Expression of IL-1β and implantation serine proteases is required for mouse blastocyst hatching

Abstract

Mammalian blastocyst hatching is critically an indispensable process for successful implantation. One of the major challenges in IVF clinics is to achieve superior embryonic development with intrinsically potent hatching-competent blastocyst. However, the molecular regulation of hatching phenomenon is poorly understood. In this study, we examined the expression and function of one of the cytokines, IL-1β during blastocyst hatching in the mouse. In particular, the expression of IL-1β (Interleukin-1β), IL-1ra (Interleukin-1 receptor antagonist) and their functional receptor IL-1rt1 (Interleukin 1 receptor type-1) in morulae, zona intact- and hatched- blastocysts was studied. Supplementation of IL-1β to cultured embryos accelerated blastocyst development with improved hatching (treated: 89.6 ± 3.6% vs untreated: 65.4 ± 4.1%). When embryos were treated with IL-1ra, blastocyst hatching was decreased (treated: 28.8 ± 3.1% vs untreated: 67.5 ± 3.8%). Moreover, IL-1β and IL-1ra influenced the expression of hatching enzymes viz., implantation serine proteases (ISP 1 and ISP 2). While IL-1β increased the embryonic mRNA expression of ISPs (ISP1: 2-4; ISP2: 9-11 fold), IL-1ra decreased expression. The protein localization studies revealed increased nuclear presence predominantly of ISP 2 in IL-1β treated blastocysts. This is the first report to show the functional significance of embryonic IL-1β in regulating hatching-associated proteases, particularly ISP2. These findings have implications in our understanding of molecular regulation of blastocyst hatching and implantation failure in other species including humans.

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

“…Consistent with this embryonic expression of proteases, IL‐1β is reported to mediate implantation‐associated uterine expression of proteases (van Mourik et al, 2009). The stimulating effect of IL‐1β on blastocyst development observed in the hamster is similar to that we observed earlier in mice (Pathak et al, 2021). Also, it is reported in the bovine species, albeit, with no detailed evaluation (Paula‐Lopes et al, 1998).…”

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.…”

“…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. In this previous study, embryos were developed in vivo until they reached the morulae stage and freshly recovered by flushing the mouse uterine horns.…”

“…Previous studies have shown that by modulating proteases, pro-inflammatory and anti-inflammatory cytokines improved hatching rates ( 5 ), which may reflect the in vivo interaction between the blastocyst and the microenvironment/maternal immune system. It was published in 2021 that IL-1β (interleukin-1β) was indispensable for mouse blastocyst hatching by regulating the hatching-associated protease ISP2 ( 6 ). The same group also reported that supplementation of IL-1β 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-1β in trophectodermal projections of the golden hamster hatching blastocysts ( 7 ).…”

Gaq-PKD/PKCμ regulates the IkB transcription to limit the NF-kB mediated inflammatory response essential for early pregnancy

“…Both pro-inflammatory and anti-inflammatory cytokine (of endometrial and embryonic origin) are potentially required to maintain normal pre-implantation embryo development and blastocyst hatching, leading to successful implantation (Pathak, Vani et al 2021). Deferred or failed blastocyst hatching can lead to blastocyst implantation failure (Khorram, Shapiro et al 2000), and 14 delayed or failed blastocyst adhesion miss the "implantation window" lead to infertility or early pregnancy loss.…”