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| 3. |
- Philipson, Ola, 1979-, et al.
(författare)
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Biochemical and morphological analyses of Aβ deposits in postmortem brain of Arctic APP mutation carriers
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The clinical symptoms associated with the Arctic (E693G) mutation in the amyloid-β precursor protein (APP) are those of typical Alzheimer’s disease (AD), beginning with insidious loss of recent memories. However, an unusual neuropathology of ring-like amyloid-β (Aβ) plaques is identified in postmortem brain. Here, the neuropathology of subjects carrying the Arctic mutation was compared to that of sporadic AD. Different types of Aβ-deposits were examined with light, confocal and electron microscopy, and their composition was analyzed with biochemical techniques. Parenchymal deposits of the Arctic mutant brain were homogenous in structure, lacked an amyloid core and were immunostained differentially by antibodies recognizing C- or N-terminal epitopes of Aβ. Superficially, Arctic Aβ plaques bore considerable resemblance to cotton wool plaques (CWP), namely their large size, the presence of healthy neuronal nuclei and the absence of marked neuritic dystrophy within the plaques, and the sparsity of astro- or microgliosis in the surrounding tissue. Both parenchymal deposits and cerebral amyloid angiopathy of Arctic mutant brain contained a mixture of Arctic and wild-type Aβ. While Aβ peptides in parenchymal plaques were often N-terminally truncated, a substantial amount of full-length Aβ1-40 was deposited in the vessel walls as cerebral amyloid angiopathy (CAA). Thus, the absence of amyloid cores in parenchymal plaques of Arctic mutant brain was likely due to the scarcity of full-length Aβ species, although other mechanisms could also be involved. Our findings are discussed in relation to the clinical features of patients carrying the Arctic mutation and neuropathological observations made with other intra-Aβ mutations in human and transgenic mouse brain.
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| 4. |
- Philipson, Ola, et al.
(författare)
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The Arctic amyloid-β precursor protein (AβPP) mutation results in distinct plaques and accumulation of N- and C-truncated Aβ
- 2012
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Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580 .- 1558-1497. ; 33:5, s. 1010.e1-1010.e13
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Tidskriftsartikel (refereegranskat)abstract
- The Arctic (p. E693G) mutation in the amyloid-β precursor protein (AβPP) facilitates amyloid-β (Aβ) protofibril formation and generates clinical symptoms of Alzheimer's disease (AD). Here, molecular details of Aβ in post mortem brain were investigated with biochemical and morphological techniques. The basic structure of Arctic plaques resembled cotton wool plaques. However, they appeared ring-formed with Aβ42-specific antibodies, but were actually targetoid, since the periphery and center of many parenchymal Aβ deposits stained differently with mid-domain, N- and C-terminal Aβ antibodies. Aβ fibrils were similar in shape, albeit shorter than in sporadic AD brain, when examined by electron microscopy. Aβwild-type and Aβarctic codeposited and parenchymal deposits were highly enriched in both N- and C-terminally truncated Aβ. In contrast, cerebral amyloid angiopathy (CAA) contained a substantial amount of Aβ1-40. The absence of plaques with cores of fibrillary Aβ might be due to the scarcity of full-length Aβ, although other mechanisms could be involved. Our findings are discussed in relation to mechanisms and relevance of amyloid formation and to the clinical features of AD.
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| 5. |
- Ekman, Sirkka-Liisa, et al.
(författare)
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Alzheimer
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Moen, Vibeke, et al.
(författare)
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Feto-maternal osmotic balance at term. A prospective observational study
- 2018
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Ingår i: Journal of Perinatal Medicine. - : WALTER DE GRUYTER GMBH. - 0300-5577 .- 1619-3997. ; 46:2, s. 183-189
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Tidskriftsartikel (refereegranskat)abstract
- Objective: We performed the present study to investigate the feto-maternal osmotic relationship at term with the hypothesis that, in contrast to the literature, maternal plasma osmolality is lower than fetal levels. In a previous study, we found that maternal plasma sodium at delivery was consistently lower than the sodium in the umbilical artery. Our aim was to corroborate these results with analysis of osmolality. Methods: Blood was sampled from 30 women immediately before cesarean section and from the umbilical artery and vein before cord clamping and osmolality, sodium and albumin were analyzed. Results: Maternal osmolality was (mean; 95% confidence interval) 287.0 (285.8-288.2) mOsmkg/kg, arterial cord osmolality was 289.4 (287.9-291.0) mOsm/kg and venous cord osmolality was 287.3 (286.0-288.5) mOsm/kg. The paired difference between maternal and umbilical arterial osmolality was mean (SD) -2.4 (3.3) mOsm/kg (P amp;lt; 0.001), between maternal and umbilical vein -0.3 (3.0) mOsm/kg (P = 0.63) and between umbilical artery and vein -2.1 (2.8) mOsm/kg (P amp;lt; 0.001). Conclusion: Maternal osmolality was significantly lower than arterial cord osmolality confirming our previous results. The feto-maternal osmotic gradient favors water transport from the mother to the fetus and may increase the fetal risk of water intoxication when the mother ingests or is administered large volumes of electrolyte free solutions.
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| 7. |
- Axenhus, Michael, et al.
(författare)
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Changes in dementia diagnoses in Sweden during the COVID-19 pandemic
- 2022
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Ingår i: BMC Geriatrics. - : BioMed Central. - 1471-2318. ; 22:1
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The COVID-19 pandemic has caused large disruptions to healthcare systems. Refocus on COVID-19 related care might have contributed to indirect effects on other healthcare areas. Care focused on acute conditions have been negatively affected although research into the effects on chronic and care intensive patient groups such as patients with dementia diseases is lacking. In this study we evaluated dementia diagnosis trends in Sweden during 2015–2020 according to International Classification of Disease version 10 coding of common dementia diseases.Methods: Regional and national statistics in the form of International Classification of Disease version 10 coding, COVID-19 incidence, mortality data, and population census data were collected from the National Institute of Health and Welfare. Logistic regression analysis was performed to identify trends of dementia diagnosis during 2015–2020. Correlation test was performed between COVID-19 incidence, mortality rates, and dementia coding.Results: Dementia diagnosis incidence has been declining since 2015 and further decline was noted in many regions in Sweden during 2020. As COVID-19 incidence increased, fewer cases of dementia were diagnosed, a decrease that differentially impacted women and those who were advanced in age.Conclusions: Dementia diagnosis incidence in Sweden has been on a decline since 2015. The COVID-19 pandemic caused a further larger decline in dementia diagnosis incidence during 2020. COVID-19 incidence, but not mortality, was associated with decrease in dementia diagnosis incidence. There might be a large number of undiagnosed patients with dementia and healthcare reforms should be enacted to address this. Women and elderly are particularly vulnerable groups.
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| 8. |
- Carlsson, Hanna, et al.
(författare)
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Cell-Mediated Proteomics, and Serological and Mucosal Humoral Immune Responses after Seasonal Influenza Immunization: Characterization of Serological Responders and Non-Responders
- 2024
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Ingår i: Vaccines. - : MDPI. - 2076-393X. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- Immunization against influenza through vaccination is the most effective method with which to prevent infection. To assess protection after immunization, analysing humoral response with a hemagglutinin inhibition assay is the gold standard, but cell-mediated immune response has been shown to better correlate with protection in the elderly. Our aim was to explore the influenza-specific cell-mediated and mucosal humoral responses in serologically defined responders and non-responders. We analysed sera for total immunoglobulins (Ig) A, G, and M and nasal swab samples for influenza-specific IgA. Peripheral blood mononuclear cells were stimulated with trivalent influenza vaccine VaxiGripTetra, and supernatants were analysed for influenza-specific responses with the Olink Immune-Oncology panel using a proximity extension assay. We included 73 individuals, of which 69 completed the study with follow-up sampling at one and six months post-vaccination. Of the 73, 51 (70%) were found to be serological responders and 22 (30%) were non-responders. We did not find any significant differences in sex or mucosal humoral response between responders and non-responders; however, a higher IFN gamma/IL-10 ratio in individuals <= 65 years of age indicates an enhanced cell-mediated immune response in this age group. Characteristics of the non-responders were found to be higher levels of IgM, Granzyme B and Interleukin 12, and lower levels of C-X-C motif chemokine 13 compared with those of the responders. In conclusion, our results did not show any correlation between serological response and age. Furthermore, the majority of influenza-specific cell-mediated immune markers did not differ between responders and non-responders; the immune marker profile of the non-responders and its contribution to protection is of interest but needs to be further explored.
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| 9. |
- Carlsson, Hanna, et al.
(författare)
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Complement activation in individuals with previous subclinical Lyme borreliosis and patients with previous Lyme neuroborreliosis
- 2020
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Ingår i: European Journal of Clinical Microbiology and Infectious Diseases. - : Springer. - 0934-9723 .- 1435-4373. ; 39:5, s. 855-862
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Tidskriftsartikel (refereegranskat)abstract
- Lyme borreliosis (LB) is caused by Borrelia burgdorferi and infection may lead to not only a large variety of clinical manifestations but also a subclinical outcome. The aim of the present study was to investigate if there is a constitutional difference in complement activation between individuals with previous subclinical Lyme borreliosis (SB) and patients previously diagnosed with Lyme neuroborreliosis (LNB).Lepirudin plasma for activation studies was collected from 60 SB individuals and from 22 patients pre-diagnosed with LNB. The plasma was incubated with live Borrelia spirochetes of two strains (complement sensitive B. garinii Lu59 and complement resistant B. afzelii ACA1).Complement factor C3 was measured in non-activated lepirudin plasma with immune-nephelometry and C3a and sC5b-9 generated during complement activation were measured by enzyme-linked immunosorbent assay.We found that the complement sensitive Lu59 induced higher complement activation than the complement resistant ACA1 when measuring activation products C3a and sC5b-9 in SB and LNB patients, p < 0.0001. No significant difference was found between SB and LNB patients in systemic levels of C3. Furthermore, SB individuals generated a higher activation of C3 cleavage to C3a (C3a/C3 ratio) than LNB patients after activation with ACA1, p < 0.001, but no significant differences were found in response to Lu59. In conclusion, Lu59 induced higher complement activation than ACA1 and individuals with previous SB showed increased generation of C3a compared with patients with previous LNB. In our study population, this mechanism could lead to less elimination of spirochetes in LNB patients and thereby be a factor contributing to the clinical outcome.
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| 10. |
- Carlsson, Hanna, et al.
(författare)
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Subclinical Lyme borreliosis is common in south-eastern Sweden and may be distinguished from Lyme neuroborreliosis by sex, age and specific immune marker patterns
- 2018
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Ingår i: Ticks and Tick-borne Diseases. - : ELSEVIER GMBH, URBAN & FISCHER VERLAG. - 1877-959X .- 1877-9603. ; 9:3, s. 742-748
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Tidskriftsartikel (refereegranskat)abstract
- Background: Determinants of a subclinical course of Lyme borreliosis (LB) remain largely unknown. The aim of this study was to assess the extent, sex and age profiles of subclinical Borrelia seroconversion in a LB endemic area in Sweden and to map blood cellular Borrelia-specific immune marker patterns in individuals with a previous subclinical LB course compared with patients previously diagnosed with Lyme neuroborreliosis (LNB). Methods: A large group of 1113 healthy blood donors was screened for multiple IgG anti-Borrelia antibodies and asked to complete a health inquiry regarding previous LB. A group of subjects with anti-Borrelia-specific IgG antibodies but no previous history of LB (subclinical LB, n = 60) was identified together with 22 cases of previous LNB. Whole Borrelia spirochetes, strains B. afzelii ACA1 and B. garinii Ip90, were used for ex vivo whole blood stimulations, whereas outer surface protein enriched fractions of the same strains were used for stimulation of peripheral blood mononuclear cells (PBMCs). An extensive panel of immune markers was analysed in the supernatants after stimulation using multiplex bead arrays, and Borrelia-specific secretion was determined by subtracting the spontaneous secretion. Results: A total of 125/1113 blood donors reported previous clinical LB. In contrast, 66 donors denied previous LB but showed multiple IgG anti-Borrelia antibodies; these were defined as subclinical subjects, of whom 60 were available for further studies. The subclinical subjects consisted of significantly more men and had a younger age compared with the LNB patients (p amp;lt;= 0.01). Discriminant analysis revealed a distinct pattern of sex, age and PBMC B. garinii-specific levels of IL-10, IL-17A and CCL20 discriminating subclinical subjects from LNB patients. Conclusions: This study confirms that subclinical Borrelia seroconversion is common in south-eastern Sweden. The findings further suggest that male sex, younger age together with B. gariniii induced levels of IL-10, IL-17A and CCL20 may be associated with a subclinical course.
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| 11. |
- Domert, Jakob, 1986-
(författare)
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Neuron-to-neuron propagation of neurodegenerative proteins; relation to degradative systems
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Alzheimer’s disease (AD) and Parkinson’s disease (PD) are defined by neurodegeneration and accumulations of misfolded proteins that spread through the brain in a well characterized manner. In AD these accumulations consist mainly of β-amyloid (Aβ) and tau, while in PD, α-synuclein (α-syn) make up the characteristic lewy pathology. The general aim of this thesis was to investigate mechanisms associated with neurotoxic peptide activity by Aβ, tau and α-syn in relation to cellular degradation and transfer with a cell-to-cell transfer model system. We found that intercellular transfer of oligomeric Aβ occurs independently of isoform. However, the amount of transfer correlates with each isoforms ability to resist degradation or cellular clearance. The Aβ1-42 isoform showed particular resistance to clearance, which resulted in higher levels of cell-to-cell transfer of the isoform and lysosomal stress caused by accumulation. As Aβ accumulations can inhibit the proteasomal degradation we investigated how reduced proteasomal degradation affected neuron-like cells. We found increased levels of phosphorylated tau protein, disturbed microtubule stability and impaired neuritic transport after reduced proteasomal activity. These changes was partly linked to c-Jun and ERK 1/2 kinase activity. We could also show that α-syn transferred from cell-to-cell in our model system, with a higher degree of transfer for the larger oligomer and fibrillar species. Similar to Aβ, α-syn mainly colocalized with lysosomes, before and after transfer. Lastly, we have developed our cell-to-cell transfer system into a model suitable for high throughput screening (HTS). The type of cells have been upgraded from SH-SY5Y cells to induced pluripotent stem cells (iPSCs), with a differentiation profile more similar to mature neurons. The next step will be screening a small molecular library for substances with inhibitory effect on cell-to-cell transfer of Aβ peptides. The importance of the degradative systems in maintaining protein homeostasis and prevent toxic accumulations in general is well known. Our findings shows the importance of these systems for neurodegenerative diseases and also highlight the link between degradation and cell-to-cell transfer. To restore or enhance the degradative systems would be an interesting avenue to treat neurodegenerative diseases. Another way would be to inhibit the transfer of misfolded protein aggregates. By using the HTS model we developed, a candidate substance with good inhibitory effect on transfer can hopefully be found.
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| 12. |
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| 13. |
- Falkevall, Annelie, et al.
(författare)
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Degradation of the amyloid beta-protein by the novel mitochondrial peptidasome, PreP
- 2006
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 281:39, s. 29096-29104
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Tidskriftsartikel (refereegranskat)abstract
- Recently we have identified the novel mitochondrial peptidase responsible for degrading presequences and other short unstructured peptides in mitochondria, the presequence peptidase, which we named PreP peptidasome. In the present study we have identified and characterized the human PreP homologue, hPreP, in brain mitochondria, and we show its capacity to degrade the amyloid beta-protein (Abeta). PreP belongs to the pitrilysin oligopeptidase family M16C containing an inverted zinc-binding motif. We show that hPreP is localized to the mitochondrial matrix. In situ immuno-inactivation studies in human brain mitochondria using anti-hPreP antibodies showed complete inhibition of proteolytic activity against Abeta. We have cloned, overexpressed, and purified recombinant hPreP and its mutant with catalytic base Glu(78) in the inverted zinc-binding motif replaced by Gln. In vitro studies using recombinant hPreP and liquid chromatography nanospray tandem mass spectrometry revealed novel cleavage specificities against Abeta-(1-42), Abeta-(1-40), and Abeta Arctic, a protein that causes increased protofibril formation an early onset familial variant of Alzheimer disease. In contrast to insulin degrading enzyme, which is a functional analogue of hPreP, hPreP does not degrade insulin but does degrade insulin B-chain. Molecular modeling of hPreP based on the crystal structure at 2.1 A resolution of AtPreP allowed us to identify Cys(90) and Cys(527) that form disulfide bridges under oxidized conditions and might be involved in redox regulation of the enzyme. Degradation of the mitochondrial Abeta by hPreP may potentially be of importance in the pathology of Alzheimer disease.
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| 14. |
- Fredriksson, Tobias, et al.
(författare)
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Diagnostic patterns of serum inflammatory protein markers in children with Lyme neuroborreliosis
- 2024
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Ingår i: Ticks and Tick-borne Diseases. - : Elsevier. - 1877-959X .- 1877-9603. ; 15:4
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Tidskriftsartikel (refereegranskat)abstract
- Definite diagnosis of Lyme neuroborreliosis (LNB) requires investigation of serum and cerebrospinal fluid (CSF). Thus, lumbar puncture is necessary, and requires administration of sedating drugs in children. This study aimed to investigate if a pattern of different inflammatory biomarkers in serum could contribute to the selection of children for lumbar puncture in suspected LNB. Patients were included from a cohort of children who was previously investigated for LNB including serum and CSF sampling during the years 2010-2014. The multiplex proximity extension assay (PEA) inflammation panel Target 96 (Olink Bioscience, Uppsala, Sweden) was used to examine 92 biomarkers in serum. Based on the presence of CSF pleocytosis and Borrelia-specific antibodies, patients were divided into a definite LNB group (n=61) and a non-LNB control group (n=58). Following PEA and statistical analysis with multivariate logistic regression, five biomarkers remained significant (p < 0.001), which were included in a calculation of protein index. The index biomarkers were CST5, IL-15RA, CXCL10, DNER and CX3CL1. A receiver operating characteristic curve was constructed from the index, which showed an 80 % sensitivity and 81 % specificity. Area under the curve was 0.889. We offer evidence that, with further refinements, patterns of serum biomarkers might help identify those children more or less likely to have LNB, perhaps ultimately decreasing the need for lumbar punctures.
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| 15. |
- Frykman, Susanne, et al.
(författare)
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Synaptic and Endosomal Localization of Active gamma-Secretase in Rat Brain
- 2010
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 5:1, s. e8948-
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundA key player in the development of Alzheimer's disease (AD) is the gamma-secretase complex consisting of at least four components: presenilin, nicastrin, Aph-1 and Pen-2. gamma-Secretase is crucial for the generation of the neurotoxic amyloid beta-peptide (A beta) but also takes part in the processing of many other substrates. In cell lines, active gamma-secretase has been found to localize primarily to the Golgi apparatus, endosomes and plasma membranes. However, no thorough studies have been performed to show the subcellular localization of the active gamma-secretase in the affected organ of AD, namely the brain.Principal FindingsWe show by subcellular fractionation of rat brain that high gamma-secretase activity, as assessed by production of A beta 40, is present in an endosome-and plasma membrane-enriched fraction of an iodixanol gradient. We also prepared crude synaptic vesicles as well as synaptic membranes and both fractions showed high A beta 40 production and contained high amounts of the gamma-secretase components. Further purification of the synaptic vesicles verified the presence of the gamma-secretase components in these compartments. The localization of an active gamma-secretase in synapses and endosomes was confirmed in rat brain sections and neuronal cultures by using a biotinylated gamma-secretase inhibitor together with confocal microscopy.SignificanceThe information about the subcellular localization of gamma-secretase in brain is important for the understanding of the molecular mechanisms of AD. Furthermore, the identified fractions can be used as sources for highly active gamma-secretase.
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| 16. |
- Gao, Yang, et al.
(författare)
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Live Cell FRET Imaging Reveals Amyloid beta-Peptide Oligomerization in Hippocampal Neurons
- 2021
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 22:9
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Tidskriftsartikel (refereegranskat)abstract
- Amyloid beta-peptide (A beta) oligomerization is believed to contribute to the neuronal dysfunction in Alzheimer disease (AD). Despite decades of research, many details of A beta oligomerization in neurons still need to be revealed. Forster resonance energy transfer (FRET) is a simple but effective way to study molecular interactions. Here, we used a confocal microscope with a sensitive Airyscan detector for FRET detection. By live cell FRET imaging, we detected A beta 42 oligomerization in primary neurons. The neurons were incubated with fluorescently labeled A beta 42 in the cell culture medium for 24 h. A beta 42 were internalized and oligomerized in the lysosomes/late endosomes in a concentration-dependent manner. Both the cellular uptake and intracellular oligomerization of A beta 42 were significantly higher than for A beta 40. These findings provide a better understanding of A beta 42 oligomerization in neurons.
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| 17. |
- Goto, Masafumi, et al.
(författare)
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Dissecting the instant blood-mediated inflammatory reaction in islet xenotransplantation
- 2008
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Ingår i: Xenotransplantation. - : Wiley. - 0908-665X .- 1399-3089. ; 15:4, s. 225-234
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: A massive destruction of transplanted tissue occurs immediately following transplantation of pancreatic islets from pig to non-human primates. The detrimental instant blood-mediated inflammatory reaction (IBMIR), triggered by the porcine islets, is a likely explanation for this tissue loss. This reaction may also be responsible for mediating an adaptive immune response in the recipient that requires a heavy immunosuppressive regimen. MATERIALS AND METHODS: Low molecular weight dextran sulfate (LMW-DS) and the complement inhibitor Compstatin were used in a combination of in vitro and in vivo studies designed to dissect the xenogeneic IBMIR in a non-human primate model of pancreatic islet transplantation. Adult porcine islets (10,000 IEQs/kg) were transplanted intraportally into three pairs of cynomolgus monkeys that had been treated with LMW-DS or heparin (control), and the effects on the IBMIR were characterized. Porcine islets were also incubated in human blood plasma in vitro to assess complement inhibition by LMW-DS and Compstatin. RESULTS: Morphological scoring and immunohistochemical staining revealed that the severe islet destruction and macrophage, neutrophilic granulocyte, and T-cell infiltration observed in the control (heparin-treated) animals were abrogated in the LMW-DS-treated monkeys. Both coagulation and complement activation were significantly reduced in monkeys treated with LMW-DS, but IgM and complement fragments were still found on the islet surface. This residual complement activation could be inhibited by Compstatin in vitro. CONCLUSIONS: The xenogeneic IBMIR in this non-human primate model is characterized by an immediate binding of antibodies that triggers deleterious complement activation and a subsequent clotting reaction that leads to further complement activation. The effectiveness of LMW-DS (in vivo and in vitro) and Compstatin (in vitro) in inhibiting this IBMIR provides the basis for a protocol that can be used to abrogate the IBMIR in pig-human clinical islet transplantation.
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| 18. |
- Haytural, Hazal, et al.
(författare)
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Insights into the changes in the proteome of Alzheimer disease elucidated by a meta-analysis
- 2021
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Ingår i: Scientific Data. - : Springer Science and Business Media LLC. - 2052-4463. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Mass spectrometry (MS)-based proteomics is a powerful tool to explore pathogenic changes of a disease in an unbiased manner and has been used extensively in Alzheimer disease (AD) research. Here, by performing a meta-analysis of high-quality proteomic studies, we address which pathological changes are observed consistently and therefore most likely are of great importance for AD pathogenesis. We retrieved datasets, comprising a total of 21,588 distinct proteins identified across 857 postmortem human samples, from ten studies using labeled or label-free MS approaches. Our meta-analysis findings showed significant alterations of 757 and 1,195 proteins in AD in the labeled and label-free datasets, respectively. Only 33 proteins, some of which were associated with synaptic signaling, had the same directional change across the individual studies. However, despite alterations in individual proteins being different between the labeled and the label-free datasets, several pathways related to synaptic signaling, oxidative phosphorylation, immune response and extracellular matrix were commonly dysregulated in AD. These pathways represent robust changes in the human AD brain and warrant further investigation.
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| 19. |
- Keller, Lina, et al.
(författare)
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The PSEN1 I143T mutation in a Swedish family with Alzheimer's disease: clinical report and quantification of A beta in different brain regions
- 2010
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Ingår i: European Journal of Human Genetics. - London : Springer Science and Business Media LLC. - 1476-5438 .- 1018-4813. ; 18:11, s. 1202-1208
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Tidskriftsartikel (refereegranskat)abstract
- Early-onset dominantly inherited forms of Alzheimer's disease (AD) are rare, but studies of such cases have revealed important information about the disease mechanisms. Importantly, mutations in amyloid precursor protein (APP), presenilin 1 (PSEN1) and PSEN2, alter the APP processing and lead to an increased amyloid beta-peptide (A beta) 42/40 ratio. This, together with other studies on pathogenic mechanisms, show that A beta 42 is a major player in the etiology of AD. Here, we present a clinical and neuropathological description of a Swedish family with an I143T mutation in the PSEN1 gene, which gives rise to a severe form of AD. We also performed an extensive investigation on the concentration and distribution of A beta species of different lengths in six brain regions from two mutation carriers. Our study showed that A beta 42 and a longer peptide, A beta 43, were present both in plaque cores and in total amyloid preparations, and were each clearly more frequent than A beta 40 in all examined regions, as shown by both mass spectrometry and immunohistochemistry. European Journal of Human Genetics (2010) 18, 1202-1208; doi: 10.1038/ejhg.2010.107; published online 14 July 2010
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| 20. |
- Labbé Sandelin, Lisa, 1977-, et al.
(författare)
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Detection of Neoehrlichia mikurensis DNA in blood donors in southeastern Sweden
- 2022
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Ingår i: Infectious Diseases. - : Taylor & Francis Group. - 2374-4235 .- 2374-4243. ; 54:10, s. 748-759
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Tidskriftsartikel (refereegranskat)abstract
- Background The tick-borne bacterium Neoehrlichia mikurensis can cause persistent asymptomatic bloodstream infections, but transfusion-mediated transmission has not been reported. This study aimed to investigate the prevalence of N. mikurensis in blood donors, and recipients of blood components from N. mikurensis-positive donors were traced.Methods In 2019 and 2021, 1007 blood donors were recruited. Participants completed a questionnaire and additional blood samples were collected during blood donation. Detection of N. mikurensis was performed by PCR followed by sequencing. Positive donors were interviewed and retested. Look-back was performed on positive donations and on all subsequent donations.Results N. mikurensis was detected in 7/1006 (0.7%) donors. A total of 380/1005 (38%) donors reported at least one noticed tick bite during the current season. The questionnaire could not detect any differences between negative and positive N. mikurensis-donors. Two of the positive donors were still positive on days 318 and 131 after the index donation, respectively. One donor with persistent N. mikurensis in blood experienced slight fatigue. All other had no symptoms attributable to neoehrlichiosis. Look-back included ten donations and 20 blood components. Eight components were discarded, and 12 recipients of N. mikurensis-positive donations were identified. PCR was negative in seven recipients. Five recipients had died, but their medical records gave no evidence for neoehrlichiosis.Conclusions Although N. mikurensis was found in 0.7% of blood donors, transfusion-mediated infection was not detected, despite several recipients being at high risk for severe neoehrlichiosis. The results warrant further studies as well as raised clinical awareness.
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| 21. |
- Labbé Sandelin, Lisa, 1977-
(författare)
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Neoehrlichia mikurensis in Sweden : An emerging tick-borne human pathogen
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Neoehrlichia mikurensis is an emerging tick-borne human pathogen, causing neoehrlichiosis in immunosuppressed and immunocompetent individuals. It targets the vascular endothelium, leading to thromboembolic and vascular events, but can also pass without symptoms. As symptoms easily are misinterpreted, immunosuppressive treatment or chemotherapy is often incorrectly initiated. Diagnostic delay can be considerable.The overall aim of this thesis was to gain a better understanding on N. mikurensis in Sweden, focusing on human infections and public health aspects. The prevalence of N. mikurensis in different populations was examined. The symptomatology of neoehrlichiosis and the risk of transfusion-mediated transmission was studied. N. mikurensis was observed in low prevalences in ticks collected from migratory birds, in tick-bitten individuals, in patients with persistent symptoms attributed to presumed tick-bite exposure, and in blood donors. Fourteen N. mikurensis-positive individuals were identified. The majority were immunocompetent and asymptomatic. Both spontaneous clearance and persistence was observed. Two of 102 tick-bitten individuals were N. mikurensis-positive. Both presented with erythema migrans, but borreliosis was a more probable cause in both. The findings do not support a change in practice regarding first-line treatment of erythema migrans, but further studies are warranted.Persistence of N. mikurensis in blood raises questions regarding the possibility of transmission by transfusion and the risk of activating the infection if immune status is altered. N. mikurensis was identified in seven out of 1 006 blood donors. Look-back and tracing identified 12 recipients who were transfused with blood components from N. mikurensis-positive donors. Several recipients had multiple risk factors for severe neoehrlichiosis, but transfusion-transmitted neoehrlichiosis was not detected. Nevertheless, the possibility that N. mikurensis can be transmitted by transfusion cannot be excluded.Isolates from birds and blood donors were identical to previously reported Swedish human isolates. Migrating birds can act as dispersal vectors of N. mikurensis, but their role as transmission hosts is still unclear.The disease burden and public health impact of neoehrlichiosis is probably small, but information is lacking in several areas. Suspicion of neoehrlichiosis is warranted in immunocompromised and/or splenectomised patients with persistent fever, with or without thromboembolic and vascular events. Furthermore, neoehrlichiosis should be included in the differential diagnosis of anaplasmosis. Besides raised awareness, a possible mandatory notification is proposed as well as a comprehensive surveillance system for transfusion-transmitted infections. One of the priority issues is the possible need for screening of patients living in N. mikurensis-endemic areas before and during immunosuppressive treatment.
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| 22. |
- Larsson, Annika, et al.
(författare)
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Unwinding fibril formation of medin, the peptide of the most common form of human amyloid.
- 2007
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 361:4, s. 822-828
-
Tidskriftsartikel (refereegranskat)abstract
- Medin amyloid affects the medial layer of the thoracic aorta of most people above 50 years of age. The consequences of this amyloid are not completely known but the deposits may contribute to diseases such as thoracic aortic aneurysm and dissection or to the general diminished elasticity of blood vessels seen in elderly people. We show that the 50-amino acid residue peptide medin forms amyloid-like fibrils in vitro. With the use of Congo red staining, Thioflavin T fluorescence, electron microscopy, and a solid-phase binding assay on different synthetic peptides, we identified the last 18-19 amino acid residues to constitute the amyloid-promoting region of medin. We also demonstrate that the two C-terminal phenylalanines, previously suggested to be of importance for amyloid formation, are not required for medin amyloid formation.
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| 23. |
- Lindhagen Persson, Malin, 1982-
(författare)
-
Targeting cytotoxic species in amyloid diseases
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Amyloid diseases are a world-wide problem causing great human suffer and large economical costs. Although amyloid deposits, a common denominator in all amyloid disorders, are detrimental to the surrounding tissue, there is a poor correlation between total amyloid burden and clinical symptoms. Soluble oligomers are much more potent to exert a tissue damaging effect. Alzheimer’s disease (AD) is strongly linked to self-assembly of the amyloid-β (Aβ) peptide. Antibodies selectively targeting cytotoxic Aβ-species are useful both for understanding oligomer formation and for their therapeutic abilities. We hypothesized that the effect of avidity would compensate for a low single site affinity and be enough to selectively target oligomers. To evaluate this hypothesis, we focused on the IgM isotype having ten antigen-binding sites. In accordance with the hypothesis, the IgM isotype effectively bound oligomeric Aβ also in presence of a vast excess of its monomeric counterpart, clearly illustrating the potentiating effect of avidity. As a continuation of this work, we have shown that the avidity effect from a bivalent binding is enough to induce oligomer specificity. This finding facilitates a direct application on the clinically more useful IgG isotype, where the binding properties now can be controlled in detail. The method is general and we have, using this technique, also designed oligomer specific antibodies targeting α-synuclein. Transthyretin (TTR) is an amyloidogenic protein involved in both hereditary and sporadic amyloidosis. The cytotoxicity of TTR is intriguing since studies have shown cytotoxic potential from oligomers, tetramers and even monomers. Elucidation of the molecular properties associated with TTR cytotoxicity is hence of interest. By preventing tetramer dissociation, TTR aggregation and TTR-induced cytotoxicity is abolished. Based on this rationale, a current therapeutic strategy is to stabilize the TTR tetramer with small molecules. The kinetic stability within the spectra of known TTR mutations spans more than three orders of magnitude. However, although the most stable mutants are inert, a poor correlation within the group of cytotoxic variants exists where the cytotoxic effect is not potentiated in proportion to their kinetic stability. Through analysis of a large spectra of TTR variants, our results indicate that TTR induced cytotoxicity requires an intermediate stability of the TTR molecule. The kinetic stability should be low enough to permit tetramer dissociation and the thermodynamic stability high enough to prevent instant aggregation and to allow formation of the cytotoxic fold.
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| 24. |
- Lu, Jun, et al.
(författare)
-
Ebsulfur is a benzisothiazolone cytocidal inhibitor targeting the trypanothione reductase of Trypanosoma brucei
- 2013
-
Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 288:38, s. 27456-27468
-
Tidskriftsartikel (refereegranskat)abstract
- Trypanosoma brucei is the causing agent of African trypanosomiasis. These parasites possess a unique thiol redox system required for DNA synthesis and defense against oxidative stress. It includes trypanothione and trypanothione reductase (TryR) instead of the thioredoxin and glutaredoxin systems of mammalian hosts. Here, we show that the benzisothiazolone compound ebsulfur (EbS), a sulfur analogue of ebselen, is a potent inhibitor of T. brucei growth with a favorable selectivity index over mammalian cells. EbS inhibited the TryR activity and decreased non-protein thiol levels in cultured parasites. The inhibition of TryR by EbS was irreversible and NADPH-dependent. EbS formed a complex with TryR and caused oxidation and inactivation of the enzyme. EbS was more toxic for T. brucei than for Trypanosoma cruzi, probably due to lower levels of TryR and trypanothione in T. brucei. Furthermore, inhibition of TryR produced high intracellular reactive oxygen species. Hydrogen peroxide, known to be constitutively high in T. brucei, enhanced the EbS inhibition of TryR. The elevation of reactive oxygen species production in parasites caused by EbS induced a programmed cell death. Soluble EbS analogues were synthesized and cured T. brucei brucei infection in mice when used together with nifurtimox. Altogether, EbS and EbS analogues disrupt the trypanothione system, hampering the defense against oxidative stress. Thus, EbS is a promising lead for development of drugs against African trypanosomiasis.
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| 25. |
- Lundgren, Jolanta L, et al.
(författare)
-
Activity-independent release of the amyloid β-peptide from rat brain nerve terminals.
- 2014
-
Ingår i: Neuroscience Letters. - : Elsevier BV. - 0304-3940 .- 1872-7972. ; 566:Mar 3, s. 125-130
-
Tidskriftsartikel (refereegranskat)abstract
- Synaptic degeneration is one of the earliest hallmarks of Alzheimer disease. The molecular mechanism underlying this degeneration is not fully elucidated but one key player appears to be the synaptotoxic amyloid β-peptide (Aβ). The exact localization of the production of Aβ and the mechanisms whereby Aβ is released remain elusive. We have earlier shown that Aβ can be produced in crude synaptic vesicle fractions and it has been reported that increased synaptic activity results in increased secreted but decreased intracellular Aβ levels. Therefore, we considered whether Aβ could be produced in synaptic vesicles and/or released through the same mechanisms as neurotransmitters in synaptic vesicle exocytosis. Small amounts of Aβ were found to be produced in pure synaptic vesicle preparations. We also studied the release of glutamate and Aβ from rat cortical nerve terminals (synaptosomes). We found that large amounts of Aβ were secreted from non-stimulated synaptosomes, from which glutamate was not released. On the contrary, we could not detect any differences in Aβ release between non-stimulated synaptosomes and synaptosomes stimulated with KCl or 4-aminopyridine, whereas glutamate release was readily inducible in this system. To conclude, our results indicate that the major release mechanism of Aβ from isolated nerve terminals differs from the synaptic release of glutamate and that the activity-dependent increase of secreted Aβ, reported by several groups using intact cells, is likely dependent on post-synaptic events, trafficking and/or protein synthesis mechanisms.
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| 26. |
- Lundgren, Jolanta L, et al.
(författare)
-
ADAM10 and BACE1 are localized to synaptic vesicles.
- 2015
-
Ingår i: Journal of Neurochemistry. - : Wiley. - 1471-4159 .- 0022-3042. ; 135:3, s. 606-615
-
Tidskriftsartikel (refereegranskat)abstract
- Synaptic degeneration and accumulation of the neurotoxic amyloid β-peptide (Aβ) in the brain are hallmarks of Alzheimer disease. Aβ is produced by sequential cleavage of its precursor protein, APP, by the β-secretase BACE1 and γ-secretase. However, Aβ generation is precluded if APP is cleaved by the α-secretase ADAM10 instead of BACE1. We have previously shown that Aβ can be produced locally at the synapse. To study the synaptic localization of the APP processing enzymes we used western blotting to demonstrate that, compared to total brain homogenate, ADAM10 and BACE1 were greatly enriched in synaptic vesicles isolated from rat brain using controlled-pore glass chromatography, whereas Presenilin1 was the only enriched component of the γ-secretase complex. Moreover, we detected ADAM10 activity in synaptic vesicles and enrichment of the intermediate APP-C-terminal fractions (APP-CTFs). We confirmed the western blotting findings using in situ proximity ligation assay to demonstrate close proximity of ADAM10 and BACE1 with the synaptic vesicle marker synaptophysin in intact mouse primary hippocampal neurons. In contrast, only sparse co-localization of active γ-secretase and synaptophysin was detected. These results indicate that the first step of APP processing occurs in synaptic vesicles whereas the final step is more likely to take place elsewhere. This article is protected by copyright. All rights reserved.
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| 27. |
- Martinsson, Isak, et al.
(författare)
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APP depletion alters selective pre- and post-synaptic proteins
- 2019
-
Ingår i: Molecular and Cellular Neuroscience. - : Elsevier BV. - 1044-7431 .- 1095-9327. ; 95, s. 86-95
-
Tidskriftsartikel (refereegranskat)abstract
- The normal role of Alzheimer's disease (AD)-linked amyloid precursor protein (APP) in the brain remains incompletely understood. Previous studies have reported that lack of APP has detrimental effects on spines and electrophysiological parameters. APP has been described to be important in synaptic pruning during development. The effect of APP knockout on mature synapses is complicated by this role in development. We previously reported on differential changes in synaptic proteins and receptors in APP mutant AD transgenic compared to wild-type neurons, which revealed selective decreases in levels of pre- and post-synaptic proteins, including of surface glutamate receptors. In the present study, we undertook a similar analysis of synaptic composition but now in APP knockout compared to wild-type mouse neurons. Here we demonstrate alterations in levels of selective pre- and post-synaptic proteins and receptors in APP knockout compared to wild-type mouse primary neurons in culture and brains of mice in youth and adulthood. Remarkably, we demonstrate selective increases in levels of synaptic proteins, such as GluA1, in neurons with APP knockout and with RNAi knockdown, which tended to be opposite to the reductions seen in AD transgenic APP mutant compared to wild-type neurons. These data reinforce that APP is important for the normal composition of synapses.
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| 28. |
- Nahalkova, Jarmila, et al.
(författare)
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CD147, a gamma-secretase associated protein is upregulated in Alzheimer's disease brain and its cellular trafficking is affected by presenilin-2
- 2010
-
Ingår i: Neurochemistry International. - : Elsevier BV. - 0197-0186 .- 1872-9754. ; 56:1, s. 67-76
-
Tidskriftsartikel (refereegranskat)abstract
- gamma-Secretase activity has been extensively investigated due to its role in Alzheimer's disease. Here, we studied the association of CD147, a transmembrane glycoprotein belonging to the immunoglobulin family, with gamma-secretase and its expression in Alzheimer's disease and control tissues. Subcellular fractionation of postmitochondrial supernatant from Fat brain on step iodixanol gradient in combination with co-immunoprecipitation using an anti-nicastrin antibody showed association of limited amount of CD147 to gamma-secretase. By immunoblotting of postnuclear pellets from Alzheimer's disease and control human brain tissues we showed that CD147 with molecular weight 75 kDa is upregulated in frontal cortex and thalamus of the Alzheimer's disease brains. Immunohistochemistry of brain tissues from Alzheimer's disease and control revealed specific Upregulation of CD147 in neurons, axons and capillaries of Alzheimer's disease frontal cortex and thalamus. The effect of presenilin-1 and -2, which are the catalytic subunits of gamma-secretase, on CD147 expression and subcellular localization was analyzed by confocal microscopy in combination with flow cytometry and showed that PS2 affected the subcellular localization of CD147 in Mouse embryonic fibroblast cells. We suggest that a small fraction of CD147 present in the brain is associated with the gamma-secretase, and can be involved in mechanisms dysregulated in Alzheimer's disease brain.
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| 29. |
- Nilsson, Per, et al.
(författare)
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Loss of neprilysin alters protein expression in the brain of Alzheimer's disease model mice
- 2015
-
Ingår i: Proteomics. - : Wiley. - 1615-9853 .- 1615-9861. ; 15:19, s. 3349-3355
-
Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease (AD) is a neurodegenerative disease displaying extracellular plaques formed by the neurotoxic amyloid -peptide (A), and intracellular neurofibrillary tangles consisting of protein tau. However, how these pathologies relate to the massive neuronal death that occurs in AD brains remain elusive. Neprilysin is the major A-degrading enzyme and a lack thereof increases A levels in the brain twofold. To identify altered protein expression levels induced by increased A levels, we performed a proteomic analysis of the brain of the AD mouse model APPsw and compared it to that of APPsw mice lacking neprilysin. To this end we established an LC-MS/MS method to analyze brain homogenate, using an O-18-labeled internal standard to accurately quantify the protein levels. To distinguish between alterations in protein levels caused by increased A levels and those induced by neprilysin deficiency independently of A, the brain proteome of neprilysin deficient APPsw mice was also compared to that of neprilysin deficient mice. By this approach we identified approximately 600 proteins and the levels of 300 of these were quantified. Pathway analysis showed that many of the proteins with altered expression were involved in neurological disorders, and that tau, presenilin and APP were key regulators in the identified networks. The data have been deposited to the ProteomeXchange Consortium with identifiers PXD000968 and PXD001786 ( and (). Interestingly, the levels of several proteins, including some not previously reported to be linked to AD, were associated with increased A levels.
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| 30. |
- Ottvall, Richard, et al.
(författare)
-
Population trends for Swedish breeding birds
- 2009
-
Ingår i: Ornis Svecica. - 1102-6812. ; 19:3, s. 117-192
-
Tidskriftsartikel (refereegranskat)abstract
- We have assessed the population trends for the 255 bird species breeding in Sweden (including distinct subspecies), based on data for the last 30 and 10 years, respectively. Over the past 30 years more species have decreased (38%) than increased (32%) in numbers. In particular, formerly common farmland species have fared poorly but this is also true for some forest species. Over the past 10 years there are more species with increasing trends (29%) than there are species with decreasing trends (19%). Trends for several species in long-term decline have levelled off and have in some cases even started to increase. It is not known whether this recent change is a result of conservation efforts or simply that population numbers have stabilised at lower levels now permitted by the environment. It is therefore essential to initiate research devoted to finding factors directly linked to ongoing population changes, particularly for species in longterm decline. To cover population trends for all Swedish species additional monitoring programmes are needed, in particular on owls and in mountain habitats.
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| 31. |
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| 32. |
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| 33. |
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| 34. |
- Rising, Anna, et al.
(författare)
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Systemic AA amyloidosis in the red fox (Vulpes vulpes)
- 2017
-
Ingår i: Protein Science. - : WILEY. - 0961-8368 .- 1469-896X. ; 26:11, s. 2312-2318
-
Tidskriftsartikel (refereegranskat)abstract
- Amyloid A (AA) amyloidosis occurs spontaneously in many mammals and birds, but the prevalence varies considerably among different species, and even among subgroups of the same species. The Blue fox and the Gray fox seem to be resistant to the development of AA amyloidosis, while Island foxes have a high prevalence of the disease. Herein, we report on the identification of AA amyloidosis in the Red fox (Vulpes vulpes). Edman degradation and tandem MS analysis of proteolyzed amyloid protein revealed that the amyloid partly was composed of full-length SAA. Its amino acid sequence was determined and found to consist of 111 amino acid residues. Based on inter-species sequence comparisons we found four residue exchanges (Ser31, Lys63, Leu71, Lys72) between the Red and Blue fox SAAs. Lys63 seems unique to the Red fox SAA. We found no obvious explanation to how these exchanges might correlate with the reported differences in SAA amyloidogenicity. Furthermore, in contrast to fibrils from many other mammalian species, the isolated amyloid fibrils from Red fox did not seed AA amyloidosis in a mouse model.
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| 35. |
- Sandebring, Anna, et al.
(författare)
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The Pathogenic A beta 43 Is Enriched in Familial and Sporadic Alzheimer Disease
- 2013
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:2, s. e55847-
-
Tidskriftsartikel (refereegranskat)abstract
- The amyloid-cascade hypothesis posits that the role of amyloid beta-peptide (A beta) in Alzheimer disease (AD) involves polymerization into structures that eventually are deposited as amyloid plaques. During this process, neurotoxic oligomers are formed that induce synaptic loss and neuronal death. Several different isoforms of A beta are produced, of which the 40 and 42 residue variants (A beta 40 and A beta 42) are the most common. A beta 42 has a strong tendency to form neurotoxic aggregates and is involved in AD pathogenesis. Longer A beta isoforms, like the less studied A beta 43, are gaining attention for their higher propensity to aggregate into neurotoxic oligomers. To further investigate A beta 43 in AD, we conducted a quantitative study on A beta 43 levels in human brain. We homogenized human brain tissue and prepared fractions of various solubility; tris buffered saline (TBS), sodium dodecyl sulfate (SDS) and formic acid (FA). Levels of A beta 43, as well as A beta 40 and A beta 42, were quantified using ELISA. We compared quantitative data showing A beta levels in occipital and frontal cortex from sporadic (SAD) and familial (FAD) AD cases, as well as non-demented (ND) controls. Results showed A beta 43 present in each fraction from the SAD and FAD cases, while its level was lower than the detection limit in the majority of the ND-cases. A beta 42 and A beta 43 were enriched in the less soluble fractions (SDS and FA) of SAD and FAD cases in both occipital and frontal cortex. Thus, although the total levels of A beta 43 in human brain are low compared to A beta 40 and A beta 42, we suggest that A beta 43 could initiate the formation of oligomers and amyloid plaques and thereby be crucial to AD pathogenesis.
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| 36. |
- Schedin-Weiss, Sophia, et al.
(författare)
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Super-resolution microscopy reveals gamma-secretase at both sides of the neuronal synapse
- 2016
-
Ingår i: Acta neuropathologica communications. - : BioMed Central. - 2051-5960. ; 4
-
Tidskriftsartikel (refereegranskat)abstract
- The transmembrane protein assembly gamma-secretase is a key protease in regulated intramembrane processing (RIP) of around 100 type-1 transmembrane proteins. Importantly, it has a pathological role in Alzheimer disease (AD) as it generates the neurotoxic amyloid beta-peptide from the amyloid precursor protein (APP). Studies on gamma-secretase location are therefore crucial both from a biological and a therapeutic perspective. Despite several years of efforts in many laboratories, it is not clear where in the neuron gamma-secretase exerts it's activities. Technical challenges include the fact that the active enzyme contains four protein components and that most subcellular compartments cannot be spatially resolved by traditional light microscopy. Here, we have used a powerful combination of the two nanoscopy techniques STORM and STED microscopy to visualize the location of gamma-secretase in neurons using an active-site specific probe, with a focus on the synapse. We show that gamma-secretase is present in both the pre-and postsynaptic compartments. We further show that the enzyme is enriched very close to the synaptic cleft in the postsynaptic membrane, as well as to NMDA receptors, demonstrating that gamma-secretase is present in the postsynaptic plasma membrane. Importantly, the expression of gamma-secretase increased in the pre-and postsynaptic compartments with the size of the synapse, suggesting a correlation between gamma-secretase activity and synapse maturation. Thus, our data shows the synaptic location with high precision in three dimensions and settles the long-lasting debate on the synaptic location of gamma-secretase.
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| 37. |
- Skogman, Barbro Hedin, 1967-, et al.
(författare)
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Cytokines and chemokines in cerebrospinal fluid in relation to diagnosis, clinical presentation and recovery in children being evaluated for Lyme neuroborreliosis
- 2020
-
Ingår i: Ticks and Tick-borne Diseases. - : Elsevier. - 1877-959X .- 1877-9603. ; 11:3
-
Tidskriftsartikel (refereegranskat)abstract
- In Lyme neuroborrelios (LNB), the immune response has been in focus, but the association between different cytokines/chemokines and clinical manifestations in LNB patients has not been fully investigated. The aim of this study was to evaluate a large number of cytokines and chemokines in cerebrospinal fluid (CSF) in relation to diagnosis, clinical presentation and recovery in children being evaluated for LNB.Materials and methods: Pediatric patients (n = 105) were recruited at seven Swedish pediatric departments during 2010-14. Serum and CSF samples were drawn on admission, before start of antibiotic treatment. Patients diagnosed as Definite LNB or Possible LNB were categorized as LNBtot patients, all LNBtot patients presented with pleocytosis in CSF. Patients diagnosed as Non-LNB or Other diagnosis were categorized as Controls(tot), all controls(tot) presented without pleocytosis in CSF. Multiplex bead array (Luminex) kits were used for analyses of 41 different cytokines/chemokines in CSF (Millipore).Results: Twenty-eight cytokines/chemokines were detectable in CSF and the levels of 26 of these mediators were significantly higher in LNBtot patients than in Controls(tot). In a discriminant analysis, a combination of four cytokines/chemokines (CXCL1, GM-CSF, IL-7 and IL-10) were shown to independently separate relevant patient groups. Furthermore, an IL-10/CXCL1 ratio was created and shown to have an improved diagnostic performance in distinguishing LNBtot vs Non-LNB patients, as compared to CXCL13 in CSF. No immune mediator differed significantly, when comparing LNBtot patients with different clinical presentation on admission or when comparing patients with or without recovery within 2 months of admission.Conclusion: A discriminant analysis was shown to be useful to distinguish the independently most important cytokines/chemokines (CXCL1, GM-CSF, IL-7 and IL-10) in CSF, in order to discriminate LNBtot patients from Non-LNB patients. An IL-10/CXCL1 ratio was shown to have a promising diagnostic profile with a better performance than the chemokine CXCL13 in CSF. However, further evaluation is required to address future possible usefulness of these cytokines and chemokines in laboratory diagnostics in LNB, including control groups with neuro-inflammation. No significant associations were found between CSF immune mediator levels and clinical presentation or recovery in pediatric LNB patients.
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| 38. |
- Teranishi, Yasuhiro, et al.
(författare)
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Erlin-2 is associated with active γ-secretase in brain and affects amyloid β-peptide production
- 2012
-
Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 424:3, s. 476-481
-
Tidskriftsartikel (refereegranskat)abstract
- The transmembrane protease complex γ-secretase is responsible for the generation of the neurotoxic amyloid β-peptide (Aβ) from its precursor (APP). Aβ has a causative role in Alzheimer disease, and thus, γ-secretase is a therapeutic target. However, since there are more than 70 γ-secretase substrates besides APP, selective inhibition of APP processing is required. Recent data indicates the existence of several γ-secretase associated proteins (GSAPs) that affect the selection and processing of substrates. Here, we use a γ-secretase inhibitor for affinity purification of γ-secretase and associated proteins from microsomes and detergent resistant membranes (DRMs) prepared from rat or human brain. By tandem mass spectrometry we identified a novel brain GSAP; erlin-2. This protein was recently reported to reside in DRMs in the ER. A proximity ligation assay, as well as co-immunoprecipitation, confirmed the association of erlin-2 with γ-secretase. We found that a higher proportion of erlin-2 was associated with γ-secretase in DRMs than in soluble membranes. siRNA experiments indicated that reduced levels of erlin-2 resulted in a decreased Aβ production, whereas the effect on Notch processing was limited. In summary, we have found a novel brain GSAP, erlin-2, that resides in DRMs and affects Aβ production.
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| 39. |
- Tjernberg, Ivar, et al.
(författare)
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Identification of potential biomarkers in active Lyme borreliosis
- 2023
-
Ingår i: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 18:6
-
Tidskriftsartikel (refereegranskat)abstract
- ObjectivesLyme serology does not readily discriminate an active Lyme borreliosis (LB) from a previous Borrelia infection or exposure. Here, we aimed to investigate a large number of immunological protein biomarkers to search for an immunological pattern typical for active LB, in contrast to patterns found in healthy blood donors, a proportion of whom were previously exposed to Borrelia. MethodsSerum samples from well-characterised adult patients with ongoing LB and healthy blood donors were included and investigated using a proximity extension assay (provided by Olink & REG;) by which 92 different immune response-related human protein biomarkers were analysed simultaneously. ResultsIn total, 52 LB patients and 75 healthy blood donors were included. The blood donors represented both previously Borrelia exposed (n = 34) and not exposed (n = 41) based on anti-Borrelia antibody status. Ten of the examined 92 proteins differed between patients and blood donors and were chosen for further logistic regression (p<0.1). Six proteins were statistically significantly different between LB patients and blood donors (p<0.05). These six proteins were then combined in an index and analysed using receiver-operating-characteristic curve analysis showing an area under the curve of 0.964 (p<0.001). ConclusionsThe results from this study suggest that there is an immunological protein pattern that can distinguish a present Borrelia infection from a previous exposure as well as anti-Borrelia antibody negative blood donors. Although this method is not adapted for routine clinical use at this point, the possibility is interesting and may open new diagnostic opportunities improving the laboratory diagnostics of LB.
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| 40. |
- Tjernberg, Lars
(författare)
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Molecular basis and pharmacological implications of Alzheimer amyloid ß-peptide fibril formation
- 1998
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Alzheimer's disease is a progressive neurodegenerative disease, mostly affecting elderly. The invariable deposition of protease-resistant fibrils of Alzheimer amyloid ß-peptide (Aß) in the parenchyma and blood vessels of the brain is a central event. The aim of this study was to investigate whether Aß develops protease resistance upon polymerization and whether Aß may be generated through non-specific proteolysis of a polymerized precursor, to identify Aß-Aß binding and fibril forming sequences in Aß and define the molecular basis of Aß polymerization, and to find inhibitors of fibril formation. To investigate if Aß fibril formation is sufficient to acquire protease resistance, non-polymerized and polymerized Aß were treated with an array of proteases. Non-polymerized Aß was degraded whereas fibrils were resistant to proteolysis. The proteases generating Aß from its precursor, APP, have not been identified. We show that Aß can be generated through nonspecific proteolysis of a polymerized precursor. A C-terminal fragment of APP was purified and allowed to polymerize. Fibrils remained after digestion with proteinase K, an enzyme capable of cleaving most peptide bonds. The fibrils were dissolved and subjected to gel electrophoresis, showing an Aß immunoreactive band comigrating with synthetic Aß. A sequence critical for Aß-Aß binding was identified by incubating decapeptides corresponding to various Aß sequences with labeled Aß by systematically truncating binding peptides, the shortest sequence mediating intact Aß binding was found to be Aß 16-20 Short peptides containing this sequence inhibited fibril formation. Further studies showed that Aß 16-20 bound to the homologous region in Aß. The Aß 16-20 sequence was used as a labeled probe to search for binders in a combinatorial library consisting of pentapeptides composed of D-amino acids. The most efficient binders were incubated with Aß and found capable of inhibiting fibril formation. Hence, short Aß 16-20 containing peptides can be used to identify inhibitors of Aß fibril formation in combinatorial libraries. Fluorescence correlation spectroscopy (FCS) was used to follow the polymerization of Aß in solution. Initially, only monomers/dimers were observed and polymerization was found to proceed over large aggregates, via small aggregates into mature fibrils. The amounts of aggregates were reduced in the presence of an inhibitor and formed aggregates were partly dissolved after addition of an inhibitor. Labeled inhibitor bound to monomeric/dimeric Aß as well as aggregates and was displaced by unlabeled inhibitor. The shortest fibril forming sequence containing the Aß-Aß binding motif was identified by systematically elongating and truncating sequences containing Aß 16-20. The shortest sequence forming Aß-like fibrils was Aß 14-23. Substitutions and truncations in this peptide yielded ultrastructurally different aggregates, none resembling Aß fibrils. A model with favorable hydrophobic and ionic interactions between two Aß 14-23 peptides in an antiparalell ß-sheet configuration were subjected to molecular modeling. Two dimers were aligned to form a tetramer, which could be the smallest repeating unit in fibrils. It is suggested that these interactions are present also in Aß fibrils.
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| 41. |
- Wanngren, Johanna, et al.
(författare)
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Changed membrane integration and catalytic site conformation are two mechanisms behind the increased Aβ42/Aβ40 ratio by presenilin 1 familial Alzheimer-linked mutations.
- 2014
-
Ingår i: FEBS Open Bio. - : Wiley. - 2211-5463. ; 4, s. 393-406
-
Tidskriftsartikel (refereegranskat)abstract
- The enzyme complex γ-secretase generates amyloid β-peptide (Aβ), a 37-43-residue peptide associated with Alzheimer disease (AD). Mutations in presenilin 1 (PS1), the catalytical subunit of γ-secretase, result in familial AD (FAD). A unifying theme among FAD mutations is an alteration in the ratio Aβ species produced (the Aβ42/Aβ40 ratio), but the molecular mechanisms responsible remain elusive. In this report we have studied the impact of several different PS1 FAD mutations on the integration of selected PS1 transmembrane domains and on PS1 active site conformation, and whether any effects translate to a particular amyloid precursor protein (APP) processing phenotype. Most mutations studied caused an increase in the Aβ42/Aβ40 ratio, but via different mechanisms. The mutations that caused a particular large increase in the Aβ42/Aβ40 ratio did also display an impaired APP intracellular domain (AICD) formation and a lower total Aβ production. Interestingly, seven mutations close to the catalytic site caused a severely impaired integration of proximal transmembrane/hydrophobic sequences into the membrane. This structural defect did not correlate to a particular APP processing phenotype. Six selected FAD mutations, all of which exhibited different APP processing profiles and impact on PS1 transmembrane domain integration, were found to display an altered active site conformation. Combined, our data suggest that FAD mutations affect the PS1 structure and active site differently, resulting in several complex APP processing phenotypes, where the most aggressive mutations in terms of increased Aβ42/Aβ40 ratio are associated with a decrease in total γ-secretase activity.
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| 42. |
- Wennmalm, Stefan, et al.
(författare)
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Highly Sensitive FRET-FCS Detects Amyloid beta-Peptide Oligomers in Solution at Physiological Concentrations
- 2015
-
Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 87:23, s. 11700-11705
-
Tidskriftsartikel (refereegranskat)abstract
- Oligomers formed by the amyloid beta-peptide (A beta) are pathogens in Alzheimers disease. Increased knowledge on the oligomerization process is crucial for understanding the disease and for finding treatments. Ideally, A beta oligomerization should be studied in solution and at physiologically relevant concentrations, but most popular techniques of today are not capable of such analyses. We demonstrate here that the combination of FOrster Resonance Energy Transfer and Fluorescence Correlation Spectroscopy (FRET-FCS) has a unique ability to detect small subpopulations of FRET-active molecules and oligomers. FRET-FCS could readily detect a FRET-active oligonucleotide present at levels as low as 0.5% compared to FRET-inactive dye molecules. In contrast, three established fluorescence fluctuation techniques (FCS, FCCS, and PCH) required fractions between 7 and 11%. When applied to the analysis of A beta, FRET-FCS detected oligomers consisting of less than 10 A beta molecules, which coexisted with the monomers at fractions as low as 2 +/- 2%. Thus, we demonstrate for the first time direct detection of small fractions of A beta oligomers in solution at physiological concentrations. This ability of FRET-FCS could be an indispensable tool for studying biological oligomerization processes, in general, and for finding therapeutically useful oligomerization inhibitors.
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| 43. |
- Yu, Yang, et al.
(författare)
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Neuronal A beta 42 is enriched in small vesicles at the presynaptic side of synapses
- 2018
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Ingår i: Life Science Alliance. - : LIFE SCIENCE ALLIANCE LLC. - 2575-1077. ; 1:3
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Tidskriftsartikel (refereegranskat)abstract
- The amyloid beta-peptide (A beta) is a physiological ubiquitously expressed peptide suggested to be involved in synaptic function, long-term potentiation, and memory function. The 42 amino acid-long variant (A beta 42) forms neurotoxic oligomers and amyloid plaques and plays a key role in the loss of synapses and other pathogenic events of Alzheimer disease. Still, the exact localization of A beta 42 in neurons and at synapses has not been reported. Here, we used super-resolution microscopy and show that A beta 42 was present in small vesicles in presynaptic compartments, but not in postsynaptic compartments, in the neurites of hippocampal neurons. Some of these vesicles appeared to lack synaptophysin, indicating that they differ from the synaptic vesicles responsible for neurotransmitter release. The A beta 42-containing vesicles existed in presynapses connected to stubby spines and mushroom spines, and were also present in immature presynapses. These vesicleswere scarce inother parts of the neurites, where A beta 42 was instead present in large, around 200-600 nm, vesicular structures. Three-dimensional super-resolution microscopy confirmed that A beta 42 was present in the presynapse and absent in the postsynapse.
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| 44. |
- Zhou, Robin Ziyue, et al.
(författare)
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A glycan epitope correlates with tau in serum and predicts progression to Alzheimer's disease in combination with APOE4 allele status
- 2023
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Ingår i: Alzheimer's & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 19:7, s. 3244-3249
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: There is an urgent need for novel blood biomarkers for the detection of Alzheimer's disease (AD). We previously showed that levels of the bisecting N-acetylglucosamine glycan epitope was elevated in cerebrospinal fluid in AD. However, its diagnostic value in blood is unknown.METHODS: We analyzed blood levels of bisecting N-acetylglucosamine and total tau in a retrospective cohort of 233 individuals. Progression to AD was compared between the groups using Cox regression. The predictive value of the biomarkers was determined by logistic regression.RESULTS: Bisecting N-acetylglucosamine correlated with tau levels (p < 0.0001). Individuals with an intermediate tau/bisecting N-acetylglucosamine ratio had elevated AD risk (hazard ratio = 2.06, 95% confidence interval [CI]: 1.18–3.6). Moreover, a combined model including tau/bisecting N-acetylglucosamine ratio, apolipoprotein E (APOE) ε4 status, and Mini-Mental State Examination score predicted future AD (area under the curve = 0.81, 95% CI: 0.68–0.93).DISCUSSION: Bisecting N-acetylglucosamine in combination with tau is a valuable blood biomarker for predicting AD.
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