Neurodegenerative Processes Research Articles

Senescence and aging differentially alter key metabolic pathways in murine brain microglia

Microglia, the resident immune cells of the central nervous system, are critically involved in maintaining brain homeostasis. With age, microglia display morphological and functional alterations that have been associated with cognitive decline and neurodegeneration. Although microglia seem to participate in an increasing number of biological processes which require a high energy demand, little is known about their metabolic regulation under physiological and pathophysiological conditions and during aging/senescence. Here, we determined mRNA expression levels of critical rate limiting enzymes in several key metabolic pathways including glycolysis, pentose phosphate pathway, fatty acid oxidation and synthesis in association with oxidative phosphorylation in microglia, both under aging and senescent conditions. We found strong evidence for different metabolic changes occuring in senescent vs. aged microglia cells. While senescent microglia display a hypermetabolic state as indicated by increased expression of key enzymes involved in glycolysis and pentose phosphate pathway, aging microglia are rather in a state of hypometabolism. Our findings indicate that studies involving aging and senescent microglia require a clear differentiation between these microglial states due to profound metabolic differences observed here. Understanding metabolic changes in senescent and aged microglia may lead to novel strategies to decrease over-activation of these cells due to aging, which is associated to the process of inflamm-aging and neurodegeneration.

Uncovering Cell Cycle Dysregulations and Associated Mechanisms in Cancer and Neurodegenerative Disorders: A Glimpse of Hope for Repurposed Drugs.

The cell cycle is the sequence of events orchestrated by a complex network of cell cycle proteins. Unlike normal cells, mature neurons subsist in a quiescent state of the cell cycle, and aberrant cell cycle activation triggers neuronal death accompanied by neurodegeneration. The periodicity of cell cycle events is choreographed by various mechanisms, including DNA damage repair, oxidative stress, neurotrophin activity, and ubiquitin-mediated degradation. Given the relevance of cell cycle processes in cancer and neurodegeneration, this review delineates the overlapping cell cycle events, signaling pathways, and mechanisms associated with cell cycle aberrations in cancer and the major neurodegenerative disorders. We suggest that dysregulation of some common fundamental signaling processes triggers anomalous cell cycle activation in cancer cells and neurons. We discussed the possible use of cell cycle inhibitors for neurodegenerative disorders and described the associated challenges. We propose that a greater understanding of the common mechanisms driving cell cycle aberrations in cancer and neurodegenerative disorders will open a new avenue for the development of repurposed drugs.

Involvement of Glucosamine 6 Phosphate Isomerase 2 (GNPDA2) Overproduction in β-Amyloid- and Tau P301L-Driven Pathomechanisms.

Alzheimer's disease (AD) is a neurodegenerative olfactory disorder affecting millions of people worldwide. Alterations in the hexosamine- or glucose-related pathways have been described through AD progression. Specifically, an alteration in glucosamine 6 phosphate isomerase 2 (GNPDA2) protein levels has been observed in olfactory areas of AD subjects. However, the biological role of GNPDA2 in neurodegeneration remains unknown. Using mass spectrometry, multiple GNPDA2 interactors were identified in human nasal epithelial cells (NECs) mainly involved in intraciliary transport. Moreover, GNPDA2 overexpression induced an increment in NEC proliferation rates, accompanied by transcriptomic alterations in Type II interferon signaling or cellular stress responses. In contrast, the presence of beta-amyloid or mutated Tau-P301L in GNPDA2-overexpressing NECs induced a slowdown in the proliferative capacity in parallel with a disruption in protein processing. The proteomic characterization of Tau-P301L transgenic zebrafish embryos demonstrated that GNPDA2 overexpression interfered with collagen biosynthesis and RNA/protein processing, without inducing additional changes in axonal outgrowth defects or neuronal cell death. In humans, a significant increase in serum GNPDA2 levels was observed across multiple neurological proteinopathies (AD, Lewy body dementia, progressive supranuclear palsy, mixed dementia and amyotrophic lateral sclerosis) (n = 215). These data shed new light on GNPDA2-dependent mechanisms associated with the neurodegenerative process beyond the hexosamine route.

Experimental rationale for the use of thioctic acid and indomethacin in the therapy of the early stage of retinal neurodegeneration

Purpose: to assess the possibility of using thioctic acid and indomethacin tin eyedrops for the therapy of early stages of retinal neurodegeneration.Material and methods. The study was performed on 20 Chinchilla rabbits, including 16 rabbits in whom the neurodegenerative process in the retina was produced by intravitreal installation of 6-hydroxydopamine (6-OHDA), 0.25 mg per eye, and 4 rabbits (8 eyes) served as control. Thioctic acid 0.5% and Indocollir 0.1% were instilled separately and in combination 5 times daily for 7 days after the injection of 6-OHDA. Pupillary light reaction was estimated and eye fundus condition analyzed. Alpha2-macroglobuline ( 2-MG) and SOD activity, dopamine and protein concentrations were measured in retinal homogenates.Results. Instillations of thioctic acid reduced the retinal damage area almost by half as compared to the untreated group (p d 0.005). Indomethacin was less effective, but the combination of the two drugs brought about a maximal reduction of the damage area (p d 0.05 against the untreated group). Both preparations normalized the disturbed pupillary light reaction. The injection of 6-OHDA caused a decrease of dopamine concentration in the retina (0.050 ± 0.009 pg/mg as against 0.095 ± 0.031 pg/mg in healthy controls, р d 0,05). After instillations of indomethacin and thioctic acid, the concentration tended to increase, and it increased significantly after treatment with their combination (0.141 ± 0.037 pg/mg, p d 0.01 as against untreated animals). The activity of 2-MG in retina decreased after a 6-OHDA injection (2.93 ± 0.42 pg/mg as against 5.5 ± 1.2 pg/mg in healthy controls, р < 0 005) just as they increased the decreased SOD (13.30 ± 5.68 U/mg in healthy controls, 5.41 ± 1.50 U/mg in untreated animals, р < 0.05). Both preparations applied separately or in combination caused a significant increase of 2-MG activity (thioctic acid — 4.19 ± 0.91 pg/mg, indomethacin — 6.95 ± 1.09 pg/mg, combination — 7.25 ± 0.63 pg/mg, р < 0.05 as against the untreated animals) and SOD activity (thioctic acid — 8.25 ± 1.27 U/mg, indomethacin — 29.84 ± 6.63 U/mg, combination — 23.99 ± 3.78 U/mg, р < 0.01 as against the untreated animals).Conclusion. The combination of indomethacin and thioctic acid in eyedrops is the most effective for the prevention of eye damage caused by 6-OHDA, which makes this method promising for the treatment of eye diseases accompanied by neurodegeneration.

Atypical Structure of Broca's Area in a Patient with Primary Progressive Atrophy Syndrome at the Onset of Alzheimer's Disease

This article presents a clinical case of Alzheimer’s disease with a debut as primary progressive aphasia syndrome. Insufficient use of routine magnetic resonance imaging in this case in the diagnosis of neurodegenerative diseases and the advantage of such additional neuroimaging methods as positron emission tomography, functional magnetic resonance imaging with a scale assessment of atrophic changes. Additional neuroimaging techniques have been shown to significantly improve the early detection of pathological changes in brain structures and to reveal the location of functional areas involved in the neurodegenerative process.

Computational Modelling and Biomechanical Analysis of Age-Related Craniocerebral Injuries: Insights into Bridging Veins

The aim of this study is to explain the higher incidence of subdural haematomas in elderly people compared to young adult. This research addresses the phenomenon by developing two distinct numerical models of the human head, simulating individuals people aged 77 and 28, respectively. These models are methodically constructed based on medical imaging data acquired through collaboration with hospitals and subsequently verified through empirical experimentation. Studies have shown that the main factor that influences the vulnerability to bridging vein rupture in older adults is the degenerative processes of nervous tissue. The most visible structural damage was observed in the outflow cuff segment. This phenomenon can be primarily attributed to specific geometric parameters associated with this anatomical region. The presented research emphasises the importance of computational models in understanding the pathomechanics of brain structures. As a result of the analyses, it was proven that the neurodegenerative processes of the brain that occur with age are crucial in understanding the higher incidence of subdural haematomas in elderly people.

Epigenetics and the neurodegenerative process.

Neurological diseases are multifactorial, geneticand environmental. Environmental factors such as diet, physical activityand emotional state are epigenetic factors. Environmental markers are responsible for epigenetic modifications. The effect of epigenetic changes is increased inflammation of the nervous system and neuronal damage. In recent years, it has been shown that epigenetic changes may cause an increased risk of neurological disordersbut, currently, the relationship between epigenetic modifications and neurodegeneration remains unclear. This review summarizes current knowledge about neurological disorders caused by epigenetic changes in diseases such as Alzheimer's disease, Parkinson's disease, strokeand epilepsy. Advances in epigenetic techniques may bekey to understanding the epigenetics of central changes in neurological diseases.

Proteoform Analysis of the Human Olfactory System: A Window into Neurodegenerative Diseases.

Background: Very little is known about the proteome of the human olfactory system and how diseases associated with olfactory dysfunctions can affect it. With this review, we try to summarize the existing literature on the use of this technique for a better understanding of the neurodegenerative disease process. Methods: We used the PubMed database and found different articles which were then selected independently by three authors. Results: We found 157 articles, of which, after careful selection, only 30 were analyzed in this review. We presented all the associations identified between the protein/pathway alterations neurodegenerative diseases and SARS-CoV-2 infection. Conclusions: We think that the proteome of the olfactory system through blood, saliva, and mucus analysis could be a new way to better understand, diagnose, and finally treat neurodegenerative diseases.

Galectin-9 and Tim-3 are upregulated in response to microglial activation induced by the peptide Amyloid-β (25–35)

Galectins are a group of β-galactoside-binding lectins associated with regulating immunological response. In the brains of AD patients and 5xFAD (familial AD) mice, galectin-3 (Gal-3) was highly upregulated and found to be expressed in microglia associated with Aβ plaques. However, the participation of other galectins, specifically galectin-9 (Gal-9) and T-cell immunoglobulin and mucin domain 3 (Tim-3) receptors, are unknown in the inflammatory response. The experimental model of the Aβ25–35 peptide will allow us to study the mechanisms of neuroinflammation and describe the changes in the expression of the Gal-9 and Tim-3 receptor. This study aimed to evaluate whether Aβ25–35 peptide administration into the lateral ventricles of rats upregulated Gal-9 and Tim-3 implicated in the modulation of neuroinflammation. The vehicle or Aβ25–35 peptide (1 μg/μL) was bilaterally administered into the lateral ventricles of the rat, and control group. After the administration of the Aβ25–35 peptide, animals were tested for learning (day 29) and spatial memory (day 30) in the novel object recognition test (NOR). On day 31, hippocampus was examined for morphological changes by Nilss stain, biochemical changes by NO2 and MDA, immunohistochemical analysis by astrocytes (GFAP), microglia (Iba1), Gal-9 and Tim-3, and western blot. Our results show the administration of the Aβ25–35 peptide into the lateral ventricles of rats induce memory impairment in the NOR by increases the oxidative stress and inflammatory response. This result is associated with an upregulation of Gal-9 and Tim-3 predominantly detected in the microglia cells of Aβ25–35-treated rats with respect to the control group. Gal-9 and Tim-3 are upregulated in activated microglia that could modulate the inflammatory response and damage in neurodegenerative processes induced by the Aβ25–35 peptide. Therefore, we suggest that Gal-9 and Tim-3 participate in the inflammatory process induced by the administration of the Aβ25–35 peptide.

Advanced brain aging in Parkinson’s disease with cognitive impairment

Patients with Parkinson’s disease and cognitive impairment (PD-CI) deteriorate faster than those without cognitive impairment (PD-NCI), suggesting an underlying difference in the neurodegeneration process. We aimed to verify brain age differences in PD-CI and PD-NCI and their clinical significance. A total of 94 participants (PD-CI, n = 27; PD-NCI, n = 34; controls, n = 33) were recruited. Predicted age difference (PAD) based on gray matter (GM) and white matter (WM) features were estimated to represent the degree of brain aging. Patients with PD-CI showed greater GM-PAD (7.08 ± 6.64 years) and WM-PAD (8.82 ± 7.69 years) than those with PD-NCI (GM: 1.97 ± 7.13, Padjusted = 0.011; WM: 4.87 ± 7.88, Padjusted = 0.049) and controls (GM: -0.58 ± 7.04, Padjusted = 0.004; WM: 0.88 ± 7.45, Padjusted = 0.002) after adjusting demographic factors. In patients with PD, GM-PAD was negatively correlated with MMSE (Padjusted = 0.011) and MoCA (Padjusted = 0.013) and positively correlated with UPDRS Part II (Padjusted = 0.036). WM-PAD was negatively correlated with logical memory of immediate and delayed recalls (Padjusted = 0.003 and Padjusted < 0.001). Also, altered brain regions in PD-CI were identified and significantly correlated with brain age measures, implicating the neuroanatomical underpinning of neurodegeneration in PD-CI. Moreover, the brain age metrics can improve the classification between PD-CI and PD-NCI. The findings suggest that patients with PD-CI had advanced brain aging that was associated with poor cognitive functions. The identified neuroimaging features and brain age measures can serve as potential biomarkers of PD-CI.

NeuroGenetics of Alzheimer’s Disease: Crosslinking SIRT1 Gene in the Genetic Nexus of Type II Diabetes and Dementia

Background: Background: Type II Diabetes Mellitus (DM) is a chronic condition that not only affects organ function but also contributes to the development of dementia. SIRT1, a gene implicated in the pathophysiology of Type II DM, has been associated with neurodegenerative processes and cognitive decline. Objective: This study aimed to evaluate the expression of the SIRT1 gene in patients with Type II DM and dementia, elucidating its potential role as a biomarker for cognitive impairment and neurodegeneration in this population. Methods: A cohort of 88 diabetic patients with dementia and 12 healthy controls were recruited, and EDTA blood samples were collected. SIRT1 serum levels were quantified using chemiluminescent immunoassay (CLIA). Genomic DNA was extracted and assessed for quality before bisulfite DNA modification and Methylation Specific PCR (MSP) to profile SIRT1 gene methylation. Real-time PCR was conducted to determine SIRT1 gene expression levels. Cognitive function was assessed using Mini-Mental State Examination (MMSE) scores. Results: The average SIRT1 serum levels in diabetic dementia patients (4.98 ± 1.38 µg/mL) were significantly lower than those in healthy controls (14.21 ± 3.64 µg/mL). MMSE scores mirrored this trend, with patients scoring 12.26 ± 4.56, indicating more considerable cognitive impairment compared to healthy controls' score of 24.1 ± 3.12. SIRT1 gene expression was found to be underexpressed with a fold decrease of approximately 4.1 in dementia cases. Conclusion: The study's findings highlight the downregulated expression of the SIRT1 gene in diabetic patients with dementia, confirming its potential as a biomarker for cognitive decline. Identifying SIRT1 alterations may provide a non-invasive approach for early diagnosis and management of dementia in the diabetic population.

Reactive antibodies against brain antigens as serological biomarkers of neurodegenerative diseases

The aging of the population, attributed to increased life expectancy, coincides with a rise in the prevalence of neurodegenerative diseases such as Alzheimer&amp;rsquo;s disease and Parkinson&amp;rsquo;s disease. The symptoms of these disorders, such as motor disturbances and cognitive impairment, occur only after significant neurological damage, greatly diminishing the effectiveness of treatments. Consequently, achieving early diagnosis of neurodegenerative diseases stands as a paramount global health challenge. These conditions are characterized by the progressive loss of specific neuronal groups in the nervous system, resulting in dysfunction and eventual cell death in the brain. Although the exact cause of neuronal degeneration remains largely unknown, recent studies have revealed the significant involvement of the immune system in the pathogenesis of these diseases. Notably, the identification of reactive antibodies targeting specific antigens has highlighted a close association between immune mechanisms and the neurodegenerative process. Thus, the aim of this review is to explore the mechanisms of the adaptive immune system and their impact on the pathogenesis of neurodegenerative diseases, with a particular focus on reactive antibodies and their potential as diagnostic biomarkers.

VEGF expression disparities in brainstem motor neurons of the SOD1G93A ALS model: Correlations with neuronal vulnerability

Amyotrophic lateral sclerosis (ALS) is a rare neuromuscular disease characterized by severe muscle weakness mainly due to degeneration and death of motor neurons. A peculiarity of the neurodegenerative processes is the variable susceptibility among distinct neuronal populations, exemplified by the contrasting resilience of motor neurons innervating the ocular motor system and the more vulnerable facial and hypoglossal motor neurons. The crucial role of vascular endothelial growth factor (VEGF) as a neuroprotective factor in the nervous system is well-established since a deficit of VEGF has been related to motoneuronal degeneration. In this study, we investigated the survival of ocular, facial, and hypoglossal motor neurons utilizing the murine SOD1G93A ALS model at various stages of the disease. Our primary objective was to determine whether the survival of the different brainstem motor neurons was linked to disparate VEGF expression levels in resilient and susceptible motor neurons throughout neurodegeneration. Our findings revealed a selective loss of motor neurons exclusively within the vulnerable nuclei. Furthermore, a significantly higher level of VEGF was detected in the more resistant motor neurons, the extraocular ones. We also examined whether TDP-43 dynamics in the brainstem motor neuron of SOD mice was altered. Our data suggests that the increased VEGF levels observed in extraocular motor neurons may potentially underlie their resistance during the neurodegenerative processes in ALS in a TDP-43-independent manner. Our work might help to better understand the underlying mechanisms of selective vulnerability of motor neurons in ALS.

NeuroGenetics of Alzheimer’s Disease: Cross-Linking BDNF Brain-Derived Neurotrophic Factor in the Genetic Nexus of Type II Diabetes and Dementia

Background: Alzheimer’s disease and dementia are commonly associated with aging, particularly in the context of Type II Diabetes Mellitus (Type II DM), which is known to exacerbate micro and macrovascular complications that affect cognitive functions. The Brain-Derived Neurotrophic Factor (BDNF) gene has been implicated in the neurodegenerative processes that underscore these conditions. Objective: This study aimed to investigate the expression of the BDNF gene in diabetic patients with dementia and analyze its correlation with cognitive impairment, to establish BDNF as a potential biomarker for early detection and therapeutic targeting. Methods: A cohort of 102 patients with diabetic dementia and 32 healthy controls was enrolled. EDTA blood samples were collected and processed to measure BDNF serum levels using a Chemiluminescent Immunoassay (CLIA). Genomic DNA was isolated, and its integrity was confirmed via UV spectrophotometry and gel electrophoresis. The bisulfite DNA modification and Methylation-Specific PCR were conducted to analyze BDNF gene expression, followed by quantitative real-time PCR. Cognitive function was assessed using Mini-Mental State Examination (MMSE). Results: The study revealed a significant decrease in BDNF serum levels in diabetic dementia patients (12.6 ng/mL) compared to healthy controls (34.8 ng/mL), with MMSE scores averaging at 13.2 and 24.6, respectively. BDNF gene expression showed a 4.1-fold decrease in the dementia group. Statistical analysis indicated that these differences were significant (p&lt;0.05). Conclusion: The reduced expression of BDNF in patients with diabetic dementia confirms its potential as a biomarker for cognitive impairment. Early detection and intervention strategies that modulate BDNF could ameliorate the impact of dementia in the context of diabetes.

Second Near-Infrared Macrophage-Biomimetic Nanoprobes for Photoacoustic Imaging of Neuroinflammation.

Neuroinflammation is a significant pathological event involving the neurodegenerative process associated with many neurological disorders. Diagnosis and treatment of neuroinflammation in its early stage are essential for the prevention and management of neurological diseases. Herein, we designed macrophage membrane-coated photoacoustic (PA) probes (MSINPs), with targeting specificities based on naturally existing target-ligand interactions for the early diagnosis of neuroinflammation. The second near-infrared dye, IR1061, was doped into silica as the core and was encapsulated with a macrophage membrane. In vitro as well as in vivo, the MSINPs could target inflammatory cells via the inflammation chemotactic effect. PA imaging was used to trace the MSINPs in a neuroinflammation mouse model and showed a great targeted effect of MSINPs in the prefrontal cortex. Therefore, the biomimetic nanoprobe prepared in this study offers a new strategy for PA molecular imaging of neuroinflammation, which can enhance our understanding of the evolution of neuroinflammation in specific brain regions.

The clinical and genetic spectrum of inherited glycosylphosphatidylinositol deficiency disorders.

Inherited glycosylphosphatidylinositol deficiency disorders (IGDs) are a group of rare multisystem disorders arising from pathogenic variants in glycosylphosphatidylinositol anchor pathway (GPI-AP) genes. Despite associating 24 of at least 31 GPI-AP genes with human neurogenetic disease, prior reports are limited to single genes without consideration of the GPI-AP as a whole and with limited natural history data. In this multinational retrospective observational study, we systematically analyse the molecular spectrum, phenotypic characteristics and natural history of 83 individuals from 75 unique families with IGDs, including 70 newly reported individuals; the largest single cohort to date. Core clinical features were developmental delay or intellectual disability (DD/ID, 90%), seizures (83%), hypotonia (72%) and motor symptoms (64%). Prognostic and biologically significant neuroimaging features included cerebral atrophy (75%), cerebellar atrophy (60%), callosal anomalies (57%) and symmetric restricted diffusion of the central tegmental tracts (60%). Sixty-one individuals had multisystem involvement including gastrointestinal (66%), cardiac (19%) and renal (14%) anomalies. Though dysmorphic features were appreciated in 82%, no single dysmorphic feature had a prevalence >30%, indicating substantial phenotypic heterogeneity. Follow-up data were available for all individuals, 15 of whom were deceased at the time of writing. Median age at seizure onset was 6 months. Individuals with variants in synthesis stage genes of the GPI-AP exhibited a significantly shorter time to seizure onset than individuals with variants in transamidase and remodelling stage genes of the GPI-AP (P = 0.046). Forty individuals had intractable epilepsy. The majority of individuals experienced delayed or absent speech (95%), motor delay with non-ambulance (64%), and severe-to-profound DD/ID (59%). Individuals with a developmental epileptic encephalopathy (51%) were at greater risk of intractable epilepsy (P = 0.003), non-ambulance (P = 0.035), ongoing enteral feeds (P < 0.001) and cortical visual impairment (P = 0.007). Serial neuroimaging showed progressive cerebral volume loss in 87.5% and progressive cerebellar atrophy in 70.8%, indicating a neurodegenerative process. Genetic analyses identified 93 unique variants (106 total), including 22 novel variants. Exploratory analyses of genotype-phenotype correlations using unsupervised hierarchical clustering identified novel genotypic predictors of clinical phenotype and long-term outcome with meaningful implications for management. In summary, we expand both the mild and severe phenotypic extremities of the IGDs, provide insights into their neurological basis, and vitally, enable meaningful genetic counselling for affected individuals and their families.

Functional analysis of feedback inhibition-insensitive aspartate kinase identified in a threonine-accumulating mutant of Saccharomyces cerevisiae.

Humans and mammals need to ingest essential amino acids (EAAs) for protein synthesis. In addition to their importance as nutrients, EAAs are involved in brain homeostasis. However, elderly people are unable to efficiently consume EAAs from their daily diet due to reduced appetite and variations in the contents of EAAs in foods. On the other hand, strains of the yeast Saccharomyces cerevisiae that accumulate EAAs would enable elderly people to intakegest adequate amounts of EAAs and thus might slow down the neurodegenerative process, contributing to the extension of their healthy lifespan. In this study, we isolated a mutant (strain HNV-5) that accumulates threonine, an EAA, derived from a diploid laboratory yeast by conventional mutagenesis. Strain HNV-5 carries a novel mutation in the HOM3 gene encoding the Ala462Thr variant of aspartate kinase (AK). Enzymatic analysis revealed that the Ala462Thr substitution significantly decreased the sensitivity of AK activity to threonine feedback inhibition even in the presence of 50 mM threonine. Interestingly, Ala462Thr substitution did not affect the catalytic ability of Hom3, in contrast to previously reported amino acid substitutions that resulted in reduced sensitivity to threonine feedback inhibition. Furthermore, yeast cells expressing the Ala462Thr variant showed an approximately threefold increase in intracellular threonine content compared to that of the wild-type Hom3. These findings will be useful for the development of threonine-accumulating yeast strains that may improve the quality of life in elderly people.IMPORTANCEFor humans and mammals, essential amino acids (EAAs) play an important role in maintaining brain function. Therefore, increasing the intake of EAAs by using strains of the yeast Saccharomyces cerevisiae that accumulate EAAs may inhibit neurodegeneration in elderly people and thus contribute to extending healthy lifespan and improving their quality of life. Threonine, an EAA, is synthesized from aspartate. Aspartate kinase (AK) catalyzes the first step in threonine biosynthesis and is subject to allosteric regulation by threonine. Here, we isolated a threonine-accumulating mutant of S. cerevisiae by conventional mutagenesis and identified a mutant gene encoding a novel variant of AK. In contrast to previously isolated variants, the Hom3 variant exhibited AK activity that was insensitive to feedback inhibition by threonine but retained its catalytic ability. This resulted in increased production of threonine in yeast. These findings open up the possibility for the rational design of AK to increase threonine productivity in yeast.

TDP-43 pathology in subacute sclerosing panencephalitis.

Subacute sclerosing panencephalitis (SSPE) is a fatal, slowly progressive brain disorder caused by a mutated measles virus. Both subacute inflammatory and neurodegenerative mechanisms appear to play significant roles in the pathogenesis. TAR DNA-binding protein 43 (TDP-43) inclusions are a common co-pathology in several neurodegenerative disorders with diverse pathogenesis. In the present study, we examined brains of 16 autopsied SSPE patients for the presence of TDP-43 pathology and possible associations with tau pathology. Immunohistochemical staining identified TDP-43 inclusions in 31% of SSPE cases. TDP-43 pathology was widely distributed in the brains, most severely in the atrophied cerebral cortex (temporal and parietal), and most frequently as tangle- and thread-like neuronal cytoplasmic inclusions. It was associated with longer disease duration (>4 years) and tau pathology (all TDP-43-positive cases had tau-positive neurofibrillary tangles). This study demonstrates for the first time an association between TDP-43 pathology and SSPE. The co-occurrence of TDP-43 and tau aggregates and correlation with the disease duration suggest that both pathological proteins are involved in the neurodegenerative process induced by viral inflammation.

In a novel autoimmune and high-pressure glaucoma model a complex immune response is induced.

The neurodegenerative processes leading to glaucoma are complex. In addition to elevated intraocular pressure (IOP), an involvement of immunological mechanisms is most likely. In the new multifactorial glaucoma model, a combination of high IOP and optic nerve antigen (ONA) immunization leads to an enhanced loss of retinal ganglion cells accompanied by a higher number of microglia/macrophages in the inner retina. Here, we aimed to evaluate the immune response in this new model, especially the complement activation and the number of T-cells, for the first time. Further, the microglia/macrophage response was examined in more detail. Six-week-old wildtype (WT+ONA) and βB1-connective tissue growth factor high-pressure mice (CTGF+ONA) were immunized with 1 mg ONA. A wildtype control (WT) and a CTGF group (CTGF) received NaCl instead. Six weeks after immunization, retinae from all four groups were processed for immunohistology, RT-qPCR, and flow cytometry, while serum was used for microarray analyses. We noticed elevated numbers of C1q+ cells (classical complement pathway) in CTGF and CTGF+ONA retinae as well as an upregulation of C1qa, C1qb, and C1qc mRNA levels in these groups. While the complement C3 was only increased in CTGF and CTGF+ONA retinae, enhanced numbers of the terminal membrane attack complex were noted in all three glaucoma groups. Flow cytometry and RT-qPCR analyses revealed an enhancement of different microglia/macrophages markers, including CD11b, especially in CTGF and CTGF+ONA retinae. Interestingly, increased retinal mRNA as well as serum levels of the tumor necrosis factor α were found throughout the different glaucoma groups. Lastly, more T-cells could be observed in the ganglion cell layer of the new CTGF+ONA model. These results emphasize an involvement of the complement system, microglia/macrophages, and T-cells in glaucomatous disease. Moreover, in the new multifactorial glaucoma model, increased IOP in combination with autoimmune processes seem to enforce an additional T-cell response, leading to a more persistent pathology. Hence, this new model mimics the pathomechanisms occurring in human glaucoma more accurately and could therefore be a helpful tool to find new therapeutic approaches for patients in the future.

Early Increase in Blood-Brain Barrier Permeability in a Murine Model Exposed to Fifteen Days of Intermittent Hypoxia.

Obstructive sleep apnea (OSA) is characterized by intermittent repeated episodes of hypoxia-reoxygenation. OSA is associated with cerebrovascular consequences. An enhanced blood-brain barrier (BBB) permeability has been proposed as a marker of those disorders. We studied in mice the effects of 1 day and 15 days intermittent hypoxia (IH) exposure on BBB function. We focused on the dorsal part of the hippocampus and attempted to identify the molecular mechanisms by combining in vivo BBB permeability (Evans blue tests) and mRNA expression of several junction proteins (zona occludens (ZO-1,2,3), VE-cadherin, claudins (1,5,12), cingulin) and of aquaporins (1,4,9) on hippocampal brain tissues. After 15 days of IH exposure we observed an increase in BBB permeability, associated with increased mRNA expressions of claudins 1 and 12, aquaporins 1 and 9. IH seemed to increase early for claudin-1 mRNA expression as it doubled with 1 day of exposure and returned near to its base level after 15 days. Claudin-1 overexpression may represent an immediate response to IH exposure. Then, after 15 days of exposure, an increase in functional BBB permeability was associated with enhanced expression of aquaporin. These BBB alterations are possibly associated with a vasogenic oedema that may affect brain functions and accelerate neurodegenerative processes.