Antibody targeting TDP-43 mitigates pathogenic pathways induced by the cerebrospinal fluid of ALS.

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease characterized by the cytoplasmic mislocalization and accumulation of TAR DNA binding protein 43 (TDP-43). We reported previously the protective effects in a transgenic mouse model expressing ALS-linked mutant TDP-43^A315T of a monoclonal antibody, called E6, binding specifically to the RNA Recognition Motif 1 (RRM1) domain of TDP-43. Here, we tested the effects of E6 antibody in an animal model of sporadic ALS based on the intracerebroventricular (i.c.v.) infusion during 14 days of cerebrospinal fluid (CSF) from sporadic ALS patients into transgenic mice expressing human TDP-43^WT. Either intrathecal (i.t.) or i.c.v. injection of E6 antibody conferred protective effects in this model of disease. Thus, the CSF-inoculated E6 antibody reduced motor and cognitive impairments, mitigated TDP-43 proteinopathy and prevented neurofilament (Nf) disorganization in cortical and spinal neurons. Administration of E6 antibody reduced the loss of motor neurons in the spinal cord and the denervation of neuromuscular junctions. Moreover, E6 antibody promoted a switch toward features associated with a protective phenotype of microglial activation characterized by enhanced phagocytic function and reduced secretion of pro-inflammatory cytokines. The results suggest that an immunotherapy targeting the RRM1 domain of TDP-43 may confer protection against pathogenic pathways triggered by the CSF of ALS patients.