title: Surfactant Protein D Binds to Coxiella burnetii and Results in a Decrease in Interactions with Murine Alveolar Macrophages.
abstract: Coxiella burnetii is a Gram-negative, obligate intracellular bacterium and the causative agent of Q fever. Infections are usually acquired after inhalation of contaminated particles, where C. burnetii infects its cellular target cells, alveolar macrophages. Respiratory pathogens encounter the C-type lectin surfactant protein D (SP-D) during the course of natural infection. SP-D is a component of the innate immune response in the lungs and other mucosal surfaces. Many Gram-negative pulmonary pathogens interact with SP-D, which can cause aggregation, bactericidal effects and aid in bacterial clearance. Here we show that SP-D binds to C. burnetii in a calcium-dependent manner with no detectable bacterial aggregation or bactericidal effects. Since SP-D interactions with bacteria often alter macrophage interactions, it was determined that SP-D treatment resulted in a significant decrease in C. burnetii interactions to a mouse alveolar macrophage model cell line MH-S indicating SP-D causes a significant decrease in phagocytosis. The ability of SP-D to modulate macrophage activation by C. burnetii was tested and it was determined that SP-D does not alter the correlates measured for macrophage activation. Taken together these studies support those demonstrating limited activation of alveolar macrophages with C. burnetii and demonstrate interactions with SP-D participate in reduction of phagocyte attachment and phagocytosis.
authors.affiliation: Department of Microbial Pathogenesis & Immunology, Texas A&M Health Science Center, Bryan, Texas, United States of America.
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Soltysiak
authors.affiliation: Department of Microbial Pathogenesis & Immunology, Texas A&M Health Science Center, Bryan, Texas, United States of America.
authors.forename: Erin J
authors.initials: EJ
authors.lastname: van Schaik
authors.affiliation: Department of Microbial Pathogenesis & Immunology, Texas A&M Health Science Center, Bryan, Texas, United States of America.
authors.forename: James E
authors.initials: JE
authors.lastname: Samuel
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology*; D002460:Cell Line; D016997:Coxiella burnetii / Q000187:drug effects* / Q000472:pathogenicity; D008264:Macrophages / Q000276:immunology / Q000382:microbiology*; D051379:Mice; D010587:Phagocytosis; D037663:Pulmonary Surfactant-Associated Protein D / Q000494:pharmacology*
chemical_list: D000890:Anti-Infective Agents; D037663:Pulmonary Surfactant-Associated Protein D