Haddox J L, Pfister R R, Sommers C I, Blalock J E, Villain M
Eye Research Laboratories, Sight Savers of Alabama, Birmingham 35209, USA.
Invest Ophthalmol Vis Sci. 2001 Nov;42(12):2769-75.
Two tripeptide chemoattractants, acetyl-proline-glycine-proline (Ac-PGP) and methyl-proline-glycine-proline (Me-PGP), are the primary triggers for early neutrophil invasion into the alkali-injured cornea. In the present study the effectiveness of a complementary peptide designed to inhibit the PGP chemoattractants (arginine-threonine-arginine [RTR] tetrameric peptide) and an apo A-1 mimicking peptide (5F) was investigated in the alkali-injured rabbit eye.
(L)-RTR tetramer, (D)-RTR tetramer, and 5F were tested in vitro for their effects on neutrophil polarization. Synthetic 5F was also tested in vitro for its effect on the neutrophil respiratory burst. In the alkali-injured rabbit eye model, the right corneas of 48 rabbits were exposed to 1 N NaOH for 35 seconds. Sixteen animals were randomly assigned to each of three groups: phosphate-buffered saline (PBS) control; 800 microM RTR (dextrorotatory) tetramer in PBS alternating each hour with 1.5 mM RTR (levorotatory) tetramer in PBS; and 12 microM 5F in PBS. One topical drop of each substance was administered hourly (14 times per day) for 33 days. The experiment was continued until day 42 with no additional drops administered.
(L)-RTR tetramer and (D)-RTR tetramer inhibited neutrophil polarization activated by the PGP chemoattractants in vitro. Synthetic 5F did not inhibit neutrophil polarization in the presence of Ac-PGP or the respiratory burst of neutrophils in the presence of a metabolic stimulant derived from alkali-degraded corneas. During the entire animal experiment, statistically fewer ulcers occurred in the RTR tetramer group than in the PBS control group (43.8% vs. 87.5%, P = 0.0046). The frequency of ulceration in the 5F group (68.8%) was not significantly different from the PBS control group.
The reduction in the frequency of corneal ulceration by the RTR tetramer possibly resulted from its complementary binding to Ac-PGP and Me-PGP in the cornea shortly after alkali injury, leading to a reduction in the early and late infiltration of neutrophils. RTR tetramer appears to hold enough promise to warrant additional study as a therapeutic drug for the alkali-injured eye.
两种三肽趋化因子，乙酰 - 脯氨酸 - 甘氨酸 - 脯氨酸（Ac - PGP）和甲基 - 脯氨酸 - 甘氨酸 - 脯氨酸（Me - PGP），是中性粒细胞早期侵入碱烧伤角膜的主要触发因素。在本研究中，研究了一种设计用于抑制PGP趋化因子的互补肽（精氨酸 - 苏氨酸 - 精氨酸[RTR]四聚体肽）和一种载脂蛋白A - 1模拟肽（5F）在碱烧伤兔眼中的有效性。
在体外测试（L）-RTR四聚体、（D）-RTR四聚体和5F对中性粒细胞极化的影响。还在体外测试了合成的5F对中性粒细胞呼吸爆发的影响。在碱烧伤兔眼模型中，48只兔的右眼暴露于1 N氢氧化钠35秒。16只动物被随机分配到三个组中的每组：磷酸盐缓冲盐水（PBS）对照组；在PBS中每小时交替使用800 microM RTR（右旋）四聚体和在PBS中的1.5 mM RTR（左旋）四聚体；以及在PBS中的12 microM 5F。每小时（每天14次）给予每种物质一滴，持续33天。实验持续到第42天，不再额外给药。
（L）-RTR四聚体和（D）-RTR四聚体在体外抑制了PGP趋化因子激活的中性粒细胞极化。在存在Ac - PGP的情况下，合成的5F没有抑制中性粒细胞极化，在存在来自碱降解角膜的代谢刺激物的情况下，也没有抑制中性粒细胞的呼吸爆发。在整个动物实验期间，RTR四聚体组发生溃疡的统计学数量少于PBS对照组（43.8%对87.5%，P = 0.0046）。5F组的溃疡频率（68.8%）与PBS对照组没有显著差异。
RTR四聚体使角膜溃疡频率降低可能是由于其在碱损伤后不久与角膜中的Ac - PGP和Me - PGP互补结合，导致中性粒细胞的早期和晚期浸润减少。RTR四聚体似乎有足够的前景，值得作为碱烧伤眼的治疗药物进行进一步研究。
