Effects of early IL-17A neutralization on disease induction in a primate model of experimental autoimmune encephalomyelitis

Delimiting MOGAD as a disease entity using translational imaging

The first formal consensus diagnostic criteria for myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) were recently proposed. Yet, the distinction of MOGAD-defining characteristics from characteristics of its important differential diagnoses such as multiple sclerosis (MS) and aquaporin-4 antibody seropositive neuromyelitis optica spectrum disorder (NMOSD) is still obstructed. In preclinical research, MOG antibody-based animal models were used for decades to derive knowledge about MS. In clinical research, people with MOGAD have been combined into cohorts with other diagnoses. Thus, it remains unclear to which extent the generated knowledge is specifically applicable to MOGAD. Translational research can contribute to identifying MOGAD characteristic features by establishing imaging methods and outcome parameters on proven pathophysiological grounds. This article reviews suitable animal models for translational MOGAD research and the current state and prospect of translational imaging in MOGAD.

Anti-inflammatory mechanisms and pharmacological actions of phycocyanobilin in a mouse model of experimental autoimmune encephalomyelitis: A therapeutic promise for multiple sclerosis

Cytokines, demyelination and neuroaxonal degeneration in the central nervous system are pivotal elements implicated in the pathogenesis of multiple sclerosis (MS) and its nonclinical model of experimental autoimmune encephalomyelitis (EAE). Phycocyanobilin (PCB), a chromophore of the biliprotein C-Phycocyanin (C-PC) from Spirulina platensis, has antioxidant, immunoregulatory and anti-inflammatory effects in this disease, and it could complement the effect of other Disease Modifying Treatments (DMT), such as Interferon-β (IFN-β). Here, our main goal was to evaluate the potential PCB benefits and its mechanisms of action to counteract the chronic EAE in mice. MOG_35-55-induced EAE was implemented in C57BL/6 female mice. Clinical signs, pro-inflammatory cytokines levels by ELISA, qPCR in the brain and immunohistochemistry using precursor/mature oligodendrocytes cells antibodies in the spinal cord, were assessed. PCB enhanced the neurological condition, and waned the brain concentrations of IL-17A and IL-6, pro-inflammatory cytokines, in a dose-dependent manner. A down- or up-regulating activity of PCB at 1 mg/kg was identified in the brain on three (LINGO1, NOTCH1, and TNF-α), and five genes (MAL, CXCL12, MOG, OLIG1, and NKX2-2), respectively. Interestingly, a reduction of demyelination, active microglia/macrophages density, and axonal damage was detected along with an increase in oligodendrocyte precursor cells and mature oligodendrocytes, when assessed the spinal cords of EAE mice that took up PCB. The studies in vitro in rodent encephalitogenic T cells and in vivo in the EAE mouse model with the PCB/IFN-β combination, showed an enhanced positive effect of this combined therapy. Overall, these results demonstrate the anti-inflammatory activity and the protective properties of PCB on the myelin and support its use with IFN-β as an improved DMT combination for MS.

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.

Experimental autoimmune encephalomyelitis in the common marmoset: a translationally relevant model for the cause and course of multiple sclerosis

Aging Western societies are facing an increasing prevalence of chronic autoimmune-mediated inflammatory disorders (AIMIDs) for which treatments that are safe and effective are scarce. One of the main reasons for this situation is the lack of animal models, which accurately replicate clinical and pathological aspects of the human diseases. One important AIMID is the neuroinflammatory disease multiple sclerosis (MS), for which the mouse experimental autoimmune encephalomyelitis (EAE) model has been frequently used in preclinical research. Despite some successes, there is a long list of experimental treatments that have failed to reproduce promising effects observed in murine EAE models when they were tested in the clinic. This frustrating situation indicates a wide validity gap between mouse EAE and MS. This monography describes the development of an EAE model in nonhuman primates, which may help to bridge the gap.

Intrathecal delivery of human ESC-derived mesenchymal stem cell spheres promotes recovery of a primate multiple sclerosis model

Nonhuman primate experimental autoimmune encephalomyelitis (EAE) is a valuable model for multiple sclerosis, an inflammatory demyelinating disease in the central nervous system (CNS). Human embryonic stem cell-derived mesenchymal stem cells (EMSC) are effective in treating murine EAE. Yet, it remains unknown whether the EMSC efficacy is translatable to humans. Here we induced a primate EAE model in cynomolgus monkeys and delivered EMSC in spheres (EMSC_sp) to preserve the cell viability during long-distance transportation. EMSC_sp intrathecally injected into the CNS, remarkably reduced the clinical symptoms, brain lesions, and neuronal demyelination in the EAE monkeys during a 3-month observation. Whereas, symptoms in the vehicle control-injected EAE monkey remained and reduced slowly and MRI lesions in brain expanded. Moreover, EMSC could transdifferentiate into neural cells in vivo in the CNS of the treated animals. Supporting evidence demonstrated that EMSC_sp cells cultured in cerebrospinal fluid from the EAE monkeys largely converted to neural cells with elevated expression of genes for neuronal markers, neurotrophic factors, and neuronal myelination. Thus, this study demonstrates that EMSC_sp injected directly into the CNS, can attenuate the disease progression in the primate EAE model, highly encouraging for clinical translation.

Fingolimod inhibits brain atrophy and promotes brain-derived neurotrophic factor in an animal model of multiple sclerosis

Longitudinal brain atrophy quantification is a critical efficacy measurement in multiple sclerosis (MS) clinical trials and the determination of No Evidence of Disease Activity (NEDA). Utilising fingolimod as a clinically validated therapy we evaluated the use of repeated brain tissue volume measures during chronic experimental autoimmune encephalomyelitis (EAE) as a new preclinical efficacy measure. Brain volume changes were quantified using magnetic resonance imaging (MRI) at 7 Tesla and correlated to treatment-induced brain derived neurotrophic factor (BDNF) measured in blood, cerebrospinal fluid, spinal cord and brain. Serial brain MRI measurements revealed slow progressive brain volume loss in vehicle treated EAE mice despite a stable clinical score. Fingolimod (1 mg/kg) significantly ameliorated brain tissue atrophy in the cerebellum and striatum when administered from established EAE disease onwards. Fingolimod-dependent tissue preservation was associated with induction of BDNF specifically within the brain and co-localized with neuronal soma. In contrast, therapeutic teriflunomide (3 mg/kg) treatment failed to inhibit CNS autoimmune mediated brain degeneration. Finally, weekly anti-IL-17A antibody (15 mg/kg) treatment was highly efficacious and preserved whole brain, cerebellum and striatum volume. Fingolimod-mediated BDNF increases within the CNS may contribute to limiting progressive tissue loss during chronic neuroinflammation.

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.

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.

An Evaluation of 20 Years of EU Framework Programme-Funded Immune-Mediated Inflammatory Translational Research in Non-Human Primates

Aging western societies are facing an increasing prevalence of chronic inflammatory and degenerative diseases for which often no effective treatments exist, resulting in increasing health-care expenditure. Despite high investments in drug development, the number of promising new drug candidates decreases. We propose that preclinical research in non-human primates can help to bridge the gap between drug discovery and drug prescription. Translational research covers various stages of drug development of which preclinical efficacy tests in valid animal models is usually the last stage. Preclinical research in non-human primates may be essential in the evaluation of new drugs or therapies when a relevant rodent model is not available. Non-human primate models for life-threatening or severely debilitating diseases in humans are available at the Biomedical Primate Research Centre (BPRC). These have been instrumental in translational research for several decades. In order to stimulate European health research and innovation from bench to bedside, the European Commission has invested heavily in access to non-human primate research for more than 20 years. BPRC has hosted European users in a series of transnational access programs covering a wide range of research areas with the common theme being immune-mediated inflammatory disorders. We present an overview of the results and give an account of the studies performed as part of European Union Framework Programme (EU FP)-funded translational non-human primate research performed at the BPRC. These data illustrate the value of translational non-human primate research for the development of new therapies and emphasize the importance of EU FP funding in drug development.

The common marmoset (<i>Callithrix jacchus</i>): a relevant preclinical model of human (auto)immune-mediated inflammatory disease of the brain

Abstract. The increasing prevalence of chronic autoimmune-mediated inflammatory disorders (AIMIDs) in aging human populations creates a high unmet need for safe and effective medications. However, thus far the translation of pathogenic concepts developed in animal models into effective treatments for the patient has been notoriously difficult. The main reason is that currently used mouse-based animal models for the pipeline selection of promising new treatments were insufficiently predictive for clinical success. Regarding the high immunological similarity between human and non-human primates (NHPs), AIMID models in NHPs can help to bridge the translational gap between rodent and man. Here we will review the preclinical relevance of the experimental autoimmune encephalomyelitis (EAE) model in common marmosets (Callithrix jacchus), a small-bodied neotropical primate. EAE is a generic AIMID model projected on the human autoimmune neuro-inflammatory disease multiple sclerosis (MS).

Dual Inhibition of Interleukin-23 and Interleukin-17 Offers Superior Efficacy in Mouse Models of Autoimmunity

Therapies targeting either interleukin (IL)-23 or IL-17 have shown promise in treating T helper 17 (Th17)-driven autoimmune diseases. Although IL-23 is a critical driver of IL-17, recognition of nonredundant and independent functions of IL-23 and IL-17 has prompted the notion that dual inhibition of both IL-23 and IL-17 could offer even greater efficacy for treating autoimmune diseases relative to targeting either cytokine alone. To test this hypothesis, we generated selective inhibitors of IL-23 and IL-17 and tested the effect of either treatment alone compared with their combination in vitro and in vivo. In vitro, using a novel culture system of murine Th17 cells and NIH/3T3 fibroblasts, we showed that inhibition of both IL-23 and IL-17 completely suppressed IL-23-dependent IL-22 production from Th17 cells and cooperatively blocked IL-17-dependent IL-6 secretion from the NIH/3T3 cells to levels below either inhibitor alone. In vivo, in the imiquimod induced skin inflammation model, and in the myelin oligodendrocyte glycoprotein peptide-induced experimental autoimmune encephalomyelitis model, we demonstrated that dual inhibition of IL-17 and IL-23 was more efficacious in reducing disease than targeting either cytokine alone. Together, these data support the hypothesis that neutralization of both IL-23 and IL-17 may provide enhanced benefit against Th17 mediated autoimmunity and provide a basis for a therapeutic strategy aimed at dual targeting IL-23 and IL-17.

The primate autoimmune encephalomyelitis model; a bridge between mouse and man

Introduction

Multiple sclerosis (MS) is an enigmatic autoimmune-driven inflammatory/demyelinating disease of the human central nervous system (CNS), affecting brain, spinal cord, and optic nerves. The cause of the disease is not known and the number of effective treatments is limited. Despite some clear successes, translation of immunological discoveries in the mouse experimental autoimmune encephalomyelitis (EAE) model into effective therapies for MS patients has been difficult. This translation gap between MS and its elected EAE animal model reflects the phylogenetic distance between humans and their experimental counterpart, the inbred/specific pathogen free (SPF) laboratory mouse.

Objective

Here, we discuss that important new insights can be obtained into the mechanistic basis of the therapy paradox from the study of nonhuman primate EAE (NHP-EAE) models, the well-validated EAE model in common marmosets (Callithrix jacchus) in particular.

Interpretation

Data presented in this review demonstrate that due to a considerable immunological and pathological overlap with mouse EAE on one side and MS on the other, the NHP EAE model can help us bridge the translation gap.

Nanomaterial applications in multiple sclerosis inflamed brain

In the last years scientific progress in nanomaterials, where size and shape make the difference, has increased their utilization in medicine with the development of a promising new translational science: nanomedicine. Due to their surface and core biophysical properties, nanomaterials hold the promise for medical applications in central nervous system (CNS) diseases: inflammatory, degenerative and tumors. The present review is focused on nanomaterials at the neuro-immune interface, evaluating two aspects: the possible CNS inflammatory response induced by nanomaterials and the developments of nanomaterials to improve treatment and diagnosis of neuroinflammatory diseases, with a focus on multiple sclerosis (MS). Indeed, nanomedicine allows projecting new ways of drug delivery and novel techniques for CNS imaging. Despite the wide field of application in neurological diseases of nanomaterials, our topic here is to review the more recent development of nanomaterials that cross blood brain barrier (BBB) and reach specific target during CNS inflammatory diseases, a crucial strategy for CNS early diagnosis and drug delivery, indeed the main challenges of nanomedicine.

CNS-targeted production of IL-17A induces glial activation, microvascular pathology and enhances the neuroinflammatory response to systemic endotoxemia

Interleukin-17A (IL-17A) is a key cytokine modulating the course of inflammatory diseases. Whereas effector functions of IL-17A like induction of antimicrobial peptides and leukocyte infiltration could clearly be demonstrated for peripheral organs, CNS specific effects are not well defined and appear controversial. To further clarify the functional significance of IL-17A in the CNS, we generated a transgenic mouse line with astrocyte-restricted expression of the IL-17A gene. GFAP/IL-17A transgenic mice develop normally and do not show any signs of neurological dysfunction. However, histological characterization revealed astrocytosis and activation of microglia. Demyelination, neurodegeneration or prominent tissue damage was not observed but a vascular pathology mimicking microangiopathic features was evident. Histological and flow cytometric analysis demonstrated the absence of parenchymal infiltration of immune cells into the CNS of GFAP/IL-17A transgenic mice. In GFAP/IL-17A mice, LPS-induced endotoxemia led to a more pronounced microglial activation with expansion of a distinct CD45(high)/CD11b(+) population and increased induction of proinflammatory cytokines compared with controls. Our data argues against a direct role of IL-17A in mediating tissue damage during neuroinflammation. More likely IL-17A acts as a modulating factor in the network of induced cytokines. This novel mouse model will be a very useful tool to further characterize the role of IL-17A in neuroinflammatory disease models.

Novel marmoset (Callithrix jacchus) model of human Herpesvirus 6A and 6B infections: immunologic, virologic and radiologic characterization

Human Herpesvirus 6 (HHV-6) is a ubiquitous virus with an estimated seroprevalence of 95% in the adult population. HHV-6 is associated with several neurologic disorders, including multiple sclerosis, an inflammatory demyelinating disease affecting the CNS. Animal models of HHV-6 infection would help clarify its role in human disease but have been slow to develop because rodents lack CD46, the receptor for cellular entry. Therefore, we investigated the effects of HHV-6 infections in a non-human primate, the common marmoset Callithrix jacchus. We inoculated a total of 12 marmosets with HHV-6A and HHV-6B intravenously and HHV-6A intranasally. Animals were monitored for 25 weeks post-inoculation clinically, immunologically and by MRI. Marmosets inoculated with HHV-6A intravenously exhibited neurologic symptoms and generated virus-specific antibody responses, while those inoculated intravenously with HHV-6B were asymptomatic and generated comparatively lower antibody responses. Viral DNA was detected at a low frequency in paraffin-embedded CNS tissue of a subset of marmosets inoculated with HHV-6A and HHV-6B intravenously. When different routes of HHV-6A inoculation were compared, intravenous inoculation resulted in virus-specific antibody responses and infrequent detection of viral DNA in the periphery, while intranasal inoculation resulted in negligible virus-specific antibody responses and frequent detection of viral DNA in the periphery. Moreover, marmosets inoculated with HHV-6A intravenously exhibited neurologic symptoms, while marmosets inoculated with HHV-6A intranasally were asymptomatic. We demonstrate that a marmoset model of HHV-6 infection can serve to further define the contribution of this ubiquitous virus to human neurologic disorders.

Chronic autoimmune-mediated inflammation: a senescent immune response to injury

The increasing prevalence of chronic autoimmune-mediated inflammatory diseases (AIMIDs) in ageing western societies is a major challenge for the drug development industry. The current high medical need for more-effective treatments is at least in part caused by our limited understanding of the mechanisms that drive chronic inflammation. Here, we postulate a role for immunosenescence in the progression of acute to chronic inflammation via a dysregulated response to primary injury at the level of the damaged target organ. A corollary to this notion is that treatment of acute versus chronic phases of disease might require differential targeting strategies.

The inhibition of Th17 immune response in vitro and in vivo by the carbosilane dendrimer 2G-NN16

We evaluated the 2G-NN16-carbosilane dendrimer activities in Th17 response as a potential therapy for Th17 deregulated pathologies. IL17A, IL17F, IL22, IL23 and other interleukins secreted by Th17 cells CD4+ cells were down regulated when cells were cultured in the presence of this dendrimer. Furthermore, IL17F and IL17A protein levels in splenocytes from mice pretreated with 2G-NN16 dendrimer in a Th17 induction mouse model were lower than those corresponding to PBS treated mice. Treatment of mice with 2G-NN16 inhibited the Th17 response causing much more pathogenicity as indicated by the increase in the number of Candida albicans colonies in the kidneys as compared to PBS-treated mice. All these results suggest a potential pharmacological application for this dendrimer in the therapy of Th17-mediated diseases.