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CNS-associated macrophages contribute to intracerebral aneurysm pathophysiology.

ABSTRACT: Intracerebral aneurysms (IAs) are pathological dilatations of cerebral arteries whose rupture leads to subarachnoid hemorrhage, a significant cause of disability and death. Inflammation is recognized as a critical contributor to the formation, growth, and rupture of IAs; however, its precise actors have not yet been fully elucidated. Here, we report CNS-associated macrophages (CAMs), also known as border-associated macrophages, as one of the key players in IA pathogenesis, acting as critical mediators of inflammatory processes related to IA ruptures. Using a new mouse model of middle cerebral artery (MCA) aneurysms we show that CAMs accumulate in the IA walls. This finding was confirmed in a human MCA aneurysm obtained after surgical clipping, together with other pathological characteristics found in the experimental model including morphological changes and inflammatory cell infiltration. In addition, in vivo longitudinal molecular MRI studies revealed vascular inflammation strongly associated with the aneurysm area, i.e., high expression of VCAM-1 and P-selectin adhesion molecules, which precedes and predicts the bleeding extent in the case of IA rupture. Specific CAM depletion by intracerebroventricular injection of clodronate liposomes prior to IA induction reduced IA formation and rupture rate. Moreover, the absence of CAMs ameliorated the outcome severity of IA ruptures resulting in smaller hemorrhages, accompanied by reduced neutrophil infiltration. Our data shed light on the unexplored role of CAMs as main actors orchestrating the progression of IAs towards a rupture-prone state.

SUBMITTER: Glavan M

PROVIDER: S-EPMC10946177 | biostudies-literature | 2024 Mar

REPOSITORIES: biostudies-literature

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CNS-associated macrophages contribute to intracerebral aneurysm pathophysiology.

Glavan Martina M Jelic Ana A Levard Damien D Frösen Juhana J Keränen Sara S Franx Bart A A BAA Bras Ana-Rita AR Louet Estelle R ER Dénes Ádám Á Merlini Mario M Vivien Denis D Rubio Marina M

Acta neuropathologica communications 20240318 1

Intracerebral aneurysms (IAs) are pathological dilatations of cerebral arteries whose rupture leads to subarachnoid hemorrhage, a significant cause of disability and death. Inflammation is recognized as a critical contributor to the formation, growth, and rupture of IAs; however, its precise actors have not yet been fully elucidated. Here, we report CNS-associated macrophages (CAMs), also known as border-associated macrophages, as one of the key players in IA pathogenesis, acting as critical med ...[more]

PMID: 38500201

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Project description:Background and purposeThe incidences of intracranial aneurysm and aneurysmal subarachnoid hemorrhage are high in postmenopausal women. Although population-based studies suggest that hormone replacement therapy is beneficial for postmenopausal women with intracranial aneurysms, estrogen replacement may no longer be recommended for the prevention of chronic diseases given its association with adverse outcomes, such as cancer and ischemic stroke. The isoflavone daidzein and its intestinal metabolite equol are bioactive phytoestrogens and potent agonists of estrogen receptors. Given their estrogenic properties, we investigated whether the isoflavones daidzein and equol are protective against the formation and rupture of intracranial aneurysms in a mouse model of the postmenopausal state.MethodsWe induced intracranial aneurysms in ovariectomized adult female mice using a combination of induced systemic hypertension and a single injection of elastase into the cerebrospinal fluid. We fed the mice with an isoflavone-free diet with/without daidzein supplementation, or in a combination of intraperitoneal equol, or oral vancomycin treatment. We also used estrogen receptor beta knockout mice.ResultsBoth dietary daidzein and supplementation with its metabolite, equol, were protective against aneurysm formation in ovariectomized mice. The protective effects of daidzein and equol required estrogen receptor-β. The disruption of the intestinal microbial conversion of daidzein to equol abolished daidzein’s protective effect against aneurysm formation. Mice treated with equol had lower inflammatory cytokines in the cerebral arteries, suggesting that phytoestrogens modulate inflammatory processes important to intracranial aneurysm pathogenesis.ConclusionsOur study establishes that both dietary daidzein and its metabolite, equol, protect against aneurysm formation in ovariectomized female mice through the activation of estrogen receptor-β and subsequent suppression of inflammation. Dietary daidzein’s protective effect required the intestinal conversion to equol. Our results indicate the potential therapeutic value of dietary daidzein and its metabolite, equol, for the prevention of the formation of intracranial aneurysms and related subarachnoid hemorrhage.

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CNS-associated macrophages contribute to intracerebral aneurysm pathophysiology.

Publications

CNS-associated macrophages contribute to intracerebral aneurysm pathophysiology.

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