Insights from the Menstrual Cycle in Pulmonary Arterial Hypertension

Investigating the "sex paradox" in pulmonary arterial hypertension: Results from the Pulmonary Hypertension Association Registry (PHAR)

BACKGROUND

Female sex is a significant risk factor for pulmonary arterial hypertension (PAH), yet males with PAH have worse survival - a phenomenon referred to as the "sex paradox" in PAH.

METHODS

All adult PAH patients in the Pulmonary Hypertension Association Registry (PHAR) with congruent sex and gender were included. Baseline differences in demographics, hemodynamics, functional parameters, and quality of life were assessed by sex. Kaplan-Meier survival analysis was used to evaluate survival by sex. Mediation analysis was conducted with Cox proportional hazards regression by comparing the unadjusted hazard ratios for sex before and after adjustment for covariates. The plausibility of collider-stratification bias was assessed by modeling how large an unmeasured factor would have to be to generate the observed sex-based mortality differences. Subgroup analysis was performed on idiopathic and incident patients.

RESULTS

Among the 1,891 patients included, 75% were female. Compared to men, women had less favorable hemodynamics, lower 6-minute walk distance, more PAH therapies, and worse functional class; however, sex-based differences were less pronounced when accounting for body surface area or expected variability by gender. On multivariate analysis, women had a 48% lower risk of death compared to men (Hazard Ratio 0.52, 95% Confidence interval 0.36 - 0.74, p < 0.001). Modeling found that under reasonable assumptions collider-stratification could account for sex-based differences in mortality.

CONCLUSIONS

In this large registry of PAH patients new to a care center, men had worse survival than women despite having more favorable baseline characteristics. Collider-stratification bias could account for the observed greater mortality among men.

Pulmonary arterial hypertension: Sex matters

Pulmonary arterial hypertension (PAH) is a complex disease of multifactorial origin. While registries have demonstrated that women are more susceptible to the disease, females with PAH have superior right ventricle (RV) function and a better prognosis than their male counterparts, a phenomenon referred to as the 'estrogen paradox'. Numerous pre-clinical studies have investigated the involvement of sex hormones in PAH pathobiology, often with conflicting results. However, recent advances suggest that abnormal estrogen synthesis, metabolism and signalling underpin the sexual dimorphism of this disease. Other sex hormones, such as progesterone, testosterone and dehydroepiandrosterone may also play a role. Several non-hormonal factor including sex chromosomes and epigenetics have also been implicated. Though the underlying pathophysiological mechanisms are complex, several compounds that modulate sex hormones levels and signalling are under investigation in PAH patients. Further elucidation of the estrogen paradox will set the stage for the identification of additional therapeutic targets for this disease.

Prevalence and Determinants of Delay in Time-to-Diagnosis for Pulmonary Arterial Hypertension Patients in Gansu China: A Observational Cohort Study

Current studies of patients with pulmonary arterial hypertension (PAH) have shown a significant diagnostic delay. However, the causes and risk factors for this delay are not been well explored in Chinese population. This study aimed to assess the status of diagnostic delay in patients with PAH in China. Additionally, we identified factors associated with the delay. Demographic and clinical data were collected from 153 PAH patients admitted to three tertiary hospitals in Gansu, China, from March 2020 to October 2022. Based on the recorded date, the diagnostic delay was divided into patient delay and health system delay. For analysis, we divided diagnostic delay into 2 groups (≤3 years and >3 years). Factors associated with delay were identified by binary logistic regression. The median diagnostic delay was 3 years (IQR: 0.25-5.88). Binary logistic regression analysis showed that male (OR = 2.48, 95% CI: 1.10-5.58), those with junior high school or below (OR = 3.65, 95% CI: 1.36-9.78), living far away from the tertiary hospital (OR = 2.66, 95% CI: 1.14-6.18), initially visit hospital before 2018 (OR = 3.82, 95% CI: 1.68-8.71), and visit hospital at county level or below (OR = 3.80, 95% CI: 1.42-10.18) were risk factor for diagnostic delay (>3 years). Despite increased awareness, most patients with PAH in Gansu, China still experienced a delay in diagnosis of more than 3 years. Male sex, lower educational background, and being away from tertiary hospitals are risk factors for delay. Furthermore, factors impacting time-to-diagnosis and its impact should be continuously evaluated as therapeutic strategies continue to evolve and improve.

Biomechanical and Mechanobiological Drivers of the Transition From PostCapillary Pulmonary Hypertension to Combined Pre-/PostCapillary Pulmonary Hypertension

Combined pre-/postcapillary pulmonary hypertension (Cpc-PH), a complication of left heart failure, is associated with higher mortality rates than isolated postcapillary pulmonary hypertension alone. Currently, knowledge gaps persist on the mechanisms responsible for the progression of isolated postcapillary pulmonary hypertension (Ipc-PH) to Cpc-PH. Here, we review the biomechanical and mechanobiological impact of left heart failure on pulmonary circulation, including mechanotransduction of these pathological forces, which lead to altered biological signaling and detrimental remodeling, driving the progression to Cpc-PH. We focus on pathologically increased cyclic stretch and decreased wall shear stress; mechanotransduction by endothelial cells, smooth muscle cells, and pulmonary arterial fibroblasts; and signaling-stimulated remodeling of the pulmonary veins, capillaries, and arteries that propel the transition from Ipc-PH to Cpc-PH. Identifying biomechanical and mechanobiological mechanisms of Cpc-PH progression may highlight potential pharmacologic avenues to prevent right heart failure and subsequent mortality.

Sex and Gender in Lung Diseases and Sleep Disorders: A State-of-the-Art Review: Part 2

There is now ample evidence that differences in sex and gender contribute to the incidence, susceptibility, presentation, diagnosis, and clinical course of many lung diseases. Some conditions are more prevalent in women, such as pulmonary arterial hypertension and sarcoidosis. Some life stages-such as pregnancy-are unique to women and can affect the onset and course of lung disease. Clinical presentation may differ as well, such as the higher number of exacerbations experienced by women with cystic fibrosis (CF), more fatigue in women with sarcoidosis, and more difficulty in achieving smoking cessation. Outcomes such as mortality may be different as well, as indicated by the higher mortality in women with CF. In addition, response to therapy and medication safety may also differ by sex, and yet, pharmacogenomic factors are often not adequately addressed in clinical trials. Various aspects of lung/sleep biology and pathobiology are impacted by female sex and female reproductive transitions. Differential gene expression or organ development can be impacted by these biological differences. Understanding these differences is the first step in moving toward precision medicine for all patients. This article is the second part of a state-of-the-art review of specific effects of sex and gender focused on epidemiology, disease presentation, risk factors, and management of selected lung diseases. We review the more recent literature and focus on guidelines incorporating sex and gender differences in pulmonary hypertension, CF and non-CF bronchiectasis, sarcoidosis, restless legs syndrome and insomnia, and critical illness. We also provide a summary of the effects of pregnancy on lung diseases and discuss the impact of sex and gender on tobacco use and treatment of nicotine use disorder.

Baseline Sex Differences in Pulmonary Arterial Hypertension Randomized Clinical Trials

Rationale: Sex-based differences in pulmonary arterial hypertension (PAH) are known, but the contribution to disease measures is understudied. Objectives: We examined whether sex was associated with baseline 6-minute-walk distance (6MWD), hemodynamics, and functional class. Methods: We conducted a secondary analysis of participant-level data from randomized clinical trials of investigational PAH therapies conducted between 1998 and 2014 and provided by the U.S. Food and Drug Administration. Outcomes were modeled as a function of an interaction between sex and age or sex and body mass index (BMI), respectively, with generalized mixed modeling. Results: We included a total of 6,633 participants from 18 randomized clinical trials. A total of 5,197 (78%) were female, with a mean age of 49.1 years and a mean BMI of 27.0 kg/m2. Among 1,436 males, the mean age was 49.7 years, and the mean BMI was 26.4 kg/m2. The most common etiology of PAH was idiopathic. Females had shorter 6MWD. For every 1 kg/m2 increase in BMI for females, 6MWD decreased 2.3 (1.6-3.0) meters (P < 0.001), whereas 6MWD did not significantly change with BMI in males (0.31 m [-0.30 to 0.92]; P = 0.32). Females had lower right atrial pressure (RAP) and mean pulmonary artery pressure, and higher cardiac index than males (all P < 0.03). Age significantly modified the sex by RAP and mean pulmonary artery pressure relationships. For every 10-year increase in age, RAP was lower in males (0.5 mm Hg [0.3-0.7]; P < 0.001), but not in females (0.13 [-0.03 to 0.28]; P = 0.10). There was a significant decrease in pulmonary vascular resistance (PVR) with increasing age regardless of sex (P < 0.001). For every 1 kg/m2 increase in BMI, there was a 3% decrease in PVR for males (P < 0.001), compared with a 2% decrease in PVR in females (P < 0.001). Conclusions: Sexual dimorphism in subjects enrolled in clinical trials extends to 6MWD and hemodynamics; these relationships are modified by age and BMI. Sex, age, and body size should be considered in the evaluation and interpretation of surrogate outcomes in PAH.

Sex and gender in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare disease characterised by pulmonary vascular remodelling and elevated pulmonary pressure, which eventually leads to right heart failure and death. Registries worldwide have noted a female predominance of the disease, spurring particular interest in hormonal involvement in the disease pathobiology. Several experimental models have shown both protective and deleterious effects of oestrogens, suggesting that complex mechanisms participate in PAH pathogenesis. In fact, oestrogen metabolites as well as receptors and enzymes implicated in oestrogen signalling pathways and associated conditions such as BMPR2 mutation contribute to PAH penetrance more specifically in women. Conversely, females have better right ventricular function, translating to a better prognosis. Along with right ventricular adaptation, women tend to respond to PAH treatment differently from men. As some young women suffer from PAH, contraception is of particular importance, considering that pregnancy in patients with PAH is strongly discouraged due to high risk of death. When contraception measures fail, pregnant women need a multidisciplinary team-based approach. This article aims to review epidemiology, mechanisms underlying the higher female predominance, but better prognosis and the intricacies in management of women affected by PAH.

Interplay of sex hormones and long-term right ventricular adaptation in a Dutch PAH-cohort

BACKGROUND

To investigate the association between altered sex hormone expression and long-term right ventricular (RV) adaptation and progression of right heart failure in a Dutch cohort of Pulmonary Arterial Hypertension (PAH)-patients across a wide range of ages.

METHODS

In this study we included 279 PAH-patients, of which 169 females and 110 males. From 59 patients and 21 controls we collected plasma samples for sex hormone analysis. Right heart catheterization (RHC) and/or cardiac magnetic resonance (CMR) imaging was performed at baseline. For longitudinal data analysis, we selected patients that underwent a RHC and/or CMR maximally 1.5 years prior to an event (death or transplantation, N = 49).

RESULTS

Dehydroepiandrosterone-sulfate (DHEA-S) levels were reduced in male and female PAH-patients compared to controls, whereas androstenedione and testosterone were only reduced in female patients. Interestingly, low DHEA-S and high testosterone levels were correlated to worse RV function in male patients only. Subsequently, we analyzed prognosis and RV adaptation in females stratified by age. Females ≤45years had best prognosis in comparison to females ≥55years and males. No differences in RV function at baseline were observed, despite higher pressure-overload in females ≤45years. Longitudinal data demonstrated a clear distinction in RV adaptation. Although females ≤45years had an event at a later time point, RV function was more impaired at end-stage disease.

CONCLUSIONS

Sex hormones are differently associated with RV function in male and female PAH-patients. DHEA-S appeared to be lower in male and female PAH-patients. Females ≤45years could persevere pressure-overload for a longer time, but had a more severe RV phenotype at end-stage disease.

A Prospective Study of the Effects of Sex Hormones on Lung Function and Inflammation in Women with Cystic Fibrosis

Rationale: Epidemiologic studies demonstrate worse outcomes in women with cystic fibrosis (CF) than men. Women are colonized earlier with respiratory pathogens and have increased rates of pulmonary exacerbations after puberty and near ovulation. The etiology of this disparity is unclear, but sex hormones may contribute to these differences.Objectives: We sought to explore whether natural hormonal fluctuations and hormonal contraception associate with changes in lung function, respiratory symptoms, or inflammatory markers.Methods: We prospectively followed women with CF who were not on hormonal contraceptives and reported regular menstrual cycles. We captured study visits at points that corresponded with menses, ovulation, and the luteal phase. A subset of subjects were subsequently placed on a standard oral estrogen/progesterone combination contraceptive pill, ethinyl estradiol/norethindrone (loestrin), and reevaluated. Measurements included lung function, symptom questionnaires, sweat tests, blood for hormone concentrations, and sputum for inflammatory markers, bacterial density, and cytology.Results: Twenty-three women participated in this study. Hormone concentrations were as expected on and off hormonal contraception. At times of peak estrogen (ovulation), there was a significant increase in sputum proinflammatory cytokines (neutrophil-free elastase) and a corresponding pattern of decrease in lung function. Proinflammatory cytokines (IL-8, TNF-α, and neutrophil-free elastase) improved when placed on hormone contraception.Conclusions: Our results show that there are potentially important fluctuations in inflammatory biomarkers in the lungs that correlate with changes in lung function in women with CF. Larger studies evaluating the impact of sex hormones on airway inflammation and immune response are necessary to better understand the clinical impact of these responses.

Sex and Gender Differences in Lung Disease

Sex differences in the anatomy and physiology of the respiratory system have been widely reported. These intrinsic sex differences have also been shown to modulate the pathophysiology, incidence, morbidity, and mortality of several lung diseases across the life span. In this chapter, we describe the epidemiology of sex differences in respiratory diseases including neonatal lung disease (respiratory distress syndrome, bronchopulmonary dysplasia) and pediatric and adult disease (including asthma, cystic fibrosis, idiopathic pulmonary fibrosis, chronic obstructive pulmonary disease, lung cancer, lymphangioleiomyomatosis, obstructive sleep apnea, pulmonary arterial hypertension, and respiratory viral infections such as respiratory syncytial virus, influenza, and SARS-CoV-2). We also discuss the current state of research on the mechanisms underlying the observed sex differences in lung disease susceptibility and severity and the importance of considering both sex and gender variables in research studies' design and analysis.

Experimental design of the Effects of Dehydroepiandrosterone in Pulmonary Hypertension (EDIPHY) trial

Pulmonary arterial hypertension (PAH) remains life-limiting despite numerous approved vasodilator therapies. Right ventricular (RV) function determines outcome in PAH but no treatments directly target RV adaptation. PAH is more common in women, yet women have better RV function and survival as compared to men with PAH. Lower levels of the adrenal steroid dehydroepiandrosterone (DHEA) and its sulfate ester are associated with more severe pulmonary vascular disease, worse RV function, and mortality independent of other sex hormones in men and women with PAH. DHEA has direct effects on nitric oxide (NO) and endothelin-1 (ET-1) synthesis and signaling, direct antihypertrophic effects on cardiomyocytes, and mitigates oxidative stress. Effects of Dehydroepiandrosterone in Pulmonary Hypertension (EDIPHY) is an on-going randomized double-blind placebo-controlled crossover trial of DHEA in men (n = 13) and pre- and post-menopausal women (n = 13) with Group 1 PAH funded by the National Heart, Lung and Blood Institute. We will determine whether orally administered DHEA 50 mg daily for 18 weeks affects RV longitudinal strain measured by cardiac magnetic resonance imaging, markers of RV remodeling and oxidative stress, NO and ET-1 signaling, sex hormone levels, other PAH intermediate end points, side effects, and safety. The crossover design will elucidate sex-based phenotypes in PAH and whether active treatment with DHEA impacts NO and ET-1 biosynthesis. EDIPHY is the first clinical trial of an endogenous sex hormone in PAH. Herein we present the study’s rationale and experimental design.