Summary of the context and overall objectives of the project 

Amyotrophic lateral sclerosis (ALS) is a progressively paralyzing neurodegenerative disorder usually fatal within 3 years of diagnosis (Masrori and Van Damme, 2020). ALS affects both upper and lower motoneurons located in the motor cortex, brainstem and spinal cord. The incidence of ALS ranges between 2 to 3 per 100 000 person-years, with a median age of age comprised between 50 and 70 years (Longinetti and Fang, 2019). The majority of cases being diagnosed are considered sporadic, while approximately 10% of patients have a familial history of the disease (Mathis et al., 2019). ALS causing mutations in Cu-Zn superoxide dismutase (SOD1) were the first to be identified and are among the most frequently found in familial cases. Transgenic mice that express ALS-causing mutations in SOD1 recapitulate the main traits of the human disease and represent therefore a reliable and informative model to comprehend pathogenic mechanisms.

The vast majority of ALS research has legitimately approached this disorder as an adult condition. The concept that this disease can take root very early in the life of patients has received little consideration, while structural and fundamental sensorimotor functions are established during specific developmental window. Indeed, this critical period of spinal network organization being detrimental throughout the lifespan. Surprisingly, apprehending ALS as a developmental disease of sensorimotor network connectivity is a major conceptual step, both at the level of our vision to understand pathogenic mechanisms and especially at the therapeutic scale. Considering an early, infantile origin, sub-lethal aberrant network connectivity, escaping the vigilance of parents and clinicians, will provide new insight into ALS aetiology and open innovative therapeutic perspective.

This MSCA aims to identify alterations in early spontaneous sensory-evoked electrical activities in the spinal cord and motor reflexes of neonatal ALS animals to propose innovative therapeutic intervention.

 

References

Feather-Schussler, D.N., and Ferguson, T.S. (2016). A Battery of Motor Tests in a Neonatal Mouse Model of Cerebral Palsy. J Vis Exp.

Longinetti, E., and Fang, F. (2019). Epidemiology of amyotrophic lateral sclerosis: an update of recent literature. Curr Opin Neurol 32, 771-776.

Masrori, P., and Van Damme, P. (2020). Amyotrophic lateral sclerosis: a clinical review. Eur J Neurol.

Mathis, S., Goizet, C., Soulages, A., Vallat, J.M., and Masson, G.L. (2019). Genetics of amyotrophic lateral sclerosis: A review. J Neurol Sci 399, 217-226.

Roubertoux, P.L., Ghata, A., and Carlier, M. (2018). Measuring Preweaning Sensorial and Motor Development in the Mouse. Curr Protoc Mouse Biol 8, 54-78.

 

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The global health crisis posed by the Coronavirus disease COVID-19 pandemic has considerably slowed down the pace of the project. The mice model of the disease was initially supposed to arrive in mid-April 2020 in KFU lab, but could not arrive until the end of September 2020. In addition, border closure did not facilitate the supply of small equipment required for the project (silicone-based 16 electrode probes, dissection tools, wires).

Nevertheless, this period was fruitful in terms of exchanges and discussions with collaborators from different fields and allowed the writing of two reviews in peer-reviewed international journal (open Access)(Crabé et al., 2020; Layalle et al., 2021) and a book chapter (Scamps et al., 2021). These works have the dual affiliation of the laboratory of the Federal University of Kazan (KFU, outgoing phase) and the National Institute of Health and Medical Research (Inserm, incoming phase). All these publications acknowledged MSCA funding.

Following the lab lock-down, the first months were employed to learn about multielectrode extracellular recording, local field potential (LFP) and multiunit activity (MUA) recordings in vivo, repeating the original experiments performed in the neonatal rats (Inacio et al., 2016). For the first time to our knowledge, the first recordings of the spinal sensory-motor dynamics could be made in neonate mouse spinal cords. These LFP and MUA recordings are particularly challenging and are still being developed. The integrity of the spinal somatosensory network of mouse with ALS has been conducted by neonate reflex behavior (Feather-Schussler and Ferguson, 2016; Roubertoux et al., 2018).

Reference

Crabe, R., Aimond, F., Gosset, P., Scamps, F., and Raoul, C. (2020). How Degeneration of Cells Surrounding Motoneurons Contributes to Amyotrophic Lateral Sclerosis. Cells 9.

Feather-Schussler, D.N., and Ferguson, T.S. (2016). A Battery of Motor Tests in a Neonatal Mouse Model of Cerebral Palsy. J Vis Exp.

Inacio, A.R., Nasretdinov, A., Lebedeva, J., and Khazipov, R. (2016). Sensory feedback synchronizes motor and sensory neuronal networks in the neonatal rat spinal cord. Nature communications 7, 13060.

Layalle, S., They, L., Ourghani, S., Raoul, C., and Soustelle, L. (2021). Amyotrophic Lateral Sclerosis Genes in Drosophila melanogaster. Int J Mol Sci 22.

Roubertoux, P.L., Ghata, A., and Carlier, M. (2018). Measuring Preweaning Sensorial and Motor Development in the Mouse. Curr Protoc Mouse Biol 8, 54-78.

Scamps, F., Aimond, F., Hilaire, C., and Raoul, C. (2021). Synaptic Transmission and Motoneuron Excitability Defects in Amyotrophic Lateral Sclerosis. In Amyotrophic lateral sclerosis, E. Publications, ed. Submitted.

 

Progress beyond the state of the art, expected results until the end of the project and potential impacts

ADELE aims at exploring the spatiotemporal dynamics of spinal network activity during post-natal development of an ALS mouse model. We propose to combine complementary areas of expertise to answer a question that has never been functionally addressed before: is ALS a developmental disease that originates when spinal circuits are first established and remains silent before reaching a clinical breakthrough point? This conceptual paradigm shift requires a scientifically robust proof of concept in order to stimulate new examination protocols aimed to reveal early preclinical markers of the disease raising an alert towards early ALS diagnostics, to guide screening of genetic background in the cohort of patients with a risk of ALS development, and will open large time window for the new treatments preventing the disease. Strikingly, in humans, asymptomatic mutation carriers can exhibit electrophysiological abnormalities such as intracortical facilitation transmission deficits, which can be observed 30 years before the onset of symptoms (Chipika et al., 2020). In mice, during embryonic development (E17.5), motoneurons already exhibits depolarized GABAAR reversal potential, reduced glycinergic and GABAergic inhibitory post-synaptic currents (Branchereau et al., 2019). However, these defects are not clinically translated. Our results obtained by early reflex behavior indeed testify that at the macroscopic scale, defects of the neuronal circuitry are compensated and allow an adaptation of the animals to the environment. Currently, to our knowledge no laboratory has studied the sensory-motor activity in the spinal cord of SOD1 neonate mouse using a translaminar extracellular recording approach. This development, as we have experienced, is particularly challenging but still remains a major asset in our understanding of the disease. This interdisciplinary approach implicates electrophysiologists, neurobiologists, physicists and mathematicians to propose an innovative and potentially ground-breaking description of pathophysiological process underlying ALS pathogenesis. Project outcomes would enable detection at very early developmental stages in ALS mice, well before the emergence of clinical symptoms and support novel preventive and effective therapy. Indeed, our goal is to identify very early network defects in order to perform a targeted therapeutic intervention on a short developmental period and to evaluate the benefits in adults. Reconsidering ALS as a neurodevelopmental disease whose effective therapy consists in targeting the early stages remains an original approach that will surely raise many questions but will open new horizons.

References

Branchereau, P., Martin, E., Allain, A.E., Cazenave, W., Supiot, L., Hodeib, F., Laupenie, A., Dalvi, U., Zhu, H., and Cattaert, D. (2019). Relaxation of synaptic inhibitory events as a compensatory mechanism in fetal SOD spinal motor networks. Elife 8.

Chipika RH, Siah WF, McKenna MC, Li Hi Shing S, Hardiman O, Bede P. The presymptomatic phase of amyotrophic lateral sclerosis: are we merely scratching the surface? J Neurol. 2020.