Interleukin 13 - Clinical Significance

Clinical Significance

IL-13 specifically induces physiological changes in parasitized organs that are required to expel the offending organisms or their products. For example, expulsion from the gut of a variety of mouse helminths requires IL-13 secreted by Th2 cells. IL-13 induces several changes in the gut that create an environment hostile to the parasite, including enhanced contractions and glycoprotein hyper-secretion from gut epithelial cells, that ultimately lead to detachment of the organism from the gut wall and their removal.

The eggs of the parasite Schistosoma mansoni may lodge in a variety of organs including the gut wall, liver, lung and even central nervous system, inducing the formation of granulomas under the control of IL-13. Here, however, the eventual result is organ damage and often profound or even fatal disease, not resolution of the infection. An emerging concept is that IL-13 may antagonize Th1 responses that are required to resolve intracellular infections. In this immune dysregulated context, marked by the recruitment of aberrantly large numbers of Th2 cells, IL-13 inhibits the ability of host immune cells to destroy intracellular pathogens.

IL-13 induces many features of allergic lung disease, including airway hyperresponsiveness, goblet cell metaplasia and mucus hypersecretion, which all contribute to airway obstruction. IL-4 contributes to these physiologic changes, but is less important than IL-13. IL-13 also induces secretion of chemokines that are required for recruitment of allergic effector cells to the lung. Studies of STAT6 transgenic mice suggest the interesting possibility that IL-13 signaling occurring only through the airway epithelium is required for most of these effects. While no studies have yet directly implicated IL-13 in the control of human diseases, many polymorphisms in the IL-13 gene have been shown to confer an enhanced risk of atopic respiratory diseases such as asthma.