Fig. 4: The immune environment of the intestinal wall from balance to disease.

The structural status of the intestinal barrier affects the tendency of immune cells to release cytokines (represented in blue) that stimulate transcription factors (pink boxes) and signalling pathways, causing the activation of inflammatory stimuli and cellular components (purple boxes). These are not just a mere consequence but could also represent a trigger of the inflammatory cascade hereby represented, which depicts the difficulty of untangling this process. When the intestinal barrier is healthy and selectively permeable, tolerant signalling takes place. Transient or persistent gaps in the barrier promote either resolutive or detrimental inflammation. Created with BioRender.com.