Differential Protein Expression Profile in the Intestinal Epithelium from Patients with Inflammatory Bowel Disease

Abstract

The loss of intestinal epithelial cell (IEC) function is a critical component in the initiation and perpetuation of chronic intestinal inflammation in the genetically susceptible host. We applied proteome analysis (PA) to characterize changes in the protein expression profile of primary IEC from patients with Crohn's disease (CD) and ulcerative colitis (UC). Surgical specimens from 18 patients with active CD (N = 6), UC (N = 6), and colonic cancer (N = 6) were used to purify primary IEC from ileal and colonic tissues. Changes in protein expression were identified using 2D-gel electrophoreses (2D SDS-PAGE) and peptide mass fingerprinting via MALDI-TOF mass spectrometry (MS) as well as Western blot analysis. PA of primary IEC from inflamed ileal tissue of CD patients and colonic tissue of UC patients identified 21 protein spots with at least 2-fold changes in steady-state expression levels compared to the noninflamed tissue of control patients. Statistical significance was achieved for 9 proteins including the Rho-GDP dissociation inhibitor alpha that was up-regulated in CD and UC patients. Additionally, 40 proteins with significantly altered expression levels were identified in IEC from inflamed compared to noninflamed tissue regions of single UC (N = 2) patients. The most significant change was detected for programmed cell death protein 8 (7.4-fold increase) and annexin 2A (7.7-fold increase). PA in primary IEC from IBD patients revealed significant expression changes of proteins that are associated with signal transduction, stress response as well as energy metabolism. The induction of Rho GDI alpha expression may be associated with the destruction of IEC homeostasis under condition of chronic intestinal inflammation.

Current application of proteomics in biomarker discovery for inflammatory bowel disease

“…Employing a similar rationale, direct sampling of diseased tissue in IBD (a far simpler task compared to other diseases due to routine endoscopic biopsies) has been utilised for proteomic experiments (Table 2). Shkoda et al [33] reported the first proteomic study of intestinal tissue, identifying nine statistically significant proteins delineating inflamed IBD tissue from noninflamed controls. Furthermore, 40 proteins were further detected between inflamed and noninflamed UC tissue, although only two pairs of patient samples were analysed.…”

“…This issue holds true across the aforementioned studies in IBD as out of 19 biosample based discovery experiments, 8 studies used ≤ 6 cases and controls [33,34,38,5659] . In an effort to address this issue, Skates et al [55] designed a statistical model that estimates the statistical power of discovery and verification studies in tissue and plasma.…”

Classification of inflammatory bowel diseases by means of Raman spectroscopic imaging of epithelium cells

“…4 In addition, it is known that enterocytes from patients with IBD show distinct differences in protein expression profile. 5 The distinction between UC and CD is made based on clinical, endoscopic, radiologic, and pathologic features. 6 However, for about 15 to 20% of the patients it is not possible to classify them into either one of the IBD forms, with the result that diagnostics and therapy cannot be given, as requested, to these patients.…”

Proteomic Approaches for Biomarker Discovery in Ulcerative Colitis

“…Aberrant activation of nuclear factor of activated T cell (NFAT), and ectopic expression of tumor rejection antigen 1 and poliovirus receptor related protein 1 were detected in the UCaffected colonic mucosa. Comparison with colonic mucosal proteins between UC and CD revealed their specific characters of UC and common features to IBD (25)(26)(27). Intestinal epithelial cells (IECs) from patients with UC, CD, and colon cancer, analyzed by 2DE and MALDI-TOF/MS, showed 21 protein spots with at least 2-fold change between inflamed tissue from the IBD (UC and CD) patients and non-inflamed tissue from the patients with colonic cancer (25).…”

“…Comparison with colonic mucosal proteins between UC and CD revealed their specific characters of UC and common features to IBD (25)(26)(27). Intestinal epithelial cells (IECs) from patients with UC, CD, and colon cancer, analyzed by 2DE and MALDI-TOF/MS, showed 21 protein spots with at least 2-fold change between inflamed tissue from the IBD (UC and CD) patients and non-inflamed tissue from the patients with colonic cancer (25). The identified proteins were functionally related to signal transduction, stress response, and energy metabolism.…”