Regional Neural Activation Defines a Gateway for Autoreactive T Cells to Cross the Blood-Brain Barrier

IL-6 in inflammation, autoimmunity and cancer

IL-6 is involved both in immune responses and in inflammation, hematopoiesis, bone metabolism and embryonic development. IL-6 plays roles in chronic inflammation (closely related to chronic inflammatory diseases, autoimmune diseases and cancer) and even in the cytokine storm of corona virus disease 2019 (COVID-19). Acute inflammation during the immune response and wound healing is a well-controlled response, whereas chronic inflammation and the cytokine storm are uncontrolled inflammatory responses. Non-immune and immune cells, cytokines such as IL-1β, IL-6 and tumor necrosis factor alpha (TNFα) and transcription factors nuclear factor-kappa B (NF-κB) and signal transducer and activator of transcription 3 (STAT3) play central roles in inflammation. Synergistic interactions between NF-κB and STAT3 induce the hyper-activation of NF-κB followed by the production of various inflammatory cytokines. Because IL-6 is an NF-κB target, simultaneous activation of NF-κB and STAT3 in non-immune cells triggers a positive feedback loop of NF-κB activation by the IL-6-STAT3 axis. This positive feedback loop is called the IL-6 amplifier (IL-6 Amp) and is a key player in the local initiation model, which states that local initiators, such as senescence, obesity, stressors, infection, injury and smoking, trigger diseases by promoting interactions between non-immune cells and immune cells. This model counters dogma that holds that autoimmunity and oncogenesis are triggered by the breakdown of tissue-specific immune tolerance and oncogenic mutations, respectively. The IL-6 Amp is activated by a variety of local initiators, demonstrating that the IL-6-STAT3 axis is a critical target for treating diseases.

A comprehensive review on the role of chemokines in the pathogenesis of multiple sclerosis

Multiple sclerosis (MS) as a chronic inflammatory disorder of the central nervous system (CNS) is thought to be caused by the abnormal induction of immune responses. Chemokines as molecules that can engage leukocytes into the location of inflammation, actively participate in the pathogenesis of MS. Several members of this family of chemo attractants have been shown to be dysregulated in the peripheral blood, cerebrospinal fluid or CNS lesions of MS patients. Studies in animal models of MS particularly experimental autoimmune encephalomyelitis have indicated the critical roles of chemokines in the pathophysiology of MS. In the current review, we summarize the data regarding the role of CCL2, CCL3, CCL4, CCL11, CCL20, CXCL1, CXCL2, CXCL8, CXCL10, CXCL12 and CXCL13 in the pathogenesis of MS.

Active psychosis and pro-inflammatory cytokines in first-episode of psychosis

Higher levels of pro-inflammatory cytokines are consistently found in the serum of first episode psychosis (FEP) patients and this immune dysfunction could contribute to neural harm. On the other hand, lengthy periods of active psychosis during the early phases of the illness appear to be associated to worst functional outcome. We aim to explore the possible relationship between lengthy periods of active psychosis during early phases of the illness and the levels of pro-inflammatory cytokines. This is a prospective clinical study consisting of a 3-year clinical follow-up. We assessed the relation between the duration of active psychosis in patients with FEP and the serum levels of 21 cytokines at baseline and 3 months after initiating antipsychotic medication. We used the Human High Sensitivity T Cell Magnetic Bead Panel protocol from the Milliplex® Map Kit. The sample consisted of 59 patients with a FEP. The percentage of variation of the serum levels of the chemokine MIP-3α during the first 3 months of antipsychotic treatment and the score in negative psychotic symptoms 3 months after the initiation of antipsychotic medication, acted as predictors of the initial time to remission of positive psychotic symptoms. Our findings open the possibility to investigating the potential use of the variation in chemokine MIP-3α serum levels during the first months of antipsychotic treatment to identify a subtype of FEP patients that could benefit from an add-on treatment with immune modulators. CLINICALTRIALS.GOV ID: NCT02897167. DATE OF FIRST REGISTRATION: September 13, 2016. "Study of the Activation of Proinflammatory Pathways of Toll-like Receptors in Schizophrenia Patients (PAFIP_TLR)". https://clinicaltrials.gov/ct2/show/NCT02897167.

Differential effects on blood and cerebrospinal fluid immune protein markers and kynurenine pathway metabolites from aerobic physical exercise in healthy subjects

Mounting evidence shows that physical exercise modulates systemic inflammation. However, its effect on cerebrospinal fluid (CSF) immune-marker profiles in man are largely unknown. We here report a study on healthy subjects (n = 27, males = 12, mean age 28.7, range 22-52) allocated to either an acute exercise setting over four consecutive days, or a training intervention over 4 weeks. Paired plasma and CSF samples collected at baseline, after 7 days of exercise abstention, and the day after completion of the exercise interventions, were analyzed for protein inflammation markers using a multiplex proximity extension assay and neurotransmitters and kynurenine pathway (KP) metabolites using liquid chromatography, respectively. Routine cell counts, and albumin, immunoglobulin G and neurofilament light chain concentrations in CSF remained unchanged in both paradigms, while several inflammatory proteins became upregulated after acute exercise. However, only changes in three CSF (vascular endothelial growth factor-A, interleukin-7 and matrix metalloproteinase-10) and 12 plasma proteins reached significance levels after adjustment for multiple comparisons and exclusion of less stable proteins. Similarly, KP metabolites only changed among participants after acute exercise, while neurotransmitter levels, except for increased CSF serine, remained stable. Both in plasma and CSF changes in KP metabolites and inflammatory proteins correlated, suggesting that these processes are functionally linked. These findings suggest that acute aerobic physical exercise affects immune markers and KP metabolites systemically and in the CSF.

A noninflammatory mRNA vaccine for treatment of experimental autoimmune encephalomyelitis

The ability to control autoreactive T cells without inducing systemic immune suppression is the major goal for treatment of autoimmune diseases. The key challenge is the safe and efficient delivery of pharmaceutically well-defined antigens in a noninflammatory context. Here, we show that systemic delivery of nanoparticle-formulated 1 methylpseudouridine-modified messenger RNA (m1Ψ mRNA) coding for disease-related autoantigens results in antigen presentation on splenic CD11c+ antigen-presenting cells in the absence of costimulatory signals. In several mouse models of multiple sclerosis, the disease is suppressed by treatment with such m1Ψ mRNA. The treatment effect is associated with a reduction of effector T cells and the development of regulatory T cell (Treg cell) populations. Notably, these Treg cells execute strong bystander immunosuppression and thus improve disease induced by cognate and noncognate autoantigens.

Preparation of Thin Frozen Sections from Nonfixed and Undecalcified Hard Tissues Using Kawamoto's Film Method (2020)

A method for preparing frozen sections with an adhesive film is described. In order to observe fine structures and weak fluorescence of samples, new types of adhesive films [Cryofilm type 3C(16UF) and 4D(16UF)] are used. The adhesive film is made with very clear and very low autofluorescence. For gene analysis, a very thin adhesive film (LMD film) is used to cut by means of the laser microdissection (LMD). For MALDI mass spectrometry imaging (MALDI-MSI), a conductive adhesive film (Cryofilm type MS) is used to avoid electric charge of the sample. A biological sample is frozen quickly and freeze-embedded. The frozen sample is cut with a very sharp disposable blade made from fine tungsten carbide. The combination of the adhesive films and the blade can generate 3 micrometer thick sections from samples including bone, while it is also possible to generate 1 μm thick sections. The morphology of bone and soft tissues are preserved using this method. Cells such as osteoblasts, fibroblasts, and osteoclasts are clearly observed with an oil immersion lens at high magnification. Sections generated using the Cryofilm type 3C(16UF) shows weak fluorescent signals more clearly than sections generated with the previously reported adhesive films [Cryofilm type 2C(9) and 2C(10)]. Furthermore fluorescence of the fine structures in cells is clearly shown using a super-high-resolution microscope. Several staining and experimental methods such as histology, histochemistry, enzyme histochemistry, immunohistochemistry, and in situ hybridization can be performed on these sections. This method is also useful for preparing frozen sections of large sample such as a whole-body mouse and rat. In gene analysis, gene quality of sample collected from the section made with the LMD film is superior to that of sample made by a conventional method. The Cryofilm type MS makes almost complete section from tissues including hard tissues and large samples. The satisfactory signals are detected from the section with MALDI-MSI.

Molecular and Cellular Mechanisms Associated with Effects of Molecular Hydrogen in Cardiovascular and Central Nervous Systems

The increased production of reactive oxygen species and oxidative stress are important factors contributing to the development of diseases of the cardiovascular and central nervous systems. Molecular hydrogen is recognized as an emerging therapeutic, and its positive effects in the treatment of pathologies have been documented in both experimental and clinical studies. The therapeutic potential of hydrogen is attributed to several major molecular mechanisms. This review focuses on the effects of hydrogen on the cardiovascular and central nervous systems, and summarizes current knowledge about its actions, including the regulation of redox and intracellular signaling, alterations in gene expressions, and modulation of cellular responses (e.g., autophagy, apoptosis, and tissue remodeling). We summarize the functions of hydrogen as a regulator of nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated redox signaling and the association of hydrogen with mitochondria as an important target of its therapeutic action. The antioxidant functions of hydrogen are closely associated with protein kinase signaling pathways, and we discuss possible roles of the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) and Wnt/β-catenin pathways, which are mediated through glycogen synthase kinase 3β and its involvement in the regulation of cellular apoptosis. Additionally, current knowledge about the role of molecular hydrogen in the modulation of autophagy and matrix metalloproteinases-mediated tissue remodeling, which are other responses to cellular stress, is summarized in this review.

Current Status and Challenges Associated with CNS-Targeted Gene Delivery across the BBB

The era of the aging society has arrived, and this is accompanied by an increase in the absolute numbers of patients with neurological disorders, such as Alzheimer’s disease (AD) and Parkinson’s disease (PD). Such neurological disorders are serious costly diseases that have a significant impact on society, both globally and socially. Gene therapy has great promise for the treatment of neurological disorders, but only a few gene therapy drugs are currently available. Delivery to the brain is the biggest hurdle in developing new drugs for the central nervous system (CNS) diseases and this is especially true in the case of gene delivery. Nanotechnologies such as viral and non-viral vectors allow efficient brain-targeted gene delivery systems to be created. The purpose of this review is to provide a comprehensive review of the current status of the development of successful drug delivery to the CNS for the treatment of CNS-related disorders especially by gene therapy. We mainly address three aspects of this situation: (1) blood-brain barrier (BBB) functions; (2) adeno-associated viral (AAV) vectors, currently the most advanced gene delivery vector; (3) non-viral brain targeting by non-invasive methods.

Orosomucoid 1 is involved in the development of chronic allograft rejection after kidney transplantation

Chronic allograft rejection is the most common cause of long-term allograft failure. One reason is that current diagnostics and therapeutics for chronic allograft rejection are very limited. We here show that enhanced NFκB signaling in kidney grafts contributes to chronic active antibody-mediated rejection (CAAMR), which is a major pathology of chronic kidney allograft rejections. Moreover, we found that urinary orosomucoid 1 (ORM1) is a candidate marker molecule and therapeutic target for CAAMR. Indeed, urinary ORM1 concentration was significantly higher in kidney transplant recipients pathologically diagnosed with CAAMR than in kidney transplant recipients with normal histology, calcineurin inhibitor toxicity, or interstitial fibrosis and tubular atrophy. Additionally, we found that kidney biopsy samples with CAAMR expressed more ORM1 and had higher NFκB and STAT3 activation in tubular cells than samples from non-CAAMR samples. Consistently, ORM1 production was induced after cytokine-mediated NFκB and STAT3 activation in primary kidney tubular cells. The loss- and gain-of-function of ORM1 suppressed and promoted NFκB activation, respectively. Finally, ORM1-enhanced NFκB-mediated inflammation development in vivo. These results suggest that an enhanced NFκB-dependent pathway following NFκB and STAT3 activation in the grafts is involved in the development of chronic allograft rejection after kidney transplantation and that ORM1 is a non-invasive candidate biomarker and possible therapeutic target for chronic kidney allograft rejection.

Protective Immunity to Dengue Virus Induced by DNA Vaccines Encoding Nonstructural Proteins in a Lethal Challenge Immunocompetent Mouse Model

Dengue virus represents the main arbovirus affecting humans, but there are no effective drugs or available worldwide licensed vaccine formulations capable of conferring full protection against the infection. Experimental studies and results generated after the release of the licensed anti-DENV vaccine demonstrated that induction of high-titer neutralizing antibodies does not represent the sole protection correlate and that, indeed, T cell-based immune responses plays a relevant role in the establishment of an immune protective state. In this context, this study aimed to further demonstrate protective features of immune responses elicited in immunocompetent C57BL/6 mice immunized with three plasmids encoding DENV2 nonstructural proteins (NS1, NS3, and NS5), which were subsequently challenged with a DENV2 strain naturally capable of inducing lethal encephalitis in immunocompetent mouse strains. The animals were immunized intramuscularly with the DNA vaccine mix and complete protection was observed among vaccinated mice. Vaccine induced protection correlated with the cytokine profiles expressed by spleen cells and brain-infiltrating mononuclear cells. The results confirm the pivotal role of cellular immune responses targeting nonstructural DENV proteins and validate the experimental model based on a DENV2 strain capable of infecting and killing immunocompetent mice as a tool for the evaluation of protective immunity induced by anti-DENV vaccines.

Regulatory T cells suppress Th17 cell Ca2+ signaling in the spinal cord during murine autoimmune neuroinflammation

T lymphocyte motility and interaction dynamics with other immune cells are vital determinants of immune responses. Regulatory T (Treg) cells prevent autoimmune disorders by suppressing excessive lymphocyte activity, but how interstitial motility patterns of Treg cells limit neuroinflammation is not well understood. We used two-photon microscopy to elucidate the spatial organization, motility characteristics, and interactions of endogenous Treg and Th17 cells together with antigen-presenting cells (APCs) within the spinal cord leptomeninges in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. Th17 cells arrive before the onset of clinical symptoms, distribute uniformly during the peak, and decline in numbers during later stages of EAE. In contrast, Treg cells arrive after Th17 cells and persist during the chronic phase. Th17 cells meander widely, interact with APCs, and exhibit cytosolic Ca²⁺ transients and elevated basal Ca²⁺ levels before the arrival of Treg cells. In contrast, Treg cells adopt a confined, repetitive-scanning motility while contacting APCs. These locally confined but highly motile Treg cells limit Th17 cells from accessing APCs and suppress Th17 cell Ca²⁺ signaling by a mechanism that is upstream of store-operated Ca²⁺ entry. Finally, Treg cell depletion increases APC numbers in the spinal cord and exaggerates ongoing neuroinflammation. Our results point to fundamental differences in motility characteristics between Th17 and Treg cells in the inflamed spinal cord and reveal three potential cellular mechanisms by which Treg cells regulate Th17 cell effector functions: reduction of APC density, limiting access of Th17 cells to APCs, and suppression of Th17 Ca²⁺ signaling.

The integrity of cochlear hair cells is established and maintained through the localization of Dia1 at apical junctional complexes and stereocilia

Dia1, which belongs to the diaphanous-related formin family, influences a variety of cellular processes through straight actin elongation activity. Recently, novel DIA1 mutants such as p.R1213X (p.R1204X) and p.A265S, have been reported to cause an autosomal dominant sensorineural hearing loss (DFNA1). Additionally, active DIA1 mutants induce progressive hearing loss in a gain-of-function manner. However, the subcellular localization and pathological function of DIA1(R1213X/R1204X) remains unknown. In the present study, we demonstrated the localization of endogenous Dia1 and the constitutively active DIA1 mutant in the cochlea, using transgenic mice expressing FLAG-tagged DIA1(R1204X) (DIA1-TG). Endogenous Dia1 and the DIA1 mutant were regionally expressed at the organ of Corti and the spiral ganglion from early life; alongside cochlear maturation, they became localized at the apical junctional complexes (AJCs) between hair cells (HCs) and supporting cells (SCs). To investigate HC vulnerability in the DIA1-TG mice, we exposed 4-week-old mice to moderate noise, which induced temporary threshold shifts with cochlear synaptopathy and ultrastructural changes in stereocilia 4 weeks post noise exposure. Furthermore, we established a knock-in (KI) mouse line expressing AcGFP-tagged DIA1(R1213X) (DIA1-KI) and confirmed mutant localization at AJCs and the tips of stereocilia in HCs. In MDCK^{AcGFP-DIA1(R1213X)} cells with stable expression of AcGFP-DIA1(R1213X), AcGFP-DIA1(R1213X) revealed marked localization at microvilli on the apical surface of cells and decreased localization at cell-cell junctions. The DIA1-TG mice demonstrated hazy and ruffled circumferential actin belts at AJCs and abnormal stereocilia accompanied with HC loss at 5 months of age. In conclusion, Dia1 plays a pivotal role in the development and maintenance of AJCs and stereocilia, ensuring cochlear and HC integrity. Subclinical/latent vulnerability of HCs may be the cause of progressive hearing loss in DFNA1 patients, thus suggesting new therapeutic targets for preventing HC degeneration and progressive hearing loss associated with DFNA1.

Swimming Exercise Ameliorates Symptoms of MOG-Induced Experimental Autoimmune Encephalomyelitis by Inhibiting Inflammation and Demyelination in Rats

Purpose

Multiple sclerosis is an autoimmune disease that affects the central nerve system, resulting in cumulative loss of motor function. Multiple sclerosis is induced through multiple mechanisms and is caused by inflammation and demyelination. This study aims to evaluate the neuroprotective effect of swimming exercise in experimental autoimmune encephalomyelitis (EAE) rats, an animal model of multiple sclerosis.

Methods

EAE was induced by an intradermal injection of 50-μg purified myelin oligodendrocyte glycoprotein 33–55 (MOG_33-55) dissolved in 200-μL saline at the base of the tail. The rats in the swimming exercise group were made to swim for 30 minutes once pert a day for 26 consecutive days, starting 5 days after induction of EAE. To compare the effect of swimming exercise with interferon-β, a drug for multiple sclerosis, interferon-β was injected intraperitoneally into rats of the EAE-induced and interferon-β-treated group during the exercise period.

Results

Injection of MOG_33-55 caused weight loss, decreased clinical disability score, and increased level of pro-inflammatory cytokines and inflammatory mediators in the lumbar spinal cord. Loss of motor function and weakness increased demyelination score. Swimming exercise suppressed demyelination and expression of pro-inflammatory cytokines and inflammatory mediators. These changes promoted recovery of EAE symptoms such as body weight loss, motor dysfunction, and weakness. Swimming exercise caused the same level of improvement as interferon-β treatment.

Conclusions

The results of this experiment suggest the possibility of swimming exercise in urological diseases that are difficult to treat. Swimming exercises can be considered for relief of symptom in incurable multiple sclerosis.

Inflammation-related plasma and CSF biomarkers for multiple sclerosis

Effective biomarkers for multiple sclerosis diagnosis, assessment of prognosis, and treatment responses, in particular those measurable in blood, are largely lacking. We have investigated a broad set of protein biomarkers in cerebrospinal fluid (CSF) and plasma using a highly sensitive proteomic immunoassay. Cases from two independent cohorts were compared with healthy controls and patients with other neurological diseases. We identified and replicated 10 cerebrospinal fluid proteins including IL-12B, CD5, MIP-1a, and CXCL9 which had a combined diagnostic efficacy similar to immunoglobulin G (IgG) index and neurofilament light chain (area under the curve [AUC] = 0.95). Two plasma proteins, OSM and HGF, were also associated with multiple sclerosis in comparison to healthy controls. Sensitivity and specificity of combined CSF and plasma markers for multiple sclerosis were 85.7% and 73.5%, respectively. In the discovery cohort, eotaxin-1 (CCL11) was associated with disease duration particularly in patients who had secondary progressive disease (P _CSF < 4 × 10^-5, P _plasma < 4 × 10^-5), and plasma CCL20 was associated with disease severity (P = 4 × 10^-5), although both require further validation. Treatment with natalizumab and fingolimod showed different compartmental changes in protein levels of CSF and peripheral blood, respectively, including many disease-associated markers (e.g., IL12B, CD5) showing potential application for both diagnosing disease and monitoring treatment efficacy. We report a number of multiple sclerosis biomarkers in CSF and plasma for early disease detection and potential indicators for disease activity. Of particular importance is the set of markers discovered in blood, where validated biomarkers are lacking.

Increased urinary exosomal SYT17 levels in chronic active antibody-mediated rejection after kidney transplantation via the IL-6 amplifier

Chronic active antibody-mediated rejection (CAAMR) is a particular problem in kidney transplantation (KTx), and ~25% of grafts are lost by CAAMR. Further, the pathogenesis remains unclear, and there is no effective cure or marker. We previously found that a hyper NFκB-activating mechanism in non-immune cells, called the IL-6 amplifier, is induced by the co-activation of NFκB and STAT3, and that this activation can develop various chronic inflammatory diseases. Here, we show that synaptotagmin-17 (SYT17) is increased in an exosomal fraction of the urine from CAAMR patients, and that this increase is associated with activation of the IL-6 amplifier. Immunohistochemistry showed that SYT17 protein expression was increased in renal tubule cells of the CAAMR group. While SYT17 protein was not detectable in whole-urine samples by western blotting, urinary exosomal SYT17 levels were significantly elevated in the CAAMR group compared to three other histology groups (normal, interstitial fibrosis and tubular atrophy, and calcineurin inhibitors toxicity) after KTx. On the other hand, current clinical laboratory data could not differentiate the CAAMR group from these groups. These data suggest that urinary exosomal SYT17 is a potential diagnostic marker for CAAMR.

Neurons promote encephalitogenic CD4+ lymphocyte infiltration in experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system characterized by neuroinflammation, leading to demyelination and axonal degeneration. Neuronal excitotoxity mediated by Ca²⁺/calmodulin-dependent protein kinase IIα (CaMKIIα) results in neuronal damage in experimental autoimmune encephalitis (EAE), an animal model of MS. Here, we define a critical role of excitatory neurons in the pathogenesis of CD4⁺ lymphocyte accumulation in EAE. We silenced the activity of excitatory neurons in a mouse model of targeted EAE using inhibitory designer receptors exclusively activated by designer drugs (DREADD) under a CaMKIIα promoter. Neuronal silencing mitigated clinical disease scores in EAE, reduced the expression of c-fos, Tnfα, Ccl2, and Ccr2 mRNAs in targeted EAE lesions, and prevented the migration of CD4⁺ lymphocytes towards neurons. Ccl2 shRNA treatment of targeted EAE suppressed the migration of CD4⁺ lymphocytes and alleviated the motor deficits of EAE. Our findings indicate that neuronal activation in EAE promotes the migration of CCR2⁺ CD4⁺ lymphocytes and that neuronal silencing with an inhibitory DREADD alleviates clinical and molecular markers of disease. Neuronal CCL2 is thought to be involved in promoting lymphocytes migration.

Repeated stress induces a pro-inflammatory state, increases amygdala neuronal and microglial activation, and causes anxiety in adult male rats

A link exists between immune function and psychiatric conditions, particularly depressive and anxiety disorders. Psychological stress is a powerful trigger for these disorders and stress influences immune state. However, the nature of peripheral immune changes after stress conflicts across studies, perhaps due to the focus on few measures of pro-inflammatory or anti-inflammatory processes. The basolateral amygdala (BLA) is critical for emotion, and plays an important role in the effects of stress on anxiety. As such, it may be a primary central nervous system (CNS) mediator for the effects of peripheral immune changes on anxiety after stress. Therefore, this study aimed to delineate the influence of stress on peripheral pro-inflammatory and anti-inflammatory aspects, BLA immune activation, and its impact on BLA neuronal activity. To produce a more encompassing view of peripheral immune changes, this study used a less restrictive approach to categorize and group peripheral immune changes. We found that repeated social defeat stress in adult male Sprague-Dawley rats increased the frequencies of mature T-cells positive for intracellular type 2-like cytokine and serum pro-inflammatory cytokines. Principal component analysis and hierarchical clustering was used to guide grouping of T-cells and cytokines, producing unique profiles. Stress shifted the balance towards a specific set that included mostly type 2-like T-cells and pro-inflammatory cytokines. Within the CNS component, repeated stress caused an increase of activated microglia in the BLA, increased anxiety-like behaviors across several assays, and increased BLA neuronal firing in vivo that was prevented by blockade of microglia activation. Because repeated stress can trigger anxiety states by actions in the BLA, and altered immune function can trigger anxiety, these results suggest that repeated stress may trigger anxiety-like behaviors by inducing a pro-inflammatory state in the periphery and the BLA. These results begin to uncover how stress may recruit the immune system to alter the function of brain regions critical to emotion.

Neuroinflammation

Neuroinflammation is implicated in contributing to a variety of neurologic and somatic illnesses including Alzheimer's disease (AD), Parkinson's disease (PD), and depression. In this chapter, we focus on the role of neuroinflammation in mediating these three illnesses and portray interactions between the immune response and the central nervous system in the context of sex differences in disease progression. The majority of this chapter is supported by clinical findings; however, we occasionally utilize preclinical models where human studies are currently lacking. We begin by detailing the pathology of neuroinflammation, distinguishing between acute and chronic inflammation, and examining contributions from the innate and adaptive immune systems. Next, we summarize potential mechanisms of immune cell mediators including interleukin-1 beta (IL-1β), tumor necrosis factor α, and IL-6 in AD, PD, and depression development. Given the strong sex bias seen in these illnesses, we additionally examine the role of sex hormones, e.g., estrogen and testosterone in mediating neuroinflammation at the cellular level. Systematically, we detail how sex hormones may contribute to distinct behavioral and clinical symptoms and prognosis between males and females with AD, PD, or depression. Finally, we highlight the possible role of exercise in alleviating neuroinflammation, as well as evidence that antiinflammatory drug therapies improve cognitive symptoms observed in brain-related diseases.

Role of Regulatory T cells in Atorvastatin Induced Absorption of Chronic Subdural Hematoma in Rats

Chronic subdural hematoma (CSDH) is a neurological disorder with a substantial recurrence rate. Atorvastatin is an effective drug for treating hyperlipidemia and known to improve neurological outcome after intracerebral hemorrhage. Previous studies have reported that atorvastatin treatment promotes hematoma absorption in CSDH, while the underlying mechanisms remain unclear. In this study, we investigated whether the anti-inflammatory effects of atorvastatin mediate absorption of CSDH. 144 male, Wistar rats (6 months old) were randomly divided into the following groups: 1) sham surgery control, 2) treatment: CSDH + atorvastatin, and 3) vehicle control: CSDH + saline. Atorvastatin or saline was orally administered daily for 19 days after CSDH procedure. A T2WI MRI was used to evaluate CSDH volume changes during the time course of the study. Flow cytometry and immunohistochemical staining were used to measure the number of regulatory T cells (Treg). ELISA was used to measure cytokine level in the hematoma border. Neurological function and cognitive outcome were evaluated using Foot-Fault test and Morris Water Maze test, respectively. When compared to saline treatment, atorvastatin treatment accelerated the absorption of CSDH as indicated by decreased hematoma volume in T2WI MRI data on 14^th and 21^st day after CSDH (P<0.05). Atorvastatin treatment significantly increased the number of Treg in circulation and hematoma border from 3^rd to 21^st day after CSDH. Atorvastatin treatment significantly decreased the levels of interleukins (IL-6 and IL-8) and tumor necrosis factor-α (TNF-α), but increased IL-10 level in the hematoma border. Atorvastatin treatment also improved neurological function and cognitive outcome compared to vehicle treated group. Atorvastatin induced anti-inflammatory responses and increased Treg in circulation and brain which may contribute to the accelerated CSDH absorption in rats.

Neural stimulations regulate the infiltration of immune cells into the CNS

The systemic regulation of immune reactions by the nervous system is well studied and depends on the release of hormones. Some regional regulations of immune reactions, on the other hand, depend on specific neural pathways. Better understanding of these regulations will expand therapeutic applications for neuroimmune and organ-to-organ functional interactions. Here, we discuss one regional neuroimmune interaction, the gateway reflex, which converts specific neural inputs into local inflammatory outputs in the CNS. Neurotransmitters released by the inputs stimulate specific blood vessels to express chemokines, which serve as a gateway for immune cells to extravasate into the target organ such as the brain or spinal cord. Several types of gateway reflexes have been reported, and each controls distinct CNS blood vessels to form gateways that elicit local inflammation, particularly in the presence of autoreactive immune cells. For example, neural stimulation by gravity creates the initial entry point to the CNS by CNS-reactive pathogenic CD4+ T cells at the dorsal vessels of fifth lumbar spinal cord, while pain opens the gateway at the ventral side of blood vessels in the spinal cord. In addition, it was recently found that local inflammation by the gateway reflex in the brain triggers the activation of otherwise resting neural circuits to dysregulate organ functions in the periphery including the upper gastrointestinal tract and heart. Therefore, the gateway reflex represents a novel bidirectional neuroimmune interaction that regulates organ functions and could be a promising target for bioelectric medicine.

Neural activity regulates autoimmune diseases through the gateway reflex

The brain, spinal cord and retina are protected from blood-borne compounds by the blood-brain barrier (BBB), blood-spinal cord barrier (BSCB) and blood-retina barrier (BRB) respectively, which create a physical interface that tightly controls molecular and cellular transport. The mechanical and functional integrity of these unique structures between blood vessels and nervous tissues is critical for maintaining organ homeostasis. To preserve the stability of these barriers, interplay between constituent barrier cells, such as vascular endothelial cells, pericytes, glial cells and neurons, is required. When any of these cells are defective, the barrier can fail, allowing blood-borne compounds to encroach neural tissues and cause neuropathologies. Autoimmune diseases of the central nervous system (CNS) and retina are characterized by barrier disruption and the infiltration of activated immune cells. Here we review our recent findings on the role of neural activity in the regulation of these barriers at the vascular endothelial cell level in the promotion of or protection against the development of autoimmune diseases. We suggest nervous system reflexes, which we named gateway reflexes, are fundamentally involved in these diseases. Although their reflex arcs are not completely understood, we identified the activation of specific sensory neurons or receptor cells to which barrier endothelial cells respond as effectors that regulate gateways for immune cells to enter the nervous tissue. We explain this novel mechanism and describe its role in neuroinflammatory conditions, including models of multiple sclerosis and posterior autoimmune uveitis.

Mdivi-1, a mitochondrial fission inhibitor, modulates T helper cells and suppresses the development of experimental autoimmune encephalomyelitis

Background

Unrestrained activation of Th1 and Th17 cells is associated with the pathogenesis of multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE). While inactivation of dynamin-related protein 1 (Drp1), a GTPase that regulates mitochondrial fission, can reduce EAE severity by protecting myelin from demyelination, its effect on immune responses in EAE has not yet been studied.

Methods

We investigated the effect of Mdivi-1, a small molecule inhibitor of Drp1, on EAE. Clinical scores, inflammation, demyelination and Drp1 activation in the central nervous system (CNS), and T cell responses in both CNS and periphery were determined.

Results

Mdivi-1 effectively suppressed EAE severity by reducing demyelination and cellular infiltration in the CNS. Mdivi-1 treatment decreased the phosphorylation of Drp1 (ser616) on CD4⁺ T cells, reduced the numbers of Th1 and Th17 cells, and increased Foxp3⁺ regulatory T cells in the CNS. Moreover, Mdivi-1 treatment effectively inhibited IFN-γ⁺, IL-17⁺, and GM-CSF⁺ CD4⁺ T cells, while it induced CD4⁺ Foxp3⁺ regulatory T cells in splenocytes by flow cytometry.

Conclusions

Together, our results demonstrate that Mdivi-1 has therapeutic potential in EAE by modulating the balance between Th1/Th17 and regulatory T cells.

Imbalanced spinal infiltration of Th17/Treg cells contributes to bone cancer pain via promoting microglial activation

Increasing evidence suggests that T cells participate in the pathology of neuropathic pain, as well as the activation of microglia. However, whether T cells infiltrate into the spinal cord and contribute to the development of bone cancer pain (BCP) remains unknown. Here, we used a mouse model of BCP to show that numbers of T cells infiltrated into the spinal cord after sarcoma cell implantation with increased BCP, and most infiltrating T cells in the spinal cord were CD3⁺CD4⁺ T cells. Both Th17 and Treg subpopulations were analyzed by immunofluorescence. Treg cells in the spinal cord were transiently up-regulated, followed by an imbalance towards Th17 afterwards, and elevated IL-17/IL-17A levels were observed in both blood and spinal cord. Meanwhile, TGF-β, IL-6, and IL-23, the factors which regulate Th17/Treg differentiation, increased their expressions during the development of BCP. Additionally, IL-17A receptor (IL-17AR) was found to be expressed on microglia, and the level of IL-17AR increased with activated microglia during BCP development. Furthermore, BCP was ameliorated when IL-17/IL-17A neutralizing antibodies were intrathecally injected, accompanied with inhibited Th17/Treg infiltration and suppressed microglial activation. In conclusion, T cells infiltrated into the spinal cord with the imbalance of Th17/Treg towards Th17 during the development of BCP, which could promote the microglial activation and further increased BCP, while neutralizing IL-17/IL-17A in the spinal cord could ameliorate BCP. Our results suggest that targeting the imbalanced Th17/Treg infiltration in the spinal cord could be a novel strategy for BCP therapy.

Altered Gene Expression in Dioxin-Like and Non-Dioxin-Like PCB Exposed Peripheral Blood Mononuclear Cells

Polychlorinated biphenyls (PCBs) are well known carcinogenic persistent environmental pollutants and endocrine disruptors. Our aim was to identify the possible dysregulation of genes in PCB exposed peripheral blood mononuclear cells (PBMCs) in order to give more insight into the differential pathophysiological effects of PCB congeners and mixtures, with an emphasis on immunological effects and oxidative stress. The PBMCs of a healthy volunteer (male, 56 years old) were exposed to a mixture of dioxin-like (DL)-PCBs (PCB 77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169, and 189, 250 µg/L resp.) or non-dioxin-like (NDL)-PCBs (PCB 28, 52, 101, 138, 153, 180, 250 µg/L resp.) or single PCB congener (no.28, 138, 153, 180, 250 µg/L resp.). After an incubation period of 24 h, a microarray gene expression screening was performed, and the results were compared to gene expression in control samples (PBMCs treated with the vehicle iso-octane). Treatment of PBMCs with the DL-PCB mixture resulted in the largest number of differentially regulated genes (181 upregulated genes >2-fold, 173 downregulated >2-fold). Treatment with the NDL-PCB mix resulted in 32 upregulated genes >2-fold and 12 downregulated genes >2-fold. A gene set enrichment analysis (GSEA) on DL-PCB treated PBMCs resulted in an upregulation of 125 gene sets and a downregulation of 76 gene sets. Predominantly downregulated gene sets were involved in immunological pathways (such as response to virus, innate immune response, defense response). An upregulation of pathways related to oxidative stress could be observed for all PCB congeners except PCB-28; the latter congener dysregulated the least number of genes. Our experiment augments the information known about immunological and cellular stress responses following DL- as well as NDL-PCB exposure and provides new information on PCB 28. Further studies should be performed to evaluate how disruption of these pathways contributes to the development of autoimmune diseases and cancer.

Phosphorylation-dependent Regnase-1 release from endoplasmic reticulum is critical in IL-17 response

The endoribonuclease Regnase-1 suppresses inflammation through RNA degradation. Here, we show that Regnase-1 is phosphorylated and inactivated by the Act1-TBK1-IKKi axis during IL-17 stimulation. Moreover, this phosphorylation substantially contributes to the mRNA stabilization needed for amplification of TH17-cell–mediated inflammation.

Regnase-1 (also known as Zc3h12a or MCPIP-1) is an endoribonuclease involved in mRNA degradation of inflammation-associated genes. Regnase-1 is inactivated in response to external stimuli through post-translational modifications including phosphorylation, yet the precise role of phosphorylation remains unknown. Here, we demonstrate that interleukin (IL)-17 induces phosphorylation of Regnase-1 in an Act1-TBK1/IKKi–dependent manner, especially in nonhematopoietic cells. Phosphorylated Regnase-1 is released from the endoplasmic reticulum (ER) into the cytosol, thereby losing its mRNA degradation function, which leads to expression of IL-17 target genes. By using CRISPR/Cas-9 technology, we generated Regnase-1 mutant mice, in which IL-17–induced Regnase-1 phosphorylation is completely blocked. Mutant mice (Regnase-1^AA/AA and Regnase-1^ΔCTD/ΔCTD) were resistant to the IL-17–mediated inflammation caused by T helper 17 (Th17) cells in vivo. Thus, Regnase-1 plays a critical role in the development of IL-17–mediated inflammatory diseases via the Act1-TBK1-IKKi axis, and blockade of Regnase-1 phosphorylation sites may be promising for treatment of Th17-associated diseases.

The role of fatty acid binding protein 7 in spinal cord astrocytes in a mouse model of experimental autoimmune encephalomyelitis

Fatty acid binding protein 7 (FABP7) is expressed in astrocytes of the developing and mature central nervous system, and modulates astrocyte function by controlling intracellular fatty acid homeostasis. Astrocytes in the spinal cord have an important role in the process of myelin degeneration and regeneration. In the present study, the authors examined the role of FABP7 in astrocytes in a mouse model of experimental autoimmune encephalomyelitis (EAE), which is an established model of multiple sclerosis (MS). FABP7 was expressed in the white matter astrocytes and increased after EAE onset; particularly strong expression was observed in demyelinating regions. In FABP7-knockout (KO) mice, the onset of EAE symptoms occurred earlier than in wild type (WT) mice, and mRNA expression levels of inflammatory cytokines (IL-17 and TNF-α) were higher in FABP7-KO lumbar spinal cord than in WT lumbar spinal cord at early stage of EAE. Interestingly, however, the clinical score was significantly reduced in FABP7-KO mice compared with WT mice in the late phase of EAE. Moreover, the area exhibiting expression of fibronectin, which is an extracellular matrix protein mainly produced by astrocytes and inhibits remyelination of oligodendrocytes, was significantly decreased in FABP7-KO compared with WT mice. Collectively, FABP7 in astrocyte may have a role to protect from the induction of inflammation leading to demyelination in CNS at early phase of EAE. Moreover, FABP7 may be involved in the regulation of fibronectin production through the modification of astrocyte activation at late phase of EAE.

Schlafen-8 is essential for lymphatic endothelial cell activation in experimental autoimmune encephalomyelitis

Schlafen-8 (Slfn8) is a member of the Schlafen family of proteins, which harbor helicase domains and are induced by LPS and interferons. It has been reported that the Schlafen family are involved in various cellular functions, including proliferation, differentiation and regulation of virus replication. Slfn8 has been implicated in T-cell differentiation in the thymus. However, the roles of Slfn8 in the immune system remains unclear. In this study, we generated Slfn8 knockout mice (Slfn8-/-) and investigated the immunological role of Slfn8 using the T-cell-mediated autoimmune model experimental autoimmune encephalomyelitis (EAE). We found that the clinical score was reduced in Slfn8-/- mice. IL-6 and IL-17A cytokine production, which are associated with EAE onset and progression, were decreased in the lymph nodes of Slfn8-/- mice. Immune cell populations in Slfn8-/- mice, including macrophages, neutrophils, T cells and B cells, did not reveal significant differences compared with wild-type mice. In vitro activation of Slfn8-/- T cells in response to TCR stimulation also did not reveal significant differences. To confirm the involvement of non-hematopoietic cells, we isolated CD45- CD31+ endothelial cells and CD45-CD31- gp38+ fibroblastic reticular cells by FACS sorting. We showed that the levels of IL-6 and Slfn8 mRNA in CD45- CD31+ endothelial cells were increased after EAE induction. In contrast, the level of IL-6 mRNA after EAE induction was markedly decreased in CD31+ endothelial cells from Slfn8-/- mice. These results indicate that Slfn8 may play a role in EAE by regulating inflammation in endothelial cells.

Establishment of Novel Murine Model showing Vascular Inflammation-derived Cognitive Dysfunction

Inflammation is a critical feature of aging and its related diseases, including cardiovascular diseases. Recent epidemiological studies demonstrated that abdominal aortic aneurysm (AAA), an aging-related vascular pathological condition, is associated with cognitive decline. However, the underlying mechanism, especially the role of vascular inflammation, is largely unknown because of lack of an available animal model. In this study, we examined whether vascular inflammation affects synaptic and cognitive dysfunction, using an AAA mouse model. In young (3 months) and middle-aged (12 months) C57BL/6J mice, AAA was induced by angiotensin II infusion with calcium chloride application. After 4 weeks of induction, aortic diameter was significantly increased and excessive Mac3-positive inflammatory cells infiltrated the destroyed aorta in middle-aged mice. AAA-induced middle-aged mice further exhibited cognitive impairment. Neuronal loss was observed in the CA3 region of the hippocampus. IBA1/MHCII-double-positive microglia activation was also seen in the hippocampus, suggesting that vascular inflammation drives neuroinflammation and subsequent cognitive dysfunction. Furthermore, we found that senescence-accelerated mice prone 8 exhibited robust AAA formation and a marked decrease of cognitive and synaptic function in the hippocampus mediated by inflammation. In conclusion, this novel murine model convincingly suggested the occurrence of vascular inflammation-derived cognitive dysfunction.

Photopic light-mediated down-regulation of local α1A-adrenergic signaling protects blood-retina barrier in experimental autoimmune uveoretinitis

We have reported the gateway reflex, which describes specific neural activations that regulate immune cell gateways at specific blood vessels in the central nervous system (CNS). Four types of gateway reflexes exist, all of which induce alterations in endothelial cells at specific vessels of the blood-brain barrier followed by inflammation in the CNS in the presence of CNS-autoreactive T cells. Here we report a new gateway reflex that suppresses the development of retinal inflammation by using an autoreactive T cell-mediated ocular inflammation model. Exposure to photopic light down-regulated the adrenoceptor pathway to attenuate ocular inflammation by suppressing breaching of the blood-retina barrier. Mechanistic analysis showed that exposure to photopic light down-regulates the expression of α_1A-adrenoceptor (α_1AAR) due to high levels of norepinephrine and epinephrine, subsequently suppressing inflammation. Surgical ablation of the superior cervical ganglion (SCG) did not negate the protective effect of photopic light, suggesting the involvement of retinal noradrenergic neurons rather than sympathetic neurons from the SCG. Blockade of α_1AAR signaling under mesopic light recapitulated the protective effect of photopic light. Thus, targeting regional adrenoceptor signaling might represent a novel therapeutic strategy for autoimmune diseases including those that affect organs separated by barriers such as the CNS and eyes.

Microglia pre-activation and neurodegeneration precipitate neuroinflammation without exacerbating tissue injury in experimental autoimmune encephalomyelitis

Human inflammatory or neurodegenerative diseases, such as progressive multiple sclerosis (MS), occur on a background of age-related microglia activation and iron accumulation as well as pre-existing neurodegeneration. Most experimental models for CNS diseases, however, are induced in rodents, which are naturally characterized by a homeostatic microglia phenotype, low cellular iron load and absence of neurodegeneration. Here, we show that naïve LEWzizi rats – Lewis rats with a zitter rat background – show a spontaneous phenotype partly mimicking the changes seen in human aging and particularly in the normal-appearing white and grey matter of patients with progressive MS. Using this model system, we further aimed to investigate (i) whether the acute monophasic MS model experimental autoimmune encephalomyelitis (EAE) transforms into chronic progressive disease and (ii) whether EAE-induced neuroinflammation and tissue damage aggravate on the LEWzizi background. We found that the pre-existing LEWzizi-specific pathology precipitated EAE-related neuroinflammation into forebrain areas, which are devoid of EAE lesions in normal Lewis rats. However, EAE-related tissue damage was neither modified by the LEWzizi-specific pathology nor did EAE-induced neuroinflammation modify the LEWzizi-related pathological process. Our data indicate that the interaction between pre-activated microglia and CD4⁺ autoreactive T cells during the induction and propagation of tissue damage in the CNS is limited.

Neuroinflammation and B-Cell Phenotypes in Cervical and Lumbosacral Regions of the Spinal Cord in Experimental Autoimmune Encephalomyelitis in the Absence of Pertussis Toxin

OBJECTIVES

The active experimental autoimmune encephalomyelitis (EAE) model is often initiated using myelin oligodendrocyte glycoprotein (MOG) immunization followed by pertussis toxin (PTX) to study multiple sclerosis. However, PTX inactivates G protein-coupled receptors, and with increasing knowledge of the role that various G protein-coupled receptors play in immune homeostasis, it is valuable to establish neuroimmune endpoints for active EAE without PTX.

METHODS

Female C57BL/6 mice were immunized with MOG35-55 peptide in Complete Freund's Adjuvant and neuroinflammation, including central nervous system B-cell infiltration, was compared to saline-injected mice. Since it was anticipated that disease onset would be slower and less robust than EAE in the presence of PTX, both cervical and lumbosacral sections of the spinal cord were evaluated.

RESULTS

Immunohistochemical analysis showed that EAE without PTX induced immune infiltration, CCL2 and VCAM-1 upregulation. Demyelination in the cervical region correlated with the infiltration of CD19+ B cells in the cervical region. There was upregulation of IgG, CD38, and PDL1 on B cells in cervical and lumbosacral regions of the spinal cord in EAE without PTX. Interestingly, IgG was expressed predominantly by CD19- cells.

CONCLUSIONS

These data demonstrate that many neuroimmune endpoints are induced in EAE without PTX and although clinical disease is mild, this can be used as an autoimmune model when PTX inactivation of G protein-coupled receptors is not desired.

Systematic Understanding of Bioactive Lipids in Neuro-Immune Interactions: Lessons from an Animal Model of Multiple Sclerosis

Bioactive lipids, or lipid mediators, are utilized for intercellular communications. They are rapidly produced in response to various stimuli and exported to extracellular spaces followed by binding to cell surface G protein-coupled receptors (GPCRs) or nuclear receptors. Many drugs targeting lipid signaling such as non-steroidal anti-inflammatory drugs (NSAIDs), prostaglandins, and antagonists for lipid GPCRs are in use. For example, the sphingolipid analog, fingolimod (also known as FTY720), was the first oral disease-modifying therapy (DMT) for relapsing-remitting multiple sclerosis (MS), whose mechanisms of action (MOA) includes sequestration of pathogenic lymphocytes into secondary lymphoid organs, as well as astrocytic modulation, via down-regulation of the sphingosine 1-phosphate (S1P) receptor, S1P₁, by in vivo-phosphorylated fingolimod. Though the cause of MS is still under debate, MS is considered to be an autoimmune demyelinating and neurodegenerative disease. This review summarizes the involvement of bioactive lipids (prostaglandins, leukotrienes, platelet-activating factors, lysophosphatidic acid, and S1P) in MS and the animal model, experimental autoimmune encephalomyelitis (EAE). Genetic ablation, along with pharmacological inhibition, of lipid metabolic enzymes and lipid GPCRs revealed that each bioactive lipid has a unique role in regulating immune and neural functions, including helper T cell (T_H1 and T_H17) differentiation and proliferation, immune cell migration, astrocyte responses, endothelium function, and microglial phagocytosis. A systematic understanding of bioactive lipids in MS and EAE dredges up information about understudied lipid signaling pathways, which should be clarified in the near future to better understand MS pathology and to develop novel DMTs.

Gateway reflex: Local neuroimmune interactions that regulate blood vessels

Neuroimmunology is a research field that intersects neuroscience and immunology, with the larger aim of gaining significant insights into the pathophysiology of chronic inflammatory diseases such as multiple sclerosis. Conventional studies in this field have so far mainly dealt with immune responses in the nervous system (i.e. neuroinflammation) or systemic immune regulation by the release of glucocorticoids. On the other hand, recently accumulating evidence has indicated bidirectional interactions between specific neural activations and local immune responses. Here we discuss one such local neuroimmune interaction, the gateway reflex. The gateway reflex represents a mechanism that translates specific neural stimulations into local inflammatory outcomes by changing the state of specific blood vessels to allow immune cells to extravasate, thus forming the gateway. Several types of gateway reflex have been identified, and each regulates distinct blood vessels to create gateways for immune cells that induce local inflammation. The gateway reflex represents a novel therapeutic strategy for neuroinflammation and is potentially applicable to other inflammatory diseases in peripheral organs.

PDGFRβ Cells Rapidly Relay Inflammatory Signal from the Circulatory System to Neurons via Chemokine CCL2

Acute infection, if not kept in check, can lead to systemic inflammatory responses in the brain. Here, we show that within 2 hr of systemic inflammation, PDGFRβ mural cells of blood vessels rapidly secrete chemokine CCL2, which in turn increases total neuronal excitability by promoting excitatory synaptic transmission in glutamatergic neurons of multiple brain regions. By single-cell RNA sequencing, we identified Col1a1 and Rgs5 subgroups of PDGFRβ cells as the main source of CCL2. Lipopolysaccharide (LPS)- or Poly(I:C)-treated pericyte culture medium induced similar effects in a CCL2-dependent manner. Importantly, in Pdgfrb-Cre;Ccl2^fl/fl mice, LPS-induced increase in excitatory synaptic transmission was significantly attenuated. These results demonstrate in vivo that PDGFRβ cells function as initial sensors of external insults by secreting CCL2, which relays the signal to the central nervous system. Through their gateway position in the brain, PDGFRβ cells are ideally positioned to respond rapidly to environmental changes and to coordinate responses.

Interleukin-17-producing γδ T (γδ17) cells in inflammatory diseases

Interleukin‐17 (IL‐17) is a pro‐inflammatory cytokine and is involved in the development of many diseases. Recent studies have revealed that IL‐17‐producing γδ T cells (γδ17 cells) in addition to IL‐17‐producing CD4⁺ T cells [T helper type 17 (Th17) cells] are often the main producers of IL‐17 in mouse models of inflammatory diseases. γδ T cells are functionally committed during intra‐thymic differentiation. γδ thymocytes capable of producing IL‐17, which express the transcription factor retinoic‐acid‐receptor‐related orphan receptor γt and the signature cytokine receptor IL‐23R, leave the thymus, and produce IL‐17 rapidly by the stimulation with IL‐1β and IL‐23 in the periphery. Therefore, γδ17 cells play important roles in the early phase of host defence against pathogens and in inflammatory diseases. γδ T cells that can produce IL‐17 are also increased in the skin of patients with psoriasis and in peripheral blood of patients with ankylosing sclerosis. Indeed, the therapy targeting IL‐17 has been approved or is in clinical trials, and proved to be very efficient to treat psoriasis, psoriatic arthritis and ankylosing sclerosis. In this review, we discuss recent knowledge about the pathophysiological function of γδ17 cells in infection and inflammatory diseases and therapeutic advances targeting IL‐17.

Presenilin 1 Regulates NF-κB Activation via Association with Breakpoint Cluster Region and Casein Kinase II

We recently reported that NF-κB-mediated inflammation caused by breakpoint cluster region (BCR) is dependent on the α subunit of casein kinase II (CK2α) complex. In the current study, we demonstrate that presenilin 1 (Psen1), which is a catalytic component of the γ-secretase complex and the mutations of which are known to cause familial Alzheimer disease, acts as a scaffold of the BCR-CK2α-p65 complex to induce NF-κB activation. Indeed, Psen1 deficiency in mouse endothelial cells showed a significant reduction of NF-κB p65 recruitment to target gene promoters. Conversely, Psen1 overexpression enhanced reporter activation under NF-κB responsive elements and IL-6 promoter. Furthermore, the transcription of NF-κB target genes was not inhibited by a γ-secretase inhibitor, suggesting that Psen1 regulates NF-κB activation in a manner independent of γ-secretase activity. Mechanistically, Psen1 associated with the BCR-CK2α complex, which is required for phosphorylation of p65 at serine 529. Consistently, TNF-α-induced phosphorylation of p65 at serine 529 was significantly decreased in Psen1-deficient cells. The association of the BCR-CK2α-p65 complex was perturbed in the absence of Psen1. These results suggest that Psen1 functions as a scaffold of the BCR-CK2α-p65 complex and that this signaling cascade could be a novel therapeutic target for various chronic inflammation conditions, including those in Alzheimer disease.

Cell- and stage-specific localization of galectin-3, a β-galactoside-binding lectin, in a mouse model of experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is an autoimmune disease in which pathogenic T cells play an important role, and an experimental autoimmune encephalomyelitis (EAE) is used as an animal model of MS. Galectins are β-galactoside-binding lectins and involved in various physiological and pathological events. Among fifteen members of galectins, galectin-1, -8, and -9 play immunosuppressive roles in MS and EAE; however, the role of galectin-3 (gal-3) is complex and controversial. We examined expression of gal-3 in the spinal cord and nerve roots of EAE mice. No immunohistochemical signals were detected in naïve mice, whereas gal-3 appeared at lower lumbar levels of the spinal cord and nerve roots in EAE mice. In the spinal cord, gal-3-positive cells were activated microglia and/or infiltrating macrophages, which were round in shape and intensified for the lysosomal enzyme, cathepsin D, indicating elevated phagocytic activity. Gal-3-positive cells in the spinal cord were most abundant during the peak symptomatic period. In the recovery period, they disappeared from the spinal parenchyma but remained at moderate levels in the pia mater. Interestingly, gal-3-positive cells selectively appeared in ventral, but not dorsal, nerve roots running through the spinal canal, with expression peaking during the recovery period. In ventral nerve roots, the major cell type expressing gal-3 was a specific population of Schwann cells that surround unmyelinated axons and express the biosynthetic enzyme for l-serine, a potent neurotrophic amino acid. Gal-3 was also induced in Iba1/F4/80-positive macrophages, which engulf damaged myelin and axon debris. Thus, gal-3 is induced in distinct cell types that are engaged in removal of damaged axons and cell debris and axon regeneration and remyelination, suggesting a potential neuroprotective role of gal-3 in EAE mice.

Easy sectioning of whole grain of rice using cryomicrotome

To obtain a clear intact section of a ripened rice grain, which is suitable for biochemical and histological analysis, the Kawamoto method using a specific adhesive film was applied using a cryomicrotome. The longitudinal and sagittal sections were easily obtained together with the cross-section, and cell characteristics were clearly discerned in the ripened grain. It was demonstrated that the Kawamoto method is readily applicable for intact sectioning of hard tissue, including ripened grain. Intact section sampling may be useful for enzymatic analysis and transcriptomic analysis of plant tissue.

Molecular and Functional Neuroscience in Immunity

The nervous system regulates immunity and inflammation. The molecular detection of pathogen fragments, cytokines, and other immune molecules by sensory neurons generates immunoregulatory responses through efferent autonomic neuron signaling. The functional organization of this neural control is based on principles of reflex regulation. Reflexes involving the vagus nerve and other nerves have been therapeutically explored in models of inflammatory and autoimmune conditions, and recently in clinical settings. The brain integrates neuro-immune communication, and brain function is altered in diseases characterized by peripheral immune dysregulation and inflammation. Here we review the anatomical and molecular basis of the neural interface with immunity, focusing on peripheral neural control of immune functions and the role of the brain in the model of the immunological homunculus. Clinical advances stemming from this knowledge within the framework of bioelectronic medicine are also briefly outlined.

Obesity exacerbates colitis-associated cancer via IL-6-regulated macrophage polarisation and CCL-20/CCR-6-mediated lymphocyte recruitment

Colorectal cancer (CRC) is one of the most lethal cancers worldwide in which the vast majority of cases exhibit little genetic risk but are associated with a sedentary lifestyle and obesity. Although the mechanisms underlying CRC and colitis-associated colorectal cancer (CAC) remain unclear, we hypothesised that obesity-induced inflammation predisposes to CAC development. Here, we show that diet-induced obesity accelerates chemically-induced CAC in mice via increased inflammation and immune cell recruitment. Obesity-induced interleukin-6 (IL-6) shifts macrophage polarisation towards tumour-promoting macrophages that produce the chemokine CC-chemokine-ligand-20 (CCL-20) in the CAC microenvironment. CCL-20 promotes CAC progression by recruiting CC-chemokine-receptor-6 (CCR-6)-expressing B cells and γδ T cells via chemotaxis. Compromised cell recruitment as well as inhibition of B and γδ T cells protects against CAC progression. Collectively, our data reveal a function for IL-6 in the CAC microenvironment via lymphocyte recruitment through the CCL-20/CCR-6 axis, thereby implicating a potential therapeutic intervention for human patients.

Inflammation can be induced by obesity, and has been linked with onset of colorectal cancer (CAC). Here the authors show in mouse models that obesity-induced interleukin-6 alters macrophage function to enhance CCL-20/CCR-6-mediated recruitment of B cells and γδ T cells, thereby promoting gut inflammation and CAC progression.

TNF-α-sensitive brain pericytes activate microglia by releasing IL-6 through cooperation between IκB-NFκB and JAK-STAT3 pathways

Interleukin (IL)-6 is an important mediator of neurovascular dysfunction, neurodegeneration and/or neuroinflammation. We previously reported that brain pericytes released higher levels of IL-6 than did glial cells (astrocytes and microglia) in response to tumor necrosis factor (TNF)-α. Moreover, pericytes stimulated with TNF-α enhanced activation of BV-2 microglia. In this study, we investigated the mechanisms of TNF-α mediated induction of IL-6 release from brain pericytes and astrocytes and whether pericyte-derived IL-6 would facilitate activation of BV-2 microglia. Using rat brain pericyte and astrocyte primary cultures and pharmacological inhibitors, we found that, TNF-α induced the highest levels of IL-6 release from pericytes by activating the inhibitor kappa B (IκB)-nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) and Janus family of tyrosine kinase (JAK)-signal transducer and activator of transcription (STAT)3 pathways. STAT3 contributed to TNF-α induced nuclear translocation of phospho-NFκB in pericytes. TNF-α-induced IL-6 release in astrocytes was mediated by NFκB but not by STAT3. The presence of pericytes amplified TNF-α-induced iNOS mRNA expression in BV-2 microglia. This effect was blocked by a neutralizing antibody for IL-6. These findings indicated that crosstalk between the IκB-NFκB and JAK-STAT3 pathways is a pericyte specific mechanism, not occurring in astrocytes, for TNF-α-induced IL-6 release. IL-6 derived from pericytes enhanced microglial activation. Our findings increase understanding of the role of pericyte-microglia crosstalk in the brain under neuroinflammatory conditions and suggest a potentially attractive therapeutic target for brain inflammation.

Redirecting adult mesenchymal stromal cells to the brain: a new approach for treating CNS autoimmunity and neuroinflammation?

Mesenchymal stromal cells or stem cells (MSCs) have been shown to participate in tissue repair and are immunomodulatory in neuropathological settings. Given this, their potential use in developing a new generation of personalized therapies for autoimmune and inflammatory diseases of the central nervous system (CNS) will be explored. To effectively exert these effector functions, MSCs must first gain entry into damaged neural tissues, a process that has been demonstrated to be a limiting factor in their therapeutic efficacy. In this review, we discuss approaches to maximize the therapeutic efficacy of MSCs by altering their intrinsic trafficking programs to effectively enter neuropathological sites. To this end, we explore the significant role of chemokine receptors and adhesion molecules in directing cellular traffic to the inflamed CNS and the capacity of MSCs to adopt these molecular mechanisms to gain entry to this site. We postulate that understanding and exploiting these migratory mechanisms may be key to the development of cell-based therapies tailored to respond to the migratory cues unique to the nature and stage of progression of individual CNS disorders.