To investigate the role of lipopolysaccharide (LPS) from Porphyromonas gingivalis and miR-155-5p-enriched exosomes in the formation of foam cells and the occurrence of carotid atherosclerosis (CAS).The CAS tissue samples and plasma from the healthy control group or patients undergoing periodontitis without CAS and with CAS were collected at the Xuanwu Hospital, Capital Medical University. The expression level of miR-155-5p was evaluated by immunofluorescent analysis and qRT-PCR. Oil red O staining and lipid accumulation assays were performed to explore the effects of LPS and miR-155-5p on mouse macrophage Raw264.7 and human monocytes THP-1. The expression levels of lipid-regulated genes were detected by qRT-PCR. Dual-luciferase reporter gene assay and DET1 overexpressed or inhibited Raw264.7 cells were used to verify the target gene of exosomal miR-155-5p. ApoE-/- mice were used to confirm the auxo-action of atherosclerosis from exosomal miR-155-5p in vivo, and LAL assay was used to detect the LPS content.miR-155-5p was higher in patients with periodontitis and CAS plasma exosomes than those in patients without CAS. The expression of miR-155-5p was significantly increased in CAS tissues compared with Normal tissues, and the expression level of miR-155-5p was associated with lipid-regulated genes in CAS tissues. MiR-155-5p-enriched exosomes accelerated lipid accumulation in macrophage-like cells and promoted the activity of lipid-accumulation genes by targeting DET1. In ApoE-/- mice, circulating miR-155-5p-enriched exosomes captured LPS, and the LPS-laden exosomes conferred plasma access for LPS, triggering the formation of foam cells and the occurrence of CAS.miR-155-5p enriched exosomes capture and escort LPS to the atherosclerotic sites, licensing the formation of foam cells and thus promoting CAS.© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.