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Fetal Membranes Canadian Journal of Physiology and Pharmacology Cyclo-oxygenase inhibitors for treating preterm labour: what is the molecular evidence? Journal: Canadian Journal of Physiology and Pharmacology Manuscript ID cjpp-2018-0380.R1 Manuscript Type: Article Date Submitted by the 09-Dec-2018 Author: Complete List of Authors: Urrego, Daniela; University of Calgary Cumming School of Medicine, Physiology and Pharmacology Liwa, Anthony; University of Calgary Cumming School of Medicine, Physiology and Pharmacology; Catholic University of Health And Allied Sciences WeillDraft Bugando School of Medicine, Clinical Pharmacology Cole, William; University of Calgary Cumming School of Medicine, Physiology and Pharmacology Wood, Stephen; University of Calgary Cumming School of Medicine, Obstetrics and Gynecology; University of Calgary Cumming School of Medicine, O'Brien Institute for Public Health Slater, Donna; University of Calgary Cumming School of Medicine, Physiology and Pharmacology; University of Calgary Cumming School of Medicine, Obstetrics and Gynecology Is the invited manuscript for consideration in a Special Connecting Maternal Fetal Newborn Physiology Issue: Cyclooxygenase, Preterm Labour, Pregnancy, Myometrium, Fetal Keyword: Membranes https://mc06.manuscriptcentral.com/cjpp-pubs Page 1 of 42 Canadian Journal of Physiology and Pharmacology 1 Cyclo-oxygenase inhibitors for treating preterm labour: what is the molecular evidence? 2 3 Daniela Urrego1*, Anthony C Liwa1,2, William C Cole1, Stephen Wood3, Donna M Slater1,3* 4 5 1Department of Physiology and Pharmacology, Cumming School of Medicine, University of 6 Calgary, 3330 Hospital Drive NW Calgary, AB, Canada T2N 4N1. 7 8 2Department of Clinical Pharmacology, Weill School of Medicine, Catholic University of Health 9 and Allied Sciences, PO Box 1464, Mwanza,Draft Tanzania. 10 11 3Department of Obstetrics and Gynaecology, Cumming School of Medicine, University of 12 Calgary, 3330 Hospital Drive NW Calgary, AB, Canada T2N 1N4. 13 14 *Corresponding Author: 15 Daniela Urrego 16 Room 280 Heritage Medical Research Building 17 3330 Hospital Drive NW, Calgary, AB, Canada, T2N 4N1 18 [email protected] 19 20 1 https://mc06.manuscriptcentral.com/cjpp-pubs Canadian Journal of Physiology and Pharmacology Page 2 of 42 21 22 Draft 2 https://mc06.manuscriptcentral.com/cjpp-pubs Page 3 of 42 Canadian Journal of Physiology and Pharmacology 23 Abstract 24 Preterm birth (<37 weeks of gestation) significantly increases the risk of neonatal mortality and 25 morbidity. As many as half of all preterm births occur following spontaneous preterm labour. 26 Since in such cases there are no known reasons for the initiation of labour, treatment of preterm 27 labour (tocolysis) has sought to stop labour contractions and delay delivery. Despite some 28 success, the use of cyclooxygenase (COX) inhibitors is associated with maternal/fetal side effects, 29 and possibly increased risk of preterm birth. Clinical use of these drugs predates the collection 30 of molecular and biochemical evidence in vitro, examining the expression and activity of COX 31 enzymes in pregnant uterine tissues withDraft and without labour. Such evidence is important to the 32 rationale that COX enzymes are, or are not, appropriate targets for the tocolysis. The current 33 study systematically searched existing scientific evidence to address the hypothesis that COX 34 expression/activity is increased with the onset of human labour, in an effort to determine whether 35 there is a rationale for the use of COX inhibitors as tocolytics. Our review identified 40 studies, 36 but determined that there is insufficient evidence to support or refute a role of COX-1/-2 in the 37 onset of preterm labour that supports COX-targetted tocolysis. 38 39 Keywords: Cyclooxygenase, Cyclooxygenase inhibitors, Preterm, Labour, Pregnancy, 40 Prostaglandins, Tocolysis, Myometrium, Decidua, Fetal Membranes 41 42 Introduction 3 https://mc06.manuscriptcentral.com/cjpp-pubs Canadian Journal of Physiology and Pharmacology Page 4 of 42 43 Preterm birth (<37 weeks) is associated with increased risk of neonatal mortality and morbidity, 44 and occurs in 10% of all pregnancies (Purisch and Gyamfi-Bannerman 2017). Of these 45 approximately half are due to the onset of spontaneous labour contractions (Ananth and 46 Vintzileos 2006; Goldenberg et al. 2008). Key treatments for preterm labour have focused on the 47 prevention or inhibition of myometrial contractions (tocolytics), mainly to provide time to 48 administer steroids to aid fetal lung maturation, and transfer to a special neonatal care unit 49 (Vogel et al. 2014; Haram et al. 2015). One tocolytic agent used to treat preterm labour is 50 indomethacin, a non-steroidal anti-inflammatory drug (NSAID) (Zuckerman et al. 1974). 51 Indomethacin decreases production ofDraft the prostaglandins, implicated to be important in the 52 labour process (Wiqvist et al. 1974; Vane and Williams 1973; Olson et al. 1995). The mechanism 53 of action of indomethacin, and other NSAIDs, is the inhibition of cyclooxygenase (COX), a key 54 enzyme in prostaglandin synthesis, thereby reducing prostaglandin production (Figure 1) (Vane 55 1971; Flower and Vane 1974; Vane and Botting 1998). A second COX enzyme, COX-2 (PTGS2, 56 official gene symbol) was subsequently identified and shown to be rapidly inducible by 57 inflammatory mediators, in contrast to COX-1 (PTGS1, official gene symbol) that is generally 58 constitutively expressed (Hla and Neilson 1992; Appleby et al. 1994; Needleman and Isakson 59 1997). The existence of two COX enzymes, each with distinct regulation and function, supported 60 a rationale for selectively inhibiting COX-2 over COX-1, and thus inhibiting inflammatory versus 61 constitutive prostaglandin production (Vane and Botting 1995; Mitchell et al. 1993). 4 https://mc06.manuscriptcentral.com/cjpp-pubs Page 5 of 42 Canadian Journal of Physiology and Pharmacology 62 Indeed, administration of the non-selective COX inhibitor, indomethacin, to women in 63 preterm labour led to a dramatic cessation of uterine contractions (Zuckerman et al. 1974; Gyory 64 et al. 1974). This approach was met with optimism since preterm labour was successfully delayed 65 for up to seven days. However, subsequent studies revealed that indomethacin use is associated 66 with a variety of maternal and fetal side effects, including oligohydramnios, premature closure 67 of the ductus arteriosus, necrotizing enterocolitis and intraventricular hemorrhage (Norton et al. 68 1993; Sood et al. 2011; Van der Veyver et al. 1993). These side effects were thought to be related 69 to COX-1 inhibition, thus the use of COX-2 selective inhibition was explored (Needleman and 70 Isakson 1997; Smith et al. 1996; Vane andDraft Botting 1995). 71 The first clinical report of COX-2 selective inhibition for preterm birth prevention was 72 described by Sawdy et al. (1997). In a pregnant patient with recurrent miscarriage, the COX-2 73 selective inhibitor nimesulide was administered prophylactically from 16 weeks gestation. 74 Nimesulide treatment was stopped at 34 weeks and delivery occurred six days later (Sawdy et al. 75 1997). This single case study report offered new hope, and rationale for the use of COX-2 76 selective inhibitors as tocolytics to delay preterm birth. However, subsequent reports described 77 severe neonatal renal damage after prolonged maternal exposure to nimesulide, suggesting 78 COX-2 is important for normal fetal kidney development and function, and not only involved in 79 pathogenic inflammation (Peruzzi et al. 1999; Balasubramaniam 2000; Magnani et al. 2004). Most 80 concerning, in a clinical trial with women at high risk of preterm delivery, the use of rofecoxib 81 (COX-2 selective inhibitor), not only failed to prevent, but further increased the risk of preterm 5 https://mc06.manuscriptcentral.com/cjpp-pubs Canadian Journal of Physiology and Pharmacology Page 6 of 42 82 birth (Groom et al. 2005). More recent studies have also found that exposure to COX inhibitors, 83 and especially COX-2 selective inhibitors, in late pregnancy increase the risk of premature 84 delivery (Berard et al. 2018). Still, other groups report the possible benefits of low dose aspirin 85 taken prophylactically to reduce the risk of preterm delivery (Andrikopoulou et al. 2018). 86 Current obstetric practice generally suggests limiting indomethacin as a tocolytic, to 87 pregnancies <32 weeks, for temporary (<48 hours) delay of preterm birth (ACOG, 2016). Since 88 COX-inhibition for acute tocolysis is not fully effective, opportunities for further refinement of 89 this approach remain (Reinebrant et al. 2015). There is a paucity of scientific evidence to make 90 solid recommendations on the clinical useDraft of either selective or non-selective COX inhibitors to 91 prevent or treat preterm labour (Khanprakob et al. 2012). To this end, molecular/biochemical in 92 vitro studies sought to determine whether COX enzymes are active and/or upregulated with 93 labour. Studies reporting increased expression and/or activity of either COX-1 and/or COX-2 94 enzyme contrast widely when comparing the gestational tissues, patient groups studied, and 95 methodologies used. That prostaglandins can elicit labour contractions is clear, but whether, or 96 not, inhibition of either COX-1 and/or COX-2, key enzymes in prostaglandin synthesis, provide 97 the best target for tocolysis is uncertain. Therefore, we have systematically evaluated the in vitro 98 scientific literature, to interrogate the evidence
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