ANGIOTENSIN II-INDUCED HYPERTENSION INDUCES INNATE IMMUNE MEMORY AND PROMOTES ATHEROSCLEROSIS PROGRESSION [RNA-seq]

Recently, a phenomenon that promotes long-lasting innate immune activation called ‘trained immunity’ has been identified. Trained immunity is driven by epigenetic and metabolic reprogramming of innate immune progenitors in response to specific stimuli. This ‘priming’ of progenitors results in innate immune cell progeny that are epigenetically and transcriptionally rewired to mount an augmented inflammatory response. Hypothesis: We hypothesize that hypertension induces trained immunity in myeloid progenitor, leading to persistent monocyte activation and increased atherosclerosis progression. Methods and Results: To examine whether residual cardiovascular risk in treated hypertensive (Rx-HTN) patients correlates with increased inflammation, we analyzed serum and PBMC samples from normotensive (NT), untreated hypertensive (HTN), and Rx-HTN patients and observed multiple markers of increased inflammation in the Rx-HTN and HTN groups. To investigate causality, we induced Angiotensin-II (Ang II)-mediated hypertension in donor mice, followed by bone marrow transplantation into irradiated C57BL/6 or atherosclerosis-prone Ldlr-/- mice. Fourteen weeks post-transplant, flow cytometry and in vivo peritonitis experiments revealed an elevated inflammatory state in C57BL/6 mice transplanted with hypertensive marrow compared to controls. This increased inflammation was evidenced by increased monocyte recruitment to zymosan-induced sterile inflammation and circulating monocyte skewing to pro-inflammatory monocyte subsets. In Ldlr-/- recipients fed a Western diet for 10 weeks, Ang II-induced hypertensive marrow recipients had accelerated atherosclerosis compared to normotensive marrow recipients. Flow cytometry analysis of bone marrow and whole blood isolated from Ldlr-/- recipients demonstrated increased monocytosis and progenitor expansion in hypertensive marrow recipients, a hallmark of trained immunity. Integrated bulk RNA-seq and ATAC-seq analyses of isolated monocyte progeny from Ang II-trained hematopoietic stem and progenitor cells (HSPCs) revealed durable transcriptional and epigenetic signatures characteristic of trained immunity. Using an in vitro model of trained immunity with human CD34+ stem cells or murine HSPCs, transient Ang II exposure before myeloid differentiation was sufficient to induce training and led to an increased pro-inflammatory cytokine response to LPS. Interestingly, while treatment with an angiotensin receptor blocker did not eliminate the training phenotype, blocking or genetically deleting Dectin-1—the canonical receptor involved in trained immunity—completely abolished the Ang II-induced inflammatory response in vitro. This finding highlights the essential role of Dectin-1 in mediating Ang II-induced trained immunity. Conclusion: Our results suggest that Ang II induces trained immunity in immune progenitors via a Dectin-1 mediated pathway. These findings represent a novel mechanism by which hypertension contributes to the long-term increased risk of atherosclerosis in treated hypertensive patients. Hypertension confers substantial residual risk of atherosclerotic cardiovascular disease (ASCVD) even after blood pressure is controlled, suggesting that hypertensive signaling leaves a persistent pathogenic imprint. Here we show that angiotensin II (Ang II) induces trained immunity in hematopoietic progenitors, generating monocyte progeny with enhanced inflammatory cytokine production and metabolic rewiring. Bone marrow from Ang II-treated mice accelerated atherosclerosis after transplantation into Ldlr−/− recipients, despite the absence of continued Ang II exposure, demonstrating durable and transferable reprogramming of the hematopoietic system. Monocytes from recipient mice retained transcriptional features of innate immune memory for up to 14 weeks. This inflammatory program was not prevented by angiotensin receptor blockade but was abrogated by genetic deletion or antibody-mediated inhibition of Dectin-1. These findings identify Dectin-1 as a non-canonical mediator of Ang II-induced trained immunity and establish a blood-pressure-independent mechanism linking hypertension to persistent myeloid activation and long-term ASCVD risk.