Abstract:

Objective: To investigate the role of oleic acid (OA) in the clearance of Mycobacterium tuberculosis (MTB) by macrophages and explore the underlying mechanisms. Methods: Macrophages induced from the human monocyte leukemia cell line (THP-1) were infected with the standard MTB strain H37Ra with or without oleic acid. The effect of oleic acid on the clearance of MTB by macrophages was assessed using colony-forming unit (CFU). Key target genes were identified through RNA-seq, and relevant pathways were determined using gene enrichment analysis. Real-time quantitative PCR was used for validating gene expression. Results: After 72 hours of infection with H37Ra, the CFU for macrophages (H37Ra group) was 49×10⁴ (48×10⁴, 59×10⁴), significantly higher than that of macrophages induced with oleic acid (OA+H37Ra group) at 34×10⁴ (30×10⁴, 42×10⁴) (U=3.500, P=0.017). RNA-seq data showed that the expression of recombinant perilipin 2 (PLIN2) in the OA+H37Ra group was significantly higher than in the H37Ra group. In oleic acid-induced macrophages, the CFU in the PLIN2 knock down group was 86×10⁴ (78×10⁴, 96×10⁴), significantly higher than that in the control group (56×10⁴ (54×10⁴, 62×10⁴); U=3.000, P=0.015). In the OA+H37Ra group, the relative expression of PLIN2 was 3.219±0.298, significantly higher than the 0.555±0.028 in the H37Ra group (t=15.410, P<0.01). The relative expression of PPARγ in the OA+H37Ra group was 0.666±0.075, significantly lower than the 2.217±0.153 in the H37Ra group (t=14.700, P<0.01). In the OA+H37Ra group, the relative expression of ACOX1 and HADHA was 1.410±0.124 and 1.107±0.111, both significantly lower than the H37Ra group of 2.476±0.207 and 3.140±0.240 (t=13.520, P<0.01; t=12.760, P<0.01) respectively. Conclusion: Oleic acid regulates fatty acid oxidation in macrophages through the lipid droplet surface protein PLIN2, promoting the clearance of MTB by macrophages.

Key words: Mycobacterium tuberculosis, Macrophages, Oleic acid, Perilipin, Gene expression regulation, bacterial