Reid Colm J, Thompson Laura, Donnelly Samantha, Deaton Christopher M, Marlin David J, Carrington Stephen D, Irwin Jane A
Veterinary Sciences Centre, School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
Res Vet Sci. 2009 Aug;87(1):20-5. doi: 10.1016/j.rvsc.2008.11.002. Epub 2008 Dec 21.
Recurrent airway obstruction (RAO) is a chronic inflammatory condition in equine lung, which may share a common immunological basis with human asthma, in which dysregulated Th2 responses occur. Mammals express chitinases and chitinase-like proteins, two of which are active enzymes, chitotriosidase and acidic mammalian chitinase (AMCase). Both enzymes are upregulated in a range of inflammatory conditions, including asthma. We investigated the activity of chitinase in bronchoalveolar lavage fluid from horses with and without RAO in response to organic dust challenges. No significant differences were found in activity, although in one study RAO animals had elevated chitinase activity that fell short of statistical significance. The pH optimum and pH lability of the activity was consistent with the presence of chitotriosidase. RT-PCR amplification of the mRNA encoding chitotriosidase and AMCase in normal equine lung showed that chitotriosidase, but not AMCase, is expressed in trachea, bronchi, and peripheral lung tissue. The gene for chitotriosidase was identified from the Equus caballus (horse) genome 1.1 database and its similarity to the same genes from other species was determined. The results of this study indicate that the involvement of chitotriosidase in RAO is uncertain.
复发性气道阻塞（RAO）是马肺部的一种慢性炎症性疾病，可能与人类哮喘有着共同的免疫基础，哮喘中存在Th2反应失调。哺乳动物表达几丁质酶和几丁质酶样蛋白，其中两种是活性酶，即壳三糖酶和酸性哺乳动物几丁质酶（AMCase）。这两种酶在包括哮喘在内的一系列炎症性疾病中均上调。我们研究了有或没有RAO的马在受到有机粉尘刺激后支气管肺泡灌洗液中几丁质酶的活性。尽管在一项研究中RAO动物的几丁质酶活性升高但未达到统计学显著性，但在活性方面未发现显著差异。该活性的最适pH值和pH稳定性与壳三糖酶的存在一致。对正常马肺中编码壳三糖酶和AMCase的mRNA进行RT-PCR扩增表明，壳三糖酶而非AMCase在气管、支气管和外周肺组织中表达。从马（Equus caballus）基因组1.1数据库中鉴定出壳三糖酶基因，并确定了其与其他物种相同基因的相似性。本研究结果表明壳三糖酶在RAO中的作用尚不确定。
