Allicin Inhibits Keratinocytes Proliferation in HaCaT and psoriatic lesions
Sustained abnormal proliferation is the hallmark of keratinocytes in psoriatic lesions; thus, we investigated whether allicin inhibits the proliferation of keratinocytes in IMQ-induced psoriatic skin. HaCaT cells were treated with different concentrations of allicin (3.2, 6.4, 9.6, 12.8, 25.6, 51.2 μg/mL), and the cell viability was assessed by CCK8 assays after 48h (figure 3A). The effect of allicin treatment was concentration-dependent and significantly reduced cell viability. We next analyzed the influence of allicin on the cell distribution in the different cell cycle phases with flow cytometry. Allicin significantly decreased the HaCaT cell numbers in the G0/G1 phase, whereas the number of cells in the G2/M phase was increased compared with the control group (Figure 3B). The percentage of cells in the G2/M increased from 21.62% to 58.33%, indicating that allicin inhibited the proliferation of keratinocytes by inducing G2/M cell cycle arrest (Figure 3C). We used immunohistochemistry analysis to examine the expression of Ki67 in skin lesions, which is a marker expressed in proliferating cells. Figure 3D showed that the Ki67 expression of allicin-treatment was significantly fewer than with the IMQ-treated group. These results demonstrate that allicin reduced epidermal thickness by inhibiting keratinocyte hyperproliferation.