Neuroinflammation and its resolution in Alzheimer's disease

Alzheimer's disease (AD) is the most common dementia with high prevalence among an increasing aged population. Despite the existence of symptom-reliving drugs for AD, the clinical trials performed until now have failed to find drugs that cure or stop the progression of AD. New perspectives and strategies for treatments are therefore direly needed. Chronic inflammation as indicated by persistent activation of microglia and increased proinflammatory mediators is one of the major characteristics for AD, together with pathological accumulation of β-amyloid (Aβ), hyperphosphorylated tau proteins and neuronal loss. In normal physiological conditions, inflammation is ended by resolution, an active process associated with restoration and regeneration mediated by specialised pro-resolving lipid mediators (SPMs). Previous studies have shown that there are alterations in the resolution of inflammation in AD that can cause neurodegeneration by impairment in neuroprotective signalling, control of inflammation, and in the removal of the pathogenic Aβ peptide. The current studies focus on the impairment of pro-resolving mechanisms in the context of AD. The prospect of reducing harmful inflammation while at the same time increasing protective and pro-homeostatic activities present a promising strategy for treating AD. In Paper I and II, we focused on answering the fundamental question, whether and how the neuroinflammation (Paper I) and its resolution (Paper II) are altered in AD patients. We aimed to identify dissimilar inflammation-related protein mediators (Paper I) and SPMs (Paper II) profiles in the cerebrospinal fluid (CSF) of patients diagnosed with subjective cognitive impairment (SCI), mild cognitive impairment (MCI) or AD. We found an inflammatory pattern in the CSF that could differentiate SCI and AD. Comorbidities have an influence on the inflammatory pattern. SPMs were decreased in the CSF of AD patients and were associated with AD pathologies and cognition, suggesting that SPMs have potential to be novel biomarkers for AD. In Paper III and IV, the aim of the studies was to explore the pro-resolving role of maresin 1 (MaR1) in the context of Aβ42-induced inflammation in human microglial cell models. In Paper III, AD-like neuroinflammation was induced exposure to Ab42 monomers in both human monocyte-derived microglia (MdM) and a differentiated human monocyte cell line (THP-1 cells). We showed that one of the SPMs MaR1 reduced Aβ42-induced elevation in pro-inflammatory activation and stimulated the Aβ42 uptake. In Paper IV, RNA-Sequencing (RNA-Seq) was used to study the effects of MaR1 on the transcriptome of Aβ42-treated MdM to obtain a broader view regarding the pro-resolving roles of MaR1. We found that Aβ42 up-regulated inflammatory pathways and that co-incubation with MaR1 down-regulated some of these pathways. Proteomics confirmed the finding. In conclusion, the inflammation-related protein mediator profile and SPMs in CSF have a potential to contribute to the diagnosis of AD and are correlated to AD pathologies and cognition. SPM MaR1 attenuates AD-like neuroinflammation and supports the hypothesis that stimulating the resolution of inflammation could be a new therapeutic strategy in A

2018 IMSAloquium, Student Investigation Showcase

This is IMSA\u27s 31st year of leading in educational innovation and the 30th year of the Student Inquiry and Research Program (SIR)! ... These studies have all happened during the past year in a variety of laboratories, real or virtual, on and off campus. Students were asked to not only learn a great deal about complex topics, but to contribute to them in meaningful ways. The presentations you hear today reflect the various stages of their work on a myriad of projects.https://digitalcommons.imsa.edu/archives_sir/1028/thumbnail.jp

Investigation of Sirtuins as Therapeutic Targets in Neurodegenerative Disorders: Studies on Mechanisms and Possible Combined Therapy

Up to now, current therapies for Alzheimer’s disease (AD) can treat the symptoms with modest effect and have little impact on the overall progression. AD is a complex, multifactorial disorder, featured by aggregation of toxic proteins, inflammation, oxidative stress, synaptic deficits, and cognitive decline. Thus, the multi-target therapeutic strategy is of particular interest as it uses a combination of drugs to affect different molecular targets and converge on neuroprotection or even disease modification. In drug discovery for neurodegenerative processes, an interesting role emerged for the histone-deacetylase enzymes Sirtuins (SIRTs), and SIRT1 and SIRT2 have been associated with neuroprotection and neurodegeneration, respectively. The availability of SIRTs small molecule modulators allowed the achievement of good results of SIRT1 activation or SIRT2 inhibition in models of neurodegeneration and AD, as both SIRTs are actively involved, to different extent, in the regulation of amyloidogenic processing, inflammatory and oxidative cascades. A direct intervention on such molecular players could be beneficial in obtaining cognitive or pathologic phenotype improvement deriving from multiple pathways targeting. In this work, we aimed at combining SIRT1 activation and SIRT2 inhibition to study a possible multi-target approach on AD models, both in vitro and in vivo. An initial drug dose-response and biochemical assessment was performed on the AD in vitro model H4-sw, focusing on the increase of the neuroprotective sAPPα fragment. Next, 3xTg-AD mice received the single or the combined treatment with SIRT1 activator SRT2104 and SIRT2 inhibitor AK7 for two weeks, and the effects on cognitive performance and key biochemical parameters were assessed. Results showed that both SIRT1 and SIRT2 single modulation independently improved cognitive performance in treated mice. Combined treatment showed complete memory recovery too. Some differences between single and double treatment emerged in biochemical assessments. Double-treated mice had increased NRF2, sAPPα and reduced Aβ oligomers in hippocampus, already seen upon SIRT2 inhibition, suggesting that cognitive improvement given by SIRT2 modulation could be attributed to those underlying effects. Together with memory recovery, SIRT1 activator treated mice showed decreased hippocampal CD11b and GFAP, increased synaptophysin, SOD1, sAPPα and NRF2, all seen upon double treatment too. Thus, SIRT1 and SIRT2 independent modulations could improve memory deficit acting both on peculiar or common protein targets. In conclusion, the combined treatment resumed all the behavioural and biochemical effects of single modulations. Our data support the concept that, with a multi-target strategy, it could be possible to take full advantage of the complementarity of SIRT1/SIRT2 treatments and obtain cognitive improvement based on changes on several underlying biochemical mechanisms that with single modulation could only be partially achieved. All these observations could open up new insights for research on SIRTs involvement in AD and neurodegeneration

Developing the Common Marmoset (\u3cem\u3eCallithrix jacchus\u3c/em\u3e) as a Model of Neurologic and Endocrine Aging

The Common marmoset (Callithrix jacchus) is a prominent translational neuroscience and geroscience model that presents promise as a model of human aging and neurodegenerative disease. Marmosets spontaneously exhibit age-associated phenotypes mirroring those of humans such as cognitive decline and amyloid deposition, and have the shortest lifespan among anthropoid primates, positioning the species for longitudinal study. The trajectory of cortisol across the marmoset lifespan was examined via measure of hair cortisol concentration (HCC) in a cohort of 50 captive animals subdivided into five age groups that span the entire marmoset lifespan. We found that infants exhibited higher HCC than all other age groups, females exhibited higher HCC than males, and an overall moderate negative correlation of cortisol with age across the marmoset lifespan. This suggests that marmosets do not display senescence and progressive dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis as they age. An ongoing 10-month pilot study aims to characterize aging profiles in a cohort of seven aged marmosets in terms of neuroinflammation, cognition, and neurodegenerative biomarkers. This will be done via parallel analysis of dynamic PET images using radiotracer [18F]-DPA-714 to quantify microglial activity, two cognitive tasks, and assessment of neurodegenerative blood biomarkers, including glial fibrillary acidic protein (GFAP), and pro-/anti-inflammatory cytokines. These projects aim to further our understanding of the aging process in the common marmoset, with the hope that these findings may be applied to future efforts using marmosets as an model of human aging, serving to identify risk factors for decline associated with aging, and elucidate the underlying mechanisms inherent in normal or pathological decline with age

Discovering lesser known molecular players and mechanistic patterns in Alzheimer's disease using an integrative disease modelling approach

Convergence of exponentially advancing technologies is driving medical research with life changing discoveries. On the contrary, repeated failures of high-profile drugs to battle Alzheimer's disease (AD) has made it one of the least successful therapeutic area. This failure pattern has provoked researchers to grapple with their beliefs about Alzheimer's aetiology. Thus, growing realisation that Amyloid-β and tau are not 'the' but rather 'one of the' factors necessitates the reassessment of pre-existing data to add new perspectives. To enable a holistic view of the disease, integrative modelling approaches are emerging as a powerful technique. Combining data at different scales and modes could considerably increase the predictive power of the integrative model by filling biological knowledge gaps. However, the reliability of the derived hypotheses largely depends on the completeness, quality, consistency, and context-specificity of the data. Thus, there is a need for agile methods and approaches that efficiently interrogate and utilise existing public data. This thesis presents the development of novel approaches and methods that address intrinsic issues of data integration and analysis in AD research. It aims to prioritise lesser-known AD candidates using highly curated and precise knowledge derived from integrated data. Here much of the emphasis is put on quality, reliability, and context-specificity. This thesis work showcases the benefit of integrating well-curated and disease-specific heterogeneous data in a semantic web-based framework for mining actionable knowledge. Furthermore, it introduces to the challenges encountered while harvesting information from literature and transcriptomic resources. State-of-the-art text-mining methodology is developed to extract miRNAs and its regulatory role in diseases and genes from the biomedical literature. To enable meta-analysis of biologically related transcriptomic data, a highly-curated metadata database has been developed, which explicates annotations specific to human and animal models. Finally, to corroborate common mechanistic patterns — embedded with novel candidates — across large-scale AD transcriptomic data, a new approach to generate gene regulatory networks has been developed. The work presented here has demonstrated its capability in identifying testable mechanistic hypotheses containing previously unknown or emerging knowledge from public data in two major publicly funded projects for Alzheimer's, Parkinson's and Epilepsy diseases

Identification And Characterization Of Mediators Of Toxicity Of Aβ Oligomers By Genome Wide Screening In <i>Caenorhabditis Elegans</i>

Soluble oligomers of the amyloid-β (Aβ) protein play a key role in the pathogenesis of Alzheimer’s disease (AD), although the underlying molecular mechanisms are poorly understood. In order to search for proteins involved in the formation and/or toxicity of Aβ oligomers, a transgenic C. elegans model of AD was used in which inducible expression of Aβ oligomers results in a complete paralysis; in these worms a genetic screen following chemical mutagenesis was applied to discover the genes involved in the Aβ-dependent paralysis (forward genetics). This analysis allowed identification of a mutated clone showing a complete lack of paralysis, despite this it not bear mutations in the Aβ coding region, and accumulates Aβ transcript and protein levels comparable to that of the non-mutated strain. This is the first in vivo model in which the expression of Aβ oligomers do not result in any toxic effect. The genome of the mutated worm was then sequenced and compared with that of the control strain to search for altered genes. Two genes, with no known function, were found to bear a stop codon mutation, likely resulting in the translation of an inactive protein. The rest of the mutations were missense mutations. Among them, point mutations were observed in some genes previously correlated with nematode lifespan and ageing. In C. elegans these biological processes are coordinated by the insulin/IGF-1-like signalling (IIS) pathway, which also regulates the response of the organism to toxic aggregated proteins. Thus, the activation of the IIS pathway was investigated in control and mutated worms. As expected, Aβ expression induced the up-regulation of two genes coding for small heat shock proteins (a class of chaperons known to be involved in AD) in the control strain, whereas these genes were actually down-regulated in the mutated strain. Since heat shock proteins are known to bind Aβ oligomers, these chaperons could directly mediate the formation of toxic amyloid species. Moreover, the results of the whole genome sequencing indicate that several proteins could act as potential novel mediators of Aβ toxicity and could open up new insights for research on age-related, neurodegenerative diseases

Novel molecular alterations in amyotrophic lateral sclerosis and frontotemporal lobar degeneration spectrum

[eng] Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are clinically distinct neurodegenerative diseases that are connected by genetic and pathological overlap. ALS patients present with muscle weakness and spasticity associated with degeneration of motor neurons in the motor cortex, brainstem, and spinal cord that ultimately leads to death. In contrast, patients with FTLD display cognitive dysfunction associated with degeneration of neurons in the frontal and temporal lobes of the brain. Despite being clinically distinct, 15% of individuals presenting FTLD also have ALS, whereas 30% of individuals with ALS will develop FTLD. This implies that these two neurodegenerative diseases are part of a shared clinical spectrum. In recent years, several mechanisms have been proposed as contributory factors in the pathogenesis of neuron damage in ALS and FTLD, including excitoxicity, mitochondrial and energy metabolism failure, oxidative stress damage, altered glial cells, inflammation, cytoskeletal abnormalities, alterations in RNA metabolism, and altered TDP-43 metabolism, among others. However, it is poor known about the etiology of these disorders and their possible treatment. The objective of the investigations presented in this doctoral thesis is focused in the identification of new molecular alterations underlying motor and cognitive changes in post-mortem human spinal cord and brain samples of ALS patients and brain samples of FTLD-TDP patients compared with controls, combining microarray, mRNA, protein and enzyme assays studies. The obtained results have identified new molecular alterations in ALS and FTLD of different biological functions and cellular pathways including changes in mitochondrial energy metabolism, neuroinflammation, neuronal structure, neurotransmission, axonal transport mechanisms and oligodendrocyte function; allowing in turn, the screening and identification of new candidate molecules as biomarkers for these disorders.[spa] La esclerosis lateral amiotrófica (ELA) y la degeneración del lóbulo frontotemporal (DLFT) son enfermedades neurodegenerativas clínicamente distintas que están conectadas por una superposición genética y patológica. Los pacientes con ELA presentan debilidad muscular y espasticidad asociada con la degeneración de las neuronas motoras en la corteza motora, el tronco cerebral y la médula espinal que finalmente conduce a la muerte. En contraste, los pacientes con DLFT muestran disfunción cognitiva asociada con la degeneración de las neuronas en los lóbulos frontal y temporal del cerebro. A pesar de ser clínicamente distintos, el 15% de las personas que presentan DLFT también tienen ELA, mientras que el 30% de las personas con ELA desarrollarán DLFT. Esto implica que estas dos enfermedades neurodegenerativas son parte de un espectro clínico compartido. En los últimos años, se han propuesto varios mecanismos como factores contribuyentes en la patogénesis del daño neuronal en la ELA y el DLFT, que incluyen la excitoxicidad, el fallo del metabolismo mitocondrial y energético, el daño por estrés oxidativo, las células gliales alteradas, la inflamación, las anomalías del citoesqueleto y las alteraciones en el metabolismo del ARN y alteración del metabolismo del TDP-43, entre otros. Sin embargo, es poco conocido sobre la etiología de estos trastornos y su posible tratamiento. El objetivo de las investigaciones presentadas en esta tesis doctoral se centra en la identificación de nuevas alteraciones moleculares subyacentes a los cambios motores y cognitivos en tejido post-mortem de médula espinal humana y en muestras de cerebro de pacientes con ELA y en las muestras de cerebro de pacientes con FTLD-TDP en comparación con muestras controles, combinando estudios de microarray, expresión de mRNA, proteínas y ensayos enzimáticos. Los resultados obtenidos han identificado nuevas alteraciones moleculares dentro del espectro ELA- DLFT en diferentes funciones biológicas y vías celulares que incluyen cambios en el metabolismo de energético y mitocondrial, la neuroinflamación, la estructura neuronal, la neurotransmisión, los mecanismos de transporte axonal y la función de oligodendrocitos; permitiendo a su vez, la selección e identificación de nuevas moléculas candidatas a biomarcadores para estos trastornos

Chronic Dysregulation of the Cerebrovasculature in a Mouse Model of Repetitive Mild Traumatic Brain Injury

There are over 2 million reports of Traumatic Brain Injury (TBI) every year in the United States alone, the majority of which are classified as a mild head injury. Incidences of mild TBI (mTBI), the kind of which are sustained most routinely by contact sports athletes, active military personnel, are now well accepted as being a risk factor for development of chronic neurodegenerative disorders such as Chronic Traumatic Encephalopathy (CTE). To date, the diagnosis of CTE has been based on post-mortem neuropathological assessment of brain tissue, precluding the possibility of prophylactic or interventional therapy in human patients presenting with symptomatology too ambiguous for antemortem diagnosis, and ergo, appropriate clinical trial stratification. Recently, it has been reported that military personnel and players of contact sports experiencing repetitive m-TBI (r-mTBI), as well as individuals suffering from chronic TBI-related illness, demonstrate a deficit in Cerebral Vascular Reactivity (CVR). This physiological impairment is non-invasively detected following repeat mTBI, and seen to be sustained at chronic time-points post-injury in both r-mTBI and moderate to severe TBI patients alike, implicating CVR detriment as an endophenotypic biomarker and possible in vivo diagnostic of TBI-related neuropathogenesis, and Traumatic Cerebral Vascular Injury (TCVI). In this thesis, I developed and validated a preclinical in vivo imaging setup to examine CVR in our CTE-like neuropathology exhibiting mouse model of r-mTBI, with an aim to characterizing the evolving pathobiology of TCVI and concurrent euro behavioral impairment, and their correlation to perturbed CVR. I demonstrated recapitulation of the CVR deficit seen in the human population in our animal model, alongside sustained memory and learning impairment, and signs of an underlying response of the cerebral vasculature to injury. These finding implicate measurement of CVR as a valid preclinical diagnostic, and the treatment of TCVI as a compelling parallel pathological target in r-mTBI