Differential effects of medroxyprogesterone acetate on thrombosis and atherosclerosis in mice

A Rare Case of Splenic Artery Thrombosis Provoked By Medroxyprogesterone Acetate Requiring Splenectomy

Splenic artery thrombosis is estimated to occur in only 0.016% of hospital admissions. Hormonal contraception is known to have hypercoagulable side effects, but splenic artery thrombosis (SAT) followed by functional autosplenectomy is a very rare side effect. We report a case of a 48-year-old female with persistent SAT provoked by depot medroxyprogesterone acetate (DMPA). She initially presented with severe left lower quadrant abdominal pain, and imaging revealed an extensive thrombus in the splenic artery. She was immediately started on intravenous heparin, and her symptoms improved after a few days, at which point she was discharged on oral apixaban. Three months after discharge, the patient presented with symptoms similar to the initial presentation. Further history revealed that she received an injectable DMPA shot prior to her initial admission. Other possible causes of SAT were ruled out. On imaging, her previous thrombus had increased in size and now filled the entire splenic artery. Therefore, the patient underwent robotic splenectomy with remarkable improvement in her symptoms. This case represents a rare clinical manifestation of a hypercoagulable state induced by DMPA. We review the existing literature to explain the epidemiology, presentation, diagnosis, and treatment of SAT, and incorporate our patient's presentation into the existing literature regarding the effect of contraception in inducing thrombotic events.

Effects of Estrogens on Platelets and Megakaryocytes

In women, oral menopausal hormonal therapy (MHT) is associated with adverse effects including an increased incidence of thromboembolic events, classically attributed to an increase in several liver-derived coagulation factors due to hepatic first pass. While platelets are central players in thrombus constitution, their implication in women treated with estrogens remains incompletely characterized. Platelets and their medullar progenitors, megakaryocytes, express estrogen receptors (ER) that may explain, at least in part, a sensitivity to hormonal changes. The purpose of this review is to summarize our current knowledge of estrogen actions on platelets and megakaryocytes in mice following in vivo administration and in women using MHT.

Association between progestin-only contraceptive use and cardiometabolic outcomes: A systematic review and meta-analysis

Aims The association between progestin-only contraceptive (POC) use and the risk of various cardiometabolic outcomes has rarely been studied. We performed a systematic review and meta-analysis to determine the impact of POC use on cardiometabolic outcomes including venous thromboembolism, myocardial infarction, stroke, hypertension and diabetes. Methods and results Nineteen observational studies (seven cohort and 12 case-control) were included in this systematic review. Of those, nine studies reported the risk of venous thromboembolism, six reported the risk of myocardial infarction, six reported the risk of stroke, three reported the risk of hypertension and two studies reported the risk of developing diabetes with POC use. The pooled adjusted relative risks (RRs) for venous thromboembolism, myocardial infarction and stroke for oral POC users versus non-users based on the random effects model were 1.06 (95% confidence interval (CI) 0.70-1.62), 0.98 (95% CI 0.66-1.47) and 1.02 (95% CI 0.72-1.44), respectively. Stratified analysis by route of administration showed that injectable POC with a RR of 2.62 (95% CI 1.74-3.94), but not oral POCs (RR 1.06, 95% CI 0.7-1.62), was associated with an increased risk of venous thromboembolism. A decreased risk of venous thromboembolism in a subgroup of women using an intrauterine levonorgestrel device was observed with a RR of 0.53 (95% CI 0.32-0.89). No effect of POC use on blood pressure was found, but there was an indication for an increased risk of diabetes with injectable POCs, albeit non-significant. Conclusions This systematic review and meta-analysis suggests that oral POC use is not associated with an increased risk of developing various cardiometabolic outcomes, whereas injectable POC use might increase the risk of venous thromboembolism.

Effect of chronic estradiol plus progesterone treatment on experimental arterial and venous thrombosis in mouse

Postmenopausal hormone replacement therapy (HRT) with estrogen plus progestogens is the first line therapy to treat menopausal symptoms. The progestogen is added to estrogen to reduce or eliminate the excess risk of endometrial cancer due to the unopposed effect of estrogen. Whereas progestin clearly opposes the proliferative and deleterious long-term actions of estrogen on the endometrium, the interference of progestin on the other estrogen action remains unclear. We previously reported that chronic subcutaneous 17α-estradiol (E2) in mice decreases platelet responsiveness, prolongs the tail-bleeding time and protects against acute thromboembolism. Here, we report the tissue-specific interference of progesterone (P4) on the action of E2 in ovariectomized mice. We first confirm that, in our experimental conditions, P4 attenuates the proliferative action of E2 on the uterus and the effects of E2 on vagina weight and lubrication. We then studied the effect of E2 combined with P4 on hemostasis and thrombosis in vivo in mice and found that P4 did not interfere with the main actions of E2 on platelets, bleeding time and arterial and venous thrombosis. Thus, whereas activation of progesterone receptor interferes with the action of E2 on its classic sex targets, P4 appears to have minimal effect on the hemostasis and thrombosis actions of E2, supporting the prominent role of estrogens and the accessory role of natural progestin on the extra-reproductive cells and tissues involved in thrombosis.

Synthetic gestagens exert differential effects on arterial thrombosis and aortic gene expression in ovariectomized apolipoprotein E-deficient mice

BACKGROUND AND PURPOSE

Combined hormone replacement therapy with oestrogens plus the synthetic progestin medroxyprogesterone acetate (MPA) is associated with an increased risk of thrombosis. However, the mechanisms of this pro-thrombotic effect are largely unknown. The purpose of this study was to: (i) compare the pro-thrombotic effect of MPA with another synthetic progestin, norethisterone acetate (NET-A), (ii) determine if MPA's pro-thrombotic effect can be antagonized by the progesterone and glucocorticoid receptor antagonist mifepristone and (iii) elucidate underlying mechanisms by comparing aortic gene expression after chronic MPA with that after NET-A treatment.

EXPERIMENTAL APPROACH

Female apolipoprotein E-deficient mice were ovariectomized and treated with placebo, MPA, a combination of MPA + mifepristone or NET-A for 90 days on a Western-type diet. Arterial thrombosis was measured in vivo in a photothrombosis model. Aortic gene expression was analysed using microarrays; GeneOntology and KEGG pathway analyses were conducted.

KEY RESULTS

MPA's pro-thrombotic effects were prevented by mifepristone, while NET-A did not affect arterial thrombosis. Aortic gene expression analysis showed, for the first time, that gestagens induce similar effects on a set of genes potentially promoting thrombosis. However, in NET-A-treated mice other genes with potentially anti-thrombotic effects were also affected, which might counterbalance the effects of the pro-thrombotic genes.

CONCLUSIONS AND IMPLICATIONS

The pro-thrombotic effects of synthetic progestins appear to be compound-specific, rather than representing a class effect of gestagens. Furthermore, the different thrombotic responses elicited by MPA and NET-A might be attributed to a more balanced, 'homeostatic' gene expression induced in NET-A- as compared with MPA-treated mice.

Molecular biology of atherosclerosis

At least 468 individual genes have been manipulated by molecular methods to study their effects on the initiation, promotion, and progression of atherosclerosis. Most clinicians and many investigators, even in related disciplines, find many of these genes and the related pathways entirely foreign. Medical schools generally do not attempt to incorporate the relevant molecular biology into their curriculum. A number of key signaling pathways are highly relevant to atherogenesis and are presented to provide a context for the gene manipulations summarized herein. The pathways include the following: the insulin receptor (and other receptor tyrosine kinases); Ras and MAPK activation; TNF-α and related family members leading to activation of NF-κB; effects of reactive oxygen species (ROS) on signaling; endothelial adaptations to flow including G protein-coupled receptor (GPCR) and integrin-related signaling; activation of endothelial and other cells by modified lipoproteins; purinergic signaling; control of leukocyte adhesion to endothelium, migration, and further activation; foam cell formation; and macrophage and vascular smooth muscle cell signaling related to proliferation, efferocytosis, and apoptosis. This review is intended primarily as an introduction to these key signaling pathways. They have become the focus of modern atherosclerosis research and will undoubtedly provide a rich resource for future innovation toward intervention and prevention of the number one cause of death in the modern world.

Assessing the risk of venous thromboembolic events in women taking progestin-only contraception: a meta-analysis

OBJECTIVES

To evaluate the risk of venous thromboembolic events associated with the use of progestin-only contraception and whether that risk differs with the mode of drug delivery (oral, intrauterine, or depot injection).

DESIGN

Systematic review and meta-analysis of randomised controlled trials and observational studies.

DATA SOURCES

Pubmed, Embase, Cochrane Library, and reference lists of relevant reviews.

STUDY SELECTION

Randomised controlled trials and case-control, cohort, and cross sectional studies with venous thromboembolic outcome for progestin-only contraception reported relative to a non-hormone comparator group.

DATA EXTRACTION

Data were extracted by two independent investigators, and consensus for inclusion was reached after assessment by additional investigators.

RESULTS

Among the 2022 unique references identified by all searches, eight observational studies fulfilled inclusion criteria. A total of 147 women across all studies were diagnosed with a venous thromboembolic event while taking progestin-only contraception, and the summary measure for the adjusted relative risk of a venous thromboembolic episode for users versus non-users of a progestin-only contraceptive was, based on the random effects model, 1.03 (95% CI 0.76 to 1.39). Subgroup analysis confirmed there was no association between venous thromboembolic risk and progestin-only pills (relative risk 0.90 (0.57 to 1.45)) or a progestin intrauterine device (0.61 (0.24 to 1.53)). The relative risk of a venous thromboembolic event for users of an injectable progestin versus non-users was 2.67 (1.29 to 5.53).

CONCLUSIONS

Published data assessing the risk of venous thromboembolism in women prescribed progestin-only contraception are limited. In this meta-analysis of eight observational studies, the use of progestin-only contraception was not associated with an increased risk of venous thromboembolism compared with non-users of hormonal contraception. The potential association between injectable progestins and thrombosis requires further study.