Dual Trigger Modulates Distinctive and Selective Pathways within Cumulus Cells Compared to HCG alone among Normal Responders – a Whole Transcriptome Investigation

Introduction: Dual trigger (DT), combining GnRH agonist (GnRHa) and hCG, has been reported as a promising regimen to improve clinical outcome compared to single trigger (ST) of hCG alone among normal responder patients during IVF. While FSH surge induction by GnRHa is a well-recognized, the specific molecular mechanism for these optimistic observations is not clear.

Aim: To investigate cumulus cells (CC) transcriptome after exposure to either DT or ST by next generation sequencing (NGS) in normal responder patients.

Materials & Methods: This prospective study included patients with a normal ovarian reserve undergoing IVF-ICSI and receiving either a ST (5000 units of hCG, N=4) or DT (5000 hCG + 0.2ml GnRHa, N=5). For each patient, CC of three expanded MII oocytes were trimmed, lysed, and RNA was extracted. Differential mRNA expression was evaluated by NGS. Biologically significant genes were determined by clinical relevance and participation in a defined pathway.

Results: Both groups had similar average AMH, AFC, gonadotropins consumption, and E2 on trigger day. 237 genes were differentially expressed in DT compared to ST (fold change 2 and false discovery rate < 0.05). Pathway analysis revealed pathways enriched for genes involved in cell division accompanied by suppression of immune response and related processes (ex. apoptotic signaling and cytokine production) in the DT cohort (Figure 1).

Conclusions: The addition of GnRHa significantly alters intra cellular processes within CC. This comprehensive transcriptome investigation aids in elucidating the molecular explanations for the clinical superiority observed by DT among normal responder patients.