IL-21R blockade reduces atherosclerosis development in LDLR-/- mice

Abstract

Background and Aims : Many pro-inflammatory cytokines increase during atherosclerosis and contribute to disease progression. Elevated IL-21 serum levels have been found in CAD patients, but its exact role in atherosclerosis remains unknown. IL-21 is primarily secreted by T-cells and binds to the IL-21 receptor (IL-21R), which is expressed on most lymphoid and myeloid cells. Consequently, IL-21/IL-21R signaling has pleiotropic effects and can cause activation of immune cells but can also inhibit anti-inflammatory Tregs. In this study, we aim to provide further insight into the role of IL-21 in atherosclerosis by blocking the IL-21/IL-21R axis.Methods: First, we confirmed IL-21R expression on many immune cells within the atherosclerotic plaque of Ldlr-/- mice and carotid endarterectomy patients using flow cytometry and scRNAseq. Next, Ldlr-/- mice were fed a Western-type diet for five weeks, during which mice were treated with an IL-21R blocking antibody or an isotype control.Results: IL-21R blockade significantly reduced atherosclerosis development by 38%. This coincided with increased atheroprotective Foxp3 expression within aortic CD4+ T-cells and elevated percentages of CD4+Foxp3+ cells in lymphoid organs (spleen: αIL-21R: 14.02±0.48% vs. ctr: 12.18±0.32%, P <0.01, HLN: αIL-21R: 21.97±1.05% vs. ctr: 18.77±1.06%, P<0.05). Similarly, significantly increased anti-inflammatory IL-10 was observed in serum (αIL-21R: 617.63±156.93 vs ctr: 36.01±29.93 pg/mL, P <0.001) and culture supernatant from splenocytes (αIL-21R: 64.86±10.24 vs ctr: 38.48±5.41 pg/mL, P <0.05) of αIL-21R-treated mice.Conclusions: Collectively, we show that IL-21R blockade reduces atherosclerosis by promoting atheroprotective regulatory T-cell immunity and elevating anti-inflammatory IL-10 production, representing a promising novel therapeutic strategy to extend health span and to combat CVD. Background and Aims : Many pro-inflammatory cytokines increase during atherosclerosis and contribute to disease progression. Elevated IL-21 serum levels have been found in CAD patients, but its exact role in atherosclerosis remains unknown. IL-21 is primarily secreted by T-cells and binds to the IL-21 receptor (IL-21R), which is expressed on most lymphoid and myeloid cells. Consequently, IL-21/IL-21R signaling has pleiotropic effects and can cause activation of immune cells but can also inhibit anti-inflammatory Tregs. In this study, we aim to provide further insight into the role of IL-21 in atherosclerosis by blocking the IL-21/IL-21R axis. Methods: First, we confirmed IL-21R expression on many immune cells within the atherosclerotic plaque of Ldlr-/- mice and carotid endarterectomy patients using flow cytometry and scRNAseq. Next, Ldlr-/- mice were fed a Western-type diet for five weeks, during which mice were treated with an IL-21R blocking antibody or an isotype control. Results: IL-21R blockade significantly reduced atherosclerosis development by 38%. This coincided with increased atheroprotective Foxp3 expression within aortic CD4+ T-cells and elevated percentages of CD4+Foxp3+ cells in lymphoid organs (spleen: αIL-21R: 14.02±0.48% vs. ctr: 12.18±0.32%, P <0.01, HLN: αIL-21R: 21.97±1.05% vs. ctr: 18.77±1.06%, P<0.05). Similarly, significantly increased anti-inflammatory IL-10 was observed in serum (αIL-21R: 617.63±156.93 vs ctr: 36.01±29.93 pg/mL, P <0.001) and culture supernatant from splenocytes (αIL-21R: 64.86±10.24 vs ctr: 38.48±5.41 pg/mL, P <0.05) of αIL-21R-treated mice. Conclusions: Collectively, we show that IL-21R blockade reduces atherosclerosis by promoting atheroprotective regulatory T-cell immunity and elevating anti-inflammatory IL-10 production, representing a promising novel therapeutic strategy to extend health span and to combat CVD.