Effects of age on plasma matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs)

The Senescent Heart-"Age Doth Wither Its Infinite Variety"

Cardiovascular diseases are a leading cause of morbidity and mortality world-wide. While many factors like smoking, hypertension, diabetes, dyslipidaemia, a sedentary lifestyle, and genetic factors can predispose to cardiovascular diseases, the natural process of aging is by itself a major determinant of the risk. Cardiac aging is marked by a conglomerate of cellular and molecular changes, exacerbated by age-driven decline in cardiac regeneration capacity. Although the phenotypes of cardiac aging are well characterised, the underlying molecular mechanisms are far less explored. Recent advances unequivocally link cardiovascular aging to the dysregulation of critical signalling pathways in cardiac fibroblasts, which compromises the critical role of these cells in maintaining the structural and functional integrity of the myocardium. Clearly, the identification of cardiac fibroblast-specific factors and mechanisms that regulate cardiac fibroblast function in the senescent myocardium is of immense importance. In this regard, recent studies show that Discoidin domain receptor 2 (DDR2), a collagen-activated receptor tyrosine kinase predominantly located in cardiac fibroblasts, has an obligate role in cardiac fibroblast function and cardiovascular fibrosis. Incisive studies on the molecular basis of cardiovascular aging and dysregulated fibroblast function in the senescent heart would pave the way for effective strategies to mitigate cardiovascular diseases in a rapidly growing elderly population.

Targeting Collagen Pathways as an HFpEF Therapeutic Strategy

Heart failure with preserved ejection fraction (HFpEF) is a complex and heterogeneous clinical syndrome. The prevalence is expected to increase in the coming years, resulting in heart failure with reduced ejection fraction (HFrEF). This condition poses a burden to the global health care system as the number of patients affected by this condition is constantly increasing due to a rising average lifespan. The absence of validated drugs effective in reducing hospitalization rates and mortality may reflect the impossibility of applying a one size fits all approach as in HFrEF, heading for a personalized approach. Available evidence demonstrated the link between collagen quantity and quality alterations, and cardiac remodeling. In the context of fibrosis, collagen cross-linking is strictly involved, displaying two types of mechanisms: enzymatic and non-enzymatic. In the murine model, enzymatic inhibition of fibrosis-inducing protease-activated receptor-1 (PAR1) and transforming growth factor (TGF)-β signaling appeared to reduce cardiac fibrosis. On the other hand, in the case of non-enzymatic cross-linking, sodium glucose co-transporter type 2 inhibitors (SGLT2is), appeared to counteract the deposition of advanced glycation end-products (AGEs), which in turn contributed to ventricular remodeling. In this review, we address the mechanisms associated with collagen alterations to identify potential targets of cardiac fibrosis in HFpEF patients.

Serum matrix metalloproteinase-7: a potential biomarker in patients with Lynch Syndrome

BACKGROUND AND AIMS

The expression of tissue and serum matrix metalloproteinase-7 (MMP-7) was shown to be elevated both in colon cancer and dysplastic lesions. We aimed to evaluate, for the first time, its role as a diagnostic marker in Lynch syndrome (LS) carriers, a hereditary syndrome with predisposition to colon cancer.

METHODS

This was a case control study. Baseline serum MMP-7 levels were determined by ELISA in 40 colon cancer patients, 62 LS-carriers and 60 healthy controls. Retrieved data from medical files included demographics, background diseases, clinical data regarding tumor characteristics and genetic data. We assessed the association of serum MMP-7 levels with different variables in the study cohort using linear regression model adjusted for potential confounders.

RESULTS

In crude analysis, serum MMP-7 levels were significantly higher in colon cancer group compared to LS-carriers and controls [median (IQR) 4.1 ng/ml (2.7-6.0), 2.3 ng/ml (1.7-3.1), 2.5 ng/ml (1.5-3.7), respectively; p value - p < 0.001) while there was no difference between the two last groups (p value = 0.583). However, after adjusting for age and gender, LS-carriers' patients had 18% higher concentrations of serum MMP-7 compared to healthy controls (p value = 0.037), while colon cancer patients had 50% higher serum MMP-7 level in comparison to healthy controls (p value < 0.001). Additionally, age was positively associated with higher serum MMP-7 levels across all study groups (r = 0.67, p value < 0.001). In contrast, no correlation was observed between serum MMP-7 and either tumor staging and gene mutation.

CONCLUSIONS

Age-adjusted serum MMP-7 levels in asymptomatic LS carriers are higher than its levels in healthy population. While in colon cancer, MMP-7 higher level probably reflects the tumor burden and may have a prognostic effect, its significance and clinical applicability as a biomarker for tumorigenesis in LS is less clear and should be elucidated.

Female C57BL/6N mice are a viable model of aortic aging in women

The aorta stiffens with aging in both men and women, which predicts cardiovascular mortality. Aortic wall structural and extracellular matrix (ECM) remodeling, induced in part by chronic low-grade inflammation, contribute to aortic stiffening. Male mice are an established model of aortic aging. However, there is little information regarding whether female mice are an appropriate model of aortic aging in women, which we aimed to elucidate in the present study. We assessed two strains of mice and found that in C57BL/6N mice, in vivo aortic stiffness (pulse wave velocity, PWV) was higher with aging in both sexes, whereas in B6D2F1 mice, PWV was higher in old versus young male mice, but not in old versus young female mice. Because the age-related stiffening that occurs in men and women was reflected in male and female C57BL/6N mice, we examined the mechanisms of stiffening in this strain. In both sexes, aortic modulus of elasticity (pin myography) was lower in old mice, occurred in conjunction with and was related to higher plasma levels of the elastin-degrading enzyme matrix metalloproteinase-9 (MMP-9), and was accompanied by higher numbers of aortic elastin breaks and higher abundance of adventitial collagen-1. Plasma levels of the inflammatory cytokines interferon-γ, interleukin 6, and monocyte chemoattractant protein-1 were higher in both sexes of old mice. In conclusion, female C57BL/6N mice exhibit aortic stiffening, reduced modulus of elasticity and structural/ECM remodeling, and associated increases in MMP-9 and systemic inflammation with aging, and thus are an appropriate model of aortic aging in women.NEW & NOTEWORTHY Our study demonstrates that with aging, female C57BL/6N mice exhibit higher in vivo aortic stiffness, reduced modulus of elasticity, aortic wall structural and extracellular matrix remodeling, and elevations in systemic inflammation. These changes are largely reflective of those that occur with aging in women. Thus, female C57BL/6N mice are a viable model of human aortic aging and the utility of these animals should be considered in future biomedical investigations.

Senescent cardiac fibroblasts: A key role in cardiac fibrosis

Cardiac fibroblasts are a cell population that controls the homeostasis of the extracellular matrix and orchestrates a damage response to maintain cardiac architecture and performance. Due to these functions, fibroblasts play a central role in cardiac fibrosis development, and there are large differences in matrix protein secretion profiles between fibroblasts from aged versus young animals. Senescence is a multifactorial and complex process that has been associated with inflammatory and fibrotic responses. After damage, transient cellular senescence is usually beneficial, as these cells promote tissue repair. However, the persistent presence of senescent cells within a tissue is linked with fibrosis development and organ dysfunction, leading to aging-related diseases such as cardiovascular pathologies. In the heart, early cardiac fibroblast senescence after myocardial infarction seems to be protective to avoid excessive fibrosis; however, in non-infarcted models of cardiac fibrosis, cardiac fibroblast senescence has been shown to be deleterious. Today, two new classes of drugs, termed senolytics and senostatics, which eliminate senescent cells or modify senescence-associated secretory phenotype, respectively, arise as novel therapeutical strategies to treat aging-related pathologies. However, further studies will be needed to evaluate the extent of the utility of senotherapeutic drugs in cardiac diseases, in which pathological context and temporality of the intervention must be considered.

Serum levels of matrix metalloproteinase 2 and its inhibitor after tonic-clonic seizures

Damage to the blood-brain barrier (BBB) may result from on-going neuroinflammation, which can lead to leakage of blood components, such as leukocytes and serum proteins, into the brain, resulting in disturbed brain homeostasis. The aim of the project was to examine the involvement of modulatory proteins in the processes of BBB integration after epileptic seizures. We investigated serum changes in the levels of MMP-2 and MMP-7 and its inhibitors after seizures in epilepsy patients. Concentrations of these proteins were measured by ELISA in 50 patients at 1-3, 24, and 72 h after generalized tonic-clonic seizures and once in participants of the control group. The level of MMP-2 in serum was slightly higher after seizures (at 1-3 h time point), but the difference was not statistically significant. The levels of trombospondine (TSP) - 1 and - 2 were decreased at 1-3 h after seizures. The expression of TIMP-2 was increased 1 and 24 h after seizures. There were no significant changes in the level of α2-macroglobulin and MMP-7. Changes in the expression of both specific and non-specific inhibitors indicate the initiation of repair processes of the blood-brain barrier and improvement of its integrity. Since we performed serum analysis, further studies are necessary to investigate the correlation with the expression of the investigated markers in the brain. Perhaps this will allow for the identification of new biomarkers associated with epileptic seizures.

Evaluation of the main regulators of extracellular matrix metabolism in healthy adolescents in the Far North

Myocardial remodeling is well-known to be both an adaptive option under certain conditions of life (sports, pregnancy, etc.), and the result of cardiovascular pathology. The study of the features of cardiac remodeling includes the involvement of cardiomyocytes in the process by the level of troponins, creatine phosphokinase, and its cardiac isoform as markers of ischemia and necrosis. Also, neurohormonal rearrangement is evaluated using a natriuretic peptide, and endothelial dysfunction is determined using a C–reactive protein. The level of matrix metalloproteinases (MMP) and their tissue inhibitors (TIMP) reflects the degree of the proteolytic activity and collagen fibers’ degradation. However, there are no clear biochemical markers of “adaptive heart” and pathological changes in different age periods, in the climatic environment, various types and severity of sports loads, especially when evaluating matrix metalloproteinases and their tissue inhibitors. The primary task in determining the criteria for pathological remodeling of the myocardium becomes the definition of normative indicators.The aim of the study was to determine the reference values of the main biochemical markers of cardiac remodeling in healthy adolescents living in the Far North. The levels of troponin I, creatine phosphokinase-MV, aspartate aminotransferase did not exceed the generally accepted standard values. There were correlations between lactate dehydrogenase, aspartate aminotransferase, and mass-growth indicators of adolescents. Markers of extracellular matrix degradation (MMP-9, TIMP-1 and TIMP-4, MMP-9/ TIMP-1) differed from the data available in the published studies, which is probably due to the influence of tissue hypoxia associated with the climatic living conditions and the age in children of the study group.

Framing Heartaches: The Cardiac ECM and the Effects of Age

The cardiac extracellular matrix (ECM) is involved in several pathological conditions, and age itself is also associated with certain changes in the heart: it gets larger and stiffer, and it develops an increased risk of abnormal intrinsic rhythm. This, therefore, makes conditions such as atrial arrythmia more common. Many of these changes are directly related to the ECM, yet the proteomic composition of the ECM and how it changes with age is not fully resolved. The limited research progress in this field is mainly due to the intrinsic challenges in unravelling tightly bound cardiac proteomic components and also the time-consuming and costly dependency on animal models. This review aims to give an overview of the composition of the cardiac ECM, how different components aid the function of the healthy heart, how the ECM is remodelled and how it is affected by ageing.

Blood-Brain Barrier-Associated Proteins Are Elevated in Serum of Epilepsy Patients

Blood-brain barrier (BBB) dysfunction emerges as one of the mechanisms underlying the induction of seizures and epileptogenesis. There is growing evidence that seizures also affect BBB, yet only scarce data is available regarding serum levels of BBB-associated proteins in chronic epilepsy. In this study, we aimed to assess serum levels of molecules associated with BBB in patients with epilepsy in the interictal period. Serum levels of MMP-9, MMP-2, TIMP-1, TIMP-2, S100B, CCL-2, ICAM-1, P-selectin, and TSP-2 were examined in a group of 100 patients who were seizure-free for a minimum of seven days and analyzed by ELISA. The results were compared with an age- and sex-matched control group. Serum levels of MMP-9, MMP-2, TIMP-1, TIMP-2 and S100B were higher in patients with epilepsy in comparison to control group (p < 0.0001; <0.0001; 0.001; <0.0001; <0.0001, respectively). Levels of CCL-2, ICAM-1, P-selectin and TSP-2 did not differ between the two groups. Serum levels of MMP-9, MMP-2, TIMP-1, TIMP-2 and S100B are elevated in patients with epilepsy in the interictal period, which suggests chronic processes of BBB disruption and restoration. The pathological process initiating epilepsy, in addition to seizures, is probably the factor contributing to the elevation of serum levels of the examined molecules.

Cardiac System during the Aging Process

The aging process is accompanied by a continuous decline of the cardiac system, disrupting the homeostatic regulation of cells, organs, and systems. Aging increases the prevalence of cardiovascular diseases, thus heart failure and mortality. Understanding the cardiac aging process is of pivotal importance once it allows us to design strategies to prevent age-related cardiac events and increasing the quality of live in the elderly. In this review we provide an overview of the cardiac aging process focus on the following topics: cardiac structural and functional modifications; cellular mechanisms of cardiac dysfunction in the aging; genetics and epigenetics in the development of cardiac diseases; and aging heart and response to the exercise.

The Biology and Function of Tissue Inhibitor of Metalloproteinase 2 in the Lungs

Tissue inhibitors of matrix metalloproteinases (TIMP) are a family of four endogenous proteins that primarily function to inhibit the activities of proteases such as the matrix metalloproteinases (MMP). Altered MMP/TIMP ratios are frequently observed in several human diseases. During aging and disease progression, the extracellular matrix (ECM) undergoes structural changes in which elastin and collagens serve an essential role. MMPs and TIMPs significantly influence the ECM. Classically, elevated levels of TIMPs are suggested to result in ECM accumulation leading to fibrosis, whereas loss of TIMP responses leads to enhanced matrix proteolysis. Here, we outline the known roles of the most abundant TIMP, TIMP2, in pulmonary diseases but also discuss future perspectives in TIMP2 research that could impact the lungs. TIMP2 directly inhibits MMPs, in particular MMP2, but TIMP2 is also required for the activation of MMP2 through its interaction with MMP14. The protease and antiprotease imbalance of MMPs and TIMPs are extensively studied in diseases but recent discoveries suggest that TIMPs, specifically, TIMP2 could play other roles in aging and inflammation processes.

D-galactose-induced cardiac ageing: A review of model establishment and potential interventions

Cardiovascular disease (CVD) is highly prevalent in an ageing society. The increased incidence and mortality rates of CVD are global issues endangering human health. There is an urgent requirement for understanding the aetiology and pathogenesis of CVD and developing possible interventions for preventing CVD in ageing hearts. It is necessary to select appropriate models and treatment methods. The D‐galactose‐induced cardiac ageing model possesses the advantages of low mortality, short time and low cost and has been increasingly used in the study of cardiovascular diseases in recent years. Therefore, understanding the latest progress in D‐galactose‐induced cardiac ageing is valuable. This review highlights the recent progress and potential therapeutic interventions used in D‐galactose‐induced cardiac ageing in recent years by providing a comprehensive summary of D‐galactose‐induced cardiac ageing in vivo and in vitro. This review may serve as reference literature for future research on age‐related heart diseases.

Senescence-associated secretory phenotype and its impact on oral immune homeostasis

The senescence-associated secretory phenotype (SASP), which accumulates over the course of normal aging and in age-related diseases, is a crucial driver of chronic inflammation and aging phenotypes. It is also responsible for the pathogenesis of multiple oral diseases. However, the pathogenic mechanism underlying SASP has not yet been fully elucidated. Here, relevant articles on SASP published over the last five years (2017-2022) were retrieved and used for bibliometric analysis, for the first time, to examine SASP composition. More than half of the relevant articles focus on various cytokines (27.5%), growth factors (20.9%), and proteases (20.9%). In addition, lipid metabolites (13.1%) and extracellular vesicles (6.5%) have received increasing attention over the past five years, and have been recognized as novel SASP categories. Based on this, we summarize the evidences demonstrating that SASP plays a pleiotropic role in oral immunity and propose a four-step hypothetical framework for the progression of SASP-related oral pathology-1) oral SASP development, 2) SASP-related oral pathological alterations, 3) pathological changes leading to oral immune homeostasis disruption, and 4) SASP-mediated immune dysregulation escalating oral disease. By targeting specific SASP factors, potential therapies can be developed to treat oral and age-related diseases.

Clinical significance of matrix metalloproteinase-9 in Fragile X Syndrome

High plasma matrix metalloproteases-9 (MMP-9) levels have been reported in Fragile X Syndrome in a limited number of animal and human studies. Since the results obtained are method-dependent and not directly comparable, the clinical utility of MMP-9 measurement in FXS remains unclear. This study aimed to compare quantitative gel zymography and ELISA and to determine which method better discriminates abnormal MMP-9 levels of individuals with FXS from healthy controls and correlates with the clinical profile. The active and total forms of MMP-9 were quantified respectively, by gel zymography and ELISA in a cohort of FXS (n = 23) and healthy controls (n = 20). The clinical profile was assessed for the FXS group using the Aberrant Behavior Checklist FXS adapted version (ABC-C_FX), Adaptive Behavior Assessment System (ABAS), Social Communication Questionnaire (SCQ), and Anxiety Depression and Mood Scale questionnaires. Method comparison showed a disagreement between gel zymography and ELISA with a constant error of − 0.18 [95% CI: − 0.35 to − 0.02] and a proportional error of 2.31 [95% CI: 1.53 to 3.24]. Plasma level of MMP-9 active form was significantly higher in FXS (n = 12) as compared to their age-sex and BMI matched controls (n = 12) (p = 0.039) and correlated with ABC-C_FX (r_s = 0.60; p = 0.039) and ADAMS (r_s = 0.57; p = 0.043) scores. As compared to the plasma total form, the plasma MMP-9 active form better enables the discrimination of individuals with FXS from controls and correlates with the clinical profile. Our results highlight the importance of choosing the appropriate method to quantify plasma MMP-9 in future FXS clinical studies.

Clinical electrophysiology of the aging heart

INTRODUCTION

Advancements in medical and consumer-grade technologies have made it easier than ever to monitor a patient's heart rhythm and to diagnose arrhythmias. Octogenarians with symptomatic arrhythmias have unique management challenges due to their frailty, complex drug interactions, cognitive impairment, and competing comorbidities. The management decisions are further complicated by the lack of randomized evidence to guide treatment.

AREAS COVERED

A comprehensive literature review was undertaken to outline various tachyarrhythmias and bradyarrhythmias and their management, the role of cardiac implantable electronic devices, cardiac ablations, and specific geriatric arrhythmia considerations as recommended in international guidelines.

EXPERT OPINION

Atrial fibrillation (AF) is arguably the most important arrhythmia in the elderly and is associated with significant morbidity and mortality. Early diagnosis of AF, potentially with smart devices (wearables), has the potential to reduce the incidence of stroke, systemic emboli, and the risk of dementia. Bradyarrhythmias have a high incidence in the elderly as well, often requiring implantation of a permanent pacemaker. Leadless pacemakers implanted directly into the right ventricle are great options for gaining traction in elderly patients.

Serological cancer-associated protein biomarker levels at bowel endoscopy: Increased risk of subsequent primary malignancy

BACKGROUND

It was previously shown in three subpopulations that subjects not identified with colorectal cancer (CRC) at bowel endoscopy, but with increased serological cancer-associated protein biomarker levels had an increased risk of being diagnosed with subsequent malignant diseases.

OBJECTIVE

The aim of the present study was to perform a pooled analysis of subjects from the three subpopulations and subsequently validate the results in an independent study. The study population denoted the training set includes N = 4,076 subjects with symptoms attributable to CRC and the independent validation set N = 3,774 similar subjects.

METHODS

Levels of CEA, CA19-9, TIMP-1 and YKL-40 were determined in blood samples collected prior to diagnostic bowel endoscopy. Follow-up of subjects not diagnosed with CRC at endoscopy, was ten years and identified subjects diagnosed with primary intra- or extra-colonic malignant diseases. The primary analysis was time to a newly diagnosed malignant disease and was analyzed with death as a competing risk in the training set. Subjects with HNPCC or FAP were excluded. The cumulated incidence was estimated for each biomarker and in a multivariate model. The resulting model was then validated on the second study population.

RESULTS

In the training set primary malignancies were identified in 515 (12.6%) of the 4,076 subjects, who had a colorectal endoscopy with non-malignant findings. In detail, 33 subjects were subsequently diagnosed with CRC and 482 subjects with various extra-colonic cancers. Multivariate additive analysis of the dichotomized biomarkers demonstrated that CEA (HR = 1.50, 95% CI:1.21-1.86, p < 0.001), CA19-9 (HR = 1.41, 95% CI:1.10-1.81, p = 0.007) and TIMP-1 (HR = 1.25 95% CI: 1.01-1.54, p = 0.041) were significant predictors of subsequent malignancy. The cumulated incidence at 5 years landmark time was 17% for those subjects with elevated CEA, CA19-9 and TIMP-1 versus 6.7% for those with low levels of all. When the model was applied to the validation set the cumulated 5-year incidence was 10.5% for subjects with elevated CEA, CA19-9 and TIMP-1 and 5.6% for subjects with low levels of all biomarkers. Further analysis demonstrated a significant interaction between TIMP-1 and age in the training set. The age dependency of TIMP-1 indicated a greater risk of malignancy in younger subjects if the biomarker was elevated. This observation was validated in the second set.

CONCLUSION

Elevated cancer-associated protein biomarker levels in subjects with non-malignant findings at large bowel endoscopy identifies subjects at increased risk of being diagnosed with subsequent primary malignancy. CEA, CA19-9 and TIMP-1 were significant predictors of malignant disease in this analysis. TIMP-1 was found dependent on age. The results were validated in an independent symptomatic population.

The Mechanobiology of Vascular Remodeling in the Aging Lung

Aging is accompanied by declining lung function and increasing susceptibility to lung diseases. The role of endothelial dysfunction and vascular remodeling in these changes is supported by growing evidence, but underlying mechanisms remain elusive. In this review we summarize functional, structural, and molecular changes in the aging pulmonary vasculature and explore how interacting aging and mechanobiological cues may drive progressive vascular remodeling in the lungs.

A potential role of autophagy-mediated vascular senescence in the pathophysiology of HFpEF

Heart failure with preserved ejection fraction (HFpEF) is one of the most complex and most prevalent cardiometabolic diseases in aging population. Age, obesity, diabetes, and hypertension are the main comorbidities of HFpEF. Microvascular dysfunction and vascular remodeling play a major role in its development. Among the many mechanisms involved in this process, vascular stiffening has been described as one the most prevalent during HFpEF, leading to ventricular-vascular uncoupling and mismatches in aged HFpEF patients. Aged blood vessels display an increased number of senescent endothelial cells (ECs) and vascular smooth muscle cells (VSMCs). This is consistent with the fact that EC and cardiomyocyte cell senescence has been reported during HFpEF. Autophagy plays a major role in VSMCs physiology, regulating phenotypic switch between contractile and synthetic phenotypes. It has also been described that autophagy can regulate arterial stiffening and EC and VSMC senescence. Many studies now support the notion that targeting autophagy would help with the treatment of many cardiovascular and metabolic diseases. In this review, we discuss the mechanisms involved in autophagy-mediated vascular senescence and whether this could be a driver in the development and progression of HFpEF.

Pathophysiology of Circulating Biomarkers and Relationship With Vascular Aging: A Review of the Literature From VascAgeNet Group on Circulating Biomarkers, European Cooperation in Science and Technology Action 18216

Impairment of the arteries is a product of sustained exposure to various deleterious factors and progresses with time; a phenomenon inherent to vascular aging. Oxidative stress, inflammation, the accumulation of harmful agents in high cardiovascular risk conditions, changes to the extracellular matrix, and/or alterations of the epigenetic modification of molecules, are all vital pathophysiological processes proven to contribute to vascular aging, and also lead to changes in levels of associated circulating molecules. Many of these molecules are consequently recognized as markers of vascular impairment and accelerated vascular aging in clinical and research settings, however, for these molecules to be classified as biomarkers of vascular aging, further criteria must be met. In this paper, we conducted a scoping literature review identifying thirty of the most important, and eight less important, biomarkers of vascular aging. Herein, we overview a selection of the most important molecules connected with the above-mentioned pathological conditions and study their usefulness as circulating biomarkers of vascular aging.

Immuno-regenerative biomaterials for in situ cardiovascular tissue engineering - Do patient characteristics warrant precision engineering?

In situ tissue engineering using bioresorbable material implants - or scaffolds - that harness the patient's immune response while guiding neotissue formation at the site of implantation is emerging as a novel therapy to regenerate human tissues. For the cardiovascular system, the use of such implants, like blood vessels and heart valves, is gradually entering the stage of clinical translation. This opens up the question if and to what extent patient characteristics influence tissue outcomes, necessitating the precision engineering of scaffolds to guide patient-specific neo-tissue formation. Because of the current scarcity of human in vivo data, herein we review and evaluate in vitro and preclinical investigations to predict the potential role of patient-specific parameters like sex, age, ethnicity, hemodynamics, and a multifactorial disease profile, with special emphasis on their contribution to the inflammation-driven processes of in situ tissue engineering. We conclude that patient-specific conditions have a strong impact on key aspects of in situ cardiovascular tissue engineering, including inflammation, hemodynamic conditions, scaffold resorption, and tissue remodeling capacity, suggesting that a tailored approach may be required to engineer immuno-regenerative biomaterials for safe and predictive clinical applicability.

MMP-2 knockdown blunts age-dependent carotid stiffness by decreasing elastin degradation and augmenting eNOS activation

AIMS

Arterial stiffness is a hallmark of vascular aging that precedes and strongly predicts the development of cardiovascular diseases. Age-dependent stiffening of large elastic arteries is primarily attributed to increased levels of matrix metalloproteinase-2 (MMP-2). However, the mechanistic link between age-dependent arterial stiffness and MMP-2 remains unclear. Thus, we aimed to investigate the efficacy of MMP-2 knockdown using small interfering RNA (siRNA) on age-dependent arterial stiffness.

METHODS AND RESULTS

Pulse wave velocity (PWV) was assessed in right carotid artery of wild type (WT) mice from different age groups. MMP-2 levels in the carotid artery and plasma of young (3 months) and old (20-25 months) WT mice were determined. Carotid PWV as well as vascular and circulating MMP-2 were elevated with increasing age in mice. Old WT mice (18-21-month-old) were treated for 4 weeks with either MMP-2 or scrambled (Scr) siRNA via tail vein injection. Carotid PWV was assessed at baseline, 2 and 4 weeks after start of the treatment. MMP-2 knockdown reduced vascular MMP-2 levels and attenuated age-dependent carotid stiffness. siMMP-2 treated mice showed increased elastin to collagen ratio, lower plasma desmosine (DES), enhanced phosphorylation of endothelial nitric oxide synthase (eNOS) and higher levels of vascular cyclic guanosine monophosphate (cGMP). An age-dependent increase in direct protein-protein interaction between MMP-2 and eNOS was also observed. Lastly, DES, an elastin breakdown product, was measured in a patient cohort (n = 64, 23-86 years old), where carotid-femoral PWV was also assessed; here, plasma levels of DES directly correlated with age and arterial stiffness.

CONCLUSION

MMP-2 knockdown attenuates age-dependent carotid stiffness by blunting elastin degradation and augmenting eNOS bioavailability. Given the increasing clinical use of siRNA technology, MMP2 knockdown should be investigated further as a possible strategy to mitigate age-dependent arterial stiffness and related CV diseases.

TRANSLATIONAL PERSPECTIVE

Arterial stiffness is a hallmark of vascular aging that precedes and strongly predicts the development of cardiovascular diseases. This study provides translational evidence to support a key role for MMP-2 on the development of age-associated arterial stiffness. Silencing of MMP-2 using siRNA technology shows an effect on aged mice where it attenuates age-dependent carotid stiffness by reducing elastin degradation and increasing eNOS bioavailability. Additionally, in humans we show that elastin breakdown increases with age and increased PWV. These findings indicate MMP-2 knockdown as a promising novel strategy to attenuate age-dependent arterial stiffness and cardiovascular diseases.

Collagen Biosynthesis, Processing, and Maturation in Lung Ageing

In addition to providing a macromolecular scaffold, the extracellular matrix (ECM) is a critical regulator of cell function by virtue of specific physical, biochemical, and mechanical properties. Collagen is the main ECM component and hence plays an essential role in the pathogenesis and progression of chronic lung disease. It is well-established that many chronic lung diseases, e.g., chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF) primarily manifest in the elderly, suggesting increased susceptibility of the aged lung or accumulated alterations in lung structure over time that favour disease. Here, we review the main steps of collagen biosynthesis, processing, and turnover and summarise what is currently known about alterations upon lung ageing, including changes in collagen composition, modification, and crosslinking. Recent proteomic data on mouse lung ageing indicates that, while the ER-resident machinery of collagen biosynthesis, modification and triple helix formation appears largely unchanged, there are specific changes in levels of type IV and type VI as well as the two fibril-associated collagens with interrupted triple helices (FACIT), namely type XIV and type XVI collagens. In addition, levels of the extracellular collagen crosslinking enzyme lysyl oxidase are decreased, indicating less enzymatically mediated collagen crosslinking upon ageing. The latter contrasts with the ageing-associated increase in collagen crosslinking by advanced glycation endproducts (AGEs), a result of spontaneous reactions of protein amino groups with reactive carbonyls, e.g., from monosaccharides or reactive dicarbonyls like methylglyoxal. Given the slow turnover of extracellular collagen such modifications accumulate even more in ageing tissues. In summary, the collective evidence points mainly toward age-induced alterations in collagen composition and drastic changes in the molecular nature of collagen crosslinks. Future work addressing the consequences of these changes may provide important clues for prevention of lung disease and for lung bioengineering and ultimately pave the way to novel targeted approaches in lung regenerative medicine.

Terminal Schwann Cell Aging: Implications for Age-Associated Neuromuscular Dysfunction

Action potential is transmitted to muscle fibers through specialized synaptic interfaces called neuromuscular junctions (NMJs). These structures are capped by terminal Schwann cells (tSCs), which play essential roles during formation and maintenance of the NMJ. tSCs are implicated in the correct communication between nerves and muscles, and in reinnervation upon injury. During aging, loss of muscle mass and strength (sarcopenia and dynapenia) are due, at least in part, to the progressive loss of contacts between muscle fibers and nerves. Despite the important role of tSCs in NMJ function, very little is known on their implication in the NMJ-aging process and in age-associated denervation. This review summarizes the current knowledge about the implication of tSCs in the age-associated degeneration of NMJs. We also speculate on the possible mechanisms underlying the observed phenotypes.

D-galactose-induced toxicity associated senescence mitigated by alpinate oxyphyllae fructus fortified adipose-derived mesenchymal stem cells

This study addresses the effect of D-galactose-induced toxicity associated senescence mitigated by alpinate oxyphyllae fructus (AOF; Alpinia oxyphylla Miq) extracts fortified with adipose-derived mesenchymal stem cells (ADMSCs) in rats. Male 18 week-old Wistar Kyoto (WKY) rats were used in this study. We analyzed cardiac fibrosis by Masson's trichrome staining. The tissue sections were dyed using hematoxylin and eosin (H&E). Tissue sections were stained for the restoration of Nrf2 expression in treatment groups by immunohistochemistry. Immunohistochemistry and western blotting analysis showed that AOF with ADMSCs could significantly reduce aging-induced oxidative stress in D-galactose-induced aging rat hearts by inducing Nrf2 pathway. Reduction in ROS resulted in the suppression of inflammatory signals (p-NF-κB and IL-6). Histopathological studies were showed an increased interstitium and collagen accumulation in aging-induced heart sections. However, AOF and ADMSCs treated hearts were recovered from cardiac remodeling. Furthermore, hypertrophy and fibrosis associated markers were also significantly reduced (P < .05) in treatment groups. We speculate that ADMSCs might activate certain paracrine factors, which could target the upstream activator of aging associated cardiac complications and AOF might provide homing for these stem cells.

Concerted actions by MMPs, ADAMTS and serine proteases during remodeling of the cartilage callus into bone during osseointegration of hip implants

INTRODUCTION

Although the number of patients undergoing total hip arthroplasty is constantly on the rise, we only have limited knowledge of the molecular mechanisms necessary for successful osseointegration of implants or the reasons why some fail. Understanding the spatiotemporal characteristics of signaling pathways involved in bone healing of implants is therefore of particular importance for our ability to identify factors causing implants to fail. The current study investigated the role of three families of proteases, i.e. MMPs (matrix metalloproteinases), ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) and serine proteases, as well as their endogenous inhibitors during osseointegration of hip implants that have endured two decades of use without clinical or radiological signs of loosening.

MATERIALS AND METHODS

Twenty-four patients that had undergone primary THA due to one-sided osteoarthritis (OA) were monitored during 18 years (Y) with repeated measurements of plasma biomarkers, clinical variables and radiographs. All implants were clinically and radiographically well-fixed throughout the follow-up. Eighty-one healthy donors divided in three gender and age-matched groups and twenty OA patients awaiting THA, served as controls. Plasma was analyzed for MMP-1, -2, -3, -8, -9, -10, -13, -14, tissue inhibitor of metalloproteinase (TIMP)-1, -2, -3, ADAMTS4, ADAMTS5, the serine proteases neutrophil elastase (NE), proteinase 3 (PR3) and their endogenous inhibitors, secretory leucocyte proteinase inhibitor (SLPI), trappin-2/elafin and serpina1 (α-1 antitrypsin). Cartilage turnover was monitored using two markers of cartilage synthesis, type II procollagen and PIICP (procollagen II C-terminal propeptide), and two markers of cartilage degradation, CTX-II (C-terminal telopeptide fragments of type II collagen) and split products of aggrecan (G1-IGD-G2).

RESULTS

MMP-1, MMP-9, ADAMTS4, NE and PR3 were above healthy in presurgery OA patients but returned to the level of healthy within 6 weeks (W) after surgery. MMPs and serine proteases were counter-regulated during this phase by TIMP-1, SLPI and trappin-2/elafin. Type II procollagen, PIICP and CTX-II increased to a peak 6 W after surgery with a gradual return to the level of controls within weeks. Significant increases by MMP-8, MMP-9, ADAMTS4, ADAMTS5, NE, PR3 and the protease inhibitors, TIMP-3 and serpina1, were seen 5 Y after hip arthroplasty paralleled by a sharp increase in the levels of the cartilage degradation markers, CTX-II and G1-IGD-G2. All the above mediators were normalized before 18 Y, except MMP-1 and MMP-9 that remained above healthy at 18 Y. MMP-14 increased immediately after surgery and remained elevated until 5 Y postsurgery before returning to the level of controls at 7 Y.

CONCLUSION

Notwithstanding temporal differences, the molecular processes of bone repair in arthroplasty patients show great spatial similarities with the classical phases of fracture repair as previously shown in animal models. Cartilagenous callus, produced and remodeled early after hip arthroplasty, is replaced with bone 5 Y to7 Y after surgery by the concerted actions of MMP-8, MMP-9, ADAMTS4, ADAMTS5, NE and PR3, thus suggesting that a complex regulatory cross-talk may exist between different families of proteases during this transitional phase of cartilage degradation. Regulation and fine-tuning of cartilage remodeling by MMPs and ADAMTS is controlled by TIMP-3 whereas serine proteases are regulated by serpina1. Increased MMP-1 and MMP-9 beyond 10Y post-THA support a role during coupled bone remodeling.

The 'rejuvenating factor' TIMP-2 is detectable in human blood components for transfusion

Background and Objectives

Tissue inhibitor of metalloproteinases 2 (TIMP‐2) is a protein suspected to be crucial in numerous physiological and pathological processes such as morphogenesis, tissue remodelling and metastasis suppression. In animal models, the administration of TIMP‐2 to aged mice improved their cognitive functions. Therefore, one can hypothesize that differences in TIMP‐2 levels between blood donors and recipients might influence cognitive functions also in humans. However, the stability of TIMP‐2 during processing and storage of blood components for transfusion has not been intensively investigated so far. This study determined TIMP‐2 concentrations in fresh‐frozen plasma (FFP), erythrocyte concentrate (EC) and pathogen‐inactivated platelet concentrate (PI‐PC) depending on the donor's demographic factors age and gender.

Materials and Methods

Tissue inhibitor of metalloproteinases 2 was measured in FFP (n = 30), EC (n = 12) and PI‐PC (n = 12) using a Q‐Plex single‐plex immunoassay for chemiluminescence‐based detection. Absolute quantification of TIMP‐2 was performed with Q‐view software. Fresh umbilical cord plasma was used as a positive control.

Results

Tissue inhibitor of metalloproteinases 2 was detected in FFP (30/30 samples), EC (11/12 samples) and PI‐PC (12/12 samples). The median TIMP‐2 concentration in EC (17·2 ng/ml; range: 0–26·5 ng/ml) was significantly lower compared with FFP (63·4 ng/ml; range: 44·4–87·3 ng/ml) or PI‐PC (69·9 ng/ml; range: 39·9–83·6 ng/ml). Across all blood components, TIMP‐2 levels are comparable in male and female donors and independent of age.

Conclusion

Tissue inhibitor of metalloproteinases 2 is detectable and stable in FFP, PI‐PC and, in low concentration, EC. It can be hypothesized that TIMP‐2 will be transmitted to recipients during transfusion.

Endothelial shear stress and vascular remodeling in bioresorbable scaffold and metallic stent

BACKGROUND AND AIMS

The impact of endothelial shear stress (ESS) on vessel remodeling in vessels implanted with bioresorbable scaffold (BRS) as compared to metallic drug-eluting stent (DES) remains elusive. The aim of this study was to determine whether the relationship between ESS and remodeling patterns differs in BRS from those seen in metallic DES at 3-year follow-up.

METHODS

In the ABSORB II randomized trial, lesions were investigated by serial coronary angiography and intravascular ultrasound (IVUS). Three-dimensional reconstructions of coronary arteries post-procedure and at 3 years were performed. ESS was quantified using non-Newtonian steady flow simulation. IVUS cross-sections in device segment were matched using identical landmarks.

RESULTS

Paired ESS calculations post-procedure and at 3 years were feasible in 57 lesions in 56 patients. Post-procedure, median ESS at frame level was higher in BRS than in DES, with marginal statistical significance (0.97 ± 0.48 vs. 0.75 ± 0.39 Pa, p = 0.063). In the BRS arm, vessel area and lumen area showed larger increases in the highest tercile of median ESS post-procedure as compared to the lowest tercile. In contrast, in DES, no significant relationship between median ESS post-procedure and remodeling was observed. In multivariate analysis, smaller vessel area, larger lumen area, higher plaque burden post-procedure, and higher median ESS post-procedure were independently associated with expansive remodeling in matched frames. Only in BRS, younger age was an additional significant predictor of expansive remodeling.

CONCLUSIONS

In a subset of lesions with large plaque burden, shear stress could be associated with expansive remodeling and late lumen enlargement in BRS, while ESS had no impact on vessel dimension in metallic DES.

Cardiac tissue remodeling in healthy aging: the road to pathology

This review aims to highlight the normal physiological remodeling that occurs in healthy aging hearts, including changes that occur in contractility, conduction, valve function, large and small coronary vessels, and the extracellular matrix. These "normal" age-related changes serve as the foundation that supports decreased plasticity and limited ability for tissue remodeling during pathophysiological states such as myocardial ischemia and heart failure. This review will identify populations at greater risk for poor tissue remodeling in advanced age along with present and future therapeutic strategies that may ameliorate dysfunctional tissue remodeling in aging hearts.

Polytrauma in Older Adults Leads to Significantly Increased TIMP-1 Levels in the Early Posttraumatic Period

Background

Patients after polytrauma regularly suffer from posttraumatic immune system destabilization, which closely influences the further clinical development. Increasing age has recently been identified as an isolated risk factor for an adverse outcome after major trauma. Higher rates and intensity of acute inflammation following severe injury suggest that deregulated inflammation may contribute to these higher rates of posttraumatic morbidity and mortality in older adults. MMP-9 and TIMP-1 have been found to play a major role in posttraumatic immune disorder in a previous genome-wide mRNA analysis.

Objective

The aim of this study was to evaluate the differences in serum protein dynamics in older and younger polytraumatized adults.

Methods

Blood samples were drawn immediately within 90 minutes after trauma and subsequently after 6, 12, 24, 48, and 72 h. Serum levels of TIMP-1 and MMP-9 were quantified using ELISA. Age groups were divided according to a cutoff of 60 years.

Results

60 polytrauma patients (ISS > 16) were included (<60 years, n = 49; ≥60 years, n = 49; ≥60 years, n = 11). Serum TIMP-1 and MMP-9 levels showed a highly significant serum dynamic in young and old polytrauma patients (p < 0.001). Patients ≥ 60 years showed significantly higher overall TIMP-1 levels (p < 0.001). Patients ≥ 60 years showed significantly higher overall TIMP-1 levels (p = 0.008). TIMP-1 levels showed a significant maximum after 72 h in the older study population. MMP-9 levels were nonsignificantly higher during the whole observational period in older polytrauma patients when compared to younger patients.

Conclusion

The posttraumatic immune response is characterized by significantly higher TIMP-1 levels in older polytrauma patients. This significant association between TIMP-1 levels and patients' age indicates a more extensive immune dysregulation following major trauma in older adults.

Cardiac changes associated with vascular aging

Cardiovascular aging is a complex process of adaptive structural and functional changes over time. With advancing age, the arterial tree thickens and decreases in compliance, resulting in increased pulse wave velocity, systolic blood pressure, and left ventricular afterload. In response to these arterial changes, the myocardium remodels to maintain systolic function and diastolic filling. These adaptive mechanisms are not necessarily pathologic but increase the susceptibility for myocardial ischemia and heart failure in the presence of common age-associated comorbidities. This article reviews the pathophysiology of cardiovascular aging and discusses therapeutic interventions that may ameliorate these processes.

Matrix metalloproteinase 7 in diagnosis and differentiation of pulmonary arterial hypertension

Pulmonary arterial hypertension is a severe disease for which diagnosis often is delayed. Matrix metalloproteinases have been suggested to play a role in vascular remodeling and pulmonary hypertension development. Our aim was therefore to investigate the potential role of matrix metalloproteinases as biomarkers in diagnosis and differentiation of pulmonary arterial hypertension in relation to various causes of dyspnea and pulmonary hypertension. Using proximity extension assays, 10 matrix metalloproteinases and associated proteins were analyzed in venous plasma from healthy controls (n = 20), as well as patients diagnosed with pulmonary arterial hypertension (n = 48), chronic thromboembolic pulmonary hypertension (n = 20), pulmonary hypertension due to heart failure with preserved (n = 33) or reduced (n = 36) ejection fraction, and heart failure with reduced ejection fraction and heart failure with preserved ejection fraction without pulmonary hypertension (n = 15). Plasma levels of matrix metalloproteinase-2, -7, -9, -12 and TIMP-4 were elevated (p < 0.01) in pulmonary arterial hypertension compared to controls. Plasma levels of matrix metalloproteinase-7 were furthermore lower (p < 0.0081) in pulmonary arterial hypertension than in all the other disease groups, but higher compared to controls (p < 0.0001). Receiver operating characteristic analysis of matrix metalloproteinase-7 resulted in sensitivity of 58.7% and a specificity of 83.3% for detecting pulmonary arterial hypertension among the other disease groups. Plasma matrix metalloproteinase-7 may provide a potential new diagnostic tool to differentiate pulmonary arterial hypertension from other causes of dyspnea, including heart failure with or without pulmonary hypertension and healthy controls. Matrix metalloproteinase-7 may furthermore be involved in the development of pulmonary hypertension and pulmonary arterial hypertension. Future studies investigating the clinical usefulness of matrix metalloproteinase-7 in the differentiation and earlier diagnosis of pulmonary arterial hypertension, as well as its relationship to pulmonary arterial hypertension pathogenesis, are encouraged.

Age-dependent differences in pulmonary host responses in ARDS: a prospective observational cohort study

Background

Results from preclinical studies suggest that age-dependent differences in host defense and the pulmonary renin–angiotensin system (RAS) are responsible for observed differences in epidemiology of acute respiratory distress syndrome (ARDS) between children and adults. The present study compares biomarkers of host defense and RAS in bronchoalveolar lavage (BAL) fluid from neonates, children, adults, and older adults with ARDS.

Methods

In this prospective observational study, we enrolled mechanical ventilated ARDS patients categorized into four age groups: 20 neonates (< 28 days corrected postnatal age), 29 children (28 days–18 years), 26 adults (18–65 years), and 17 older adults (> 65 years of age). All patients underwent a nondirected BAL within 72 h after intubation. Activities of the two main enzymes of RAS, angiotensin converting enzyme (ACE) and ACE2, and levels of biomarkers of inflammation, endothelial activation, and epithelial damage were determined in BAL fluid.

Results

Levels of myeloperoxidase, interleukin (IL)-6, IL-10, and p-selectin were higher with increasing age, whereas intercellular adhesion molecule-1 was higher in neonates. No differences in activity of ACE and ACE2 were seen between the four age groups.

Conclusions

Age-dependent differences in the levels of biomarkers in lungs of ARDS patients are present. Especially, higher levels of markers involved in the neutrophil response were found with increasing age. In contrast to preclinical studies, age is not associated with changes in the pulmonary RAS.

Electronic supplementary material

The online version of this article (10.1186/s13613-019-0529-4) contains supplementary material, which is available to authorized users.

Plasma matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs and aging and lifelong exercise adaptations in ventricular and arterial stiffness

The age-associated increase in cardiac and central arterial stiffness is attenuated with lifelong (>25 years) endurance exercise in a dose-dependent manner. Remodelling of the extracellular matrix of cardiovascular structures may underpin these lifelong exercise adaptations in structural stiffness. The primary aim was to examine whether matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) levels are associated with aging and lifelong exercise-related changes in cardiac and central arterial stiffness. Plasma MMPs and TIMPs, left ventricular (LV) (LV stiffness constant) and central arterial stiffness (pulse wave velocity) were examined in healthy adults stratified into five groups based on age and lifelong weekly exercise frequency: (1) young sedentary adults (28-50 years), and older adults (>60 years) who had performed either: (a) sedentary (0-1 sessions/week), (b) casual (2-3 sessions/week), (c) committed (4-5 sessions/week) or (d) athletic (≥6 sessions/week) frequency of exercise. MMP-1 was significantly lower in young compared to older sedentary (p = 0.049). Except for TIMP-2 (p = 0.018 versus committed) and the ratio of MMP-2/TIMP-4 (p = 0.047 versus committed), MMP and TIMP expression was not significantly different in lifelong exercise groups (≥casual) compared to the older sedentary group. MMP-1, -3 had a weak positive relationship with central PWV (r = 0.17-0.25, p ≤ 0.050) but there were no significant relationships between MMPs or TIMPs and LV stiffness constant (p ≥ 0.148). In conclusion, there was not a clear or consistent difference in plasma MMPs and TIMPs with lifelong exercise dose despite exhibiting lower cardiovascular stiffness at the highest exercise levels.

Molecular changes to tendons after collagenase-induced acute tendon injury in a senescence-accelerated mouse model

BACKGROUND

Aging impairs tendon healing and is a potential risk factor for chronic tendinitis. During normal aging, tendons undergo structural and biomechanical degenerative changes, accompanied by a reduction in the number of tenocytes and changes to their properties. However, molecular changes in aged tendons under inflammatory conditions are not well understood. The present study analyzed the molecular changes in collagenase induced acute tendon injury using a senescence-accelerated mouse (SAM) model.

METHODS

SAMP6 mice were used as an aging animal model and SAMR1 mice were used as a control to represent a senescence-resistant inbred strain. All the mice used in the study were 40 weeks old. Collagenase I from Clostridium histolyticum (20 μL) was injected percutaneously to the tendon-bone junction of the Achilles tendon. Two weeks after treatment, the Achilles tendons were harvested and stained using Picrosirius Red to determine collagen expression. Real-time PCR was performed to analyze gene expression of IL-6, tenomodulin, type I and type II collagen, MMP-9, TIMP-1, and TIMP-2.

RESULTS

Collagenase injection resulted in significantly higher gene expression of IL-6 but significantly lower tenomodulin expression compared with the control in SAMP6 and SAMR1 mice. In SAMP6 mice, gene expression of type III collagen and MMP-9 was significantly higher in the collagenase-injected group compared with the control group. SAMP6 mice also showed lower expression of type I collagen, TIMP-1, and TIMP-2 in the collagenase-injected group compared with the control group. Picrosirius Red staining showed the highest expression of type III collagen in the collagenase-injected SAMP6 group compared with the other groups.

CONCLUSIONS

The collagenase-injected SAMP6 group showed higher expression of IL-6, MMP-9, and type III collagen and lower expression of type I collagen, TIMP-1, and TIMP-2, which are known to suppress metalloproteinases. The results indicate that aging may lead to dysfunction of the tendon healing process after acute tendon injury.

Netrin-1 plays a role in the effect of moderate exercise on myocardial fibrosis in rats

INTRODUCTION

This study aimed to investigate the effect of aerobic exercise on the expression of neitrin-1,DCC receptor and myocardial fibrosis in rats with acute myocardial infarction.

METHODS

Twenty-four rats were randomly divided into three groups: the sham group (n = 8), the acute myocardial infarction (AMI) model group (n = 8), and the aerobic exercise treatment after acute myocardial infarction group (ET) (n = 8). After 10 weeks, the serum levels of netrin-1, tumor necrosis factor alpha α (TNF-α), and interleukin 6 (IL-6) were measured. The expression of matrix metalloproteinase 2 and 9 (MMP2, 9), and their inhibitor, tissue inhibitor of metalloproteinase 2 (TIMP2), myocardial netrin-1, and the deleted in colorectal cancer (DCC) receptor were evaluated. Histopathological results were also evaluated. The collagen volume fraction of the myocardial tissues was also calculated.

RESULTS

Compared with the sham group, in the AMI and ET groups, left ventricular end diastolic pressure (LVEDP) were increased, while left ventricular systolic pressure (LVSP), and left ventricular pressure maximal rate of rise and fall (± dp/dtmax) were significantly decreased (P<0.05,). Compared with the AMI group, in the ET group, LVSP, and ±dp/dtmax were significantly increased while LVEDP was decreased (P<0.05). Compared with the sham group, the AMI group and ET groups showed increased levels of serum TNF-α, IL-6 and significantly reduced levels of netrin-1. Levels of TNF-α and IL-6 were significantly reduced in the ET group compared with the AMI group, whereas the level of netrin-1 was increased. The expression of myocardial MMP2 and MMP9 was significantly increased in the AMI group compared with the sham group, whereas that of myocardial netrin-1, TIMP2 and the DCC receptor, was significantly reduced. Compared with the AMI group, the ET group showed reduced expression of myocardial MMP2 and MMP9 proteins, whereas expression of myocardial netrin-1, TIMP2 and the DCC receptor, was significantly increased. The collagen volume fraction of the myocardial tissues was significantly increased in the AMI group and the ET group compared with the sham group, with a greater increase in the AMI group.

CONCLUSIONS

Aerobic exercise increased levels of serum netrin-1, myocardial netrin-1, and the DCC receptor and reduced the expression of myocardial MMP2 and MMP9 proteins, to improve the degree of fibrosis following myocardial infarction in rats.

Extracellular matrix roles in cardiorenal fibrosis: Potential therapeutic targets for CVD and CKD in the elderly

Whereas hypertension, diabetes, and dyslipidemia are age-related risk factors for cardiovascular disease (CVD) and chronic kidney disease (CKD), aging alone is an independent risk factor. With advancing age, the heart and kidney gradually but significantly undergo inflammation and subsequent fibrosis, which eventually results in an irreversible decline in organ physiology. Through cardiorenal network interactions, cardiac dysfunction leads to and responds to renal injury, and both facilitate aging effects. Thus, a comprehensive strategy is needed to evaluate the cardiorenal aging network. Common hallmarks shared across systems include extracellular matrix (ECM) accumulation, along with upregulation of matrix metalloproteinases (MMPs) including MMP-9. The wide range of MMP-9 substrates, including ECM components and inflammatory cytokines, implicates MMP-9 in a variety of pathological and age-related processes. In particular, there is strong evidence that inflammatory cell-derived MMP-9 exacerbates cardiorenal aging. This review explores the potential therapeutic targets against CVD and CKD in the elderly, focusing on ECM and MMP roles.

Cardiovascular aging: the unveiled enigma from bench to bedside

: The rapid increase in the median age of the world's population requires particular attention towards older and more fragile people. Cardiovascular risk factors, time and comorbidities play a vicious role in the development of heart failure, both with reduced and preserved ejection fraction, in the elderly. Understanding the mechanisms underlying the pathophysiological processes observed with aging is pivotal to target those patients and their therapeutic needs properly. This review aims to investigate and to dissect the main pathways leading to the aging cardiomyopathy, helping to understand the relationship from bench to bedside of the clinical phenotype.

Changes in cardiac resident fibroblast physiology and phenotype in aging

The cardiac fibroblast plays a central role in tissue homeostasis and in repair after injury. With aging, dysregulated cardiac fibroblasts have a reduced capacity to activate a canonical transforming growth factor-β-Smad pathway and differentiate poorly into contractile myofibroblasts. That results in the formation of an insufficient scar after myocardial infarction. In contrast, in the uninjured aged heart, fibroblasts are activated and acquire a profibrotic phenotype that leads to interstitial fibrosis, ventricular stiffness, and diastolic dysfunction, all conditions that may lead to heart failure. There is an apparent paradox in aging, wherein reparative fibrosis is impaired but interstitial, adverse fibrosis is augmented. This could be explained by analyzing the effectiveness of signaling pathways in resident fibroblasts from young versus aged hearts. Whereas defective signaling by transforming growth factor-β leads to insufficient scar formation by myofibroblasts, enhanced activation of the ERK1/2 pathway may be responsible for interstitial fibrosis mediated by activated fibroblasts. Listen to this article's corresponding podcast at https://ajpheart.podbean.com/e/fibroblast-phenotypic-changes-in-the-aging-heart/ .

Inhibitor of lysyl oxidase improves cardiac function and the collagen/MMP profile in response to volume overload

The cardiac extracellular matrix is a complex architectural network that serves many functions, including providing structural and biochemical support to surrounding cells and regulating intercellular signaling pathways. Cardiac function is directly affected by extracellular matrix (ECM) composition, and alterations of the ECM contribute to the progression of heart failure. Initially, collagen deposition is an adaptive response that aims to preserve tissue integrity and maintain normal ventricular function. However, the synergistic effects of proinflammatory and profibrotic responses induce a vicious cycle, which causes excess activation of myofibroblasts, significantly increasing collagen deposition and accumulation in the matrix. Furthermore, excess synthesis and activation of the enzyme lysyl oxidase (LOX) during disease increases collagen cross-linking, which significantly increases collagen resistance to degradation by matrix metalloproteinases (MMPs). In the present study, the aortocaval fistula model of volume overload (VO) was used to determine whether LOX inhibition could prevent adverse changes in the ECM and subsequent cardiac dysfunction. The major findings from this study were that LOX inhibition 1) prevented VO-induced increases in left ventricular wall stress; 2) partially attenuated VO-induced ventricular hypertrophy; 3) completely blocked the increases in fibrotic proteins, including collagens, MMPs, and their tissue inhibitors; and 4) prevented the VO-induced decline in cardiac function. It remains unclear whether a direct interaction between LOX and MMPs exists; however, our experiments suggest a potential link between the two because LOX inhibition completely attenuated VO-induced increases in MMPs. Overall, our study demonstrated key cardioprotective effects of LOX inhibition against adverse cardiac remodeling due to chronic VO. NEW & NOTEWORTHY Although the primary role of lysyl oxidase (LOX) is to cross-link collagens, we found that elevated LOX during cardiac disease plays a key role in the progression of heart failure. Here, we show that inhibition of LOX in volume-overloaded rats prevented the development of cardiac dysfunction and improved ventricular collagen and matrix metalloproteinase/tissue inhibitor of metalloproteinase profiles.

Combined Inflammation and Metabolism Biomarker Indices of Robust and Impaired Physical Function in Older Adults

OBJECTIVES

To determine whether combinations of inflammatory markers are related to physical function.

DESIGN AND SUBJECTS

secondary analysis of baseline of three observational studies of community-dwelling older adults MEASUREMENTS: The baseline data from 3 cohorts of older adults with different health and disease status were employed. Twenty markers of inflammation and metabolism were individually assessed for correlation with usual gait speed and were separated into robust and impairment quartiles. For the robustness and impairment indices, individual markers were selected using step-wise regression over bootstrapping iterations, and regression coefficients were estimated for the markers individually and collectively as an additive score.

RESULTS

We developed a robustness index involving 6 markers and an impairment index involving 8 markers corresponding positively and negatively with gait speed. Two markers, glycine and tumor necrosis factor receptor 1 (TNFR1), appeared only in the robustness index, and TNFR2; regulated on activation, normal T-cell expressed and secreted; the amino acid factor; and matrix metallopeptidase 3; appeared only in the impairment index.

CONCLUSION

Indices of biomarkers were associated with robust and impaired physical performance but differ, in composition suggesting potential biological differences that may contribute to robustness and impairment.

Macrophage migration inhibitory factor is critical for dengue NS1-induced endothelial glycocalyx degradation and hyperpermeability

Vascular leakage is one of the salient characteristics of severe dengue. Nonstructural protein 1 (NS1) of dengue virus (DENV) can stimulate endothelial cells to secrete endothelial hyperpermeability factor, macrophage migration inhibitory factor (MIF), and the glycocalyx degradation factor heparanase 1 (HPA-1). However, it is unclear whether MIF is directly involved in NS1-induced glycocalyx degradation. In this study, we observed that among NS1, MIF and glycocalyx degradation-related molecules, the HPA-1, metalloproteinase 9 (MMP-9) and syndecan 1 (CD138) serum levels were all increased in dengue patients, and only NS1 and MIF showed a positive correlation with the CD138 level in severe patients. To further characterize and clarify the relationship between MIF and CD138, we used recombinant NS1 to stimulate human cells in vitro and challenge mice in vivo. Our tabulated results suggested that NS1 stimulation could induce human endothelial cells to secrete HPA-1 and immune cells to secrete MMP-9, resulting in endothelial glycocalyx degradation and hyperpermeability. Moreover, HPA-1, MMP-9, and CD138 secretion after NS1 stimulation was blocked by MIF inhibitors or antibodies both in vitro and in mice. Taken together, these results suggest that MIF directly engages in dengue NS1-induced glycocalyx degradation and that targeting MIF may represent a possible therapeutic approach for preventing dengue-induced vascular leakage.

Ginsenoside Re prevents angiotensin II-induced gap-junction remodeling by activation of PPARγ in isolated beating rat atria

AIMS

Ginsenoside Re (G-Re), a major ginsenoside in ginseng, has many beneficial pharmacological effects on negative cardiac contractility, electromechanical alternans, antiarrhythmia, angiogenic regeneration and cardiac electrophysiological function. However, effects of G-Re on gap-junction remodeling are unclear. Therefore, this study aimed to investigate the effect of G-Re on angiotensin II (Ang II)-induced downregulation of connexin-40 (CX40) and -43 (CX43) in beating rat left atria.

MAIN METHODS

In this study, the isolated perfused beating rat atrial model was used and atrial gap-junction remodeling was induced by Ang II. In vivo hemodynamic experiments were analyzed with a biological recorder. Changes in protein expression were analyzed by western blot.

KEY FINDINGS

G-Re attenuated Ang II-induced abnormal changes in heart rate, MAP, LVESP, LVEDP, +dp/dt max, -dp/dt min, P wave amplitude, P-R interval and P wave length. This indicated a dose-dependent preventive role against Ang II-induced hyper hemodynamics in rats. Atrial activities of p38 mitogen-activated protein kinase (MAPK), nuclear factor kappa-B (NF-κB) and activator protein 1 (AP-1) were significantly increased by Ang II, as was expression of atrial collagen I and matrix metalloproteinase 2 (MMP2). Atrial CX40 and CX43 expression was downregulated by Ang II. These Ang II-induced atrial effects were blocked by G-Re, as well as rosiglitazone, an agonist of peroxisome proliferator-activated receptor γ (PPARγ), in a dose-dependent manner. However, this inhibition was abolished by the PPARγ inhibitor GW9662.

SIGNIFICANCE

G-Re may suppress Ang II-induced downregulation of CX40 and CX43, by activating PPARγ signaling, in isolated perfused beating rat atria.

Cardiac fibrosis in the ageing heart: Contributors and mechanisms

Cardiac fibrosis refers to an excessive deposition of extracellular matrix (ECM) in cardiac tissue. Fibrotic tissue is stiffer and less compliant, resulting in subsequent cardiac dysfunction and heart failure. Cardiac fibrosis in the ageing heart may involve activation of fibrogenic signalling and inhibition of anti-fibrotic signalling, leading to an imbalance of ECM turnover. Excessive accumulation of ECM such as collagen in older patients contributes to progressive ventricular dysfunction. Overexpression of collagen is derived from various sources, including higher levels of fibrogenic growth factors, proliferation of fibroblasts and cellular transdifferentiation. These may be triggered by factors, such as oxidative stress, inflammation, hypertension, cellular senescence and cell death, contributing to age-related fibrotic cardiac remodelling. In this review, we will discuss the fibrogenic contributors in age-related cardiac fibrosis, and the potential mechanisms by which fibrogenic processes can be interrupted for therapeutic intent.

Advances in Therapeutic Approaches to Extend Healthspan: a perspective from the 2nd Scripps Symposium on the Biology of Aging

The 2^nd Scripps Florida Symposium on The Biology of Aging entitled ‘Advances in Therapeutic Approaches to Extend Healthspan’ was held on January 22^nd–25^th, 2017 at The Scripps Research Institute in Jupiter, Florida. The meeting highlighted a variety of therapeutic approaches in animal models of aging that either are or soon will be in clinic trials. For example, drugs targeting senescent cells, metformin, rapalogs, NAD precursors, young plasma, mitochondrial‐targeted free radical scavengers, stem cells, and stem cell factors all have shown significant preclinical efficacy. This perspective, based on presentations and discussions at the symposium, outlines the current and future state of development of therapeutic approaches to extend human healthspan.

Reduced collagen accumulation and augmented MMP-2 activity in left ventricle of old rats submitted to high-intensity resistance training

Progressive fibrosis is a hallmark of the aging heart. Age-related fibrosis is modulated by endurance exercise training; however, little is known concerning the influence of resistance training (RT). Therefore we investigated the chronic effects of high-intensity RT on age-associated alterations of left ventricle (LV) structure, collagen content, matrix metalloproteinase-2 (MMP-2), and extracellular matrix-related gene expression, including transforming growth factor-β (TGF-β). Young adult (3 mo) and aged (21 mo) male Wistar rats were submitted to a RT protocol (ladder climbing with 65, 85, 95, and 100% load), three times a week for 12 wk. Forty-eight hours posttraining, arterial systolic and diastolic pressure, LV end-diastolic pressure (LVEDP) and dP/dt were recorded. LV morphology, collagen deposition, and gene expression of type I (COL-I) and type III (COL-III) collagen, MMP-2, tissue inhibitor of metalloproteinases-1 (TIMP-1), and TGF-β1 were analyzed by quantitative reverse transcriptase-PCR. MMP-2 content was assessed by zymography. Increased collagen deposition was observed in LV from aged rats. These parameters were modulated by RT and were associated with increased MMP-2 activity and decreased COL-I, TGF-β1, and TIMP-1 mRNA content. Despite the effect of RT on collagen accumulation, there was no improvement on LVEDP and maximal negative LV dP/dt of aged rats. Cardiomyocyte diameter was preserved in all experimental conditions. In conclusion, RT attenuated age-associated collagen accumulation, concomitant to the increase in MMP-2 activity and decreased expression of COL-I, TGF-β1, and TIMP-1 in LV, illustrating a cardioprotective effect of RT on ventricular structure and function.NEW & NOTEWORTHY We demonstrated the beneficial resistance-training effect against age-related left ventricle collagen accumulation in the left ventricle, which was associated with decreased type I collagen (COL-I), transforming growth factor-β1 (TGF-β1), and tissue inhibitor of metalloproteinases-1 (TIMP-1) gene expression and matrix metalloproteinase-2 (MMP-2) activity. Our findings suggest for the first time the potential effects of resistance training in modulating collagen accumulation and possibly fibrosis in the aging heart.

Effects of age-related shifts in cellular function and local microenvironment upon the innate immune response to implants

The host macrophage response is now well recognized as a predictor of the success or failure of biomaterial implants following placement. More specifically, shifts from an "M1" pro-inflammatory towards a more "M2-like" anti-inflammatory macrophage polarization profile have been shown to result in enhanced material integration and/or tissue regeneration downstream. As a result, a number of biomaterials-based approaches to controlling macrophage polarization have been developed. However, the ability to promote such activity is predicated upon an in-depth, context-dependent understanding of the host response to biomaterials. Recent work has shown the impacts of both tissue location and tissue status (i.e. underlying pathology) upon the host innate immune response to implants, representing a departure from a focus upon implant material composition and form. Thus, the ideas of "biocompatibility," the host macrophage reaction, and ideal material requirements and modification strategies may need to be revisited on a patient, tissue, and disease basis. Immunosenescence, dysregulation of macrophage function, and delayed resolution of immune responses in aged individuals have all been demonstrated, suggesting that the host response to biomaterials in aged individuals should differ from that in younger individuals. However, despite the increasing usage of implantable medical devices in aged patients, few studies examining the effects of aging upon the host response to biomaterials and the implications of this response for long-term integration and function have been performed. The objective of the present manuscript is to review the putative effects of aging upon the host response to implanted materials and to advance the hypothesis that age-related changes in the local microenvrionement, with emphasis on the extracellular matrix, play a previously unrecognized role in determining the host response to implants.

Dissecting the Role of the Extracellular Matrix in Heart Disease: Lessons from the Drosophila Genetic Model

The extracellular matrix (ECM) is a dynamic scaffold within organs and tissues that enables cell morphogenesis and provides structural support. Changes in the composition and organisation of the cardiac ECM are required for normal development. Congenital and age-related cardiac diseases can arise from mis-regulation of structural ECM proteins (Collagen, Laminin) or their receptors (Integrin). Key regulators of ECM turnover include matrix metalloproteinases (MMPs) and their inhibitors, tissue inhibitors of matrix metalloproteinases (TIMPs). MMP expression is increased in mice, pigs, and dogs with cardiomyopathy. The complexity and longevity of vertebrate animals makes a short-lived, genetically tractable model organism, such as Drosophila melanogaster, an attractive candidate for study. We survey ECM macromolecules and their role in heart development and growth, which are conserved between Drosophila and vertebrates, with focus upon the consequences of altered expression or distribution. The Drosophila heart resembles that of vertebrates during early development, and is amenable to in vivo analysis. Experimental manipulation of gene function in a tissue- or temporally-regulated manner can reveal the function of adhesion or ECM genes in the heart. Perturbation of the function of ECM proteins, or of the MMPs that facilitate ECM remodelling, induces cardiomyopathies in Drosophila, including cardiodilation, arrhythmia, and cardia bifida, that provide mechanistic insight into cardiac disease in mammals.

Ageing related down-regulation of myocardial connexin-43 and up-regulation of MMP-2 may predict propensity to atrial fibrillation in experimental animals

Mechanisms underlying atrial fibrillation (AF), the most common cardiac arrhythmia, particularly in aged population, are not fully elucidated. We have previously shown an increased propensity of old guinea pigs (GPs) heart to inducible AF when comparing to young animals. This study aimed to verify our hypothesis that susceptibility of aged heart to AF may be attributed to abnormalities in myocardial connexin-43 (Cx43) and extracellular matrix that affect cardiac electrical properties. Experiments were conducted on male and female 4-week-old and 24-week-old GPs. Atrial tissue was processed for analysis of Cx43 topology using immunohistochemistry, expression of Cx43 protein using immunobloting, and expression of mRNA of Cx43 and extracellular matrix metalloproteinase-2 (MMP-2) using real time PCR. Immunohistochemistry revealed uniform Cx43 distribution predominantly on lateral sides of the cardiomyocytes of young male and female GP atria. In contrast, non-uniform distribution, mislocalization and reduced immunolabeling of Cx43 were detected in atria of old GPs. In parallel, the atrial tissue levels of Cx43 mRNA were significantly decreased, while mRNA expression of MMP-2 was significantly increased in old versus young GPs. The changes were more pronounced in old GPs males comparing to females. Findings indicate that age-related down-regulation of atrial Cx43 and up-regulation of MMP-2 as well as disordered Cx43 distribution can facilitate development of AF in old guinea pig hearts.