ESTROGEN RECEPTOR ALPHA LOCALIZATION AFFECTS CYTOKINE GENE EXPRESSION AFTER TLR7 AGONISM IN LUPUS-PRONE MALES

PV010 / #583 Poster Topic: AS02 - Animal Models Background/Purpose Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disease characterized by autoantibody production and immune complex formation, resulting in inflammation and tissue damage. There are gaps in knowledge regarding the pathogenesis of SLE, including female sex as a risk factor. It has also been suggested that male patients diagnosed with SLE have increased disease severity (organ-threatening disease) compared to women. It is known that estrogen contributes to SLE disease expression. Estrogen exerts its effects on the immune system via the nuclear hormone receptor estrogen receptor alpha (ERα), and ERα’s function is tissue-, cell-, and localization-specific. Herein, we backcrossed mice with membrane-only ERα (MOER) function and nuclear-only ERα (NOER) function onto the lupus-prone B6.Nba2 strain. This allows us to investigate the hypothesis that ERα localization to the membrane may impact SLE disease development. Methods Bone marrow (BM) was isolated from MOER, NOER, and wild-type (WT) male B6.Nba2 mice at 12 weeks of age. On days 0 and 3, BM cells were cultured with GM-CSF and IL-4 (10 ng/uL) to promote dendritic cell (BMDC) differentiation. On day 7, BMDCs were treated with 200 µM of loxoribine (Lox, a Toll-like receptor 7 agonist) or DMSO vehicle for 6 hours. Message levels of proinflammatory cytokines IL-1β, IL6, and TNF-α were assessed via qPCR. Results NOER BMDCs had a trend toward increased Il1β expression after 6 hours of Lox treatment compared to MOER (p=0.07) but not WT BMDCs (p=0.91). There was a trend toward downregulation of Il1β in MOER BMDCs treated with Lox compared to WT BMDCs (p=0.14). MOER BMDCs also had decreased Il6 compared to WT BMDCs (p=0.02), while BMDCs from NOER mice trended toward increased tnf-α expression compared to MOER (p=0.07) BMDCs. Conclusions These preliminary results suggest that ERα localization to the plasma membrane impacts IL-1β, IL-6 and TNF-α expression in DCs. Non-genomic mechanisms of action by membrane ERα may be involved in antiinflammatory signaling. Further investigation is warranted in female mice to elucidate sex differences in pro- and antiinflammatory cytokine profiles in WT, MOER, and NOER BMDCs after TLR7 agonism.