Folic acid deficiency enhanced microglial immune response via the Notch1/nuclear factor kappa B p65 pathway in hippocampus following rat brain I/R injury and BV2 cells

Scalp acupuncture alleviates remote hippocampal damage in MCAO rats by inhibiting neuroinflammation: A TMT-based proteomics analysis

While mounting evidence suggests that scalp acupuncture (SA) may be effective in alleviating neurological deficits in patients with acute ischemic stroke (IS), its effect on remote hippocampal damage in acute IS and the underlying mechanisms remain elusive. Thus, proteomics analysis was conducted to identify potential targets of SA therapy in acute IS. SA significantly reduced cerebral infarct volume and attenuated neuronal damage in the ischemic penumbra and hippocampus, as well as alleviated neurological deficits in rats with middle cerebral artery occlusion (MCAO). Moreover, 74 upregulated and 50 downregulated proteins were identified in the MCAO group compared to the sham group, whilst 52 up-regulated and 50 down-regulated proteins were identified in the SA group compared to the MCAO group. Bioinformatics analysis indicated that SA may exert neuroprotective effects by modulating the acute inflammatory response and microglial activation. Additionally, SA down-regulated the expression levels of Iba-1, TNF-α, IL-1β, and IL-6, while up-regulating those of IL-4 and IL-10. Likewise, it downregulated the expression levels of three key proteins identified via proteomics analysis (Kng1, Brd9, and Magl) that may mediate the anti-inflammatory effects of SA. Overall, these results indicate that SA attenuates neuronal damage in the hippocampus and ischemic penumbra and ameliorates neurological deficits. Proteomic analysis suggested that this effect is related to the modulation of the acute inflammatory response. SA attenuated remote hippocampal damage after IS by inhibiting microglia activation and neuroinflammation. Lastly, Kng1, Brd9, and Magl were identified as potential targets that mediate the anti-inflammatory effects of SA.

The role of m6A modification in the risk prediction and Notch1 pathway of Alzheimer's disease

N6-methyladenosine (m6A) methylation and abnormal immune responses are implicated in neurodegenerative diseases, yet their relationship in Alzheimer's disease (AD) remains unclear. We obtained AD datasets from GEO databases and used AD mouse and cell models, observing abnormal expression of m6A genes in the AD group, alongside disruptions in the immune microenvironment. Key m6A genes (YTHDF2, LRPPRC, and FTO) selected by machine learning were associated with the Notch pathway, with FTO and Notch1 displaying the strongest correlation. Specifically, FTO expression decreased and m6A methylation of Notch1 increased in AD mouse and cell models. We further silenced FTO expression in HT22 cells, resulting in upregulation of the Notch1 signaling pathway. Additionally, increased Notch1 expression in dendritic cells heightened inflammatory cytokine secretion in vitro. These results suggest that reduced FTO expression may contribute to the pathogenesis of AD by activating the Notch1 pathway to interfere with the immune response.

Gamma entrainment using audiovisual stimuli alleviates chemobrain pathology and cognitive impairment induced by chemotherapy in mice

Patients with cancer undergoing chemotherapy frequently experience a neurological condition known as chemotherapy-related cognitive impairment, or "chemobrain," which can persist for the remainder of their lives. Despite the growing prevalence of chemobrain, both its underlying mechanisms and treatment strategies remain poorly understood. Recent findings suggest that chemobrain shares several characteristics with neurodegenerative diseases, including chronic neuroinflammation, DNA damage, and synaptic loss. We investigated whether a noninvasive sensory stimulation treatment we term gamma entrainment using sensory stimuli (GENUS), which has been shown to alleviate aberrant immune and synaptic pathologies in mouse models of neurodegeneration, could also mitigate chemobrain phenotypes in mice administered a chemotherapeutic drug. When administered concurrently with the chemotherapeutic agent cisplatin, GENUS alleviated cisplatin-induced brain pathology, promoted oligodendrocyte survival, and improved cognitive function in a mouse model of chemobrain. These effects persisted for up to 105 days after GENUS treatment, suggesting the potential for long-lasting benefits. However, when administered to mice 90 days after chemotherapy, GENUS treatment only provided limited benefits, indicating that it was most effective when used to prevent the progression of chemobrain pathology. Furthermore, we demonstrated that the effects of GENUS in mice were not limited to cisplatin-induced chemobrain but also extended to methotrexate-induced chemobrain. Collectively, these findings suggest that GENUS may represent a versatile approach for treating chemobrain induced by different chemotherapy agents.

Mechanisms of immune response and cell death in ischemic stroke and their regulation by natural compounds

Ischemic stroke (IS), which is the third foremost cause of disability and death worldwide, has inflammation and cell death as its main pathological features. IS can lead to neuronal cell death and release factors such as damage-related molecular patterns, stimulating the immune system to release inflammatory mediators, thereby resulting in inflammation and exacerbating brain damage. Currently, there are a limited number of treatment methods for IS, which is a fact necessitating the discovery of new treatment targets. For this review, current research on inflammation and cell death in ischemic stroke was summarized. The complex roles and pathways of the principal immune cells (microglia, astrocyte, neutrophils, T lymphocytes, and monocytes/macrophage) in the immune system after IS in inflammation are discussed. The mechanisms of immune cell interactions and the cytokines involved in these interactions are summarized. Moreover, the cell death mechanisms (pyroptosis, apoptosis, necroptosis, PANoptosis, and ferroptosis) and pathways after IS are explored. Finally, a summary is provided of the mechanism of action of natural pharmacological active ingredients in the treatment of IS. Despite significant recent progress in research on IS, there remain many challenges that need to be overcome.

Targeting Microglia/Macrophages Notch1 Protects Neurons from Pyroptosis in Ischemic Stroke

BACKGROUND AND AIMS

The immune-inflammatory cascade and pyroptosis play an important role in the pathogenesis of cerebral ischemia-reperfusion injury (CIRI). The maintenance of immune homeostasis is inextricably linked to the Notch signaling pathway, but whether myeloid Notch1 affects microglia polarization as well as neuronal pyroptosis in CIRI is not fully understood. This study was designed to clarify the role of myeloid Notch1 in CIRI, providing new therapeutic strategies for ischemic stroke.

METHODS AND RESULTS

Myeloid-specific Notch1 knockout (Notch1M-KO) mice and the floxed Notch1 (Notch1FL/FL) mice were subjected to middle cerebral artery occlusion (MCAO). After 3 days of CIRI, we evaluated the neurological deficit score and cerebral infarction volume. Immunofluorescence staining was used to detect the expression of Notch1 and microglial subtype markers. Cerebral infiltrating macrophages were detected by flow cytometry. RT-qPCR was used to detect pro-inflammatory cytokines. Western blot was used to detect the expression of pyroptosis related proteins. The Notch1-siRNA transfected BV2 cells were co-cultured with HT22 cells to investigate the potential mechanisms by which microglial Notch1 affects neuronal pyroptosis induced by anoxia/reoxygenation in vitro. We found that Notch1 was activated in cerebral microglia/macrophages after CIRI. Myeloid Notch1 deficiency decreased the cerebral infarct volume (24.17 ± 3.29 vs. 36.17 ± 2.27, p < 0.001), neurological function scores (2.33 ± 0.47 vs. 3.17 ± 0.37, p < 0.001) and the infiltration of peripheral monocytes/macrophages (3.26 ± 0.53 vs. 5.67 ± 0.57, p < 0.01). Strikingly, myeloid-specific Notch1 knockout alleviated pyroptosis. Compared with microglia M1, increased microglia M2 were detected in the ischemic penumbra. In parallel in vitro co-culture experiments, we found that Notch1 knockdown in microglial BV2 cells inhibited anoxia/reoxygenation-induced JAK2/STAT3 activation and pyroptosis in hippocampal neuron HT22 cells.

CONCLUSIONS

Our findings elucidate the underlying mechanism of the myeloid Notch1 signaling pathway in regulating neuronal pyroptosis in CIRI, suggesting that targeting myeloid-specific Notch1 is an effective strategy for the treatment of ischemic stroke.

Protective effects of pyrroloquinoline quinone in brain folate deficiency

BACKGROUND

Folates (Vitamin B9) are critical for normal neurodevelopment and function, with transport mediated by three major pathways: folate receptor alpha (FRα), proton-coupled folate transporter (PCFT), and reduced folate carrier (RFC). Cerebral folate uptake primarily occurs at the blood-cerebrospinal fluid barrier (BCSFB) through concerted actions of FRα and PCFT, with impaired folate transport resulting in the neurological disorder cerebral folate deficiency (CFD). Increasing evidence suggests that disorders associated with CFD also present with neuroinflammation, oxidative stress, and mitochondrial dysfunction, however the role of brain folate deficiency in inducing these abnormalities is not well-understood. Our laboratory has identified the upregulation of RFC by nuclear respiratory factor 1 (NRF-1) at the blood-brain barrier (BBB) once indirectly activated by the natural compound pyrroloquinoline quinone (PQQ). PQQ is also of interest due to its anti-inflammatory, antioxidant, and mitochondrial biogenesis effects. In this study, we examined the effects of folate deficiency and PQQ treatment on inflammatory and oxidative stress responses, and changes in mitochondrial function.

METHODS

Primary cultures of mouse mixed glial cells exposed to folate-deficient (FD) conditions and treated with PQQ were analyzed for changes in gene expression of the folate transporters, inflammatory markers, oxidative stress markers, and mitochondrial DNA (mtDNA) content through qPCR analysis. Changes in cellular reactive oxygen species (ROS) levels were analyzed in vitro through a DCFDA assay. Wildtype (C57BL6/N) mice exposed to FD (0 mg/kg folate), or control (2 mg/kg folate) diets underwent a 10-day (20 mg/kg/day) PQQ treatment regimen and brain tissues were collected and analyzed.

RESULTS

Folate deficiency resulted in increased expression of inflammatory and oxidative stress markers in vitro and in vivo, with increased cellular ROS levels observed in mixed glial cells as well as a reduction of mitochondrial DNA (mtDNA) content observed in FD mixed glial cells. PQQ treatment was able to reverse these changes, while increasing RFC expression through activation of the PGC-1α/NRF-1 signaling pathway.

CONCLUSION

These results demonstrate the effects of brain folate deficiency, which may contribute to the neurological deficits commonly seen in disorders of CFD. PQQ may represent a novel treatment strategy for disorders associated with CFD, as it can increase folate uptake, while in parallel reversing many abnormalities that arise with brain folate deficiency.

Folate Deficiency Increased Microglial Amyloid-β Phagocytosis via the RAGE Receptor in Chronic Unpredictable Mild-Stress Rat and BV2 Cells

Depression is often considered one of the prevalent neuropsychiatric symptoms of Alzheimer's disease (AD). β-amyloid (Aβ) metabolism disorders and impaired microglia phagocytosis are potential pathological mechanisms between depression and AD. Folate deficiency (FD) is a risk factor for depression and AD. In this study, we used a chronic unpredictable mild stress (CUMS) rat model and a model of Aβ phagocytosis by BV2 cells to explore the potential mechanisms by which FD affects depression and AD. The results revealed that FD exacerbated depressive behavior and activated microglia in CUMS rats, leading to an increase in intracellular Aβ and phagocytosis-related receptors for advanced glycation end products (RAGE). Then, in vitro results showed that the expression of the RAGE receptor and M2 phenotype marker (CD206) were upregulated by FD treatment in BV2 cells, leading to an increase in Aβ phagocytosis. However, there was no significant difference in the expression of toll-like receptor 4 (TLR4) and clathrin heavy chain (CHC). Furthermore, when using the RAGE-specific inhibitor FPS-ZM1, there was no significant difference in Aβ uptake between folate-normal (FN) and FD BV2 cell groups. In conclusion, these findings suggest FD may promote microglia phagocytosis Aβ via regulating the expression of RAGE or microglia phenotype under Aβ treatment.

Folic acid deficiency exacerbates the inflammatory response of astrocytes after ischemia-reperfusion by enhancing the interaction between IL-6 and JAK-1/pSTAT3

AIM

To demonstrate the role of IL-6 and pSTAT3 in the inflammatory response to cerebral ischemia/reperfusion following folic acid deficiency (FD).

METHODS

The middle cerebral artery occlusion/reperfusion (MCAO/R) model was established in adult male Sprague-Dawley rats in vivo, and cultured primary astrocytes were exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) to emulate ischemia/reperfusion injury in vitro.

RESULTS

Glial fibrillary acidic protein (GFAP) expression significantly increased in astrocytes of the brain cortex in the MCAO group compared to the SHAM group. Nevertheless, FD did not further promote GFAP expression in astrocytes of rat brain tissue after MCAO. This result was further confirmed in the OGD/R cellular model. In addition, FD did not promote the expressions of TNF-α and IL-1β but raised IL-6 (Peak at 12 h after MCAO) and pSTAT3 (Peak at 24 h after MCAO) levels in the affected cortices of MCAO rats. In the in vitro model, the levels of IL-6 and pSTAT3 in astrocytes were significantly reduced by treatment with Filgotinib (JAK-1 inhibitor) but not AG490 (JAK-2 inhibitor). Moreover, the suppression of IL-6 expression reduced FD-induced increases in pSTAT3 and pJAK-1. In turn, inhibited pSTAT3 expression also depressed the FD-mediated increase in IL-6 expression.

CONCLUSIONS

FD led to the overproduction of IL-6 and subsequently increased pSTAT3 levels via JAK-1 but not JAK-2, which further promoted increased IL-6 expression, thereby exacerbating the inflammatory response of primary astrocytes.

Folate deprivation induced neuroinflammation impairs cognition

Nutritional status is associated with many neurocognitive diseases. Folate is one of the micronutrients, and its deficiency is associated with clinical outcomes of neurological diseases. Nevertheless, molecular mechanism behind the folate deficiency induced neurological disorders are not well-known. We have hypothesized that folate-deficiency is a cardinal determinant responsible for manifestation of cognitive impairment through inflammation mediated neurodegenerative pathologies. Objective of the current study was to assess whether folate deficiency is associated with cognitive dysfunction or is merely an epiphenomenon and to identify the underlying mechanisms. We developed folate insufficient zebrafish model through intra-peritoneal treatment of methotrexate. T-maze test was carried to assess the spatial learning and memory of the fish. Higher latency of the folate-deprived zebrafishes in the T-maze test is a reflection of altered cognition. This result is supported by declined levels of dopamine and serotonin, neurotransmitters linked with learning and memory. Elevated IL-6 and CRP in peripheral blood, along with increased expression of NF-ĸB in brain indicates manifestation of neuroinflammation. Indeed, together with upregulation of maptb gene it can be implied that folate deficiency acts as a risk factor for neurodegeneration in the form of tauopathies. Furthermore, diminished localisation of synaptopodin, a protein linked to neural plasticity, suggests that neuroinflammation caused by folate deprivation hampers the plasticity of brain. Histological analysis of brain revealed the development of histopathological features including spongiform degeneration and neuronal loss in folate deprived condition. We thus conclude that folate deficiency results in NF-ĸB activation, which through multiple processes mediated by neuroinflammation could lead to cognitive decline.

TJ-M2010-5, a novel CNS drug candidate, attenuates acute cerebral ischemia-reperfusion injury through the MyD88/NF-κB and ERK pathway

Background: Cerebral ischemia-reperfusion injury (CIRI) inevitably occurs after vascular recanalization treatment for ischemic stroke. The accompanying inflammatory cascades have a major impact on outcome and regeneration after ischemic stroke. Evidences have demonstrated that TLR/MyD88/NF-κB signaling contributes to CIRI. This study aimed to investigate the druggability of MyD88 in the central nervous system (CNS) and the neuroprotective and anti-neuroinflammatory effects of the MyD88 inhibitor TJ-M2010-5 on CIRI. Methods: A middle cerebral artery occlusion (MCAO) model was used to simulate CIRI in mice. BV-2 cells were stimulated with oxygen glucose deprivation/reoxygenation (OGD/R) or lipopolysaccharide, and SH-SY5Y cells were induced by OGD/R in vitro. Neurological deficit scores and cerebral infarction volumes were evaluated. Immunofluorescence staining was performed to measure neuronal damage and apoptosis in the brain. The anti-neuroinflammatory effect of TJ-M2010-5 was evaluated by analyzing the expression of inflammatory cytokines, activation of microglia, and infiltration of peripheral myeloid cells. The expression of proteins of the MyD88/NF-κB and ERK pathway was detected by Simple Western. The concentrations of TJ-M2010-5 in the blood and brain were analyzed by liquid chromatography-mass spectrometry. Results: The cerebral infarction volume decreased in mice treated with TJ-M2010-5, with the most prominent decrease being approximately 80% of the original infarction volume. Neuronal loss and apoptosis were reduced following TJ-M2010-5 treatment. TJ-M2010-5 inhibited the infiltration of peripheral myeloid cells and the activation of microglia. TJ-M2010-5 also downregulated the expression of inflammatory cytokines and inhibited the MyD88/NF-κB and ERK pathway. Furthermore, TJ-M2010-5 showed good blood-brain barrier permeability and no neurotoxicity. Conclusion: TJ-M2010-5 has an excellent therapeutic effect on CIRI as a novel CNS drug candidate by inhibiting excessive neuroinflammatory responses.

Ischemic stroke: From pathological mechanisms to neuroprotective strategies

Ischemic stroke (IS) has complex pathological mechanisms, and is extremely difficult to treat. At present, the treatment of IS is mainly based on intravenous thrombolysis and mechanical thrombectomy, but they are limited by a strict time window. In addition, after intravenous thrombolysis or mechanical thrombectomy, damaged neurons often fail to make ideal improvements due to microcirculation disorders. Therefore, finding suitable pathways and targets from the pathological mechanism is crucial for the development of neuroprotective agents against IS. With the hope of making contributions to the development of IS treatments, this review will introduce (1) how related targets are found in pathological mechanisms such as inflammation, excitotoxicity, oxidative stress, and complement system activation; and (2) the current status and challenges in drug development.

Astaxanthin-folic acid combined treatment potentiates neuronal regeneration and functional recovery after brachial plexus avulsion and reimplantation

Brachial plexus avulsion (BPA), which commonly occurs in neonatal birth injuries and car accidents, severely disrupts spinal cord segments and nerve roots. Avulsion is usually located in the transitional zone at the junction of spinal nerve roots and starting point of the spinal cord, which places heavy disability burdens on patients due to sensory and motor function loss in the innervated areas. Primary mechanical injuries and secondary pathogenesis, such as inflammatory infiltration and oxidative stress, lead to inefficient management and poor prognosis. Astaxanthin (AST) has a strong ability to bleach singlet oxygen and capture free radicals, quench singlet oxygen and trap free radicals, and folic acid (FC) can effectively inhibit the inflammatory response. This study aimed to investigate the therapeutic effects of AST and FC on BPA. The 24 h after BPA was considered the acute phase of the injury, and the combination of AST and FC had the best therapeutic effect due to the synergistic effect of AST’s antioxidant and FC’s anti-inflammatory properties. At 6 weeks after BPA, AST-FC promoted the recovery of biceps motor functions, increased myofiber diameter, enlarged the amplitude of musculocutaneous nerve-biceps compound action potential, and improved Terzis grooming test (TGT) scores. Meanwhile, more functional ventral horn motor neurons in the spinal cord were maintained. In conclusion, AST-FC combined therapy has a potential role in the clinical management of BPA since it can effectively alleviate oxidative stress and the inflammatory response in the acute phase of BPA, increase the survival rate of neurons, and promote neuronal regeneration and recovery of motor functions in the late stage of BPA.

Facile bimetallic co-amplified electrochemical sensor for folic acid sensing based on CoNPs and CuNPs

Folic acid (FA) is essential for human health, particularly for pregnant women and infants. In this work, a glassy carbon electrode (GCE) was modified by a bimetallic layer of Cu/Co nanoparticles (CuNPs/CoNPs) as a synergistic amplification element by simple step-by-step electrodeposition, and was used for sensitive detection of FA. The proposed CuNPs/CoNPs/GCE sensor was characterized by differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and field emission scanning electron microscopy (FESEM). Then, under optimal conditions, a linear relationship was obtained in the wide range of 110.00-1750.00 μM for the detection of FA with a limit of detection (LOD) of 34.79 μM (S/N = 3). The sensitivity was calculated as 0.096 μA μM^-1 cm^-2. Some interfering compounds including glucose (Glc), biotin, dopamine (DA), and glutamic acid (Glu) showed little effect on the detection of FA by amperometry (i-t). Finally, the average recovery obtained was in a range of 91.77-110.06%, with a relative standard deviation (RSD) less than 8.00% in FA tablets, indicating that the proposed sensor can accurately and effectively detect the FA content in FA tablets.

Natural bear bile powder suppresses neuroinflammation in lipopolysaccharide-treated mice via regulating TGR5/AKT/NF-κB signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

According to the Tang Dynasty classics Dietetic Material Medica and the Ming Dynasty classics Compendium of Materia Medica records, bear bile powder (BBP) has been used to treat a variety of diseases, such as febrile seizures, the pathogenesis of which is associated to neuroinflammation. However, the mechanism of BBP on alleviating neuroinflammation remains unclear.

AIMS OF THE STUDY

Microglia can be activated by peripheral lipopolysaccharide (LPS) and play an important role in the pathogenesis of neuroinflammation. The purpose of this study is to investigate the effects and mechanism of BBP in inhibiting LPS-induced microglia inflammation in vitro and in vivo.

MATERIALS AND METHODS

The anti-microglia inflammatory effects and mechanism of BBP were assessed in LPS-treated BV2 microglial cells and in LPS-treated mice. The mRNA expression levels of the inflammatory factor and the protein expressions of cyclooxygenase-2 (COX2), inducible nitric oxide synthase (iNOS), takeda G-protein coupled receptor 5 (TGR5), nuclear factor-κB (NF-κB), inhibitor of NF-κB (IκBɑ), protein kinase B (AKT) in BV2 cells, mouse hippocampus and cortex were detected. The NF-κB transcription activity and NF-κB nuclear translocation were observed.

RESULTS

Our findings showed that BBP reduces branched process retraction and NO in LPS-treated BV2 cells, inhibits the protein expression of ionized calcium binding adaptor molecule 1 in the hippocampus of LPS-treated mice. Moreover, we observed that BBP decreases tumor necrosis factor α, interleukin (IL)-6 and IL-1β mRNA levels, deceases iNOS and COX-2 protein levels, increases TGR5 protein levels, suppresses the phosphorylation of AKT, NF-κB and IκBɑ protein in microglia both in vitro and in vivo. Further, we found that triamterene, the inhibitor of TGR5, abolishes the effects of BBP in LPS- treated BV2 cells.

CONCLUSION

BBP inhibits LPS-induced microglia activation, and the mechanism of its action is partly through TGR5/AKT/NF-κB signaling pathway.

Alleviating Oxidative Damage-Induced Telomere Attrition: a Potential Mechanism for Inhibition by Folic Acid of Apoptosis in Neural Stem Cells

DNA oxidative damage can cause telomere attrition or dysfunction that triggers cell senescence and apoptosis. The hypothesis of this study is that folic acid decreases apoptosis in neural stem cells (NSCs) by preventing oxidative stress-induced telomere attrition. Primary cultures of NSCs were incubated for 9 days with various concentrations of folic acid (0-40 µM) and then incubated for 24 h with a combination of folic acid and an oxidant (100-µM hydrogen peroxide, H₂O₂), antioxidant (10-mM N-acetyl-L-cysteine, NAC), or vehicle. Intracellular folate concentration, apoptosis rate, cell proliferative capacity, telomere length, telomeric DNA oxidative damage, telomerase activity, intracellular reactive oxygen species (ROS) levels, cellular oxidative damage, and intracellular antioxidant enzyme activities were determined. The results showed that folic acid deficiency in NSCs decreased intracellular folate concentration, cell proliferation, telomere length, and telomerase activity but increased apoptosis, telomeric DNA oxidative damage, and intracellular ROS levels. In contrast, folic acid supplementation dose-dependently increased intracellular folate concentration, cell proliferative capacity, telomere length, and telomerase activity but decreased apoptosis, telomeric DNA oxidative damage, and intracellular ROS levels. Exposure to H₂O₂ aggravated telomere attrition and oxidative damage, whereas NAC alleviated the latter. High doses of folic acid prevented telomere attrition and telomeric DNA oxidative damage by H₂O₂. In conclusion, inhibition of telomeric DNA oxidative damage and telomere attrition in NSCs may be potential mechanisms of inhibiting NSC apoptosis by folic acid.

PLXNA2 knockdown promotes M2 microglia polarization through mTOR/STAT3 signaling to improve functional recovery in rats after cerebral ischemia/reperfusion injury

Ischemic stroke is an acute cerebrovascular disease characterized by high mortality, morbidity and disability rates. Ischemia/reperfusion is a critical pathophysiological basis of motor and cognitive dysfunction caused by ischemic stroke. Microglia, innate immune cells of the central nervous system, mediate the neuroinflammatory response to ischemia/reperfusion. PlexinA2 (PLXNA2) plays an important role in the regulation of neuronal axon guidance, the immune response and angiogenesis. However, it is not clear whether PLXNA2 regulates microglia polarization in ischemic stroke or the underlying mechanism. In the present study, we investigated the role of PLXNA2 in rats with middle cerebral artery occlusion/reperfusion (MCAO/R) and BV2 microglia cells with oxygen and glucose deprivation/reoxygenation (OGD/R). A battery of behavioral tests, including the beam balance test, forelimb placement test, foot fault test, cylinder test, CatWalk gait analysis and Morris water maze test were performed to evaluate sensorimotor function, locomotor activity and cognitive ability. The expression of M1/M2-specific markers in the ischemic penumbra and BV2 microglia cells was detected using immunofluorescence staining, quantitative real-time PCR analysis and Western blot analysis. Our study showed that PLXNA2 knockdown accelerated the recovery of motor function and cognitive ability after MCAO/R. In addition, PLXNA2 knockdown restrained proinflammatory cytokine release and promoted anti-inflammatory cytokine release, and the mammalian target of rapamycin (mTOR)/signal transducer and activator of transcription 3 (STAT3) pathway was involved in PLXNA2 regulated microglia polarization. Taken together, our results indicate that PLXNA2 knockdown reduces neuroinflammation by switching the microglia phenotype from M1 to M2 in the ischemic penumbra of MCAO/R-injured rats, which may be due to the inhibition of mTOR/STAT3 signaling. Treatments targeting PLXNA2 may be a promising therapeutic strategy for ischemic stroke.

Long noncoding RNA ANRIL knockdown attenuates neuroinflammation following ischemic stroke via suppressing the expression of NF-κB in vitro and in vivo

OBJECTIVE

Increasing evidence suggests that long-noncoding RNAs can exert neuroprotective effects in cerebral ischemia-reperfusion injury. Levels of the long noncoding RNA ANRIL (ANRIL) are reportedly altered in ischemic stroke (IS) patients, but its role in IS requires further clarification. This study was designed to explore the mechanistic function of ANRIL in IS.

METHODS

In vitro, HT22 cells was treated with an oxygen-glucose deprivation/reperfusion (OGD/R). In vivo, brain ischemia/reperfusion was induced by 60-minute transient middle cerebral artery occlusion/reperfusion (MCAO/R) IS model in C57/BL6 mice. Additionally, cells were transfected with si-ANRIL, pcDNA3.1-ANRIL, pcDNA3.1-NF-κB, or appropriate negative controls, and si-ANRIL and pcDNA3.1-NF-κB were administered into the lateral ventricles in MCAO/R model mice. Cell viability and apoptosis were detected via MTT and flow cytometry assays. mRNA and protein expression of NF-κB were detected via qRT-PCR and Western blotting. IL-1β, IL-6, TNF-a, and iNOS levels were detected via ELISA. In addition, infarcted area and neuronal injury were evaluated via TTC, Nissl, and immunofluorescent staining.

RESULTS

We found that ANRIL knockdown increased cell viability and reduced apoptosis in vitro. Additionally, we found that ANRIL knockdown decreased p-P65, P65, IL-1β, IL-6, TNF-a, and iNOS levels, whereas these effects were reversed by NF-κB overexpression both in vitro and in vivo.

CONCLUSION

our results suggest that ANRIL knockdown attenuates neuroinflammation by suppressing the expression of NF-κB both in vitro and vivo model of IS, sugguesting that ANRIL might be a potentially viable therapeutictarget to diminish neuroinflammation in IS patients.

Tea polyphenols ameliorates memory decline in aging model rats by inhibiting brain TLR4/NF-κB inflammatory signaling pathway caused by intestinal flora dysbiosis

AIMS

Tea is a rich source of pharmacologically active molecules that has been suggested to provide a variety of health benefits. However, its mechanism of action in aging-related intestinal flora dysbiosis mediated neuroinflammation is still unclear. This study aimed to explore whether tea polyphenols (TP) can improve memory by regulating intestinal flora mediated neuroinflammation in aging model rats.

METHODS

Ovariectomy (OVX) combined with D-galactose injection was used to establish aging rats related to menopause. The rats were divided into Sham control group, Aging model group, TP 75 mg/kg, 150 mg/kg, 300 mg/kg groups and VE group. After 12 weeks of intervention, the shuttle box test and Y maze test were used to check the memory of rats. The composition of intestinal flora was assessed by 16S rRNA sequencing technology. HE staining and ELISA were used to detect intestinal epithelial morphology and permeability, respectively. TLR4/NF-κB inflammation pathway related indicators were investigated by western blot, and the microglia activation in rat hippocampal tissue was checked by immunofluorescence.

RESULTS

In the shuttle box test and the Y maze test, compared with the Sham control group, the memory of Aging model rats was significantly declined. It was observed that the intestinal flora of Aging model rats was dysbiosis, the permeability of the intestinal epithelium was increased. Further experimental results showed that the expression of TLR4/NF-κB inflammatory pathway related proteins in the hippocampus were increased, and the excessive activation of microglia was observed. The beneficial effects of TP intervention have been found to prevent memory decline and significantly improve brain inflammation induced by intestinal flora dysbiosis, and TP 300 mg/kg showed a more obvious advantage than TP 75 mg/kg. TP 300 mg/kg can significantly improve the behavior of rats, improve the composition and diversity of the intestinal flora, and the shape and function of the intestinal epithelium. By reversing the increased expression levels of TLR4, IRAK, p-IκBα and nuclear NF-κB p65 proteins in the hippocampus of Aging model rats, the activation of microglia in the CA1, CA3 and Dentate gyrus (DG) sub-regions of the hippocampus can be inhibited.

CONCLUSION

TP inhibits the brain TLR4/NF-κB inflammatory signal pathway caused by the dysbiosis of intestinal flora, which may be one of the mechanisms to improve the memory decline in aging model rats.

Xiaoxuming Decoction Regulates Vascular Function by Modulating G Protein-Coupled Receptors: A Molecular Docking Study

Xiaoxuming decoction (XXMD) is a traditional Chinese herbal medicine (CHM) that is used for the treatment of stroke in China. Stroke injury damages the cerebral vasculature and disrupts the autoregulation of vasoconstriction and vasodilatation, which is crucial for maintaining constant cerebral blood flow (CBF). It has been reported that XXMD exerts a positive effect on cerebral circulation in animal models of stroke. However, the mechanisms underlying the regulatory effect of XXMD on vascular tone, and the interactions among the multiple components of XXMD, remain unclear. In this study, XXMD was found to induce relaxation of the basilar artery rings of rats precontracted by 5-hydroxytryptamine (5-HT) in vitro, in a dose-dependent manner. The modulation of vascular tone and the process of cerebral ischemia are mediated via the interactions between G protein-coupled receptors (GPCRs) and their ligands, including 5-HT, angiotensin II (Ang II), and urotensin II (UII). Thus, the potential synergistic effects of the different components of XXMD on the regulation of vasoconstriction and vasodilation were further investigated by molecular docking based on network pharmacology. We constructed and analyzed a database comprising 963 compounds of XXMD and studied the interactions between five vascular GPCRs (5-HT1A receptor (5-HT1AR), 5-HT1B receptor (5-HT1BR), Ang II type 1 receptor (AT1R), beta 2-adrenergic receptor (β2-AR), and UII receptor (UTR)) and the various herbal constituents of XXMD using molecular docking. By constructing and analyzing the compound-target networks of XXMD, we found that Glycyrrhizae Radix et Rhizoma, Ginseng Radix et Rhizoma, and Paeoniae Radix Alba were the three major herbs that contained a large number of compounds with high docking scores. We additionally observed that several constituents of XXMD, including gallotannin, liquiritin apioside, nariutin, 1,2,3,4,6-pentagalloylglucose, folic acid, and ginsenoside Rb1, targeted multiple vascular GPCRs. Moreover, the interactions between the components of XXMD and the targets related to vascular tone constituted the comprehensive cerebrovascular regulatory function of XXMD and provided a material basis of the vasoregulatory function of XXMD. The study reports the contributions of various components of XXMD to the regulatory effects on vascular tone and provides scientific evidence for the multicomponent and multitargeting characteristics of XXMD.

Mapping of folic acid in the children brainstem

Using highly specific antisera, the neuroanatomical distribution of folic acid (FA) and retinoic acid (RA) has been studied for the first time in the children brainstem. Neither immunoreactive structures containing RA nor immunoreactive fibers containing FA were found. FA-immunoreactive perikarya (fusiform, small/medium in size, one short dendrite) were only found in the pons in three regions: central gray, reticular formation, and locus coeruleus. The number of cell bodies decreased with age. In the first case studied (2 years), a moderate density of cell bodies was observed in the central gray and reticular formation, whereas a low density was found in the locus coeruleus. In the second case (6 years), a low density of these perikarya was observed in the central gray, reticular formation, and locus coeruleus. In the third case (7 years), a low density of FA-immunoreactive cell bodies was found in the central gray and reticular formation, whereas in the locus coeruleus no immunoreactive cell bodies were observed. The distribution of FA in the central nervous system of humans and monkeys is different and, in addition, in these species the vitamin was located in different parts of the nerve cells. The restricted distribution of FA suggests that the vitamin is involved in specific physiological mechanisms.

The role of nutrition in space exploration: Implications for sensorimotor, cognition, behavior and the cerebral changes due to the exposure to radiation, altered gravity, and isolation/confinement hazards of spaceflight

Multi-year crewed space exploration missions are now on the horizon; therefore, it is important that we understand and mitigate the physiological effects of spaceflight. The spaceflight hazards-radiation, isolation, confinement, and altered gravity-have the potential to contribute to neuroinflammation and produce long-term cognitive and behavioral effects-while the fifth hazard, distance from earth, limits capabilities to mitigate these risks. Accumulated evidence suggests that nutrition has an important role in optimizing cognition and reducing the risk of neurodegenerative diseases caused by neuroinflammation. Here we review the nutritional perspective of how these spaceflight hazards affect the astronaut's brain, behavior, performance, and sensorimotor function. We also assess potential nutrient/nutritional countermeasures that could prevent or mitigate spaceflight risks and ensure that crewmembers remain healthy and perform well during their missions. Just as history has taught us the importance of nutrition in terrestrial exploration, we must understand the role of nutrition in the development and mitigation of spaceflight risks before humans can successfully explore beyond low-Earth orbit.

Pterostilbene alleviates cerebral ischemia and reperfusion injury in rats by modulating microglial activation

Ischemic stroke is a severe neurological disease without known effective therapy. Microglia-mediated neuroinflammation plays an important role in ischemic stroke. Therefore, finding a safe and effective microglial activation inhibitor might lead to an effective therapeutic strategy against ischemic stroke. In this project, our goal was to explore both the mechanism and effect of pterostilbene in MCAO/R rats. The potential effect of pterostilbene on ischemic stroke was tested using MCAO/R rats and its effect on microglial activation was tested in LPS-stimulated BV-2 cells. In vivo, pterostilbene decreased the neurological scores, brain water content and infarct volume in MCAO/R rats. Pterostilbene increased the number of mature neurons, decreased the number of activated microglia, and reduced iNOS and IL-1β mRNA expression. Pterostilbene inhibited phosphorylated-IκBα expression, thus promoting IκBα expression and inhibiting ROS overexpression. In vitro, pterostilbene inhibited the expression of inflammatory cytokines and suppressed NAPDH activity as well as activation of both the NF-κB pathway and ROS production. To our knowledge, our study is the first to demonstrate that pterostilbene-mediated alleviation of cerebral ischemia and reperfusion injury in rats may be correlated with the inhibition of the ROS/NF-κB-mediated inflammatory pathway in microglia, indicating the potential for the use of pterostilbene as a candidate therapeutic compound for ischemic stroke.

Astaxanthin inhibits microglia M1 activation against inflammatory injury triggered by lipopolysaccharide through down-regulating miR-31-5p

AIMS

Astaxanthin is a natural carotenoid, can readily cross the blood-brain barrier and exerts a powerful neuroprotective effect. In this study, experiments were performed to explore the underlying molecular mechanisms of which Astaxanthin inhibiting the microglia M1 activation.

MAIN METHODS

BV2 cells and mice were pre-treated with Astaxanthin and treated by Lipopolysaccharide (LPS). The expressions of M1-related factors (pro-inflammatory cytokines and M1 markers) were measured by RT-qPCR and western blot. The target association between miR-31-5p and Numb was explored via luciferase activity assay. MiR-31-5p mimic was transfected into BV2 cells, then the cells were treated with Astaxanthin in combination with LPS. The expression of M1-related factors and Notch pathway-related molecules were measured via RT-qPCR, western blot and immunofluorescence assay.

KEY FINDINGS

Precondition of BV2 cells with Astaxanthin inhibited the expression of M1-related factors triggered by LPS. In addition, Astaxanthin decreased the number of Iba1-positive microglia and downregulated the levels of M1-related factors in hippocampus in LPS-treated mice. Further investigation revealed that Astaxanthin-mediated suppression of M1-related factors levels was reversed by miR-31-5p mimic in BV2 cells stimulated by LPS. Subsequently, we verified that miR-31-5p repressed Numb expression by binding to the 3'-UTR of Numb mRNA. Also, Astaxanthin suppressed the expression of Notch1, Hes1 and Hes5 and improved the expression of Numb in BV2 cells challenged by LPS, but this alteration can be reversed by miR-31-5p mimic.

SIGNIFICANCE

Our study demonstrated that down-regulating miR-31-5p by Astaxanthin could be a potential therapeutic approach to suppress neuroinflammation via regulating microglia M1 activation.

Andrographolide exerts anti-inflammatory effects in Mycobacterium tuberculosis-infected macrophages by regulating the Notch1/Akt/NF-κB axis

Tuberculosis is a serious public health problem aggravated by the slow progress in the development of new anti-tuberculosis drugs. The hyper-reactive TB patients have suffered from chronic inflammation which could cause deleterious effects on their bodies. Therefore, it is imperative to develop an adjunctive therapy based on inflammatory modulation during Mycobacterium tuberculosis (Mtb) infection. The present study aims to investigate the immune regulatory effects of Andrographolide (Andro) on Mtb-infected macrophages and its underlying mechanisms. The results showed that Andro inhibits the production of IL-1β and other inflammatory cytokines in a dose-dependent manner. The down-regulation of IL-1β expression causes the declining expression of IL-8 and MCP-1 in lung epithelial cells which were co-cultured with Mtb-infected macrophages.  The inhibition of the activation of NF-κB pathway, but not the inhibition of MAPK signaling pathway, accounts for the anti-inflammatory role of Andro. Further studies elucidated that Andro could evoke the activation of autophagy to degrade NLRP3, which ultimately inhibited inflammasome activation and subsequent IL-1β production. Finally, the relevant results demonstrated that Andro inhibited the Notch1 pathway to down-regulate the phosphorylation of Akt/mTOR and NF-κB p65 subunit. Taken together, Andro has been found to suppress the Notch1/Akt/NF-κB signaling pathway. Both Akt inhibition-induced autophagy and inhibition of the NF-κB pathway contributed to restraining the activation of NLRP3 inflammasome and subsequent IL-1β production. Then, the decreased production of IL-1β influenced chemokine expression in lung epithelial cells. Based on these results, anti-inflammatory effect of Andro in TB infection is merit further investigation.

Inhibition of mast cell tryptase attenuates neuroinflammation via PAR-2/p38/NFκB pathway following asphyxial cardiac arrest in rats

Background

Cardiac arrest survivors suffer from neurological dysfunction including cognitive impairment. Cerebral mast cells, the key regulators of neuroinflammation contribute to neuroinflammation-associated cognitive dysfunction. Mast cell tryptase was demonstrated to have a proinflammatory effect on microglia via the activation of microglial protease-activated receptor-2 (PAR-2). This study investigated the potential anti-neuroinflammatory effect of mast cell tryptase inhibition and the underlying mechanism of PAR-2/p-p38/NFκB signaling following asphyxia-induced cardiac arrest in rats.

Methods

Adult male Sprague-Dawley rats resuscitated from 10 min of asphyxia-induced cardiac arrest were randomized to four separate experiments including time-course, short-term outcomes, long-term outcomes and mechanism studies. The effect of mast cell tryptase inhibition on asphyxial cardiac arrest outcomes was examined after intranasal administration of selective mast cell tryptase inhibitor (APC366; 50 μg/rat or 150 μg/rat). AC55541 (selective PAR-2 activator; 30 μg/rat) and SB203580 (selective p38 inhibitor; 300 μg/rat) were used for intervention. Short-term neurocognitive functions were evaluated using the neurological deficit score, number of seizures, adhesive tape removal test, and T-maze test, while long-term cognitive functions were evaluated using the Morris water maze test. Hippocampal neuronal degeneration was evaluated by Fluoro-Jade C staining.

Results

Mast cell tryptase and PAR-2 were dramatically increased in the brain following asphyxia-induced cardiac arrest. The inhibition of mast cell tryptase by APC366 improved both short- and long-term neurological outcomes in resuscitated rats. Such behavioral benefits were associated with reduced expressions of PAR-2, p-p38, NFκB, TNF-α, and IL-6 in the brain as well as less hippocampal neuronal degeneration. The anti-neuroinflammatory effect of APC366 was abolished by AC55541, which when used alone, indeed further exacerbated neuroinflammation, hippocampal neuronal degeneration, and neurologic deficits following cardiac arrest. The deleterious effects aggregated by AC55541 were minimized by p38 inhibitor.

Conclusions

The inhibition of mast cell tryptase attenuated neuroinflammation, led to less hippocampal neuronal death and improved neurological deficits following cardiac arrest. This effect was at least partly mediated via inhibiting the PAR-2/p-p38/NFκB signaling pathway. Thus, mast cell tryptase might be a novel therapeutic target in the management of neurological impairment following cardiac arrest.

Neuroprotective effects of irisin against cerebral ischemia/ reperfusion injury via Notch signaling pathway

Irisin, a 112-amino acid peptide induced with exercise in mice and human is thought to have correlation with the short-term outcomes of patients in ischemic stroke. In the present study, the neuroprotective effects of irisin were evaluated in vivo and in vitro and its underlying mechanism was also explored. The global cerebral ischemia/reperfusion (I/R) model was established by bilateral common carotid artery occlusion for 20 min and reperfusion for 24 h in mice and oxygen-glucose deprivation/reperfusion in HT22 cells. Neurological function was scored and then the mice were sacrificed. The brains were harvested for HE staining and detection of brain water content (BWC). The percentage of neuronal apoptosis was evaluated by TUNEL and flow cytometry analysis. The mRNA expression of TNF-α and IL-1β was detected by RT-PCR analysis. The Notch intracellular domain (NICD) was detected by double immunofluorescence staining and western blot, and the protein expression of Notch1 and Hes 1 was detected by western blot. It was observed that irisin could alleviate morphological damage and improve neurological function after global cerebral I/R injury in mice. The apoptosis of hippocampal neurons reduced in the presence of irisin in vivo and in vitro. Additionally irisin could downregulate the expression of IL-1β and TNF-α and upregulate the expression of NICD, Notch1 and Hes 1 in vitro and in vivo. After the application of γ-secretase inhibitor DAPT, all the morphological, neurological and biochemical changes were reversed. Taken together, these results suggest that irisin could regulate the Notch signaling pathway that leads to the alleviation of transient global cerebral I/R injury.

HMGB1-triggered inflammation inhibition of notoginseng leaf triterpenes against cerebral ischemia and reperfusion injury via MAPK and NF-κB signaling pathways

Ischemic stroke is a clinically common cerebrovascular disease whose main risks include necrosis, apoptosis and cerebral infarction, all caused by cerebral ischemia and reperfusion (I/R) injury. This process has particular significance for the treatment of stroke patients. Notoginseng leaf triterpenes (PNGL), as a valuable medicine, have been discovered to have neuroprotective effects. However, it was not confirmed that whether PNGL may possess neuroprotective effects against cerebral I/R injury. To explore the neuroprotective effects of PNGL and their underlying mechanisms, a middle cerebral artery occlusion/reperfusion (MCAO/R) model was established. In vivo results suggested that in MCAO/R model rats, PNGL pretreatment (73.0, 146, 292 mg/kg) remarkably decreased infarct volume, reduced brain water content, and improved neurological functions; moreover, PNGL (73.0, 146, 292 mg/kg) significantly alleviated blood-brain barrier (BBB) disruption and inhibited neuronal apoptosis and neuronal loss caused by cerebral I/R injury, while PNGL with a different concertation (146, 292 mg/kg) significantly reduced the concentrations of IL-6, TNF-α, IL-1 β, and HMGB1 in serums in a dose-dependent way, which indicated that inflammation inhibition could be involved in the neuroprotective effects of PNGL. The immunofluorescence and western blot analysis showed PNGL decreased HMGB1 expression, suppressed the HMGB1-triggered inflammation, and inhibited microglia activation (IBA1) in hippocampus and cortex, thus dose-dependently downregulating inflammatory cytokines including VCAM-1, MMP-9, MMP-2, and ICAM-1 concentrations in ischemic brains. Interestingly, PNGL administration (146 mg/kg) significantly downregulated the levels of p-P44/42, p-JNK1/2 and p-P38 MAPK, and also inhibited expressions of the total NF-κB and phosphorylated NF-κB in ischemic brains, which was the downstream pathway triggered by HMGB1. All of these results indicated that the protective effects of PNGL against cerebral I/R injury could be associated with inhibiting HMGB1-triggered inflammation, suppressing the activation of MAPKs and NF-κB, and thus improved cerebral I/R-induced neuropathological changes. This study may offer insight into discovering new active compounds for the treatment of ischemic stroke.

Folic acid deficiency enhanced microglial immune response via the Notch1/nuclear factor kappa B p65 pathway in hippocampus following rat brain I/R injury and BV2 cells

Recent studies revealed that folic acid deficiency (FD) increased the likelihood of stroke and aggravated brain injury after focal cerebral ischaemia. The microglia-mediated inflammatory response plays a crucial role in the complicated pathologies that lead to ischaemic brain injury. However, whether FD is involved in the activation of microglia and the neuroinflammation after experimental stroke and the underlying mechanism is still unclear. The aim of the present study was to assess whether FD modulates the Notch1/nuclear factor kappa B (NF-κB) pathway and enhances microglial immune response in a rat middle cerebral artery occlusion-reperfusion (MCAO) model and oxygen-glucose deprivation (OGD)-treated BV-2 cells. Our results exhibited that FD worsened neuronal cell death and exaggerated microglia activation in the hippocampal CA1, CA3 and Dentate gyrus (DG) subregions after cerebral ischaemia/reperfusion. The hippocampal CA1 region was more sensitive to ischaemic injury and FD treatment. The protein expressions of proinflammatory cytokines such as tumour necrosis factor-α, interleukin-1β and interleukin-6 were also augmented by FD treatment in microglial cells of the post-ischaemic hippocampus and in vitro OGD-stressed microglia model. Moreover, FD not only dramatically enhanced the protein expression levels of Notch1 and NF-κB p65 but also promoted the phosphorylation of pIkBα and the nuclear translocation of NF-κB p65. Blocking of Notch1 with N-[N-(3, 5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester partly attenuated the nuclear translocation of NF-κB p65 and the protein expression of neuroinflammatory cytokines in FD-treated hypoxic BV-2 microglia. These results suggested that Notch1/NF-κB p65 pathway-mediated microglial immune response may be a molecular mechanism underlying cerebral ischaemia-reperfusion injury worsened by FD treatment.