and Specific Aims.) Pneumocystis carinii is an opportunistic fungus which causes severe pneumonia in immunocompromised hosts including patients with hematologic and solid malignancies, organ transplantation and AIDS. P. carinii has a complex life cycle alternating between cyst and trophozoite forms which live on the epithelium of the lower respiratory tract. Evidence suggests that alveolar macrophages mediate the uptake and removal of P. carinii from alveolar spaces and serve an essential role in host defense against infection. Macrophages not only bind and phagocytize P. carinii, but are further activated to release a number of important inflammatory products including reactive oxidants, arachidonic acid (AA) metabolites and tumor necrosis factor alpha (TNFa). The mechanisms by which macrophages bind and phagocytize P. carinii and become activated to release inflammatory mediators are not well understood. Recent studies suggest that the interaction of macrophages with P. carinii is largely mediated by macrophage mannose receptors. The precise ligand on P. carinii which is recognized by mannose receptors has not been determined. P. carinii, however, contains a mannose-rich surface glycoprotein termed gp120 which is the probable ligand for this receptor. The application hypothesizes that gp120, a principal component of P. carinii, interacts with macrophage mannose receptors and the interaction of gp120 with macrophages mediates P. carinii binding and phagocytosis and activates macrophage inflammatory systems including AA metabolism, oxidant generation, and TNFa release.
The Specific Aims are to: 1) evaluate the interaction of purified gp120 with alveolar macrophages; 2) purify and characterize gp120 receptors present on the surface of alveolar macrophages; 3) evaluated the role of gp120 in mediating the adherence of P. carinii to alveolar macrophages and in initiation of phagocytosis; 4) investigate the role of gp120 in activating macrophage inflammatory systems; and 5) determine the expression of gp120 on isolated P. carinii cysts and trophozoites.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29AI034336-02
Application #
2069452
Study Section
Lung Biology and Pathology Study Section (LBPA)
Project Start
1993-07-01
Project End
1998-06-30
Budget Start
1994-07-01
Budget End
1995-06-30
Support Year
2
Fiscal Year
1994
Total Cost
Indirect Cost
Name
Mayo Clinic, Rochester
Department
Type
DUNS #
City
Rochester
State
MN
Country
United States
Zip Code
55905
Gustafson, M P; Limper, A H; Leof, E B (1999) Characterization of the Cdc25 phosphatase in Pneumocystis carinii. J Eukaryot Microbiol 46:129S
Thomas, C F; Anders, R A; Gustafson, M P et al. (1998) Pneumocystis carinii contains a functional cell-division-cycle Cdc2 homologue. Am J Respir Cell Mol Biol 18:297-306
Limper, A H (1998) Alveolar macrophage and glycoprotein responses to Pneumocystis carinii. Semin Respir Infect 13:339-47
Thomas Jr, C F; Limper, A H (1998) Pneumocystis pneumonia: clinical presentation and diagnosis in patients with and without acquired immune deficiency syndrome. Semin Respir Infect 13:289-95
Limper, A H; Hoyte, J S; Standing, J E (1997) The role of alveolar macrophages in Pneumocystis carinii degradation and clearance from the lung. J Clin Invest 99:2110-7
Hoyte, J S; Standing, J E; Limper, A H (1997) Steady-state effects of vitronectin and fibronectin on the binding, uptake, and degradation of Pneumocystis carinii in rat alveolar macrophages. Inflammation 21:335-45
Limper, A H; Thomas Jr, C F; Mubarak, K K et al. (1997) Characterization of the Pneumocystis carinii cyclin-dependent kinase life cycle regulatory system. J Eukaryot Microbiol 44:32S
Limper, A H; Thomas Jr, C F; Anders, R A et al. (1997) Interactions of parasite and host epithelial cell cycle regulation during Pneumocystis carinii pneumonia. J Lab Clin Med 130:132-8
Yu, M L; Limper, A H (1997) Pneumocystis carinii induces ICAM-1 expression in lung epithelial cells through a TNF-alpha-mediated mechanism. Am J Physiol 273:L1103-11
Limper, A H; Standing, J E; Hoyte, J S (1996) The role of alveolar macrophages in Pneumocystis carinii elimination from the lower respiratory tract. J Eukaryot Microbiol 43:12S

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