The Neuronal Ischemic Tolerance Is Conditioned by the Tp53 Arg72Pro Polymorphism

1,25-D3 ameliorates ischemic brain injury by alleviating endoplasmic reticulum stress and ferroptosis: Involvement of vitamin D receptor and p53 signaling

Endoplasmic reticulum stress (ERS) and ferroptosis are linked to cerebral ischemia reperfusion injury (CIRI). The neuroprotective properties of 1α, 25-dihydroxyvitamin D3 (VitD3 or 1,25-D3) have been well established; however, the mechanism by which VitD3 treats CIRI through ERS and ferroptosis has not been examined. Hence, we developed middle cerebral artery occlusion/reperfusion (MCAO/R) model in SD rats to ascertain if VitD3 preconditioning mediates ERS and ferroptosis involving of p53 signaling. In this study, we observed that VitD3 can reduce infarction volume and cerebral edema, which leads to the improvement of nerve function. HE, Nissl and Tunel staining showed that VitD3 treatment significantly improved the morphology of neuronal cells and reduced their death. The expression and activation of Vitamin D receptor (VDR), PKR-like ER kinase (PERK), C/EBP-homologous protein (CHOP), p53, nuclear factor erythroid 2-related factor 2 (Nrf2), glutathione peroxidase 4 (GPX4) and reactive oxygen species (ROS) in the ischemic penumbral area were detected by real-time qPCR, Western-blotting and Elisa. The results showed that after VitD3 treatment, VDR increased, ERS-related indices (PERK, CHOP) significantly decreased and ferroptosis-related indices (Nrf2, GPX4) increased. As a VDRs antagonist, pyridoxal-5-phosphate (P5P) can partially block the neuroprotective effects of VitD3. Therefore, CIRI can induce ERS and ferroptosis in the ischemic penumbra area and VitD3 may ameliorate nerve damage in CIRI rats by up-regulating VDR, alleviating p53-associated ERS and ferroptosis.

Brain Ischemic Tolerance Triggered by Preconditioning Involves Modulation of Tumor Necrosis Factor-α-Stimulated Gene 6 (TSG-6) in Mice Subjected to Transient Middle Cerebral Artery Occlusion

Ischemic preconditioning (PC) induced by a sub-lethal cerebral insult triggers brain tolerance against a subsequent severe injury through diverse mechanisms, including the modulation of the immune system. Tumor necrosis factor (TNF)-α-stimulated gene 6 (TSG-6), a hyaluronate (HA)-binding protein, has recently been involved in the regulation of the neuroimmune response following ischemic stroke. Thus, we aimed at assessing whether the neuroprotective effects of ischemic PC involve the modulation of TSG-6 in a murine model of transient middle cerebral artery occlusion (MCAo). The expression of TSG-6 was significantly elevated in the ischemic cortex of mice subjected to 1 h MCAo followed by 24 h reperfusion, while this effect was further potentiated (p < 0.05 vs. MCAo) by pre-exposure to ischemic PC (i.e., 15 min MCAo) 72 h before. By immunofluorescence analysis, we detected TSG-6 expression mainly in astrocytes and myeloid cells populating the lesioned cerebral cortex, with a more intense signal in tissue from mice pre-exposed to ischemic PC. By contrast, levels of TSG-6 were reduced after 24 h of reperfusion in plasma (p < 0.05 vs. SHAM), but were dramatically elevated when severe ischemia (1 h MCAo) was preceded by ischemic PC (p < 0.001 vs. MCAo) that also resulted in significant neuroprotection. In conclusion, our data demonstrate that neuroprotection exerted by ischemic PC is associated with the elevation of TSG-6 protein levels both in the brain and in plasma, further underscoring the beneficial effects of this endogenous modulator of the immune system.

Research hotspots and frontiers of preconditioning in cerebral ischemia: A bibliometric analysis

Background

Preconditioning is a promising strategy against ischemic brain injury, and numerous studies in vitro and in vivo have demonstrated its neuroprotective effects. However, at present there is no bibliometric analysis of preconditioning in cerebral ischemia. Therefore, a comprehensive overview of the current status, hot spots, and emerging trends in this research field is necessary.

Materials and methods

Studies on preconditioning in cerebral ischemia from January 1999-December 2022 were retrieved from the Web of Science Core Collection (WOSCC) database. CiteSpace was used for data mining and visual analysis.

Results

A total of 1738 papers on preconditioning in cerebral ischemia were included in the study. The annual publications showed an upwards and then downwards trend but currently remain high in terms of annual publications. The US was the leading country, followed by China, the most active country in recent years. Capital Medical University published the largest number of articles. Perez-Pinzon, Miguel A contributed the most publications, while KITAGAWA K was the most cited author. The focus of the study covered three areas: (1) relevant diseases and experimental models, (2) types of preconditioning and stimuli, and (3) mechanisms of ischemic tolerance. Remote ischemic preconditioning, preconditioning of mesenchymal stem cells (MSCs), and inflammation are the frontiers of research in this field.

Conclusion

Our study provides a visual and scientific overview of research on preconditioning in cerebral ischemia, providing valuable information and new directions for researchers.

Integrating network pharmacology and pharmacological evaluation to explore the protective mechanism of Ershiwuwei Zhenzhu pill in ischemic stroke

ETHNOPHARMACOLOGICAL RELEVANCE

Ershiwuwei Zhenzhu Pill (EZP), a representative and classic formula in Tibetan medicine, is commonly used in the treatment of various cerebrovascular diseases, including ischemic stroke (IS). Nevertheless, their efficacy and potential mechanism in treating IS have yet to be investigated.

AIM OF THE STUDY

This study aimed to investigate the potential mechanisms of EZP in the treatment of IS based on network pharmacology and experimental verification.

MATERIALS AND METHODS

The chemical profile of EZP was characterized using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). The targets related to the compounds in EZP were predicted by the Swiss Target Prediction and Target Net platform, and targets of IS were collected from the Gene Cards and OMIM databases. Subsequently, a protein-protein interaction (PPI) network of targets was constructed and analyzed by the STRING database and Cytoscape software, version 3.7.1. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed, and an ingredient-target-pathway network was constructed. Ultimately, the middle cerebral artery occlusion (MCAO) model was established to evaluate the anti-IS effects of EZP by detecting the neurological deficit score, HE, Nissl and TCC staining, and inflammatory factors, and the expression of key protein targets was detected by western blotting.

RESULTS

A total of 129 components were identified in EZP. Network pharmacology revealed 3136 compound targets and 2826 disease-related targets, and 412 overlapping proteins were obtained as potential therapeutic targets. The PPI network results showed that 6 key targets (AKT1, SRC, VEGFA, TP53, TNF and EGFR) were core targets of EZP in the treatment of IS. Western blotting demonstrated that the expression levels of AKT1, VEGFA, TP53, SRC, TNF and EGFR in the brain tissue of MCAO rats were significantly changed after treatment with EZP compared to the model group.

CONCLUSIONS

EZP ameliorated IS in MCAO rats. The underlying mechanism might be associated with inhibiting inflammation and apoptosis, promoting angiogenesis and protecting neurons by regulating multiple targets and pathways.

Ischemic Preconditioning Modulates the Peripheral Innate Immune System to Promote Anti-Inflammatory and Protective Responses in Mice Subjected to Focal Cerebral Ischemia

The development of tolerance triggered by a sublethal ischemic episode (preconditioning, PC) involves a complex crosstalk between neurons, astrocytes and microglia, although the role of the peripheral immune system in this context is largely unexplored. Here, we report that severe cerebral ischemia caused by transient middle cerebral artery occlusion (MCAo) in adult male mice elevates blood counts of inflammatory neutrophils and monocytes, and plasma levels of miRNA-329-5p. These inflammatory responses are prevented by ischemic PC induced by 15 min MCAo, 72h before the severe insult (1h MCAo). As compared with sham-operated animals, mice subjected to either ischemic PC, MCAo or a combination of both (PC+MCAo) display spleen contraction. However, protein levels of Ym1 (a marker of polarization of myeloid cells towards M2/N2 protective phenotypes) are elevated only in spleen from the experimental groups PC and PC+MCAo, but not MCAo. Conversely, Ym1 protein levels only increase in circulating leukocytes from mice subjected to 1h MCAo, but not in preconditioned animals, which is coincident with a dramatic elevation of Ym1 expression in the ipsilateral cortex. By immunofluorescence analysis, we observe that expression of Ym1 occurs in amoeboid-shaped myeloid cells, mainly representing inflammatory monocytes/macrophages and neutrophils. As a result of its immune-regulatory functions, ischemic PC prevents elevation of mRNA levels of the pro-inflammatory cytokine interleukin (IL)-1β in the ipsilateral cortex, while not affecting IL-10 mRNA increase induced by MCAo. Overall, the elevated anti-inflammatory/pro-inflammatory ratio observed in the brain of mice pre-exposed to PC is associated with reduced brain infarct volume and ischemic edema, and with amelioration of functional outcome. These findings reaffirm the crucial and dualistic role of the innate immune system in ischemic stroke pathobiology, extending these concepts to the context of ischemic tolerance and underscoring their relevance for the identification of novel therapeutic targets for effective stroke treatment.

Is Immune Suppression Involved in the Ischemic Stroke? A Study Based on Computational Biology

OBJECTIVE

To identify the genetic mechanisms of immunosuppression-related genes implicated in ischemic stroke.

BACKGROUND

A better understanding of immune-related genes (IGs) involved in the pathophysiology of ischemic stroke may help identify drug targets beneficial for immunomodulatory approaches and reducing stroke-induced immunosuppression complications.

METHODS

Two datasets related to ischemic stroke were downloaded from the GEO database. Immunosuppression-associated genes were obtained from three databases (i.e., DisGeNET, HisgAtlas, and Drugbank). The CIBERSORT algorithm was used to calculate the mean proportions of 22 immune-infiltrating cells in the stroke samples. Differential gene expression analysis was performed to identify the differentially expressed genes (DEGs) involved in stroke. Immunosuppression-related crosstalk genes were identified as the overlapping genes between ischemic stroke-DEGs and IGs. Feature selection was performed using the Boruta algorithm and a classifier model was constructed to evaluate the prediction accuracy of the obtained immunosuppression-related crosstalk genes. Functional enrichment analysis, gene-transcriptional factor and gene-drug interaction networks were constructed.

RESULTS

Twenty two immune cell subsets were identified in stroke, where resting CD4 T memory cells were significantly downregulated while M0 macrophages were significantly upregulated. By overlapping the 54 crosstalk genes obtained by feature selection with ischemic stroke-related genes obtained from the DisGenet database, 17 potentially most valuable immunosuppression-related crosstalk genes were obtained, ARG1, CD36, FCN1, GRN, IL7R, JAK2, MAFB, MMP9, PTEN, STAT3, STAT5A, THBS1, TLR2, TLR4, TLR7, TNFSF10, and VASP. Regulatory transcriptional factors targeting key immunosuppression-related crosstalk genes in stroke included STAT3, SPI1, CEPBD, SP1, TP53, NFIL3, STAT1, HIF1A, and JUN. In addition, signaling pathways enriched by the crosstalk genes, including PD-L1 expression and PD-1 checkpoint pathway, NF-kappa B signaling, IL-17 signaling, TNF signaling, and NOD-like receptor signaling, were also identified.

CONCLUSION

Putative crosstalk genes that link immunosuppression and ischemic stroke were identified using bioinformatics analysis and machine learning approaches. These may be regarded as potential therapeutic targets for ischemic stroke.

Preconditioning With Intermittent Hypobaric Hypoxia Attenuates Stroke Damage and Modulates Endocytosis in Residual Neurons

Background: Moderate hypobaric hypoxia induces cerebral ischemic tolerance. We investigated the optimal method for applying hypobaric hypoxia preconditioning at 5,000 m to ischemic brain tissue and combined it with proteomics to determine the mechanisms underlying this effect. Methods: Male SD rats were randomly grouped as S (sham, n = 20), M (middle cerebral artery occlusion [MCAO], n = 28), H2M (intermittent hypobaric hypoxia preconditioned MCAO group, 2 h/day, 10 days, n = 20), H6M (intermittent hypobaric hypoxia preconditioned MCAO group, 6 h/day, 10 days, n = 28), and HpM (persistent hypobaric hypoxia preconditioned MCAO group, 10 days, n = 28). The permanent MCAO model was established based on the Zea Longa method. Infarction was assessed with the modified neurological severity score (mNSS) and 2,3,5-triphenyl tetrazolium chloride staining. The total protein expression of the neuron-specific nuclear protein (NeuN), cysteinyl aspartate specific proteinase 3 (caspase-3), cleaved-caspase-3, and interleukin 6 (IL-6) was determined using western blotting. We assessed the peri-infarct cortex's ultrastructural changes. A label-free proteomic study and western blot verification were performed on the most effective preconditioned group. Results: The H6M group showed a lower infarct volume (p = 0.0005), lower mNSS score (p = 0.0009) than the M group. The H2M showed a lower level of IL-6 (p = 0.0213) than the M group. The caspase-3 level decreased in the H2M (p = 0.0002), H6M (p = 0.0025), and HpM groups (p = 0.0054) compared with that in the M group. Cleaved-caspase-3 expression decreased in the H2M (p = 0.0011), H6M (p < 0.0001), and HpM groups (p < 0.0001) compared with that in the M group. The neurons' ultrastructure and the blood-brain barrier in the peri-infarct tissue improved in the H2M and H6M groups. Immunofluorescence revealed increased NeuN-positive cells in the peri-infarct tissue in the H6M group (p = 0.0003, H6M vs. M). Protein expression of Chmp1a, Arpc5, and Hspa2 factors related to endocytosis were upregulated in the H6M compared with those of the M group (p < 0.05 for all) on western blot verification of label-free proteomics. Conclusions: Intermittent hypobaric hypoxia preconditioning exerts a neuroprotective effect in a rat stroke model. Persistent hypobaric hypoxia stimulation exhibited no significant neuroprotective effect. Intermittent hypoxic preconditioning for 6 h/day for 10 days upregulates key proteins in clathrin-dependent endocytosis of neurons in the cortex.

Preconditioning-Activated AKT Controls Neuronal Tolerance to Ischemia through the MDM2-p53 Pathway

One of the most important mechanisms of preconditioning-mediated neuroprotection is the attenuation of cell apoptosis, inducing brain tolerance after a subsequent injurious ischemia. In this context, the antiapoptotic PI3K/AKT signaling pathway plays a key role by regulating cell differentiation and survival. Active AKT is known to increase the expression of murine double minute-2 (MDM2), an E3-ubiquitin ligase that destabilizes p53 to promote the survival of cancer cells. In neurons, we recently showed that the MDM2–p53 interaction is potentiated by pharmacological preconditioning, based on subtoxic stimulation of NMDA glutamate receptor, which prevents ischemia-induced neuronal apoptosis. However, whether this mechanism contributes to the neuronal tolerance during ischemic preconditioning (IPC) is unknown. Here, we show that IPC induced PI3K-mediated phosphorylation of AKT at Ser⁴⁷³, which in turn phosphorylated MDM2 at Ser¹⁶⁶. This phosphorylation triggered the nuclear stabilization of MDM2, leading to p53 destabilization, thus preventing neuronal apoptosis upon an ischemic insult. Inhibition of the PI3K/AKT pathway with wortmannin or by AKT silencing induced the accumulation of cytosolic MDM2, abrogating IPC-induced neuroprotection. Thus, IPC enhances the activation of PI3K/AKT signaling pathway and promotes neuronal tolerance by controlling the MDM2–p53 interaction. Our findings provide a new mechanistic pathway involved in IPC-induced neuroprotection via modulation of AKT signaling, suggesting that AKT is a potential therapeutic target against ischemic injury.

Interactions among variants in P53 apoptotic pathway genes are associated with neurologic deterioration and functional outcome after acute ischemic stroke

OBJECTIVE

Neurologic deterioration (ND) and functional outcome after ischemic stroke (IS) are not accurately predicted by clinical pictures on admission. The aim of present study was to investigate the association of variants in P53 apoptotic pathway genes with ND and functional outcome after IS.

METHODS

Genotypes of nine variants in apoptosis-relevant genes were measured in patients with acute IS. Gene-gene interactions were analyzed by generalized multifactor dimensionality reduction (GMDR). The primary outcome was ND. ND was diagnosed in patients who worsened ≥2 points (National Institutes of Health Stroke Scale [NIHSS] score) within the first 10 days of stroke onset. The secondary outcome was functional status at 90 days after IS as measured by modified Rankin Scale (mRS) score.

RESULTS

A total of 705 enrolled patients, ND occurred in 174 (24.7%) patients, and 184 (26.1%) patients were poor functional outcome (mRS score > 2). Although the nine variants were not significantly associated with ND and functional outcome by univariate analysis, there was a gene-gene interaction among P53rs1042522, MDM-2rs2279744, and MMP-9 rs3918242 using GMDR analysis. The high-risk interaction among the three variants was independently associated with higher risk of ND (HR, 2.04, 95% CI: 1.22-5.64, p = .018) and poor functional outcome (OR, 2.68, 95% CI: 1.68-7.86, p = .004) after adjusting for the covariates.

CONCLUSION

The interactions among P53 rs1042522, MDM-2 rs2279744, and MMP-9 rs3918242 may increase the risk of ND and poor functional outcome and may be considered as a genetic marker of predicting ND and poor functional outcome after stroke.

Endogenous neuroprotective mechanism of ATP2B1 in transcriptional regulation of ischemic preconditioning

Ischemic stroke is the main cause of disability and mortality in the world. Clinical studies have shown that patients who undergo mild transient ischemic attack (TIA) before more severe ischemic stroke have lower clinical severity of stroke and better functional prognosis. This phenomenon is called ischemic preconditioning (IPC). IPC is a powerful intrinsic protection of the brain against ischemic injury, but the underlying mechanism of IPC-mediated endogenous protection of the brain is not clear.

METHODS

Using transcriptome method, we sequenced the serum of 3 stroke patients with progenitor TIA and 3 stroke patients without prodromal TIA. We explored the expression profiles of miRNAs and mRNAs in response to IPC, and predicted the regulatory pathway of IPC related genes and their expression in cerebral neurons. The methylation consistent expression of IPC-related gene ATP2B1 in blood and brain and alternative polyadenylate (APA) analysis were used to identify the pathway and molecular mechanism of endogenous neuroprotection of IPC.

RESULTS

We found that the brain protective effect of IPC was related to platelet homeostasis and Ca²⁺ concentration. IPC-related gene ATP2B1 was highly expressed in γ-aminobutyric acid (GABA)-containing neurons in the brain. From the mechanism, we speculated that ATP2B1 was representative of the same methylation in blood and brain and was affected by alternative polyadenylation.

CONCLUSION

We speculate that IPC can induce alternative polyadenylation of ATP2B1 and trigger the mechanism of brain endogenous neuroprotection by regulating the decrease of Ca²⁺ concentration in platelet homeostasis pathway and the activation of GABAB receptor.

Mitochondrial-nuclear p53 trafficking controls neuronal susceptibility in stroke

Stroke is a major cause of death and long-term disability in the adult. Neuronal apoptosis plays an essential role in the pathophysiology of ischemic brain damage and impaired functional recovery after stroke. The tumor suppressor protein p53 regulates key cellular processes, including cell cycle arrest, DNA repair, senescence, and apoptosis. Under cellular stress conditions, p53 undergoes post-translational modifications, which control protein localization, stability, and proapoptotic activity. After stroke, p53 rapidly accumulates in the ischemic brain, where it activates neuronal apoptosis through both transcriptional-dependent and -independent programs. Over the last years, subcellular localization of p53 has emerged as an important regulator of ischemia-induced neuronal apoptosis. Upon an ischemic insult, p53 rapidly translocates to the mitochondria and interacts with B-cell lymphoma-2 family proteins, which activate the mitochondrial apoptotic program, with higher efficacy than through its activity as a transcription factor. Moreover, the identification of a human single nucleotide polymorphism at codon 72 of the Tp53 gene that controls p53 mitochondrial localization and cell susceptibility to apoptosis supports the important role of the p53 mitochondrial program in neuronal survival and functional recovery after stroke. In this article, we review the relevance of mitochondrial and nuclear localization of p53 on neuronal susceptibility to cerebral ischemia and its impact on functional outcome of stroke patients.

Phosphorylation at S548 as a Functional Switch of Sterile Alpha and TIR Motif-Containing 1 in Cerebral Ischemia/Reperfusion Injury in Rats

Sterile alpha and Toll/interleukin-1 receptor motif-containing 1 (SARM1) is a pro-degenerative molecule in Wallerian degeneration, which is mainly expressed in brain/neurons and colocalized with mitochondria and microtubules. The aim of this study was to determine the role of SARM1 in cerebral ischemia/reperfusion (I/R) injury and the underlying mechanisms. In vivo, a middle cerebral artery occlusion/reperfusion (MCAO/R) model in adult male Sprague Dawley rats (250-300 g) was established, and in vitro, cultured primary neurons were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) to imitate I/R injury. Overexpression lentiviruses encoding wild-type SARM1 and SARM1 with serine 548 alanine mutation (S548A) were constructed and administered to rats by intra-penumbral injection. First, the potential role of SARM1 in cerebral I/R injury was confirmed by the increased protein levels of SARM1 within penumbra tissue, especially in neurons. Second, there was an increase in the phosphorylation ratio of p-SARM1(S548)/SARM1 at 2 h after MCAO/R. Third, on the basis of site-specific mutagenesis, we identified S548 as a key site for SARM1 phosphorylation in I/R conditions. Fourth, SARM1 (S548A) overexpression reduced infarct size, neuronal death, and neurobehavioral dysfunction, while wild-type SARM1 overexpression had the opposite effects. Finally, we found that SARM1 phosphorylation at the S548 site switched SARM1 function from promoting mitochondrial transport to inhibiting mitochondrial transport along axons after I/R injury. Restriction of SARM1 phosphorylation at S548 may be a promising intervention target for I/R injury; thus, exogenous administration of SARM1 (S548A) may be a novel strategy for improving neurological outcomes.

Inflammatory Response of Ischemic Tolerance in Circulating Plasma: Preconditioning-Induced by Transient Ischemic Attack (TIA) Phenomena in Acute Ischemia Patients (AIS)

Introduction: Ischemic tolerance (IT) refers to a state where cells are resistant to the damaging effects caused by periods of ischemia. In a clinical scenario, the IT phenomenon would be activated by a recent transient ischemic attack (TIA) before an ischemic stroke (IS). The characterization of inflammatory protein expression patterns will contribute to improved understanding of IT.

Methods: A total of 477 IS patients from nine hospitals, recruited between January 2011 and January 2016, were included in the current study and divided in three groups: 438 (91.9%) patients without previous TIA (group 1), 22 (4.6%) patients who suffered TIA 24 h before IS (group 2), and 17 (3.5%) patients who suffered TIA between 24 h and 7 days prior to IS (group 3). An inflammatory biomarker panel (IL-6, NT-proBNP, hsCRP, hs-Troponin, NSE, and S-100b) on plasma and a cytokine antibody array was performed to achieve the preconditioning signature potentially induced by TIA phenomena. Primary outcome was modified rankin scale (mRs) score at 90 days.

Results: Recent previous TIA was associated with better clinical outcome at 90 days (median mRS of group 1: 2.0 [1.0–4.0]; group 2: 2.0 [0.0–3.0]; group 3: 1.0 [0–2.5]; p = 0.086) and smaller brain lesion (group 1: 3.7 [0.7–18.3]; group 2: 0.8 [0.3–8.9]; group 3: 0.6 [0.1–5.5] mL; p = 0.006). All inflammation biomarkers were down regulated in the groups of recent TIA prior to IS compared to those who did not suffer a TIA events. Moreover, a cytokine antibody array revealed 30 differentially expressed proteins between the three groups. Among them, HRG1-alpha (Fold change 74.4 between group 1 and 2; 74.2 between group 1 and 3) and MAC-1 (Fold change 0.05 between group 1 and 2; 0.06 between group 1 and 3) expression levels would better stratify patients with TIA 7 days before IS. These two proteins showed an earlier inflammation profile that was not detectable by the biomarker panel.

Conclusion: Inflammatory pathways were activated by transient ischemic attack, however the period of time between this event and a further ischemic stroke could be determined by a protein signature that would contribute to define the role of ischemic tolerance induced by TIA.

Genetic variation in APOE, GRN, and TP53 are phenotype modifiers in frontotemporal dementia

Frontotemporal dementia (FTD) is a clinical, genetic, and pathologic heterogeneous group of neurodegenerative diseases. In this study, we investigated the role of APOƐ4, rs5848 in GRN, and rs1042522 in TP53 gene as disease risk factors and/or phenotype modifiers in 440 FTD patients, including 175 C9orf72 expansion carriers. We found that the C9orf72 expansion carriers showing an earlier age at onset (p < 0.001). Among the clinical groups, the FTD-MND (motoneuron disease) showed the lowest survival (hazard ratio [HR] = 4.12), and the progressive nonfluent aphasia group showed the highest onset age (p = 0.03). In our cohort, the rs1042522 in TP53 was associated with disease onset (p = 0.02) and survival (HR = 1.73) and rs5848 GRN with a significantly shorter survival in CC homozygous patients (HR = 1.98). The frequency of APOƐ4 carriers was significantly increased in the C9orf72 noncarriers (p = 0.022). Although validation of our findings is necessary, our results suggest that TP53, GRN, and APOE genes may act as phenotype modifiers in FTD and should be considered in future clinical trials.

Modulation of Cerebral Store-operated Calcium Entry-regulatory Factor (SARAF) and Peripheral Orai1 Following Focal Cerebral Ischemia and Preconditioning in Mice

Store-operated Ca²⁺ entry (SOCE) contributes to Ca²⁺ refilling of endoplasmic reticulum (ER), but also provides Ca²⁺ influx involved in physiological and pathological signalling functions. Upon depletion of Ca²⁺ store, the sensor protein stromal interaction molecule (STIM) activates Orai1, forming an ion-conducting pore highly selective for Ca²⁺. SOCE-associated regulatory factor (SARAF) associates with STIM1 to facilitate a slow form of Ca²⁺-dependent inactivation of SOCE or interacts with Orai1 to stimulate SOCE in STIM1-independent manner. We have investigated whether cerebral ischemic damage and neuroprotection conferred by ischemic preconditioning (PC) in mouse are associated with changes in the expression of the molecular components of SOCE. Ischemic PC induced by 15-min occlusion of the middle cerebral artery (MCAo) resulted in significant amelioration of histological and functional outcomes produced, 72 h later, by a more severe ischemia (1 h MCAo). Neither ischemia, nor PC affected the expression of Orai1 in the frontoparietal cortex. However, the number of Orai1-immunopositive cells, mostly corresponding to Ly-6G+ neutrophils, was significantly elevated in the blood after the ischemic insult, regardless of previous PC. The expression of Stim1 and SARAF, mainly localised in NeuN-immunopositive neurons, was reduced in the ischemic cortex. Interestingly, neuroprotection by ischemic PC prevented the reduction of SARAF expression in the lesioned cortex and this could be interpreted as a compensatory mechanism to restore ER Ca²⁺ refilling in neurons in the absence of STIM1. Thus, preventing SARAF downregulation may represent a pivotal mechanism implicated in neuroprotection provided by ischemic PC and should be exploited as an original target for novel stroke therapies.

Refocusing the Brain: New Approaches in Neuroprotection Against Ischemic Injury

A new era for neuroprotective strategies is emerging in ischemia/reperfusion. This has forced to review the studies existing to date based in neuroprotection against oxidative stress, which have undoubtedly contributed to clarify the brain endogenous mechanisms, as well as to identify possible therapeutic targets or biomarkers in stroke and other neurological diseases. The efficacy of exogenous administration of neuroprotective compounds has been shown in different studies so far. However, something must be missing to get these treatments successfully applied in the clinical environment. Here, the mechanisms involved in neuronal protection against physiological level of ROS and the main neuroprotective signaling pathways induced by excitotoxic and ischemic stimuli are reviewed. Also, the endogenous ischemic tolerance in terms of brain self-protection mechanisms against subsequent cerebral ischemia is revisited to highlight how the preconditioning has emerged as a powerful tool to understand these phenomena. A better understanding of endogenous defense against exacerbated ROS and metabolism in nervous cells will therefore aid to design pharmacological antioxidants targeted specifically against oxidative damage induced by ischemic injury, but also might be very valuable for translational medicine.

Influences of genetic variants on stroke recovery: a meta-analysis of the 31,895 cases

Background

The influences of genetic variants on functional clinical outcomes following stroke are unclear. In order to reliably quantify these influences, we undertook a comprehensive meta-analysis of outcomes after acute intracerebral haemorrhage (ICH) or ischaemic stroke (AIS) in relation to different genetic variants.

Methods

PubMed, PsycInfo, Embase and Medline electronic databases were searched up to January 2019. Outcomes, defined as favourable or poor, were assessed by validated scales (Barthel index, modified Rankin scale, Glasgow outcome scale and National Institutes of Health stroke scale).

Results

Ninety-two publications comprising 31,895 cases met our inclusion criteria. Poor outcome was observed in patients with ICH who possessed the APOE4 allele: OR =2.60 (95% CI = 1.25–5.41, p = 0.01) and in AIS patients with the GA or AA variant at the BDNF-196 locus: OR = 2.60 (95% CI = 1.25–5.41, p = 0.01) or a loss of function allele of CYP2C19: OR = 2.36 (95% CI = 1.56–3.55, p < 0.0001). Poor outcome was not associated with APOE4: OR = 1.02 (95% CI = 0.81–1.27, p = 0.90) or IL6-174 G/C: OR = 2.21 (95% CI = 0.55–8.86, p = 0.26) in patients with AIS.

Conclusions

We demonstrate that recovery of AIS was unfavourably associated with variants of BDNF and CYP2C19 genes whilst recovery of ICH was unfavourably associated with APOE4 gene.

Electronic supplementary material

The online version of this article (10.1007/s10072-019-04024-w) contains supplementary material, which is available to authorized users.