Abstract MP229: Signaling Mechanisms Leading To CD4+ T-lymphocyte Activation During Ischemic Heart Failure
CD4 + T-cells turn pathological during chronic heart failure (HF). Phenotypic changes that mediate this transition are unknown. Thus, at 8 weeks post-infarction we conducted limited cell RNA-sequencing on 150 CD4 + T-cells isolated from rodent failing hearts and using ingenuity pathway analysis (z score>2) compared them either with CD4 + T-cells isolated from the mediastinal lymph nodes (mLNs) of the same mice or cardiac CD4 + T-cells from sham mice. T-cells isolated from the mLNs of HF mice showed enhanced TCR signaling (p<2X10 -4 ) with 3-6 fold increase in several downstream mediators such as ITK, MAPK, LCK and Zap70. We also observed heightened leukocyte extravasation signaling (p<2X10 -5 ) with significant increase in PKCθ, and Rho GTPase activating and Ras association domain proteins. These are consistent with enhanced antigen-presentation, and TCR activation during HF. Moreover, we observed significant upregulation of oxidative phosphorylation (p<3X10 -15 ) in cardiac CD4 + T-cells as compared to mLN T-cells with 2-3 fold increase in the gene expression of ATP synthase subunits and cytochrome C indicative of their increased metabolic activity upon infiltration into the failing hearts. Compared to CD4 + T-cells from sham hearts, significant upregulation of inflammatory genes (p<3X10 -5 ), chemotactic factors (p<8X10 -4 ), and several pro-inflammatory cytokine-mediated pathways such as IL-6 (p<2X10 -4 ), IL-1a (p<2X10 -3 ) and TNFα (p<2X10 -3 ) was observed in cardiac CD4 + T-cells from HF mice. Interestingly, we also observed a significant upregulation of homing (p<3X10 -4 ) and connective tissue remodeling genes (p<1.8X10 -3 ) with >8-fold increase in genes like LCN2, SLPI, IGF1, FGFR1, LTF, and TIMP2 required for transmigration and homing of CD4 + T-cells into the ischemic hearts. Our studies show enhanced antigenic CD4 + T-cell activation in the mLNs supporting enhanced pro-inflammatory signaling, metabolic activation, and extravasation into the ischemic hearts.