Pharmacological Inhibition of 5-Lipoxygenase Accelerates and Enhances Fracture-Healing
Pharmacological Inhibition of 5-Lipoxygenase Accelerates and Enhances Fracture-Healing
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DOI：
10.2106/jbjs.h.01844
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发表时间：
2009-11-01
影响因子：
5.3
通讯作者：
O'Connor, J. Patrick
中科院分区：
文献类型：
--
作者：
Cottrell, Jessica A.;O'Connor, J. Patrick
背景：环氧合酶-2活性的丧失在动物模型中损害骨愈合，在人类中抑制异位骨化。环氧合酶-2是花生四烯酸转化为洋地黄素的限速酶。花生四烯酸也是5-脂氧合酶的底物，5-脂氧合酶催化白三烯合成的初始步骤。与环氧合酶-2相反，5-脂氧合酶的基因消融加速并增强小鼠的再愈合。本研究的目的是确定是否与口服药物的5-脂氧合酶的全身抑制可以加速arterre-healing.Methods：闭合性股骨骨折在Sprague-Dawley大鼠。大鼠经口给予溶剂（95只大鼠）、塞来昔布（59只大鼠）或AA-861（5-脂氧合酶抑制剂; 89只大鼠）。骨折愈合的测量：1使用X线片，组织形态学，生物力学测试。结果：AA-861处理后骨痂细胞增殖时间缩短，早期软骨形成时间明显增加，早期软骨形成时间明显延长（5.6倍; p < 0.001）末端骨形成（4.2倍; p = 0.015），并且与载体处理的大鼠骨折相比显著增加了骨痂机械性能。骨折后第2天，AA-861处理的愈伤组织细胞增殖率高于溶剂处理（3.68%对2.08%; p < 0.001; 95%置信区间，-2.81至-0.039），但在骨折后第4天，塞来昔布治疗降低了（4.22%对1.84%; p < 0.001; 95%置信区间，2.27 - 4.07）。骨折后第10天，AA-861和塞来昔布治疗使II型胶原mRNA水平增加（分别为16.0倍和6.1倍;两者p < 0.001），但只有AA-861治疗导致X型胶原mRNA增加（6.3倍; p < 0.001）。AA-861治疗显著增加环氧合酶-2（第10天为4.0倍; p < 0.001）和骨桥蛋白mRNA水平（第7天为3.6倍; p = 0.024），同时降低5-脂氧合酶mRNA水平（第4天为5.6倍; p < 0.001）。在该大鼠模型中，口服药物全身抑制5-脂氧合酶显著加速和增强了溃疡愈合。基因表达分析表明，环氧合酶-2是必要的愈伤组织软骨细胞向肥大的进展，以完成软骨内骨化。相反，5-脂氧合酶的抑制改变炎症反应，从而增强愈伤组织软骨细胞肥大并加速软骨内骨化。
Background: Loss of cyclooxygenase-2 activity is known to impair fracture-healing in animal models and to inhibit heterotopic ossification in humans. Cyclooxygenase-2 is the rate-limiting enzyme involved in the conversion of arachidonic acid into prostaglandins. Arachidonic acid also is a substrate for 5-lipoxygenase, which catalyzes the initial steps in leukotriene synthesis. In contrast to cyclooxygenase-2, genetic ablation of 5-lipoxygenase accelerates and enhance:; fracture-healing in mice. The goal of this study was to determine if systemic inhibition of 5-lipoxygenase with an orally delivered drug could accelerate fracture-healing.Methods: Closed femoral fractures were made in Sprague-Dawley rats. The rats were treated with oral doses of vehicle (ninety-five rats), celecoxib (fifty-nine rats), or AA-861 (a 5-lipoxygenase inhibitor; eighty-nine rats). Fracture-healing was measure:1 with use of radiographs, histomorphometry, and biomechanical testing. Effects of drug treatments on callus cell proliferation and gene expression were determined by incorporation of bromodeoxyuridine and quantitative polymerase chain reactions, respectively.Results: AA-861 treatment decreased fracture-bridging time, significantly increased early callus cartilage (5.6-fold; p < 0.001) end bone formation (4.2-fold; p = 0.015), and significantly increased callus mechanical properties compared with the vehicle-treated rat fractures. Callus cell proliferation rate was increased by AA-861 treatment, compared with vehicle, at day 2 after fracture (3.68% compared with 2.08%; p < 0.001; 95% confidence interval, -2.81 to -0.039) but was reduced by celecoxib treatment at day 4 after fracture (4.22% compared with 1.84%; p < 0.001; 95% confidence interval, 2.27 to 4.07). At day 10 after fracture, AA-861 and celecoxib treatment increased Type-II collagen mRNA levels (16.0-fold and 6.1-fold, respectively; p < 0.001 for both), but only AA-861 treatment caused an increase in Type-X collagen mRNA (6.3-fold; p < 0.001). AA-861 treatment significantly increased cyclooxygenase-2 (4.0-fold at day 10; p < 0.001) and osteopontin mRNA levels (3.6-fold at day 7; p = 0.024), while decreasing 5-lipoxygenase mRNA levels (5.6-fold at day 4; p < 0.001).Conclusions: Systemic inhibition of 5-lipoxygenase with an orally delivered drug significantly accelerated and enhanced fracture-healing in this rat model. Gene expression analysis indicates that cyclooxygenase-2 is necessary for callus chondrocytes to progress into hypertrophy so as to complete endochondral ossification. Conversely, inhibition of 5-lipoxygenase alters the inflammatory response, which enhances callus chondrocyte hypertrophy and accelerates endochondral ossification.