Surfactant Protein A Mediates Mycoplasmacidal Activity of Alveolar Macrophages by Production of Peroxynitrite

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 96; no. 9; pp. 4953 - 4958
• Main Authors: Hickman-Davis, Judy, Gibbs-Erwin, Julie, Lindsey, J. Russell, Matalon, Sadis
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 27-04-1999; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences
• Subjects: Animals; Biological Sciences; Cells, Cultured; Cellular biology; Infections; Laboratory staining techniques; Lesions; Lungs; Macrophage Activation; Macrophages, Alveolar - microbiology; Macrophages, Alveolar - physiology; Mice; Mice, Inbred C57BL; Mycoplasma; Mycoplasma Infections - metabolism; Mycoplasma pulmonis; Nitrates - metabolism; Proteins; Proteolipids - metabolism; Pulmonary Surfactant-Associated Protein A; Pulmonary Surfactant-Associated Proteins; Pulmonary Surfactants - metabolism; Superoxides; Surfactants; Toxicity; Xanthines
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.96.9.4953

We have previously shown that surfactant protein A (SP-A) mediates in vitro killing of mycoplasmas by alveolar macrophages (AMs) from resistant C57BL/6 mice through a nitric oxide (· NO)-dependent mechanism. Herein, SP-A-deficient [SP-A(-/-)] and inducible · NO synthase-deficient [iNOS(-/-)] mice were infected intranasally with 105or 107colony-forming units of Mycoplasma pulmonis. SP-A(-/-) mice were as susceptible to mycoplasmal infection as highly susceptible C3H/He mice, and far more susceptible than resistant C57BL/6 mice. iNOS(-/-) mice had significantly greater numbers of mycoplasmas and severity of lung lesions than iNOS(+/+) controls. In vitro, AMs isolated from C57BL/6 mice, activated with IFN-γ , incubated with SP-A (25 μ g/ml), and infected with 1010colony-forming units of M. pulmonis, killed mycoplasmas within 6 h. Mycoplasmal killing was abrogated by 1,000 units/ml of copper-zinc superoxide dismutase. In the absence of AMs, incubation of M. pulmonis with the peroxynitrite generator$\text{3-morpholinosynodiomine}· \text{HCl}$(SIN-1) effected complete killing of mycoplasmas by 90 min in a dose-dependent manner. Addition of copper-zinc superoxide dismutase (3,000 units/ml), which converts SIN-1 to a · NO donor, prevented this killing. Neither of the reactive oxygen species generated by xanthine oxidase (10 milliunits/ml, plus 500 μ M xanthine and 100 μ M nor · NO generated by 1-propanamine-3-(2-hydroxy-2-nitroso-1-propylhydrazine (PAPA NONOate) (100 μ M) killed mycoplasmas. These data establish that peroxynitrite generation by AMs is necessary for the killing of a pathogen in vitro and in vivo.