its mitochondria have been recognized as important contributors to whole-body energy balance and the development of obesity. This thesis investigates the biological pathways in adipose tissue that lead to the development of metabolic complications in early-onset obesity in young healthy twins. The aim was to study how acquired obesity affects adipose tissue and adipocyte function and how these link to whole body metabolism. The rare weight-discordant monozygotic (MZ) co-twin setting used in this study, is uniquely positioned to disentangle acquired and inherited metabolic pathways to disease in obesity. MZ twin pairs discordant for obesity enable controlling for genetic background, age, sex and early environmental influences. As MZ twins are fully identical at the level of genome sequence, the observed differences between the co-twins can be assumed to be acquired. This is a major strength of our study regarding a polygenic and multifactorial trait as obesity. Adipocyte hypertrophy in adipose tissue is one of the main features of obesity. The first study of the thesis investigated adipose tissue hypertrophy and hyperplasia in acquired obesity and its associations to whole body metabolism and gene expression pathways of the adipose tissue. We showed a high within-pair resemblance in adipocyte size and number suggesting that the adipocyte phenotype is genetic or due to shared environmental factors. Hypertrophy (large size) and low number of adipocytes in acquired obesity was related to metabolic dysfunction in obesity and associated with the disturbances in mitochondrial function and with increased cell death within the adipose tissue. In the second study we investigated how transcriptional pathways of subcutaneous adipose tissue and the liver fat associate with metabolically healthy obesity a phenomenon where some of the obese individuals stay free from metabolic complications usually associated with weight gain. We showed for the first time in twins that the amount of liver fat is a key clinical determinant of metabolic health and that low liver fat associates with maintenance of high mitochondrial transcription and lack of inflammation in subcutaneous adipose tissue. In further investigations we addressed mitochondrial biogenesis and oxidative metabolism in detail. The third and fourth studies concentrated on mitochondrial biogenesis in adipose tissue and in adipocytes, respectively. The novel findings in the third study were that obesity is related to reduced mitochondrial mass and oxidative metabolic activity in subcutaneous adipose tissue, both in the nuclear and in the mitochondrial transcription level, as well as decreased protein levels in the OXPHOS system, especially OXPHOS complex subunits I and IV. The mitochondrial dysfunction paralleled whole body insulin resistance and low-grade systemic inflammation. Remarkably, these changes were seen already at the early stages of acquired obesity. In the fourth study, we showed that the global downregulation of mitochondrial transcriptional signature in acquired obesity originates at least partly from the adipocyte cells of adipose tissue. This research resulted in better understanding of the factors behind metabolic complications in acquired obesity. Development of obesity seems to associate with mitochondrial dysfunction in adipose tissue. The decreased function of mitochondria was evident at the level of both nuclear gene expression level and mitochondrial gene expression, as well as mitochondrial protein levels. These changes associated with metabolic disturbances of obesity. With rare obesity-discordant MZ twins we have been able to show that the changes are not genetic but result from acquired factors. However, as there was a remarkable similarity of adipocyte size and especially number between the co-twins, responses to obesity may have a partial genetic basis. With low capacity to adipocyte hypertrophy, excess fat may accumulate to liver and other tissues. Liver fat content is a clear determinant of metabolic health in acquired obesity. The results of my thesis as a whole suggest that obesity-associated metabolic disturbances might be halted by improving mitochondrial number and/or activity in adipose tissue.
  • Salminen, Aino (Helsingin yliopisto, 2016)
    Matrix metalloproteinases (MMPs) are enzymes that are responsible for the degradation of the extracellular matrix (ECM) during development, repair, and remodeling of tissues. MMP-8, also known as neutrophil collagenase, is released from neutrophils when they enter the tissues at the site of inflammation. An imbalance in MMP-8 activity leads to excess degradation of tissues and destructive inflammation, such as periodontitis. Elevated concentrations of MMP-8 in serum and plasma are also associated with cardiovascular diseases (CVDs). Doxycycline has inhibitory effects against MMPs in addition to its well-known property of being antimicrobial. This thesis investigated the genetics of MMP-8, the effect of MMP-8 and its inhibitors on lipid metabolism, and the potential of salivary MMP-8 in diagnostics of periodontitis. We performed a genome-wide association study (GWAS) in two independent populations with a total of 6049 individuals to identify genetic variants and molecular mechanisms that affect serum MMP-8 concentrations. In addition, we studied whether MMP-8-associated genetic variants are related to increased risk of CVDs in over 20 000 individuals. We discovered that genetic polymorphism in the gene of complement factor H (CFH) is strongly associated with the concentrations of MMP-8 in serum. By conducting functional experiments with isolated neutrophils, we found that genetic variation of CFH affected the release of MMP-8 from neutrophils in response to complement activation. In addition, genetic polymorphism in the locus containing the genes of S100 calcium binding proteins A8, A9, and A12 was associated with serum and plasma MMP-8 levels and also with the prevalence and incidence of CVDs. We studied the effect of MMP-8 and its inhibitors on lipid metabolism by conducting cell experiments, in an MMP-8-knockout mouse model, and in a placebo-controlled clinical trial of two years. We discovered that MMP-8 cleaved apolipoprotein A-I (apoA-I), the main protein component of HDL. MMP-8 significantly reduced the ability of HDL to promote cholesterol efflux from cholesterol-loaded macrophages. The cleavage of apoA-I by MMP-8 and the reduction in its cholesterol efflux capacity was inhibited by doxycycline at clinically attainable doses. MMP-8 deficient mice had significantly lower serum triglyceride levels and larger HDL particle size compared to wild type mice. In the clinical trial, the subjects treated with subantimicrobial-dose doxycycline (SDD) displayed a significant increase in cholesterol efflux from macrophages to the serum compared to the baseline, whereas the efflux levels did not change in the placebo group over the study period. We studied the association of three salivary biomarkers, MMP-8, interleukin-1β, and Porphyromonas gingivalis, with periodontal status in 463 subjects. The salivary concentrations of MMP-8, interleukin-1β, and P. gingivalis were associated with the number of deepened periodontal pockets and the extent of alveolar bone loss. The combination of the biomarkers was more strongly associated with moderate to severe periodontitis than any of the biomarkers alone. Our results indicate that activation of the complement system, especially the alternative pathway, contributes significantly to the concentrations of MMP-8 in serum. Genetic polymorphism in S100A8/A9/A12 locus affects circulating MMP-8 levels, and is associated with CVDs. These results emphasize the role of inflammation and the immune system in CVDs. Proteolysis of apoA-I by MMP-8 may disturb HDL metabolism and reverse cholesterol transport, which leads to accumulation of cholesterol in the vessel walls and accelerated atherosclerosis. Inhibition of MMP-8 by doxycycline may reduce the risk of CVDs, especially in vulnerable individuals such as periodontitis patients. Saliva MMP-8, particularly when combined with other biomarkers, has great potential in the diagnostics of periodontitis. MMP-8 in saliva reflects the health of the oral cavity, whereas circulating MMP-8 is associated with systemic diseases such as CVDs. Our results suggest that MMP-8 functions as a link between inflammatory disorders, such as periodontitis, and cardiovascular disorders.