Interleukin-10 Protection against Lipopolysaccharide-Induced Neuro-Inflammation and Neurotoxicity in Ventral Mesencephalic Cultures

Differentiation and regulation of CD4+ T cell subsets in Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease, and its hallmark pathological features are the loss of dopaminergic (DA) neurons in the midbrain substantia nigra pars compacta (SNpc) and the accumulation of alpha-synuclein (α-syn). It has been shown that the integrity of the blood-brain barrier (BBB) is damaged in PD patients, and a large number of infiltrating T cells and inflammatory cytokines have been detected in the cerebrospinal fluid (CSF) and brain parenchyma of PD patients and PD animal models, including significant change in the number and proportion of different CD4+ T cell subsets. This suggests that the neuroinflammatory response caused by CD4+ T cells is an important risk factor for the development of PD. Here, we systematically review the differentiation of CD4+ T cell subsets, and focus on describing the functions and mechanisms of different CD4+ T cell subsets and their secreted cytokines in PD. We also summarize the current immunotherapy targeting CD4+ T cells with a view to providing assistance in the diagnosis and treatment of PD.

Human amniotic mesenchymal stromal cell-derived exosomes promote neuronal function by inhibiting excessive apoptosis in a hypoxia/ischemia-induced cerebral palsy model: A preclinical study

BACKGROUND

Cerebral palsy (CP) is a condition resulting from perinatal brain injury and can lead to physical disabilities. Exosomes derived from human amniotic mesenchymal stromal cells (hAMSC-Exos) hold promise as potential therapeutic options.

OBJECTIVE

This study aimed to investigate the impact of hAMSC-Exos on neuronal cells and their role in regulating apoptosis both in vitro and in vivo.

METHODS

hAMSC-Exos were isolated via ultracentrifugation and characterized via transmission electron microscopy, particle size analysis, and flow cytometry. In vitro, neuronal damage was induced by lipopolysaccharide (LPS). CP rat models were established via left common carotid artery ligation. Apoptosis levels in cells and CP rats were assessed using flow cytometry, quantitative reverse transcription polymerase chain reaction (RT-qPCR), Western blotting, and TUNEL analysis.

RESULTS

The results demonstrated successful isolation of hAMSC-Exos via ultracentrifugation, as the isolated cells were positive for CD9 (79.7%) and CD63 (80.2%). Treatment with hAMSC-Exos significantly mitigated the reduction in cell viability induced by LPS. Flow cytometry revealed that LPS-induced damage promoted apoptosis, but this effect was attenuated by treatment with hAMSC-Exos. Additionally, the expression of caspase-3 and caspase-9 and the Bcl-2/Bax ratio indicated that excessive apoptosis could be attenuated by treatment with hAMSC-Exos. Furthermore, tail vein injection of hAMSC-Exos improved the neurobehavioral function of CP rats. Histological analysis via HE and TUNEL staining showed that apoptosis-related damage was attenuated following hAMSC-Exo treatment.

CONCLUSIONS

In conclusion, hAMSC-Exos effectively promote neuronal cell survival by regulating apoptosis, indicating their potential as a promising therapeutic option for CP that merits further investigation.

Regulation of Diseases-Associated Microglia in the Optic Nerve by Lipoxin B4 and Ocular Hypertension

Background

The resident astrocyte-retinal ganglion cell (RGC) lipoxin circuit is impaired during retinal stress, which includes ocular hypertension-induced neuropathy. Lipoxin B4 produced by homeostatic astrocytes directly acts on RGCs to increase survival and function in ocular hypertension-induced neuropathy. RGC death in the retina and axonal degeneration in the optic nerve are driven by the complex interactions between microglia and macroglia. Whether LXB4 neuroprotective actions include regulation of other cell types in the retina and/or optic nerve is an important knowledge gap.

Methods

Cellular targets and signaling of LXB4 in the retina were defined by single-cell RNA sequencing. Retinal neurodegeneration was induced by injecting silicone oil into the anterior chamber of the mouse eyes, which induced sustained and stable ocular hypertension. Morphological characterization of microglia populations in the retina and optic nerve was established by MorphOMICs and pseudotime trajectory analyses. The pathways and mechanisms of action of LXB4 in the optic nerve were investigated using bulk RNA sequencing. Transcriptomics data was validated by qPCR and immunohistochemistry. Differences between experimental groups was assessed by Student's t-test and one-way ANOVA.

Results

Single-cell transcriptomics identified microglia as a primary target for LXB4 in the healthy retina. LXB4 downregulated genes that drive microglia environmental sensing and reactivity responses. Analysis of microglial function revealed that ocular hypertension induced distinct, temporally defined, and dynamic phenotypes in the retina and, unexpectedly, in the distal myelinated optic nerve. Microglial expression of CD74, a marker of disease-associated microglia in the brain, was only induced in a unique population of optic nerve microglia, but not in the retina. Genetic deletion of lipoxin formation correlated with the presence of a CD74 optic nerve microglia population in normotensive eyes, while LXB4 treatment during ocular hypertension shifted optic nerve microglia toward a homeostatic morphology and non-reactive state and downregulated the expression of CD74. Furthermore, we identified a correlation between CD74 and phospho-phosphoinositide 3-kinases (p-PI3K) expression levels in the optic nerve, which was reduced by LXB4 treatment.

Conclusion

We identified early and dynamic changes in the microglia functional phenotype, reactivity, and induction of a unique CD74 microglia population in the distal optic nerve as key features of ocular hypertension-induced neurodegeneration. Our findings establish microglia regulation as a novel LXB4 target in the retina and optic nerve. LXB4 maintenance of a homeostatic optic nerve microglia phenotype and inhibition of a disease-associated phenotype are potential neuroprotective mechanisms for the resident LXB4 pathway.

Role of MAPK and PI3K-Akt signaling pathways in cuprizone-induced demyelination and cognitive impairment in mice

This study aimed to find the genes and signaling pathways underlying cuprizone-induced demyelination and cognitive impairments in mice. We used the cuprizone-exposed mice as an animal model of schizophrenia and assessed cognitive function in mice. Total RNA was extracted from mouse brain tissues for RNA sequencing. The DESeq2 R package was utilized to analyze the differentially expressed genes (DEGs). Functional and pathway enrichment analyses were performed simultaneously. We also constructed a protein-protein interaction (PPI) network to screen potential hub genes, and quantitative real-time polymerase chain reaction (qRT-PCR) was employed to validate the screened genes. After 6 weeks of cuprizone treatment, the cognitive function of mice was impaired. Compared to the controls, the cuprizone-exposed mice contained 351 DEGs, including 167 upregulated and 184 downregulated genes. Enrichment analysis showed that the DEGs were enriched in some biological processes involved in demyelination, including the MAPK pathway. Functional pathway analysis revealed that the DEGs were significantly enriched in the PI3K-Akt signaling pathway, which may be associated with cognitive impairments. MBP, IGF1, GFAP, PTPRC, CD14, CD68, ITGB2, LYN, TLR2, TLR4, VAV1, and PLEK were considered as potential hub genes. Except for MBP, all genes were upregulated in the cuprizone models, as verified by qRT-PCR. We suggest that the MAPK and PI3K-Akt signaling pathways may be associated with demyelination and cognitive impairments, respectively. GFAP and IGF-1 expression levels increased in cuprizone-exposed mice, suggesting that astrocytes may play a role in protecting the myelin sheath following treatment with cuprizone.

Reactive Gliosis in Neonatal Disorders: Friend or Foe for Neuroregeneration?

A developing nervous system is particularly vulnerable to the influence of pathophysiological clues and injuries in the perinatal period. Astrocytes are among the first cells that react to insults against the nervous tissue, the presence of pathogens, misbalance of local tissue homeostasis, and a lack of oxygen and trophic support. Under this background, it remains uncertain if induced astrocyte activation, recognized as astrogliosis, is a friend or foe for progressing neonatal neurodevelopment. Likewise, the state of astrocyte reactivity is considered one of the key factors discriminating between either the initiation of endogenous reparative mechanisms compensating for aberrations in the structures and functions of nervous tissue or the triggering of neurodegeneration. The responses of activated cells are modulated by neighboring neural cells, which exhibit broad immunomodulatory and pro-regenerative properties by secreting a plethora of active compounds (including interleukins and chemokines, neurotrophins, reactive oxygen species, nitric oxide synthase and complement components), which are engaged in cell crosstalk in a paracrine manner. As the developing nervous system is extremely sensitive to the influence of signaling molecules, even subtle changes in the composition or concentration of the cellular secretome can have significant effects on the developing neonatal brain. Thus, modulating the activity of other types of cells and their interactions with overreactive astrocytes might be a promising strategy for controlling neonatal astrogliosis.

The Emerging Role of Pericyte-Derived Extracellular Vesicles in Vascular and Neurological Health

Pericytes (PCs), as a central component of the neurovascular unit, contribute to the regenerative potential of the central nervous system (CNS) and peripheral nervous system (PNS) by virtue of their role in blood flow regulation, angiogenesis, maintenance of the BBB, neurogenesis, and neuroprotection. Emerging evidence indicates that PCs also have a role in mediating cell-to-cell communication through the secretion of extracellular vesicles (EVs). Extracellular vesicles are cell-derived, micro- to nano-sized vesicles that transport cell constituents such as proteins, nucleic acids, and lipids from a parent originating cell to a recipient cell. PC-derived EVs (PC-EVs) play a crucial homeostatic role in neurovascular disease, as they promote angiogenesis, maintain the integrity of the blood-tissue barrier, and provide neuroprotection. The cargo carried by PC-EVs includes growth factors such as endothelial growth factor (VEGF), connecting tissue growth factors (CTGFs), fibroblast growth factors, angiopoietin 1, and neurotrophic growth factors such as brain-derived neurotrophic growth factor (BDNF), neuron growth factor (NGF), and glial-derived neurotrophic factor (GDNF), as well as cytokines such as interleukin (IL)-6, IL-8, IL-10, and MCP-1. The PC-EVs also carry miRNA and circular RNA linked to neurovascular health and the progression of several vascular and neuronal diseases. Therapeutic strategies employing PC-EVs have potential in the treatment of vascular and neurodegenerative diseases. This review discusses current research on the characteristic features of EVs secreted by PCs and their role in neuronal and vascular health and disease.

Pre-clinical Studies Identifying Molecular Pathways of Neuroinflammation in Parkinson's Disease: A Systematic Review

Parkinson's disease (PD), the second most common neurodegenerative disorder, is characterized by neuroinflammation, formation of Lewy bodies, and progressive loss of dopaminergic neurons in the substantia nigra of the brain. In this review, we summarize evidence obtained by animal studies demonstrating neuroinflammation as one of the central pathogenetic mechanisms of PD. We also focus on the protein factors that initiate the development of PD and other neurodegenerative diseases. Our targeted literature search identified 40 pre-clinical in vivo and in vitro studies written in English. Nuclear factor kappa B (NF-kB) pathway is demonstrated as a common mechanism engaged by neurotoxins such as 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 6-hydroxydopamine (6-OHDA), as well as the bacterial lipopolysaccharide (LPS). The α-synuclein protein, which plays a prominent role in PD neuropathology, may also contribute to neuroinflammation by activating mast cells. Meanwhile, 6-OHDA models of PD identify microsomal prostaglandin E synthase-1 (mPGES-1) as one of the contributors to neuroinflammatory processes in this model. Immune responses are used by the central nervous system to fight and remove pathogens; however, hyperactivated and prolonged immune responses can lead to a harmful neuroinflammatory state, which is one of the key mechanisms in the pathogenesis of PD.

MicroRNA-124 attenuates PTSD-like behaviors and reduces the level of inflammatory cytokines by downregulating the expression of TRAF6 in the hippocampus of rats following single-prolonged stress

BACKGROUND

MicroRNA-124-3p (miR-124) plays an important role in neuroprotective functions in various neurological disorders, but whether miR-124 participates in the pathological progression of posttraumatic stress disorder (PTSD) remains poorly understood.

METHODS

In the present study, we assessed the level of neuroinflammation in the hippocampus of rats exposed to single-prolonged stress (SPS) by Western blot and immunofluorescence staining, while the effect of miR-124 on PTSD-like behaviors was evaluated by behavioral test.

RESULTS

Our results showed that the level of miR-124 in the hippocampus of rats exposed to SPS was downregulated and that the upregulation of miR-124 could alleviate the PTSD-like behaviors of SPS rats. This effect of miR-124 might be achieved through TNF receptor-associated Factor 6 (TRAF6), which is a target gene of miR-124 and plays an important role in the immune and inflammatory reaction by regulating nuclear factor kappa-B (NF-κB). Furthermore, we found that miR-124 not only decreased the level of proinflammatory cytokines but also increased the expression levels of synaptic proteins (PSD95 and synapsin I) and regulated the morphology of neurons.

CONCLUSION

These results suggested that miR-124 might attenuate PTSD-like behaviors and decrease the level of proinflammatory cytokines by downregulating the expression of TRAF6 in the hippocampus of rats exposed to SPS.

Evidence of Anti-Inflammatory Effect of Transcranial Direct Current Stimulation in a CFA-Induced Chronic Inflammatory Pain Model in Wistar Rats

INTRODUCTION

Given that chronic inflammatory pain is highly prevalent worldwide, it is important to study new techniques to treat or relieve this type of pain. The present study evaluated the effect of transcranial direct current stimulation (tDCS) in rats submitted to a chronic inflammatory model by nociceptive response, biomarker levels (brain-derived neurotrophic factor [BDNF] and interleukin [IL]-6 and IL-10), and by histological parameters.

METHODS

Sixty-day-old male Wistar rats were used in this study and randomized by weight into 6 major groups: total control, control + sham-tDCS, control + active tDCS, total CFA, CFA + sham-tDCS, and CFA + active tDCS. After inflammatory pain was established, the animals were submitted to the treatment protocol for 8 consecutive days, according to the experimental group. The nociceptive tests (von Frey and hot plate) were assessed, and euthanasia by decapitation occurred at day 8 after the end of tDCS treatment, and the blood serum and central nervous structures were collected for BDNF and IL measurements. All experiments and procedures were approved by the Institutional Committee for Animal Care and Use (UFPel #4538).

RESULTS

The tDCS treatment showed a complete reversal of the mechanical allodynia induced by the pain model 24 h and 8 days after the last tDCS session, and there was partial reversal of the thermal hyperalgesia at all time points. Serum BDNF levels were decreased in CFA + sham-tDCS and CFA + tDCS groups compared to the control + tDCS group. The control group submitted to tDCS exhibited an increase in serum IL-6 levels in relation to the other groups. In addition, there was a significant decrease in IL-10 striatum levels in control + tDCS, CFA, and CFA + sham-tDCS groups in relation to the control group, with a partial tDCS effect on the CFA pain model. Local histology demonstrated tDCS effects in decreasing lymphocytic infiltration and neovascularization and tissue regeneration in animals exposed to CFA.

CONCLUSION

tDCS was able to reverse the mechanical allodynia and decrease thermal hyperalgesia and local inflammation in a chronic inflammatory pain model, with a modest effect on striatum IL-10 levels. As such, we suggest that analgesic tDCS mechanisms may be related to tissue repair by modulating the local inflammatory process.

Involvement of IL-10R/STAT3 pathway in amyloid β clearance by microlgia in Alzheimer's disease

Both the total amount and annual growth rate of Alzheimer's disease (AD) patients in China are much higher than in other regions in the world. This trend of rapid growth will be difficult to change in the next few decades, hence the prevention and treatment situation of AD patients in China is more severe. Maintaining the balance between the production and removal pathways of Aβ is an important guarantee for the body to maintain its normal physiological state. The dysfunction of Aβ clearance is an important factor of Aβ accumulation in brain tissue of AD patients causing neurotoxicity of synaptic damage and neuronal death. Based on the literature review, it introduced the important role of microglias in clearing Aβ deposits in the process of Alzheimer's disease. And most of these phagocytic cells were the specific phenotype of disease-related microglia (DAM-I/DAM-II) that induced microglial differentiation after activation. IL-10KO promoted the transformation of microglial phenotype DAM-II, and enhanced its phagocytosis for Aβ oligomers. There is a hypothesis that IL-10R/STAT3 negatively regulates microglial phagocytosis. It was learnt that blocking the IL-10R/STAT3 pathway promoted microglial activation and enhanced phagocytosis. The comprehensive review on the involvement of IL-10R/STAT3 pathway in the process of AD would open up new ideas and discover new targets for the development of new therapeutic drugs.

Injection of Anti-proBDNF Attenuates Hippocampal-Dependent Learning and Memory Dysfunction in Mice With Sepsis-Associated Encephalopathy

Sepsis-associated encephalopathy (SAE) is a risk factor for cognitive and memory dysfunction; however, the mechanism remains unclear. Brain-derived neurotrophic factor (BDNF) was reported to have a positive effect on cognition and emotion regulation, but the study of its precursor, proBDNF, has been limited. This study aimed to elucidate the effects and associated mechanisms of hippocampal proBDNF in a lipopolysaccharide (LPS)-induced SAE mouse model. In this study, we found that the mice exhibited cognitive dysfunction on day 7 after LPS injection. The expression of proBDNF and its receptor, p75^NTR, was also increased in the hippocampus, while the levels of BDNF and its receptor, TrkB, were decreased. A co-localization study showed that proBDNF and p75^NTR were mainly co-localized with neurons. Furthermore, LPS treatment reduced the expression of NeuN, Nissl bodies, GluR4, NR1, NR2A, and NR2B in the hippocampus of SAE mice. Furthermore, an intrahippocampal or intraperitoneal injection of anti-proBDNF antibody was able to ameliorate LPS-induced cognitive dysfunction and restore the expression of NeuN, Nissl bodies, GluR4, NR1, NR2A, NR2B, and PSD95. These results indicated that treatment with brain delivery by an intrahippocampal and systemic injection of mAb-proBDNF may represent a potential therapeutic strategy for treating patients with SAE.

Mechanisms of the Procognitive Effects of Xanthotoxin and Umbelliferone on LPS-Induced Amnesia in Mice

Neuroinflammation plays an essential role in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease. Although coumarins have been shown to improve cognitive function in animal models and exert anti-inflammatory effects in cell cultures, the exact mechanism of their neuroprotective effects has not yet been fully elucidated. The present study aimed to investigate the neuroprotective effects of xanthotoxin (furanocoumarin) and umbelliferone (simple coumarin) in lipopolysaccharide-induced cognitive dysfunction in mice. For evaluation memory and learning processes, a passive avoidance test was used. Furthermore, acetylcholinesterase level and impact on the tumor necrosis factor α, interleukin 10 levels in the whole brain, and cyclooxygenase-II in hippocampus was established. Subchronic administration of both coumarins (15 mg/kg) enhanced the learning and memory function, but only the xanthotoxin improved cognitive processes impaired by lipopolysaccharide (0.8 mg/kg) administration. Behavioral results stay in line with acetylcholinesterase level in the brain. A statistically significant decrease in the level of tumor necrosis factor α and cyclooxygenase-II in lipopolysaccharide-treated rodents after coumarins' administration was observed. Together, our findings demonstrate that both coumarins improved cognitive functions, but only xanthotoxin significantly enhanced the learning and memory function and reduced the level of acetylcholinesterase in lipopolysaccharide-treated mice. This effect may suggest that only furanocoumarin-xanthotoxin attenuates neuroinflammation and enhances cholinergic neurotransmission, thus it can be a potential remedy with procognitive potential effective in treatment of neuroinflammatory disease.

miR-142 downregulation alleviates rat PTSD-like behaviors, reduces the level of inflammatory cytokine expression and apoptosis in hippocampus, and upregulates the expression of fragile X mental retardation protein

Background

FMRP is a selective mRNA-binding protein that regulates protein synthesis at synapses, and its loss may lead to the impairment of trace fear memory. Previously, we found that FMRP levels in the hippocampus of rats with post-traumatic stress disorder (PTSD) were decreased. However, the mechanism underlying these changes remains unclear.

Methods

Forty-eight male Sprague-Dawley rats were randomly divided into four groups. The experimental groups were treated with the single-prolonged stress (SPS) procedure and injected with a lentivirus-mediated inhibitor of miR-142-5p. Behavior test as well as morphology and molecular biology experiments were performed to detect the effect of miR-142 downregulation on PTSD, which was further verified by in vitro experiments.

Results

We found that silence of miRNA-142 (miR-142), an upstream regulator of FMRP, could alleviate PTSD-like behaviors of rats exposed to the SPS paradigm. MiR-142 silence not only decreased the levels of proinflammatory mediators, such as interleukin-1β, interleukin-6, and tumor necrosis factor-α, but also increased the expressive levels of synaptic proteins including PSD95 and synapsin I in the hippocampus, which was one of the key brain regions associated with PTSD. We further detected that miR-142 silence also downregulated the transportation of nuclear factor kappa-B (NF-κB) into the nuclei of neurons and might further affect the morphology of neurons.

Conclusions

The results revealed miR-142 downregulation could alleviate PTSD-like behaviors through attenuating neuroinflammation in the hippocampus of SPS rats by binding to FMRP.

Therapeutic Potential of Porcine Liver Decomposition Product: New Insights and Perspectives for Microglia-Mediated Neuroinflammation in Neurodegenerative Diseases

It is widely accepted that microglia-mediated inflammation contributes to the progression of neurodegenerative diseases; however, the precise mechanisms through which these cells contribute remain to be elucidated. Microglia, as the primary immune effector cells of the brain, play key roles in maintaining central nervous system (CNS) homeostasis. Microglia are located throughout the brain and spinal cord and may account for up to 15% of all cells in the brain. Activated microglia express pro-inflammatory cytokines that act on the surrounding brain and spinal cord. Microglia may also play a detrimental effect on nerve cells when they gain a chronic inflammatory function and promote neuropathologies. A key feature of microglia is its rapid morphological change upon activation, characterized by the retraction of numerous fine processes and the gradual acquisition of amoeba-like shapes. These morphological changes are also accompanied by the expression and secretion of inflammatory molecules, including cytokines, chemokines, and lipid mediators that promote systemic inflammation during neurodegeneration. This may be considered a protective response intended to limit further injury and initiate repair processes. We previously reported that porcine liver decomposition product (PLDP) induces a significant increase in the Hasegawa’s Dementia Scale-Revised (HDS-R) score and the Wechsler Memory Scale (WMS) in a randomized, double-blind, placebo-controlled study in healthy humans. In addition, the oral administration of porcine liver decomposition product enhanced visual memory and delayed recall in healthy adults. We believe that PLDP is a functional food that aids cognitive function. In this review, we provide a critical assessment of recent reports of lysophospholipids derived from PLDP, a rich source of phospholipids. We also highlight some recent findings regarding bidirectional interactions between lysophospholipids and microglia and age-related neurodegenerative diseases such as dementia and Alzheimer’s disease.

Ethanol extracts from Ilex pubescens promotes cerebral ischemic tolerance via modulation of TLR4-MyD88/TRIF signaling pathway in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Pubescent Holly Root is the dry root of Ilex pubescens Hook. et Arn. It is clinically using in the treatment for stroke and coronary artery disease. It remains unclear whether the ethanol extracts of Ilex pubescens(IPEE) treatment can promote cerebral ischemic tolerance (CIT) and exert endogenous neuroprotective effects and thus to alleviate the nerve injury caused by the subsequent persistent cerebral ischemic attacks.

AIM OF THE STUDY

To investigate the effects of IPEE on CIT and its underlying molecular mechanisms.

MATERIALS AND METHODS

Adult male Wistar rats were used in the present study. The bilateral common carotid arteries were blocked for 10 min followed a subsequent reperfusion to create the cerebral ischemic preconditioning (CIP); After 3 days post CIP, rats were subjected to middle cerebral artery occlusion/reperfusion (MCAO/R)-injury. Rats were continuously fed with IPEE for 5 days throughout the experiment period at the dose of 100 mg/kg and 200 mg/kg, respectively. Then, the brain infarct volume, histopathology, neurological deficits, and the gene/protein expression related with the TLR4-MyD88/TRIF signaling pathway were evaluated after 24 h of MCAO/R experiment.

RESULTS

IPEE pretreatment significantly reduced the cerebral infarct volume, the neurological deficit scores, and the plasma level of neuron specific enolase (NSE) at the dose of 100 mg/kg. Meanwhile, IPEE pretreatment significantly decreased the levels of inflammatory cytokines including TNF-α, IL-6, MCP-1, MIP-1α and RANTES, while it increased the levels of anti-inflammatory cytokines, such as IL-10 and TGF-β, when compared with the group with CIP treatment alone. Moreover, the effect of IPEE treatment on CIT was in a dose-dependent manner, showing as a better effect in the group pretreated with IPEE with the dose of 100 mg/kg than that in group pretreated with IPEE with the dose of 200 mg/kg. In addition, IPEE pretreatment significantly inhibited the expressions of MyD88 mRNA and the protein expression of COX-2 and NF-κBp65, while it strengthened the expressions of TRIF mRNA and protein. The effects of IPEE pretreatment on the expression of these genes were better than that in the group treated with CIP alone.

CONCLUSIONS

The present study demonstrates that IPEE pretreatment can enhance cerebral ischemic tolerance with a underlying mechanism involved in the toll-like receptor 4 (TLR4) signaling pathway through inhibiting the production of proteins or cytokines in the downstream of MyD88 and activating TRIF dependent anti-inflammatory pathways.

Antioxidants and Neuron-Astrocyte Interplay in Brain Physiology: Melatonin, a Neighbor to Rely on

This manuscript is a review focused onto the role of astrocytes in the protection of neurons against oxidative stress and how melatonin can contribute to the maintenance of brain homeostasis. The first part of the review is dedicated to the dependence of neurons on astrocytes by terms of survival under oxidative stress conditions. Additionally, the effects of melatonin against oxidative stress in the brain and its putative role in the protection against diseases affecting the brain are highlighted. The effects of melatonin on the physiology of neurons and astrocytes also are reviewed.

Microglia Mediated Neuroinflammation: Focus on PI3K Modulation

Immune activation in the central nervous system involves mostly microglia in response to pathogen invasion or tissue damage, which react, promoting a self-limiting inflammatory response aimed to restore homeostasis. However, prolonged, uncontrolled inflammation may result in the production by microglia of neurotoxic factors that lead to the amplification of the disease state and tissue damage. In particular, specific inducers of inflammation associated with neurodegenerative diseases activate inflammatory processes that result in the production of a number of mediators and cytokines that enhance neurodegenerative processes. Phosphoinositide 3-kinases (PI3Ks) constitute a family of enzymes regulating a wide range of activity, including signal transduction. Recent studies have focused attention on the intracellular role of PI3K and its contribution to neurodegenerative processes. This review illustrates and discusses recent findings about the role of this signaling pathway in the modulation of microglia neuroinflammatory responses linked to neurodegeneration. Finally, we discuss the modulation of PI3K as a potential therapeutic approach helpful for developing innovative therapeutic strategies in neurodegenerative diseases.

BAP31 regulates IRAK1-dependent neuroinflammation in microglia

BACKGROUND

Microglia, the mononuclear immune cells of the central nervous system (CNS), are essential for the maintenance of CNS homeostasis. BAP31, a resident and ubiquitously expressed protein of the endoplasmic reticulum, serves as a sorting factor for its client proteins, mediating the subsequent export, retention, and degradation or survival. Recently, BAP31 has been defined as a regulatory molecule in the CNS, but the function of BAP31 in microglia has yet to be determined. In the present study, we investigated whether BAP31 is involved in the inflammatory response of microglia.

METHODS

This study used the BV2 cell line and BAP31 conditional knockdown mice generated via the Cre/LoxP system. A BAP31 knockdown experiment was performed to elucidate the role of BAP31 in the endogenous inflammatory cytokine production by microglial BV2 cells. A mouse model of lipopolysaccharide (LPS)-induced cognitive impairment was established to evaluate the neuroprotective effect of BAP31 against neuroinflammation-induced memory deficits. Behavioral alterations were assessed with the open field test (OFT), Y maze, and Morris water maze. The activation of microglia in the hippocampus of mice was observed by immunohistochemistry. Western blot, enzyme-linked immunosorbent assay (ELISA), immunofluorescence staining, and reverse transcription quantitative real-time polymerase chain reaction (RT-PCR) were used to clarify the mechanisms.

RESULTS

BAP31 deficiency upregulates LPS-induced proinflammatory cytokines in BV2 cells and mice by upregulating the protein level of IRAK1, which in turn increases the translocation and transcriptional activity of NF-κB p65 and c-Jun, and moreover, knockdown of IRAK1 or use of an IRAK1 inhibitor reverses these functions. In the cognitive impairment animal model, the BAP31 knockdown mice displayed increased severity in memory deficiency accompanied by an increased expression of proinflammatory factors in the hippocampus.

CONCLUSIONS

These findings indicate that BAP31 may modulate inflammatory cytokines and cognitive impairment induced by neuroinflammation through IRAK1, which demonstrates that BAP31 plays an essential role in microglial inflammation and prevention of memory deficits caused by neuroinflammation.

Rice Protein Exerts Anti-Inflammatory Effect in Growing and Adult Rats via Suppressing NF-κB Pathway

To elucidate the effect of rice protein (RP) on the depression of inflammation, growing and adult rats were fed with caseins and RP for 2 weeks. Compared with casein, RP reduced hepatic accumulations of reactive oxygen species (ROS) and nitro oxide (NO), and plasma activities of alanine transaminase (ALT) and aspartate transaminase (AST) in growing and adult rats. Intake of RP led to increased mRNA levels, and protein expressions of phosphoinositide 3 kinase (PI3K), protein kinase B (Akt), nuclear factor-κB 1 (NF-αB1), reticuloendotheliosis viral oncogene homolog A (RelA), tumor necrotic factor α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and monocyte chemoattractant protein-1 (MCP-1) were decreased, whereas hepatic expressions of interleukin-10 (IL-10) and heme oxygenase 1 (HO-1) were increased by RP. The activation of NF-κB was suppressed by RP through upregulation of inhibitory κB α (IκBα), resulting in decreased translocation of nuclear factor-κB 1 (p50) and RelA (p65) to the nucleus in RP groups. The present study demonstrates that RP exerts an anti-inflammatory effect to inhibit ROS-derived inflammation through suppression of the NF-κB pathway in growing and adult rats. Results suggest that the anti-inflammatory capacity of RP is independent of age.

Early Celastrol Administration Prevents Ketamine-Induced Psychotic-Like Behavioral Dysfunctions, Oxidative Stress and IL-10 Reduction in The Cerebellum of Adult Mice

Administration of subanesthetic doses of ketamine during brain maturation represents a tool to mimic an early insult to the central nervous system (CNS). The cerebellum is a key player in psychosis pathogenesis, to which oxidative stress also contributes. Here, we investigated the impact of early celastrol administration on behavioral dysfunctions in adult mice that had received ketamine (30 mg/kg i.p.) at postnatal days (PNDs) 7, 9, and 11. Cerebellar levels of 8-hydroxydeoxyguanosine (8-OHdG), NADPH oxidase (NOX) 1 and NOX2, as well as of the calcium-binding protein parvalbumin (PV), were also assessed. Furthermore, celastrol effects on ketamine-induced alterations of proinflammatory (TNF-α, IL-6 and IL-1β) and anti-inflammatory (IL-10) cytokines in this brain region were evaluated. Early celastrol administration prevented ketamine-induced discrimination index decrease at adulthood. The same was found for locomotor activity elevations and increased close following and allogrooming, whereas no beneficial effects on sniffing impairment were detected. Ketamine increased 8-OHdG in the cerebellum of adult mice, which was also prevented by early celastrol injection. Cerebellar NOX1 levels were enhanced at adulthood following postnatal ketamine exposure. Celastrol per se induced NOX1 decrease in the cerebellum. This effect was more significant in animals that were early administered with ketamine. NOX2 levels did not change. Ketamine administration did not affect PV amount in the cerebellum. TNF-α levels were enhanced in ketamine-treated animals; however, this was not prevented by early celastrol administration. While no changes were observed for IL-6 and IL-1β levels, ketamine determined a reduction of cerebellar IL-10 expression, which was prevented by early celastrol treatment. Our results suggest that NOX inhibition during brain maturation prevents the development of psychotic-like behavioral dysfunctions, as well as the increased cerebellar oxidative stress and the reduction of IL-10 in the same brain region following ketamine exposure in postnatal life. This opens novel neuroprotective opportunities against early detrimental insults occurring during brain development.

Interleukin-10 Facilitates Glutamatergic Synaptic Transmission and Homeostatic Plasticity in Cultured Hippocampal Neurons

Anti-inflammatory cytokines are known to exert neuroprotective action ameliorating aberrant neuronal network activity associated with inflammatory responses. Yet, it is still not fully understood if anti-inflammatory cytokines play a significant role in the regulation of synaptic activity under normal conditions. Thus, the aim of our study was to investigate the effect of Interleukin-10 (IL-10) on neuronal synaptic transmission and plasticity. For this we tested the effect of IL-10 on miniature excitatory postsynaptic currents (mEPSC) and intracellular Ca²⁺ responses using whole-cell patch clamp and fluorescence microscopy in 13–15 DIV primary hippocampal neuroglial culture. We found that IL-10 significantly potentiated basal glutamatergic excitatory synaptic transmission within 15 min after application. Obtained results revealed a presynaptic nature of the effect, as IL-10 in a dose-dependent manner significantly increased the frequency but not the amplitude of mEPSC. Further, we tested the effect of IL-10 on mEPSC in a model of homeostatic synaptic plasticity (HSP) induced by treatment of primary hippocampal culture with 1 µM of tetrodotoxin (TTX) for a 24 h. It was found that 15 min application of IL-10 at established HSP resulted in enhanced mEPSC frequency, thus partially compensating for a decrease in the mEPSC frequency associated with TTX-induced HSP. Next, we studied if IL-10 can influence induction of HSP. We found that co-incubation of IL-10 with 1 µM of TTX for 24 h induced synaptic scaling, significantly increasing the amplitude of mEPSC and Ca²⁺ responses to application of the AMPA agonist, 5-Fluorowillardiine, thus facilitating a compensatory postsynaptic mechanism at HSP condition. Our results indicate that IL-10 potentiates synaptic activity in a dose- and time-dependent manner exerting both presynaptic (short-term exposure) and postsynaptic (long-term exposure) action. Obtained results demonstrate involvement of IL-10 in the regulation of basal glutamatergic synaptic transmission and plasticity at normal conditions.

Lipopolysaccharide-Induced Neuroinflammation as a Bridge to Understand Neurodegeneration

A large body of experimental evidence suggests that neuroinflammation is a key pathological event triggering and perpetuating the neurodegenerative process associated with many neurological diseases. Therefore, different stimuli, such as lipopolysaccharide (LPS), are used to model neuroinflammation associated with neurodegeneration. By acting at its receptors, LPS activates various intracellular molecules, which alter the expression of a plethora of inflammatory mediators. These factors, in turn, initiate or contribute to the development of neurodegenerative processes. Therefore, LPS is an important tool for the study of neuroinflammation associated with neurodegenerative diseases. However, the serotype, route of administration, and number of injections of this toxin induce varied pathological responses. Thus, here, we review the use of LPS in various models of neurodegeneration as well as discuss the neuroinflammatory mechanisms induced by this toxin that could underpin the pathological events linked to the neurodegenerative process.

The Role of Insulin-Like Growth Factors and Insulin-Like Growth Factor-Binding Proteins in the Nervous System

The insulin-like growth factors (IGF-I and IGF-II) and their receptors are widely expressed in nervous tissue from early embryonic life. They also cross the blood brain barriers by active transport, and their regulation as endocrine factors therefore differs from other tissues. In brain, IGFs have paracrine and autocrine actions that are modulated by IGF-binding proteins and interact with other growth factor signalling pathways. The IGF system has roles in nervous system development and maintenance. There is substantial evidence for a specific role for this system in some neurodegenerative diseases, and neuroprotective actions make this system an attractive target for new therapeutic approaches. In developing new therapies, interaction with IGF-binding proteins and other growth factor signalling pathways should be considered. This evidence is reviewed, gaps in knowledge are highlighted, and recommendations are made for future research.

Pretreatment with crocin along with treadmill exercise ameliorates motor and memory deficits in hemiparkinsonian rats by anti-inflammatory and antioxidant mechanisms

The motor symptoms of Parkinson's disease (PD) are preceded by non-motorized symptoms including memory deficits. Treatment with dopamine replacement medications, such as L-DOPA only control motor symptoms and does not meet the clinical challenges of the disease, such as dyskinesia, non-motor symptoms, and neuroprotection. The purpose of the current study was to examine the neuroprotective potential of crocin and physical exercise in an animal model of PD. Male Wistar rats ran on a horizontal treadmill and/or pretreated with crocin at a dose of 100 mg/kg. Then, 16 μg of the neurotoxin 6-hydroxydopamine (6-OHDA) was microinjected into left medial forebrain bundle. Crocin treatment and/or exercise continued for 6 more weeks. Spatial and aversive memories, rotational behaviour, inflammatory and oxidative stress parameters were assessed at the end of week 6 post surgery. The results showed that pretreatment with crocin alone and in combination with exercise decreased the total number of rotaions as compared with 6-OHDA-lesioned group. Furthermore, treatment of parkinsonian rats with crocin along with exercise training improved aversive and spatial memories. Biochemical analysis showed that crocin and exercise (alone and in combination) reduced tumor necrosis factor- (TNF) α levels in the striatum. Moreover, treatment with crocin at a dose of 100 mg/kg decreased the lipid peroxidation levels in the hippocampus, while exercise training increased the total thiol concentration. In conclusion, our findings indicated that pretreatment with crocin along with treadmill exercise ameliorated motor and memory deficits induced by 6-OHDA, which is considered to be due to their antioxidant and anti-inflammatory activities. The results suggest that combined therapy with crocin and exercise may be protective for motor and memory deficits in PD patients.

β-arrestin2 regulates the anti-inflammatory effects of Salmeterol in lipopolysaccharide-stimulated BV2 cells

Microglial activation contributes to chronic inflammation and neuronal loss in progressive neurodegenerative disorders such as Parkinson's disease (PD). Thus, treatments suppressing microglial activation may have therapeutic benefits to prevent neuronal loss in neurodegenerative diseases. Our previous findings show that Salmeterol, a long-acting β2-adrenergic receptor (β2-AR) agonist, is neuroprotective in two distinct animal models of PD, including where lipopolysaccharide (LPS) from E. coli was used to initiate chronic neurodegeneration. Salmeterol was found to be a potent inhibitor of dopaminergic neurodegeneration by regulating the production of pro-inflammatory mediators from activated microglial cells. In the present study, we investigated the molecular basis of the anti-inflammatory effects of Salmeterol on LPS-activated murine microglial BV2 cells. BV2 cells were pretreated with Salmeterol and followed by stimulation with LPS. Salmeterol inhibited LPS-induced release of the pro-inflammatory mediators such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and nitric oxide from BV2 cells. Additionally, Salmeterol suppressed nuclear translocation of nuclear factor kappa-B (NF-κB) p65 by inhibiting the IκB-α degradation and TAK1 (transforming growth factor-beta-activated kinase1) phosphorylation. We have also found that Salmeterol increases the expression of β-arrestin2 and enhances the interaction between β-arrestin2 and TAB1 (TAK1-binding protein), reduced TAK1/TAB1 mediated activation of NFκB and expression of pro-inflammatory genes. Furthermore, silencing of β-arrestin2 abrogates the anti-inflammatory effects of Salmeterol in LPS-stimulated BV2 cells. Our findings suggest that the anti-inflammatory properties of Salmeterol is β-arrestin2 dependent and also offers novel therapeutics targeting inflammatory pathways to prevent microglial cell activation and neuronal loss in neuroinflammatory diseases like PD.

Regional microglia are transcriptionally distinct but similarly exacerbate neurodegeneration in a culture model of Parkinson's disease

Background

Parkinson’s disease (PD) is characterized by selective degeneration of dopaminergic (DA) neurons of the substantia nigra pars compacta (SN) while neighboring ventral tegmental area (VTA) DA neurons are relatively spared. Mechanisms underlying the selective protection of the VTA and susceptibility of the SN are still mostly unknown. Here, we demonstrate the importance of balance between astrocytes and microglia in the susceptibility of SN DA neurons to the PD mimetic toxin 1-methyl-4-phenylpyridinium (MPP⁺).

Methods

Previously established methods were used to isolate astrocytes and microglia from the cortex (CTX), SN, and VTA, as well as embryonic midbrain DA neurons from the SN and VTA. The transcriptional profile of isolated microglia was examined for 21 canonical pro- and anti-inflammatory cytokines by qRT-PCR with and without MPP⁺ exposure. Homo- and heterotypic co-cultures of neurons and astrocytes were established, and the effect of altering the ratio of astrocytes and microglia in vitro on the susceptibility of midbrain DA neurons to the PD mimetic toxin MPP⁺ was investigated.

Results

We found that regionally isolated microglia (SN, VTA, CTX) exhibit basal differences in their cytokine profiles and that activation of these microglia with MPP⁺ results in differential cytokine upregulation. The addition of microglia to cultures of SN neurons and astrocytes was not sufficient to cause neurodegeneration; however, when challenged with MPP⁺, all regionally isolated microglia resulted in exacerbation of MPP⁺ toxicity which was alleviated by inhibition of microglial activation. Furthermore, we demonstrated that isolated VTA, but not SN, astrocytes were able to mediate protection of both SN and VTA DA neurons even in the presence of exacerbatory microglia; however, this protection could be reversed by increasing the numbers of microglia present.

Conclusion

These results suggest that the balance of astrocytes and microglia within the midbrain is a key factor underlying the selective vulnerability of SN DA neurons seen in PD pathogenesis and that VTA astrocytes mediate protection of DA neurons which can be countered by greater numbers of deleterious microglia.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1181-x) contains supplementary material, which is available to authorized users.

Intact interleukin-10 receptor signaling protects from hippocampal damage elicited by experimental neurotropic virus infection of SJL mice

Theiler’s murine encephalomyelitis virus (TMEV) infection represents an experimental mouse model to study hippocampal damage induced by neurotropic viruses. IL-10 is a pleiotropic cytokine with profound anti-inflammatory properties, which critically controls immune homeostasis. In order to analyze IL-10R signaling following virus-induced polioencephalitis, SJL mice were intracerebrally infected with TMEV. RNA-based next generation sequencing revealed an up-regulation of Il10, Il10rα and further genes involved in IL-10 downstream signaling, including Jak1, Socs3 and Stat3 in the brain upon infection. Subsequent antibody-mediated blockade of IL-10R signaling led to enhanced hippocampal damage with neuronal loss and increased recruitment of CD3⁺ T cells, CD45R⁺ B cells and an up-regulation of Il1α mRNA. Increased expression of Tgfβ and Foxp3 as well as accumulation of Foxp3⁺ regulatory T cells and arginase-1⁺ macrophages/microglia was detected in the hippocampus, representing a potential compensatory mechanism following disturbed IL-10R signaling. Additionally, an increased peripheral Chi3l3 expression was found in spleens of infected mice, which may embody reactive regulatory mechanisms for prevention of excessive immunopathology. The present study highlights the importance of IL-10R signaling for immune regulation and its neuroprotective properties in the context of an acute neurotropic virus infection.

Estrogen receptor-β of microglia underlies sexual differentiation of neuronal protection via ginsenosides in mice brain

AIMS

Streptococcus pneumoniae infection in acute bacterial meningitis can lead to widespread brain damage and mortality. Inflammatory responses by immune cells in the brain are thought to determine the degree of brain injury. Yet, the mechanisms underlying host responses to pneumococcal meningitis are largely unknown. To explore host responses as a potential therapeutic target for preventing brain injury after pneumococcal meningitis.

METHODS

We evaluated signaling mechanisms that minimize neuronal damage caused by pneumococcal infection; specifically, we assessed pathways related to neuronal survival after enhancing estrogen receptor-β (ER-β) expression using a natural therapeutic substance known as ginsenoside Rb1 and Rg3 enhanced ginseng.

RESULTS

Tissue damage caused by bacterial infection was reduced in Rb1/Rg3-treated mice as a result of microglial activation and the inhibition of apoptosis. Furthermore, Rb1 upregulated the expression of brain-derived neurotrophic factor (BDNF) as well as anti-apoptotic factors including Bcl-2 and Bcl-xL. Using BV2 microglial cells in vitro, Rb1 treatment inhibited microglial apoptosis in a manner associated with JAK2/STAT5 phosphorylation.

CONCLUSION

After S. pneumoniae infection in mice, particularly in female mice, Rb1-containing ginseng increased bacterial clearance and survival. These findings inform our understanding of the host immune response to pneumococcal meningitis.

Oxymatrine attenuates lipopolysaccharide-induced acute lung injury by activating the epithelial sodium channel and suppressing the JNK signaling pathway

The epithelial sodium channel (ENaC) and mitogen-activated protein kinase (MAPK) pathway have been reported to be associated with the progression of acute lung injury (ALI). Oxymatrine (OMT) alone or combined with other drugs can ameliorate paraquat- or oleic acid-induced lung injury. However, the effect of OMT on lipopolysaccharide (LPS)-induced ALI remains unknown. The aim of the present study was to evaluate whether OMT can attenuate LPS-induced ALI through regulation of the ENaC and MAPK pathway using an ALI mouse model. Histological assessment of the lung and inflammatory cell counts in bronchoalveolar lavage fluid (BALF) were performed by H&E and Wright-Giemsa staining. The lung wet/dry (W/D) weight ratio and the levels of tumor necrosis factor-α (TNF-α), C-reactive protein (CRP), ENaC subunits, and the MAPK pathway members were determined. Isolated type II rat alveolar epithelial cells were incubated with OMT 30 min before LPS stimulation to investigate the activation of ENaC and the MAPK pathway. The results showed that OMT remarkably alleviated histopathologic changes in lung and pulmonary edema, reduced inflammatory cell counts in BALF, and decreased TNF-α and CRP levels in a dose-dependent manner. OMT significantly increased the three subunits of ENaC proteins in vivo and in vitro, while it decreased p-ERK/ERK, p-p38/p38, and p-JNK/JNK ratios in vivo. However, only the JNK pathway was markedly inhibited in vitro following pretreatment with OMT. Collectively, the results suggested that OMT might alleviate LPS-induced ALI by elevating ENaC proteins and inhibiting the JNK signaling pathway.

Albumin-Conjugated Lipid-Based Multilayered Nanoemulsion Improves Drug Specificity and Anti-Inflammatory Potential at the Spinal Cord Injury gSite after Intravenous Administration

Albumin-conjugated multilayered nanoemulsion (albumin-MNE) of methyl prednisolone (MP) was developed to ensure the specificity of the drug at the spinal cord injury (SCI) site. MNE was prepared by emulsification followed by ionic deposition of oppositely charged polymer followed by albumin conjugation using N-hydroxysuccinimide. Prepared nanoemulsion was characterized for particle size, polydispersity index (PDI), zeta potential (Zp), pH, viscosity, and entrapment efficiency. It was further evaluated for shape and morphological analysis, in vitro release, cell viability, and in vivo efficacy against post SCI-like conditions in terms of behavioral assessment, histopathological evaluation, and immunoflorescence assay of the histological sections showing Bax-driven apoptosis. Entrapment efficiency, particle size, PDI, and Zp of spherical-shaped, smooth-surfaced MNE droplets were found to be 68.9%, 83.2 ± 14.4 nm, 0.231, and + 62.7 mV, respectively. In vitro release of MP from MNE and albumin-MNE was observed to be 68.5 and 72.2% after 96th hour of the study. MNE showed higher viability of astrocytes than MP solution. Albumin-MNE improved behavior of SCI rat and histopathological conditions in a very effective manner when compared with MNE. Immunoflorescence assay reveals explicit decline in mitochondrial-mediated apoptosis by sub-cellular upregulation of Bax at spinal cord injury site. In conclusion, albumin-MNE delivered MP specifically at SCI site and avoided its instant availability inside astrocytes culture. On account of which the chitosan stabilized, lecithin-emulsified, multilayered nanoemulsion of MP depicts higher efficacy and safety than MNE and may offer safe and effective mean for the treatment of post SCI-like conditions in human.

Pericyte Secretome

The role of pericytes seems to extend beyond their known function in angiogenesis, fibrosis and wound healing, blood-brain barrier maintenance, and blood flow regulation. More and more data are currently accumulating indicating that pericytes, uniquely positioned at the interface between blood and parenchyma, secrete a large plethora of different molecules in response to microenvironmental changes. Their secretome is tissue-specific and stimulus-specific and includes pro- and anti-inflammatory factors, growth factors, and extracellular matrix as well as microvesicles suggesting the important role of pericytes in the regulation of immune response and immune evasion of tumors. However, the angiogenic and trophic secretome of pericytes indicates that their secretome plays a role in physiological homeostasis but possibly also in disease progression or could be exploited for regenerative processes in the future. This book chapter summarizes the current data on the secretory properties of pericytes from different tissues in response to certain pathological stimuli such as inflammatory stimuli, hypoxia, high glucose, and others and thereby aims to provide insights into the possible role of pericytes in these conditions.

Neuroprotective effect of total flavonoids from Ilex pubescens against focal cerebral ischemia/reperfusion injury in rats

Ilex pubescens is commonly used in traditional Chinese medicine to treat cardiovascular and cerebrovascular diseases, such as coronary artery disease and stroke. However, the underlying mechanisms remain to be fully elucidated. The aim of the present study was to investigate the effects of Ilex pubescens total flavonoids (IPTF) on neuroprotection and the potential mechanisms in a rat model of focal cerebral ischemia/reperfusion (I/R) injury. Rats were pretreated with intragastric administration of IPTF at doses of 200 and 100 mg/kg for 5 days; middle cerebral artery occlusion surgery was then performed to induce cerebral I/R injury. Neurological deficits were determined using the 5‑point neurological function score evaluation system, brain infarct sizes were determined by 2,3,5‑triphenyltetrazolium chloride staining and alterations in brain histology were determined by hematoxylin and eosin staining. The neurological deficit score, the infarcted area and the brain tissue pathological injury were significantly reduced when the rats were pretreated with IPTF. In addition, inflammatory mediators and neurotrophic factors in the brain were investigated. IPTF pretreatment decreased the activities of total nitric oxide synthase (TNOS), induced NOS (iNOS) and constitutive NOS (cNOS), and the levels of nitric oxide (NO), interleukin‑1β (IL‑1β) and tumor necrosis factor‑α (TNF‑α), however, it increased the levels of IL‑10 in brain tissues. Furthermore, pretreatment with IPTF also increased the protein expressions of brain‑derived neurotrophic factor, glial cell‑derived neurotrophic factor and vascular endothelial growth factor, when compared with the model group. In conclusion, the results of the present study demonstrated that IPTF has a neuroprotective effect against focal cerebral I/R injury in rats. The mechanism may be associated with the decreased production of certain proinflammatory cytokines including NO, IL‑1β, TNF‑α, TNOS, iNOS and cNOS, the increased production of the anti‑inflammatory cytokine IL‑10 and the increased secretion of neurotrophic factors.

Licochalcone A Prevents the Loss of Dopaminergic Neurons by Inhibiting Microglial Activation in Lipopolysaccharide (LPS)-Induced Parkinson's Disease Models

The neuroprotective effects of Licochalcone A (Lico.A), a flavonoid isolated from the herb licorice, in Parkinson's disease (PD) have not been elucidated. The prominent pathological feature of PD is the loss of dopaminergic neurons. The crucial role of neuroinflammation induced by activated microglia in dopaminergic neurodegeneration has been validated. In this study, we explore the therapeutic effects of Lico.A in lipopolysaccharide (LPS)-induced PD models in vivo and in vitro. We find that Lico.A significantly inhibits LPS-stimulated production of pro-inflammatory mediators and microglial activation by blocking the phosphorylation of extracellular signal-regulated kinase (ERK1/2) and nuclear factor κB (NF-κB) p65 in BV-2 cells. In addition, through cultured primary mesencephalic neuron-glia cell experiments, we illustrate that Lico.A attenuates the decrease in [³H] dopamine (DA) uptake and the loss of tyrosine hydroxylase-immunoreactive (TH-ir) neurons in LPS-induced PD models in vitro. Furthermore, LPS intoxication in rats results in microglial activation, dopaminergic neurodegeneration and significant behavioral deficits in vivo. Lico.A treatment prevents microglial activation and reduction of dopaminergic neuron and ameliorates PD-like behavioral impairments. Thus, these results demonstrate for the first time that the neuroprotective effects of Lico.A are associated with microglia and anti-inflammatory effects in PD models.

Interleukin-10 inhibits neuroinflammation-mediated apoptosis of ventral mesencephalic neurons via JAK-STAT3 pathway

Neuroinflammation plays an important role in the pathogenesis of Parkinson's disease. Interleukin (IL)-10 is one of the most important and best anti-inflammatory cytokines. The objective of this report is to investigate whether IL-10 has any role in protecting ventral mesencephalic (VM) neurons in in vitro model of neuroinflammation. In this study, primary neuron-enriched culture was prepared from the VM tissues of E14 embryos of rats. The cells were pretreated with IL-10 (15 or 50ng/mL) for 1h followed by lipopolysaccharide (LPS, 50ng/mL) application. We found LPS induced neuronal apoptosis and loss while pretreatment with IL-10 reduced neuronal damage after exposure of LPS toxicity. Furthermore, signal transduction pathways related to IL-10 in VM neurons were studied in inflammatory condition. We used both shRNA and pharmacologic inhibition to determine the role of the IL-10 receptor (IL-10R) and its downstream signaling pathways in LPS-induced VM neuronal toxicity. Silence of the IL-10R gene in VM neurons abolished IL-10 mediated protection and the properties of anti-inflammatory and anti-apoptosis. IL-10 also induced phosphorylation of signal transducer and activator of transcription (STAT) 3 in VM neurons. Pretreatment with the specific Janus kinase (JAK) inhibitor reduced STAT3 phosphorylation and blocked IL-10 mediated protection against LPS. These findings suggest that IL-10 provides neuroprotection by acting via IL-10R and its down-stream JAK-STAT3 signal pathways in VM neurons.

CD8+ T Cells and Endogenous IL-10 Are Required for Resolution of Chemotherapy-Induced Neuropathic Pain

Chemotherapy-induced peripheral neuropathy (CIPN), characterized by pain and numbness in hands and feet, is a common side effect of cancer treatment. In most patients, symptoms of CIPN subside after treatment completion. However, in a substantial subgroup, CIPN persists long into survivorship. Impairment in pain resolution pathways may explain persistent CIPN. We investigated the contribution of T cells and endogenous interleukin (IL)-10 to resolution of CIPN. Paclitaxel-induced mechanical allodynia was prolonged in T-cell-deficient (Rag1^-/-) mice compared with wild-type (WT) mice. There were no differences between WT and Rag1^-/- mice in severity of paclitaxel-induced mechanical allodynia. Adoptive transfer of either CD3⁺ or CD8⁺, but not CD4⁺, T cells to Rag1^-/- mice normalized resolution of CIPN. Paclitaxel treatment increased the number of T cells in lumbar dorsal root ganglia (DRG), where CD8⁺ T cells were the major subset. Inhibition of endogenous IL-10 signaling by intrathecal injection of anti-IL-10 to WT mice or Rag1^-/- mice reconstituted with CD8⁺ T cells delayed recovery from paclitaxel-induced mechanical allodynia. Recovery was also delayed in IL-10 knock-out mice. Conversely, administration of exogenous IL-10 attenuated paclitaxel-induced allodynia. In vitro, IL-10 suppressed abnormal paclitaxel-induced spontaneous discharges in DRG neurons. Paclitaxel increased DRG IL-10 receptor expression and this effect requires CD8⁺ T cells. In conclusion, we identified a novel mechanism for resolution of CIPN that requires CD8⁺ T cells and endogenous IL-10. We propose that CD8⁺ T cells increase DRG IL-10 receptor expression and that IL-10 suppresses the abnormal paclitaxel-induced spontaneous discharges by DRG neurons to promote recovery from CIPN.

SIGNIFICANCE STATEMENT

Chemotherapy-induced peripheral neuropathy persists after completion of cancer treatment in a significant subset of patients, whereas others recover. Persistent neuropathy after completion of cancer treatment severely affects quality of life. We propose that understanding how neuropathy resolves will identify novel avenues for treatment. We identified a novel and critical role for CD8⁺ T cells and for endogenous IL-10 in recovery from paclitaxel-induced neuropathy in mice. Enhancing the capacity of CD8⁺ T cells to promote resolution or increasing IL-10 signaling are promising targets for novel interventions. Clinically, peripheral blood CD8⁺ T-cell function and/or the capacity of individuals to produce IL-10 may represent biomarkers of risk for developing persistent peripheral neuropathy after completion of cancer treatment.

Nano-carrier mediated co-delivery of methyl prednisolone and minocycline for improved post-traumatic spinal cord injury conditions in rats

OBJECTIVE

The objective of this study is to investigate the fate of albumin coupled nanoparticulate system over non-targeted drug carrier in the treatment of hemisectioned spinal cord injury (SCI).

SIGNIFICANCE

Targeted delivery of methyl prednisolone (MP) and minocycline (MC) portrayed improved therapeutic efficacy as compared with non-targeted nanoparticles (NPS).

METHODS

Albumin coupled, chitosan stabilized, and cationic NPS (albumin-MP + MC - NPS) of poly-(lactide-co-glycolic acid) were prepared using the emulsion solvent evaporation method. Prepared NPS were characterized for drug entrapment efficiency, particle size, poly-dispersity index (PDI), zeta potential, and morphological characteristics. Their evaluation was done based on the pharmaceutical, toxicological, and pharmacological parameters.

RESULTS AND DISCUSSION

In vitro release of MP + MC from albumin-MP + MC - NPS and MP + MC - NPS was observed to be very controlled for the period of eight days. Cell viability study portrayed non-toxic nature of the developed NPS. Albumin-MP + MC - NPS showed prominent anti-inflammatory potential as compared with non-targeted NPS (MP + MC - NPS) when studied in LPS-induced inflamed astrocytes. Albumin-MP + MC - NPS reduced lesional volume and improved behavioral outcomes significantly in rats with SCI (hemisectioned injury model) when compared with that of MP + MC - NPS.

CONCLUSIONS

Albumin-coupled NPS carrier offered an effective method of SCI treatment following safe co-administration of MP and MC. The in vitro and in vivo effectiveness of MP + MC was improved tremendously when compared with the effectiveness showed by MP + MC - NPS. That could be attributed to the site specific, controlled release of MP + MC to the inflammatory site.

Th17 Cells Induce Dopaminergic Neuronal Death via LFA-1/ICAM-1 Interaction in a Mouse Model of Parkinson's Disease

T helper (Th)17 cells, a subset of CD4⁺ T lymphocytes, have strong pro-inflammatory property and appear to be essential in the pathogenesis of many inflammatory diseases. However, the involvement of Th17 cells in Parkinson's disease (PD) that is characterized by a progressive degeneration of dopaminergic (DAergic) neurons in the nigrostriatal system is unclear. Here, we aimed to demonstrate that Th17 cells infiltrate into the brain parenchyma and induce neuroinflammation and DAergic neuronal death in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)- or 1-methyl-4-phenylpyridinium (MPP⁺)-induced PD models. Blood-brain barrier (BBB) disruption in the substantia nigra (SN) was assessed by the signal of FITC-labeled albumin that was injected into blood circulation via the ascending aorta. Live cell imaging system was used to observe a direct contact of Th17 cells with neurons by staining these cells using the two adhesion molecules, leukocyte function-associated antigen (LFA)-1 and intercellular adhesion molecule (ICAM)-1, respectively. Th17 cells invaded into the SN where BBB was disrupted in MPTP-induced PD mice. Th17 cells exacerbated DAergic neuronal loss and pro-inflammatory/neurotrophic factor disorders in MPP⁺-treated ventral mesencephalic (VM) cell cultures. A direct contact of LFA-1-stained Th17 cells with ICAM-1-stained VM neurons was dynamically captured. Either blocking LFA-1 in Th17 cells or blocking ICAM-1 in VM neurons with neutralizing antibodies abolished Th17-induced DAergic neuronal death. These results establish that Th17 cells infiltrate into the brain parenchyma of PD mice through lesioned BBB and exert neurotoxic property by promoting glial activation and importantly by a direct damage to neurons depending on LFA-1/ICAM-1 interaction.