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Suppression of IL-1β promotes beneficial accumulation of fibroblast-like cells in atherosclerotic plaques in clonal hematopoiesis [CITE-seq]

ABSTRACT: Clonal hematopoiesis (CH) is an independent risk factor for atherosclerotic cardiovascular disease. Murine models of CH suggest a central role of inflammasomes and IL-1β in accelerated atherosclerosis and plaque destabilization. Here we show using scRNAseq in human carotid plaques that inflammasome components are enriched in macrophages, while the receptor for IL-1β is enriched in fibroblasts and smooth muscle cells (SMCs). To address the role of inflammatory crosstalk in features of plaque destabilization, we conducted SMC fate mapping in mice modeling Jak2VF or Tet2 CH treated with IL-1β antibodies. Unexpectedly, this treatment minimally affected SMC differentiation, leading instead to a prominent expansion of fibroblast-like cells. Depletion of fibroblasts from mice treated with IL-1β antibody resulted in thinner fibrous caps. Conversely, genetic inactivation of Jak2VF during plaque regression promoted fibroblasts accumulation and fibrous cap thickening. Our studies suggest that suppression of inflammasomes promotes plaque stabilization by recruiting fibroblast-like cells to the fibrous cap.

ORGANISM(S): Mus musculus

PROVIDER: GSE248276 | GEO | 2023/11/25

REPOSITORIES: GEO

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Project description:Despite decades of research, our understanding of processes controlling the stability of late-stage atherosclerotic plaques remains poor. However, a prevailing hypothesis is that reducing inflammation may improve plaque stability. Indeed, the potent inflammatory cytokine, interleukin-1β (IL-1β), has been shown to be a key driver of atherosclerosis development. Importantly, the CANTOS Trial recently demonstrated that administration of an anti-IL-1β antibody to high-risk post-myocardial infarction (MI) patients reduced the incidence of recurrent nonfatal MI, but did not reduce the incidence of cardiovascular death or stroke. As such, although the CANTOS trial results providing exciting evidence that targeting inflammation can have clinical benefit for treating advanced atherosclerosis, extensive further investigation is needed to better understand the mechanisms by which IL-1β inhibition impacts established lesions. Therefore, we performed intervention studies on smooth muscle cell (SMC) lineage tracing mice with advanced atherosclerosis using anti-IL- 1 or IgG control antibodies. Surprisingly, we found no effect on lesion size but a profound shift in the composition of the fibrous cap characterized by reduced collagen and SMC content but an increase in macrophage number, which was primarily driven by opposite effects on the proliferation of these respective cell types. By generating SMC-specific and macrophage-selective Il1r1 KO Apoe -/- mice, we found that SMC-specific Il1r1 KO resulted in a ~60% reduction in lesion size and lesions that were nearly devoid of YFP + SMC whereas, myeloid-selective loss of IL1R1 had no effect on lesion size, or cell composition. This suggests that SMC are a primary cell type responding to IL-1β in atherosclerosis and that IL1 signaling in SMC is critical for their investment and retention within the fibrous cap. In addition, we found that inhibition of IL-1β promoted an expansion of the M2 macrophage population within the fibrous cap, and that these effects may be due in part to elevated levels of IL4. Taken together, results show that IL-1β can promote beneficial changes in late-stage murine atherosclerosis by promoting maintenance of a SMC/collagen-rich fibrous cap. Moreover, studies identify critical cell types and pathways that need to be considered when attempting to develop safer and more effective anti-inflammatory therapies for widespread treatment of atherosclerotic disease, including in moderate or low risk patients.

Project description:Neuroinflammation is thought to contribute to the pathogenesis of Alzheimer’s disease (AD), yet numerous studies have demonstrated a beneficial role for neuroinflammation in amyloid plaque clearance. We have previously shown that sustained expression of IL-1β in the hippocampus of APP/PS1 mice decreases amyloid plaque burden independent of recruited CCR2+ myeloid cells, suggesting resident microglia as the main phagocytic effectors of IL-1β-induced plaque clearance. To date, however, the mechanisms of IL-1β-induced plaque clearance remain poorly understood. To determine whether IL-1β-induced plaque clearance is due to enhanced microglial phagocytosis of Aβ, APP/PS1 mice induced to express mature human IL-1β in the hippocampus via adenoviral transduction were treated with the Aβ fluorescent probe methoxy-X04 (MX04) and microglial internalization of Aβ was analyzed by flow cytometry and immunohistochemistry. We found that resident microglia (CD45loCD11b+) constituted >70% of the MX04+ cells in both control and IL-1β-treated conditions, and that <10% of MX04+ cells were recruited myeloid cells (CD45hiCD11b+). However, we found that IL-1β treatment did not augment the percentage of MX04+ microglia nor the quantity of Aβ internalized by individual microglia. Instead, we found that IL-1β treatment resulted in a significant increase in the total number of MX04+ microglia in the hippocampus due to IL-1β-induced proliferation. Consistent with these results, transcriptomic analyses revealed very similar gene expression profiles between MX04+ and MX04- microglia, indicating IL-1β does not drive enhanced expression of phagocytosis-related genes. By contrast, IL-1β treatment was associated with large-scale changes in the expression of genes related to proliferation, immune function and inflammation. Together, these studies demonstrate that IL-1β induces microglial proliferation and the expression of genes involved in inflammatory immune functions that may be related to Aβ clearance.

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Suppression of IL-1β promotes beneficial accumulation of fibroblast-like cells in atherosclerotic plaques in clonal hematopoiesis [CITE-seq]

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