Abstract:Objective To explore the effect of rhubarb combined with probiotics on immune function in patients with acute respiratory distress syndrome（ARDS） and study its mechanism. Methods A prospective multicenter randomized controlled clinical study was conducted on 90 ARDS patients admitted to the intensive care unit （ICU） in Affiliated Hospital of Jiangsu University, Jurong People's Hospital and Liyang Branch of Jiangsu Province Hospital from July 2020 to August 2021. They were randomly divided into control group, rhubarb treatment group and combination treatment group （30 cases in each group）, and were given routine treatment, routine + rhubarb enema treatment and routine + rhubarb enema + probiotics treatment, respectively. The changes in the serum level of inflammatory cytokines, immune function and intestinal flora were respectively detected by ELISA, flow cytometry and 16S rRNA sequencing technology among three groups. Results After 14 days of treatment, in combination treatment group, the serum interleukin-6（IL-6） and tumor necrosis factor-alpha（TNF-α） levels were significantly lower than those in control group and rhubarb treatment group （P＜0.05）,the peripheral blood lymphocyte counts and the monocyte-human leukocyte antigen-DR （mHLA-DR）expression level were significantly higher than those in control group and rhubarb group （P＜0.05）, while Treg expression level was significantly decreased （P＜0.05）. The diversity and structure of intestinal flora in combination treatment group were significantly improved and better than those in other two groups （P＜0.05）. Conclusion In the treatment of patients with ARDS,rhubarb combined with probiotics can significantly reduce the inflammatory response and improve the cellular immune function, which may be related to the improvement of intestinal flora structure.