title: Reduced expression of CD45 protein-tyrosine phosphatase provides protection against anthrax pathogenesis.
abstract: The modulation of cellular processes by small molecule inhibitors, gene inactivation, or targeted knockdown strategies combined with phenotypic screens are powerful approaches to delineate complex cellular pathways and to identify key players involved in disease pathogenesis. Using chemical genetic screening, we tested a library of known phosphatase inhibitors and identified several compounds that protected Bacillus anthracis infected macrophages from cell death. The most potent compound was assayed against a panel of sixteen different phosphatases of which CD45 was found to be most sensitive to inhibition. Testing of a known CD45 inhibitor and antisense phosphorodiamidate morpholino oligomers targeting CD45 also protected B. anthracis-infected macrophages from cell death. However, reduced CD45 expression did not protect anthrax lethal toxin (LT) treated macrophages, suggesting that the pathogen and independently added LT may signal through distinct pathways. Subsequent, in vivo studies with both gene-targeted knockdown of CD45 and genetically engineered mice expressing reduced levels of CD45 resulted in protection of mice after infection with the virulent Ames B. anthracis. Intermediate levels of CD45 expression were critical for the protection, as mice expressing normal levels of CD45 or disrupted CD45 phosphatase activity or no CD45 all succumbed to this pathogen. Mechanism-based studies suggest that the protection provided by reduced CD45 levels results from regulated immune cell homeostasis that may diminish the impact of apoptosis during the infection. To date, this is the first report demonstrating that reduced levels of host phosphatase CD45 modulate anthrax pathogenesis.
authors.affiliation: United States Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702-5011, USA. rekha.panchal@amedd.army.mil
authors.forename: Rekha G
authors.initials: RG
authors.lastname: Panchal
authors.forename: Ricky L
authors.initials: RL
authors.lastname: Ulrich
authors.forename: Steven B
authors.initials: SB
authors.lastname: Bradfute
authors.forename: Douglas
authors.initials: D
authors.lastname: Lane
authors.forename: Gordon
authors.initials: G
authors.lastname: Ruthel
authors.forename: Tara A
authors.initials: TA
authors.lastname: Kenny
authors.forename: Patrick L
authors.initials: PL
authors.lastname: Iversen
authors.forename: Arthur O
authors.initials: AO
authors.lastname: Anderson
authors.forename: Rick
authors.initials: R
authors.lastname: Gussio
authors.forename: William C
authors.initials: WC
authors.lastname: Raschke
authors.forename: Sina
authors.initials: S
authors.lastname: Bavari
mesh_terms: D000818:Animals; D000881:Anthrax / Q000201:enzymology* / Q000517:prevention & control*; D000942:Antigens, Bacterial / Q000378:metabolism / Q000633:toxicity; D017209:Apoptosis; D001408:Bacillus anthracis / Q000472:pathogenicity* / Q000502:physiology; D001427:Bacterial Toxins / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000633:toxicity; D002470:Cell Survival; D005260:Female; D005434:Flow Cytometry; D055785:Gene Knockdown Techniques; D005820:Genetic Testing; D015151:Immunoblotting; D007124:Immunoenzyme Techniques; D017493:Leukocyte Common Antigens / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008264:Macrophages / Q000382:microbiology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009025:Morpholines / Q000494:pharmacology; D060172:Morpholinos; D010587:Phagocytosis; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D013171:Spores, Bacterial / Q000254:growth & development / Q000472:pathogenicity
chemical_list: D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D009025:Morpholines; D060172:Morpholinos; C030325:anthrax toxin; D010744:Phosphoric Monoester Hydrolases; D017493:Leukocyte Common Antigens