Pro-apoptotic role of NF-κB pathway inhibition in lipopolysaccharide-stimulated polymorphonuclear neutrophils

Objective To investigate the role of nuclear factor kappa B (NF-κB) pathway inhibition in lipopolysaccharide (LPS)-stimulated apoptosis of polymorphonuclear neutrophils (PMNs).Methods Rats with acute lung injury induced by LPS intratracheal instillation and cultured human venous PMNs were studied. Pyrrolidine dithiocarbamate (PDTC) and gliotoxin were used as NF-κB inhibitors. Additionally,to explore the role of extracellularly regulated protein kinase as an upstream signal in NF-κB pathway on regulating LPS-stimulated PMN apoptosis,PD098059,the specific inhibitor of extracellularly regulated protein kinase,was also applied. The lung injury was determined by protein content and PMN numbers in bronchoalveolar lavage fluid. PMN apoptosis was measured by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) end labeling and DNA fragmentation. IκBα degradation was analyzed by Western blot. NF-κB DNA binding activity was detected by an electrophoretic mobility shift assay.Results (1) The increase of protein content and PMN numbers in bronchoalveolar lavage fluid induced by LPS (100 μg per rat) intratracheal instillation were alleviated by PDTC (50,100,or 200 mg/kg,i.p.) in a dose-dependent manner. (2) PMNs apoptosis in vivo or in vitro was delayed by LPS,and accelerated by PDTC,gliotoxin or PD098059 pretreatment. (3) IκBα degradation and increased NF-κB DNA binding activity mediated by LPS were inhibited by PDTC,gliotoxin or PD098059 pretreatment.Conclusion Inhibition of either NF-κB itself or the upstream signals in NF-κB pathway such as extracellularly regulated protein kinases has therapeutic effect on LPS-induced acute lung injury,in which the dysregulation of PMN apoptosis plays an important role.

PMN apoptosis and its relationship with the lung injury after chest impact trauma

Background Polymorphonuclear neutrophil (PMN),one of the most important inflammatory cells,functions throughout the initiation,progression and resolution of inflammation. This study aimed at investigating the relationship between PMN apoptosis and the lung injury after chest impact trauma. Methods PMNs were purified from rabbits subjected to the chest impact trauma and their apoptosis,necrosis,survival and respiratory burst were detected by flow cytometry. Meanwhile,lactate dehydrogenase and (LDH) [Ca 2+ ]i were measured. Results The delayed apoptosis of PMNs in bronchoalveolar lavage fluid was observed from 2 hours to 12 hours after trauma,and viable cells increased. Respiratory burst of PMNs in bronchoalveolar lavage fluid was increased significantly from 2 hours with the peak at 8 hours. Meanwhile,lactate dehydrogenase in bronchoalveolar lavage fluid was higher than that in control ( P <0.05) from 4 hours to 24 hours,and intracellular free Ca 2+ in PMN was increased temporarilly. Conclusions Retention of PMN in tissues and the abnormality in apoptotic pathway inevitably generate persistent activation of PMN and excessive release of toxic substances,resulting in tissue injury. The temporary increase of intracellular free Ca 2+ may be responsible for the delayed apoptosis of PMN.

Corticosteroid resistance in chronic obstructive pulmonary disease： new uses of theophylline

Chronic obstructive pulmonary disease （COPD） is a major global health problem with a rising morbidity and mortality, which is expected to account for about 27% of tobacco related deaths and is anticipated to move from the fifth to the fourth leading cause of death worldwide from 2002 to 2030.1 COPD is characterized by the abnormal and chronic inflammation induced by cigarette smoking and other inflammatory insults in both small airway and lung parenchyma.2＇3 Glucocorticosteroids （also called glucocorticoids, corticosteroids or steroids） are the most effective anti-inflammatory drugs available for the treatment of many chronic inflammatory and immune diseases.