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Treatment of advanced atherosclerotic mice with ABT-263 reduced indices of plaque stability and increased mortality.

ABSTRACT: The use of senolytic agents to remove senescent cells from atherosclerotic lesions is controversial. A common limitation of previous studies is the failure to rigorously define the effects of senolytic agent ABT-263 (Navitoclax) on smooth muscle cells (SMC) despite studies claiming that these cells are the major source of senescent cells. Moreover, there are no studies on the effect of ABT-263 on endothelial cells (EC), which - along with SMC - comprise 90% of α-smooth muscle actin+ (α-SMA+) myofibroblast-like cells in the protective fibrous cap. Here we tested the hypothesis that treatment of advanced atherosclerotic mice with ABT-263 will reduce lesion size and increase plaque stability. SMC (Myh11-CreERT2-eYFP) and EC (Cdh5-CreERT2-eYFP) lineage tracing Apoe-/- mice were fed a western diet (WD) for 18 weeks, followed by ABT-263 at 100 mg/kg/bw for 6 weeks or 50 mg/kg/bw for 9 weeks. ABT-263 treatment did not change lesion size or lumen area of the brachiocephalic artery (BCA). However, ABT-263 treatment reduced SMC by 90% and increased EC contributions to lesions via EC-to-mesenchymal transition (EndoMT) by 60%. ABT-263 treatment also reduced α-SMA+ fibrous cap thickness by 60% and was associated with a > 50% mortality rate. Taken together, ABT-263 treatment of WD-fed Apoe-/- mice with advanced lesions resulted in multiple detrimental changes, including reduced indices of stability and increased mortality.

SUBMITTER: Karnewar S

PROVIDER: S-EPMC10906456 | biostudies-literature | 2024 Jan

REPOSITORIES: biostudies-literature

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Treatment of advanced atherosclerotic mice with ABT-263 reduced indices of plaque stability and increased mortality.

Karnewar Santosh S Karnewar Vaishnavi V Shankman Laura S LS Owens Gary K GK

JCI insight 20240123 2

The use of senolytic agents to remove senescent cells from atherosclerotic lesions is controversial. A common limitation of previous studies is the failure to rigorously define the effects of senolytic agent ABT-263 (Navitoclax) on smooth muscle cells (SMC) despite studies claiming that these cells are the major source of senescent cells. Moreover, there are no studies on the effect of ABT-263 on endothelial cells (EC), which - along with SMC - comprise 90% of α-smooth muscle actin+ (α-SMA+) myo ...[more]

PMID: 38258907

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Project description:The use of senolytic agents to remove senescent cells from atherosclerotic lesions is controversial. A common limitation of previous studies is the failure to rigorously define the effects of senolytic agent ABT-263 (Navitoclax) on smooth muscle cells (SMC) despite studies claiming that they are the major source of senescent cells. Moreover, there are no studies of the effect of ABT-263 on endothelial cells (EC), which along with SMC comprise 90% of α-SMA + myofibroblast-like cells in the protective fibrous cap. Here we tested the hypothesis that treatment of advanced atherosclerotic mice with the ABT-263 will reduce lesion size and increase plaque stability. SMC (Myh11-CreER T2 -eYFP) and EC (Cdh5-CreER T2 -eYFP) lineage tracing Apoe -/- mice were fed a WD for 18 weeks, followed by ABT-263 100mg/kg/bw for six weeks or 50mg/kg/bw for nine weeks. ABT-263 treatment did not change lesion size or lumen area of the brachiocephalic artery (BCA). However, ABT-263 treatment reduced SMC by 90% and increased EC-contributions to lesions via EC-to-mesenchymal transition (EndoMT) by 60%. ABT-263 treatment also reduced α-SMA + fibrous cap thickness by 60% and increased mortality by >50%. Contrary to expectations, treatment of WD-fed Apoe -/- mice with the senolytic agent ABT-263 resulted in multiple detrimental changes including reduced indices of stability, and increased mortality.Graphical abstractUploaded separately.HighlightsTreatment of Apoe-/- mice with advanced atherosclerosis with the senolytic agent ABT-263 increased mortality by >50%.ABT-263 showed a 90% reduction in SMC but a 60% increase in endothelial cell (EC) contributions to lesions via EC to mesenchymal transition (EndoMT) but prevented adaptive increases in investment of EC-derived cells into the fibrous cap via beneficial EndoMT to myofibroblast transitions that we have shown normally occur when SMC investment into fibrous cap of lesions is impaired.Knock out (KO) of Klf4 in SMC, which results in smaller but more stable atherosclerotic lesions, was associated with reduced expression of pro-senescence markers, but preserved expression of the anti-senescence marker, telomerase reverse transcriptase although it is unclear if the latter is causal or an effect.

Project description:ObjectiveThere is increasing evidence supporting the role of platelets in atherosclerotic vascular disease. The G-protein-coupled receptor P2Y12 is a central mediator of platelet activation and aggregation but has also been linked to platelet-independent vascular disease. Ticagrelor is an oral P2Y12 antagonist that is used as a standard treatment in patients after acute myocardial infarction. However, the effects of ticagrelor on advanced atherosclerosis have not been investigated.Materials and methodsTwenty-week-old apolipoprotein-E-deficient mice received standard chow or standard chow supplemented with 0.15% ticagrelor (approximately 270 mg/kg/day) for 25 weeks. The lesion area was evaluated in the aortic sinus by Movat's pentachrome staining and lesion composition, thickness of the fibrous cap, and size of the necrotic core evaluated by morphometry. RAW 264.7 macrophages were serum starved and treated with ticagrelor in vitro for the detection and quantification of apoptosis. In addition, oxLDL uptake in RAW 264.7 macrophages was evaluated.ResultsA trend toward the reduction of total lesion size was detected. However, data did not reach the levels of significance (control, n=11, 565,881 μm(2) [interquartile range {IQR} 454,778-603,925 μm(2)] versus ticagrelor, n=13, 462,595 μm(2) [IQR 379,740-546,037 μm(2)]; P=0.1). A significant reduction in the relative area of the necrotic core (control, n=11, 0.46 [IQR 0.4-0.51] versus ticagrelor, n=13, 0.34 [IQR 0.31-0.39]; P=0.008), and a significant increase in fibrous caps thickness (control, n=11, 3.7 μm [IQR 3.4-4.2 μm] versus ticagrelor, n=13, 4.7 [IQR 4.3-5.5 μm], P=0.04) were seen in ticagrelor-treated mice. In vitro studies demonstrated a reduction in apoptotic RAW 264.7 macrophages (control 0.07±0.03 versus ticagrelor 0.03±0.03; P=0.0002) when incubated with ticagrelor. Uptake of oxLDL in RAW 264.7 was significantly reduced when treated with ticagrelor (control 9.2 [IQR 5.3-12.9] versus ticagrelor 6.4 [IQR 2.5-9.5], P=0.02).ConclusionThe present study demonstrates for the first time a plaque-stabilizing effect of ticagrelor in a model of advanced vascular disease, potentially induced by a reduction of oxLDL uptake or an inhibition of apoptosis as seen in vitro.

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Treatment of advanced atherosclerotic mice with ABT-263 reduced indices of plaque stability and increased mortality.

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Treatment of advanced atherosclerotic mice with ABT-263 reduced indices of plaque stability and increased mortality.

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