446-P: Lipid Droplet Protein PLIN1 Regulates Inflammatory Polarity in Human Macrophages and Is Involved in Atherosclerotic Plaque Development by Promoting Stable Lipid Storage
Authors: CHO KYU YONG , MIYOSHI HIDEAKI , NAKAMURA AKINOBU , ATSUMI TATSUYA 
Published: May 2022

Background: Lipid droplet (LD) proteins play important roles in lipid accumulation and maturation in adipocytes. The relationship among PLIN family proteins and macrophage polarization in atherosclerosis has not been elucidated.
Methods: The experiments used human artery tissues from 65 patients who had undergone a carotid endarterectomy. Cultured macrophages generated from healthy human peripheral blood mononuclear cells are utilized as well.
Results: Plaque immunohistochemistry demonstrated co-expression of PLIN1 and PLIN2 in both symptomatic (n=31) and asymptomatic patients (n=34) . PLIN2 mRNA expression increased 3.38-fold in the symptomatic group compared with those from asymptomatic. PLIN1 was not expressed on small LDs at a shorter incubation (24 h) but was on large LDs at longer incubation (7 days) with oxidized LDL and VLDL, while PLIN2 was observed after 24 h and increased with a longer incubation in cultured M1 macrophage. In M2 macrophages, PLIN1 was seen as early as 24 h following incubation with VLDL, and LD size increased with longer incubation. PLIN1 overexpression increased the size of LDs in M1 macrophages, even after a short incubation, and reduced the RNA expression of TNFA, MMP2, ABCA1, and ABCG1 versus the M1 control. Conversely, silencing of PLIN1 in M2 macrophages had the contrary effects on LD size and RNA expression.
Conclusion: There was a relationship among macrophage polarity, cytosolic LD size, and PLIN1/PLIN2 expression levels. PLIN2 was mainly expressed in arterial plaques in symptomatic stroke patients, and associated with the inflammatory phenotype of human macrophages, while PLIN1 expression is closely associated with plaque stability and the anti-inflammatory phenotype.

Disclosure
K.Cho: None. H.Miyoshi: Research Support; Abbott Japan Co., Ltd., Boehringer Ingelheim International GmbH, Daiichi Sankyo, Kowa Company, Ltd., LifeScan, Mitsubishi Tanabe Pharma Corporation, Novo Nordisk, Ono Pharmaceutical Co., Ltd., Sumitomo Dainippon Pharma Co., Ltd., Taisho Pharmaceutical Holdings Co., Ltd., Speaker's Bureau; Astellas Pharma Inc., Boehringer Ingelheim International GmbH, Eli Lilly and Company, Kowa Company, Ltd., Merck & Co., Inc., Mitsubishi Tanabe Pharma Corporation, Novo Nordisk, Ono Pharmaceutical Co., Ltd., Sanofi K.K., Sumitomo Dainippon Pharma Co., Ltd., Taisho Pharmaceutical Holdings Co., Ltd. A.Nakamura: Research Support; Kissei Pharmaceutical Co., Ltd., MSD, Nippon Boehringer Ingelheim, Taisho Pharmaceutical Holdings Co., Ltd. T.Atsumi: Consultant; AbbVie Inc., AstraZeneca, MEDICAL & BIOLOGICAL LABORATORIES CO., Nippon Boehringer Ingelheim Co. Ltd., Novartis Pharma K.K., Ono Pharmaceutical Co., Ltd., Pfizer Inc., Research Support; AbbVie Inc., Alexion Pharmaceuticals, Inc., Astellas Pharma Inc., Chugai Pharmaceutical Co., Ltd., Daiichi Sankyo, Mitsubishi Tanabe Pharma Corporation, Nippon Boehringer Ingelheim Co. Ltd., Otsuka Pharmaceutical Co., Ltd., Pfizer Inc., Taiho Pharmaceutical Co. Ltd., Takeda Pharmaceutical Company Limited, Teijin Pharma Limited, Speaker's Bureau; AbbVie Inc., Astellas Pharma Inc., Bristol-Myers Squibb Company, Chugai Pharmaceutical Co., Ltd., Daiichi Sankyo, Eisai Co., Ltd., Eli Lilly and Company, Kyowa Kirin Co., Ltd., Mitsubishi Tanabe Pharma Corporation, Novartis Pharma K.K., Pfizer Inc., Taiho Pharmaceutical Co. Ltd., Takeda Pharmaceutical Company Limited, UCB, Inc.