Intestinal mast cell progenitors function as innate lymphoid cells (P497) (71.3)

Small intestinal innate lymphoid cells (mainly NKp46+ILCs) are known to have a protective role from infection of pathogenic bacteria through the production of IL-22. The proportions of ILCs localized intestinal lamina propria are higher than those in the others lymphoid tissues, such as mesenteric lymph node, spleen, liver, and bone marrow. In this study, we did a microarray experiment to study whether small intestinal ILCs (Lin-c-Kit+Sca-1- cells) highly express which genes as compared with non-ILCs (Lin-c-Kit-Sca-1- cells). We selected 251 up-regulated genes and 219 down-regulated genes in Lin-c-Kit+Sca-1- cells. Especially, Lin-c-Kit+Sca-1- cells highly expressed genes coding to Il22, Csf2rb2, mast cell proteases (Mcpts), and Rorc. To address whether which ILC populations are main source of IL-22, we more detailed divided Lin-c-Kit+Sca-1- cells into the two groups [Lin-c-Kit+NKp46+ (NKp46+ILCs) and Lin-c-Kit+NKp46-CD4-]. Only Lin-c-Kit+NKp46-CD4- cells expressed Csf2rb2 and Mcpts transcripts. These cells expressed higher level of Il22 mRNA, IL-22 protein, and IL-17F protein in physiological condition and in IL-23 stimulated condition compared with NKp46+ILCs. Moreover, these cells could differentiate into mast cells in the presence of mIL-3 and mSCF. Taken together, Lin-c-Kit+NKp46-CD4- cells as mast cell progenitors may regulate small intestinal homeostasis through the production of Mcpts, IL-17F, and IL-22 in physiological condition and in pathophysiological condition.