Investigating ticagrelor in a preclinical pipeline as a novel therapeutic to prevent preterm birth.

In brief: Preterm birth is the leading cause of perinatal morbidity and mortality, and new therapies that delay preterm birth and improve neonatal outcomes are urgently needed. This study investigates whether ticagrelor inhibits uterine contractility and inflammation in preclinical in vitro, ex vivo (human) and in vivo (mouse) studies, to explore the potential of repurposing ticagrelor for the prevention of preterm birth. Abstract: Preterm birth remains a significant global health challenge, affecting approximately 10% of pregnancies and resulting in one million deaths globally every year. Tocolytic agents, used to manage preterm labour, have considerable limitations including lack of efficacy, and adverse side effects, emphasising the urgent need for innovative solutions. Here, we explore repurposing an antiplatelet cardioprotective drug, ticagrelor, as a potential treatment to prevent preterm birth. Ticagrelor has demonstrated pleiotropic actions beyond platelet inhibition, including relaxant effects on smooth muscle cells and anti-inflammatory effects in models of diabetes and sepsis. As preterm birth is underscored by inflammatory processes triggering uterine contractions, these actions position ticagrelor as an attractive candidate for prevention or delay of preterm birth. Utilising primary human myometrial tissue, human myometrial cells, and a mouse model of preterm birth, we investigated ticagrelor's potential as a safe and effective therapy for preterm birth. We showed that ticagrelor did not reduce the frequency or strength of spontaneous muscle contractions of ex vivo myometrial tissue nor did it reduce in vitro inflammation-induced contractility in myometrial cells. Additionally, ticagrelor did not exhibit the anticipated anti-inflammatory effects in myometrial cell culture experiments. In our mouse model of preterm birth, ticagrelor neither improved the preterm birth rate or fetal survival outcomes. Gene expression of pro-inflammatory cytokines and contraction-associated proteins in postpartum mouse uteri were unaltered by ticagrelor. In conclusion, ticagrelor is not a strong candidate to continue investigations in clinical trial for the treatment of preterm labour and prevention of preterm birth.

Assessment of the tocolytic nifedipine in preclinical primary models of preterm birth.

Spontaneous preterm birth is the leading cause of perinatal morbidity and mortality. Tocolytics are drugs used in cases of imminent preterm birth to inhibit uterine contractions. Nifedipine is a calcium channel blocking agent used to delay threatened spontaneous preterm birth, however, has limited efficacy and lacks preclinical data regarding mechanisms of action. It is unknown if nifedipine affects the pro-inflammatory environment associated with preterm labour pathophysiology and we hypothesise nifedipine only targets myometrial contraction rather than also mitigating inflammation. We assessed anti-inflammatory and anti-contractile effects of nifedipine on human myometrium using in vitro and ex vivo techniques, and a mouse model of preterm birth. We show that nifedipine treatment inhibited contractions in myometrial in vitro contraction assays (P = 0.004 vs. vehicle control) and potently blocked spontaneous and oxytocin-induced contractions in ex vivo myometrial tissue in muscle myography studies (P = 0.01 vs. baseline). Nifedipine treatment did not reduce gene expression or protein secretion of pro-inflammatory cytokines in either cultured myometrial cells or ex vivo tissues. Although nifedipine could delay preterm birth in some mice, this was not consistent in all dams and was overall not statistically significant. Our data suggests nifedipine does not modulate preterm birth via inflammatory pathways in the myometrium, and this may account for its limited clinical efficacy.

Immune regulatory cytokines in seminal plasma of healthy men: A scoping review and analysis of variance.

OBJECTIVE: Seminal plasma cytokines are associated with fertility and reproductive health, but progressing their clinical utility is hampered by absence of reference data on concentration ranges of relevant cytokines in healthy men. We employed a systematic approach to assemble current evidence on the concentrations of immune regulatory cytokines present in seminal plasma (SP) of normozoospermic and/or fertile men and evaluated the impact of different platform methodologies for cytokine quantification. EVIDENCE REVIEW: A systematic literature search was performed utilising PubMed, Web of Science and Scopus. Databases were searched from inception until 30th June 2022 inclusive, using combinations of keywords pertaining to seminal fluid and cytokines, and was restricted to human participants. Original data with values reported as concentration of specific cytokines in SP of men clearly defined as fertile or normozoospermic were extracted from studies written in English. RESULTS: A total of 3769 publications were initially identified, of which 118 fulfilled the eligibility criteria for inclusion. A total of 51 individual cytokines are detectable in SP of healthy men. The number of studies reporting on each cytokine range from 1 to >20. The reported concentrations for many cytokines linked with fertility status, including IL6, CXCL8/IL8, and TNFA, are highly variable between published studies. This is associated with the different immunoassay methodologies utilised and may be exacerbated by a lack of validation of assays to ensure suitability for SP assessment. Due to the large variation between studies, accurate reference ranges for healthy men cannot be determined from the published data. CONCLUSIONS: The concentrations of cytokines and chemokines detected in SP is inconsistent and highly variable between studies and cohorts, limiting current capacity to define reference ranges for cytokine concentrations in fertile men. The lack of standardisation in methods used to process and store SP, and variation in platforms used to evaluate cytokine abundance, are factors contributing to the observed heterogeneity. To progress the clinical utility of SP cytokine analysis will require standardisation and validation of methodologies so that reference ranges for healthy fertile men can be defined.

Repurposing existing drugs as a therapeutic approach for the prevention of preterm birth.

In brief: Preterm birth is the leading cause of perinatal morbidity and mortality; however, current therapies offer limited efficacy to delay birth and improve neonatal outcomes. This review explores the potential of repurposing drugs with known safety profiles to quench uterine contractions and inflammation, identifying promising agents for clinical trials. Abstract: Preterm birth is the leading cause of neonatal morbidity and mortality globally. Despite extensive research into the underlying pathophysiology, rates of preterm birth have not significantly reduced. Currently, preterm labour management is based on optimising neonatal outcomes. Treatment involves administering drugs (tocolytics) to suppress uterine contractions to allow sufficient time for transfer to an appropriate facility and administration of antenatal corticosteroids for fetal lung maturation. Current tocolytics are limited as they are associated with adverse maternal and fetal effects and only delay delivery for a short period. There has been a serious lack of therapeutic development for preterm birth, and new approaches to protect against or delay preterm birth are urgently needed. Repurposing drugs for the prevention of preterm birth presents as a promising approach by reducing the time and costs associated with pharmaceutical drug development. In this review, we explore the evidence for the potential of therapies, specifically proton pump inhibitors, tumour necrosis factor inhibitors, prostaglandin receptor antagonists, aspirin, and statins, to be repurposed as preventatives and/or treatments for preterm birth. Importantly, many of these innovative approaches being explored have good safety profiles in pregnancy. We also review how delivery of these drugs can be enhanced, either through targeted delivery systems or via combination therapy approaches. We aim to present innovative strategies capable of targeting multiple aspects of the complex pathophysiology that underlie preterm birth. There is an urgent unmet need for preterm birth therapeutic development, and these strategies hold great promise for improving neonatal outcomes.