Neuron-specific effects of interleukin-1β are mediated by a novel isoform of the IL-1 receptor accessory protein

Neuroimmune regulation of the prefrontal cortex tetrapartite synapse

The prefrontal cortex (PFC) is an essential driver of cognitive, affective, and motivational behavior. There is clear evidence that the neuroimmune system directly influences PFC synapses, in addition to its role as the first line of defense against toxins and pathogens. In this review, we first describe the core structures that form the tetrapartite PFC synapse, focusing on the signaling microdomain created by astrocytic cradling of the synapse as well as the emerging role of the extracellular matrix in synaptic organization and plasticity. Neuroimmune signals (e.g. pro-inflammatory interleukin 1β) can impact the function of each core structure within the tetrapartite synapse, as well as promote intra-synaptic crosstalk, and we will provide an overview of recent advances in this field. Finally, evidence from post mortem human brain tissue and preclinical studies indicate that inflammation may be a key contributor to PFC dysfunction. Therefore, we conclude with a mechanistic discussion of neuroimmune-mediated maladaptive plasticity in neuropsychiatric disorders, with a focus on alcohol use disorder (AUD). Growing recognition of the neuroimmune system's role as a critical regulator of the PFC tetrapartite synapse provides strong support for targeting the neuroimmune system to develop new pharmacotherapeutics.

Alternatively spliced mini-exon B in PTPδ regulates excitatory synapses through cell-type-specific trans-synaptic PTPδ-IL1RAP interaction

PTPδ, encoded by PTPRD, is implicated in various neurological, psychiatric, and neurodevelopmental disorders, but the underlying mechanisms remain unclear. PTPδ trans-synaptically interacts with multiple postsynaptic adhesion molecules, which involves its extracellular alternatively spliced mini-exons, meA and meB. While PTPδ-meA functions have been studied in vivo, PTPδ-meB has not been studied. Here, we report that, unlike homozygous PTPδ-meA-mutant mice, homozygous PTPδ-meB-mutant (Ptprd-meB-/-) mice show markedly reduced early postnatal survival. Heterozygous Ptprd-meB+/- male mice show behavioral abnormalities and decreased excitatory synaptic density and transmission in dentate gyrus granule cells (DG-GCs). Proteomic analyses identify decreased postsynaptic density levels of IL1RAP, a known trans-synaptic partner of meB-containing PTPδ. Accordingly, IL1RAP-mutant mice show decreased excitatory synaptic transmission in DG-GCs. Ptprd-meB+/- DG interneurons with minimal IL1RAP expression show increased excitatory synaptic density and transmission. Therefore, PTPδ-meB is important for survival, synaptic, and behavioral phenotypes and regulates excitatory synapses in cell-type-specific and IL1RAP-dependent manners.

The functional role of locus coeruleus microglia in the female stress response

Neuropsychiatric disorders that result from stress exposure are highly associated with central inflammation. Our previous work established that females selectively exhibit heightened proinflammatory cytokine production within the noradrenergic locus coeruleus (LC) along with a hypervigilant behavioral phenotype in response to witnessing social stress. Notably, ablation of microglia using pharmacological techniques prevents this behavioral response. These studies were designed to further investigate the impact of stress-induced neuroimmune signaling on the long-term behavioral and neuronal consequences of social stress exposure in females using chemogenetics. We first characterized the use of an AAV-CD68-Gi-DREADD virus targeted to microglia within the LC and confirmed viral transduction, selectivity, and efficacy. Clozapine-n-oxide (CNO) was used for the suppression of microglial reactivity during acute and chronic exposure to vicarious/witness social defeat in female rats. Chemogenetic-mediated inhibition of microglial reactivity during stress blunted the neuroimmune response to stress and prevented both acute and long-term hypervigilant behavioral responses. Further, a history of microglial suppression during stress prevented the heightened LC activity typically observed in response to stress cues. These studies are among the first to use a chemogenetic approach to inhibit central microglia in vivo and establish LC microglia as a key driver of the behavioral and neuronal responses to social stress in females.

Sleep loss-induced oncogenic pathways are mediated via the neuron-specific interleukin-1 receptor accessory protein (AcPb)

Interleukin-1β (IL1), a pleiotropic cytokine, is involved in sleep regulation, tumor ontogeny, and immune responses. IL1 receptor adaptor proteins, including the IL1 receptor accessory protein (AcP), and its neuron-specific isoform, AcPb, are required for IL1 signaling. The AcPb isoform is resultant from alternate splicing of the AcP transcript. Our previous studies using AcPb null (AcPb-/-) mice characterized its participation in sleep regulation and emergent neuronal/glial network properties. Here, we investigated the impact of acute sleep disruption (SD) on brain cancer-related pathways in wild-type (WT) and AcPb-/- mice, employing RNA sequencing methods. In WT mice, SD increased AcPb mRNA levels, but not AcP mRNA, confirming prior similar work in rats. Transcriptome and pathway enrichment analyses demonstrated significant alterations in cancer, immune, and viral disease-related pathways in WT mice after SD, which were attenuated in AcPb-/- mice including multiple upregulated Src phosphorylation-signaling-dependent genes associated with cancer progression and metastasis. Our RNAseq findings, were analyzed within the context of The Cancer Genome Atlas Program (TCGA) data base; revealing an upregulation of sleep- and cancer-linked genes (e.g., IL-17B, IL-17RA, LCN2) across various tumors, including brain tumors, compared to normal tissues. Sleep-linked factors, identified through TCGA analyses, significantly impact patient prognosis and survival, particularly in low-grade glioma (LGG) and glioblastoma multiforme (GBM) patients. Overall, our findings suggest that SD promotes a pro-tumor environment through AcPb-modulated pathways.

Localization of brain neuronal IL-1R1 reveals specific neural circuitries responsive to immune signaling

Interleukin-1 (IL-1) is a pro-inflammatory cytokine that exerts a wide range of neurological and immunological effects throughout the central nervous system (CNS) and is associated with the etiology of affective and cognitive disorders. The cognate receptor for IL-1, Interleukin-1 Receptor Type 1 (IL-1R1), is primarily expressed on non-neuronal cells (e.g., endothelial cells, choroidal cells, ventricular ependymal cells, astrocytes, etc.) throughout the brain. However, the presence and distribution of neuronal IL-1R1 (nIL-1R1) has been controversial. Here, for the first time, a novel genetic mouse line that allows for the visualization of IL-1R1 mRNA and protein expression (Il1r1GR/GR) was used to map all brain nuclei and determine the neurotransmitter systems which express nIL-1R1 in adult male mice. The direct responsiveness of nIL-1R1-expressing neurons to both inflammatory and physiological levels of IL-1β in vivo was tested. Neuronal IL-1R1 expression across the brain was found in discrete glutamatergic and serotonergic neuronal populations in the somatosensory cortex, piriform cortex, dentate gyrus, and dorsal raphe nucleus. Glutamatergic nIL-1R1 comprises most of the nIL-1R1 expression and, using Vglut2-Cre-Il1r1r/r mice, which restrict IL-1R1 expression to only glutamatergic neurons, an atlas of glutamatergic nIL-1R1 expression across the brain was generated. Analysis of functional outputs of these nIL-1R1-expressing nuclei, in both Il1r1GR/GR and Vglut2-Cre-Il1r1r/r mice, reveals IL-1R1+ nuclei primarily relate to sensory detection, processing, and relay pathways, mood regulation, and spatial/cognitive processing centers. Intracerebroventricular (i.c.v.) injections of IL-1 (20 ng) induces NFκB signaling in IL-1R1+ non-neuronal cells but not in IL-1R1+ neurons, and in Vglut2-Cre-Il1r1r/r mice IL-1 did not change gene expression in the dentate gyrus of the hippocampus (DG). GO pathway analysis of spatial RNA sequencing 1mo following restoration of nIL-1R1 in the DG neurons reveals IL-1R1 expression downregulates genes related to both synaptic function and mRNA binding while increasing select complement markers (C1ra, C1qb). Further, DG neurons exclusively express an alternatively spliced IL-1R Accessory protein isoform (IL-1RAcPb), a known synaptic adhesion molecule. Altogether, this study reveals a unique network of neurons that can respond directly to IL-1 via nIL-1R1 through non-autonomous transcriptional pathways; earmarking these circuits as potential neural substrates for immune signaling-triggered sensory, affective, and cognitive disorders.

Oxidative stress-mediated neuroinflammation in Alzheimer's disease

Reactive oxygen species (ROS) are metabolic by-products that constitute an indispensable component of physiological processes, albeit their heightened presence may proffer substantial perils to biological entities. Such a proliferation gives rise to a gradual escalation of oxidative stress within the organism, thereby compromising mitochondrial functionality and inflicting harm upon various bodily systems, with a particular predilection for the central nervous system. In its nascent stages, it is plausible that inflammation has been a facilitator in the progression of the malady. The precise role of inflammation in Alzheimer's disease (AD) remains somewhat enigmatic, although it is conceivable that activated microglia and astrocytes might be implicated in the removal of amyloid-β (Aβ) deposits. Nonetheless, prolonged microglial activation is associated with Tau phosphorylation and Aβ aggregation. Research studies have indicated that AD brains upregulate complementary molecules, inflammatory cytokines, acute phase reacting agents, and other inflammatory mediators that may cause neurodegeneration. In this review, oxidative damage products will be discussed as potential peripheral biomarkers for AD and its early stages. The disordered excretion of pro-inflammatory cytokines, chemokines, oxygen, and nitrogen-reactive species, along with the stimulation of the complement system by glial cells, has the potential to disrupt the functionality of neuronal termini. This perturbation, in turn, culminates in compromised synaptic function, a phenomenon empirically linked to the manifestation of cognitive impairments. The management of neurodegenerative conditions in the context of dementia necessitates therapeutic interventions that specifically target the excessive production of inflammatory and oxidative agents. Furthermore, we shall deliberate upon the function of microglia and oxidative injury in the etiology of AD and the ensuing neurodegenerative processes.

Decoding paradoxical links of cytokine markers in cognition: Cross talk between physiology, inflammaging, and Alzheimer's disease- related cognitive decline

Recent research has revolutionized our understanding of memory consolidation by emphasizing the critical role of astrocytes, microglia, and immune cells in through cytokine signaling. Cytokines, compact proteins, play pivotal roles in neuronal development, synaptic transmission, and normal aging. This review explores the cellular mechanisms contributing to cognitive decline in inflammaging and Alzheimer's disease, highlighting the paradoxical effects of most studied cytokines (IL-1, IL-6, TNF-α) in brain function, which act as a double-edged sword in brain physiology, acting both as facilitators of healthy cognitive function and as a potential contributor to cognitive decline.

Ethanol drinking sex-dependently alters cortical IL-1β synaptic signaling and cognitive behavior in mice

Individuals with alcohol use disorder (AUD) struggle with inhibitory control, decision making, and emotional processing. These cognitive symptoms reduce treatment adherence, worsen clinical outcomes, and promote relapse. Neuroimmune activation is a key factor in the pathophysiology of AUD, and targeting this modulatory system is less likely to produce unwanted side effects compared to directly targeting neurotransmitter dysfunction. Notably, the cytokine interleukin-1β (IL-1β) has been broadly associated with the cognitive symptoms of AUD, though the underlying mechanisms are not well understood. Here we investigated how chronic intermittent 24-hour access two bottle choice ethanol drinking affects medial prefrontal cortex (mPFC)-related cognitive function and IL-1 synaptic signaling in male and female C57BL/6J mice. In both sexes, ethanol drinking decreased reference memory and increased mPFC IL-1 receptor 1 (IL-1R1) mRNA levels. In neurons, IL-1β can activate either pro-inflammatory or neuroprotective intracellular pathways depending on the isoform of the accessory protein (IL-1RAcP) recruited to the IL-1R1 complex. Moreover, ethanol drinking sex-dependently shifted mPFC IL-1RAcP isoform gene expression and IL-1β regulation of mPFC GABA synapses, both of which may contribute to female mPFC resiliency and male mPFC susceptibility. This type of signaling bias has become a recent focus of rational drug development. Therefore, in addition to increasing our understanding of how IL-1β sex-dependently contributes to mPFC dysfunction in AUD, our current findings also support the development of a new class of pharmacotherapeutics based on biased IL-1 signaling.

Repurposing Anakinra for Alzheimer's Disease: The In Vitro and In Vivo Effects of Anakinra on LPS- and AC-Induced Neuroinflammation

Alzheimer's disease is a significant global health issue, and studies suggest that neuroinflammation plays a vital role in the advancement of this disease. In this study, anakinra has been shown to display a time- and concentration-dependent antineuroinflammatory effect. In the in vitro studies, it diminished the gene expressions of tumor necrosis factor-alpha (TNF-α) and nitric oxide (NO) synthase 2 stimulated by lipopolysaccharide (LPS). Anakinra also reduced the LPS-induced production of NO and reactive oxygen species. Thus, the hypertrophic state of LPS-activated BV2 microglial cells was reversed by anakinra. Furthermore, acrylamide (ACR)-induced activation of nuclear transcription factor-κB, TNF-α, and interleukin-1β was downregulated, while cAMP response element binding protein and brain-derived neurotrophic factor expression levels were markedly enhanced in ACR-treated zebrafish larvae. It was also observed that anakinra improved the uncoordinated swimming behaviors in ACR-exposed zebrafish larvae. Overall, anakinra demonstrated potential antineuroinflammatory and antioxidative effects.

N-methyl-d-aspartate receptors: Structure, function, and role in organophosphorus compound poisoning

Acute organophosphorus compound (OP) poisoning induces symptoms of the cholinergic crises with the occurrence of severe epileptic seizures. Seizures are induced by hyperstimulation of the cholinergic system, but are enhanced by hyperactivation of the glutamatergic system. Overstimulation of muscarinic cholinergic receptors by the elevated acetylcholine causes glutamatergic hyperexcitation and an increased influx of Ca2+ into neurons through a type of ionotropic glutamate receptors, N-methyl-d-aspartate (NMDA) receptors (NMDAR). These excitotoxic signaling processes generate reactive oxygen species, oxidative stress, and activation of the neuroinflammatory response, which can lead to recurrent epileptic seizures, neuronal cell death, and long-term neurological damage. In this review, we illustrate the NMDAR structure, complexity of subunit composition, and the various receptor properties that change accordingly. Although NMDARs are in normal physiological conditions important for controlling synaptic plasticity and mediating learning and memory functions, we elaborate the detrimental role NMDARs play in neurotoxicity of OPs and focus on the central role NMDAR inhibition plays in suppressing neurotoxicity and modulating the inflammatory response. The limited efficacy of current medical therapies for OP poisoning concerning the development of pharmacoresistance and mitigating proinflammatory response highlights the importance of NMDAR inhibitors in preventing neurotoxic processes and points to new avenues for exploring therapeutics for OP poisoning.

Enhanced fear memory after social defeat in mice is dependent on interleukin-1 receptor signaling in glutamatergic neurons

Chronic stress is associated with increased anxiety, cognitive deficits, and post-traumatic stress disorder. Repeated social defeat (RSD) in mice causes long-term stress-sensitization associated with increased microglia activation, monocyte accumulation, and enhanced interleukin (IL)-1 signaling in endothelia and neurons. With stress-sensitization, mice have amplified neuronal, immune, and behavioral responses to acute stress 24 days later. This is clinically relevant as it shares key aspects with post-traumatic stress disorder. The mechanisms underlying stress-sensitization are unclear, but enhanced fear memory may be critical. The purpose of this study was to determine the influence of microglia and IL-1R1 signaling in neurons in the development of sensitization and increased fear memory after RSD. Here, RSD accelerated fear acquisition, delayed fear extinction, and increased cued-based freezing at 0.5 day. The enhancement in contextual fear memory after RSD persisted 24 days later. Next, microglia were depleted with a CSF1R antagonist prior to RSD and several parameters were assessed. Microglia depletion blocked monocyte recruitment to the brain. Nonetheless, neuronal reactivity (pCREB) and IL-1β RNA expression in the hippocampus and enhanced fear memory after RSD were microglial-independent. Because IL-1β RNA was prominent in the hippocampus after RSD even with microglia depletion, IL-1R1 mediated signaling in glutamatergic neurons was assessed using neuronal Vglut2+/IL-1R1-/- mice. RSD-induced neuronal reactivity (pCREB) in the hippocampus and enhancement in fear memory were dependent on neuronal IL-1R1 signaling. Furthermore, single-nuclei RNA sequencing (snRNAseq) showed that RSD influenced transcription in specific hippocampal neurons (DG neurons, CA2/3, CA1 neurons) associated with glutamate signaling, inflammation and synaptic plasticity, which were neuronal IL-1R1-dependent. Furthermore, snRNAseq data provided evidence that RSD increased CREB, BDNF, and calcium signaling in DG neurons in an IL-1R1-dependent manner. Collectively, increased IL-1R1-mediated signaling (monocytes/microglia independent) in glutamatergic neurons after RSD enhanced neuronal reactivity and fear memory.

Lupus autoantibodies initiate neuroinflammation sustained by continuous HMGB1:RAGE signaling and reversed by increased LAIR-1 expression

Cognitive impairment is a frequent manifestation of neuropsychiatric systemic lupus erythematosus, present in up to 80% of patients and leading to a diminished quality of life. In the present study, we used a model of lupus-like cognitive impairment that is initiated when antibodies that crossreact with excitatory neuronal receptors penetrate the hippocampus, causing immediate, self-limited, excitotoxic death of hippocampal neurons, which is then followed by a significant loss of dendritic complexity in surviving neurons. This injury creates a maladaptive equilibrium that is sustained in mice for at least 1 year. We identified a feedforward loop of microglial activation and microglia-dependent synapse elimination dependent on neuronal secretion of high mobility group box 1 protein (HMGB1) which binds the receptor for advanced glycation end products (RAGE) and leads to microglial secretion of C1q, upregulation of interleukin-10 with consequent downregulation of leukocyte-associated immunoglobulin-like receptor 1 (LAIR-1), an inhibitory receptor for C1q. Treatment with a centrally acting angiotensin-converting enzyme inhibitor or with an angiotensin-receptor blocker restored a healthy equilibrium, microglial quiescence and intact spatial memory.

Molecular crosstalk between circadian clock and NLRP3 inflammasome signaling in Parkinson's disease

Parkinson's disease (PD) is one of the most common neurodegenerative diseases. Research has recently found that both animal models and patients with PD have circadian dysfunction, accompanied by abnormal expression of circadian genes and proteins, which implies that the circadian clock plays a crucial role in PD etiopathogenesis. In addition, a strong relationship between NLRP3 inflammasome signaling and PD has been observed. Meanwhile, the activation of the NLRP3 inflammasome is highly relevant to dysfunctions of the molecular clock. Therefore, alleviating the neuroinflammation caused by NLRP3 inflammasome signaling by adjusting the abnormal molecular clock may be a potential strategy for preventing and treating PD. In this article, we have reviewed the potential or direct relationship between abnormalities of the circadian clock and NLRP3 inflammasome signaling in PD.

Interleukin-1 receptor accessory protein (IL-1RAP): A magic bullet candidate for immunotherapy of human malignancies

IL-1, plays a role in some pathological inflammatory conditions. This pro-inflammatory cytokine also has a crucial role in tumorigenesis and immune responses in the tumor microenvironment (TME). IL-1 receptor accessory protein (IL-1RAP), combined with IL-1 receptor-1, provides a functional complex for binding and signaling. In addition to the direct role of IL-1, some studies demonstrated that IL1-RAP has essential roles in the progression, angiogenesis, and metastasis of solid tumors such as gastrointestinal tumors, lung carcinoma, glioma, breast and cervical cancers. This molecule also interacts with FLT-3 and c-Kit tyrosine kinases and is involved in the pathogenesis of hematological malignancies such as acute myeloid lymphoma. Additionally, IL-1RAP interacts with solute carrier family 3 member 2 (SLC3A2) and thereby increasing the resistance to anoikis and metastasis in Ewing sarcoma. This review summarizes the role of IL-1RAP in different types of cancers and discusses its targeting as a novel therapeutic approach for malignancies.

"NO" Time in Fear Response: Possible Implication of Nitric-Oxide-Related Mechanisms in PTSD

Post-traumatic stress disorder (PTSD) is a psychiatric condition characterized by persistent fear responses and altered neurotransmitter functioning due to traumatic experiences. Stress predominantly affects glutamate, a neurotransmitter crucial for synaptic plasticity and memory formation. Activation of the N-Methyl-D-Aspartate glutamate receptors (NMDAR) can trigger the formation of a complex comprising postsynaptic density protein-95 (PSD95), the neuronal nitric oxide synthase (nNOS), and its adaptor protein (NOS1AP). This complex is pivotal in activating nNOS and nitric oxide (NO) production, which, in turn, activates downstream pathways that modulate neuronal signaling, including synaptic plasticity/transmission, inflammation, and cell death. The involvement of nNOS and NOS1AP in the susceptibility of PTSD and its comorbidities has been widely shown. Therefore, understanding the interplay between stress, fear, and NO is essential for comprehending the maintenance and progression of PTSD, since NO is involved in fear acquisition and extinction processes. Moreover, NO induces post-translational modifications (PTMs), including S-nitrosylation and nitration, which alter protein function and structure for intracellular signaling. Although evidence suggests that NO influences synaptic plasticity and memory processing, the specific role of PTMs in the pathophysiology of PTSD remains unclear. This review highlights pathways modulated by NO that could be relevant to stress and PTSD.

Enhanced Activation of the S1PR2-IL-1β-Src-BDNF-TrkB Pathway Mediates Neuroinflammation in the Hippocampus and Cognitive Impairment in Hyperammonemic Rats

Hyperammonemia contributes to hepatic encephalopathy. In hyperammonemic rats, cognitive function is impaired by altered glutamatergic neurotransmission induced by neuroinflammation. The underlying mechanisms remain unclear. Enhanced sphingosine-1-phosphate receptor 2 (S1PR2) activation in the cerebellum of hyperammonemic rats contributes to neuroinflammation. in In hyperammonemic rats, we assessed if blocking S1PR2 reduced hippocampal neuroinflammation and reversed cognitive impairment and if the signaling pathways were involved. S1PR2 was blocked with intracerebral JTE-013, and cognitive function was evaluated. The signaling pathways inducing neuroinflammation and altered glutamate receptors were analyzed in hippocampal slices. JTE-013 improved cognitive function in the hyperammonemic rats, and hyperammonemia increased S1P. This increased IL-1β, which enhanced Src activity, increased CCL2, activated microglia and increased the membrane expression of the NMDA receptor subunit GLUN2B. This increased p38-MAPK activity, which altered the membrane expression of AMPA receptor subunits and increased BDNF, which activated the TrkB → PI3K → Akt → CREB pathway, inducing sustained neuroinflammation. This report unveils key pathways involved in the induction and maintenance of neuroinflammation in the hippocampus of hyperammonemic rats and supports S1PR2 as a therapeutic target for cognitive impairment.

Engineered Extracellular Vesicles for Delivery of an IL-1 Receptor Antagonist Promote Targeted Repair of Retinal Degeneration

Retinal degeneration (RD) is an irreversible blinding disease that seriously affects patients' daily activities and mental health. Targeting hyperactivated microglia and regulating polarization are promising strategies for treating the disease. Mesenchymal stem cell (MSC) transplantation is proven to be an effective treatment due to its immunomodulatory and regenerative properties. However, the low efficiency of cell migration and integration of MSCs remains a major obstacle to clinical use. The goal of this study is to develop a nanodelivery system that targets hyperactivated microglia and inhibits their release of proinflammatory factors, to achieve durable neuroprotection. This approach is to engineer extracellular vesicles (EVs) isolated from MSC, modify them with a cyclic RGD (cRGD) peptide on their surface, and load them with an antagonist of the IL-1 receptor, anakinra. Comparing with non-engineered EVs, it is observed that engineered cRGD-EVs exhibit an increased targeting efficiency against hyperactivated microglia and strongly protected photoreceptors in experimental RD cells and animal models. This study provides a strategy to improve drug delivery to degenerated retinas and offers a promising approach to improve the treatment of RD through targeted modulation of the immune microenvironment via engineered cRGD-EVs.

The effects of alpha-pinene on inflammatory responses and oxidative stress in the formalin test

Alpha-pinene (α- pinene), an essential oil that falls under the category of monoterpenes, has various advantages. This research delves into the potential benefits of α-pinene in alleviating nociception caused by the formalin test and the molecular mechanisms involved. Alpha-pinene (1, 5, or 10 mg/kg/day, i.p.) was administrated for 7 days before the formalin test. Observations of nociceptive behaviors were made during the formalin test. We examined the levels of TNF-α and IL-1β, as well as the expression of COX-1 in the spinal cord. Additionally, we evaluated the levels of TNF-α, IL-1β, SOD, GSH, CAT, and MDA in the skin of the hind paw that received a formalin injection. The peripheral injection of formalin triggered nociceptive behaviors, which was notably diminished by α-pinene 5 or 10 mg/kg. The biochemical evaluation revealed that α-pinene significantly moderated the evaluation in TNF-α and IL-1β in the spinal cord induced by formalin injection. Additionally, it was found that α-pinene had a decreasing effect on the expression of COX-1 protein in the spinal cord. Also, α-pinene 5 or 10 mg/kg caused a decrease of TNF-α, IL-1β, and MDA and an increase of SOD, GSH, and CAT at the formalin injection site. The study discovered that doses of 5 or 10 mg/ml of α-pinene can effectively relieve nociceptive response in the formalin test. Alpha-pinene pretreatment reduced the presence of pro-inflammatory cytokines. It also improved the oxidative stress condition by enhancing antioxidant factors and reducing oxidant factors.

IL-1β/IL-1R1 signaling is involved in the propagation of α-synuclein pathology of the gastrointestinal tract to the brain

The pathological hallmark of Parkinson's disease (PD) is the intraneuronal accumulation of misfolded alpha-synuclein (termed Lewy bodies) in dopaminergic neurons of substantia nigra par compacta (SNc). It is assumed that the α-syn pathology is induced by gastrointestinal inflammation and then transfers to the brain by the gut-brain axis. Therefore, the relationship between gastrointestinal inflammation and α-syn pathology leading to PD remains to be investigated. In our study, rotenone (ROT) oral administration induces gastrointestinal tract (GIT) inflammation in mice. In addition, we used pseudorabies virus (PRV) for tracing studies and performed behavioral testing. We observed that ROT treatments enhance macrophage activation, inflammatory mediator expression, and α-syn pathology in the GIT 6-week post-treatment (P6). Moreover, pathological α-syn was localized with IL-1R1 positive neural cells in GIT. In line with these findings, we also find pS129-α-syn signals in the dorsal motor nucleus of the vagus (DMV) and tyrosine hydroxylase in the nigral-striatum dynamically change from 3-week post-treatment (P3) to P6. Following that, pS129-α-syn was dominant in the enteric neural cell, DMV, and SNc, accompanied by microglial activation, and these phenotypes were absent in IL-1R1r/r mice. These data suggest that IL-1β/IL-1R1-dependent inflammation of GIT can induce α-syn pathology, which then propagates to the DMV and SNc, resulting in PD.

Soluble interleukin-1 receptor type 2 plasma levels in Parkinson's disease: relationship with cardiac autonomic profile before and after peripheral mechanical somatosensory stimulation

Introduction: Systemic inflammation promotes neurodegeneration in Parkinson's disease (PD). Interleukin-1 receptor type 2 (sIL-1R2) plasma levels increase during inflammation. Data on sIL-1R2 in PD patients and its relationship with PD cardiac autonomic profile are limited, given the possible anti-inflammatory effect of vagal activation. Previously, automated mechanical peripheral somatosensory stimulation (AMPSS) enhanced cardiac vagal modulation. Objectives were to 1) evaluate sIL-1R2 plasma concentrations in PD patients and healthy controls and 2) investigate the correlations between sIL-1R2 and cardiac autonomic indices obtained by spectrum analysis of heart rate variability before and after AMPSS. Methods: sIL-1R2 plasma levels were assessed in 48 PD patients and 50 healthy controls. Electrocardiogram and beat-by-beat arterial pressure were recorded at baseline and after 5 AMPSS sessions in 16 PD patients. Results: PD patients had higher sIL-1R2 levels than controls. In the PD subgroup, an inverse correlation between sIL-1R2 and HFnu was found. There was a negative correlation between changes induced by AMPSS on HFnu and sIL-1R2. Discussion: Higher sIL-1R2 levels in PD patients reflect the inflammatory dysregulation associated with the disease. In PD patients, higher sIL-1R2 was associated with reduced cardiovagal tone. Increased cardiovagal modulation following AMPSS was associated with lower sIL-1R2 levels in Parkinson's disease patients, suggesting inflammatory state improvement.

The Intersection of Innate Immune Pathways with the Latent Herpes Simplex Virus Genome

Innate immune responses can impact different stages of viral life cycles. Herpes simplex virus latent infection of neurons and subsequent reactivation provide a unique context for immune responses to intersect with different stages of infection. Here, we discuss recent findings linking neuronal innate immune pathways with the modulation of latent infection, acting at the time of reactivation and during initial neuronal infection to have a long-term impact on the ability of the virus to reactivate.

The Effect of Biological Treatment on Fatigue in Inflammatory Bowel Disease: A Systematic Review and Meta-analysis

BACKGROUND

Fatigue is a frequent complaint in patients with inflammatory bowel disease. Biological drugs have demonstrated beneficial effects on some extraintestinal manifestations, but the effect on fatigue is not clear.

OBJECTIVE

This study investigated the effects of biological and small molecule drugs approved for inflammatory bowel disease on fatigue.

METHODS

We performed a systematic review and meta-analysis of randomized, placebo-controlled trials reporting Federal Drug Agency (FDA)-approved biological and small molecule drugs for use in ulcerative colitis and Crohn's disease in which measures of fatigue were recorded before and after treatment. Only induction studies were included. Maintenance studies were excluded. We searched Embase (Ovid), Medline (Ovid), PsycINFO (Ovid), Cinahl (EBSCOhost), Web of Science Core Collection, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov in May 2022. Risk of bias was analyzed using the Cochrane risk-of-bias tool. Standardized mean difference was used to measure the treatment effect.

RESULTS

A total of seven randomized controlled trials composed of 3835 patients were included in the meta-analysis. All of the studies included patients with moderately to severely active ulcerative colitis or Crohn's disease. The studies used three different generic fatigue instruments: the Functional Assessment of Chronic Illness Therapy-Fatigue and the Short Form 36 Health Survey Vitality Subscale versions 1 and 2. Overall treatment with biological or small molecule agents showed a beneficial effect compared with placebo, with a standardized mean difference of 0.25 (95% confidence interval 0.15-0.34, p < 0.001). The effect was independent of type of drug or subtype of inflammatory bowel disease.

DISCUSSION

The risk of bias was considered to be low for all domains except for missing outcome data. Even though the included studies were of high methodological quality, the review is limited by the small number of studies included and that the available studies were not designed to evaluate fatigue specifically.

CONCLUSION

Biological and small molecule drugs used in inflammatory bowel disease have a consistent, though small, beneficial effect on fatigue.

Chronic ethanol induces a pro-inflammatory switch in interleukin-1β regulation of GABAergic signaling in the medial prefrontal cortex of male mice

Neuroimmune pathways regulate brain function to influence complex behavior and play a role in several neuropsychiatric diseases, including alcohol use disorder (AUD). In particular, the interleukin-1 (IL-1) system has emerged as a key regulator of the brain's response to ethanol (alcohol). Here we investigated the mechanisms underlying ethanol-induced neuroadaptation of IL-1β signaling at GABAergic synapses in the prelimbic region of the medial prefrontal cortex (mPFC), an area responsible for integrating contextual information to mediate conflicting motivational drives. We exposed C57BL/6J male mice to the chronic intermittent ethanol vapor-2 bottle choice paradigm (CIE-2BC) to induce ethanol dependence, and conducted ex vivo electrophysiology and molecular analyses. We found that the IL-1 system regulates basal mPFC function through its actions at inhibitory synapses on prelimbic layer 2/3 pyramidal neurons. IL-1β can selectively recruit either neuroprotective (PI3K/Akt) or pro-inflammatory (MyD88/p38 MAPK) mechanisms to produce opposing synaptic effects. In ethanol naïve conditions, there was a strong PI3K/Akt bias leading to a disinhibition of pyramidal neurons. Ethanol dependence produced opposite IL-1 effects - enhanced local inhibition via a switch in IL-1β signaling to the canonical pro-inflammatory MyD88 pathway. Ethanol dependence also increased cellular IL-1β in the mPFC, while decreasing expression of downstream effectors (Akt, p38 MAPK). Thus, IL-1β may represent a key neural substrate in ethanol-induced cortical dysfunction. As the IL-1 receptor antagonist (kineret) is already FDA-approved for other diseases, this work underscores the high therapeutic potential of IL-1 signaling/neuroimmune-based treatments for AUD.

Aß Pathology and Neuron-Glia Interactions: A Synaptocentric View

Alzheimer's disease (AD) causes the majority of dementia cases worldwide. Early pathological hallmarks include the accumulation of amyloid-ß (Aß) and activation of both astrocytes and microglia. Neurons form the building blocks of the central nervous system, and astrocytes and microglia provide essential input for its healthy functioning. Their function integrates at the level of the synapse, which is therefore sometimes referred to as the "quad-partite synapse". Increasing evidence puts AD forward as a disease of the synapse, where pre- and postsynaptic processes, as well as astrocyte and microglia functioning progressively deteriorate. Here, we aim to review the current knowledge on how Aß accumulation functionally affects the individual components of the quad-partite synapse. We highlight a selection of processes that are essential to the healthy functioning of the neuronal synapse, including presynaptic neurotransmitter release and postsynaptic receptor functioning. We further discuss how Aß affects the astrocyte's capacity to recycle neurotransmitters, release gliotransmitters, and maintain ion homeostasis. We additionally review literature on how Aß changes the immunoprotective function of microglia during AD progression and conclude by summarizing our main findings and highlighting the challenges in current studies, as well as the need for further research.

Post-traumatic Stress Disorder: Focus on Neuroinflammation

Post-traumatic stress disorder (PTSD), gaining increasing attention, is a multifaceted psychiatric disorder that occurs following a stressful or traumatic event or series of events. Recently, several studies showed a close relationship between PTSD and neuroinflammation. Neuroinflammation, a defense response of the nervous system, is associated with the activation of neuroimmune cells such as microglia and astrocytes and with changes in inflammatory markers. In this review, we first analyzed the relationship between neuroinflammation and PTSD: the effect of stress-derived activation of the hypothalamic-pituitary-adrenal (HPA) axis on the main immune cells in the brain and the effect of stimulated immune cells in the brain on the HPA axis. We then summarize the alteration of inflammatory markers in brain regions related to PTSD. Astrocytes are neural parenchymal cells that protect neurons by regulating the ionic microenvironment around neurons. Microglia are macrophages of the brain that coordinate the immunological response. Recent studies on these two cell types provided new insight into neuroinflammation in PTSD. These contribute to promoting comprehension of neuroinflammation, which plays a pivotal role in the pathogenesis of PTSD.

Inhibitor of NF-κB Kinase Subunit ε Contributes to Neuropsychiatric Manifestations in Lupus-Prone Mice Through Microglial Activation

OBJECTIVE

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by multiorgan dysfunction. Neuropsychiatric SLE (NPSLE) occurs in 30-40% of lupus patients and is the most severe presentation of SLE, frequently resulting in limitation of daily life. Recent studies have shown that microglia, tissue-resident macrophages in the central nervous system, are involved in the pathogenesis of NPSLE. This study was undertaken to explore new therapeutic targets for NPSLE focusing on microglia.

METHODS

RNA sequencing of microglia in MRL/lpr, lupus-prone mice, as well as that of microglia cultured in vitro with cytokines were performed. A candidate gene, which could be a therapeutic target for NPSLE, was identified, and its role in microglial activation and phagocytosis was investigated using specific inhibitors and small interfering RNA. The effect of intracerebroventricular administration of the inhibitor on the behavioral abnormalities of MRL/lpr was also evaluated.

RESULTS

Transcriptome analysis revealed the up-regulation of Ikbke, which encodes the inhibitor of NF-κB kinase subunit ɛ (IKBKε) in both microglia from MRL/lpr mice and cytokine-stimulated microglia in vitro. Intracerebroventricular administration of an IKBKε inhibitor ameliorated cognitive function and suppressed microglial activation in MRL/lpr mice. Mechanistically, IKBKε inhibition reduced glycolysis, which dampened microglial activation and phagocytosis.

CONCLUSION

These findings suggest that IKBKε plays a vital role in the pathogenesis of NPSLE via microglial activation, and it could serve as a therapeutic target for NPSLE.

Molecular Mechanisms Underlying Neuroinflammation Elicited by Occupational Injuries and Toxicants

Occupational injuries and toxicant exposures lead to the development of neuroinflammation by activating distinct mechanistic signaling cascades that ultimately culminate in the disruption of neuronal function leading to neurological and neurodegenerative disorders. The entry of toxicants into the brain causes the subsequent activation of glial cells, a response known as 'reactive gliosis'. Reactive glial cells secrete a wide variety of signaling molecules in response to neuronal perturbations and thus play a crucial role in the progression and regulation of central nervous system (CNS) injury. In parallel, the roles of protein phosphorylation and cell signaling in eliciting neuroinflammation are evolving. However, there is limited understanding of the molecular underpinnings associated with toxicant- or occupational injury-mediated neuroinflammation, gliosis, and neurological outcomes. The activation of signaling molecules has biological significance, including the promotion or inhibition of disease mechanisms. Nevertheless, the regulatory mechanisms of synergism or antagonism among intracellular signaling pathways remain elusive. This review highlights the research focusing on the direct interaction between the immune system and the toxicant- or occupational injury-induced gliosis. Specifically, the role of occupational injuries, e.g., trips, slips, and falls resulting in traumatic brain injury, and occupational toxicants, e.g., volatile organic compounds, metals, and nanoparticles/nanomaterials in the development of neuroinflammation and neurological or neurodegenerative diseases are highlighted. Further, this review recapitulates the recent advancement related to the characterization of the molecular mechanisms comprising protein phosphorylation and cell signaling, culminating in neuroinflammation.

GPR55 activation prevents amphetamine-induced conditioned place preference and decrease the amphetamine-stimulated inflammatory response in the ventral hippocampus in male rats

Inflammatory response in the Central Nervous System (CNS) induced by psychostimulants seems to be a crucial factor in the development and maintenance of drug addiction. The ventral hippocampus (vHp) is part of the reward system involved in substance addiction and expresses abundant G protein-coupled receptor 55 (GPR55). This receptor modulates the inflammatory response in vitro and in vivo, but there is no information regarding its anti-inflammatory effects and its impact on psychostimulant consumption. The aim of the present study was to investigate whether vHp GPR55 activation prevents both the inflammatory response induced by amphetamine (AMPH) in the vHp and the AMPH-induced conditioned place preference (A-CPP). Wistar adult male rats with a bilateral cannula into the vHp or intact males were subjected to A-CPP (5 mg/kg). Upon the completion of A-CPP, the vHp was dissected to evaluate IL-1β and IL-6 expression through RT-PCR, Western blot and immunofluorescence. Our results reveal that AMPH induces both A-CPP and an increase of IL-1β and IL-6 in the vHp. The GPR55 agonist lysophosphatidylinositol (LPI, 10 μM) infused into the vHp prevented A-CPP and the AMPH-induced IL-1β increase. CID 16020046 (CID, 10 μM), a selective GPR55 antagonist, abolished LPI effects. To evaluate the effect of the inflammatory response, lipopolysaccharide (LPS, 5 μg/μl) was infused bilaterally into the vHp during A-CPP acquisition. LPS strengthened A-CPP and increased IL-1β/IL-6 mRNA and protein levels in the vHp. LPS also increased CD68, Iba1, GFAP and vimentin expression. All LPS-induced effects were blocked by LPI. Our results suggest that GPR55 activation in the vHp prevents A-CPP while decreasing the local neuro-inflammatory response. These findings indicate that vHp GPR55 is a crucial factor in preventing the rewarding effects of AMPH due to its capacity to interfere with proinflammatory responses in the vHp.

A Review of Antidepressant Effects and Mechanisms of Three Common Herbal Medicines: Panax ginseng, Bupleurum chinense, and Gastrodia elata

OBJECTIVES

Major depressive disorder (MDD) has been reported to affect an increasing number of individuals due to the modern lifestyle. Because of its complicated mechanisms and recurrent attacks, MDD is considered a refractory chronic disease. Although the mainstream therapy for MDD is chemical drugs, they are not a panacea for MDD because of their expensiveness, associated serious adverse reactions, and endless treatment courses. Hence, we studied three kinds of herbal medicines, namely, Panax ginseng C.A. Mey (PGM), Bupleurum chinense DC (BCD), and Gastrodia elata Blume (GEB), and reviewed the mechanisms underlying their antidepressant properties to provide a reference for the development of antidepressants and clinical medications.

METHODS

An extensive range of medicinal, clinical, and chemistry databases and search engines were used for our literature search. We searched the literature using certain web literature search engines, including Google Scholar, PubMed, Science Direct, CNKI (China National Knowledge Infrastructure), and Web of Science.

RESULTS

Experimental research found that active compounds of these three medicines exhibited good antidepressant effects in vivo and in vitro. Clinical investigations revealed that single or combined treatment of these medicines improved certain depressive symptoms. Antidepressant mechanisms are summarized based on this research.

CONCLUSION

The antidepressant mechanism of these three medicines includes but is not limited to ameliorating inflammation within the brain, reversing the hypothalamic-pituitary adrenal axis (HPA) system hyperfunction, inhibiting monoamine neurotransmitters reuptake, anti-neuron apoptosis and preventing neurotoxicity, and regulating depressive-related pathways such as the BDNF pathway and the PI3K/Akt/mTOR pathway.

The complex role of inflammation and gliotransmitters in Parkinson's disease

Our understanding of the role of innate and adaptive immune cell function in brain health and how it goes awry during aging and neurodegenerative diseases is still in its infancy. Inflammation and immunological dysfunction are common components of Parkinson's disease (PD), both in terms of motor and non-motor components of PD. In recent decades, the antiquated notion that the central nervous system (CNS) in disease states is an immune-privileged organ, has been debunked. The immune landscape in the CNS influences peripheral systems, and peripheral immunological changes can alter the CNS in health and disease. Identifying immune and inflammatory pathways that compromise neuronal health and survival is critical in designing innovative and effective strategies to limit their untoward effects on neuronal health.

Stress and the brain transcriptome: Identifying commonalities and clusters in standardized data from published experiments

Interpretation of transcriptomic experiments is hindered by many problems including false positives/negatives inherent to big-data methods and changes in gene nomenclature. To find the most consistent effect of stress on brain transcriptome, we retrieved data from 79 studies applying animal models and 3 human studies investigating post-traumatic stress disorder (PTSD). The analyzed data were obtained either with microarrays or RNA sequencing applied to samples collected from more than 1887 laboratory animals and from 121 human subjects. Based on the initial database containing a quarter million differential expression effect sizes representing transcripts in three species, we identified the most frequently reported genes in 223 stress-control comparisons. Additionally, the analysis considers sex, individual vulnerability and contribution of glucocorticoids. We also found an overlap between gene expression in PTSD patients and animals which indicates relevance of laboratory models for human stress response. Our analysis points to genes that, as far as we know, were not specifically tested for their role in stress response (Pllp, Arrdc2, Midn, Mfsd2a, Ccn1, Htra1, Csrnp1, Tenm4, Tnfrsf25, Sema3b, Fmo2, Adamts4, Gjb1, Errfi1, Fgf18, Galnt6, Slc25a42, Ifi30, Slc4a1, Cemip, Klf10, Tom1, Dcdc2c, Fancd2, Luzp2, Trpm1, Abcc12, Osbpl1a, Ptp4a2). Provided transcriptomic resource will be useful for guiding the new research.

Cilostazol Alleviates NLRP3 Inflammasome-Induced Allodynia/Hyperalgesia in Murine Cerebral Cortex Following Transient Ischemia: Focus on TRPA1/Glutamate and Akt/Dopamine/BDNF/Nrf2 Trajectories

Global cerebral ischemia/reperfusion (I/R) provokes inflammation that augments neuropathic pain. Cilostazol (CLZ) has pleiotropic effects including neuroprotection in several ravaging central disorders; nonetheless, its potential role in transient central ischemic-induced allodynia and hyperalgesia has not been asserted before. Rats were allocated into 4 groups; sham, sham + CLZ, and 45 min-bilateral carotid occlusion followed by a 48 h-reperfusion period either with or without CLZ (50 mg/kg; p.o) post-treatment. CLZ prolonged latency of hindlimb withdrawal following von Frey filaments, 4 °C cold, and noxious mechanical stimulations. Histopathological alterations and the immunoexpression of glial fibrillary acidic protein induced by I/R were reduced by CLZ in the anterior cingulate cortex (ACC) area, while, CLZ enhanced intact neuronal count. Meanwhile, CLZ modulated cerebral cortical glutamate, dopamine neurotransmission, and transient receptor potential ankyrin 1 (TRPA1). CLZ anti-inflammatory potential was mediated by the downregulated p65 NF-κB and sirtuin-1 enhancement to reduce nucleotide-binding domain-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein (ASC), active caspase-1, and interleukin-1β, indicative of inflammasome deactivation. It also revealed an antioxidant capacity via boosting nuclear factor E2-related factor (Nrf2) enhancing glutathione through forkhead box protein O3a (FOXO3a) reduction. Additionally, CLZ triggered neuronal survival by promoting the p-content of Akt, TrkB, and CREB as well as BDNF content. A novel approach of CLZ in hindering global cerebral I/R-mediated neuropathy is firstly documented herein to forward its adjunct action via deactivating the NLRP3 inflammasome, besides enhancing Nrf2 axis, neuronal survival, and dopamine neurotransmission as well as inhibiting TRPA1 and excitotoxicity.

IL-1RAP, a Key Therapeutic Target in Cancer

Cancer is a major cause of death worldwide and especially in high- and upper-middle-income countries. Despite recent progress in cancer therapies, such as chimeric antigen receptor T (CAR-T) cells or antibody-drug conjugate (ADC), new targets expressed by the tumor cells need to be identified in order to selectively drive these innovative therapies to tumors. In this context, IL-1RAP recently showed great potential to become one of these new targets for cancer therapy. IL-1RAP is highly involved in the inflammation process through the interleukins 1, 33, and 36 (IL-1, IL-33, IL-36) signaling pathways. Inflammation is now recognized as a hallmark of carcinogenesis, suggesting that IL-1RAP could play a role in cancer development and progression. Furthermore, IL-1RAP was found overexpressed on tumor cells from several hematological and solid cancers, thus confirming its potential involvement in carcinogenesis. This review will first describe the structure and genetics of IL-1RAP as well as its role in tumor development. Finally, a focus will be made on the therapies based on IL-1RAP targeting, which are now under preclinical or clinical development.

Src Family Kinases Facilitate the Crosstalk between CGRP and Cytokines in Sensitizing Trigeminal Ganglion via Transmitting CGRP Receptor/PKA Pathway

The communication between calcitonin gene-related peptide (CGRP) and cytokines plays a prominent role in maintaining trigeminal ganglion (TG) and trigeminovascular sensitization. However, the underlying regulatory mechanism is elusive. In this study, we explored the hypothesis that Src family kinases (SFKs) activity facilitates the crosstalk between CGRP and cytokines in sensitizing TG. Mouse TG tissue culture was performed to study CGRP release by enzyme-linked immunosorbent assay, cytokine release by multiplex assay, cytokine gene expression by quantitative polymerase chain reaction, and phosphorylated SFKs level by western blot. The results demonstrated that a SFKs activator, pYEEI (YGRKKRRQRRREPQY(PO3H2)EEIPIYL) alone, did not alter CGRP release or the inflammatory cytokine interleukin-1β (IL-1β) gene expression in the mouse TG. In contrast, a SFKs inhibitor, saracatinib, restored CGRP release, the inflammatory cytokines IL-1β, C-X-C motif ligand 1, C-C motif ligand 2 (CCL2) release, and IL-1β, CCL2 gene expression when the mouse TG was pre-sensitized with hydrogen peroxide and CGRP respectively. Consistently with this, the phosphorylated SFKs level was increased by both hydrogen peroxide and CGRP in the mouse TG, which was reduced by a CGRP receptor inhibitor BIBN4096 and a protein kinase A (PKA) inhibitor PKI (14–22) Amide. The present study demonstrates that SFKs activity plays a pivotal role in facilitating the crosstalk between CGRP and cytokines by transmitting CGRP receptor/PKA signaling to potentiate TG sensitization and ultimately trigeminovascular sensitization.

Fatty Acid-Derived N-acylethanolamines Dietary Supplementation Attenuates Neuroinflammation and Cognitive Impairment in LPS Murine Model

Neuroinflammation plays a critical role in the pathogenesis of most neurological and neurodegenerative diseases and therefore represents a potential therapeutic target. In this regard, accelerating the resolution process in chronic neuroinflammation may be an effective strategy to deal with the cognitive consequences of neuropathology and generalized inflammatory processes. N-acylethanolamine (NAE) derivatives of fatty acids, being highly active lipid mediators, possess pro-resolving activity in inflammatory processes and are promising agents for the suppression of neuroinflammation and its consequences. This paper is devoted to a study of the effects played by dietary supplement (DS), containing a composition of fatty acid-derived NAEs, obtained from squid Berryteuthis magister, on the hippocampal neuroinflammatory and memory processes. By detecting the production of pro-inflammatory cytokines and glial markers, a pronounced anti-inflammatory activity of DS was demonstrated both in vitro and in vivo. DS administration reversed the LPS-induced reduction in hippocampal neurogenesis and memory deterioration. LC-MS analysis revealed an increase in the production of a range of NAEs with well-documented anti-inflammatory activity in response to the administered lipid composition. To conclude, we found that tested DS suppresses the neuroinflammatory response by reducing glial activation, positively regulates neural progenitor proliferation, and attenuates hippocampal-dependent memory impairment.

Structural basis of the IL-1 receptor TIR domain-mediated IL-1 signaling

The cytoplasmic Toll/interleukin-1 receptor (TIR) domains of IL-1 receptors (IL-1Rs) are evolutionally conserved and essential for transmitting signals. IL-1RAcP is a shared co-receptor in the IL-1R family for signaling. Its splicing form IL-1RAcPb contains a different TIR domain and is unable to transduce NF-κB signaling. Here, we determined crystal structures of TIR domains of IL-1RAcPb and other IL-1Rs including IL-18Rβ, IL-1RAPL2, and zebrafish SIGIRR (zSIGIRR). Structurally variant regions in the TIR domain important for signaling were revealed by structural comparisons. Taking advantage of the IL-1RAcP/IL-1RAcPb pair, we demonstrated that differential TIR domain determines signaling discrepancies between IL-1RAcP and IL-1RAcPb. We also proved the functional importance of two helices (αC and αD) in the structurally variable regions and pinpointed critical residues in αC and αD for signaling. These results collectively provide additional and important knowledge for fully understanding the molecular basis of IL-1R TIR domain in mediating signaling.

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The crystal structures of several IL-1R TIR domains were determinated

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Structurally variant regions in TIR domains were revealed by structural comparisons

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Differential TIR domain determines signaling discrepancy between IL-1RAcP and IL-1RAcPb

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αC/αD regions and several residues there were proved to be vital for IL-1 signaling

Molecular Mechanisms in the Genesis of Seizures and Epilepsy Associated With Viral Infection

Seizures are a common presenting symptom during viral infections of the central nervous system (CNS) and can occur during the initial phase of infection ("early" or acute symptomatic seizures), after recovery ("late" or spontaneous seizures, indicating the development of acquired epilepsy), or both. The development of acute and delayed seizures may have shared as well as unique pathogenic mechanisms and prognostic implications. Based on an extensive review of the literature, we present an overview of viruses that are associated with early and late seizures in humans. We then describe potential pathophysiologic mechanisms underlying ictogenesis and epileptogenesis, including routes of neuroinvasion, viral control and clearance, systemic inflammation, alterations of the blood-brain barrier, neuroinflammation, and inflammation-induced molecular reorganization of synapses and neural circuits. We provide clinical and animal model findings to highlight commonalities and differences in these processes across various neurotropic or neuropathogenic viruses, including herpesviruses, SARS-CoV-2, flaviviruses, and picornaviruses. In addition, we extensively review the literature regarding Theiler's murine encephalomyelitis virus (TMEV). This picornavirus, although not pathogenic for humans, is possibly the best-characterized model for understanding the molecular mechanisms that drive seizures, epilepsy, and hippocampal damage during viral infection. An enhanced understanding of these mechanisms derived from the TMEV model may lead to novel therapeutic interventions that interfere with ictogenesis and epileptogenesis, even within non-infectious contexts.

Neuromodulatory effect of interleukin 1β in the dorsal raphe nucleus on individual differences in aggression

Heightened aggressive behavior is considered as one of the central symptoms of many neuropsychiatric disorders including autism, schizophrenia, and dementia. The consequences of aggression pose a heavy burden on patients and their families and clinicians. Unfortunately, we have limited treatment options for aggression and lack mechanistic insight into the causes of aggression needed to inform new efforts in drug discovery and development. Levels of proinflammatory cytokines in the periphery or cerebrospinal fluid were previously reported to correlate with aggressive traits in humans. However, it is still unknown whether cytokines affect brain circuits to modulate aggression. Here, we examined the functional role of interleukin 1β (IL-1β) in mediating individual differences in aggression using a resident-intruder mouse model. We found that nonaggressive mice exhibit higher levels of IL-1β in the dorsal raphe nucleus (DRN), the major source of forebrain serotonin (5-HT), compared to aggressive mice. We then examined the effect of pharmacological antagonism and viral-mediated gene knockdown of the receptors for IL-1 within the DRN and found that both treatments consistently increased aggressive behavior of male mice. Aggressive mice also exhibited higher c-Fos expression in 5-HT neurons in the DRN compared to nonaggressive mice. In line with these findings, deletion of IL-1 receptor in the DRN enhanced c-Fos expression in 5-HT neurons during aggressive encounters, suggesting that modulation of 5-HT neuronal activity by IL-1β signaling in the DRN controls expression of aggressive behavior.

Molecular Signature of Neuroinflammation Induced in Cytokine-Stimulated Human Cortical Spheroids

Crucial in the pathogenesis of neurodegenerative diseases is the process of neuroinflammation that is often linked to the pro-inflammatory cytokines Tumor necrosis factor alpha (TNFα) and Interleukin-1beta (IL-1β). Human cortical spheroids (hCSs) constitute a valuable tool to study the molecular mechanisms underlying neurological diseases in a complex three-dimensional context. We recently designed a protocol to generate hCSs comprising all major brain cell types. Here we stimulate these hCSs for three time periods with TNFα and with IL-1β. Transcriptomic analysis reveals that the main process induced in the TNFα- as well as in the IL-1β-stimulated hCSs is neuroinflammation. Central in the neuroinflammatory response are endothelial cells, microglia and astrocytes, and dysregulated genes encoding cytokines, chemokines and their receptors, and downstream NFκB- and STAT-pathway components. Furthermore, we observe sets of neuroinflammation-related genes that are specifically modulated in the TNFα-stimulated and in the IL-1β-stimulated hCSs. Together, our results help to molecularly understand human neuroinflammation and thus a key mechanism of neurodegeneration.

Salidroside Ameliorates Depression by Suppressing NLRP3-Mediated Pyroptosis via P2X7/NF-κB/NLRP3 Signaling Pathway

Depression is a common and serious mental disorder. Data on its pathogenesis remain unclear and the options of drug treatments are limited. Here, we explored the role of pyroptosis, a novel pro-inflammatory programmed cell death process, in depression as well as the anti-depression effects and mechanisms of salidroside (Sal), a bioactive extract from Rhodiola rosea L. We established a corticosterone (CORT)-induced or lipopolysaccharide (LPS)-induced mice in vivo, and CORT, or nigericin (NLRP3 agonist)-induced PC12 cells in vitro. Our findings demonstrated that Sal profoundly mediated CORT or LPS-induced depressive behavior and improved synaptic plasticity by upregulating the expression of brain-derived neurotrophic factor (BDNF) gene. The data showed upregulation of proteins associated with NLRP3-mediated pyroptosis, including NLRP3, cleaved Caspase-1, IL-1β, IL-18, and cleaved GSDMD. The molecular docking simulation predicted that Sal would interact with P2X7 of the P2X7/NF-κB/NLRP3 signaling pathway. In addition, our findings showed that the NLRP3-mediated pyroptosis was regulated by P2X7/NF-κB/NLRP3 signaling pathway. Interestingly, Sal was shown to ameliorate depression via suppression of the P2X7/NF-κB/NLRP3 mediated pyroptosis, and rescued nigericin-induced pyroptosis in the PC12 cells. Besides, knock down of the NLRP3 gene by siRNA markedly increased the inhibitory effects of Sal on pyroptosis and proinflammatory responses. Taken together, our findings demonstrated that pyroptosis plays a crucial role in depression, and Sal ameliorates depression by suppressing the P2X7/NF-κB/NLRP3-mediated pyroptosis. Thus, our study provides new insights into the potential treatment options for depression.

Novel IL1RAP mutation associated with schizophrenia interferes with neuronal growth and related NF-κB signal pathways

Schizophrenia is a complex, severe psychiatric disorder with a high heritability that affects approximately 1% of the world's population. Numerous schizophrenia-related risk genes have been reported in large-scale studies, but the role of most genetic abnormalities in the pathogenesis of the disease is still obscure. In this study, using whole-exome sequencing, we identified a novel nonsense mutation c.1324C>T in the Interleukin 1 receptor accessory protein (IL1RAP) gene in four affected individuals with schizophrenia of a Chinese family.IL1RAP was found involved in initiating the immune responses and regulating synaptic formation. Considering that schizophrenia has been hypothesized to be neurodevelopment disorder for decades, we further explored the influence of altered expression of IL1RAP gene on neuronal growth, and assessed whether this mutation affects the function of IL1RAP protein in IL-1 signaling pathway. We used lentivirus-mediated shRNA to knockdown the IL1RAP gene expression, which suppressed the axon and dendrites growth of cultured mouse cortical neurons. These defects can be recovered by human IL1RAP wild type construct, but not the R442* mutant construct. Furthermore, this mutant even inhibited neuronal growth and IL-1β-induced JNK phosphorylation when overexpressed in cortical neurons. Although overexpression of this mutant in HePG2 cells did not change IL1RAP protein expression, it partially prohibited the IL-1β-induced nuclear translocation of transcript factor NF-κB, indicating that IL1RAP c.1324C>T is a loss-of-function mutation. Our findings show that IL1RAP plays an important role in early stages of neurodevelopment, and the mutation c.1324C>T may contribute to the pathogenesis of schizophrenia.

Actions of Klotho on hippocampal neuronal cells

Klotho gene was originally recognized as a putative aging-suppressor and its prominent age-regulating effects are mostly attributed to the modulation of mineral homeostasis in the kidney. However, recent studies link alterations in hippocampal Klotho expression with cognitive impairment and neurodegenerative diseases. This suggests that hippocampal neurons require Klotho for health and proper functionality. Klotho protects against neuronal dysfunction and regulates several intracellular signaling pathways including oxidative stress response, inflammation, DNA damage, autophagy, endoplasmic reticulum stress response, and multiple types of cell death. Specifically, this chapter covers the current knowledge as to how Klotho protein affects the hippocampal neuronal cells, with special attention paid to underlying molecular mechanisms, and thus influences hippocampal development, hippocampal-dependent cognition, behavior, and motor skills as well as mediates neurodegenerative processes.

Calcium Ions Aggravate Alzheimer's Disease Through the Aberrant Activation of Neuronal Networks, Leading to Synaptic and Cognitive Deficits

Alzheimer’s disease (AD) is a neurodegenerative disease that is characterized by the production and deposition of β-amyloid protein (Aβ) and hyperphosphorylated tau, leading to the formation of β-amyloid plaques (APs) and neurofibrillary tangles (NFTs). Although calcium ions (Ca²⁺) promote the formation of APs and NFTs, no systematic review of the mechanisms by which Ca²⁺ affects the development and progression of AD has been published. Therefore, the current review aimed to fill the gaps between elevated Ca²⁺ levels and the pathogenesis of AD. Specifically, we mainly focus on the molecular mechanisms by which Ca²⁺ affects the neuronal networks of neuroinflammation, neuronal injury, neurogenesis, neurotoxicity, neuroprotection, and autophagy. Furthermore, the roles of Ca²⁺ transporters located in the cell membrane, endoplasmic reticulum (ER), mitochondria and lysosome in mediating the effects of Ca²⁺ on activating neuronal networks that ultimately contribute to the development and progression of AD are discussed. Finally, the drug candidates derived from herbs used as food or seasoning in Chinese daily life are summarized to provide a theoretical basis for improving the clinical treatment of AD.

Zinc induces reactive astrogliosis through ERK-dependent activation of Stat3 and promotes synaptic degeneration

Reactive astrogliosis is an early event in Alzheimer's disease (AD) brain and plays a key role in synaptic degeneration in AD development. Zinc accumulates in extracellular fraction and synaptosomes in AD human brains with its effect on reactive astrocytes remaining unknown. Through Western blotting, Quantitative polymerase chain reaction (qPCR), and immunofluorescence detection on primary astrocytes treated by zinc and/or zinc chelator, we revealed that zinc induced harmful A1-type reactive astrogliosis in cultured primary astrocytes; the latter, promoted synaptic degeneration in primary neurons. The mechanism investigation showed that zinc induced activation of extracellular regulated protein kinase (ERK) and Janus kinase 2 (JAK2), which phosphorylated signal transduction and transcription activator 3 (Stat3) at serine 727 (S727-Stat3) and tyrosine 705 (Y705-Stat3), respectively, resulting in activation of Stat3. Stat3 phosphorylation at S727 by ERK plays a key role in zinc-induced astrogliosis. These data imply a new molecular mechanism of reactive astrogliosis in AD, in which excessive zinc activates Stat3 through up-regulating ERK signaling pathway.

NLRP2 Is Overexpressed in Spinal Astrocytes at the Peak of Mechanical Pain Sensitivity during Complete Freund Adjuvant-Induced Persistent Pain

Our earlier findings revealed that interleukin-1 receptor type-1 (IL-1R1) was overexpressed in spinal neurons, and IL-1R1-deficient mice showed significant attenuation of thermal and mechanical allodynia during the course of the Complete Freund adjuvant (CFA)-induced persistent pain model. In the present study, we found that a ligand of IL-1R1, termed interleukin-1β (IL-1β), is also significantly overexpressed at the peak of mechanical pain sensitivity in the CFA-evoked pain model. Analysis of cellular distribution and modeling using IMARIS software showed that in the lumbar spinal dorsal horn, IL-1β is significantly elevated by astrocytic expression. Maturation of IL-1β to its active form is facilitated by the formation of the multiprotein complex called inflammasome; thus, we tested the expression of NOD-like receptor proteins (NLRPs) in astrocytes. At the peak of mechanical allodynia, we found expression of the NLRP2 inflammasome sensor and its significantly elevated co-localization with the GFAP astrocytic marker, while NLRP3 was moderately present and NLRP1 showed total segregation from the astrocytic profiles. Our results indicate that peripheral CFA injection induces NLRP2 inflammasome and IL-1β expression in spinal astrocytes. The release of mature IL-1β can contribute to the maintenance of persistent pain by acting on its neuronally expressed receptor, which can lead to altered neuronal excitability.

Three's Company: Neuroimmune activation, sex, and memory at the tripartite synapse

The neuroimmune system is required for normal cognitive functions such as learning and memory in addition to its critical role in detecting and responding to invading pathogens and injury. Understanding the functional convergence of neurons, astrocytes, and microglia at the synapse, particularly in the hippocampus, is key to understanding the nuances of such diverse roles. In the healthy brain, communication between all three cells is important for regulating neuronal activation and synaptic plasticity mechanisms, and during neuroinflammation, the activity and functions of all three cells can produce and be modulated by inflammatory cytokines. An important remaining component to this system is the conclusive evidence of sex differences in hippocampal plasticity mechanisms, hormone modulation of synaptic plasticity, functional properties of hippocampal neurons, and in neuroimmune activation. Sex as a biological variable here is necessary to consider given sex differences in the prevalence of memory-related disorders such as Alzheimer's disease and Post-Traumatic Stress disorder, both of which present with neuroimmune dysregulation. To make meaningful progress towards a deeper understanding of sex biases in memory-related disease prevalence, I propose that the next chapter of psychoneuroimmune research must focus on the signal integration and transduction at the synapse between experience-dependent plasticity mechanisms, neuroimmune activation, and the influence of biological sex.

Internalization of the Membrane Attack Complex Triggers NLRP3 Inflammasome Activation and IL-1β Secretion in Human Macrophages

Interleukin 1β (IL-1β) plays a major role in inflammation and is secreted by immune cells, such as macrophages, upon recognition of danger signals. Its secretion is regulated by the inflammasome, the assembly of which results in caspase 1 activation leading to gasdermin D (GSDMD) pore formation and IL-1β release. During inflammation, danger signals also activate the complement cascade, resulting in the formation of the membrane attack complex (MAC). Here, we report that stimulation of LPS-primed human macrophages with sub-lytic levels of MAC results in activation of the NOD-like receptor 3 (NLRP3) inflammasome and GSDMD-mediated IL-1β release. The MAC is first internalized into endosomes and then colocalizes with inflammasome components; adapter protein apoptosis associated speck-like protein containing a CARD (ASC) and NLRP3. Pharmacological inhibitors established that MAC-triggered activation of the NLRP3 inflammasome was dependent on MAC endocytosis. Internalization of the MAC also caused dispersion of the trans-Golgi network. Thus, these data uncover a role for the MAC in activating the inflammasome and triggering IL-1β release in human macrophages.

The role of meningeal populations of type II innate lymphoid cells in modulating neuroinflammation in neurodegenerative diseases

Recent research into meningeal lymphatics has revealed a never-before appreciated role of type II innate lymphoid cells (ILC2s) in modulating neuroinflammation in the central nervous system (CNS). To date, the role of ILC2-mediated inflammation in the periphery has been well studied. However, the exact distribution of ILC2s in the CNS and therefore their putative role in modulating neuroinflammation in neurodegenerative diseases such as Alzheimer's disease (AD), multiple sclerosis (MS), Parkinson's disease (PD), and major depressive disorder (MDD) remain highly elusive. Here, we review the current evidence of ILC2-mediated modulation of neuroinflammatory cues (i.e., IL-33, IL-25, IL-5, IL-13, IL-10, TNFα, and CXCL16-CXCR6) within the CNS, highlight the distribution of ILC2s in both the periphery and CNS, and discuss some challenges associated with cell type-specific targeting that are important for therapeutics. A comprehensive understanding of the roles of ILC2s in mediating and responding to inflammatory cues may provide valuable insight into potential therapeutic strategies for many dementia-related disorders.

Modulation of Neural Networks by Interleukin-1

Interleukin-1 (IL-1) is an inflammatory cytokine that has been shown to modulate neuronal signaling in homeostasis and diseases. In homeostasis, IL-1 regulates sleep and memory formation, whereas in diseases, IL-1 impairs memory and alters affect. Interestingly, IL-1 can cause long-lasting changes in behavior, suggesting IL-1 can alter neuroplasticity. The neuroplastic effects of IL-1 are mediated via its cognate receptor, Interleukin-1 Type 1 Receptor (IL-1R1), and are dependent on the distribution and cell type(s) of IL-1R1 expression. Recent reports found that IL-1R1 expression is restricted to discrete subpopulations of neurons, astrocytes, and endothelial cells and suggest IL-1 can influence neural circuits directly through neuronal IL-1R1 or indirectly via non-neuronal IL-1R1. In this review, we analyzed multiple mechanisms by which IL-1/IL-1R1 signaling might impact neuroplasticity based upon the most up-to-date literature and provided potential explanations to clarify discrepant and confusing findings reported in the past.

Tubular human brain organoids to model microglia-mediated neuroinflammation

Human brain organoids, 3D brain tissue cultures derived from human pluripotent stem cells, hold promising potential in modeling neuroinflammation for a variety of neurological diseases. However, challenges remain in generating standardized human brain organoids that can recapitulate key physiological features of a human brain. Here, we present tubular organoid-on-a-chip devices to generate better organoids and model neuroinflammation. By employing 3D printed hollow mesh scaffolds, our device can be easily incorporated into multiwell-plates for reliable, scalable, and reproducible generation of tubular organoids. By introducing rocking flows through the tubular device channel, our device can perfuse nutrients and oxygen to minimize organoid necrosis and hypoxia, and incorporate immune cells into organoids to model neuro-immune interactions. Compared with conventional protocols, our method increased neural progenitor proliferation and reduced heterogeneity of human brain organoids. As a proof-of-concept application, we applied this method to model the microglia-mediated neuroinflammation after exposure to an opioid receptor agonist. We found isogenic microglia were activated after exposure to an opioid receptor agonist (DAMGO) and transformed back to the homeostatic status with further treatment by a cannabinoid receptor 2 (CB2) agonist (LY2828360). Importantly, the activated microglia in tubular organoids had stronger cytokine responses compared to those in 2D microglial cultures. Our tubular organoid device is simple, versatile, inexpensive, easy-to-use, and compatible with multiwell-plates, so it can be widely used in common research and clinical laboratory settings. This technology can be broadly used for basic and translational applications in inflammatory diseases including substance use disorders, neural diseases, autoimmune disorders, and infectious diseases.