Impaired NF ‐ κB /Nrf2 Crosstalk in Rett Syndrome

Rett syndrome (RTT), caused primarily by mutations in the X-linked MECP2 gene, is a neurodevelopmental disorder marked by systemic alterations, including mitochondrial dysfunction, chronic oxidative stress, and persistent subclinical inflammation. This OxInflammatory state suggests that disruption of redox-inflammatory regulatory pathways may contribute to disease pathophysiology. In this context, NF-κB and Nrf2 represent two important signaling regulators that operate in a coordinated crosstalk to balance inflammatory activation and antioxidant defense. In this study, we explored the functional status of NF-κB/Nrf2 crosstalk in primary dermal fibroblasts derived from RTT patients and healthy controls (CTR). Under basal conditions, RTT fibroblasts exhibited increased nuclear localization of NF-κB p65 and higher levels of acetylated NF-κB, indicating a constitutive inflammatory condition. In contrast, Nrf2 activation was not proportionally enhanced, suggesting an imbalance between inflammatory and antioxidant signaling. Following LPS stimulation, CTR fibroblasts displayed the expected coordinated activation of NF-κB and Nrf2 pathways, along with induction of downstream target genes. RTT fibroblasts, however, failed to activate either pathway and showed blunted transcriptional responses. These findings support the presence of a dysregulated signaling axis consistent with a chronic OxInflammatory state. Analysis of regulatory mechanisms revealed increased basal CBP/p300 levels in RTT cells without a compensatory increase in SIRT1, pointing toward altered acetylation dynamics that may favor persistent NF-κB activity. To mechanistically study the NF-κB/Nrf2 crosstalk, LPS-stimulated cells were treated with the Nrf2 activator sulforaphane (SFN), alone or combined with the NF-κB inhibitor BAY-117082. In RTT fibroblasts, these combined interventions significantly reduced pro-inflammatory cytokine expression and consistently enhanced HMOX1 transcription and HO-1 protein levels. Although nuclear localization changes were modest at the selected time point, downstream gene expression patterns indicated that coordinated modulation of inflammatory and antioxidant pathways can partially rebalance cellular responses. Taken together, our findings provide preliminary evidence that RTT exhibits a dysfunctional NF-κB/Nrf2 regulatory axis characterized by basal inflammatory activation and impaired antioxidant compensation. Modulation of NF-κB signaling, in combination with Nrf2 activation, may represent a promising strategy to counteract the persistent OxInflammatory milieu associated with RTT and warrants further investigation.