Therapeutic innovations

Diagnosis and therapy of genetic and dysimmune peripheral neuropathies

PI: David Adams, Andoni Echaniz-Laguna (Team 2)

Development of targeted therapies for monogenic neuropathies by siRNA therapeutics

Targeted therapies for peripheral neuropathies

PI : Liliane Massade (Dir. Team 2)

Our research is focused on the use of nanomedecine based on small interfering RNA (siRNA) nanoparticles for the treatment of monogenic peripheral neuropathies. The strength of our team relies on complementary expertises in: 1) siRNA design, their characterization and optimization; 2) nanotechnologies, with the development of nanoparticle carriers for the delivery of siRNA and neuroactive molecules.

Recently, we investigated the regulation of a gene playing a key role in inherited demyelinating peripheral neuropathy by siRNA-squalene nanoparticles. The effect of these nanoparticles were tested in a mouse model, characterized by muscle weakness and atrophy and by slow nerve conduction velocity (European patent filed in September 2018). Importantly, we showed a normalization of the disease gene expression in this mouse model in addition of the reversal of the disease process and symptoms.

The figure below represents our projects for the next years. They consist of optimization of the treatment by siRNA-squalene nanoparticules and studying the mechanisms underlying the restoration of motor activity in the model of inherited demyelinating neuropathy. Our final aim is to reach clinical phases that will be done in the National reference center for Familial Amyloid Polyneuropathy and Other Rare Neuropathies, headed by Pr. David ADAMS.

This work is supported by a public grant overseen by the French National Research Agency (ANR) as part of the “Investissements d’Avenir” program (Labex NanoSaclay, reference: ANR-10-LABX-0035).

Therapy of  amyloid neuropathies

PI: David Adams, Andoni Echaniz-Laguna (Team 2)

Hereditary amyloidogenic transthyretin (ATTRv) amyloidosis with polyneuropathy (also known as familial amyloid polyneuropathy) is a condition with adult onset caused by mutation of transthyretin (TTR) and characterized by extracellular deposition of amyloid and destruction of the somatic and autonomic peripheral nervous system, leading to loss of autonomy and death.  The pathophysiology of the neuropathy includes instability and proteolysis of mutant TTR leading to deposition of amyloid with variable lengths of fibrils, microangiopathy and involvement of Schwann cells. Wild- type TTR is amyloidogenic in older individuals. The main symptoms are neuropathic, but the disease is systemic leading to cardiac, eye and kidney pathology.

Until recently, disease modifying therapeutics that have been developed include liver transplantation and TTR stabilizers,
both of which can slow progression of the disease and increase survival in the early stages.

D. Adams (head of the Neurology Department of the Bicêtre Hospital and member of Team 2) has developped the first-ever siRNA therapeutic for the treatment ATTRv, in collaboration with Alnylam Pharmaceuticals (Adams et al., 2018). The siRNA product Patisiran (Onpattro) has been approved by American Food and Drug Administration (FDA) and European Medicines Agency (EMA) for the treatment of hereditary transthyretin-mediated amyloidosis in adult patients after a successful Phase III trial.

Major problems faced by siRNA therapy are their rapid degradation and the difficulty to deliver the negatively charged nucleic acids to target cells. For Patisiran, the problems have been overcome by delivering the siRNA molecule in a lipid nanoparticle, able to cross the cell membranes. As transthyretin is mainly synthesized within the liver, where lipid nanoparticles naturally accumulate, the inhibition of transthyretin expression by siRNA has been successful. In a total of 148 Patisiran-treated patients compared to 77 placebo-treated patients, the almost 80% decrease in serum transthyretin levels significantly stabilized, and even improved neurological scores including gait over a 18 months period. Treatments were administered intravenously once every 3 weeks (Adams et al., 2018). Importantly, a longer-term safety and efficacy follow-up shows that patisiran maintains efficacy with an acceptable safety profile in patients with hereditary transthyretin-mediated amyloidosis (Adams et al., 2021).

Adams D et al. (2018) Patisiran, an RNAi therapeutic, for hereditary transthyretin amyloidosis. N Engl J Med 379:11-21 (https://doi.org/10.1056/NEJMoa1716153)

Mechanistic models of amyloid fibril formation and disease progression. a | Stability of transthyretin (TTR) homotetramers is reduced by TTR mutations, resulting in its dissociation into monomers and deposition in the extracellular spaces of systemic organs. The dissociation results in misfolding of TTR monomers and subsequent aggregation. These oligomers can be present before the completion of mature amyloid fibrils and can have toxic effects on neighbouring tissue. b | Disruption of the blood–nerve barrier (arrowhead; vessel lumen indicated by asterisk) can occur in the early phase of neuropathy , resulting in leakage of circulating TTR into the endoneurial space. Consequently, amorphous, electron- dense extracellular material that contains TTR monomers and oligomers becomes abundant in the extracellular spaces of the endoneurium. Aggregation of TTR is subsequently seen as dotty structures among amorphous materials. Finally , elongated fibrillar structures with a thickness similar to the diameter of the dotty structures are formed, leading to adjacent Schwann cell atrophy. (from Adams et al, Nat Rev Neurol, 2019)

Postnatal and prenatal gene transfer via AVV vectors

PIs : Pierre Bougnères, Catherine LeStunff (Team 1)

We use postnatal and prenatal AAV gene transfer to transduce brain and spinal cord oligodendrocytes in mouse disease models and in non human primates as preclinical models for the gene therapy of X-adrenoleukodystrophy, adrenomyeloneuropathy, Krabbe’s disease, and more generally demyelinating diseases or axonopathies. We also develop a program of AAV mediated gene therapy directed at mitofusin deficiency (Charcot-Marie Tooth 2). We design and build plasmids with specific CNS expressing promoters and use all techniques allowing gene expression to be quantified in these animal models.

Cerebroprotective effects of steroid hormons and of neurosteroids

PI : Michael Schumacher (Dir. Team 1)

Our teams share expertise in steroid neuroendocrinology and providing precise, sensitive and robust steroid profiling by gas chromatography-tandem mass spectrometry (GC-MS/MS). This expertise allow to use of steroids and other neuroactive signaling molecules to promote the regeneration of myelin. To improve the safety and efficacy of steroids for treating diseases and lesions of the nervous system, and for preferentially administering them to the brain and spinal cord, the intranasal delivery route is explored. The identication of the intracellular progesterone receptors as major players in actions of progesterone in neural cells has important therapeutic implications, opening the way for the use in neuroprotective and myelin repair strategies of synthetic progestins, developed for hormonal contraception and the treatment of endocrine disorders.

PI : Rachida Guennoun (Team 1)

The project aims to better understand
1) the role of neurosteroid synthesis in cerebroprotection after ischemic stroke;
2) the mechanisms by which steroids exert their cerebroprotective effects at the molecular and cellular level;
3) The optimization of intranasal administration of natural or synthetic steroids as a potential route of cerebroprotection in ischemic stroke.

We have a multidisplinary approach combining generation of mice with selective invalidation of steroid receptors or enzymes of steroidogenesis using the Cre/Lox strategy, surgery (experimental cerebral ischemia), behavioral tests to evaluate functional recovery (neurological deficits, motor coordination), histological analysis, gene and protein expression analysis (Transcriptomic analysis, RT-qPCR, Western blot, immunofluorescence, Confocal microscopy) and steroid measurement by Gas Chromatography-tandem mass spectrometry.

Thanks to the interaction between basic scientists and clinicians we aim to generate preclinical data for the development of a neuroprotective therapy based on treatment with natural or synthetic steroids or on stimulation of endogenous synthesis of neurosteroids in stroke patients of both sexes.

Other Therapies

Promoting peripheral nerve regeneration by combining microsurgery and neuroregenerative treatments

PI : Song Liu (Team 2)

A new surgical procedure for repairing the injured facial nerve with functional restoration has been developed using a rat model of facial nerve crush lesion. The method consists of hypoglossal–facial nerve ‘side’-to-side neurorrhaphy with a predegenerated nerve autograft for restoring functions after facial palsy. The method has then been successfully translated to the clinics and represents a major advance in the rehabilitation of facial nerve injury.

In preclinical studies, we test the usefulness of small molecules, in particular ligands of the tanslocator protein (TSPO), and of viral vectors delivering neurotrophic factors to promote the viability of sensory and motoneurons and the regeneration of axons after peripheral nerve injury.

Preclinical development of analgesic and anti-inflammatory molecules in pain models

PI : Dan Benhamou

The laboratory of anesthesia focus on preclinical development of analgesic and anti-inflammatory molecules such as Opiorphin (endogenous peptide inhibit NEP and APN) and Losmapimod (an inhibitor of p38 MAPK used as treatment of depression). We developed several murine models of neuropathic pain and showed that:
– Opiorphin as well as its stable derivate STR-324 have an analgesic effect and potentialize that of enkephalins.
– Losmapimod have analgesic and anti-inflammatory effects.

The future studies will consist to understand the mechanisms underlying these observations and to expend their studies on sever pains.

Morphology and regeneration of the autonomic nervous system

PI : Thomas Bessede

Functional sequelae after abdomino-pelvic oncologic surgery are mainly related to nerve damage in the peripheral autonomic system. Because of anatomical, physiological and functional particularities, specific studies are required to try to improve its intraoperative nerve preservation and its postoperative nerve regeneration.

A Computer-Assisted Anatomical Dissection model was elaborated and is used to identify peripheral autonomic nerve fibers. Utilizing specific immunolabelings, we create 3D morphologic cartographies that are augmented with functional data. It is possible to analyse surgical dissection planes to better preserve vegetative functions.

As a second model, the recovery of erectile function was assessed after cavernous nerve injury in rats. Various techniques to promote cavernous neuroregeneration were assessed : pharmacologic treatments, support with silicone guide, autologous support, combined strategies.
Morphological and experimental data converge towards the objective of reducing functional sequelae after lesions of the autonomic nervous system. With new experimental and imaging models, it is possible to overpass surgical applications and collaborate in Neuroscience.