La lateralisation cerebrale et les relations cerveau-immunite. Approches lesionnelle et comportementale

SIGLEINIST T 76448 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

NF-L in cerebrospinal fluid and serum is a biomarker of neuronal damage in an inducible mouse model of neurodegeneration

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A Nurr1 Agonist Causes Neuroprotection in a Parkinson’s Disease Lesion Model Primed with the Toll-Like Receptor 3 dsRNA Inflammatory Stimulant Poly(I:C)

Dopaminergic neurons in the substantia nigra pars compacta (SNpc) are characterized by the expression of genes required for dopamine synthesis, handling and reuptake and the expression of these genes is largely controlled by nuclear receptor related 1 (Nurr1). Nurr1 is also expressed in astrocytes and microglia where it functions to mitigate the release of proinflammatory cytokines and neurotoxic factors. Given that Parkinson’s disease (PD) pathogenesis has been linked to both loss of Nurr1 expression in the SNpc and inflammation, increasing levels of Nurr1 maybe a promising therapeutic strategy. In this study a novel Nurr1 agonist, SA00025, was tested for both its efficiency to induce the transcription of dopaminergic target genes in vivo and prevent dopaminergic neuron degeneration in an inflammation exacerbated 6-OHDA-lesion model of PD. SA00025 (30mg/kg p.o.) entered the brain and modulated the expression of the dopaminergic phenotype genes TH, VMAT, DAT, AADC and the GDNF receptor gene c-Ret in the SN of naive rats. Daily gavage treatment with SA00025 (30mg/kg) for 32 days also induced partial neuroprotection of dopaminergic neurons and fibers in rats administered a priming injection of polyinosinic-polycytidylic acid (poly(I:C) and subsequent injection of 6-OHDA. The neuroprotective effects of SA00025 in this dopamine neuron degeneration model were associated with changes in microglial morphology indicative of a resting state and a decrease in microglial specific IBA-1 staining intensity in the SNpc. Astrocyte specific GFAP staining intensity and IL-6 levels were also reduced. We conclude that Nurr1 agonist treatment causes neuroprotective and anti-inflammatory effects in an inflammation exacerbated 6-OHDA lesion model of PD

Gene delivery of a modified antibody to Aβ reduces progression of murine Alzheimer's disease.

Antibody therapies for Alzheimer's Disease (AD) hold promise but have been limited by the inability of these proteins to migrate efficiently across the blood brain barrier (BBB). Central nervous system (CNS) gene transfer by vectors like adeno-associated virus (AAV) overcome this barrier by allowing the bodies' own cells to produce the therapeutic protein, but previous studies using this method to target amyloid-β have shown success only with truncated single chain antibodies (Abs) lacking an Fc domain. The Fc region mediates effector function and enhances antigen clearance from the brain by neonatal Fc receptor (FcRn)-mediated reverse transcytosis and is therefore desirable to include for such treatments. Here, we show that single chain Abs fused to an Fc domain retaining FcRn binding, but lacking Fc gamma receptor (FcγR) binding, termed a silent scFv-IgG, can be expressed and released into the CNS following gene transfer with AAV. While expression of canonical IgG in the brain led to signs of neurotoxicity, this modified Ab was efficiently secreted from neuronal cells and retained target specificity. Steady state levels in the brain exceeded peak levels obtained by intravenous injection of IgG. AAV-mediated expression of this scFv-IgG reduced cortical and hippocampal plaque load in a transgenic mouse model of progressive β-amyloid plaque accumulation. These findings suggest that CNS gene delivery of a silent anti-Aβ scFv-IgG was well-tolerated, durably expressed and functional in a relevant disease model, demonstrating the potential of this modality for the treatment of Alzheimer's disease

SA00025 entered the brain and modulated the transcription of dopaminergic target genes.

<p>The chemical structure of SA00025: 2-{3-[2-(4-chlorophenyl)imidazo[1,2-a]-pyridin-6-yl]phenyl}propan-2-ol (A). The Nurr1 agonist compound was administered once daily for 7 consecutive days (30mg/kg/ day) in naive rats by oral gavage (B). The compound was observed in the brain at 1 hour after the last gavage and reached a maximum concentration at 4 hrs post-gavage treatment (C). High levels of the compound were still observed in the brains of rats at 24 hrs and returned to baseline at 48 hrs (C). SA00025 caused a transcriptional upregulation of Nurr1, TH and VMAT at 1-hour post daily gavage and a transcriptional downregulation of VMAT, DAT and c-RET at 4 hours post-gavage treatment (D). A normalization of Nurr1, TH and VMAT expression was observed at 4–48 hours post-gavage treatment (D). Transcription of all dopaminergic target genes was equivalent between compound and vehicle treated rats at 48 hours post-gavage treatment (D). TH protein levels were elevated at 4 hours post-gavage treatment (E). Significance is annotated as p<0.05* & p<0.001*** compared vehicle treatment (dashed lines), unpaired <i>T</i>-tests and ANOVA. N = 4–8/ group. Graphs are expressed as mean ± SEM.</p

SA00025 caused neuroprotection in the 6-OHDA lesion model primed with dsRNA inflammatory stimulant (poly(I:C)).

<p>Rats received an initial unilateral injection of poly(I:C) in the SN (Start—day 0) and a subsequent unilateral injection of 6-OHDA in the striatum (day 12) (A). Rats were also administered daily with the Nurr1 agonist (30mg/kg/ day) or vehicle treatment throughout the paradigm (day 1–32) and were sacrificed at day 33 (A). 24 hrs following the last gavage treatment levels of the compound were significantly elevated in brain homogenates and was absent in vehicle treated conditions (B). Representative photomicrographs indicate the Nurr1 agonist caused a protective affect on TH +ve (brown) and NeuN +ve (grey) neurons within the SNpc and TH +ve fibers in the striatum (C). Rats had a significant sparing of dopaminergic neurons in the SNpc after 32 days of treatment with the compound, compared to vehicle treatment (D). Dopamine neuron fibers in the rostral striatum were also significantly spared with Nurr1 agonist treatment compared to vehicle treatment (E). Significance is annotated as p<0.05*, unpaired <i>T</i>-tests. N = 6–8/ group. Graphs are expressed at mean ± SEM. Abbreviations: dorsal lateral striatum (DL Stri) & medial striatum (M Stri). Scale bars = 200μm. TH and NeuN +ve neurons are indicated by black arrow heads and NeuN +ve neurons are indicated by grey arrows.</p

Cytokine and Chemokine protein levels in the SNpc following Nurr1 agonist treatment.

<p>^a Cytokines and chemokine levels in the SN (pg/mg), analyzed by multiplex ELISA</p><p>^b Data is represented as mean ± SEM and significance is annotated as *p<0.05</p><p>Cytokine and Chemokine protein levels in the SNpc following Nurr1 agonist treatment.</p

SA00025 induced anti-inflammatory activity in the 6-OHDA lesion model primed with dsRNA inflammatory stimulant (poly(I:C)).

<p>There was a significant increase in the amount IBA-1 +ve microglia in the SNpc scored as rating 1 (ramified and resting) and a significant decrease in microglia scored at rating 3 (bushy and reactive) with 32 days of Nurr1 agonist treatment, compared to vehicle (A). Representative photomicrographs show that Nurr1 agonist treatment caused a reduction in IBA-1 +ve microglia that were bushy and reactive and an increase in IBA-1 +ve microglia that were ramified and resting in the SNpc (B). Representative photomicrographs show that Nurr1 agonist treatment also caused a reduction in the immunofluorescent intensity of IBA-1 +ve microglia (green) and GFAP +ve astrocytes (C). Optical density analysis indicated that Nurr1 agonist treatment caused a significant decrease in IBA-1 (D) and GFAP (E) staining in the SNpc, compared to vehicle conditions. Significance is annotated as p<0.05*, 2- way ANOVA. N = 6–8/ group. Graphs are expressed at mean ± SEM. Scale bars = 100μm.</p

SAR228810: an antibody for protofibrillar amyloid β peptide designed to reduce the risk of amyloid-related imaging abnormalities (ARIA)

Abstract Background Anti-amyloid β (Aβ) immunotherapy represents a major area of drug development for Alzheimer’s disease (AD). However, Aβ peptide adopts multiple conformations and the pathological forms to be specifically targeted have not been identified. Aβ immunotherapy-related vasogenic edema has also been severely dose limiting for antibodies with effector functions binding vascular amyloid such as bapineuzumab. These two factors might have contributed to the limited efficacy demonstrated so far in clinical studies. Methods To address these limitations, we have engineered SAR228810, a humanized monoclonal antibody (mAb) with limited Fc effector functions that binds specifically to soluble protofibrillar and fibrillar forms of Aβ peptide and we tested it together with its murine precursor SAR255952 in vitro and in vivo. Results Unlike gantenerumab and BAN2401, SAR228810 and SAR255952 do not bind to Aβ monomers, low molecular weight Aβ oligomers or, in human brain sections, to Aβ diffuse deposits which are not specific of AD pathology. Both antibodies prevent Aβ42 oligomer neurotoxicity in primary neuronal cultures. In vivo, SAR255952, a mouse aglycosylated IgG1, dose-dependently prevented brain amyloid plaque formation and plaque-related inflammation with a minimal active dose of 3 mg/kg/week by the intraperitoneal route. No increase in plasma Aβ levels was observed with SAR255952 treatment, in line with its lack of affinity for monomeric Aβ. The effects of SAR255952 translated into synaptic functional improvement in ex-vivo hippocampal slices. Brain penetration and decoration of cerebral amyloid plaques was documented in live animals and postmortem. SAR255952 (up to 50 mg/kg/week intravenously) did not increase brain microhemorrhages and/or microscopic changes in meningeal and cerebral arteries in old APPSL mice while 3D6, the murine version of bapineuzumab, did. In immunotolerized mice, the clinical candidate SAR228810 demonstrated the same level of efficacy as the murine SAR255952. Conclusion Based on the improved efficacy/safety profile in non-clinical models of SAR228810, a first-in-man single and multiple dose administration clinical study has been initiated in AD patients