Athanasios Lourbopoulos

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.

Variable behavior and complications of autologous bone marrow mesenchymal stem cells transplanted in experimental autoimmune encephalomyelitis

Autologous bone marrow stromal cells (BMSCs) offer significant practical advantages for potential clinical applications in multiple sclerosis (MS). Based on recent experimental data, a number of clinical trials have been designed for the intravenous (IV) and/or intrathecal (ITH) administration of BMSCs in MS patients. Delivery of BMSCs in the cerebrospinal fluid via intracerebroventricular (ICV) transplantation is a useful tool to identify mechanisms underlying the migration and function of these cells. In the current study, BMSCs were ICV administered in severe and mild EAE, as well as naive animals; neural precursor cells (NPCs) served as cellular controls. Our data indicated that ICV-transplanted BMSCs significantly ameliorated mild though not severe EAE. Moreover, BMSCs exerted significant anti-inflammatory effect on spinal cord with concomitant reduced axonopathy only in the mild EAE model. BMSCs migrated into the brain parenchyma and, depending on their cellular density, within brain parenchyma formed cellular masses characterized by focal inflammation, demyelination, axonal loss and increased collagen-fibronectin deposition. These masses were present in 64% of ICV BMASC-transplanted severe EAE animals whereas neither BMSCs transplanted in mild EAE cases nor the NPCs exhibited similar behavior. BMSCs possibly exerted their fibrogenic effect via both paracrine and autocrine manner, at least partly due to up-regulation of connective tissue growth factor (CTGF) under the trigger of TGFb1. Our findings are of substantial relevance for clinical trials in MS, particularly regarding the possibility that ICV transplanted BMSCs entering the inflamed central nervous system may exhibit - under conditions - a local pathology of yet unknown consequences.

Histone deacetylase inhibitor ITF2357 is neuroprotective, improves functional recovery, and induces glial apoptosis following experimental traumatic brain injury

Despite efforts aimed at developing novel therapeutics for traumatic brain injury (TBI), no specific pharmacological agent is currently clinically available. Here, we show that the pan‐histone deacety‐ lase (HDAC) inhibitor ITF2357, a compound shown to be safe and effective in humans, improves functional recovery and attenuates tissue damage when adminis‐ tered as late as 24 h postinjury. Using a well‐character‐ ized, clinically relevant mouse model of closed head injury (CHI), we demonstrate that a single dose of ITF2357 administered 24 h postinjury improves neu‐ robehavioral recovery from d 6 up to 14 d postinjury (improved neurological score vs. vehicle; P<0.05), and that this functional benefit is accompanied by de‐ creased neuronal degeneration, reduced lesion volume (22% reduction vs. vehicle; P<0.01), and is preceded by increased acetylated histone H3 levels and attenuation of injury‐induced decreases in cytoprotective heat‐ shock protein 70 kDa and phosphorylated Akt. More‐ over, reduced glial accumulation and activation were observed 3 d postinjury, and total p53 levels at the area of injury and caspase‐3 immunoreactivity within microglia/macrophages at the trauma area were ele‐ vated, suggesting enhanced clearance of these cells via apoptosis following treatment. Hence, our find‐ ings underscore the relevance of HDAC inhibitors for ameliorating trauma‐induced functional deficits and warrant consideration of applying ITF2357 for this indication.—Shein, N. A., Grigoriadis, N., Alex‐ androvich, A. G., Simeonidou, C., Lourbopoulos, A., Polyzoidou, E., Trembovler, V., Mascagni, P., Din‐ arello, C. A., Shohami, E. Histone deacetylase inhib‐ itor ITF2357 is neuroprotective, improves functional recovery, and induces glial apoptosis following ex‐ perimental traumatic brain injury. FASEB J. 23, 4266‐4275 (2009). www.fasebj.org

Administration of 2-arachidonoylglycerol ameliorates both acute and chronic experimental autoimmune encephalomyelitis.

BACKGROUND AND PURPOSE Experimental autoimmune encephalomyelitis (EAE) is a widely used model of multiple sclerosis (MS) and both conditions have been reported to exhibit reduced endocannabinoid activity. The purpose of this study was to address the effect of exogenously administered 2-arachidonoylglycerol (2AG), an endocannabinoid receptor ligand, on acute phase and chronic disability in EAE. EXPERIMENTAL APPROACH Acute and chronic EAE models were induced in susceptible mice and 2AG-treatment was applied for 14 days from day of disease induction. KEY RESULTS 2AG-treatment ameliorated acute phase of disease with delay of disease onset in both EAE models and reduced disease mortality and long-term (70 days post-induction) clinical disability in chronic EAE. Reduced axonal pathology in the chronic EAE- (p<0.0001) and increased activation and ramification of microglia in the 2AG-treated acute EAE- (p<0.05) model were noticed. The latter was accompanied by a 2- to 4-fold increase of the M2-macrophages in the perivascular infiltrations (p<0.001) of the 2AG-treated animals in the acute (day 22), although not the chronic (day 70), EAE model. Expression of cannabinoid receptors 1 (CB1R) and 2 (CB2R) was increased in 2AG-treated animals of acute EAE vs. controls (p<0.05). In addition, ex vivo viability assays exhibited reduced proliferation of activated lymph node cells when extracted from 2AG-treated EAE animals, whereas a dose-dependent response of activated lymphocytes to 2AG-treatment in vitro was noticed. CONCLUSION AND IMPLICATIONS Our data indicate for the first time that 2AG treatment may provide direct (via CBRs) and immune (via M2 macrophages) mediated neuroprotection in EAE.

Amelioration of autoimmune neuroinflammation by recombinant human alpha-fetoprotein.

Alpha-fetoprotein (AFP) is a 65-kDa oncofetal glycoprotein found in fetal and maternal fluids during pregnancy. Clinical remissions during pregnancy have been observed in several autoimmune diseases, such as multiple sclerosis (MS), and have been attributed to the presence of pregnancy-associated natural immune-reactive substances, including AFP which can exert immunomodulatory effects on immune cells. In this study, we tested the effect of recombinant human AFP (rhAFP) isolated from transgenic goats, which contain the genomic DNA for hAFP, on experimental autoimmune encephalomyelitis (EAE), the animal model used for the study of MS. RhAFP treatment markedly improved the clinical manifestations of EAE, preventing central nervous system (CNS) inflammation and axonal degeneration. RhAFP exerted a broad immunomodulating activity, influencing the various populations of immune cells. T cells from treated mice had significantly reduced activity towards the encephalitogenic peptide of myelin oligodendrocyte glycoprotein (MOG), exhibiting less proliferation and reduced Th1 cytokine secretion. Moreover, AFP affected the humoral response, causing an inhibition in MOG-specific antibody production. The expression of CD11b, MHC class II and the chemokine receptor CCR5 was also down-regulated. This is the first study demonstrating reduced inflammation and axonal damage exerted by recombinant AFP. In light of our findings, rhAFP may serve as a potential candidate for treatment of MS and other autoimmune diseases.

Repeated immunization of mice with phosphorylated-tau peptides causes neuroinflammation ☆

The recent studies of others and of us showing robust efficacy of anti-tangle immunotherapy, directed against phosphorylated (phos)-tau protein, may pave the way to clinical trials of phos-tau immunotherapy in Alzheimers-disease and other tauopathies. At this stage addressing the safety of the phos-tau-immunotherapy is highly needed, particularly since we have previously shown the neurotoxic potential of tau-immunotherapy, specifically of full-length unphosphorylated-tau vaccine under a CNS-proinflammatory milieu [induced by emulsification in complete-Freunds-adjuvant (CFA) and pertussis-toxin (PT)] in young wild-type (WT)-mice. The aim of our current study was to address safety aspects of the phos-tau-immunotherapy in both neurofibrillary-tangle (NFT)-mice as well as in WT-mice, under challenging conditions of repeated immunizations with phos-tau peptides under a CNS-proinflammatory milieu. NFT- and WT-mice were repeatedly immunized (7 injections in adult-, 4 in aged-mice) with phos-tau peptides emulsified in CFA-PT. A paralytic disease was evident in the phos-tau-immunized adult NFT-mice, developing progressively to 26.7% with the number of injections. Interestingly, the WT-mice were even more prone to develop neuroinflammation following phos-tau immunization, affecting 75% of the immunized mice. Aged mice were less prone to neuroinflammatory manifestations. Anti-phos-tau antibodies, detected in the serum of immunized mice, partially correlated with the neuroinflammation in WT-mice. This points that repeated phos-tau immunizations in the frame of a proinflammatory milieu may be encephalitogenic to tangle-mice, and more robustly to WT-mice, indicating that - under certain conditions - the safety of phos-tau immunotherapy is questionable.

Effectiveness of a new modified intraluminal suture for temporary middle cerebral artery occlusion in rats of various weight.

Intraluminal temporary middle cerebral artery occlusion (MCAO) is a common model of ischemic stroke in the rat with significant, suture and weight-dependent variability along with increased risk of subarachnoid haemorrhage (SAH). Our purpose was to increase reproducibility and decrease SAH using a modification of the Koizumi suture. We compared a Koizumi 5/0 Ethilon poly-l-lysine-coated suture (s-2, group B) to an identical, uncoated one (s-1, group A) and the Belayevs 3/0 suture (s-3, group C), in the 2-h MCAO model in Wistar rats of varying weight (310-527 g). Assessment included successful infarction rates, the modified neurological stroke scale (mNSS), a modified Bedersons scale (mBS), the grid-walking test (GWT), infarction volume (with rostrocaudal subanalysis and analysis of cortical/striatal involvement) and hemispheric edema. The s-2 suture increased the successful MCAO from 61.1% and 66.6% (groups A and C) to 97.5% in group B and induced a more severe clinical stroke (P<0.05) irrespective of animals weight, with no incidence of SAH. Infarction volume and ipsilateral hemispheric edema significantly (P<0.05) increased and well correlated with the mNSS (P<or=0.005), the mBS (P<or=0.01) and GWT outcomes. Our data suggest that the new modified suture induces a more reproducible ischemic stroke in Wistar rats for temporary-MCAO experiments, overcoming the variability of weight and the risk of SAH.

Altered peptide ligands of myelin basic protein ( MBP87-99 ) conjugated to reduced mannan modulate immune responses in mice.

Mutations of peptides to generate altered peptide ligands, capable of switching immune responses from T helper 1 (Th1) to T helper 2 (Th2), are promising candidates for the immunotherapy of autoimmune diseases such as multiple sclerosis (MS). We synthesized two mutant peptides from myelin basic protein 87–99 (MBP87–99), an immunodominant peptide epitope identified in MS. Mutations of residues K91 and P96, known to be critical T‐cell receptor (TCR) contact sites, resulted in the mutant peptides [R91, A96]MBP87–99 and [A91, A96]MBP87–99. Immunization of mice with these altered peptide ligands emulsified in complete Freund’s adjuvant induced both interferon‐γ (IFN‐γ) and interleukin‐4 (IL‐4) responses compared with only IFN‐γ responses induced to the native MBP87–99 peptide. It was of interest that [R91, A96]MBP87–99 conjugated to reduced mannan induced 70% less IFN‐γ compared with the native MBP87–99 peptide. However, [A91, A96]MBP87–99 conjugated to reduced mannan did not induce IFN‐γ‐secreting T cells, but elicited very high levels of interleukin‐4 (IL‐4). Furthermore, antibodies generated to [A91, A96]MBP87–99 peptide conjugated to reduced mannan did not cross‐react with the native MBP87–99 peptide. By molecular modelling of the mutant peptides in complex with major histocompatibility complex (MHC) class II, I‐As, novel interactions were noted. It is clear that the double‐mutant peptide analogue [A91, A96]MBP87–99 conjugated to reduced mannan is able to divert immune responses from Th1 to Th2 and is a promising mutant peptide analogue for use in studies investigating potential treatments for MS.

Time Course and Spatial Profile of Nogo-A Expression in Experimental Autoimmune Encephalomyelitis in C57BL/6 Mice

Abstract Inhibition of the myelin-associated neurite outgrowth inhibitor Nogo-A has been found to be beneficial in experimental autoimmune encephalomyelitis (EAE), but there are little data on its expression dynamics during the disease course. We analyzed Nogo-A mRNA and protein during the course of EAE in 27 C57BL/6 mice and in 8 controls. Histopathologic and molecular analyses were performed on Day 0 (naive), preclinical (Day 10), acute (Days 18–22) and chronic (Day 50) time points. In situ hybridization and real-time polymerase chain reaction analyses revealed reduced Nogo-A mRNA expression at preclinical (p < 0.0001) and acute phases (p < 0.0001), followed by upregulation during the chronic phase (p < 0.0001). Nogo-A mRNA was expressed in neurons and oligodendrocytes. By immunohistochemistry and Western blot, there was increased Nogo-A protein expression (p < 0.001) in the chronic phase. Moreover, spatial differences were observed within EAE lesions. The pattern of Nogo-A protein expression inversely correlated with axonal regeneration growth-associated protein 43–positive axons (60% of which were Nogo-A contact–free during the acute phase) and axonal injury (&bgr;-amyloid precursor protein–positive axons). Cortical Nogo-66 receptor protein and mRNA levels increased during the chronic phase. The results indicate that Nogo-A and Nogo receptor are actively regulated in EAE lesions; this may indicate a specific time window for localized axonal regeneration in the acute phase of EAE.

Moderate Environmental Enrichment Mitigates Tauopathy in a Neurofibrillary Tangle Mouse Model

Epidemiological studies show that stimulating activities reduce therisk of dementia. In animal models of Alzheimer disease, there have been conflicting results of the effects of environmental enrichment (EE) on disease-related amyloid pathology. Here, we tested the direct effect of EE, independently of amyloid pathology, on brain neurofibrillary tangles (NFTs), which best correlate with dementia. We exposed transgenic mice (E257K/P301S-Tau-Tg driven by the natural tau promoter) to moderate nonstrained EE or regular environment. Concomitant with neurogenesis, we detected a decrease in NFT burden and a decrease in the activation of microglia in EE versus regular-environment mice. There was also a trend toward improvementin cognitive tasks in the EE mice. Increased immunoreactivity of brain-derived neurotrophic factor, which is involved in the regulation of tau phosphorylation, was detected in the EE mice, suggesting its possible involvement in the beneficial effects on NFTs and other parameters in the EE mice. These results suggest that NFTs may be directly responsive to environmental stimulating activities and that even nonstrained activities may mitigate tauopathies independent of theinvolvement of amyloid.