Platelets impair the resolution of inflammation in atherosclerotic plaques in insulin-resistant mice after lipid lowering
Maria Laskou, Sofie Delbare, Michael Gildea, Ada Weinstock, Vitor De Moura Virginio, Maxwell La Forest, Franziska Krautter, Casey Donahoe, Letizia Amadori, Natalia Eberhardt, Tessa J. Barrett, Chiara Giannarelli, Jeffrey S. Berger, Edward A. Fisher
Maria Laskou, Sofie Delbare, Michael Gildea, Ada Weinstock, Vitor De Moura Virginio, Maxwell La Forest, Franziska Krautter, Casey Donahoe, Letizia Amadori, Natalia Eberhardt, Tessa J. Barrett, Chiara Giannarelli, Jeffrey S. Berger, Edward A. Fisher
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Research Article Cardiology Inflammation Vascular biology

Platelets impair the resolution of inflammation in atherosclerotic plaques in insulin-resistant mice after lipid lowering

Abstract

Insulin resistance impairs benefits of lipid-lowering treatment, as evidenced by higher cardiovascular disease risk in individuals with type 2 diabetes versus those without. Because platelet activity is higher in insulin-resistant patients and promotes atherosclerosis progression, we questioned whether platelets impair inflammation resolution in plaques during lipid lowering. In mice with obesity and insulin resistance, we induced advanced plaques and then implemented lipid lowering to promote atherosclerotic plaque inflammation resolution. Concurrently, mice were treated with either platelet-depleting or control antibodies for 3 weeks. Platelet activation and insulin resistance were unaffected by lipid lowering. Both antibody-treated groups showed reduced plaque macrophages, but plaque cellular and structural composition differed. In platelet-depleted mice, single-cell RNA-seq revealed dampened inflammatory gene expression in plaque macrophages and an expansion of a subset of Fcgr4+ macrophages having features of inflammation-resolving, phagocytic cells. Necrotic core size was smaller and collagen content greater, resembling stable human plaques. Consistent with the mouse results, clinical data showed that patients with lower platelet counts had decreased proinflammatory signaling pathways in circulating nonclassical monocytes after lipid lowering. These findings highlight that platelets hinder inflammation resolution in atherosclerosis during lipid-lowering treatment. Identifying novel platelet-targeted therapies following lipid-lowering treatment in individuals with insulin resistance may be a promising therapeutic approach to promote atherosclerotic plaque inflammation resolution.

Authors

Maria Laskou, Sofie Delbare, Michael Gildea, Ada Weinstock, Vitor De Moura Virginio, Maxwell La Forest, Franziska Krautter, Casey Donahoe, Letizia Amadori, Natalia Eberhardt, Tessa J. Barrett, Chiara Giannarelli, Jeffrey S. Berger, Edward A. Fisher

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Figure 1

Platelet activation and impaired glucose tolerance are sustained during the lipid-lowering treatment period in obese Ldlr–/– male mice.

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Platelet activation and impaired glucose tolerance are sustained during ...
(A) Study design. Eight-week-old Ldlr–/– male mice fed a high-fat, high-cholesterol (HFHC) diet for the whole duration of the study (23 weeks). After the atherosclerosis progression period (obese baseline, Ob), mice were injected with ApoB ASO to lower lipids (lipid-lowering period). All lipid-lowered mice were split into 2 groups, injected either with isotype control antibody (IgG) or platelet depletion antibody (αCD42b) every 3 days for a total of 3 weeks. (B) Platelet counts in circulating blood of Ob, IgG, and αCD42b 3 days before harvest. (C) Blood glucose measurements (lean n = 16, Ob n = 47) and (D) area of curve (AOC) quantification of glucose tolerance tests (GTTs) from lean, Ob, IgG, and αCD42b mice after 16 weeks of HFHC diet during atherosclerosis progression. (E) Blood glucose measurements (Ob n = 3, IgG n = 4, αCD42b n = 4) and (F) AOC quantification of GTTs from Ob, IgG, and αCD42b mice after 22 weeks of HFHC diet during atherosclerosis resolution. Mean fluorescent intensity (MFI) of platelet (G) JonA and (H) P-selectin in nonstimulated (NS) samples and upon 100 μM PAR4-AP agonist stimulation of lean and Ob circulating blood samples. (I) Mean platelet volume (MPV) from circulating blood of lean, Ob, and IgG-treated mice, 3 days before harvest. In C and E, error bars represent SD. Data were analyzed by Kruskal-Wallis with Dunn’s post hoc test (B and F), unpaired Mann-Whitney test (C, D, and H), unpaired Student’s t test (G), or ordinary 1-way ANOVA with Tukey’s multiple-comparison test (I). P values are shown in graphs.