Expression of human Ras-related protein Rab39B variant T168K in Caenorhabditis elegans leads to motor dysfunction and dopaminergic neuron degeneration.

Human RAB39B gene is related to familial early-onset Parkinson disease. In early adulthood, men with the RAB39B c.503C > A (Thr168Lys, p. T168K) mutation develop typical tremor, bradykinesia, and alpha-synuclein accumulation. We investigated the pathological mechanism of RAB39B T168K in a Caenorhabditis elegans model. In early adult C. elegans, RAB39B T168K led to dopaminergic neuron degeneration that presented as disrupted dendrites and blunt neuronal cells. Abnormal dopamine secretion was inferred from a decline in motor function and a positive basal slowing phenotype. Dopamine-associated tests confirmed that synthesis and recycling of dopamine were normal. The RAB39B T168K mutation might impair dopamine vesicular transmission from the presynaptic membrane to the synaptic gap in dopaminergic neurons. The release-dependent feedback mechanism in neurotransmitters regulates the balance of receptor activities. Protein-protein interactions network analysis revealed that RAB39B may also function in lysosomal degradation and autophagy. Impaired disposal of misfolded α-synuclein eventually leads to protein aggregation. Thus, like other members of the Rab family, RAB39B may be involved in vesicular transport associated with dopamine secretion and α-synuclein clearance.

Phosphorylation of AQP4 by LRRK2 R1441G impairs glymphatic clearance of IFNγ and aggravates dopaminergic neurodegeneration.

Aquaporin-4 (AQP4) is essential for normal functioning of the brain's glymphatic system. Impaired glymphatic function is associated with neuroinflammation. Recent clinical evidence suggests the involvement of glymphatic dysfunction in LRRK2-associated Parkinson's disease (PD); however, the precise mechanism remains unclear. The pro-inflammatory cytokine interferon (IFN) γ interacts with LRRK2 to induce neuroinflammation. Therefore, we examined the AQP4-dependent glymphatic system's role in IFNγ-mediated neuroinflammation in LRRK2-associated PD. We found that LRRK2 interacts with and phosphorylates AQP4 in vitro and in vivo. AQP4 phosphorylation by LRRK2 R1441G induced AQP4 depolarization and disrupted glymphatic IFNγ clearance. Exogeneous IFNγ significantly increased astrocyte expression of IFNγ receptor, amplified AQP4 depolarization, and exacerbated neuroinflammation in R1441G transgenic mice. Conversely, inhibiting LRRK2 restored AQP4 polarity, improved glymphatic function, and reduced IFNγ-mediated neuroinflammation and dopaminergic neurodegeneration. Our findings establish a link between LRRK2-mediated AQP4 phosphorylation and IFNγ-mediated neuroinflammation in LRRK2-associated PD, guiding the development of LRRK2 targeting therapy.

Cortical microinfarcts potentiate recurrent ischemic injury through NLRP3-dependent trained immunity.

Microinfarcts are common among the elderly and patients with microinfarcts are more vulnerable to another stroke. However, the impact of microinfarcts on recurrent stroke has yet to be fully understood. The purpose of this study was to explore the negative effects of microinfarcts on recurrent stroke. To achieve this, two-photon laser was used to induce microinfarcts, while photothrombotic stroke was induced on the opposite side. The results showed that microinfarcts led to trained immunity in microglia, which worsened the pro-inflammatory response and ischemic injury in the secondary photothrombotic stroke. Additionally, the study clarified the role of NLRP3 in microglial nuclei, indicating that it interacts with the MLL1 complex through NACHT domain and increases H3K4 methylation, which suggests that NLRP3 is critical in the formation of innate immune memory caused by microinfarcts. Furthermore, the knockout of NLRP3 in microglia alleviated the trained immunity and reduced the harmful effects of microinfarcts on recurrent stroke. This study emphasizes the detrimental effect of trained immunity on recurrent stroke and highlights the critical role of NLRP3 in mediating the formation of this memory, which may offer a potential therapeutic target for mitigating recurrent strokes.

Exogenous monocyte myeloid-derived suppressor cells ameliorate immune imbalance, neuroinflammation and cognitive impairment in 5xFAD mice infected with Porphyromonas gingivalis.

BACKGROUND: Periodontitis is closely associated with the pathogenesis of Alzheimer's disease (AD). Porphyromonas gingivalis (Pg), the keystone periodontal pathogen, has been reported in our recent study to cause immune-overreaction and induce cognitive impairment. Monocytic myeloid-derived suppressor cells (mMDSCs) possess potent immunosuppressive function. It is unclear whether mMDSCs-mediated immune homeostasis is impaired in AD patients with periodontitis, and whether exogenous mMDSCs could ameliorate immune-overreaction and cognitive impairment induced by Pg. METHODS: To explore the influence of Pg on cognitive function, neuropathology and immune balance in vivo, 5xFAD mice were treated with live Pg by oral gavage, three times a week for 1 month. The cells of peripheral blood, spleen and bone marrow from 5xFAD mice were treated with Pg to detect the proportional and functional alterations of mMDSCs in vitro. Next, exogenous mMDSCs were sorted from wild-type healthy mice and intravenously injected into 5xFAD mice that were infected with Pg. We used behavioral tests, flow cytometry and immunofluorescent staining to evaluate whether exogenous mMDSCs could ameliorate the cognitive function, immune homeostasis and reduce neuropathology exacerbated by Pg infection. RESULTS: Pg exacerbated cognitive impairment in 5xFAD mice, with the deposition of amyloid plaque and increased number of microglia in the hippocampus and cortex region. The proportion of mMDSCs decreased in Pg-treated mice. In addition, Pg reduced the proportion and the immunosuppressive function of mMDSCs in vitro. Supplement of exogenous mMDSCs improved the cognitive function, and enhanced the proportions of mMDSCs and IL-10+ T cells of 5xFAD mice infected with Pg. At the same time, supplement of exogenous mMDSCs increased the immunosuppressive function of endogenous mMDSCs while decreased the proportions of IL-6+ T cells and IFN-γ+ CD4+ T cells. In addition, the deposition of amyloid plaque decreased while the number of neurons increased in the hippocampus and cortex region after the supplement of exogenous mMDSCs. Furthermore, the number of microglia increased with an increase in the proportion of M2 phenotype. CONCLUSIONS: Pg can reduce the proportion of mMDSCs, induce immune-overreaction, and exacerbate the neuroinflammation and cognitive impairment in 5xFAD mice. Supplement of exogenous mMDSCs can reduce the neuroinflammation, immune imbalance and cognitive impairment in 5xFAD mice infected with Pg. These findings indicate the mechanism of AD pathogenesis and Pg-mediated promotion of AD, and provide a potential therapeutic strategy for AD patients.

Mutant VPS35-D620N induces motor dysfunction and impairs DAT-mediated dopamine recycling pathway.

The D620N mutation in vacuolar protein sorting protein 35 (VPS35) gene has been identified to be linked to late onset familial Parkinson disease (PD). However, the pathophysiological roles of VPS35-D620N in PD remain unclear. Here, we generated the transgenic Caenorhabditis elegans overexpressing either human wild type or PD-linked mutant VPS35-D620N in neurons. C. elegans expressing VPS35-D620N, compared with non-transgenic controls, showed movement disorders and dopaminergic neuron loss. VPS35-D620N worms displayed more swimming induced paralysis but showed no defects in BSR assays, thus indicating the disruption of dopamine (DA) recycling back inside neurons. Moreover, VPS35 formed a protein interaction complex with DA transporter (DAT), RAB5, RAB11 and FAM21. In contrast, the VPS35-D620N mutant destabilized these interactions, thus disrupting DAT transport from early endosomes to recycling endosomes, and decreasing DAT at the cell surface. These effects together increased DA in synaptic clefts, and led to dopaminergic neuron degeneration and motor dysfunction. Treatment with reserpine significantly decreased the swimming induced paralysis in VPS35-D620N worms, as compared with vehicle treated VPS35-D620N worms. Our studies not only provide novel insights into the mechanisms of VPS35-D620N-induced dopaminergic neuron degeneration and motor dysfunction via disruption of DAT function and the DA signaling pathway but also indicate a potential strategy to treat VPS35-D620N-related PD and other disorders.

Mettl5 mediated 18S rRNA N6-methyladenosine (m6A) modification controls stem cell fate determination and neural function.

Ribosome RNA (rRNA) accounts for more than 80% of the cell's total RNA, while the physiological functions of rRNA modifications are poorly understood. Mutations of 18S rRNA m6A methyltransferase METTL5 cause intellectual disability, microcephaly, and facial dysmorphisms in patients, however, little is known about the underlying mechanisms. In this study, we identified METTL5 protein complex and revealed that METTL5 mainly interacts with RNA binding proteins and ribosome proteins. Functionally, we found that Mettl5 knockout in mESCs leads to the abnormal craniofacial and nervous development. Moreover, using Mettl5 knockout mouse model, we further demonstrated that Mettl5 knockout mice exhibit intellectual disability, recapitulating the human phenotype. Mechanistically, we found that Mettl5 maintains brain function and intelligence by regulating the myelination process. Our study uncovered the causal correlation between mis-regulated 18S rRNA m6A modification and neural function defects, supporting the important physiological functions of rRNA modifications in human diseases.

Porphyromonas gingivalis-Induced Cognitive Impairment Is Associated With Gut Dysbiosis, Neuroinflammation, and Glymphatic Dysfunction.

Background: Periodontal pathogen and gut microbiota are closely associated with the pathogenesis of Alzheimer's disease (AD). Porphyromonas gingivalis (Pg), the keystone periodontal pathogen, can induce cognitive impairment. The gut has a connection and communication with the brain, which is an important aspect of the gut-brain axis (GBA). In the present study, we investigate whether Pg induces cognitive impairment through disturbing the GBA. Methods: In this study, Pg was orally administered to mice, three times a week for 1 month. The effects of Pg administration on the gut and brain were evaluated through behaviors, gut microbiota, immune cells, glymphatic pathway clearance, and neuroinflammation. Results: Pg induced cognitive impairment and dysbiosis of gut microbiota. The α-diversity parameters did not show significant change after Pg administration. The ß-diversity demonstrated that the gut microbiota compositions were different between the Pg-administered and control groups. At the species level, the Pg group displayed a lower abundance of Parabacteroides gordonii and Ruminococcus callidus than the control group, but a higher abundance of Mucispirillum schaedleri. The proportions of lymphocytes in the periphery and myeloid cells infiltrating the brain were increased in Pg-treated animals. In addition, the solute clearance efficiency of the glymphatic system decreased. Neurons in the hippocampus and cortex regions were reduced in mice treated with Pg. Microglia, astrocytes, and apoptotic cells were increased. Furthermore, amyloid plaque appeared in the hippocampus and cortex regions in Pg-treated mice. Conclusions: These findings indicate that Pg may play an important role in gut dysbiosis, neuroinflammation, and glymphatic system impairment, which may in turn lead to cognitive impairment.

Mutations of RNF213 are responsible for sporadic cerebral cavernous malformation and lead to a mulberry-like cluster in zebrafish.

Although familial forms of cerebral cavernous malformation are mainly attributed to three CCM genes (KRIT1, CCM2 and PDCD10), no mutation is identified in sporadic cerebral cavernous malformation cases with a unique lesion, indicating additional genes for sporadic cerebral cavernous malformation. To screen the candidate genes, we conducted whole exome sequencing in 31 sporadic cerebral cavernous malformation patients and 32 healthy controls, and identified 5 affected individuals carrying 6 heterozygous deleterious mutations in RNF213 but no RNF213 mutation in healthy individuals. To further confirm RNF213 was associated with cerebral cavernous malformation, we generated rnf213a homozygous knockout zebrafish and found mutation of rnf213a in zebrafish led to a mulberry-like cluster of disordered-flow vascular channels which was reminiscent of human cerebral cavernous malformation. In addition, we revealed kbtbd7 and anxa6 were significantly downregulated due to rnf213a mutation through transcriptomic sequencing and RT-qPCR analysis. Based on the mulberry-like phenotype partly rescued by mRNA of kbtbd7 as well as anxa6, we suggested that rnf213a promoted mulberry-like cluster via downregulation of kbtbd7 and anxa6. Altogether, we firstly demonstrate RNF213is a novel candidate gene for sporadic cerebral cavernous malformation and the mutation of rnf213a is responsible for the mulberry-like cluster in zebrafish.

Oral P. gingivalis impairs gut permeability and mediates immune responses associated with neurodegeneration in LRRK2 R1441G mice.

BACKGROUND: The R1441G mutation in the leucine-rich repeat kinase 2 (LRRK2) gene results in late-onset Parkinson's disease (PD). Peripheral inflammation and gut microbiota are closely associated with the pathogenesis of PD. Chronic periodontitis is a common type of peripheral inflammation, which is associated with PD. Porphyromonas gingivalis (Pg), the most common bacterium causing chronic periodontitis, can cause alteration of gut microbiota. It is not known whether Pg-induced dysbiosis plays a role in the pathophysiology of PD. METHODS: In this study, live Pg were orally administrated to animals, three times a week for 1 month. Pg-derived lipopolysaccharide (LPS) was used to stimulate mononuclear cells in vitro. The effects of oral Pg administration on the gut and brain were evaluated through behaviors, morphology, and cytokine expression. RESULTS: Dopaminergic neurons in the substantia nigra were reduced, and activated microglial cells were increased in R1441G mice given oral Pg. In addition, an increase in mRNA expression of tumor necrosis factor (TNF-α) and interleukin-1ß (IL-1ß) as well as protein level of α-synuclein together with a decrease in zonula occludens-1 (Zo-1) was detected in the colon in Pg-treated R1441G mice. Furthermore, serum interleukin-17A (IL-17A) and brain IL-17 receptor A (IL-17RA) were increased in Pg-treated R1441G mice. CONCLUSIONS: These findings suggest that oral Pg-induced inflammation may play an important role in the pathophysiology of LRRK2-associated PD.

hUCMSCs Mitigate LPS-Induced Trained Immunity in Ischemic Stroke.

Innate immune memory is a part of the innate immune system that facilitates the elimination of pathogens. However, it may exacerbate neuropathology. In this study, we found that innate immune memory is detrimental in stroke, because it promotes the acute immune response and exacerbates ischemic infarcts. Mesenchymal stem cell therapy has been widely studied for its therapeutic potential in various diseases including stroke, but whether it diminishes innate immune memory has not been studied. Here, our study demonstrates that, after the activation of innate immune memory by lipopolysaccharide, mesenchymal stem cell therapy can diminish innate immune memory though down-regulation of H3 methylation and subsequently protect against stroke. Our results demonstrate that innate immune memory is detrimental in stroke, and we describe a novel potential therapeutic target involving the use of mesenchymal stem cells to treat stroke patients.

Overexpression of Slit2 decreases neuronal excitotoxicity, accelerates glymphatic clearance, and improves cognition in a multiple microinfarcts model.

BACKGROUND: Cerebral microinfarcts (MIs) lead to progressive cognitive impairments in the elderly, and there is currently no effective preventative strategy due to uncertainty about the underlying pathogenic mechanisms. One possibility is the dysfunction of GABAergic transmission and ensuing excitotoxicity. Dysfunction of GABAergic transmission induces excitotoxicity, which contributes to stroke pathology, but the mechanism has kept unknown. The secreted leucine-rich repeat (LRR) family protein slit homologue 2 (Slit2) upregulates GABAergic activity and protects against global cerebral ischemia, but the neuroprotective efficacy of Slit2 against MIs has not been examined. METHODS: Middle-aged Wild type (WT) and Slit2-Tg mice were divided into sham and MI treatment groups. MIs were induced in parietal cortex by laser-evoked arteriole occlusion. Spatial memory was then compared between sham and MI groups using the Morris water maze (MWM) task. In addition, neuronal activity, blood brain barrier (BBB) permeability, and glymphatic clearance in peri-infarct areas were compared using two-photon imaging, while GABAergic transmission, microglial activation, neuronal loss, and altered cortical connectivity were compared by immunofluorescent staining or western blotting. RESULTS: Microinfarcts increased the amplitude and frequency of spontaneous intracellular Ca2+ signals, reduced neuronal survival and connectivity within parietal cortex, decreased the number of GABAergic interneurons and expression of vesicular GABA transporter (VGAT), induced neuroinflammation, and impaired both glymphatic clearance and spatial memory. Alternatively, Slit2 overexpression attenuated dysfunctional neuronal Ca2+ signaling, protected against neuronal death in the peri-infarct area as well as loss of parietal cortex connectivity, increased GABAergic interneuron number and VGAT expression, attenuated neuroinflammation, and improved both glymphatic clearance and spatial memory. CONCLUSION: Our results strongly suggest that overexpression of Slit2 protected against the dysfunction in MIs, which is a potential therapeutic target for cognition impairment in the elderly.

Continuous theta burst stimulation dilates meningeal lymphatic vessels by up-regulating VEGF-C in meninges.

BACKGROUND: Lymphatic vessels (LVs) of meninges and lymphatic drainage in the brain have been investigated previously. Here, we examined the role of continuous theta burst stimulation (CTBS) in the modulation of meningeal LVs. METHODS: To explore the effects of CTBS on meningeal LVs, the diameters of LVs were measured between a real CTBS group and sham CTBS group of wild-type male mice. Vascular endothelial growth factor-C (VEGF-C) expression was subsequently calculated in both groups to account for lymphatic changes after CTBS. Sunitinib was administered by 3-day oral gavage to inhibit the VEGF receptor (VEGFR), and the effects of CTBS were further examined in the following groups: vehicle with real CTBS, vehicle with sham CTBS, sunitinib treatment with real CTBS, and sunitinib treatment with sham CTBS. RESULTS: The lymphatic vessels were augmented, and the level of VEGF-C in meninges increased after CTBS. CTBS dilated meningeal lymphatic vessels were impaired after the VEGF-C/VEGFR3 pathway was blocked. CONCLUSIONS: CTBS can dilate meningeal lymphatic vessels by up-regulating VEGF-C in meninges.

Rational Design of Cyclometalated Iridium(III) Complexes for Three-Photon Phosphorescence Bioimaging.

Compared to 2PE (two-photon excitation) microscopy, 3PE microscopy has superior spatial resolution, deeper tissue penetration, and less defocused interference. The design of suitable agents with a large Stokes shift, good three-photon absorption (3PA), subcellular targeting, and fluorescence lifetime imaging (FLIM) properties, is challenging. Now, two IrIII complexes (3PAIr1 and 3PAIr2) were developed as efficient three-photon phosphorescence (3PP) agents. Calculations reveal that the introduction of a new group to the molecular scaffold confers a quadruple promotion in three-photon transition probability. Confocal and lifetime imaging of mitochondria using IrIII complexes as 3PP agents is shown. The complexes exhibit low working concentration (50 nm), fast uptake (5 min), and low threshold for three-photon excitation power (0.5 mW at 980 nm). The impressive tissue penetration depth (ca. 450 µm) allowed the 3D imaging and reconstruction of brain vasculature from a living specimen.

Extracellular ASC exacerbated the recurrent ischemic stroke in an NLRP3-dependent manner.

Using a photothrombotic mouse model of single stroke, we show that a single stroke onset increases the nuclear factor-κB (NF-κB), NLR family CARD domain containing protein 4 (NLRC4), and absent in melanoma 2 (AIM2) inflammasomes, as well as the mRNA levels of NLRP3. Next, using a photothrombotic mouse model of recurrent stroke, we found that recurrent strokes increased the activation of NLRP3, exacerbated the brain damage and the pro-inflammatory response in wild type (WT) mice, but not in NLRP3 knockout (NLRP3 KO) mice. Additionally, we found that apoptosis-associated speck-like protein containing a CARD (ASC) protein level surrounding the infarct area was comparatively increased, but that ASC specks outside of microglia in both the ipsilateral and contralateral of stroke site were decreased in NLRP3 KO mice relative to wild-type (WT) controls, and the number of ASC specks surrounding the second infarct area was positively correlated to the damage scores. Mechanistically, we found that recombinant ASC (RecASC) activated NLRP3 and induced pro-inflammatory responses, exacerbating the outcome of ischemic stroke, in WT mice, but not in NLRP3 KO mice. We therefore conclude that the NLRP3 inflammasome is activated by two attacks of stroke, which act together with ASC to exacerbate recurrent strokes.

Continuous theta burst stimulation provides neuroprotection by accelerating local cerebral blood flow and inhibiting inflammation in a mouse model of acute ischemic stroke.

Acute ischemic stroke is a leading cause of disability with limited therapeutic options. Continuous theta burst stimulation (cTBS) has recently been shown to be a promising noninvasive therapeutic strategy for neuroprotection in ischemic stroke patients. Here, we investigated the protective effects of cTBS following acute infarction using a photothrombotic stroke (PTS) model in the right posterior parietal cortex (PPC) of C57BL/6 mice. Treatment with cTBS resulted in a reduction in the volume of the infarct region and significantly increased vascular diameter and blood flow velocity in peri-infarct region, as well as decreased the numbers of calcium binding adapter molecule 1 (Iba-1)-positive microglia and glial fibrillary acidic protein (GFAP)-positive astrocytes. Moreover, the number of CD16/32 positive microglia was decreased, whereas the number of CD206 positive microglia was increased. In addition, performance in a water maze task was significantly improved. These results indicated that cTBS protected against PPC infarct region, leading to an improvement in spatial cognitive function, possibly as a result of changes to cerebral microvascular function and inflammatory responses.

Mesenchymal stem cells alleviate AQP-4-dependent glymphatic dysfunction and improve brain distribution of antisense oligonucleotides in BACHD mice.

Huntington's disease (HD) is a neurodegenerative disorder caused by a mutation in the huntingtin (HTT) gene that results in the production of neurotoxic mutant HTT (mHTT) protein. Suppressing HTT production with antisense oligonucleotides (ASOs) is a promising treatment strategy for HD; however, the difficulty of delivering ASOs to deep brain structures is a major barrier for its clinical application. The glymphatic system of astrocytes involving aquaporin 4 (AQP-4) controls the entry of macromolecules from the cerebrospinal fluid into the brain. Mesenchymal stem cells (MSCs) target astrocytes to inhibit neuroinflammation. Here we examined the glymphatic distribution of ASO in the brain and the therapeutic potential of combining intravenously injection of mesenchymal stem cells (IV-MSC) and ASOs for the treatment of HD. Our results show that Cy3-labeled ASOs entered the brain parenchyma via the perivascular space following cisternal injection, but the brain distribution was significantly lower in AQP-4-/- as compared with wild-type mice. Downregulation of the AQP-4 M23 isoform was accompanied by decreased brain levels of ASOs in BACHD mice as well as an increase in astrogliosis and phosphorylation of nuclear factor κB (NF-κB) p65. IV-MSC treatment restored AQP-4 M23 expression, attenuated astrogliosis, and decreased NF-κB p65 phosphorylation; it also increased the brain distribution of ASOs and enhanced the suppression of mHTT in BACHD mice. These results suggest that modulating glymphatic activity using IV-MSC is a novel strategy for improving the potency of ASO in the treatment of HD.

Phasic GABA signaling mediates the protective effects of cTBS against cerebral ischemia in mice.

Continuous theta burst stimulation (cTBS) has been widely recognized as a therapeutic treatment for ischemic stroke, but the underlying mechanism is still elusive. Here, we investigated the protective effects of cTBS in the posterior parietal cortex during the chronic phase of stroke in the photothrombotic ischemic model. Infarction volume and neuron excitability in the peri-infarct area were assessed using immunohistochemistry and whole-cell patch-clamp. Spatial cognitive function was measured using the Morris water maze. Gamma-Amino butyric acid (GABA) interneurons were responsive to cTBS, and cTBS induced elevated phasic inhibition rather than tonic inhibition. Given that GABA-A-mediated phasic inhibition was elevated during the chronic phase of ischemic stroke for 30 days and was beneficial for stroke recovery, we investigated the therapeutic potential of cTBS in promoting functional recovery and found that the elevated phasic inhibition by cTBS improved spatial cognitive function in the photothrombotic stroke mouse model with induction in the posterior parietal cortex. Our study indicates the mechanism by which cTBS may modify the excitability of the brain cortex and provides novel insight into the potential of cTBS to protect against neuronal dysfunction in ischemic stroke.

Increased cortical infarction and neuroinflammation in ischemic stroke mice with experimental periodontitis.

Ischemic stroke is a common life-threatening disease. Epidemiological studies have shown that chronic periodontitis is closely related to ischemic stroke. However, it remains unknown whether periodontitis plays a direct role in the injury of cerebral ischemia. To explore the role of chronic periodontitis in the development process of ischemic stroke, we combined two mouse models: experimental periodontitis induced by a periodontal injection of lipopolysaccharide and ischemic stroke induced by the photothrombotic method. Alveolar bone loss and inflammatory infiltration of the periodontal tissue were found in the mice with experimental periodontitis. Periodontitis significantly increased the infarction volume, and numbers of activated microglia and astrocytes. Furthermore, an increased expression of nod-like receptor protein 3 inflammasome and interleukin-1ß was detected in the peri-infarct region. We drew a conclusion that chronic periodontitis exacerbated ischemic stroke by increasing the activation of microglia/astrocytes and the expression of nod-like receptor protein 3 inflammasome and interleukin-1ß. This suggested that chronic periodontitis played a role in ischemic brain injury directly through exacerbating the inflammation of the damaged brain.

Xyloketal derivative C53N protects against mild traumatic brain injury in mice.

PURPOSE: Mild traumatic brain injury (mTBI), the most common type of TBI, can result in prolonged cognitive impairment, mood disorders, and behavioral problems. Reducing oxidative stress and inflammation can rescue the neurons from mTBI-induced cell death. Xyloketal B, a natural product from mangrove fungus, has shown good antioxidative and neuroprotective effects in several disease models. Here, we investigated the potential protection afforded by a xyloketal derivative, C53N, in a closed-skull mTBI model. MATERIALS AND METHODS: Skulls of mice were thinned to 20-30 µm thickness, following which they were subjected to a slight compression injury to induce mTBI. One hour after TBI, mice were intraperitoneally injected with C53N, which was solubilized in 0.5% dimethyl sulfoxide in saline. In vivo two-photon laser scanning microscopy was used to image cell death in injured parenchyma in each mouse over a 12-hour period (at 1, 3, 6, and 12 hours). Water content and oxidation index, together with pathological analysis of glial reactivity, were assessed at 24 hours to determine the effect of C53N on mTBI. RESULTS: Cell death, oxidative stress, and glial reactivity increased in mTBI mice compared with sham-injured mice. Treatment with 40 or 100 mg/kg C53N 1 hour after mTBI significantly attenuated oxidative stress and glial reactivity and reduced parenchymal cell death at the acute phase after mTBI. CONCLUSION: The present study highlights the therapeutic potential of the xyloketal derivative C53N for pharmacological intervention in mTBI.

Chronic colitis induces meninges traffic of gut-derived T cells, unbalances M1 and M2 microglia/macrophage and increases ischemic brain injury in mice.

Ischemic stroke is one of the most common diseases leading to death and is the primary cause of physical handicap. Recent studies have reported that chronic colitis increases the risk of ischemic stroke, but it is unknown whether chronic colitis participates in ischemic brain injury directly. A combined mouse model of chronic colitis induced by dextran sodium sulfate (DSS) and ischemic stroke induced by photochemical infarction was used in this study. We demonstrated that chronic colitis significantly increased the infarction volume, activated microglia/macrophage numbers, proliferation of M1 microglia/macrophage, non-gut-derived CD4+ T lymphocyte penetration and decreased neuron numbers in the peri-infarction at 7 d after stroke. Furthermore, gut-derived CD4+ T cell accumulation on the meninges was observed at 7 d after stroke. In addition, selective depletion of meningeal macrophages resulted in a reduction of infarction volume and the non-gut-derived CD4+ T lymphocyte penetration. We concluded that chronic colitis exacerbated ischemic stroke by promoting CD4+ T cell migration from the gut to the meninges and disequilibrium of M1 and M2 microglia/macrophages. We speculated that the gut-derived CD4+ T cells may interact with meningeal macrophages and result in non-gut-derived CD4+ T lymphocyte infiltration that aggravated brain injury in ischemic stroke.