Oksana Dmytriyeva

BACKGROUND: Metabolic and neurovascular disturbances contribute to brain injury after birth asphyxia. We previously showed that plasma feeding attenuated neuropathology after transient umbilical cord occlusion in piglets. This study explored the metabolic and molecular consequences of birth asphyxia and whether plasma feeding preserves metabolic homeostasis and brain barrier integrity. METHODS: Piglets (n=89) delivered by cesarean section on gestational day 113 underwent umbilical cord occlusion (asphyxia [ASP]) or remained nonasphyxiated (control [CON]). ASP and CON piglets were randomly assigned to receive formula reconstituted with either water (vehicle-treated group) or sow plasma (plasma-treated group). Animals were euthanized at 1 hour, 24 hours, or day 4 after insult. Cerebrospinal fluid metabolites were profiled by untargeted liquid chromatography–mass spectrometry metabolomics at 24 hours. Expression of metabolite transporters and structural components of the blood-brain barrier in the caudate nucleus and the blood–cerebrospinal fluid barrier at the choroid plexus was assessed by reverse transcription quantitative polymerase chain reaction and Western blotting. The CSF/plasma Na ⁺ ratio was assessed, and cell-specific AQP4 expression was confirmed with RNAscope. Data were analyzed using linear and linear mixed-effects models. RESULTS: Birth asphyxia dysregulated the CSF metabolic profile, with reductions in multiple metabolites and increases in a smaller subset, consistent with impaired amino acid and lipid metabolism. This was accompanied by reduced expression of substrate transporters, including xCT , LAT1 , ASCT2 , FATP1 , CAV1 , and MCTs . In the caudate nucleus, expression of blood-brain barrier structural proteins and ion transporters, including Na ⁺ /K ⁺ -ATPase, was reduced, whereas the choroid plexus blood-CSF barrier remained largely preserved. Plasma feeding partially restored transporter expression at both brain interfaces and increased AQP4 and ion transporter expression at the blood-brain barrier by day 4. Increased VE-cadherin (vascular endothelial cadherin) and ZO-1 (zonula occludens-1) expression and elevated CSF Na ⁺ concentrations suggested early modulation of the integrity of the 2 brain barriers. CONCLUSIONS: Plasma feeding preserves metabolic homeostasis and supports brain barrier integrity after birth asphyxia, highlighting plasma-derived factors as potential therapeutic targets to reduce neurodevelopmental impairment after perinatal asphyxia.

Optogenetic stimulation of the rostral pedunculotegmental nucleus (PTg) induces global motor arrest, but it remains unclear whether this is merely a suppression of motor activity or a broader disruption of brain processes required to guide action. We developed a visuospatial cue task for rats, to test if sensory information presented during PTg-induced arrest can guide laterresponses. Here, we show that optogenetic stimulation during cue presentation reduces accuracy to chance level. By moving stimulation to only before or only after the cue, we found that performance was only affected when stimulation and cue presentation overlapped, that rats recover cue-guided behavior almost immediately at the end of stimulation, and that stimulation does not appear to abolish responses based on cue information acquired before arrest. These findings indicate that stimulation of the rostral PTg does not only pause motoroutput but transiently disrupts the ability to process and use cue information effectively.

Weight loss is a potentially deadly hallmark of many cancers, including lung cancer. In particular, the loss of skeletal muscle mass and function impairs survival and lowers quality of life. Despite being a major determinant of prognosis, the molecular drivers of muscle wasting remain ill-defined. Therefore, there is a critical need for human molecular data to support the development of effective therapies for this currently untreatable condition. Here, we utilize cutting-edge proteomics technology to longitudinally map the proteome and phosphoproteome of skeletal muscle from patients with newly diagnosed, advanced-stage non-small cell lung cancer during their treatment. Leveraging deep in vivo clinical phenotyping of activity, body composition, muscle quality, and nutritional risk, we identified 118/174 muscle proteins/phospho-sites associated with cachexia at diagnosis with indications of sexual dimorphism. Treatment altered 278 proteins and 1,155 phospho-sites, of which 137/91 proteins/phospho-sites were associated with muscle wasting. Our findings highlight disrupted calcium, anabolic, and stress signalling, alongside extracellular matrix and mitochondrial alterations, as key molecular features of cachexia in non-small cell lung cancer. These clinically anchored proteomic and phosphoproteomic signatures provide potential targets for future research.

Alzheimer’s disease (AD) is a progressive and irreversible neurodegenerative disease characterized by the accumulation of aggregated amyloid beta (Aβ) and hyperphosphorylated tau along with a slow decline in cognitive functions. Unlike advanced AD, the initial steps of AD pathophysiology have been poorly investigated, partially due to limited availability of animal models focused on the early, plaque-free stages of the disease. The aim of this study was to evaluate the early behavioral, anatomical and molecular alterations in wild-type rats following intracerebroventricular injections of human Aβ oligomers (AβOs). Bioactive human AD and nondemented control brain tissue extracts were characterized using ELISA and proteomics approaches. Following a bilateral infusion, rats underwent behavioral testing, including the elevated plus maze, social recognition test, Morris water maze and Y-maze within 6 weeks postinjection. An analysis of brain structure was performed with manganese-enhanced MRI. Collected brain tissues were analyzed using stereology, immunohistochemistry, ELISA and qPCR. No sensorimotor deficits affecting motor performance on different maze tasks were observed, nor was spatial memory disturbed in AD rats. In contrast, a significant impairment of social memory became evident at 21 days postinjection. This deficit was associated with a significantly decreased volume of the lateral entorhinal cortex and a tendency toward a decrease in the total brain volume. Significant increase of cleaved caspase-3-positive cells, microglial activation and proinflammatory responses accompanied by altered expression of synaptic markers were observed in the hippocampus of AD rats with immunohistochemical and qPCR approaches at 6 weeks postinjection. Our data suggest that the social memory impairment observed in AβO-injected rats might be determined by neuroinflammatory responses and synaptopathy. An infusion of native oligomeric Aβ in the rat brain represents a feasible tool to model early plaque-free events associated with AD.

Vascular endothelial growth factor B (VEGFB) is a pleiotropic trophic factor which, in contrast to the closely related VEGFA, is known to have a limited effect on angiogenesis. VEGFB improves survival in various tissues including the nervous system, where the effect was observed mainly for peripheral neurons. The neurotrophic effect of VEGFB on central nervous system neurons has been less investigated. Here we demonstrated that VEGFB promotes neurite outgrowth from primary cerebellar granule, hippocampal and retinal neurons in vitro. VEGFB protected hippocampal and retinal neurons from both oxidative stress and glutamate-induced neuronal death. The VEGF receptor 1 (VEGFR1) is required for VEGFB-induced neurotrophic and neuroprotective effects. Using a structure-based approach, we designed short peptides, termed Vefins1–7, mimicking the binding interface of VEGFB to VEGFR1. Vefins were analyzed for their secondary structure and binding to VEGF receptors and compared with previously described peptides derived from VEGFA, another ligand of VEGFR1. We show that Vefins have neurotrophic and neuroprotective effects on primary hippocampal, cerebellar granule and retinal neurons in vitro with potencies comparable to VEGFB. Similar to VEGFB, Vefins were not mitogenic for MCF-7 cancer cells. Furthermore, one of the peptides, Vefin7, dose-dependently even inhibited the proliferation of MCF-7 cells in vitro. Unraveling the neurotrophic and neuroprotective potentials of VEGFB, the only non-angiogenic factor of the VEGF family, is promising for the development of neuroprotective peptide-based therapies.

Cell therapy raises hopes high for better treatment of brain disorders. However, the majority of transplanted cells often die soon after transplantation, and those that survive initially continue to die in the subacute phase, diminishing the impact of transplantations. In this study, we genetically modified transplanted human neural stem cells (hNSCs), from 2 distant embryonic stem cell lines (H9 and RC17), to express 1 of 4 prosurvival factors — Hif1a, Akt1, Bcl-2, or Bcl-xl — and studied how these modifications improve short- and long-term survival of transplanted hNSCs. All genetic modifications dramatically increased survival of the transplanted hNSCs. Importantly, 3 out of 4 modifications also enhanced the exit of hNSCs from the cell cycle, thus avoiding aberrant growth of the transplants. Bcl-xl expression provided the strongest protection of transplanted cells, reducing both immediate and delayed cell death, and stimulated hNSC differentiation toward neuronal and oligodendroglial lineages. By designing hNSCs with drug-controlled expression of Bcl-xl, we demonstrated that short-term expression of a prosurvival factor can ensure the long-term survival of transplanted cells. Importantly, transplantation of Bcl-xl–expressing hNSCs into mice suffering from stroke improved behavioral outcome and recovery of motor activity in mice.

Understanding the mechanisms of neurodegeneration is crucial for development of therapies to treat neurological disorders. S100 proteins are extensively expressed in the injured brain but S100's role and signalling in neural cells remain elusive. We recently demonstrated that the S100A4 protein protects neurons in brain injury and designed S100A4-derived peptides mimicking its beneficial effects. Here we show that neuroprotection by S100A4 involves the growth factor family receptor ErbB4 and its ligand Neuregulin 1 (NRG), key regulators of neuronal plasticity and implicated in multiple brain pathologies. The neuroprotective effect of S100A4 depends on ErbB4 expression and the ErbB4 signalling partners ErbB2/Akt, and is reduced by functional blockade of NRG/ErbB4 in cell models of neurodegeneration. We also detect binding of S100A4 with ErbB1 (EGFR) and ErbB3. S100A4-derived peptides interact with, and signal through ErbB, are neuroprotective in primary and immortalized dopaminergic neurons, and do not affect cell proliferation/motility - features which make them promising as potential neuroprotectants. Our data suggest that the S100-ErbB axis may be an important mechanism regulating neuronal survival and plasticity.

Synaptic cell adhesion molecules represent important targets for neuronal activity-dependent proteolysis. Postsynaptic neuroligins (NLs) form trans-synaptic complexes with presynaptic neurexins (NXs). Both NXs and NLs are cleaved from the cell surface by metalloproteases in an activity-dependent manner, releasing a soluble extracellular fragment and membrane-tethered C-terminal fragment. The cleavage of NL1 depresses synaptic transmission, but the mechanism by which this occurs is unknown. Metabotropic glutamate receptor 2 (mGluR2) are located primarily at the periphery of presynaptic terminals, where they inhibit the formation of cyclic adenosine monophosphate (cAMP) and consequently suppress the release of glutamate and decrease synaptic transmission. In the present study, we found that the soluble ectodomain of NL1 binds to and activates mGluR2 in both neurons and heterologous cells, resulting in a decrease in cAMP formation. In a slice preparation from the hippocampus of mice, NL1 inhibited the release of glutamate from mossy fibers that project to CA3 pyramidal neurons. The presynaptic effect of NL1 was abolished in the presence of a selective antagonist for mGluR2. Thus, our data suggest that the soluble extracellular domain of NL1 functionally interacts with mGluR2 and thereby decreases synaptic strength.