Corticotropin-releasing factor receptor subtype 2 in human colonic mucosa: Down-regulation in ulcerative colitis

Figure 1 Reverse transcription polymerase chain reaction for corticotropin-releasing factor 2 receptor gene expression in total RNA isolated from the human colon cancer cell line Caco2 (1), human colon (2), and human brain (3) from healthy subjects. The predicted size products (308 bp) were amplified in the human colon and brain samples. Negative controls in the absence of reverse transcription enzyme (4) or DNA template (5) are also presented. CRF: Corticotropin-releasing factor; M: Marker.

Figure 2 Mapping of corticotropin-releasing factor 2 receptor protein expression in distal/sigmoid colon biopsies of healthy human subjects. Tissue sections from normal mucosal biopsies were stained by immunofluorescence using specific antisera against corticotropin-releasing factor 2 (CRF₂) (A, 2064a-CRF₂) and both CRF₁ and CRF₂ (B, 4392a-CRF_{1 and 2}). Immunoreactivity was localized in isolated structures of the lamina propria (long arrows) and in the epithelial cells of the intestinal crypts (short arrows). Replacement of the antiserum by non-specific rabbit IgG (C, negative) abolished all specific staining. Original magnification 100×.

Figure 3 Comparison of corticotropin-releasing factor 2 receptor immunoreactivity in distal/sigmoid biopsies from healthy human subjects and patients with moderate ulcerative colitis and patients in remission. Tissue sections from mucosal biopsies were stained by immunofluorescence using specific antisera 2064a- corticotropin-releasing factor 2 (CRF₂) (A, C, E). Immunoreactivity for CRF₂ observed in the epithelial cells of the intestinal crypts in the control group, was not found in the UCact and UCrem groups. Replacement of the antiserum by non-specific rabbit IgG (B, D, F) abolished all specific staining. Original magnification 100×.

Figure 4 Corticotropin-releasing factor 2 receptor protein expression in epithelial cells in distal/sigmoid biopsies from five groups: Healthy subjects, patients with moderately active ulcerative colitis, patients with ulcerative colitis in remission, patients with human immunodeficiency virus and functional bowel disease. UCact: Active ulcerative colitis; UCrem: Ulcerative colitis in remission; HIV: Human immunodeficiency virus; FBD: Functional bowel disease. ^aP < 0.05 vs control group.