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M cells as portals of entry for HIV
1VA Medical Center and University of California, San Francisco, CA 94121, USA. zelda@itsa.ucsf.edu
Abstract:
Accumulating evidence points toward active uptake by mucosal antigen sampling cells as the mechanism for rectal HIV acquisition. Organized lymphoid tissue in the intestine consists of lymphoid follicles with an epithelium containing M cells specialized for uptake and transport of microorganisms, bringing them into contact with lymphoid cells. M cells have been found in the human colon and rectum, and adherence and uptake of HIV by M cells in mouse and rabbit Peyer's patches has been demonstrated in vitro. In an in vivo mouse model of viral acquisition, reovirus is actively taken up by M cells into rectal lymphoid tissue containing CD4 lymphocytes and macrophages, which are targets and replication sites for HIV. Immunization strategies for prevention of HIV transmission should include a mucosal component to prevent initial entry, since elimination from cellular sanctuaries remains an elusive goal.
Insights
Rectal HIV acquisition occurs through active uptake by specialized M cells in the rectal tissue. Mucosal immunization is crucial for preventing initial HIV entry, as eliminating the virus from established cellular sanctuaries is challenging.
Area of Science:
- Immunology
- Virology
- Gastroenterology
Background:
- Mucosal antigen sampling cells, particularly M cells, are implicated in the initial stages of rectal HIV acquisition.
- These specialized cells in the intestinal lymphoid tissue facilitate the transport of microorganisms, including HIV, to underlying immune cells.
Discussion:
- In vitro studies demonstrate HIV adherence and uptake by M cells in Peyer's patches.
- An in vivo mouse model shows active M cell uptake of reovirus into rectal lymphoid tissue, where target cells like CD4 lymphocytes and macrophages reside.
Key Insights:
- M cells in the human colon and rectum are key players in the rectal HIV transmission pathway.
- The rectal lymphoid tissue contains CD4 lymphocytes and macrophages, which are critical targets and replication sites for HIV.
Outlook:
- Future HIV prevention strategies must incorporate mucosal components to block initial viral entry.
- Targeting M cell-mediated uptake could be a novel approach for rectal HIV prevention.