Galectin-3, Cardiac Function, and Fibrosis

Unlocking the role of Galectin-3: Implications for sleep disorders and health

Galectin-3 is a member of the lectin family, and is an intriguing protein that is found in diverse tissues across the body. It is known for its multifaceted involvement in various physiological functions, including tissue repair, immune function and neuroinflammation in the central nervous system. It also serves as a paracrine signal, promoting the growth of certain cells and contributing to fibrosis, while higher levels of Galectin-3 in the bloodstream correlate with an increased risk of mortality and cardiovascular disease-related outcomes in the general population. Recent scientific studies have identified a potential link between Galectin-3 and sleep disorders. However, the precise mechanisms through which galectin-3 influences sleep disorders remain an active area of investigation. Although initial studies suggest a potential association between Galectin-3 and sleep disruptions, including conditions, such as insomnia, insufficient sleep time, and obstructive sleep apnea, further research is required to establish a more definitive relationship. This review explores recent findings regarding the potential connection between Galectin-3 and sleep patterns, and offers insights into the complex interplay between this protein and sleep. These discoveries present promising prospects for the development of innovative therapeutic approaches aimed at sleep disorder management, using Galectin-3 as a potential target for interventions or as a biomarker for sleep health.

Glycopolymer Inhibitors of Galectin-3 Suppress the Markers of Tissue Remodeling in Pulmonary Hypertension

Pulmonary hypertension is a cardiovascular disease with a low survival rate. The protein galectin-3 (Gal-3) binding β-galactosides of cellular glycoproteins plays an important role in the onset and development of this disease. Carbohydrate-based drugs that target Gal-3 represent a new therapeutic strategy in the treatment of pulmonary hypertension. Here, we present the synthesis of novel hydrophilic glycopolymer inhibitors of Gal-3 based on a polyoxazoline chain decorated with carbohydrate ligands. Biolayer interferometry revealed a high binding affinity of these glycopolymers to Gal-3 in the subnanomolar range. In the cell cultures of cardiac fibroblasts and pulmonary artery smooth muscle cells, the most potent glycopolymer 18 (Lac-high) caused a decrease in the expression of markers of tissue remodeling in pulmonary hypertension. The glycopolymers were shown to penetrate into the cells. In a biodistribution and pharmacokinetics study in rats, the glycopolymers accumulated in heart and lung tissues, which are most affected by pulmonary hypertension.

Diffuse Myocardial Fibrosis on Cardiac Magnetic Resonance Imaging Is Related to Galectin-3 and Predicts Outcome in Heart Failure

AIMS

Ongoing adverse remodeling is a hallmark of heart failure (HF), which might be reflected by either focal or diffuse myocardial fibrosis. Therefore, in (pre)clinical settings, we used immunohistochemistry or cardiac magnetic resonance imaging (CMR) to investigate the association of (focal or diffuse) fibrosis with cardiac biomarkers and adverse events in HF.

METHODS AND RESULTS

In C57Bl/6J mice, we determined the presence and extent of myocardial fibrosis 6 weeks post-myocardial infarction (MI). Furthermore, we studied 159 outpatient HF patients who underwent CMR, and determined focal and diffuse fibrosis by late gadolinium enhancement (LGE) and post-contrast T1 time of the non-LGE myocardium, respectively. HF patients were categorized based on the presence of LGE, and by the median post-contrast T1 time. Kaplan-Meier and Cox regression analyses were used to determine the association of fibrosis with HF hospitalization and all-cause mortality. LGE was detected in 61 (38%) patients. Cardiac biomarker levels were comparable between LGE-positive and LGE-negative patients. LGE-positive patients with a short T1 time had elevated levels of both NT-proBNP and galectin-3 (1611 vs. 453 ng/L, p = 0.026 and 20 vs. 15 μg/L, p = 0.004, respectively). This was not observed in LGE-negative patients. Furthermore, a short T1 time in LGE-positive patients was associated with a higher risk of adverse events (log-rank p = 0.01).

CONCLUSION

This study implies that cardiac biomarkers reflect active remodeling of the non-infarcted myocardium of patients with focal myocardial scarring. Diffuse fibrosis, in contrast to focal scarring, might have a higher prognostic value regarding adverse outcomes in HF patients.

Circulating heart failure biomarkers beyond natriuretic peptides: review from the Biomarker Study Group of the Heart Failure Association (HFA), European Society of Cardiology (ESC)

New biomarkers are being evaluated for their ability to advance the management of patients with heart failure. Despite a large pool of interesting candidate biomarkers, besides natriuretic peptides virtually none have succeeded in being applied into the clinical setting. In this review, we examine the most promising emerging candidates for clinical assessment and management of patients with heart failure. We discuss high-sensitivity cardiac troponins (Tn), procalcitonin, novel kidney markers, soluble suppression of tumorigenicity 2 (sST2), galectin-3, growth differentiation factor-15 (GDF-15), cluster of differentiation 146 (CD146), neprilysin, adrenomedullin (ADM), and also discuss proteomics and genetic-based risk scores. We focused on guidance and assistance with daily clinical care decision-making. For each biomarker, analytical considerations are discussed, as well as performance regarding diagnosis and prognosis. Furthermore, we discuss potential implementation in clinical algorithms and in ongoing clinical trials.

Differences of TNF-α, IL-6 and Gal-3 in lobar pneumonia and bronchial pneumonia caused by mycoplasma pneumoniae

OBJECTIVE

To investigate the differences of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and galectin-3 concentrations in lobar pneumonia and bronchopneumonia induced by mycoplasma pneumoniae (MP) in children and to explore these related factors predicting the severity of MP.

METHODS

A total of 148 children with mycoplasma pneumoniae pneumonia (MPP) and 32 healthy controls were analyzed from March 2017 to August 2018 in our province. Clinical information was collected from the hospitalized MP patients. The 148 patients with MPP were divided into two groups: lobar pneumonia group and bronchial pneumonia group. The 32 healthy children were considered the control group. The concentrations of TNF-α, IL-6 and Gal-3 were examined in the serum of 148 children patients with MPP and 32 healthy children by double-antibody sandwich enzyme-linked immunosorbent assay (ELISA).

RESULTS

The TNF-α, IL-6 and Gal-3 levels were obviously higher in both the lobar pneumonia and bronchial pneumonia groups, compared to those in the control group. Furthermore, these levels were significantly higher in the lobar pneumonia group, compared to the bronchial pneumonia group. After treatment, the levels of TNF-α, IL-6 and Gal-3 totally descended during the recovery period.

CONCLUSION

There are differences in serum TNF-α, IL-6 and Gal-3 concentrations in lobar pneumonia and bronchial pneumonia caused by MP in children. In general, the TNF-α, IL-6 and Gal-3 levels were significantly higher in the lobar pneumonia group, when compared to the bronchial pneumonia group. This was because most lobar pneumonia cases are much more serious than bronchial pneumonia. Moreover, it has been proven that TNF-α, IL-6 and Gal-3 may play an important role in the pathogenesis development of MPP. At the same time, these are important issues in diagnosing MPP.

The effect of initial periodontal treatment on gingival crevicular fluid galectin-3 levels in participants with periodontal disease

BACKGROUND

The aim of study was to evaluate galectin-3 levels in gingival crevicular fluid (GCF) from periodontally healthy (H) patients and those with periodontitis (P), gingivitis (G) and the effect of initial periodontal treatment on GCF galectin-3 level.

METHODS

A total of 75 participants, 25 patients with periodontitis, 25 with gingivitis and 25 periodontally healthy subjects were included into the study. Patients with periodontal disease received initial periodontal treatment. GCF galectin-3 level was assessed at baseline and at the 6th-8th weeks after completion of periodontal treatment. GCF galectin-3 level was evaluated by enzyme-linked immunosorbent assay.

RESULTS

GCF galectin-3 level was the lowest in the H group (102.31[63.07] μg/30 s), followed by the G group (241.45[145.89] μg/30 s) and the highest in the P group (338.27[219.37] μg/30 s). These differences were statistically significant between H and the other groups (P < 0.001). After initial periodontal treatment, GCF galectin-3 level significantly decreased in the G and P groups compared to baseline values (P < 0.01).

CONCLUSION

The results of this study suggest that GCF galectin-3 level is a potential biomarker for the evaluation of gingival inflammation and initial periodontal treatment is effective in decreasing GCF galectin-3 level.

Genetic Deletion of Galectin-3 Alters the Temporal Evolution of Macrophage Infiltration and Healing Affecting the Cardiac Remodeling and Function after Myocardial Infarction in Mice

We studied the role of galectin-3 (Gal-3) in the expression of alternative activation markers (M2) on macrophage, cytokines, and fibrosis through the temporal evolution of healing, ventricular remodeling, and function after myocardial infarction (MI). C57BL/6J and Gal-3 knockout mice (Lgals3^-/-) were subjected to permanent coronary ligation or sham. We studied i) mortality, ii) macrophage infiltration and expression of markers of alternative activation, iii) cytokine, iv) matrix metalloproteinase-2 activity, v) fibrosis, and vi) cardiac function and remodeling. At 1 week post-MI, lack of Gal-3 markedly attenuated F4/80+ macrophage infiltration and significantly increased the expression of Mrc1 and Chil1, markers of M2 macrophages at the MI zone. Levels of IL-10, IL-6, and matrix metalloproteinase-2 were significantly increased, whereas tumor necrosis factor-α, transforming growth factor-β, and fibrosis were remarkably attenuated at the infarct zone. In Gal-3 knockout mice, scar thinning ratio, expansion, and cardiac remodeling and function were severely affected from the onset of MI. At 4 weeks post-MI, the natural evolution of fibrosis in Gal-3 knockout mice was also affected. Our results suggest that Gal-3 is essential for wound healing because it regulates the dynamics of macrophage infiltration, proinflammatory and anti-inflammatory cytokine expression, and fibrosis along the temporal evolution of MI in mice. The deficit of Gal-3 affected the dynamics of wound healing, thus aggravating the evolution of remodeling and function.

Trypanosoma cruzi cleaves galectin-3 N-terminal domain to suppress its innate microbicidal activity

Galectin-3 is the best-characterized member of galectins, an evolutionary conserved family of galactoside-binding proteins that play central roles in infection and immunity, regulating inflammation, cell migration and cell apoptosis. Differentially expressed by cells and tissues with immune privilege, they bind not only to host ligands, but also to glycans expressed by pathogens. In this regard, we have previously shown that human galectin-3 recognizes several genetic lineages of the protozoan parasite Trypanosoma cruzi, the causal agent of Chagas' disease or American trypanosomiasis. Herein we describe a molecular mechanism developed by T. cruzi to proteolytically process galectin-3 that generates a truncated form of the protein lacking its N-terminal domain - required for protein oligomerization - but still conserves a functional carbohydrate recognition domain (CRD). Such processing relies on specific T. cruzi proteases, including Zn-metalloproteases and collagenases, and ultimately conveys profound changes in galectin-3-dependent effects, as chemical inhibition of parasite proteases allows galectin-3 to induce parasite death in vitro. Thus, T. cruzi might have established distinct mechanisms to counteract galectin-3-mediated immunity and microbicide properties. Interestingly, non-pathogenic T. rangeli lacked the ability to cleave galectin-3, suggesting that during evolution two genetically similar organisms have developed different molecular mechanisms that, in the case of T. cruzi, favoured its pathogenicity, highlighting the importance of T. cruzi proteases to avoid immune mechanisms triggered by galectin-3 upon infection. This study provides the first evidence of a novel strategy developed by T. cruzi to abrogate signalling mechanisms associated with galectin-3-dependent innate immunity.

Stimulation of β-adrenoceptors up-regulates cardiac expression of galectin-3 and BIM through the Hippo signalling pathway

Background and Purpose

Expression of the pro‐fibrotic galectin‐3 and the pro‐apoptotic BIM is elevated in diseased heart or after β‐adrenoceptor stimulation, but the underlying mechanisms are unclear. This question was addressed in the present study.

Experimental Approach

Wild‐type mice and mice with cardiac transgenic expression of β₂‐adrenoceptors, mammalian sterile‐20 like kinase 1 (Mst1) or dominant‐negative Mst1, and non‐specific galectin‐3 knockout mice were used. Effects of the β‐adrenoceptor agonist isoprenaline or β‐adrenoceptor antagonists were studied. Rat cardiomyoblasts (H9c2) were used for mechanistic exploration. Biochemical assays were performed.

Key Results

Isoprenaline treatment up‐regulated expression of galectin‐3 and BIM, and this was inhibited by non‐selective or selective β‐adrenoceptor antagonists (by 60–70%). Cardiac expression of galectin‐3 and BIM was increased in β₂‐adrenoceptor transgenic mice. Isoprenaline‐induced up‐regulation of galectin‐3 and BIM was attenuated by Mst1 inactivation, but isoprenaline‐induced galectin‐3 expression was exaggerated by transgenic Mst1 activation. Pharmacological or genetic activation of β‐adrenoceptors induced Mst1 expression and yes‐associated protein (YAP) phosphorylation. YAP hyper‐phosphorylation was also evident in Mst1 transgenic hearts with up‐regulated expression of galectin‐3 (40‐fold) and BIM as well as up‐regulation of many YAP‐target genes by RNA sequencing. In H9c2 cells, isoprenaline induced YAP phosphorylation and expression of galectin‐3 and BIM, effects simulated by forskolin but abolished by PKA inhibitors, and YAP knockdown induced expression of galectin‐3 and BIM.

Conclusions and Implications

Stimulation of cardiac β‐adrenoceptors activated the Mst1/Hippo pathway leading to YAP hyper‐phosphorylation with enhanced expression of galectin‐3 and BIM. This signalling pathway would have therapeutic potential.

Linked Articles

This article is part of a themed section on Adrenoceptors—New Roles for Old Players. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.14/issuetoc

Intermediate filaments in cardiomyopathy

Intermediate filament (IF) proteins are critical regulators in health and disease. The discovery of hundreds of mutations in IF genes and posttranslational modifications has been linked to a plethora of human diseases, including, among others, cardiomyopathies, muscular dystrophies, progeria, blistering diseases of the epidermis, and neurodegenerative diseases. The major IF proteins that have been linked to cardiomyopathies and heart failure are the muscle-specific cytoskeletal IF protein desmin and the nuclear IF protein lamin, as a subgroup of the known desminopathies and laminopathies, respectively. The studies so far, both with healthy and diseased heart, have demonstrated the importance of these IF protein networks in intracellular and intercellular integration of structure and function, mechanotransduction and gene activation, cardiomyocyte differentiation and survival, mitochondrial homeostasis, and regulation of metabolism. The high coordination of all these processes is obviously of great importance for the maintenance of proper, life-lasting, and continuous contraction of this highly organized cardiac striated muscle and consequently a healthy heart. In this review, we will cover most known information on the role of IFs in the above processes and how their deficiency or disruption leads to cardiomyopathy and heart failure.

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.