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Microb Pathog ; 135: 103649, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31374321


Extracellular adenosine triphosphate (ATP) is as key mediator of immune and inflammatory responses. ATP is normally sequestered in the intracellular milieu and released by apoptotic and necrotic cells, where it acts as a pro-inflammatory mediator in the extracellular milieu. A limited number of studies have explored the involvement of purinergic signaling in oomycete infections, including Saprolegnia parasitica; this is a most destructive oomycete pathogen, associated with high mortality and severe economic losses for fish producers. The aim of this study was to determine whether purinergic signaling exerts anti- or pro-inflammatory effects in spleens of grass carp (Ctenopharyngodon idella) naturally infected by S. parasitica. Animals naturally infected with S. parasitica showed typical gross lesions characterized by cotton-wool tufts on the tail and fins, as well as severe histopathological lesions such as necrosis. Spleen ATP and metabolites of nitric oxide (NOx) levels were higher in fish naturally infected by S. parasitica compared to control on day 7 post-infection (PI). Spleen nucleoside triphosphate diphosphohydrolase (NTPDase) activity (ATP as substrate) was greater in fish naturally infected by S. parasitica than in uninfected on day 7 PI, while no significant differences were observed between groups with respect to NTPDase (adenosine diphosphate as substrate) and 5'-nucleotidase activities. Finally, adenosine deaminase (ADA) activity was lower in fish naturally infected by S. parasitica than in uninfected fish on day 7 PI. In summary, spleen tissue necrosis in the context of saprolegniosis provokes an intense release of ATP into the extracellular milieu, where it interacts with the P2X7 purine receptor and leads to a self-sustained pro-inflammatory deleterious cycle, contributing to an intense inflammatory process. In response to excessive ATP levels in the extracellular milieu, ATP and adenosine hydrolysis were modulated in an attempt to restrict the inflammatory process via upregulation of NTPDase and downregulation of ADA activities. We conclude that the purinergic signaling pathway modulates immune and inflammatory responses during natural infection with S. parasitica.

Trifosfato de Adenosina/metabolismo , Anti-Inflamatórios/metabolismo , Carpas/imunologia , Doenças dos Peixes/imunologia , Doenças dos Peixes/parasitologia , Purinérgicos/metabolismo , Transdução de Sinais , Baço/metabolismo , Adenosina Desaminase/metabolismo , Animais , Carpas/metabolismo , Modelos Animais de Doenças , Doenças dos Peixes/patologia , Proteínas de Peixes/imunologia , Micoses , Necrose , Óxido Nítrico/metabolismo , Saprolegnia/patogenicidade , Baço/patologia
Microb Pathog ; 135: 103637, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31326563


The indiscriminate use of antibiotics is a major concern for the aquaculture industry because of the increasing prevalence of bacterial resistance, including the emergence of multi-resistant strains of Aeromonas hydrophila. Therefore, alternative ecofriendly therapeutic or prophylactic approaches such as natural products have been suggested, including caffeine, a methylxanthine with potent bactericidal and antioxidant properties. The aims of this study were to evaluate whether dietary supplementation with caffeine exerted bactericidal effects against A. hydrophila, and to determine whether caffeine protected the liver of grass carp (Ctenopharyngodon idella) against A. hydrophila-induced oxidative damage. Experiment I evaluated the antimicrobial properties of caffeine dietary supplementation linked to longevity and mortality rates during aeromonosis. Fish infected with A. hydrophila that were fed diets containing 5% and 8% caffeine lived significantly longer than those fed with control diets. Experiment II evaluated hepatic oxidative stress-related parameters and microbial loads on day 7 post-infection. Levels of hepatic reactive oxygen species (ROS), lipid peroxidation (LOOH) and protein carbonylation (PC) levels were significantly higher in infected fish fed with control diet than in uninfected fish, and hepatic antioxidant capacity against peroxyl radicals (ACAP) levels, and superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione S-transferase (GST) and glutathione reductase (GR) activities were significantly inhibited. Dietary supplementation with 5% and 8% caffeine prevented the increase on hepatic ROS, LOOH and PC levels (except 5% caffeine) elicited by infection. Caffeine supplementation reduced or prevented the inhibition of hepatic SOD, GPx and GST activities. Finally, both caffeine concentrations reduced the hepatic microbial load compared to fish fed with control diets that were infected with A. hydrophila. Taken together, the data suggest that dietary supplementation with 8% caffeine may be considered a compelling prophylactic approach to aeromonosis caused by A. hydrophila.

Carga Bacteriana/efeitos dos fármacos , Cafeína/farmacologia , Suplementos Nutricionais , Doenças dos Peixes/tratamento farmacológico , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Hepatopatias/prevenção & controle , Aeromonas hydrophila , Ração Animal , Animais , Antioxidantes/farmacologia , Carpas , Modelos Animais de Doenças , Doenças dos Peixes/microbiologia , Doenças dos Peixes/mortalidade , Proteínas de Peixes , Infecções por Bactérias Gram-Negativas/microbiologia , Peroxidação de Lipídeos , Fígado/lesões , Fígado/patologia , Estresse Oxidativo , Peróxidos , Espécies Reativas de Oxigênio/metabolismo , Taxa de Sobrevida