Discovery of novel biomarkers for atherosclerotic aortic aneurysm through proteomics-based assessment of disease progression

Biomechanical dysregulation of SGK-1 dependent aortic pathologic markers in hypertension

Introduction

In hypertension (HTN), biomechanical stress may drive matrix remodeling through dysfunctional VSMC activity. Prior evidence has indicated VSMC tension-induced signaling through the serum and glucocorticoid inducible kinase-1 (SGK-1) can impact cytokine abundance. Here, we hypothesize that SGK-1 impacts production of additional aortic pathologic markers (APMs) representing VSMC dysfunction in HTN.

Methods

Aortic VSMC expression of APMs was quantified by QPCR in cyclic biaxial stretch (Stretch) +/- AngiotensinII (AngII). APMs were selected to represent VSMC dedifferentiated transcriptional activity, specifically Interleukin-6 (IL-6), Cathepsin S (CtsS), Cystatin C (CysC), Osteoprotegerin (OPG), and Tenascin C (TNC). To further assess the effect of tension alone, abdominal aortic rings from C57Bl/6 WT mice were held in a myograph at experimentally derived optimal tension (OT) or OT + 30% +/-AngII. Dependence on SGK-1 was assessed by treating with EMD638683 (SGK-1 inhibitor) and APMs were measured by QPCR. Then, WT and smooth muscle cell specific SGK-1 heterozygous knockout (SMC-SGK-1KO+/-) mice had AngII-induced HTN. Systolic blood pressure and mechanical stress parameters were assessed on Day 0 and Day 21. Plasma was analyzed by ELISA to quantify APMs. Statistical analysis was performed by ANOVA.

Results

In cultured aortic VSMCs, expression of all APMs was increased in response to biomechanical stimuli (Stretch +/-AngII,). Integrating the matrix contribution to signal transduction in the aortic rings led to IL-6 and CysC demonstrating SGK-1 dependence in response to elevated tension and interactive effect with concurrent AngII stimulation. CtsS and TNC, on the other hand, primarily responded to AngII, and OPG expression was unaffected in aortic ring experimentation. Both mouse strains had >30% increase in blood pressure with AngII infusion, reduced aortic distensibility and increased PPV, indicating increased aortic stiffness. In WT + AngII mice, IL-6, CtsS, CysC, and TNC plasma levels were significantly elevated, but these APMs were unaffected by HTN in the SMC-SGK-1KO+/- +AngII mice, suggesting SGK-1 plays a major role in VSMC biomechanical signaling to promote dysfunctional production of selected APMs.

Conclusion

In HTN, changes in the plasma levels of markers associated with aortic matrix homeostasis can reflect remodeling driven by mechanobiologic signaling in dysfunctional VSMCs, potentially through the activity of SGK-1. Further defining these pathways may identify therapeutic targets to reduce cardiovascular morbidity and mortality.

Tissue and plasma proteomic profiling indicates AHSG as a potential biomarker for ascending thoracic aortic aneurysms

BACKGROUND

Thoracic Aortic Aneurysms (TAAs) develop asymptomatically and are characterized by dilatation of the aorta. This is considered a life-threatening vascular disorder due to the risk of aortic dissection and rupture. There is an urgent need to identify blood-borne biomarkers for the early detection of TAA. The goal of the present study was to identify potential protein biomarkers associated with TAAs, using proteomic analysis of aortic tissue and plasma samples.

METHODS

Extracted proteins from 14 aneurysmal and 12 non-aneurysmal thoracic aortic tissue specimens as well as plasma samples from six TAA patients collected pre-and postoperatively and six healthy controls (HC), were analyzed by liquid chromatography-tandem mass spectrometry. Proteomic data were further processed and following filtering criteria, one protein was selected for verification and validation in a larger cohort of patients and controls using a targeted quantitative proteomic approach and enzyme-linked immunosorbent assay, respectively.

RESULTS

A total of 1593 and 363 differentially expressed proteins were identified in tissue and plasma samples, respectively. Pathway enrichment analysis on the differentially expressed proteins revealed a number of dysregulated molecular pathways that might be implicated in aneurysm pathology including complement and coagulation cascades, focal adhesion, and extracellular matrix receptor interaction pathways. Alpha-2-HS glycoprotein (AHSG) was selected for further verification in 36 TAA and 21 HC plasma samples using targeted quantitative proteomic approach. The results showed a significantly decreased concentration of AHSG (p = 0.0002) in the preoperative plasma samples compared with HC samples. Further analyses using a larger validation dataset revealed that AHSG protein levels were significantly lower (p = 0.03) compared with HC. Logistic regression analysis on the validation dataset revealed males, advanced age, hypertension and hyperlipidaemia as significant risk factors for TAA.

CONCLUSION

AHSG concentrations distinguish plasma samples derived from TAA patients and controls. The findings of this study suggest that AHSG may be a potential biomarker for TAA that could lead to better diagnostic capabilities.

Emerging computational paradigms to address the complex role of gut microbial metabolism in cardiovascular diseases

The human gut microbiota and its associated perturbations are implicated in a variety of cardiovascular diseases (CVDs). There is evidence that the structure and metabolic composition of the gut microbiome and some of its metabolites have mechanistic associations with several CVDs. Nevertheless, there is a need to unravel metabolic behavior and underlying mechanisms of microbiome-host interactions. This need is even more highlighted when considering that microbiome-secreted metabolites contributing to CVDs are the subject of intensive research to develop new prevention and therapeutic techniques. In addition to the application of high-throughput data used in microbiome-related studies, advanced computational tools enable us to integrate omics into different mathematical models, including constraint-based models, dynamic models, agent-based models, and machine learning tools, to build a holistic picture of metabolic pathological mechanisms. In this article, we aim to review and introduce state-of-the-art mathematical models and computational approaches addressing the link between the microbiome and CVDs.

Thrombospondins in human aortic aneurysms

Thrombospondins are a family of matricellular proteins with a multimeric structure that is known to be involved in several biological and pathological processes. Their relationship with vascular disorders has raised special interest recently. Aortic aneurysms are related to the impairment of vascular remodeling, in which extracellular matrix proteins seem to play an important role. Thus, research in thrombospondins, and their potential role in aneurysm development is progressively gaining importance. Nevertheless, studies showing thrombospondin dysregulation in human samples are still scarce. Although studies performed in vitro and in vivo models are essential to understand the molecular mechanisms and pathways underlying the disorder, descriptive studies in human samples are also necessary to ascertain their real value as biomarkers and/or novel therapeutic targets. The present article reviews the latest findings regarding the role of thrombospondins in aortic aneurysm development, paying particular attention to the studies performed in human samples.

Prognostic impact of tumor-specific insulin-like growth factor binding protein 7 (IGFBP7) levels in breast cancer: a prospective cohort study

The prognostic impact of insulin-like growth factor binding protein 7 (IGFBP7) in breast cancer is unclear. Host factors, including lifestyle, anthropometry and metabolic profile, might influence tumor-specific IGFBP7. This study aimed to investigate whether IGFBP7 levels and messenger ribonucleic acid (mRNA) expression are associated with the patient and tumor characteristics and prognosis in breast cancer. Patients with primary breast cancer in Lund, Sweden, were included preoperatively in the study between 2002 and 2012 (n = 1018). Tumor-specific IGFBP7 protein levels were evaluated with immunohistochemistry using tissue microarrays in tumors from 878 patients. IGFBP7 mRNA expression and its corresponding clinical data were obtained from The Cancer Genome Atlas and analyzed for 809 patients. Tumor-specific IGFBP7 protein levels were categorized based on Histo 300 scores into IGFBP7^low (6.2%), IGFBP7^intermediate (75.7%) and IGFBP7^high (18.1%). Both low IGFBP7 protein levels and mRNA expression were associated with less aggressive tumor characteristics. Overall, IGFBP7^low conferred low recurrence risk. The prognostic impact of IGFBP7^high varied according to any alcohol consumption and tamoxifen treatment. IGFBP7^high was associated with low recurrence risk in alcohol consumers but high recurrence risk in alcohol abstainers (P_interaction= 0.039). Moreover, the combination of IGFBP7^high and estrogen receptor-positive tumors was associated with low recurrence risk only in tamoxifen-treated patients (P_interaction= 0.029). To conclude, IGFBP7^low might be a good, independent prognosticator in breast cancer. The prognostic impact of IGFBP7^high depends on host factors and treatment. IGFBP7 merits further investigation to confirm whether it could be a suitable biomarker for treatment selection.

In the balance: how do thrombospondins contribute to the cellular pathophysiology of cardiovascular disease?

Thrombospondins (TSPs) are multidomain, secreted proteins that associate with cell surfaces and extracellular matrix. In mammals, there is a large body of data on functional roles of various TSP family members in cardiovascular disease (CVD), including stroke, cardiac remodeling and fibrosis, atherosclerosis, and aortic aneurysms. Coding single nucleotide polymorphisms (SNPs) of TSP1 or TSP4 are also associated with increased risk of several forms of CVD. Whereas interactions and functional effects of TSPs on a variety of cell types have been studied extensively, the molecular and cellular basis for the differential effects of the SNPs remains under investigation. Here, we provide an integrative review on TSPs, their roles in CVD and cardiovascular cell physiology, and known properties and mechanisms of TSP SNPs relevant to CVD. In considering recent expansions to knowledge of the fundamental cellular roles and mechanisms of TSPs, as well as the effects of wild-type and variant TSPs on cells of the cardiovascular system, we aim to highlight knowledge gaps and areas for future research or of translational potential.

Multi-omics approaches for revealing the complexity of cardiovascular disease

The development and progression of cardiovascular disease (CVD) can mainly be attributed to the narrowing of blood vessels caused by atherosclerosis and thrombosis, which induces organ damage that will result in end-organ dysfunction characterized by events such as myocardial infarction or stroke. It is also essential to consider other contributory factors to CVD, including cardiac remodelling caused by cardiomyopathies and co-morbidities with other diseases such as chronic kidney disease. Besides, there is a growing amount of evidence linking the gut microbiota to CVD through several metabolic pathways. Hence, it is of utmost importance to decipher the underlying molecular mechanisms associated with these disease states to elucidate the development and progression of CVD. A wide array of systems biology approaches incorporating multi-omics data have emerged as an invaluable tool in establishing alterations in specific cell types and identifying modifications in signalling events that promote disease development. Here, we review recent studies that apply multi-omics approaches to further understand the underlying causes of CVD and provide possible treatment strategies by identifying novel drug targets and biomarkers. We also discuss very recent advances in gut microbiota research with an emphasis on how diet and microbial composition can impact the development of CVD. Finally, we present various biological network analyses and other independent studies that have been employed for providing mechanistic explanation and developing treatment strategies for end-stage CVD, namely myocardial infarction and stroke.

Circulating Biomarkers for the Prediction of Abdominal Aortic Aneurysm Growth

BACKGROUND

Abdominal aortic aneurysm represents a distinct group of vascular lesions, in terms of surveillance and treatment. Screening and follow-up of patients via duplex ultrasound has been well established and proposed by current guidelines. However, serum circulating biomarkers could earn a position in individualized patient surveillance, especially in cases of aggressive AAA growth rates. A systematic review was conducted to assess the correlation of AAA expansion rates with serum circulating biomarkers.

METHODS

A data search of English medical literature was conducted, using PubMed, EMBASE, and CENTRAL, until 7 March 2021, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement (PRISMA) guidelines. Studies reporting on humans, on abdominal aortic aneurysm growth rates and on serum circulating biomarkers were included. No statistical analysis was conducted.

RESULTS

A total of 25 studies with 4753 patients were included. Studies were divided in two broad categories: Those reporting on clinically applicable (8 studies) and those reporting on experimental (17 studies) biomarkers. Twenty-three out of 25 studies used duplex ultrasound (DUS) for following patients. Amongst clinically applicable biomarkers, D-dimers, LDL-C, HDL-C, TC, ApoB, and HbA1c were found to bear the most significant association with AAA growth rates. In terms of the experimental biomarkers, PIIINP, osteopontin, tPA, osteopontin, haptoglobin polymorphisms, insulin-like growth factor I, thioredoxin, neutrophil extracellular traps (NETs), and genetic factors, as polymorphisms and microRNAs were positively correlated with increased AAA expansion rates.

CONCLUSION

In the presence of future robust data, specific serum biomarkers could potentially form the basis of an individualized surveillance strategy of patients presenting with increased AAA growth rates.

Increase in plasma Niemann-Pick disease type C2 protein is associated with poor prognosis of sepsis

The functional significance of extracellular Niemann-Pick disease type C2 protein (NPC2) is poorly defined. It is not known whether there is an association between plasma NPC2 and sepsis. Our exploratory, quantitative proteomic analysis showed a significant increase in the level of plasma NPC2 in moribund sepsis patients. Thus, we subsequently determined NPC2 concentration in plasma from healthy subjects, pneumonia patients and sepsis patients with comorbid pneumonia; and analyzed the association of plasma NPC2 with organ dysfunction and prognosis of sepsis patients. Our data shows that plasma NPC2 concentration was significantly higher in pneumonia and sepsis patients than healthy subjects, and was further increased in sepsis patients when the SOFA score reached 14. In addition, NPC2 concentration was significantly higher in patients that subsequently developed septic shock or died within 30 days. Moreover, NPC2 level showed the strongest association with the degree of renal dysfunction in sepsis patients. In moribund sepsis patients, however, NPC2 had highest correlation coefficient with indicators of coagulation anomaly. Based on these results, we conclude that the increase in plasma NPC2 in sepsis patients is associated with multiple organ failure, possibly results from a deficiency in renal clearance, and may serve as a prognostic marker for sepsis.

Targeting the Extracellular Matrix in Abdominal Aortic Aneurysms Using Molecular Imaging Insights

This review outlines recent preclinical and clinical advances in molecular imaging of abdominal aortic aneurysms (AAA) with a focus on molecular magnetic resonance imaging (MRI) of the extracellular matrix (ECM). In addition, developments in pharmacologic treatment of AAA targeting the ECM will be discussed and results from animal studies will be contrasted with clinical trials. Abdominal aortic aneurysm (AAA) is an often fatal disease without non-invasive pharmacologic treatment options. The ECM, with collagen type I and elastin as major components, is the key structural component of the aortic wall and is recognized as a target tissue for both initiation and the progression of AAA. Molecular imaging allows in vivo measurement and characterization of biological processes at the cellular and molecular level and sets forth to visualize molecular abnormalities at an early stage of disease, facilitating novel diagnostic and therapeutic pathways. By providing surrogate criteria for the in vivo evaluation of the effects of pharmacological therapies, molecular imaging techniques targeting the ECM can facilitate pharmacological drug development. In addition, molecular targets can also be used in theranostic approaches that have the potential for timely diagnosis and concurrent medical therapy. Recent successes in preclinical studies suggest future opportunities for clinical translation. However, further clinical studies are needed to validate the most promising molecular targets for human application.