Effect of the systemic administration of methylprednisolone on the lungs of brain-dead donor rats undergoing pulmonary transplantation

OBJECTIVE: Most lung transplants are obtained from brain-dead donors. The physiopathology of brain death involves hemodynamics, the sympathetic nervous system, and inflammatory mechanisms. Administering methylprednisolone 60 min after inducing brain death in rats has been shown to modulate pulmonary inflammatory activity. Our objective was to evaluate the effects of methylprednisolone on transplanted rat lungs from donors treated 60 min after brain death. METHODS: Twelve Wistar rats were anesthetized, and brain death was induced. They were randomly divided into two groups (n = 6), namely a control group, which was administered saline solution, and a methylprednisolone group, which received the drug 60 min after the induction of brain death. All of the animals were observed and ventilated for 2 h prior to being submitted to lung transplantation. We evaluated the hemodynamic and blood gas parameters, histological score, lung tissue levels of thiobarbituric acid-reactive substances, level of superoxide dismutase, level of tumor necrosis factor-alpha, and level of interleukin-1 beta. RESULTS: After transplantation, a significant reduction in the levels of tumor necrosis factor-alpha and IL-1β was observed in the group that received methylprednisolone (p = 0.0084 and p = 0.0155, respectively). There were no significant differences in tumor necrosis factor-alpha and superoxide dismutase levels between the control and methylprednisolone groups (p = 0.2644 and p = 0.7461, respectively). There were no significant differences in the blood gas parameters, hemodynamics, and histological alterations between the groups. CONCLUSION: The administration of methylprednisolone after brain death in donor rats reduces inflammatory activity in transplanted lungs but has no influence on parameters related to oxidative stress

Evaluation of systemic inflammation in patients being weaned from mechanical ventilation

OBJECTIVES: The aim of this study was to evaluate systemic inflammatory factors and their relation to success or failure in a spontaneous ventilation test. METHODS: This cross-sectional study included a sample of 54 adult patients. Demographic data and clinical parameters were collected, and blood samples were collected in the first minute of the spontaneous ventilation test to evaluate interleukin (IL)-1b, IL-6, IL-8, and IL-10, tumour necrosis factor alpha (TNFa) and C-reactive protein. RESULTS: Patients who experienced extubation failure presented a lower rapid shallow breathing index than those who passed, and these patients also showed a significant increase in C-reactive protein 48 hours after extubation. We observed, moreover, that each unit increase in inflammatory factors led to a higher risk of spontaneous ventilation test failure, with a risk of 2.27 (1.001 – 4.60, p=0.049) for TNFa, 2.23 (1.06 – 6.54, p=0.037) for IL-6, 2.66 (1.06 – 6.70, p=0.037) for IL-8 and 2.08 (1.01 – 4.31, p=0.04) for IL-10, and the rapid shallow breathing index was correlated with IL-1 (r=-0.51, p=0.04). CONCLUSIONS: C-reactive protein is increased in patients who fail the spontaneous ventilation test, and increased ILs are associated with a greater prevalence of failure in this process; the rapid shallow breathing index may not be effective in patients who present systemic inflammation

O efeito da n-acetilcisteína (NAC) sobre a lesão de isquemia e reperfusão pulmonar em ratos

Objetivo – Verificar os efeitos da N-acetilcisteína (NAC), administrada antes e após isquemia em um modelo animal da lesão pulmonar de isquemiareperfusão. Métodos - Vinte e quatro ratos Wistar foram submetidos a um modelo experimental de clampeamento do hilo pulmonar esquerdo durante 45 minutos, seguido por 2 horas de reperfusão. Os animais foram divididos em quatro grupos: SHAM, isquemia-reperfusão (IR), N-acetilcisteína pré isquemia (NACPré) e NAC pós isquemia (NAC-Pós). Foram avaliados os parâmetros hemodinâmicos, gasométricos e histológicos. Foram analisadas a expressão protéica de iNOS, nitrotirosina, caspase 3 clivada e NF-қB (sub-unidade p65 fosforilada), IkB-R, TNF-R e expressão de IL-1S. A peroxidação lipídica foi avaliada pelas substâncias reativas ao ácido tiobarbitúrico (TBARS) e a atividade da enzima antioxidante superóxido dismutase (SOD). A infiltração de neutrófilos foi determinada por atividade de mieloperoxidase. Resultados - Não houve diferenças significativas nos parâmetros hemodinâmicos e gasométricos entre os grupos. Houve um aumento significativo na peroxidação lipídica nos grupos IR e NAC-Pré (p<0,01) quando comparado com SHAM e NAC-Pós. Não houve diferença na SOD entre os grupos. As expressões de NF-қB, TNF-R, IL-1S, nitrotirosina e caspase 3 clivada estavam significativamente aumentadas no grupo IR quando comparado ao SHAM e grupos NAC (p<0,01). O grupo NAC-Pré mostrou um aumento significativo na expressão dessas proteínas quando comparado com SHAM e NAC-Pós (p<0,01). A expressão de iNOS encontrava-se elevada em todos os grupos quando comparados ao SHAM (p<0,01). Conclusão - O uso intravenoso da NAC protege o pulmão contra a lesão de isquemia e reperfusão pulmonar. O seu uso reduz o dano provocado pelo estresse oxidativo, além disso esta substância apresenta propriedades antiinflamatórias e previne a apoptose. Quando utilizada logo após o final do periodo de isquemia, a NAC potencializa seus efeitos protetores mostrando-se este como o melhor período para sua administração.Objective - To verify the effects of N-acetylcysteine (NAC) administered before and after ischemia in an animal model of lung ischemia-reperfusion injury. Methods – Twenty-four Wistar rats were subjected to an experimental model of selective left pulmonary hilum clamping for 45 minutes followed by 2 hours of reperfusion. The animals were divided into four groups: SHAM, ischemiareperfusion (IR), N-acetylcysteine pre ischemia (NAC-Pre) and NAC post ischemia (NAC-Post) groups. We recorded the hemodynamic parameters, blood gas analysis and histology. We measured the iNOS, nitrotyrosine, cleaved caspase 3, NF-қB (sub-unit phospho p65), IkB-R, TNF-R and IL-1S expression. Lipid peroxidation was assessed by the thiobarbituric acid reactive substances (TBARS) assay and the activity of the antioxidant enzyme superoxide dismutase (SOD). Neutrophil infiltration was assayed by myeloperoxidase activity. Results - No significant differences were observed in hemodynamic parameters and blood gas analysis among the groups. Lipid peroxidation was significantly higher in IR and NAC-Pre groups (p<0.01). SOD activity had no difference among the groups. The expressions of NF-қB, TNF-R, IL-1S, Nitrotyrosine and Cleaved caspase 3 were significantly higher in the IR group when compared to SHAM and NAC groups (p<0.01). NAC-Pre group showed a significant higher expression of these proteins when compared to SHAM and NAC-Post groups (p<0.01). After reperfusion the expression of iNOS increased almost uniformly in all groups when compared to SHAM group (p<0.01). Conclusion - The intravenous administration of NAC demonstrated protective properties against lung IR injury. Its use reduces the damage produced by oxidative stress, has anti-inflammatory activity and prevents apoptosis. Furthermore, the use of NAC just after reperfusion potentiates its protective effects showing to be the more effective period for its administration

O efeito da n-acetilcisteína (NAC) sobre a lesão de isquemia e reperfusão pulmonar em ratos

Objetivo – Verificar os efeitos da N-acetilcisteína (NAC), administrada antes e após isquemia em um modelo animal da lesão pulmonar de isquemiareperfusão. Métodos - Vinte e quatro ratos Wistar foram submetidos a um modelo experimental de clampeamento do hilo pulmonar esquerdo durante 45 minutos, seguido por 2 horas de reperfusão. Os animais foram divididos em quatro grupos: SHAM, isquemia-reperfusão (IR), N-acetilcisteína pré isquemia (NACPré) e NAC pós isquemia (NAC-Pós). Foram avaliados os parâmetros hemodinâmicos, gasométricos e histológicos. Foram analisadas a expressão protéica de iNOS, nitrotirosina, caspase 3 clivada e NF-қB (sub-unidade p65 fosforilada), IkB-R, TNF-R e expressão de IL-1S. A peroxidação lipídica foi avaliada pelas substâncias reativas ao ácido tiobarbitúrico (TBARS) e a atividade da enzima antioxidante superóxido dismutase (SOD). A infiltração de neutrófilos foi determinada por atividade de mieloperoxidase. Resultados - Não houve diferenças significativas nos parâmetros hemodinâmicos e gasométricos entre os grupos. Houve um aumento significativo na peroxidação lipídica nos grupos IR e NAC-Pré (p<0,01) quando comparado com SHAM e NAC-Pós. Não houve diferença na SOD entre os grupos. As expressões de NF-қB, TNF-R, IL-1S, nitrotirosina e caspase 3 clivada estavam significativamente aumentadas no grupo IR quando comparado ao SHAM e grupos NAC (p<0,01). O grupo NAC-Pré mostrou um aumento significativo na expressão dessas proteínas quando comparado com SHAM e NAC-Pós (p<0,01). A expressão de iNOS encontrava-se elevada em todos os grupos quando comparados ao SHAM (p<0,01). Conclusão - O uso intravenoso da NAC protege o pulmão contra a lesão de isquemia e reperfusão pulmonar. O seu uso reduz o dano provocado pelo estresse oxidativo, além disso esta substância apresenta propriedades antiinflamatórias e previne a apoptose. Quando utilizada logo após o final do periodo de isquemia, a NAC potencializa seus efeitos protetores mostrando-se este como o melhor período para sua administração.Objective - To verify the effects of N-acetylcysteine (NAC) administered before and after ischemia in an animal model of lung ischemia-reperfusion injury. Methods – Twenty-four Wistar rats were subjected to an experimental model of selective left pulmonary hilum clamping for 45 minutes followed by 2 hours of reperfusion. The animals were divided into four groups: SHAM, ischemiareperfusion (IR), N-acetylcysteine pre ischemia (NAC-Pre) and NAC post ischemia (NAC-Post) groups. We recorded the hemodynamic parameters, blood gas analysis and histology. We measured the iNOS, nitrotyrosine, cleaved caspase 3, NF-қB (sub-unit phospho p65), IkB-R, TNF-R and IL-1S expression. Lipid peroxidation was assessed by the thiobarbituric acid reactive substances (TBARS) assay and the activity of the antioxidant enzyme superoxide dismutase (SOD). Neutrophil infiltration was assayed by myeloperoxidase activity. Results - No significant differences were observed in hemodynamic parameters and blood gas analysis among the groups. Lipid peroxidation was significantly higher in IR and NAC-Pre groups (p<0.01). SOD activity had no difference among the groups. The expressions of NF-қB, TNF-R, IL-1S, Nitrotyrosine and Cleaved caspase 3 were significantly higher in the IR group when compared to SHAM and NAC groups (p<0.01). NAC-Pre group showed a significant higher expression of these proteins when compared to SHAM and NAC-Post groups (p<0.01). After reperfusion the expression of iNOS increased almost uniformly in all groups when compared to SHAM group (p<0.01). Conclusion - The intravenous administration of NAC demonstrated protective properties against lung IR injury. Its use reduces the damage produced by oxidative stress, has anti-inflammatory activity and prevents apoptosis. Furthermore, the use of NAC just after reperfusion potentiates its protective effects showing to be the more effective period for its administration