The effect of icariin for infertile women with thin endometrium: A protocol for systematic review

Label-free proteomic analysis and functional analysis in patients with intrauterine adhesion

Intrauterine adhesion (IUA) is one of the principal causes of secondary infertility in women of reproductive age, which seriously affects female reproductive function and quality of life. In recent years, the incidence of IUA has been increasing year by year, but its pathological mechanism has not yet been clarified. This study intended to reveal the pathogenesis of IUA and find new therapeutic targets by analyzing the proteomic differences between intrauterine adhesion tissues and normal human endometrial tissues. In the label-free quantitative proteomics, we identified 789 up-regulated differentially expressed proteins (DEPs) and 539 down-regulated DEPs. These DEPs were further analyzed by Gene Ontology (GO) annotation and enrichment analysis, Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis to preliminarily clarify the biomarkers involved in the pathogenesis of the IUA. The DEPs were further verified by parallel reaction monitoring (PRM) to confirm the results of proteomics. Finally, 7 target proteins may be candidates for treatment and elucidating the pathophysiology of IUA. SIGNIFICANCE: IUA is a fertility complication, which has increasing incidence recently. Until now, only a little research paid attention to the proteomic changes of IUA. This is the first study focused on the comparative analysis of endometrial tissue between IUA patients and normal women. We found 7 key proteins that may become the potential biomarkers of IUA.

The expressions of matrix metalloproteinase-9, estrogen receptor, and progesterone receptor in thin endometrial tissue and their significance

OBJECTIVE

This study aims to investigate the expressions of matrix metalloproteinase-9 (MMP-9), estrogen receptor (ER), and progesterone receptor (PR) in thin endometrium.

METHODS

Patients who received treatment in our hospital between January 2018 and September 2020 were enrolled. Endometrial thickness was measured using transvaginal ultrasound; in patients with a midluteal phase endometrial thickness of <7 mm, a sample of endometrial tissue was obtained using a hysteroscope, and the MMP-9, ER, and PR expressions were detected using immunohistochemistry. In addition, the number of endometrial glands was calculated in a complete field of view under a low-power (100×) microscope, and the serum estrogen and progesterone levels were determined. Following hormone therapy, the midluteal phase endometrial thickness was measured again using transvaginal ultrasound, and the patients were divided into two groups: the thin endometrium group and the normal endometrium group (n = 50, each). Patients in the thin endometrium group had an endometrial thickness of <7 mm, while patients in the normal endometrium group had an endometrial thickness of 7-10 mm.

RESULTS

The number of endometrial glands as well as the ER and MMP-9 expressions were lower in the thin endometrium group than in the normal endometrium group; the differences were statistically significant (p < .05). The receiver operator characteristic curve revealed that ER and MMP-9 had a high prediction accuracy in patients with refractory thin endometrium, while the number of endometrial glands was moderately predictive.

CONCLUSION

Compared with other patients with thin endometrium, patients with refractory thin endometrium had a reduced the number of endometrial glands and significantly lower ER and MMP-9 expressions.

Down-regulation of PBK inhibits proliferation of human endometrial stromal cells in thin endometrium

BACKGROUND

Thin endometrium (TE) is a challenging clinical issue in the reproductive medicine characterized by inadequate endometrial thickness, poor response to estrogen and no effective treatments currently. At present, the precise pathogenesis of thin endometria remains to be elucidated. We aimed to explore the related molecular mechanism of TE by comparing the transcriptome profiles of late-proliferative phase endometria between TE and matched controls.

METHODS

We performed a bulk RNA-Seq (RNA-sequencing) of endometrial tissues in the late-proliferative phase in 7 TE and 7 matched controls for the first time. Differential gene expression analysis, gene ontology enrichment analysis and protein-protein interactions (PPIs) network analysis were performed. Immunohistochemistry was used for molecular expression and localization in endometria. Human endometrial stromal cells (HESCs) were isolated and cultured for verifying the functions of hub gene.

RESULTS

Integrative data mining of our RNA-seq data in endometria revealed that most genes related to cell division and cell cycle were significantly inhibited, while inflammation activation, immune response and reactive oxygen species associated genes were upregulated in TE. PBK was identified as a hub of PPIs network, and its expression level was decreased by 2.43-fold in endometria of TE patients, particularly reduced in the stromal cells, which was paralleled by the decreased expression of Ki67. In vitro experiments showed that the depletion of PBK reduced the proliferation of HESCs by 50% and increased the apoptosis of HESCs by 1 time, meanwhile PBK expression was inhibited by oxidative stress (reduced by 76.2%), hypoxia (reduced by 51.9%) and inflammatory factors (reduced by approximately 50%). These results suggested that the insufficient expression of PBK was involved in the poor endometrial thickness in TE.

CONCLUSIONS

The endometrial transcriptome in late-proliferative phase showed suppressed cell proliferation in women with thin endometria and decreased expression of PBK in human endometrial stromal cells (HESCs), to which inflammation and reactive oxygen species contributed.

Integrated Transcriptomic Analysis of the miRNA-mRNA Interaction Network in Thin Endometrium

Although the thin endometrium (TE) has been widely recognized as a critical factor in implantation failure, the contribution of miRNA-mRNA regulatory network to the development of disease etiology remains to be further elucidated. This study performed an integrative analysis of the miRNA-mRNA expression profiles in the thin and adjacent normal endometrium of eight patients with intrauterine adhesion to construct the transcriptomic regulatory networks. A total of 1,093 differentially expressed genes (DEGs) and 72 differentially expressed miRNAs (DEMs) were identified in the thin adhesive endometrium of the TE group compared with the control adjacent normal endometrial cells. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that the DEGs and the target genes of DEM were significantly enriched in angiogenesis, cell growth regulation, and Wnt signaling pathway. Multiple hub genes (CAV1, MET, MAL2, has-mir-138, ARHGAP6, CLIC4, RRAS, AGFG1, has-mir-200, and has-mir-429) were identified by constructing the miRNA-mRNA regulatory networks. Furthermore, a miRNA-mRNA pathway function analysis was conducted, and the hub genes were enriched in the FoxO signaling pathway, cell growth regulation, inflammatory response regulation, and regulation of autophagy pathways. Our study is the first to perform integrated mRNA-seq and miRNA-seq analyses in the thin adhesive endometrium and the control adjacent normal endometrial cells. This study provides new insights into the molecular mechanisms underlying the formation of thin endometrium.