Legumain is a predictor of all-cause mortality and potential therapeutic target in acute myocardial infarction

Associations of Serum Legumain with Severity and Prognosis Among Acute Exacerbation of Chronic Obstructive Pulmonary Disease Patients

Background

A number of studies have demonstrated that legumain is engaged in the pulmonary diseases. Nevertheless, the role of legumain is indistinct in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). The aim is to identify the correlation of serum legumain with AECOPD patients through a prospective cohort study.

Methods

All 202 patients with AECOPD were enrolled. Fasting venous blood was collected. Serum legumain was detected by ELISA.

Results

On admission, serum legumain concentration was gradually elevated in line with AECOPD severity scores. Additionally, serum legumain was closely associated with clinical characteristics. Linear regression analysis confirmed the positive relationships of serum legumain with COPD severity scores. Moreover, the poor prognoses were tracked in patients of AECOPD. Serum higher legumain at admission increased the risks of death and acute exacerbation during hospitalization.

Conclusion

Serum legumain at admission was positively correlated with the severity and adverse prognosis in AECOPD patients, indicating that legumain plays a vital role in the initiation and development of AECOPD. As a result, serum legumain can become a biomarker in the disease assessment and prognosis prediction for AECOPD.

Harnessing synergistic effects of MMP-2 Inhibition and bFGF to simultaneously preserve and vascularize cardiac extracellular matrix after myocardial infarction

Myocardial infarction (MI) leads to cardiac extracellular matrix (ECM) degradation and fibrosis, reducing heart function. Consequently, simultaneously addressing ECM degradation and inhibiting cardiac fibrosis is essential for preserving heart function and mitigating adverse remodeling. However, the preserved ECM becomes unstable if not vascularized, as its structure and composition undergo changes over time. ECM vascularization is crucial to improve cardiac function. Presently, there is no clinically approved therapy that can simultaneously preserve and vascularize the ECM, and inhibit cardiac fibrosis. Our study develops a drug delivery system aiming to achieve these goals. It includes the peptide CTTHWGFTLC (CTT), a specific MMP-2 inhibitor, and basic fibroblast growth factor (bFGF), a potent factor with pro-angiogenic and anti-fibrotic properties. An injectable hydrogel serves as the carrier, featuring a rapid gelation that allows for the substantial retention of drugs. Additionally, the hydrogel has the capability to scavenge upregulated reactive oxygen species (ROS), thereby reducing tissue inflammation. Our findings indicate that CTT and bFGF synergistically enhance endothelial cell migration and tube formation while inhibiting the differentiation of fibroblasts into myofibroblasts. Upon delivery into hearts, the system significantly decreases MMP-2 level, promotes angiogenesis, attenuates cardiac fibrosis, and alleviates inflammation, resulting in a noteworthy cardiac function improvement. STATEMENT OF SIGNIFICANCE: 1) This work addresses key challenges in cardiac repair after myocardial infarction (MI), including extracellular matrix (ECM) degradation, vascularization, and fibrosis. 2) We combined an MMP-2/9 inhibitor (CTT) with bFGF to prevent ECM degradation, enhance vascularization, and inhibit fibrosis, providing a comprehensive strategy to improve cardiac function. 3) An injectable hydrogel was developed with rapid gelation and mechanical properties similar to heart tissue, ensuring efficient drug retention and reducing tissue stress. 4) The hydrogel enabled controlled, spatiotemporal release of CTT to dynamically reduce MMP-2/9 activity, and gradually released bFGF to promote angiogenesis and inhibit fibrosis.

Association between high plasma levels of legumain and cardiovascular events in patients undergoing coronary angiography

Degradation of vascular extracellular matrix is important in atherosclerosis. Cysteine protease legumain is upregulated in atherosclerotic plaques. We recently reported that plasma legumain levels are high in patients with complex coronary lesions. This study investigated the association between legumain levels and cardiovascular events in 372 patients undergoing coronary angiography. Patients with acute coronary syndrome were excluded. Of the 372 patients, 225 had coronary artery disease (CAD). During a mean follow-up of 7.0 ± 4.3 years, cardiovascular events occured in 62 patients. Compared with 310 patients without events, 62 with events tended to have higher prevalence of complex lesions (15% vs. 10%). Notably, patients with events had higher legumain levels (median 5.51 vs. 4.90 ng/mL, P < 0.01) than those without events. A Kaplan-Meier analysis showed lower event-free survival in patients with legumain > 5.0 ng/mL than in those with ≤ 5.0 ng/mL (P < 0.01). In multivariate Cox regression analysis, legumain level was an independent predictor of cardiovascular events. The hazard ratio for legumain > 5.0 ng/mL for cardiovascular events was 2.18 (95%CI = 1.27-3.77, P < 0.01). Only among 225 patients with CAD, patients with events had higher legumain levels (5.49 vs. 4.73 ng/mL) than without events (P < 0.02). Legumain level was also a predictor of cardiovascular events in patients with CAD. Thus, high plasma legumain levels were associated with an increased risk of cardiovascular events in patients undergoing coronary angiography and those with stable CAD.

Legumain in cardiovascular diseases

Cardiovascular diseases (CVDs) are the leading cause of death worldwide, having become a global public health problem, so the pathophysiological mechanisms and therapeutic strategies of CVDs need further study. Legumain is a powerful enzyme that is widely distributed in mammals and plays an important role in a variety of biological processes. Recent research suggests that legumain is associated with the occurrence and progression of CVDs. In this review, we provide a comprehensive overview of legumain in the pathogenesis of CVDs. The role of legumain in CVDs, such as carotid atherosclerosis, pulmonary hypertension, coronary artery disease, peripheral arterial disease, aortic aneurysms and dissection, is discussed. The potential applications of legumain as a biomarker of these diseases are also explored. By understanding the role of legumain in the pathogenesis of CVDs, we aim to support new therapeutic strategies to prevent or treat these diseases.

Plasma legumain in familial hypercholesterolemia: associations with statin use and cardiovascular risk markers

Legumain is known to be regulated in atherosclerotic disease and may have both pro- and anti-atherogenic properties. The study aimed to explore legumain in individuals with familial hypercholesterolemia (FH), a population with increased cardiovascular risk. Plasma legumain was measured in 251 subjects with mostly genetically verified FH, of which 166 were adults (≥18 years) and 85 were children and young adults (<18 years) and compared to 96 normolipidemic healthy controls. Plasma legumain was significantly increased in the total FH population compared to controls (median 4.9 versus 3.3 pg/mL, respectively, p < 0.001), whereof adult subjects with FH using statins had higher levels compared to non-statin users (5.7 versus 3.9 pg/mL, respectively, p < 0.001). Children and young adults with FH (p = 0.67) did not have plasma legumain different from controls at the same age. Further, in FH subjects, legumain showed a positive association with apoB, and markers of inflammation and platelet activation (i.e. fibrinogen, NAP2 and RANTES). In the current study, we show that legumain is increased in adult subjects with FH using statins, whereas there was no difference in legumain among children and young adults with FH compared to controls. Legumain was further associated with cardiovascular risk markers in the FH population. However the role of legumain in regulation of cardiovascular risk in these individuals is still to be determined.

CD4+ T-Cell Legumain Deficiency Attenuates Hypertensive Damage via Preservation of TRAF6

BACKGROUND

T cells are central to the immune responses contributing to hypertension. LGMN (legumain) is highly expressed in T cells; however, its role in the pathogenesis of hypertension remains unclear.

METHODS

Peripheral blood samples were collected from patients with hypertension, and cluster of differentiation (CD)4+ T cells were sorted for gene expression and Western blotting analysis. TLGMNKO (T cell-specific LGMN-knockout) mice (Lgmnf/f/CD4Cre), regulatory T cell (Treg)-specific LGMN-knockout mice (Lgmnf/f/Foxp3YFP Cre), and RR-11a (LGMN inhibitor)-treated C57BL/6 mice were infused with Ang II (angiotensin II) or deoxycorticosterone acetate/salt to establish hypertensive animal models. Flow cytometry, 4-dimensional label-free proteomics, coimmunoprecipitation, Treg suppression, and in vivo Treg depletion or adoptive transfer were used to delineate the functional importance of T-cell LGMN in hypertension development.

RESULTS

LGMN mRNA expression was increased in CD4+ T cells isolated from hypertensive patients and mice, was positively correlated with both systolic and diastolic blood pressure, and was negatively correlated with serum IL (interleukin)-10 levels. TLGMNKO mice exhibited reduced Ang II-induced or deoxycorticosterone acetate/salt-induced hypertension and target organ damage relative to wild-type (WT) mice. Genetic and pharmacological inhibition of LGMN blocked Ang II-induced or deoxycorticosterone acetate/salt-induced immunoinhibitory Treg reduction in the kidneys and blood. Anti-CD25 antibody depletion of Tregs abolished the protective effects against Ang II-induced hypertension in TLGMNKO mice, and LGMN deletion in Tregs prevented Ang II-induced hypertension in mice. Mechanistically, endogenous LGMN impaired Treg differentiation and function by directly interacting with and facilitating the degradation of TRAF6 (tumor necrosis factor receptor-associated factor 6) via chaperone-mediated autophagy, thereby inhibiting NF-κB (nuclear factor kappa B) activation. Adoptive transfer of LGMN-deficient Tregs reversed Ang II-induced hypertension, whereas depletion of TRAF6 in LGMN-deficient Tregs blocked the protective effects.

CONCLUSIONS

LGMN deficiency in T cells prevents hypertension and its complications by promoting Treg differentiation and function. Specifically targeting LGMN in Tregs may be an innovative approach for hypertension treatment.

Relationship between Increased Plasma Levels of Legumain and Properties of Coronary Atherosclerotic Plaque

BACKGROUND

Many clinical studies have confirmed that legumain is closely related to atherosclerosis. Unfortunately, different conclusions have been reached, and analyses and studies on atherosclerotic plaque characteristics in patients with increased plasma levels of legumain are still lacking.

OBJECTIVES

This study aimed to investigate the correlation between legumain and coronary atherosclerotic plaque characteristics.

METHODS

A total of 81 patients with coronary atherosclerotic heart disease (CHD), including 43 patients with unstable angina (UA) and 38 patients with stable angina (SA), were screened by coronary angiography. Intravascular ultrasound (IVUS) was performed to evaluate the characteristics of coronary atherosclerotic plaques, and plasma legumain levels were also measured. Values of p < 0.05 were considered significant.

RESULTS

Legumain concentration was significantly higher in the two CHD subgroups than in the control group (all p<0.001). Legumain concentrations in the UA group were significantly higher than in the SA group (p=0.001). The plaque area, remodeling index (RI), and eccentricity index (EI) in the UA group were significantly higher than those in the SA group (p<0.001, p=0.001, p=0.001, respectively). There was a significant positive correlation between legumain levels and RI and EI in both UA and SA patients (all p<0.05).

CONCLUSIONS

High plasma levels of legumain were closely related to the occurrence and severity of CHD, and the lesions tended to be unstable. Legumain is expected to be a potential inflammatory biomarker for the diagnosis of CHD and the early identification of unstable coronary lesions.

Brain-Derived Neurotrophic Factor Precursor Contributes to a Proinflammatory Program in Monocytes/Macrophages After Acute Myocardial Infarction

Background The imbalance of monocyte/macrophage polarization toward the preferential proinflammatory phenotype and a lack of normal inflammation resolution are present in acute myocardial infarction (AMI). Our previous study showed that upregulation of brain-derived neurotrophic factor precursor (proBDNF) in M2-like monocytes may contribute to the proinflammatory response in the Stanford type-A acute aortic dissection. The present study aimed to investigate the role of proBDNF signaling in monocytes/macrophages in the progress of AMI. Methods and Results We observed the upregulation of proBDNF in the proinflammatory monocytes of patients with AMI. The upregulation of proBDNF was also observed in the circulating proinflammatory Ly6C^high monocytes and cardiac F4/80⁺CD86⁺ macrophages 3 days after AMI in a mice model. To neutralize proBDNF, the mice subjected to AMI were injected intraperitoneally with a monoclonal anti-proBDNF antibody. Echocardiography, 2,3,5-triphenyltetrazolium chloride staining, and positron emission tomography/computed tomography results demonstrate that monoclonal anti-proBDNF antibody treatment further impaired cardiac functions, increased infarct size, and exacerbated the proinflammatory state. Moreover, the level of proinflammatory Ly6C^high in the blood and F4/80⁺CD86⁺ in the heart was further increased in monoclonal anti-proBDNF antibody mice. RNA sequencing revealed that matrix metalloprotease-9 protein level was dramatically increased, along with the activated proinflammatory-related cytokines. Matrix metalloprotease-9 inhibitor treatment attenuated the deteriorated effect of monoclonal anti-proBDNF antibody on cardiac function and infarct areas. Conclusions Our study shows that endogenous proBDNF in monocytes/macrophages may exert protective roles in cardiac remodeling after AMI by regulating matrix metalloprotease-9 activity.

The Mammalian Cysteine Protease Legumain in Health and Disease

The cysteine protease legumain (also known as asparaginyl endopeptidase or δ-secretase) is the only known mammalian asparaginyl endopeptidase and is primarily localized to the endolysosomal system, although it is also found extracellularly as a secreted protein. Legumain is involved in the regulation of diverse biological processes and tissue homeostasis, and in the pathogenesis of various malignant and nonmalignant diseases. In addition to its proteolytic activity that leads to the degradation or activation of different substrates, legumain has also been shown to have a nonproteolytic ligase function. This review summarizes the current knowledge about legumain functions in health and disease, including kidney homeostasis, hematopoietic homeostasis, bone remodeling, cardiovascular and cerebrovascular diseases, fibrosis, aging and senescence, neurodegenerative diseases and cancer. In addition, this review addresses the effects of some marketed drugs on legumain. Expanding our knowledge on legumain will delineate the importance of this enzyme in regulating physiological processes and disease conditions.

Legumain Is an Endogenous Modulator of Integrin αvβ3 Triggering Vascular Degeneration, Dissection, and Rupture

BACKGROUND

The development of thoracic aortic dissection (TAD) is closely related to extracellular matrix degradation and vascular smooth muscle cell (VSMC) transformation from contractile to synthetic type. LGMN (legumain) degrades extracellular matrix components directly or by activating downstream signals. The role of LGMN in VSMC differentiation and the occurrence of TAD remains elusive.

METHODS

Microarray datasets concerning vascular dissection or aneurysm were downloaded from the Gene Expression Omnibus database to screen differentially expressed genes. Four-week-old male Lgmn knockout mice (Lgmn^-/-), macrophage-specific Lgmn knockout mice (Lgmn^F/F;LysM^Cre), and RR-11a-treated C57BL/6 mice were given BAPN (β-aminopropionitrile monofumarate; 1 g/kg/d) in drinking water for 4 weeks for TAD modeling. RNA sequencing analysis was performed to recapitulate transcriptome profile changes. Cell interaction was examined in macrophage and VSMC coculture system. The reciprocity of macrophage-derived LGMN with integrin αvβ3 in VSMCs was tested by coimmunoprecipitation assay and colocalization analyses.

RESULTS

Microarray datasets from the Gene Expression Omnibus database indicated upregulated LGMN in aorta from patients with TAD and mice with angiotensin II-induced AAA. Elevated LGMN was evidenced in aorta and sera from patients with TAD and mice with BAPN-induced TAD. BAPN-induced TAD progression was significantly ameliorated in Lgmn-deficient or inhibited mice. Macrophage-specific deletion of Lgmn alleviated BAPN-induced extracellular matrix degradation. Unbiased profiler polymerase chain reaction array and Gene Ontology analysis displayed that LGMN regulated VSMC phenotype transformation. Macrophage-specific deletion of Lgmn ameliorated VSMC phenotypic switch in BAPN-treated mice. Macrophage-derived LGMN inhibited VSMC differentiation in vitro as assessed by macrophages and the VSMC coculture system. Macrophage-derived LGMN bound to integrin αvβ3 in VSMCs and blocked integrin αvβ3, thereby attenuating Rho GTPase activation, downregulating VSMC differentiation markers and eventually exacerbating TAD development. ROCK (Rho kinase) inhibitor Y-27632 reversed the protective role of LGMN depletion in vascular dissection.

CONCLUSIONS

LGMN signaling may be a novel target for the prevention and treatment of TAD.

Progress of Pathogenesis in Pediatric Multifocal Atrial Tachycardia

Multifocal atrial tachycardia (MAT) is defined as irregular P-P, R-R, and P-R intervals, isoelectric baseline between P waves, and ventricular rate over 100 beats/min. Although the prognosis of pediatric MAT in most patients is favorable, adverse outcomes of MAT have been reported, such as cardiogenic death (3%), respiratory failure (6%), or persistent arrhythmia (7%), due to delayed diagnosis and poorly controlled MAT. Previous studies demonstrated that pediatric MAT is associated with multiple enhanced automatic lesions located in the atrium or abnormal automaticity of a single lesion located in the pulmonary veins via multiple pathways to trigger electrical activity. Recent studies indicated that pediatric MAT is associated with the formation of a re-entry loop, abnormal automaticity, and triggering activity. The occurrence of pediatric MAT is affected by gestational disease, congenital heart disease, post-cardiac surgery, pulmonary hypertension, and infectious diseases, which promote MAT via inflammation, redistribution of the autonomic nervous system, and abnormal ion channels. However, the pathogenesis of MAT needs to be explored. This review is aimed to summarize and analyze the pathogenesis in pediatric MAT.

Serum Legumain Is Associated with Peripheral Artery Disease in Patients with Type 2 Diabetes

BACKGROUND

Legumain is related to carotid atherosclerotic plaques and may be a new biomarker of carotid atherosclerosis. However, the association between legumain and peripheral artery disease (PAD) of lower extremity has been less studied. This study is aimed at exploring the potential link between legumain and PAD in patients with type 2 diabetes mellitus (T2DM).

METHODS

A cross-sectional study was conducted on 483 hospitalized T2DM patients. The serum legumain level was measured by a sandwich enzyme-linked immunosorbent assay. PAD was evaluated by color Doppler sonography. The association between legumain and PAD was tested by logistic regression. The predictive power of legumain for PAD was evaluated with the receiver-operating-characteristic (ROC) curve.

RESULTS

Overall, 201 (41.6%) patients suffered from PAD. Patients with PAD had significantly higher serum legumain level than those without PAD [11.9 (6.3, 17.9) μg/L vs. 7.6 (3.2, 14.2) μg/L, p < 0.001]. Logistic regression showed that a higher serum legumain level was independently associated with a greater risk of PAD in T2DM patients [adjusted odds ratio (aOR): 1.03; 95% confidence interval (CI): 1.01-1.06]. The area under the ROC curve was 0.634 (95% CI, 0.585 to 0.684).

CONCLUSION

High serum legumain level was significantly correlated with an increased risk of PAD in T2DM patients.