Loss of TDP-43 Drives Innate Immune Activation Through Relish in Drosophila

Inflammatory and immune alterations are increasingly recognized as components of ALS pathology, yet whether they arise as a direct consequence of TDP-43 dysfunction or as a downstream response to neurodegeneration remains unresolved. To address this question, we profiled adult head transcriptomes of Drosophila lacking TBPH, the fly homolog of TDP-43, and identified marked overactivation of the conserved Toll/Imd/NF-κB (Relish) innate immune pathway, including increased expression of antimicrobial effector genes and inflammatory genes. We further found that TDP-43/TBPH regulates the NF-κB homolog Relish by associating with its mRNA and that its loss permits Relish-dependent immune overactivation. Genetic reduction in Relish in TDP-43-deficient flies suppressed inflammatory signaling and ameliorated neurological defects in vivo, indicating that immune dysregulation contributes to TDP-43 loss-associated phenotypes.