Role of human β defensin 2 on preventing oxidized low-density lipoprotein induced monocyte foaming

Objective To clarify the role of human β-defensin2 (hBD2) on preventing oxidized low-density lipoprotein (OX-LDL) induced human leukemic monocyte (THP-1) foaming. Methods The monocyte foaming model was established using THP-1 cell induced by OX-LDL and the model was identified by oil red staining. The hBD2 was overexpressed on THP-1 cells by using lentivirus system and the effect of hBD2 overexpression on THP-1 cell foaming induced by OX-LDL was detected. The levels of inflammatory factors including tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 in cell supernatant of each group were detected by enzyme-linked immunosorbent assay (ELISA). Differences between the groups were compared by using the t test. Results The gene transfection efficiency of the cells was close to 100% at 72 h after infection. The hBD2 protein levels were 0.122±0.024 in the control group, 0.123±0.022 in Lv-control infection group and 0.981±0.183 in Lv-hBD2 infection group; and the level in control group was statistically higher than that in hBD-2 infection group (t=-3.175, P=0.007). The relative levels of hBD2 mRNA at 72 h after virus infection were 0.131±0.021 in control group, 0.128±0.022 in Lv-control group and 1.001±0.105 in Lv-hBD2 infection group; and the level in control group was statistically higher than that in hBD-2 infection group (t=-7.213, P=0.003). The results of oil red staining showed that OX-LDL inducing THP-1 cells for 72 h could significantly induce lipid accumulation in cells. Overexpression of hBD2 could effectively inhibit lipid accumulation in THP-1 cells induced by OX-LDL. The expression of hBD2 mRNA in THP-1 group was significantly higher than that in THP-1+ OX-LDL group (t=3.237, P=0.004); and the difference was also significant when comparing THP-1+ Lv-hBD2+ OX-LDL group with THP-1+ OX-LDL group (t=-6.021, P=0.003). The level of hBD2 protein in THP-1 group was significantly higher than that in THP-1+ OX-LDL group (t=0.314, P=0.006); and the difference was also significant when comparing THP-1+ Lv-hBD2+ OX-LDL group with THP-1+ OX-LDL group (t=-4.061, P=0.007). The levels of TNF-α, IL-1β and IL-6 in the supernatant of THP-1 cells induced by OX-LDL for 72 h were significantly increased compared with those in THP-1group (t=-3.825, -2.017 and -3.551, respectively; P=0.007, 0.004 and 0.005, respectively). The levels of TNF-α, IL-1β and IL-6 in THP-1+ Lv-hBD2+ OX-LDL group were significantly lower than those in THP-1+ OX-LDL group (t=4.132, 3.681, and 2.991, respectively; P=0.003, 0.002, and 0.007, respectively). Conclusions hBD2 can effectively inhibit THP-1 foaming induced by OX-LDL, which may be related to its inhibition of inflammatory response. Key words: Human β-defensin-2; THP-1; Monocytes foam; OX-LDL