Endometrial LGR7 expression and implantation failure

Abstract

Implantation failure is considered as a major cause of infertility in women with recurrent pregnancy loss (RPL) and in otherwise healthy women with unexplained infertility. Preliminary data in primates suggested that relaxin (RLX) is involved in endometrial preparation for implantation. In a prospective observational study, the endometrial RLX receptor (LGR7) expression was assessed in three groups of patients with regular ovulatory cycle and normal uterine cavity: 23 with RPL (Group A), 23 with unexplained infertility undergone at least three cycles of failed in vitro fertilization (IVF) reporting good oocyte and embryo quality (Group B), 23 with proven fertility (Group C). Assessment of LGR7 expression was performed with both polymerase chain reaction (PCR) analysis and immunohistochemistry on endometrial samples obtained with hysteroscopic biopsy performed in the secretory phase of the menstrual cycle. Endometrial LGR7 was less expressed in group A and B versus C, both by PCR analysis (p = 0.024) and immunohistochemistry. The decreased expression of the endometrial RLX receptor in women with implantation failures, both in vitro fertilization failure and recurrent pregnancy loss, suggests that RLX may play a crucial role in the structural and functional changes of the endometrium during the window of implantation.

Chinese abstract

着床失败被认为是不孕女性反复性流产(RPL)和健康妇女不明原因不孕的主要原因。初步灵长类动物的实验数据提示，松弛素(RLX)与参与子宫内膜植入有关。在一个前瞻性研究中，对三组有正常排卵周期以及正常子宫腔的患者评估其子宫内膜RLX受体(LGR7)的表达:23名RPL患者(A组)，23名经历了至少三个周期体外受精(IVF)失败但卵母细胞及胚胎质量良好者(B组)，23生育能力正常者(C组)。在月经周期的分泌阶段进行宫腔镜活组织检查获得分泌期子宫内膜，通过聚合酶链氏反应(PCR)和免疫组化分析子宫内膜样本的LGR7表达情况。

通过PCR分析(p = 0.024)和免疫组织化学分析均显示，与C组相比A和B组的LGR7表达较少。在胚胎种植失败包括体外受精失败和反复性流产的患者中，子宫内膜的RLX受体表达减少，表明在子宫内膜着床期，RLX可能对内膜的结构和功能发挥着至关键的作用。

• Endometrial biopsy
• implantation failure
• relaxin receptor
• window of implantation

Acknowledgements

We thank Simona Signoriello and Giuseppe Signoriello for their statistical support.

Declaration of interest

The authors report no declarations of interest

Supplementary materials available online