Role In Experimental Autoimmune Encephalomyelitis Research Articles

Lymphotoxins from distinct types of lymphoid cells differentially contribute to neuroinflammation.

Lymphotoxin α and lymphotoxin β (LTs), TNF superfamily members, are expressed in either soluble (LTα3) or membrane-bound (LTα1β2 or LTα2β1) forms. In the pathological context, LT-mediated signaling is known to exacerbate autoimmunity by perpetuating inflammation and promoting the formation of tertiary lymphoid organs. Despite this understanding, the exact roles of LTα and LTβ in the pathogenesis of the murine model of multiple sclerosis, and experimental autoimmune encephalomyelitis (EAE), remain controversial. Here, we employed a panel of gene-modified mice with cell-type restricted ablation of LTα (targeting both membrane-bound and soluble forms of LTs) to unravel the contributions of LTs from various lymphoid cells, namely T cells, type 3 innate lymphoid cells (ILC3) and B cells, in EAE. We found that the effects of LTα deletion were dependent on the cellular source. ILC3-derived lymphotoxins exerted a protective role in EAE by regulating the accumulation of IFN-ɣ- and GM-CSF-producing TH cells in the CNS. In contrast, T-cell-derived lymphotoxins promoted IL-17A- and GM-CSF-mediated TH responses in the periphery, whereas B-cell-derived lymphotoxins were pathogenic only in the autoantibody-mediated EAE model. Collectively, our findings unveil the multifaceted involvement of lymphotoxins in EAE pathogenesis and challenge the view that lymphotoxins play a solely pathogenic role in neuroinflammation.

IKKβ deletion from CNS macrophages increases neuronal excitability and accelerates the onset of EAE, while from peripheral macrophages reduces disease severity

BackgroundMultiple sclerosis (MS) is a neuroinflammatory demyelinating disease characterized by motor deficits and cognitive decline. Many immune aspects of the disease are understood through studies in the experimental autoimmune encephalomyelitis (EAE) model, including the contribution of the NF-κB transcription factor to neuroinflammation. However, the cell-specific roles of NF-κB to EAE and its cognitive comorbidities still needs further investigation. We have previously shown that the myeloid cell NF-κB plays a role in the healthy brain by exerting homeostatic regulation of neuronal excitability and synaptic plasticity and here we investigated its role in EAE.MethodsWe used constitutive MφIKKβΚΟ mice, in which depletion of IKKβ, the main activating kinase of NF-κB, was global to CNS and peripheral macrophages, and ΜgΙΚΚβKO mice, in which depletion was inducible and specific to CNS macrophages by 28 days after tamoxifen administration. We subjected these mice to MOG35-55 induced EAE and cuprizone-induced demyelination. We measured pathology by immunohistochemistry, investigated molecular mechanisms by RNA sequencing analysis and studied neuronal functions by in vivo electrophysiology in awake animals.ResultsGlobal depletion of IKKβ from myeloid cells in MφIKKβΚΟ mice accelerated the onset and significantly supressed chronic EAE. Knocking out IKKβ only from CNS resident macrophages accelerated the onset and exacerbated chronic EAE, accompanied by earlier demyelination and immune cell infiltration but had no effect in cuprizone-induced demyelination. Peripheral T cell effector functions were not affected by myeloid cell deletion of IKKβ, but CNS resident mechanisms, such as microglial activation and neuronal hyperexcitability were altered from early in EAE. Lastly, depletion of myeloid cell IKKβ resulted in enhanced late long-term potentiation in EAE.ConclusionsIKKβ-mediated activation of NF-κΒ in myeloid cells has opposing roles in EAE depending on the cell type and the disease stage. In CNS macrophages it is protective while in peripheral macrophages it is disease-promoting and acts mainly during chronic disease. Although clinically protective, CNS myeloid cell IKKβ deletion dysregulates neuronal excitability and synaptic plasticity in EAE. These effects of IKKβ on brain cognitive abilities deserve special consideration when therapeutic interventions that inhibit NF-κB are used in MS.

How myeloid cells shape experimental autoimmune encephalomyelitis: At the crossroads of outside-in immunity.

Experimental autoimmune encephalomyelitis (EAE) is an animal model of central nervous system (CNS) autoimmunity. It is most commonly used to mimic aspects of multiple sclerosis (MS), a demyelinating disorder of the human brain and spinal cord. The innate immune response displays one of the core pathophysiological features linked to both the acute and chronic stages of MS. Hence, understanding and targeting the innate immune response is essential. Microglia and other CNS resident MUs, as well as infiltrating myeloid cells, diverge substantially in terms of both their biology and their roles in EAE. Recent advances in the field show that antigen presentation, as well as disease-propagating and regulatory interactions with lymphocytes, can be attributed to specific myeloid cell types and cell states in EAE lesions, following a distinct temporal pattern during disease initiation, propagation and recovery. Furthermore, single-cell techniques enable the assessment of characteristic proinflammatory as well as beneficial cell states, and identification of potential treatment targets. Here, we discuss the principles of EAE induction and protocols for varying experimental paradigms, the composition of the myeloid compartment of the CNS during health and disease, and systematically review effects on myeloid cells for therapeutic approaches in EAE.

IL-33 and HMGB1 modulate the progression of EAE via oppositely regulating each other

Interleukin-33 (IL-33) and high mobility group box 1 (HMGB1) have been reported to play crucial and distinct roles in experimental autoimmune encephalomyelitis (EAE). However, little is known about their interaction in the progression of EAE. In this study, the dynamic expression and release of IL-33 and HMGB1 in different stages of EAE in vivo, and their interaction in vitro were explored. We found that HMGB1 was dominant in pre-onset stage of EAE, while IL-33 was dominant in peak stage. Moreover, both blockade of extracellular HMGB1 in the central nervous system (CNS) and conditional knockout of HMGB1 in astrocytes decreased IL-33 release. HMGB1 promoted the release of IL-33, while IL-33 reduced the release of HMGB1 from primary astrocytes in vitro. Taken together, IL-33 and HMGB1 in the CNS jointly participate in the EAE progression and the inhibitory effect of IL-33 on HMGB1 may be involved in the self-limiting of EAE.

Tehranolid and Artemisinin Effects on Ameliorating Experimental Autoimmune Encephalomyelitis by Modulating Inflammation and Remyelination.

Multiple sclerosis (MS) is an autoimmune demyelinating disease of the central nervous system. Artemisinin (ART) is a natural sesquiterpene lactone with an endoperoxide bond that is well-known for its anti-inflammatory effects in experimental autoimmune encephalomyelitis (EAE), the most commonly used animal model of MS. Tehranolide (TEH) is a novel compound with structural similarity to ART. In this study, we aimed to investigate the ameliorating effect of TEH on EAE development by targeting proteins and genes involved in this process and compare its effects with ART. Female C57BL/6 mice were immunized with MOG35-55. Twelve days post-immunization, mice were treated with 0.28mg/kg/day TEH and 2.8mg/kg/day ART for 18 consecutive days, and the clinical score was measured daily. The levels of pro-inflammatory and anti-inflammatory cytokines were assessed in mice serum and splenocytes by ELISA. We also evaluated the mRNA expression level of cytokines, as well as genes involved in T cell differentiation and myelination in the spinal cord tissue by qRT-PCR. Administration of TEH and ART significantly alleviated EAE signs. A significant reduction in IL-6 and IL-17 secretion and IL-17 and IL-1 gene expression in spinal cord were observed in the TEH-treated group. ART had similar or less significant effects. Moreover, TGF-β, IL-4, and IL-10 genes were stimulated by ART and TEH in the spinal cord, while the treatments did not affect IFN-γ expression. Both treatments dramatically increased the expression of FOXP3, GATA3, MBP, and AXL. Additionally, the T-bet gene was reduced after TEH administration. The compounds made no changes in RORγt, nestin, Gas6, Tyro3, and Mertk mRNA expression levels in the spinal cord. The study revealed that both TEH and ART can effectively modulate the genes responsible for inflammation and myelination that play a crucial role in EAE. Interestingly, TEH demonstrated a greater potency compared to ART and hence may have the potential to be evaluated in interventions for the management of MS.

The role of tumor necrosis factor receptor 2 (TNFR2) in EAE

Abstract Multiple Sclerosis (MS) is a chronic autoimmune disease of the central nervous system which affects over 2 million people worldwide and is the most common neurological disability in young adults. MS is a heterogenous disease characterized by recurrent, remitting and/or progressive neurological deficits, and clinical manifestations include nerve damage, visual loss, motor and balance impairment, gait disturbance, and others. While several environmental and genetic risk factors have been identified, such as the DR2b (DRB1*1501) human MHC class II allele, the molecular mechanisms underlying the development and severity of MS remain poorly understood. Tumor necrosis factor is a cytokine that exerts its effects through two different surface receptors TNFR1 and TNFR2, and it has been identified as a key player in MS pathogenesis. TNFR2 is thought to have a protective role in experimental autoimmune encephalomyelitis (EAE), a mouse model for MS, by altering the function of astrocytes and regulatory T cells (Tregs). Previous data from our lab demonstrated that in the absence of TNFR2, transgenic mice expressing the DR2b allele and lacking mouse MHC class II (DR2bDR2) develop a more severe and progressive form of EAE, exhibiting astrogliosis. We have previously demonstrated that multiple Treg-associated genes were upregulated in CD4 +T cells from DR2bDR2 mice compared to those from control mice. However, the exact mechanism by which TNFR2 regulates Treg function in EAE is unknown. Here, we show that deletion of TNFR2 impacts the ability of Tregs to expand in vitro as well as their localization within the brains of mice undergoing EAE. Our results provide key insights into the mechanism by which TNFR2 limits and protects against CNS inflammation.

Translational Significance of GMF-β Inhibition by Indazole-4-yl-methanol in Enteric Glial Cells for Treating Multiple Sclerosis

In the emerging context of gut-brain control of multiple sclerosis (MS), developing therapeutics targeting proinflammatory proteins controlling the gut-brain immunomodulation is welcoming. One such immunomodulator is glia maturation factor-β (GMF-β). GMF-β activation following GMF-β-ser-83 phosphorylation upregulates proinflammatory responses and exacerbates experimental autoimmune encephalomyelitis (EAE). Notably, GMF-β-/- mice exhibited no EAE symptoms. Thus, we identified 1H-indazole-4-yl-methanol (GMFBI.1) inhibitor which blocked GMF-β-ser-83 phosphorylation critical in EAE suppression. To establish gut GMF-β's role in EAE in the context of gut-brain involvement in neurodegenerative diseases, we altered gut GMFBI.1 bioavailability as an index of EAE suppression. At first, we identified Miglyol 812N as a suitable biocompatible GMFBI.1 carrier compared to other FDA-approved carriers using in silico molecular docking analysis. GMFBI.1 administration in Miglyol 812N enhanced its retention/brain permeability. Subsequently, we administered GMFBI.1-Miglyol 812N by subcutaneous/oral routes at different doses with differential GMFBI.1 bioavailability in gut and brain to assess the role of local GMFBI.1 bioavailability in EAE reversal by a pharmacokinetic approach. Deprival of gut GMFBI.1 bioavailability led to partial EAE suppression despite having sufficient GMFBI.1 in circulation to inhibit brain GMF-β activity. Restoration of gut GMFBI.1 bioavailability led to complete EAE reversal. Molecular pathology behind partial/full EAE reversal was associated with differential GMF-β-Ser-83 phosphorylation/GM-CSF expression levels in enteric glial cells owing to GMFBI.1 bioavailability. In addition, we observed leaky gut reversal, tight junction protein ZO-1 restoration, beneficial gut microbiome repopulation, recovery from gut dysbiosis, and upregulation of Treg cells. GMFBI.1's dual gut/brain targeting of GMF-β has therapeutical/translational potential in controlling autoimmunity in MS.

RNA Editing Alterations Define Disease Manifestations in the Progression of Experimental Autoimmune Encephalomyelitis (EAE).

RNA editing is an epitranscriptomic modification, leading to targeted changes in RNA transcripts. It is mediated by the action of ADAR (adenosine deaminases acting on double-stranded (ds) RNA and APOBEC (apolipoprotein B mRNA editing enzyme catalytic polypeptide-like) deaminases and appears to play a major role in the pathogenesis of many diseases. Here, we assessed its role in experimental autoimmune encephalomyelitis (EAE), a widely used non-clinical model of autoimmune inflammatory diseases of the central nervous system (CNS), which resembles many aspects of human multiple sclerosis (MS). We have analyzed in silico data from microglia isolated at different timepoints through disease progression to identify the global editing events and validated the selected targets in murine tissue samples. To further evaluate the functional role of RNA editing, we induced EAE in transgenic animals lacking expression of APOBEC-1. We found that RNA-editing events, mediated by the APOBEC and ADAR deaminases, are significantly reduced throughout the course of disease, possibly affecting the protein expression necessary for normal neurological function. Moreover, the severity of the EAE model was significantly higher in APOBEC-1 knock-out mice, compared to wild-type controls. Our results implicate regulatory epitranscriptomic mechanisms in EAE pathogenesis that could be extrapolated to MS and other neurodegenerative disorders (NDs) with common clinical and molecular features.

HMGB1 from Astrocytes Promotes EAE by Influencing the Immune Cell Infiltration-Associated Functions of BMECs in Mice.

High mobility group box 1 (HMGB1) has been reported to play an important role in experimental autoimmune encephalomyelitis (EAE). Astrocytes are important components of neurovascular units and tightly appose the endothelial cells of microvessels by their perivascular endfeet and directly regulate the functions of the blood-brain barrier. Astrocytes express more HMGB1 during EAE while the exact roles of astrocytic HMGB1 in EAE have not been well elucidated. Here, using conditional-knockout mice, we found that astrocytic HMGB1 depletion decreased morbidity, delayed the onset time, and reduced the disease score and demyelination of EAE. Meanwhile, there were fewer immune cells, especially pathogenic T cells infiltration in the central nervous system of astrocytic HMGB1 conditional-knockout EAE mice, accompanied by up-regulated expression of the tight-junction protein Claudin5 and down-regulated expression of the cell adhesion molecules ICAM1 and VCAM1 in vivo. In vitro, HMGB1 released from astrocytes decreased Claudin5 while increased ICAM1 and VCAM1 expressed by brain microvascular endothelial cells (BMECs) through TLR4 or RAGE. Taken together, our results demonstrate that HMGB1 derived from astrocytes aggravates EAE by directly influencing the immune cell infiltration-associated functions of BMECs.

CCR1 antagonist ameliorates experimental autoimmune encephalomyelitis by inhibition of Th9/Th22-related markers in the brain and periphery

Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system. The disease manifestation is associated with the proliferation and activation of lymphocytes and astrocytes, leading to demyelination and neuronal damage. Most of the current therapies are not completely effective, and few target the underlying pathophysiology of MS. T helper 9 (Th9)- and Th22-dominant cells have been proven to play a pathogenic role in experimental autoimmune encephalomyelitis (EAE), an animal model of MS. The goal of the present study was to investigate the therapeutic efficacy of J-113863, a novel CCR1 chemokine receptor, on PLP139–151-induced EAE in SJL/J mice. Following induction of EAE, mice were treated with J-113863 (10 mg/kg) or saline intraperitoneally daily from day 14 until day 25, and the clinical score was evaluated. We further investigated the effect of J-113863 on IL-9, IRF4, IL-22, IFN-γ, STAT3, AhR, and IL-17A in CD3+, CD4+, CCR6+, and CCR8+ spleen cells using flow cytometry. We also analyzed the effect of J-113863 on IL-9, IRF4, IL-22, IFN-γ, STAT3, AhR, and IL-17A mRNA expression levels. Our results revealed that J-113863 treatment notably attenuated the severity of clinical scores in EAE mice. J-113863 treatment decreased the percentage expression of CD4+IL-9+, CCR8+IL-9+, CD4+IRF4+, CD3+IL-22+, CCR6+IL-22+, CD3+IFN-γ+, CCR6+IFN-γ+, CD3+STAT3+, CCR6+STAT3+, CD4+IL-17A+, and CCR6+IL-17A+, and increased the percentage of CD3+AhR+, and CCR6+AhR+ cells in the spleen. These results confirmed that J-113863 suppressed Th9/Th22 cells to reduce demyelination in EAE mice, suggesting its potential role as a novel drug candidate for MS treatment.

Tibolone restrains neuroinflammation in mouse experimental autoimmune encephalomyelitis.

Multiple sclerosis (MS) is an immune-mediated and degenerating disease in which myelin sheaths are damaged as a result of chronic progressive inflammation of the central nervous system. Tibolone [(7α,17α)-17-hydroxy-7-methyl-19-norpregn-5(10)-en-20-in-3-one], a synthetic estrogenic compound with tissue-specific actions and used for menopausal hormone therapy, shows neuroprotective and antioxidant properties both in vivo and in vitro. In the present study, we analyzed whether tibolone plays a therapeutic role in experimental autoimmune encephalomyelitis (EAE) mice, a commonly used model of MS. Female C57BL/6mice were induced with the myelin oligodendrocyte glycoprotein MOG35-55 and received s.c. tibolone (0.08mgkg-1 ) injection every other day from the day of induction until death on the acute phase of the disease. Reactive gliosis, Toll like receptor 4 (TLR4), high mobility group box protein 1 (HMGB1), inflammasome parameters, activated Akt levels and myelin were assessed by a real-time polymerase chain reaction, immunohistochemistry, and western blot analysis. Our findings indicated that, in the EAE spinal cord, tibolone reversed the astrocytic and microglial reaction, and reduced the hyperexpression of TLR4 and HMGB1, as well as NLR family pyrin domain containing 3-caspase 1-interleukin-1β inflammasome activation. At the same time, tibolone attenuated the Akt/nuclear factor kappa B pathway and limited the white matter demyelination area. Estrogen receptor expression was unaltered with tibolone treatment. Clinically, tibolone improved neurological symptoms without uterine compromise. Overall, our data suggest that tibolone may serve as a promising agent for the attenuation of MS-related inflammation.

LRRC4 functions as a neuron-protective role in experimental autoimmune encephalomyelitis

BackgroundLeucine rich repeat containing 4 (LRRC4), also known as netrin-G ligand-2 (NGL-2), belongs to the superfamily of LRR proteins and serves as a receptor for netrin-G2. LRRC4 regulates the formation of excitatory synapses and promotes axon differentiation. Mutations in LRRC4 occur in Autism Spectrum Disorder (ASD) and intellectual disability. Multiple sclerosis (MS) is a chronic neuroinflammatory disease with spinal cords demyelination and neurodegeneration. Here, we sought to investigate whether LRRC4 is involved in spinal cords neuron-associated diseases.MethodsLRRC4 was detected in the CNS of experimental autoimmune encephalomyelitis (EAE) mice by the use of real-time PCR and western blotting. LRRC4−/− mice were created and immunized with myelin oligodendrocyte glycoprotein peptide (MOG)35–55. Pathological changes in spinal cords of LRRC4−/− and WT mice 15 days after immunization were examined by using hematoxylin and eosin (H&E), Luxol Fast Blue (LFB) staining and immunohistochemistry. The number of Th1/Th2/Th17/Treg cells in spleens and blood were measured with flow cytometry. Differential gene expression in the spinal cords from WT and LRRC4−/− mice was analyzed by using RNA sequencing (RNA-seq). Adeno-associated virus (AAV) vectors were used to overexpress LRRC4 (AAV-LRRC4) and were injected into EAE mice to assess the therapeutic effect of AAV-LRRC4 ectopic expression on EAE.ResultsWe report that LRRC4 is mainly expressed in neuron of spinal cords, and is decreased in the spinal cords of the EAE mice. Knockout of LRRC4 have a disease progression quickened and exacerbated with more severe myelin degeneration and infiltration of leukocytes into the spinal cords. We also first found that Rab7b is high expressed in EAE mice, and the deficiency of LRRC4 induces the elevated NF-κB p65 by up-regulating Rab7b, and up-regulation of IL-6, IFN-γ and down-regulation of TNF-α, results in more severe Th1 immune response in LRRC4−/− mice. Ectopic expression of LRRC4 alleviates the clinical symptoms of EAE mice and protects the neurons from immune damages.ConclusionsWe identified a neuroprotective role of LRRC4 in the progression of EAE, which may be used as a potential target for auxiliary support therapeutic treatment of MS.

IL-38 Ablation Reduces Local Inflammation and Disease Severity in Experimental Autoimmune Encephalomyelitis.

IL-38 is an IL-1 family receptor antagonist that restricts IL-17-driven inflammation by limiting cytokine production from macrophages and T cells. In the current study, we aimed to explore its role in experimental autoimmune encephalomyelitis in mice, which is, among others, driven by IL-17. Unexpectedly, IL-38-deficient mice showed strongly reduced clinical scores and histological markers of experimental autoimmune encephalomyelitis. This was accompanied by reduced inflammatory cell infiltrates, including macrophages and T cells, as well as reduced expression of inflammatory markers in the spinal cord. IL-38 was highly expressed by infiltrating macrophages in the spinal cord, and in vitro activated IL-38-deficient bone marrow-derived macrophages showed reduced expression of inflammatory markers, accompanied by altered cellular metabolism. These data suggest an alternative cell-intrinsic role of IL-38 to promote inflammation in the CNS.

Microglial Expression of Hdac1 and Hdac2 is Dispensable for Experimental Autoimmune Encephalomyelitis (EAE) Progression

Previously, we reported that microglial expression of histone deacetylases 1 and 2 (Hdac1 and Hdac2) is required for microglial maturation and modulates disease progression in a mouse model of Alzheimer’s disease. Here, we analyze the role of microglial expression of Hdac1 and Hdac2 in another disease paradigm, namely experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis. The aim of this study was to ascertain whether microglial expression of these two epigenetic regulators modulates disease progression in the context of autoimmune disease. Hdac1 and Hdac2 were knocked out either individually or in combination using a microglia-specific, tamoxifen-inducible Cre-deleter line (Cx3cr1-CreERT2). The clinical course as well as histopathological changes during EAE were assessed in adult mice lacking microglial expression of these genes. Overall, no differences in disease onset, progression or severity could be detected in mice lacking microglial expression of either one or both of Hdac1 and Hdac2 genes. Similarly, the histopathology showed no differences in lymphocyte or macrophage infiltration or demyelination in either of the analyzed groups. As such, we conclude that unlike in neurodegenerative disease, microglial expression of Hdac1 and Hdac2 does not play a role in EAE.

A Systematic Review on the Role of Arachidonic Acid Pathway in Multiple Sclerosis.

Multiple sclerosis (MS) is an inflammatory neurodegenerative disease characterized by destruction of oligodendrocytes, immune cell infiltration and demyelination. Inflammation plays a significant role in MS, and the inflammatory mediators such as eicosanoids, leukotrienes, and superoxide radicals are involved in pro-inflammatory responses in MS. In this systematic review, we tried to define and discuss all the findings of in vivo animal studies and human clinical trials on the potential association between arachidonic acid (AA) pathway and multiple sclerosis. A systematic literature search across Pubmed, Scopus, Embase and Cochrane database was conducted. This systematic review was performed according to PRISMA guidelines. A total of 146 studies were included, of which 34 were conducted on animals, 58 on humans, and 60 studies reported the role of different compounds that target AA mediators or their corresponding enzymes/receptors, and can have a therapeutic effect in MS. These results suggest that eicosanoids have significant roles in Experimental Autoimmune Encephalomyelitis (EAE) and MS. The data from animal and human studies elucidated that PGI2, PGFI2α, PGDI2, isoprostanes, PGEI2, PLAI2, and LTs are increased in MS. PLAI2 inhibition modulates the progression of the disease. PGE1 analogues can be a useful option in the treatment of MS. All studies reported the beneficial effects of COX and LOX inhibitors in MS. The hybrid compounds, such as COX-2 inhibitors/TP antagonists and 5-LOX inhibitors, can be an innovative approach for multiple sclerosis treatment. Future work in MS should shed light on synthesizing new compounds targeting the arachidonic acid pathway.

Bcl6 modulates innate immunity by controlling macrophage activity and plays critical role in experimental autoimmune encephalomyelitis.

The B-cell CLL/lymphoma 6 (Bcl6) oncogenic repressor is a master regulator of humoral immunity and B-cell lymphomagenesis. Although much research has focused on its regulation and function of GC B cells and T cells, the role of Bcl6 in regulating the functions of innate immunity is not well defined. Here, we demonstrated that EAE is exacerbated in LysM Cre+/- Bcl6fl/fl mice. Although other cells such as neutrophils might be involved in this conditional mutant mouse model, we found that the disease pathology is mainly associated with a biased M1 macrophage activity and an enhanced encephalitogenic CD4+ Th17 cell response. In addition, LPS-induced sepsis mice exhibited an enhanced M1 and inhibited M2 response, further confirming that Bcl6 has an important role in regulating macrophage polarization. Mechanistically, Bcl6 interacts with IκBζ and interferes its binding to the interleukin-6 (Il-6) promoter in macrophages, leading to a suppressed transcription of Il-6. These findings have demonstrated that Bcl6 exerts its regulatory function mainly by repressing Il-6 expression in macrophages. Thus, our study presents a novel role for Bcl6 in regulating immune response and inflammation. Interaction between Bcl6 and IκBζ in macrophages may provide a potential therapeutic target for autoimmune inflammatory disease.

CPT1A plays a key role in the development and treatment of multiple sclerosis and experimental autoimmune encephalomyelitis

Human mutations in carnitine palmitoyl transferase 1A (CPT1A) are correlated with a remarkably low prevalence of multiple sclerosis (MS) in Inuits (P479L) and Hutterites (G710E). To elucidate the role of CPT1A, we established a Cpt1a P479L mouse strain and evaluated its sensitivity to experimental autoimmune encephalomyelitis (EAE) induction. Since CPT1a is a key molecule in lipid metabolism, we compared the effects of a high-fat diet (HFD) and normal diet (ND) on disease progression. The disease severity increased significantly in WT mice compared to that in Cpt1 P479L mice. In addition, WT mice receiving HFD showed markedly exacerbated disease course when compared either with Cpt1a P479L mice receiving HFD or WT control group receiving ND. Induction of EAE caused a significant decrease of myelin basic protein expression in the hindbrain of disease affected WT mice in comparison to Cpt1a P479L mice. Further, WT mice showed increased expression of oxidative stress markers like Nox2 and Ho-1, whereas expression of mitochondrial antioxidants regulator Pgc1α was increased in Cpt1a P479L mice. Our results suggest that, lipids metabolism play an important role in EAE, as shown by the higher severity of disease progression in both WT EAE and WT EAF HFD-fed mice in contrast to their counterpart Cpt1a P479L mutant mice. Interestingly, mice with downregulated lipid metabolism due to the Cpt1a P479L mutation showed resistance to EAE induction. These findings support a key role for CPT1A in the development of EAE and could be a promising target in MS treatment.

Combination of Cannabinoids, Δ9- Tetrahydrocannabinol and Cannabidiol, Ameliorates Experimental Multiple Sclerosis by Suppressing Neuroinflammation Through Regulation of miRNA-Mediated Signaling Pathways.

Multiple sclerosis (MS) is a chronic and disabling disorder of the central nervous system (CNS) characterized by neuroinflammation leading to demyelination. Recently a combination of Δ9-tetrahydrocannabinol (THC) and Cannabidiol (CBD) extracted from Cannabis has been approved in many parts of the world to treat MS-related spasticity. THC+CBD combination was also shown to suppresses neuroinflammation, although the mechanisms remain to be further elucidated. In the current study, we demonstrate that THC+CBD combination therapy (10 mg/kg each) but not THC or CBD alone, attenuates murine experimental autoimmune encephalomyelitis (EAE) by reducing neuroinflammation and suppression of Th17 and Th1 cells. These effects were mediated through CB1 and CB2 receptors inasmuch as, THC+CBD failed to ameliorate EAE in mice deficient in CB1 and CB2. THC+CBD treatment also caused a decrease in the levels of brain infiltrating CD4+ T cells and pro-inflammatory molecules (IL-17, INF-γ, TNF-α, IL-1β, IL-6, and TBX21), while increasing anti-inflammatory phenotype such as FoxP3, STAT5b, IL-4, IL-10, and TGF-β. Also, the brain-derived cells showed increased apoptosis along with decreased percentage in G0/G1 phase with increased percentage in G2/M phase of cell cycle. miRNA microarray analysis of brain-derived CD4+ T cells revealed that THC+CBD treatment significantly down-regulated miR-21a-5p, miR-31-5p, miR-122-5p, miR-146a-5p, miR-150-5p, miR-155-5p, and miR-27b-5p while upregulating miR-706-5p and miR-7116. Pathway analysis showed that majority of the down-regulated miRs targeted molecules involved in cycle arrest and apoptosis such as CDKN2A, BCL2L11, and CCNG1, as well as anti-inflammatory molecules such as SOCS1 and FoxP3. Additionally, transfection studies involving miR-21 and use of Mir21−/− mice suggested that while this miR plays a critical role in EAE, additional miRs may also be involved in THC+CBD-mediated attenuation of EAE. Collectively, this study suggests that combination of THC+CBD suppresses neuroinflammation and attenuates clinical EAE development and that this effect is associated with changes in miRNA profile in brain-infiltrating cells.

Protective effects of CX3CR1 on autoimmune inflammation in a chronic EAE model for MS through modulation of antigen-presenting cell-related molecular MHC-II and its regulators.

Recent evidences have implicated neuroprotective effects of CX3CR1 in multiple sclerosis (MS). But whether CX3CR1 is involved in modulation of antigen-presenting cell (APC)-related molecular MHC-II and what the possible mechanism is remain unidentified. In this study, we intended to investigate the effects of CX3CR1 on MHC-II expressions on brain myeloid cells in experimental autoimmune encephalomyelitis (EAE) mice and explore the possible regulators for it. CX3CR1-deficient EAE mice were created. Disease severity, pathological damage, and the expressions of MHC-II and its mediators on myeloid cells were detected. We found that compare with wile-typed EAE mice, CX3CR1-deficient EAE mice exhibited more severe disease severity. An accumulation of CD45+CD115+Ly6C-CD11c+ cells was reserved in the affected EAE brain of CX3CR1-deficient mice, consistent with disease severity and pathological damage in the brain. The expressions of MHC-II on the brain CD45+CD115+Ly6C-CD11c+ cells of CX3CR1-deficient EAE mice were elevated, in accord with the increased protein and mRNA expressions of class II transactivator (CIITA) and interferon regulatory factor-1 (IRF-1). The findings indicated that CX3CR1 might be an important regulator for MHC-II expressions on APCs, playing a beneficial role in EAE. The mechanism was probably through regulation on the MHC-II regulators CIITA and IRF-1.

TRPM2 Exacerbates Central Nervous System Inflammation in Experimental Autoimmune Encephalomyelitis by Increasing Production of CXCL2 Chemokines.

Multiple sclerosis (MS) is a chronic inflammatory disorder of the CNS characterized by demyelination and axonal injury. Current therapies that mainly target lymphocytes do not fully meet clinical need due to the risk of severe side effects and lack of efficacy against progressive MS. Evidence suggests that MS is associated with CNS inflammation, although the underlying molecular mechanism is poorly understood. Transient receptor potential melastatin 2 (TRPM2), a Ca2+-permeable nonselective cation channel, is expressed at high levels in the brain and by immune cells, including monocyte lineage cells. Here, we show that TRPM2 plays a pathological role in experimental autoimmune encephalomyelitis (EAE), an animal model of MS. Knockout (KO) or pharmacological inhibition of TRPM2 inhibited progression of EAE and TRPM2-KO mice showed lower activation of Iba1-immunopositive monocyte lineage cells and neutrophil infiltration of the CNS than WT mice. Moreover, CXCL2 production in TRPM2-KO mice was significantly reduced at day 14, although the severity of EAE was the same as that in WT mice at that time point. In addition, we used BM chimeric mice to show that TRPM2 expressed by CNS-infiltrating macrophages contributes to progression of EAE. Because CXCL2 induces migration of neutrophils, these results indicate that reduced expression of CXCL2 in the CNS suppresses neutrophil infiltration and slows progression of EAE in TRPM2-KO mice. Together, the results suggest that TRPM2 plays an important role in progression of EAE pathology and shed light on its putative role as a therapeutic target for MS.SIGNIFICANCE STATEMENT Current therapies for multiple sclerosis (MS), which mainly target lymphocytes, carry the risk of severe side effects and lack efficacy against the progressive form of the disease. Here, we found that the transient receptor potential melastatin 2 (TRPM2) channel, which is abundantly expressed in CNS-infiltrating macrophages, plays a crucial role in development of experimental autoimmune encephalomyelitis (EAE), an animal model of MS. EAE progression was suppressed by Knockout (KO) or pharmacological inhibition of TRPM2; this was attributed to a reduction in CXCL2 chemokine production by CNS-infiltrating macrophages in TRPM2-KO mice, resulting in suppression of neutrophil infiltration into the CNS. These results reveal an important role of TRPM2 in the pathogenesis of EAE and shed light on its potential as a therapeutic target.