Published online Nov 7, 2014. doi: 10.3748/wjg.v20.i41.15216
Revised: March 18, 2014
Accepted: June 14, 2014
Published online: November 7, 2014
The small and large intestine of the gastrointestinal tract (GIT) have evolved to have discrete functions with distinct anatomies and immune cell composition. The importance of these differences is underlined when considering that different pathogens have uniquely adapted to live in each region of the gut. Furthermore, different regions of the GIT are also associated with differences in susceptibility to diseases such as cancer and chronic inflammation. The large and small intestine, given their anatomical and functional differences, should be seen as two separate immunological sites. However, this distinction is often ignored with findings from one area of the GIT being inappropriately extrapolated to the other. Focussing largely on the murine small and large intestine, this review addresses the literature relating to the immunology and biology of the two sites, drawing comparisons between them and clarifying similarities and differences. We also highlight the gaps in our understanding and where further research is needed.
Core tip: The small and large intestine of the gastrointestinal tract (GIT) have evolved to have different functions and have a distinct anatomy, biology and immunology. Despite this, findings from the small intestine are often inappropriately attributed to large intestine and vice versa. The importance of these biological differences is underlined when considering that different regions of the GIT are associated with different infections and pathologies. This review addresses the literature relating to the small and large intestine – clarifying the similarities and differences between the two sites. We also highlight the gaps in our understanding where further research is needed.