Increased Circulating Tissue Inhibitor of Metalloproteinase-2 Is Associated With Resistant Hypertension

Neutrophil extracellular trap production and CCL4L2 expression influence corticosteroid response in asthma

The association between neutrophil extracellular traps (NETs) and response to inhaled corticosteroids (ICS) in asthma is unclear. To better understand this relationship, we analyzed the blood transcriptomes from children with controlled and uncontrolled asthma in the Taiwanese Consortium of Childhood Asthma Study using weighted gene coexpression network analysis and pathway enrichment methods. We identified 298 uncontrolled asthma-specific differentially expressed genes and one gene module associated with neutrophil-mediated immunity, highlighting a potential role for neutrophils in uncontrolled asthma. We also found that NET abundance was associated with nonresponse to ICS in patients. In a neutrophilic airway inflammation murine model, steroid treatment could not suppress neutrophilic inflammation and airway hyperreactivity. However, NET disruption with deoxyribonuclease I (DNase I) efficiently inhibited airway hyperreactivity and inflammation. Using neutrophil-specific transcriptomic profiles, we found that CCL4L2 was associated with ICS nonresponse in asthma, which was validated in human and murine lung tissue. CCL4L2 expression was also negatively correlated with pulmonary function change after ICS treatment. In summary, steroids fail to suppress neutrophilic airway inflammation, highlighting the potential need to use alternative therapies such as leukotriene receptor antagonists or DNase I that target the neutrophil-associated phenotype. Furthermore, these results highlight CCL4L2 as a potential therapeutic target for individuals with asthma refractory to ICS.

Polymorphisms and gene expression of metalloproteinases and their inhibitors associated with cerebral ischemic stroke in young patients with sickle cell anemia

BACKGROUND

Sickle cell anemia (SCA) is a genetic disease with great clinical heterogeneity and few viable strategies for treatment; hydroxyurea (HU) is the only widely used drug. Thus, the study of single nucleotide polymorphisms (SNPs) and the gene expression of MMPs 1, 2, 9, 7 and TIMPs 1 and 2, which are involved in the regulation of extracellular matrix, inflammation, and neuropathies, may provide further insights into the pathophysiology of the disease and elucidate biomarkers and molecules as potential therapeutic targets for patients with SCA.

METHODS AND RESULTS

We evaluated 251 young individuals with SCA from northeastern Brazil. The groups were divided according to vaso-occlusive crisis (VOC) and cerebrovascular disease (CVD), compared to control individuals. SNP detection and gene expression assays were performed by real-time PCR, TaqMan system®. Both the expression levels of MMP1 gene, and the SNP MMP1-1607 1G/2G were associated with the risk of cerebral ischemic stroke (IS), and the expression of MMP1 was also associated with a higher frequency of VOC/year. Expression levels of MMP7, TIMP1, and TIMP2 were increased in patients conditioned to IS. The SNP 372T>C (rs4898) TIMP1 T alleles were more frequent in patients with > 5 VOC events/year. The SNP rs17576 of MMP9 showed differences in gene expression levels; it was increased in the genotypes AG, and AG+GG.

CONCLUSION

The findings of this study, the SNPs, and expression provide initial support for understanding the role of MMPs-TIMPs in the pathophysiology of SCA in young patients.

Matrix metaloproteinases in vascular pathology

Vascular diseases are the main cause of morbidity and mortality. The vascular extracellular matrix (ECM) is essential in mechanical support, also regulating the cellular behavior fundamental to vascular function and homeostasis. Vascular remodeling is an adaptive response to various physiological and pathological changes and is associated with aging and vascular diseases. The aim of this review is provide a general overview of the involvement of MMPs in the pathogenesis of vascular diseases, namely, arterial hypertension, atherosclerosis, aortic aneurysms and myocardial infarction. The change in the composition of the ECM by matrix metalloproteinases (MMPs) generates a pro-inflammatory microenvironment that modifies the phenotypes of endothelial cells and vascular smooth muscle cells. They play a central role in morphogenesis, tissue repair and remodeling in response to injury, e.g., after myocardial infarction, and in progression of diseases such as atherosclerosis. Alterations in specific MMPs could influence arterial remodeling and lead to various pathological disorders such as hypertension and aneurysm formation. MMPs are regulated by endogenous tissue inhibitors of metalloproteinases (TIMPs), and the MMP/TIMP ratio generally determines the extent of ECM protein degradation and tissue remodeling. Studies are currently focused on improving the diagnostic and prognostic value of MMPs involved in the pathogenic process, increasing their therapeutic potential, and monitoring the disease. New selective MMP inhibitors may improve the specificity of these inhibitors, target specific MMPs in relevant pathological conditions and mitigate some of the side effects.

Association of Circulating Extracellular Matrix Components with Central Hemodynamics and Arterial Distensibility of Peripheral Arteries

BACKGROUND

In addition to neuronal and endothelial regulators of vascular tone, the passive mechanical properties of arteries, determined by the molecular structure of extracellular matrices, are the principle modulators of vascular distensibility. Specifically, the association between collagen type IV (Col IV), a constituent of basement membrane, and arterial compliance remains unclear.

METHODS

In 31 healthy adult men, radial applanation tonometry and pulse wave analysis were used to assess aortic augmentation index (AIx), aortic-to-radial pulse pressure amplification (PPAmpl), and time to reflection wave.

RESULTS

Plasma Col IV and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) concentrations were correlated with AIx (r = 0.51, p = 0.021 and r = -0.45, p = 0.042, respectively) after adjustment for age and heart rate (HR). Greater matrix metalloproteinase-9 (MMP-9) and TIMP-1 levels were associated with high PPAmpl (r = 0.45 and r = 0.64, respectively) and hence with compliant arteries. Multiple regression analyses revealed that 99% of the variation in PPAmpl was attributable to age, HR, Col IV, TIMP-1, and Col × TIMP-1 interaction (p < 0.001). No relations between tonometric variables and levels of MMP-1, -2, and -3; TIMP-2 and -4; fibronectin; glycosaminoglycans; and hydroxyproline were found.

CONCLUSION

High circulating Col IV level indexes were associated with stiffer peripheral arteries whereas increased MMP-9 and TIMP-1 concentrations were associated with more compliant ones.

Integrative Genomics Analysis Unravels Tissue-Specific Pathways, Networks, and Key Regulators of Blood Pressure Regulation

Blood pressure (BP) is a highly heritable trait and a major cardiovascular disease risk factor. Genome wide association studies (GWAS) have implicated a number of susceptibility loci for systolic (SBP) and diastolic (DBP) blood pressure. However, a large portion of the heritability cannot be explained by the top GWAS loci and a comprehensive understanding of the underlying molecular mechanisms is still lacking. Here, we utilized an integrative genomics approach that leveraged multiple genetic and genomic datasets including (a) GWAS for SBP and DBP from the International Consortium for Blood Pressure (ICBP), (b) expression quantitative trait loci (eQTLs) from genetics of gene expression studies of human tissues related to BP, (c) knowledge-driven biological pathways, and (d) data-driven tissue-specific regulatory gene networks. Integration of these multidimensional datasets revealed tens of pathways and gene subnetworks in vascular tissues, liver, adipose, blood, and brain functionally associated with DBP and SBP. Diverse processes such as platelet production, insulin secretion/signaling, protein catabolism, cell adhesion and junction, immune and inflammation, and cardiac/smooth muscle contraction, were shared between DBP and SBP. Furthermore, "Wnt signaling" and "mammalian target of rapamycin (mTOR) signaling" pathways were found to be unique to SBP, while "cytokine network", and "tryptophan catabolism" to DBP. Incorporation of gene regulatory networks in our analysis informed on key regulator genes that orchestrate tissue-specific subnetworks of genes whose variants together explain ~20% of BP heritability. Our results shed light on the complex mechanisms underlying BP regulation and highlight potential novel targets and pathways for hypertension and cardiovascular diseases.

Arterial (Aortic) Stiffness in Patients with Resistant Hypertension: from Assessment to Treatment

PURPOSE OF REVIEW

The purpose of the review is to examine whether measurement of aortic stiffness could be especially value-adding for risk stratification and treatment among patients with resistant hypertension (RH).

RECENT FINDINGS

Adverse arterial remodeling and increased aortic stiffness is associated with RH, and it may be of additional clinical benefit to measure aortic stiffness in these patients. However, there is insufficient evidence to determine whether aortic stiffness is excessively high relative to the level of blood pressure (BP) among people with RH. This issue needs resolution as it could help refine management decisions guided by aortic stiffness. If conventional antihypertensive therapy fails to lower BP in patients with RH, there is good rationale for effectiveness of spironolactone as add on therapy, and this should also improve aortic stiffness. Lifestyle intervention with exercise and diet should be additionally efficacious towards improving BP and aortic stiffness in patients with RH, but there is limited data in this patient population. For better characterization on the effects of BP treatment on aortic stiffness, measures of central aortic BP may help refine management decisions above and beyond conventional arm cuff BP. There is strong evidence to support the use of aortic stiffness as a tool to aid risk stratification in hypertension management. Although there is a theoretical basis for special additional benefit of measuring aortic stiffness in patients with RH (as distinct from uncomplicated hypertension), at this time, there is inadequate data available to make definitive conclusions and is an area for future investigation.