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Dendritic cells endocytose Bacillus anthracis spores: implications for anthrax pathogenesis
Katherine C Brittingham1, Gordon Ruthel, Rekha G Panchal
1U.S. Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA.
Journal of Immunology (Baltimore, Md. : 1950)
|April 22, 2005
Summary
Bacillus anthracis spores are engulfed by dendritic cells (DCs), which then migrate to lymph nodes. Anthrax spores manipulate DCs, potentially aiding infection spread.
Area of Science:
- Immunology
- Microbiology
- Pathogenesis
Background:
- Inhalational anthrax progression involves Bacillus anthracis spore phagocytosis and lymph node transport.
- Dendritic cells (DCs) in the respiratory tract are key phagocytes that migrate to lymph nodes.
Purpose of the Study:
- To investigate the role of human dendritic cells (DCs) in the uptake and dissemination of Bacillus anthracis spores.
- To understand the early immune response and host-pathogen interactions during inhalational anthrax.
Main Methods:
- Human DCs were exposed to pathogenic and attenuated B. anthracis spores.
- Flow cytometry was used to analyze DC surface receptors and maturation markers.
- MAPK signaling pathways and inflammatory cytokine secretion (TNF-alpha, IL-6, IL-8) were measured.
Main Results:
- DCs efficiently phagocytosed B. anthracis spores via coiling phagocytosis.
- Spore uptake altered DC chemokine receptor expression, promoting lymph node homing.
- DCs matured phenotypically and showed enhanced costimulatory activity post-infection.
- MAPK signaling was rapidly activated then suppressed, correlating with reduced inflammatory cytokine production and potential anthrax lethal toxin activity.
Conclusions:
- Bacillus anthracis spores are readily phagocytosed by human dendritic cells.
- B. anthracis spores induce DC maturation and migration, potentially exploiting DCs for dissemination.
- Early MAPK pathway modulation and suppressed cytokine secretion suggest a mechanism for immune evasion by B. anthracis.