Abstract:Aim To investigate the effects of fatty acid-binding protein 5 (FABP5) on lipid metabolism and inflammatory responses during atherosclerosis (As), and to explore the potential interaction between FABP5 and carnitine palmitoyltransferase 1A (CPT1A), so as to clarify the molecular regulatory network of FABP5 in the initiation and progression of As and its therapeutic potential. Methods Differentially expressed genes associated with coronary endothelial dysfunction were screened using the GSE132651 dataset. A protein-protein interaction network was constructed using the STRING database, followed by GO and KEGG enrichment analysis. Lipid metabolism-related genes were obtained from the Reactome database and intersected with differentially expressed genes to identify lipid metabolism-related candidate genes. An As model was established in ApoE－/－ mice fed a high-fat diet, followed by in vivo intervention with FABP5 knockdown lentivirus (sh-FABP5) or combined FABP5/CPT1A knockdown lentiviruses (sh-FABP5+sh-CPT1A) via tail vein injection. An oxidized-low density lipoprotein (ox-LDL)-induced RAW264.7 macrophage foam cell model was used for in vitro validation, including FABP5 knockdown (si-FABP5), FABP5 overexpression (OE-FABP5), and FABP5 overexpression combined with CPT1A knockdown (OE-FABP5+si-CPT1A). qPCR was used to detect the mRNA expression levels of FABP5, CPT1A, and inflammatory cytokines. High-performance liquid chromatography was used to measure intracellular cholesterol levels. Western blot was performed to detect the expression of FABP5, CPT1A, and lipid metabolism-related proteins. ELISA was used to determine inflammatory cytokine levels, biochemical assays were used to measure serum lipid profiles, and HE staining, Masson staining, and CD68 immunofluorescence were used to evaluate aortic root plaque lesions. Results Analysis of the GSE132651 dataset identified 24 significantly differentially expressed genes between the coronary endothelial dysfunction group and the normal endothelial function group, including 11 upregulated and 13 downregulated genes. Intersecting these genes with Reactome lipid metabolism-related genes identified three lipid metabolism-related differentially expressed genes:FABP5, FABP4, and ANKRD1. After ox-LDL treatment, FABP5, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) mRNA expression levels and intracellular total cholesterol (TC), free cholesterol (FC), and cholesteryl ester (CE) levels in RAW264.7 cells increased significantly compared with the normal control group (P＜0.05). Compared with the model group, FABP5 knockdown significantly reduced IL-6, TNF-α, and IL-1β mRNA expression, and TC, FC and CE levels. FABP5 overexpression further increased inflammatory cytokine expression and cholesterol accumulation, with statistically significant differences (P＜0.05). STRING prediction, Co-IP assays, and GSE54666 dataset analysis suggested a potential functional association between FABP5 and CPT1A. In a human primary macrophage foam cell dataset, both FABP5 and CPT1A were significantly upregulated in ox-LDL-induced foam cells (P＜0.01). Further in vitro experiments showed that, compared with the OE-FABP5 group, the OE-FABP5+sh-CPT1A group exhibited significantly lower mRNA expression of IL-6, TNF-α and IL-1β, as well as lower levels of TC, FC and CE (P＜0.05). In vivo, compared with the As group, FABP5 knockdown significantly decreased serum TC, TG and LDLC levels while increasing HDLC level; the aortic root plaque area, collagen-positive area and mean fluorescence intensity of CD68 were also markedly reduced (P＜0.05). Combined knockdown of FABP5 and CPT1A further improved lipid abnormalities, inflammatory responses, and aortic root plaque lesions. Conclusions FABP5 may promote macrophage cholesterol accumulation and inflammatory cytokine expression by upregulating CPT1A, thereby contributing to As progression. The FABP5/CPT1A axis may serve as a potential target for intervention in lipid metabolism disorders and inflammatory responses in As.
