Targeting astrocyte-mediated neurotoxicity induced by ALS/FTD-associated RNA binding proteins.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are neurodegenerative disorders characterized by reactive astrocytes that contribute to neuronal injury through TAR DNA-binding protein 43 (TDP-43)-or fused in sarcoma (FUS)-driven neuroinflammatory signaling. Dehydrocostus lactone (DHE), a blood-brain barrier-permeable sesquiterpene lactone with established anti-inflammatory activity, represents a promising but unexplored therapeutic candidate for ALS/FTD.

METHODS: The therapeutic effects of DHE were evaluated in primary mouse and human astrocytes expressing ALS/FTD-associated RNA-binding protein pathology, ALS patient-derived fibroblasts, and primary cortical neurons exposed to astrocyte-conditioned medium. Drosophila models expressing mutant FUS or TDP-43 in glial cells were used to assess locomotor performance and survival. Molecular analyses examined nuclear factor kappa B (NF-κB) signaling, nuclear factor erythroid 2-related factor 2 (NRF2)-dependent antioxidant responses, protein aggregation, mitochondrial function, and inflammatory mediator production. Plasma concentrations of inflammatory cytokines and chemokines were measured in patients with sporadic ALS.

RESULTS: DHE exerted neuroprotective effects through a dual mechanism involving suppression of NF-κB-dependent inflammatory signaling and activation of NRF2-mediated antioxidant pathways in astrocytes exhibiting FUS or TDP-43 proteinopathy. DHE attenuated astrocyte-mediated neurotoxicity and improved neuronal mitochondrial function in conditioned-medium assays. In addition, DHE reduced pathological FUS accumulation in FUS P525L-expressing astrocytes and in stress-challenged patient-derived fibroblasts. In Drosophila models, DHE significantly improved locomotor function and extended survival. Translationally, the chemokines CXCL10, CCL3, and CCL19 were elevated in plasma from patients with ALS, were induced by FUS or TDP-43 pathology in astrocytes, and were suppressed by DHE treatment, supporting the clinical relevance of the inflammatory pathways targeted by DHE.

CONCLUSION: DHE mitigates astrocyte-driven neurotoxicity associated with ALS/FTD-related RNA-binding protein pathology by suppressing inflammatory signaling and enhancing antioxidant defense mechanisms. The consistent therapeutic effects observed across mouse and human cellular models, patient-derived samples, and in vivo Drosophila models support further investigation of DHE as a potential therapeutic strategy for ALS/FTD and highlight astrocyte-mediated signaling pathways as actionable targets in neurodegenerative disease.