Meshulam T, Billah M M, Eckel S, Griendling K K, Diamond R D
Section of Infectious Diseases, Department of Medicine and Evans Department of Clinical Research, Boston University Medical Center Hospital, Massachusetts.
J Leukoc Biol. 1995 Jun;57(6):842-50. doi: 10.1002/jlb.57.6.842.
Neutrophil (PMN) oxidant release, a key component of defenses against disseminated candidiasis, was preceded by oxidant generation after stimulation by Candida albicans hyphae. Opsonized or unopsonized hyphae triggered phospholipase D (PLD) activation within 5 or 30 s, respectively, forming 1-O-alkyl-phosphatidic acid (alkyl-PA) or 1-O-alkyl-phosphatidyl-ethanol in the presence of ethanol. Ethanol, which competitively lowers phosphatidic acid (PA) production, caused dose-dependent inhibition of superoxide (O2-) generation after hyphal stimulation but altered neither baseline-unstimulated O2- production nor responses to phorbol myristate acetate. PA rises evoked by unopsonized hyphae began 2 min before significant O2- release, also preceding both phospholipase C activation and cytosolic Ca2+ rises. Diacylglycerol (DAG) rose in two distinct phases after stimulation by opsonized or unopsonized hyphae, peaking briefly after 60 or 120 s, respectively, followed by prolonged secondary rises. Initial DAG rises preceded inositol triphosphate elevations evoked by unopsonized hyphae. Though PA rose before DAG, no dephosphorylation of PA to form 1-O-alkyl-DAG was noted. Propranalol, which increases PA accumulation by inhibiting PA phosphohydrolase, lowered PMN O2- responses to hyphae. Early DAG rises temporally overlapped respiratory burst initiation but PMN responses to hyphae were unchanged by a DAG kinase inhibitor, R59022, which blocks phosphorylation of DAG to PA and enhances DAG accumulation. Thus, neither PA nor DAG accumulation individually accounted for triggering PMN O2- responses to hyphae. PLD activation and PA production may facilitate PMN fungicidal responses to hyphae but play an indirect role in initiating the respiratory burst.
中性粒细胞（PMN）释放氧化剂是抵御播散性念珠菌病的关键组成部分，在白色念珠菌菌丝刺激后会先产生氧化剂。调理化或未调理化的菌丝分别在5秒或30秒内触发磷脂酶D（PLD）激活，在乙醇存在的情况下形成1-O-烷基磷脂酸（烷基-PA）或1-O-烷基磷脂酰乙醇。乙醇竞争性降低磷脂酸（PA）的产生，导致菌丝刺激后超氧化物（O2-）生成呈剂量依赖性抑制，但既不改变基线未刺激时的O2-产生，也不改变对佛波酯肉豆蔻酸酯乙酸盐的反应。未调理化菌丝引起的PA升高在显著的O2-释放前2分钟开始，也先于磷脂酶C激活和细胞质Ca2+升高。在调理化或未调理化菌丝刺激后，二酰基甘油（DAG）在两个不同阶段升高，分别在60秒或120秒后短暂达到峰值，随后是长时间的二次升高。未调理化菌丝引起的肌醇三磷酸升高之前，DAG会先出现初始升高。尽管PA在DAG之前升高，但未观察到PA去磷酸化形成1-O-烷基-DAG。普萘洛尔通过抑制PA磷酸水解酶增加PA积累，降低了PMN对菌丝的O2-反应。早期DAG升高在时间上与呼吸爆发启动重叠，但DAG激酶抑制剂R59022（可阻断DAG磷酸化为PA并增强DAG积累）对PMN对菌丝的反应没有影响。因此，PA和DAG积累单独都不能解释触发PMN对菌丝的O2-反应。PLD激活和PA产生可能促进PMN对菌丝的杀真菌反应，但在启动呼吸爆发中起间接作用。
