benzyloxycarbonylvalyl-alanyl-aspartyl-fluoromethyl-ketone and Pulmonary-Disease--Chronic-Obstructive

Smoking can lead to airway inflammation and mucus secretion through the nucleotide-binding domain-like receptor protein 3/caspase-1 pathway. In this study, z-VaD-Ala-Asp-fluoromethyl ketone(Z-VAD), a pan-caspase inhibitor, and acetyl-Asp-Glu-Val-Asp-aldehyde(Ac-DEVD), a caspase-3 inhibitor, were used to investigate the effect of caspase inhibitors on the expression of interleukin(IL)-1β and IL-8, airway inflammation, and mucus secretion in mice exposed to cigarette smoke(CS).. Thirty-two C57BL/6J male mice were divided into a control group, Smoke group, Z-VAD group, and Ac-DEVD group. Except for the control group, the animals were all exposed to CS for three months. After the experiment, lung function was measured and hematoxylin and eosin staining and periodic acid-Schiff staining were performed. The levels of IL-1β, IL-8, and mucin 5ac(Muc5ac) in serum and bronchoalveolar lavage fluid(BALF) were determined by enzyme-linked immunosorbent assay.. Compared with the control group, the lung function of mice exposed to smoke was poorer, with a large number of inflammatory cells infiltrating around the airway, collapse of alveoli, expansion and fusion of distal alveoli, and formation of emphysema. The Z-VAD group was relieved compared with the smoke group. Airway inflammation was also reduced in the Ac-DEVD group compared with the Smoke group, but the degree of emphysema was not significantly improved. Although Z-VAD relieved airway inflammation and emphysema, Ac-DEVD only relieved inflammation. Z-VAD and Ac-DEVD decreased serum IL-1β and IL-8 levels. In BALF, IL-1β was decreased in Z-VAD group and IL-8 was highest in Smoke +Ac-DEVD group compared with control group and Ac-DEVD group. There was no significant difference in the expression of Muc5ac in serum. However, in BALF, levels of Muc5ac were higher in the smoking group and the lowest in the Ac-DEVD group.. Mice exposed to smoke had decreased lung function and significant cilia lodging, epithelial cell shedding, and inflammatory cell infiltration, with significant emphysema formation. The pan-caspase inhibitor, Z-VAD, improved airway inflammation and emphysema lesions in the mice exposed to smoke and reduced IL-1β and IL-8 levels in serum. The caspase-3 inhibitor, Ac-DEVD, reduced airway inflammation, serum IL-1β and IL-8 levels, and Muc5ac levels in BALF, but it did not improve emphysema.

Topics: Animals; Caspase 3; Cigarette Smoking; Inflammation; Interleukin-8; Male; Mice; Mice, Inbred C57BL; Mucus; Pulmonary Disease, Chronic Obstructive; Pulmonary Emphysema

Neutrophils are the primary inflammatory cell in smokers' lungs, but little is known about the ability of cigarette smoke to modulate neutrophil function. Neutrophils undergo caspase-3-dependent spontaneous, as well as phagocytosis-induced, apoptosis. This study investigated the ability of cigarette smoke extract (CSE) to alter neutrophil caspase-3 activity, apoptosis, and phagocytosis. CSE treatment resulted in a dramatic suppression of neutrophil caspase-3-like activity, which correlated with reduced cleavage of glutamate-L-cysteine ligase catalytic subunit, a known target of active caspase-3. CSE did not affect procaspase-3 processing to its active fragment, suggesting a direct effect of CSE on active caspase-3. Consistent with this, CSE inhibited active recombinant caspase-3 activity, which was abolished by dithiothreitol, suggesting a redox-sensitive mechanism. CSE-induced suppression of caspase-3 activity did not alter spontaneous apoptosis but did impair phagocytic activity. Since CSE treatment resulted in profound suppression of caspase-3 activity but did not alter apoptosis, the possibility of a threshold level of caspase-3 activity was investigated. CSE reduced caspase-3 activity in a concentration-dependent manner. Despite near complete suppression of caspase-3 activity, spontaneous apoptosis was not altered. Conversely, treatment with the pan-caspase inhibitor, Z-Val-Ala-Asp-fluoromethylketone, reduced spontaneous apoptosis. These data demonstrate that CSE does not suppress caspase-3 activity below a threshold level to prevent spontaneous apoptosis, but the level of inhibition is sufficient to impair neutrophil phagocytic activity. These divergent functions of caspase-3 may contribute to the persistence of neutrophils in the lungs of smokers, as well as be a factor in their higher incidence of community-acquired pneumonia.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; Caspase 3; Caspase Inhibitors; Cysteine Proteinase Inhibitors; Humans; In Vitro Techniques; Neutrophils; Phagocytosis; Pulmonary Disease, Chronic Obstructive; Smoking; Tobacco Smoke Pollution