Intracellular reactive oxygen species production and phagocytosis of Staphylococcus aureus by milk neutrophils as tool to diagnose mastitis and identify susceptible dairy cows / Produção intracelular de espécies reativas de oxigênio e fagocitose de Staphylococcus aureus por neutrófilos lácteos como ferramentas para o diagnóstico da mastite e identificação de vacas leiteiras susceptíveis à mastite

The immune response capacity of the mammary gland plays a major role to determine if mastitis will or not be established. Thus, we hypothesize that a better understanding of polymorphonuclear neutrophil leukocyte (PMN) function will elucidate mechanisms that will improve our knowledge of how we could avoid an inflammatory process by increasing the immune capacity of the cow, and even further, to search for a tool to diagnose mastitis or a possible way to select and identify non-susceptible animals. The present study utilized 112 quarters from 28 Holstein dairy cows that were divided into quarters milk samples with somatic cell count (SCC) <2×105 cells mL-1 (n=72) and SCC >2×105 cells mL-1 (n=40). The percentages of milk PMNs and the levels of intracellular reactive oxygen species (ROS) and the phagocytosis of Staphylococcus aureus by milk neutrophils were evaluated by flow cytometry. Our results showed a higher percentage of neutrophils in quarter milk samples with high SCC (P=0.0003), and this group also had a significantly higher percentage of neutrophils that produced ROS (P=0.008). On the other hand, the phagocytosis intensity of S. aureus by milk neutrophils was higher in quarters with low SCC (P=0.003), suggesting a better mammary gland immunity against invading pathogens. Analyzing the results of the predictive values of the measured PMN functions, they cannot be used isolated as a good diagnosis test since none of them had a satisfactory sensitivity and specificity values, which was also confirmed by the Youden index values being far from one. In conclusion, the assessment of milk bovine neutrophil functions could improve our understanding of the cellular basis of mastitis. Although, the intracellular ROS production and S. aureus phagocytosis by milk neutrophil did not have high predictive values to detect intramammary infections, our results strengthen the idea that that poor bovine mammary gland neutrophil phagocytic ability may be associated with high SCC, and might be considered to identify susceptible dairy cows to mastitis.(AU)

A resposta imune da glândula mamária desempenha um papel importante ao determinar o estabelecimento da infecção. Desta forma, a melhor compreensão da função dos neutrófilos irá nos subsidiar conhecimentos, pelo qual podemos evitar o processo inflamatório pela otimização da resposta imune de bovinos leiteiros, e fornece ferramentas para diagnosticar a mastite ou um possível instrumento para identificar e selecionar animais resistentes à infecção intramamária, aumentando a produtividade do rebanho. O presente estudo utilizou 112 amostras provenientes de quartos mamários de 28 vacas Holandesas que foram divididos em amostras de leite com baixa (n=72; <2×105 células mL-1) ou alta (n=40; 2×105 células mL-1) contagem de células somáticas (CCS). A porcentagem de neutrófilos no leite, a produção intracelular de espécies reativas de oxigênio (ERO) e a fagocitose de Staphylococcus aureus pelos neutrófilos do leite foram avaliadas por citometria de fluxo. Os resultados do presente estudo demonstraram maior percentagem de neutrófilos (CH138+; P=0,0003) e percentagem de neutrófilos que produziram ERO (P=0,008) em amostras de leite com alta CCS. Por outro lado, a intensidade de fagocitose de S. aureus por neutrófilos em amostras de leite com baixa CCS (P=0,003), que demonstra maior atividade funcional destas células neste grupo. As funções neutrofílicas para o diagnóstico da mastite não apresentaram valores de sensibilidade e especificidade altos, que foram confirmados pelo índice Youden. Desta forma, conclui-se que a produção intracelular de ERO e fagocitose de S. aureus pelos neutrófilos do leite não apresentaram valores preditivos altos para detecção de mastite. Além disto, os resultados do presente estudo reforçam a ideia de neutrófilos do leite com menor capacidade fagocítica podem ser associados à alta CCS, e pode ser considerado como uma ferramenta para identificar animais mais susceptíveis à infecções intramamárias.(AU)

Edaravone attenuates paraquat-induced lung injury by inhibiting oxidative stress in human type Ⅱ alveolar epithelial cells / 世界急诊医学杂志（英文）

BACKGROUND: Edaravone (3-methyl-1-penyl-2-pyrazolin-5-one) is a potent free-radical scavenger and has the antioxidant ability to inhibit lipid peroxidation. The study aimed to examine the effect of edaravone on protecting the acute injury of human type Ⅱ alveolar epithelial cells (A549 cells) induced by paraquat (PQ) and the change of production of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD). METHODS: A549 cells were cultured and divided into PQ group (group P), edaravone-treated group (group E) and normal control group (group C). The cells in group P were exposed to paraquat (600 mol/L), and the cells in group E were treated with edaravone (100 mol/L) additionally, and no drug intervention was given to the cells in group C. Real-time monitoring by LSCM was used to detect the cell response and the intracellular dynamic change of ROS level in A549 cells after administration of PQ and edaravone. And the levels of SOD and MDA were detected respectively by biochemistry colorimetry. Data were expressed as mean ± standard error of the mean. Statistical analysis was carried out with the soft SPSS 16.0. RESULTS: The concentration of intracellular ROS significantly increased when PQ was given to A549 cells. But after administration of edaravone, the concentration of intracellular ROS was decreased. Compared to the PQ group, the levels of SOD in the edaravone group were significantly increased while the levels of MDA were markedly decreased. CONCLUSIONS: Paraquat can increase the oxidative stress, and induce the lipid peroxidation of A549 cells. Edaravone has the effect to scavenge reactive oxygen species, and to protect against the PQ-induced lung toxicity.