Background: Rett syndrome (RTT) is an early-onset neurological disorder primarily affecting females, leading to severe cognitive and physical disabilities. Recent studies indicate that an imbalance of redox homeostasis and exacerbated inflammatory responses are key players in the clinical manifestations of the disease. Emerging evidence highlights that the p75 neurotrophin receptor (p75NTR) is implicated in the regulation of oxidative stress (OS) and inflammation. Thus, this study is aimed at investigating the effects of p75NTR modulation by LM11A-31 on fibroblasts derived from RTT donors. Methods: RTT cells were treated with 0.1 µM of LM11A-31 for 24 h, and results were obtained using qPCR, immunofluorescence, ELISA, and Western blot techniques. Results: Our findings demonstrate that LM11A-31 reduces OS markers in RTT fibroblasts. Specifically, p75NTR modulation by LM11A-31 restores protein glutathionylation and reduces the expression of the pro-oxidant enzyme NOX4. Additionally, LM11A-31 significantly decreases the expression of the pro-inflammatory mediators interleukin-6 and interleukin-8. Additionally, LM11A-31 normalizes the expression levels of transcription factors involved in the regulation of the antioxidant response and inflammation. Conclusions: Collectively, these data suggest that p75NTR modulation may represent an effective therapeutic target to improve redox balance and reduce inflammation in RTT.

Background/Objectives: Parkinson’s disease (PD) is one of the most prevalent neurodegenerative disorders. Despite its multifactorial etiology, PD pathophysiology shared specific features such as cytoplasmic α-synuclein inclusions, oxidative stress, mitochondrial dysfunction, and impaired autophagy. Bromodomain and Extra-Terminal domain (BET) proteins, functioning as epigenetic readers, have recently emerged as promising therapeutic targets due to their regulatory role in redox homeostasis, neuroinflammation, and autophagy. However, their potential involvement in PD pathophysiology remains largely unexplored. Therefore, we aimed at evaluating whether BET modulation could ameliorate the parkinsonian phenotype in two cellular models. Methods: Differentiated SH-SY5Y and N1E-115 neuronal cells were exposed to rotenone toxin to mimic PD phenotype and co-treated with the small BET inhibitor JQ1. Results: BET inhibition significantly counteracted rotenone-induced cell death, neuromorphological alterations, and α-synuclein accumulation. These protective effects were accompanied by restoration of redox balance, as indicated by enhanced activation of the antioxidant system and suppression of the pro-oxidant NADPH oxidase complex. Moreover, JQ1 treatment alleviated mitochondrial dysfunction and corrected autophagy impairments triggered by rotenone. Conclusions: These data highlight a novel role for BET proteins in neurodegeneration, suggesting that their modulation may represent a promising approach to counteract PD neuropathology.

Neurotrophins play pivotal roles in the development and proper functioning of the nervous system. The effects of these growth factors are mediated through the binding of high-affinity receptors, known as Trks, as well as the low-affinity receptor p75NTR. The latter has the capacity to induce complex signal pathways, as it favors both pro-survival and pro-apoptotic cascades depending on the physiopathological condition. Recent findings have indicated that p75NTR expression is increased in post-mortem Parkinson’s disease (PD) brains, and this upregulation is associated with a significant reduction in neuroprotection. Given its double-edged sword nature, p75NTR has recently been identified as a promising therapeutic target to counteract neurodegenerative events. The present study aims to assess the neuroprotective effects of p75NTR modulation in a rotenone-induced neuronal model of PD. To this end, differentiated SH-SY5Y cells were exposed to rotenone to mimic the PD phenotype, and the small molecule LM11A-31 was used to modulate p75NTR activity. The main results revealed that LM11A-31 significantly mitigated the hallmarks of PD, including cell death, neuromorphological aberrations, and α-synuclein accumulation. Pharmacological manipulation of p75NTR also reduced oxidative damage by increasing the expression of transcriptional factors that regulate the antioxidant response and by decreasing the expression of the pro-oxidant NADPH-oxidase modulatory subunits. Furthermore, LM11A-31 hampered cholesterol buildup induced by rotenone, normalizing the expression of proteins involved in cholesterol biosynthesis, uptake and intracellular trafficking. Taken together, these findings suggest that p75NTR modulation may represent a novel approach to counteracting PD abnormalities of redox and cholesterol metabolism.