Weiss C A, Wasiluk K R, Kellogg T A, Dunn D L
Department of Surgery, University of Minnesota, Minneapolis 55455, USA.
Surgery. 2000 Aug;128(2):339-44. doi: 10.1067/msy.2000.108061.
Release of lipopolysaccharide (endotoxin, LPS) is a critical inciting event in the development of sepsis syndrome due to gram-negative bacteria, and mortality associated with this entity remains approximately 40%. Limulus anti-LPS factor (LALF) is a naturally occurring horseshoe crab derived protein that, unlike antibiotics, is both bactericidal for gram-negative bacteria and capable of neutralizing LPS. We hypothesized that a peptide derived from the active domain of LALF (LALF #28-54) would exhibit potent biologic activity similar to that of LALF itself and could potentially be useful as a therapeutic agent.
The effects of LALF, synthetic peptide LALF #28-54, polymyxin B (PmB), and a biologically inactive synthetic peptide were examined in several models. In vitro bactericidal activity was determined against Pseudomonas aeruginosa, and LPS-neutralizing capacity was determined via inhibition of LPS-induced tumor necrosis factor-alpha (TNF-alpha) secretion by RAW 264.7 cells. In vivo biologic activity was determined via pretreatment following which P aeruginosa endotoxemia or bacteremia was induced; serum TNF-alpha levels, bacterial clearance, and survival were assessed.
LALF and LALF #28-54 exhibited potent in vitro bactericidal and LPS-neutralizing activity comparable to PmB (P <.01). However, although LALF #28-54 diminished systemic TNF-alpha production and aided bacterial clearance similar to that observed for LALF (P <.01), it did not provide significant protective capacity (P >.1).
These data demonstrate that peptide LALF #28-54 retained the LPS-neutralizing and bactericidal biologic activity of LALF but failed to protect during overwhelming P aeruginosa bacteremia, perhaps due to short serum half-life.
脂多糖（内毒素，LPS）的释放是革兰氏阴性菌所致脓毒症综合征发生过程中的关键激发事件，与此相关的死亡率仍约为40%。鲎抗LPS因子（LALF）是一种天然存在的源自鲎的蛋白质，与抗生素不同，它对革兰氏阴性菌具有杀菌作用且能够中和LPS。我们推测，源自LALF活性结构域的一种肽（LALF #28 - 54）将表现出与LALF本身相似的强大生物活性，并可能作为一种治疗药物发挥作用。
在多个模型中检测了LALF、合成肽LALF #28 - 54、多粘菌素B（PmB）及一种无生物活性的合成肽的作用。测定了对铜绿假单胞菌的体外杀菌活性，并通过抑制RAW 264.7细胞分泌LPS诱导的肿瘤坏死因子-α（TNF-α）来测定LPS中和能力。通过预处理后诱导铜绿假单胞菌内毒素血症或菌血症来测定体内生物活性；评估血清TNF-α水平、细菌清除率和生存率。
LALF和LALF #28 - 54表现出与PmB相当的强大体外杀菌和LPS中和活性（P <.01）。然而，尽管LALF #28 - 54与LALF一样减少了全身TNF-α的产生并有助于细菌清除（P <.01），但它并未提供显著的保护能力（P >.1）。
这些数据表明，肽LALF #28 - 具有LALF的LPS中和及杀菌生物活性，但在严重的铜绿假单胞菌菌血症期间未能起到保护作用，这可能是由于血清半衰期较短所致。
