Interleukin-6 and its receptor are expressed in human intestinal epithelial cells

Recent studies have suggested that intestinal epithelial cells demonstrate some of the functions associated with immune competent cells. Based on these observations, we investigated whether gastrointestinal epithelial cells express Interleukin-6 (IL-6). The presence of this cytokine was tested in 53 normal and pathological tissue specimens of the human gastrointestinal tract using an immunohistochemical technique with anti-IL-6 monoclonal and polyclonal antibodies. Immunostaining shows that IL-6 is expressed in gastric and small intestinal epithelial cells. The tumor cells from a large subset (11 of 15) of colon cancer specimens were strongly immunostained. IL-6 immunostaining was less conspicuous and less frequent in the epithelial cells of normal colonic mucosa. Northern blot experiments indicated that the expression of IL-6 in colonic mucosa correlates quantitatively with the presence of its m-RNA. Furthermore, IL-6 receptor (IL-6R) m-RNA was also detected and was twice as abundant in colonic carcinoma as in normal colon. It is concluded that mucosal epithelial cells of the gastrointestinal system express IL-6 and that in the case of the colon, malignancy is accompanied by a higher expression. In addition, the presence of IL-6R transcript suggests that normal and neoplastic colonic epithelial cells might be autocrinally regulated by IL-6.