In order to coexist peacefully, a “firewall” exists that keeps the commensal bacteria that reside in our intestines and associated lymphoid tissue contained. Several diseases and infections, however, lead to a breach in this barrier, which leads to chronic inflammation and pathology. Sonnenberg et al. found that in mice, innate lymphoid cells (ILCs) are critically important for the anatomical containment of commensal bacteria in an interleukin-22 (IL-22)–dependent manner. ILC depletion or blockade of IL-22 led to loss of bacterial containment and systemic inflammation.
G. F. Sonnenberg, L. A. Monticelli, T. Alenghat, T. C. Fung, N. A. Hutnick, J. Kunisawa, N. Shibata, S. Grunberg, R. Sinha, A. M. Zahm, M. R. Tardif, T. Sathaliyawala, M. Kubota, D. L. Farber, R. G. Collman, A. Shaked, L. A. Fouser, D. B. Weiner, P. A. Tessier, J. R. Friedman, H. Kiyono, F. D. Bushman, K.-M. Chang, D. Artis, Innate lymphoid cells promote anatomical containment of lymphoid-resident commensal bacteria. Science 336, 1321–1325 (2012). [Abstract] [Full Text]