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- Title
NADPH Phagocyte Oxidase Knockout Mice Control Trypanosoma cruzi Proliferation, but Develop Circulatory Collapse and Succumb to Infection.
- Authors
Santiago, Helton C.; Gonzalez Lombana, Claudia Z.; Macedo, Juan P.; Utsch, Lara; Tafuri, Wagner L.; Campagnole-Santos, Maria José; Alves, Rosana O.; Alves-Filho, José C. F.; Romanha, Alvaro J.; Cunha, Fernando Queiroz; Teixeira, Mauro M.; Radi, Rafael; Vieira, Leda Q.
- Abstract
•NO is considered to be a key macrophage-derived cytotoxic effector during Trypanosoma cruzi infection. On the other hand, the microbicidal properties of reactive oxygen species (ROS) are well recognized, but little importance has been attributed to them during in vivo infection with T. cruzi. In order to investigate the role of ROS in T. cruzi infection, mice deficient in NADPH phagocyte oxidase (gp91phox−/− or phox KO) were infected with Y strain of T. cruzi and the course of infection was followed. phox KO mice had similar parasitemia, similar tissue parasitism and similar levels of IFN-γ and TNF in serum and spleen cell culture supernatants, when compared to wild-type controls. However, all phox KO mice succumbed to infection between day 15 and 21 after inoculation with the parasite, while 60% of wild-type mice were alive 50 days after infection. Further investigation demonstrated increased serum levels of nitrite and nitrate (NOx) at day 15 of infection in phox KO animals, associated with a drop in blood pressure. Treatment with a NOS2 inhibitor corrected the blood pressure, implicating NOS2 in this phenomenon. We postulate that superoxide reacts with •NO in vivo, preventing blood pressure drops in wild type mice. Hence, whilst superoxide from phagocytes did not play a critical role in parasite control in the phox KO animals, its production would have an important protective effect against blood pressure decline during infection with T. cruzi. Author Summary: When pathogens enter their hosts, they are fought by several resistance strategies, including capture by phagocytes and the production of pathogen-toxic molecules. Nitric oxide, a free radical, has been extensively studied as one of these toxic molecules that successfully mediates intracellular parasite killing, including Trypanosoma cruzi, the protozoan parasite that causes Chagas' disease. On the other hand, reactive oxygen species also mediate resistance to several pathogens, mainly bacterial. In this study, we addressed the role of reactive oxygen species in the resistance to T. cruzi using gene-deficient mice, a species which phagocytes lack the ability to produce (phox−/− mice). We found that phagocyte-derived reactive oxygen species are not critical to mediate resistance to parasite in the knock-out animals. However, phox−/− mice presented higher mortality and lower blood pressure due to infection with T. cruzi than non-deficient mice. The blood pressure was restored to normal by an inhibitor of nitric oxide synthesis by phagocytes. We hypothesize that superoxide (one of the oxygen reactive species) controls blood pressure during infection with T. cruzi, by reacting with nitric oxide and preventing its action on blood vessels.
- Subjects
TRYPANOSOMA cruzi; NADPH oxidase; CHAGAS' disease; KNOCKOUT mice; SUPEROXIDES; NITRIC oxide; REACTIVE oxygen species; BLOOD pressure
- Publication
PLoS Neglected Tropical Diseases, 2012, Vol 6, Issue 2, p1
- ISSN
1935-2727
- Publication type
Article
- DOI
10.1371/journal.pntd.0001492