Erwin L. A. Blezer

Prevention of Experimental Autoimmune Encephalomyelitis in Common Marmosets Using an Anti-IL-12p40 Monoclonal Antibody

The experimental autoimmune encephalomyelitis (EAE) model in the common marmoset approximates recognized features of the human disease multiple sclerosis (MS) with regard to its clinical presentation as well as neuropathological and radiological aspects of the lesions in brain and spinal cord. IL-12 is a proinflammatory cytokine that is produced by APC and promotes differentiation of Th1 effector cells. IL-12 is produced in the developing lesions of patients with MS as well as in EAE-affected animals. Previously it was shown that interference in IL-12 pathways effectively prevents EAE in rodents. In this study we report that in vivo neutralization of IL-12p40 using a novel Ab has beneficial effects in the myelin-induced EAE model in common marmosets. The Ab was injected i.v. at 7-day intervals starting well after immunization (day 14) and was continued until the end of the study (day 86). Stable levels of the Ab were measured 3 days after each injection throughout the study period. During this period anti-Ab responses could not be detected. We demonstrate that anti-IL-12p40 treatment has a protective effect on the neurological dysfunction as well as on neuropathological changes normally observed in the brain and spinal cord of EAE-affected individuals.

Human neural stem cells ameliorate autoimmune encephalomyelitis in non-human primates†

Transplanted neural stem/precursor cells (NPCs) display peculiar therapeutic plasticity in vivo. Although the replacement of cells was first expected as the prime therapeutic mechanism of stem cells in regenerative medicine, it is now clear that transplanted NPCs simultaneously instruct several therapeutic mechanisms, among which replacement of cells might not necessarily prevail. A comprehensive understanding of the mechanism(s) by which NPCs exert their therapeutic plasticity is lacking. This study was designed as a preclinical approach to test the feasibility of human NPC transplantation in an outbreed nonhuman primate experimental autoimmune encephalomyelitis (EAE) model approximating the clinical and complex neuropathological situation of human multiple sclerosis (MS) more closely than EAE in the standard laboratory rodent.

Prevention of Experimental Autoimmune Encephalomyelitis in the Common Marmoset ( Callithrix jacchus ) Using a Chimeric Antagonist Monoclonal Antibody Against Human CD40 Is Associated with Altered B Cell Responses

Inhibition of CD40-CD40 ligand interaction is a potentially effective approach for treatment of autoimmune diseases, such as multiple sclerosis. We have investigated this concept with a chimeric antagonist anti-human CD40 mAb (ch5D12) in the marmoset monkey experimental autoimmune encephalomyelitis (EAE) model. Marmosets were immunized with recombinant human myelin oligodendrocyte glycoprotein (rMOG) and treated from the day before immunization (day −1) until day 50 with either ch5D12 (5 mg/kg every 2–4 days) or placebo. On day 41 after the induction of EAE, four of four placebo-treated monkeys had developed severe clinical EAE, whereas all animals from the ch5D12-treated group were completely free of disease symptoms. High serum levels of ch5D12 associated with complete coating of CD40 on circulating B cells were found. At necropsy placebo- and ch5D12-treated animals showed similar MOG-specific lymphoproliferative responses in vitro, but ch5D12 treatment resulted in strongly reduced anti-MOG IgM Ab responses and delayed anti-MOG IgG responses. Most importantly, treatment with ch5D12 prevented intramolecular spreading of epitope recognition. Postmortem magnetic resonance imaging and immunohistologic analysis of the CNS showed a markedly reduced lesion load after ch5D12 treatment. In conclusion, the strong reduction of clinical, pathological, and radiological aspects of EAE by ch5D12 treatment in this preclinical model points to a therapeutic potential of this engineered antagonist anti-CD40 mAb for multiple sclerosis.

Suppression of Ongoing Disease in a Nonhuman Primate Model of Multiple Sclerosis by a Human-Anti-Human IL-12p40 Antibody

IL-12p40 is a shared subunit of two cytokines with overlapping activities in the induction of autoreactive Th1 cells and therefore a potential target of therapy in Th1-mediated diseases. We have examined whether ongoing disease in a nonhuman primate model of multiple sclerosis (MS) can be suppressed with a new human IgG1κ Ab against human IL-12p40. Lesions developing in the brain white matter were visualized and characterized with standard magnetic resonance imaging techniques. To reflect the treatment of MS patients, treatment with the Ab was initiated after active brain white matter lesions were detected in T2-weighted images. In placebo-treated control monkeys we observed the expected progressive increase in the total T2 lesion volume and markedly increased T2 relaxation times, a magnetic resonance imaging marker of inflammation. In contrast, in monkeys treated with anti-IL-12p40 Ab, changes in the total T2 lesion volume and T2 relaxation times were significantly suppressed. Moreover, the time interval to serious neurological deficit was delayed from 31 ± 10 to 64 ± 20 days (odds ratio, 0.312). These results, in a disease model with high similarity to MS, are important for ongoing and planned trials of therapies that target IL-12 and/or IL-23.

Non-human primate models of multiple sclerosis.

Summary: The phylogenetic proximity between non‐human primate species and humans is reflected by a high degree of immunological similarity. Non‐human primates therefore provide important experimental models for disorders in the human population that are caused by the immune system, such as autoimmune diseases. In this paper we describe non‐human primate models of multiple sclerosis, a chronic inflammatory and demyelinating disease of the human central nervous system. While reviewing data from the literature and our own research we will discuss the unique role of such models in the research of basic disease mechanisms and the development of new therapies.

MRI of monocyte infiltration in an animal model of neuroinflammation using SPIO-labeled monocytes or free USPIO

Magnetic resonance imaging (MRI) has been applied to visualize monocyte infiltration with the use of intravenously injected ultrasmall superparamagnetic iron oxide (USPIO). However, USPIO uptake in vivo remains elusive, and the heterogeneous enhancement patterns observed by MRI point to multiple pathophysiological events. This study focused on specific imaging of monocyte infiltration into the brain by transfusion of superparamagnetic iron oxide (SPIO)-labeled monocytes in a rat model of neuroinflammation, experimentally induced photothrombosis (PT). At day 5 after lesion induction, animals were transfused with SPIO-labeled monocytes (5 × 106 cells) or free USPIO (17 mg Fe/kg). MRI was performed 24, 72 and, 120 h later. To investigate temporal changes directly after intravenous USPIO administration, MRI was performed repeatedly up to 8 h. Relaxation measurements showed that rat monocytes were efficiently labeled in vitro using SPIO (R2=12±0.9 s−1). After transfusion of SPIO-labeled monocytes, a significant increase in contrast enhanced area (340%±106%) in the PT lesion was observed not before 72 h. Contrast enhancement after USPIO injection increased up to 407%±39% at a much earlier point of time (24 h) and diminished thereafter. Repetitive MRI directly after USPIO injection showed significant contrast enhancement in the lesion within 2 h. Our study shows that MRI enables in vivo tracking of SPIO-labeled monocytes longitudinally. Moreover, our data suggest that contrast enhancement after injection of free USPIO does not primarily represent signals from peripherally labeled monocytes that migrated toward the inflammatory lesion. The use of SPIO-labeled monocytes provides a better tool to specifically assess the time window of monocyte infiltration.

Does high-field MR imaging improve cortical lesion detection in multiple sclerosis?

ObjectiveCortical lesions in multiple sclerosis (MS) are notoriously difficult to visualize with standard MR imaging (MRI) techniques. However, the use of higher field-strengths with intrinsically higher signal-to-noise, which can partly be used to increase spatial resolution, may improve cortical lesion detection. Therefore, in this post mortem study, the sensitivity of high fieldstrength MRI (4.7 T) for cortical lesions was investigated, and compared to that of standard field-strength (1.5 T).MethodsAt 1.5 T, dual-echo T2-weighted spin-echo, as well as 3D-FLAIR images of seventeen formalin-fixed coronal MS and four control hemispheres were acquired. At 4.7 T, the same specimens were imaged with a mainly proton-density (PD)- weighted sequence. Proteolipid protein (PLP)-stained tissue sections (10 μm) of the same brain slices were matched to the corresponding MR images, and cortical lesions were scored on all three MR sequences (blinded to histology) and in tissue sections (blinded to MRI). Sensitivity of the sequences for four cortical lesion types was calculated. Additionally, an unblinded, retrospective MR scoring was performed.ResultsSensitivity for purely intracortical lesions (histological lesion types II, III, and IV; n = 128) was below 10 % for both 1.5 T and 4.7 T MRI, while mixed gray matter-white matter (type I) lesions (n = 5) were detected in four out of five cases. All lesion counts increased upon retrospective (unblinded) scoring. However, up to 80% of the intracortical lesions still remained undetected.ConclusionsMRI sensitivity for post mortem detection of cortical lesions is low, even when a higher field-strength was used. It varies, however, for different subtypes of cortical lesions.

Antagonizing the α4β1 Integrin, but Not α4β7, Inhibits Leukocytic Infiltration of the Central Nervous System in Rhesus Monkey Experimental Autoimmune Encephalomyelitis

The immune system is characterized by the preferential migration of lymphocytes through specific tissues (i.e., tissue tropism). Tissue tropism is mediated, in part, by the α4 integrins expressed by T lymphocytes. The α4β1 integrin mediates migration of memory T lymphocytes into the CNS, whereas the α4β7 integrin mediates migration preferentially into gastrointestinal tissue. This paradigm was established primarily from investigations in rodents; thus, the objective of this investigation was to determine if blocking the α4β7 integrin exclusively would affect migration of T lymphocytes into the CNS of primates. The effects of the dual α4β1 and α4β7 antagonist natalizumab were compared with those of the α4β7 antagonist vedolizumab on experimental autoimmune encephalomyelitis in the rhesus monkey. Animals received an initial i.v. bolus of placebo, natalizumab (30 mg/kg), or vedolizumab (30 mg/kg) before intracutaneous immunization with recombinant human myelin oligodendrocyte glycoprotein and then Ab once weekly thereafter. Natalizumab prevented CNS inflammation and demyelination significantly (p < 0.05), compared with time-matched placebo control animals, whereas vedolizumab did not inhibit these effects, despite saturating the α4β7 integrin in each animal for the duration of the investigation. These results demonstrate that blocking α4β7 exclusively does not inhibit immune surveillance of the CNS in primates.

Early-Onset But Not Late-Onset Endothelin-A–Receptor Blockade Can Modulate Hypertension, Cerebral Edema, and Proteinuria in Stroke-Prone Hypertensive Rats

-The ability of endothelin receptor blockade to prevent and to treat established cerebral and renal injury was explored in salt-loaded stroke-prone spontaneously hypertensive rats (SHRSP) with the endothelin receptor subtype-A antagonist A127722. SHRSP were subjected to 1% NaCl intake. The start of treatment with A127722 (35 and 70 mg. kg-1. d-1, respectively) was either synchronized with salt loading or initiated after the first observation of cerebral edema with T2-weighted magnetic resonance imaging. In untreated control animals median survival was 54 days (range, 32 to 80 days) after the start of salt loading. Early-onset A127722 treatment increased median survival to 233 days (range, 92 to 407 days; P<0.05 versus controls) with 35 mg/kg and to 124 days (range, 97 to 169 days; P<0.05 versus control) with 70 mg/kg. The development of cerebral edema was prevented, and systolic blood pressure and proteinuria were dose-dependently reduced. However, all rats in the 70-mg/kg treatment group developed hemorrhages in the basal ganglia shortly before death. Late-onset A127722 treatment failed to affect survival, systolic blood pressure, or proteinuria. Nevertheless, cerebral edema was reduced but not as well as in early-onset treatment. Development of hypertension, cerebral edema, and proteinuria was prevented in SHRSP when A127722 treatment was initiated at the start of salt-loading. However, A127722 treatment did not prolong survival in SHRSP with cerebral edema. This suggests that in SHRSP the endothelin A receptor participates actively in the development of increased blood pressure and initiation of organ damage but participates minimally in established malignant hypertension and progression of target-organ damage.

Fast Progression of Recombinant Human Myelin/Oligodendrocyte Glycoprotein (MOG)-Induced Experimental Autoimmune Encephalomyelitis in Marmosets Is Associated with the Activation of MOG34–56-Specific Cytotoxic T Cells

The recombinant human (rh) myelin/oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) model in the common marmoset is characterized by 100% disease incidence, a chronic disease course, and a variable time interval between immunization and neurological impairment. We investigated whether monkeys with fast and slow disease progression display different anti-MOG T or B cell responses and analyzed the underlying pathogenic mechanism(s). The results show that fast progressor monkeys display a significantly wider specificity diversification of anti-MOG T cells at necropsy than slow progressors, especially against MOG34–56 and MOG74–96. MOG34–56 emerged as a critical encephalitogenic peptide, inducing severe neurological disease and multiple lesions with inflammation, demyelination, and axonal injury in the CNS. Although EAE was not observed in MOG74–96-immunized monkeys, weak T cell responses against MOG34–56 and low grade CNS pathology were detected. When these cases received a booster immunization with MOG34–56 in IFA, full-blown EAE developed. MOG34–56-reactive T cells expressed CD3, CD4, or CD8 and CD56, but not CD16. Moreover, MOG34–56-specific T cell lines displayed specific cytotoxic activity against peptide-pulsed B cell lines. The phenotype and cytotoxic activity suggest that these cells are NK-CTL. These results support the concept that cytotoxic cells may play a role in the pathogenesis of multiple sclerosis.