TLR4激活的血小板附着到嗜中性粒细胞上从而导致嗜中性粒细胞胞外杀菌网络(neutrophil extracellular traps, NETs)形成,图片来自Nature Medicine, 2007 Apr; 13(4):463-9,在此引用仅作研究之用,版权归Kubes P.所有。
英国伯明翰大学科学家发现一种方法来触发体内被称作嗜中性粒细胞的保护性白细胞产生一种强有力的抗细菌感染DNA“蜘蛛”网。
伯明翰大学牙医学院研究人员使用次氯酸(Hypochlorous acid, HOCl)让病人嗜中性粒细胞产生这种被称作嗜中性粒细胞胞外杀菌网络(neutrophil extracellular traps, NETs)的“蜘蛛”网,其中这些病人患有一种特殊疾病即慢性肉芽肿病(chronic granulomatous disease, CGD)而使得他们的嗜中性粒细胞在自然条件下不能够产生这种胞外杀菌网络。相关研究结果发表在2012年2月那期Clinical and Experimental Immunology期刊上。
最近研究已经表明当嗜中性粒细胞---形成体内抵抗细菌感染的第一道防御线的白细胞---遭受着细菌的大量攻击时,这些细胞以一种特异性控制的方式开始死亡。作为最后一搏,它们释放来自自身细胞核内的全部DNA到周围组织。正是这种DNA形成粘性的“蜘蛛”网,而且这种网一旦捕捉住细菌,就利用它含有的酶来破坏它们。
伯明翰大学牙周研究小组教授Iain Chapple和博士Paul Cooper领导的一个科学家研究团队发现次氯酸刺激CGD病人产生嗜中性粒细胞胞外杀菌网络。他们也发现“牛磺酸(taurine)”降低这种胞外杀菌网络形成,因而可能延长嗜中性粒细胞存活。
Chapple教授评论道:“我们对这种胞外杀菌网络在抵抗导致牙周病(periodontal disease)发生的细菌过程中所起的作用感到兴趣,不过关于胞外杀菌网络形成的基础生物学特征对很多传染性免疫疾病而言是共同的。”
“我们知道这种胞外杀菌网络形成需要氧自由基,但是CGD病人的嗜中性粒细胞不能有效地产生氧自由基,因而不能够产生该胞外杀菌网络,或者说不能对某些感染作出反应。这项研究有助于我们更多一点理解这些过程,而且可能在未来导致人们开发出新的治疗策略来增加或者在某些情形下降低这种胞外杀菌网络形成。”
不过研究人员也特别强调关于嗜中性粒细胞胞外杀菌网络的多种矛盾之处。“在一些病人当中,这种胞外杀菌网络似乎在杀死细菌中起着非常重要的作用”,Professor Chapple报道,“但是在其他一些病人当中,他们似乎产生自身抗体对抗该胞外杀菌网络中的组分,从而与某些免疫介导的疾病如类风湿性关节炎和自身免疫血管炎相关联在一起。因此,对一些病人而言,这种胞外杀菌网络可能是一把双刃剑,不过当前关于这个免疫控制新领域的研究正在如火如荼地开展,因而激动人心的发现将在接下来的5到10年内纷沓而来。” (生物谷:towersimper编译)
doi:10.1111/j.1365-2249.2011.04518.x
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Hypochlorous acid regulates neutrophil extracellular trap release in humans
L. J. Palmer, P. R. Cooper, M. R. Ling, H. J. Wright, A. Huissoon, I. L. C. Chapple
Neutrophil extracellular traps (NETs) comprise extracellular chromatin and granule protein complexes that immobilize and kill bacteria. NET release represents a recently discovered, novel anti-microbial strategy regulated non-exclusively by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase generation of reactive oxygen intermediates (ROIs), particularly hydrogen peroxide. This study aimed to characterize the role of ROIs in the process of NET release and to identify the dominant ROI trigger. We employed various enzymes, inhibitors and ROIs to record their effect fluorometrically on in vitro NET release by human peripheral blood neutrophils. Treatment with exogenous superoxide dismutase (SOD) supported the established link between hydrogen peroxide and NET production. However, treatment with myeloperoxidase inhibitors and direct addition of hypochlorous acid (HOCl; generated in situ from sodium hypochlorite) established that HOCl was a necessary and sufficient ROI for NET release. This was confirmed by the ability of HOCl to stimulate NET release in chronic granulomatous disease (CGD) patient neutrophils which, due to the lack of a functional NADPH oxidase, also lack the capacity for NET release in response to classical stimuli. Moreover, the exogenous addition of taurine, abundantly present within the neutrophil cytosol, abrogated NET production stimulated by phorbol myristate acetate (PMA) and HOCl, providing a novel mode of cytoprotection by taurine against oxidative stress by taurine.