PD-1/PD-L1 Inhibitors Exert Anti-apoptosis And Anti-inflammatory Activity In LPS-stimulated Murine Alveolar Macrophages

Objective:Sepsis is a life-threatening organ dysfunction syndrome caused by dysregulation of the body’s response to infection,and the lung is the main target organ for sepsis.The ALI and ARDS caused by the development of sepsis disease have no special therapeutic drugs so far,and the mortality rate is extremely high.Therefore,the main purpose of this experimental study is to determine whether PD-1 / PD-L1 inhibitors can reduce the apoptosis of alveolar macrophages,restore the immune function of alveolar macrophages,and improve the ability to remove bacteria.On the other hand,it is clear whether PD-1 /PD-L1 inhibitors can reduce the release of inflammatory factors of alveolar macrophages,thereby reducing the inflammation and extenuate lung tissue damage,and play a role in lung protection.Methods:Murine alveolar macrophages,MH-S,were cultured in sterile 6-well plates and divided into control,LPS and LPS + BMS-1 groups.Lipopolysaccharide(LPS)(10ng/mL)was added to the LPS and LPS + BMS-1 groups for 24 h,and PD-1/PD-L1 inhibitors BMS-1(1 μM)were added to the LPS + BMS-1 group for 72 h.PD-1 mRNA expression was detected by RT-PCR.PD-1 protein expression was detected by Western blot.MH-S apoptosis was detected by flow cytometry.The level of inflammatory factors IL-1β,IL-6,TNF-α,and IL-10 were detected by ELISA.Results:Murine alveolar macrophages expressed PD-1 at both the molecular and protein levels,and PD-1 expression was increased in MH-S cells stimulated with LPS.Compared with the LPS group,the expression of PD-1 in the LPS + BMS-1 group was significantly decreased.Flow cytometry showed that there was increased apoptosis of alveolar macrophages in the LPS group,compared to remarkably reduced apoptosis in the LPS + BMS-1 group.IL-1β,IL-6,and TNF-α were significantly increased in the LPS group,and IL-10 was relatively low.The level of IL-1β,IL-6 and TNF-α in the LPS +BMS-1 group was lower than those in the LPS group,and IL-10 was increased.Conclusion:In vitro,PD-1/PD-L1 inhibitors reduced alveolar macrophage apoptosis compared to the LPS group to maintain effective immune clearance and reduce inflammatory factor release.This decreases the inflammatory response,reducing acute lung injury caused by sepsis and play a role in lung protection.Therefore,PD-1/PD-L1 inhibitors may represent a potential therapeutic target for acute lung injury in sepsis.