Inflammation mediates varying effects in neurogenesis: relevance to the pathogenesis of brain injury and neurodegenerative disorders

Radiation-Induced Brain Injury with Special Reference to Astrocytes as a Therapeutic Target

Radiotherapy is one of the primary modalities for oncologic treatment and has been utilized at least once in over half of newly diagnosed cancer patients. Cranial radiotherapy has significantly enhanced the long-term survival rates of patients with brain tumors. However, radiation-induced brain injury, particularly hippocampal neuronal damage along with impairment of neurogenesis, inflammation, and gliosis, adversely affects the quality of life for these patients. Astrocytes, a type of glial cell that are abundant in the brain, play essential roles in maintaining brain homeostasis and function. Despite their importance, the pathophysiological changes in astrocytes induced by radiation have not been thoroughly investigated, and no systematic or comprehensive review addressing the effects of radiation on astrocytes and related diseases has been conducted. In this paper, we review current studies on the neurophysiological roles of astrocytes following radiation exposure. We describe the pathophysiological changes in astrocytes, including astrogliosis, astrosenescence, and the associated cellular and molecular mechanisms. Additionally, we summarize the roles of astrocytes in radiation-induced impairments of neurogenesis and the blood-brain barrier (BBB). Based on current research, we propose that brain astrocytes may serve as potential therapeutic targets for treating radiation-induced brain injury (RIBI) and subsequent neurological and neuropsychiatric disorders.

The chemotherapy agent doxorubicin induces CNS expression of Ascl1, a regulator of adult neurogenesis and differentiation

Cancer-related cognitive impairment (CRCI) is a common side effect of cancer and its treatments. Cancer chemotherapy has been associated with hippocampal dysfunction and memory impairment. We investigated the effects of one chemotherapy agent, doxorubicin, on the transcription factor Ascl1 and proliferation of stem cells in the brain. We used an inducible mouse model designed to express TdTomato in Ascl1-lineage cells. Five to six-month-old Ascl1-CreERT2:ROSA mice were treated peripherally with a single dose of either doxorubicin (10 mg/kg) or DMSO control (n = 9 per group, n = 4-5 per sex). We analyzed brains of mice that had been exposed to doxorubicin for 2 weeks and had induced Ascl1 expression after the first week. We used immunostaining of neurogenesis stage specific markers to evaluate the doxorubicin effects on neuronal differentiation in the dentate gyrus of the hippocampus. Overall, doxorubicin significantly increased Ascl1 expression by 81% at this time point. As measured by Ascl1 double stains with Sox2, GFAP, and NeuroD1, doxorubicin-treated mice experienced an increase in Ascl1-mediated neural proliferation compared to control. A similar significant increase in the number of Ascl1-expressing cells (by 146%) after doxorubicin treatment was observed in the gray matter of the cerebral cortex. Thus, rather than leading to the loss of developing neurons, we found that a single dose of doxorubicin increased their appearance and progression, suggesting that hippocampal losses from chemotherapies may require greater and more sustained damage.

Insufficient Sleep and Alzheimer's Disease: Potential Approach for Therapeutic Treatment Methods

The interaction between Alzheimer's disease (AD) and sleep deprivation has recently gained attention in the scientific literature, and recent advances suggest that AD epidemiology management should coincide with the management of sleeping disorders. This review focuses on the aspects of the mechanisms underlying the link between AD and insufficient sleep with progressing age. We also provide information which could serve as evidence for future treatments of AD from the early stages in connection with sleep disorder medication.

Microglia-induced neuroinflammation in hippocampal neurogenesis following traumatic brain injury

Traumatic brain injury (TBI) is one of the most causes of death and disability among people, leading to a wide range of neurological deficits. The important process of neurogenesis in the hippocampus, which includes the production, maturation and integration of new neurons, is affected by TBI due to microglia activation and the inflammatory response. During brain development, microglia are involved in forming or removing synapses, regulating the number of neurons, and repairing damage. However, in response to injury, activated microglia release a variety of pro-inflammatory cytokines, chemokines and other neurotoxic mediators that exacerbate post-TBI injury. These microglia-related changes can negatively affect hippocampal neurogenesis and disrupt learning and memory processes. To date, the intracellular signaling pathways that trigger microglia activation following TBI, as well as the effects of microglia on hippocampal neurogenesis, are poorly understood. In this review article, we discuss the effects of microglia-induced neuroinflammation on hippocampal neurogenesis following TBI, as well as the intracellular signaling pathways of microglia activation.

Increased neural differentiation after a single session of aerobic exercise in older adults

Aging is associated with decreased cognitive function. One theory posits that this decline is in part due to multiple neural systems becoming dedifferentiated in older adults. Exercise is known to improve cognition in older adults, even after only a single session. We hypothesized that one mechanism of improvement is a redifferentiation of neural systems. We used a within-participant, cross-over design involving 2 sessions: either 30 minutes of aerobic exercise or 30 minutes of seated rest (n = 32; ages 55-81 years). Both functional Magnetic Resonance Imaging (fMRI) and Stroop performance were acquired soon after exercise and rest. We quantified neural differentiation via general heterogeneity regression. There were 3 prominent findings following the exercise. First, participants were better at reducing Stroop interference. Second, while there was greater neural differentiation within the hippocampal formation and cerebellum, there was lower neural differentiation within frontal cortices. Third, this greater neural differentiation in the cerebellum and temporal lobe was more pronounced in the older ages. These data suggest that exercise can induce greater neural differentiation in healthy aging.

Acute cycling exercise and hippocampal subfield function and microstructure in healthy older adults

Aging is associated with deterioration in dentate gyrus (DG) and CA3, both crucial hippocampal subfields for age susceptible memory processes such as mnemonic discrimination (MD). Meanwhile, a single aerobic exercise session alters DG/CA3 function and neural activity in both rats and younger adults and can elicit short-term microstructural alterations in the hippocampus of older adults. However, our understanding of the effects of acute exercise on hippocampal subfield integrity via function and microstructure in older adults is limited. Thus, a within subject-design was employed to determine if 20-min of moderate to vigorous aerobic exercise alters bilateral hippocampal subfield function and microstructure using high-resolution functional magnetic resonance imaging (fMRI) during an MD task (n = 35) and high angular resolution multi-shell diffusion imaging (n = 31), in healthy older adults, compared to seated rest. Following the exercise condition, participants exhibited poorer MD performance, particularly when their perception of effort was higher. Exercise was also related to lower MD-related activity within the DG/CA3 but not CA1 subfield. Finally, after controlling for whole brain gray matter diffusion, exercise was associated with lower neurite density index (NDI) within the DG/CA3. However, exercise-related differences in DG/CA3 activity and NDI were not associated with differences in MD performance. Our results suggest moderate to vigorous aerobic exercise may temporarily inhibit MD performance, and suppress DG/CA3 MD-related activity and NDI, potentially through neuroinflammatory/glial processes. However, additional studies are needed to confirm whether these short-term changes in behavior and hippocampal subfield neurophysiology are beneficial and how they might relate to long-term exercise habits.

Neuroprotective effects of meloxicam on transient brain ischemia in rats: the two faces of anti-inflammatory treatments

The inflammatory response plays an important role in neuroprotection and regeneration after ischemic insult. The use of non-steroidal anti-inflammatory drugs has been a matter of debate as to whether they have beneficial or detrimental effects. In this context, the effects of the anti-inflammatory agent meloxicam have been scarcely documented after stroke, but its ability to inhibit both cyclooxygenase isoforms (1 and 2) could be a promising strategy to modulate post-ischemic inflammation. This study analyzed the effect of meloxicam in a transient focal cerebral ischemia model in rats, measuring its neuroprotective effect after 48 hours and 7 days of reperfusion and the effects of the treatment on the glial scar and regenerative events such as the generation of new progenitors in the subventricular zone and axonal sprouting at the edge of the damaged area. We show that meloxicam's neuroprotective effects remained after 7 days of reperfusion even if its administration was restricted to the two first days after ischemia. Moreover, meloxicam treatment modulated glial scar reactivity, which matched with an increase in axonal sprouting. However, this treatment decreased the formation of neuronal progenitor cells. This study discusses the dual role of anti-inflammatory treatments after stroke and encourages the careful analysis of both the neuroprotective and the regenerative effects in preclinical studies.

Modulation of neurotrophic factors in the treatment of dementia, stroke and TBI: Effects of Cerebrolysin

Neurotrophic factors (NTFs) are involved in the pathophysiology of neurological disorders such as dementia, stroke and traumatic brain injury (TBI), and constitute molecular targets of high interest for the therapy of these pathologies. In this review we provide an overview of current knowledge of the definition, discovery and mode of action of five NTFs, nerve growth factor, insulin-like growth factor 1, brain derived NTF, vascular endothelial growth factor and tumor necrosis factor alpha; as well as on their contribution to brain pathology and potential therapeutic use in dementia, stroke and TBI. Within the concept of NTFs in the treatment of these pathologies, we also review the neuropeptide preparation Cerebrolysin, which has been shown to resemble the activities of NTFs and to modulate the expression level of endogenous NTFs. Cerebrolysin has demonstrated beneficial treatment capabilities in vitro and in clinical studies, which are discussed within the context of the biochemistry of NTFs. The review focuses on the interactions of different NTFs, rather than addressing a single NTF, by outlining their signaling network and by reviewing their effect on clinical outcome in prevalent brain pathologies. The effects of the interactions of these NTFs and Cerebrolysin on neuroplasticity, neurogenesis, angiogenesis and inflammation, and their relevance for the treatment of dementia, stroke and TBI are summarized.

Detrimental Effects of Alcohol-Induced Inflammation on Brain Health: From Neurogenesis to Neurodegeneration

Alcohol consumption is known to cause several brain anomalies. The pathophysiological changes associated with alcohol intoxication are mediated by various factors, most notable being inflammation. Alcohol intoxication may cause inflammation through several molecular mechanisms in multiple organs, including the brain, liver and gut. Alcohol-induced inflammation in the brain and gut are intricately connected. In the gut, alcohol consumption leads to the weakening of the intestinal barrier, resulting in bacteria and bacterial endotoxins permeating into the bloodstream. These bacterial endotoxins can infiltrate other organs, including the brain, where they cause cognitive dysfunction and neuroinflammation. Alcohol can also directly affect the brain by activating immune cells such as microglia, triggering the release of pro-inflammatory cytokines and neuroinflammation. Since alcohol causes the death of neural cells, it has been correlated to an increased risk of neurodegenerative diseases. Besides, alcohol intoxication has also negatively affected neural stem cells, affecting adult neurogenesis and causing hippocampal dysfunctions. This review provides an overview of alcohol-induced brain anomalies and how inflammation plays a crucial mechanistic role in alcohol-associated pathophysiology.

Mass cytometric analysis of the immune cell landscape after traumatic brain injury elucidates the role of complement and complement receptors in neurologic outcomes

Following traumatic brain injury (TBI), a neuroinflammatory response can persist for years and contribute to the development of chronic neurological manifestations. Complement plays a central role in post-TBI neuroinflammation, and C3 opsonins and the anaphylatoxins (C3a and C5a) have been implicated in promoting secondary injury. We used single cell mass cytometry to characterize the immune cell landscape of the brain at different time points after TBI. To specifically investigate how complement shapes the post-TBI immune cell landscape, we analyzed TBI brains in the context of CR2-Crry treatment, an inhibitor of C3 activation. We analyzed 13 immune cell types, including peripheral and brain resident cells, and assessed expression of various receptors. TBI modulated the expression of phagocytic and complement receptors on both brain resident and infiltrating peripheral immune cells, and distinct functional clusters were identified within same cell populations that emerge at different phases after TBI. In particular, a CD11c+ (CR4) microglia subpopulation continued to expand over 28 days after injury, and was the only receptor to show continuous increase over time. Complement inhibition affected the abundance of brain resident immune cells in the injured hemisphere and impacted the expression of functional receptors on infiltrating cells. A role for C5a has also been indicated in models of brain injury, and we found significant upregulation of C5aR1 on many immune cell types after TBI. However, we demonstrated experimentally that while C5aR1 is involved in the infiltration of peripheral immune cells into the brain after injury, it does not alone affect histological or behavioral outcomes. However, CR2-Crry improved post-TBI outcomes and reduced resident immune cell populations, as well as complement and phagocytic receptor expression, indicating that its neuroprotective effects are mediated upstream of C5a generation, likely via modulating C3 opsonization and complement receptor expression.

TIPE2 regulates the response of BV2 cells to lipopolysaccharide by the crosstalk between PI3K/AKT signaling and microglia M1/M2 polarization

Tumor necrosis factor (TNF)-α-induced protein 8-like 2 (TIPE2) is a crucial negative regulator of both adaptive and innate immunity, which helps maintain the dynamic balance of the immune system by negatively regulating the signaling of T-cell receptors (TCR) and Toll-like receptors (TLR). In this study, we aimed to investigate the role and molecular mechanism of TIPE2 using a lipopolysaccharide (LPS)-induced inflammatory injury model in BV2 cells. Specifically, we constructed a BV2 cell line of TIPE2-overexpression or TIPE2-knockdown via lentiviral transfection. Our results demonstrated that overexpression of TIPE2 downregulated the expression of pro-inflammatory cytokines IL-1β and IL-6, which was reversed by knockdown of TIPE2 in the inflammation model of BV2 cells. In addition, overexpression of TIPE2 resulted in the conversion of BV2 cells to the M2 phenotype, while the knockdown of TIPE2 promoted the transformation of BV2 cells to the M1 phenotype. Notably, our co-culture experiments with neuronal cells SH-SY5Y showed that the overexpression of TIPE2 in inflammation-injured BV2 cells exhibited a protective effect on the neuronal cells. Finally, western blot analysis demonstrated that TIPE2 significantly reduced the expression of p-PI3K, p-AKT, p-p65, and p-IκBα in LPS treated BV2 cells, and inhibited the activation of NF-κB through the dephosphorylation of PI3K/AKT. These results suggest that TIPE2 plays an important role in mediating neuroinflammatory responses and may be involved in neuroprotection by modulating the phenotypic changes of BV2 cells and regulating the pro-inflammatory responses through the PI3K/AKT and NF-κB signaling pathways. In conclusion, our study provides new insights into the crucial role of TIPE2 in regulating neuroinflammatory responses and highlights its potential as a therapeutic target for neuroprotection.

Mice as an Animal Model for Japanese Encephalitis Virus Research: Mouse Susceptibility, Infection Route, and Viral Pathogenesis

Japanese encephalitis virus (JEV), a zoonotic flavivirus, is principally transmitted by hematophagous mosquitoes, continually between susceptible animals and incidentally from those animals to humans. For almost a century since its discovery, JEV was geographically confined to the Asia-Pacific region with recurrent sizable outbreaks involving wildlife, livestock, and people. However, over the past decade, it has been detected for the first time in Europe (Italy) and Africa (Angola) but has yet to cause any recognizable outbreaks in humans. JEV infection leads to a broad spectrum of clinical outcomes, ranging from asymptomatic conditions to self-limiting febrile illnesses to life-threatening neurological complications, particularly Japanese encephalitis (JE). No clinically proven antiviral drugs are available to treat the development and progression of JE. There are, however, several live and killed vaccines that have been commercialized to prevent the infection and transmission of JEV, yet this virus remains the main cause of acute encephalitis syndrome with high morbidity and mortality among children in the endemic regions. Therefore, significant research efforts have been directed toward understanding the neuropathogenesis of JE to facilitate the development of effective treatments for the disease. Thus far, multiple laboratory animal models have been established for the study of JEV infection. In this review, we focus on mice, the most extensively used animal model for JEV research, and summarize the major findings on mouse susceptibility, infection route, and viral pathogenesis reported in the past and present, and discuss some unanswered key questions for future studies.

The Role and Mechanism of Transglutaminase 2 in Regulating Hippocampal Neurogenesis after Traumatic Brain Injury

Traumatic brain injury usually results in neuronal loss and cognitive deficits. Promoting endogenous neurogenesis has been considered as a viable treatment option to improve functional recovery after TBI. However, neural stem/progenitor cells (NSPCs) in neurogenic regions are often unable to migrate and differentiate into mature neurons at the injury site. Transglutaminase 2 (TGM2) has been identified as a crucial component of neurogenic niche, and significantly dysregulated after TBI. Therefore, we speculate that TGM2 may play an important role in neurogenesis after TBI, and strategies targeting TGM2 to promote endogenous neural regeneration may be applied in TBI therapy. Using a tamoxifen-induced Tgm2 conditional knockout mouse line and a mouse model of stab wound injury, we investigated the role and mechanism of TGM2 in regulating hippocampal neurogenesis after TBI. We found that Tgm2 was highly expressed in adult NSPCs and up-regulated after TBI. Conditional deletion of Tgm2 resulted in the impaired proliferation and differentiation of NSPCs, while Tgm2 overexpression enhanced the abilities of self-renewal, proliferation, differentiation, and migration of NSPCs after TBI. Importantly, injection of lentivirus overexpressing TGM2 significantly promoted hippocampal neurogenesis after TBI. Therefore, TGM2 is a key regulator of hippocampal neurogenesis and a pivotal therapeutic target for intervention following TBI.

Aging with TBI vs. Aging: 6-month temporal profiles for neuropathology and astrocyte activation converge in behaviorally relevant thalamocortical circuitry of male and female rats

Traumatic brain injury (TBI) manifests late-onset and persisting clinical symptoms with implications for sex differences and increased risk for the development of age-related neurodegenerative diseases. Few studies have evaluated chronic temporal profiles of neuronal and glial pathology that include sex as a biological variable. After experimental diffuse TBI, late-onset and persisting somatosensory hypersensitivity to whisker stimulation develops at one-month post-injury and persists to at least two months post-injury in male rats, providing an in vivo model to evaluate the temporal profile of pathology responsible for morbidity. Whisker somatosensation is dependent on signaling through the thalamocortical relays of the whisker barrel circuit made up of glutamatergic projections between the ventral posteromedial nucleus of the thalamus (VPM) and primary somatosensory barrel cortex (S1BF) with inhibitory (GABA) innervation from the thalamic reticular nucleus (TRN) to the VPM. To evaluate the temporal profiles of pathology, male and female Sprague Dawley rats ( n = 5-6/group) were subjected to sham surgery or midline fluid percussion injury (FPI). At 7-, 56-, and 168-days post-injury (DPI), brains were processed for amino-cupric silver stain and glial fibrillary acidic protein (GFAP) immunoreactivity, where pixel density of staining was quantified to determine the temporal profile of neuropathology and astrocyte activation in the VPM, S1BF, and TRN. FPI induced significant neuropathology in all brain regions at 7 DPI. At 168 DPI, neuropathology remained significantly elevated in the VPM and TRN, but returned to sham levels in the S1BF. GFAP immunoreactivity was increased as a function of FPI and DPI, with an FPI × DPI interaction in all regions and an FPI × Sex interaction in the S1BF. The interactions were driven by increased GFAP immunoreactivity in shams over time in the VPM and TRN. In the S1BF, GFAP immunoreactivity increased at 7 DPI and declined to age-matched sham levels by 168 DPI, while GFAP immunoreactivity in shams significantly increased between 7 and 168 days. The FPI × Sex interaction was driven by an overall greater level of GFAP immunoreactivity in FPI males compared to FPI females. Increased GFAP immunoreactivity was associated with an increased number of GFAP-positive soma, predominantly at 7 DPI. Overall, these findings indicate that FPI, time post-injury, sex, region, and aging with injury differentially contribute to chronic changes in neuronal pathology and astrocyte activation after diffuse brain injury. Thus, our results highlight distinct patterns of pathological alterations associated with the development and persistence of morbidity that supports chronic neuropathology, especially within the thalamus. Further, data indicate a convergence between TBI-induced and age-related pathology where further investigation may reveal a role for divergent astrocytic phenotypes associated with increased risk for neurodegenerative diseases.

The Dialogue Between Neuroinflammation and Adult Neurogenesis: Mechanisms Involved and Alterations in Neurological Diseases

Adult neurogenesis occurs mainly in the subgranular zone of the hippocampal dentate gyrus and the subventricular zone of the lateral ventricles. Evidence supports the critical role of adult neurogenesis in various conditions, including cognitive dysfunction, Alzheimer's disease (AD), and Parkinson's disease (PD). Several factors can alter adult neurogenesis, including genetic, epigenetic, age, physical activity, diet, sleep status, sex hormones, and central nervous system (CNS) disorders, exerting either pro-neurogenic or anti-neurogenic effects. Compelling evidence suggests that any insult or injury to the CNS, such as traumatic brain injury (TBI), infectious diseases, or neurodegenerative disorders, can provoke an inflammatory response in the CNS. This inflammation could either promote or inhibit neurogenesis, depending on various factors, such as chronicity and severity of the inflammation and underlying neurological disorders. Notably, neuroinflammation, driven by different immune components such as activated glia, cytokines, chemokines, and reactive oxygen species, can regulate every step of adult neurogenesis, including cell proliferation, differentiation, migration, survival of newborn neurons, maturation, synaptogenesis, and neuritogenesis. Therefore, this review aims to present recent findings regarding the effects of various components of the immune system on adult neurogenesis and to provide a better understanding of the role of neuroinflammation and neurogenesis in the context of neurological disorders, including AD, PD, ischemic stroke (IS), seizure/epilepsy, TBI, sleep deprivation, cognitive impairment, and anxiety- and depressive-like behaviors. For each disorder, some of the most recent therapeutic candidates, such as curcumin, ginseng, astragaloside, boswellic acids, andrographolide, caffeine, royal jelly, estrogen, metformin, and minocycline, have been discussed based on the available preclinical and clinical evidence.

Dietary Flavonoids and Adult Neurogenesis: Potential Implications for Brain Aging

Adult neurogenesis deficiency has been proposed to be a common hallmark in different age-related neurodegenerative diseases. The administration of flavonoids is currently reported as a potentially beneficial strategy for preventing brain aging alterations, including adult neurogenesis decline. Flavonoids are a class of plant-derived dietary polyphenols that have drawn attention for their neuroprotective and pro-cognitive effects. Although they undergo extensive metabolism and localize in the brain at low concentrations, flavonoids are now believed to improve cerebral vasculature and interact with signal transduction cascades involved in the regulation of adult neurogenesis. Furthermore, many dietary flavonoids have been shown to reduce oxidative stress and neuroinflammation, improving the neuronal microenvironment where adult neurogenesis occurs. The overall goal of this review is to summarize the evidence supporting the role of flavonoids in modulating adult neurogenesis as well as to highlight how these dietary agents may be promising candidates in restoring healthy brain function during physiological and pathological aging.

Recent progress of electroactive interface in neural engineering

Neural tissue is an electrical responsible organ. The electricity plays a vital role in the growth and development of nerve tissue, as well as the repairing after diseases. The interface between the nervous system and external device for information transmission is called neural electroactive interface. With the development of new materials and fabrication technologies, more and more new types of neural interfaces are developed and the interfaces can play crucial roles in treating many debilitating diseases such as paralysis, blindness, deafness, epilepsy, and Parkinson's disease. Neural interfaces are developing toward flexibility, miniaturization, biocompatibility, and multifunctionality. This review presents the development of neural electrodes in terms of different materials for constructing electroactive neural interfaces, especially focus on the piezoelectric materials-based indirect neuromodulation due to their features of wireless control, excellent effect, and good biocompatibility. We discussed the challenges we need to consider before the application of these new interfaces in clinical practice. The perspectives about future directions for developing more practical electroactive interface in neural engineering are also discussed in this review. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement.

Role of neurotransmitters in immune-mediated inflammatory disorders: a crosstalk between the nervous and immune systems

Immune-mediated inflammatory diseases (IMIDs) are a group of common heterogeneous disorders, characterized by an alteration of cellular homeostasis. Primarily, it has been shown that the release and diffusion of neurotransmitters from nervous tissue could result in signaling through lymphocyte cell-surface receptors and the modulation of immune function. This finding led to the idea that the neurotransmitters could serve as immunomodulators. It is now manifested that neurotransmitters can also be released from leukocytes and act as autocrine or paracrine modulators. Increasing data indicate that there is a crosstalk between inflammation and alterations in neurotransmission. The primary goal of this review is to demonstrate how these two pathways may converge at the level of the neuron and glia to involve in IMID. We review the role of neurotransmitters in IMID. The different effects that these compounds exert on a variety of immune cells are also reviewed. Current and future developments in understanding the cross-talk between the immune and nervous systems will undoubtedly identify new ways for treating immune-mediated diseases utilizing agonists or antagonists of neurotransmitter receptors.

Role of integrating cannabinoids and the endocannabinoid system in neonatal hypoxic-ischaemic encephalopathy

Neonatal hypoxic-ischaemic events, which can result in long-term neurological impairments or even cell death, are among the most significant causes of brain injury during neurodevelopment. The complexity of neonatal hypoxic-ischaemic pathophysiology and cellular pathways make it difficult to treat brain damage; hence, the development of new neuroprotective medicines is of great interest. Recently, numerous neuroprotective medicines have been developed to treat brain injuries and improve long-term outcomes based on comprehensive knowledge of the mechanisms that underlie neuronal plasticity following hypoxic-ischaemic brain injury. In this context, understanding of the medicinal potential of cannabinoids and the endocannabinoid system has recently increased. The endocannabinoid system plays a vital neuromodulatory role in numerous brain regions, ensuring appropriate control of neuronal activity. Its natural neuroprotection against adult brain injury or acute brain injury also clearly demonstrate the role of endocannabinoid signalling in modulating neuronal activity in the adult brain. The goal of this review is to examine how cannabinoid-derived compounds can be used to treat neonatal hypoxic-ischaemic brain injury and to assess the critical function of the endocannabinoid system and its potential for use as a new neuroprotective treatment for neonatal hypoxic-ischaemic brain injury.

COVID-19-Induced Stroke and the Potential of Using Mesenchymal Stem Cells-Derived Extracellular Vesicles in the Regulation of Neuroinflammation

Ischemic stroke (IS) is a known neurological complication of COVID-19 infection, which is associated with high mortality and disability. Following IS, secondary neuroinflammation that occurs can play both harmful and beneficial roles and lead to further injury or repair of damaged neuronal tissue, respectively. Since inflammation plays a pivotal role in the pathogenesis of COVID-19-induced stroke, targeting neuroinflammation could be an effective strategy for modulating the immune responses following ischemic events. Numerous investigations have indicated that the application of mesenchymal stem cells-derived extracellular vesicles (MSC-EVs) improves functional recovery following stroke, mainly through reducing neuroinflammation as well as promoting neurogenesis and angiogenesis. Therefore, MSC-EVs can be applied for the regulation of SARS-CoV-2-mediated inflammation and the management of COVID-19- related ischemic events. In this study, we have first described the advantages and disadvantages of neuroinflammation in the pathological evolution after IS and summarized the characteristics of neuroinflammation in COVID-19-related stroke. Then, we have discussed the potential benefit of MSC-EVs in the regulation of inflammatory responses after COVID-19-induced ischemic events.

Rabies virus isolated from insectivorous bats induces different inflammatory responses in experimental model

Rabies virus (RABV) is a neurotropic virus that causes fatal neuroinflammation in mammals. The insectivorous bat RABV strains are less pathogenic for mice than strains associated with other reservoirs. We characterized the tissue inflammatory response in the CNS of RABV isolated from insectivorous bats. Eptesicus furinalis (EPBRV)-infected mice had a robust inflammatory response and a greater amount of IL-1β, IL-6 and TNF-α, while Myotis nigricans (MNBRV)-infected mice showed a higher expression of IL-17 and greater activation of IFN-β. New approaches to understand the inflammatory response to different mechanisms of action may provide insights for the development of novel therapies for rabies.

Dual roles of interleukin-33 in cognitive function by regulating central nervous system inflammation

With the advent of an aging society, the incidence of dementia is increasing, resulting in a vast burden on society. It is increasingly acknowledged that neuroinflammation is implicated in various neurological diseases with cognitive dysfunction such as Alzheimer’s disease, multiple sclerosis, ischemic stroke, traumatic brain injury, and central nervous system infections. As an important neuroinflammatory factor, interleukin-33 (IL-33) is highly expressed in various tissues and cells in the mammalian brain, where it plays a role in the pathogenesis of a number of central nervous system conditions. Reams of previous studies have shown that IL-33 has both pro- and anti-inflammatory effects, playing dual roles in the progression of diseases linked to cognitive impairment by regulating the activation and polarization of immune cells, apoptosis, and synaptic plasticity. This article will summarize the current findings on the effects IL-33 exerts on cognitive function by regulating neuroinflammation, and attempt to explore possible therapeutic strategies for cognitive disorders based on the adverse and protective mechanisms of IL-33.

rTMS/iTBS and Cognitive Rehabilitation for Deficits Associated With TBI and PTSD: A Theoretical Framework and Review

Rehabilitation of cognitive and psychosocial deficits resulting from traumatic brain injury (TBI) continues to be an area of concern in health care. Commonly co-occurring psychiatric disorders, such as major depressive disorder and posttraumatic stress disorder, create additional hurdles when attempting to remediate cognitive sequelae. There is increased need for procedures that will yield consistent gains indicative of recovery of function. Intermittent theta-burst stimulation (iTBS), a form of repetitive transcranial magnetic stimulation, has potential as an instrument that can be tailored to aid cognitive processes and support functional gains. The use of iTBS enables direct stimulation of desired neural systems. iTBS, performed in conjunction with behavioral interventions (e.g., cognitive rehabilitation, psychotherapy), may result in additive success in facilitating cognitive restoration and adaptation. The purpose of this theoretical review is to illustrate how the technical and physiological aspects of iTBS may enhance other forms of neurorehabilitation for individuals with TBI. Future research on combinatorial iTBS interventions has the potential to translate to other complex neuropsychiatric conditions.

TNFα-Induced Oxidative Stress and Mitochondrial Dysfunction Alter Hypothalamic Neurogenesis and Promote Appetite Versus Satiety Neuropeptide Expression in Mice

Maternal obesity results in programmed offspring hyperphagia and obesity. The increased offspring food intake is due in part to the preferential differentiation of hypothalamic neuroprogenitor cells (NPCs) to orexigenic (AgRP) vs. anorexigenic (POMC) neurons. The altered neurogenesis may involve hypothalamic bHLH (basic helix–loop–helix) neuroregulatory factors (Hes1, Mash1, and Ngn3). Whilst the underlying mechanism remains unclear, it is known that mitochondrial function is critical for neurogenesis and is impacted by proinflammatory cytokines such as TNFα. Obesity is associated with the activation of inflammation and oxidative stress pathways. In obese pregnancies, increased levels of TNFα are seen in maternal and cord blood, indicating increased fetal exposure. As TNFα influences neurogenesis and mitochondrial function, we tested the effects of TNFα and reactive oxidative species (ROS) hydrogen peroxide (H₂O₂) on hypothalamic NPC cultures from newborn mice. TNFα treatment impaired NPC mitochondrial function, increased ROS production and NPC proliferation, and decreased the protein expression of proneurogenic Mash1/Ngn3. Consistent with this, AgRP protein expression was increased and POMC was decreased. Notably, treatment with H₂O₂ produced similar effects as TNFα and also reduced the protein expression of antioxidant SIRT1. The inhibition of STAT3/NFκB prevented the effects of TNFα, suggesting that TNFα mediates its effects on NPCs via mitochondrial-induced oxidative stress that involves both signaling pathways.

Omentin-1 promoted proliferation and ameliorated inflammation, apoptosis, and degeneration in human nucleus pulposus cells

PURPOSE

Intervertebral disc degeneration is an abnormal, cell-mediated process of tissue remodeling, recognized as the principal cause of low back pain affecting 80% of the population worldwide. Inflammatory cytokine, Interleukin-1beta (IL-1β) is involved in the intervertebral disc degeneration (IDD) process, and it is upregulated in degenerated discs. Omentin-1, also known as intelectin-1, is an adipokine with anti-inflammatory, anti-apoptosis, pro-proliferation, and proangiogenic properties in various types of cells. However, little is known about the effects of omentin-1 on human nucleus pulposus cells (HNPCs). This study aims to investigate the effects of omentin-1 on healthy HNPCs regarding proliferation and further investigate the effects of omentin-1 on IL-1β-induced inflammation, apoptosis, and degeneration in HNPCs.

METHODS

Genes and proteins of interest were measured by qRT-PCR, immunoblotting, and immunofluorescence to conduct related experiments. Cell viability (CCK-8), EdU, and mitochondrial membrane potential (JC-1), flow cytometry assays were used to assess proliferation and apoptosis, respectively.

RESULTS

Our study showed that omentin-1 promoted proliferation in normal HNPCs. Furthermore, omentin-1 expression was decreased in IL-1β-treated HNPCs. Omentin-1 protected against IL-1β-induced inflammation, apoptosis, and degeneration in HNPCs in vitro via the activation of the PI3K/Akt signaling pathway.

CONCLUSION

These findings may contribute to understanding the role of omentin-1 in HNPCs and may be a potential therapeutic candidate for intervertebral disc degeneration.

White-matter free-water diffusion MRI in schizophrenia: a systematic review and meta-analysis

White-matter abnormalities, including increases in extracellular free-water, are implicated in the pathophysiology of schizophrenia. Recent advances in diffusion magnetic resonance imaging (MRI) enable free-water levels to be indexed. However, the brain levels in patients with schizophrenia have not yet been systematically investigated. We aimed to meta-analyse white-matter free-water levels in patients with schizophrenia compared to healthy volunteers. We performed a literature search in EMBASE, MEDLINE, and PsycINFO databases. Diffusion MRI studies reporting free-water in patients with schizophrenia compared to healthy controls were included. We investigated the effect of demographic variables, illness duration, chlorpromazine equivalents of antipsychotic medication, type of scanner, and clinical symptoms severity on free-water measures. Ten studies, including five of first episode of psychosis have investigated free-water levels in schizophrenia, with significantly higher levels reported in whole-brain and specific brain regions (including corona radiata, internal capsule, superior and inferior longitudinal fasciculus, cingulum bundle, and corpus callosum). Six studies, including a total of 614 participants met the inclusion criteria for quantitative analysis. Whole-brain free-water levels were significantly higher in patients relative to healthy volunteers (Hedge's g = 0.38, 95% confidence interval (CI) 0.07-0.69, p = 0.02). Sex moderated this effect, such that smaller effects were seen in samples with more females (z = -2.54, p < 0.05), but antipsychotic dose, illness duration and symptom severity did not. Patients with schizophrenia have increased free-water compared to healthy volunteers. Future studies are necessary to determine the pathological sources of increased free-water, and its relationship with illness duration and severity.

Targeting C–C Chemokine Receptor 5: Key to Opening the Neurorehabilitation Window After Ischemic Stroke

Stroke is the world’s second major cause of adult death and disability, resulting in the destruction of brain tissue and long-term neurological impairment; induction of neuronal plasticity can promote recovery after stroke. C–C chemokine receptor 5 (CCR5) can direct leukocyte migration and localization and is a co-receptor that can mediate human immunodeficiency virus (HIV) entry into cells. Its role in HIV infection and immune response has been extensively studied. Furthermore, CCR5 is widely expressed in the central nervous system (CNS), is engaged in various physiological activities such as brain development, neuronal differentiation, communication, survival, and learning and memory capabilities, and is also involved in the development of numerous neurological diseases. CCR5 is differentially upregulated in neurons after stroke, and the inhibition of CCR5 in specific regions of the brain promotes motor and cognitive recovery. The mechanism by which CCR5 acts as a therapeutic target to promote neurorehabilitation after stroke has rarely been systematically reported yet. Thus, this review aims to discuss the function of CCR5 in the CNS and the mechanism of its effect on post-stroke recovery by regulating neuroplasticity and the inflammatory response to provide an effective basis for clinical rehabilitation after stroke.

SARS-CoV-2 Attacks in the Brain: Focus on the Sialome

The epidemiological observations suggest that respiratory and gastrointestinal symptoms caused by severe acute respiratory coronavirus 2 (SARS-CoV-2) are accompanied by short- and long-term neurological manifestations. There is increasing evidence that the neuroinvasive potential of SARS-CoV-2 is closely related to its capacity to interact with cell membrane sialome. Given the wide expression of sialylated compounds of cell membranes in the brain, the interplay between cell membrane sialoglycans and the virus is crucial for its attachment and cell entry, transport, neuronal damage and brain immunity. Here, we focus on the significance of the brain sialome in the progress of coronavirus disease 2019 (COVID-19) and SARS-CoV-2-induced neuropathology.

Isoflurane and Sevoflurane Induce Cognitive Impairment in Neonatal Rats by Inhibiting Neural Stem Cell Development Through Microglial Activation, Neuroinflammation, and Suppression of VEGFR2 Signaling Pathway

Inhaled anesthetics are known to induce neurotoxicity in the developing brains of rodents, although the mechanisms are not well understood. The aim of this study was to elucidate the molecular mechanisms underlying anesthetics-induced neurodevelopmental toxicity by VEGF receptor 2 (VEGFR2) through the interaction between microglia and neural stem cells (NSCs) in postnatal day 7 (P7) rats. Cognitive function of P7 rats exposed to isoflurane and sevoflurane were assessed using Morris Water Maze and T maze tests. We also evaluated the expression levels of NSC biomarkers (Nestin and Sox2), microglia biomarker (CD11b or or IBA1), pro-inflammatory cytokines (IL-6 and TNF-α), and VEGFR2 using western blotting and immunohistochemistry in the brains of control and anesthesia-treated rats. We found spatial learning and working memory was impaired 2 weeks after anesthetics exposure in rats. Isoflurane induced stronger and more prolonged neurotoxicity than sevoflurane. However, cognitive functions were recovered 6 weeks after anesthesia. Isoflurane and sevoflurane decreased the levels of Nestin, Sox2, and p-VEGFR2, activated microglia, decreased the number of NSCs and reduced neurogenesis and the proliferation of NSCs, and increased the levels of IL-6, TNF-α, and CD11b. Our results suggested that isoflurane and sevoflurane induced cognitive impairment in rats by inhibiting NSC development and neurogenesis via microglial activation, neuroinflammation, and suppression of VEGFR2 signaling pathway.

Supplemental or dietary intake of omega-3 fatty acids for the treatment of periodontitis: A meta-analysis

AIM

To evaluate the intervention effect of omega-3 fatty acids on changes in periodontal parameters.

MATERIALS AND METHODS

This meta-analysis included studies published in English language between 2010 and 2020, which were extracted from the Cochrane Library, EMBASE, and PubMed databases. The effects of omega-3 fatty acid intervention were investigated using the amount of omega-3 intake, periodontal pocket depth (PPD), clinical attachment loss (CAL), and bleeding on probing (BOP). The random-effects model was generated for data analysis. To obtain robustness of the model, sensitivity analysis was implemented. Subgroup analyses were performed based on the intervention period for each parameter.

RESULTS

All 13 studies included in the meta-analysis were interventional, randomized controlled trials. Two studies implemented omega-3 fatty acid-rich diets, while 11 studies used supplements. Risk of bias was low, and publication bias was not shown. Meta-analysis showed a statistically significant PPD reduction (standardized mean difference [SMD] = -0.81, absolute mean difference [MD] = -0.44 mm), CAL gain (SMD = -0.77, MD = -0.51 mm), and BOP reduction (SMD = -0.65, MD = -9.45%) for the omega-3 fatty acid intervention overall.

CONCLUSION

This study suggests that supplemental or dietary intake of omega-3 fatty acids for the treatment of periodontitis may have a positive impact on the disease.

Switching Roles: Beneficial Effects of Adipose Tissue-Derived Mesenchymal Stem Cells on Microglia and Their Implication in Neurodegenerative Diseases

Neurological disorders, including neurodegenerative diseases, are often characterized by neuroinflammation, which is largely driven by microglia, the resident immune cells of the central nervous system (CNS). Under these conditions, microglia are able to secrete neurotoxic substances, provoking neuronal cell death. However, microglia in the healthy brain carry out CNS-supporting functions. This is due to the ability of microglia to acquire different phenotypes that can play a neuroprotective role under physiological conditions or a pro-inflammatory, damaging one during disease. Therefore, therapeutic strategies focus on the downregulation of these neuroinflammatory processes and try to re-activate the neuroprotective features of microglia. Mesenchymal stem cells (MSC) of different origins have been shown to exert such effects, due to their immunomodulatory properties. In recent years, MSC derived from adipose tissue have been made the center of attention because of their easy availability and extraction methods. These cells induce a neuroprotective phenotype in microglia and downregulate neuroinflammation, resulting in an improvement of clinical symptoms in a variety of animal models for neurological pathologies, e.g., Alzheimer’s disease, traumatic brain injury and ischemic stroke. In this review, we will discuss the application of adipose tissue-derived MSC and their conditioned medium, including extracellular vesicles, in neurological disorders, their beneficial effect on microglia and the signaling pathways involved.

PTP70-2, a novel polysaccharide from Polygala tenuifolia, prevents neuroinflammation and protects neurons by suppressing the TLR4-mediated MyD88/NF-κB signaling pathway

PTP70-2, a novel polysaccharide isolated from Polygala tenuifolia in our previous publication, exhibits potential anti-inflammatory effects. Here, we investigate the mechanisms underlying these effects and the neuroprotective activity of PTP70-2 in lipopolysaccharide (LPS)-damaged BV2 microglial cells and neuroinflammation-injured primary cortical neurons. The results suggest that PTP70-2 dramatically reduces the LPS-stimulated inflammatory cytokines overexpression, as well as down-regulates the levels of TLR4-, MyD88-, and NF-κB-related proteins. The effect of PTP70-2 in down-regulation of proinflammatory cytokines and downstream proteins implicated in MyD88 and NF-κB signaling is related to the TLR4 pathway. Furthermore, this effect is enhanced by the co-incubation of BV2 cells with PTP70-2 and TAK242, a TLR4 inhibitor, before exposure to LPS. Importantly, PTP70-2 prevents neuroinflammation-induced neurotoxicity by mitigating ROS overproduction and MMP dissipation. Overall, the PTP70-2's anti-neuroinflammation and neuroprotection are involved to the modulation of the TLR4-mediated MyD88/NF-κB signaling pathway.

Inflammatory and neurodegenerative pathophysiology implicated in postpartum depression

Postpartum depression (PPD) is the most common psychiatric complication associated with pregnancy and childbirth with debilitating symptoms that negatively impact the quality of life of the mother as well as inflict potentially long-lasting developmental impairments to the child. Much of the theoretical pathophysiology put forth to explain the emergence of PPD overlaps with that of major depressive disorder (MDD) and, although not conventionally described in such terms, can be seen as neurodegenerative in nature. Framing the disorder from the perspective of the well-established inflammatory theory of depression, symptoms are thought to be driven by dysregulation, and subsequent hyperactivation of the body's immune response to stress. Compounded by physiological stressors such as drastic fluctuations in hormone signaling, physical and psychosocial stressors placed upon new mothers lay bare a number of significant vulnerabilities, or points of potential failure, in systems critical for maintaining healthy brain function. The inability to compensate or properly adapt to meet the changing demands placed upon these systems has the potential to damage neurons, hinder neuronal growth and repair, and disrupt neuronal circuit integrity such that essential functional outputs like mood and cognition are altered. The impact of this deterioration in brain function, which includes depressive symptoms, extends to the child who relies on the mother for critical life-sustaining care as well as important cognitive stimulation, accentuating the need for further research.

Effect of combination therapy with neural stem cell transplantation and teramethylpyrazine in rats following acute spinal cord injury

OBJECTIVES

This study was to explore the effects of teramethylpyrazine (TMP) administered in conjunction with neural stem cell transplantation on motor function, pathological lesions and the Janus kinase (JAK)2/signal transducer and activator of transcription 3 signal transduction pathway in rats following acute spinal cord injury (SCI).

METHODS

Female Sprague-Dawley rats were randomly divided into sham, model, neural stem cells (NSCs) and NSCs+TMP groups. Motor function was evaluated using the Basso, Beattie, Bresnahan scale. Spinal cord neuropathies and neuron apoptosis were observed by HE and TUNEL staining. The brain-derived neurotrophic factor (BDNF), Nogo-A, JAK2 and p-JAK2 protein levels were measured by western blot analysis.

RESULTS

NSCs+TMP significantly improved rat motor function, attenuated impaired spinal cords, and decreased cellular apoptosis, compared with NSCs therapy alone (P < 0.05). In addition, expression of BDNF protein was significantly higher in NSCs+TMP rats compared with other groups regardless of time postinjury (P < 0.05). The highest expression levels of Nogo-A protein were observed in the model group. The expression of p-JAK2 in the NSCs+TMP group was relatively lower than the model and NSCs groups (P < 0.05).

CONCLUSIONS

In rats with SCI, NSCs+TMP effectively improved motor function and offered spinal cord protection by increasing BDNF and decreasing Nogo-A levels, as well as inhibiting the JAK2/STAT3 signal transduction pathway, suggesting that TMP could be a useful agent in NSCs transplantation in the treatment of SCI.

T lymphocytes as critical mediators in tissue regeneration, fibrosis, and the foreign body response

Research on the foreign body response (FBR) to biomaterial implants has been focused on the roles that the innate immune system has on mediating tolerance or rejection of implants. However, the immune system also involves the adaptive immune response and it must be included in order to form a complete picture of the response to biomaterials and medical implants. In this review, we explore recent understanding about the roles of adaptive immune cells, specifically T cells, in modulating the immune response to biomaterial implants. The immune response to implants elicits a delicate balance between tissue repair and fibrosis that is mainly regulated by three types of T helper cell responses -T helper type 1, T helper type 2, and T helper type 17- and their crosstalk with innate immune cells. Interestingly, many T cell response mechanisms to implants overlap with the process of fibrosis or repair in different tissues. This review explores the fibrotic and regenerative T cell biology and draws parallels to T cell responses to biomaterials. Additionally, we also explore the biomedical engineering advancements in biomaterial applications in designing particle and scaffold systems to modulate T cell activity for therapeutics and devices. Not only do the deliberate engineering design of physical and chemical material properties and the direct genetic modulation of T cells not only offer insights to T cell biology, but they also present different platforms to develop immunomodulatory biomaterials. Thus, an in-depth understanding of T cells' roles can help to navigate the biomaterial-immune interactions and reconsider the long-lasting adaptive immune response to implants, which, in the end, contribute to the design of immunomodulatory medical implants that can advance the next generation of regenerative therapy. STATEMENT OF SIGNIFICANCE: This review article integrates knowledge of adaptive immune responses in tissue damage, wound healing, and medical device implantation. These three fields, often not discussed in conjunction, are important to consider when evaluating and designing biomaterials. Through incorporation of basic biological research alongside engineering research, we provide an important lens through which to evaluate adaptive immune contributions to regenerative medicine and medical device development.

The Nordic prudent diet prolongs survival with good mental and physical functioning among older adults: The role of healthy lifestyle

BACKGROUND & AIMS

Healthy diet has been associated with decreased mortality, but its impact on survival without disability is less clear. We aimed to investigate the association between the Nordic Prudent Diet Pattern (NPDP) and dementia- and disability-free survival, and to assess its interaction with other healthy lifestyle behaviors.

METHODS

Within the Swedish National Study on Aging and Care-Kungsholmen, 2290 dementia- and disability-free adults aged ≥60 were followed up to 12 years to detect survival free from dementia (standard criteria) and disability (Katz's Activities of Daily Living). NPDP index was assessed at baseline with a 98-item food frequency questionnaire (characterized mainly by more frequent intakes of vegetable, fruit, cooking, cereals, whole grains, fish, and water) and was further categorized into tertiles (low, moderate, or high). Information on lifestyle factors was collected via baseline questionnaire. A favorable (vs unfavorable) lifestyle profile was determined based on smoking status, social network and physical activity. Data were analyzed using Cox proportional hazard regression models and Laplace regression.

RESULTS

During the follow-up, 1074 participants survived without dementia and disability (614 died, 518 became disabled, and 84 developed dementia). Compared to low NPDP adherence, the hazard ratio (HR) of high NPDP adherence was 1.19 (95% CI 1.04-1.34) for dementia- and disability-free survival. High NPDP adherence prolonged lifespan without mental and physical disability by an average of 1.24 years (95% CI 0.11-2.37). Further, among participants with high NPDP adherence, a favorable lifestyle profile was associated with an even higher HR (1.96, 95% CI 1.52-2.42) of dementia- and disability-free survival, corresponding to an average of 3.80 (95% CI 2.25-5.35) years longer life compared to those with low NPDP adherence and an unfavorable lifestyle profile.

CONCLUSION

High adherence to NPDP prolongs survival with good mental and physical function for more than one year, and this could increase to almost four years with a favorable lifestyle.

Neurogenesis after Spinal Cord Injury: State of the Art

Neurogenesis in the adult state is the process of new neuron formation. This relatively infrequent phenomenon comprises four stages: cell proliferation, cell migration, differentiation, and the integration of these cells into an existing circuit. Recent reports suggest that neurogenesis can be found in different regions of the Central Nervous System (CNS), including the spinal cord (SC). This process can be observed in physiological settings; however, it is more evident in pathological conditions. After spinal cord injury (SCI), the activation of microglial cells and certain cytokines have shown to exert different modulatory effects depending on the presence of inflammation and on the specific region of the injury site. In these conditions, microglial cells and cytokines are considered to play an important role in the regulation of neurogenesis after SCI. The purpose of this article is to present an overview on neural progenitor cells and neurogenic and non-neurogenic zones as well as the cellular and molecular regulation of neurogenesis. Additionally, we will briefly describe the recent advances in the knowledge of neurogenesis after SCI.

Deficiency of Endothelial Nitric Oxide Synthase (eNOS) Exacerbates Brain Damage and Cognitive Deficit in A Mouse Model of Vascular Dementia

Vascular Dementia (VaD) accounts for nearly 20% of all cases of dementia. eNOS plays an important role in neurovascular remodeling, anti-inflammation, and cognitive functional recovery after stroke. In this study, we investigated whether eNOS regulates brain damage, cognitive function in mouse model of bilateral common carotid artery stenosis (BCAS) induced VaD. Late-adult (6-8 months) C57BL/6J and eNOS knockout (eNOS-/-) mice were subjected to BCAS (n=12/group) or sham group (n=8/group). BCAS was performed by applying microcoils to both common carotid arteries. Cerebral blood flow (CBF) and blood pressure were measured. A battery of cognitive functional tests was performed, and mice were sacrificed 30 days after BCAS. Compared to corresponding sham mice, BCAS in wild-type (WT) and eNOS-/- mice significantly: 1) induces short term, long term memory loss, spatial learning and memory deficits; 2) decreases CBF, increases ischemic cell damage, including apoptosis, white matter (WM) and axonal damage; 3) increases blood brain barrier (BBB) leakage, decreases aquaporin-4 (AQP4) expression and vessel density; 4) increases microglial, astrocyte activation and oxidative stress in the brain; 5) increases inflammatory factor interleukin-1 receptor-associated kinase-1(IRAK-1) and amyloid beta (Aβ) expression in brain; 6) increases IL-6 and IRAK4 expression in brain. eNOS-/-sham mice exhibit increased blood pressure, decreased iNOS and nNOS in brain compared to WT-sham mice. Compared to WT-BCAS mice, eNOS-/-BCAS mice exhibit worse vascular and WM/axonal damage, increased BBB leakage and inflammatory response, increased cognitive deficit, decreased iNOS, nNOS in brain. eNOS deficit exacerbates BCAS induced brain damage and cognitive deficit.

Hydrogen Alleviates Neuronal Injury and Neuroinflammation Induced by Microglial Activation via the Nuclear Factor Erythroid 2-related Factor 2 Pathway in Sepsis-associated Encephalopathy

Sepsis-associated encephalopathy (SAE) is characterized by diffuse cerebral and central nervous system (CNS) dysfunction. Microglia play a vital role in protecting the brain from neuronal damage, which is closely related to inflammatory responses. The nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway has an impact on microglial and neuronal injury. Here, we mainly explored the molecular mechanism by which Hydrogen (H₂) regulates neuroinflammation in SAE and the role of Nrf2 in this process. An in vivo model of SAE was generated by cecal ligation and puncture (CLP). Primary microglia and neurons were cultured to establish an in vitro model. Microglia, neurons and brain tissue were obtained to detect Nrf2 expression, inflammation, cell injury, apoptosis, and microglial polarization. Escape latency, the number of platform crossings and the time spent in the target quadrant were measured to assess cognitive function. H₂ attenuated microglial polarization from the M1 to the M2 phenotype, cytokine release and TLR/NF-κb activation and protected neurons from lipopolysaccharide (LPS)-activated microglia-induced injury via the Nrf2 pathway. SAE activated Nrf2 expression, and H₂ further improved Nrf2 expression in SAE mice. H₂ alleviated microglial polarization from the M1 to the M2 phenotype and cytokine release in the cerebral cortex and improved neuronal injury or cognitive dysfunction in SAE mice and wild-type mice but not in Nrf2-/- mice. H₂ exerts antineuroinflammatory effects associated with TLR4/NF-κB signaling activation and neuroprotective effects by inhibiting the excessive release of proinflammatory cytokines, neuronal loss and apoptosis in vitro and in vivo through the Nrf2 pathway.

Oxolipidomics profile in major depressive disorder: Comparing remitters and non-remitters to repetitive transcranial magnetic stimulation treatment

BACKGROUND

Repetitive Transcranial Magnetic Stimulation [rTMS] is increasingly being used to treat Major Depressive Disorder [MDD]. Given that not all patients respond to rTMS, it would be clinically useful to have reliable biomarkers that predict treatment response. Oxidized phosphatidylcholine [OxPC] and some oxylipins are important plasma biomarkers of oxidative stress and inflammation. Not only is depression associated with oxidative stress, but rTMS has been shown to have anti-oxidative effects.

OBJECTIVES

To investigate whether plasma oxolipidomics profiles could predict treatment response in patients with treatment resistant MDD.

METHODS

Fourty-eight patients undergoing rTMS treatment for MDD were recruited along with nine healthy control subjects. Plasma OxPCs and oxylipins were extracted and analyzed through high performance liquid chromatography coupled with mass spectrometry. Patients with a Hamilton Depression Rating Scale score [Ham-D] ≤7 post-treatment were defined as having entered remission.

RESULTS

Fifty-seven OxPC and 32 oxylipin species were identified in our subjects. MDD patients who entered remission following rTMS had significantly higher pre-rTMS levels of total and fragmented OxPCs compared to non-remitters and controls [one-way ANOVA, p<0.05]. However, no significant changes in OxPC levels were found as a result of rTMS, regardless of treatment response [p>0.05]. No differences in plasma oxylipins were found between remitters and non-remitters at baseline.

CONCLUSION

Certain categories of OxPCs may be useful predictive biomarkers for response to rTMS treatment in MDD. Given that elevated oxidized lipids may indicate higher levels of oxidative stress and inflammation in the brain, patients with this phenotype of depression may be more receptive to rTMS treatment.

Effects of Platelet-Rich Plasma on Cellular Populations of the Central Nervous System: The Influence of Donor Age

Platelet-rich plasma (PRP) is a biologic therapy that promotes healing responses across multiple medical fields, including the central nervous system (CNS). The efficacy of this therapy depends on several factors such as the donor's health status and age. This work aims to prove the effect of PRP on cellular models of the CNS, considering the differences between PRP from young and elderly donors. Two different PRP pools were prepared from donors 65‒85 and 20‒25 years old. The cellular and molecular composition of both PRPs were analyzed. Subsequently, the cellular response was evaluated in CNS in vitro models, studying proliferation, neurogenesis, synaptogenesis, and inflammation. While no differences in the cellular composition of PRPs were found, the molecular composition of the Young PRP showed lower levels of inflammatory molecules such as CCL-11, as well as the presence of other factors not found in Aged PRP (GDF-11). Although both PRPs had effects in terms of reducing neural progenitor cell apoptosis, stabilizing neuronal synapses, and decreasing inflammation in the microglia, the effect of the Young PRP was more pronounced. In conclusion, the molecular composition of the PRP, conditioned by the age of the donors, affects the magnitude of the biological response.

Traumatic brain injury-induced cerebral microbleeds in the elderly

Traumatic brain injury (TBI) was shown to lead to the development of cerebral microbleeds (CMBs), which are associated with long term cognitive decline and gait disturbances in patients. The elderly is one of the most vulnerable parts of the population to suffer TBI. Importantly, ageing is known to exacerbate microvascular fragility and to promote the formation of CMBs. In this overview, the effect of ageing is discussed on the development and characteristics of TBI-related CMBs, with special emphasis on CMBs associated with mild TBI. Four cases of TBI-related CMBs are described to illustrate the concept that ageing exacerbates the deleterious microvascular effects of TBI and that similar brain trauma may induce more CMBs in old patients than in young ones. Recommendations are made for future prospective studies to establish the mechanistic effects of ageing on the formation of CMBs after TBI, and to determine long-term consequences of CMBs on clinically relevant outcome measures including cognitive performance, gait and balance function.

Cerebrospinal fluid biomarkers of neuroinflammation in children with hydrocephalus and shunt malfunction

BACKGROUND

Approximately 30% of cerebrospinal fluid (CSF) shunt systems for hydrocephalus fail within the first year and 98% of all patients will have shunt failure in their lifetime. Obstruction remains the most common reason for shunt failure. Previous evidence suggests elevated pro-inflammatory cytokines in CSF are associated with worsening clinical outcomes in neuroinflammatory diseases. The aim of this study was to determine whether cytokines and matrix metalloproteinases (MMPs) contribute towards shunt failure in hydrocephalus.

METHODS

Using multiplex ELISA, this study examined shunt failure through the CSF protein concentration profiles of select pro-inflammatory and anti-inflammatory cytokines, as well as select MMPs. Interdependencies such as the past number of previous revisions, length of time implanted, patient age, and obstruction or non-obstruction revision were examined. The pro-inflammatory cytokines were IL-1β, IL-2, IL-5, IL-6, IL-8, IL-12, IL-17, TNF-α, GM-CSF, IFN-γ. The anti-inflammatory cytokines were IL-4 and IL-10, and the MMPs were MMP-2, MMP-3, MMP-7, MMP-9. Protein concentration is reported as pg/mL for each analyte.

RESULTS

Patient CSF was obtained at the time of shunt revision operation; all pediatric (< 18), totaling n = 38. IL-10, IL-6, IL-8 and MMP-7 demonstrated significantly increased concentrations in patient CSF for the non-obstructed subgroup. Etiological examination revealed IL-6 was increased in both obstructed and non-obstructed cases for PHH and congenital hydrocephalic patients, while IL-8 was higher only in PHH patients. In terms of number of past revisions, IL-10, IL-6, IL-8, MMP-7 and MMP-9 progressively increased from zero to two past revisions and then remained low for subsequent revisions. This presentation was notably absent in the obstruction subgroup. Shunts implanted for three months or less showed significantly increased concentrations of IL-6, IL-8, and MMP-7 in the obstruction subgroup. Lastly, only patients aged six months or less presented with significantly increased concentration of IL-8 and MMP-7.

CONCLUSION

Non-obstructive cases are reported here to accompany significantly higher CSF cytokine and MMP protein levels compared to obstructive cases for IL-10, IL-6, IL-8, MMP-7 and MMP-9. A closer examination of the definition of obstruction and the role neuroinflammation plays in creating shunt obstruction in hydrocephalic patients is suggested.

Polydatin inhibits LPS-induced inflammatory response in BV2 microglia by disrupting the formation of lipid rafts

OBJECTIVE

Polydatin has been used in the treatment of various inflammatory diseases. However, its role in the regulation of neuroinflammation has not been reported. In this study, we designed to investigate the anti-inflammatory effects of polydatin in LPS-stimulated BV2 microglia cells.

METHODS

Inflammatory mediators TNF-α, IL-1β, NO, and PGE2 production were measured by ELISA. The protein of signaling pathways were detected by western blot analysis.

RESULTS

The results showed that polydatin significantly ameliorated the production of TNF-α, IL-1β, NO, and PGE2 up-regulated by LPS. Polydatin also blocked LPS-induced NF-κB activation. In addition, PI3K and AKT, the up-stream molecules of NF-κB signaling pathway, were inhibited by the treatment of polydatin. Also, we found the formation of lipid rafts was inhibited by polydatin through attenuating the cholesterol content. Finally, polydatin was found to increase the expression of ABCA1 and ABCG1.

CONCLUSION

In conclusion, the results of the present study suggested that polydatin exhibited its anti-inflammatory effects in BV2 cells through disrupting lipid rafts, which subsequently inhibiting PI3K/AKT signaling pathway.

Regionally Specific Human Pre-Oligodendrocyte Progenitor Cells Produce Both Oligodendrocytes and Neurons after Transplantation in a Chronically Injured Spinal Cord Rat Model after Glial Scar Ablation

Chronic spinal cord injury (SCI) is a devastating medical condition. In the acute phase after injury, there is cell loss resulting in chronic axonal damage and loss of sensory and motor function including loss of oligodendrocytes that results in demyelination of axons and further dysfunction. In the chronic phase, the inhibitory environment within the lesion including the glial scar can arrest axonal growth and regeneration and can also potentially affect transplanted cells. We hypothesized that glial scar ablation (GSA) along with cell transplantation may be required as a combinatorial therapy to achieve functional recovery, and therefore we proposed to examine the survival and fate of human induced pluripotent stem cell (iPSC) derived pre-oligodendrocyte progenitor cells (pre-OPCs) transplanted in a model of chronic SCI, whether this was affected by GSA, and whether this combination of treatments would result in functional recovery. In this study, chronically injured athymic nude (ATN) rats were allocated to one of three treatment groups: GSA only, pre-OPCs only, or GSA+pre-OPCs. We found that human iPSC derived pre-OPCs were multi-potent and retained the ability to differentiate into mainly oligodendrocytes or neurons when transplanted into the chronically injured spinal cords of rats. Twelve weeks after cell transplantation, we observed that more of the transplanted cells differentiated into oligodendrocytes when the glial scar was ablated compared with no GSA. Further, we also observed that a higher percentage of transplanted cells differentiated into V2a interneurons and motor neurons in the pre-OPCs only group when compared with GSA+pre-OPCs. This suggests that the local environment created by ablation of the glial scar may have a significant effect on the fate of cells transplanted into the injury site.

Peripheral Inflammatory Biomarkers of Methamphetamine Withdrawal Patients Based on the Neuro-Inflammation Hypothesis: The Possible Improvement Effect of Exercise

Methamphetamine (MA) induced addiction and neuroinflammation has been implicated. Based on the neuroinflammation hypothesis, this study aims to investigate how exercise influences the craving of patients in MA withdrawal, and explore the mechanism of peripheral inflammation. A total of 90 patients in MA withdrawal were recruited. No difference was noted in the number of years of drug use and the frequency of drug use among patients, and the withdrawal time was within 2 months. The subjects were grouped based on the degree of craving induced by the cues: non-craving control group (NCC group), craving control group (CC group), and craving exercise group (CE group). The CE group was subjected to aerobic combined resistance training. Then, the ELISA method was used to detect plasma IL-6, TNF-α, and IL-1β concentrations; Visual Analog Scale (VAS) measurement of cue-induced cravings under Virtual Reality (VR) exposure (VR-VAS) and the Desires for Drug Questionnaire (DDQ) were used to assess cravings. Consequently, plasma IL-6, TNF-α, IL-1β, levels, and the VR-VAS and DDQ scores of MA withdrawal patients were significantly reduced after exercise. This study confirmed that 8 weeks of incremental load aerobic combined with resistance training reduces peripheral inflammation and significantly reduces the level of craving for MA.

A novel polysaccharide from Acorus tatarinowii protects against LPS-induced neuroinflammation and neurotoxicity by inhibiting TLR4-mediated MyD88/NF-κB and PI3K/Akt signaling pathways

Our previous study has indicated that a crude polysaccharide derived from Acorus tatarinowii, AT50, remarkably improves learning and memory in scopolamine-induced amnesic mice and prevents the release of inflammatory mediators. To further explore the bioactive constituents of AT50, a novel polysaccharide (ATP50-3) was purified, and its anti-neuroinflammatory effects and underlying mechanisms were investigated. ATP50-3 significantly reduced abnormal elevation of inflammatory mediators in lipopolysaccharide (LPS)-induced proinflammatory BV2 cells in vitro and inhibited the activation of nuclear factor kappa B (NF-κB). Moreover, ATP50-3 down-regulated LPS-induced protein levels of Toll-like receptor 4 (TLR4), myeloid differentiation primary response protein (MyD88), p-PI3K (phosphoinositide 3-kinase), and p-Akt (protein kinase B). Further experiments demonstrated that TAK242 (a TLR4 inhibitor) and LY294002 (a PI3K inhibitor) remarkably augmented ATP50-3's down-regulation on LPS-induced proinflammatory mediators. Importantly, ATP50-3 provided neuroprotection against neuroinflammation-induced neurotoxicity in primary cortical and hippocampal neurons by mitigating overproduction of reactive oxygen species and damage to the mitochondrial membrane potential (MMP). Taken together, our findings suggest that ATP50-3 exerts anti-neuroinflammatory and neuroprotective effects through modulation of TLR4-mediated MyD88/NF-κB and PI3K/Akt signaling pathways.

Enduring neuroimmunological consequences of developmental experiences: From vulnerability to resilience

The immune system is crucial for normal neuronal development and function (neuroimmune system). Both immune and neuronal systems undergo significant postnatal development and are sensitive to developmental programming by environmental experiences. Negative experiences from infection to psychological stress at a range of different time points (in utero to adolescence) can permanently alter the function of the neuroimmune system: given its prominent role in normal brain development and function this dysregulation may increase vulnerability to psychiatric illness. In contrast, positive experiences such as exercise and environmental enrichment are protective and can promote resilience, even restoring the detrimental effects of negative experiences on the neuroimmune system. This suggests the neuroimmune system is a viable therapeutic target for treatment and prevention of psychiatric illnesses, especially those related to stress. In this review we will summarise the main cells, molecules and functions of the immune system in general and with specific reference to central nervous system development and function. We will then discuss the effects of negative and positive environmental experiences, especially during development, in programming the long-term functioning of the neuroimmune system. Finally, we will review the sparse but growing literature on sex differences in neuroimmune development and response to environmental experiences.

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The immune system is essential for development and function of the central nervous system (neuroimmune system)

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Environmental experiences can permanently alter neuroimmune function and associated brain development

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Altered neuroimmune function following negative developmental experiences may play a role in psychiatric illnesses

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Positive experiences can promote resilience and rescue the effects of negative experiences on the neuroimmune system

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The neuroimmune system is therefore a viable therapeutic target for preventing and treating psychiatric illnesses