Pectin-stabilized nanoceria double coated with lactoferrin/chitosan for management of experimental autoimmune encephalomyelitis.

Cerium oxide nanoparticles are a unique antioxidant mimicking the activity of natural antioxidant enzymes. Previous research showed its' promising effect mitigating free radical damage in neurodegenerative disorders. However, there is still unmet therapeutic needs due to poor BBB penetration, a high accumulation in liver, kidney and spleen. This study aimed to synthesize and optimize nanoceria stabilized by natural bioactive polymers suitable for intranasal administration to manage multiple sclerosis. Among the different employed biopolymers, pectin-stabilized nanoceria exhibited the ideal properties with small particles size 87.20 ±â€¯3.43 nm, high zeta potential -56.37 ±â€¯2.39 mV and high free radical scavenging activity 85.27 ±â€¯0.07 %. Then coating was achieved for the first time by two biopolymers: lactoferrin and chitosan producing a double coated cationic nanoceria. Biological assessment involved using experimental autoimmune encephalomyelitis animal model treated in a dose of 1 mg/kg nanoceria for 15 days. Motor function testing in rats revealed 6- and 17-folds increase in latency time in rotating rod and hanging wire tests, respectively. Biochemical analysis revealed significant reduction in lipid peroxidation along with about 1-fold upgrading of the intrinsic antioxidant system. Moreover, histologic examination disclosed decreased degeneration of the brain and spinal cord of treated rats and much decreased liver toxicity.

IL-7Rα on CD4+ T cells is required for their survival and the pathogenesis of experimental autoimmune encephalomyelitis.

BACKGROUND: The IL-7 receptor alpha (IL-7Rα) binds both IL-7 and thymic stromal lymphopoietin (TSLP). IL-7Rα is essential for the development and survival of naive CD4+ T cells and their differentiation to effector/memory CD4+ T cells. Mice lacking IL-7Rα have severe lymphopenia and are resistant to experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis. However, it has been reported that IL-7Rα on peripheral CD4+ T cells is disposable for their maintenance and EAE pathogenesis, which does not align with the body of knowledge on the role of IL-7Rα in the biology of CD4+ T cells. Given that a definitive study on this important topic is lacking, we revisited it using a novel approach, an inducible knockout of the IL-7Rα gene in CD4+ T cells. METHODS: We generated Il7rafl/fl/CD4CreERT2 double transgenic mouse line (henceforth CD4ΔIl7ra), susceptible to tamoxifen-induced knockout of the IL-7Rα gene in CD4+ T cells. CD4ΔIl7ra mice were immunized with MOG35 - 55 for EAE induction and monitored for disease development. The expression of IL-7Rα, CD4+ T cell numbers, and MOG35 - 55-specific CD4+ T cell response was evaluated in the central nervous system (CNS) and lymphoid tissues by flow cytometry. Additionally, splenocytes of CD4ΔIl7ra mice were stimulated with MOG35 - 55 to assess their proliferative response and cytokine production by T helper cells. RESULTS: Loss of IL-7Rα from the surface of CD4+ T cells in CD4ΔIl7ra mice was virtually complete several days after tamoxifen treatment. The loss of IL-7Rα in CD4+ T cells led to a gradual and substantial decrease in their numbers in both non-immunized and immunized CD4ΔIl7ra mice, followed by slow repopulation up to the initial numbers. CD4ΔIl7ra mice did not develop EAE. We found a decrease in the total numbers of TNF-, IFN-γ-, IL-17 A-, and GM-CSF-producing CD4+ T cells and regulatory T cells in the spleens and CNS of immunized CD4ΔIl7ra mice. Tracking MOG35 - 55-specific CD4+ T cells revealed a significant reduction in their numbers in CD4ΔIl7ra mice and decreased proliferation and cytokine production in response to MOG35 - 55. CONCLUSION: Our study demonstrates that IL-7Rα on peripheral CD4+ T cells is essential for their maintenance, immune response, and EAE pathogenesis.

Anti-inflammatory and remyelinating effects of fexagratinib in experimental multiple sclerosis.

BACKGROUND AND PURPOSE: FGF, VEGFR-2 and CSF1R signalling pathways play a key role in the pathogenesis of multiple sclerosis (MS). Selective inhibition of FGFR by infigratinib in MOG35-55-induced experimental autoimmune encephalomyelitis (EAE) prevented severe first clinical episodes by 40%; inflammation and neurodegeneration were reduced, and remyelination was enhanced. Multi-kinase inhibition of FGFR1-3, CSFR and VEGFR-2 by fexagratinib (formerly known as AZD4547) may be more efficient in reducing inflammation, neurodegeneration and regeneration in the disease model. EXPERIMENTAL APPROACH: Female C57BL/6J mice were treated with fexagratinib (6.25 or 12.5 mg·kg-1) orally or placebo over 10 days either from time of EAE induction (prevention experiment) or onset of symptoms (suppression experiment). Effects on inflammation, neurodegeneration and remyelination were assessed at the peak of the disease (Day 18/20 post immunization) and the chronic phase of EAE (Day 41/42). KEY RESULTS: In the prevention experiment, treatment with 6.25 or 12.5 mg·kg-1 fexagratinib prevented severe first clinical episodes by 66.7% or 84.6% respectively. Mice treated with 12.5 mg·kg-1 fexagratinib hardly showed any symptoms in the chronic phase of EAE. In the suppression experiment, fexagratinib resulted in a long-lasting reduction of severe symptoms by 91 or 100%. Inflammation and demyelination were reduced, and axonal density, numbers of oligodendrocytes and their precursor cells, and remyelinated axons were increased by both experimental approaches. CONCLUSION AND IMPLICATIONS: Multi-kinase inhibition by fexagratinib in a well-tolerated dose of 1 mg·kg-1 in humans may be a promising approach to reduce inflammation and neurodegeneration, to slow down disease progression and support remyelination in patients.

High-yield production of recombinant human myelin oligodendrocyte glycoprotein in SHuffle bacteria without a refolding step.

Experimental autoimmune encephalomyelitis (EAE) is a model for central nervous system (CNS) autoimmune demyelinating diseases such as multiple sclerosis (MS) and MOG antibody-associated disease (MOGAD). Immunization with the extracellular domain of recombinant human MOG (rhMOG), which contains pathogenic antibody and T cell epitopes, induces B cell-dependent EAE for studies in mice. However, these studies have been hampered by rhMOG availability due to its insolubility when overexpressed in bacterial cells, and the requirement for inefficient denaturation and refolding. Here, we describe a new protocol for the high-yield production of soluble rhMOG in SHuffle cells, a commercially available E. coli strain engineered to facilitate disulfide bond formation in the cytoplasm. SHuffle cells can produce a soluble fraction of rhMOG yielding >100 mg/L. Analytical size exclusion chromatography multi-angle light scattering (SEC-MALS) and differential scanning fluorimetry of purified rhMOG reveals a homogeneous monomer with a high melting temperature, indicative of a well-folded protein. An in vitro proliferation assay establishes that purified rhMOG can be processed and recognized by T cells expressing a T cell receptor (TCR) specific for the immunodominant MOG35-55 peptide epitope. Lastly, immunization of wild-type, but not B cell deficient, mice with rhMOG resulted in robust induction of EAE, indicating a B cell-dependent induction. Our SHuffle cell method greatly simplifies rhMOG production by combining the high yield and speed of bacterial cell expression with enhanced disulfide bond formation and folding, which will enable further investigation of B cell-dependent EAE and expand human research of MOG in CNS demyelinating diseases.

Disruption of blood-brain barrier and endothelial-to-mesenchymal transition are attenuated by Astragalus polysaccharides mediated through upregulation of ETS1 expression in experimental autoimmune encephalomyelitis.

Blood-brain barrier (BBB) breakdown, an early hallmark of multiple sclerosis (MS), remains crucial for MS progression. Our previous works have confirmed that Astragalus polysaccharides (APS) can significantly ameliorate demyelination and disease progression in experimental autoimmune encephalomyelitis (EAE) mice. However, it remains unclear whether APS protects BBB and the potential mechanism. In this study, we found that APS effectively reduced BBB leakage in EAE mice, which was accompanied by a decreased level of endothelial-to-mesenchymal transition (EndoMT) in the central nervous system (CNS). We further induced EndoMT in the mouse brain endothelial cells (bEnd.3) by interleukin-1ß (IL-1ß) in vitro. The results showed that APS treatment could inhibit IL-1ß-induced EndoMT and endothelial cell dysfunction. In addition, the transcription factor ETS1 is a central regulator of EndoMT related to the compromise of BBB. We tested the regulation of APS on ETS1 and identified the expression of ETS1 was upregulated in both EAE mice and bEnd.3 cells by APS. ETS1 knockdown facilitated EndoMT and endothelial cell dysfunction, which completely abolished the regulatory effect of APS. Collectively, APS treatment could protect BBB integrity by inhibiting EndoMT, which might be associated with upregulating ETS1 expression. Our findings indicated that APS has potential value in the prevention of MS.

Microglia-astrocyte crosstalk is regulated by Astragalus polysaccharides mediated through suppression of Sema4D-PlexinB2 signaling in experimental autoimmune encephalomyelitis.

The crosstalk between microglia inflamed in multiple sclerosis (MIMS) and astrocytes inflamed in MS (AIMS) is a crucial factor in the formation of the central inflammatory microenvironment and neurotoxicity. Astragalus polysaccharides (APS), an important bioactive component extracted from the dried root of Astragalus, was previously found by our team to attenuate the formation of pro-inflammatory microglia and neurological dysfunction in the experimental autoimmune encephalomyelitis (EAE) mice, a classic model of MS. To investigate the effect of APS on the MIMS-AIMS crosstalk and its underlying mechanism, in this study, a mouse model of EAE and a co-culture model of microglia-astrocytes in vitro were established. It was discovered that APS can alleviate the neurological dysfunction of EAE mice and effectively inhibit the formation of MIMS and AIMS both in vivo and in vitro. Furthermore, it was found that APS can suppress the inflammatory factors of MIMS-AIMS crosstalk in EAE mice and the resulting neurotoxicity in vivo and in vitro. The Sema4D-PlexinB2 signaling is essential for MIMS-AIMS crosstalk and promotes CNS inflammation. We demonstrated that APS can inhibit this signaling in vivo and in vitro. Treatment of recombinant Sema4D protein on cultured astrocytes in vitro significantly increases pro-inflammatory and neurotoxic factors, while APS significantly inhibits them. Conversely, after knockdown of Sema4D expression in microglia, APS no longer improves the neurotoxicity from MIMS-AIMS crosstalk. Overall, these results indicate that APS may modulate MIMS-AIMS crosstalk via the Sema4D-PlexinB2 signal. This study provides a scientific basis for APS as a potential treatment candidate for demyelinating diseases.

Expression of Macrophage Colony-Stimulating Factor CSF-1 in Spinal Cord Neurons in Mice with Experimental Autoimmune Encephalomyelitis.

In mice with acute and chronic models of experimental autoimmune encephalomyelitis (EAE), a quantitative study of the dynamics of CSF-1 and IL-34 protein levels in the spinal cord and blood plasma was conducted by ELISA and the specificity of CSF-1 expression in spinal cord cells was examined by immunohistological methods. A significant increase in the level of CSF-1 in the spinal cord was detected and populations of motoneurons with intense CSF-1 immunoreactivity were identified in mice with acute and chronic EAE. The obtained results suggest a possible role of CSF-1 in the pathogenesis and progression of EAE/multiple sclerosis.

Impact of Epstein-Barr Virus Nuclear Antigen 1 on Neuroinflammation in PARK2 Knockout Mice.

This study aimed to explore the intricate relationship between mitochondrial dysfunction, infection, and neuroinflammation, focusing specifically on the impact of pathogenic epitopes of the Epstein-Barr Virus (EBV) nuclear antigen 1 (EBNA1) in a mouse model of mitochondrial dysfunctions. The investigation included female middle-aged PARK2-/- and C57BL/6J wild-type mice immunized with EBNA1386-405 or with active experimental autoimmune encephalomyelitis (EAE) induction by the myelin oligodendrocyte glycoprotein (MOG)35-55 peptide. The PARK2-/- mice developed more severe EAE than the wild-type mice. Following immunization with EBNA1386-405, only PARK2-/- exhibited symptoms resembling EAE. During the acute phase, PARK2-/- mice immunized with either MOG35-55 or EBNA1386-405 exhibited a similar infiltration of the T cells and macrophages in the spinal cord and decreased glial fibrillary acidic protein (GFAP) expression in the brain. However, the EBNA1386-405 -immunized PARK2-/- mice showed significantly increased frequencies of CD8a+ T cells and CD11c+ B cells, and distinct cytokine profiles in the periphery compared to the wild-type controls. These findings highlight the role of EBV in exacerbating inflammation, particularly in the context of mitochondrial deficiencies.

Tyzzerella nexilis strains enriched in mobile genetic elements are involved in progressive multiple sclerosis.

Multiple sclerosis (MS) is an autoimmune-demyelinating disease with an inflammatory pathology formed by self-reactive lymphocytes with activated glial cells. Progressive MS, characterized by resistance to medications, significantly differs from the non-progressive form in gut microbiome profiles. After confirming an increased abundance of "Tyzzerella nexilis" in various cohorts of progressive MS, we identified a distinct cluster of T. nexilis strains enriched in progressive MS based on long-read metagenomics. The distinct T. nexilis cluster is characterized by a large number of mobile genetic elements (MGEs) and a lack of defense systems against MGEs. Microbial genes for sulfate reduction and flagella formation with pathogenic implications are specific to this cluster. Moreover, these flagellar genes are encoded on MGEs. Mono-colonization with MGE-enriched T. nexilis made germ-free mice more susceptible to experimental autoimmune encephalomyelitis. These results indicate that the progression of MS may be promoted by MGE-enriched T. nexilis with potentially pathogenic properties.

S100A4 promotes experimental autoimmune encephalomyelitis by impacting microglial inflammation through TLR4/NF-κB signaling pathway.

Multiple sclerosis (MS) is a neurodegenerating autoimmune disease with no clinical cure currently. The calcium-binding protein S100A4 has been demonstrated to exert regulatory roles in inflammatory disorders including MS. However, the precise mechanisms by which S100A4 regulates neuroinflammation in MS remains unknown. To investigate the regulatory effect of S100A4 on microglial inflammation and its impact on neuroinflammation, the mouse-derived microglia cell line BV2 cells were infected with lentivirus to knockout S100A4 for in vitro studies. Wild-type (WT) and S100A4-/- mice were induced to develop experimental autoimmune encephalomyelitis (EAE), an animal model of MS, for in vivo investigation. Results indicated that the frequencies of microglia in the spinal cord and brain and the expression of S100A4 in these tissues varied kinetically along with the progression of the disease in mice with EAE. S100A4-/- mice presented ameliorated clinical scores of EAE and exhibited less severe EAE signs, including inflammatory cell infiltration in the spinal cord and brain and demyelination of the spinal cord. Moreover, these mice demonstrated overall reduced levels of inflammatory cytokines in the spinal cord and brain. Compromised systematic inflammatory responses including circulating cytokines and frequencies of immune cells in the spleen were also observed in these mice. In addition, both exogenous and endogenous S100A4 could promote the microglial inflammation, affect the polarization of microglia and enhance inflamed microglia-mediated apoptosis of neuronal cells through TLR4/NF-κB signaling pathway. Thus, S100A4 may participate in the regulation of neuroinflammation at least partly through regulating the inflammation of microglia.

Upregulated expression of ubiquitin ligase TRIM21 promotes PKM2 nuclear translocation and astrocyte activation in experimental autoimmune encephalomyelitis.

Reactive astrocytes play critical roles in the occurrence of various neurological diseases such as multiple sclerosis. Activation of astrocytes is often accompanied by a glycolysis-dominant metabolic switch. However, the role and molecular mechanism of metabolic reprogramming in activation of astrocytes have not been clarified. Here, we found that PKM2, a rate-limiting enzyme of glycolysis, displayed nuclear translocation in astrocytes of EAE (experimental autoimmune encephalomyelitis) mice, an animal model of multiple sclerosis. Prevention of PKM2 nuclear import by DASA-58 significantly reduced the activation of mice primary astrocytes, which was observed by decreased proliferation, glycolysis and secretion of inflammatory cytokines. Most importantly, we identified the ubiquitination-mediated regulation of PKM2 nuclear import by ubiquitin ligase TRIM21. TRIM21 interacted with PKM2, promoted its nuclear translocation and stimulated its nuclear activity to phosphorylate STAT3, NF-κB and interact with c-myc. Further single-cell RNA sequencing and immunofluorescence staining demonstrated that TRIM21 expression was upregulated in astrocytes of EAE. TRIM21 overexpressing in mice primary astrocytes enhanced PKM2-dependent glycolysis and proliferation, which could be reversed by DASA-58. Moreover, intracerebroventricular injection of a lentiviral vector to knockdown TRIM21 in astrocytes or intraperitoneal injection of TEPP-46, which inhibit the nuclear translocation of PKM2, effectively decreased disease severity, CNS inflammation and demyelination in EAE. Collectively, our study provides novel insights into the pathological function of nuclear glycolytic enzyme PKM2 and ubiquitination-mediated regulatory mechanism that are involved in astrocyte activation. Targeting this axis may be a potential therapeutic strategy for the treatment of astrocyte-involved neurological disease.

Simvastatin alleviates experimental autoimmune encephalomyelitis through regulating the balance of Th17 and Treg in mice.

The aim of this study was to elucidate the therapeutic effect of simvastatin on experimental autoimmune encephalomyelitis (EAE) by regulating the balance between Th17 and Treg cells in mice. C57BL/6 mice were randomly divided into four groups: normal group, EAE group, simvastatin (2 and 10 mg/kg) group, and AG490 group (with AG490 serving as the positive control). Neurological function scores of mice were assessed daily. The four groups received treatments of normal saline, normal saline, and simvastatin (2 and 10 mg/kg), respectively. In the AG490 group, mice were injected intraperitoneally with AG490 (1 mg) every other day, and treatment was halted after 3 weeks. The spinal cord was stained with hematoxylin and eosin (H&E), and immunohistochemical staining for retinoic acid receptor-related orphan receptor γ(RORγ) and Foxp3 (Foxp3) was performed. Spleen samples were taken for Th17 and Treg analysis using flow cytometry. The levels of interleukin-17 and transforming growth factor-ß (TGF-ß) were detected using enzyme-linked immunosorbent assay (ELISA). In the simvastatin and AG490 groups, recovery from neurological impairment was earlier compared to the EAE group, and the symptoms were notably improved. Both simvastatin and AG490 reduced focal inflammation, decreased RORγ-positive cell infiltration, and significantly increased the number of FOXP3-positive cells. The number of Th17 cells and the level of IL-17 in the spleen were decreased in the simvastatin and AG490 treatment groups, while the number of Treg cells and TGF-ß levels were significantly increased across all treatment groups. Simvastatin exhibits anti-inflammatory and immunomodulatory effects, potentially alleviating symptoms of neurological dysfunction of EAE. Regulating the balance between Th17 and Treg may represent a therapeutic mechanism for simvastatin in treating EAE.

Life history of a brain autoreactive T cell: From thymus through intestine to blood-brain barrier and brain lesion.

Brain antigen-specific autoreactive T cells seem to play a key role in inducing inflammation in the central nervous system (CNS), a characteristic feature of human multiple sclerosis (MS). These T cells are generated within the thymus, where they escape negative selection and become integrated into the peripheral immune repertoire of immune cells. Typically, these autoreactive T cells rest in the periphery without attacking the CNS. When autoimmune T cells enter gut-associated lymphatic tissue (GALT), they may be stimulated by the microbiota and its metabolites. After activation, the cells migrate into the CNS through the blood‒brain barrier, become reactivated upon interacting with local antigen-presenting cells, and induce inflammatory lesions within the brain parenchyma. This review describes how microbiota influence autoreactive T cells during their life, starting in the thymus, migrating through the periphery and inducing inflammation in their target organ, the CNS.

Discussion of spinal cord neurons apoptosis and neuroprotection mechanism of NGF gene transfection mediated by recombinant adenovirus in EAE mice.

To investigate the spinal cord neuron apoptosis and neuroprotective mechanism of nerve growth factorganismsor (NGF) gene mediated by recombinant adenovirus (Ad-NGF) via peripheral transfection in mice with experimental autoimmune encephalomyelitis (EAE). Forty healthy female C57BL/6 mice were randomly divided into a control group, adenovirus (AdV) group, EAE group, and Ad-NGF transfection group; the control group received no treatment; the AdV group received adenovirus injection via the tail vein; the EAE and Ad-NGF transfection groups were induced with experimental autoimmune encephalomyelitis (EAE) using myelin oligodendrocyte glycoprotein 35-55 (MOG35-55), Ad-NGF transfection group received Ad-NGF injection via the tail vein, and daily neurological impairment scores were obtained. AQThe TUNEL method was employed to observe spinal neuron apoptosis in each group of mice; protein immunoblotting (western blot) and RT-PCR were used to measure NGF levels in the spinal cord tissues of each group, and western blotting was used to assess levels of cleaved caspase-3, Bax, and Bcl-2. ELISA and RT-PCR were employed to detect protein and mRNA levels of neuron-specific enolase (NSE) in spinal cord tissues, respectively. The control group and AdV mice did not develop symptoms. Compared to the EAE group, in the Ad-NGF transfection group, neurological function scores, TUNEL-positive cell counts, the ratio of NeuN + TUNEL to NeuN, levels of Bax and cleaved caspase-3 apoptotic proteins were significantly reduced, while Bcl-2 protein expression was increased. Expression levels of NGF, NGF-mRNA, NSE, and NSE-mRNA in spinal cord tissues were significantly elevated (P < 0.01). Immunofluorescence labeling revealed a significant punctate aggregation of apoptotic cells in spinal neurons of the EAE group, while the aggregation phenomenon was less pronounced in the Ad-NGF transfection group. Ad-NGF transfected by the periphery has a protective effect on spinal cord neurons in EAE mice by up-regulation NGF level, down-regulating apoptotic protein Caspase-3 in spinal cord neurons, inhibiting spinal cord neuron apoptosis and promoting NSE expression.

Rigid crosslinking of the CD3 complex leads to superior T cell stimulation.

Functionally bivalent non-covalent Fab dimers (Bi-Fabs) specific for the TCR/CD3 complex promote CD3 signaling on T cells. While comparing functional responses to stimulation with Bi-Fab, F(ab')2 or mAb specific for the same CD3 epitope, we observed fratricide requiring anti-CD3 bridging of adjacent T cells. Surprisingly, anti-CD3 Bi-Fab ranked first in fratricide potency, followed by anti-CD3 F(ab')2 and anti-CD3 mAb. Low resolution structural studies revealed anti-CD3 Bi-Fabs and F(ab')2 adopt similar global shapes with CD3-binding sites oriented outward. However, under molecular dynamic simulations, anti-CD3 Bi-Fabs crosslinked CD3 more rigidly than F(ab')2. Furthermore, molecular modelling of Bi-Fab and F(ab')2 binding to CD3 predicted crosslinking of T cell antigen receptors located in opposing plasma membrane domains, a feature fitting with T cell fratricide observed. Thus, increasing rigidity of Fab-CD3 crosslinking between opposing effector-target pairs may result in stronger T cell effector function. These findings could guide improving clinical performance of bi-specific anti-CD3 drugs.

The Protective Effect of Astragalus Polysaccharide on Experimental Autoimmune Encephalomyelitis in Mice by Activating the AMPK/JAK/STAT3/Arginase-1 Signaling Pathway.

OBJECTIVE: This study aimed to investigate the protective effect and mechanism of Astragalus polysaccharide (APS) on autoimmune encephalomyelitis. METHODS: C57BL/6 mice were randomly divided into the blank control group, EAE group, and APS intervention group (n=15/group). The Experimental Autoimmune Encephalomyelitis (EAE) mouse model was established by active immunization. The pathological changes in the spinal cord were evaluated by Hematoxylin-eosin (HE) and Luxol Fast Blue (LFB) staining. The number of CD11b+ Gr-1+ myeloid-derived suppressor cells (MDSCs) in the spleen tissues of mice in each group was determined by immunofluorescence staining. The expression of Arginase-1 in the spinal cord and spleen of each group was detected by immunofluorescence double staining. The TNF-α, IL-6, and Arginase-1 levels in the spleen were detected by ELISA assay. A western blot was used to detect the protein expression of the AMPK/JAK/STAT3/Arginase-1 signaling pathway. RESULTS: After the intervention of APS, the incidence of autoimmune encephalomyelitis in mice of the APS group was significantly lower than that in the EAE group, and the intervention of APS could significantly delay the onset time in the EAE mice, and the score of neurological function deficit in mice was significantly lower than that in EAE group (P < 0.05). APS intervention could reduce myelin loss and improve the inflammatory response of EAE mice. Moreover, it could induce the expression of CD11b+ GR-1 + bone MDSCs in the spleen and increase the expression of Arginase-1 in the spinal cord and spleen. This study further demonstrated that APS can protect EAE mice by activating the AMPK/JAK/STAT3/Arginase-1 signaling pathway. CONCLUSION: After the intervention of APS, myelin loss and inflammatory response of EAE mice were effectively controlled. APS promoted the secretion of Arginase-1 by activating MDSCs and inhibited CD4+T cells by activating AMPK/JAK/STAT3/Arginase-1 signaling pathway, thus improving the clinical symptoms and disease progression of EAE mice.

CYP7B1 deficiency impairs myeloid cell activation in autoimmune disease of the central nervous system.

Dysregulation of cholesterol metabolism underlies neurodegenerative disease and is increasingly implicated in neuroinflammatory diseases, such as multiple sclerosis (MS). Cytochrome P450 family 7 subfamily B member 1 (CYP7B1) is a key enzyme in alternative cholesterol metabolism. A recessive mutation in the gene CYP7B1 is known to cause a neurodegenerative disease, hereditary spastic paraplegia type 5 and oxysterol accumulation. However, the role of CYP7B1 in neuroinflammation has been little revealed. In this study, we induced experimental autoimmune encephalomyelitis (EAE), as a murine model of MS, using CYP7B1 homozygous knockout (KO) mice. We found that CYP7B1 deficiency can significantly attenuate EAE severity. CYP7B1 deficiency is sufficient to reduce leukocyte infiltration into the central nervous system, suppress proliferation of pathogenic CD4+ T cells, and decrease myeloid cell activation during EAE. Additionally, live-animal imaging targeting translocator protein expression, an outer mitochondrial membrane protein biomarker of neuroinflammation, showed that CYP7B1 deficiency results in suppressed neuroinflammation. Using human monocyte-derived microglia-like cellular disease model and primary microglia of CYP7B1 KO mice, we also found that activation of microglia of CYP7B1 deficiency was impaired. These cumulative results suggest that CYP7B1 can regulate neuroinflammation, thus providing potential new targets for therapeutic intervention.

Formyl peptide receptor 2 regulates dendritic cell metabolism and Th17 cell differentiation during neuroinflammation.

Formyl peptide receptor 2 (FPR2) is a receptor for formylated peptides and specific pro-resolving mediators, and is involved in various inflammatory processes. Here, we aimed to elucidate the role of FPR2 in dendritic cell (DC) function and autoimmunity-related central nervous system (CNS) inflammation by using the experimental autoimmune encephalomyelitis (EAE) model. EAE induction was accompanied by increased Fpr2 mRNA expression in the spinal cord. FPR2-deficient (Fpr2 KO) mice displayed delayed onset of EAE compared to wild-type (WT) mice, associated with reduced frequencies of Th17 cells in the inflamed spinal cord at the early stage of the disease. However, FPR2 deficiency did not affect EAE severity after the disease reached its peak. FPR2 deficiency in mature DCs resulted in decreased expression of Th17 polarizing cytokines IL6, IL23p19, IL1ß, and thereby diminished the DC-mediated activation of Th17 cell differentiation. LPS-activated FPR2-deficient DCs showed upregulated Nos2 expression and nitric oxide (NO) production, as well as reduced oxygen consumption rate and impaired mitochondrial function, including decreased mitochondrial superoxide levels, lower mitochondrial membrane potential and diminished expression of genes related to the tricarboxylic acid cycle and genes related to the electron transport chain, as compared to WT DCs. Treatment with a NO inhibitor reversed the reduced Th17 cell differentiation in the presence of FPR2-deficient DCs. Together, by regulating DC metabolism, FPR2 enhances the production of DC-derived Th17-polarizing cytokines and hence Th17 cell differentiation in the context of neuroinflammation.

The chemically stable analogue of resolvin D1 ameliorates experimental autoimmune encephalomyelitis by mediating the resolution of inflammation.

While Resolvin D1 (RvD1) shows promise in resolving inflammation in experimental autoimmune encephalomyelitis (EAE), its pro-resolving roles on dendritic cells (DCs) remain unknown, and the chemical instability of RvD1 poses significant challenges to its drug development. This study aims to investigate whether 4-(2'-methoxyphenyl)-1-[2'-[N-(2″-pyridinyl)-p-fluorobenzamido]ethyl]piperazine (p-MPPF), a novel chemically stable analogue of RvD1, can play a pro-resolving role in EAE, particularly on DCs, and if p-MPPF could serve as a potential substitute for RvD1. We showed that both RvD1 and p-MPPF mediated the resolution of inflammation in EAE, as evidenced by ameliorated EAE progression, attenuated pathological changes in the spinal cord, altered cytokine expression profile in serum, and reduced proportion of pro-inflammatory immune cells in the spleen. Utilizing DCs derived from both the spleen and bone marrow of EAE, our investigation showed that RvD1 and p-MPPF prevented DC maturation, decreased pro-inflammatory cytokine secretion, shifted DCs away from a pro-inflammatory phenotype, increased the phagocytosis capacity of DCs, and suppressed their ability to induce differentiation of CD4+ T cells into Th1 and Th17 subsets. For underlying intracellular mechanisms, we found that RvD1 and p-MPPF down-regulated the lactate dehydrogenase A signaling pathways. Comparisons between RvD1 and p-MPPF showed that they exerted overlapped pro-resolving effects to a large extent. This study demonstrates that both RvD1 and p-MPPF exert therapeutic effects on EAE by mediating inflammation resolution, which is closely associated with modulating DC immune function towards a tolerogenic phenotype. SPM mimetics may serve as a more promising therapeutic drug.

Obesity intensifies sex-specific interferon signaling to selectively worsen central nervous system autoimmunity in females.

Obesity has been implicated in the rise of autoimmunity in women. We report that obesity induces a serum protein signature that is associated with T helper 1 (Th1), interleukin (IL)-17, and multiple sclerosis (MS) signaling pathways selectively in human females. Females, but not male mice, subjected to diet-induced overweightness/obesity (DIO) exhibited upregulated Th1/IL-17 inflammation in the central nervous system during experimental autoimmune encephalomyelitis, a model of MS. This was associated with worsened disability and a heightened expansion of myelin-specific Th1 cells in the peripheral lymphoid organs. Moreover, at steady state, DIO increased serum levels of interferon (IFN)-α and potentiated STAT1 expression and IFN-γ production by naive CD4+ T cells uniquely in female mice. This T cell phenotype was driven by increased adiposity and was prevented by the removal of ovaries or knockdown of the type I IFN receptor in T cells. Our findings offer a mechanistic explanation of how obesity enhances autoimmunity.