Lan X.Y., Liang X.S., Cao M.X., Qin H.M., Chu C.Y., Boltze J., Li S.

The neural cell adhesion molecule (NCAM) promotes neural development and regeneration. Whether NCAM mimetic peptides could synergize with bone marrow mesenchymal stem cells (BMSCs) in stroke treatment deserves investigation. We found that the NCAM mimetic peptide P2 promoted BMSC proliferation, migration, and neurotrophic factor expression, protected neurons from oxygen-glucose deprivation through ERK and PI3K/AKT activation and anti-apoptotic mechanisms in vitro. Following middle cerebral artery occlusion (MCAO) in rats, P2 alone or in combination with BMSCs inhibited neuronal apoptosis and induced the phosphorylation of ERK and AKT. P2 combined with BMSCs enhanced neurotrophic factor expression and BMSC proliferation in the ischemic boundary zone. Moreover, combined P2 and BMSC therapy induced translocation of nuclear factor erythroid 2-related factor, upregulated heme oxygenase-1 expression, reduced infarct volume, and increased functional recovery as compared to monotreatments. Treatment with LY294002 (PI3K inhibitor) and PD98059 (ERK inhibitor) decreased the neuroprotective effects of combined P2 and BMSC therapy in MCAO rats. Collectively, P2 is neuroprotective while P2 and BMSCs work synergistically to improve functional outcomes after ischemic stroke, which may be attributed to mechanisms involving enhanced BMSC proliferation and neurotrophic factor release, anti-apoptosis, and PI3K/AKT and ERK pathways activation.

Journal of Cerebral Blood Flow & Metabolism. January 2024

Jack Butler, Nicholas Dale

Connexin32 (Cx32) is expressed in myelinating Schwann cells. It forms both reflexive gap junctions, to facilitate transfer of molecules from the outer to the inner myelin layers and hemichannels at the paranode to permit action potential-evoked release of ATP into the extracellular space. Loss of function mutations in Cx32 cause X-linked Charcot Marie Tooth disease (CMTX), a slowly developing peripheral neuropathy. The mechanistic links between Cx32 mutations and CMTX are not well understood. As Cx32 hemichannels can be opened by increases in PCO2, we have examined whether CMTX mutations alter this CO2 sensitivity. We have shown that Schwannoma RT4 D6P2T cells can release ATP in response to elevated PCO2 via the opening of Cx32. This is consistent with the hypothesis that the CO2 sensitivity of Cx32 may be important for maintenance of healthy myelin. Our data, showing a transdominant effect of certain CMTX mutations on CO2 sensitivity, may need to be taken into account in any future gene therapies for this condition.

Frontiers in Cellular Neuroscience. December 2023

Mononuclear cell therapy of neonatal hypoxic-ischemic encephalopathy in preclinical versus clinical studies: a systematic analysis of therapeutic efficacy and study design

Scrutton A. M., Ollis F., Boltze J

Hypoxic-ischemic encephalopathy (HIE) is a devastating condition affecting around 8.5 in 1000 newborns globally. Therapeutic hypothermia (TH) can reduce mortality and, to a limited extent, disability after HIE. Nevertheless, there is a need for new and effective treatment strategies. Here, we conducted a systematic review and meta-analysis. and analyzed overall MNC efficacy in preclinical trials, the methodological quality of preclinical trials, and relevant design features in preclinical versus clinical trials. Based on the analyzed data, it is unlikely that therapeutic effect size is massively overestimated in preclinical studies. It is more plausible that the many design differences between preclinical and clinical trials are responsible for the so far lacking proof of the efficacy of MNC treatments in HIE. Additional preclinical and clinical research is required to optimize the application of MNC for experimental HIE treatment.

Neuroprotection. December 2023

MCC950 reduces autophagy and improves cognitive function by inhibiting NLRP3-dependent neuroinflammation in a rat model of Alzheimer's disease

Abdul Naeem, Ravi Prakash, Neha Kumari, Mohsin Ali Khan, Abdul Quaiyoom Khan, Shahab Uddin, Sandeep Verma, Avril AB Robertson, Johannes Boltze, Syed Shadab Raza

In this study, we investigated the potential therapeutic effects of MCC950 on NLRP3-mediated inflammasome-driven inflammation and autophagy in Alzheimer's disease (AD). . MCC950 effectively suppressed STZ-induced cognitive impairment and anxiety by inhibiting NLRP3-dependent neuroinflammation. Moreover, our findings indicate that MCC950 exerts neuroprotective effects by attenuating autophagy in neuronal cells. The inhibiting effects of MCC950 on inflammasome activation and autophagy were reproduced in vitro, provding further mechansistic insights into MCC950 therapeutic action. Our findings suggest that MCC950 impedes the progression of AD and may also improve cognitive function through the mitigation of autophagy and NLRP3 inflammasome.

Brain, Behavior and Immunity. December 2023

Amol M Bhandare, Nicholas Dale

While central autonomic, cardiac, and/or respiratory dysfunction underlies sudden unexpected death in epilepsy (SUDEP), the specific neural mechanisms that lead to SUDEP remain to be determined. In this study, we took advantage of single-cell neuronal Ca2+ imaging and intrahippocampal kainic acid (KA)-induced chronic epilepsy in mice to investigate progressive changes in key cardiorespiratory brainstem circuits during chronic epilepsy. Our findings establish a dysfunctional breathing phenotype with its RTN neuronal correlate in mice with chronic epilepsy and suggest that the assessment of respiratory chemosensitivity may have the potential for identifying people at risk of SUDEP.

Frontiers in Cellular Neuroscience. December 2023

Taguchi A., Okinaka Y., Takeda A., Okamoto T., Boltze J., Claussen C., Gul S

It is proposed that age-related brain dysfunction may not necessarily result from the accumulation of uncontrollable disorders, but rather the natural deterioration of brain function following expiration of the limited innate program to preserve the brain in a healthy condition. We now have identified a means by which this process could potentially be mitigated or even partially reversed by applying stem cell therapy. Furthermore, we propose that the activation of neurogenesis in the hippocampus, also through stem cell therapy, is a promising therapeutic target in AD.

Neuroprotection. November 2023

T. Bertie Ansell, Wanling Song, Claire E. Coupland, Loic Carrique, Robin A. Corey, Anna L. Duncan, C. Keith Cassidy, Maxwell M. G. Geurts, Tim Rasmussen, Andrew B. Ward, Christian Siebold, Phillip J. Stansfeld, Mark S. P. Sansom

Cryo-electron microscopy (cryo-EM) enables the determination of membrane protein structures in native-like environments. Characterising how membrane proteins interact with the surrounding membrane lipid environment is assisted by resolution of lipid-like densities visible in cryo-EM maps. Nevertheless, establishing the molecular identity of putative lipid and/or detergent densities remains challenging. Here we present LipIDens, a pipeline for molecular dynamics (MD) simulation-assisted interpretation of lipid and lipid-like densities in cryo-EM structures.

Nature Communications. November 2023

Reno Roberts, Robert T.R. Huckstepp

Sleep apnea (SA) is a major threat to physical health and carries a significant economic burden. These impacts are worsened by its interaction with, and induction of, its comorbidities. SA holds a bidirectional relationship with hypertension, which drives atherosclerosis/arteriolosclerosis, ultimately culminating in vascular dementia. To enable a better understanding of these sequelae of events, we investigated innate SA and its effects on cognition in adult-aged spontaneously hypertensive rats, which have a range of cardiovascular disorders. Spontaneously hypertensive rats displayed a higher degree of sleep-disordered breathing, which emanates from poor vascular health leading to a loss of preBötzinger Complex neurons. These rats also display small vessel white matter disease, a form of vascular dementia, which may be exacerbated by the SA-induced neuroinflammation in the hippocampus to worsen the related deficits in both long- and short-term memories.

Stroke. November 2023

Tang T., Li D., Fan T.P., Guo L.J., Lan X.Y., Bi C.J., Boltze J., Thomas A.M., Zhao X.S., Mo M., Zhao M.H., Ji X., Li S

Timely recognition of futile recanalization might enable a prompter response and thus improve outcomes in patients receiving successful thrombectomy. This study aims to evaluate whether postoperative fibrinogen-to-albumin ratio (FAR) could act as an indicator of futile recanalization.This is a single-center, retrospective analysis of patients with acute anterior circulation large-vessel occlusion and successful thrombectomy between May 2019 and June 2022. A total of 255 patients were enrolled, amongst which 34.1% had high postoperative FAR. Futile recanalization was more prevalent among patients with high FAR compared to those with low FAR. After adjusting for potential confounders, high postoperative FAR was found to independently correspond with the occurrence of futile. This association was consistently observed regardless of prior antithrombotic therapy, treatment of intravenous thrombolysis, occlusion site, time from symptom onset to groin puncture, and reperfusion status. Our findings support high postoperative FAR serving as an indicator of futile recanalization in patients with anterior circulation large-vessel occlusion and successful thrombectomy.

Brain & Behavior. November 2023

Patrick Becker, Fiona B. Naughton, Deborah H. Brotherton, Raul Pacheco-Gomez, Oliver Beckstein, Alexander D. Cameron

The bile acid sodium symporter (BASS) family transports a wide array of molecules across membranes, including bile acids in humans, and small metabolites in plants. These transporters, many of which are sodium-coupled, have been shown to use an elevator mechanism of transport, but exactly how substrate binding is coupled to sodium ion binding and transport is not clear. Here, we solve the crystal structure at 2.3 Å of a transporter from Neisseria meningitidis (ASBTNM) in complex with pantoate, a potential substrate of ASBTNM.. Comparison of structures in the presence and absence of pantoate demonstrates that pantoate elicits a conformational change in one of the cross-over helices. This modifies the interface between the two domains that move relative to one another to elicit the elevator mechanism. These results have implications, not only for ASBTNM but for the BASS family as a whole and indeed other transporters that work through the elevator mechanism.

eLife. November 2023

Yiying Yang, Haoxiang Chen, Robin A. Corey, Violette Morales, Yves Quentin, Carine Froment, Anne Caumont-Sarcos, Cécile Albenne, Odile Burlet-Schiltz, David Ranava, Phillip J. Stansfeld, Julien Marcoux, Raffaele Ieva

Insertion of lipopolysaccharide (LPS) into the bacterial outer membrane (OM) is mediated by a druggable OM translocon consisting of a β-barrel membrane protein, LptD, and a lipoprotein, LptE. The β-barrel assembly machinery (BAM) assembles LptD together with LptE at the OM. In the enterobacterium Escherichia coli, formation of two native disulfide bonds in LptD controls translocon activation. Here we report the discovery of LptM (formerly YifL), a lipoprotein conserved in Enterobacteriaceae, that assembles together with LptD and LptE at the BAM complex.. Our results suggest that, by mimicking LPS binding, LptM facilitates oxidative maturation of LptD, thereby activating the LPS translocon.

Nature Communications. October 2023

Haley, Maisy, Bertrand, Jeanri, Anderson, Vanessa Torrico, Fuad, Mukattar, Frenguelli, Bruno G., Corrêa, Sônia A. L. and Wall, Mark J.

Expression of the immediate early gene Arc/Arg3.1 (Arc), a key mediator of synaptic plasticity, is enhanced by neural activity and then reduced by proteasome-dependent degradation. We have previously shown that disruption of Arc degradation, in an Arc knock-in mouse (ArcKR), where the predominant Arc ubiquitination sites were mutated, reduced the threshold to induce, and also enhanced, the strength of Group I metabotropic glutamate receptor-mediated long- term depression (DHPG-LTD). Here we have investigated if ArcKR expression changes long- term potentiation (LTP) in CA1 area of the hippocampus. Our findings support the hypothesis that Arc ubiquitination supports the induction and expression of LTP, likely via limiting Arc-dependent removal of AMPA receptors at synapses.

European Journal of Neuroscience. October 2023

CK Cassidy, Zhuan Qin, Thomas Frosio, Khoosheh Gosink, Zhengyi Yang, Mark Sansom, Phillip Stansfeld, John Parkinson, and Peijun Zhang

The sensory apparatus of the chemotaxis pathway is an array of core-signaling units (CSUs) composed of transmembrane chemoreceptors, the histidine kinase CheA and an adaptor protein, CheW. Although chemotaxis pathways represent the best understood signaling systems, a detailed mechanistic understanding of signal transduction has been hindered by the lack of a complete structural picture of the CSU and extended array. In this study, we present the structure of the complete CSU from phage ϕX174 E protein lysed Escherichia coli cells, determined using cryo-electron tomography and sub-tomogram averaging to 12-Å resolution. Our results provide new insight into previously poorly-resolved regions of the complex and offer a structural basis for designing new experiments to test mechanistic hypotheses.

mBio. September 2023

Chatzichristofi, Agathangelos, Sagris, Vasileios, Pallaris, Aristos, Eftychiou, Marios, Kalvari, Ioanna, Price, Nicholas, Theodosiou, Theodosios, Iliopoulos, Ioannis, Nezis, Ioannis P. and Promponas, Vasilis J

Several selective macroautophagy receptor and adaptor proteins bind members of the Atg8 (autophagy related 8) family using short linear motifs (SLiMs), most often referred to as Atg8-family interacting motifs (AIMs) or LC3-interacting regions (LIRs). AIM/LIR motifs have been extensively studied during the last fifteen years, since they can uncover the underlying biological mechanisms and possible substrates for this key catabolic process of eukaryotic cells. Prompted by the fact that experimental information regarding LIR motifs can be found scattered across heterogeneous literature resources, we have developed LIRcentral (https://lircentral.euLink opens in a new window), a freely available online repository for user-friendly access to comprehensive, high-quality information regarding LIR motifs from manually curated publications. Herein, we describe the development of LIRcentral and showcase currently available data and features, along with our plans for the expansion of this resource.

Autophagy. August 2023

Björn Nitzsche, Sabine Schulze, Johannes Boltze, Martin J. Schmidt

Pathomorphological alterations of the central nervous system in dogs, such as syringomyelia and Chiari-like malformation, can cause cranial and cervical hyperesthesia and neuropathic pain. The long-term activity of the pain network can induce functional alteration and eventually even morphological changes in the pain network. This may happen especially in the prefrontal and cingulate cortex, where atrophy of the gray matter (GM) was observed in humans with chronic pain, irrespective of the nature of the pain syndrome. We tested the hypothesis that Cavalier King Charles Spaniels (CKCS) with Chiari-like malformation and associated syringomyelia (SM) and pain show cerebral morphological differences compared to animals without signs of syringomyelia and pain. We found that GM atrophy in the CG is associated with chronic pain and thus may serve as an objective readout parameter for the diagnosis or treatment of canine pain syndromes.

Frontiers in Neuroanatomy. July 2023

Monica Garcia-Durillo and Bruno. G. Frenguelli  

Approximately 30% of patients with status epilepticus (SE) become refractory to two or more antiseizure medications (ASM). There is thus a real need to identify novel targets to develop new ASMs for treating this clinical emergency. This study evaluated the effect of the selective P2X7R antagonist A740003 on acute seizures in the dentate gyrus (DG) of hippocampal brain slices, where P2X7Rs are highly expressed, with a view to establishing its potential use as a therapy or adjunct with lorazepam (LZP) in refractory SE.. Our study revealed that, in the absence of changes in mRNA for P2X7Rs or inflammatory markers, P2X7R antagonism did not alter the frequency of SLEs. However, A740003 in conjunction with LZP delayed the onset of seizures. Furthermore, our results support the need for employing LZP before seizures become refractory during SE (i.e., in the 60 min frame since first seizure appears) as delayed of application LZP increased seizure frequency. These studies reveal possible sites of intervention that could have a positive impact in patients with high risk of suffering SE or its drug-refractory variant.

Neuropharmacology. July 2023

Everett, James, Brooks, Jake, Lermyte, Frederik, Tjendana Tjhin, Vindy, Hands-Portman, Ian, Hill, Emily, Collingwood, Joanna F. and Telling, Neil D.

The synchrotron x-ray spectromicroscopy technique Scanning Transmission X-ray Microscopy (STXM) offers a powerful means to examine the underlying biochemistry of biological systems, owing to its combined chemical sensitivity and nanoscale spatial resolution. Here we introduce and demonstrate methodology for the use of STXM to examine the biochemistry of the human brain. We then discuss how this approach can help us better understand the biochemical changes that occur during the development of degenerative brain disorders, potentially facilitating the development of new therapies for disease diagnosis and treatment.

Journal of Electron Spectroscopy and Related Phenomena

Jessica Brown, Elena Camporesi, Juan Lantero-Rodriguez, Maria Olsson, Alice Wang, Blanca Medem, Henrik Zetterberg, Kaj Blennow, Thomas K. Karikari, Mark Wall and Emily Hill

Alzheimer’s disease (AD) and other tauopathies are characterized by the aggregation of tau into soluble and insoluble forms (including tangles and neuropil threads). In humans, a fraction of both phosphorylated and non-phosphorylated N-terminal to mid-domain tau species, are secreted into cerebrospinal fluid (CSF). Some of these CSF tau species can be measured as diagnostic and prognostic biomarkers, starting from early stages of disease. Here, we have developed and applied a novel approach to examine the electrophysiological effects of CSF from patients with a tau-positive biomarker profile. We demonstrate that CSF-tau mediates an increase in neuronal excitability in single cells. We then observed, at the network level, increased input–output responses and enhanced paired-pulse facilitation as well as an increase in long-term potentiation. Finally, we show that CSF-tau modifies the generation and maintenance of hippocampal theta oscillations, which have important roles in learning and memory and are known to be altered in AD patients. Together, we describe a novel method for screening human CSF-tau to understand functional effects on neuron and network activity, which could have far-reaching benefits in understanding tau pathology, thus allowing for the development of better targeted treatments for tauopathies in the future.

Acta Neuropathologica Communications. April 2023