Positive Effect of 6-Gingerol on Functional Plasticity of Microglia in a rat Model of LPS-induced Depression.

Neuroinflammation has emerged as a crucial factor in the development of depression. Despite the well-known anti-inflammatory properties of 6-gingerol, its potential impact on depression remains poorly understood. This study aimed to investigate the antidepressant effects of 6-gingerol by suppressing microglial activation. In vivo experiments were conducted to evaluate the effect of 6-gingerol on lipopolysaccharide (LPS)-induced behavioral changes and neuroinflammation in rat models. In vitro studies were performed to examine the neuroprotective properties of 6-gingerol against LPS-induced microglial activation. Furthermore, a co-culture system of microglia and neurons was established to assess the influence of 6-gingerol on the expression of synaptic-related proteins, namely synaptophysin (SYP) and postsynaptic density protein 95 (PSD95), which are influenced by microglial activation. In the in vivo experiments, administration of 6-gingerol effectively alleviated LPS-induced depressive behavior in rats. Moreover, it markedly suppressed the activation of rat prefrontal cortex (PFC) microglia induced by LPS and the activation of the NF-κB/NLRP3 inflammatory pathway, while also reducing the levels of inflammatory cytokines IL-1ß and IL-18. In the in vitro experiments, 6-gingerol mitigated nuclear translocation of NF-κB p65, NLRP3 activation, and maturation of IL-1ß and IL-18, all of which were induced by LPS. Furthermore, in the co-culture system of microglia and neurons, 6-gingerol effectively restored the decreased expression of SYP and PSD95. The findings of this study demonstrate the neuroprotective effects of 6-gingerol in the context of LPS-induced depression-like behavior. These effects are attributed to the inhibition of microglial hyperactivation through the suppression of the NF-κB/NLRP3 inflammatory pathway.

A Pilot Study on a Possible Mechanism behind Olfactory Dysfunction in Parkinson's Disease: The Association of TAAR1 Downregulation with Neuronal Loss and Inflammation along Olfactory Pathway.

Parkinson's disease (PD) is characterized not only by motor symptoms but also by non-motor dysfunctions, such as olfactory impairment; the cause is not fully understood. Our study suggests that neuronal loss and inflammation in brain regions along the olfactory pathway, such as the olfactory bulb (OB) and the piriform cortex (PC), may contribute to olfactory dysfunction in PD mice, which might be related to the downregulation of the trace amine-associated receptor 1 (TAAR1) in these areas. In the striatum, although only a decrease in mRNA level, but not in protein level, of TAAR1 was detected, bioinformatic analyses substantiated its correlation with PD. Moreover, we discovered that neuronal death and inflammation in the OB and the PC in PD mice might be regulated by TAAR through the Bcl-2/caspase3 pathway. This manifested as a decrease of anti-apoptotic protein Bcl-2 and an increase of the pro-apoptotic protein cleaved caspase3, or through regulating astrocytes activity, manifested as the increase of TAAR1 in astrocytes, which might lead to the decreased clearance of glutamate and consequent neurotoxicity. In summary, we have identified a possible mechanism to elucidate the olfactory dysfunction in PD, positing neuronal damage and inflammation due to apoptosis and astrocyte activity along the olfactory pathway in conjunction with the downregulation of TAAR1.

Neuregulin 4 (Nrg4) cooperates with melatonin to regulate the PRL expression via ErbB4/Erk signaling pathway as a potential prolactin (PRL) regulator.

Neuregulin-4 (Nrg4) and melatonin play vital roles in endocrine diseases. However, there is little discussion about the function and potential mechanism of Nrg4 and melatonin in prolactin (PRL) regulation. The human normal pituitary data from Gene Expression Profiling Interactive Analysis (GEPIA) database was used to explore the correlation between NRG4 and PRL. The expression and correlation of NRG4 and PRL were determined by Immunofluorescence staining (IF) and human normal pituitary tissue microarray. Western Blot (WB) was used to detect the expression of PRL, p-ErbB2/3/4, ErbB2/3/4, p-Erk1/2, Erk1/2, p-Akt and Akt in PRL-secreting pituitary GH3 and RC-4B/C cells treated by Nrg4, Nrg4-small interfering RNA, Erk1/2 inhibitor FR180204 and melatonin. The expression of NRG4 was significantly positively correlated with that of PRL in the GEPIA database and normal human pituitary tissues. Nrg4 significantly increased the expression and secretion of PRL and p-Erk1/2 expression in GH3 cells and RC-4B/C cells. Inhibition of Nrg4 significantly inhibited PRL expression. The increased levels of p-Erk1/2 and PRL induced by Nrg4 were abolished significantly in response to FR180204 in GH3 and RC-4B/C cells. Additionally, Melatonin promotes the expression of Nrg4, p-ErbB4, p-Erk1/2, and PRL and can further promote the expression of p-Erk1/2 and PRL in combination with Nrg4. Further investigation into the function of Nrg4 and melatonin on PRL expression and secretion may provide new clues to advance the clinical control of prolactinomas and hyperprolactinemia.

Akkermansia muciniphila Is Beneficial to a Mouse Model of Parkinson's Disease, via Alleviated Neuroinflammation and Promoted Neurogenesis, with Involvement of SCFAs.

Increasing evidence suggests that the gut microbiota may represent potential strategies for Parkinson's disease (PD) treatment. Our previous research revealed a decreased abundance of Akkermansia muciniphila (Akk) in PD mice; however, whether Akk is beneficial to PD is unknown. To answer this question, the mice received MPTP intraperitoneally to construct a subacute model of PD and were then supplemented with Akk orally for 21 consecutive days. Motor function, dopaminergic neurons, neuroinflammation, and neurogenesis were examined. In addition, intestinal inflammation, and serum and fecal short-chain fatty acids (SCFAs) analyses, were assessed. We found that Akk treatment effectively inhibited the reduction of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and partially improved the motor function in PD mice. Additionally, Akk markedly alleviated neuroinflammation in the striatum and hippocampus and promoted hippocampal neurogenesis. It also decreased the level of colon inflammation. Furthermore, these aforementioned changes are mainly accompanied by alterations in serum and fecal isovaleric acid levels, and lower intestinal permeability. Our research strongly suggests that Akk is a potential neuroprotective agent for PD therapy.

Reducing polypyrimidine tract­binding protein 1 fails to promote neuronal transdifferentiation on HT22 and mouse astrocyte cells under physiological conditions.

In contrast to prior findings that have illustrated the conversion of non-neuronal cells into functional neurons through the specific targeting of polypyrimidine tract-binding protein 1 (PTBP1), accumulated evidence suggests the impracticality of inducing neuronal transdifferentiation through suppressing PTBP1 expression in pathological circumstances. Therefore, the present study explored the effect of knocking down PTBP1 under physiological conditions on the transdifferentiation of mouse hippocampal neuron HT22 cells and mouse astrocyte (MA) cells. A total of 20 µM negative control small interfering (si)RNA and siRNA targeting PTBP1 were transfected into HT22 and MA cells using Lipo8000™ for 3 and 5 days, respectively. The expression of early neuronal marker ßIII-Tubulin and mature neuronal markers NeuN and microtubule-associated protein 2 (MAP2) were detected using western blotting. In addition, ßIII-tubulin, NeuN and MAP2 were labeled with immunofluorescence staining to evaluate neuronal cell differentiation in response to PTBP1 downregulation. Under physiological conditions, no significant changes in the expression of ßIII-Tubulin, NeuN and MAP2 were found after 3 and 5 days of knockdown of PTBP1 protein in both HT22 and MA cells. In addition, the immunofluorescence staining results showed no apparent transdifferentiation in maker levels and morphology. The results suggested that the knockdown of PTBP1 failed to induce neuronal differentiation under physiological conditions.

5-HT4 Receptor is Protective for MPTP-induced Parkinson's Disease Mice Via Altering Gastrointestinal Motility or Gut Microbiota.

Serotonergic dysfunction is related to both motor and nonmotor symptoms in Parkinson's disease (PD). As a 5-HT receptor, 5-HT4 receptor (5-HT4R) is well-studied and already-used in clinical therapy of constipation, which is a typical non-motor symptom in PD. In this study, we investigated the role of 5-HT4R as a regulator of gut function in MPTP-induced acute PD mice model. Daily intraperitoneal injection of GR 125487 (5-HT4R antagonist) was administered 3 days before MPTP treatment until sacrifice. Seven days post-MPTP treatment, feces were collected and gastrointestinal transit time (GITT) was measured, 8 days post-MPTP treatment, behavioral tests were performed, and then animals were sacrificed for the further analysis. We found GR 125487 pretreatment not only increased GITT, but also aggravated MPTP-induced motor bradykinesia. In addition, GR 125487 pretreatment exacerbated the loss of dopaminergic neurons probably by suppressing JAK2/PKA/CREB signaling pathway and increased reactive glia and neuroinflammation in the striatum. 16 S rRNA sequencing of fecal microbiota showed that GR 125487 pretreatment altered the composition of gut microbiota, in which the abundance of Akkermansia muciniphila and Clostridium clostridioforme was increased, whereas that of Parabacteroides distasonis and Bacteroides fragilis was decreased, which are closely associated with inflammation condition. Taken together, we demonstrated that GR 125487 pretreatment exacerbates MPTP-induced striatal neurodegenerative processes possibly via the JAK2/PKA/CREB pathway and neuroinflammation by altering gut microbiota composition. In the microbiota-gut-brain axis of PD, 5-HT4R should be further explored and might serve as a target for PD diagnosis and treatment.

Research on ferroptosis as a therapeutic target for the treatment of neurodegenerative diseases.

Ferroptosis is an iron- and lipid peroxidation (LPO)-mediated programmed cell death type. Recently, mounting evidence has indicated the involvement of ferroptosis in neurodegenerative diseases, especially in Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and so on. Treating ferroptosis presents opportunities as well as challenges for neurodegenerative diseases. This review provides a comprehensive overview of typical features of ferroptosis and the underlying mechanisms that contribute to its occurrence, as well as their implications in the pathogenesis and advancement of major neurodegenerative disorders. Meanwhile, we summarize the utilization of ferroptosis inhibition in both experimental and clinical approaches for the treatment of major neurodegenerative disorders. In addition, we specifically summarize recent advances in developing therapeutic means targeting ferroptosis in these diseases, which may guide future approaches for the effective management of these devastating medical conditions.

Fecal Microbiota Transplantation from Aged Mice Render Recipient Mice Resistant to MPTP-Induced Nigrostriatal Degeneration Via a Neurogenesis-Dependent but Inflammation-Independent Manner.

Accumulating data support a crucial role of gut microbiota in Parkinson's disease (PD). However, gut microbiota vary with age and, thus, will affect PD in an age-dependent, but unknown manner. We examined the effects of fecal microbiota transplantation (FMT) pretreatment, using fecal microbiota from young (7 weeks) or aged mice (23 months), on MPTP-induced PD model. Motor function, pathological changes, striatal neurotransmitters, neuroinflammation, gut inflammation and gut permeability were examined. Gut microbiota composition and metabolites, namely short-chain fatty acids (SCFAs), were analyzed. Neurogenesis was also evaluated by measuring the number of doublecortin-positive (DCX+) neurons and Ki67-positive (Ki67+) cells in the hippocampus. Expression of Cd133 mRNA, a cellular stemness marker, in the hippocampus was also examined. Mice who received FMT from young mice showed MPTP-induced motor dysfunction, and reduction of striatal dopamine (DA), dopaminergic neurons and striatal tyrosine hydroxylase (TH) levels. Interestingly and unexpectedly, mice that received FMT from aged mice showed recovery of motor function and rescue of dopaminergic neurons and striatal 5-hydroxytryptamine (5-HT), as well as decreased DA metabolism after MPTP challenge. Further, they showed improved metabolic profiling and a decreased amount of fecal SCFAs. High-throughput sequencing revealed that FMT remarkably reshaped the gut microbiota of recipient mice. For instance, levels of genus Akkermansia and Candidatus Saccharimonas were elevated in fecal samples of recipient mice receiving aged microbiota (AM + MPTP mice) than YM + MPTP mice. Intriguingly, both young microbiota and aged microbiota had no effect on neuroinflammation, gut inflammation or gut permeability. Notably, AM + MPTP mice showed a marked increase in DCX+ neurons, as well as Ki67+ cells and Cd133 expression in the hippocampal dentate gyrus (DG) compared to YM + MPTP mice. These results suggest that FMT from aged mice augments neurogenesis, improves motor function and restores dopaminergic neurons and neurotransmitters in PD model mice, possibly through increasing neurogenesis.

Multifunctional High Entropy Alloys Enabled by Severe Lattice Distortion.

Since 2004, the design of high entropy alloys (HEAs) has generated significant interest within the materials science community due to their exceptional structural and functional properties. By incorporating multiple principal elements into a common lattice, it is possible to create a single-phase crystal with a highly distorted lattice. This unique feature enables HEAs to offer a promising combination of mechanical and physical properties that are not typically observed in conventional alloys. In this article, an extensive overview of multifunctional HEAs that exhibit severe lattice distortion is provided, covering the theoretical models that are developed to understand lattice distortion, the experimental and computational methods employ to characterize lattice distortion, and most importantly, the impact of severe lattice distortion on the mechanical, physical and electrochemical properties of HEAs. Through this review, it is hoped to stimulate further research into the study of distorted lattices in crystalline solids.

A prognostic biomarker NRG1 promotes U-87 MG glioblastoma cell malignancy by inhibiting autophagy via ERBB2/AKT/mTOR pathway.

Glioblastoma (GBM) is the most common and aggressive primary brain malignancy. Studies have shown that autophagy-related (ATG) genes play important roles in regulating GBM malignancy. However, the mechanism still needs to be fully elucidated. Based on clinical and gene expression information of GBM patients downloaded from The The Cancer Genome Atlas database, Kaplan-Meier, univariate Cox regression, least absolute shrinkage and selection operator regression and multivariate Cox regression were applied to construct a risk signature for GBM prognosis, followed by validation using receiver operating characteristic analysis. Next, Cell Counting Kit-8, wound healing assay, flow cytometry, monodansyl cadaverine autophagy staining assay, immunofluorescence staining and western blot, either in the absence or presence of ERBB2/AKT/mTOR inhibitors, were carried out in GBM U87 cell line to explore molecular pathway underlying GBM malignancy. A three-ATG-gene signature (HIF1A, ITGA3, and NGR1) was constructed for GBM prognosis with the greatest contribution from NRG1. In vitro experiments showed that NRG1 promoted U87 cell migration and proliferation by inhibiting autophagy, and ERBB2/AKT/mTOR is a downstream pathway that mediates the autophagy-inhibitory effects of NRG1. We constructed an ATG gene prognostic model for GBM and demonstrated that NRG1 inhibited autophagy by activating ERBB2/AKT/mTOR, promoting GBM malignancy, thus providing new insights into the molecular contribution of autophagy in GBM malignancy.

Involvement of CXCL10 in Neuronal Damage under the Condition of Spinal Cord Injury and the Potential Therapeutic Effect of Nrg1.

OBJECTIVE: Few studies have reported the direct effect of C-X-C motif chemokine ligand 10 (CXCL10) and Neuregulin 1 (Nrg1) on neurons after spinal cord injury (SCI). This study reports the role of CXCL10 in the regulation of neuronal damage after SCI and the potential therapeutic effect of Nrg1. METHODS: The expression level of CXCL10 and Nrg1 in SCI mice was analyzed in the Gene Expression Omnibus DataSets, followed by immunohistochemical confirmation using a mouse SCI model. HT22 cells and NSC34 cells were treated with CXCL10 and Nrg1, individually or in combination, and then assayed for cell viability. The percentage of wound closure was determined through the cell scratch injury model using HT22 and NSC34 cells. Potential molecular mechanisms were also tested in response to either the individual administration of CXCL10 and Nrg1 or a mixture of both molecules. RESULTS: CXCL10 expression was significantly increased in both young and old mice subjected to SCI, while Nrg1 expression was significantly decreased. CXCL10 induced a decrease in cell viability, which was partially reversed by Nrg1. CXCL10 failed to inhibit scratch healing in HT22 and NSC34 cells, while Nrg1 promoted scratch healing. At the molecular level, CXCL10-activated cleaved caspase 9 and cleaved caspase 3 were both inhibited by Nrg1 through pERK1/2 signaling in HT22 and NSC34 cells. CONCLUSIONS: CXCL10 is upregulated in SCI. Despite the negative effect on cell viability, CXCL10 failed to inhibit the scratch healing of HT22 and NSC34 cells. Nrg1 may protect neurons by partially antagonizing the effect of CXCL10.

Age-related decline in hippocampal tyrosine phosphatase PTPRO is a mechanistic factor in chemotherapy-related cognitive impairment.

Chemotherapy-related cognitive impairment (CRCI) or "chemo brain" is a devastating neurotoxic sequela of cancer-related treatments, especially for the elderly individuals. Here we show that PTPRO, a tyrosine phosphatase, is highly enriched in the hippocampus, and its level is tightly associated with neurocognitive function but declined significantly during aging. To understand the protective role of PTPRO in CRCI, a mouse model was generated by treating Ptpro-/- female mice with doxorubicin (DOX) because Ptpro-/- female mice are more vulnerable to DOX, showing cognitive impairments and neurodegeneration. By analyzing PTPRO substrates that are neurocognition-associated tyrosine kinases, we found that SRC and EPHA4 are highly phosphorylated/activated in the hippocampi of Ptpro-/- female mice, with increased sensitivity to DOX-induced CRCI. On the other hand, restoration of PTPRO in the hippocampal CA3 region significantly ameliorate CRCI in Ptpro-/- female mice. In addition, we found that the plant alkaloid berberine (BBR) is capable of ameliorating CRCI in aged female mice by upregulating hippocampal PTPRO. Mechanistically, BBR upregulates PTPRO by downregulating miR-25-3p, which directly targeted PTPRO. These findings collectively demonstrate the protective role of hippocampal PTPRO against CRCI.

Orally Induced High Serum Level of Trimethylamine N-oxide Worsened Glial Reaction and Neuroinflammation on MPTP-Induced Acute Parkinson's Disease Model Mice.

Neuroinflammation mediated by brain glial cells is one of the pathological drivers of Parkinson's disease (PD). Recent studies have shown that higher circulating trimethylamine N-oxide (TMAO, a gut microbiota-derived metabolite) can induce neuroinflammation and are strongly related to a variety of central nervous system diseases and adverse brain events. Herein, we explored the effect of pre-existing higher circulating TMAO on dopamine system and neuroinflammation in acute PD model mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydroxypyridine (MPTP). TMAO pretreatment was given by adding 3% (w/v) TMAO to drinking water of mice for 21 days to induce higher circulating TMAO status, then mice were administered with MPTP (20 mg/kg, i.p) for four times in one day to construct an acute PD model mice and treated with TMAO continuously until the end of the experiment. Results demonstrated that TMAO treatment significantly increased serum TMAO levels. Moreover, high serum TMAO significantly increased activation of microglia and astrocytes both in striatum and in substantia nigra. And strikingly, high serum TMAO significantly promoted the metabolism of striatal dopamine (DA) of PD model mice, although it had no significant effect on the number of dopaminergic neurons or the content of DA. Furthermore, immunofluorescence, ELISA, and RT-qPCR results of the hippocampus also showed that high serum TMAO significantly promoted the activation of microglia and astrocytes in the dentate gyrus, increased the levels of TNF-α and IL-1ß, and upregulated gene expression of M1 microglia-related markers (including CD16, CD32, and iNOS) and A2 astrocyte-related markers (including S100a10, Ptx3, and Emp1) in mRNA levels. In summary, we found that pre-existing high serum levels of TMAO worsened the PD-related brain pathology by promoting DA metabolism, aggravating neuroinflammation and regulating glial cell polarization.

RIPK1-Induced A1 Reactive Astrocytes in Brain in MPTP-Treated Murine Model of Parkinson's Disease.

Neuroinflammation is one of the hallmarks of Parkinson's disease, including the massive activation of microglia and astrocytes and the release of inflammatory factors. Receptor-interacting protein kinase 1 (RIPK1) is reported to mediate cell death and inflammatory signaling, and is markedly elevated in the brain in PD mouse models. Here, we aim to explore the role of RIPK1 in regulating the neuroinflammation of PD. C57BL/6J mice were intraperitoneally injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 20 mg/kg four times/day), followed by necrostatin-1 treatment (Nec-1, RIPK1 inhibitor; 1.65 mg/kg once daily for seven days. Notably, the first Nec-1 was given 12 h before MPTP modeling). Behavioral tests indicated that inhibition of RIPK1 greatly relieved motor dysfunction and anxiety-like behaviors of PD mice. It also increased striatal TH expression, rescue the loss of dopaminergic neurons, and reduce activation of astrocytes in the striatum of PD mice. Furthermore, inhibition of RIPK1 expression reduced A1 astrocytes' relative gene expression (CFB, H2-T23) and inflammatory cytokine or chemokine production (CCL2, TNF-α, IL-1ß) in the striatum of PD mice. Collectively, inhibition of RIPK1 expression can provide neuroprotection to PD mice, probably through inhibition of the astrocyte A1 phenotype, and thus RIPK1 might be an important target in PD treatment.

Trimethylamine N-Oxide Exacerbates Neuroinflammation and Motor Dysfunction in an Acute MPTP Mice Model of Parkinson's Disease.

Observational studies have shown abnormal changes in trimethylamine N-oxide (TMAO) levels in the peripheral circulatory system of Parkinson's disease (PD) patients. TMAO is a gut microbiota metabolite that can cross the blood-brain barrier and is strongly related to neuroinflammation. Neuroinflammation is one of the pathological drivers of PD. Herein, we investigated the effect of TMAO on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model mice. TMAO pretreatment was given by adding 1.5% (w/v) TMAO to the drinking water of the mice for 21 days; then, the mice were administered MPTP (20 mg/kg, i.p.) four times a day to construct an acute PD model. Their serum TMAO concentrations, motor function, dopaminergic network integrity, and neuroinflammation were then assayed. The results showed that TMAO partly aggravated the motor dysfunction of the PD mice. Although TMAO had no effect on the dopaminergic neurons, TH protein content, and striatal DA level in the PD mice, it significantly reduced the striatal 5-HT levels and aggravated the metabolism of DA and 5-HT. Meanwhile, TMAO significantly activated glial cells in the striatum and the hippocampi of the PD mice and promoted the release of inflammatory cytokines in the hippocampus. In summary, higher-circulating TMAO had adverse effects on the motor capacity, striatum neurotransmitters, and striatal and hippocampal neuroinflammation in PD mice.

Current study on diagnosis and treatment of Alzheimer's disease by targeting amyloid b-protein.

Alzheimer's disease (AD), also known as senile dementia, is a degenerative disease of the central nervous system and is characterized by insidious onset and a chronic progressive course. It is the most common type of senile dementia. Studies have proved that the deposition of amyloid b (Ab) in the brain is one of the initiating factors correlated to the pathology of AD, and it acts as one of the critical factors leading to the onset of AD. A large number of long-term studies have shown that Ab may be a therapeutic target for a breakthrough in the treatment of AD. This review elucidates the important role of Ab in the development of AD, current research on the role of Ab in AD pathogenesis, and treatment of AD by targeting Ab.

Nuclear translocation of cGAS orchestrates VEGF-A-mediated angiogenesis.

Cyclic GMP-AMP synthase (cGAS) senses cytosolic incoming DNA and consequently activates stimulator of interferon response cGAMP interactor 1 (STING) to mount immune response. Here, we show nuclear cGAS could regulate VEGF-A-mediated angiogenesis in an immune-independent manner. We found VEGF-A stimulation induces cGAS nuclear translocation via importin-ß pathway. Moreover, nuclear cGAS subsequently regulates miR-212-5p-ARPC3 cascade to modulate VEGF-A-mediated angiogenesis through affecting cytoskeletal dynamics and VEGFR2 trafficking from trans-Golgi network (TGN) to plasma membrane via a regulatory feedback loop. In contrast, cGAS deficiency remarkably impairs VEGF-A-mediated angiogenesis in vivo and in vitro. Furthermore, we found strong association between the expression of nuclear cGAS and VEGF-A, and the malignancy and prognosis in malignant glioma, suggesting that nuclear cGAS might play important roles in human pathology. Collectively, our findings illustrated the function of cGAS in angiogenesis other than immune surveillance, which might be a potential therapeutic target for pathological angiogenesis-related diseases.

DSS-induced acute colitis causes dysregulated tryptophan metabolism in brain: an involvement of gut microbiota.

Inflammatory bowel disease can cause pathological changes of certain organs, including the gut and brain. As the major degradation route of tryptophan (Trp), Kynurenine (Kyn) pathway are involved in multiple pathologies of brain. This study sought to explore the effects of Dextran sulphate sodium (DSS)-induced colitis on serum and brain Trp metabolism (especially the Kyn pathway) and its mechanisms. We induced acute colitis and sub-chronic colitis with 3% DSS and 1% DSS respectively and found more severe intestinal symptoms in acute colitis than sub-chronic colitis. Both of the colitis groups altered Trp-Kyn-Kynurenic acid (Kyna) pathway in serum by regulating the expression of rate-limiting enzyme (IDO-1, KAT2). Interestingly, only 3% DSS group activated Trp-Kyn pathway under the action of metabolic enzymes (IDO-1, TDO-2 and KAT2) in brain. Furthermore, intestinal flora 16S rRNA sequencing showed significantly changes in both DSS-induced colitis groups, including microbial diversity, indicator species, and the abundance of intestinal microflora related to Trp metabolism. The functional pathways of microbiomes involved in inflammation and Trp biosynthesis were elevated after DSS treatment. Moreover, correlation analysis showed a significant association between intestinal flora and Trp metabolism (both in serum and brain). In conclusion, our study suggests that DSS-induced acute colitis causes dysregulation of Trp-Kyn-Kyna pathways of Trp metabolism in serum and brain by affecting rate-limiting enzymes and intestinal flora.

Vancomycin Pretreatment on MPTP-Induced Parkinson's Disease Mice Exerts Neuroprotection by Suppressing Inflammation Both in Brain and Gut.

A growing body of evidence implies that gut microbiota was involved in pathogenesis of Parkinson's disease (PD), but the mechanism is still unclear. The aim of this study is to investigate the effects of antibiotics pretreatment on the 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced PD mice. In this study, vancomycin pretreatment was given by gavage once daily with either vancomycin or distilled water for 14 days to mice, then mice were administered with MPTP (20 mg/kg, i.p) for four times in one day to establish an acute PD model. Results show that vancomycin pretreatment significantly improved motor dysfunction of mice in pole and traction tests. Although vancomycin pretreatment had no effect on dopamine (DA) or the process of DA synthesis, it inhibited the metabolism of DA by suppressing the expression of striatal monoamine oxidase B (MAO-B). Furthermore, vancomycin pretreatment reduced the number of astrocytes and microglial cells in the substantia nigra pars compacta (SNpc) to alleviate neuroinflammation, decreased the expression of TLR4/MyD88/NF-κB/TNF-α signaling pathway in both brain and gut. Meanwhile, vancomycin pretreatment changed gut microbiome composition and the levels of fecal short chain fatty acids (SCFAs). The abundance of Akkermansia and Blautia increased significantly after vancomycin pretreatment, which might be related to inflammation and inhibition of TLR4 signaling pathway. In summary, these results demonstrate that the variation of gut microbiota and its metabolites induced by vancomycin pretreatment might decrease dopamine metabolic rate and relieve inflammation in both gut and brain via the microbiota-gut-brain axis in MPTP-induced PD mice. The neuroprotection of vancomycin pretreatment on MPTP-induced Parkinson's disease mice The alterations of gut microbiota and SCFAs induced by vancomycin pretreatment might not only improve motor dysfunction, but also decrease dopamine metabolism and relieve inflammation in both brain and gut via TLR4/MyD88/NF-κB/TNF-α pathway in MPTP-induced PD mice.

Par6 Enhances Glioma Invasion by Activating MEK/ERK Pathway Through a LIN28/let-7d Positive Feedback Loop.

The invasion of glioblastoma usually results in the recurrence and poor prognosis in patients with glioma. However, the underlying mechanisms involved in glioma invasion remains undefined. In this study, immunohistochemistry analyses of glioma specimens demonstrated that high expression of Par6 was positively correlated with malignancy and poor prognosis of patients with glioma. Par6-overexpressing glioma cells showed much more fibroblast-like morphology, suggesting that regulation of Par6 expression might be associated with tumor invasion in glioma cells. Further study indicated that Par6 overexpression subsequently increased CD44 and N-cadherin expression to enhance glioma invasion through activating MEK/ERK/STAT3 pathway, in vivo and in vitro. Moreover, we found that LIN28/let-7d axis was involved in this process via a positive feedback loop, suggesting that MEK/ERK/LIN28/let-7d/STAT3 cascade might be essential for Par6-mediated glioma invasion. Therefore, these data highlight the roles of Par6 in glioma invasion, and Par6 may serve as a potential therapeutic target for patients with glioma.