T cell specific Eomes Deletion Does Not Protect Against High Fat Diet Induced Large Artery Stiffening

Abstract

We have found that T cells contribute to age-related large artery stiffness. The T-box transcription factor, Eomes is an important regulator of CD8+ (Cytotoxic) T cell differentiation from a naïve to a memory phenotype. We previously reported that these effector memory CD8+ T cells accumulate in the aorta of old mice. We aimed to investigate whether inhibiting CD8+ T cell memory differentiation in mice, specifically through T cell-specific Eomes deletion, would protect these animals from high-fat diet (HFD)-induced large artery stiffness. Mice with a CD8 driven Cre Recombinase were bred with mice with loxp sites surrounding the Eomes gene resulting in wild type (CD8 Eomes+/+) and T cell specific Eomes deleted (CD8 Eomesf/f) mice. Mice were randomly divided into a normal chow (NC) and HFD. Resulting in 8 mice of each genotype and diet. The NC group was given a normal diet containing 4% fat and the HFD group was given a high-fat diet containing 60% fat. At 4-8 months of age, doppler pulse wave velocity was used to assess large artery stiffness. Following euthanasia, aortic T cell phenotype was assessed using flow-cytometry. Group differences were assessed by two-way ANOVA and Tukey’s post-hoc test. Data shown as mean ± SD. Regardless of genotype, HFD had a significant impact on pulse wave velocity (PWV), indicating elevated aortic stiffness. In the HFD group, both CD8 Eomesf/f and CD8 Eomes+/+ mice exhibited higher PWV values (330.08±72.33 cm/s;312.5±53.74 cm/s) compared to their counterparts in the NC group (256.4±63.67 cm/s;259.2±66.36 cm/s, p=0.0172). To determine whether HFD-induced increases in aortic stiffness are accompanied by changes in aortic T cell phenotype, flow cytometric analysis was performed on the aorta. First, we observed, regardless of mouse genotype, HFD had a significant impact on CD4+ (Helper T) naïve cells, resulting in a blunted percentage of these cells. This dietary effect was observed in both CD8 Eomesf/f and CD8 Eomes+/+ mice (NCD CD8 Eomesf/f: 70.92±5.912%; NCD CD8 Eomes+/+ mice: 56.46±20.62%; HFD CD8 Eomesf/f: 47.5±7.865%; HFD CD8 Eomes+/+ mice: 50.58±13.907%; p=0.0206). In contrast, the percentages of CD8+ naïve cells did not display a significant change in response to the high-fat diet (p=0.6303). HFD significantly influenced CD4+ memory cells, resulting in an increase in percentages, regardless of mouse genotype (NCD CD8 Eomesf/f: 29.09± 5.909%; NCD CD8 Eomes+/+ mice: 44.27±19.17%; HFD CD8 Eomesf/f: 52.47±7.875%; HFD CD8 Eomes+/+ mice: 49.44±13.9%; p=0.02). However, HFD did not produce any significant alterations in CD8+ memory cell percentages (p=0.6). These results suggest that contrary to our hypothesis, T cell specific Eomes deletion is not suffcient to protect against diet induced large artery stiffness. However, this may be due to greater proportions of CD4+ memory cells in the aorta with high fat feeding. Funding: AHA 940023, NIH R01AG060395, K01AG061271. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.