Assessing the Correlation Between Phospholipase C Zeta Measurements and Semen Parameters

Official title

Assessing the Correlation Between Phospholipase C Zeta (PLCZeta) Measurements and Semen Parameters

Overview

With declining fertility rates Worldwide, Assisted Reproductive Technology is seen as a viable solution for infertility, however, individual success rates following ART remain relatively low, rarely exceeding \~50%. The European Society for Human Reproduction and Embryology (ESHRE) indicates pregnancy rates per embryo transfer remain below 50%. Additionally, male infertility is regarded as a leading contributor to global infertility with approximately a third of cases attributed to genetic causes while half of the cases remain unexplained. In this observational study we investigate the correlation between phospholipase C Zeta (PLCζ ) measurements and semen parameters. PLCζ is a sperm-specific protein which is introduced into a mature egg (oocyte) following gamete fusion and upon introduction, PLCζ is believed to initiate a series of characteristic calcium ion oscillations which lead to oocyte activation and persist beyond the completion of meiosis. Mounting evidence implicates defects in PLCζ in cases of male factor infertility where intracytoplasmic sperm injection (ICSI; whereby a single sperm is injected into the oocyte) is unsuccessful. Furthermore, defects in PLCζ are also increasingly implicated in cases of male sub-fertility, which affects a much larger proportion of the global population. Numerous studies now indicate that PLCζ not only holds significant value as a therapeutic to rescue cases of ICSI failure, but also as a prognostic diagnostic test of male fertility. Indeed, the reduction or absence of normal PLCζ within sperm has been linked to cases of male factor infertility in humans, either due to inactivation through mutation, due to abrogation of protein levels in sperm as a result of mutation in the PLCζ promoter, or mutations within coding exonic regions of the PLCζ gene. Such data indicate both therapeutic, and diagnostic applications for PLCζ within the fertility clinic. This study seeks to determine the effect of abnormal PLCζ on semen parameters and correlate that with downstream events including clinical pregnancy and live birth rates.

Detailed description

Despite advances in assisted reproductive technology (ART), significant gaps remain in understanding recurrent implantation failure and abortive embryogenesis. Male factor infertility is globally the leading cause of infertility, and is particularly prevalent in GCC countries, notably the UAE; where fertility rates have halved over the past decade, driven by cultural, lifestyle, and environmental shifts. Poor semen parameters (sperm count, motility, and morphology) account for 41% of infertility cases in the region.

The financial burden is substantial: a single ART cycle can exceed AED 30,000, with couples typically requiring 2-3 cycles (AED 60,000-100,000), translating to an estimated national expenditure of \~AED 0.5 billion annually in fertility treatments alone, excluding associated healthcare investigations.

A critical and underexplored mechanism underlying poor ART outcomes involves oocyte activation, initiated at fertilization by characteristic intracellular calcium (Ca²⁺) oscillations. These are triggered by phospholipase C zeta (PLCζ), a sperm-specific protein delivered into the oocyte upon gamete fusion. Ca²⁺ oscillation profiles directly govern cell cycle progression, embryo gene expression, and early developmental competence; deviations in amplitude or frequency compromise embryo quality. Notably, preimplantation mouse studies show that both insufficient and excessive PLCζ impair blastocyst development, with successful outcomes occurring within a \~4-fold effective dose range - mirroring the natural variation of PLCζ levels observed across fertile men.

Mounting clinical evidence links reduced or absent sperm PLCζ to fertilization failure following intracytoplasmic sperm injection (ICSI), as well as to broader male sub-fertility. PLCζ deficiencies may arise through point mutations, promoter alterations, or disrupted exonic regions, and correlate with known sperm defects including poor motility, globozoospermia, and elevated DNA fragmentation. Crucially, even when residual PLCζ is sufficient to trigger oocyte activation, it may be inadequate for full embryonic competence, a distinction with major clinical implications for sub-fertile men.

Despite this evidence, the direct relationship between sperm PLCζ parameters and downstream outcomes including embryonic efficacy, recurrent implantation failure, and ART success rates has not yet been systematically investigated. We propose that abnormalities in PLCζ-mediated Ca²⁺ oscillations represent a significant and underappreciated contributor to poor global ART outcomes. Establishing this link would position PLCζ as both a prognostic diagnostic marker of sperm health and a therapeutic agent, with the potential to improve outcomes across a broad spectrum of infertility presentations beyond complete fertilization failure.

Interventions

• Other No Intervention: Observational Cohort
  This is a cohort observational study and there will be no intervention of any type.

Primary outcome measures

• Biochemical pregnancy [Time frame: From enrollment to clinical pregnancy result and delivery where applicable.]
• Clinical Pregnancy result [Time frame: From enrollment to delivery (live birth or miscarriage)]
• PLC Zeta measurement [Time frame: From enrollment to submission of sperm (1 day)]

Secondary outcome measures (1)

• Live birth or miscarriage [Time frame: From enrollment to delivery or miscarriage.]

Eligibility criteria

Couple inclusion criteria:

• Presenting to the IVF clinic for IVF/ICSI treatment or routine semen analysis
• Semen sample must have a total sperm count of ≥1 million sperm/ml
• Availability of excess, leftover sperm after clinical treatment procedures
• Couples must have experienced infertility for at least one year and be undergoing fertility treatment
• Undergoing standard clinical treatment protocols (including embryo culture and, when applicable, PGTA) with routinely collected treatment outcome data
• Sufficient ovarian reserve and/or meeting the clinic's standard criteria for fertility treatment

Couple exclusion criteria:

• Known genetic disorders affecting fertility
• History of vasectomy or other irreversible sterilization procedures
• Current use of medications known to affect sperm parameters (e.g., exogenous androgens, chemotherapeutic agents, or other drugs specifically impacting spermatogenesis)
• Recent history of chemotherapy or radiation therapy
• Female age >38 years old
• Known chromosomal abnormalities or genetic disorders that directly affect oocyte quality or embryo development
• Presence of severe uterine or pelvic pathology (e.g., significant uterine anomalies, advanced endometriosis)
• Documented ovarian failure or extremely diminished ovarian reserve as determined by AMH levels (AMH >1 ng/mL, AFC ≥5)
• Use of medications or undergoing treatments that could significantly alter oocyte quality or embryogenesis (outside standard ART protocols).

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Observational model

Cohort

Study locations

United Arab Emirates · 2 centers

• Fakih IVF — Abu Dhabi
• Khalifa University — Abu Dhabi

Publications

• World Health Organization, 2010, Fifth Edition. ISBN: 978 92 4 154778 9.
• Yamaguchi et al., Cell Calcium 2017;pii: S0143-4160(16)30191-9.
• Janghorban-Laricheh E, Ghazavi-Khorasgani N, Tavalaee M, Zohrabi D, Abbasi H, Nasr-Esfahani MH. An association between sperm PLCzeta levels and varicocele? J Assist Reprod Genet. 2016 Dec;33(12):1649-1655. doi: 10.1007/s10815-016-0802-5. Epub 2016 Sep 9. PMID 27612872
• Kamali-Dolat Abadi M, Tavalaee M, Shahverdi A, Nasr-Esfahani MH. Evaluation of PLCzeta and PAWP Expression in Globozoospermic Individuals. Cell J. 2016 Fall;18(3):438-45. doi: 10.22074/cellj.2016.4572. Epub 2016 Aug 24. PMID 27602326
• Wong CC, Loewke KE, Bossert NL, Behr B, De Jonge CJ, Baer TM, Reijo Pera RA. Non-invasive imaging of human embryos before embryonic genome activation predicts development to the blastocyst stage. Nat Biotechnol. 2010 Oct;28(10):1115-21. doi: 10.1038/nbt.1686. Epub 2010 Oct 3. PMID 20890283
• Miyazaki S, Ito M. Calcium signals for egg activation in mammals. J Pharmacol Sci. 2006;100(5):545-52. doi: 10.1254/jphs.cpj06003x. PMID 16799264
• Fulton BP, Whittingham DG. Activation of mammalian oocytes by intracellular injection of calcium. Nature. 1978 May 11;273(5658):149-51. doi: 10.1038/273149a0. No abstract available. PMID 565475
• Ducibella T, Schultz RM, Ozil JP. Role of calcium signals in early development. Semin Cell Dev Biol. 2006 Apr;17(2):324-32. doi: 10.1016/j.semcdb.2006.02.010. Epub 2006 Mar 2. PMID 16580237

Identifiers

NCT: NCT07684339 · FAKIHIVF-001 · DOH/ADHRTC/2024/2075

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗