A Fab fragment directed against the neural cell adhesion molecule L1 enhances functional recovery after injury of the adult mouse spinal cord

Abstract

Lack of permissive mechanisms and abundance of inhibitory molecules in the lesioned central nervous system of adult mammals contribute to the failure of functional recovery, which leads to severe disabilities in motor functions or pain. Previous studies have indicated that the neural cell adhesion molecule L1 constitutes a viable target to promote regeneration. In the present study, we describe the cloning, functional expression in Escherichia coli cells and purification of a recombinant αL1 Fab fragment that binds to L1 with comparable activity as the function-triggering monoclonal antibody 557.B6 and induces neurite outgrowth and neuronal survival in cultured neurons, despite its monovalent function. Infusion of αL1 Fab into the lesioned spinal cord of mice enhanced functional recovery after thoracic spinal cord compression injury. αL1 Fab treatment resulted in reduced scar volume, enhanced number of tyrosine hydroxylase-positive axons and increased linear density of VGLUT1 (vesicular glutamate transporter 1) on motoneurons. Furthermore, the number and soma size of ChAT (choline acetyltransferase)-positive motoneurons and the linear density of ChAT-positive boutons on motoneurons as well as parvalbumin-positive interneurons in the lumbar spinal cord were elevated. Stimulation of endogenous L1 by application of the αL1 Fab opens new avenues for recombinant antibody technology, offering prospects for therapeutic applications after traumatic nervous system lesions.

Mst‐1 deficiency promotes post‐traumatic spinal motor neuron survival via enhancement of autophagy flux

“…Here, we demonstrated that genetic ablation of Mst-1 promotes SCIinduced motor neuron survival. However, although the Hippo/Mst-1 pathway can be stimulated by multiple types of cellular stress, including mechanical stress, DNA damage, and reactive oxygen species , it is still unknown how Mst-1 activation occurs during SCI-induced cellular stress (Hetz et al 2009;Liu et al 2010;Deng et al 2013;Maejima et al 2013;Li et al 2014;Loers et al 2014). Interestingly, consistent with previous report (Lee et al 2013), we found the phosphorylation of Mst-1 at Thr183 was activated in SCI, and the activation was specific for motor neurons.…”

Histamine Promotes Locomotion Recovery After Spinal Cord Hemisection via Inhibiting Astrocytic Scar Formation

“…Mean thickness of glial scar was calculated from fixed four areas per section. The scar volume was estimated according to the Cavalieri principle .…”

Function-Triggering Antibodies to the Adhesion Molecule L1 Enhance Recovery after Injury of the Adult Mouse Femoral Nerve

“…The function-triggering, i.e. agonistic action of the Fab fragment of antibody 557 has also been reported [37].…”

“…Our previous cell culture experiments with soluble beneficial function triggering monoclonal antibody 557 revealed optimal stimulation of neuronal growth and survival at 50 µg/ml or higher concentrations of 557 antibody in the cell culture medium [37], hence 400 µg/ml was chosen for the in vivo experiments to assure that the maximal stimulatory effect of the antibody can be reached. In these previous experiments we had used 200 µg/ml of a Fab fragment derived from antibody 557 in vivo and shown that the Fab is active in a similar micro-molar range as the IgG.…”