Medical Research Council Centre for Developmental and Biomedical Genetics, University of Sheffield, Sheffield, United Kingdom.
PLoS One. 2011 Jan 6;6(1):e15768. doi: 10.1371/journal.pone.0015768.
Human tissue inflammation is terminated, at least in part, by the death of inflammatory neutrophils by apoptosis. The regulation of this process is therefore key to understanding and manipulating inflammation resolution. Previous data have suggested that the short-lived pro-survival Bcl-2 family protein, Mcl-1, is instrumental in determining neutrophil lifespan. However, Mcl-1 can be cleaved following caspase activity, and the possibility therefore remains that the observed fall in Mcl-1 levels is due to caspase activity downstream of caspase activation, rather than being a key event initiating apoptosis in human neutrophils.We demonstrate that apoptosis in highly purified neutrophils can be almost completely abrogated by caspase inhibition with the highly effective di-peptide caspase inhibitor, Q-VD.OPh, confirming the caspase dependence of neutrophil apoptosis. Effective caspase inhibition does not prevent the observed fall in Mcl-1 levels early in ultrapure neutrophil culture, suggesting that this fall in Mcl-1 levels is not a consequence of neutrophil apoptosis. However, at later timepoints, declines in Mcl-1 can be reversed with effective caspase inhibition, suggesting that Mcl-1 is both an upstream regulator and a downstream target of caspase activity in human neutrophils.
人类组织炎症的终止，至少部分是通过凋亡使炎性中性粒细胞死亡。因此，该过程的调节是理解和操纵炎症消退的关键。先前的数据表明，短寿命的促生存 Bcl-2 家族蛋白 Mcl-1 对于确定中性粒细胞寿命至关重要。然而，Mcl-1 可以在 caspase 活性后被切割，因此仍然存在这样的可能性，即观察到的 Mcl-1 水平下降是由于 caspase 激活下游的 caspase 活性，而不是作为引发人中性粒细胞凋亡的关键事件。我们证明，用高效的二肽 caspase 抑制剂 Q-VD.OPh 抑制 caspase 活性几乎可以完全阻断高度纯化的中性粒细胞中的凋亡，从而证实了 caspase 对中性粒细胞凋亡的依赖性。有效的 caspase 抑制并不能阻止在超纯中性粒细胞培养的早期观察到的 Mcl-1 水平下降，这表明 Mcl-1 水平的下降不是中性粒细胞凋亡的结果。然而，在稍后的时间点，有效的 caspase 抑制可以逆转 Mcl-1 的下降，这表明 Mcl-1 既是人中性粒细胞中 caspase 活性的上游调节剂，也是下游靶标。
