Browsing by Author "Miller, Francis J"
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Item Open Access Drebrin attenuates atherosclerosis by limiting smooth muscle cell transdifferentiation.(Cardiovascular research, 2021-04-29) Wu, Jiao-Hui; Zhang, Lisheng; Nepliouev, Igor; Brian, Leigh; Huang, Taiqin; Snow, Kamie P; Schickling, Brandon M; Hauser, Elizabeth R; Miller, Francis J; Freedman, Neil J; Stiber, Jonathan AAims
The F-actin-binding protein Drebrin inhibits smooth muscle cell (SMC) migration, proliferation and pro-inflammatory signaling. Therefore, we tested the hypothesis that Drebrin constrains atherosclerosis.Methods and results
SM22-Cre+/Dbnflox/flox/Ldlr-/- (SMC-Dbn-/-/Ldlr-/-) and control mice (SM22-Cre+/Ldlr-/-, Dbnflox/flox/Ldlr-/-, and Ldlr-/-) were fed a Western diet for 14-20 weeks. Brachiocephalic arteries of SMC-Dbn-/-/Ldlr-/- mice exhibited 1.5- or 1.8-fold greater cross-sectional lesion area than control mice at 14 or 20 wk, respectively. Aortic atherosclerotic lesion surface area was 1.2-fold greater in SMC-Dbn-/-/Ldlr-/- mice. SMC-Dbn-/-/Ldlr-/- lesions comprised necrotic cores that were two-fold greater in size than those of control mice. Consistent with their bigger necrotic core size, lesions in SMC-Dbn-/- arteries also showed more transdifferentiation of SMCs to macrophage-like cells: 1.5- to 2.5-fold greater, assessed with BODIPY or with CD68, respectively. In vitro data were concordant: Dbn-/- SMCs had 1.7-fold higher levels of KLF4 and transdifferentiated to macrophage-like cells more readily than Dbnflox/flox SMCs upon cholesterol loading, as evidenced by greater up-regulation of CD68 and galectin-3. Adenovirally mediated Drebrin rescue produced equivalent levels of macrophage-like transdifferentiation in Dbn-/- and Dbnflox/flox SMCs. During early atherogenesis, SMC-Dbn-/-/Ldlr-/- aortas demonstrated 1.6-fold higher levels of reactive oxygen species than control mouse aortas. The 1.8-fold higher levels of Nox1 in Dbn-/- SMCs was reduced to WT levels with KLF4 silencing. Inhibition of Nox1 chemically or with siRNA produced equivalent levels of macrophage-like transdifferentiation in Dbn-/- and Dbnflox/flox SMCs.Conclusions
We conclude that SMC Drebrin limits atherosclerosis by constraining SMC Nox1 activity and SMC transdifferentiation to macrophage-like cells.Translational perspective
Drebrin is abundantly expressed in vascular smooth muscle cells (SMCs) and is up-regulated in human atherosclerosis. A hallmark of atherosclerosis is the accumulation of foam cells that secrete pro-inflammatory cytokines and contribute to plaque instability. A large proportion of these foam cells in humans derive from SMCs. We found that SMC Drebrin limits atherosclerosis by reducing SMC transdifferentiation to macrophage-like foam cells in a manner dependent on Nox1 and KLF4. For this reason, strategies aimed at augmenting SMC Drebrin expression in atherosclerotic plaques may limit atherosclerosis progression and enhance plaque stability by bridling SMC-to-foam-cell transdifferentiation.Item Open Access Drebrin regulates angiotensin II-induced aortic remodelling.(Cardiovascular research, 2018-11) Zhang, Lisheng; Wu, Jiao-Hui; Huang, Tai-Qin; Nepliouev, Igor; Brian, Leigh; Zhang, Zhushan; Wertman, Virginia; Rudemiller, Nathan P; McMahon, Timothy J; Shenoy, Sudha K; Miller, Francis J; Crowley, Steven D; Freedman, Neil J; Stiber, Jonathan AAims
The actin-binding protein Drebrin is up-regulated in response to arterial injury and reduces smooth muscle cell (SMC) migration and proliferation through its interaction with the actin cytoskeleton. We, therefore, tested the hypothesis that SMC Drebrin inhibits angiotensin II-induced remodelling of the proximal aorta.Methods and results
Angiotensin II was administered via osmotic minipumps at 1000 ng/kg/min continuously for 28 days in SM22-Cre+/Dbnflox/flox (SMC-Dbn-/-) and control mice. Blood pressure responses to angiotensin II were assessed by telemetry. After angiotensin II infusion, we assessed remodelling in the proximal ascending aorta by echocardiography and planimetry of histological cross sections. Although the degree of hypertension was equivalent in SMC-Dbn-/- and control mice, SMC-Dbn-/- mice nonetheless exhibited 60% more proximal aortic medial thickening and two-fold more outward aortic remodelling than control mice in response to angiotensin II. Proximal aortas demonstrated greater cellular proliferation and matrix deposition in SMC-Dbn-/- mice than in control mice, as evidenced by a higher prevalence of proliferating cell nuclear antigen-positive nuclei and higher levels of collagen I. Compared with control mouse aortas, SMC-Dbn-/- aortas demonstrated greater angiotensin II-induced NADPH oxidase activation and inflammation, evidenced by higher levels of Ser-536-phosphorylated NFκB p65 subunits and higher levels of vascular cell adhesion molecule-1, matrix metalloproteinase-9, and adventitial macrophages.Conclusions
We conclude that SMC Drebrin deficiency augments angiotensin II-induced inflammation and adverse aortic remodelling.Item Open Access Inhalation of an RNA aptamer that selectively binds extracellular histones protects from acute lung injury.(Molecular therapy. Nucleic acids, 2023-03) Lei, Beilei; Wang, Chaojian; Snow, Kamie; Graton, Murilo E; Tighe, Robert M; Fager, Ammon M; Hoffman, Maureane R; Giangrande, Paloma H; Miller, Francis JAcute lung injury (ALI) is a syndrome of acute inflammation, barrier disruption, and hypoxemic respiratory failure associated with high morbidity and mortality. Diverse conditions lead to ALI, including inhalation of toxic substances, aspiration of gastric contents, infection, and trauma. A shared mechanism of acute lung injury is cellular toxicity from damage-associated molecular patterns (DAMPs), including extracellular histones. We recently described the selection and efficacy of a histone-binding RNA aptamer (HBA7). The current study aimed to identify the effects of extracellular histones in the lung and determine if HBA7 protected mice from ALI. Histone proteins decreased metabolic activity, induced apoptosis, promoted proinflammatory cytokine production, and caused endothelial dysfunction and platelet activation in vitro. HBA7 prevented these effects. The oropharyngeal aspiration of histone proteins increased neutrophil and albumin levels in bronchoalveolar lavage fluid (BALF) and precipitated neutrophil infiltration, interstitial edema, and barrier disruption in alveoli in mice. Similarly, inhaling wood smoke particulate matter, as a clinically relevant model, increased lung inflammation and alveolar permeability. Treatment by HBA7 alleviated lung injury in both models of ALI. These findings demonstrate the pulmonary delivery of HBA7 as a nucleic acid-based therapeutic for ALI.