Banca de DEFESA: DANIELBA ALMEIDA DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : DANIELBA ALMEIDA DA SILVA
DATA : 05/07/2019
HORA: 08:00
LOCAL: IMS/CAT - UFBA
TÍTULO:

In vitro and in vivo effects of the nitroxide tempol on inflammation and redox stress induced by acute exposure to cigarette smoke.

PALAVRAS-CHAVES:

Tempol, cigarette smoke, Nrf2, acute inflammation, redox stress.

PÁGINAS: 100
GRANDE ÁREA: Ciências da Saúde
ÁREA: Farmácia
RESUMO:

Cigarette smoke is a complex mixture of more than 6000 different chemicals substances. In the lung, these components can directly or indirectly trigger inflammation and redox stress, characteristic of some pulmonary diseases, including Chronic Obstructive Pulmonary Disease. Tempol (4-hydroxy-2,2,6,6-tetramethyl piperidine-1-oxyl) and other cyclic nitroxides reduce tissue injury associated with inflammation by mechanisms that are not fully understood. In the literature there is no report on the effects of tempol on lung injury caused by cigarette smoke as well as its involvement in the activation of the Nrf2 pathway. In this context, this study aimed to evaluate the in vitro and in vivo effect of tempol on inflammation and redox stress induced by acute exposure to cigarette smoke. C57BL/6 (n=32) were assigned to four groups (n = 8 each): 1) control exposed to ambient air (CG), 2) mice exposed to cigarette smoke for 5 days (CSG), mice treated 3) preventively or 4) therapeutically with tempol (50 mg/kg/day) and exposed to cigarette smoke for 5 days (TP50+CS and TT50+CS, respectively). The animals were euthanized after 24 h of last exposure to cigarette smoke, and bronchoalveolar lavage and lungs were collected for further analysis. The number of total leukocytes and neutrophils as well as myeloperoxidase concentration and activity increased in the respiratory tract and lung parenchyma of mice exposed to cigarette smoke. As consequence, there was an increase in lipid peroxidation, and nitration and carbonylation of lung proteins. Administration of tempol before or during exposure to cigarette smoke inhibited 60-80% all of the above parameters. Tempol also reduced inflammatory cytokines expression IL-6, IL-1β and IL-17 for basal levels and TNF-α by approximately 50%. On the other hand, IL-10, TGF-β transcription, and activation Nrf2 pathway markers, heme oxygenase 1 (HO-1) and GPx2 increased significantly in the mice treated preventively and therapeutically with the nitroxide, which reflected a higher activity of glutathione peroxidase in the lung homogenate. Then, the effects of tempol were evaluated on intracellular redox state, nitric oxide synthase activity and HO-1 expression in RAW 264.7 murine macrophages. When RAW 264.7 cells were preincubated with tempol (25, 50 and 100 μM) for 24 h and stimulated with cigarette smoke extract, the intracellular oxidation of dichlorofluorescein was reduced in a concentration dependent manner, although nitrite and nitrate concentrations, indirect marker of nitric oxide synthase activity, did not change. In the cells treated with tempol (50 and 100 μM) for 24 h, HO-1 levels increased according to SDS-PAGE / Western Blotting. Collectively, these data indicate that tempol protects cells and tissues against oxidative damage and inflammation on exposure to cigarette smoke probably through the activation of the Nrf2 pathway.

MEMBROS DA BANCA:
Interno - 1112111 - AMELIA CRISTINA MENDES DE MAGALHAES GUSMAO
Externo à Instituição - FLÁVIA VIANA SANTA CECÍLIA
Presidente - 011.632.625-52 - RAPHAEL FERREIRA QUEIROZ - USP