Objective:To explore the effect of lipoxygenase 15B(ALOX15B)on the transformation of Ana-1 macrophages into foam cells and its mechanism.Methods:12 patients with atherosclerosis were selected as the research subjects.The relationship be-tween the level of ALOX15B and pathological features was analyzed by Oil Red O staining and immunohistochemical methods.shRNA and CRISPR/Cas9 techniques were used to construct ALOX15B down-regulated cells(shALOX15B)and ALOX15B up-regulated cells(oeALOX15B),respectively.Foam cells were obtained by treating macrophages with oxidized low-density lipoproteins.The Oil Red O staining was used to detect the intracellular lipid accumulation.Western blot was used to detect the protein levels of ALOX15B and HIF-1α.The mRNA levels of inflammatory factors NF-κB,IL-1β,IL-6 and IL-10 were analyzed by RT-qPCR.Results:Atherosclerotic plaques were formed by the accumulation of foam cells.ALOX15B expression was decreased in atherosclerotic plaque compared with normal blood vessels.Oil Red O staining revealed that ALOX15B deficiency significantly increased lipid accumulation in macrophages.Compared with the shRen group,the expression of HIF-1α protein and the mRNA levels of pro-inflammatory factors NF-κB,IL-1 β and IL-6 in shALOX15B cells were significantly increased,while the IL-10 was significantly decreased.ALOX15B upregulation can reverse the changes caused by ALOX15B deficiency.Hypoxic treatment of oeALOX15B cells could reverse the abnormally changed levels of HIF-1α and inflammatory factors NF-κB,IL-1 β,IL-6,and IL-10.Conclusion:ALOX15 B is abnormally low expressed in atherosclerotic tissues.ALOX15B may affect the transformation of macrophages into foam cells by regulating HIF-1α.