Expression and function of interleukin‐1β is required for hamster blastocyst hatching: Involvement of hatching‐associated cathepsin proteases

Abstract

In mammals, the phenomenon of blastocyst hatching is an essential prerequisite for successful implantation. Blastocyst hatching is regulated by various molecules. Of them, cytokines, expressed by preimplantation embryos, are thought to be functionally important in blastocyst development and hatching, but their mechanistic roles are not clearly understood. Here, we examined the involvement of two cytokines, namely, interleukin‐1β (IL‐1β) and its natural antagonist, IL‐1ra, in blastocyst hatching in the golden hamster. Blastocysts expressed both cytokines and their receptor, IL‐1rt1. Supplementation of IL‐1β to cultured eight‐cell embryos improved blastocyst hatching (84.1% ± 4.2% vs. 66.6% ± 6.8%; treated vs. control). This improvement was diminished by IL‐1ra treatment (23.6% ± 12.9% vs. 76.4% ± 12.9%; treated vs. control). Interestingly, IL‐1β‐treated embryos showed increased messenger RNA expression of zonalytic proteases, that is, cathepsin‐L and ‐B by 1.9 ± 0.5‐ and 3.5 ± 0.1‐folds, respectively. This was accompanied by their increased enzyme activities; cathepsin‐L by 2.8 ± 0.7 fold and ‐B by 2.3 ± 0.7‐fold. Strikingly, proteases and IL‐1β were intensely colocalized to trophectodermal projections of hatching blastocysts. This is the first report to show the involvement of embryonic IL‐1β in regulating hatching‐associated proteases required for blastocyst hatching.

Neddylation Inhibition Causes Impaired Mouse Embryo Quality and Blastocyst Hatching Failure Through Elevated Oxidative Stress and Reduced IL-1β

“…The decreased level of secreted IL-1β in hatching-impaired MLN4924-treated blastocysts is in accordance with previous published studies. Researchers showed the supplement of pro-inflammatory cytokine IL-1β improved the blastocyst hatching in both mouse and golden hamster embryos by promoting the expressions of related proteases ( 6 , 7 ). We noticed that the immunofluorescence staining pattern of IL-1β in our study, the sporadic intercellular dots, was different from the previous study ( 6 ) and it could be due to the following two reasons.…”

“…It was published in 2021 that IL-1b (interleukin-1b) was indispensable for mouse blastocyst hatching by regulating the hatching-associated protease ISP2 (6). The same group also reported that supplementation of IL-1b to 8-cell embryos greatly increased their hatching rate, together with the enhanced expressions and activities of zonalytic proteases, cathepsin-L and cathepsin-B, which were colocalized with IL-1b in trophectodermal projections of the golden hamster hatching blastocysts (7). However more detailed molecular mechanisms remain poorly understood.…”

Molecular regulators of human blastocyst development and hatching: Their significance in implantation and pregnancy outcome

“…20 Importantly, hamsters exhibit a striking blastocyst hatching behavior and they also exhibit actin-based trophectodermal projections (TEPs), harboring hatching-enabling molecular factors during hatching. [20][21][22][23][24] TEPs are also observed in mouse, bovine and equine species. 25,26 Interestingly, human blastocysts also appear to exhibit TEPs.…”

“…This is not notwithstanding the fact that cellular events of blastocyst hatching and implantation have been relatively well studied. 10,[20][21][22][23]25,28,29 Blastocyst hatching-related deficiencies account for a major cause of human infertility, accounting for 30% implantation failure. Zona hardening phenomenon contributes to the hatching failure, which is being mitigated by assisted hatching (AH) procedure in ART clinics.…”

“…A Hormone: factor (LIF) 23,28,29,63,[69][70][71][72] and soluble human leukocyte antigen-G (sHLA-G). 63,[73][74][75] Proteases include matrix metalloproteinases (MMP), tissue plasminogen activators (tPAs), cathepsins, implantation serine proteinases (ISPs).…”