Influence and implications of the renin-angiotensin-aldosterone system in obstructive sleep apnea: An updated systematic review and meta-analysis

Hypertension in obstructive sleep apnea: the hidden role of renin-angiotensin-aldosterone system dysregulation

BACKGROUND

Hypertension commonly co-exists with obstructive sleep apnea (OSA). However, the role of renin-angiotensin-aldosterone system (RAAS) in the development of hypertension in OSA patients remains poorly defined, with inconclusive evidence regarding the activation of the RAAS in these patients. Herein, we aimed to evaluate the RAAS profile in OSA patients and to elucidate the influence of RAAS on hypertension in these individuals.

METHODS

In this observational study, patients referred from health clinics aged 18 years and older, with obesity, defined as body mass index greater than 27.5 kg/m2, and confirmed OSA were recruited if they met study criteria. Anthropometric data were collected, and blood sampled for plasma aldosterone concentration (PAC) and plasma renin concentration (PRC). Treatment intensity was assessed using the therapeutic intensity score (TIS). The RAAS components were compared between the OSA patients, healthy controls, and patients with confirmed primary aldosteronism.

RESULTS

A total of 204 patients who fulfilled the study criteria were recruited, of which 160 had hypertension. Patients with hypertensive OSA demonstrated higher PAC with no significant difference in PRC compared to normotensive OSA; and higher PAC and ARR with lower PRC compared to healthy controls. PAC was positively correlated with TIS (β = 0.281, p < 0.001), systolic blood pressure (β = 0.156, p = 0.049), and hypertension duration (β = 0.168, p = 0.011), while negatively correlated with hypertension diagnosis (β = - 0.170, p = 0.024).

CONCLUSIONS

This is the first study from Southeast Asia evaluating the impact of RAAS on hypertension severity in OSA patients. Findings suggest that hypertensive individuals with OSA exhibit greater RAAS dysregulation, highlighting the role of aldosterone in the development of hypertension and its severity in OSA. This also underscores the need for targeted management strategies particularly in tropical regions with a rising prevalence of metabolic disorders.

Sleep stage, sleep fragmentation and heart rate variability during the initial 3-h sleep period in patients with obstructive sleep apnea syndrome

To investigate differences in polysomnography (PSG) parameters and heart rate variability (HRV) during the initial 3-h sleep period in patients with mild, moderate, and severe obstructive sleep apnea syndrome (OSA). According to the apnea-hypopnea index, patients were divided into 3 groups: mild, moderate, and severe (n = 23, 59, and 94, respectively). PSG was performed, and HRV (frequency domain analysis), sleep stage (S1, S2, S3, REM, and waking), and sleep fragmentation index (SFI) were measured during the initial 3-h sleep periods. The total S1 time was significantly longer in the severe group than in the mild and moderate groups (p < 0.001). The severe group had significantly shorter total S2 and S3 times than the mild (p = 0.014, p < 0.001) and moderate (p = 0.034, p = 0.029) groups did. The SFI was significantly greater in the severe group than in the mild and moderate groups (p < 0.001, p = 0.008). The high-frequency component (HF) of the HRV showed no significant differences except that it was significantly smaller during S3 in the moderate group than in the mild group (p = 0.026). Compared with those with mild/moderate status, patients with severe OSA have shallower sleep and a higher SFI, suggesting poorer sleep quality. Although HF during S3 was significantly smaller in the moderate group, it did not significantly differ between the mild and severe groups, suggesting that the parasympathetic nervous system might compensate for humoral and hypoxemic abnormalities in patients with severe OSA.

A possible important regulatory role of estrogen in obstructive sleep apnea hypoventilation syndrome

Obstructive sleep apnea-hypoventilation syndrome (OSAHS) is a prevalent clinical sleep breathing disorder that affects both pediatric and adult populations. If left untreated, OSAHS can induce or aggravate systemic dysfunction across multiple organ systems, with a particularly pronounced impact on cardiovascular health, thereby posing a substantial threat to overall human well-being. Notably, there exists a significant sex disparity in the prevalence and severity of OSAHS, with a higher incidence and greater severity observed in males. However, this disparity tends to diminish post-menopause. Research indicates that sex differences in OSAHS are associated with gonadal function, wherein estrogen exerts a protective effect by modulating pharyngeal muscle tone and mitigating oxidative stress. This regulatory role of estrogen partially reduces the incidence of OSAHS and attenuates its pathological impact. Conversely, OSAHS may adversely affect gonadal function, resulting in decreased estrogen levels, which can exacerbate the condition. This review examines the beneficial role of estrogen in the progression of OSAHS and explores the potential impact of OSAHS on estrogen levels.

The Kidney in Obesity: Current Evidence, Perspectives and Controversies

PURPOSE OF REVIEW

As obesity and chronic kidney disease (CKD) remain a public health issue, we aim to elaborate on their complex relationship regarding pathogenetic mechanisms and therapeutic potential as well. The purpose of this review is to enhance our understanding of the interplay between obesity and CKD in order to timely diagnose and treat obesity-related CKD.

RECENT FINDINGS

Obesity and CKD pose significant intertwined challenges to global health, affecting a substantial portion of the population worldwide. Obesity is recognized as an independent risk factor, intricately contributing to CKD pathogenesis through mechanisms such as lipotoxicity, chronic inflammation, and insulin resistance. Recent evidence highlights additional factors including hemodynamic changes and intestinal dysbiosis that exacerbate kidney dysfunction in obese individuals, leading to histologic alterations known as obesity-related glomerulopathy (ORG). This narrative review synthesizes current knowledge on the prevalence, pathophysiology, clinical manifestations, and diagnostic strategies of obesity-related kidney disease. Furthermore, it explores mechanistic insights to delineate current therapeutic approaches, future directions for managing this condition and controversies. By elucidating the multifaceted interactions between obesity and kidney health, this review aims to inform clinical practice and stimulate further research to address this global health epidemic effectively.

Up-to-date advance in the relationship between obstructive sleep apnea and heart failure: a narrative review

PURPOSE

Obstructive sleep apnea (OSA) is recognized as an independent and significant risk factor for various cardiovascular and cerebrovascular conditions, including heart failure (HF). In this review, we explore the impact of OSA on HF, examine shared contributing factors and underlying pathophysiological mechanisms, and assess the treatment options for OSA and their potential therapeutic value in HF patients.

METHODS

Pubmed/MEDLINE were searched through September 2024 to explore the relationship between OSA and HF. The relevant papers included OSA and HF, risk factors of OSA and HF, and the prognosis and treatment of HF patients with OSA.

RESULTS

The results showed that OSA increased the risk of HF. OSA can exacerbate or contribute to the onset of HF in several ways. The application of continuous positive airway pressure (CPAP) and other treatments may benefit HF patients with OSA. Drug therapy has shown promise for treating OSA, extensive multi-center studies remain essential, particularly in patients with both OSA and HF.

CONCLUSION

OSA can exacerbate or contribute to the onset and recurrence of HF in several ways. Further studies should be carried out to explore effective treatments in patients with HF and OSA.

Updates on the Renin-Angiotensin-Aldosterone System and the Cardiovascular Continuum

The cardiovascular continuum describes how several cardiovascular risk factors contribute to the development of atherothrombosis, ischemic heart disease, and peripheral arteriopathy, leading to cardiac and renal failure and ultimately death. Due to its multiple valences, the renin-angiotensin-aldosterone system plays an important role in all stages of the cardiovascular continuum, starting from a cluster of cardiovascular risk factors, and continuing with the development of atherosclerosis thorough various mechanisms, and culminating with heart failure. Therefore, this article aims to analyze how certain components of the renin-angiotensin-aldosterone system (converting enzymes, angiotensin, angiotensin receptors, and aldosterone) are involved in the underlying pathophysiology of the cardiovascular continuum and the possible arrest of its progression.

Beyond blood pressure, fluid and electrolyte homeostasis - Role of the renin angiotensin aldosterone system in the interplay between metabolic diseases and breast cancer

The classical renin angiotensin aldosterone system (RAAS), as well as the recently described counter-regulatory or non-canonical RAAS have been well characterized for their role in cardiovascular homeostasis. Moreover, extensive research has been conducted over the past decades on both paracrine and the endocrine roles of local RAAS in various metabolic regulations and in chronic diseases. Clinical evidence from patients on RAAS blockers as well as pre-clinical studies using rodent models of genetic manipulations of RAAS genes documented that this system may play important roles in the interplay between metabolic diseases and cancer, namely breast cancer. Some of these studies suggest potential therapeutic applications and repurposing of RAAS inhibitors for these diseases. In this review, we discuss the mechanisms by which RAAS is involved in the pathogenesis of metabolic diseases such as obesity and type-2 diabetes as well as the role of this system in the initiation, expansion and/or progression of breast cancer, especially in the context of metabolic diseases.

Sleep-related breathing disorder in a Japanese occupational population and its association with hypertension-stratified analysis by obesity status

Sleep-related breathing disorder (SRBD) causes hypertension, and obesity has been highly associated with SRBD, which has become a serious health problem in young and middle-aged Japanese males. However, the relation between SRBD and hypertension considering the effects of obesity remains unknown. In this cross-sectional study, we examined the relationship between SRBD and hypertension, with consideration for the effects of obesity, in Japanese occupational population. Using 3% oxygen desaturation index (3%ODI) obtained by simplified polysomnography (PSG), participants were classified into low (0 ≤ 3%ODI < 5), medium (5 ≤ 3%ODI < 15), and high (15 ≤ 3%ODI) 3%ODI groups. We excluded employees who had not undergone medical examination with simplified PSG in the same year from 2012 to 2018. Logistic regression analysis was performed to calculate odds ratios for having hypertension according to 3%ODI levels. In total, 2532 employees were included. Among them, 25% and 4% were categorized into the medium and high 3%ODI groups, respectively. The odds ratio for hypertension increased significantly with higher 3%ODI levels after adjustment for age, sex, alcohol drinking status and smoking status (p for trend < 0.0001). However, further adjustment for obesity status (body mass index ≥ 25 kg/m2) attenuated the associations. When we performed the stratified analysis by obesity status, the odds ratio for hypertension increased significantly with higher 3%ODI only for non-obese individuals, with significant interaction (p for interaction = 0.014). Higher 3%ODI was significantly associated with higher prevalence of hypertension especially in non-obese participants, suggesting the importance of vigilance for the presence of SRBD even in non-obese individuals. We investigated the association between SRBD and hypertension considering the effects of obesity, which would suggest the need to keep in mind the presence of SRBD even in non-obese individuals.

Female obesity: clinical and psychological assessment toward the best treatment

Obesity is a heterogeneous condition which results from complex interactions among sex/gender, sociocultural, environmental, and biological factors. Obesity is more prevalent in women in most developed countries, and several clinical and psychological obesity complications show sex-specific patterns. Females differ regarding fat distribution, with males tending to store more visceral fat, which is highly correlated to increased cardiovascular risk. Although women are more likely to be diagnosed with obesity and appear more motivated to lose weight, as confirmed by their greater representation in clinical trials, males show better outcomes in terms of body weight and intra-abdominal fat loss and improvements in the metabolic risk profile. However, only a few relatively recent studies have investigated gender differences in obesity, and sex/gender is rarely considered in the assessment and management of the disease. This review summarizes the evidence of gender differences in obesity prevalence, contributing factors, clinical complications, and psychological challenges. In addition, we explored gender differences in response to obesity treatments in the specific context of new anti-obesity drugs.

Sleep deprivation reduces the baroreflex sensitivity through elevated angiotensin (Ang) II subtype 1 receptor expression in the nucleus tractus solitarii

Introduction

Sleep insufficiency has been linked to an increased risk of high blood pressure and cardiovascular diseases. Emerging studies have demonstrated that impaired baroreflex sensitivity (BRS) is involved in the adverse cardiovascular effects caused by sleep deprivation, however, the underlying mechanisms remain unknown. Therefore, the present study aims to clarify the role of abnormal renin-angiotensin system in the nucleus tractus solitarii (NTS) in impaired BRS induced by sleep deprivation.

Methods

Rats were randomly divided into two groups: normal sleep (Ctrl) and chronic sleep deprivation (CSD) group. Rats were sleep deprived by an automated sleep deprivation system. The blood pressure, heart rate, BRS, the number of c-Fos positive cells and the expression of angiotensin (Ang) II subtype 1 receptors (AT1R) in the NTS of rats were assessed.

Results

Compared to Ctrl group, CSD group exhibited a higher blood pressure, heart rate, and reduced BRS. Moreover, the number of c-Fos positive cells and local field potential in the NTS in CSD group were increased compared with the Ctrl group. It was shown that the expression of the AT1R and the content of Ang II and the ratio of Ang II to Ang-(1-7) were increased in the NTS of rats in CSD group compared to Ctrl group. In addition, microinjection of losartan into the NTS significantly improved the impaired BRS caused by sleep deprivation.

Discussion

In conclusion, these data suggest that the elevated AT1R expression in the NTS mediates the reduced BRS induced by chronic sleep deprivation.

Obstructive sleep apnea and vitamin D level: Has the dust settled?

Obstructive sleep apnea and vitamin D deficiency are associated with multiple complications with increased morbidity and mortality. However, the relationship between these two entities remains unclear, with clinical studies demonstrating contradictory results. This narrative review aims to present the current evidence and understanding of this relationship and discuss the possible mechanisms linking these two disease entities. Finally, we summarize and propose areas of opportunity for future research.

Approach the Patient With Obstructive Sleep Apnea and Obesity

Obstructive sleep apnea (OSA) and obesity are highly prevalent and bidirectionally associated. OSA is underrecognized, however, particularly in women. By mechanisms that overlap with those of obesity, OSA increases the risk of developing, or having poor outcomes from, comorbid chronic disorders and impairs quality of life. Using 2 illustrative cases, we discuss the relationships between OSA and obesity with type 2 diabetes, dyslipidemia, cardiovascular disease, cognitive disturbance, mood disorders, lower urinary tract symptoms, sexual function, and reproductive disorders. The differences in OSA between men and women, the phenotypic variability of OSA, and comorbid sleep disorders are highlighted. When the probability of OSA is high due to consistent symptoms, comorbidities, or both, a diagnostic sleep study is advisable. Continuous positive airway pressure or mandibular advancement splints improve symptoms. Benefits for comorbidities are variable depending on nightly duration of use. By contrast, weight loss and optimization of lifestyle behaviors are consistently beneficial.

Sleep and cardiovascular disease

This review centres around the recent evidence in examining the intersection of sleep and cardiovascular disease (CVD). Sleep in this review will be further subdivided to consider both sleep quantity and quality along and will also consider some of the more common sleep disorders, such as insomnia and obstructive sleep apnoea, in the context of CVD. Sleep disorders have been further explored in several specific populations which are both at risk of sleep disorders and CVD. Secondly, the review will present some of the risk factors for CVD that are affected by sleep and sleep disorders which include hypertension, diabetes, and obesity. It will also examine the potential underlying mechanisms including inflammation, appetite control, endocrine, and genetic processes that are affected by sleep and sleep disorders leading to increased risk of CVD development. In addition, we will consider the observed bi-directional relationships between sleep and cardiovascular risk factors. For example, obesity, a risk factor for CVD can be affected by sleep, but in turn can increase the risk of certain sleep disorder development which disrupts sleep, leading to further risk of obesity development and increased CVD risk. Finally, the review will explore emerging evidence around lifestyle interventions that have included a sleep component and how it impacts the management of CVD risk factor. The need for increased awareness of the health effects of poor sleep and sleep disorders will be discussed alongside the need for policy intervention to improve sleep to facilitate better health and well-being.

Kidney Renin Release under Hypoxia and Its Potential Link with Nitric Oxide: A Narrative Review

The renin-angiotensin system (RAS) and hypoxia have a complex interaction: RAS is activated under hypoxia and activated RAS aggravates hypoxia in reverse. Renin is an aspartyl protease that catalyzes the first step of RAS and tightly regulates RAS activation. Here, we outline kidney renin expression and release under hypoxia and discuss the putative mechanisms involved. It is important that renin generally increases in response to acute hypoxemic hypoxia and intermittent hypoxemic hypoxia, but not under chronic hypoxemic hypoxia. The increase in renin activity can also be observed in anemic hypoxia and carbon monoxide-induced histotoxic hypoxia. The increased renin is contributed to by juxtaglomerular cells and the recruitment of renin lineage cells. Potential mechanisms regulating hypoxic renin expression involve hypoxia-inducible factor signaling, natriuretic peptides, nitric oxide, and Notch signaling-induced renin transcription.

Blood pressure control in hypertensive sleep apnoea patients of the European Sleep Apnea Database cohort - effects of positive airway pressure and antihypertensive medication

Aims

We analysed longitudinal blood pressure (BP) data from hypertensive obstructive sleep apnoea (OSA) patients in the European Sleep Apnea Database cohort. The study investigated the interaction between positive airway pressure (PAP)-induced BP change and antihypertensive treatment (AHT).

Methods and results

Hypertensive patients with AHT [monotherapy/dual therapy n = 1283/652, mean age 59.6 ± 10.7/60.6 ± 10.3 years, body mass index (BMI) 34.2 ± 6.5/34.8 ± 7.0 kg/m2, apnoea-hypopnoea index 46 ± 25/46 ± 24 n/h, proportion female 29/26%, respectively] started PAP treatment. Office BP at baseline and 2- to 36-month follow-up were assessed. The interaction between AHT drug classes and PAP on BP was quantified and the influences of age, gender, BMI, co-morbidities, BP at baseline, and study site were evaluated. Following PAP treatment (daily usage, 5.6 ± 1.6/5.7 ± 1.9 h/day), systolic BP was reduced by -3.9 ± 15.5/-2.8 ± 17.7 mmHg in mono/dual AHT and diastolic BP by -3.0 ± 9.8/-2.7 ± 10.8 mmHg, respectively, all P < 0.0001. Systolic and diastolic BP control was improved following PAP treatment (38/35% to 54/46% and 67/67% to 79/74%, mono/dual AHT, respectively). PAP treatment duration predicted a larger BP improvement in the monotherapy group. Intake of renin-angiotensin blockers [angiotensin converting enzyme inhibitor (ACEI)/angiotensin receptor blocker (ARB)] alone or in any AHT combination was associated with better BP control. The AHT-dependent BP improvement was independent of confounders.

Conclusion

In this pan-European OSA patient cohort, BP control improved following initiation of PAP. Longer PAP treatment duration, was associated with a favourable effect on BP. Our study suggests that ACEI/ARB, alone or in combination with other drug classes, provides a particularly strong reduction of BP and better BP control when combined with PAP in OSA.

Obesity-related kidney disease: Beyond hypertension and insulin-resistance

Chronic kidney disease (CKD) causes considerable morbidity, mortality, and health expenditures worldwide. Obesity is a significant risk factor for CKD development, partially explained by the high prevalence of diabetes mellitus and hypertension in obese patients. However, adipocytes also possess potent endocrine functions, secreting a myriad of cytokines and adipokines that contribute to insulin resistance and induce a chronic low-grade inflammatory state thereby damaging the kidney. CKD development itself is associated with various metabolic alterations that exacerbate adipose tissue dysfunction and insulin resistance. This adipose-renal axis is a major focus of current research, given the rising incidence of CKD and obesity. Cellular senescence is a biologic hallmark of aging, and age is another significant risk factor for obesity and CKD. An elevated senescent cell burden in adipose tissue predicts renal dysfunction in animal models, and senotherapies may alleviate these phenotypes. In this review, we discuss the direct mechanisms by which adipose tissue contributes to CKD development, emphasizing the potential clinical importance of such pathways in augmenting the care of CKD.