Cytokines and Chemokines in the Pathogenesis of Experimental Autoimmune Encephalomyelitis

The brain cytokine orchestra in multiple sclerosis: from neuroinflammation to synaptopathology

The central nervous system (CNS) is finely protected by the blood-brain barrier (BBB). Immune soluble factors such as cytokines (CKs) are normally produced in the CNS, contributing to physiological immunosurveillance and homeostatic synaptic scaling. CKs are peptide, pleiotropic molecules involved in a broad range of cellular functions, with a pivotal role in resolving the inflammation and promoting tissue healing. However, pro-inflammatory CKs can exert a detrimental effect in pathological conditions, spreading the damage. In the inflamed CNS, CKs recruit immune cells, stimulate the local production of other inflammatory mediators, and promote synaptic dysfunction. Our understanding of neuroinflammation in humans owes much to the study of multiple sclerosis (MS), the most common autoimmune and demyelinating disease, in which autoreactive T cells migrate from the periphery to the CNS after the encounter with a still unknown antigen. CNS-infiltrating T cells produce pro-inflammatory CKs that aggravate local demyelination and neurodegeneration. This review aims to recapitulate the state of the art about CKs role in the healthy and inflamed CNS, with focus on recent advances bridging the study of adaptive immune system and neurophysiology.

CCDC88B interacts with RASAL3 and ARHGEF2 and regulates dendritic cell function in neuroinflammation and colitis

CCDC88B is a risk factor for several chronic inflammatory diseases in humans and its inactivation causes a migratory defect in DCs in mice. CCDC88B belongs to a family of cytoskeleton-associated scaffold proteins that feature protein:protein interaction domains. Here, we identified the Rho/Rac Guanine Nucleotide Exchange Factor 2 (ARHGEF2) and the RAS Protein Activator Like 3 (RASAL3) as CCDC88B physical and functional interactors. Mice defective in Arhgef2 or Rasal3 show dampened neuroinflammation, and display altered cellular response and susceptibility to colitis; ARHGEF2 maps to a human Chromosome 1 locus associated with susceptibility to IBD. Arhgef2 and Rasal3 mutant DCs show altered migration and motility in vitro, causing either reduced (Arhgef2) or enhanced (Rasal3) migratory properties. The CCDC88B/RASAL3/ARHGEF2 complex appears to regulate DCs migration by modulating activation of RHOA, with ARHGEF2 and RASAL3 acting in opposite regulatory fashions, providing a molecular mechanism for the involvement of these proteins in DCs immune functions.

Novel nano-carriers with N-formylmethionyl-leucyl-phenylalanine-modified liposomes improve effects of C16-angiopoietin 1 in acute animal model of multiple sclerosis

Gradual loss of neuronal structure and function due to impaired blood-brain barrier (BBB) and neuroinflammation are important factors in multiple sclerosis (MS) progression. Our previous studies demonstrated that the C16 peptide and angiopoietin 1 (Ang-1) compound (C + A) could modulate inflammation and vascular protection in many models of MS. In this study, nanotechnology and a novel nanovector of the leukocyte chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP) were used to examine the effects of C + A on MS. The acute experimental autoimmune encephalomyelitis (EAE) model of MS was established in Lewis rats. The C + A compounds were conjugated to control nano-carriers and fMLP-nano-carriers and administered to animals by intravenous injection. The neuropathological changes in the brain cortex and spinal cord were examined using multiple approaches. The stimulation of vascular injection sites was examined using rabbits. The results showed that all C + A compounds (C + A alone, nano-carrier C + A, and fMLP-nano-carrier C + A) reduced neuronal inflammation, axonal demyelination, gliosis, neuronal apoptosis, vascular leakage, and BBB impairment induced by EAE. In addition, the C + A compounds had minimal side effects on liver and kidney functions. Furthermore, the fMLP-nano-carrier C + A compound had better effects compared to C + A alone and the nano-carrier C + A. This study indicated that the fMLP-nano-carrier C + A could attenuate inflammation-related pathological changes in EAE and may be a potential therapeutic strategy for the treatment of MS and EAE.

Hydroxyfasudil regulates immune balance and suppresses inflammatory responses in the treatment of experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a central nervous system (CNS) disease with complicated etiology. Multifocal demyelination and invasion of inflammatory cells are its primary pathological features. Fasudil has been confirmed to improve experimental autoimmune encephalomyelitis (EAE), an animal model of MS. However, Fasudil is accompanied by several shortcomings in the clinical practice. Hydroxyfasudil is a metabolite of Fasudil in the body with better pharmaceutical properties. Therefore, we attempted to study the influence of Hydroxyfasudil upon EAE mice. The results demonstrated that Hydroxyfasudil relieved the symptoms of EAE and the associated pathological damage, reduced the adhesion molecules and chemokines, decreased the invasion of peripheral immune cells. Simultaneously, Hydroxyfasudil modified the rebalance of peripheral T cells. Moreover, Hydroxyfasudil shifted the M1 phenotype to M2 polarization, inhibited inflammatory signaling cascades as well as inflammatory factors, and promoted anti-inflammatory factors in the CNS. In the end, mice in the Hydroxyfasudil group expressed more tight junction proteins, indirectly indicating that the blood-brain barrier (BBB) was protected. Our results indicate that Hydroxyfasudil may be a prospective treatment for MS.

Fc multimers effectively treat murine models of multiple sclerosis

Multiple Sclerosis (MS) is a chronic neurodegenerative disease with limited therapeutic options. Recombinant Fc multimers (rFc), designed to mirror many of the anti-inflammatory activities of Intravenous Immunoglobulin (IVIG), have been shown to effectively treat numerous immune-mediated diseases in rodents. In this study we used the experimental autoimmune encephalomyelitis (EAE) murine model of MS to test the efficacy of a rFc, M019, that consists of multimers of the Fc portion of IgG2, in inhibiting disease severity. We show that M019 effectively reduced clinical symptoms when given either pre- or post-symptom onset compared to vehicle treated EAE induced mice. M019 was effective in reducing symptoms in both SJL model of relapsing remitting MS as well as the B6 model of chronic disease. M019 binds to FcγR bearing-monocytes both in vivo and in vitro and prevented immune cell infiltration into the CNS of treated mice. The lack of T cell infiltration into the spinal cord was not due to a decrease in T cell priming; there was an equivalent frequency of Th17 cells in the spleens of M019 and vehicle treated EAE induced mice. Surprisingly, there was an increase in chemokines in the sera but not in the CNS of M019 treated mice compared to vehicle treated animals. We postulate that M019 interacts with a FcγR rich monocyte intermediary to prevent T cell migration into the CNS and demyelination.

Microglial expression of CD83 governs cellular activation and restrains neuroinflammation in experimental autoimmune encephalomyelitis

Microglial activation during neuroinflammation is crucial for coordinating the immune response against neuronal tissue, and the initial response of microglia determines the severity of neuro-inflammatory diseases. The CD83 molecule has been recently shown to modulate the activation status of dendritic cells and macrophages. Although the expression of CD83 is associated with early microglia activation in various disease settings, its functional relevance for microglial biology has been elusive. Here, we describe a thorough assessment of CD83 regulation in microglia and show that CD83 expression in murine microglia is not only associated with cellular activation but also with pro-resolving functions. Using single-cell RNA-sequencing, we reveal that conditional deletion of CD83 results in an over-activated state during neuroinflammation in the experimental autoimmune encephalomyelitis model. Subsequently, CD83-deficient microglia recruit more pathogenic immune cells to the central nervous system, deteriorating resolving mechanisms and exacerbating the disease. Thus, CD83 in murine microglia orchestrates cellular activation and, consequently, also the resolution of neuroinflammation.

Gut microbiome-modulated dietary strategies in EAE and multiple sclerosis

Over the last few decades, the incidence of multiple sclerosis has increased as society's dietary habits have switched from a whole foods approach to a high fat, high salt, low dietary fiber, and processed food diet, termed the "Western diet." Environmental factors, such as diet, could play a role in the pathogenesis of multiple sclerosis due to gut microbiota alterations, gut barrier leakage, and subsequent intestinal inflammation that could lead to exacerbated neuroinflammation. This mini-review explores the gut microbiome alterations of various dietary strategies that improve upon the "Western diet" as promising alternatives and targets to current multiple sclerosis treatments. We also provide evidence that gut microbiome modulation through diet can improve or exacerbate clinical symptoms of multiple sclerosis, highlighting the importance of including gut microbiome analyses in future studies of diet and disease.

COVID-19 and Multiple Sclerosis: A Complex Relationship Possibly Aggravated by Low Vitamin D Levels

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an exceptionally transmissible and pathogenic coronavirus that appeared at the end of 2019 and triggered a pandemic of acute respiratory disease, known as coronavirus disease 2019 (COVID-19). COVID-19 can evolve into a severe disease associated with immediate and delayed sequelae in different organs, including the central nervous system (CNS). A topic that deserves attention in this context is the complex relationship between SARS-CoV-2 infection and multiple sclerosis (MS). Here, we initially described the clinical and immunopathogenic characteristics of these two illnesses, accentuating the fact that COVID-19 can, in defined patients, reach the CNS, the target tissue of the MS autoimmune process. The well-known contribution of viral agents such as the Epstein-Barr virus and the postulated participation of SARS-CoV-2 as a risk factor for the triggering or worsening of MS are then described. We emphasize the contribution of vitamin D in this scenario, considering its relevance in the susceptibility, severity and control of both pathologies. Finally, we discuss the experimental animal models that could be explored to better understand the complex interplay of these two diseases, including the possible use of vitamin D as an adjunct immunomodulator to treat them.

Phenethyl Ester of Gallic Acid Ameliorates Experimental Autoimmune Encephalomyelitis

Gallic acid is a phenolic acid present in various plants, nuts, and fruits. It is well known for its anti-oxidative and anti-inflammatory properties. The phenethyl ester of gallic acid (PEGA) was synthesized with the aim of increasing the bioavailability of gallic acid, and thus its pharmacological potential. Here, the effects of PEGA on encephalitogenic cells were examined, and PEGA was found to modulate the inflammatory activities of T cells and macrophages/microglia. Specifically, PEGA reduced the release of interleukin (IL)-17 and interferon (IFN)-γ from T cells, as well as NO, and IL-6 from macrophages/microglia. Importantly, PEGA ameliorated experimental autoimmune encephalomyelitis, an animal model of chronic inflammatory disease of the central nervous system (CNS)-multiple sclerosis. Thus, PEGA is a potent anti-inflammatory compound with a perspective to be further explored in the context of CNS autoimmunity and other chronic inflammatory disorders.

Neuro-immune interactions at single-cell resolution in neurodevelopmental, infectious, and neurodegenerative diseases

Recent technological advance in single-cell and single-nucleus transcriptomics has made it possible to generate an unprecedentedly detailed landscape of neuro-immune interactions in healthy and diseased brains. In this review, we overview the recent literature that catalogs single-cell-level gene expression in brains with signs of inflammation, focusing on maternal immune activation, viral infection, and auto-immune diseases. The literature also includes a series of papers that provide strong evidence for immunological contributions to neurodegenerative diseases, which, in a strict sense, are not considered neuroinflammatory. To help with the discussion, we present a diagram of experimental and analytical flows in the single-cell analysis of the brain. We also discuss the recurring themes of neuro-immune interactions and suggest future research directions.

"Near Cure" treatment of severe acute EAE in MIF-1-deficient female and male mice with a bifunctional MHCII-derived molecular construct

Our previous studies demonstrated increased serum levels of macrophage migration inhibitory factor (MIF-1) and its homologue, MIF-2, in males during MS progression; and that genetically high-MIF-expressing male subjects with relapsing multiple sclerosis (MS) had a significantly greater risk of conversion to progressive MS than lower-MIF-expressing males and females. However, female MS subjects with severe disease expressed higher levels of CD74, the common MIF-1/MIF-2 receptor, on blood cells. In the murine model of MS, experimental autoimmune encephalomyelitis (EAE), both male and female mice lacking MIF-1 and/or MIF-2 were clinically improved during development of moderately severe disease, thus implicating both homologs as co-pathogenic contributors. The current study using MIF-deficient mice with severe acute EAE revealed a highly significant reduction of EAE scores in MIF-1-deficient females, in contrast to only minor and delayed reduction of clinical signs in MIF-1-deficient males. However, clinical EAE scores and factor expression were strongly suppressed in males and further reduced in females after treatment of WT and MIF-1-, MIF-2- and MIF-1/2-DUAL-deficient female and male mice with a MHCII DRα1-MOG-35-55 molecular construct that competitively inhibits MIF-1 & MIF-2 signaling through CD74 as well as T cell activation. These results suggest sex-dependent differences in which the absence of the MIF-1 and/or MIF-2 genotypes may permit stronger compensatory CD74-dependent EAE-inducing responses in males than in females. However, EAE severity in both sexes could still be reduced nearly to background (a "near cure") with DRα1-MOG-35-55 blockade of compensatory MIF and CD74-dependent factors known to attract peripheral inflammatory cells into the spinal cord tissue.

Helminthic dehydrogenase drives PGE2 and IL-10 production in monocytes to potentiate Treg induction

Immunoregulation of inflammatory, infection‐triggered processes in the brain constitutes a central mechanism to control devastating disease manifestations such as epilepsy. Observational studies implicate the viability of Taenia solium cysts as key factor determining severity of neurocysticercosis (NCC), the most common cause of epilepsy, especially in children, in Sub‐Saharan Africa. Viable, in contrast to decaying, cysts mostly remain clinically silent by yet unknown mechanisms, potentially involving Tregs in controlling inflammation. Here, we show that glutamate dehydrogenase from viable cysts instructs tolerogenic monocytes to release IL‐10 and the lipid mediator PGE₂. These act in concert, converting naive CD4⁺ T cells into CD127⁻CD25^hiFoxP3⁺CTLA‐4⁺ Tregs, through the G protein‐coupled receptors EP2 and EP4 and the IL‐10 receptor. Moreover, while viable cyst products strongly upregulate IL‐10 and PGE₂ transcription in microglia, intravesicular fluid, released during cyst decay, induces pro‐inflammatory microglia and TGF‐β as potential drivers of epilepsy. Inhibition of PGE₂ synthesis and IL‐10 signaling prevents Treg induction by viable cyst products. Harnessing the PGE₂‐IL‐10 axis and targeting TGF‐ß signaling may offer an important therapeutic strategy in inflammatory epilepsy and NCC.

Is there a window of opportunity for the therapeutic use of vitamin D in multiple sclerosis?

Multiple sclerosis is an autoimmune treatable but not curable disease. There are a multiplicity of medications for multiple sclerosis therapy, including a class entitled disease-modifying drugs that are mainly indicated to reduce the number and severity of disease relapses. Not all patients respond well to these therapies, and minor to severe adverse effects have been reported. Vitamin D, called sunshine vitamin, is being studied as a possible light at the end of the tunnel. In this review, we recapitulated the similar immunopathogenesis of multiple sclerosis and experimental autoimmune encephalomyelitis, the immunomodulatory and neuroprotective potential of vitamin D and the state-of-art concerning its supplementation to multiple sclerosis patients. Finally, based on our and other groups’ experimental findings, we analyzed the need to consider the relevance of the route and the different time-point administration aspects for a more rational indication of this vitamin to multiple sclerosis patients.

Therapeutic Potential of Combined Therapy of Vitamin A and Vitamin C in the Experimental Autoimmune Encephalomyelitis (EAE) in Lewis Rats

Demyelination, inflammation, oxidative injury, and glial activation are the main pathological hallmarks of multiple sclerosis (MS). Vitamins, as essential micronutrients, seem to be crucial in the pathogenesis of MS, and particularly vitamins A and C were found to have a protective role in MS development or progression. In this study, the therapeutic potential of combined therapy of vitamins A and C on progression of experimental autoimmune encephalomyelitis (EAE) and myelin repair mechanisms was examined. EAE, an animal model of MS, was induced in female Lewis rats. The rats were treated with daily intraperitoneal injections of vitamins A and C and their combination. We found that co-supplementation of vitamins A and C mitigated neurological severity and EAE disease progression. Histological study confirmed a significant reduction in demyelination size, inflammation and immune cell infiltration as well as microglia and astrocyte activation following co-administration of vitamins A and C. Co-administration of vitamins A and C also decreased the levels of pro-inflammatory cytokines (TNF-α, IL1β) and iNOS and increased gene expressions of IL-10, Nrf-2, HO-1, and MBP. Combination therapy of vitamins A and C also increased the total antioxidant capacity and decreased levels of oxidative stress markers. Finally, we proved that co-administration of vitamins A and C has anti-apoptotic and neuroprotective impacts in EAE via decreasing caspase-3 and increasing BDNF and NeuN expressing cells. The present study suggests that combined therapy of vitamins A and C may be an effective strategy for development of alternative medicine in boosting myelin repair in demyelinating diseases.

Ganciclovir attenuates the onset and progression of experimental autoimmune uveitis by inhibiting infiltration of Th17 and inflammatory cells into the retina

Noninfectious (autoimmune and immune-mediated) uveitis is one of the primary diseases leading to blindness in the world. Due to the limitation of current first-line drugs for clinical uveitis, novel drugs and targets against uveitis are urgently needed. Ganciclovir (GCV), an FDA-approved antiviral drug, is often used to treat cytomegalovirus-induced retinitis in clinical patients. Recently, GCV was found to suppress neuroinflammation via targeting STING signaling because the STING pathway plays a pivotal role in autoimmune diseases. However, until now, the effect of GCV on non-infectious uveitis has never been explored. In this work, using the rat experimental autoimmune uveitis (EAU) model, we first found STING to be highly expressed in infiltrating cells (CD68⁺, CD45⁺, and CD4⁺) and retinal glial cells (Iba1⁺ and GFAP⁺) of the immunized retina. More importantly, GCV treatment can significantly suppress the initiation and progression of EAU by inhibiting infiltration of Th17 and inflammatory cells into the retina. Mechanistically, we found that GCV could reverse the levels of pro-inflammatory factors (such as IL-1β) and chemokine-related factors (such as Cxcr3), possibly via targeting the STING pathway. The present results suggest that GCV may be considered as a novel therapeutic strategy against human uveitis.

The Efficacy of Fecal Microbiota Transplantation in Experimental Autoimmune Encephalomyelitis: Transcriptome and Gut Microbiota Profiling

Objective

To study the protective effect of fecal microbiota transplantation (FMT) on experimental autoimmune encephalomyelitis (EAE) and reveal its potential intestinal microflora-dependent mechanism through analyses of the intestinal microbiota and spinal cord transcriptome in mice.

Method

We measured the severity of disease by clinical EAE scores and H&E staining. Gut microbiota alteration in the gut and differentially expressed genes (DEGs) in the spinal cord were analyzed through 16S rRNA and transcriptome sequencing. Finally, we analyzed associations between the relative abundance of intestinal microbiota constituents and DEGs.

Results

We observed that clinical EAE scores were lower in the EAE+FMT group than in the EAE group. Meanwhile, mice in the EAE+FMT group also had a lower number of infiltrating cells. The results of 16S rRNA sequence analysis showed that FMT increased the relative abundance of Firmicutes and Proteobacteria and reduced the abundance of Bacteroides and Actinobacteria. Meanwhile, FMT could modulate gut microbiota balance, especially via increasing the relative abundance of g_Adlercreutzia, g_Sutterella, g_Prevotella_9, and g_Tyzzerella_3 and decreasing the relative abundance of g_Turicibacter. Next, we analyzed the transcriptome of mouse spinal cord tissue and found that 1476 genes were differentially expressed between the EAE and FMT groups. The analysis of these genes showed that FMT mainly participated in the inflammatory response. Correlation analysis between gut microbes and transcriptome revealed that the relative abundance of Adlercreutzia was correlated with the expression of inflammation-related genes negatively, including Casp6, IL1RL2 (IL-36R), IL-17RA, TNF, CCL3, CCR5, and CCL8, and correlated with the expression of neuroprotection-related genes positively, including Snap25, Edil3, Nrn1, Cpeb3, and Gpr37.

Conclusion

Altogether, FMT may selectively regulate gene expression to improve inflammation and maintain the stability of the intestinal environment in a gut microbiota-dependent manner.

Nitric Oxide Induces a Janus Kinase-1-Dependent Inflammatory Response in Primary Murine Astrocytes

Nitric oxide (NO) is a versatile free radical that has been implicated in many biological processes (i.e., vasodilation, neurotransmission, and smooth muscle relaxation). High levels of NO, such as those produced by inducible NO synthase, are associated with innate immunity as well as tissue damage and disease pathology. Previous studies have characterized many stimuli that lead to NO production following central nervous system (CNS) infection, ischemia, and during neurodegeneration, but less is known about the effects of NO on the CNS resident astrocytes. Previously, excessive NO has been shown to impair protein folding leading to endoplasmic reticulum (ER) stress and initiation of the unfolded protein response. Previous studies have shown that ER stress drives activation of protein kinase R-like ER kinase (PERK) and Janus kinase-1 (JAK1) leading to inflammatory gene expression. We hypothesized that NO drives inflammatory processes within astrocytes through a similar process. To test this, we examined the effects of exogenous NO on primary cultures of murine astrocytes. Our data suggest that NO promotes a pro-inflammatory response that includes interleukin-6 and several chemokines. Our data show that NO induces phosphorylation of eukaryotic initiation factor 2 alpha; however, this and the inflammatory gene expression are independent of PERK. Knockdown of JAK1 using small interfering RNA reduced the expression of inflammatory mediators. Overall, we have identified that NO stimulates the integrated stress response and a JAK1-dependent inflammatory program in astrocytes.

Summary statement: Murine astrocytes in culture respond to NO with increased expression of stress and inflammatory genes. The inflammatory stress response is independent of the ER stress-activated kinase PERK and is, in part, mediated by JAK1.

Microglia promote autoimmune inflammation via the noncanonical NF-κB pathway

Microglia have been implicated in neuroinflammatory diseases, including multiple sclerosis and its animal model experimental autoimmune encephalomyelitis (EAE). We demonstrate that microglia mediate EAE disease progression via a mechanism relying on the noncanonical nuclear factor kB (NF-κB) pathway. Microglia-specific deletion of the noncanonical NF-κB-inducing kinase (NIK) impairs EAE disease progression. Although microglial NIK is dispensable for the initial phase of T cell infiltration into the central nervous system (CNS) and EAE disease onset, it is critical for the subsequent CNS recruitment of inflammatory T cells and monocytes. Our data suggest that following their initial CNS infiltration, T cells activate the microglial noncanonical NF-κB pathway, which synergizes with the T cell-derived cytokine granulocyte-macrophage colony-stimulating factor to induce expression of chemokines involved in the second-wave of T cell recruitment and disease progression. These findings highlight a mechanism of microglial function that is dependent on NIK signaling and required for EAE disease progression.

Piperine Improves Experimental Autoimmune Encephalomyelitis (EAE) in Lewis Rats Through its Neuroprotective, Anti-inflammatory, and Antioxidant Effects

Inflammation, demyelination, glial activation, and oxidative damage are the most pathological hallmarks of multiple sclerosis (MS). Piperine, a main bioactive alkaloid of black pepper, possesses antioxidant, anti-inflammatory, and neuroprotective properties whose therapeutic potential has been less studied in the experimental autoimmune encephalomyelitis (EAE) models. In this study, the efficiency of piperine on progression of EAE model and myelin repair mechanisms was investigated. EAE was induced in female Lewis rats and piperine and its vehicle were daily administrated intraperitoneally from day 8 to 29 post immunization. We found that piperine alleviated neurological deficits and EAE disease progression. Luxol fast blue and H&E staining and immunostaining of lumbar spinal cord cross sections confirmed that piperine significantly reduced the extent of demyelination, inflammation, immune cell infiltration, microglia, and astrocyte activation. Gene expression analysis in lumbar spinal cord showed that piperine treatment decreased the level of pro-inflammatory cytokines (TNF-α, IL-1β) and iNOS and enhanced IL-10, Nrf2, HO-1, and MBP expressions. Piperine supplementation also enhanced the total antioxidant capacity (FRAP) and reduced the level of oxidative stress marker (MDA) in the CNS of EAE rats. Finally, we found that piperine has anti-apoptotic and neuroprotective effect in EAE through reducing caspase-3 (apoptosis marker) and enhancing BDNF and NeuN expressing cells. This study strongly indicates that piperine has a beneficial effect on the EAE progression and could be considered as a potential therapeutic target for MS treatment. Upcoming clinical trials will provide a deeper understanding of piperine's role for the treatment of the MS.

Hyperbaric Oxygen Therapy Alleviates the Autoimmune Encephalomyelitis via the Reduction of IL-17a and GM-Csf Production of Autoreactive T Cells as Well as Boosting the Immunosuppressive IL-10 in the Central Nervous System Tissue Lesions

Multiple sclerosis (MS) is a chronic autoimmune disease mainly caused by autoreactive T cells, followed by neuronal demyelination and disabling paralysis. Hyperbaric oxygen therapy (HBOT) is usually an adjunct to therapy for the treatment of neurological disorders. However, it remains still controversial whether HBOT is an effective option for the treatment of MS. Experimental autoimmune encephalomyelitis (EAE) is a well-studied mouse model investigated for the MS pathogenesis and the efficacy of the therapeutic intervention. Both encephalitogenic Th1 and Th17 are pivotal T cell subsets immunopathogenically producing several disease-initiating/modifying cytokines in the central nervous system (CNS) lesions to further exacerbate/ameliorate the progression of EAE or MS. However, it remains unclear whether HBOT modulates the context of T helper cell subsets in CNS lesions. We employed EAE in the presence of HBOT to assess whether disease amelioration is attributed to alterations of CNS-infiltrating T cell subsets. Our results demonstrated that semi-therapeutic HBOT significantly alleviated the progression of EAE, at least, via the suppression of Th17 response, the downregulation of CD4 T helper cells expressing GM-CSF or TNF-α, and the boosting of immunomodulatory IL-4 or IL-10-expressed CD4 T cells in the CNS lesions. Conclusively, HBOT attenuated EAE through the modulation of T cell responses in an earlier stage.

Cytokines as a marker of central nervous system autoantibody associated epilepsy

OBJECTIVE

Autoantibodies to central nervous system (CNS) antigens are increasingly identified in patients with epilepsy. Alterations in cytokines and chemokines have also been demonstrated in epilepsy, but this has not been explored in subjects with autoantibodies. If antibody positive and antibody negative subjects show a difference in immune activation, as measured by cytokine levels, this could improve diagnostic and therapeutic approaches, and provide insights into the underlying pathophysiology. We aimed to evaluate serum and CSF cytokines and chemokines in patients with and without autoantibody positivity to identify any differences between the two groups.

METHODS

We studied participants who had undergone serum and CSF testing for CNS autoantibodies, as part of their clinical evaluation. Cases were classified as antibody positive or antibody negative for comparison. Stored CSF and sera were analysed for cytokine and chemokine concentrations.

RESULTS

25 participants underwent testing. 8 were antibody positive, 17 were antibody negative. Significant elevations in the mean concentration of IL-13 and RANTES in CSF were found in the antibody positive cases and significant elevation of CSF VEGF was found in the antibody negative cases. Significant elevations in the mean concentrations of serum TNFβ, INFγ, bNGF, IL-8, and IL-12 were seen in the antibody negative group, and there was poor correlation between the majority of serum and CSF concentrations.

SIGNIFICANCE

Measurement of cytokines and chemokines such as IL-13 and RANTES could be useful in diagnosis of autoimmune associated epilepsy. Such markers might also guide targeted immunotherapy to improve seizure control and provide insights into the underlying pathophysiology of epilepsy associated with CNS autoantibodies.

m6A demethylase ALKBH5 controls CD4+ T cell pathogenicity and promotes autoimmunity

N⁶-methyladenosine (m⁶A) modification is dynamically regulated by "writer" and "eraser" enzymes. m⁶A "writers" have been shown to ensure the homeostasis of CD4⁺ T cells, but the "erasers" functioning in T cells is poorly understood. Here, we reported that m⁶A eraser AlkB homolog 5 (ALKBH5), but not FTO, maintains the ability of naïve CD4⁺ T cells to induce adoptive transfer colitis. In addition, T cell-specific ablation of ALKBH5 confers protection against experimental autoimmune encephalomyelitis. During the induced neuroinflammation, ALKBH5 deficiency increased m⁶A modification on interferon-γ and C-X-C motif chemokine ligand 2 messenger RNA (mRNA), thus decreasing their mRNA stability and protein expression in CD4⁺ T cells. These modifications resulted in attenuated CD4⁺ T cell responses and diminished recruitment of neutrophils into the central nervous system. Our findings reveal an unexpected specific role of ALKBH5 as an m⁶A eraser in controlling the pathogenicity of CD4⁺ T cells during autoimmunity.

Cross-Talk of the CNS With Immune Cells and Functions in Health and Disease

The immune system's role is much more than merely recognizing self vs. non-self and involves maintaining homeostasis and integrity of the organism starting from early development to ensure proper organ function later in life. Unlike other systems, the central nervous system (CNS) is separated from the peripheral immune machinery that, for decades, has been envisioned almost entirely as detrimental to the nervous system. New research changes this view and shows that blood-borne immune cells (both adaptive and innate) can provide homeostatic support to the CNS via neuroimmune communication. Neurodegeneration is mostly viewed through the lens of the resident brain immune populations with little attention to peripheral circulation. For example, cognition declines with impairment of peripheral adaptive immunity but not with the removal of microglia. Therapeutic failures of agents targeting the neuroinflammation framework (inhibiting immune response), especially in neurodegenerative disorders, call for a reconsideration of immune response contributions. It is crucial to understand cross-talk between the CNS and the immune system in health and disease to decipher neurodestructive and neuroprotective immune mechanisms for more efficient therapeutic strategies.

Trichinella spiralis excretory-secretory products downregulate MMP-9 in Dark Agouti rats affected by experimental autoimmune encephalomyelitis

Matrix metalloproteinases (MMPs), are implicated in the pathogenesis of multiple sclerosis (MS) and in its animal model, experimental autoimmune encephalomyelitis (EAE). Our aim was to investigate whether amelioration of EAE in Dark Agouti (DA) rats, induced by Trichinella spiralis muscle larvae excretory-secretory products (ES L1), could be related to the level and activity of gelatinases, MMP-9 and MMP-2. Serum levels of MMP-9, MMP-2, NGAL/MMP-9, TIMP-1, and cytokines, evaluated by gel-zymography or ELISA, as well as gelatinases and TIMP-1 expression in the spinal cord (SC), were determined in: i) EAE induced, ii) ES L1-treated EAE induced animals. Milder clinical signs in ES L1-treated EAE induced DA rats were accompanied with lower serum levels of MMP-9 and NGAL/MMP-9 complex. However, the correlation between the severity of EAE and the level of serum MMP-9 was found only in the peak of the disease, with MMP-9/TIMP-1 ratio higher in EAE animals without ES L1 treatment. Lower expression of MMP-9 in SC of ES L1-treated, EAE induced rats, correlated with the reduced number of SC infiltrating cells. In SC infiltrates, in the effector and the recovery phase, production of anti-inflammatory cytokines IL-4 and IL-10 was higher in animals treated with ES L1 prior to EAE induction, compared to untreated EAE animals. Reduced expression of MMP-9 in SC tissue, which correlated with the reduced number of infiltrating cells, might be ascribed to regulatory mechanisms, among which is IL-10.

MicroRNA in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system (CNS). Despite a complex pathogenesis, it appears that an imbalanced immune system plays an important role in the disease process. MicroRNAs (miRNAs) are comprised of short non-coding single-stranded molecules mainly involved in regulating gene expression through the inhibition of transcription and translation. miRNAs are key regulatory molecules in the nucleus and participate in the proliferation, differentiation, and apoptosis of various cells throughout the body. Recent studies, however, have found that miRNAs are also involved in MS pathogenesis, mainly affecting glial cells and peripheral immune cells. Fortunately, miRNAs are highly stable and have high specificity in peripheral body fluids. Accordingly, these molecules have become new diagnostic and therapeutic targets. The present review discusses the role of miRNAs in the pathogenesis of MS. We highlight the potential of miRNAs as new biomarkers of MS and potential therapeutic agents.

Sex differences in EAE reveal common and distinct cellular and molecular components

Experimental autoimmune encephalomyelitis (EAE) is commonly used as an animal model for evaluating clinical, histological and immunological processes potentially relevant to the human disease multiple sclerosis (MS), for which the mode of disease induction remains largely unknown. An important caveat for interpreting EAE processes in mice is the inflammatory effect of immunization with myelin peptides emulsified in Complete Freund's Adjuvant (CFA), often followed by additional injections of pertussis toxin (Ptx) in some strains to induce EAE. The current study evaluated clinical, histological, cellular (spleen), and chemokine-driven processes in spinal cords of male vs. female C57BL/6 mice that were immunized with mouse (m)MOG-35-55/CFA/Ptx to induce EAE; immunized with saline/CFA/Ptx only (CFA, no EAE); or were untreated (Naïve, no EAE). Analysis of response curves utilized a rigorous and sophisticated methodology to parse and characterize the effects of EAE and adjuvant alone vs. the Naive baseline responses. The results demonstrated stronger pro-inflammatory responses of immune cells and their associated cytokines, chemokines, and receptors in male vs. female CFA and EAE mice that appeared to be offset partially by increased percentages of male anti-inflammatory, regulatory and checkpoint T cell, B cell, and monocyte/macrophage subsets. These sex differences in peripheral immune responses may explain the reduced cellular infiltration and differing chemokine profiles in the Central Nervous System (CNS) of male vs. female CFA immunized mice and the reduced CNS infiltration and demyelination observed in male vs. female EAE groups of mice that ultimately resulted in the same clinical EAE disease severity in both sexes. Our findings suggest EAE disease severity is governed not only by the degree of CNS infiltration and demyelination, but also by the balance of pro-inflammatory vs. regulatory cell types and their secreted cytokines and chemokines.

Targeting Chemokines and Chemokine Receptors in Multiple Sclerosis and Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is an immune-mediated and neurodegenerative disorder that results in inflammation and demyelination of the central nervous system (CNS). MS symptoms include walking difficulties, visual weakening, as well as learning and memory impairment, thus affecting the quality of the patient's life. Chemokines and chemokine receptors are expressed on the immune cells as well as the CNS resident cells. Several sets of chemokine receptors and their ligands tend to be pathogenic players in MS, including CCL2, CCL3, CCL4, CCL5, CCL7, CCL8, CCL11, CCL17, CCL19, CCL21, CCL22, CXCL1, CXCL8, CXCL9, CXCL10, CXCL11, and CXCL16. Furthermore, current modulatory drugs that are used in the treatment of MS and its animal model, the experimental autoimmune encephalomyelitis (EAE), affect the expression of several chemokine and chemokine receptors. In this review, we highlight the pathogenic roles of chemokines and their receptors as well as utilizing them as potential therapeutic targets through selective agents, such as specific antibodies and receptor blockers, or indirectly through MS or EAE immunomodulatory drugs.

CXCR3 Ligands in Cancer and Autoimmunity, Chemoattraction of Effector T Cells, and Beyond

CXCR3 is a chemokine receptor with three ligands; CXCL9, CXCL10, and CXCL11. CXCL11 binds CXCR3 with a higher affinity than the other ligands leading to receptor internalization. Long ago we reported that one of these chemokines, CXCL10, not only attracts CXCR3+ CD4+ and CD8+ effector T cells to sites of inflammation, but also direct their polarization into highly potent effector T cells. Later we showed that CXCL11 directs the linage development of T-regulatory-1 cells (Tr1). We also observed that CXCL11 and CXCL10 induce different signaling cascades via CXCR3. Collectively this suggests that CXCR3 ligands differentially regulate the biological function of T cells via biased signaling. It is generally accepted that tumor cells evolved to express several chemokine receptors and secrete their ligands. Vast majority of these chemokines support tumor growth by different mechanisms that are discussed. We suggest that CXCL10 and possibly CXCL9 differ from other chemokines by their ability to restrain tumor growth and enhance anti-tumor immunity. Along with this an accumulating number of studies showed in various human cancers a clear association between poor prognosis and low expression of CXCL10 at tumor sites, and vice versa. Finally, we discuss the possibility that CXCL9 and CXCL10 may differ in their biological function via biased signaling and its possible relevance to cancer immunotherapy. The current mini review focuses on exploring the role of CXCR3 ligands in directing the biological properties of CD4+ and CD8+ T cells in the context of cancer and autoimmunity. We believe that the combined role of these chemokines in attracting T cells and also directing their biological properties makes them key drivers of immune function.

The proportion of myeloid-derived suppressor cells in the spleen is related to the severity of the clinical course and tissue damage extent in a murine model of multiple sclerosis

Multiple Sclerosis (MS) is the second cause of paraplegia among young adults, after all types of CNS traumatic lesions. In its most frequent relapsing-remitting form, the severity of the disease course is very heterogeneous, and its reliable evaluation remains a key issue for clinicians. Myeloid-Derived sSuppressor Cells (MDSCs) are immature myeloid cells that suppress the inflammatory response, a phenomenon related to the resolution or recovery of the clinical symptoms associated with experimental autoimmune encephalomyelitis (EAE), the most common model for MS. Here, we establish the severity index as a new parameter for the clinical assessment in EAE. It is derived from the relationship between the maximal clinical score and the time elapsed since disease onset. Moreover, we relate this new index with several histopathological hallmarks in EAE and with the peripheral content of MDSCs. Based on this new parameter, we show that the splenic MDSC content is related to the evolution of the clinical course of EAE, ranging from mild to severe. Indeed, when the severity index indicates a severe disease course, EAE mice display more intense lymphocyte infiltration, demyelination and axonal damage. A direct correlation was drawn between the MDSC population in the peripheral immune system, and the preservation of myelin and axons, which was also correlated with T cell apoptosis within the CNS (being these cells the main target for MDSC suppression). The data presented clearly indicated that the severity index is a suitable tool to analyze disease severity in EAE. Moreover, our data suggest a clear relationship between circulating MDSC enrichment and disease outcome, opening new perspectives for the future targeting of this population as an indicator of MS severity.