Abstract P3068: TNFR1 Regulates Cellular Proliferation And Not Pathogenicity Of Cd4 + T-lymphocytes During Ischemic Heart Failure

Abstract

Ischemic heart failure (HF) is associated with elevated inflammatory responses including pro-inflammatory cytokines, such as Tumor necrosis factor (TNF) α [and its cognate receptors, TNF receptor (TNFR) 1 and TNFR2] and pathological switching of CD4 + T-cells. TNF-TNFR2 signaling is known to promote CD4 + T-cell activation and proliferation. However, it is unknown if CD4 + T-cells also express TNFR1, and if elevated TNFα-TNFR1 signaling during HF mediates pathological effects of CD4 + T-cells. Using flow cytometry, we show that TNFR1 + CD4 + T-cells are amplified in the hearts at 3 days (d) and 8 weeks (wks) post-MI (HF) in mice. As compared to sham, while TNFα expression (and %) is blunted in CD4 + T-cells at 3 d post-MI, it is increased during HF with significantly higher expression in TNFR1 + T-cells as compared to TNFR1 - T-cells. Splenic CD4 + T-cells activated using anti-CD3/CD28 antibodies and treated with neutralizing anti-TNFR1 antibody showed increased T-cell proliferation, and Bcl-xL (pro-survival factor) and TNFα expression without affecting activation marker (CD69) suggesting a role of TNFR1 in mediating pro-apoptotic signaling without affecting activation. To confirm these results, we adoptively transferred (AT) HF-activated splenic WT and TNFR1 -/- T-cells (CD45.2) into CD45.1 naïve mice, and measured changes in cardiac function of recipient mice by echocardiography (as an indicator of pathological activity), and donor T-cells (as a measure of cell survival) in the blood, heart, spleen and mediastinal lymph nodes (mLNs) at 14 wks post-AT. Compared to WT, we observed amplified levels of donor TNFR1 -/- T-cells in the blood, spleen, and mLNs which were not different in the hearts. Consistently, recipient mice injected either with WT and TNFR1 -/- T-cells showed similar degrees of cardiac dysfunction. Interestingly, at 14 wks post-AT the expression of ki67, a proliferation marker, was magnified in HF-activated TNFR1 -/- T-cells (as compared to WT) infiltrated into the myocardium suggesting that TNF-TNFR1 mediates pro-survival and proliferative signaling in T-cells during HF, and not their pathogenicity. Our results also provide deeper insights into the paradoxical outcomes observed in the clinical trials antagonizing TNFα in human HF patients.