Sildenafil Citrate Downregulates PDE5A mRNA Expression in Women with Recurrent Pregnancy Loss without Altering Angiogenic Factors—A Preliminary Study

Abstract

In our previous study, we showed that sildenafil citrate (SC), a selective PDE5A blocker, modulated NK cell activity in patients with recurrent pregnancy loss, which correlated with positive pregnancy outcomes. It was found that NK cells had a pivotal role in decidualization, angiogenesis, spiral artery remodeling, and the regulation of trophoblast invasion. Thus, in the current study, we determined the effects of SC on angiogenic factor expression and production, as well as idNK cell activity in the presence of nitric synthase blocker L-NMMA. Methods: NK cells (CD56+) were isolated from the peripheral blood of 15 patients and 15 fertile women on MACS columns and cultured in transformation media containing IL-15, TGF-β, and AZA—a methylation agent—for 7 days in hypoxia (94% N2, 1% O2, 5% CO2). Cultures were set up in four variants: (1) with SC, (2) without SC, (3) with NO, a synthase blocker, and (4) with SC and NO synthase blocker. NK cell activity was determined after 7 days of culturing as CD107a expression after an additional 4h of stimulation with K562 erythroleukemia cells. The expression of the PDE5A, VEGF-A, PIGF, IL-8, and RENBP genes was determined with quantitative real-time PCR (qRT-PCR) using TaqMan probes and ELISA was used to measure the concentrations of VEGF-A, PLGF, IL-8, Ang-I, Ang-II, IFN–γ proteins in culture supernatants after SC supplementation. Results: SC downregulated PDE5A expression and had no effect on other studied angiogenic factors. VEGF-A expression was increased in RPL patients compared with fertile women. Similarly, VEGF production was enhanced in RPL patients’ supernatants and SC increased the concentration of PIGF in culture supernatants. SC did not affect the expression or concentration of other studied factors, nor idNK cell activity, regardless of NO synthase blockade.

Uterine NK cells underexpress KIR2DL1/S1 and LILRB1 in reproductive failure

“…It has been suggested that these cells could account for the greater likelihood of success in second and subsequent pregnancies (49) and if so, this would be consistent with a role for LILRB1 in optimizing placental development. For women with reproductive failure, studies on LILRB1 have mostly concentrated on pNK in RM patients (39,50) except for one study on uNK using termination samples stratified by uterine artery resistance (51). On balance, and in line with our findings, these studies reported reduced expression of LILRB1 in women with high risk of reproductive problems.…”

Uterine NK cells underexpress receptors recognizing HLA-C2 and HLA-G in reproductive failure

“…We found significantly lower expression of KIR2DL1/S1 in uNK subsets in the reproductive failure group compared to controls, and these findings were mirrored in pNK. Our finding in pNK is consistent with previous work which has reported a reduction in the expression of KIR2DL1 expression by pNK associated with reproductive failure (Ntrivalas et al ., 2002; Yamada et al ., 2004; Faridi et al ., 2011; Kniotek et al ., 2021), although we did not find a reduction in KIR2DL2 expression, which has also been reported (Ntrivalas et al ., 2002). Studies on uNK KIR expression have thus far included samples retrieved after TOP stratified to high and low risk of resistance index on uterine artery doppler (Wallace et al ., 2015) or post-surgical management of miscarriage (Wang et al ., 2014), which reported reduction in KIR2DL1/S1 but no change in KIR2DL2/L3/S2 associated with worse pregnancy outcomes.…”

“…It has been suggested that these cells could account for the greater likelihood of success in second and subsequent pregnancies (Goldman-Wohl et al ., 2019) and if so, this would be consistent with a role for LILRB1 in optimizing placental development. For women with reproductive failure, studies on LILRB1 have mostly concentrated on pNK in RM patients (Kniotek et al ., 2021; Habets et al ., 2022) except for one study on uNK using TOP samples stratified by uterine artery resistance (Wallace et al ., 2014). On balance, and in line with our findings, these studies reported reduced expression of LILRB1 in women with high risk of reproductive problems.…”

Identification of differentially expressed genes and signaling pathways in gestational diabetes mellitus by integrated bioinformatics analysis

“…Recent studies have shown that GLP1R [310], NEUROD1 [311], PPARGC1A [312], IGF1 [313], LRP1B [314], NOTCH2 [315], BAK1 [316], TLR2 [317], IL6R [318], TIMP1 [319], PIK3CD [320], PRKCA (protein kinase C alpha) [321], CXCR4 [322], RAB8A [323] and M6PR [324] are associated with GDM. Abnormal expression PDE5A was linked with abortion [325].…”