Butyrate differentially affects constitutive and cytokine-induced expression of HLA molecules, secretory component (SC), and ICAM-1 in a colonic epithelial cell line (HT-29, clone m3).

In conclusion, we have found that physiological concentrations of butyrate increase the constitutive levels of HLA class I and SC molecules in HT-29m3 cells. Moreover, butyrate at high concentrations induces de novo synthesis of HLA-DR but not ICAM-1 molecules. Our data further showed that butyrate generally facilitates the cytokine-induced expression of immunological molecules in these cells but, interestingly, it specifically reduces the stimulatory effects of TNF and IL-4 on HLA class I and SC, respectively. We are currently studying how butyrate affects transcriptional regulation of the genes encoding these molecules. Further knowledge about the effects of butyrate in relation to gene regulation is required. It is possible that butyrate might interfere with specific, cytokine-dependent regulatory elements in certain genes which, in turn, could have implications for immune regulation of colonic epithelial cells in vivo.