Gabriel C, Becher-Deichsel A, Hlavaty J, Mair G, Walter I
Department of Pathobiology, Institute of Anatomy, Histology and Embryology, University of Veterinary Medicine, Vienna, Austria.
Division for Obstetrics, Gynecology and Andrology, Department of Small Animals and Horses, University of Veterinary Sciences, Vienna, Austria.
Theriogenology. 2016 Jun;85(9):1599-1609.e2. doi: 10.1016/j.theriogenology.2016.01.021. Epub 2016 Jan 30.
Pyometra, the purulent inflammation of the uterus, is a common uterine disease of bitches that has potentially life-threatening consequences. The opportunistic bacterial infection of the uterus often progresses into the serious systemic inflammatory response syndrome. In a previous study, we characterized epithelial foam cells in the canine endometrial surface occurring in metestrus, and we regularly observed pronounced epithelial foam-cell formations in pyometra-affected uteri. Therefore, it was assumed that the mechanism behind lipid droplet accumulation in surface epithelial cells might even increase bacterial binding capacity and promote pyometra development. Lipid droplet accumulation in epithelial cells is accomplished via specialized lipid receptors called scavenger receptors (SR). Scavenger receptor class B type 1 (SR-B1) is an important receptor for lipid accumulation in diverse cell types, but it is also a strong binding partner for bacteria, and thereby enhances bacterial adhesion and clinical signs of systemic inflammatory response syndrome. In the present study, after the isolation of metestrous surface epithelial cells from canine uteri by laser capture microdissection, SR-B1 was identified at the messenger RNA (mRNA) level by quantitative real time polymerase chain reaction and also at the protein level by means of immunohistochemistry. In pyometra-affected uteri, SR-B1 mRNA expression was higher than that in the healthy control samples, and SR-B1 protein was expressed in the surface and crypt epithelial cells. Furthermore, to understand the physiological role of SR-B1 expression in the metestrus surface epithelial cells, we investigated its expression in the epithelial cells of the glandular chambers of canine placenta in different stages of gestation because these cells are also characterized by lipid droplet accumulation. SR-B1 was present in the placental epithelial cells of the glandular chambers from 25 to 30 and 45 to 50 days of gestation, where basal and basal and/or apical expression patterns were observed. The physiological expression of SR-B1 in metestrous endometrial surface epithelia might be related to the implantation process and embryo development, as SR-B1 was also identified in the epithelial cells of the canine placental chambers. The increased levels of SR-B1 in pyometra-affected uteri indicate a potential role for this scavenger receptor in endometrial bacterial adhesion.
子宫蓄脓，即子宫的脓性炎症，是母犬常见的子宫疾病，可能会产生危及生命的后果。子宫的机会性细菌感染常常会发展为严重的全身炎症反应综合征。在之前的一项研究中，我们对发情后期犬子宫内膜表面出现的上皮泡沫细胞进行了特征描述，并且我们经常在受子宫蓄脓影响的子宫中观察到明显的上皮泡沫细胞形成。因此，人们认为表面上皮细胞中脂滴积累背后的机制甚至可能会增加细菌结合能力并促进子宫蓄脓的发展。上皮细胞中的脂滴积累是通过一种名为清道夫受体（SR）的特殊脂质受体来完成的。B1型清道夫受体（SR-B1）是多种细胞类型中脂质积累的重要受体，但它也是细菌的强力结合伙伴，从而增强细菌黏附以及全身炎症反应综合征的临床症状。在本研究中，通过激光捕获显微切割从犬子宫中分离出发情后期的表面上皮细胞后，通过定量实时聚合酶链反应在信使核糖核酸（mRNA）水平鉴定出了SR-B1，并且通过免疫组织化学在蛋白质水平也鉴定出了SR-B1。在受子宫蓄脓影响的子宫中，SR-B1 mRNA表达高于健康对照样本，并且SR-B1蛋白在表面和隐窝上皮细胞中表达。此外，为了了解SR-B1在发情后期表面上皮细胞中表达的生理作用，我们研究了其在犬胎盘不同妊娠阶段腺腔上皮细胞中的表达，因为这些细胞也具有脂滴积累的特征。在妊娠25至30天以及45至50天的腺腔胎盘上皮细胞中存在SR-B1，观察到其呈基底和基底及/或顶端表达模式。发情后期子宫内膜表面上皮中SR-B1的生理表达可能与着床过程和胚胎发育有关，因为在犬胎盘腔的上皮细胞中也鉴定出了SR-B1。受子宫蓄脓影响的子宫中SR-B1水平升高表明这种清道夫受体在子宫内膜细菌黏附中具有潜在作用。
