Thacianna Barreto da Costa

Long-term effects of neonatal malnutrition on microbicide response, production of cytokines, and survival of macrophages infected by Staphylococcus aureus sensitive/resistant to methicillin

OBJECTIVE: To assess microbicide function and macrophage viability after in vitro cellular infection by methicillin-sensitive/resistant Staphylococcus aureus in nourished rats and rats subjected to neonatal malnutrition. METHODS: Male Wistar rats (n=40) were divided in two groups: Nourished (rats suckled by dams consuming a 17% casein diet) and Malnourished (rats suckled by dams consuming an 8% casein diet). Macrophages were recovered after tracheotomy, by bronchoalveolar lavage. After mononuclear cell isolation, four systems were established: negative control composed exclusively of phagocytes; positive control composed of macrophages plus lipopolysaccharide; and two testing systems, macrophages plus methicillin-sensitive Staphylococcus aureus and macrophages plus methicillin-resistant Staphylococcus aureus. The plates were incubated in a humid atmosphere at 37 degrees Celsius containing 5% CO2 for 24 hours. After this period tests the microbicidal response, cytokine production, and cell viability were analyzed. The statistical analysis consisted of analysis of variance (p<0.05). RESULTS: Malnutrition reduced weight gain, rate of phagocytosis, production of superoxide anion and nitric oxide, and macrophage viability. Production of nitrite and interleukin 18, and viability of macrophages infected with methicillin-resistant Staphylococcus aureus were lower. CONCLUSION: The neonatal malnutrition model compromised phagocyte function and reduced microbicidal response and cell viability. Interaction between malnutrition and the methicillin-resistant strain decreased the production of inflammatory mediators by effector cells of the immune response, which may compromise the immune systems defense ability.

Immunological parameters of macrophages infected by methicillin resistant/sensitive Staphylococcus aureus

INTRODUCAO: Modificacoes nas paredes celulares das cepas de Staphylococcus aureus relacionadas com o fenotipo de multirresistencia poderiam influenciar seus mecanismos de evasao frente a resposta imune? OBJETIVO: Avaliar a resposta microbicida e a sobrevivencia de macrofagos alveolares apos infeccao in vitro com Staphylococcus aureus meticilina sensivel/resistente. MATERIAL E METODOS: Utilizaram-se 20 ratos adultos, machos, albinos e da linhagem Wistar. Os macrofagos alveolares foram obtidos apos procedimento cirurgico de traqueostomia, por meios da coleta do lavado broncoalveolar. Os macrofagos alveolares foram cultivados na proporcao de 1:1 celulas/ml de Roswell Park Memorial Institute (RPMI)/poco e isolados pela capacidade de adesao a placa. Para avaliacao de parâmetros imunologicos, foram estabelecidos quatro sistemas: controle negativo, controle positivo, S. aureus sensivel a meticilina (MSSA) e S. aureus resistente a meticilina (MRSA). RESULTADOS: Ao comparar os sistemas de MSSA e MRSA, nao foi observada diferenca no indice de aderencia, na taxa de fagocitose, na producao do ânion superoxido e na viabilidade dos macrofagos. Ao analisar a cinetica de oxido nitrico, houve menor producao media desse radical para o MRSA quando comparado com o MSSA, no periodo de 4 a 10 horas de incubacao das culturas celulares. Entretanto, apos 12 horas, nao foi detectada divergencias entre esses sistemas. CONCLUSAO: Sugere-se que a resistencia a meticilina podera ser um fator que influenciara a capacidade de evasao da bacteria a resposta microbicida dos macrofagos. Apesar dos resultados de alguns parâmetros imunologicos terem sido similares entre os sistemas analisados, as oscilacoes ocorridas durante a producao do oxido nitrico poderao contribuir de forma importante para a sobrevivencia da bacteria Staphylococcus aureus.

Desnutrição neonatal e produção de IFN-γ IL-12 e IL-10 por macrófagos/linfócitos: estudo da infecção celular, in vitro, por Staphylococcus aureus meticilina sensível e meticilina resistente

OBJECTIVE: The present study assessed the influence of neonatal malnutrition on the production of interferon gamma, interleukin-12 and interleukin-10 in cultured macrophages and lymphocytes infected in vitro with methicillin-sensitive or methicillin-resistant Staphylococcus aureus. METHODS: Male Wistar rats were suckled by mothers fed during lactation a chow containing 17% protein for the nourished group and 8% for the undernourished group. After weaning, both groups received a normal diet in terms of protein content. The macrophages were obtained by bronchoalveolar lavage after tracheostomy. Cardiac puncture was used for the collection of lymphocytes. After isolation of different cell types, the challenge with the different strains was performed. Cytokines were measured by enzymelinked immunosorbent assay (ELISA), using samples collected from the culture supernatant after an incubation period of 24 hours. RESULTS: Malnutrition let to slow weight gain, low interferon gamma in cultured alveolar macrophages and lymphocytes and low production of interleukin-12 in cultured alveolar macrophages. Only interferon gamma and interleukin-10 in cultured alveolar macrophages differed between the two groups and study strains. CONCLUSION: The neonatal malnutrition model used impaired weight gain and reduced production of proinflammatory cytokines (interleukin-12 and interferon gamma), indicating that protein malnutrition may result in an inability to fight infections. The methicillin-resistant Staphylococcus aureus strain stimulated macrophages to produce interferon gamma and interleukin-10, suggesting that this strain better provokes the immune system, specifically for this cell type.