Galectin-9: A novel promoter of atherosclerosis progression

Elsevier

Available online 19 November 2022

AtherosclerosisAuthor links open overlay panelHighlights•

Galectin-9 deficiency reduces plaque burden in vivo.

Soluble Gal-9 induces a pro-inflammatory phenotype in macrophages.

Monocytes are captured and adhere to immobilised Gal-9 under physiological flow.

Endothelial cells are source of circulating Gal-9 which is increased in PAD patients.

AbstractBackground and aims

Atherosclerosis is widely accepted to be an inflammatory disease driven by lipid accumulation and leukocyte recruitment. More recently, galectins, a family of β-galactoside binding proteins, have been shown to play a role in leukocyte recruitment among other immunomodulatory functions. Galectin (Gal) −9, a tandem repeat type galectin expressed by the endothelium in inflammatory environments, has been proposed to promote leukocyte recruitment. However, the role of Gal-9 in the context of monocyte recruitment remains elusive.

Methods and results

Here, we characterise the immunomodulatory role of Gal-9 in context of atherosclerosis. We show that ApoE−/−Gal-9−/− mice have a significantly reduced aortic plaque burden compared to their ApoE−/− littermate controls after 12 weeks of high fat diet. RNA sequencing data from two independent studies reveal Lgals9 expression in leukocyte clusters isolated from murine atherosclerotic plaques. Additionally, soluble Gal-9 protein induces monocyte activation and a pro-inflammatory phenotype in macrophages. Furthermore, we show that immobilised recombinant Gal-9 acts as capture and adhesion molecule for CD14+ monocytes in a β2-integrin and glycan dependent manner, while adhesion of monocytes to stimulated endothelium is reduced when Gal-9 is knocked down. Gal-9 also facilitates enhanced recruitment of leukocytes from peripheral arterial disease (PAD) patients compared to healthy young and aged controls. We further characterise the endothelium as source of circulating Gal-9, which is increased in plasma of PAD patients compared to healthy controls. These results highlight a pathological role for Gal-9 as promoter of monocyte recruitment and atherosclerotic plaque progression, making it a novel target in the prevention of plaque formation and progression.

Keywords

Macrophages

Galectin-9

Atherosclerosis

Monocytes

© 2022 The Authors. Published by Elsevier B.V.

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