Matsuoka Yoh, Masuda Hitoshi, Yokoyama Minato, Kihara Kazunori
Department of Urology, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.
BJU Int. 2007 Dec;100(6):1402-8. doi: 10.1111/j.1464-410X.2007.07111.x.
To investigate the expression profiles and protective roles of the inducible isoform of heme oxygenase-1 (HO-1) in cyclophosphamide (CYP)-induced cystitis, as the HO system is involved in heme degradation and plays an important role in cellular homeostasis but its characterization is still unknown in urinary tract diseases.
In female Sprague-Dawley rats CYP was administed intraperitoneally and the bladders excised at various time points. In separate experiments, hemin, an inducer of HO, was administered before CYP treatment, and bladders were harvested 24 h after CYP injection. The expressions of HO-1 and HO-2 were investigated by reverse-transcription polymerase chain reaction and immunohistochemistry. The effects of CYP with/without hemin pretreatment were evaluated by microscopic features, bladder wet weight, myeloperoxidase activity, nitric oxide (NO)-metabolite production, and expression levels of inflammation-related genes.
CYP injection resulted in severe cystitis with time-dependent increases both in bladder wet weight and HO-1 mRNA expression. Pretreatment with hemin enhanced the CYP-induced expression of HO-1 mRNA and protein further, but significantly ameliorated inflammatory changes and reduced the increases in bladder oedema and myeloperoxidase activity. NO-metabolite production and inducible NO synthase (iNOS) expression, induced by CYP, were down-regulated significantly by hemin pretreatment. By contrast, HO-2 was constitutively present in the urothelium and its expression was not influenced by CYP or by CYP plus hemin.
HO-1 expression is up-regulated in bladders with CYP-induced haemorrhagic cystitis, and this inducible enzyme plays cytoprotective roles in association with down-regulation of NO production and iNOS expression. Our results suggest that HO-1 induction might have therapeutic potential against inflammatory insults such as CYP-induced cystitis.
由于血红素加氧酶系统参与血红素降解并在细胞内稳态中发挥重要作用，但在泌尿系统疾病中的特征仍不清楚，因此研究血红素加氧酶-1（HO-1）的诱导型同工型在环磷酰胺（CYP）诱导的膀胱炎中的表达谱及其保护作用。
对雌性Sprague-Dawley大鼠腹腔注射CYP，并在不同时间点切除膀胱。在单独的实验中，在CYP治疗前给予HO诱导剂血红素，并在注射CYP后24小时收集膀胱。通过逆转录聚合酶链反应和免疫组织化学研究HO-1和HO-2的表达。通过显微镜特征、膀胱湿重、髓过氧化物酶活性、一氧化氮（NO）代谢产物生成以及炎症相关基因的表达水平评估有无血红素预处理的CYP的作用。
注射CYP导致严重膀胱炎，膀胱湿重和HO-1 mRNA表达均随时间依赖性增加。血红素预处理进一步增强了CYP诱导的HO-1 mRNA和蛋白表达，但显著改善了炎症变化，并减少了膀胱水肿和髓过氧化物酶活性的增加。血红素预处理显著下调了CYP诱导的NO代谢产物生成和诱导型NO合酶（iNOS）表达。相比之下，HO-2在尿路上皮中组成性存在，其表达不受CYP或CYP加血红素的影响。
在CYP诱导的出血性膀胱炎的膀胱中HO-1表达上调，并且这种诱导酶通过下调NO生成和iNOS表达发挥细胞保护作用。我们的结果表明，诱导HO-1可能对诸如CYP诱导的膀胱炎等炎症损伤具有治疗潜力。
