TCHH and inflammatory bowel disease: In a study of sterile mice, when the numbers of intestinal Thl and Thl7 decreased, the intestinal immune response was controlled by Th2, while this imbalance of Thl/Th2 could be improved through the colonization of Bacteroides fragilis, indicating that intestinal microbiome colonization plays an important role in regulating imbalance in the immune response of T cells, thus mitigating the onset of IBD [147].