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Lysozyme-rich muciphages surrounding colorectal adenomas
1Gastrointestinal and Liver Pathology Research Laboratory, Karolinska Institute and Hospital, Stockholm, Sweden. Carlos.Rubio@onkpat.ki.se
Abstract:
Muciphages are mucin-rich phagocytes believed to evolve as a result of the disruption of colorectal crypts. In a previous work we found, in rectal biopsies from patients with chronic ulcerative colitis, muciphages having not only mucin but also lysozyme, an enzyme with a potent antimicrobial activity. Recently we detected lysozyme-rich muciphages in the normal mucosa of the stalk of colonic adenomas. Filed hematoxylin and eosin (H&E)-stained sections from 30 consecutive colorectal adenomas with a stalk (lined by normal colorectal mucosa) were stained with PAS (for mucopolysaccharides), with CD68 (to label macrophages) and with lysozyme (Muramidase). Of the 30 adenomas, 16 (40%) showed muciphages in the mucosa of the stalk. Those muciphages were PAS- CD68- and lysozyme-positive. Although the significance of these findings remains elusive, it is conceivable that lysozyme-rich muciphages mirror increased cell destruction in colorectal adenomas with a high cell turnover. The possibility that lysozyme-rich muciphages surrounding adenomas are instrumental in a novel molecular mechanism of host defense, effective at the early stages of colorectal carcinogenesis, was also entertained. Such a mechanism would prevent the lateral expansion of the dysplastic epithelium of the adenoma into the surrounding normal mucosa of the stalk.
Insights
Lysozyme-rich muciphages were found in the stalks of colonic adenomas, suggesting a potential role in host defense against colorectal cancer. These findings may indicate increased cell turnover and a novel mechanism to prevent adenoma expansion.
Area of Science:
- Gastroenterology
- Immunology
- Oncology
Background:
- Muciphages, phagocytes rich in mucin, are thought to arise from colorectal crypt disruption.
- Previous studies identified muciphages containing lysozyme, an antimicrobial enzyme, in ulcerative colitis rectal biopsies.
- Lysozyme-rich muciphages have now been detected in the normal mucosa of colonic adenoma stalks.
Purpose of the Study:
- To investigate the presence and characteristics of muciphages in the stalks of colonic adenomas.
- To determine if these muciphages express lysozyme and other macrophage markers.
- To explore the potential role of lysozyme-rich muciphages in early colorectal carcinogenesis and host defense.
Main Methods:
- Analysis of 30 stalk sections from consecutive colonic adenomas.
- Staining with Periodic Acid-Schiff (PAS) for mucopolysaccharides.
- Immunohistochemical staining for CD68 (macrophage marker) and lysozyme (muramidase).
Main Results:
- Muciphages were identified in the stalk mucosa of 16 out of 30 (40%) colonic adenomas.
- These muciphages were PAS-negative, CD68-negative, and lysozyme-positive.
- The findings suggest these cells are distinct from typical macrophages.
Conclusions:
- Lysozyme-rich muciphages are present in the normal mucosa adjacent to colonic adenomas.
- Their presence may reflect increased cell turnover or destruction within adenomas.
- These cells could play a role in a novel host defense mechanism against early colorectal carcinogenesis by limiting adenoma expansion.