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Isolation and Characterization of Dendritic Cells and Macrophages from the Mouse Intestine
Published on: May 21, 2012
The identification and developmental requirements of colonic CD169⁺ macrophages
Abstract:
CD169-positive macrophages in the marginal zone of the spleen and subcapsular sinus of lymph nodes play an important role as gatekeepers, strategically located to capture pathogens. Here we identified a population of CD169-positive macrophages in the colon and investigated which factors influenced their development. Murine colonic CD115+ F4/80(lo) CD11c(lo) macrophages expressing CD169 were present in the lamina propria, mainly surrounding the crypts. In spite of the high levels of bacterial flora in the colon and the importance of Toll-like receptor signalling in mucosal homeostasis, the presence of CD169+ macrophages was not affected in mice that were deficient in MyD88-mediated Toll-like receptor signalling and in mice in which the bacterial flora was eradicated. Whereas the development of splenic CD169+ macrophages was dependent on lymphotoxin α, colonic CD169+ macrophages were present in normal numbers in lymphotoxin α-deficient mice. In contrast, reduced numbers of CD169+ macrophages were found in the colon of mice deficient in vitamin A, whereas CD169+ macrophages in the spleen were unaffected. In conclusion, we identified a new macrophage subset in the lamina propria of the colon characterized by the expression of CD169. Its differentiation, unlike CD169+ macrophages in lymphoid organs, is independent of lymphotoxin α signalling, but requires vitamin A.
Insights
Researchers discovered a new type of CD169-positive macrophage in the colon. Their development is independent of lymphotoxin-alpha but relies on vitamin A, unlike those in spleen and lymph nodes.
Area of Science:
- Immunology
- Gastroenterology
- Cell Biology
Background:
- CD169-positive macrophages act as crucial gatekeepers in lymphoid organs, capturing pathogens.
- Their presence and function in the colon, a site with high bacterial load, remain largely unexplored.
Purpose of the Study:
- To identify and characterize CD169-positive macrophages in the murine colon.
- To investigate the factors influencing the development of these colonic macrophages.
Main Methods:
- Flow cytometry analysis of colonic lamina propria macrophages.
- Assessment of CD169+ macrophage populations in genetically modified mice (MyD88-deficient, lymphotoxin-alpha-deficient, vitamin A-deficient) and germ-free conditions.
Main Results:
- A distinct population of CD169+ macrophages (CD115+ F4/80lo CD11clo) was identified in the colonic lamina propria, primarily around crypts.
- Colonic CD169+ macrophage presence was unaffected by MyD88-mediated Toll-like receptor signaling deficiency or bacterial eradication.
- Unlike splenic CD169+ macrophages, colonic CD169+ macrophage development was independent of lymphotoxin-alpha.
- Vitamin A deficiency led to reduced numbers of colonic CD169+ macrophages, while splenic populations remained unaffected.
Conclusions:
- A novel subset of CD169-positive macrophages exists in the colonic lamina propria.
- The differentiation of these colonic macrophages is distinct from their lymphoid counterparts, being independent of lymphotoxin-alpha signaling and dependent on vitamin A.
