Association of Soluble HLA-G Plasma Level and HLA-G Genetic Polymorphism With Pregnancy Outcome of Patients Undergoing in vitro Fertilization Embryo Transfer
Izabela Nowak, Karolina Wilczyńska, Paweł Radwan, Andrzej Wiśniewski, Rafał Krasiński, Michał Radwan, Jacek R. Wilczyński, Andrzej Malinowski, Piotr Kuśnierczyk
Abstract
Infertility is currently a growing problem observed around the world and is estimated to affect between 8 and 12% of reproductive-aged couples worldwide. Artificial reproductive techniques are the last chance for couples seeking their own child. Human leukocyte antigen (HLA)-G expression has been suggested as an immunomodulatory molecule influencing pregnancy outcome. The HLA-G gene encodes either membrane-bound or/and soluble proteins. The aim of this study was the evaluation of soluble HLA-G (sHLA-G) role and its gene polymorphism in success of implantation after in vitro fertilization embryo transfers (IVF-ETs) in different clinical protocols. We tested HLA-G polymorphism in 3 positions: rs1632947: c-964G>A; rs1233334: c.-725G>C/T in promoter region; rs371194629: c.*65_*66insATTTGTTCATGCCT in 3’UTR of exon 8, in 389 patients who underwent IVF-ETs and 320 women with healthy born children after natural conception. Among the patient group, 239 women were with recurrent implantation failure and 117 women had an ongoing pregnancy or a child born after IVF-ET. We found certain rs1632947-rs1233334-rs371194629 HLA-G haplotypes and diplotypes were associated with infertility, while others were protective. The lowest secretors of sHLA-G were G-C-ins haplotype carriers (37.21 IU/mL), while the highest - G-C-del carriers (73.80 IU/mL). Other haplotype carriers were intermediate secretors. In our study, regardless of possessed haplotype by the patient, 59.73 IU/mL sHLA-G was threshold value with the best sensitivity (58.82%) and specificity (66.10%) to discriminate patients who achieved and maintained pregnancy from those who did not conceive or they had miscarriage (p = 0.0085, likelihood ratio 1.74, 95% CI = 0.55-0.78). However, we do not exclude that factors other than sHLA-G may also contribute to complications in pregnancy. In addition, we found that IVF patients in cycles when frozen/thawed embryo was transferred secreted higher soluble HLA-G levels than patients with fresh embryo transferred (p = 0.021). Moreover, correlation analysis of sHLA-G concentration measured before and after embryo transfer for particular patients indicated short ovarian stimulation with gonadotropin-releasing hormone (GnRH) antagonist as more beneficial than long protocol with GnRH agonist. Our study confirm a role of HLA-G polymorphism in infertility and soluble HLA-G in the early stages of pregnancy.