id_869. TARGETING POST-ISCHEMIC NEUROINFLAMMATION WITH PAPE-1 BEYOND THE ACUTE THERAPEUTIC WINDOW
Andrzej Łach1, Bernadeta A. Pietrzak-Wawrzyńska1, Karolina Przepiórska-Drońska1,2, Wiktoria Płonka1, Agnieszka Wnuk1
1 Maj Institute of Pharmacology Polish Academy of Sciences, Department of Pharmacokinetics and Drug Metabolism, Team III
2 Maj Institute of Pharmacology Polish Academy of Sciences, Department of Experimental Neuroendocrinology
INTRODUCTION: Therapeutic options for ischemic stroke remain limited, particularly beyond the acute intervention window and secondary injury mechanisms such as neuroinflammation are poorly targeted by current treatments. To combat those limitation we researched a novel compound Pathway Preferential Estrogen-1 (PaPE-1), designed to selectively activate non-nuclear estrogen receptor (ER) signaling while minimizing classical hormonal detrimental effects associated with non-specific ERs activation.
AIM(S): This study investigated the effects of PaPE-1 on post-ischemic inflammatory responses and examined whether modulation of retinoid X receptor (RXR) isoforms expression contributes to its neuroprotective actions.
METHOD(S): Mouse primary neocortical neurons and a human microglial cell line were subjected to ischemia followed by PaPE-1 treatment during reoxygenation to model delayed intervention. Inflammatory mediators (interleukins, Cox2, Nlrp3) were quantified using qPCR and ELISA. We have also assessed the neuronal expression of RXRα, RXRβ, and RXRγ and inflammation-associated microRNAs. Microglial proliferation and viability were evaluated using BrdU incorporation, calcein staining, and morphological analysis.
RESULTS: PaPE-1 significantly reduced ischemia-induced pro-inflammatory signaling including IL1β, IL10, COX2, miR-19a, miR-130a and miR-132. Ischemia decreased neuronal RXRα isoform expression, and PaPE-1 was able to attenuate these changes. Moreover, PaPE-1 normalized microglial activation, as indicated by reduced BrdU incorporation and decreased microglial cell area.
CONCLUSIONS: Selective activation of non-nuclear ER signaling by PaPE-1 attenuates post-ischemic inflammation and supports neuronal resilience, working on both genomic and proteomic levels. Regulation of microglia activation together with normalization of neuronal RXR isoforms expression, especially RXRα, may contribute to reduced secondary inflammatory injury, posing PaPE-1 as a promising therapeutic tool for ischemic stroke beyond the acute phase.
FINANCIAL SUPPORT: National Science Centre of Poland, grant number 2021/43/D/NZ7/00633