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Alternate high fat diet aggravates atherosclerosis through an IL1b-dependent reprogramming of neutrophil progenitors

ABSTRACT: Systemic immune responses induced by chronic hypercholesterolemia contribute to the initiation, progression and complications of atherosclerosis. However, the consequences of an alternate high fat diet and the associated variations in plasma cholesterol levels on atherosclerosis are unknown. To address this relevant issue concerning common situations where dietary habits change over time, we developed a novel protocol in athero-prone mice that allowed us to compare the effects of alternate versus continuous high fat diet (HFD) on atherosclerosis, the overall period of time of exposure to HFD being similar between groups. We showed that alternate HFD lead to accelerated atherosclerosis in Ldlr-/- and Apoe-/- mice compared to continuous HFD. The pro-atherogenic effect of alternate HFD was also found in Apoe-/-Rag2-/- mice lacking T, B, and NKT cells, ruling out a role for the adaptive immune system in the observed phenotype. Using different complementary in vivo approaches, we found that lipid-rich diet discontinuation in alternate group downregulated Runx1, a negative regulator downstream of TLR-4 pathways. As a result, after re-exposure to HFD, myeloid progenitors were more sensitive to hypercholesterolemia leading to acute differentiation into IL-1b- producing immature neutrophils, which caused a state of emergency myelopoiesis. Consecutively, neutrophils markedly increased in the peripheral blood, infiltrated atherosclerotic lesions and locally released neutrophil extracellular traps. Anti-Ly6G neutrophil depletion abolished the pro-atherogenic effects of alternate HFD. Specific deletion of Il1b and Il1b receptor confirmed that the IL-1b signaling pathway was a major driver of the pro-inflammatory and pro-atherogenic neutrophil signature. Finally, treatment with anti-IL-1b neutralizing antibody or inflammasome inhibitor during re-exposure to HFD reversed the pro-atherogenic effects of alternate HFD. In summary, we showed that alternate HFD accelerates atherosclerosis through IL-1b-dependent neutrophil progenitor reprogramming.

ORGANISM(S): Mus musculus

PROVIDER: GSE252604 | GEO | 2024/04/14

REPOSITORIES: GEO

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Project description:Systemic immune responses induced by chronic hypercholesterolemia contribute to the initiation, progression and complications of atherosclerosis. However, it is common for individuals to change dietary habits over time. The consequences of an alternating high fat diet and the associated variations in plasma cholesterol levels on atherosclerosis are unknown. To address this relevant issue, we developed a novel protocol in atherosclerosis-prone mice that allowed us to compare the effects of alternate versus continuous high fat diet (HFD) on atherosclerosis, while keeping the overall period of exposure to HFD similar between groups. We showed that an alternate HFD lead to accelerated atherosclerosis in Ldlr-/- and Apoe 55 -/- mice compared to continuous HFD. This pro-atherogenic effect of alternate HFD was also observed in Apoe-/-Rag2 57 -/- mice lacking T, B, and NKT cells, ruling out the role of the adaptive immune system in the observed phenotype. Employing various complementary in vivo approaches, we discovered that discontinuing HFD in the alternate group downregulated Runx1, a negative regulator of inflammatory signaling pathways in the myeloid lineage. Consequently, after re61 exposure to HFD, myeloid progenitors were primed to respond to HFD re-exposure by differentiating into IL-1-producing immature neutrophils, and inducing a state of emergency myelopoiesis. Subsequently, neutrophils markedly increased in the peripheral blood, infiltrated atherosclerotic lesions and locally released neutrophil extracellular traps. Anti-Ly6G neutrophil depletion abolished the pro-atherogenic effects of alternate HFD. Specific deletion of Il1b and Il1 receptor confirmed that the IL-1 signaling pathway was a major driver of the pro67 inflammatory and pro-atherogenic neutrophil signature. Finally, treatment with anti-IL-1 neutralizing antibody or an inflammasome inhibitor during re-exposure to HFD reversed the pro-atherogenic effects of alternate HFD. In summary, we showed that alternate HFD accelerates atherosclerosis through IL-1-dependent neutrophil progenitor reprogramming.

Project description:Objectives: Pinolenic acid (PNLA), an omega-6 polyunsaturated fatty acid from pine nuts, has anti-inflammatory and anti-atherogenic effects. We aimed to investigate the direct anti-inflammatory effect and anti-atherogenic effects of PNLA on activated purified CD14 monocytes from peripheral blood of patients with rheumatoid arthritis (RA) in vitro. Methods: Flow cytometry was used to assess the proportions of CD14 monocytes expressing TNF-α, IL-6, IL-1β, and IL-8 in purified monocytes from patients with RA after lipopolysaccharide (LPS) stimulation with/without PNLA pre-treatment. The whole genomic transcriptome (WGT) profile of PNLA-treated, and LPS-activated monocytes from patients with active RA was investigated by RNA-sequencing. Results: PNLA reduced percentage of monocytes expressing cytokines: TNF-a by 23% (p=0.048), IL-6 by 25% (p=0.011), IL-1B by 23% (p=0.050), IL-8 by 20% (p=0.066). Pathway analysis identified upstream activation of peroxisomes proliferator-activated receptors (PPARs), sirtuin3, and let7miRNA, KLF15 which are anti-inflammatory and antioxidative. In contrast, DAP3, LIF and STAT3, which are involved in TNF-a, and IL-6 signal transduction, were inhibited. Canonical Pathway analysis showed that PNLA inhibited oxidative phosphorylation (p=9.14E-09) and mitochondrial dysfunction (p=4.18E-08), while the sirtuin (SIRTs) signalling pathway was activated (p=8.89E-06) which interfere with the pathophysiologic process of atherosclerosis. Many miRNAs were modulated by PNLA suggesting potential post-transcriptional regulation of metabolic and immune response that has not been described previously. Multiple miRNAs target pyruvate dehydrogenase kinase-4 (PDK4), single-immunoglobulin interleukin-1 receptor molecule (SIGIRR), mitochondrially encoded ATP synthase membrane subunit 6 (MT-ATP6) and Acetyl-CoA Acyltranferase2 (ACAA2); genes implicated in regulation of lipid and cell metabolism, inflammation, and mitochondrial dysfunction. Conclusion: PNLA has potential anti-atherogenic and immune-metabolic effects on monocytes that are pathogenic in RA and atherosclerosis. Dietary PNLA supplementation regulates key miRNAs that are involved in metabolic, mitochondrial, and inflammatory pathways.

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Alternate high fat diet aggravates atherosclerosis through an IL1b-dependent reprogramming of neutrophil progenitors

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