Neuropeptide FF (NPFF)-positive nerve cells of the human cerebral cortex and white matter in controls, selected neurodegenerative diseases, and schizophrenia.

We quantified and determined for the first time the distribution pattern of the neuropeptide NPFF in the human cerebral cortex and subjacent white matter. To do so, we studied n = 9 cases without neurological disorders and n = 22 cases with neurodegenerative diseases, including sporadic amyotrophic lateral sclerosis (ALS, n = 8), Alzheimer's disease (AD, n = 8), Pick's disease (PiD, n = 3), and schizophrenia (n = 3). NPFF-immunopositive cells were located chiefly, but not exclusively, in the superficial white matter and constituted there a subpopulation of white matter interstitial cells (WMIC): Pyramidal-like and multipolar somata predominated in the gyral crowns, whereas bipolar and ovoid somata predominated in the cortex surrounding the sulci. Their sparsely ramified axons were unmyelinated and exhibited NPFF-positive bead-like varicosities. We found significantly fewer NPFF-immunopositive cells in the gray matter of the frontal, cingulate, and superior temporal gyri of both sporadic ALS and late-stage AD patients than in controls, and significantly fewer NPFF-positive cells in the subjacent as well as deep white matter of the frontal gyrus of these patients compared to controls. Notably, the number of NPFF-positive cells was also significantly lower in the hippocampal formation in AD compared to controls. In PiD, NPFF-positive cells were present in significantly lower numbers in the gray and white matter of the cingulate and frontal gyrii in comparison to controls. In schizophrenic patients, lower wNPFF cell counts in the neocortex were significant and global (cingulate, frontal, superior temporal gyrus, medial, and inferior gyri). The precise functions of NPFF-positive cells and their relationship to the superficial corticocortical white matter U-fibers are currently unknown. Here, NPFF immunohistochemistry and expression characterize a previously unrecognized population of cells in the human brain, thereby providing a new entry-point for investigating their physiological and pathophysiological roles.

Dynamics of synaptic damage in severe traumatic brain injury revealed by cerebrospinal fluid SNAP-25 and VILIP-1.

BACKGROUND: Biomarkers of neuronal, glial cells and inflammation in traumatic brain injury (TBI) are available but they do not specifically reflect the damage to synapses, which represent the bulk volume of the brain. Experimental models have demonstrated extensive involvement of synapses in acute TBI, but biomarkers of synaptic damage in human patients have not been explored. METHODS: Single-molecule array assays were used to measure synaptosomal-associated protein-25 (SNAP-25) and visinin-like protein 1 (VILIP-1) (along with neurofilament light chain (NFL), ubiquitin carboxy-terminal hydrolase L1 (UCH-L1), glial fibrillar acidic protein (GFAP), interleukin-6 (IL-6) and interleukin-8 (IL-8)) in ventricular cerebrospinal fluid (CSF) samples longitudinally acquired during the intensive care unit (ICU) stay of 42 patients with severe TBI or 22 uninjured controls. RESULTS: CSF levels of SNAP-25 and VILIP-1 are strongly elevated early after severe TBI and decline in the first few days. SNAP-25 and VILIP-1 correlate with inflammatory markers at two distinct timepoints (around D1 and then again at D5) in follow-up. SNAP-25 and VILIP-1 on the day-of-injury have better sensitivity and specificity for unfavourable outcome at 6 months than NFL, UCH-L1 or GFAP. Later elevation of SNAP-25 was associated with poorer outcome. CONCLUSION: Synaptic damage markers are acutely elevated in severe TBI and predict long-term outcomes, as well as, or better than, markers of neuroaxonal injury. Synaptic damage correlates with initial injury and with a later phase of secondary inflammatory injury.

Blood-CSF barrier integrity in amyotrophic lateral sclerosis.

The integrity of the blood-CSF barrier plays a major role in inflammation, but also in shielding the central nervous system from external and systemic - potentially toxic - factors. Here we report results of measurements of the albumin quotient - which is thought to mirror the integrity of the blood/CSF barrier - in 1059 amyotrophic lateral sclerosis patients. The results were compared with groups of patients suffering from Alzheimer´s disease, facial palsy and tension headache. The albumin quotient, an accepted measure of the blood/CSF barrier integrity, was not significantly different from control populations. In addition, we found that the albumin quotient correlated with survival of the patients; this effect was mainly driven by male patients and influenced by age, BMI and diabetes mellitus. We conclude that the blood/CSF barrier is intact in this large cohort of ALS patients and that the albumin quotient correlates with survival. Whether this is important for the pathogenesis of the disease, requires mechanistic studies.

Non-canonical adrenergic neuromodulation of motoneuron intrinsic excitability through ß-receptors in wild-type and ALS mice.

Altered neuronal excitability and synaptic inputs to motoneurons are part of the pathophysiology of Amyotrophic Lateral Sclerosis. The cAMP/PKA pathway regulates both of them but therapeutic interventions at this level are limited by the lack of knowledge about suitable pharmacological entry points. Here we used transcriptomics on microdissected and in situ motoneurons to reveal the modulation of PKA-coupled receptorome in SOD1(G93A) ALS mice, vs WT, demonstrating the dysregulation of multiple PKA-coupled GPCRs, in particular on vulnerable MNs, and the relative sparing of ß-adrenergic receptors. In vivo MN electrophysiology showed that ß2/ß3 agonists acutely increase excitability, in particular the input/output relationship, demonstrating a non-canonical adrenergic neuromodulation mediated by ß2/ß3 receptors both in WT and SOD1 mice. The excitability increase corresponds to the upregulation of immediate-early gene expression and dysregulation of ion channels transcriptome. However the ß2/ß3 neuromodulation is submitted to a strong homeostasis, since a ten days delivery of ß2/ß3 agonists results in an abolition of the excitability increase. The homeostatic response is largely caused by a substantial downregulation of PKA-coupled GPCRs in MNs from WT and SOD1 mice. Thus, ß-adrenergic receptors are physiologically involved in the regulation of MN excitability and transcriptomics, but, intriguingly, a strong homeostatic response is triggered upon chronic pharmacologic intervention.

Spinal microcircuits go through multiphasic homeostatic compensations in a mouse model of motoneuron degeneration.

In neurological conditions affecting the brain, early-stage neural circuit adaption is key for long-term preservation of normal behaviour. We tested if motoneurons and respective microcircuits also adapt in the initial stages of disease progression in a mouse model of progressive motoneuron degeneration. Using a combination of in vitro and in vivo electrophysiology and super-resolution microscopy, we found that, preceding muscle denervation and motoneuron death, recurrent inhibition mediated by Renshaw cells is reduced in half due to impaired quantal size associated with decreased glycine receptor density. Additionally, higher probability of release from proprioceptive Ia terminals leads to increased monosynaptic excitation to motoneurons. Surprisingly, the initial impairment in recurrent inhibition is not a widespread feature of inhibitory spinal circuits, such as group I inhibitory afferents, and is compensated at later stages of disease progression. We reveal that in disease conditions, spinal microcircuits undergo specific multiphasic homeostatic compensations to preserve force output.

AI-assisted quantification of hypothalamic atrophy in amyotrophic lateral sclerosis by convolutional neural network-based automatic segmentation.

The hypothalamus is a small structure of the brain with an essential role in metabolic homeostasis, sleep regulation, and body temperature control. Some neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and dementia syndromes are reported to be related to hypothalamic volume alterations. Despite its crucial role in human body regulation, neuroimaging studies of this structure are rather scarce due to work-intensive operator-dependent manual delineations from MRI and lack of automated segmentation tools. In this study we present a fully automatic approach based on deep convolutional neural networks (CNN) for hypothalamic segmentation and volume quantification. We applied CNN of U-Net architecture with EfficientNetB0 backbone to allow for accurate automatic hypothalamic segmentation in seconds on a GPU. We further applied our approach for the quantification of the normalized hypothalamic volumes to a large neuroimaging dataset of 432 ALS patients and 112 healthy controls (without the ground truth labels). Using the automated volumetric analysis, we could reproduce hypothalamic atrophy findings associated with ALS by detecting significant volume differences between ALS patients and controls at the group level. In conclusion, a fast and unbiased AI-assisted hypothalamic quantification method is introduced in this study (whose acceptance rate based on the outlier removal strategy was estimated to be above 95%) and made publicly available for researchers interested in the conduction of hypothalamus studies at a large scale.

Patterns of synaptic loss in human amyotrophic lateral sclerosis spinal cord: a clinicopathological study.

Amyotrophic Lateral Sclerosis (ALS) is mainly characterized by the degeneration of corticospinal neurons and spinal α-motoneurons; vulnerable cells display prominent pTDP-43 inclusions. Evidence gathered from genetics, murine models, and iPSC-derived neurons point to the early involvement of synapses in the disease course and their crucial role in the pathogenic cascade. However, pathology studies, with specimens from large post-mortem cohorts, mapping the pattern of synaptic disturbances over clinical and neuropathological hallmarks of disease progression, are currently not available. Thus, the appearance and progression of synaptic degeneration in human ALS patients are currently not known, preventing a full validation of the murine and in vitro models. Here, we investigated the loss of synaptophysin-positive terminals in cervical, thoracic, and lumbar spinal cord samples from a retrospective cohort of n = 33 ALS patients and n = 8 healthy controls, and we correlated the loss of synapses against clinicodemographic features and neuropathological ALS stage. We found that, although dorsal and intermediate spinal cord laminae do not lose synapses, ALS patients displayed a substantial but variable loss of synapses in the ventral horn of lumbar and cervical spinal cord. The amount of synaptic loss was predicted by disease duration, by the clinical site of onset, and by the loss of α-motoneurons, although not by the fraction of pTDP-43-immunopositive α-motoneurons. Taken together, our findings validate the synaptic pathology observed in other models and suggest that pathogenic pathways unfolding in the spinal microenvironment are critical to the progressive disassembly of local synaptic connectivity.

SRF deletion results in earlier disease onset in a mouse model of amyotrophic lateral sclerosis.

Changes in neuronal activity modulate the vulnerability of motoneurons (MNs) in neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). So far, the molecular basis of neuronal activity's impact in ALS is poorly understood. Herein, we investigated the impact of deleting the neuronal activity-stimulated transcription factor (TF) serum response factor (SRF) in MNs of SOD1G93A mice. SRF was present in vulnerable MMP9+ MNs. Ablation of SRF in MNs induced an earlier disease onset starting around 7-8 weeks after birth, as revealed by enhanced weight loss and decreased motor ability. This earlier disease onset in SRF-depleted MNs was accompanied by a mild elevation of neuroinflammation and neuromuscular synapse degeneration, whereas overall MN numbers and mortality were unaffected. In SRF-deficient mice, MNs showed impaired induction of autophagy-encoding genes, suggesting a potentially new SRF function in transcriptional regulation of autophagy. Complementary, constitutively active SRF-VP16 enhanced autophagy-encoding gene transcription and autophagy progression in cells. Furthermore, SRF-VP16 decreased ALS-associated aggregate induction. Chemogenetic modulation of neuronal activity uncovered SRF as having important TF-mediating activity-dependent effects, which might be beneficial to reduce ALS disease burden. Thus, our data identify SRF as a gene regulator connecting neuronal activity with the cellular autophagy program initiated in degenerating MNs.

Shank2 identifies a subset of glycinergic neurons involved in altered nociception in an autism model.

BACKGROUND: Autism Spectrum Disorders (ASD) patients experience disturbed nociception in the form of either hyposensitivity to pain or allodynia. A substantial amount of processing of somatosensory and nociceptive stimulus takes place in the dorsal spinal cord. However, many of these circuits are not very well understood in the context of nociceptive processing in ASD. METHODS: We have used a Shank2-/- mouse model, which displays a set of phenotypes reminiscent of ASD, and performed behavioural and microscopic analysis to investigate the role of dorsal horn circuitry in nociceptive processing of ASD. RESULTS: We determined that Shank2-/- mice display increased sensitivity to formalin pain and thermal preference, but a sensory specific mechanical allodynia. We demonstrate that high levels of Shank2 expression identifies a subpopulation of neurons in murine and human dorsal spinal cord, composed mainly by glycinergic interneurons and that loss of Shank2 causes the decrease in NMDAR in excitatory synapses on these inhibitory interneurons. In fact, in the subacute phase of the formalin test, glycinergic interneurons are strongly activated in wild type (WT) mice but not in Shank2-/- mice. Consequently, nociception projection neurons in laminae I are activated in larger numbers in Shank2-/- mice. LIMITATIONS: Our investigation is limited to male mice, in agreement with the higher representation of ASD in males; therefore, caution should be applied to extrapolate the findings to females. Furthermore, ASD is characterized by extensive genetic diversity and therefore the findings related to Shank2 mutant mice may not necessarily apply to patients with different gene mutations. Since nociceptive phenotypes in ASD range between hyper- and hypo-sensitivity, diverse mutations may affect the circuit in opposite ways. CONCLUSION: Our findings prove that Shank2 expression identifies a new subset of inhibitory interneurons involved in reducing the transmission of nociceptive stimuli and whose unchecked activation is associated with pain hypersensitivity. We provide evidence that dysfunction in spinal cord pain processing may contribute to the nociceptive phenotypes in ASD.

CLARITY increases sensitivity and specificity of fluorescence immunostaining in long-term archived human brain tissue.

BACKGROUND: Post mortem human brain tissue is an essential resource to study cell types, connectivity as well as subcellular structures down to the molecular setup of the central nervous system especially with respect to the plethora of brain diseases. A key method is immunostaining with fluorescent dyes, which allows high-resolution imaging in three dimensions of multiple structures simultaneously. Although there are large collections of formalin-fixed brains, research is often limited because several conditions arise that complicate the use of human brain tissue for high-resolution fluorescence microscopy. RESULTS: In this study, we developed a clearing approach for immunofluorescence-based analysis of perfusion- and immersion-fixed post mortem human brain tissue, termed human Clear Lipid-exchanged Acrylamide-hybridized Rigid Imaging / Immunostaining / In situ hybridization-compatible Tissue-hYdrogel (hCLARITY). hCLARITY is optimized for specificity by reducing off-target labeling and yields very sensitive stainings in human brain sections allowing for super-resolution microscopy with unprecedented imaging of pre- and postsynaptic compartments. Moreover, hallmarks of Alzheimer's disease were preserved with hCLARITY, and importantly classical 3,3'-diaminobenzidine (DAB) or Nissl stainings are compatible with this protocol. hCLARITY is very versatile as demonstrated by the use of more than 30 well performing antibodies and allows for de- and subsequent re-staining of the same tissue section, which is important for multi-labeling approaches, e.g., in super-resolution microscopy. CONCLUSIONS: Taken together, hCLARITY enables research of the human brain with high sensitivity and down to sub-diffraction resolution. It therefore has enormous potential for the investigation of local morphological changes, e.g., in neurodegenerative diseases.

CSF oligoclonal IgG bands are not associated with ALS progression and prognosis.

Introduction: Amyotrophic Lateral Sclerosis (ALS) is characterized by progressive motoneuron degeneration through cell autonomous and non-cell autonomous mechanisms; and the involvement of the innate and adaptive immune system has been hypothesized based on human and murine model data. We have explored if B-cell activation and IgG responses, as detected by IgG Oligoclonal bands (OCB) in serum and cerebrospinal fluid, were associated with ALS or with a subgroup of patients with distinct clinical features. Methods: IgG OCB were determined in patients affected by ALS (n=457), Alzheimer Disease (n=516), Mild Cognitive Impairment (n=91), Tension-type Headache (n=152) and idiopathic Facial Palsy (n=94). For ALS patients, clinico-demographic and survival data were prospectively collected in the Register Schabia. Results: The prevalence of IgG OCB is comparable in ALS and the four neurological cohorts. When the OCB pattern was considered (highlighting either intrathecal or systemic B-cells activation), no effect of OCB pattern on clinic-demographic parameters and overall. ALS patients with intrathecal IgG synthesis (type 2 and 3) were more likely to display infectious, inflammatory or systemic autoimmune conditions. Discussion: These data suggest that OCB are not related to ALS pathophysiology but rather are a finding possibly indicative a coincidental infectious or inflammatory comorbidity that merits further investigation.

Loss of hypothalamic MCH decreases food intake in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is associated with impaired energy metabolism, including weight loss and decreased appetite which are negatively correlated with survival. Neural mechanisms underlying metabolic impairment in ALS remain unknown. ALS patients and presymptomatic gene carriers have early hypothalamic atrophy. The lateral hypothalamic area (LHA) controls metabolic homeostasis through the secretion of neuropeptides such as orexin/hypocretin and melanin-concentrating hormone (MCH). Here, we show loss of MCH-positive neurons in three mouse models of ALS based on SOD1 or FUS mutations. Supplementation with MCH (1.2 µg/d) through continuous intracerebroventricular delivery led to weight gain in male mutant Sod1G86R mice. MCH supplementation increased food intake, rescued expression of the key appetite-related neuropeptide AgRP (agouti-related protein) and modified respiratory exchange ratio, suggesting increased carbohydrate usage during the inactive phase. Importantly, we document pTDP-43 pathology and neurodegeneration in the LHA of sporadic ALS patients. Neuronal cell loss was associated with pTDP-43-positive inclusions and signs of neurodegeneration in MCH-positive neurons. These results suggest that hypothalamic MCH is lost in ALS and contributes to the metabolic changes, including weight loss and decreased appetite.

Metabolic alterations precede neurofilament changes in presymptomatic ALS gene carriers.

BACKGROUND: The emergence of potentially effective new therapies for genetic forms of amyotrophic lateral sclerosis (ALS) necessitates the identification of biomarkers to facilitate early treatment, prior to the onset of motor symptoms. Here, we sought to investigate whether metabolic alterations are detectable in presymptomatic ALS gene mutation carriers, and whether such alterations precede neurofilament light chain (NfL) changes in serum. METHODS: Between 02/2014 and 11/2021, we prospectively studied 60 presymptomatic ALS gene mutation carriers (40% male, age 48.7 ± 14.9; 28 C9orf72, 22 SOD1, 10 other) compared to 73 individuals from the same families (47% male, age 47.4 ± 12.9) without pathogenic mutations as controls. Bioimpedance analysis (BIA) and indirect calorimetry were performed, and Body Mass Index (BMI), Fat Mass (FM), Body Fat Percentage, Body Water (BW), Lean Body Mass (LBM), Extracellular Mass (ECM), Body Cell Mass (BCM), ECM/BCM ratio, Cells Percentage, Phase Angle, Resting Metabolic Rate (RMR), Metabolic Ratio (MR), and NfL were measured. Participants and evaluators were blinded regarding gene carrier status. FINDINGS: Presymptomatic ALS gene carriers showed reduced LBM (p = 0.02), BCM (p = 0.004), Cells Percentage (p = 0.04), BW (p = 0.02), Phase Angle (p = 0.04), and increased ECM/BCM ratio (p = 0.04), consistently indicating a loss of metabolically active body cells. While in C9orf72 mutation carriers all tissue masses were reduced, only metabolically active tissue was affected in SOD1 mutation carriers. Unexpectedly, RMR (p = 0.009) and MR (p = 0.01) were lower in presymptomatic ALS gene carriers compared to non-carriers. NfL serum levels were similar in mutation carriers and non-carriers (p = 0.60). INTERPRETATION: The observed metabolic phenomena might reflect reduced physical activity and/or preemptive, insufficient compensatory mechanisms to prepare for the later hypermetabolic state. As pre-symptomatic biomarkers we propose ECM/BCM ratio and Phase Angle for SOD1, and a 4-compartment affection in BIA for C9orf72 mutation carriers. FUNDING: This work was an investigator-initiated trial. On the German side, there was no institutional or industrial funding. On the Swedish side, this work was supported by grants from the Swedish Brain Foundation (grants nr. 2013-0279, 2016-0303, 2018-0310, 2020-0353), the Swedish Research Council (grants nr. 2012-3167, 2017-03100), the Knut and Alice Wallenberg Foundation (grants nr. 2012.0091, 2014.0305, 2020.0232), the Ulla-Carin Lindquist Foundation, Umeå University (223-2808-12, 223-1881-13, 2.1.12-1605-14) and the Västerbotten County Council (grants nr 56103-7002829), King Gustaf V:s and Queen Victoria's Freemason's Foundation.

Interleukin-13 and its receptor are synaptic proteins involved in plasticity and neuroprotection.

Immune system molecules are expressed by neurons, yet their functions are often unknown. We have identified IL-13 and its receptor IL-13Ra1 as neuronal, synaptic proteins in mouse, rat, and human brains, whose engagement upregulates the phosphorylation of NMDAR and AMPAR subunits and, in turn, increases synaptic activity and CREB-mediated transcription. We demonstrate that increased IL-13 is a hallmark of traumatic brain injury (TBI) in male mice as well as in two distinct cohorts of human patients. We also provide evidence that IL-13 upregulation protects neurons from excitotoxic death. We show IL-13 upregulation occurring in several cohorts of human brain samples and in cerebrospinal fluid (CSF). Thus, IL-13 is a physiological modulator of synaptic physiology of neuronal origin, with implications for the establishment of synaptic plasticity and the survival of neurons under injury conditions. Furthermore, we suggest that the neuroprotection afforded through the upregulation of IL-13 represents an entry point for interventions in the pathophysiology of TBI.

Integrative genetic analysis illuminates ALS heritability and identifies risk genes.

Amyotrophic lateral sclerosis (ALS) has substantial heritability, in part shared with fronto-temporal dementia (FTD). We show that ALS heritability is enriched in splicing variants and in binding sites of 6 RNA-binding proteins including TDP-43 and FUS. A transcriptome wide association study (TWAS) identified 6 loci associated with ALS, including in NUP50 encoding for the nucleopore basket protein NUP50. Independently, rare variants in NUP50 were associated with ALS risk (P = 3.71.10-03; odds ratio = 3.29; 95%CI, 1.37 to 7.87) in a cohort of 9,390 ALS/FTD patients and 4,594 controls. Cells from one patient carrying a NUP50 frameshift mutation displayed a decreased level of NUP50. Loss of NUP50 leads to death of cultured neurons, and motor defects in Drosophila and zebrafish. Thus, our study identifies alterations in splicing in neurons as critical in ALS and provides genetic evidence linking nuclear pore defects to ALS.

Met/HGFR triggers detrimental reactive microglia in TBI.

The complexity of signaling events and cellular responses unfolding in neuronal, glial, and immune cells upon traumatic brain injury (TBI) constitutes an obstacle in elucidating pathophysiological links and targets for intervention. We use array phosphoproteomics in a murine mild blunt TBI to reconstruct the temporal dynamics of tyrosine-kinase signaling in TBI and then scrutinize the large-scale effects of perturbation of Met/HGFR, VEGFR1, and Btk signaling by small molecules. We show Met/HGFR as a selective modifier of early microglial response and that Met/HGFR blockade prevents the induction of microglial inflammatory mediators, of reactive microglia morphology, and TBI-associated responses in neurons and vasculature. Both acute and prolonged Met/HGFR inhibition ameliorate neuronal survival and motor recovery. Early elevation of HGF itself in the cerebrospinal fluid of TBI patients suggests that this mechanism has translational value in human subjects. Our findings identify Met/HGFR as a modulator of early neuroinflammation in TBI with promising translational potential.

Neuronal nuclear calcium signaling suppression of microglial reactivity is mediated by osteoprotegerin after traumatic brain injury.

BACKGROUND: Traumatic brain injury (TBI) is characterized by massive changes in neuronal excitation, from acute excitotoxicity to chronic hyper- or hypoexcitability. Nuclear calcium signaling pathways are involved in translating changes in synaptic inputs and neuronal activity into discrete transcriptional programs which not only affect neuronal survival and synaptic integrity, but also the crosstalk between neurons and glial cells. Here, we report the effects of blunting neuronal nuclear calcium signals in the context of TBI. METHODS: We used AAV vectors to express the genetically encoded and nuclear-targeted calcium buffer parvalbumin (PV.NLS.mCherry) or the calcium/calmodulin buffer CaMBP4.mCherry in neurons only. Upon TBI, the extent of neuroinflammation, neuronal death and synaptic loss were assessed by immunohistochemistry and targeted transcriptome analysis. Modulation of the overall level of neuronal activity was achieved by PSAM/PSEM chemogenetics targeted to parvalbumin interneurons. The functional impact of neuronal nuclear calcium buffering in TBI was assessed by quantification of spontaneous whisking. RESULTS: Buffering neuronal nuclear calcium unexpectedly resulted in a massive and long-lasting increase in the recruitment of reactive microglia to the injury site, which was characterized by a disease-associated and phagocytic phenotype. This effect was accompanied by a substantial surge in synaptic loss and significantly reduced whisking activity. Transcriptome analysis revealed a complex effect of TBI in the context of neuronal nuclear calcium buffering, with upregulation of complement factors, chemokines and interferon-response genes, as well as the downregulation of synaptic genes and epigenetic regulators compared to control conditions. Notably, nuclear calcium buffering led to a substantial loss in neuronal osteoprotegerin (OPG), whereas stimulation of neuronal firing induced OPG expression. Viral re-expression of OPG resulted in decreased microglial recruitment and synaptic loss. OPG upregulation was also observed in the CSF of human TBI patients, underscoring its translational value. CONCLUSION: Neuronal nuclear calcium signals regulate the degree of microglial recruitment and reactivity upon TBI via, among others, osteoprotegerin signals. Our findings support a model whereby neuronal activity altered after TBI exerts a powerful impact on the neuroinflammatory cascade, which in turn contributes to the overall loss of synapses and functional impairment.

Shank2/3 double knockout-based screening of cortical subregions links the retrosplenial area to the loss of social memory in autism spectrum disorders.

Members of the Shank protein family are master scaffolds of the postsynaptic architecture and mutations within the SHANK genes are causally associated with autism spectrum disorders (ASDs). We generated a Shank2-Shank3 double knockout mouse that is showing severe autism related core symptoms, as well as a broad spectrum of comorbidities. We exploited this animal model to identify cortical brain areas linked to specific autistic traits by locally deleting Shank2 and Shank3 simultaneously. Our screening of 10 cortical subregions revealed that a Shank2/3 deletion within the retrosplenial area severely impairs social memory, a core symptom of ASD. Notably, DREADD-mediated neuronal activation could rescue the social impairment triggered by Shank2/3 depletion. Data indicate that the retrosplenial area has to be added to the list of defined brain regions that contribute to the spectrum of behavioural alterations seen in ASDs.

Neurochemical Monitoring of Traumatic Brain Injury by the Combined Analysis of Plasma Beta-Synuclein, NfL, and GFAP in Polytraumatized Patients.

Traumatic brain injury (TBI) represents a major determining factor of outcome in severely injured patients. However, reliable brain-damage-monitoring markers are still missing. We therefore assessed brain-specific beta-synuclein as a novel blood biomarker of synaptic damage and measured the benchmarks neurofilament light chain (NfL), as a neuroaxonal injury marker, and glial fibrillary acidic protein (GFAP), as an astroglial injury marker, in patients after polytrauma with and without TBI. Compared to healthy volunteers, plasma NfL, beta-synuclein, and GFAP were significantly increased after polytrauma. The markers demonstrated highly distinct time courses, with beta-synuclein and GFAP peaking early and NfL concentrations gradually elevating during the 10-day observation period. Correlation analyses revealed a distinct influence of the extent of extracranial hemorrhage and the severity of head injury on biomarker concentrations. A combined analysis of beta-synuclein and GFAP effectively discriminated between polytrauma patients with and without TBI, despite the comparable severity of injury. Furthermore, we found a good predictive performance for fatal outcome by employing the initial plasma concentrations of NfL, beta-synuclein, and GFAP. Our findings suggest a high diagnostic value of neuronal injury markers reflecting distinct aspects of neuronal injury for the diagnosis of TBI in the complex setting of polytrauma, especially in clinical surroundings with limited imaging opportunities.