Calcitriol decreases live Porphyromonas gingivalisinternalized into epithelial cells and monocytes by promoting autophagy

The present study aimed to explore the effects of the active form of vitamin D (calcitriol, 1α,25‐dihydroxyvitamin D3, 1α,25 (OH)2D3, 1,25D) on live Porphyromonas gingivalisinternalized into KB cells and U937 cells. Quantitative real‐time polymerase chain reaction method was used to evaluate the number of surviving P. gingivalisinternalized into KB cells and U937 cells. Transmission electron microscopy was used to detect P. gingivalisin cells. A western blot analysis was performed to observe LC3 expressions. 1) Treatment with 1,25D decreased the number of live P. gingivalisin KB cells and U937 cells in a dose‐dependent manner. 2) Dividing P. gingivaliswere found only in KB cells but not in U937 cells. The cell walls of most P. gingivalisin KB cells were intact, while those in U937 cells were disrupted. Treatment with 1,25D promoted the encapsulation of P. gingivalisin autophagosomes in both KB and U937 cells. 3) Both 1,25D treatment and P. gingivalisinfection increased the LC3 II/I ratio. Furthermore, 1,25D treatment increased the P. gingivalis‐upregulated LC3 II/I ratio. 4) Treatment with 3‐methyladenine (3‐MA) decreased the number of P. gingivalisby 11.41% in KB cells, while increased that by 121.51% in U937 cells. Under 1,25D treatment conditions, 3‐MA treatment increased the number of P. gingivalisby 88.71% in KB cells and by 284.70% in U937 cells. Autophagy may facilitate P. gingivalissurvival in KB cells and eliminate P. gingivalisin U937 cells. Treatment with 1,25D may help decrease the number of live P. gingivalisin KB cells and U937 cells by promoting functional autophagy.