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Updated: Aug 13, 2026
Depletion and Reconstitution of Macrophages in Mice
Published on: August 1, 2012
Cyclooxygenase 2 is up-regulated and localized to macrophages in the intestine of Min mice
Abstract:
Expression of cyclooxygenase 2 (COX-2) is believed to play an important role in adenoma formation in murine polyposis models, and inhibition of COX-2 activity may, at least, partly explain the chemopreventative activity of non-steroidal anti-inflammatory drugs against colorectal cancer in humans. However, the mechanism by which COX-2 acts in intestinal tumorigenesis remains unresolved because of conflicting data on the cellular localization of COX-2 in intestinal mucosa. Using immunohistochemistry with specific COX-2 antiserum, we have shown that COX-2 protein is localized to interstitial cells at the base of and within adenomas of the small and large intestine of multiple intestinal neoplasia (Min) mice. No COX-2 staining was observed in dysplastic epithelial cells within adenomas or in histologically normal epithelium. Moreover, COX-2 staining was observed in lamina propria cells of histologically normal intestine of Min mice. No staining was demonstrated in wild-type littermates. The rat monoclonal antibody F4/80 was used to show that COX-2-positive cells represented a subset of the macrophage population present in the intestine of Min mice. Localization of COX-2 to macrophages implies a paracrine effect of COX-2 function on epithelial cells in adenomas and also on histologically normal epithelium. Up-regulation of COX-2 expression in lamina propria macrophages may precede loss of the second functional Apc allele in epithelial cells before adenoma formation in the Min mouse model of intestinal tumorigenesis.
Insights
Cyclooxygenase 2 (COX-2) in intestinal tumors is found in macrophages, not cancer cells. This suggests COX-2 influences tumor growth indirectly, offering new insights into colorectal cancer prevention.
Area of Science:
- Gastroenterology
- Oncology
- Immunology
Background:
- Cyclooxygenase 2 (COX-2) is implicated in colorectal cancer development.
- The precise cellular location of COX-2 in intestinal tumors is debated, hindering understanding of its role.
- Non-steroidal anti-inflammatory drugs' chemopreventive effects may involve COX-2 inhibition.
Purpose of the Study:
- To determine the specific cellular localization of COX-2 in the intestine of a mouse model of intestinal tumorigenesis.
- To elucidate the cell types expressing COX-2 within adenomas and normal intestinal tissue.
- To understand the implications of COX-2 localization for its role in intestinal tumorigenesis.
Main Methods:
- Immunohistochemistry using specific COX-2 antiserum on intestinal tissues from multiple intestinal neoplasia (Min) mice and wild-type littermates.
- Utilized the F4/80 antibody to identify macrophage populations.
- Correlated COX-2 expression with specific cell types within adenomas and normal intestinal mucosa.
Main Results:
- COX-2 protein was localized to interstitial cells at the base and within intestinal adenomas in Min mice.
- No COX-2 staining was detected in dysplastic epithelial cells or normal epithelium.
- COX-2 staining was observed in lamina propria cells of normal intestine in Min mice, identified as a subset of macrophages.
- No COX-2 staining was observed in wild-type littermates.
Conclusions:
- COX-2 is expressed in macrophages within the intestinal mucosa of Min mice, not in epithelial cells.
- This macrophage-specific COX-2 expression suggests a paracrine mechanism influencing both adenoma and normal epithelial cells.
- Upregulation of COX-2 in macrophages may be an early event preceding adenoma formation in this model.
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