Inhibition of macrophage signaling pathway by bone marrow mesenchymal stem cells (BMSC) and alleviation of pulmonary alveolitis in mice exposed to silica dust / 上海预防医学

ABSTRACT

Objective To study the mechanism of bone marrow mesenchymal stem cell (BMSC)-mediated alleviation of pulmonary alveolitis in mice exposed to silica dust. Methods Thirty mice were randomly divided into 3 groupscontrol group, and two silica groups with or without BMSCs transplantation.Through the tracheal tube clearance, mice in control group received a single injection 20.0 μL of 0.90% sodium chloride solution by one time.Mice from in silica group and silica/BMSCs transplantation group first received a single injection of 20.0 μL silica dust suspension (mass concentration 250 g/L); followed by either 500.0 μL of 0.90% sodium chloride solution or by 500.0 μL of BMSCs suspension (cell density 1×109/L) through tail vein infusion 6 hours later.Mice were euthanized on the 3th day of the experiments.The levels of NALP3 inflammasome in lungs was determined by Western blot.Transwell system was used for co-culture of BMDM (in upper-chamber) and BMSC (in lower-chamber) co-culture.The level of cytokines IL-1β in BMDM cultural supernatant was detected by enzyme linked immunosorbent assay after stimulated by SiO2 stimulation.The levels of NALP3 inflammasome of in BMDM was determined by Western blot. Results The levels of pro-IL-1β, IL-1β, pro-caspase-1, caspase-1 in lungs of silica/BMSCs transplantation group were lower than that in silica group (P < 0.01).In the experiment in vitro, the concentrations of IL-1β in SiO2 exposed BMSC/BMDM co-culture group were lower than the SiO2 exposure only groups (P < 0.05).Meanwhile, the levels of pro-IL-1β, IL-1β, pro-caspase-1, caspase-1 in BMDM was lower than that in silica group (P < 0.01).The level of these proteins didn′t change while when the cell-free supernatant of BMSC culture was directly added. Conclusion The BMSC could inhibit NALP3 inflammasome of macrophages stimulated by SiO2.