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Publications in Clinical Medicine by NOMIS researchers

Regulatory T cell identity: Formation and maintenance

NOMIS Researcher(s)

Published in

June 1, 2015

T regulatory (Treg) cells are central to the maintenance of immune homeostasis. The transcription factor forkhead box P3 (Foxp3) is essential for specifying the Treg cell lineage during development, and continued expression of Foxp3 in mature Treg cells is necessary for suppressive function. Loss of Foxp3 expression in Treg cells is associated with autoimmune pathology. Here, we review recent insights into the mechanisms that maintain Treg cell stability and function, and place these findings within the broader understanding of mechanisms that establish Treg cell identity during development. We integrate emerging principles in Treg cell lineage maintenance with the mechanisms that allow Treg cells to sense and respond to varied inflammatory environments, and outline important areas of future inquiry in this context.

Research field(s)
Health Sciences, Clinical Medicine, Immunology

DOI
10.1016/j.it.2015.04.006

Characterizing new fluorescent tools for studying 5-HT3 receptor pharmacology

NOMIS Researcher(s)

Published in

January 1, 2015

The pharmacological characterization of ligands depends upon the ability to accurately measure their binding properties. Fluorescence provides an alternative to more traditional approaches such as radioligand binding. Here we describe the binding and spectroscopic properties of eight fluorescent 5-HT3 receptor ligands. These were tested on purified receptors, expressed receptors on live cells, or in vivo. All compounds had nanomolar affinities with fluorescent properties extending from blue to near infra-red emission. A fluorescein-derivative had the highest affinity as measured by fluorescence polarization (FP; 1.14 nM), flow cytometry (FC; 3.23 nM) and radioligand binding (RB; 1.90 nM). Competition binding with unlabeled 5-HT3 receptor agonists (5-HT, mCPBG, quipazine) and antagonists (granisetron, palonosetron, tropisetron) yielded similar affinities in all three assays. When cysteine substitutions were introduced into the 5-HT3 receptor binding site the same changes in binding affinity were seen for both granisetron and the fluorescein-derivative, suggesting that they both adopt orientations that are consistent with co-crystal structures of granisetron with a homologous protein (5HTBP). As expected, in vivo live imaging in anaesthetized mice revealed staining in the abdominal cavity in intestines, but also in salivary glands. The unexpected presence of 5-HT3 receptors in mouse salivary glands was confirmed by Western blots. Overall, these results demonstrate the wide utility of our new high-affinity fluorescently-labeled 5-HT3 receptor probes, ranging from in vitro receptor pharmacology, including FC and FP ligand competition, to live imaging of 5-HT3 expressing tissues.

Research field(s)
Health Sciences, Clinical Medicine, Neurology & Neurosurgery

DOI
10.1016/j.neuropharm.2014.11.007

An empirically derived composite cognitive test score with improved power to track and evaluate treatments for preclinical Alzheimer’s disease

NOMIS Researcher(s)

Published in

November 1, 2014

Background There is growing interest in the evaluation of preclinical Alzheimer’s disease (AD) treatments. As a result, there is a need to identify a cognitive composite that is sensitive to track preclinical AD decline to be used as a primary endpoint in treatment trials. Methods Longitudinal data from initially cognitively normal, 70- to 85-year-old participants in three cohort studies of aging and dementia from the Rush Alzheimer’s Disease Center were examined to empirically define a composite cognitive endpoint that is sensitive to detect and track cognitive decline before the onset of cognitive impairment. The mean-to-standard deviation ratios (MSDRs) of change over time were calculated in a search for the optimal combination of cognitive tests/subtests drawn from the neuropsychological battery in cognitively normal participants who subsequently progressed to clinical stages of AD during 2- and 5-year periods, using data from those who remained unimpaired during the same period to correct for aging and practice effects. Combinations that performed well were then evaluated for representation of relevant cognitive domains, robustness across individual years before diagnosis, and occurrence of selected items within top performing combinations. Results The optimal composite cognitive test score comprised seven cognitive tests/subtests with an MSDR = 0.964. By comparison, the most sensitive individual test score was Logical Memory Delayed Recall with an MSDR = 0.64. Conclusions We have identified a composite cognitive test score representing multiple cognitive domains that has improved power compared with the most sensitive single test item to track preclinical AD decline and evaluate preclinical AD treatments. We are confirming the power of the composite in independent cohorts and with other analytical approaches, which may result in refinements, have designated it as the primary endpoint in the Alzheimer’s Prevention Initiative’s preclinical treatment trials for individuals at high imminent risk for developing symptoms due to late-onset AD.

Research field(s)
Health Sciences, Clinical Medicine, Neurology & Neurosurgery

DOI
10.1016/j.jalz.2014.02.002

Developmental dyscalculia: a dysconnection syndrome?

NOMIS Researcher(s)

Published in

September 1, 2014

Numerical understanding is important for everyday life. For children with developmental dyscalculia (DD), numbers and magnitudes present profound problems which are thought to be based upon neuronal impairments of key regions for numerical understanding. The aim of the present study was to investigate possible differences in white matter fibre integrity between children with DD and controls using diffusion tensor imaging. White matter integrity and behavioural measures were evaluated in 15 children with developmental dyscalculia aged around 10 years and 15 matched controls. The main finding, obtained by a whole brain group comparison, revealed reduced fractional anisotropy in the superior longitudinal fasciculus in children with developmental dyscalculia. In addition, a region of interest analysis exhibited prominent deficits in fibres of the superior longitudinal fasciculus adjacent to the intraparietal sulcus, which is thought to be the core region for number processing. To conclude, our results outline deficient fibre projection between parietal, temporal and frontal regions in children with developmental dyscalculia, and therefore raise the question of whether dyscalculia can be seen as a dysconnection syndrome. Since the superior longitudinal fasciculus is involved in the integration and control of distributed brain processes, the present results highlight the importance of considering broader domain-general mechanisms in the diagnosis and therapy of dyscalculia.

Research field(s)
Health Sciences, Clinical Medicine, Neurology & Neurosurgery

DOI
10.1007/s00429-013-0597-4

Diversification of TAM receptor tyrosine kinase function

NOMIS Researcher(s)

Published in

January 1, 2014

The clearance of apoptotic cells is critical for both tissue homeostasis and the resolution of inflammation. We found that the TAM receptor tyrosine kinases Axl and Mer had distinct roles as phagocytic receptors in these two settings, in which they exhibited divergent expression, regulation and activity. Mer acted as a tolerogenic receptor in resting macrophages and during immunosuppression. In contrast, Axl was an inflammatory response receptor whose expression was induced by proinflammatory stimuli. Axl and Mer differed in their ligand specificities, ligand-receptor complex formation in tissues, and receptor shedding upon activation. These differences notwithstanding, phagocytosis by either protein was strictly dependent on receptor activation triggered by bridging of TAM receptor-ligand complexes to the ‘eat-me’ signal phosphatidylserine on the surface of apoptotic cells.

Research field(s)
Health Sciences, Clinical Medicine, Immunology

DOI
10.1038/ni.2986

Inflammasome-microbiota interplay in host physiologies

NOMIS Researcher(s)

Published in

November 13, 2013

Host defense responses against microbes are most often thought of in terms of effectors of microbial destruction. However, recent evidence demonstrates that the more complex interactions between the microbiota and innate immune mechanisms, such as the inflammasome-mediated response, cannot be readily explained within just the traditional paradigms of microbial killing mechanisms. In this review, the concepts of both resistance and tolerance are applied to inflammasome-microbiota interactions, and the various physiological consequences of this interplay, including roles in inflammation, tissue repair, tumorigenesis, and metabolism, are discussed. © 2013 Elsevier Inc.

Research field(s)
Health Sciences, Clinical Medicine, Immunology

DOI
10.1016/j.chom.2013.10.013

Advances in cellular reprogramming: Moving toward a reprieve from immunogenicity

NOMIS Researcher(s)

Published in

September 1, 2013

Somatic cell nuclear reprogramming is opening new doors for the modeling of human disease phenotypes in vitro, the identification of novel therapeutic compounds and diagnostic factors as well as future autologous cell replacement therapies. Despite the potential that reprogramming technologies bring, there are remaining concerns preventing their broad application in the short-term. One of them is the safety concern associated with the use of stem cell derivatives, those generated by reprogramming or even when embryonic stem cells are employed. Here we summarize the current knowledge in the field of stem cells and reprogramming with a particular focus on the pitfalls preventing rapid translation of stem cell technologies into the clinic. We discuss the most recent findings on immunogenicity and tumorigenicity of reprogrammed cells. We additionally provide an overview on the potential applications that reprogramming approaches might bring to the immunological field and elaborate on the use of induced pluripotent stem cells (iPSCs) with pre-arranged immune receptors for the development of future immunotherapeutic approaches. The use of reprogramming approaches can represent and provide groundbreaking strategies previously unachievable for stem cell engineering aimed at modulating immune responses. In summary, we provide an overview on the different topics related to the use of stem cells and highlight the most provocative, yet perhaps currently underappreciated, aspect of combining immunological and reprogramming strategies for the treatment of human disease. © 2013 Elsevier B.V.

Research field(s)
Health Sciences, Clinical Medicine, Immunology

DOI
10.1016/j.imlet.2013.09.019

Enveloped viruses disable innate immune responses in dendritic cells by direct activation of TAM receptors

NOMIS Researcher(s)

Published in

August 14, 2013

Upon activation by the ligands Gas6 and Protein S, Tyro3/Axl/Mer (TAM) receptor tyrosine kinases promote phagocytic clearance of apoptotic cells and downregulate immune responses initiated by Toll-like receptors and type I interferons (IFNs). Many enveloped viruses display the phospholipid phosphatidylserine on their membranes, through which they bind Gas6 and Protein S and engage TAM receptors. We find that ligand-coated viruses activate TAM receptors on dendritic cells (DCs), dampen type I IFN signaling, and thereby evade host immunity and promote infection. Upon virus challenge, TAM-deficient DCs display type I IFN responses that are elevated in comparison to wild-type cells. As a consequence, TAM-deficient DCs are relatively resistant to infection by flaviviruses and pseudotyped retroviruses, but infection can be restored with neutralizing type I IFN antibodies. Correspondingly, a TAM kinase inhibitor antagonizes the infection of wild-type DCs. Thus, TAM receptors are engaged by viruses in order to attenuate type I IFN signaling and represent potential therapeutic targets. © 2013 Elsevier Inc.

Research field(s)
Health Sciences, Clinical Medicine, Immunology

DOI
10.1016/j.chom.2013.07.005

Ushering in the study and treatment of preclinical Alzheimer disease

NOMIS Researcher(s)

Published in

July 1, 2013

Researchers have begun to characterize the subtle biological and cognitive processes that precede the clinical onset of Alzheimer disease (AD), and to set the stage for accelerated evaluation of experimental treatments to delay the onset, reduce the risk of, or completely prevent clinical decline. In this Review, we provide an overview of the experimental strategies, and brain imaging and cerebrospinal fluid biomarker measures that are used in early detection and tracking of AD, highlighting at-risk individuals who could be suitable for preclinical monitoring. We discuss how advances in the field have contributed to reconceptualization of AD as a sequence of biological changes that occur during progression from preclinical AD, to mild cognitive impairment and finally dementia, and we review recently proposed research criteria for preclinical AD. Advances in the study of preclinical AD have driven the recognition that efficacy of at least some AD therapies may depend on initiation of treatment before clinical manifestation of disease, leading to a new era of AD prevention research. © 2013 Macmillan Publishers Limited. All rights reserved.

Research field(s)
Health Sciences, Clinical Medicine, Neurology & Neurosurgery

DOI
10.1038/nrneurol.2013.107

Florbetapir PET analysis of amyloid-β deposition in the presenilin 1 E280A autosomal dominant Alzheimer’s disease kindred: A cross-sectional study

NOMIS Researcher(s)

Published in

December 1, 2012

Background: Fibrillar amyloid-β (Aβ) is thought to begin accumulating in the brain many years before the onset of clinical impairment in patients with Alzheimer’s disease. By assessing the accumulation of Aβ in people at risk of genetic forms of Alzheimer’s disease, we can identify how early preclinical changes start in individuals certain to develop dementia later in life. We sought to characterise the age-related accumulation of Aβ deposition in presenilin 1 (PSEN1) E280A mutation carriers across the spectrum of preclinical disease. Methods: Between Aug 1 and Dec 6, 2011, members of the familial Alzheimer’s disease Colombian kindred aged 18-60 years were recruited from the Alzheimer’s Prevention Initiative’s registry at the University of Antioquia, Medellín, Colombia. Cross-sectional assessment using florbetapir PET was done in symptomatic mutation carriers with mild cognitive impairment or mild dementia, asymptomatic carriers, and asymptomatic non-carriers. These assessments were done at the Banner Alzheimer’s Institute in Phoenix, AZ, USA. A cortical grey matter mask consisting of six predefined regions was used to measure mean cortical florbetapir PET binding. Cortical-to-pontine standard-uptake value ratios were used to characterise the cross-sectional accumulation of fibrillar Aβ deposition in carriers and non-carriers with regression analysis and to estimate the trajectories of fibrillar Aβ deposition. Findings: We enrolled a cohort of 11 symptomatic individuals, 19 presymptomatic mutation carriers, and 20 asymptomatic non-carriers, ranging in age from 20 to 56 years. There was greater florbetapir binding in asymptomatic PSEN1 E280A mutation carriers than in age matched non-carriers. Fibrillar Aβ began to accumulate in PSEN 1E280A mutation carriers at a mean age of 28·2 years (95% CI 27·3-33·4), about 16 years and 21 years before the predicted median ages at mild cognitive impairment and dementia onset, respectively. 18F florbetapir binding rose steeply over the next 9·4 years and plateaued at a mean age of 37·6 years (95% CI 35·3-40·2), about 6 and 11 years before the expected respective median ages at mild cognitive impairment and dementia onset. Prominent florbetapir binding was seen in the anterior and posterior cingulate, precuneus, and parietotemporal and frontal grey matter, as well as in the basal ganglia. Binding in the basal ganglia was not seen earlier or more prominently than in other regions. Interpretation: These findings contribute to the understanding of preclinical familial Alzheimer’s disease and help set the stage for assessment of amyloid-modifying treatments in the prevention of familial Alzheimer’s disease. Funding: Avid Radiopharmaceuticals, Banner Alzheimer’s Foundation, Nomis Foundation, Anonymous Foundation, Forget Me Not Initiative, Colciencias, National Institute on Aging, and the State of Arizona. © 2012 Elsevier Ltd.

Research field(s)
Health Sciences, Clinical Medicine, Neurology & Neurosurgery

DOI
10.1016/S1474-4422(12)70227-2

Brain imaging and fluid biomarker analysis in young adults at genetic risk for autosomal dominant Alzheimer’s disease in the presenilin 1 E280A kindred: A case-control study

NOMIS Researcher(s)

Published in

December 1, 2012

Background: We have previously characterised functional brain abnormalities in young adults at genetic risk for late-onset Alzheimer’s disease. To gain further knowledge on the preclinical phase of Alzheimer’s disease, we sought to characterise structural and functional MRI, CSF, and plasma biomarkers in a cohort of young adults carrying a high-penetrance autosomal dominant mutation that causes early-onset Alzheimer’s disease. Methods: Between January and August, 2010, 18-26-year-old presenilin 1 (PSEN1) E280A mutation carriers and non-carriers from the Colombian Alzheimer’s Prevention Initiative Registry in Medellín Antioquia, Colombia, had structural MRI, functional MRI during associative memory encoding and novel viewing and control tasks, and cognitive assessments. Consenting participants also had lumbar punctures and venepunctures. Outcome measures were task-dependent hippocampal or parahippocampal activations and precuneus or posterior cingulate deactivations, regional grey matter reductions, CSF Aβ1-42, total tau and phospho-tau181 concentrations, and plasma Aβ1-42 concentrations and Aβ1-42:Aβ1-40 ratios. Structural and functional MRI data were compared using automated brain mapping algorithms and search regions related to Alzheimer’s disease. Cognitive and fluid biomarkers were compared using Mann-Whitney tests. Findings: 44 participants were included: 20 PSEN1 E280A mutation carriers and 24 non-carriers. The carrier and non-carrier groups did not differ significantly in their dementia ratings, neuropsychological test scores, or proportion of apolipoprotein E (APOE) e{open}4 carriers. Compared with non-carriers, carriers had greater right hippocampal and parahippocampal activation (p=0·001 and p<0·014, respectively, after correction for multiple comparisons), less precuneus and posterior cingulate deactivation (all p<0·010 after correction), and less grey matter in several parietal regions (all p<0·002 uncorrected and corrected p=0·009 in the right parietal search region). In the 20 participants (ten PSEN1 E280A mutation carriers and ten non-carriers) who had lumbar punctures and venepunctures, mutation carriers had higher CSF Aβ1-42 concentrations (p=0·008) and plasma Aβ1-42 concentrations (p=0·01) than non-carriers. Interpretation: Young adults at genetic risk for autosomal dominant Alzheimer's disease have functional and structural MRI findings and CSF and plasma biomarker findings consistent with Aβ1-42 overproduction. Although the extent to which the underlying brain changes are either neurodegenerative or developmental remain to be determined, this study shows the earliest known biomarker changes in cognitively normal people at genetic risk for autosomal dominant Alzheimer's disease. Funding: Banner Alzheimer's Foundation, Nomis Foundation, Anonymous Foundation, Forget Me Not Initiative, Boston University Department of Psychology, Colciencias, National Institute on Aging, National Institute of Neurological Disorders and Stroke, and the State of Arizona. © 2012 Elsevier Ltd.

Research field(s)
Health Sciences, Clinical Medicine, Neurology & Neurosurgery

DOI
10.1016/S1474-4422(12)70228-4

Mental number line training in children with developmental dyscalculia

NOMIS Researcher(s)

Published in

August 1, 2011

Developmental dyscalculia (DD) is a specific learning disability that affects the acquisition of mathematical skills in children with normal intelligence and age-appropriate school education (prevalence 3-6%). One essential step in the development of mathematical understanding is the formation and automated access to a spatial representation of numbers. Many children with DD show a deficient development of such a mental number line. The present study aimed to develop a computer-based training program to improve the construction and access to the mental number line.Sixteen children with DD aged 8-10. years and 16 matched control children completed the 5-week computer training. All children played the game 15. min a day for 5. days a week. The efficiency of the training was evaluated by means of neuropsychological tests and functional magnetic resonance imaging (fMRI) during a number line task.In general, children with and without DD showed a benefit from the training indicated by (a) improved spatial representation of numbers and (b) the number of correctly solved arithmetical problems.Regarding group differences in brain activation, children with DD showed less activation in bilateral parietal regions, which reflects neuronal dysfunction in pivotal regions for number processing. Both groups showed reduced recruitment of relevant brain regions for number processing after the training which can be attributed to automatization of cognitive processes necessary for mathematical reasoning. Moreover, results point to a partial remediation of deficient brain activation in dyscalculics after consolidation of acquired and refined number representation.To conclude, the present study represents the first attempt to evaluate a custom-designed training program in a group of dyscalculic children and results indicate that the training leads to an improved spatial representation of the mental number line and a modulation of neural activation, which both facilitate processing of numerical tasks. © 2011 Elsevier Inc.

Research field(s)
Health Sciences, Clinical Medicine, Neurology & Neurosurgery

DOI
10.1016/j.neuroimage.2011.01.070

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