Abstract Body: Background: Pathological T-cell activation promotes left-ventricular (LV) remodeling and disease progression in ischemic heart failure (HF). We have previously shown that Estrogen Receptor (ER) α signaling is activated in CD4⁺helper T-cells (Th) in HF mice, and our novel ERβ agonist, OSU-ERβ-012, suppresses T-cell activation, blunts LV remodeling and progressive cardiac dysfunction.
Approach: We examined the efficacy of OSU-ERβ-012 in inhibiting CD4⁺ T-cell activation and proliferation in HF and control patients. Sorted CD4⁺ T-cells were stimulated with anti-CD3/CD28 antibodies and evaluated for activation and proliferation with and without OSU-ERβ-012 (0.5-10 μM).
Results: OSU-ERβ-012 treatment significantly inhibited proliferation of circulating CD4⁺ T-cells isolated from the HF patients in a dose-dependent manner with an IC₅₀ of 5.6 µM. Anti-CD3/CD28 treatment resulted in markedly elevated CD69 and TNFα expressing CD4⁺ T-cells as compared to non-stimulated T-cells (3.5-fold, p <0.0001). OSU-ERβ-012 treatment significantly reduced CD69⁺ and TNFα⁺ CD4⁺ T-cells to 51.6 ± 15.3% (p <0.0001) and 76.2 ± 24.1% (p =0.0093), respectively, at 5 μM compared with vehicle-treated CD4⁺ T-cells. These effects were not due to cytotoxicity as T-cell viability was not affected even at 10 µM OSU-ERβ-012 dose. Importantly, these effects were sex independent and T-cells from both male and female HF patients were inhibited with similar potencies. Interestingly, OSU-ERβ-012 did not inhibit CD4⁺ T-cell proliferation in control patients, indicating that ERα signaling and ERβ agonism effects are specific to HF. Surprisingly, OSU-ERβ-012 also failed to inhibit CD4⁺ T-cells from some of the HF patients suggesting patient specific effects which could be due to the differences in receptor affinities to bind ERα/β agonists. To test this, we identified eight splice variants of ERβ (ESR2) and utilized Webina 1.0.5 autodock vina to predict estradiol binding to these splice variants. Interestingly, we observed significant differences in binding energies (indicative of receptor affinities for ERβ agonists) ranging from -4.835 kcal/mol to +32.36 kcal/mol. Different ERβ splice variants in patients may be exploited to tailor HF treatment with ERβ agonists like OSU-ERβ-012. Taken together, these results indicate that OSU-ERβ-012 inhibits T-cell activation and proliferation in HF patients, suggesting ERβ-targeted immunomodulation as a potential treatment for inflammatory cardiovascular disease.