Formation of tertiary lymphoid tissue in dextran sulfate sodium induced
colitis is partially dependant on LT1 2-LTR axis
B.J. Olivier1, M. Knippenberg1, M.J. Greuter1, G. Goverse1, E.D. Keuning1, A.A.
te Velde2, G.Bouma3 and R.E. Mebius1.
1 Department
of Molecular Cell Biology and Immunology, Vrije Universiteit Medical Center,
Amsterdam, The Netherlands. 2 Tytgat Institute for Liver and Intestinal Research, Academic
Medical Center, Amsterdam, The Netherlands. 3 Department of Gastroenterology, Vrije
Universiteit Medical Center, Amsterdam, The Netherlands.
Patients with inflammatory bowel disease (IBD) suffer from chronic inflammation
of the intestine, which may lead to the formation of lymphoid aggregates that
closely resemble secondary lymphoid tissue. The formation of secondary
lymphoid tissue is dependent on the lymphotoxin alpha1 beta2 - lymphotoxin
beta receptor signaling axis. Hematopoietic lymphoid tissue inducer (LTi) cells
express lymphotoxin alpha1 beta2 (LT12) which binds to the lymphotoxin beta
receptor (LTR) expressed on stromal organizers cells, and leads to the
induction of chemokines (CXCL13 and CCL21) and adhesion molecules (VCAM1, ICAM and MAdCAM-1). These molecules serve to attract and retain additional
hematopoietic cells leading to the formation of secondary lymphoid tissue. Here
we show, using dextran sulfate sodium (DSS) induced colitis, that stromal cells in
the acute inflammatory setting have the ability to upregulate LTR expression
along with CXCL13, CCL21, VCAM-1 and MAdCAM-1. In the more chronic
setting tertiary lymphoid tissues were detected in inflamed colons and consisted
of tightly clustered B cell follicles with distinct T cell areas. Surprisingly, these
structures could also be found at the chronic phase of DSS colitis in LT-/- mice,
although the B cell areas were devoid of follicular dendritic cells (FDCs) and
germinal centers (GCs). These results show that lamina propria stromal cells
become activated upon damage to the epithelial barrier and function as organizer
cells to locally form lymphoid tissue. This process is only partially dependent on
the LT12-LTR axis and must involve alternate pathways.