Nikolaos Grigoriadis

Natalizumab treatment for multiple sclerosis: updated recommendations for patient selection and monitoring.

Natalizumab, a highly specific α4-integrin antagonist, is approved for treatment of patients with active relapsing-remitting multiple sclerosis (RRMS). It is generally recommended for individuals who have not responded to a currently available first-line disease-modifying therapy or who have very active disease. The expected benefits of natalizumab treatment have to be weighed against risks, especially the rare but serious adverse event of progressive multifocal leukoencephalopathy. In this Review, we revisit and update previous recommendations on natalizumab for treatment of patients with RRMS, based on additional long-term follow-up of clinical studies and post-marketing observations, including appropriate patient selection and management recommendations.

Neuroprotection and immunomodulation with mesenchymal stem cells in chronic experimental autoimmune encephalomyelitis.

OBJECTIVE To investigate the therapeutic potential of mesenchymal stromal cells (MSCs) in the chronic model of experimental autoimmune encephalomyelitis (EAE). DESIGN Mesenchymal stromal cells were obtained from the bone marrow of naïve C57BL and green fluorescent protein-transgenic mice and cultured with Eagle minimum essential medium/alpha medium after removal of adhering cells. Following 2 to 3 passages, MSCs were injected intraventricularly or intravenously into mice in which chronic EAE had been induced with myelin oligodendrocyte glycoprotein 35-55 peptide. RESULTS In 8 separate experiments, the intravenously and intraventricularly injected green fluorescent protein-positive MSCs were attracted to the areas of central nervous system inflammation and expressed galactocerebroside, O4, glial fibrillary acidic protein, and beta-tubulin type III. The clinical course of chronic EAE was ameliorated in MSC-treated animals (0% mortality; mean [SE] maximal EAE score, 1.76 [1.01] and 1.8 [0.46] in the intraventricular and intravenous groups, respectively, vs 13% and 21% mortality and 2.80 [0.79] and 3.42 [0.54] mean maximal score in the controls). A strong reduction in central nervous system inflammation, accompanied by significant protection of the axons (86%-95% intact axons vs 45% in the controls) was observed in the animals injected with MSCs (especially following intraventricular administration). Mesenchymal stromal cells injected intravenously were detected in the lymph nodes and exhibited systemic immunomodulatory effects, downregulating proliferation of lymphocytes in response to myelin antigens and mitogens. Mesenchymal stromal cells cultured with fibroblast growth factor and brain-derived neurotrophic factor in vitro acquired neuronal-lineage cell morphology and expressed beta-tubulin type III, nestin glial fibrillary acidic protein, and O4. CONCLUSIONS Our results indicate that stem cells derived from bone marrow may provide a feasible and practical way for neuroprotection, immunomodulation, and possibly remyelination and neuroregeneration in diseases such as multiple sclerosis.

Effects of proinflammatory cytokines on the growth, fate, and motility of multipotential neural precursor cells.

We have recently shown that the inflammatory process during experimental allergic encephalomyelitis (EAE), the animal model of MS, attracts transplanted NPC migration into the inflamed white matter. Here we studied how the proinflammatory cytokines tumor necrosis factor-alpha (TNFalpha) and interferon-gamma (IFNgamma) affect NPC growth, survival, differentiation, and migration. Newborn rat striatal NPCs were expanded in spheres as nestin+, PSA-NCAM+, NG2(-) cells, which differentiated into astrocytes, oligodendrocytes, and neurons. NPCs expressed receptors of TNFalpha and IFNgamma but not interleukin-1. TNFalpha and IFNgamma inhibited sphere cell proliferation, determined by [(3)H]thymidine and BrdU incorporation. IFNgamma increased apoptotic cell death (determined by TUNEL stains); this effect partially blocked by TNFalpha. Neither cytokine affected NPC lineage fate, determined by percentage of GFAP+, neurofilament+, and GalC+ cells after differentiation. TNFalpha and IFNgamma increased outward migration of cells from spheres in vitro. Thus, TNFalpha and IFNgamma, key players in MS and EAE, inhibit NPC proliferation and induce their migration.

Erythropoietin is neuroprotective, improves functional recovery, and reduces neuronal apoptosis and inflammation in a rodent model of experimental closed head injury

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality in young people in industrialized countries. Although various anti‐inflammatory and antiapoptotic modalities have shown neuroprotective effects in experimental models of TBI, to date, no specific pharmacological agent aimed at blocking the progression of secondary brain damage has been approved for clinical use. Erythropoietin (Epo) belongs to the cytokine superfamily and has traditionally been viewed as a hematopoiesis‐regulating hormone. The newly discovered neuroprotective properties of Epo lead us to investigate its effect in TBI in a mouse model of closed head injury. Recombinant human erythropoietin (rhEpo) was injected at 1 and 24 h after TBI, and the effect on recovery of motor and cognitive functions, tissue inflammation, axonal degeneration, and apoptosis was evaluated up to 14 days. Motor deficits were lower, cognitive function was restored faster, and less apoptotic neurons and caspase‐3 expression were found in rhEpo‐treated as compared with vehicle‐treated animals (P<0.05). Axons at the trauma area in rhEpo‐treated mice were relatively well preserved compared with controls (shown by their density; P<0.01). Immunohistochemical analysis revealed a reduced activation of glial cells by staining for GFAP and complement receptor type 3 (CD11b/CD18) in the injured hemisphere of Epo‐ vs. vehicle‐treated animals. We propose that further studies on Epo in TBI should be conducted in order to consider it as a novel therapy for TBI.

Intraventricular transplantation of neural precursor cell spheres attenuates acute experimental allergic encephalomyelitis

Brain transplantation of neural precursor cells (NPCs) has been proposed to enhance CNS regeneration. As the pathogenesis of most acute CNS diseases involves an inflammatory component, we studied whether NPC transplantation affects brain inflammation. Newborn rat multipotential NPCs were transplanted intraventriculary into acute experimental allergic encephalomyelitis (EAE) rats, a model for disseminated brain inflammation. Cells migrated into inflamed white matter and differentiated into glial cells. NPC transplantation attenuated the clinical severity of EAE and the brain inflammation, indicated by reduction in perivascular infiltrates and decreased expression of ICAM-1 and LFA-1. NPCs inhibited basal proliferation and proliferative responses to Concavalin-A and to MOG peptide of EAE rat-derived lymphocytes in vitro. Purified astrocytes inhibited lymphocyte proliferation in vitro, but did not migrate into EAE brains in vivo, and did not reduce EAE severity or brain inflammation. Thus, transplanted NPCs attenuate acute EAE via an anti-inflammatory mechanism which depends on cell ability to migrate into inflamed brain tissue.

Transplanted neural precursor cells reduce brain inflammation to attenuate chronic experimental autoimmune encephalomyelitis.

Stem cell transplantation was introduced as a mean of cell replacement therapy, but the mechanism by which it confers clinical improvement in experimental models of neurological diseases is not clear. Here, we transplanted neural precursor cells (NPCs) into the ventricles of mice at day 6 after induction of chronic experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis (MS). Transplanted cells migrated into white matter tracts and attenuated the clinical course of disease. NPC transplantation down-regulated the inflammatory brain process at the acute phase of disease, as indicated by a reduction in the number of perivascular infiltrates and of brain CD3+ T cells, an increase in the number and proportion of regulatory T cells and a reduction in the expression of ICAM-1 and LFA-1 in the brain. Demyelination and acute axonal injury in this model are considered to result mainly from the acute inflammatory process and correlate well with the chronic neurological residua. In consequence to inhibition of brain inflammation, precursor cell transplantation attenuated the primary demyelinating process and reduced the acute axonal injury. As a result, the size of demyelinated areas and extent of chronic axonal pathology were reduced in the transplanted brains. We suggest that the beneficial effect of transplanted NPCs in chronic EAE is mediated, in part, by decreasing brain inflammation and reducing tissue injury.

Clinical Relevance of Brain Volume Measures in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic disease with an inflammatory and neurodegenerative pathology. Axonal loss and neurodegeneration occurs early in the disease course and may lead to irreversible neurological impairment. Changes in brain volume, observed from the earliest stage of MS and proceeding throughout the disease course, may be an accurate measure of neurodegeneration and tissue damage. There are a number of magnetic resonance imaging-based methods for determining global or regional brain volume, including cross-sectional (e.g. brain parenchymal fraction) and longitudinal techniques (e.g. SIENA [Structural Image Evaluation using Normalization of Atrophy]). Although these methods are sensitive and reproducible, caution must be exercised when interpreting brain volume data, as numerous factors (e.g. pseudoatrophy) may have a confounding effect on measurements, especially in a disease with complex pathological substrates such as MS. Brain volume loss has been correlated with disability progression and cognitive impairment in MS, with the loss of grey matter volume more closely correlated with clinical measures than loss of white matter volume. Preventing brain volume loss may therefore have important clinical implications affecting treatment decisions, with several clinical trials now demonstrating an effect of disease-modifying treatments (DMTs) on reducing brain volume loss. In clinical practice, it may therefore be important to consider the potential impact of a therapy on reducing the rate of brain volume loss. This article reviews the measurement of brain volume in clinical trials and practice, the effect of DMTs on brain volume change across trials and the clinical relevance of brain volume loss in MS.

Efficacy and safety of immunization with phosphorylated tau against neurofibrillary tangles in mice

As an abnormally folded and aggregated protein, tau composed of neurofibrillary tangles (NFTs) in Alzheimers disease and other tauopathies seems to be a candidate for immunotherapy. Yet, the encephalitogenicity of full-length tau protein, recently reported by us in immunized mice, demands to carefully and selectively target pathological tau and address both efficacy (anti-NFT effect) and safety (free of encephalitis). We immunized NFT mice with NFT-related phosphorylated (phos) tau peptides, using an immunization protocol aimed to predispose a proinflammatory milieu in CNS as a set up to detect biohazard, an approach we used when the neurotoxicity of full-length tau was detected [use of complete Freund adjuvant (CFA) with pertussis toxin (PT)]. A decrease of about 40% in NFT burden in CNS was demonstrated and was accompanied with an increase in microglial burden. Anti-phos-tau antibodies were detected in serum and blood vessels in the CNS, while no encephalitogenicity (free of clinical neurological deficits, of adverse effects on brain inflammatory cells and of axonal damage) was recorded. The level of the lysosomal proteases, cathepsins D and L, was affected in the immunized mice suggesting the possible involvement of the lysosomal system in the decrease of NFTs. The robust anti-NFT effect and the lack of encephalitogenicity in NFT mice immunized with phos-tau peptides, even though CFA with PT was included in vaccine, point to their anti-NFT therapeutic potential.

Activity-Dependent Neuroprotective Protein Snippet NAP Reduces Tau Hyperphosphorylation and Enhances Learning in a Novel Transgenic Mouse Model

Activity-dependent neuroprotective protein (ADNP) differentially interacts with chromatin to regulate essential genes. Because complete ADNP deficiency is embryonic lethal, the outcome of partial ADNP deficiency was examined. ADNP+/– mice exhibited cognitive deficits, significant increases in phosphorylated tau, tangle-like structures, and neurodegeneration compared with ADNP+/+ mice. Increased tau hyperphosphorylation is known to cause memory impairments in neurodegenerative diseases associated with tauopathies, including the most prevalent Alzheimers disease. The current results suggest that ADNP is an essential protein for brain function and plays a role in normal cognitive performance. ADNP-deficient mice offer an ideal paradigm for evaluation of cognitive enhancers. NAP (NAPVSIPQ) is a peptide derived from ADNP that interacts with microtubules and provides potent neuroprotection. NAP treatment partially ameliorated cognitive deficits and reduced tau hyperphosphorylation in the ADNP+/– mice. NAP is currently in phase II clinical trials assessing effects on mild cognitive impairment.

Multiple sclerosis deep grey matter: the relation between demyelination, neurodegeneration, inflammation and iron

In multiple sclerosis (MS), diffuse degenerative processes in the deep grey matter have been associated with clinical disabilities. We performed a systematic study in MS deep grey matter with a focus on the incidence and topographical distribution of lesions in relation to white matter and cortex in a total sample of 75 MS autopsy patients and 12 controls. In addition, detailed analyses of inflammation, acute axonal injury, iron deposition and oxidative stress were performed. MS deep grey matter was affected by two different processes: the formation of focal demyelinating lesions and diffuse neurodegeneration. Deep grey matter demyelination was most prominent in the caudate nucleus and hypothalamus and could already be seen in early MS stages. Lesions developed on the background of inflammation. Deep grey matter inflammation was intermediate between low inflammatory cortical lesions and active white matter lesions. Demyelination and neurodegeneration were associated with oxidative injury. Iron was stored primarily within oligodendrocytes and myelin fibres and released upon demyelination. In addition to focal demyelinated plaques, the MS deep grey matter also showed diffuse and global neurodegeneration. This was reflected by a global reduction of neuronal density, the presence of acutely injured axons, and the accumulation of oxidised phospholipids and DNA in neurons, oligodendrocytes and axons. Neurodegeneration was associated with T cell infiltration, expression of inducible nitric oxide synthase in microglia and profound accumulation of iron. Thus, both focal lesions as well as diffuse neurodegeneration in the deep grey matter appeared to contribute to the neurological disabilities of MS patients.