Expression Of Regulatory B Cells And Related Cytokines In Peripheral Blood Of Children With Severe Pneumonia

BackgroundSevere pneumonia is a common respiratory disease in pediatrics and the main cause of death among hospitalized children in China.The pathological immune damage caused by the massive secretion of inflammatory cytokines and the breaking of the immune balance plays an important role in the disease process of severe pneumonia.Previous studies have shown that there are cytokine abnormalities in children with severe pneumonia.The serum levels of pro-inflammatory cytokines TNF-α and IL-17A are higher than those of healthy controls,and the levels of anti-inflammatory cytokine IL-10 fluctuate.The levels of these cytokines reflect the inflammatory state of the body and are closely related to the pathogenesis and prognosis of severe pneumonia.Regulatory B cells(Breg)are a newly discovered subgroup of B lymphocytes with negative regulation.They can mediate immune tolerance and inhibit excessive inflammation through the secretion of inhibitory cytokines or direct cell contact,and participate in immune regulation in a variety of diseases.Breg can regulate the levels of TNF-α and IL-17A by secreting IL-10 or up-regulating the ratio of regulatory T cells(Treg),however,it is not clear whether the changes of TNF-α,IL-17A and IL-10 levels in children with severe pneumonia are related to Breg,and how Breg expressed in children with severe pneumonia is still unclear.Therefore,analyzing the expression levels of Breg and its related cytokines in children with severe pneumonia is of great significance for further exploring the immune mechanism of children with severe pneumonia.ObjectiveDetermination of Breg ratio in children with severe pneumonia peripheral blood and related cytokines IL-10,the TNF-α,IL-17A level,and compare with children with common pneumonia and healthy control children to explore the expression differences of Breg in different severity of pneumonia and its correlation with IL-10,TNF-α,IL-17A cytokines,to explore the role of Breg and its mediated immune response in children with severe pneumonia.MethodsThis study included 30 children with severe pneumonia,30 children with common pneumonia,and 20 healthy control children.The children with pneumonia were scored by PCIS when they were admitted to the hospital,and 2ml of peripheral venous blood was collected within 24 hours and detected by flow cytometry.The ratio of CD19+CD24hiCD38hi B cells and the expression levels of IL-10,TNF-α,and IL-17A.Statistical analysis was performed using SPSS software to compare the proportion of Breg and the levels of IL-10,TNF-α,and IL-17A between the three groups,and analyze the proportion of Breg in children with severe pneumonia and common pneumonia,the number of days in hospital,PCIS score,The correlation of IL-10,TNF-α,IL-17A,and according to whether to receive mechanical ventilation,28-day treatment outcome and infectious pathogen grouping,compare the hospitalization time,PCIS score,Breg ratio,IL-10,TNF-α,IL-17A levels of children with severe pneumonia in different groups.Area under the curve(AUC),sensitivity and specificity were calculated to evaluate the accuracy of Breg ratio and PCIS score in evaluating the severity of pneumonia.Results(1)There were differences in the Breg ratio,IL-10,TNF-α,and IL-17A levels between children with severe pneumonia,children with common pneumonia,and healthy controls(P<0.05).Compared with children with common pneumonia and healthy control children,the Breg ratio in children with severe pneumonia was decreased,and the levels of IL-10,TNF-α,and IL-17A was increased(all P<0.05).Compared with healthy control children,children with common pneumonia had higher Breg ratio,IL-10,TNF-α,and IL-17A levels(all P<0.05).(2)The PCIS score of children with severe pneumonia when admitted to the hospital was lower than that of children with common pneumonia(P<0.05),and the length of stay in children with severe pneumonia was longer than that of children with common pneumonia(P<0.05).(3)The ratio of Breg in children with severe pneumonia was negatively correlated with hospitalization time,TNF-α and IL-17A levels(r=-0.370,r=-0.448,r=-0.390,all P<0.05),and it was correlated with PCIS The score is positively correlated(r=0.438,P<0.05).There was no significant correlation between the proportion of Breg in children with severe pneumonia and the level of IL-10(P>0.05).The proportion of Breg in children with common pneumonia was positively correlated with PCIS score and IL-10 level(r=0.411,r=0.468,P<0.05),and negatively correlated with TNF-α and IL-17A levels(r=-0.316,R=-0.551,all P<0.05).There was no significant correlation between the proportion of Breg in children with common pneumonia and the number of days in hospital(P>0.05).(4)The hospitalization time,TNF-α and IL-17A levels of children in the mechanical ventilation group were higher than those in the non-mechanical ventilation group(all P<0.05),and the PCIS score and the proportion of Breg were lower than those in the non-mechanical ventilation group(all P<0.05),and the difference of IL-10 level was no statistically significant between the two groups.(5)Among the 30 children with severe pn eumonia,2 cases died within 28 days.The Breg ratio and IL-10 level in these two children were lower than other children,and the levels of TNF-α and IL-17A were higher than other children,but the differences were not statistically significant(all P>0.05).(6)According to ROC curve analysis,the accuracy of the Breg ratio within 24 hours of admission to the hospital for predicting the severity of pneumonia was 0.8539(95%confidence interval:0.758-0.950),and the sensitivity of Breg ratio<7.8%for the diagnosis of severe pneumonia was 0.767 and the specificity was 0.833.The accuracy of PCIS score used to predict the severity of pneumonia at admission was 0.915(95%confidence interval:0.848-0.982),and the sensitivity of PCIS score<87 for diagnosing severe pneumonia was 0.93,and the specificity was 0.70.The PCIS score is more accurate in evaluating the severity of pneumonia than the Breg ratio.Conclusion(1)There were high levels of pro-inflammatory and anti-inflammatory reactions in children with severe pneumonia..(2)The ratio of CD19+CD24hiCD38hi B cells in children with common pneumonia was increased,which were positively correlated with the content of IL-10 and negatively correlated with the levels of TNF-α and IL-17A.The increased Breg exerted a negative regulatory effect and avoided excessive inflammatory reaction in the body.(3)Children with severe pneumonia had CD19+CD24hiCD38hi B cell immunodeficiency after severe infection,TNF-α,IL-10,IL-17A cytokine secretion disorder,and the ratio of peripheral blood CD19+CD24hiCD38hi B cells in children with severe pneumonia was positively correlated with PCIS scores.The ratio of CD19+CD24hiCD38hi B cells in children with more severe disease was lower.It was inferred that CD19+CD24hiCD38hi B cells may play a protective role in children with severe pneumonia.