Absence of IFN-γ increases brain pathology in experimental autoimmune encephalomyelitis-susceptible DRB1*0301.DQ8 HLA transgenic mice through secretion of proinflammatory cytokine IL-17 and induction of pathogenic monocytes/microglia into the central nervous system

Mac-1 regulates disease stage-specific immunosuppression via the nitric oxide pathway in autoimmune disease

Integrin Mac-1 plays a critical role in the development of multiple sclerosis (MS); however, the underlying mechanism is not fully understood. Here, we developed a myeloid-specific Mac-1-deficient mouse. Using an experimental autoimmune encephalomyelitis (EAE) mouse model of MS, we report that Mac-1 on myeloid cells is key to disease development. Our data reveal that myeloid-specific Mac-1 significantly increases EAE severity and hinders disease regression. Loss of Mac-1 increases Gr-1+ cells in peripheral tissues and the CNS and preferably accelerates the transition of Ly6Chi monocytes from a pro-inflammatory to an immunosuppressive phenotype in a disease stage-dependent manner. Mechanistically, our results demonstrate that Mac-1 suppresses interferon-γ production and prevents monocytes from acquiring immunosuppressive functions by reducing the expression of iNOS, IDO, and CD84. Administration of a NOS-specific inhibitor in Mac-1-deficient EAE mice abolishes disease regression. These insights could help develop Mac-1-targeting strategies for better treatment of MS.

HLA-transgenic mouse models to study autoimmune central nervous system diseases

It is known that certain human leukocyte antigen (HLA) genes are associated with autoimmune central nervous system (CNS) diseases, such as multiple sclerosis (MS), but their exact role in disease susceptibility and etiopathogenesis remains unclear. The best studied HLA-associated autoimmune CNS disease is MS, and thus will be the primary focus of this review. Other HLA-associated autoimmune CNS diseases, such as autoimmune encephalitis and neuromyelitis optica will be discussed. The lack of animal models to accurately capture the complex human autoimmune response remains a major challenge. HLA transgenic (tg) mice provide researchers with powerful tools to investigate the underlying mechanisms promoting susceptibility and progression of HLA-associated autoimmune CNS diseases, as well as for elucidating the myelin epitopes potentially targeted by T cells in autoimmune disease patients. We will discuss the potential role(s) of autoimmune disease-associated HLA alleles in autoimmune CNS diseases and highlight information provided by studies using HLA tg mice to investigate the underlying pathological mechanisms and opportunities to use these models for development of novel therapies.

The Mechanisms of Altered Blood-Brain Barrier Permeability in CD19 CAR T-Cell Recipients

Cluster of differentiation 19 (CD19) chimeric antigen receptor (CAR) T cells are a highly effective immunotherapy for relapsed and refractory B-cell malignancies, but their utility can be limited by the development of immune effector cell-associated neurotoxicity syndrome (ICANS). The recent discovery of CD19 expression on the pericytes in the blood-brain barrier (BBB) suggests an important off-target mechanism for ICANS development. In addition, the release of systemic cytokines stimulated by the engagement of CD19 with the CAR T cells can cause endothelial activation and decreased expression of tight junction molecules, further damaging the integrity of the BBB. Once within the brain microenvironment, cytokines trigger a cytokine-specific cascade of neuroinflammatory responses, which manifest clinically as a spectrum of neurological changes. Brain imaging is frequently negative or nonspecific, and treatment involves close neurologic monitoring, supportive care, interleukin antagonists, and steroids. The goal of this review is to inform readers about the normal development and microstructure of the BBB, its unique susceptibility to CD19 CAR T cells, the role of individual cytokines on specific elements of the brain's microstructural environment, and the clinical and imaging manifestations of ICANS. Our review will link cellular pathophysiology with the clinical and radiological manifestations of a complex clinical entity.

Concurrent Brain Subregion Microgliosis in an HLA-II Mouse Model of Group A Streptococcal Skin Infection

The broad range of clinical manifestations and life-threatening infections caused by the Gram-positive bacterium, Streptococcus pyogenes or Group A Streptococcus (GAS), remains a significant concern to public health, with a subset of individuals developing neurological complications. Here, we examined the concurrent neuroimmune effects of subcutaneous GAS infections in an HLA-Class II (HLA) transgenic mouse model of subcutaneous GAS infection. To investigate changes in the skin-brain axis, HLA-DQ8 (DQA1*0301/DQB1*0302) mice (DQ8) were randomly divided into three groups: uninfected controls (No Inf), GAS infected and untreated (No Tx), and GAS infected with a resolution by clindamycin (CLN) treatment (CLN Tx) (10 mg/kg/5 days) and were monitored for 16 days post-infection. While the skin GAS burden was significantly reduced by CLN, the cortical and hippocampal GAS burden in the male DQ8 mice was not significantly reduced with CLN. Immunoreactivity to anti-GAS antibody revealed the presence of GAS bacteria in the vicinity of the neuronal nucleus in the neocortex of both No Tx and CLN Tx male DQ8 mice. GAS infection-mediated cortical cytokine changes were modest; however, compared to No Inf or No Tx groups, a significant increase in IL-2, IL-13, IL-22, and IL-10 levels was observed in CLN Tx females despite the lack of GAS burden. Western blot analysis of cortical and hippocampal homogenates showed significantly higher ionized calcium-binding adaptor-1 (Iba-1, microglia marker) protein levels in No Tx females and males and CLN Tx males compared to the No Inf group. Immunohistochemical analysis showed that Iba-1 immunoreactivity in the hippocampal CA3 and CA1 subregions was significantly higher in the CLN Tx males compared to the No Tx group. Our data support the possibility that the subcutaneous GAS infection communicates to the brain and is characterized by intraneuronal GAS sequestration, brain cytokine changes, Iba-1 protein levels, and concurrent CA3 and CA1 subregion-specific microgliosis, even without bacteremia.

Development and Optimization of a Target Engagement Model of Brain IDO Inhibition for Alzheimer's Disease

BACKGROUND

Indoleamine 2,3-dioxygenase (IDO1) inhibition is a promising target as an Alzheimer's disease (AD) Disease-modifying therapy capable of downregulating immunopathic neuroinflammatory processes.

METHODS

To aid in the development of IDO inhibitors as potential AD therapeutics, we optimized a lipopolysaccharide (LPS) based mouse model of brain IDO1 inhibition by examining the dosedependent and time-course of the brain kynurenine:tryptophan (K:T) ratio to LPS via intraperitoneal dosing.

RESULTS

We determined the optimal LPS dose to increase IDO1 activity in the brain, and the ideal time point to quantify the brain K:T ratio after LPS administration. We then used a brain penetrant tool compound, EOS200271, to validate the model, determine the optimal dosing profile and found that a complete rescue of the K:T ratio was possible with the tool compound.

CONCLUSION

This LPS-based model of IDO1 target engagement is a useful tool that can be used in the development of brain penetrant IDO1 inhibitors for AD. A limitation of the present study is the lack of quantification of potential clinically relevant biomarkers in this model, which could be addressed in future studies.

Administration of Human Derived Upper gut Commensal Prevotella histicola delays the onset of type 1 diabetes in NOD mice

BACKGROUND

Type 1 diabetes (T1D) is an autoimmune disease that is increasing in prevalence worldwide. One of the contributing factors to the pathogenesis of T1D is the composition of the intestinal microbiota, as has been demonstrated. in T1D patients, with some studies demonstrating a deficiency in their levels of Prevotella. We have isolated a strain of Prevotella histicola from a duodenal biopsy that has anti-inflammatory properties, and in addition, alters the development of autoimmune diseases in mouse models. Therefore, our hypothesis is that the oral administration of P. histicola might delay the development of T1D in the non-obese diabetic (NOD) mice. To assess this, we used the following materials and methods. Female NOD mice (ages 5-8 weeks) were administered every other day P. histicola that was cultured in-house. Blood glucose levels were measured every other week. Mice were sacrificed at various time points for histopathological analysis of the pancreas. Modulation of immune response by the commensal was tested by analyzing regulatory T-cells and NKp46+ cells using flow cytometry and intestinal cytokine mRNA transcript levels using quantitative RT-PCR. For microbial composition, 16 s rRNA gene analysis was conducted on stool samples collected at various time points.

RESULTS

Administration of P. histicola in NOD mice delayed the onset of T1D. Beta diversity in the fecal microbiomes demonstrated that the microbial composition of the mice administered P. histicola was different from those that were not treated. Treatment with P. histicola led to a significant increase in regulatory T cells with a concomitant decrease in NKp46+ cells in the pancreatic lymph nodes as compared to the untreated group after 5 weeks of treatment.

CONCLUSIONS

These observations suggest that P. histicola treatment delayed onset of diabetes by increasing the levels of regulatory T cells in the pancreatic lymph nodes. This preliminary work supports the rationale that enteral exposure to a non pathogenic commensal P. histicola be tested as a future therapy for T1D.

Isoflavone diet ameliorates experimental autoimmune encephalomyelitis through modulation of gut bacteria depleted in patients with multiple sclerosis

The gut microbiota is a potential environmental factor that influences the development of multiple sclerosis (MS). We and others have demonstrated that patients with MS and healthy individuals have distinct gut microbiomes. However, the pathogenic relevance of these differences remains unclear. Previously, we showed that bacteria that metabolize isoflavones are less abundant in patients with MS, suggesting that isoflavone-metabolizing bacteria might provide protection against MS. Here, using a mouse model of MS, we report that an isoflavone diet provides protection against disease, which is dependent on the presence of isoflavone-metabolizing bacteria and their metabolite equol. Notably, the composition of the gut microbiome in mice fed an isoflavone diet exhibited parallels to healthy human donors, whereas the composition in those fed an isoflavone-free diet exhibited parallels to patients with MS. Collectively, our study provides evidence that dietary-induced gut microbial changes alleviate disease severity and may contribute to MS pathogenesis.

Interferon-γ Involvement in the Neuroinflammation Associated with Parkinson's Disease and L-DOPA-Induced Dyskinesia

Interferon-γ (IFN-γ) is a proinflammatory cytokine that activates glial cells. IFN-γ is increased in the plasma and brain of Parkinson's disease patients, suggesting its potential role in the disease. We investigated whether the IFN-γ deficiency could interfere with nigrostriatal degeneration induced by the neurotoxin 6-hydroxydopamine, L-DOPA-induced dyskinesia, and the neuroinflammatory features as astrogliosis, microgliosis, and induced nitric oxide synthase (iNOS) immunoreactivity induced by L-DOPA treatment. Wild type (WT) and IFN-γ knockout (IFN-γ/KO) mice received unilateral striatal microinjections of 6-hydroxydopamine. Animals were sacrificed 1, 3, 7, and 21 days after lesions. Additional group of WT and IFN-γ/KO parkinsonian mice, after 3 weeks of neurotoxin injection, received L-DOPA (intraperitoneally, for 21 days) resulting in dyskinetic-like behavior. Tyrosine hydroxylase immunostaining indicated the starting of dopaminergic lesion since the first day past toxin administration, progressively increased until the third day when it stabilized. There was no difference in the lesion and L-DOPA-induced dyskinesia intensity between WT and IFN-γ/KO mice. Remarkably, IFN-γ/KO mice treated with L-DOPA presented in the lesioned striatum an increase of iNOS and glial fibrilary acid protein (GFAP) density, compared with the WT group. Morphological analysis revealed the rise of astrocytes and microglia reactivity in IFN-γ/KO mice exibiting dyskinesia. In conclusion, IFN-γ/KO mice presented an intensification of the inflammatory reaction accompanying L-DOPA treatment and suggest that iNOS and GFAP increase, and the activation of astrocytes and microglia induced afterward L-DOPA treatment was IFN-γ independent events. Intriguingly, IFN-γ absence did not affect the degeneration of dopaminergic neurons or LID development.

The HLA-DR4-DQ8 phenotype of the recipient is associated with increased mortality after kidney transplantation

The importance of the human leukocyte antigen (HLA) system in kidney transplantation is well-known, but it remains unexplored if patient HLA antigens constitute independent risk factors in complications after transplantation. We hypothesized that specific HLA class II phenotypes associated with immune-mediated disease (HLA-IMD) predispose to immunological activity and/or complications after kidney transplantation. Based on the literature we defined HLA-DR2-DQ6; -DR3-DQ2 and -DR4-DQ8 as HLA-IMD phenotypes. We investigated associations between HLA-IMD phenotypes in patients, biomarkers of systemic chronic inflammation at the time of transplantation, and the outcome after kidney transplantation in a retrospective cohort study of 611 kidney transplanted patients. The HLA-IMD phenotypes were associated with higher levels of biomarkers of systemic inflammation. The HLA-DR4-DQ8 phenotype was associated with mortality after transplantation in Cox analyses with adjustments for confounders. Data support the hypothesis that specific HLA class II phenotypes affects immunological pathways that determine the midterm clinical outcome of kidney transplantation.

Altered Cytokine Endotoxin Responses in Neonatal Encephalopathy Predict MRI Outcomes

Background: Neonatal encephalopathy (NE) is associated with adverse neurodevelopmental outcome and is linked with systemic inflammation. Pro-inflammatory and anti-inflammatory cytokines are known to play a role in the pathology of NE by activating innate immune cells. Methods: Eighty-seven infants were enrolled including 53 infants with NE of whom 52 received therapeutic hypothermia (TH) and 34 term infant healthy controls (TC). Whole blood sampling was performed in the first 4 days of life, and a 14-spot ELISA Multiplex Cytokine Array was carried out on baseline samples or after stimulation with lipopolysaccharide (LPS) as an additional inflammatory stimulus. The cytokine medians were examined for differences between infants with NE and healthy TC; and then short-term outcomes of Sarnat stage, seizures, and MRI brain were examined within the NE group. The potential of LPS stimulation to predict abnormal MRI was explored using receiver operating characteristic (ROC) curves. Results: At baseline, infants with NE had significantly higher levels of erythropoietin (Epo), interleukin (IL)-6, and IL-1ra and significantly lower vascular endothelial growth factor (VEGF) than had controls. All cytokines were increased after LPS stimulation in infants with NE with an excessive Epo and IL-1ra response than in controls. Infants with NE had lower IL-8, IL-2, IL-6, tumor necrosis factor (TNF)-α, granulocyte-macrophage colony-stimulating factor (GM-CSF), VEGF, and interferon (IFN)-γ than controls had following LPS. GM-CSF and IFN-γ, IL-1β, IL-1ra, and VEGF were higher on days 1-2 in NE infants with abnormal neuroimaging. GM-CSF, IFN-γ, and TNF-α levels with LPS stimulation were different upon stimulation between normal and abnormal neuroimaging. TNF-α is the only strong cytokine predictor both pre- and post-LPS stimulation of abnormal brain imaging. Conclusions: Altered cytokine responses are found in infants with NE vs. controls, and more significant differences are unmasked by the additional stimulus of LPS, which potentially improves the predictive power of these cytokines for the detection of abnormal MRIs. Infants with NE undergoing TH demonstrate both trained immunity and tolerance, and understanding these responses will facilitate adjunctive immunomodulatory treatments.

Human Commensal Prevotella histicola Ameliorates Disease as Effectively as Interferon-Beta in the Experimental Autoimmune Encephalomyelitis

Gut microbiota has emerged as an important environmental factor in the pathobiology of multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system (CNS). Both genetic and environmental factors have been shown to play an important role in MS. Among genetic factors, the human leukocyte antigen (HLA) class II allele such as HLA-DR2, DR3, DR4, DQ6, and DQ8 show the association with the MS. We have previously used transgenic mice expressing MS susceptible HLA class II allele such as HLA-DR2, DR3, DQ6, and DQ8 to validate significance of HLA alleles in MS. Although environmental factors contribute to 2/3 of MS risk, less is known about them. Gut microbiota is emerging as an imporatnt environmental factor in MS pathogenesis. We and others have shown that MS patients have distinct gut microbiota compared to healthy control (HC) with a lower abundance of Prevotella. Additionally, the abundance of Prevotella increased in patients receiving disease-modifying therapies (DMTs) such as Copaxone and/or Interferon-beta (IFNβ). We have previously identified a specific strain of Prevotella (Prevotella histicola), which can suppress experimental autoimmune encephalomyelitis (EAE) disease in HLA-DR3.DQ8 transgenic mice. Since Interferon-β-1b [IFNβ (Betaseron)] is a major DMTs used in MS patients, we hypothesized that treatment with the combination of P. histicola and IFNβ would have an additive effect on the disease suppression. We observed that treatment with P. histicola suppressed disease as effectively as IFNβ. Surprisingly, the combination of P. histicola and IFNβ was not more effective than either treatment alone. P. histicola alone or in combination with IFNβ increased the frequency and number of CD4+FoxP3+ regulatory T cells in the gut-associated lymphoid tissue (GALT). Treatment with P. histicola alone, IFNβ alone, and in the combination decreased frequency of pro-inflammatory IFN-γ and IL17-producing CD4+ T cells in the CNS. Additionally, P. histicola alone or IFNβ alone or the combination treatments decreased CNS pathology, characterized by reduced microglia and astrocytic activation. In conclusion, our study indicates that the human gut commensal P. histicola can suppress disease as effectively as commonly used MS drug IFNβ and may provide an alternative treatment option for MS patients.

Effects of co-administration of rapamycin and evening primrose/hemp seed oil supplement on immunologic factors and cell membrane fatty acids in experimental autoimmune encephalomyelitis

BACKGROUND

The immune response is influenced by the administration of omega-3 polyunsaturated fatty acids (PUFA). Multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE) are affected by PUFA. The combination of evening primrose/hemp seed oil (EPO/HSO) has essential fatty acids (EFAs) for human optimal health due to the favorable ratio of omega-6/omega-3 and antioxidantal properties. The study was conducted to evaluate the effects of EPO/HSO on improving the membrane fatty acids composition of spleen and blood cells and immunologic factors in compared to rapamycin (RAPA) in the EAE model.

METHODS AND MATERIALS

Chronic-EAE was induced by induction of MOG in C57BL/6J mice (female, age: 6-8 weeks, weight 18-21). Mice were assigned to 5 groups (6/group) to evaluate the therapeutic effects of EPO/HSO supplement in comparison with rapamycin: A group; EPO/HSO + RAPA, B group; RAPA, C group; EPO/HSO. Results were compared to two control groups (EAE and naive). The fatty acid profile of the spleen and blood cell membrane was evaluated. Real-time-polymerase chain reaction was used for the evaluate the genes expression levels of interleukin (IL) -4, IL-5, and IL-13 in lymphocytes. Also, IL-4 of serum was evaluated by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Our findings indicated that EPO/HSO therapy significantly increased the percentage of essential fatty acids in cell membrane of the spleen and blood. The relative expression of IL-4, IL-5, and IL-13 genes in lymphocytes and serum level of IL-4 was significantly increased in the HSO/EPO treated group versus other groups.

CONCLUSION

These results point to potential therapeutic effects on the repair of the structure of cell membranes and suppression of inflammation by EPO/HSO in EAE.

HLA transgenic mice: application in reproducing idiosyncratic drug toxicity

Various types of transgenic mice carrying either class I or II human leukocyte antigen (HLA) molecules are readily available, and reports describing their use in a variety of studies have been published for more than 30 years. Examples of their use include the discovery of HLA-specific antigens against viral infection as well as the reproduction of HLA-mediated autoimmune diseases for the development of therapeutic strategies. Recently, HLA transgenic mice have been used to reproduce HLA-mediated idiosyncratic drug toxicity (IDT), a rare and unpredictable adverse drug reaction that can result in death. For example, abacavir-induced IDT has successfully been reproduced in HLA-B*57:01 transgenic mice. Several reports using HLA transgenic mice for IDT have proven the utility of this concept for the evaluation of IDT using various HLA allele combinations and drugs. It has become apparent that such models may be a valuable tool to investigate the mechanisms underlying HLA-mediated IDT. This review summarizes the latest findings in the area of HLA transgenic mouse models and discusses the current challenges that must be overcome to maximize the potential of this unique animal model.

GM-CSF induces noninflammatory proliferation of microglia and disturbs electrical neuronal network rhythms in situ

Background

The granulocyte-macrophage colony-stimulating factor (GM-CSF) (or CSF-2) is involved in myeloid cell growth and differentiation, and, possibly, a major mediator of inflammation in body tissues. The role of GM-CSF in the activation of microglia (CNS resident macrophages) and the consequent impacts on neuronal survival, excitability, and synaptic transmission are widely unknown, however. Here, we focused on electrical neuronal network rhythms in the gamma frequency band (30–70 Hz). Gamma oscillations are fundamental to higher brain functions, such as perception, attention, and memory, and they are exquisitely sensitive to metabolic and oxidative stress.

Methods

We explored the effects of chronic GM-CSF exposure (72 h) on microglia in male rat organotypic hippocampal slice cultures (in situ), i.e., postnatal cortex tissue lacking leukocyte invasion (adaptive immunity). We applied extracellular electrophysiological recordings of local field potential, immunohistochemistry, design-based stereology, biochemical analysis, and pharmacological ablation of microglia.

Results

GM-CSF triggered substantial proliferation of microglia (microgliosis). By contrast, the release of proinflammatory cytokines (IL-6, TNF-α) and nitric oxide, the hippocampal cytoarchitecture as well as the morphology of parvalbumin-positive inhibitory interneurons were unaffected. Notably, GM-CSF induced concentration-dependent, long-lasting disturbances of gamma oscillations, such as slowing (beta frequency band) and neural burst firing (hyperexcitability), which were not mimicked by the T lymphocyte cytokine IL-17. These disturbances were attenuated by depletion of the microglial cell population with liposome-encapsulated clodronate. In contrast to priming with the cytokine IFN-γ (type II interferon), GM-CSF did not cause inflammatory neurodegeneration when paired with the TLR4 ligand LPS.

Conclusions

GM-CSF has a unique role in the activation of microglia, including the potential to induce neuronal network dysfunction. These immunomodulatory properties might contribute to cognitive impairment and/or epileptic seizure development in disease featuring elevated GM-CSF levels, blood-brain barrier leakage, and/or T cell infiltration.

Albendazole-Schisandrin B Co-Therapy on Angiostrongylus cantonensis-Induced Meningoencephalitis in Mice

Currently, Angiostrongylus cantonensis infections are predominantly treated with albendazole. However, the use of albendazole can provoke certain neurological symptoms as a result of the immune response triggered by the dead worms. Therefore, treatment usually involves co-administration of corticosteroids to limit the inflammatory reaction. Corticosteroids play a useful role in suppressing inflammation in the brain; however, long-term usage or high dosage may make it problematic.Schisandrin B, an active ingredient from Schisandra chinensis, has been shown to have anti-inflammatory effects on the brain. This study aimed to investigate the effects and potential of schisandrin B in combination with albendazole to treat Angiostrongylus-induced meningoencephalitis. Here, we show that albendazole-schisandrin B co-treatment suppressed neuroinflammation in Angiostrongylus-infected mice and increased the survival of the mice. Accordingly, albendazole-schisandrin B co-treatment significantly inhibited inflammasome activation, pyroptosis, and apoptosis. The sensorimotor functions of the mice were also repaired after albendazole-schisandrin B treatment. Immune response was shown to shift from Th2 to Th1, which reduces inflammation and enhances immunity against A. cantonensis. Collectively, our study showed that albendazole-schisandrin B co-therapy may be used as an encouraging treatment for Angiostrongylus-induced meningoencephalitis.

The Role of Granulocyte-Macrophage Colony-Stimulating Factor in Murine Models of Multiple Sclerosis

Multiple sclerosis (MS) is an immune-mediated disease that predominantly impacts the central nervous system (CNS). Animal models have been used to elucidate the underpinnings of MS pathology. One of the most well-studied models of MS is experimental autoimmune encephalomyelitis (EAE). This model was utilized to demonstrate that the cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) plays a critical and non-redundant role in mediating EAE pathology, making it an ideal therapeutic target. In this review, we will first explore the role that GM-CSF plays in maintaining homeostasis. This is important to consider, because any therapeutics that target GM-CSF could potentially alter these regulatory processes. We will then focus on current findings related to the function of GM-CSF signaling in EAE pathology, including the cell types that produce and respond to GM-CSF and the role of GM-CSF in both acute and chronic EAE. We will then assess the role of GM-CSF in alternative models of MS and comment on how this informs the understanding of GM-CSF signaling in the various aspects of MS immunopathology. Finally, we will examine what is currently known about GM-CSF signaling in MS, and how this has promoted clinical trials that directly target GM-CSF.

T cells producing GM-CSF and IL-13 are enriched in the cerebrospinal fluid of relapsing MS patients

BACKGROUND

Multiple sclerosis (MS) is a central nervous system (CNS) autoimmune demyelinating disease. Its pathogenesis involves humoral and cellular immunity, with production of pro- and anti-inflammatory cytokines by T cells.

OBJECTIVE

To analyze the cytokine profile of cerebrospinal fluid (CSF) T cells in patients with relapsing-remitting MS (RRMS) and non-inflammatory controls.

METHODS

T cell cytokine production was analyzed by flow cytometry in CSF samples collected from 34 untreated RRMS patients and 20 age-matched controls. Immunofluorescence studies were performed in spinal cord MS active lesions.

RESULTS

Percentages of CSF-derived IL-17A, IL-17A/IL-22, and IL-17A/GM-CSF producing T cells were significantly higher in RRMS patients compared to controls. Percentages of T cells producing IFN-γ were lower in RRMS patients compared to controls. Patients in relapse showed higher percentages of CD4⁺ T cells producing IL-13 and GM-CSF compared to patients in remission. We found a positive correlation between percentages of IL-13⁺ T cells and the Expanded Disability Status Scale (EDSS; ρ = 0.5; p < 0.05). Meningeal IL-13-producing T cells were detected in spinal cord MS active lesions.

CONCLUSION

We observed differences in IL-17, IL-22, and IFN-γ production by CSF T cells in RRMS versus controls and a positive correlation between IL-13-producing T cells and EDSS in RRMS patients.

Prevotella histicola, A Human Gut Commensal, Is as Potent as COPAXONE® in an Animal Model of Multiple Sclerosis

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system. We and others have shown that there is enrichment or depletion of some gut bacteria in MS patients compared to healthy controls (HC), suggesting an important role of the gut bacteria in disease pathogenesis. Thus, specific gut bacteria that are lower in abundance in MS patients could be used as a potential treatment option for this disease. In particular, we and others have shown that MS patients have a lower abundance of Prevotella compared to HC, whereas the abundance of Prevotella is increased in patients that receive disease-modifying therapies such as Copaxone® (Glatiramer acetate-GA). This inverse correlation between the severity of MS disease and the abundance of Prevotella suggests its potential for use as a therapeutic option to treat MS. Notably we have previously identified a specific strain, Prevotella histicola (P. histicola), that suppresses disease in the animal model of MS, experimental autoimmune encephalomyelitis (EAE) compared with sham treatment. In the present study we analyzed whether the disease suppressing effects of P. histicola synergize with those of the disease-modifying drug Copaxone® to more effectively suppress disease compared to either treatment alone. Treatment with P. histicola was as effective in suppressing disease as treatment with Copaxone®, whereas the combination of P. histicola plus Copaxone® was not more effective than either individual treatment. P. histicola-treated mice had an increased frequency and number of CD4⁺FoxP3⁺ regulatory T cells in periphery as well as gut and a decreased frequency of pro-inflammatory IFN-γ and IL17-producing CD4 T cells in the CNS, suggesting P. histicola suppresses disease by boosting anti-inflammatory immune responses and inhibiting pro-inflammatory immune responses. In conclusion, our study indicates that the human gut commensal P. histicola can suppress disease as efficiently as Copaxone® and may provide an alternative treatment option for MS patients.

Hemp seed/evening primrose oil affects expression of STAT3, IL-17, and FOXP3+ in experimental autoimmune encephalomyelitis

T helper (Th)-17 mediate inflammation in both peripheral tissues and the central nervous system. Signal transducer and activator of transcription factor3 (STAT3) is required for Th-cell pathogenicity and its activation in the brain has been demonstrated during the acute phase of experimental autoimmune encephalomyelitis (EAE) through the mammalian target of rapamycin (mTOR) signaling. Rapamycin (RAPA), an inhibitor of mTOR, can drive Forkhead box P3 (FOXP3⁺) induction as a regulatory factor. The aim of this study was to determine the effects of hemp seed/evening primrose oils (HSO/EPO) supplement on the expression of FOXP3⁺, STAT3, and interleukin (IL)-17 genes in EAE lymph nodes. EAE was induced by myelin oligodendrocyte glycoprotein peptide in mice, and then the mice were assigned to three treatment groups compared to two control groups (EAE and naive). The histological findings of the spinal cord were evaluated. To determine the expression of FOXP3⁺, STAT3, and IL-17 genes in the lymphocytes, qRT-PCR was used. Our results showed that EAE severity was reduced in HSO/EPO mice by reducing the expression of STAT3 and IL-17 genes and increasing the expression of FOXP3⁺ gene, which was confirmed by slight inflammation in the spinal cord. Histological findings showed a significant improvement in the HSO/EPO group. Our findings suggest that the HSO/EPO treatment can be used to ameliorate the demyelination of spinal cord, which was confirmed by immunological and histological findings.

Regulatory effects of hemp seed/evening primrose oil supplement in comparison with rapamycin on the expression of the mammalian target of rapamycin-complex 2 and interleukin-10 genes in experimental autoimmune encephalomyelitis

The mammalian target of rapamycin (mTOR) signaling plays a critical role in lipid synthesis and immune responses. The T regulatory cells (Treg) as suppressor of T cells, are a subset of T cells that modulate the immune system, maintain tolerance, and prevent autoimmune diseases.. The interleukin (IL) -10 derived from the Treg and T helper (Th) 2 is an anti-inflammatory cytokine in multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE). Due to the exclusive roles of rapamycin (RAPA) in mTOR inhibition, we evaluated the regulatory effect of the hemp seed oil/evening primrose oil (HSO/EPO) supplement in comparison with RAPA in EAE. EAE was induced by using myelin oligodendrocyte glycoprotein peptide and complete freund’s adjuvant (CFA) in C57BL/6 mice, total mRNA was extracted from local lymph nodes and real-time polymerase chain reaction was used to evaluate the expression level of the rapamycin-insensitive companion of mTOR complex 2 (RICTOR) and IL-10 genes. The expression of IL-10 and RICTOR genes were significantly increased in HSO/EPO group. In contrast with RAPA groups, histological findings have shown that the HSO/EPO treated group remarkably reduced cell infiltration and promoted remyelination. The EPO/HSO has beneficial effects on the repair of myelin, which was confirmed by immunological and histological findings.

α-Synuclein activates innate immunity but suppresses interferon-γ expression in murine astrocytes

Glial activation and neuroinflammation contribute to pathogenesis of neurodegenerative diseases, linked to neuron loss and dysfunction. α-Synuclein (α-syn), as a metabolite of neuron, can induce microglia activation to trigger innate immune response. However, whether α-syn, as well as its mutants (A53T, A30P, and E46K), induces astrocyte activation and inflammatory response is not fully elucidated. In this study, we used A53T mutant and wild-type α-syns to stimulate primary astrocytes in dose- and time-dependent manners (0.5, 2, 8, and 20 μg/ml for 24 hr or 3, 12, 24, and 48 hr at 2 μg/ml), and evaluated activation of several canonical inflammatory pathway components. The results showed that A53T mutant or wild-type α-syn significantly upregulated mRNA expression of toll-like receptor (TLR)2, TLR3, nuclear factor-κB and interleukin (IL)-1β, displaying a pattern of positive dose-effect correlation or negative time-effect correlation. Such upregulation was confirmed at protein levels of TLR2 (at 20 μg/ml), TLR3 (at most doses), and IL-1β (at 3 hr) by western blotting. Blockage of TLR2 other than TLR4 inhibited TLR3 and IL-1β mRNA expressions. By contrast, interferon (IFN)-γ was significantly downregulated at mRNA, protein, and protein release levels, especially at high concentrations of α-syns or early time-points. These findings indicate that α-syn was a TLRs-mediated immunogenic agent (A53T mutant stronger than wild-type α-syn). The stimulation patterns suggest that persistent release and accumulation of α-syn is required for the maintenance of innate immunity activation, and IFN-γ expression inhibition by α-syn suggests a novel immune molecule interaction mechanism underlying pathogenesis of neurodegenerative diseases.

The potential effects of hemp seed/evening primrose oils on the mammalian target of rapamycin complex 1 and interferon-gamma genes expression in experimental autoimmune encephalomyelitis

The mammalian target of rapamycin (mTOR) has a fundamental role in the metabolism, growth, and regulation of the immune system. The interferon gamma (IFN-γ)derived from T helper 1 (Th1) cells is a prominent pro-inflammatory cytokine in multiple sclerosis (MS) and its animal model, the experimental autoimmune encephalomyelitis (EAE). Due to the exclusive role of rapamycin (RAPA) in mTOR complex 1 (mTORC1) inhibition, essentially Th1 differentiation and IFN-γ production, we evaluated the potential therapeutic effects of hemp seed/evening primrose oils (HSO/EPO) in comparison with RAPA administration in EAE. To evaluate the therapeutic effects of EPO/HSO supplement in comparison with RAPA, EAE was induced using myelin oligodendrocyte glycoprotein (MOG) peptide and complete Freund's adjuvant in C57BL/6 mice. The weight, clinical score, and histological findings were evaluated. Total mRNA was extracted from local lymph nodes and qRT-PCR was used for the purpose of the genes expression level of regulatory associated protein of TORC1 (RAPTOR) and IFN-γ. Our results indicated that the relative expression of RAPTOR and IFN-γ genes were significantly reduced in HSO/EPO, RAPA, and RAPA + HSO/EPO treated groups in comparison with the untreated group. Interestingly, histological findings have shown that the HSO/EPO treated group remarkably regenerated the myelin sheath, but this did not occur in the case of RAPA or combined RAPA and HSO/EPO treated groups. Our findings suggeste that HSO/HPO can be used as a potent immunomodulator and as a good candidate for re-myelination and downregulation of immune response for treatment of MS.

Interferon-γ causes mood abnormalities by altering cannabinoid CB1 receptor function in the mouse striatum

Interferon-γ (IFN-γ) has been implicated in the pathogenesis of multiple sclerosis (MS) and in its animal model, experimental autoimmune encephalomyelitis (EAE). The type-1 cannabinoid receptors (CB1Rs) are heavily involved in MS pathophysiology, and a growing body of evidence suggests that mood disturbances reflect specific effects of proinflammatory cytokines on neuronal activity. Here, we investigated whether IFN-γ could exert a role in the anxiety- and depressive-like behavior observed in mice with EAE, and in the modulation of CB1Rs. Anxiety and depression in fact are often diagnosed in MS, and have already been shown to depend on cannabinoid system. We performed biochemical, behavioral and electrophysiological experiments to assess the role of IFN-γ on mood control and on synaptic transmission in mice. Intracerebroventricular delivery of IFN-γ caused a depressive- and anxiety-like behavior in mice, associated with the selective dysfunction of CB1Rs controlling GABA transmission in the striatum. EAE induction was associated with increased striatal expression of IFN-γ, and with CB1R transmission deficits, which were rescued by pharmacological blockade of IFN-γ. IFN-γ was unable to replicate the effects of EAE on excitatory and inhibitory transmission in the striatum, but mimicked the effects of EAE on CB1R function in this brain area. Overall these results indicate that IFN-γ exerts a relevant control on mood, through the modulation of CB1R function. A better understanding of the biological pathways underling the psychological disorders during neuroinflammatory conditions is crucial for developing effective therapeutic strategies.

Determination of cytokine levels in multiple sclerosis patients and their relevance with patients' response to Cinnovex

Multiple sclerosis (MS) is a heterogeneous chronic immune-mediated disorder of the central nervous system (CNS) with several environmental and genetic factors participating in its development and disease course. Interferon (IFN)-β therapy is considered as the first line treatment in this disorder. The present study enrolled 231 relapsing-remitting MS patients who were diagnosed as IFN-β responders (n=146) and non-responders (n=85). Serum cytokine levels were analyzed by commercially available ELISA kits in distinct groups based on HLA-A, -B and -DRB1 alleles. IFN-γ levels were significantly higher in responders compared with non-responders, whereas IL-17A and IL-6 had the opposite trend. The levels of IL-10 and IL-4 were not significantly different between two groups. IFN-γ and IL-17A levels were associated with response to IFN-β. Comparison of cytokine levels revealed higher IFN-γ levels in HLA-DRB1∗04 positive patients (n=72) compared with HLA-DRB1∗04 negative patients (n=159). In responder group, patients who were positive for HLA-DRB1∗15 had significantly higher levels of IL-6 compared to HLA-DRB1∗15 negative patients. IL-17A levels tend to be higher in responder patients who were positive for HLA-DRB1∗04 compared with those were negative for the same allele. This study suggests that the serum levels of pro- and anti-inflammatory cytokines are different among IFN-β responders and non-responders. Future studies are needed to confirm their efficiency in determination of response to IFN-β in MS patients.

GM-CSF is not essential for experimental autoimmune encephalomyelitis but promotes brain-targeted disease

Experimental autoimmune encephalomyelitis (EAE) has been used as an animal model of multiple sclerosis to identify pathogenic cytokines that could be therapeutic targets. Granulocyte-macrophage colony-stimulating factor (GM-CSF) is the only cytokine reported to be essential for EAE. We investigated the role of GM-CSF in EAE in C3HeB/FeJ mice that uniquely exhibit extensive brain and spinal cord inflammation. Unexpectedly, GM-CSF-deficient C3HeB/FeJ mice were fully susceptible to EAE because IL-17 activity compensated for the loss of GM-CSF during induction of spinal cord-targeted disease. In contrast, both GM-CSF and IL-17 were needed to fully overcome the inhibitory influence of IFN-γ on the induction of inflammation in the brain. Both GM-CSF and IL-17 independently promoted neutrophil accumulation in the brain, which was essential for brain-targeted disease. These results identify a GM-CSF/IL-17/IFN-γ axis that regulates inflammation in the central nervous system and suggest that a combination of cytokine-neutralizing therapies may be needed to dampen central nervous system autoimmunity.

Opposing Roles of Interferon-Gamma on Cells of the Central Nervous System in Autoimmune Neuroinflammation

Multiple sclerosis (MS) is the principal cause of autoimmune neuroinflammation in humans, and its animal model, experimental autoimmune encephalomyelitis (EAE), is widely used to gain insight about their immunopathological mechanisms for and the development of novel therapies for MS. Most studies on the role of interferon (IFN)-γ in the pathogenesis and progression of EAE have focused on peripheral immune cells, while its action on central nervous system (CNS)-resident cells has been less explored. In addition to the well-known proinflammatory and damaging effects of IFN-γ in the CNS, evidence has also endowed this cytokine both a protective and regulatory role in autoimmune neuroinflammation. Recent investigations performed in this research field have exposed the complex role of IFN-γ in the CNS uncovering unexpected mechanisms of action that underlie these opposing activities on different CNS-resident cell types. The mechanisms behind these two-faced effects of IFN-γ depend on dose, disease phase, and cell development stage. Here, we will review and discuss the dual role of IFN-γ on CNS-resident cells in EAE highlighting its protective functions and the mechanisms proposed.

Stage-Specific Role of Interferon-Gamma in Experimental Autoimmune Encephalomyelitis and Multiple Sclerosis

The role of interferon (IFN)-γ in multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), has remained as an enigmatic paradox for more than 30 years. Several studies attribute this cytokine a prominent proinflammatory and pathogenic function in these pathologies. However, accumulating evidence shows that IFN-γ also plays a protective role inducing regulatory cell activity and modulating the effector T cell response. Several innate and adaptive immune cells also develop opposite functions strongly associated with the production of IFN-γ in EAE. Even the suppressive activity of different types of regulatory cells is dependent on IFN-γ. Interestingly, recent data supports a stage-specific participation of IFN-γ in EAE providing a plausible explanation for previous conflicting results. In this review, we will summarize and discuss such literature, emphasizing the protective role of IFN-γ on immune cells. These findings are fundamental to understand the complex role of IFN-γ in the pathogenesis of these diseases and can provide basis for potential stage-specific therapy for MS targeting IFN-γ-signaling or IFN-γ-producing immune cells.

Clinical implications of leukocyte infiltration at the choroid plexus in (neuro)inflammatory disorders

The choroid plexus (CP) is a highly vascularized organ located in the brain ventricles and contains a single epithelial cell layer forming the blood-cerebrospinal fluid barrier (BCSFB). This barrier is crucial for immune surveillance in health and is an underestimated gate for entry of immune cells during numerous inflammatory disorders. Several of these disorders are accompanied by disturbance of the BCSFB and increased leukocyte infiltration, which affects neuroinflammation. Understanding the mechanism of immune cell entry at the CP might lead to identification of new therapeutic targets. Here, we focus on current knowledge of leukocyte infiltration at the CP in inflammatory conditions and its therapeutic implications.

Violacein Treatment Modulates Acute and Chronic Inflammation through the Suppression of Cytokine Production and Induction of Regulatory T Cells

Inflammation is a necessary process to control infection. However, exacerbated inflammation, acute or chronic, promotes deleterious effects in the organism. Violacein (viola), a quorum sensing metabolite from the Gram-negative bacterium Chromobacterium violaceum, has been shown to protect mice from malaria and to have beneficial effects on tumors. However, it is not known whether this drug possesses anti-inflammatory activity. In this study, we investigated whether viola administration is able to reduce acute and chronic autoimmune inflammation. For that purpose, C57BL/6 mice were intraperitoneally injected with 1 μg of LPS and were treated with viola (3.5mg/kg) via i.p. at the same time-point. Three hours later, the levels of inflammatory cytokines in the sera and phenotypical characterization of leukocytes were determined. Mice treated with viola presented a significant reduction in the production of inflammatory cytokines compared with untreated mice. Interestingly, although viola is a compound derived from bacteria, it did not induce inflammation upon administration to naïve mice. To test whether viola would protect mice from an autoimmune inflammation, Experimental Autoimmune Encephalomyelitis (EAE)-inflicted mice were given viola i.p. at disease onset, at the 10th day from immunization. Viola-treated mice developed mild EAE disease in contrast with placebo-treated mice. The frequencies of dendritic cells and macrophages were unaltered in EAE mice treated with viola. However, the sole administration of viola augmented the levels of splenic regulatory T cells (CD4+Foxp3+). We also found that adoptive transfer of viola-elicited regulatory T cells significantly reduced EAE. Our study shows, for the first time, that violacein is able to modulate acute and chronic inflammation. Amelioration relied in suppression of cytokine production (in acute inflammation) and stimulation of regulatory T cells (in chronic inflammation). New studies must be conducted in order to assess the possible use of viola in therapeutic approaches in human autoimmune diseases.