Enhanced production of monocyte chemotactic protein 3 in inflammatory bowel disease mucosa

Abstract

Background: The beta chemokine monocyte chemotactic protein 3 (MCP-3) has chemoattractant and activating capabilities in monocytes, lymphocytes, eosinophils, and basophils.

Aims: To investigate MCP-3 expression in inflammatory conditions of the human intestinal mucosa.

Patients: Forty five colon biopsy specimens from 18 patients with inflammatory bowel disease (IBD; 16 specimens from inflamed and 10 from non-inflamed areas) and 19 control patients were examined.

Methods: Immunohistochemical staining and reverse transcription polymerase chain reaction (RT-PCR) were used for MCP-3 detection in tissue sections. Intestinal epithelial cell lines (HT-29, Caco-2, T-84) were stimulated with interleukin (IL) 1beta, IL-6, and tumour necrosis factor alpha (TNF-alpha) and examined for MCP-3 protein and mRNA expression using immunocytochemistry and RT-PCR, respectively.

Results: In tissue sections, MCP-3 protein was detected predominantly in epithelial cells, both in patients with IBD and in controls. MCP-3 staining was particularly pronounced at sites of active mucosal inflammation. The intensity of MCP-3 staining was positively correlated with the extent of epithelial destruction. In intestinal epithelial cell lines, MCP-3 mRNA was expressed, whereas MCP-3 protein was not consistently detected.

Conclusions: Our data show that MCP-3 protein is present in normal and inflamed intestinal tissue. MCP-3 production is substantially enhanced in areas of active inflammation, suggesting an immunoregulatory role of MCP-3 in intestinal inflammation.

Figure 1

Immunohistochemical staining of colonic mucosal sections with mouse antihuman MCP-3 monoclonal antibody. (A-C): macroscopically normal tissue derived from control patients; (D): negative control section derived from the same tissue sample as H; (E, F, and H): macroscopically inflamed tissues derived from patients with ulcerative colitis or (G) Crohn's disease. Original magnification × 400 (A, E) or × 1000 (B-D, F-H).

Figure 2

Semiquantitative distribution of MCP-3 in human colonic epithelial cells. UC, ulcerative colitis; CD, Crohn's disease; CP, control patients; +, biopsy specimens from macroscopically inflamed areas; −, biopsy specimens from macroscopically normal mucosa.

Figure 3

MCP-3 mRNA expression in human epithelial cells. (A): Cells were challenged with a buffer control (lanes A) or with TNF-α 10 ng/ml (lanes B) for 24 h. A 10 µl aliquot of the PCR tube content was taken out in the course of exponential DNA increase after 31 cycles (lanes 1), 33 cycles (lanes 2), and 35 cycles (lanes 3). (B): Time course analysis of MCP-3 mRNA expression by HT-29 cells without stimulation (0 h) and following stimulation with TNF-α for 2, 8, and 24 h. DNA fragments obtained after 35 cycles are shown.