Loading…
IL-22–producing T cells can strongly and continuously activate enterocytes because they are located right next to them. However, it’s not exactly known how T cells help IECs or which epithelial cell groups are affected. It's also not clear why Citrobacter rodentium infection only happens in the mid to distal part of the large intestine.
There is a specific type of cell in the colon. These cells are only in the middle to end part of the colon. Citrobacter rodentium targets these cells. This explains why Citrobacter rodentium prefers this area. Interleukin-22 (IL-22) signalling turns on certain genes in these cells. These genes are different from those in other similar cells in the intestines. We also found that these cells help show antigens to T cells. This helps IL-22 signalling work well. The body's response to Citrobacter rodentium infection depends on where the pathogen and host are. It also depends on T cells helping these cells.
Interleukin-22 (IL-22) is produced by innate and adaptive immune cells. It is essential for host protection against Citrobacter rodentium.
Sonnenberg et al. 2011 Immunity 34:122–134
IL-22 acts on Enterocytes / Intestinal Epithelial Cells (IECs). It protects the epithelial barrier. Its production is restricted both spatially and temporally.
At the start of a Citrobacter rodentium infection, certain natural immune cells, especially type 3 innate lymphoid cells (ILC3), make IL-22. Later on, CD4 T cells, specifically T helper 17 (TH 17) and T helper 22 (TH 22), take over as the main producers of IL-22.
Sonnenberg et al. 2011 Immunity 34:122–134
In simple terms, if Interleukin-22 (IL-22) is missing in innate immune cells, it can be deadly early on in Citrobacter rodentium infection. On the other hand, if IL-22 is missing in CD4+ T helper cells, it can be deadly at a later stage.
Sonnenberg et al. 2011 Immunity 34:122–134
Different immune cells that produce IL-22 divide their work. Innate immune cells are good at stopping early Citrobacter rodentium colonization, but they are stuck in certain mucosal lymphoid tissues and mostly work from a distance
This makes them less effective as the infection gets worse. After some time, T helper 17 cell (Th17) and CD4+ Th22 Cells move into the distal colon. These cells are important because they provide IL-22, which is needed to keep the epithelial barrier strong and protect the crypts from pathogens.
Citrobacter rodentium is a Gram-negative murine enteropathogen. It is related to enterohaemorrhagic and enteropathogenic Escherichia coli. These bacteria form attaching and effacing (A/E) lesions on the apical surfaces of Enterocytes / Intestinal Epithelial Cells (IECs). They use type III secretion systems to deliver virulence proteins.
Citrobacter rodentium can adhere to the mucosa and then trigger T helper 17 cell (Th17) responses. Adhesion-defective mutants are not able to do this
The presence of EPS positive Bifidobacterium breve reduced colonization levels of the gut pathogen Citrobacter rodentium
see also:
Biological effects / Functions & Interleukin-22 (IL-22)
CD4+ Th22 Cells
Citrobacter rodentium & Group 3 ILCs
Enteropathogen / Gastroenteritis
Interleukin-22 (IL-22) & Intestinal Mucosal Barrier / Mucus Layer
Interleukin-22 (IL-22) production
Lymphoid Tissue Inducer Cells (LTi cells)
Type 3 immune response