Does the endometrial gene expression of fertile women vary within and between cycles?

STUDY QUESTION: Does gene expression of putative endometrial implantation markers vary in expression between menstrual cycles? SUMMARY ANSWER: In fertile women the expression of certain genes exhibits a pattern of stable regulation.which is not affected even when sampled twice in one cycle. WHAT IS KNOWN ALREADY: Successful implantation occurs in a minority of IVF embryo transfers. In contrast to knowledge regarding the ovulatory process, there is a sparse understanding of endometrial genes critical to implantation. This lack of knowledge hinders progress in this field. STUDY DESIGN, SIZE, DURATION: Endometrial pipelle samples were collected based on blood endocrinological markers at 2 and 7 days post initial LH surge. Five samples were collected over four cycles where the interval between collections ranged from sequential months to three years. PARTICIPANTS/MATERIALS, SETTING, METHODS: Six fertile women attending an IVF clinic for male factor infertility, had samples collected. Global gene expression profiles were obtained from laser-microdissected, endometrial glands and stroma. Nineteen potential proliferation, cytokine and adhesion markers based on previous validated reports were studied. MAIN RESULTS AND THE ROLE OF CHANCE: There was a significant modification between LH+2 and LH+7 of expression for 23 genes-11 in 8 in glands and stroma, 4 in stroma only and 3 in glands only suggesting stable, controlled regulation. Nevertheless, genes exhibited individual characteristics, e.g MKI67 exhibited lower expression at LH+7 than LH+2 and CCL4 higher, whereas TRO expressed limited difference in both cell types. Stability between cycles was demonstrated for gene expression at both LH+2-more than 60% of genes had <25% variation and at LH+7-60% had <30% variation. Further, effects of prior collection of an LH+2 sample on gene expression at LH+7 were not detected. The range of mRNA expression suggested that a clinical/diagnostic sample at LH+2 and LH+7 is likely to be a better index of endometrial function than a single sample. The possibility of redundancy suggests a panel would be more informative than a single marker. LARGE SCALE DATA: Raw and normalized microarray data have been deposited with the EMBL's European Genome-Phenome Archive for collaborative analysis, reference ega-box-815 (Lappalainen I, Almeida-King J, Kumanduri V, Senf A, Spalding JD, Ur-Rehman S, Saunders G, Kandasamy J, Caccamo M, Leinonen R et al. The European Genome-phenome Archive of human data consented for biomedical research. Nat Genet 2015;47:692-695.) [https://www.ebi.ac.uk/ega/home]. LIMITATIONS, REASONS FOR CAUTION: This type of research has difficulties of recruitment of fertile women for multiple blood testing and repeat endometrial biopsies. Therefore, these data had decreased statistical power due to the overall participant numbers. However, the inclusion of four cycles for each participant permitted the aim of obtaining information on intercycle and intracycle variability to be achieved. WIDER IMPLICATIONS OF THE FINDINGS: Our results support the feasibility of a clinical means of identification of a functional receptive endometrium. The robustness of data from individual women suggests that samples from one cycle can generally be applied to subsequent cycles. STUDY FUNDING/COMPETING INTEREST(S): Funding was granted from the Tertiary Education Commission of New Zealand, Contract I.D.:UOOX06007. There are no competing interests.

In the secretory endometria of women, luminal epithelia exhibit gene and protein expressions that differ from those of glandular epithelia.

OBJECTIVE: To characterize the transcriptome of luminal epithelia (LE) of fertile secretory endometria and compare the results with those from glandular epithelia (GE). DESIGN: Endometrial samples were collected at 2 and 7 days after initial blood LH surge in separate menstrual cycles. LE were obtained with the use of laser microdissection. mRNA was amplified with the use of linear polymerase chain reaction and hybridized to Agilent 4×44 microarrays. Gene analysis was used to identify differentially expressed mRNAs. Immunohistochemistry was used to assess nine proteins. SETTING: One IVF clinic. PATIENT(S): Seven Caucasian fertile cycling women. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Cycle dating with the use of blood endocrinologic markers, microarrays of laser-microdissected LE, immunohistochemical analysis. RESULT(S): One hundred sixty-one (of 401) differentially expressed mRNAs in LE were identified from the metabolism pathway. Increased selective protein expression in LE at 7 days after initial LH surge was observed. LE mRNA expression was the converse of that in GE. The two cell types each had a different significant biologic pathway identified. CONCLUSION(S): Our results introduce a new concept that LE differentially expressed mRNAs are in the converse direction to that of GE, indicating different biologic processes despite the GE being continuous with the luminal monolayer. This probable distinction of biologic roles has not been noted previously. Further investigations must take cognizance of this observation.

Gene and protein expression signature of endometrial glandular and stromal compartments during the window of implantation.

OBJECTIVE: To map the changes in messenger RNA (mRNA) and protein abundance during the window of implantation in specifically endometrial stromal and glandular epithelial cells obtained using laser microdissection microscopy (LDM). DESIGN: Endometrial samples were collected from two menstrual cycles at 2 and 7 days after first significant rise in blood LH, and separate cell populations were obtained using LDM. A new generation linear polymerase chain reaction (PCR) amplified the mRNA, which were hybridized to both Affymetrix U133 Plus2 and Agilent 4x44K microarrays followed by gene set analysis. Immunohistochemistry assessed protein expression between the two collection times. SETTING: In vitro fertilization clinic. PATIENT(S): Nine Caucasian, fertile, cycling women. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Cycle dating using blood markers; microarrays on laser microdissected glands and stroma; dual platform microarray confirmation; immunohistochemical analysis of cell cycle proteins. RESULT(S): The two microarray platforms showed concordance. During the window of implantation, a statistically significant network of 22 mRNA associated with the cell cycle was down-regulated. Immunohistochemistry identified altered localization in stroma. CONCLUSION(S): Microarrays demonstrated glands and stroma have distinct mRNA signatures, each dependent on the day of the cycle. We characterized two compartments of the receptive endometrium with a transcriptomic signature identifying regulation of only the cell cycle. Immunohistochemical analysis of cell cycle proteins identified a signature staining pattern of nuclear relocalization of a group of cyclins of stromal cells, which may be clinically applicable.