Unexplained recurrent pregnancy loss and unexplained infertility: twins in disguise

Chelsea W Fox; Ricardo F Savaris; Jae-Wook Jeong; Tae Hoon Kim; Paul B Miller; Creighton E Likes; David P Schammel; Steven L Young; Bruce A Lessey

doi:10.1093/hropen/hoz021

Infertility Uterine Factor

Unexplained recurrent pregnancy loss and unexplained infertility: twins in disguise

Fox CW, Savaris RF, Jeong JW, Kim TH, Miller PB, Likes CE, Schammel DP, Young SL, Lessey BA

Human Reproduction Open, 2020

DOI 10.1093/hropen/hoz021 PMID 36694811 PMC PMC9869655

RRM Academy Synopsis

Unexplained infertility and pregnancy loss share elevated BCL6

A case-control study of 110 endometrial samples found nearly 8 out of 10 women with unexplained infertility or pregnancy loss had elevated BCL6, a protein marker linked to endometriosis. Fewer than 1 out of 10 fertile controls did. Laparoscopy in a subset with elevated BCL6 found endometriosis in most of them.

Key Findings

Endometrial BCL6 protein was elevated in 79% of women with unexplained recurrent pregnancy loss (uRPL) or unexplained infertility (UI), 65 out of 82, with the same 79% in each group.
Two of 28 fertile controls (7%) tested positive for elevated BCL6.
BCL6 staining differed significantly among controls, uRPL and UI (P < 0.0001, Kruskal-Wallis), and the difference remained significant after adjustment for age (P < 0.0001).
A significant trend linked the degree of infertility (fertile, uRPL, UI) with the BCL6 staining level (P < 0.001, chi-square for trend).
Laparoscopy in a subset with elevated BCL6 found endometriosis in 9 out of 11 women with uRPL and 20 out of 21 with UI.

Interpretation

The study is a case-control comparison, which sets women with a condition beside women without it. Researchers scored archived biopsies of the uterine lining taken in the second half of the cycle, timed by the LH surge. A pathologist read the slides without knowing each woman's group. The authors treat BCL6 as a marker for endometriosis. They postulate that, in women with endometriosis, a continuum of progesterone resistance and inflammation may produce different degrees of infertility. The authors note that recurrent loss meant two consecutive losses, while the European definition uses three. They call for further studies of whether treating endometriosis improves outcomes.

RRM Context

RRM views unexplained infertility and unexplained pregnancy loss as undiagnosed. Each calls for a search for the root cause. A marker that points to endometriosis adds a diagnosable disease to the list of causes. NaProTechnology and other restorative methods give close attention to ovulation and the luteal phase, the part of the cycle in which these biopsies were taken.

Our editorial summary of this paper, not the article's abstract.

Abstract

Study Question

Is B-cell CLL/lymphoma 6 (BCL6) endometrial expression, a surrogate biomarker of endometriosis, elevated in women with unexplained recurrent pregnancy loss (uRPL) and unexplained infertility (UI) compared to fertile subjects?

Summary Answer

Endometrial BCL6 expression is elevated to a similar degree in women with uRPL and UI compared to fertile controls.

What Is Known Already

Endometriosis has been linked to the genesis of endometrial progesterone resistance and to specific nuclear proteins, including endometrial BCL6. BCL6 overexpression (immune histologic score > 1.4) has been strongly associated with poor reproductive outcomes in IVF cycles in women with UI. Our previous data have demonstrated an accuracy of 94% for diagnosing endometriosis, and BCL6 protein is elevated in the decidua of women with uRPL.

Study Design, Size, Duration

In this case-control study, at a tertiary university teaching hospital, 110 samples (control n = 28; uRPL n = 29; UI n = 53) from pathological archives were analyzed. Timed endometrial biopsies were obtained between 2 January 2002 and 31 December 2016.

PARTICIPANTS/MATERIALS SETTING

Method

LH-timed endometrial biopsies were obtained from women with UI, uRPL (two or more consecutive losses) and normal fertile subjects during the mid-secretory phase of the menstrual cycle. Endometrial BCL6 protein levels were compared in women with UI and uRPL and fertile controls using western blot analysis and immunohistochemistry (HSCORE).

Main Results and the Role of Chance

The mean age of the uRPL group was significantly higher than the others [mean (SD)] control = 32.7 (2.6); uRPL = 35.8 (3.7); UI = 32.7 (4.4); P = 0.002, ANOVA]. Seventy-nine percent of women in both subfertile groups (uRPL and UI, 65 out of 82) displayed elevated BCL6 protein levels. From these, a subset of cases with abnormal BCL6 went to laparoscopy and endometriosis was found in 9 out of 11 cases of uRPL and in 20 out of 21 cases of UI. Median BCL6 HSCORE for controls versus uRPL and UI was significantly different [median (interquartile); control = 0.3 (0.02 to 0.5); uRPL = 3 (1.9 to 3.6); UI = 2.9 (1.6 to 3.1); P < 0.0001, Kruskal-Wallis]. A significant trend in the association between the degree of infertility (fertile, uRPL and UI) and the HSCORE level (negative, medium and high) was found (P < 0.001; x 2 for trend). Western blot of representative samples from each group demonstrated similar findings based on protein levels in the whole endometrium. After running ANCOVA analysis for age difference, the BCL6 difference among groups was still significant (P-value < 0.0001).

Limitations, Reasons for Caution

We studied subjects with two consecutive pregnancy losses rather than the definition adopted in Europe of three losses. The findings may lack external validity in other clinical settings (e.g. low prevalence of endometriosis).

Wider Implications of the Findings

Based on the data presented here, we postulate that the degree of BCL6 expression may represent a continuum of progesterone resistance and response to inflammation that occurs in women with endometriosis, yielding different degrees of infertility, from uRPL to UI.

Study Funding/Competing Interests

This study was supported by NICHD/NIH R01 HD067721 (SLY and BAL), by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior: Grant 99999.003035/2015-08 (BAL) and by CAPES/PROAP (RFS). Two authors (BAL, SLY) have licensed intellectual property for the detection of endometriosis. Dr Bruce Lessey is an unpaid scientific Advisor for CiceroDx. The other authors report no conflict of interest.

Topics

Infertility › Uterine Factor › Endometrial Receptivity · Diagnostics › Endometrial Assessment › Receptivity Testing · Reproductive Endocrinology › Luteal Phase › Luteal Phase Deficiency

Chelsea W Fox, Ricardo F Savaris, Jae-Wook Jeong, Tae Hoon Kim, Paul B Miller, Creighton E Likes, David P Schammel, Steven L Young, Bruce A Lessey

C Fox, R Savaris, J Jeong, T Kim, P Miller, C Likes, Dave Schammel, D Schammel, Steve Young, S Young, B Lessey

PMID 36694811 36694811 DOI 10.1093/hropen/hoz021 10.1093/hropen/hoz021 Fox et al. 2020, Fox 2020

Unexplained recurrent pregnancy loss and unexplained infertility: twins in disguise

Unexplained infertility and pregnancy loss share elevated BCL6

Key Findings

Interpretation

RRM Context

Abstract

Topics

By this author

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