By comparing the differences, it was concluded that lung inflammation in children with pneumonia is not caused by the destruction of lung bacteria but by the decrease in intestinal Tight junction expression caused by the disorder of intestinal bacteria, which causes the entry of pathogenic enteroglobulin phosphoteichoic acid (LE-LTA) into the lungs to activate ILC-3 cells, resulting in high expression of IL-17 and IL-22, leading to pneumonia. This evidence concerns the gene IL17A and susceptibility to pneumonia measurement.