Abstract
Study question
Are serum cytokines levels associated with ovarian response in IVF cycles?
Summary answer
The IL–6/IL–10 ratio is higher in patients with low ovarian response.
What is known already
Previous studies reported differences in the levels of IL–2, Il–6, IL–8, IL–10 and VEGF in follicular fluid between young patients with low ovarian response and normoresponder women. In addition, it is known that IL–6 plays an important role as a mediator of fever and acute phase reaction and IL–10 is the cytokine with the greatest anti-inflammatory power. Although there seems to be some evidence about the possible effect of the immune system on ovarian function and implantation, the role it plays in ART remains unknown. Our aim was to investigate the effect of cytokines in ovarian reserve and response.
Study design, size, duration
One hundred and fifty-two patients were included in a retrospective study between February 2016 and December 2020. Serum cytokines IL–2, IL–4, IL- 6, IL–8, IL–10, VEGF, IFN↖, TNF α, IL–1 α, IL–1 β, MCP–1 and EGF were measured previously to the ovarian stimulation cycle. Patients with altered karyotype, mutation or premutation in the FMR1 gene or endometriosis or with any other factor that could alter the ovarian reserve or response were excluded from the study.
Participants/materials, setting, methods
To measure the levels of the different cytokines, a sandwich immunoassay with specific antibodies for the cytokines IL–2, IL–4, IL–6, IL–8, IL–10, VEGF, IFN↖, TNF α, IL -1 α, IL–1 β, MCP–1 and EGF were used. The statistical analysis was performed with R Statistical Software, version 4.0.3 and the Software Statistical Product and Service Solutions, version 20.0 (SPSS, Chicago, IL, EE.UU.).
Main results and the role of chance
We found that the ratio between IL–6 and IL–10 cytokines is higher in those patients in whom four or fewer oocytes have been recovered after ovarian puncture (2.15 versus 1.55; p = 0.035; Mann-Whitney test). If we establish 0.9 as a cut-off point for the IL–6 / IL–10 ratio, we observed that above this value the risk of having a low response to ovarian stimulation is more than 3 times greater than below this value (22.9% versus 6.0%; p = 0.007; Fischer exact test). There were no statistically significant differences between both groups in terms of age (p = 0.136), dose of gonadotropin administered (p = 0.415) and duration of ovarian stimulation (p = 0.706).
In addition, performing hierarchical cluster analysis with the analyzed cytokines and the associated variables to ovarian reserve and response, we observed that the antral follicle count, the total oocytes recovered and the MII recovered are grouped in the same cluster as the cytokines IL–2, IL–4, IL–6, IL–10, IL–1α, IL–1B, IFNγ y TNFα. We determined the number of clusters based on the tree diagram and k-means method.
Limitations, reasons for caution
The retrospective study design and the sample size could be a limitation. The study was performed in patients with suspected implantation failure.
Wider implications of the findings: The ratio between IL–6 and IL–10 could be used as a potential biomarker to predict the ovarian response and provide real expectations regarding the success of IVF cycle. The action of IL–6 could be reduced by blocking its receptor using humanized monoclonal antibodies as Tocilizumab.
Trial registration number
Not applicable
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