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<p>Obesity is a major stroke risk factor. By 72&#xa0;h after ischemia, obese mice exhibit greater stroke sizes, neuroinflammation, and motor deficits. However, the immune mechanisms driving these outcomes remain incompletely understood. To define how obesity reshapes the immune response to stroke, we performed single-cell RNA sequencing of immune cells in the blood and brain 72&#xa0;h after stroke or sham surgery in control-diet and diet-induced obese mice. In the blood, macrophages and neutrophils from obese mice exhibited the most pronounced transcriptional changes under both sham and stroke conditions. These changes included <i>Ly6c2-Cd68-Cx3cr1-</i>enriched monocyte-derived transitioning macrophages and classic macrophage populations enriched in the lipid droplet gene perilipin-2 (<i>Plin2</i>) with one also enriched with foamy macrophage marker <i>Cd36</i>; chemotaxis-associated neutrophil subtypes enriched in <i>Cxcl2</i> or <i>Cxcr2;</i> and interferon-signaling neutrophils. Obese mice after sham surgery exhibited minimal immune changes in the brain, but after stroke, we report substantial transcriptional changes in infiltrating monocyte-derived macrophages with high or intermediate <i>Plin2</i> expression, interferon-signaling dendritic cells, and <i>Cxcl2</i>-enriched neutrophils. The obesity-induced changes in immune cells across both blood and brain are characterized by elevated lipid handling, inflammation, cellular stress, and notable coagulation pathways in the brain neutrophils. Co-expression analyses revealed that elevated <i>Plin2</i>, a hallmark of obesity, is positively correlated with lipid-related, immune, stress, and pro-thrombotic genes. We tested its role by stereotactically injecting <i>Plin2</i> siRNA into the stroke. In non-obese mice, <i>Plin2</i> knockdown increased infarct size and worsened motor outcomes despite reducing inflammatory markers (CD68, IFITM3, and TSPO), suggesting that early lipid droplet accumulation is neuroprotective and stimulates the immune response to stroke. In obese mice, <i>Plin2</i> knockdown mildly worsened motor deficits while reducing obesity-elevated CD68. Collectively, these findings identify elevated lipid handling, neuroinflammation, cellular stress, and coagulation as key transcriptional features of obesity-exacerbated stroke outcomes while revealing a protective role for <i>Plin2.</i></p>

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Obesity supersizes macrophage and neutrophil activation after stroke while lipid droplets play a protective role

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年3月19日

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  • Karen Bradshaw,
  • John Holsten,
  • Oliver Hahn,
  • Aulden Foltz,
  • Kristy A. Zera,
  • Li Zhu,
  • Christine Haarslev,
  • Tony Wyss-Coray,
  • Todd C. Peterson,
  • Marion S. Buckwalter

摘要

Obesity is a major stroke risk factor. By 72 h after ischemia, obese mice exhibit greater stroke sizes, neuroinflammation, and motor deficits. However, the immune mechanisms driving these outcomes remain incompletely understood. To define how obesity reshapes the immune response to stroke, we performed single-cell RNA sequencing of immune cells in the blood and brain 72 h after stroke or sham surgery in control-diet and diet-induced obese mice. In the blood, macrophages and neutrophils from obese mice exhibited the most pronounced transcriptional changes under both sham and stroke conditions. These changes included Ly6c2-Cd68-Cx3cr1-enriched monocyte-derived transitioning macrophages and classic macrophage populations enriched in the lipid droplet gene perilipin-2 (Plin2) with one also enriched with foamy macrophage marker Cd36; chemotaxis-associated neutrophil subtypes enriched in Cxcl2 or Cxcr2; and interferon-signaling neutrophils. Obese mice after sham surgery exhibited minimal immune changes in the brain, but after stroke, we report substantial transcriptional changes in infiltrating monocyte-derived macrophages with high or intermediate Plin2 expression, interferon-signaling dendritic cells, and Cxcl2-enriched neutrophils. The obesity-induced changes in immune cells across both blood and brain are characterized by elevated lipid handling, inflammation, cellular stress, and notable coagulation pathways in the brain neutrophils. Co-expression analyses revealed that elevated Plin2, a hallmark of obesity, is positively correlated with lipid-related, immune, stress, and pro-thrombotic genes. We tested its role by stereotactically injecting Plin2 siRNA into the stroke. In non-obese mice, Plin2 knockdown increased infarct size and worsened motor outcomes despite reducing inflammatory markers (CD68, IFITM3, and TSPO), suggesting that early lipid droplet accumulation is neuroprotective and stimulates the immune response to stroke. In obese mice, Plin2 knockdown mildly worsened motor deficits while reducing obesity-elevated CD68. Collectively, these findings identify elevated lipid handling, neuroinflammation, cellular stress, and coagulation as key transcriptional features of obesity-exacerbated stroke outcomes while revealing a protective role for Plin2.