p75NTR Modulation by LM11A-31 Counteracts Oxidative Stress and Cholesterol Dysmetabolism in a Rotenone-Induced Cell Model of Parkinson’s Disease

The p75 neurotrophin receptor (p75NTR) plays a dual role in regulating both pro-survival and pro-apoptotic cascades in various physiological and pathological conditions, including within dopaminergic neuronal population. Notably, its overexpression has been documented in post-mortem Parkinson's disease (PD) brains, where it correlates with a significant downregulation in neuroprotective intracellular mediators. In this study, we aimed at investigating the neuroprotective effects of p75NTR modulation by the small molecule LM11A-31 in a rotenone-induced neuronal model of PD. Differentiated SH-SY5Y cells were treated with 100 nM rotenone, with or without 500 nM LM11A-31. Our results show that LM11A-31 effectively mitigates PD phenotype by enhancing cell viability, reducing apoptosis, mitigating α-synuclein aggregation, and partially restoring neuromorphological features. Mitochondrial integrity was preserved, likely through the upregulation of transcription factors involved in mitochondrial biogenesis, namely PGC-1α and PPARs. LM11A-31 treatment also reduced oxidative damage to macromolecules, normalizing Nrf2 expression and enhancing protein S-glutathionylation. The antioxidant effect of p75NTR modulation may be partially attributed to the suppression of the NADPH oxidase regulatory subunits p22PHOX and p47PHOX. Additionally, LM11A-31 restored cholesterol homeostasis disrupted by rotenone, as evidenced by the increased NPC1 expression and lysosomal localization, normalized HMGCR levels, and reduced intracellular cholesterol accumulation. Collectively, these findings demonstrate that p75NTR modulation via LM11A-31 exerts neuroprotective effects by targeting key pathological features of PD, including oxidative damage, mitochondrial derangements, and cholesterol dysmetabolism, supporting its potential as a promising therapeutic tool in PD treatment.