1.
Mottahedin, Amin
(författare)
Developing brain and systemic inflammation: a "Toll-like" link with consequences
2017
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
The developing brain is vulnerable to external insults, and perinatal brain injury (PBI) is a major cause of life-long neurological syndromes such as cerebral palsy. Currently, no pharmaceutical intervention is available. Hypoxia/ischemia (HI), infections and inflammation are implicated in the pathogenesis of PBI. However, the crosstalk between these etiologies is not fully understood. Toll-like receptors (TLR) 3 and TLR2 are responsible for sensing viral and bacterial infections and initiating the inflammatory response. The aim of this thesis was to investigate the effect of systemic inflammation induced by activation of these TLRs on neonatal HI brain injury. We demonstrate that intraperitoneal administration of TLR3 and TLR2 ligands (PolyI:C and P3C, respectively) prior to HI increases the brain injury in neonatal mice. PolyI:C and P3C induced neuroinflammation and altered microglial phenotype as assessed by RT-qPCR, multiplex cytokine assay or flow cytometry. PolyI:C also upregulated the pro-apoptotic gene, Fasl, expression and reduced activation of pro-survival signaling molecule Akt. On the other hand, P3C suppressed mitochondrial respiration, a major mechanism of cellular energy production. P3C, unlike other TLR agonists, induced marked infiltration of leukocytes to the cerebral spinal fluid and brain of neonatal mice and rats. Confocal microscopy, Cre recombinase-mediated gene targeting and in vitro cell transmigra-tion assay revealed the choroid plexus as a site of leukocyte entry. RNA sequencing of the choroid plexus followed by transcriptome cluster analysis and Ingenuity Pathway Analysis revealed potential mechanisms of leukocyte infiltration, including a specific chemotaxis signature and cytoskeleton-related pathways. Finally, we show that N-acetylcysteine treatment inhibits TLR2-mediated leukocyte trafficking in vivo and in vitro. To conclude, this thesis describe a TLR-mediated link between systemic inflammation and developing brain with detrimental consequences on HI brain injury, suggesting potential novel therapeutic strategies.
2.
Bhandage, Amol K., 1988-
(författare)
Glutamate and GABA signalling components in the human brain and in immune cells
2016
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Glutamate and γ-aminobutyric acid (GABA) are the principal excitatory and inhibitory neurotransmitters in the central nervous system (CNS). They both can activate their ionotropic and metabotropic receptors. Glutamate activates ionotropic glutamate receptors (iGlu - AMPA, kainate and NMDA receptors) and GABA activates GABA-A receptors which are modulated by many types of drugs and substances including alcohol. Using real time quantitative polymerase chain reaction, I have shown that iGlu and/or GABA-A receptor subunits were expressed in the hippocampus dentate gyrus (HDG), orbitofrontal cortex (OFC), dorsolateral prefrontal cortex (DL-PFC), central amygdala (CeA), caudate and putamen of the human brain and their expression was altered by chronic excessive alcohol consumption. It indicates that excitatory and inhibitory neurotransmission may have been altered in the brain of human alcoholics. It is possible that changes in one type of neurotransmitter system may drive changes in another. These brain regions also play a role in brain reward system. Any changes in them may lead to changes in the normal brain functions.Apart from the CNS, glutamate and GABA are also present in the blood and can be synthesised by pancreatic islet cells and immune cells. They may act as immunomodulators of circulating immune cells and can affect immune function through glutamate and GABA receptors. I found that T cells from human, rat and mouse lymph nodes expressed the mRNAs and proteins for specific GABA-A receptor subunits. GABA-evoked transient and tonic currents recorded using the patch clamp technique demonstrate the functional GABA-A channel in T cells. Furthermore, the mRNAs for specific iGlu, GABA-A and GABA-B receptor subunits and chloride cotransporters were detected in peripheral blood mononuclear cells (PBMCs) from men, non-pregnant women, healthy and depressed pregnant women. The results indicate that the expression of iGlu, GABA-A and GABA-B receptors is related to gender, pregnancy and mental health and support the notion that glutamate and GABA receptors may modulate immune function. Intra- and interspecies variability exists in the expression and it is further influenced by physiological conditions.
3.
4.
Klawonn, Anna, 1985-
(författare)
Molecular Mechanisms of Reward and Aversion
2017
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Various molecular pathways in the brain shape our understanding of good and bad, as well as our motivation to seek and avoid such stimuli. This work evolves around how systemic inflammation causes aversion; and why general unpleasant states such as sickness, stress, pain and nausea are encoded by our brain as undesirable; and contrary to these questions, how drugs of abuse can subjugate the motivational neurocircuitry of the brain. A common feature of these various disease states is involvement of the motivational neurocircuitry - from mesolimbic to striatonigral pathways. Having an intact motivational system is what helps us evade negative outcomes and approach natural positive reinforcers, which is essential for our survival. During disease-states the motivational neurocircuitry may be overthrown by the molecular mechanisms that originally were meant to aid us.In study I, to investigate how inflammation is perceived as aversive, we used a behavioral test based on Pavlovian place conditioning with the aversive inflammatory stimulus E. coli lipopolysaccharide (LPS). Using a combination of cell-type specific gene deletions, pharmacology, and chemogenetics, we uncovered that systemic inflammation triggered aversion by MyD88-dependent activation of the brain endothelium followed by COX1-mediated cerebral prostaglandin E2 (PGE2) synthesis. Moreover, we showed that inflammation-induced PGE2 targeted EP1 receptors on striatal dopamine D1 receptor–expressing neurons and that this signaling sequence induced aversion through GABA-mediated inhibition of dopaminergic cells. Finally, inflammation-induced aversion was not an indirect consequence of fever or anorexia but constituted an independent inflammatory symptom triggered by a unique molecular mechanism. Collectively, these findings demonstrate that PGE2-mediated modulation of the dopaminergic circuitry is a key mechanism underlying inflammation-induced aversion.In study II, we investigate the role of peripheral IFN-γ in LPS induced conditioned place aversion by employing a strategy based on global and cell-type specific gene deletions, combined with measures of gene-expression. LPS induced IFN-ɣ expression in the blood, and deletion of IFN-ɣ or its receptor prevented conditioned place aversion (CPA) to LPS. LPS increased the expression of chemokine Cxcl10 in the striatum of normal mice. This induction was absent in mice lacking IFN-ɣ receptors or Myd88 in blood brain barrier endothelial cells. Furthermore, inflammation-induced aversion was blocked in mice lacking Cxcl10 or its receptor Cxcr3. Finally, mice with a selective deletion of the IFN-ɣ receptor in brain endothelial cells did not develop inflammation-induced aversion. Collectively, these findings demonstrate that circulating IFN-ɣ binding to receptors on brain endothelial cells which induces Cxcl10, is a central link in the signaling chain eliciting inflammation-induced aversion.In study III, we explored the role of melanocortin 4 receptors (MC4Rs) in aversive processing using genetically modified mice in CPA to various stimuli. In normal mice, robust aversions were induced by systemic inflammation, nausea, pain and kappa opioid receptor-induced dysphoria. In sharp contrast, mice lacking MC4Rs displayed preference towards most of the aversive stimuli, but were indifferent to pain. The unusual flip from aversion to reward in mice lacking MC4Rs was dopamine-dependent and associated with a change from decreased to increased activity of the dopamine system. The responses to aversive stimuli were normalized when MC4Rs were re-expressed on dopamine D1 receptor-expressing cells or in the striatum of mice otherwise lacking MC4Rs. Furthermore, activation of arcuate nucleus proopiomelanocortin neurons projecting to the ventral striatum increased the activity of striatal neurons in a MC4R-dependent manner and elicited aversion. Our findings demonstrate that melanocortin signaling through striatal MC4Rs is critical for assigning negative motivational valence to harmful stimuli.The neurotransmitter acetylcholine has been implied in reward learning and drug addiction. However, the role of cholinergic receptor subtypes in such processes remains elusive. In study IV we investigated the function of muscarinic M4Rs on dopamine D1R expressing neurons and acetylcholinergic neurons, using transgenic mice in various reward-enforced behaviors and in a “waiting”-impulsivity test. Mice lacking M4-receptors from D1-receptor expressing neurons exhibited an escalated reward seeking phenotype towards cocaine and natural reward, in Pavlovian conditioning and an operant self-administration task, respectively. In addition, the M4-D1RCre mice showed impaired waiting impulsivity in the 5-choice-serial-reaction-time-task. On the contrary, mice without M4Rs in acetylcholinergic neurons were unable to learn positive reinforcement to natural reward and cocaine, in an operant runway paradigm and in Pavlovian conditioning. Immediate early gene expression mirrored the behavioral findings arising from M4R-D1R knockout, as cocaine induced cFos and FosB was significantly increased in the forebrain of M4-D1RCre mice, whereas it remained normal in the M4R-ChatCre mice. Our study illustrates that muscarinic M4Rs on specific neural populations, either cholinergic or D1R-expressing, are pivotal for learning processes related to both natural reward and drugs of abuse, with opposing functionality.
5.
Bratanis, Eleni
(författare)
Bacterial antibody hydrolyzing enzymes – as bacterial virulence factors and biotechnological tools
2019
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Antibodies are an essential part of the human immune system, and antibody mediated immunity has been an area of interest for many researchers for almost a century. An accumulation of knowledge regarding antibody structure, glycosylation and receptor interactions has contributed to the current understanding of antibody mediated immunity. It has more recently become evident how bacteria and other microorganisms evade host recognition and eradication through specific antibody degradation or modification. The importance of antibody glycosylation and how glycan modification can fine-tune the elicited immune response has also contributed to the development of antibody-based drugs with improved clinical efficacy. In turn these insights have paved the way and created a need for the development of biotechnological methods and tools to specifically engineer antibodies with defined properties, for analysis to ensure quality and safety, and for improved antibody purification.This thesis highlights the importance of glycosylation for antibody function and presents different aspects and applications of antibody modifications by bacteria. We show, for the first time, activity of the IgG-specific Streptococcal endoglycosidase EndoS during Streptococcus pyogenes infection, clearly demonstrating that EndoS contributes to S. pyogenes pathogenesis and bacterial survival in the context of adaptive immunity. Further this thesis presents the use of bacterial enzymes as antibody modifying tools and their potential as binding reagents for selective antibody purification. The identification and characterization of two novel proteases, BspK and BspE exhibiting unique IgG and IgA cleavage profiles respectively, from Bdellovibrio bacteriovorus highlights the potential of using Bdellovibrio as a source for the identification of novel enzymes with biotechnological applications. Finally, I present the development of a novel method for selective antibody purification, using the inactive variants of the bacterial enzymes EndoS and EndoS2, ensuring the purification of native, correctly folded and modified antibodies.
6.
Boij, Roland, 1952-
(författare)
Aspects of inflammation, angiogenesis and coagulation in preeclampsia
2016
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Preeclampsia is a major challenge to obstetricians, due to its impact on maternal and fetal morbidity and mortality and the lack of preventive and treatment strategies. The overall aim of this thesis is to increase the knowledge of the pathogenesis of preeclampsia including the role of inflammation, angiogenesis and coagulation, both locally at the fetomaternal interface and in the maternal circulation. Uncompensated maternal endothelial inflammatory responses to factors from stressed trophoblasts seem to be a major contributor to the syndrome, together with an imbalance in angiogenesis and an activated coagulation system. An increasing amount of data indicates an involvement of the immune system with defect tolerance to the conceptus as an integral part of the pathogenesis, at least in early-onset preeclampsia (EOP).We showed that a single administration of human preeclampsia serum in pregnant IL-10−/− mice induced the full spectrum of preeclampsia-like symptoms including hypoxic injury in uteroplacental tissues and endotheliosis in maternal kidneys. Importantly, preeclampsia serum, as early as 12 to 14 weeks of gestation, disrupted cross talk between trophoblasts and endothelial cells in an in vitro model of endovascular activity (Tube formation test). These results indicate that preeclamptic sera can be used to better understand the pathophysiology and to predict the disorder. Preeclampsia has been associated with increased inflammation, aberrant angiogenesis and activated coagulation, but their correlation and relative contribution are unknown. We found that markers for all these mechanisms were independently associated with preeclampsia. Cytokines, chemokines, and complement factors seem all to be part of a Th1-associated inflammatory reaction in preeclampsia, more pronounced in EOP than in late-onset preeclampsia (LOP), in line with a more homogeneous pathogenesis in EOP as based on placental pathology. In women with intrauterine growth restriction (IUGR), with an anticipated pathologic placentation, only differences in levels for sFlt-1 and PlGF were found in comparison with mothers without IUGR. Thus, sFlt-1 and PlGF seem to be indicators of placental pathology, while other biomarkers might also reflect maternal endothelial pathology. Chemokines, in contrast to cytokines, may prove to be useful markers in preeclampsia.A deficiency in regulatory T (Treg) cells causing reduced immune regulatory capacity has been proposed in preeclampsia. Utilizing recent advances in flow cytometry phenotyping, we found no major alterations in circulating Treg numbers in preeclamptic women compared with normal pregnant and non-pregnant women. However, preeclampsia was associated with increased fractions of CTLA-4+ and CCR4+ cells within Treg subpopulations, which is in line with a migratory defect of Treg cells, and potentially associated with a reduced number of suppressive Treg cells at the fetomaternal interface. As we found that corticosteroid treatment affected the results, it should be accounted for in studies of EOP. Chemokines are supposed to be part of the immune adaptation in pregnancy. We found a decreased expression of CCL18 (Th2/Tregassociated), in trophoblasts from preeclamptic compared to normal pregnant women, indicating a local regulatory defect in preeclampsia, in line with our finding of a possible migratory defect of circulating Treg cells. Due to increased expression of CCL20 (Th17) and CCL22 (Th2) in first trimester placenta and increased circulating levels of CXCL10 (Th1) and CCL20 (Th17) in third trimester preeclamptic women, we suggest that CCL20 and CCL22 may be important for implantation and early placentation while in third trimester of a preeclamptic pregnancy CXCL10 and CCL20 mainly mirror maternal increased endothelial inflammation and aberrant angiogenesis. In summary, we found that preeclampsia is associated with increased inflammation, aberrant angiogenesis and activated coagulation, caused by placental factors in maternal peripheral circulation, more pronounced in the early-onset form of preeclampsia. It also appears that there is a defective modulation of the immune system in preeclamptic pregnancies. The results provide a better understanding of the pathogenesis of preeclampsia and have given suggestions to predictive markers for preeclampsia in the future.
7.
Garcia, Megg Gonzales
(författare)
Neuroinflammation and amyloid-β in early Alzheimer’s disease. Insight into the earliest events using mouse models
2023
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Alzheimer’s disease (AD) is the leading cause of dementia and most common neurodegenerative disease worldwide, but there currently exists no effective treatment that can stop nor slow the progression of the disease. The current dogma in the field postulates that the appearance of extracellular amyloid-beta (Aβ) plaques, a histopathological hallmark of the disease, is the trigger for downstream, detrimental events, including neuronal loss, extensive neuroinflammation and cognitive decline. However, increasing evidence suggests that neuroinflammatory alterations and synaptic and neuronal dysfunction occur already before plaque deposition, which we have also noted in previous work done by our groups. In addition, we have found that Aβ aggregates intracellularly, especially within neurons, before plaque appearance and that this has the ability to impair synaptic function. Therefore, we wonder whether there is an interplay between the neuroinflammatory system, neuronal and synaptic alterations, and intracellular Aβ in the earliest stages of the disease. To address this, we utilize mouse-based models in vivo, primarily the 5xFAD transgenic mouse model, and in vitro neuronal culture models. In the scientific papers included in this thesis work, we explore aspects related to mechanisms and modulations related to early AD. This includes looking at the prion-like spread and properties of intracellular Aβ, identifying sex-specific effects of early-life stress on inflammatory systems as well as neurons and Aβ, and investigating the interaction between neuroinflammatory cells and early aggregated Aβ. Taken together, we have worked to elucidate the earliest events in the disease, including factors that can modulate pathogenesis and the underlying mechanisms. By fostering a greater understanding of AD, we attempt to aid efforts towards the development of an effective disease-modifying treatment.
8.
Lundberg, Marcus
(författare)
Characterization of the Pancreas in Type 1 and Type 2 Diabetes
2018
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Diabetes is recognized by hyperglycaemia and polyuria. Complications, reduced quality of life and staggering health-care costs are all derived from the disease. Two subclasses of diabetes are Type 1 diabetes (T1D) and Type 2 diabetes (T2D). The beta cell mass is reduced in T1D, which is generally considered to be caused by an immune-mediated beta-cell destruction, but definitive evidence for this hypothesis remains absent. Development of insulin resistance and dysfunctional beta cells are commonly recognized as important factors that contribute to fulminant T2D. The literature that describes human T1D and T2D pancreata is sparse due to the limited number of specimens available for study. If more features of the respective pancreata are described, we might be able to elucidate the mechanisms involved in the pathoaetiology of the diseases.Accordingly, in this thesis pancreatic biopsies obtained from subjects with T1D or T2D have been examined with the aim to provide a more comprehensive picture of the respective pancreata. Paper I reports that aggregates of leucocytes substantiated mostly by macrophages are present in several T2D pancreata. Furthermore, as 28% of the T2D pancreata met the consensus definition of insulitis developed for T1D, a redefinition of insulitis is proposed. In Paper II, the density of parasympathetic axons was found to be reduced in the exocrine compartment in recent-onset T1D subjects compared to non-diabetic and long-standing T1D subjects. However, no alteration was discovered in islet-associated parasympathetic axons. In Paper III, interferon-stimulated genes were found to be over-expressed in recent-onset T1D islets, but no inducer explaining this expression has been discovered. Paper IV shows that T2D islets exhibit a stress response on a transcriptional level, and expression of these genes were investigated in islets from subjects with elevated HbA1c levels but without a clinical T2D diagnosis.In conclusion, this thesis explores several new areas of the pancreas in both T1D and T2D, and demonstrate several important findings that increase our knowledge on how diabetes develops.
9.
Svensson, Andreas
(författare)
Mesenchymal stromal cells in malignant glioma - Functions and therapeutic potential
2015
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
The most common malignant brain tumor in adults is a glioma called glioblastoma multiforme (GBM). About 300 persons are diagnosed with GBM every year in Sweden. Unfortunately, it is also the most aggressive brain tumor and as of today, it is not possible to cure it. Despite treating the patients with surgery, radiation and chemotherapy, the median survival is only 15 months. The main problem with GBM is its infiltrative growth. As the tumor cells leave the tumor bulk and migrate into the normal brain parenchyma, it is impossible to reach them with the current standard treatments. Hence, even after treatment, some tumor cells will remain in the brain and eventually give rise to a new tumor. To be able to reach the migrating cells, new treatment strategies need to be developed. One such strategy is to use stem cells as drug delivery vehicles. It has been shown that mesenchymal stromal cells (MSCs) derived from the bone marrow (BM) have the ability to specifically migrate throughout a glioma. Upon intratumoral transplantation, they spread within the tumor, along its extensions and toward migrating tumor cells that has left the main tumor bulk, making BM-MSCs ideal as transporters of anti-tumoral substances. However, several safety concerns have been raised as MSCs also have shown to mediate tumor growth by acting immunosuppressive and contribute to the tumor stroma and vascularization. This thesis will discuss 1) the role of endogenous MSCs in malignant glioma and 2) the use of transplanted BM-MSCs as glioma treatment. We have shown that human malignant gliomas harbor two distinct cell populations that resemble BM-MSCs. We have characterized the cells and conclude that they most likely play an important role in tumor angiogenesis and immunosuppression. Further on, we have seen that MSC-like pericytes within the normal mouse brain are activated by, and migrate into, an orthotopic glioma model. The cells align perivascularly and contribute the majority of all pericytes within the tumor. To evaluate their tumor-tropism, MSCs were derived from rat bone marrow and transplanted into, and adjacent to, orthotopic rat gliomas. We conclude that even though they show strong tumor-tropic migration capabilities upon intratumoral transplantation they do not migrate when transplanted into the normal brain of tumor bearing animals. We also report that intratumorally transplanted BM-MSCs potentiate the effect of peripheral immunotherapy against malignant gliomas, demonstrating their use in a therapeutic setting.
10.
