Overview of multifunctional cysteinyl cathepsins in atherosclerosis-based cardiovascular disease: from insights into molecular functions to clinical implications

Dipeptidyl peptidase-4 deficiency prevents chronic stress-induced cardiac remodeling and dysfunction in mice

Exposure to chronic psychosocial stress is a risk factor for metabolic cardiovascular disorders. Dipeptidyl peptidase-4 (DPP-4) plays essential roles in human pathobiology, and we recently showed that DPP-4 levels are increased by chronic stress in murine models. We here investigated the role of DPP-4 in stress-related cardiac injury and dysfunction in mice, focusing on oxidative stress and cardiac apoptosis. Male mice were randomly assigned to non-stress and two-week immobilized-stress groups for biological and morphological studies. On day 14 post-stress, stress had increased blood pressure, heart weight, cardiac myocyte size, and interstitial fibrosis, impaired cardiac diastolic function, and increased plasma levels of DPP-4 and glucose. The stressed mice also had increased levels of monocyte chemoattractant protein-1, inteleukin-6, gp91phox, matrix metalloproteinase-2 (MMP-2), MMP-9, tissue inhibitor of MMP-1/-2, caspase-8, and Bax genes and/or proteins and lowered levels of Bcl-2, p-Akt, and endothelial nitric oxide synthase (eNOS) proteins. DPP-4 inhibition by either a genetic or pharmacological approach ameliorated the stress-induced targeted molecular and morphological changes. In vitro, DPP-4 inhibition also mitigated the alterations in the targeted caspase-8, Bcl-2, eNOS, and p-Akt proteins in H9c2 cardiomyocytes in response to H2O2. DPP-4 inhibition appeared to improve the stress-induced cardiac injury and dysfunction in mice, possibly via the improvement of oxidative stress and apoptosis, suggesting that DPP-4 could become a novel therapeutic target for chronic psychological stress-related metabolic cardiovascular disorders.

Vascular Extracellular Matrix in Atherosclerosis

The extracellular matrix (ECM) plays a central role in the structural integrity and functionality of the cardiovascular system. Moreover, the ECM is involved in atherosclerotic plaque formation and stability. In fact, ECM remodeling affects plaque stability, cellular migration, and inflammatory responses. Collagens, fibronectin, laminin, elastin, and proteoglycans are crucial proteins during atherosclerosis development. This dynamic remodeling is driven by proteolytic enzymes such as matrix metalloproteinases (MMPs), cathepsins, and serine proteases. Exploring and investigating ECM dynamics is an important step to designing innovative therapeutic strategies targeting ECM remodeling mechanisms, thus offering significant advantages in the management of cardiovascular diseases. This review illustrates the structure and role of vascular ECM, presenting a new perspective on ECM remodeling and its potential as a therapeutic target in atherosclerosis treatments.

Potential mechanistic linkages of Naoluotong granules on the remission of atherosclerosis by multidimensional analysis

Background

Naoluotong granules (NLTGs) are a medicinal formula derived from traditional Chinese medicine, which have been demonstrated to be effective in slowing down the progression of atherosclerosis (AS) through clinical practice and animal experiments. By means of multidimensional analysis, the relevant mechanism of NLTGs in delaying the progression of atherosclerosis was studied, which is conducive to its widespread adoption.

Materials and methods

In this study, data from network pharmacology and GEO database were comprehensively analysed to identify differentially expressed core cluster genes (DECCGs). Subsequently, multilevel analyses were applied to investigate the potential mechanistic linkages and causal associations of NLTGs in delaying atherosclerosis.

Results

Eight DECCGs positively correlated with atherosclerosis risk were identified, with Polygonatum sibiricum (Huangjing), Hirudo nipponica (Shuizhi), and Ligusticum chuanxiong (Chuanxiong) as the core drug pairs. Senkyunone, Wallichilide, and Aurantiamide were the core components. The prediction model using principal components (PC) demonstrated high accuracy and clinical relevance. The mechanisms were strongly associated with the PI3K-Akt signaling pathway, as well as the polarization of Macrophages M0 and the balanced regulation of M1/M2 types. Ultimately, elevated expression of CTSB was causally associated with increased risk of cerebral atherosclerosis (OR = 1.313; 95 % CI = 1.024-1.685; P = 0.032).

Conclusions

Employing multidimensional analysis, we identified core pairs, components, and targets of NLTGs. Our multilevel analysis of DECCGs enabled the construction of a clinical prediction model, highlighting CTSB as a risk target for AS. Additionally, we unveiled NLTGs' mechanisms closely tied to the polarization and regulation of macrophage, facilitating subsequent research and application.

Cathepsin B in cardiovascular disease: Underlying mechanisms and therapeutic strategies

Cathepsin B (CTSB) is a member of the cysteine protease family, primarily responsible for degrading unnecessary organelles and proteins within the acidic milieu of lysosomes to facilitate recycling. Recent research has revealed that CTSB plays a multifaceted role beyond its function as a proteolytic enzyme in lysosomes. Importantly, recent data suggest that CTSB has significant impacts on different cardiac pathological conditions, such as atherosclerosis (AS), myocardial infarction, hypertension, heart failure and cardiomyopathy. Especially in the context of AS, preclinical models and clinical sample imaging data indicate that the cathepsin activity-based probe can reliably image CTSB activity in foam cells and atherosclerotic plaques; concurrently, it allows synchronous diagnostic and therapeutic interventions. However, our knowledge of CTSB in cardiovascular disease is still in the early stage. This paper aims to provide a comprehensive review of the significance of CTSB in cardiovascular physiology and pathology, with the objective of laying a theoretical groundwork for the development of drugs targeting CTSB.

Histone deacetylase 6 controls cardiac fibrosis and remodelling through the modulation of TGF-β1/Smad2/3 signalling in post-infarction mice

Histone deacetylase 6 (HDAC6) belongs to the class IIb group of the histone deacetylase family, which participates in remodelling of various tissues. Herein, we sought to examine the potential regulation of HDAC6 in cardiac remodelling post-infarction. Experimental myocardial infarction (MI) was created in HDAC6-deficient (HDAC6-/-) mice and wild-type (HADC6+/+) by left coronary artery ligation. At days 0 and 14 post-MI, we evaluated cardiac function, morphology and molecular endpoints of repair and remodelling. At day 14 after surgery, the ischemic myocardium had increased levels of HADC6 gene and protein of post-MI mice compared to the non-ischemic myocardium of control mice. As compared with HDAC6-/--MI mice, HADC6 deletion markedly improved infarct size and cardiac fibrosis as well as impaired left ventricular ejection fraction and left ventricular fraction shortening. At the molecular levels, HDAC6-/- resulted in a significant reduction in the levels of the transforming growth factor-beta 1 (TGF-β1), phosphor-Smad-2/3, collagen I and collagen III proteins and/or in the ischemic cardiac tissues. All of these beneficial effects were reproduced by a pharmacological inhibition of HADC6 in vivo. In vitro, hypoxic stress increased the expressions of HADC6 and collagen I and III gene; these alterations were significantly prevented by the HADC6 silencing and TubA loading. These findings indicated that HADC6 deficiency resists ischemic injury by a reduction of TGF-β1/Smad2/3 signalling activation, leading to decreased extracellular matrix production, which reduces cardiac fibrosis and dysfunction, providing a potential molecular target in the treatment of patients with MI.

Integrative multi-omics analysis reveals cellular and molecular insights into primary Sjögren's syndrome

Objective

This study aims to comprehensively analyze genomic, transcriptomic, proteomic, and single-cell sequencing data to unravel the molecular basis of primary Sjögren's syndrome (pSS) and explore potential therapeutic targets.

Methods

Mendelian randomization and single-cell RNA sequencing were employed to analyze pSS data. Differentially expressed genes specific to different blood cell types were identified. Integration of multiomics data facilitated the exploration of genetic regulatory relationships.

Results

The analysis revealed distinct cell clusters representing various immune cell subsets. Several genes, including cathepsin S (CTSS) and glutathione S-transferase omega 1 (GSTO1), were identified as potential biomarkers and therapeutic targets for pSS. Diagnostic utility analysis demonstrated the discriminatory power of CTSS and GSTO1 in distinguishing pSS patients from healthy controls.

Conclusion

The findings highlight the importance of integrating multiomics data for understanding pSS pathogenesis. CTSS and GSTO1 show promise as diagnostic biomarkers and potential therapeutic targets for pSS. Further investigations are warranted to elucidate the underlying mechanisms and develop targeted therapies for this complex autoimmune disease.

The multifaceted role of proteases and modern analytical methods for investigation of their catalytic activity

We discuss the diverse functions of proteases in the context of their biotechnological and medical significance, as well as analytical approaches used to determine the functional activity of these enzymes. An insight into modern approaches to studying the kinetics and specificity of proteases, based on spectral (absorption, fluorescence), mass spectrometric, immunological, calorimetric, and electrochemical methods of analysis is given. We also examine in detail electrochemical systems for determining the activity and specificity of proteases. Particular attention is given to exploring innovative electrochemical systems based on the detection of the electrochemical oxidation signal of amino acid residues, thereby eliminating the need for extra redox labels in the process of peptide synthesis. In the review, we highlight the main prospects for the further development of electrochemical systems for the study of biotechnologically and medically significant proteases, which will enable the miniaturization of the analytical process for determining the catalytic activity of these enzymes.

Dipeptidyl peptidase-4 disturbs adipocyte differentiation via the negative regulation of the glucagon-like peptide-1/adiponectin-cathepsin K axis in mice under chronic stress conditions

Exposure to chronic psychosocial stress is a risk factor for metabolic disorders. Because dipeptidyl peptidase-4 (DPP4) and cysteinyl cathepsin K (CTSK) play important roles in human pathobiology, we investigated the role(s) of DPP4 in stress-related adipocyte differentiation, with a focus on the glucagon-like peptide-1 (GLP-1)/adiponectin-CTSK axis in vivo and in vitro. Plasma and inguinal adipose tissue from non-stress wild-type (DPP4+/+), DPP4-knockout (DPP4-/-) and CTSK-knockout (CTSK-/-) mice, and stressed DPP4+/+, DPP4-/-, CTSK-/-, and DPP4+/+ mice underwent stress exposure plus GLP-1 receptor agonist exenatide loading for 2 weeks and then were analyzed for stress-related biological and/or morphological alterations. On day 14 under chronic stress, stress decreased the weights of adipose tissue and resulted in harmful changes in the plasma levels of DPP4, GLP-1, CTSK, adiponectin, and tumor necrosis factor-α proteins and the adipose tissue levels of CTSK, preadipocyte factor-1, fatty acid binding protein-4, CCAAT/enhancer binding protein-α, GLP-1 receptor, peroxisome proliferator-activated receptor-γ, perilipin2, secreted frizzled-related protein-4, Wnt5α, Wnt11 and β-catenin proteins and/or mRNAs as well as macrophage infiltration in adipose tissue; these changes were rectified by DPP4 deletion. GLP-1 receptor activation and CTSK deletion mimic the adipose benefits of DPP4 deficiency. In vitro, CTSK silencing and overexpression respectively prevented and facilitated stress serum and oxidative stress-induced adipocyte differentiation accompanied with changes in the levels of pref-1, C/EBP-α, and PPAR-γ in 3T3-L1 cells. Thus, these findings indicated that increased DPP4 plays an essential role in stress-related adipocyte differentiation, possibly through a negative regulation of GLP-1/adiponectin-CTSK axis activation in mice under chronic stress conditions.

Cathepsin K deficiency prevented stress-related thrombosis in a mouse FeCl3 model

BACKGROUND

Exposure to chronic psychological stress (CPS) is a risk factor for thrombotic cardiocerebrovascular diseases (CCVDs). The expression and activity of the cysteine cathepsin K (CTSK) are upregulated in stressed cardiovascular tissues, and we investigated whether CTSK is involved in chronic stress-related thrombosis, focusing on stress serum-induced endothelial apoptosis.

METHODS AND RESULTS

Eight-week-old wild-type male mice (CTSK+/+) randomly divided to non-stress and 3-week restraint stress groups received a left carotid artery iron chloride3 (FeCl3)-induced thrombosis injury for biological and morphological evaluations at specific timepoints. On day 21 post-stress/injury, the stress had enhanced the arterial thrombi weights and lengths, in addition to harmful alterations of plasma ADAMTS13, von Willebrand factor, and plasminogen activation inhibitor-1, plus injured-artery endothelial loss and CTSK protein/mRNA expression. The stressed CTSK+/+ mice had increased levels of injured arterial cleaved Notch1, Hes1, cleaved caspase8, matrix metalloproteinase-9/-2, angiotensin type 1 receptor, galactin3, p16IN4A, p22phox, gp91phox, intracellular adhesion molecule-1, TNF-α, MCP-1, and TLR-4 proteins and/or genes. Pharmacological and genetic inhibitions of CTSK ameliorated the stress-induced thrombus formation and the observed molecular and morphological changes. In cultured HUVECs, CTSK overexpression and silencing respectively increased and mitigated stressed-serum- and H2O2-induced apoptosis associated with apoptosis-related protein changes. Recombinant human CTSK degraded γ-secretase substrate in a dose-dependent manor and activated Notch1 and Hes1 expression upregulation.

CONCLUSIONS

CTSK appeared to contribute to stress-related thrombosis in mice subjected to FeCl3 stress, possibly via the modulation of vascular inflammation, oxidative production and apoptosis, suggesting that CTSK could be an effective therapeutic target for CPS-related thrombotic events in patients with CCVDs.

Unravelling the role of cathepsins in cardiovascular diseases

Lysosomal cathepsins as a regulatory medium have been assessed as potential therapeutic targets for the treatment of various cardiac diseases such as abdominal aortic aneurysm, hypertension, cardiomyopathy, coronary heart disease, atherosclerosis, etc. They are ubiquitous lysosomal proteases with papain-like folded protein structures that are involved in a variety of physiological processes, such as the digestion of proteins, activation of pro-inflammatory molecules, degradation of extracellular matrix components, and maturation of peptide hormones. Cathepsins are classified into three major groups: cysteine cathepsins, aspartic cathepsins, and serine-threonine cathepsins. Each of these groups is further divided into subgroups based on their substrate specificity, structural characteristics, and biochemical properties. Several studies suggest that cathepsins control the degradation of ECM components such as collagen and elastin fibres. These enzymes are highly expressed in macrophages and inflammatory cells, and their upregulation has been demonstrated to be critical in the progression of atherosclerotic lesions. Additionally, increased cathepsin activity has been linked to increased vascular inflammation and oxidative stress, both of which are associated with CVDs. Specifically, the inhibition of cathepsins may reduce the release of pro-apoptotic mediators such as caspase-3 and PARP-1, which are thought to contribute to plaque instability. The potential of cathepsins as biomarkers and therapeutic targets has also been supported by the identification of potential cathepsin inhibitors, which could be used to modulate the activities of cathepsins in a range of diseases. This review shall familiarise the readers with the role of cysteinyl cathepsins and their inhibitors in the pathogenesis of cardiovascular diseases.

Leveraging the transcriptome to further our understanding of GWAS findings: eQTLs associated with genes related to LDL and LDL subclasses, in a cohort of African Americans

Background: GWAS discoveries often pose a significant challenge in terms of understanding their underlying mechanisms. Further research, such as an integration with expression quantitative trait locus (eQTL) analyses, are required to decipher the mechanisms connecting GWAS variants to phenotypes. An eQTL analysis was conducted on genes associated with low-density lipoprotein (LDL) cholesterol and its subclasses, with the aim of pinpointing genetic variants previously implicated in GWAS studies focused on lipid-related traits. Notably, the study cohort consisted of African Americans, a population characterized by a heightened prevalence of hypercholesterolemia. Methods: A comprehensive differential expression (DE) analysis was undertaken, with a dataset of 17,948 protein-coding mRNA transcripts extracted from the whole-blood transcriptomes of 416 samples to identify mRNA transcripts associated with LDL, with further granularity delineated between small LDL and large LDL subclasses. Subsequently, eQTL analysis was conducted with a subset of 242 samples for which whole-genome sequencing data were available to identify single-nucleotide polymorphisms (SNPs) associated with the LDL-related mRNA transcripts. Lastly, plausible functional connections were established between the identified eQTLs and genetic variants reported in the GWAS catalogue. Results: DE analysis revealed 1,048, 284, and 94 mRNA transcripts that exhibited differential expression in response to LDL, small LDL, and large LDL, respectively. The eQTL analysis identified a total of 9,950 significant SNP-mRNA associations involving 6,955 SNPs including a subset 101 SNPs previously documented in GWAS of LDL and LDL-related traits. Conclusion: Through comprehensive differential expression analysis, we identified numerous mRNA transcripts responsive to LDL, small LDL, and large LDL. Subsequent eQTL analysis revealed a rich landscape of eQTL-mRNA associations, including a subset of eQTL reported in GWAS studies of LDL and related traits. The study serves as a testament to the important role of integrative genomics in unraveling the enigmatic GWAS relationships between genetic variants and the complex fabric of human traits and diseases.

Vascular calcification and cellular signaling pathways as potential therapeutic targets

Increased vascular calcification (VC) is observed in patients with cardiovascular diseases such as atherosclerosis, diabetes, and chronic kidney disease. VC is divided into three types according to its location: intimal, medial, and valvular. Various cellular signaling pathways are associated with VC, including the Wnt, mitogen-activated protein kinase, phosphatidylinositol-3 kinase/Akt, cyclic nucleotide-dependent protein kinase, protein kinase C, calcium/calmodulin-dependent kinase II, adenosine monophosphate-activated protein kinase/mammalian target of rapamycin, Ras homologous GTPase, apoptosis, Notch, and cytokine signaling pathways. In this review, we discuss the literature concerning the key cellular signaling pathways associated with VC and their role as potential therapeutic targets. Inhibitors to these pathways represent good candidates for use as potential therapeutic agents for the prevention and treatment of VC.

Serum and Synovial Levels of Cathepsin G and Cathepsin K in Patients with Psoriatic Arthritis and Their Correlation with Disease Activity Indices

This retrospective case-control study examined the relationship between the serum and synovial levels of cathepsin G (CatG) and cathepsin K (CatK) in patients with psoriatic arthritis (PsA) and their association with disease activity. Methods: This case-control study involved 156 PsA patients, 50 patients with gonarthrosis (GoA), and 30 healthy controls. The target parameters were measured using enzyme-linked immunosorbent assay (ELISA) kits. The serum levels of CatG and CatK were found to be significantly higher in PsA patients compared to both control groups (p < 0.001). Moreover, they could distinguish PsA patients from healthy controls with 100% accuracy. Synovial fluid CatG and CatK were positively associated with the following indicators of disease activity: the VAS (rs = 0.362, rs = 0.391); the DAPSA (rs = 0.191, rs = 0.182); and the mCPDAI (rs = 0.378, rs = 0.313). Our results suggest that serum and synovial fluid CatG and CatK levels could serve as biomarkers for PsA. In PsA patients with synovial fluid crystals, elevated synovial CatG levels demonstrated a sensitivity of 89.54% and a specificity of 86.00% in distinguishing them from PsA patients without crystals. Similarly, elevated synovial CatK levels had a sensitivity of 93.67% and a specificity of 94.34% for distinguishing PsA patients with synovial fluid crystals from those without. Furthermore, the synovial fluid levels of both CatG and CatK showed positive associations with key indicators of disease activity, including the visual analog scale (VAS) (rs = 0.362, rs = 0.391), the disease activity in psoriatic arthritis (DAPSA) (rs = 0.191, rs = 0.182), and the modified composite psoriatic disease activity index (mCPDAI) (rs = 0.378, rs = 0.313). In conclusion, our findings suggest that the serum and synovial fluid levels of CatG and CatK hold promise as potential biomarkers for assessing disease activity in psoriatic arthritis.