Cardiometabolic effects of SGLT2 inhibitors on polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a complex endocrinopathy affecting many women of reproductive age. Although its physiology is poorly understood, hyperandrogenemia and insulin resistance play a pivotal role in this complex syndrome, predisposing patients to a variety of cardiovascular and metabolic modalities. Current therapeutic options, including lifestyle modifications and medications, often do not satisfactorily improve clinical outcomes. SGLT2 inhibitors (SGLT‐2i) are a novel option which can potentially improve many hormonal and metabolic parameters for patients with PCOS, though the net cardiovascular effects remain under investigation in this population of patients with PCOS. Overall, the use of SGLT‐2i may be associated with beneficial somatometric, metabolic and hormonal outcomes of PCOS. To date, all available studies have recorded body mass index, waist and hip circumference, and fat mass reductions, improved insulin and androgen levels, and reduced blood pressure. The aim of the present review is to summarise PCOS‐related manifestations and mechanisms leading to cardiovascular disease, to explore the cardiometabolic impact of SGLT2i on PCOS, and to critically analyse the cardiometabolic and hormonal outcomes of the recent studies on the use of SGLT2i in women with PCOS.


| INTRODUCTION
Polycystic ovary syndrome (PCOS) constitutes a heterogeneous endocrinopathy, mainly affecting women of reproductive age with a prevalence varying from 5% to 20%. [1][2][3] The principal characteristics of PCOS include hyperandrogenism, oligo-anovulation and/or polycystic ovary morphology (PCOM). [1][2][3][4][5][6] PCOS is mainly observed in women with obesity; nevertheless, there are also many lean PCOS patients. 7 The exact aetiology of PCOS remains unknown, arising from multifactorial influences, including genetic, epigenetic, and environmental factors. [8][9][10] PCOS is associated with insulin resistance (IR), Type 2 Diabetes Mellitus (T2DM), dyslipidemia, obesity, and chronic systemic inflammation. 3,[11][12][13][14] These conditions predispose women with PCOS to the development or aggravation of cardiovascular disease, including hypertension and subclinical atherosclerotic plaque formation at a young age. 3,11,13,[15][16][17] Treatment of PCOS is largely symptomatic. The use of insulin sensitizers (metformin, thiazolidinediones) seemed successful in improving ovulation and reducing androgen levels in a doseresponsive manner. 18 The restoration of spontaneous ovulation and improved fertility in women with PCOS have been shown to be achieved with oral administration of inositol compounds. 19,20 However, for years, limited options were available to improve cardiometabolic outcomes in PCOS. 21,22 Sodium-glucose cotransporter 2 inhibitors (SGLT2i) constitute a novel anti-diabetic drug family which targets the kidney, enhances glucose excretion, provides glycaemic control, and ameliorates glucotoxicity. 23 Moreover, SGLT2i reduce blood pressure and induce haemodynamic effects, leading to improved cardiovascular and renal outcomes in patients with or without T2DM. [23][24][25][26] These characteristics make SGLT2i an appealing tool for ameliorating PCOS-associated cardiometabolic diseases. To date, very few studies have examined the role of SGLT2i use in women with PCOS. Therefore, the aim of the present review was to summarise PCOSrelated manifestations and mechanisms leading to cardiovascular disease, to explore the potential ways SGLT2i can affect the pathophysiology of PCOS, and to critically analyse the latest studies exploring SGLT2i use in women with PCOS and their cardiometabolic impacts.

| PATHOGENESIS OF PCOS
PCOS is the most common endocrine disorder in women of reproductive age with a reported prevalence varying between 6% and 10% according to the applied diagnostic criteria. 1,[4][5][6]27 The Rotterdam consensus (ESHRE/ASRM) is the most widely used PCOS diagnostic classification, which requires at least two of the following criteria for the diagnosis of PCOS: oligo-anovulation, clinical and/or biochemical hyperandrogenism, and polycystic ovary morphology (PCOM). 28 The National Institutes of Health (NIH/NICHD) criteria require both clinical and/or biochemical hyperandrogenism and chronic anovulation and androgen excess. Lastly, the PCOS Society requires clinical and/or biochemical hyperandrogenism for the diagnosis of PCOS, combined with oligo-/anovulation or PCOM. [29][30][31] Several genetic, epigenetic and environmental factors such as exposure to industrial endocrine disruptors, in utero exposure to androgens and anti-Müllerian hormone (AMH), and obesity are associated with PCOS. 32 The excessive release of luteinizing hormone (LH) by the anterior pituitary gland and the hyperinsulinemia is associated with the pathogenesis of PCOS, although the exact pathophysiology is not elucidated. 32 Hyperandrogenism is a hallmark of PCOS, and sources of excess androgens include the ovaries, the adrenal glands, and peripheral tissues, such as the adipose tissue, which convert pro-androgens into active metabolites. [33][34][35][36] Insulin resistance in PCOS has been demonstrated to exacerbate hyperandrogenemia by disrupting the hypothalamic-pituitary-ovarian axis, by stimulating the secretion of ovarian androgens, and inhibiting the production of sex hormone-binding globulin (SHBG), resulting in a vicious circle. 18,27 To some extent, an intrinsic resistance to insulin action pre-exists in PCOS, independent of obesity, which in combination with habitual obesogenic factors (lifestyle, poor diet, and physical inactivity) worsens the metabolic component of the syndrome. [37][38][39][40][41] Apart from ovulation abnormalities and hormonal imbalances, PCOS is associated with significant metabolic abnormalities, which confer an increased cardiometabolic risk. 42 Women with PCOS have increased insulin resistance and are at risk of T2DM, obesity, and metabolic syndrome (hypertension, dyslipidemia, glucose intolerance). 43 Furthermore, patients with PCOS have evidence of vascular dysfunction, chronic inflammation, oxidative stress, and prothrombosis. Which interact to accelerate major adverse cardiovascular events (MACE), defined as a composite of cardiovascular death, non-fatal stroke, and non-fatal myocardial infarction. 22,42 Additionally, PCOS-associated kidney injury has been recorded. 44 Even though there is a lack of data regarding the rate of cardiovascular events in this population, the benefit of modulating or mitigating these cardiometabolic risk factors in the general population is well known.
Insulin resistance appears to be a prominent link between glucose abnormalities and the cardiometabolic risk of PCOS, even though the mechanisms of insulin resistance in PCOS are not well defined. 37 Studies suggest that excess androgen causes conformational changes in the insulin receptor transduction, leading to underregulation and disturbance of its sensing capabilities, and compensatory hyperinsulinemia. 45,46 Eventually, chronic insulin resistance leads to pancreatic β-cell failure and the loss of glucose homoeostasis, resulting in glucose intolerance or frank T2DM development. 47 The effects of hyperinsulinemia extend beyond glycaemic dysregulation. Studies have demonstrated that hyperinsulinemia is a promoter of androgen production by direct stimulation of theca cells. 48 Hyperandrogenemia is associated with vascular dysfunction in women with PCOS. 45 However, It is unclear if this is the effect of hyperandrogenemia or disrupted glucose metabolism on the vascular bed. 49 This might suggest a complex interplay between insulin and androgen that results in a vicious circle in PCOS. Obesity is known to exacerbate the dysregulation of glucose metabolism. 50,51 Adipose tissue modulates energy storage and is an endocrine mediator through the secretion of cytokines known as adipokines. [52][53][54][55][56] Adipokines regulate fatty acid oxidation and lipid accumulation. 52 In PCOS, lipid expansion leads to the secretion of pro-inflammatory adipocytokines, which downregulates insulin receptors, worsens hyperinsulinemia, and increases lipid accumulation. 57 Long-standing adipocytokine release leads to chronic inflammation and oxidative stress, which play a significant role in endovascular dysfunction, atherosclerosis formation, liver disease, and cardiovascular risk. 53,56,58

| PCOS-RELATED CARDIOMETABOLIC COMPLICATIONS
Women with PCOS are at a higher risk for a range of long-term comorbidities such as obesity, dyslipidemia, non-alcoholic fatty liver disease (NAFLD), hypertension, cardiovascular events, obstructive sleep apnea (OSA), and mental health disorders, such as depression and anxiety. 59 Obesity is a common feature in women with PCOS, with a prevalence as high as 80%. 60 Among women with PCOS, obesity is characterised by an android pattern of fat distribution, with increased waist-to-hip ratio (WHR) and visceral obesity, known predictors of cardiovascular health. 61,62 Women with obesity and PCOS present worse metabolic and hormonal disturbances than matched women with normal weight. 63,64 Increases in ovarian steroidogenesis deplete sex hormone binding globulin, leading to excess free androgens, promoting an android fat distribution. 60 Upper body obesity has been linked to arterial stiffness, leading to endothelial alterations, and increased metabolic risk. 65,66 Changes in body metabolism and homoeostasis may result in disturbances in lipid profile, blood pressure, and glucose intolerance, a cluster of entities known as metabolic syndrome. 67 Furthermore, research has found evidence that upper-body fat accumulation might aggravate metabolic syndrome and increase the risk of cardiovascular events. 68 Lipid metabolism is widely affected in patients with PCOS. 69 The incidence of dyslipidemia in PCOS patients appears to be twice the average population. 70 Typical lipid derangements in women with PCOS consist of lower high-density lipoprotein (HDL-C) and higher triglycerides (TG), low-density lipoprotein (LDL-C), and total cholesterol. 70,71 Insulin resistance appears to play a significant role in the development of dyslipidemia in women with PCOS, as lipoprotein ratios positively correlate to insulin levels. 72 Moreover, abdominal obesity is linked to deranged lipid metabolism and an increase in cardiovascular risk. 73 NAFLD results from ectopic fat deposition in the liver, leading to liver dysfunction from lipo-toxicity. 74 Chronic steatosis produces cytokines, immune cell recruitment, and cellular damage resulting in non-alcoholic steatohepatitis (NASH) and advanced cirrhosis, promoting atherosclerosis, and increased cardiovascular disease. 57,74 Identification and management of liver disease in patients with PCOS are crucial as they tend to present with more severe and aggressive liver disease coexisting with other metabolic abnormalities. 75,76 However, no therapeutic intervention is currently defined as an optimal to target and decrease the lipotoxic effect of fatty accumulation in the liver. 77 Hypertension is a common feature of PCOS, with an estimated prevalence of 65% in women with PCOS. 78 Patients with PCOS commonly have elevated aldosterone levels, which mediate hypertension, reflecting the activation of the renin-angiotensin system. 79 In addition, hyperaldosteronism is a well-known cardiovascular risk factor with significant implications in developing hypertension, adverse cardiac remodelling, and chronic inflammation. 79,80 Interestingly, aldosterone could even be associated with the pathogenesis of insulin resistance due to the interplay between inflammation and insulin resistance. 81

| CURRENT PREVENTIVE AND THERAPEUTIC OPTIONS
The management of PCOS should address the regulation of metabolic derangements and mitigation of cardiovascular risk in addition to the traditional focus of symptomatic control and ovulatory regulation. 82 Current management concentrates on lifestyle modifications, weight management by medication or surgical interventions, insulin sensitizers, and androgen lowering agents. 3 Due to the vast array of metabolic pathways affected by PCOS and their interconnection, it is often necessary to use multiple agents. 3,83 Lifestyle modifications are the first step to achieve weight loss in women with PCOS who live with overweight or obesity. 3 Besides improving ovulation, fertility, and symptoms of hyperandrogenism, weight loss decreases IR, improves dyslipidemia, and decreases visceral and abdominal fat. 51,84,85 However, weight loss through lifestyle modifications, such as diet and exercise routines, requires motivation to maintain and prevent weight increase. Adjuvant therapies to lifestyle modification, such as anti-obesity agents and bariatric surgery (e.g., gastric bypass, gastroplasty, gastric banding, or duodenal switch), effectively facilitate weight loss, making them useful in the management of patients with obesity. 86,87 Among the anti-obesity pharmacologic options are, most commonly, glucagonlike peptide-1 (GLP-1) agonists, which influence appetite and affect gut motility, and orlistat, which impairs dietary lipid absorption. Both agents have been shown to promote both weight loss and improvement of metabolic profiles in patients with PCOS. 88,89 The cornerstone of pharmacotherapy for PCOS is oral contraceptives (OCPs) and metformin, which affect the hormonal and metabolic profiles. 3 Even though OCPs are the most effective at regulating menstruation and decreasing androgen levels, they have significant adverse effects in several metabolic pathways. 90 Studies have shown that they are associated with a worsening of lipid profiles, an increase in abdominal fat mass and inflammatory cytokines, and a twofold increase in cardiovascular events. 91 Furthermore, OCPs carry an augmented risk of venous thromboembolism, which is LEMPESIS ET AL.
-3 of 12 already elevated in patients with PCOS. 92 Though beneficial in rectifying the hormonal imbalance characteristic of PCOS, the metabolic dysregulation associated with OCP limits their use in patients with PCOS who already suffer from metabolic derangements.
In contrast, direct treatment of the metabolic abnormalities associated with PCOS leads to menstrual recovery and improvement in fertility profile. Metformin is a biguanide drug used in PCOS for its ovulatory, insulin-sensitising, and glucose-lowering properties. 93 Metformin decreases circulating androgen levels, leading to an improved ovulatory cycle. 94 Initial studies attributed this effect to the reduction of hyperinsulinemia. 95 However, conflicting data exist on metformin as an insulin-sensitising agent. 96 The effect of metformin as an androgen-lowering therapy seems to preclude any insulin sensitivity changes, pointing to the discordance between insulin sensitivity and androgen excess. 94 In addition, evidence regarding metformin's effect on body weight is heterogeneous. 97 Studies have shown that the weight loss properties of metformin are secondary to its side effects and not to the modification of metabolic pathways. 98 Apart from those agents, the arsenal of therapeutic choices that affect the cardinal processes of PCOS is limited, while evidence for alternative treatments is lacking. There is limited data on antiandrogen medications and no consensus on the use of novel insulin-sensitising drugs to mitigate cardiovascular risk in PCOS. 3 Ongoing research is focused on novel mechanisms underlying the metabolic disturbances of PCOS. 21,99,100 Notably, in animal models, androgens appear to modulate the expression of renal glucose transporters and upregulate SGLT2, SGLT4, and GLUT2 but downregulate SGLT3. 101 Nonetheless, the effect of androgens and insulin is prominent in this disease. In this context, it is imperative to investigate the use of newly available therapies capable of modulating these pathways for PCOS management.

| CARDIOMETABOLIC EFFECTS OF SGLT2 INHIBITORS
SGLT2i, also known as gliflozins, comprise a relatively new class of medications initially approved to treat T2DM that increase urinary glucose excretion by inhibiting glucose reabsorption in the proximal tubule of the nephron. 23,102 Beyond treating T2DM, however, SGLT2i were found to exhibit significant cardiovascular and renal benefits. 103,104 Various major trials showed significant prevention of MACE, to varying degrees, in those with T2D and either established cardiovascular disease or high cardiovascular risk. [105][106][107][108] These cardiovascular benefits were demonstrated among patients with chronic kidney disease (CKD) with or without T2D, as well as among patients with or without T2D and established heart failure (HF). [109][110][111] Renal benefits, though not consistently seen across studies, include a lower rate of progression of albuminuria as well as a reduction of dialysis, transplantation, or death due to kidney disease. 106,112 Exploring the generalisability of the cardiovascular benefits of SGLT2i, two more trials enroled patients with heart failure (HF) with a reduced ejection fraction (HFrEF) and demonstrated improved cardiovascular outcomes for dapagliflozin and empagliflozin compared to placebo, regardless of T2D status. 24,113 Yet another study showed that for patients with HF and a preserved ejection fraction (HFpEF), use of empagliflozin reduced the combined risk of cardiovascular death or hospitalizations from heart failure, mainly due to a reduction of the latter, regardless of the presence of T2DM. 114 Furthermore, a recent meta-analysis showed that the numerous cardiovascular benefits of SGLT2i persist regardless of gender, age, and race or ethnicity. 115 Besides these clinical outcomes, several markers of cardiovascular risk have been shown to be positively affected by SGLT2i as well, including reductions in body weight, blood pressure, albuminuria, and glycosylated haemoglobin (HbA1c). [105][106][107]110 These significant effects provide a clue towards the mechanisms by which SGLT2i achieve their effects on cardiovascular health but are unlikely to explain the full actions of SGLT2i. 116 For example, one study that analysed mediators of the effects of canagliflozin on HFrEF in patients with T2DM showed that systolic blood pressure, HbA1c, and body weight were only minor mediators of the effects of SGLT2i. 117 Additionally, the fact that other glucose-lowering agents, including sulfonylureas, thiazolidinediones, and insulin, have not been proven to significantly reduce macrovascular complications of T2DM suggests that other underlying mechanisms of SGLT2i are yet to be elucidated. 118 A plethora of hypotheses regarding the pleiotropic effects of SGLT2i and their role in cardiovascular disease have been proposed, including crucial modulators of atherosclerosis development. 119 This involves a complex interplay between lipid metabolism, inflammation, and endothelial dysfunction. 120 Some researchers suggest that SGLT2i precipitate a fasting state via glucosuria, thereby increasing ketoacids, [121][122][123] which have anti-inflammatory properties 124 and are more energy-efficient. 125,126 Additionally, SGLT2i has been shown to reduce insulin resistance, which is partially linked to a proinflammatory status. 127 Apart from modulating the pathophysiology of atherosclerotic disease, others argue that natriuresis and consequently the reduced plasma volume caused by SGLT2i promote positive ventricular remodelling. 58,59 It is thought that, in contrast to loop diuretics, SGLT2i achieve this effect by not provoking a compensatory, counter-productive neurohormonal activation, effectively leading to a decrease in preload and afterload. 126,128 Others suggest that the cardiovascular benefits of SGLT2i derive from the enhanced oxygenation of the failing myocardium via erythropoiesis caused by improved renal function. 116 This explanation, in conjunction with the prevention of cardiorenal syndrome in general, may be seen as an "Occam's razor" to weave together the cardiovascular and renal benefits seen with SGLT2i. 129 Cardiac fibrosis, an important "final pathway" of HF, has also been shown to be attenuated by SGLT2i. [130][131][132] Still others have borrowed from bench research to hypothesise that the effect of SGLT2i on cardiomyocyte ion homoeostasis is the source of a reduction of ventricular arrhythmias and sudden cardiac death. 133,134 In conclusion, while the multifaceted explanations for the mechanisms of action of SGLT2i remain under investigation, their diverse clinical benefits continue to be explored and reaped, with a yearning to expand the population that may benefit from their use.
Despite the multiple benefits of SGLT2i, certain side effects might limit their widespread adoption in certain populations. In women, SGLT-2i are associated with increased mycotic infections, urinary tract infections, and polyuria. 135 Even though dapagliflozin was linked to an increased incidence of breast and bladder cancer, some attribute this finding to ascertainment bias, 136 and later studies do not lend support to this claim. 137

| EFFECTS OF SGLT2 INHIBITORS ON PCOS
There are still a limited number of studies, especially prospective randomized controlled trials (RCTs), evaluating the actual impact of SGLT2i on women with overweight or obesity and PCOS (summarised in Figure 1 and Table 1 At a clinical level, in a randomized controlled trial, Javed et al. compared metabolic parameters between women with PCOS taking metformin and empagliflozin 99 . Results showed mainly anthropometric differences. 99 Specifically, those treated with empagliflozin were more likely to have greater weight loss, lower waist circumference (WC), lower hip circumference (HC), and lower fat mass. 99 Nevertheless, no significant differences were found for any hormonal or metabolic parameters, such as blood pressure, insulin sensitivity, or fasting lipid profile. From the same group, parameters of endothelial cell activation, endothelial microparticles (EMPs), were examined. 21  -Equivalent reductions in BMI and WC with PHEN/ TPM, only -EQW/DAPA and EQW resulted in significant improvements in mean blood glucose, insulin sensitivity index, and insulin secretion.
-Reductions in fasting glucose, testosterone, free androgen index, and blood pressure were seen with all drugs.
A) exenatide (EQW) 2 mg weekly and B) dapagliflozin (DAPA) alone10 mg daily And C) co-administered (EQW/DAPA) (  Kokkinidis interpreted information and revised the manuscript. All authors approved the final version of the manuscript.
No conflicts of interest are declared by the authors.

DATA AVAILABILITY STATEMENT
Data sharing is not applicable to this article as no new data were created or analysed in this review.

ETHICS STATEMENT
This is a review and not a clinical study involving humans or animals; therefore, ethics approval was not required.