The relation among aldosterone, galectin-3, and myocardial fibrosis: a prospective clinical pilot follow-up study

Insights into the Role of Galectin-3 as a Diagnostic and Prognostic Biomarker of Atrial Fibrillation

Atrial fibrillation (AF) is an irregular atrial activity and the most prevalent type of arrhythmia. Although AF is easily diagnosed with an electrocardiogram, there is a keen interest in identifying an easy-to-dose biomarker that can predict the prognosis of AF and its recurrence. Galectin-3 (Gal-3) is a beta-galactoside binding protein from the lectin family with pro-fibrotic and -inflammatory effects and a pivotal role in a variety of biological processes, cell proliferation, and differentiation; therefore, it is implicated in the pathogenesis of many cardiovascular (e.g., heart failure (HF)) and noncardiovascular diseases. However, its specificity and sensitivity as a potential marker in AF patients remain debated and controversial. This article comprehensively reviewed the evidence regarding the interplay between Gal-3 and patients with AF. Clinical implications of measuring Gal-3 in AF patients for diagnosis and prognosis are mentioned. Moreover, the role of Gal-3 as a potential biomarker for the management of AF recurrence is investigated. The association of Gal-3 and AF in special populations (coronary artery disease, HF, metabolic syndrome, chronic kidney disease, and diabetes mellitus) has been explored in this review. Overall, although further studies are needed to enlighten the role of Gal-3 in the diagnosis and treatment of AF, our study demonstrated the high potential of this molecule to be used and focused on by researchers and clinicians.

Diabetes mellitus is associated with more adverse non-hemodynamic left ventricular remodeling and less recovery in patients with primary aldosteronism

The elevated aldosterone in primary aldosteronism (PA) is associated with increased insulin resistance and prevalence of diabetes mellitus (DM). Both aldosterone excess and DM lead to left ventricular (LV) pathological remodeling. In this study, we investigated the impact of DM on LV non-hemodynamic remodeling in patients with PA. We enrolled 665 PA patients, of whom 112 had DM and 553 did not. Clinical, biochemical, and echocardiographic data were analyzed at baseline and 1 year after adrenalectomy. LV non-hemodynamic remodeling was represented by inappropriate excess left ventricular mass index (ieLVMI), which was defined as the difference between left ventricular mass index (LVMI) and predicted left ventricular mass index (pLVMI). Propensity score matching (PSM) was used with age, sex, systolic, and diastolic blood pressure to adjust for baseline variables. After PSM, the patient characteristics were balanced between the DM and non-DM groups, except for fasting glucose, HbA1c, and lipid profile. A total of 111 DM and 419 non-DM patients were selected for further analysis. Compared to the non-DM group, the DM group had significantly higher ieLVMI and LVMI. After multivariable linear regression analysis, the presence of DM remained a significant predictor of increased ieLVMI. After adrenalectomy, ieLVMI decreased significantly in the non-DM group but not in DM group. The presence of DM in PA patients was associated with more prominent non-hemodynamic LV remodeling and less recovery after adrenalectomy.

The Diagnostic and Therapeutic Potential of Galectin-3 in Cardiovascular Diseases

Galectin-3 plays a prominent role in chronic inflammation and has been implicated in the development of many disease conditions, including heart disease. Galectin-3, a regulatory protein, is elevated in both acute and chronic heart failure and is involved in the inflammatory pathway after injury leading to myocardial tissue remodelling. We discussed the potential utility of galectin-3 as a diagnostic and disease severity/prognostic biomarker in different cardio/cerebrovascular diseases, such as acute ischemic stroke, acute coronary syndromes, heart failure and arrhythmogenic cardiomyopathy. Over the last decade there has been a marked increase in the understanding the role of galectin-3 in myocardial fibrosis and inflammation and as a therapeutic target for the treatment of heart failure and myocardial infarction.

Left ventricular remodeling and dysfunction in primary aldosteronism

Primary aldosteronism (PA) is a common cause of secondary hypertension and is associated with worse cardiovascular outcomes. The elevated aldosterone in PA leads to left ventricular (LV) remodeling and dysfunction. In recent decades, clinical studies have demonstrated worse LV remodeling including increased LV mass and cardiac fibrosis in patients with PA compared to patients with essential hypertension. Several mechanisms may explain the process of aldosterone-induced LV remodeling, including directly profibrotic and hypertrophic effects of aldosterone on myocardium, increased reactive oxygen species and profibrotic molecules, dysregulation of extracellular matrix metabolism, endothelium dysfunction and circulatory macrophages activation. LV remodeling causes LV diastolic and systolic dysfunction, which may consequently lead to clinical complications such as heart failure, atrial fibrillation, ischemic heart disease, and other vascular events. Adequate treatment with adrenalectomy or medical therapy can improve LV remodeling and dysfunction in PA patients. In this review, we discuss the mechanisms of aldosterone-induced LV remodeling and provide an up-to-date review of clinical research about LV remodeling-related heart structural changes, cardiac dysfunction, and their clinical impacts on patients with PA.

In the Refractory Hypertension “Labyrinth”. Focus on Primary Hyperaldosteronism

Primary hyperaldosteronism is an existence of a functional autonomous source with increased aldosterone production (full or partial) in relation to the renin-angiotensin system. Increased production of aldosterone by the adrenal cortex is the most common form of a secondary hypertension despite the low attention of internists to the problem. The success of a treatment and a prognosis of these patients depend on correct choice of screening (aldosterone/renin ratio) and clarifying diagnostic methods. There are clear algorithms for conducting these tests in accordance with Russian and International recommendations in the respective groups of patients. The purpose of this case report is to demonstrate the long way to diagnosis of primary hyperaldosteronism in a young patient with refractory hypertension, right adrenal adenoma, and clinical (convulsions, weakness) and laboratory signs of hypokalemia. It should not only have made the diagnosis easy, but it could have also absolutely justified the surgical tactics. Unfortunately, the final verification of the disease by carrying out a saline test was accomplished 13 years after the debut of hypertension and 10 years after the primary visualization of the adrenal adenoma.

Effect of Galectin 3 on Aldosterone-Associated Risk of Cardiovascular Mortality in Patients Undergoing Coronary Angiography

Recent experimental studies have suggested that galectin-3 has an interaction with aldosterone, and modifies its adverse effects. We therefore aimed to elucidate whether the relationship between plasma aldosterone concentrations (PACs) and long-term fatal cardiovascular (CV) events would depend on plasma galectin-3 levels. A total of 2,457 patients (median age: 63.5 [interquartile range (IQR) = 56.3 to 70.6] years, 30.1% women) from the LUdwigshafen RIsk and Cardiovascular Health study, with a median follow-up of 9.9 (IQR = 8.5 to 10.7) years, were included. We tested the interaction between aldosterone and galectin-3 for CV-mortality using a multivariate Cox proportional hazard model, reporting hazard ratios (HRs) with 95% confidence intervals (95%CIs). Adjustments for multiple CV risk factors as well as medication use were included. Mean PAC was 79.0 (IQR = 48.0 to 124.0) pg/ml and there were 558 (16.8%) CV deaths. There was a significant interaction between PAC and galectin-3 (p = 0.021). When stratifying patients by the median galectin-3, there was a significant association between aldosterone and CV-mortality for those above (HR per 1 standard deviation = 1.14; 95%CI [1.01 to 1.30], p = 0.023), but not below the cut-off value (HR per 1 standard deviation = 1.00; 95%CI [0.87 to 1.15], p = 0.185). In conclusion, the current study demonstrates for the first time a modifying effect of galectin-3 on the association between aldosterone and CV-mortality risk in humans. These findings indicate that galectin-3 is an intermediate between aldosterone and adverse outcomes.

Beyond immunohistochemistry and immunocytochemistry: a current perspective on galectin-3 and thyroid cancer

Introduction: Thyroid nodules are very common in the general population, most are benign, and do not require any intervention. However, often a challenge exists in discriminating benign thyroid nodules from cancer, without performing a biopsy or operation. Galectin-3 is a beta-galactoside binding protein that is involved in diverse biological processes and has been found to have increased expression in many human cancer types including thyroid cancer. As a result, recent studies have investigated its utility as a serum biomarker for thyroid cancer, as well as a novel target for in vivo molecular imaging of cancer. Additionally, given its role in tumorigenesis and cancer progression, galectin-3 targeting is currently under investigation for its potential utility as treatment for thyroid cancer.Areas covered: Recent studies of galectin-3 as a serum marker for thyroid cancer diagnosis, and in the preclinical setting as a target for cancer imaging and therapy.Expert opinion: Even though current studies evaluating galectin-3 as a serum marker and target for cancer imaging and therapy are promising, further research is required before it can be adopted into routine clinical use.

Plasma galectin-3 concentrations in patients with primary aldosteronism

BACKGROUND

The incidence of cardiovascular events is higher in patients with primary aldosteronism than in patients with essential hypertension (EHT), despite similar blood pressure levels. This suggests detrimental cardiovascular effects of aldosterone. Amongst others, it has been suggested that galectin-3 (Gal-3) is a key mediator in aldosterone-induced myocardial fibrosis.

OBJECTIVE

We studied whether patients with primary aldosteronism have higher plasma Gal-3 concentrations than patients with EHT and evaluated its reversibility after adrenalectomy.

METHODS

In a retrospective cohort from our tertiary referral centre, we measured plasma Gal-3 concentrations in 78 patients with primary aldosteronism, 39 cured primary aldosteronism patients after adrenalectomy and 56 patients with EHT. Paired samples were available in 11 patients (preadrenalectomy and postadrenalectomy). We compared plasma Gal-3 levels by univariate analysis of covariance with correction for cardiovascular risk factors, plasma creatinine concentration, plasma potassium levels and alcohol intake.

RESULTS

Adjusted plasma Gal-3 concentrations in patients with primary aldosteronism, patients after adrenalectomy and patients with EHT were 11.39 ± 0.60, 11.64 ± 0.81 and 11.41 ± 0.73 ng/ml, respectively (mean ± SD; P = 0.95). In 11 patients of whom paired samples were available, mean Gal-3 concentrations increased from 10.03 ± 1.67 ng/ml preadrenalectomy to 14.36 ± 2.07 ng/ml postadrenalectomy (P < 0.01).

CONCLUSION

In patients with primary aldosteronism, plasma Gal-3 concentrations are not elevated when compared with patients with EHT, and levels do not decrease after adrenalectomy. These results are in contrast to previous studies and do not support a pathophysiological role of plasma Gal-3 in the increased cardiovascular risk in patients with primary aldosteronism.

Galectin-3 as a novel biomarker for disease diagnosis and a target for therapy (Review)

Galectin-3 is a member of the galectin family, which are β‑galactoside‑binding lectins with ≥1 evolutionary conserved carbohydrate‑recognition domain. It binds proteins in a carbohydrate‑dependent and ‑independent manner. Galectin‑3 is predominantly located in the cytoplasm; however, it shuttles into the nucleus and is secreted onto the cell surface and into biological fluids including serum and urine. It serves important functions in numerous biological activities including cell growth, apoptosis, pre‑mRNA splicing, differentiation, transformation, angiogenesis, inflammation, fibrosis and host defense. Numerous previous studies have indicated that galectin‑3 may be used as a diagnostic or prognostic biomarker for certain types of heart disease, kidney disease and cancer. With emerging evidence to support the function and application of galectin‑3, the current review aims to summarize the latest literature regarding the biomarker characteristics and potential therapeutic application of galectin‑3 in associated diseases.

Biomarkers in patients with myocardial fibrosis

Myocardial fibrosis is observed in many cardiovascular diseases including hypertension, heart failure and cardiomyopathy. Myocardial fibrosis has been proved to be reversible and treatable only under timely intervention, which makes early detection and assessment of fibrosis crucial. Aside from tissue biopsy as the gold standard for the diagnosis of myocardial fibrosis, circulating biomarkers have been adopted as noninvasive assessment of this lesion. Dysregulated collagen deposition is thought to be the major cause of myocardial fibrosis. Collagens, procollagens, TGF-β, TIMP, galectin-3, and microRNAs are thought to be indicators of myocardial fibrosis. In this review, we summarize the molecules that are frequently used as biomarkers in diagnosis of cardiac fibrosis. Mechanisms of fibrosis that they take part in are also introduced.

Vascular dysfunction and fibrosis in stroke-prone spontaneously hypertensive rats: The aldosterone-mineralocorticoid receptor-Nox1 axis

AIMS

We questioned whether aldosterone and oxidative stress play a role in vascular damage in severe hypertension and investigated the role of Nox1 in this process.

MATERIALS AND METHODS

We studied mesenteric arteries, aortas and vascular smooth muscle cells (VSMC) from WKY and SHRSP rats. Vascular effects of eplerenone or canrenoic acid (CA) (mineralocorticoid receptor (MR) blockers), ML171 (Nox1 inhibitor) and EHT1864 (Rac1/2 inhibitor) were assessed. Nox1-knockout mice were also studied. Vessels and VSMCs were probed for Noxs, reactive oxygen species (ROS) and pro-fibrotic/inflammatory signaling.

KEY FINDINGS

Blood pressure and plasma levels of aldosterone and galectin-3 were increased in SHRSP versus WKY. Acetylcholine-induced vasorelaxation was decreased (61% vs 115%) and phenylephrine-induced contraction increased in SHRSP versus WKY (Emax 132.8% vs 96.9%, p<0.05). Eplerenone, ML171 and EHT1864 attenuated hypercontractility in SHRSP. Vascular expression of collagen, fibronectin, TGFβ, MCP-1, RANTES, MMP2, MMP9 and p66Shc was increased in SHRSP versus WKY. These changes were associated with increased ROS generation, 3-nitrotyrosine expression and Nox1 upregulation. Activation of vascular p66Shc and increased expression of Nox1 and collagen I were prevented by CA in SHRSP. Nox1 expression was increased in aldosterone-stimulated WKY VSMCs, an effect that was amplified in SHRSP VSMCs (5.2vs9.9 fold-increase). ML171 prevented aldosterone-induced VSMC Nox1-ROS production. Aldosterone increased vascular expression of fibronectin and PAI-1 in wild-type mice but not in Nox1-knockout mice.

SIGNIFICANCE

Our findings suggest that aldosterone, which is increased in SHRSP, induces vascular damage through MR-Nox1-p66Shc-mediated processes that modulate pro-fibrotic and pro-inflammatory signaling pathways.

Role of galectin-3 in autoimmune and non-autoimmune nephropathies

Galectins are evolutionary conserved β-galactoside binding proteins with a carbohydrate-recognition domain (CRD) of approximately 130 amino acids. In mammals, 15 members of the galectin family have been identified and classified into three subtypes according to CRD organization: prototype, tandem repeat-type and chimera-type galectins. Galectin-3 (gal-3) is the only chimera type galectin in vertebrates containing one CRD linked to an unusual long N-terminal domain which displays non-lectin dependent activities. Although recent studies revealed unique, pleiotropic and context-dependent functions of gal-3 in both extracellular and intracellular space, gal-3 specific pathways and its ligands have not been clearly defined yet. In the kidney gal-3 is involved in later stages of nephrogenesis as well as in renal cell cancer. However, gal-3 has recently been associated with lupus glomerulonephritis, with Familial Mediterranean Fever-induced proteinuria and renal amyloidosis. Gal-3 has been studied in experimental acute kidney damage and in the subsequent regeneration phase as well as in several models of chronic kidney disease, including nephropathies induced by aging, ischemia, hypertension, diabetes, hyperlipidemia, unilateral ureteral obstruction and chronic allograft injury. Because of the pivotal role of gal-3 in the modulation of immune system, wound repair, fibrosis and tumorigenesis, it is not surprising that gal-3 can be an intriguing prognostic biomarker as well as a promising therapeutic target in a great variety of diseases, including chronic kidney disease, chronic heart failure and cardio-renal syndrome. This review summarizes the functions of gal-3 in kidney pathophysiology focusing on the reported role of gal-3 in autoimmune diseases.