beta-Defensin-3 and -4 in intestinal epithelial cells display increased mRNA expression in ulcerative colitis

Abstract

mRNA expression of two recently described human beta-defensins (hBD-3 and hBD-4) in epithelial cells of normal small and large intestine and the impact of chronic intestinal inflammation on their expression levels was investigated. Intestinal specimens from patients with ulcerative colitis (UC), Crohn's disease (CD) and controls with no history of inflammatory bowel disease were studied. hBD-3 and hBD-4 mRNAs were determined in freshly isolated epithelial cells by real-time quantitative reverse transcription-polymerase chain reaction (QRT-PCR) and by in situ hybridization. The effect of proinflammatory cytokines on hBD-3 and hBD-4 mRNA expression in colon carcinoma cells was also investigated. Purified epithelial cells of normal small and large intestine expressed both hBD-3 and hBD-4 mRNA, with higher expression levels of hBD-3 mRNA. In situ hybridization revealed higher levels of mRNA expression in the crypt- compared to the villus/luminal-compartment. Interferon (IFN)-gamma, but not tumour necrosis factor (TNF)-alpha or IL-1beta, augmented hBD-3 mRNA expression. None of these agents stimulated hBD-4 expression. Colonic epithelial cells from patients with UC displayed a significant increase in hBD-3 and hBD-4 mRNA compared to epithelial cells of controls. In contrast, small intestinal epithelial cells from CD patients did not show increased expression levels compared to the corresponding control cells. Moreover, Crohn's colitis did not show increased expression of hBD-4 mRNA, while the data are inconclusive for hBD-3 mRNA. We conclude that the chronic inflammatory reaction induced in the colon of UC patients enhances hBD-3 and hBD-4 mRNA expression in the epithelium, whereas in CD this is less evident.

Fig. 1

Expression of hBD-3 and hBD-4 mRNA in human intestinal mucosa as determined by in situ hybridization. (a) jejunum, hBD-3 antisense probe; (b) jejunum, hBD-3 sense probe; (c) jejunum, hBD-4 antisense probe; (d) jejunum, hBD-4 sense probe; (e) colon, hBD-3 antisense probe; (f) colon, hBD-3 sense probe; (g) colon, hBD-4 antisense probe; (h) colon, hBD-4 sense probe. Original magnification: × 55.

Fig. 2

Expression levels of hBD-3 mRNA in freshly isolated l/v-IEC and c-IEC from jejunal, ileal and colonic mucosa of controls with no history of intestinal inflammation, colonic mucosa of UC and CD patients and ileal mucosa of CD patients as determined by qRT-PCR. mRNA levels are expresses as copies of hBD-3 mRNA/18S rRNA unit. Statistically significant differences are indicated. Horizontal bars indicate median values.

Fig. 3

Expression levels of hBD-4 mRNA in freshly isolated l/v-IEC and c-IEC from jejunal, ileal and colonic mucosa of controls with no history of intestinal inflammation, colonic mucosa of UC and CD patients and ileal mucosa of CD patients as determined by qRT-PCR. mRNA levels are expresses as copies of hBD-4 mRNA/18S rRNA unit. Statistically significant differences are indicated. Horizontal bars indicate median values.