Clinically relevant positive controls validate the use of serial FACS analysis, and video endoscopy in two murine adoptive transfer models of colitis (HUM1P.315)

Abstract

Abstract The adoptive transfer of naïve TH cells into immunodeficient mice is one of the best characterized immunological models of chronic colitis (CC). Traditional disease severity endpoints of weight loss and histopathology are often misleading since colitis may occur in the absence of weight loss, mice may not engraft, and weight loss and colitis may respond independently to established or experimental treatment. To overcome these limitations, we analyzed peripheral blood to track engraftment, and performed serial endoscopies to assess onset and severity of CC in two murine models of adoptive transfer-induced colitis: naive T cells from C57Bl/6J males sorted as either CD4+, CD45RBHIGH (FACS), or CD4+, CD44-, CD62L+ (negative magnetic separation) were injected IP into RAG2-/- males. Onset of colitis corresponded with the onset of weight loss, and day 14 peripheral blood CD4+ counts correlated well with both final weight loss (R2=0.74) and final endoscopy score (R2=0.79), indicating that day 14 CD4+ count was a reliable predictor of disease severity. Treatment with anti-TNFα had little effect on terminal weight loss, but significantly affected endoscopy score (2.0±0.15 vs. 1.1±0.14 at day 49 on a scale of 0-3). Together these observations suggest that endoscopy is a useful addition to weight change as a complete readout for assessing in-life disease severity in these models.