Myeloid Irf5 Deficiency Enhances the Therapeutic Efficacy of IMD-0354 in a TDP-25-Induced Neurodegeneration Model

Neuroinflammation is recognized as a key contributor to the pathogenesis and progression of amyotrophic lateral sclerosis (ALS), with dysregulated innate immune activation implicated in exacerbating neuronal injury. However, the molecular mechanisms by which macrophages contribute to neurodegeneration in motor neurons harboring TAR DNA-binding protein 43 (TDP-43) mutations are not fully understood. M1 macrophages were generated from the bone marrow of Irf5 knockout or wild-type mice and co-cultured with the NSC34 motor neuron-like cell line overexpressing the C-terminal fragment of TDP-43 (TDP-25) using a Transwell system. Mitochondrial alterations, and apoptosis were evaluated through Western blotting, flow cytometry, and transmission electron microscopy. IMD-0354 mitigated mitochondrial dysfunction and apoptosis induced by TDP-25 exposure. This neuroprotective effect was attenuated in the presence of pro-inflammatory macrophages. Notably, the absence of Irf5 expression in macrophages amplified the protective efficacy of IMD-0354. Irf5 expression in macrophages may modulate the therapeutic efficacy of IMD-0354 in the context of TDP-43-associated proteinopathy, indicating a potential target for enhancing treatment strategies in ALS-related neurodegeneration through inhibiting inflammation.