Clonally expanded CD8 T cells patrol the cerebrospinal fluid in Alzheimer's disease.

Alzheimer's disease is an incurable neurodegenerative disorder in which neuroinflammation has a critical function1. However, little is known about the contribution of the adaptive immune response in Alzheimer's disease2. Here, using integrated analyses of multiple cohorts, we identify peripheral and central adaptive immune changes in Alzheimer's disease. First, we performed mass cytometry of peripheral blood mononuclear cells and discovered an immune signature of Alzheimer's disease that consists of increased numbers of CD8+ T effector memory CD45RA+ (TEMRA) cells. In a second cohort, we found that CD8+ TEMRA cells were negatively associated with cognition. Furthermore, single-cell RNA sequencing revealed that T cell receptor (TCR) signalling was enhanced in these cells. Notably, by using several strategies of single-cell TCR sequencing in a third cohort, we discovered clonally expanded CD8+ TEMRA cells in the cerebrospinal fluid of patients with Alzheimer's disease. Finally, we used machine learning, cloning and peptide screens to demonstrate the specificity of clonally expanded TCRs in the cerebrospinal fluid of patients with Alzheimer's disease to two separate Epstein-Barr virus antigens. These results reveal an adaptive immune response in the blood and cerebrospinal fluid in Alzheimer's disease and provide evidence of clonal, antigen-experienced T cells patrolling the intrathecal space of brains affected by age-related neurodegeneration.

Transcriptomic Profiling Identifies CD8+ T Cells in the Brain of Aged and Alzheimer's Disease Transgenic Mice as Tissue-Resident Memory T Cells.

Peripheral immune cell infiltration into the brain is a prominent feature in aging and various neurodegenerative diseases such as Alzheimer's disease (AD). As AD progresses, CD8+ T cells infiltrate into the brain parenchyma, where they tightly associate with neurons and microglia. The functional properties of CD8+ T cells in the brain are largely unknown. To gain further insights into the putative functions of CD8+ T cells in the brain, we explored and compared the transcriptomic profile of CD8+ T cells isolated from the brain and blood of transgenic AD (APPswe/PSEN1dE9, line 85 [APP-PS1]) and age-matched wild-type (WT) mice. Brain CD8+ T cells of APP-PS1 and WT animals had similar transcriptomic profiles and substantially differed from blood circulating CD8+ T cells. The gene signature of brain CD8+ T cells identified them as tissue-resident memory (Trm) T cells. Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analysis on the significantly upregulated genes revealed overrepresentation of biological processes involved in IFN-ß signaling and the response to viral infections. Furthermore, brain CD8+ T cells of APP-PS1 and aged WT mice showed similar differentially regulated genes as brain Trm CD8+ T cells in mouse models with acute virus infection, chronic parasite infection, and tumor growth. In conclusion, our profiling of brain CD8+ T cells suggests that in AD, these cells exhibit similar adaptive immune responses as in other inflammatory diseases of the CNS, potentially opening the door for immunotherapy in AD.

Association of dietary and nutritional factors with cognitive decline, dementia, and depressive symptomatology in older individuals according to a neurogenesis-centred biological susceptibility to brain ageing.

Hippocampal neurogenesis (HN) occurs throughout the life course and is important for memory and mood. Declining with age, HN plays a pivotal role in cognitive decline (CD), dementia, and late-life depression, such that altered HN could represent a neurobiological susceptibility to these conditions. Pertinently, dietary patterns (e.g., Mediterranean diet) and/or individual nutrients (e.g., vitamin D, omega 3) can modify HN, but also modify risk for CD, dementia, and depression. Therefore, the interaction between diet/nutrition and HN may alter risk trajectories for these ageing-related brain conditions. Using a subsample (n = 371) of the Three-City cohort-where older adults provided information on diet and blood biobanking at baseline and were assessed for CD, dementia, and depressive symptomatology across 12 years-we tested for interactions between food consumption, nutrient intake, and nutritional biomarker concentrations and neurogenesis-centred susceptibility status (defined by baseline readouts of hippocampal progenitor cell integrity, cell death, and differentiation) on CD, Alzheimer's disease (AD), vascular and other dementias (VoD), and depressive symptomatology, using multivariable-adjusted logistic regression models. Increased plasma lycopene concentrations (OR [95% CI] = 1.07 [1.01, 1.14]), higher red meat (OR [95% CI] = 1.10 [1.03, 1.19]), and lower poultry consumption (OR [95% CI] = 0.93 [0.87, 0.99]) were associated with an increased risk for AD in individuals with a neurogenesis-centred susceptibility. Increased vitamin D consumption (OR [95% CI] = 1.05 [1.01, 1.11]) and plasma γ-tocopherol concentrations (OR [95% CI] = 1.08 [1.01, 1.18]) were associated with increased risk for VoD and depressive symptomatology, respectively, but only in susceptible individuals. This research highlights an important role for diet/nutrition in modifying dementia and depression risk in individuals with a neurogenesis-centred susceptibility.

Impaired hippocampal neurogenesis in vitro is modulated by dietary-related endogenous factors and associated with depression in a longitudinal ageing cohort study.

Environmental factors like diet have been linked to depression and/or relapse risk in later life. This could be partially driven by the food metabolome, which communicates with the brain via the circulatory system and interacts with hippocampal neurogenesis (HN), a form of brain plasticity implicated in depression aetiology. Despite the associations between HN, diet and depression, human data further substantiating this hypothesis are largely missing. Here, we used an in vitro model of HN to test the effects of serum samples from a longitudinal ageing cohort of 373 participants, with or without depressive symptomology. 1% participant serum was applied to human fetal hippocampal progenitor cells, and changes in HN markers were related to the occurrence of depressive symptoms across a 12-year period. Key nutritional, metabolomic and lipidomic biomarkers (extracted from participant plasma and serum) were subsequently tested for their ability to modulate HN. In our assay, we found that reduced cell death and increased neuronal differentiation were associated with later life depressive symptomatology. Additionally, we found impairments in neuronal cell morphology in cells treated with serum from participants experiencing recurrent depressive symptoms across the 12-year period. Interestingly, we found that increased neuronal differentiation was modulated by increased serum levels of metabolite butyrylcarnitine and decreased glycerophospholipid, PC35:1(16:0/19:1), levels - both of which are closely linked to diet - all in the context of depressive symptomology. These findings potentially suggest that diet and altered HN could subsequently shape the trajectory of late-life depressive symptomology.

The serum metabolome mediates the concert of diet, exercise, and neurogenesis, determining the risk for cognitive decline and dementia.

INTRODUCTION: Diet and exercise influence the risk of cognitive decline (CD) and dementia through the food metabolome and exercise-triggered endogenous factors, which use the blood as a vehicle to communicate with the brain. These factors might act in concert with hippocampal neurogenesis (HN) to shape CD and dementia. METHODS: Using an in vitro neurogenesis assay, we examined the effects of serum samples from a longitudinal cohort (n = 418) on proxy HN readouts and their association with future CD and dementia across a 12-year period. RESULTS: Altered apoptosis and reduced hippocampal progenitor cell integrity were associated with exercise and diet and predicted subsequent CD and dementia. The effects of exercise and diet on CD specifically were mediated by apoptosis. DISCUSSION: Diet and exercise might influence neurogenesis long before the onset of CD and dementia. Alterations in HN could signify the start of the pathological process and potentially represent biomarkers for CD and dementia.

Inhibition of the cysteinyl leukotriene pathways increases survival of RGCs and reduces microglial activation in ocular hypertension.

Glaucoma is the second leading cause of blindness worldwide. This multifactorial, neurodegenerative group of diseases is characterized by the progressive loss of retinal ganglion cells (RGCs) and their axons, leading to irreversible visual impairment and blindness. There is a huge unmet and urging need for the development of new and translatable strategies and treatment options to prevent this progressive loss of RGC. Accumulating evidence points towards a critical role of neuroinflammation, in particular microglial cells, in the pathogenesis of glaucoma. Leukotrienes are mediators of neuroinflammation and are involved in many neurodegenerative diseases. Therefore, we tested the leukotriene receptors CysLT1R/GPR17-selective antagonist Montelukast (MTK) for its efficacy to modulate the reactive state of microglia in order to ameliorate RGCs loss in experimental glaucoma. Ocular hypertension (OHT) was induced unilaterally by injection of 8 µm magnetic microbead (MB) into the anterior chamber of female Brown Norway rats. The contralateral, untreated eye served as control. Successful induction of OHT was verified by daily IOP measurement using a TonoLab rebound tonometer. Simultaneously to OHT induction, one group received daily MTK treatment and the control group vehicle solution by oral gavage. Animals were sacrificed 13-15 days after MB injection. Retina and optic nerves (ON) of OHT and contralateral eyes were analyzed by immunofluorescence with specific markers for RGCs (Brn3a), microglial cells/macrophages (Iba1 and CD68), and cysteinyl leukotriene pathway receptors (CysLT1R and GPR17). Protein labeling was documented by confocal microscopy and analyzed with ImageJ plugins. Further, mRNA expression of genes of the inflammatory and leukotriene pathway was analyzed in retinal tissue. MTK treatment resulted in a short-term IOP reduction at day 2, which dissipated by day 5 of OHT induction in MTK treated animals. Furthermore, MTK treatment resulted in a decreased activation of Iba1+ microglial cells in the retina and ON, and in a significantly increased RGC survival in OHT eyes. Within the retina, GPR17 and CysLT1R expression was demonstrated in single RCGs and in microglial cells respectively. Further, increased mRNA expression of pro-inflammatory genes was detected in OHT induced retinas. In the ON, OHT induction increased the number of GPR17+ cells, showing a trend of reduction following MTK treatment. This study shows for the first time a significantly increased RGC survival in an acute OHT model following treatment with the leukotriene receptor antagonist MTK. These results strongly suggest a neuroprotective effect of MTK and a potential new therapeutic strategy for glaucoma treatment.

Antibody seroprevalence and rate of asymptomatic infections with SARS-CoV-2 in Austrian hospital personnel.

BACKGROUND: The aims of this study are to determine (i) SARS-CoV-2 antibody positive employees in Austrian trauma hospitals and rehabilitation facilities, (ii) number of active virus carriers (symptomatic and asymptomatic) during the study, (iii) antibody decline in seropositive subjects over a period of around 6 months, (iv) the usefulness of rapid antibody tests for outpatient screening. METHOD: A total of 3301 employees in 11 Austrian trauma hospitals and rehabilitation facilities of the Austrian Social Insurance for Occupational Risks (AUVA) participated in this open uncontrolled prospective cohort study. Rapid lateral flow tests, detecting a combination of IgM and IgM against SARS-CoV-2), two different types of CLIA (Diasorin, Roche), RT-PCR tests and serum neutralization tests (SNTs) were performed. The tests were conducted twice, with an interval of 42.4 ± 7.7 (Min = 30, Max = 64) days. Positive participants were re-tested with CLIA/SNT at a third time point after 188.0 ± 12.8 days. RESULTS: Only 27 out of 3301 participants (0.82%) had a positive antibody test at any time point during the study confirmed via neutralization test. Among positively tested participants in either test, 50.4% did not report any symptoms consistent with common manifestations of COVID-19 during the study period or within the preceding 6 weeks. In the group who tested positive during or prior to study inclusion the most common symptoms of an acute viral illness were rhinitis (21.9%), and loss of taste and olfactory sense (21.9%). Based on the neutralization test as the true condition, the rapid antibody test performed better on serum than whole blood as 84.6% instead of 65.4% could be detected correctly. Concerning both CLIA tests overall the Roche test detected 24 (sensitivity = 88.9%) and the Diasorin test 22 positive participants (sensitivity = 81.5%). In participants with a positive SNT result, a significant drop in neutralizing antibody titre from 31.8 ± 22.9 (Md = 32.0) at T1 to 26.1 ± 17.6 (Md = 21.3) at T2 to 21.4 ± 13.4 (Md = 16.0) at T3 (χ2 = 23.848, df = 2, p < 0.001) was observed (χ2 = 23.848, df = 2, p < 0.001)-with an average time of 42.4 ± 7.7 days between T1 and T2 and 146.9 ± 13.8 days between T2 and T3. CONCLUSIONS: During the study period (May 11th-August 3rd) only 0.82% were tested positive for antibodies in our study cohort. The antibody concentration decreases significantly over time with 14.8% (4 out of 27) losing detectable antibodies.

Neuroregenerative Potential of Prenyl- and Pyranochalcones: A Structure-Activity Study.

Loss of neuronal tissue is a hallmark of age-related neurodegenerative diseases. Since adult neurogenesis has been confirmed in the human brain, great interest has arisen in substances stimulating the endogenous neuronal regeneration mechanism based on adult neural stem cells. Medicinal plants are a valuable source of neuroactive small molecules. In the structure-activity study presented here, the activities of prenyl- and pyranochalcones were compared to each other, using a differentiation assay based on the doublecortin promoter sequences. The latter revealed that the pyrano ring is a crucial structural element for the induction of neuronal differentiation of adult neural stem cells, while compounds with a prenyl group show significantly lower activities. Furthermore, a decrease of pro-differentiation activity was observed following structural modifications, such as substitutions on the pyrano ring and on the B-ring of the chalcone. We also initiated the elucidation of the structural characteristics of the newly discovered lead substance xanthohumol C, which correlated with the activation of the doublecortin promoter during neuronal differentiation.

Functional Integration of Neuronal Precursors in the Adult Murine Piriform Cortex.

The extent of functional maturation and integration of nonproliferative neuronal precursors, becoming neurons in the adult murine piriform cortex, is largely unexplored. We thus questioned whether precursors eventually become equivalent to neighboring principal neurons or whether they represent a novel functional network element. Adult brain neuronal precursors and immature neurons (complex cells) were labeled in transgenic mice (DCX-DsRed and DCX-CreERT2 /flox-EGFP), and their cell fate was characterized with patch clamp experiments and morphometric analysis of axon initial segments. Young (DCX+) complex cells in the piriform cortex of 2- to 4-month-old mice received sparse synaptic input and fired action potentials at low maximal frequency, resembling neonatal principal neurons. Following maturation, the synaptic input detected on older (DCX-) complex cells was larger, but predominantly GABAergic, despite evidence of glutamatergic synaptic contacts. Furthermore, the rheobase current of old complex cells was larger and the maximal firing frequency was lower than those measured in neighboring age-matched principal neurons. The striking differences between principal neurons and complex cells suggest that the latter are a novel type of neuron and new coding element in the adult brain rather than simple addition or replacement for preexisting network components.

Early postnatal behavioral, cellular, and molecular changes in models of Huntington disease are reversible by HDAC inhibition.

Huntington disease (HD) is an autosomal dominant neurodegenerative disorder caused by expanded CAG repeats in the huntingtin gene (HTT). Although mutant HTT is expressed during embryonic development and throughout life, clinical HD usually manifests later in adulthood. A number of studies document neurodevelopmental changes associated with mutant HTT, but whether these are reversible under therapy remains unclear. Here, we identify very early behavioral, molecular, and cellular changes in preweaning transgenic HD rats and mice. Reduced ultrasonic vocalization, loss of prepulse inhibition, and increased risk taking are accompanied by disturbances of dopaminergic regulation in vivo, reduced neuronal differentiation capacity in subventricular zone stem/progenitor cells, and impaired neuronal and oligodendrocyte differentiation of mouse embryo-derived neural stem cells in vitro. Interventional treatment of this early phenotype with the histone deacetylase inhibitor (HDACi) LBH589 led to significant improvement in behavioral changes and markers of dopaminergic neurotransmission and complete reversal of aberrant neuronal differentiation in vitro and in vivo. Our data support the notion that neurodevelopmental changes contribute to the prodromal phase of HD and that early, presymptomatic intervention using HDACi may represent a promising novel treatment approach for HD.

The Leukotriene Receptor Antagonist Montelukast Attenuates Neuroinflammation and Affects Cognition in Transgenic 5xFAD Mice.

Alzheimer's disease (AD) is the most common form of dementia. In particular, neuroinflammation, mediated by microglia cells but also through CD8+ T-cells, actively contributes to disease pathology. Leukotrienes are involved in neuroinflammation and in the pathological hallmarks of AD. In consequence, leukotriene signaling-more specifically, the leukotriene receptors-has been recognized as a potential drug target to ameliorate AD pathology. Here, we analyzed the effects of the leukotriene receptor antagonist montelukast (MTK) on hippocampal gene expression in 5xFAD mice, a commonly used transgenic AD mouse model. We identified glial activation and neuroinflammation as the main pathways modulated by MTK. The treatment increased the number of Tmem119+ microglia and downregulated genes related to AD-associated microglia and to lipid droplet-accumulating microglia, suggesting that the MTK treatment targets and modulates microglia phenotypes in the disease model compared to the vehicle. MTK treatment further reduced infiltration of CD8+T-cells into the brain parenchyma. Finally, MTK treatment resulted in improved cognitive functions. In summary, we provide a proof of concept for MTK to be a potential drug candidate for AD and provide novel modes of action via modulation of microglia and CD8+ T-cells. Of note, 5xFAD females showed a more severe pathology, and in consequence, MTK treatment had a more pronounced effect in the females compared to the males. The effects on neuroinflammation, i.e., microglia and CD8+ T-cells, as well as the effects on cognitive outcome, were dose-dependent, therefore arguing for the use of higher doses of MTK in AD clinical trials compared to the approved asthma dose.

Early sacral neuromodulation ameliorates urinary bladder function and structure in complete spinal cord injury minipigs.

AIMS: To determine the effects of early sacral neuromodulation (SNM) and pudendal neuromodulation (PNM) on lower urinary tract (LUT) function, minipigs with complete spinal cord injury (cSCI) were analyzed. SNM and PNM have been proposed as therapeutic approaches to improve bladder function, for example after cSCI. However, further evidence on efficacy is required before these methods can become clinical practice. METHODS: Eleven adults, female Göttingen minipigs with cSCI at vertebral level T11-T12 were included: SNM (n = 4), PNM (n = 4), and SCI control (SCIC: n = 3). Tissue from six healthy minipigs was used for structural comparisons. Stimulation was started 1 week after cSCI. Awake urodynamics was performed on a weekly basis. After 16 weeks follow-up, samples from the urinary bladder were taken for analyses. RESULTS: SNM improved bladder function with better capacities and lower detrusor pressures at voiding and avoided the emergence of detrusor sphincter dyssynergia (DSD). PNM and untreated SCI minipigs had less favorable outcomes with either DSD or constant urinary retention. Structural results revealed SCI-typical fibrotic alterations in all cSCI minipigs. However, SNM showed a better-balanced distribution of smooth muscle to connective tissue with a trend towards the reduced progression of bladder wall scarring. CONCLUSION: Early SNM led to an avoidance of the emergence of DSD showing a more physiological bladder function during a 4 month follow-up period after cSCI. This study might pave the way for the clinical continuation of early SNM for the treatment of neurogenic LUT dysfunction after SCI.

Antisense Oligonucleotide in LNA-Gapmer Design Targeting TGFBR2-A Key Single Gene Target for Safe and Effective Inhibition of TGFß Signaling.

Antisense Oligonucleotides (ASOs) are an emerging drug class in gene modification. In our study we developed a safe, stable, and effective ASO drug candidate in locked nucleic acid (LNA)-gapmer design, targeting TGFß receptor II (TGFBR2) mRNA. Discovery was performed as a process using state-of-the-art library development and screening. We intended to identify a drug candidate optimized for clinical development, therefore human specificity and gymnotic delivery were favored by design. A staggered process was implemented spanning in-silico-design, in-vitro transfection, and in-vitro gymnotic delivery of small batch syntheses. Primary in-vitro and in-vivo toxicity studies and modification of pre-lead candidates were also part of this selection process. The resulting lead compound NVP-13 unites human specificity and highest efficacy with lowest toxicity. We particularly focused at attenuation of TGFß signaling, addressing both safety and efficacy. Hence, developing a treatment to potentially recondition numerous pathological processes mediated by elevated TGFß signaling, we have chosen to create our data in human lung cell lines and human neuronal stem cell lines, each representative for prospective drug developments in pulmonary fibrosis and neurodegeneration. We show that TGFBR2 mRNA as a single gene target for NVP-13 responds well, and that it bears great potential to be safe and efficient in TGFß signaling related disorders.

Aging restricts the ability of mesenchymal stem cells to promote the generation of oligodendrocytes during remyelination.

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system (CNS) that leads to severe neurological deficits. Due to their immunomodulatory and neuroprotective activities and their ability to promote the generation of oligodendrocytes, mesenchymal stem cells (MSCs) are currently being developed for autologous cell therapy in MS. As aging reduces the regenerative capacity of all tissues, it is of relevance to investigate whether MSCs retain their pro-oligodendrogenic activity with increasing age. We demonstrate that MSCs derived from aged rats have a reduced capacity to induce oligodendrocyte differentiation of adult CNS stem/progenitor cells. Aging also abolished the ability of MSCs to enhance the generation of myelin-like sheaths in demyelinated cerebellar slice cultures. Finally, in a rat model for CNS demyelination, aging suppressed the capability of systemically transplanted MSCs to boost oligodendrocyte progenitor cell (OPC) differentiation during remyelination. Thus, aging restricts the ability of MSCs to support the generation of oligodendrocytes and consequently inhibits their capacity to enhance the generation of myelin-like sheaths. These findings may impact on the design of therapies using autologous MSCs in older MS patients.

Improvement of fiber connectivity and functional recovery after stroke by montelukast, an available and safe anti-asthmatic drug.

Stroke is one of the main causes of death, neurological dysfunctions or disability in elderly. Neuroprotective drugs have been proposed to improve long-term recovery after stroke, but failed to reach clinical effectiveness. Hence, recent studies suggested that restorative therapies should combine neuroprotection and remyelination. Montelukast, an anti-asthmatic drug, was shown to exert neuroprotection in animal models of CNS injuries, but its ability to affect oligodendrocytes, restoring fiber connectivity, remains to be determined. In this study, we evaluated whether montelukast induces long-term repair by promoting fiber connectivity up to 8 weeks after middle cerebral artery occlusion (MCAo), using different experimental approaches such as in vivo diffusion magnetic resonance imaging (MRI), electrophysiological techniques, ex vivo diffusion tensor imaging (DTI)-based fiber tracking and immunohistochemistry. We found that, in parallel with a reduced evolution of ischemic lesion and atrophy, montelukast increased the DTI-derived axial diffusivity and number of myelin fibers, the density of myelin binding protein (MBP) and the number of GSTpi+ mature oligodendrocytes. Together with the rescue of MCAo-induced impairments of local field potentials in ischemic cortex, the data suggest that montelukast may improve fibers reorganization. Thus, to ascertain whether this effect involved changes of oligodendrocyte precursor cells (OPCs) activation and maturation, we used the reporter GPR17iCreERT2:CAG-eGreen florescent protein (GFP) mice that allowed us to trace the fate of OPCs throughout animal's life. Our results showed that montelukast enhanced the OPC recruitment and proliferation at acute phase, and increased their differentiation to mature oligodendrocytes at chronic phase after MCAo. Considering the crosstalk between OPCs and microglia has been widely reported in the context of demyelinating insults, we also assessed microglia activation. We observed that montelukast influenced the phenotype of microglial cells, increasing the number of M2 polarized microglia/macrophages, over the M1 phenotype, at acute phase after MCAo. In conclusion, we demonstrated that montelukast improves fiber re-organization and long-term functional recovery after brain ischemia, enhancing recruitment and maturation of OPCs. The present data suggest that montelukast, an already approved drug, could be "repositioned "as a protective drug in stroke acting also on fiber re-organization.

Cellular Plasticity in the Adult Murine Piriform Cortex: Continuous Maturation of Dormant Precursors Into Excitatory Neurons.

Neurogenesis in the healthy adult murine brain is based on proliferation and integration of stem/progenitor cells and is thought to be restricted to 2 neurogenic niches: the subventricular zone and the dentate gyrus. Intriguingly, cells expressing the immature neuronal marker doublecortin (DCX) and the polysialylated-neural cell adhesion molecule reside in layer II of the piriform cortex. Apparently, these cells progressively disappear along the course of ageing, while their fate and function remain unclear. Using DCX-CreERT2/Flox-EGFP transgenic mice, we demonstrate that these immature neurons located in the murine piriform cortex do not vanish in the course of aging, but progressively resume their maturation into glutamatergic (TBR1+, CaMKII+) neurons. We provide evidence for a putative functional integration of these newly differentiated neurons as indicated by the increase in perisomatic puncta expressing synaptic markers, the development of complex apical dendrites decorated with numerous spines and the appearance of an axonal initial segment. Since immature neurons found in layer II of the piriform cortex are generated prenatally and devoid of proliferative capacity in the postnatal cortex, the gradual maturation and integration of these cells outside of the canonical neurogenic niches implies that they represent a valuable, but nonrenewable reservoir for cortical plasticity.

A new technique for minimal invasive complete spinal cord injury in minipigs.

BACKGROUND: The aim of this study was to develop a minimal invasive complete spinal cord injury (SCI) minipig model for future research applications. The minipig is considered a translationally relevant model for SCI research. However, a standardized minimal invasive complete SCI model for pigs has not yet been established. METHODS: Adult Göttingen minipigs were anesthetized and placed in extended prone position. After initial computed tomography (CT) scan, the skin was incised, a needle placed in the epidural fatty tissue. Using the Seldinger technique, a guidewire and dilators were introduced to insert the balloon catheter to Th12. After confirmation of the level Th11/Th12, the balloon was inflated to 2 atm for 30 min. The severity of the lesion was followed by CT and by MRI, and by immunohistochemistry. Function was assessed at the motor and sensory level. RESULTS: Duration of procedure was about 60 min including the 30-min compression time. The balloon pressure of 2 atm was maintained without losses. The lesion site was clearly discernible and no intradural bleeding was observed by CT. Neurological assessments during the 4-month follow-up time showed consistent, predictable, and stable neurological deficits. Magnetic resonance imaging analyses at 6 h and 4 weeks post SCI with final immunohistochemical analyses of spinal cord tissue underlined the neurological outcomes and proved SCI completeness. CONCLUSIONS: We have established a new, minimal invasive, highly standardized, CT-guided spinal cord injury procedure for minipigs. All risks of the open surgery can be excluded using this technique. This CT-guided SC compression is an excellent technique as it avoids long surgery and extensive trauma and allows a feasible inter-animal comparison.

Doublecortin expression in CD8+ T-cells and microglia at sites of amyloid-ß plaques: A potential role in shaping plaque pathology?

INTRODUCTION: One characteristic of Alzheimer's disease is the formation of amyloid-ß plaques, which are typically linked to neuroinflammation and surrounded by inflammatory cells such as microglia and infiltrating immune cells. METHODS: Here, we describe nonneurogenic doublecortin (DCX) positive cells, DCX being generally used as a marker for young immature neurons, at sites of amyloid-ß plaques in various transgenic amyloid mouse models and in human brains with plaque pathology. RESULTS: The plaque-associated DCX+ cells were not of neurogenic identity, instead most of them showed coexpression with markers for microglia (ionized calcium-binding adapter molecule 1) and for phagocytosis (CD68 and TREM2). Another subpopulation of plaque-associated DCX+ cells was negative for ionized calcium-binding adapter molecule 1 but was highly positive for the pan-leukocyte marker CD45. These hematopoietic cells were identified as CD3-and CD8-positive and CD4-negative T-cells. DISCUSSION: Peculiarly, the DCX+/ionized calcium-binding adapter molecule 1+ microglia and DCX+/CD8+ T-cells were closely attached, suggesting that these two cell types are tightly interacting and that this interaction might shape plaque pathology.

Neurogenesis upregulation on the healthy hemisphere after stroke enhances compensation for age-dependent decrease of basal neurogenesis.

Stroke is a leading cause of death and disability worldwide with no treatment for the chronic phase available. Interestingly, an endogenous repair program comprising inflammation and neurogenesis is known to modulate stroke outcome. Several studies have shown that neurogenesis decreases with age but the therapeutic importance of endogenous neurogenesis for recovery from cerebral diseases has been indicated as its ablation leads to stroke aggravation and worsened outcome. A detailed characterization of the neurogenic response after stroke related to ageing would help to develop novel and targeted therapies. In an innovative approach, we used the DCX-Luc mouse, a transgenic model expressing luciferase in doublecortin-positive neuroblasts, to monitor the neurogenic response following middle cerebral artery occlusion over three weeks in three age groups (2, 6, 12months) by optical imaging while the stroke lesion was monitored by quantitative MRI. The individual longitudinal and noninvasive time profiles provided exclusive insight into age-dependent decrease in basal neurogenesis and neurogenic upregulation in response to stroke which are not accessible by conventional BrdU-based measures of cell proliferation. For cortico-striatal strokes the maximal upregulation occurred at 4days post stroke followed by a continuous decrease to basal levels by three weeks post stroke. Older animals effectively compensated for reduced basal neurogenesis by an enhanced sensitivity to the cerebral lesion, resulting in upregulated neurogenesis levels approaching those measured in young mice. In middle aged and older mice, but not in the youngest ones, additional upregulation of neurogenesis was observed in the contralateral healthy hemisphere. This further substantiates the increased propensity of older brains to respond to lesion situation. Our results clearly support the therapeutic relevance of endogenous neurogenesis for stroke recovery and particularly in older brains.

SMAD7 deficiency stimulates Müller progenitor cell proliferation during the development of the mammalian retina.

The transforming growth factor-ß (TGF-ß) pathway contributes to maintain the quiescence of adult neural stem and progenitor cells in the brain. In the retina, Müller cells are discussed to represent a glial cell population with progenitor-like characteristics. Here, we aimed to investigate if elevated TGF-ß signaling modulates the proliferation of Müller cells during retinal development. We generated mutant mice with a systemic, heterozygous up-regulation of TGF-ß signaling by deleting its inhibitor SMAD7. We investigated apoptosis, proliferation, and differentiation of Müller cells in the developing retina. We show that a heterozygous deletion of SMAD7 results in an increased proliferation of Müller cell progenitors in the central retina at postnatal day 4, the time window when Müller cells differentiate in the mouse retina. This in turn results in a thickened retina and inner nuclear layer and a higher number of differentiated Müller cells in the more developed retina. Müller cells in mutant mice contain higher amounts of nestin than those of control animals which indicates that the increase in TGF-ß signaling activity during retinal development contribute to maintain some progenitor-like characteristics in Müller cells even after their differentiation period. We conclude that TGF-ß signaling influences Müller cell proliferation and differentiation during retinal development.