Correlation Between Changes Of Serum Cytokines And Intestinal Microbiota In Premature Infants With Respiratory Distress Syndrome

ObjectiveTo explore the correlation between serum cytokines and intestinal microbiota in premature infants with respiratory distress syndrome.Methods1.A prospective cohort study consisting of 43 premature infants hospitalized in the neonatal intensive care unit of the Affiliated Hospital of Qingdao University from September 2021 to February 2023,with a gestational age of 30 to 34 weeks,diagnosed as respiratory distress syndrome(RDS).And 39 premature infants without RDS of the same gestational age at the same time as the control group.Basic data of the infants and their mothers were recorded.Peripheral venous blood samples were collected within 24 hours after birth and 7 days after birth for the detection of cytokines IL-6,IL-8,IL-10,IL-17,TNF-α,IFN-γ,neutrophil counts and Ig G levels.2.Among the premature infants included in the first part,excluding those who had a normal birth,whose mothers or newborns used probiotic,and who could not take stool samples on time,10 premature infants with RDS and 10 premature infants without RDS were finally included.Basic data of the infants and their mothers were recorded,and 60 fecal samples were collected within 24 hours,1 week and 2 weeks after birth of the two groups of premature infants.The diversity of intestinal microbiota in the fecal samples was detected.Results1.1 Within 24 hours after birth,there were no statistical differences in cytokines IL-6,IL-8,IL-10,IL-17,TNF-α,IFN-γ,neutrophil counts and Ig G levels between the RDS group and the control group(P>0.05).1.2 On the 7th day after birth,the levels of IL-6 in premature infants with RDS were higher than those in the control group,while the levels of IL-10 were lower than those in the control group(P<0.05).However,there were no statistical differences in IL-8,IL-17,TNF-α,IFN-γ,neutrophil counts and Ig G levels between the two groups(P>0.05).2.1 The rarefaction curve tended to be flat,indicating that no large number of new species would appear when the sequencing volume was increased,and the sequencing depth basically covered all species in the samples.The species accumulation curve tended to be flat,indicating that no large number of new species would appear when the number of samples was increased,and the current number of samples met the analysis requirements.2.2 The alpha diversity index and the rarefaction curve showed that the intestinal microbial richness of premature infants in the RDS group was higher than that in the control group within 24 hours,1 week,and 2 weeks after birth.However,only at 2 weeks after birth,there was a statistical difference in intestinal microbial richness between the two groups(P<0.05).There was no statistical differences in the diversity of intestinal microbiota between the two groups of premature infants within 24 hours,1 week,and 2weeks after birth(P>0.05).2.3 The species distribution bar chart showed that the intestinal microbiota of the two groups at different times were mainly composed of Firmicutes,Proteobacteria,and Actinobacteriota at the phylum level.With the growth of premature infants,the relative abundance of Firmicutes in the control group gradually increased,while the relative abundance of Firmicutes increased first and then decreased in the RDS group.However,the relative abundance of Firmicutes in the RDS group was always higher than that in the control group,and the relative abundance of Proteobacteria was always lower than that in the control group.At the genus level,with the growth of preterm infants,Clostridium＿sensu＿stricto＿1,Enterococcus,Escherichia＿Shigella and unclassyfied＿Enterobacteriaceae developed into dominant bacteria in the two groups.Moreover,the relative abundance of Clostridium＿sensu＿stricto＿1 in the RDS group was always higher than that in the control group,while the relative abundance of Escherichia＿Shigella was always lower than that in the control group.2.4 Beta diversity analysis showed that there were statistical differences in the intestinal microbiota between the RDS group and the control group within 24 hours,1 week,and 2 weeks after birth(P<0.05).LEf Se analysis showed that within 24 hours after birth,microorganisms such as p＿Firmicutes,c＿Clostridia,o＿Clostridiales,f＿Clostridiaceae and g＿Clostridium＿sensus＿stricto＿1 were enriched in the RDS group,while microorganisms such as c＿Gammaproteobacteria,o＿Enterobacterales and f＿Enterobacteriaceae were enriched in the control group.At 1 week after birth,microorganisms such as o＿Lachnospirales and f＿Lachnospiraceae were enriched in the RDS group.At 2 weeks after birth,in addition to the enrichment of o＿Lachnospirales and f＿Lachnospiraceae in the RDS group,microorganisms such as p＿Bacteroidota,c＿Bacteroidia and o＿Bacteroidales were also enriched in the RDS group.Combined with the species distribution bar chart,it was found that the relative abundance of Bacteroidota in the two groups decreased gradually in the first 2 weeks after birth.However,the relative abundance of Bacteroidota in the RDS group changed less than that in the control group.Conclusion1.On the 7th day after birth,the level of IL-6 in the RDS group was higher than that in the control group,while the level of IL-10 was lower than that in the control group.The premature infants with RDS developed postnatal inflammatory reactions.2.In a certain range,the increase of the relative abundance of Firmicutes in the RDS group was conducive to reducing the inflammatory response,and the change in the relative abundance of Proteobacteria was helpful to maintain the balance between inflammatory and anti-inflammatory responses.3.Bacteroidota may play a protective role in lung injury caused by RDS.4.The inflammatory response in preterm infants with RDS can lead to the disorder of intestinal microbiota.The disorder of intestinal microbiota can also affect the inflammatory response.There is a significant relationship between inflammatory response and intestinal microbiota disorder in preterm infants with RDS.