Endoscopic Photoconversion Reveals Unexpectedly Broad Leukocyte Trafficking to and from the Gut

Morton AM, Sefik E, Upadhyay R, Weissleder R, Benoist C, Mathis D.

Proc Natl Acad Sci U S A. 2014 May 6;111(18):6696-701. doi: 10.1073/pnas.1405634111. Epub 2014 Apr 21.

Pictured Above: Angela (Morton) Magnuson, PhD

Pictured above: Angela (Morton) Magnuson, PhD

Gut-microbiota/immune-cell interactions play important roles in immune system homeostasis and responsiveness, and have been implicated in the onset and development of autoimmune and autoinflammatory disease. Yet, surprisingly little is known about the movement of immune cells into and, particularly, out of the gut. We used a minimally invasive system (in transgenic mice where all cells express Kaede, a fluorescent protein that changes color from green to red upon exposure to violet light) to monitor immigration of diverse innate and adaptive immune-cell types to the intestine from a distant lymph node, and a novel endoscopic adaptation of the system to follow their emigration from the distal colon to nearby and distal lymphoid organs. We uncovered an unexpectedly broad movement of leukocytes to and from the gut at steady state, as well as subset-specific migration proclivities. Moreover, we evidenced a critical cellular link between an intestinal microbe, segmented filamentous bacteria, and an extraintestinal autoinflammatory disease, the K/BxN model of arthritis.                                                                                                       PubMed:24753589