Human neutrophil peptides (HNPs) increase oxidative stress and foam cell formation. A and B, Surface expression of CD36 and CD68 on human acute monocytic leukemia cell line (THP-1) derived macrophages stimulated with HNPs or vehicle (V) control for 8 hours. C, Concentration of nitrotyrosine measured in human THP-1 derived macrophage lysates after HNP stimulation. n=5 experiments. D, Foam cell formation, quantified by Oil Red O (ORO) staining. Human macrophages were incubated with HNPs (10 μg/mL) in the presence of low-density lipoprotein (LDL) or oxidized LDL (oxLDL) for 16 hours. In additional experiments, superoxide dismutase (SOD) or anti-CD36 blocking antibody was added 30 minutes before the stimulation with HNPs. n=10 experiments. E, Representative cells with ORO staining in different groups described in D. F, Cholesterol efflux. ‡P<0.05 vs V, *P<0.05 vs LDL alone, †P<0.05 vs the LDL+HNP group.