Increased NCR negative ILC 3 may be indicative for the early development of spontaneous colitis in the IL 10 knockout mouse

Abstract

Abstract The IL10 knockout (KO) mouse is a model for environmentally and genetically triggered spontaneous colitis. The response of the adaptive immune system to these changes has been studied extensively in this model. However, the response of the innate immune system, specifically the response of innate lymphoid cell (ILCs) populations to the genetic background of the mouse and the environmental stimulus of introducing microbiota has not been well studied. Herein, we evaluated the response of ILCs and Lin marker positive lymphocytes to changes in genotype (wild type Mice B6 in SPF to IL10 KO B6 mice in SPF) and also compared IL10KO mice who were either germ free or SPF exposed. To accomplish this, IL10 knockout mice were exposed to SPF conditions for three weeks. LPMCs were isolated from the colon and small bowel. Innate lymphoid cells were identified as Lin− CD90.2+CD127+cells, and within total ILC, ILC2s were ST2+ cells, ILC1s were ST2−CD117− cells, and ILC3s were ST2−CD117+NKp46+/−cells. As expected, we saw a less developed adaptive immune response in GF IL10 KO mice, with up regulation in this compartment following SPF exposure (Lin+ population increase 1.87 fold). Upon comparison of WT SPF versus IL10 KO SPF, we observed a 5 fold increase in total ILCs and an 18% increase in NCR-ILC3 in the SPF. Comparison of IL10 KO GF versus SPF revealed a 1.8 fold increase in total ILC and a 3% increase in NCR-ILC3s. In conclusion, we show that both genetic and environmental factors play a role in the innate immune changes that occur prior to the development of spontaneous colitis in the IL10 KO mouse and that the shift towards NCR-ILC 3 maybe an early marker for the development of spontaneous colitis.