Abstract: Objective To determine the role of inlerleukin-18 (IL-18) and nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) in acne vulgaris. Methods We used propionibacterium acnes (P.acnes） suspensions 〔multiplicity of infection (MOI)=0,10,20,30〕 to stimulate normal human epidermal kerationocytes (NHEKs) for 12, 24, and 36 h, respectively. Enzyme-linked immunosorbent assay (ELISA) was performed to detect the protein level of IL-18. Real-time quantitative PCR (real-time PCR) was adopted to detect the mRNA of IL-18.The NHEKs were divided into three groups: ① siRNA group: NHEKs were pretreated with siRNA for 36 h, followed by 36 h exposure to MOI=30 of P.ances suspensions; ② blank control group: NHEKs free from siRNA transfection and P.ances suspensions; ③ positive control group: NHEKs free from siRNA transfection were exposed to P.ances suspensions (MOI=30).The expression of NLRP3 was detected by Western blot. Results The expressions of protein and mRNA of IL-18 increased with exposure to P.ances suspensions in a dose responsive way (r＞0.75， P<0.05), with the peak effects showing for MOI=30 at 36 h. The expression of IL-18 decreased in the siRNA group compared with the positive control, but was still higher than that of the blank group( P<0.05). Conclusion P.ances stimulates NHEK cells to secrete IL-18. The process possibly requires the involvement of NLRP3.