Aldosterone as a mediator of severity in retinal vascular disease: Evidence and potential mechanisms

Revisiting the renin-angiotensin-aldosterone system in the eye: Mechanistic insights and pharmacological targets

The renin-angiotensin-aldosterone system (RAAS) plays a fundamental role in regulating blood pressure and fluid homeostasis through key effectors such as angiotensin II and aldosterone. These agents and their receptors have become crucial molecular targets in several cardiovascular and renal diseases. Over the past few decades, a growing body of evidence has revealed the presence of RAAS components in ocular structures, suggesting a tissue-specific RAAS within the eye. Building on this knowledge, studies have indicated that the ocular RAAS plays a significant role in the pathogenesis of various eye diseases. An impaired and overactivated RAAS contributes to the development of severe and widespread disorders affecting both the anterior and posterior segments of the eye. In this context, the current work aims to delve into the pivotal molecular pathways involving the RAAS, with an in-depth exploration of the ocular pathophysiology. It focuses on the relationship between overactivation of the RAAS and oxidative stress, as well as the exacerbation of neovascularization and inflammatory processes. The objective is to provide an updated and comprehensive understanding of the role of the RAAS in ophthalmological diseases, highlighting the therapeutic potential of RAAS modulators and discussing the controversies and challenges in this area of research.

Role of aldosterone in various target organ damage in patients with hypertensive emergency: a cross-sectional study

BACKGROUND

Hypertensive emergency is a critical disease that causes multiple organ injuries. Although the renin-angiotensin-aldosterone system (RAS) is enormously activated in this disorder, whether the RAS contributes to the development of the organ damage has not been fully elucidated. This cross-sectional study was conducted to characterize the association between RAS and the organ damage in patients with hypertensive emergencies.

METHODS

We enrolled 63 patients who visited our medical center with acute severe hypertension and multiple organ damage between 2012 and 2020. Hypertensive target organ damage was evaluated on admission, including severe kidney impairment (eGFR less than 30 mL/min/1.73 m2, SKI), severe retinopathy, concentric left ventricular hypertrophy (c-LVH), thrombotic microangiopathy (TMA), heart failure with reduced ejection fraction (HFrEF) and cerebrovascular disease. Then, whether each organ injury was associated with blood pressure or a plasma aldosterone concentration was analyzed.

RESULTS

Among 63 patients, 31, 37, 43 and 8 cases manifested SKI, severe retinopathy, c-LVH and ischemic stroke, respectively. All populations with the organ injuries except cerebral infarction had higher plasma aldosterone concentrations than the remaining subset but exhibited a variable difference in systolic or diastolic blood pressure. Twenty-two patients had a triad of SKI, severe retinopathy and c-LVH, among whom 5 patients manifested TMA. Furthermore, the number of the damaged organs was correlated with plasma aldosterone levels (Spearman's coefficient = 0.50), with a strong association observed between plasma aldosterone (≥ 250 pg/mL) and 3 or more complications (odds ratio = 9.16 [95%CI: 2.76-30.35]).

CONCLUSION

In patients with hypertensive emergencies, a higher aldosterone level not only contributed to the development of the organ damage but also was associated with the number of damaged organs in each patient.

Glaucoma and the ocular renin-angiotensin-aldosterone system: Update on molecular signalling and treatment perspectives

Glaucoma, a leading cause of blindness worldwide, encompasses a group of pathological conditions affecting the optic nerve and is characterized by progressive retinal ganglion cell loss, cupping of the optic nerve head, and distinct visual field defects. While elevated intraocular pressure (IOP) is the main risk factor for glaucoma, many patients do not have elevated IOP. Consequently, other risk factors, such as ocular blood flow abnormalities and immunological factors, have been implicated in its pathophysiology. Traditional therapeutic strategies primarily aim to reduce IOP, but there is growing interest in developing novel treatment approaches to improve disease management and reduce the high rates of severe visual impairment. In this context, targeting the ocular renin-angiotensin-aldosterone system (RAAS) has been found as a potential curative strategy. The RAAS contributes to glaucoma development through key effectors such as prorenin, angiotensin II, and aldosterone. Recent evidence has highlighted the potential of using RAAS modulators to combat glaucoma, yielding encouraging results. Our study aims to explore the molecular pathways linking the ocular RAAS and glaucoma, summarizing recent advances that elucidate the role of the RAAS in triggering oxidative stress, inflammation, and remodelling in the pathogenesis of glaucoma. Additionally, we will present emerging therapeutic approaches that utilize RAAS modulators and antioxidants to slow the progression of glaucoma.

Recent Insights into the Etiopathogenesis of Diabetic Retinopathy and Its Management

Purpose: Diabetic retinopathy (DR) is a microvascular retinal disease associated with chronic diabetes mellitus, characterized by the damage of blood vessels in the eye. It is projected to become the leading cause of blindness, given the increasing burden of the diabetic population worldwide. The diagnosis and management of DR pose significant challenges for physicians because of the involvement of multiple biochemical pathways and the complexity of ocular tissues. This review aims to provide a comprehensive understanding of the molecular pathways implicated in the pathogenesis of DR, including the polyo pathway, hexosamine pathway, protein kinase C (PKC), JAK/STAT signaling pathways, and the renin-angiotensin system (RAS). Methods: Academic databases such as PubMed, Scopus, Google Scholar and Web of Science was systematically searched using a carefully constructed search strategy incorporating keywords like "Diabetic Retinopathy," "Molecular Pathways," "Pharmacological Treatments," and "Clinical Trials" to identify relevant literature for the comprehensive review. Results: In addition to activating other inflammatory cascades, these pathways contribute to the generation of oxidative stress within the retina. Furthermore, it aims to explore the existing pharmacotherapy options available for the treatment of DR. In addition to conventional pharmacological therapies such as corticosteroids, antivascular endothelial growth factors, and nonsteroidal anti-inflammatory drugs (NSAIDs), this review highlights the potential of repurposed drugs, phyto-pharmaceuticals, and novel pipeline drugs currently undergoing various stages of clinical trials. Conclusion: Overall, this review serves as a technical exploration of the complex nature of DR, highlighting both established and emerging molecular pathways implicated in its pathogenesis. Furthermore, it delves into the available pharmacological treatments, as well as the promising repurposed drugs, phyto-pharmaceuticals, and novel drugs currently being evaluated in clinical trials, with a focus on their specific mechanisms of action.

Possible dose-dependent effect of eplerenone on intraocular pressure

Purpose

Intraocular pressure (IOP) is the main modifiable risk factor for glaucoma. Current therapies target the anterior outflow of aqueous humor or its production. This study aims to demonstrate eplerenone could reduce IOP through a possible posterior outflow path via retinal pigment epithelium (RPE).

Methods

In this retrospective study, IOP changes in patients undergoing eplerenone treatment were investigated. Inclusion criteria were IOP data immediately before and during treatment. Exclusion criteria included ophthalmic procedures, changes in topical glaucoma treatment, or taking systemic medications affecting IOP. After reviewing 162 charts, 41 subjects were eligible. Pearson correlation test was used to investigate the correlation between continuous IOP and eplerenone dosage.

Results

The mean ± SD IOP before eplerenone treatment was 14.31 ± 3.73 mmHg and decreased to 13.50 ± 4.04 mmHg; however, this was not statistically significant (P = 0.39). In subset of patients with eplerenone dose of more than 25 mg/day and baseline IOP equal to or less than 15 mmHg, the mean IOP before eplerenone treatment was 12.33 ± 2.59 mmHg and decreased to 10.33 ± 2.99, which is a trend toward IOP reduction with a 16% reduction in IOP (P = 0.055).

Conclusion

A possible dose-dependent decrease in IOP with eplerenone provides indirect evidence for the posterior flow model and suggests the mineralocorticoid receptors (MRs) in RPE play a role in the posterior flow of aqueous humor. It can be deduced that the RPE pumps responsible for the posterior flow of aqueous humor are MR-regulated and their function can be enhanced with MR antagonists.

Ocular steroidome in human eyes and in eyes with complex central serous chorioretinopathy (CSCR)

The exact link between systemic and ocular endogenous corticoids (steroidome) is unclear and whether the ocular steroidome is altered in CSCR eyes is unknown. The aims of this study were to analyze the human steroidome in the aqueous humor as a function of age, sex and time of the day, to correlate systemic and ocular steroidome and to analyze the ocular steroidome in long lasting complex inactive CSCR. Based on our results, we present two CSCR cases treated by the combination of oral mineralocorticoid antagonist and glucocorticoids drops. In a cross-sectional study, aqueous humor (AH) was collected between 8am and 6 pm from 50 unaffected individuals (25 men and 25 women) and from 14 patients with chronic CSCR, during cataract surgery. In addition, simultaneous serum and AH were collected from 27 individuals undergoing cataract surgery and, simultaneous AH and vitreous were collected from 9 patients undergoing cataract and vitrectomy to estimate corticoids levels in the different compartments. The steroidome was determined using a LC-MS/MS method that quantifies 13 endogenous corticoids from the gluco, mineralocorticoid and androgen pathways. In AH and vitreous, the highest corticoid level is reached by cortisol (F), that represents less than 10% of F serum level. The cortisol levels in the serum did not correlate with ocular cortisol levels. Serum and ocular cortisone (E) levels correlate, although less than 5% of circulating E reaches the eye. The only mineralocorticoids measured in the AH were corticosterone (B) and its inactive form, the 11-desoxycorticosterone (A). There was no influence of circadian rhythm on cortisol ocular levels and there was no correlation between the age or the sex and the level of F, E, A, and B. In eyes with chronic inactive CSCR, the levels of the active glucocorticoid form F was lower than in control eyes and the F/E ratio was reduced by 50% but the B/A ratio was higher indicating imbalance towards active mineralocorticoids. Base on this observation, we propose to combine an antagonist of the mineralocorticoid receptor together with topical glucocorticoids in two CSCR patients, resistant to all other treatments, with favorable outcome. Our results indicate that the ocular psteroidome is highly regulated suggesting a local metabolism of ocular corticoids. In eyes with long-lasting complex inactive CSCR, the steroidome analysis shows lower active glucocorticoids and higher active mineralocorticoids.

Hyperaldosteronism Presenting With Unilateral Blindness: A Case Report

Hyperaldosteronism is a common cause of secondary hypertension. It has been classically associated with the clinical triad of hypertension, unexplained hypokalemia, and metabolic alkalosis. We present a case of a 66-year-old man who experienced blindness, hypokalemia, and hypertension that was resistant to anti-hypertension medications. He was found to have a retinal detachment and central retinal vein occlusion (CRVO). Laboratory evaluation revealed a marked elevation of plasma aldosterone activity and suppressed renin. A computerized tomography (CT) abdomen was subsequently ordered, which revealed bilateral adrenal nodules. Adrenal vein sampling was performed, which confirmed bilateral hyperfunctioning adrenal nodules. He was successfully treated with spironolactone. CRVO in the setting of hyperaldosteronism is an uncommon presentation.

Impact of early initiation of renin-angiotensin blockade on renal function and clinical outcomes in patients with hypertensive emergency: a retrospective cohort study

BACKGROUND

Hypertensive emergency is a critical disease that causes multifaceted sequelae, including end-stage kidney disease and cardiovascular disease. Although the renin-angiotensin-aldosterone (RAA) system is enormously activated in this disease, there are few reports that attempt to characterize the effect of early use of RAA inhibitors (RASi) on the temporal course of kidney function.

METHODS

This retrospective cohort study was conducted to clarify whether the early use of RASi during hospitalization offered more favorable benefits on short-term renal function and long-term renal outcomes in patients with hypertensive emergencies. We enrolled a total of 49 patients who visited our medical center with acute severe hypertension and multiple organ dysfunction between April 2012 and August 2020. Upon admission, the patients were treated with intravenous followed by oral antihypertensive drugs, including RASi and Ca channel blockers (CCB). Kidney function as well as other laboratory and clinical parameters were compared between RASi-treated and CCB- treated group over 2 years.

RESULTS

Antihypertensive treatment effectively reduced blood pressure from 222 ± 28/142 ± 21 to 141 ± 18/87 ± 14 mmHg at 2 weeks and eGFR was gradually restored from 33.2 ± 23.3 to 40.4 ± 22.5 mL/min/1.73m² at 1 year. The renal effect of antihypertensive drugs was particularly conspicuous when RASi was started in combination with other conventional antihypertensive drugs at the early period of hospitalization (2nd day [IQR: 1-5.5]) and even in patients with moderately to severely diminished eGFR (< 30 mL/min/1.73 m²) on admission. In contrast, CCB modestly restored eGFR during the observation period. Furthermore, renal survival probabilities were progressively deteriorated in patients who had manifested reduced eGFR (< 15 mL/min/1.73 m²) or massive proteinuria (urine protein/creatinine ≥ 3.5 g/gCr) on admission. Early use of RASi was associated with a favorable 2-year renal survival probability (0.90 [95%CI: 0.77-1.0] vs. 0.63 [95%CI: 0.34-0.92] for RASi ( +) and RASi (-), respectively, p = 0.036) whereas no apparent difference in renal survival was noted for CCB.

CONCLUSIONS

Early use of RASi contributes to the renal functional recovery from acute reduction in eGFR among patients with hypertensive emergencies. Furthermore, RASi offers more favorable effect on 2-year renal survival, compared with CCB.

The role of aldosterone in the pathogenesis of diabetic retinopathy

Aldosterone, as a mineralocorticoid of adrenal origin, has effects that are not limited to the urinary tract. As an important regulator in Vasoactive hormone pathways, aldosterone may play an effect in the pathogenesis of diabetic retinopathy (DR) through the regulation of oxidative stress, vascular regulation, and inflammatory mechanisms. This implies that mineralocorticoids, including aldosterone, have great potential and value for the diagnosis and treatment of DR. Because early studies did not focus on the intrinsic association between mineralocorticoids and DR, targeted research is still in its infancy and there are still many obstacles to its application in the clinical setting. Recent studies have improved the understanding of the effects of aldosterone on DR, and we review them with the aim of exploring possible mechanisms for the treatment and prevention of DR.

The Association Between Circulating Sex Hormones and Central Serous Chorioretinopathy: A Case-Control Study

Background

Central serous chorioretinopathy (CSC) is preferential cocurated in males, however the associations between sex hormones and CSC incidence or progression remains unclear. The sex hormone concentration assessments in CSC cases and healthy controls will update the knowledge in CSC management.

Methods

This case-control study included 59 CSC cases and 30 healthy controls, from January 2019 to December 2020. The CSC cases would be defined as spontaneous resolved if the subretinal fluid were absorbed within three months. The concentrations of total testosterone (TT), free testosterone (FT), estradiol (E2), sex hormone-binding globulin (SHBG), progesterone, leuteinizing hormone (LH) and dehydroepiandrosterone sulfate (DHEA-S) were detected in all the participants. The relationships between sex hormone concentrations and CSC-related characteristics were analyzed with Pearson correlation analyses.

Results

Significantly increased TT, FT, FT/E2 ratio, SHBG concentrations as well as decreased DHEA-S level were detected in non-resolved CSC group compared with the control group. Comparing with the resolved ones, it was found that TT, FT and SHBG concentrations were increased in the non-resolved CSC. A significant positive correlation between TT concentrations and CMT (R²=0.168, P=0.031) as well as SRF height (R²=0.146, P=0.045) were detected in the non-solved CSC group.

Conclusion

Different concentrations of TT, FT, FT/E2 ratio, DHEA-S and SHBG were detected in resolved and non-resolved CSC cases. Sex hormones were related to CSC symptom durations and related parameters.

The Retinal Renin-Angiotensin-Aldosterone System: Implications for Glaucoma

Aldosterone is one of the main effectors of the renin-angiotensin-aldosterone system (RAAS) along with having roles in hypertension, and cardiovascular and renal diseases. Recent evidence has also shown the presence of an active local RAAS within the human eye. It has been shown that at 12 h after a retinal ischemia-reperfusion injury, there is an upregulation of the protein levels of angiotensin II type 1 receptor (AT1-R) in the retina. Furthermore, at 12 h after reperfusion, there is an increase in reactive oxygen species (ROS) production in the retina that is mediated via an NADPH oxidase pathway. This ischemia-reperfusion injury-induced increase of retinal ROS levels and NADPH oxidase expression can be prevented by the administration of an AT1-R antagonist. This suggests that one of the main retinal ischemic injury pathways is via the local RAAS. It has also been reported that progressive retinal ganglion cell loss and glaucomatous optic nerve degeneration without elevated intraocular pressure occur after administration of local or systemic aldosterone. Elucidation of glaucoma pathogenesis, especially normal-tension glaucoma (NTG) subtype by our current animal model can be used for identifying potential therapeutic targets. Based on these results, we are further evaluating NTG prevalence among primary aldosteronism patients.

The role of inflammation and neurodegeneration in diabetic macular edema

The pathogenesis of diabetic macular edema (DME) is complex. Persistently high blood glucose activates multiple cellular pathways and induces inflammation, oxidation stress, and vascular dysfunction. Retinal ganglion cells, macroglial and microglial cells, endothelial cells, pericytes, and retinal pigment epithelium cells are involved. Neurodegeneration, characterized by dysfunction or apoptotic loss of retinal neurons, occurs early and independently from the vascular alterations. Despite the increasing knowledge on the pathways involved in DME, only limited therapeutic strategies are available. Besides antiangiogenic drugs and intravitreal corticosteroids, alternative therapeutic options tackling inflammation, oxidative stress, and neurodegeneration have been considered, but none of them has been currently approved.

Quantitative analysis and clinical application of iris circulation in ischemic retinal disease

BACKGROUND

To evaluate quantitative changes in iris blood circulation in patients with ischemic risk.

METHODS

This observational case-control study included 79 patients with diabetic retinopathy (DR) and retinal vein occlusion (RVO). The RVO group included 21 patients; the monocular proliferative diabetic retinopathy (PDR) group included 19 patients; the nondiabetic retinopathy (NDR) group included 18 patients; and the healthy control group included 21 healthy controls. In the RVO group, we analyzed RVO affected eyes, RVO contralateral eyes, and healthy control eyes. We also compared eyes with PDR and contralateral eyes without PDR, patients with diabetes mellitus (DM) without DR, and healthy control eyes. The microvascular networks of the iris and retina were analyzed using optical coherence tomography angiography. The analysis included vessel area density (VAD) and vessel skeleton density (VSD) of iris and retina.

RESULTS

In the RVO group, the VAD and VSD of iris in the affected eye were higher than those in contralateral and healthy control eyes, and the VAD and VSD of contralateral eyes were higher than those of healthy control eyes. The retinal blood flow of the RVO eyes was less than that of the contralateral and healthy control eyes, but there were no difference between the contralateral eyes and healthy control eyes. The VAD and VSD of iris in PDR were larger than nonproliferative diabetic retinopathy (NPDR) and the NPDR were larger than NDR. There were no differences between NDR and healthy control eyes. Also, there were no differences among the four groups with respect to retinal blood flow.

CONCLUSIONS

Compared with the retina, iris blood circulation quantitative analysis data seem to be more sensitive to ischemia and may be used as a new predictor of ischemic disease, even if further research is needed to better understand the clinical value and importance of this analysis.

TRIAL REGISTRATION

The trial is registered with the clinical trial registration number nct03631108 .

The Correlation of Central Serous Chorioretinopathy and Subsequent Cardiovascular Diseases of Different Types: A Population-Based Cohort Study

The aim of the present study was to survey the relationship between central serous chorioretinopathy (CSC) and several cardiovascular diseases (CVDs) with different severities using the National Health Insurance Research Database. A retrospective cohort study was conducted. Subjects with CSC were enrolled according to the relevant diagnostic codes, and an age- and gender-matched population was used as the control group with a 1:4 ratio. The main outcome being considered was the development of CVD after CSC exposure. Cox proportional hazard regression was applied to calculate the adjusted hazard ratio (aHR) of CSC and CVD of different types. A total of 2865 patients that were diagnosed with CSC were enrolled in the study group, while another 11,460 non-CSC subjects were selected as the control group. There were 171 events of CVD which occurred in the study group, while another 557 cases were found in the control group. No significant differences were observed among the CVD cases between the study and control group, whether they had an acute or chronic form, according to the aHR. In the subgroup analysis, there was a significantly higher risk of CVD development in the male population aged from 40 to 59 years (aHR: 1.351, confidence interval (CI): 1.063–1.716), which was mainly due to the higher risk of mild CVD (aHR: 1.391, CI: 1.062–1.822). On the contrary, there was no significant difference in CVD development in any of the age subgroups of the female population. In conclusion, the existence of CSC is correlated with a higher rate of chronic CVD occurrence in the middle-aged male population.