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Open Access Highly Accessed Research

Interleukin-7 receptor blockade suppresses adaptive and innate inflammatory responses in experimental colitis

Cynthia R Willis1*, Audrey Seamons2, Joe Maxwell1, Piper M Treuting2, Laurel Nelson1, Guang Chen1, Susan Phelps2, Carole L Smith1, Thea Brabb2, Brian M Iritani23 and Lillian Maggio-Price2

Author Affiliations

1 Department of Inflammation, Amgen, Inc, Seattle, WA, USA

2 Department of Comparative Medicine, University of Washington, Seattle, WA, USA

3 Fred Hutchinson Cancer Research Center, Seattle, WA, USA

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Journal of Inflammation 2012, 9:39  doi:10.1186/1476-9255-9-39

Published: 12 October 2012

Abstract

Background

Interleukin-7 (IL-7) acts primarily on T cells to promote their differentiation, survival, and homeostasis. Under disease conditions, IL-7 mediates inflammation through several mechanisms and cell types. In humans, IL-7 and its receptor (IL-7R) are increased in diseases characterized by inflammation such as atherosclerosis, rheumatoid arthritis, psoriasis, multiple sclerosis, and inflammatory bowel disease. In mice, overexpression of IL-7 results in chronic colitis, and T-cell adoptive transfer studies suggest that memory T cells expressing high amounts of IL-7R drive colitis and are maintained and expanded with IL-7. The studies presented here were undertaken to better understand the contribution of IL-7R in inflammatory bowel disease in which colitis was induced with a bacterial trigger rather than with adoptive transfer.

Methods

We examined the contribution of IL-7R on inflammation and disease development in two models of experimental colitis: Helicobacter bilis (Hb)-induced colitis in immune-sufficient Mdr1a−/− mice and in T- and B-cell-deficient Rag2−/− mice. We used pharmacological blockade of IL-7R to understand the mechanisms involved in IL-7R-mediated inflammatory bowel disease by analyzing immune cell profiles, circulating and colon proteins, and colon gene expression.

Results

Treatment of mice with an anti-IL-7R antibody was effective in reducing colitis in Hb-infected Mdr1a−/− mice by reducing T-cell numbers as well as T-cell function. Down regulation of the innate immune response was also detected in Hb-infected Mdr1a−/− mice treated with an anti-IL-7R antibody. In Rag2−/− mice where colitis was triggered by Hb-infection, treatment with an anti-IL-7R antibody controlled innate inflammatory responses by reducing macrophage and dendritic cell numbers and their activity.

Conclusions

Results from our studies showed that inhibition of IL-7R successfully ameliorated inflammation and disease development in Hb-infected mice by controlling the expansion of multiple leukocyte populations, as well as the activity of these immune cells. Our findings demonstrate an important function of IL-7R-driven immunity in experimental colitis and indicate that the therapeutic efficacy of IL-7R blockade involves affecting both adaptive and innate immunity.

Keywords:
IL-7R; Colitis; Mdr1a−/− mice; Rag2−/− mice; Helicobacter bilis