Anti-IL-17A treatment reduces clinical score and VCAM-1 expression detected by in vivo magnetic resonance imaging in chronic relapsing EAE ABH mice

IL-17A Facilitates Entry of Autoreactive T-Cells and Granulocytes into the CNS During EAE

Interleukin-17A plays a crucial role in multiple sclerosis and other autoimmune diseases. Although the link between IL-17 and disease activity has been clearly demonstrated, the precise function of this cytokine remains elusive. Here, we investigated the function of astrocyte-targeted IL-17A production in GF/IL-17 transgenic mice during EAE. In particular, IL-17A is important during disease induction. In mice with transgenic IL-17A production, disease occurs earlier and peak disease is more severe, whereas remission is unimpaired. IL-17A synthesis is associated with increased infiltration of granulocytes into the CNS and microglial activation. Moreover, IL-17A synthesis allows induction of MOG-EAE without the additional administration of the co-adjuvant pertussis toxin. Examination of double transgenic GF/IL-17 2D2 mice revealed that, in addition, local IL-17A production facilitates spontaneous infiltration of immune cells into the CNS in mice expressing a MOG-specific T-cell receptor. Overall, we provide evidence for a crucial effect of IL-17A in the induction phase of EAE, facilitating the infiltration of granulocytes and autoreactive T-cells into the CNS.

Friend or Foe - Tc17 cell generation and current evidence for their importance in human disease

The term Tc17 cells refers to interleukin 17 (IL-17)-producing CD8+ T cells. While IL-17 is an important mediator of mucosal defense, it is also centrally involved in driving the inflammatory response in immune-mediated diseases, such as psoriasis, multiple sclerosis, and inflammatory bowel disease. In this review, we aim to gather the current knowledge on the phenotypic and transcriptional profile, the in vitro and in vivo generation of Tc17 cells, and the evidence pointing towards a relevant role of Tc17 cells in human diseases such as infectious diseases, cancer, and immune-mediated diseases.

Low sulfated heparan sulfate mimetic differentially affects repair in immune-mediated and toxin-induced experimental models of demyelination

There is an urgent need for therapies that target the multicellular pathology of central nervous system (CNS) disease. Modified, nonanticoagulant heparins mimic the heparan sulfate glycan family and are known regulators of multiple cellular processes. In vitro studies have demonstrated that low sulfated modified heparin mimetics (LS-mHeps) drive repair after CNS demyelination. Herein, we test LS-mHep7 (an in vitro lead compound) in experimental autoimmune encephalomyelitis (EAE) and cuprizone-induced demyelination. In EAE, LS-mHep7 treatment resulted in faster recovery and rapidly reduced inflammation which was accompanied by restoration of animal weight. LS-mHep7 treatment had no effect on remyelination or on OLIG2 positive oligodendrocyte numbers within the corpus callosum in the cuprizone model. Further in vitro investigation confirmed that LS-mHep7 likely mediates its pro-repair effect in the EAE model by sequestering inflammatory cytokines, such as CCL5 which are upregulated during immune-mediated inflammatory attacks. These data support the future clinical translation of this next generation modified heparin as a treatment for CNS diseases with active immune system involvement.

Modulation of cytokine release from peripheral blood mononuclear cells from multiple sclerosis patients by coenzyme A and soraphen A

By applying the acetyl-CoA-carboxylase inhibitors soraphen A (SorA) and coenzyme A (CoA) ex vivo, we aimed to reduce proinflammatory cytokine release by PBMCs and increase anti-inflammatory cytokine levels, thereby demonstrating a possible application of those pathways in future multiple sclerosis (MS) therapy. In a prospective exploratory monocentric study, we analysed cytokine production by PBMCs treated with SorA (10 or 50 nM) and CoA (600 μM). Thirty-one MS patients were compared to 18 healthy age-matched controls. We demonstrated the immunomodulatory potential of SorA and CoA in targeting the immune function of MS patients, with an overall reduction of cytokines except of IL-2, IL-6 and IL-10.

Autophagic Molecular Alterations in the Mouse Cerebellum Experimental Autoimmune Encephalomyelitis Model Following Treatment with Cannabidiol and Fluoxetine

The crosstalk between autophagy and apoptosis is one of the most important processes involved in the cell program death, and several mechanisms including oligodendrocyte apoptosis and autophagy play significant roles in activating macrophages, microglial cells, and finally demyelination in neurodegenerative disease. The antidepressants and anti-apoptotic mechanisms of fluoxetine (FLX) and cannabidiol (CBD) commence an autophagic event that can effectively repair myelin. This study aimed to investigate the effect of those reagents on the rate of demyelination in the cerebellum, an important site for white matter in a mouse model of experimental autoimmune encephalomyelitis (EAE). EAE was induced in twenty four adult female C57Bl/6 mice were inducted the EAE model; FLX treatment which was performed (10 mg/kg/IP) and CBD; were treated (5 mg/kg/IP); and their cerebellum was used for Western blotting, real-time PCR to autophagic markers of LC3II, Beclin-1, and apoptotic markers Bax and Bcl2 evaluation and Luxol Fast Blue staining to the assessment of demyelination. The level of autophagic markers was expressively elevated (P < 0.01) but the pro-apoptotic markers and Bax/Bcl2 ratio were reduced (P < 0.05). Luxol Fast Blue staining confirmed the noteworthy diminution of demyelination in treatment groups (P < 0.001). This finding clarified that FLX and CBD ameliorate the severity of the EAE model. Combinatory treatments of these two agents are suggested for future investigations.

IL-17 and IL-17-producing cells in protection versus pathology

IL-17 cytokine family members have diverse biological functions, promoting protective immunity against many pathogens but also driving inflammatory pathology during infection and autoimmunity. IL-17A and IL-17F are produced by CD4⁺ and CD8⁺ T cells, γδ T cells, and various innate immune cell populations in response to IL-1β and IL-23, and they mediate protective immunity against fungi and bacteria by promoting neutrophil recruitment, antimicrobial peptide production and enhanced barrier function. IL-17-driven inflammation is normally controlled by regulatory T cells and the anti-inflammatory cytokines IL-10, TGFβ and IL-35. However, if dysregulated, IL-17 responses can promote immunopathology in the context of infection or autoimmunity. Moreover, IL-17 has been implicated in the pathogenesis of many other disorders with an inflammatory basis, including cardiovascular and neurological diseases. Consequently, the IL-17 pathway is now a key drug target in many autoimmune and chronic inflammatory disorders; therapeutic monoclonal antibodies targeting IL-17A, both IL-17A and IL-17F, the IL-17 receptor, or IL-23 are highly effective in some of these diseases. However, new approaches are needed to specifically regulate IL-17-mediated immunopathology in chronic inflammation and autoimmunity without compromising protective immunity to infection.

CD47 Binding on Vascular Endothelial Cells Inhibits IL-17-Mediated Leukocyte Adhesion

To address the conflicting role of thrombospondin (TSP)-1 reported in acute and chronic pathologies, this study investigated the role of TSP-1 in regulating leukocyte recruitment and regulation of VCAM-1 expression using mouse models of uveitis. The spontaneously increased VCAM-1 expression and leukocyte adhesion in retinas of TSP-1-deficient mice suggested a TSP-1-mediated regulation of VCAM-1 expression. In a chronic uveitis model, induced by immunizing wild-type mice with specific interphotoreceptor retinoid-binding protein (IRBP) peptide, topically applied TSP-1-derived CD47-binding peptide significantly reduced the clinical disease course and retinal leukocyte adhesion as compared to the control peptide-treated group. In contrast, in LPS-mediated acute uveitis, TSP-1 deficiency significantly reduced the retinal leukocyte adhesion. The results of our in vitro study, using vascular endothelial cell (EC) cultures, demonstrate that unlike TNF-α, VCAM-1 expression induced by IL-17 is associated with a reduced expression of endogenous TSP-1. Such reduced endogenous TSP-1 expression in IL-17-stimulated ECs helps limit the CD36-mediated increased VCAM-1 expression, while favoring CD47-mediated inhibition of VCAM-1 expression and leukocyte adhesion. Thus, our study identifies TSP-1:CD47 interaction as a molecular pathway that modulates IL-17-mediated VCAM-1 expression, contributing to its anti-inflammatory effect in chronic inflammatory conditions.

Crotalphine Attenuates Pain and Neuroinflammation Induced by Experimental Autoimmune Encephalomyelitis in Mice

Multiple sclerosis (MS) is a demyelinating disease of inflammatory and autoimmune origin, which induces sensory and progressive motor impairments, including pain. Cells of the immune system actively participate in the pathogenesis and progression of MS by inducing neuroinflammation, tissue damage, and demyelination. Crotalphine (CRO), a structural analogue to a peptide firstly identified in Crotalus durissus terrificus snake venom, induces analgesia by endogenous opioid release and type 2 cannabinoid receptor (CB2) activation. Since CB2 activation downregulates neuroinflammation and ameliorates symptoms in mice models of MS, it was presently investigated whether CRO has a beneficial effect in the experimental autoimmune encephalomyelitis (EAE). CRO was administered on the 5th day after immunization, in a single dose, or five doses starting at the peak of disease. CRO partially reverted EAE-induced mechanical hyperalgesia and decreased the severity of the clinical signs. In addition, CRO decreases the inflammatory infiltrate and glial cells activation followed by TNF-α and IL-17 downregulation in the spinal cord. Peripherally, CRO recovers the EAE-induced impairment in myelin thickness in the sciatic nerve. Therefore, CRO interferes with central and peripheral neuroinflammation, opening perspectives to MS control.

A novel molecular magnetic resonance imaging agent targeting activated leukocyte cell adhesion molecule as demonstrated in mouse brain metastasis models

Molecular magnetic resonance imaging (MRI) allows visualization of biological processes at the molecular level. Upregulation of endothelial ALCAM (activated leukocyte cell adhesion molecule) is a key element for leukocyte recruitment in neurological disease. The aim of this study, therefore, was to develop a novel molecular MRI contrast agent, by conjugating anti-ALCAM antibodies to microparticles of iron oxide (MPIO), for detection of endothelial ALCAM expression in vivo. Binding specificity of ALCAM-MPIO was demonstrated in vitro under static and flow conditions. Subsequently, in a proof-of-concept study, mouse models of brain metastasis were induced by intracardial injection of brain-tropic human breast carcinoma, lung adenocarcinoma or melanoma cells to upregulate endothelial ALCAM. At selected time-points, mice were injected intravenously with ALCAM-MPIO, and ALCAM-MPIO induced hypointensities were observed on T2*-weighted images in all three models. Post-gadolinium MRI confirmed an intact blood-brain barrier, indicating endoluminal binding. Correlation between endothelial ALCAM expression and ALCAM-MPIO binding was confirmed histologically. Statistical analysis indicated high sensitivity (80-90%) and specificity (79-83%) for detection of endothelial ALCAM in vivo with ALCAM-MPIO. Given reports of endothelial ALCAM upregulation in numerous neurological diseases, this advance in our ability to image ALCAM in vivo may yield substantial improvements for both diagnosis and targeted therapy.

Cytokines and Chemokines in the Pathogenesis of Experimental Autoimmune Encephalomyelitis

Experimental autoimmune encephalomyelitis is a CD4⁺ T cell-mediated demyelinating disease of the CNS that serves as a model for multiple sclerosis. Cytokines and chemokines shape Th1 and Th17 effector responses as well as regulate migration of leukocytes to the CNS during disease. The CNS cellular infiltrate consists of Ag-specific and nonspecific CD4⁺ and CD8⁺ T cells, neutrophils, B cells, monocytes, macrophages, and dendritic cells. The mechanism of immune-mediated inflammation in experimental autoimmune encephalomyelitis has been extensively studied in an effort to develop therapeutic modalities for multiple sclerosis and, indeed, has provided insight in modern drug discovery. The present Brief Review highlights critical pathogenic aspects of cytokines and chemokines involved in generation of effector T cell responses and migration of inflammatory cells to the CNS. Select cytokines and chemokines are certainly important in the regulatory response, which involves T regulatory, B regulatory, and myeloid-derived suppressor cells. However, that discussion is beyond the scope of this brief review.

Natural product piperine alleviates experimental allergic encephalomyelitis in mice by targeting dihydroorotate dehydrogenase

Multiple sclerosis (MS) is the most popular chronic and debilitating inflammatory disease of the central nervous system (CNS) that remains incurable. Dihydroorotate dehydrogenase (DHODH) is critical to the activity of T lymphocytes and represents a potential therapeutic target for MS. Here we identify piperine, a bioactive constituent of black pepper, as a potent inhibitor of DHODH with an IC₅₀ value of 0.88 μM. Isothermal titration calorimetry and thermofluor assay demonstrate the directly interaction between piperine and DHODH. The co-complex crystal structure of DHODH and piperine at 1.98 Å resolution further reveal that Tyr356 residue of DHODH is crucial for piperine binding. Importantly, we show that piperine can inhibit T cell overactivation in a DHODH-dependent manner in concanavalin A-triggered T-cell assay and mixed lymphocyte reaction assay. Finally, piperine exhibits strong preventive and therapeutic effect in the MOG-induced experimental allergic encephalomyelitis (EAE), a useful model for studying potential treatments for MS, by restricting inflammatory cells infiltration into the CNS and preventing myelin destruction and blood-brain barrier (BBB) disruption. Taken together, these findings highlight DHODH as a therapeutic target for autoimmune disease of the nervous system, and demonstrate a novel role for piperine in the treatment of MS.

ERβ-selective agonist alleviates inflammation in a multiple sclerosis model via regulation of MHC II in microglia

Multiple sclerosis (MS) is an autoimmune, demyelinating, and neurodegenerative disease of the central nervous system (CNS) that affects 2-2.5 million people worldwide. Although the etiology of MS is not well known, MS is widely considered to be an autoimmune disease. Currently approved MS drugs reduce relapse rates but fail to reverse or prevent neurodegeneration and disability progression. Increasing evidence indicates that microglia and major histocompatibility complex class II (MHC II) expression in these cells play important roles in the pathophysiology of MS. For a T cell to contribute to CNS pathogenesis, it must be reactivated by antigen-presenting cells within the CNS parenchyma. Susceptibility to MS is associated with MHC II genes, suggesting that presentation of antigens on MHC II plays an important role in CD4+ T-cell reactivation and disease initiation. An ERβ-selective agonist was previously reported to suppress reactivation of T cells invading the spinal cord, thereby reducing the severity of symptoms and decreasing mortality in the first 2 weeks after disease onset. However, the mechanism by which the expression of MHC II in microglia is regulated by ERβ-selective agonists is still unclear. Therefore, we hypothesize that ERβ-selective agonists inhibit MHC II expression in microglia via inhibition of class II trans-activator (CIITA) expression by a mechanism involving inhibition of the translocation of IFNγ regulatory factor (IRF-1) to the nucleus, thereby inhibiting the inflammatory response and symptoms in the MS model.

Characterization of leptomeningeal inflammation in rodent experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis

BACKGROUND

Leptomeningeal inflammation, as evidenced by leptomeningeal contrast enhancement (LMCE), is associated to cortical pathology in multiple sclerosis. The temporal pattern of LMCE in experimental autoimmune encephalomyelitis (EAE) myelin oligodendrocyte glycoprotein (MOG) is unknown.

OBJECTIVE

To investigate LMCE using serial MRI in the EAE model of MS, and its association with clinical disease progression. To characterize the relationship between LMCE and underlying histological correlates.

DESIGN

Thirteen C57BL/6J mice, MOG-immunized (35-55 amino acid) and 8 saline injected animals were assessed at pre-induction and at 3, 6, 10, 20, 27, 32, 45 and 63 days post induction (dPI). LMCE scan was obtained using FLAIR-RARE sequence after post-contrast gadolinium administration on 9.4 T scanner. Brain cryo-sections were assessed for measuring cellular density of Iba1 positive macrophage/microglia at 10 dPI and 32 dPI, and for the presence of T, B and macrophage cells in the meningeal layer at 10 dPI and 63 dPI.

RESULTS

All EAE-MOG animals showed presence of LMCE and none of the control mice. The peak signal intensity of LMCE was evidenced at 10dPI in the meninges and decreased through 10-63 dPI. The peak of LMCE was associated with a weight loss starting at 1 week PI and with clinical symptoms starting at 2 weeks PI. Histological analysis of the brain tissue showed a higher density of Iba1 positive microglial cells in the EAE-MOG animals, corresponding to the areas of LMCE. Meninges of EAE mice showed higher density of Iba1 stained macrophage cells relative to saline animals. EAE animals also showed the presence of T and B cells in the meninges which were absent in the saline animals.

CONCLUSIONS

LMCE peak intensity in the meninges corresponds to the acute inflammatory phase of EAE-MOG disease progression, and is associated with clinical symptoms and higher inflammatory cell density.

Anti-IL17 treatment ameliorates Down syndrome phenotypes in mice

Down syndrome (DS) is characterized by structural and functional anomalies that are present prenatally and that lead to intellectual disabilities. Later in life, the cognitive abilities of DS individuals progressively deteriorate due to the development of Alzheimer's disease (AD)-associated neuropathology (i.e., β-amyloid (Aβ) plaques, neurofibrillary tangles (NFTs), neurodegeneration, synaptic pathology, neuroinflammation and increased oxidative stress). Increasing evidence has shown that among these pathological processes, neuroinflammation plays a predominant role in AD etiopathology. In AD mouse models, increased neuroinflammation appears earlier than Aβ plaques and NFTs, and in DS and AD models, neuroinflammation exacerbates the levels of soluble and insoluble Aβ species, favoring neurodegeneration. The Ts65Dn (TS) mouse, the most commonly used murine model of DS, recapitulates many alterations present in both DS and AD individuals, including enhanced neuroinflammation. In this study, we observed an altered neuroinflammatory milieu in the hippocampus of the TS mouse model. Pro-inflammatory mediators that were elevated in the hippocampus of this model included pro-inflammatory cytokine IL17A, which has a fundamental role in mediating brain damage in neuroinflammatory processes. Here, we analyzed the ability of an anti-IL17A antibody to reduce the neuropathological alterations that are present in TS mice during early neurodevelopmental stages (i.e., hippocampal neurogenesis and hypocellularity) or that are aggravated in later-life stages (i.e., cognitive abilities, cholinergic neuronal loss and increased cellular senescence, APP expression, Aβ peptide expression and neuroinflammation). Administration of anti-IL17 for 5 months, starting at the age of 7 months, partially improved the cognitive abilities of the TS mice, reduced the expression of several pro-inflammatory cytokines and the density of activated microglia and normalized the APP and Aβ_1-42 levels in the hippocampi of the TS mice. These results suggest that IL17-mediated neuroinflammation is involved in several AD phenotypes in TS mice and provide a new therapeutic target to reduce these pathological characteristics.

Prophylactic treatment against GM-CSF, but not IL-17, abolishes relapses in a chronic murine model of multiple sclerosis

The pathogenic role of IL-17 and GM-CSF has been unravelled in experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis (MS). However, in most models, EAE is characterised by a monophasic attack which is not representative of the relapsing nature nor the chronicity displayed in MS. Here, we used proteolipid protein peptide (PLP_139-151 ) to trigger EAE-relapses (EAE-II) in SJL mice that had recovered from a primary-EAE episode (EAE-I). This procedure resulted in severe and irreversible disease that, unlike EAE-I, was not abolished by anti-IL-17-mAb. In contrast, prophylactic anti-GM-CSF-mAb treatment prevented EAE-I and -II. Strikingly, the expression of T-cell transcription factors and cytokines/chemokines in mice treated with anti-GM-CSF during both EAE episodes was silenced. Anti-GM-CSF-mAb treatment administered only during EAE-II did not completely prevent relapses but mice ultimately reached full recovery. Anti-GM-CSF treatment also strongly impaired and ultimately resolved monophasic MOG_35-55 -induced EAE in C57Bl/6 mice. In such protected mice, anti-GM-CSF treatment also prevented a further relapse induced by MOG-revaccination. These results underscore the critical role of GM-CSF on pro-inflammatory mediator production. Furthermore, we observed a strong preventive and curative effect of anti-GM-CSF neutralisation in two EAE models, relapsing and chronic. Altogether these findings are relevant for further MS research.

Optimization of molecularly targeted MRI in the brain: empirical comparison of sequences and particles

BACKGROUND

Molecular MRI is an evolving field of research with strong translational potential. Selection of the appropriate MRI sequence, field strength and contrast agent depend largely on the application. The primary aims of the current study were to: 1) assess the sensitivity of different MRI sequences for detection of iron oxide particles in mouse brain; 2) determine the effect of magnetic field strength on detection of iron oxide particles in vivo; and 3) compare the sensitivity of targeted microparticles of iron oxide (MPIO) or ultra-small superparamagnetic iron oxide (USPIO) for detection of vascular cell adhesion molecule-1 (VCAM-1) in vivo.

METHODS

Mice were injected intrastriatally with interleukin 1β to induce VCAM-1 expression on the cerebral vasculature. Subsequently, animals were injected intravenously with either VCAM-MPIO or VCAM-USPIO and imaged 1 or 13 hours post-injection, respectively. MRI was performed at 4.7, 7.0, or 9.4 T, using three different T2*-weighted sequences: single gradient echo 3D (GE3D), multi-gradient echo 3D (MGE3D) and balanced steady-state free precession 3D (bSSFP3D).

RESULTS

MGE3D yielded the highest signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) for the detection of iron oxide particles. All sequences showed a significant increase in SNR and CNR from 4.7 to 7.0 T, but no further improvement at 9.4 T. However, whilst targeted MPIO enabled sensitive detection of VCAM-1 expression on the cerebral vasculature, the long half-life (16.5 h vs 1.2 min) and lower relaxivity per particle (1.29×10-14 vs 1.18×10-9 Hz L/particle) of USPIO vs. MPIO rendered them impractical for molecular MRI.

CONCLUSION

These findings demonstrate clear advantages of MPIO compared to USPIO for molecularly-targeted MRI, and indicate that the MGE3D sequence is optimal for MPIO detection. Moreover, higher field strengths (7.0/9.4 T) showed enhanced sensitivity over lower field strengths (4.7 T). With the development of biodegradable MPIO, these agents hold promise for clinical translation.

IL17/IL17RA as a Novel Signaling Axis Driving Mesenchymal Stem Cell Therapeutic Function in Experimental Autoimmune Encephalomyelitis

The therapeutic effect of mesenchymal stem cells (MSCs) in multiple sclerosis (MS) and the experimental autoimmune encephalomyelitis (EAE) model has been well described. This effect is, in part, mediated through the inhibition of IL17-producing cells and the generation of regulatory T cells. While proinflammatory cytokines such as IFNγ, TNFα, and IL1β have been shown to enhance MSCs immunosuppressive function, the role of IL17 remains poorly elucidated. The aim of this study was, therefore, to investigate the role of the IL17/IL17R pathway on MSCs immunoregulatory effects focusing on Th17 cell generation in vitro and on Th17-mediated EAE pathogenesis in vivo. In vitro, we showed that the immunosuppressive effect of MSCs on Th17 cell proliferation and differentiation is partially dependent on IL17RA expression. This was associated with a reduced expression level of MSCs immunosuppressive mediators such as VCAM1, ICAM1, and PD-L1 in IL17RA^-/- MSCs as compared to wild-type (WT) MSCs. In the EAE model, we demonstrated that while WT MSCs significantly reduced the clinical scores of the disease, IL17RA^-/- MSCs injected mice exhibited a clinical worsening of the disease. The disability of IL17RA^-/- MSCs to reduce the progression of the disease paralleled the inability of these cells to reduce the frequency of Th17 cells in the draining lymph node of the mice as compared to WT MSCs. Moreover, we showed that the therapeutic effect of MSCs was correlated with the generation of classical Treg bearing the CD4⁺CD25⁺Foxp3⁺ signature in an IL17RA-dependent manner. Our findings reveal a novel role of IL17RA on MSCs immunosuppressive and therapeutic potential in EAE and suggest that the modulation of IL17RA in MSCs could represent a novel method to enhance their therapeutic effect in MS.

Molecular Magnetic Resonance Imaging of Endothelial Activation in the Central Nervous System

Endothelial cells of the central nervous system over-express surface proteins during neurological disorders, either as a cause, or a consequence, of the disease. Since the cerebral vasculature is easily accessible by large contrast-carrying particles, it constitutes a target of choice for molecular magnetic resonance imaging (MRI). In this review, we highlight the most recent advances in molecular MRI of brain endothelial activation and focus on the development of micro-sized particles of iron oxide (MPIO) targeting adhesion molecules including intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), P-Selectin and E-Selectin. We also discuss the perspectives and challenges for the clinical application of this technology in neurovascular disorders (ischemic stroke, intracranial hemorrhage, subarachnoid hemorrhage, diabetes mellitus), neuroinflammatory disorders (multiple sclerosis, brain infectious diseases, sepsis), neurodegenerative disorders (Alzheimer's disease, vascular dementia, aging) and brain cancers (primitive neoplasms, metastasis).

Monoclonal Antibodies in Preclinical EAE Models of Multiple Sclerosis: A Systematic Review

Monoclonal antibodies (mAb) are promising therapeutics in multiple sclerosis and multiple new candidates have been developed, hence increasing the need for some agreement for preclinical mAb studies. We systematically analyzed publications of experimental autoimmune encephalomyelitis (EAE) studies showing effects of monoclonal antibodies. A PubMed search retrieved 570 records, out of which 122 studies with 253 experiments were eligible based on experimental design, number of animals and presentation of time courses of EAE scores. Analysis of EAE models, treatment schedules, single and total doses, routes of administration, and onset of treatment from pre-immunization up to 35 days after immunization revealed high heterogeneity. Total doses ranged from 0.1 to 360 mg/kg for observation times of up to 35 days after immunization. About half of experiments (142/253) used total doses of 10-70 mg/kg. Employing this range, we tested anti-Itga4 as a reference mAb at varying schedules and got no, mild or substantial EAE-score reductions, depending on the mouse strain and onset of the treatment. The result agrees with the range of outcomes achieved in 10 reported anti-Itga4 experiments. Studies comparing low and high doses of various mAbs or early vs. late onset of treatment did not reveal dose-effect or timing-effect associations, with a tendency towards better outcomes with preventive treatments starting within the first week after immunization. The systematic comparison allows for extraction of some "common" design characteristics, which may be helpful to further assess the efficacy of mAbs and role of specific targets in preclinical models of multiple sclerosis.

Prediction of disease activity in models of multiple sclerosis by molecular magnetic resonance imaging of P-selectin

New strategies for detecting disease activity in multiple sclerosis are being investigated to ameliorate diagnosis and follow-up of patients. Today, although magnetic resonance imaging (MRI) is widely used to diagnose and monitor multiple sclerosis, no imaging tools exist to predict the evolution of disease and the efficacy of therapeutic strategies. Here, we show that molecular MRI targeting the endothelial adhesion molecule P-selectin unmasks the pathological events that take place in the spinal cord of mice subjected to chronic or relapsing experimental autoimmune encephalomyelitis. This approach provides a quantitative spatiotemporal follow-up of disease course in relation to clinical manifestations. Moreover, it predicts relapse in asymptomatic mice and remission in symptomatic animals. Future molecular MRI targeting P-selectin may be used to improve diagnosis, follow-up of treatment, and management of relapse/remission cycles in multiple sclerosis patients by providing information currently inaccessible through conventional MRI techniques.

Interleukin 17A Promotes Lymphocytes Adhesion and Induces CCL2 and CXCL1 Release from Brain Endothelial Cells

The nature of the interaction between Th17 cells and the blood-brain barrier (BBB) is critical for the development of autoimmune inflammation in the central nervous system (CNS). Tumor necrosis factor alpha (TNF-α) or interleukin 17 (IL-17) stimulation is known to enhance the adherence of Th17 cells to the brain endothelium. The brain endothelial cells (bEnd.3) express Vascular cell adhesion molecule 1 (VCAM-1), the receptor responsible for inflammatory cell adhesion, which binds very late antigen 4 (VLA-4) on migrating effector lymphocytes at the early stage of brain inflammation. The present study examines the effect of the pro-inflammatory cytokines TNF-α and IL-17 on the adherence of Th17 cells to bEnd.3. The bEnd.3 cells were found to increase production of CCL2 and CXCL1 after stimulation by pro-inflammatory cytokines, while CCL2, CCL5, CCL20 and IL17 induced Th17 cell migration through a bEnd.3 monolayer. This observation may suggest potential therapeutic targets for the prevention of autoimmune neuroinflammation development in the CNS.

Interleukin 17A Promotes Lymphocytes Adhesion and Induces CCL2 and CXCL1 Release from Brain Endothelial Cells

The nature of the interaction between Th17 cells and the blood-brain barrier (BBB) is critical for the development of autoimmune inflammation in the central nervous system (CNS). Tumor necrosis factor alpha (TNF-α) or interleukin 17 (IL-17) stimulation is known to enhance the adherence of Th17 cells to the brain endothelium. The brain endothelial cells (bEnd.3) express Vascular cell adhesion molecule 1 (VCAM-1), the receptor responsible for inflammatory cell adhesion, which binds very late antigen 4 (VLA-4) on migrating effector lymphocytes at the early stage of brain inflammation. The present study examines the effect of the pro-inflammatory cytokines TNF-α and IL-17 on the adherence of Th17 cells to bEnd.3. The bEnd.3 cells were found to increase production of CCL2 and CXCL1 after stimulation by pro-inflammatory cytokines, while CCL2, CCL5, CCL20 and IL17 induced Th17 cell migration through a bEnd.3 monolayer. This observation may suggest potential therapeutic targets for the prevention of autoimmune neuroinflammation development in the CNS.

Memory B Cells are Major Targets for Effective Immunotherapy in Relapsing Multiple Sclerosis

Although multiple sclerosis (MS) is considered to be a CD4, Th17-mediated autoimmune disease, supportive evidence is perhaps circumstantial, often based on animal studies, and is questioned by the perceived failure of CD4-depleting antibodies to control relapsing MS. Therefore, it was interestingly to find that current MS-treatments, believed to act via T cell inhibition, including: beta-interferons, glatiramer acetate, cytostatic agents, dimethyl fumarate, fingolimod, cladribine, daclizumab, rituximab/ocrelizumab physically, or functionally in the case of natalizumab, also depleted CD19+, CD27+ memory B cells. This depletion was substantial and long-term following CD52 and CD20-depletion, and both also induced long-term inhibition of MS with few treatment cycles, indicating induction-therapy activity. Importantly, memory B cells were augmented by B cell activating factor (atacicept) and tumor necrosis factor (infliximab) blockade that are known to worsen MS. This creates a unifying concept centered on memory B cells that is consistent with therapeutic, histopathological and etiological aspects of MS.

Noninvasive Molecular Imaging of Mouse Atherosclerosis

Molecular imaging offers great potential for noninvasive visualization and quantitation of the cellular and molecular components involved in atherosclerotic plaque stability. In this chapter, we review emerging molecular imaging modalities and approaches for quantitative, noninvasive detection of early biological processes in atherogenesis, including vascular endothelial permeability, endothelial adhesion molecule up-regulation, and macrophage accumulation, with special emphasis on mouse models. We also highlight a number of targeted imaging nanomaterials for assessment of advanced atherosclerotic plaques, including extracellular matrix degradation, proteolytic enzyme activity, and activated platelets using mouse models of atherosclerosis. The potential for clinical translation of molecular imaging nanomaterials for assessment of atherosclerotic plaque biology, together with multimodal approaches is also discussed.

Recent Advances in Monoclonal Antibody Therapies for Multiple Sclerosis

INTRODUCTION

Multiple sclerosis (MS) is the most common chronic inflammatory, demyelinating disease of the CNS and results in neurological disability. Existing immunomodulatory and immunosuppressive approaches lower the number of relapses but do not cure or reverse existing deficits nor improve long-term disability in MS patients.

AREAS COVERED

Monogenic antibodies were described as treatment options for MS, however the immunogenicity of mouse antibodies hampered the efficacy of potential therapeutics in humans. Availability of improved antibody production technologies resulted in a paradigm shift in MS treatment strategies. In this review, an overview of immunotherapies for MS that use conventional monoclonal antibodies reactive to immune system and their properties and mechanisms of action will be discussed, including recent advances in MS therapeutics and highlight natural autoantibodies (NAbs) that directly target CNS cells.

EXPERT OPINION

Recent challenges for MS therapy are the identification of relevant molecular and cellular targets, time frame of treatment, and antibody toxicity profiles to identify safe treatment options for MS patients. The application of monoclonal antibody therapies with better biological efficacy associated with minimum side effects possesses huge clinical potential. Advances in monoclonal antibody technologies that directly target cells of nervous system may promote the CNS regeneration field from bench to bedside.

Intracranial delivery of interleukin-17A via adeno-associated virus fails to induce physical and learning disabilities and neuroinflammation in mice but improves glucose metabolism through AKT signaling pathway

Interleukin-17A (IL-17A) is generally considered as one of the pathogenic factors involved in multiple sclerosis (MS). Indirect evidence for this is that IL-17A-producing T helper 17 (Th17) cells preferentially accumulate in lesions of MS and experimental autoimmune encephalomyelitis (EAE). However, a direct involvement of IL-17A in MS pathogenesis is still an open question. In this study, we overexpressed IL-17A in the brains of mice (IL-17A-in-Brain mice) via recombinant adeno-associated virus serotype 5 (rAAV5)-mediated gene delivery. In spite of high levels of IL-17A expression in the brain and blood, IL-17A-in-Brain mice exhibit no inflammatory responses and no abnormalities in motor coordination and spatial orientation. Unexpectedly, IL-17A-in-Brain mice show decreases in body weight and adipose tissue mass and an improvement in glucose tolerance and insulin sensitivity. IL-17A enhances glucose uptake in PC12 cells by activation of AKT. Our results provide direct evidence for the first time that IL-17A overexpression in the central nervous system does not cause physical and learning disabilities and neuroinflammation and suggest that IL-17A may regulate glucose metabolism through the AKT signaling pathway.

IL-17 in Chronic Inflammation: From Discovery to Targeting

Interleukin-17 (IL-17) is a cytokine which elicits protection against extracellular bacterial and fungal infections and which plays important roles in inflammation. However, when produced in excess, it contributes to chronic inflammation associated with many inflammatory and autoimmune disorders. This has made IL-17 an attractive therapeutic target. The present review describes the structure of the IL-17 family, the IL-17 receptor complex, and the cells producing IL-17. The contributions of IL-17 to disease as well as new IL-17-based treatment options are discussed. Finally, the results of IL-17 or IL-17 receptor inhibitors in clinical trials are detailed. With a fruitful outlook, drug registration has now been granted for psoriasis psoriatic arthritis and ankylosing spondylitis, and also bears great potential in a growing number of conditions.

Thymic stromal lymphopoietin-induced interleukin-17A is involved in the development of IgE-mediated atopic dermatitis-like skin lesions in mice

Atopic dermatitis (AD) is a chronic inflammatory skin disease associated with elevated levels of allergen-specific IgE. Although thymic stromal lymphopoietin (TSLP) and interleukin-17A (IL-17A) have been considered as important factors in allergic diseases, their relationships in AD have not been fully defined. Here, we show the contribution of TSLP-induced IL-17A responses to IgE-mediated AD-like skin lesions. BALB/c mice passively sensitized by intraperitoneal injections of ovalbumin (OVA)-specific IgE monoclonal antibody (mAb) were challenged with OVA applied to the skin six times. Treatment with anti-TSLP mAb during the second to sixth challenges inhibited IgE-mediated AD-like skin lesions and IL-17A production in lymph nodes. Furthermore, the increased number of IL-17A-producing CD4(+) and γδ T cells in lymph nodes and neutrophilic inflammation in the skin were reduced by anti-TSLP mAb. These findings prompted us to examine the roles of IL-17A. Treatment with anti-IL-17A mAb suppressed the AD-like skin lesions and neutrophilic inflammation; anti-Gr-1 mAb also inhibited them. Furthermore, treatment with CXCR2 antagonist reduced the AD-like skin lesions and neutrophilic inflammation accompanied by the reduction of IL-17A production; the increased CXCR2 expression in the epidermal cells was suppressed by anti-TSLP mAb. Meanwhile, these treatments, except for anti-Gr-1 mAb, inhibited the increased mast cell accumulation in the skin. Collectively, the mechanism of IgE mediating IL-17A-producing CD4(+) and γδ T cells through TSLP by repeated antigen challenges is involved in AD-like skin lesions associated with skin inflammation, such as neutrophil and mast cell accumulation; TSLP may regulate CXCR2 signalling-induced IL-17A production.

NMR-Based Metabolomics Separates the Distinct Stages of Disease in a Chronic Relapsing Model of Multiple Sclerosis

Relapsing experimental allergic encephalomyelitis (Cr-EAE) is commonly used to explore the pathogenesis and efficacy of new therapies for MS, but it is unclear whether the metabolome of Cr-EAE is comparable to human multiple sclerosis (MS). For MS, the diagnosis and staging can be achieved by metabolomics on blood using a combination of magnetic resonance spectroscopy and partial least squares discriminant analysis (PLS-DA). Here, we sought to discover whether this approach could be used to differentiate between sequential disease states in Cr-EAE and whether the same metabolites would be discriminatory. Urine and plasma samples were obtained at different time-points from a clinically relevant model of MS. Using PLS-DA modelling for the urine samples furnished some predictive models, but could not discriminate between all disease states. However, PLS-DA modelling of the plasma samples was able to distinguish between animals with clinically silent disease (day 10, 28) and animals with active disease (day 14, 38). We were also able to distinguish Cr-EAE mice from naive mice at all-time points and control mice, treated with complete Freund's adjuvant alone, at day 14 and 38. Key metabolites that underpin these models included fatty acids, glucose and taurine. Two of these metabolites, fatty acids and glucose, were also key metabolites in separating relapsing-remitting MS from secondary-progressive MS in the human study. These results demonstrate the sensitivity of this metabolomics approach for distinguishing between different disease states. Furthermore, some, but not all, of the changes in metabolites were conserved in humans and the mouse model, which could be useful for future drug development.

The role of IL-17 in CNS diseases

Cytokines of the IL-17 family are uniquely placed on the border between immune cells and tissue. Although IL-17 was originally found to induce the activation and mobilization of neutrophils to sites of inflammation, its tissue-specific function is not yet fully understood. The best-studied IL-17 family members, IL-17A and IL-17F, are both typically produced by immune cells such as Th17, γδ T cells and innate lymphoid cells group 3. However, the cells that respond to these cytokines are mostly found in inflamed tissue. As seen in psoriatic skin lesions or in joints of rheumatoid arthritis patients, high levels of IL-17 have been detected in the central nervous system (CNS) during inflammatory responses. Here, we provide a general review of the molecular function of IL-17 and its role in the CNS in particular. Of the different inflammatory conditions of the CNS, we found multiple sclerosis (MS) to be the one most associated with the presence of Th17 cells and IL-17. In particular, many studies using the murine model for MS, experimental autoimmune encephalomyelitis, found a clear association of Th17 and IL-17 with disease severity and progression. We summarize the recent advances made in correlating the presence of IL-17 with impaired blood-brain barrier integrity as well as the activation of astrocytes and microglia and the consequences for disease progression. There is also evidence that IL-17 plays a pathogenic role in the post-ischemic phase of stroke as well as its experimental model. We review the limited but promising data on the sources of post-stroke IL-17 production and its effects on CNS-resident target cells. In addition to MS and stroke, there is also evidence linking high levels of IL-17 to depression, as a frequent comorbidity of several inflammatory diseases, as well as to different types of infections of the CNS. The evidence we supply here suggests that inhibiting the function of the IL-17 cytokine family could have a beneficial effect on pathogenic conditions in the CNS.

[Contrast agents in MRI-diagnosis of multiple sclerosis]

Magnetic resonance imaging using contrast agents plays an important role in diagnosis and assessment of treatment efficacy in multiple sclerosis. The development of contrast agents on the basis of gadolinium or iron oxide nanoparticles has potential for diagnosis of pathological foci (tumors, amyloid plaques, inflammation and foci of demyelination or necrosis) in nervous system diseases. Newly developing types of diagnostic substances for visualization of pathological foci in multiple sclerosis are presented in this review.

Molecular magnetic resonance imaging of brain-immune interactions

Although the blood-brain barrier (BBB) was thought to protect the brain from the effects of the immune system, immune cells can nevertheless migrate from the blood to the brain, either as a cause or as a consequence of central nervous system (CNS) diseases, thus contributing to their evolution and outcome. Accordingly, as the interface between the CNS and the peripheral immune system, the BBB is critical during neuroinflammatory processes. In particular, endothelial cells are involved in the brain response to systemic or local inflammatory stimuli by regulating the cellular movement between the circulation and the brain parenchyma. While neuropathological conditions differ in etiology and in the way in which the inflammatory response is mounted and resolved, cellular mechanisms of neuroinflammation are probably similar. Accordingly, neuroinflammation is a hallmark and a decisive player of many CNS diseases. Thus, molecular magnetic resonance imaging (MRI) of inflammatory processes is a central theme of research in several neurological disorders focusing on a set of molecules expressed by endothelial cells, such as adhesion molecules (VCAM-1, ICAM-1, P-selectin, E-selectin, …), which emerge as therapeutic targets and biomarkers for neurological diseases. In this review, we will present the most recent advances in the field of preclinical molecular MRI. Moreover, we will discuss the possible translation of molecular MRI to the clinical setting with a particular emphasis on myeloperoxidase imaging, autologous cell tracking, and targeted iron oxide particles (USPIO, MPIO).

Nanomedicine in autoimmunity

The application of nanotechnology to the diagnosis and therapy of human diseases is already a reality and is causing a real revolution in how we design new therapies and vaccines. In this review we focus on the applications of nanotechnology in the field of autoimmunity. First, we review scenarios in which iron oxide nanoparticles have been used in the diagnosis of autoimmune diseases, mostly through magnetic resonance imaging (MRI), both in animal models and patients. Second, we discuss the potential of nanoparticles as an immunotherapeutic platform for autoimmune diseases, for now exclusively in pre-clinical models. Finally, we discuss the potential of this field to generate the 'perfect drug' with the capacity to report on its therapeutic efficacy in real time, that is, the birth of theranostics in autoimmunity.