Intestinal epithelial cells are in constant contact with the ever-present commensal flora. This leaves them with a complex task of maintaining a fine balance between tolerating the microbiota and being ready to respond to invading pathogens. Intestinal cells are polarized with an apical side facing the lumen of the gut and a basolateral side facing the sterile lamina propria. Our work has uncovered that one method used by human intestinal epithelial cells (hIECs) to avoid over stimulation is that they polarize the pathogen-recognition receptor TLR‑3 to the basolateral side of hIECs to avoid over detection of the commensal bacteria. Our group continues to investigate the molecular mechanisms used by hIECs to maintain immune-homeostasis and how these mechanisms are mis-regulated in patients with inflammatory bowel disease by employing organoid cultures, live-cell imaging, and single cell sequencing. Additionally, we are now extending our observations in hIECs to additional mucosal tissues (e.g. the lung and genital tract) to determine if all tissues that act as a protect barrier use similar mechanisms to detect and fight invading pathogens while tolerating the presence of the commensal flora.