Characteristics of Inflammatory Storm in BALF of Severe Pneumonia in Children

Abstract Background: There are few studies on inflammatory storms in bronchoalveolar lavage fluid (BALF) of children with pneumonia. Therefore, we will retrospectively investigate characteristics of inflammatory storms in BALF of children with pneumonia in our hospital.Methods: 161 children with pneumonia were retrospectively divided into two groups: mild and severe pneumonia, according to the clinic diagnosis. Flow cytometry was performed to detect the levels of cytokines, including IL-2, IL-4, IL-6, IL-10, IL-17A, TNF-α and IFN-γ. We performed receiver operator characteristic curve (ROC) and spearman correlation to evaluate the role of BALF inflammatory cytokines and cells in pneumonia.Results: 1) The levels of IL-6, IL-10, IL-17A, and TNF-α, and ratios of IL-6 to IL-10 and TNF-α to IL-10 in BALF of severe pneumonia group were higher than those of mild pneumonia group. 2) The number of inflammatory cells and the percentage of neutrophils in BALF of severe pneumonia group increased, and the percentage of macrophages decreased, compared with the mild pneumonia group. 3) ROC analysis showed that both the increase of the levels of IL-6, IL-10 and TNF-α, and ratios of IL-6 to IL-10 and TNF-α to IL-10, number of inflammatory cells and neutrophils, percentage of neutrophils, and the decrease of the percentage of macrophages exceeding the cut-off value could be used to distinguish children with severe pneumonia from mild pneumonia. Conclusion: In severe pediatric pneumonia, BALF inflammatory cytokines and inflammatory cell infiltration are more intense. And these inflammatory signals are important biomarkers for reflecting the severity of pediatric pneumonia.Trial registration: This study approved by the Medical Research Ethics Committee of Children’s Hospital of Chongqing Medical University, registered in http://www.chictr.org.cn/, No. ChiCTR2000034048(registration date, June 22, 2020).