Delayed apoptosis by neutrophils from COPD patients is associated with altered Bak, Bcl-xl, and Mcl-1 mRNA expression.
BACKGROUND
Delayed neutrophil apoptosis may be an important factor in the persistent inflammation associated with chronic obstructive pulmonary disease (COPD). Bcl-2 family proteins are important regulators of neutrophil apoptosis. We determined the mRNA levels of pro-apoptotic Bak and anti-aptototic Bcl-xl and Mcl-1 members of the Bcl-2 family in unstimulated peripheral blood neutrophils from patients with mild to moderate COPD and compared these to neutrophils from healthy controls.


METHODS
Neutrophils were isolated from peripheral blood samples of 47 COPD patients (smokers: N = 24) and 47 healthy controls (smokers: N = 24). Percentages of apoptotic cells were determined at 4, 24, and 36 h for unstimulated neutrophils cultured in vitro. Neutrophil mRNA expression of Bak, Bcl-xl, and Mcl-1 was determined by real-time polymerase chain reaction (PCR). FEV1 (% predicted) and FVC were determined by spirometry and correlations between mRNA levels and lung function parameters were determined.


RESULTS
The percentages of apoptotic cells among unstimulated neutrophils from COPD patients were significantly lower compared to cells from controls after 4, 24, and 36 h in culture; smoking history had only a minimal effect on these differences. Unstimulated neutrophils from COPD patients had significantly lower Bak mRNA expression and higher expressions of Bcl-xl and Mcl-1 mRNA than cells from healthy controls. Again, smoking history had only a minimal effect on these trends. Bak mRNA expression was significantly positively correlated with both % predicted FEV1 and the FEV1/FVC ratio, while Bcl-xl and Mcl-1 mRNA expressions were significantly negatively correlated with %predicted FEV1 and the FEV1/FVC ratio.


CONCLUSIONS
The genes for pro-apoptotic Bak, and anti-apoptotic Bcl-xl and Mcl-1 may be important in regulating the delayed neutrophil apoptosis observed in COPD, which may contribute to COPD pathogenesis.
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Hangzhou Xiasha Hospital, Hangzhou, China.
Jisong
J
Zhang
Jian
J
He
Jingwen
J
Xia
Zhen
Z
Chen
Xiaodong
X
Chen
D000368:Aged; D017209:Apoptosis / Q000235:genetics*; D016022:Case-Control Studies; D002478:Cells, Cultured; D016009:Chi-Square Distribution; D005260:Female; D005541:Forced Expiratory Volume; D005786:Gene Expression Regulation; D006801:Humans; D008168:Lung / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D018375:Neutrophil Activation; D009504:Neutrophils / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics*; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000235:genetics* / Q000276:immunology / Q000473:pathology / Q000503:physiopathology; D012333:RNA, Messenger / Q000378:metabolism*; D012720:Severity of Illness Index; D012907:Smoking / Q000009:adverse effects; D013147:Spirometry; D013997:Time Factors; D014797:Vital Capacity; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000235:genetics*; D051020:bcl-X Protein / Q000235:genetics*
C494772:BAK1 protein, human; C494811:BCL2L1 protein, human; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051020:bcl-X Protein