Role of Mineralocorticoid Receptors in Obstructive Sleep Apnea and Metabolic Syndrome

Obesity, aldosterone excess, and mineralocorticoid receptor activation: Parallel or intersected circumstances?

The obesity pandemic, with its associated comorbidities of hypertension and diabetes, constitutes a global public health issue. Importantly, there is an increasing prevalence of aldosterone excess related to obesity and resultant poor health outcomes. Nevertheless, the association between aldosterone and obesity still needs to be clarified. In this review, the authors discuss the role of white adipose tissue in linking obesity, aldosterone excess, and hypertension. The consequences of aldosterone excess in obesity are presented as genomic, non-genomic, and non-epithelial effects. Moreover, the authors emphasize the value of interference with aldosterone pathophysiology (as with mineralocorticoid antagonists) in obesity, thus reducing the adverse clinical impact of aldosterone in myocardial infarction, heart failure, kidney dysfunction, and associated mortality.

The Prevalence of Obstructive Sleep Apnea in Patients With Primary Aldosteronism

CONTEXT

Investigating the co-occurrence of obstructive sleep apnea (OSA) and primary aldosteronism (PA) is crucial for understanding their interrelation.

OBJECTIVE

This work aimed to evaluate the prevalence of OSA in individuals diagnosed with PA and to assess the prevalence of PA within the OSA population, with a specific focus on hypertensive individuals.

METHODS

An exhaustive search was performed across PubMed, Embase, CINAHL, Scopus, and Web of Science up to September 2023, without restrictions on language or publication date. Studies were selected based on their focus on the prevalence of OSA in PA patients and vice versa, specifically in hypertensive individuals. Data were extracted using standard guidelines, focusing on patient characteristics, prevalence rates, and other relevant clinical parameters.

RESULTS

Proportional meta-analysis using a random-effects model revealed a 59.8% prevalence of OSA in hypertensive PA patients, with 45.4% exhibiting moderate-to-severe OSA. Meta-regression showed no significant effect of age, sex, body mass index, antihypertensive medication, systolic blood pressure, diastolic blood pressure, or serum potassium on OSA prevalence. However, a significant positive association was found with the glomerular filtration rate (GFR) (P < .001). Subgroup analysis also revealed that a hyperfiltration rate (GFR ≥ 100 mL/min per 1.73 m2) may be associated with a higher prevalence of OSA (71%, P value for interaction < .01). Among hypertensive OSA patients, 11.2% had PA.

CONCLUSION

A substantial prevalence of OSA in individuals with PA was identified, demonstrating a complex interplay between these conditions in hypertensive patients. Notably, the prevalence of OSA was significantly associated with kidney hyperfiltration.

Does obstructive sleep apnea-induced intermittent hypoxia increase the incidence of solitary pulmonary nodules, thyroid nodules, and other disorders? A retrospective study based on 750 cardiovascular disease patients

BACKGROUND

Obstructive sleep apnea (OSA) has been shown to be an important risk factor for cardiovascular disease (CVD), and intermittent hypoxia is an important pathogenetic factor for it. In the clinic, it was found that most CVD patients combined with OSA were also combined with solitary pulmonary nodules (SPN) or thyroid nodules (TN). Are these disorders related to intermittent hypoxia? One study showed that intermittent hypoxia is a pathogenic factor for lung cancer in mice, but there have been no clinical reports. So we conducted a retrospective study to explore whether intermittent hypoxia caused by OSA increases the incidence of SPN, TN, and other disorders.

METHODS

We selected 750 patients with cardiovascular disease (CVD), who were divided into the control group and the OSA group according to the result of portable sleep monitoring. Retrospectively analyzed the comorbidities that patients with OSA are prone to and explored the correlation between OSA and those comorbidities.

RESULTS

The incidence of SPN, TN, cervical spondylosis, and carotid-artery plaques was higher in the OSA group than in the control group. These diseases are significantly associated with OSA (p < 0.05), and their incidence increased with an elevated apnea-hypopnea index. After excluding interference from age, gender, BMI, smoking history, history of lung disease, and history of tumors, OSA showed a significant correlation with SPN. After excluding age, gender, BMI, and thyroid disease, OSA was associated with TN. Patients with comorbidities have lower nocturnal oxygen saturation and more extended periods of apnea. Logistic multiple regression results revealed that male, advanced age, obesity, CS, and nasal septum deviation were independent risk factors for OSA.

CONCLUSIONS

Patients combined with OSA may further develop more comorbidities, such as SPN, TN, and carotid-artery plaques. It may be related to intermittent hypoxia caused by OSA.

Primary aldosteronism and obstructive sleep apnea: What do we know thus far?

Both primary aldosteronism and obstructive sleep apnea are well-known causes of hypertension and contribute to increased cardiovascular morbidity and mortality independently. However, the relationship between these two entities remains unclear, with studies demonstrating contradictory results. This review aims to collate and put into perspective current available research regarding the association between primary aldosteronism and obstructive sleep apnea. The relationship between these two entities, clinical characteristics, clinical implications, outcomes of treatment, potential causal links and mechanisms are hereby presented.

A review of the "OMICS" for management of patients with obstructive sleep apnoea

Obstructive sleep apnaea (OSA) syndrome is a condition characterised by the presence of complete or partial collapse of the upper airways during sleep, resulting in fragmentation of sleep associated with rapid episodes of intermittent hypoxia (IH), activation of the sympathetic nervous system and oxidative stress. OSA is associated with a broad spectrum of cardiovascular, metabolic and neurocognitive comorbidities that appear to be particularly evident in obese patients, while affecting both sexes in a different manner and varying in severity according to gender and age. In recent years, studies on OSA have increased considerably, but in clinical practice, it is still a highly underdiagnosed disease. To date, the gold standard for the diagnosis of OSA is nocturnal polysomnography (PSG). However, since it is not well suited for a large number of patients, the Home Sleep Test (HST) is also an accepted diagnostic method. Currently, the major aim of research is to identify non-invasive methods to achieve a highly predictive, non-invasive screening system for these subjects. The most recent reports indicate that research in this field has made significant progress in identifying possible biomarkers in OSA, using -OMIC approaches, particularly in the fields of proteomics and metabolomics. In this review, we analyse these OMIC biomarkers found in the literature.

Molecular determinants of obstructive sleep apnea

Obstructive sleep apnea (OSA) is characterized as recurrent episodes of obstruction in the upper airway during the period of sleep. The condition occurs in approximately 11% and 4% of middle-aged men and middle-aged women, respectively. Polysomnography is a diagnostic procedure that involves the constant observation of oxygen saturation and unsaturation during sleep. Usually, positive airway pressure is considered a benchmark treatment for OSA. This review summarizes the recent developments and emerging evidence from molecular biology-based research studies that show that genetic factors have an influence on OSA. The genetic aspects of OSA that have been identified include heritability and other phenotypic co-factors such as anatomical morphology. It also draws attention to the results of a polymorphic-based study that was conducted to determine the causative single nucleotide mutations associated with obesity and adverse cardiovascular risk in OSA. However, the role of such mutations and their linkage to OSA can not yet be established. Nonetheless, a large body of evidence supports a strong association between inflammatory cytokine polymorphism and obesity in the development of OSA. There are also probable intermediate factors with several gene-gene interactions. Therefore, advanced applications and modern techniques should be applied to facilitate new findings and to minimize the risk of developing OSA.

The Impact of Empagliflozin on Obstructive Sleep Apnea and Cardiovascular and Renal Outcomes: An Exploratory Analysis of the EMPA-REG OUTCOME Trial

OBJECTIVE

To explore the effects of empagliflozin on the incidence of obstructive sleep apnea (OSA) and its effects on metabolic, cardiovascular (CV), and renal outcomes among participants with or without OSA in the EMPA-REG OUTCOME trial.

RESEARCH DESIGN AND METHODS

Participants with diabetes and CV disease were randomized to empagliflozin (10 and 25 mg) or placebo daily in addition to standard of care. OSA was assessed by investigator report using Medical Dictionary for Regulatory Activities version 18.0, and CV outcomes were independently adjudicated. Analyses were performed using multivariable-adjusted Cox regression models.

RESULTS

OSA was reported in 391 of 7,020 (5.6%) participants at baseline. Those with OSA were more likely to be male (83% vs. 71%) and to have moderate to severe obesity (BMI ≥35 kg/m2; 55% vs. 18%). Over a median of 3.1 years, empagliflozin had similar placebo-adjusted reductions in HbA1c, waist circumference, and systolic blood pressure, regardless of OSA status, but a larger effect on weight (adjusted mean ± SE difference at week 52: OSA vs. no OSA -2.9 ± 0.5 vs. -1.9 ± 0.1 kg). Incidence of 3-point major adverse CV events, CV death, heart failure hospitalization, and incident or worsening nephropathy in the placebo group was 1.2- to 2.0-fold higher for those with baseline OSA compared with those without. Empagliflozin significantly reduced the risk for outcomes regardless of OSA status (P-interaction all >0.05). Fifty patients reported a new diagnosis of OSA through 7 days after medication discontinuation, and this occurred less often with empagliflozin treatment (hazard ratio 0.48 [95% CI 0.27, 0.83]).

CONCLUSIONS

In EMPA-REG OUTCOME, participants with OSA had greater comorbidity and higher frequency of CV and renal events. Empagliflozin had favorable effects on risk factors and CV and renal outcomes regardless of preexisting OSA and may also reduce the risk for new-onset OSA.

The Aldosterone/Renin Ratio Predicts Cardiometabolic Disorders in Subjects Without Classic Primary Aldosteronism

BACKGROUND

Aldosterone has been linked with obesity, metabolic syndrome (MetS), pro-inflammatory, and prothrombotic states; however, most studies relate these indicators with primary aldosteronism (PA), excluding non-PA patients.

OBJECTIVE

To determine whether aldosterone, renin, or the plasma aldosterone/renin ratio (ARR) are associated with metabolic disorders and inflammatory/vascular biomarkers in a non-PA population.

METHODS

We studied 275 patients including adolescents and adults of both genders and measured plasma and urinary aldosterone and determined the plasma renin activity. In all subjects, the presence of MetS was determined according to Adult Treatment Panel III. Renal, vascular, inflammatory, and mineralocorticoid activity biomarkers were evaluated.

RESULTS

The ARR correlated with the number of variables of MetS (r = 0.191, P = 0.002), body mass index (BMI; r = 0.136, P = 0.026), systolic blood pressure (r = 0.183, P = 0.002), diastolic blood pressure (r = 0.1917, P = 0.0014), potassium excreted fraction (r = 0.174, P = 0.004), low-density lipoprotein (r = 0.156, P = 0.01), plasminogen activator inhibitor type 1 (r = 0.158, P = 0.009), microalbuminuria (r = 0.136, P = 0.029), and leptin (r = 0.142, P = 0.019). In a linear regression model adjusted by age, BMI, and gender, only the ARR was still significant (r = 0.108, P = 0.05). In a logistic regression analysis, the ARR predicted MetS index (odds ratio (OR) = 1.07 [95% confidence interval (CI) = 1.011-1.131], P= 0.02) even after adjusting for age, BMI, and gender. On the other hand, aldosterone showed no association with MetS or inflammatory markers.

CONCLUSION

These results suggest a continuum of cardiometabolic risk beyond the classic PA threshold screening. The ARR could be a more sensitive marker of obesity, MetS, and endothelial damage in non-PA patients than aldosterone or renin alone. Prospective studies are needed to develop future screening cutoff values.

Vascular Mineralocorticoid Receptor: Evolutionary Mediator of Wound Healing Turned Harmful by Our Modern Lifestyle

The mineralocorticoid receptor (MR) is indispensable for survival through its critical role in maintaining blood pressure in response to sodium scarcity or bleeding. Activation of MR by aldosterone in the kidney controls water and electrolyte homeostasis. This review summarizes recent advances in our understanding of MR function, specifically in vascular endothelial and smooth muscle cells. The evolving roles for vascular MR are summarized in the areas of (i) vascular tone regulation, (ii) thrombosis, (iii) inflammation, and (iv) vascular remodeling/fibrosis. Synthesis of the data supports the concept that vascular MR does not contribute substantially to basal homeostasis but rather, MR is poised to be activated when the vasculature is damaged to coordinate blood pressure maintenance and wound healing. Specifically, MR activation in the vascular wall promotes vasoconstriction, inflammation, and exuberant vascular remodeling with fibrosis. A teleological model is proposed in which these functions of vascular MR may have provided a critical evolutionary survival advantage in the face of mechanical vascular injury with bleeding. However, modern lifestyle is characterized by physical inactivity and high fat/high sodium diet resulting in diffuse vascular damage. Under these modern conditions, diffuse, persistent and unregulated activation of vascular MR contributes to post-reproductive cardiovascular disease in growing populations with hypertension, obesity, and advanced age.

The Expanding Spectrum of Primary Aldosteronism: Implications for Diagnosis, Pathogenesis, and Treatment

Primary aldosteronism is characterized by aldosterone secretion that is independent of renin and angiotensin II and sodium status. The deleterious effects of primary aldosteronism are mediated by excessive activation of the mineralocorticoid receptor that results in the well-known consequences of volume expansion, hypertension, hypokalemia, and metabolic alkalosis, but it also increases the risk for cardiovascular and kidney disease, as well as death. For decades, the approaches to defining, diagnosing, and treating primary aldosteronism have been relatively constant and generally focused on detecting and treating the more severe presentations of the disease. However, emerging evidence suggests that the prevalence of primary aldosteronism is much greater than previously recognized, and that milder and nonclassical forms of renin-independent aldosterone secretion that impart heightened cardiovascular risk may be common. Public health efforts to prevent aldosterone-mediated end-organ disease will require improved capabilities to diagnose all forms of primary aldosteronism while optimizing the treatment approaches such that the excess risk for cardiovascular and kidney disease is adequately mitigated. In this review, we present a physiologic approach to considering the diagnosis, pathogenesis, and treatment of primary aldosteronism. We review evidence suggesting that primary aldosteronism manifests across a wide spectrum of severity, ranging from mild to overt, that correlates with cardiovascular risk. Furthermore, we review emerging evidence from genetic studies that begin to provide a theoretical explanation for the pathogenesis of primary aldosteronism and a link to its phenotypic severity spectrum and prevalence. Finally, we review human studies that provide insights into the optimal approach toward the treatment of primary aldosteronism.

Predicting the risk of apparent treatment-resistant hypertension: a longitudinal, cohort study in an urban hypertension referral clinic

Apparent treatment-resistant hypertension (aTRH) is associated with higher prevalence of secondary hypertension, greater risk for adverse pressure-related clinical outcomes, and influences diagnostic and therapeutic decision-making. We previously showed that cross-sectional prevalence estimates of aTRH are lower than its true prevalence as patients with uncontrolled hypertension undergoing intensification/optimization of therapy will, over time, increasingly satisfy diagnostic criteria for aTRH. aTRH was assessed in an urban referral hypertension clinic using a 140/90 mm Hg goal blood pressure target in 745 patients with uncontrolled blood pressure, who were predominately African-American (86%) and female (65%). Analyses were stratified according to existing prescription of diuretic at initial visit. Risk for aTRH was estimated using logistic regression with patient characteristics at index visit as predictors. Among those prescribed diuretics, 84/363 developed aTRH; the risk score discriminated well (area under the receiver operating curve = 0.77, bootstrapped 95% CI [0.71, 0.81]). In patients not prescribed a diuretic, 44/382 developed aTRH, and the risk score showed a significantly better discriminative ability (area under the receiver operating curve = 0.82 [0.76, 0.87]; P < .001). In the diuretic and nondiuretic cohorts, 145/363 and 290/382 of patients had estimated risks for development of aTRH <15%. Of these low-risk patients, 139/145 and 278/290 did not develop aTRH (negative predictive value, diuretics - 0.94 [0.91, 0.98], no diuretics - 0.95 [0.93, 0.97]). We created a novel clinical score that discriminates well between those who will and will not develop aTRH, especially among those without existing diuretic prescriptions. Irrespective of baseline diuretic treatment status, a low-risk score had very high negative predictive value.