Mechanisms underlying the cardiac antifibrotic effects of losartan metabolites

Circulating collagen type I fragments as specific biomarkers of cardiovascular outcome risk: Where are the opportunities?

Collagen type I (COL1) is the most abundant protein in the human body and is a main component in the extracellular matrix. The COL1 structure vastly influences normal tissue homeostasis, and changes in the matrix drive progression in multiple diseases. Cardiovascular diseases (CVD) are the leading cause of mortality and morbidity in many Western countries; alterations in the extracellular matrix turnover processes, including COL1, are known to influence the pathophysiological processes leading to CVD outcome. Peptides reflecting COL1 formation and degradation have been established and explored for over two decades in CVD. This review aims to combine and assess the evidence for using COL1-derived circulating peptides as biomarkers in CVD. Secondly, the review identifies existing pitfalls, and evaluates future opportunities for improving the technical characteristics and performance of the biomarkers for implementation in the clinical setting.

Comparative Efficacy of β-Carotene and Losartan Against Isoproterenol-Induced Cardiac Fibrosis: An Experimental and Computational Studies

OBJECTIVE

β-carotene, a vitamin A precursor is reported to inhibit molecular pathways cardinal to pathogenesis of fibrotic tissue alterations and in this study, the effectiveness of 14 days oral administration of β-carotene (10, 20, and 40 mg/kg/day) in the cardiac fibrosis (CF) in rats was studied and explored the mechanisms through network pharmacology.

METHODS

CF was induced by isoproterenol (ISO) 6 mg/kg/SC from day 1 to day 7. Losartan (LOS) 10 mg/kg/day/p.o. served as the standard. Both β-carotene and LOS were administered from day 1 to 14. On the 15th day, ECG and blood pressure (systolic, diastolic and mean) were recorded in the anesthetized rats followed by their euthanasia. The extent of cardiac fibrosis in the isolated hearts was determined using heart coefficient, tissue levels of hydroxyproline, histological examination. The oxidative stress in cardiac tissue was estimated, as GSH, SOD, catalase, MDA and NO. β-carotene targeted proteins pathway, process, and functional enrichment analysis were explored through network pharmacology.

RESULTS

β-carotene dose-dependently mitigated the biochemical and histological changes induced by ISO in heart tissues. In ECG, it restored ST height, QT, and QRS intervals. Additionally, it normalized systolic, diastolic, and mean arterial pressures. The reduction in heart coefficient suggests β-carotene's potential to inhibit collagen deposition in heart tissue. β-carotene normalized oxidative stress markers, and hydroxyproline levels. All other biochemical parameters were restored to normal levels with β-carotene treatment. β-carotene 40 mg/kg dose showed comparable effect to that of LOS 10 mg/kg. β-carotene modulated IL-17, TNF, NF-kappa B, HIF-1, Sphingolipid, Relaxin, Adipocytokine, cAMP, Toll-like receptor, MAPK, PI3K-Akt, cGMP-PKG, VEGF, Ras, and PPAR signaling pathways.

CONCLUSIONS

β-carotene dose-dependently protects against ISO-induced CF in rats, with 40 mg/kg as an effective antifibrotic dose.

Non-invasive estimation of left ventricular chamber stiffness using cardiovascular magnetic resonance and echocardiography

BACKGROUND

Preclinical studies exploring the underlying mechanisms of elevated left ventricular (LV) chamber stiffness play a crucial role in developing new therapeutic strategies. However, there is a lack of systematic evaluation of imaging biomarkers of diastolic function against gold standard assessment of LV chamber stiffness in rodents. Therefore, we aimed to evaluate imaging biomarkers of diastolic function from cardiovascular magnetic resonance (CMR) and echocardiography in predicting the slope of the end-diastolic pressure-volume relationship (EDPVR) in rats.

METHODS

Sprague Dawley rats with varying degrees of myocardial stiffness induced by aortic constriction (n=38) and healthy controls (n=9) underwent echocardiography and CMR at approximately 13 weeks post-operation. Imaging biomarkers of diastolic function were evaluated for their ability to predict the EDPVR slope from pressure-volume recordings using regression analysis and receiver operating characteristics analysis.

RESULTS

Both CMR and echocardiographic imaging biomarkers, in particular those related to the left atrium and mitral flow, were able to predict the EDPVR slope in a rat model with varying stiffness. From CMR, native T1 values, peak early diastolic longitudinal strain rate (SRe(long)) and E/SRe(long), left atrial (LA) ejection fraction, isovolumetric relaxation time (IVRT), E/A and peak LA strain, correlated best with the EDPVR slope (|r|=0.54-0.72). From echocardiography, E/A, E, LA diameter, e'/a', E/SRe(long) and IVRT correlated with the EDPVR slope (|r|=0.49-0.67), while E/e', e' and E-wave deceleration time demonstrated poor correlation (|r|=0.17-0.27). Receiver operating characteristics analysis indicated better performance of CMR imaging biomarkers than echocardiography in predicting increased EDPVR slope.

CONCLUSIONS

Several diastolic imaging biomarkers commonly employed in preclinical studies have poor ability to predict cardiac chamber stiffness. Our study identifies several imaging biomarkers obtained from both echocardiography and CMR that are able to estimate LV chamber stiffness non-invasively, providing an important tool for future mechanistic research on myocardial stiffness.

Reversing Decline in Aging Muscles: Expected Trends, Impacts and Remedies

Background: Age-related decline in musculoskeletal function is a significant concern, particularly in Western countries facing demographic shifts and increased healthcare demands. This review examines the typical trajectories of musculoskeletal deterioration with age and evaluates the effectiveness of various interventions in preventing or reversing these changes. Methods: The review analyzes documented rates of decline across multiple parameters, including muscle mass, Type II muscle fiber reduction, and decreased motor unit firing rates. It examines evidence from studies on targeted interventions aimed at reversing these trends or preventing further decline. Results: The evidence suggests that multimodal interventions, including strength training can effectively maintain or improve physical function in aging adults. These interventions have shown potential in altering the trajectory of age-related decline in musculoskeletal function. Conclusions. The findings of this review have important implications for healthcare providers and policymakers in addressing the challenges of an aging population. By providing a framework for understanding and addressing age-related physical decline through evidence-based interventions, this review offers potential strategies for reducing healthcare costs and improving the quality of life for older adults.

Perioperative Losartan Is Associated With Similar Rates of Additional Surgical Procedures for Postoperative Shoulder Stiffness After Primary Arthroscopic Rotator Cuff Repair but Lower Rates of Secondary Debridement and Repair

PURPOSE

To compare the rate of additional shoulder surgery related to postoperative stiffness or tendon healing after primary rotator cuff repair between patients with a losartan prescription and without a losartan prescription.

METHODS

The International Classification of Diseases, Tenth Revision, code M75.1 was used to identify all patients in the TriNetX Research Network with a rotator cuff tear diagnosis who underwent arthroscopic rotator cuff repair between January 1, 2015, and December 31, 2021. Patients were stratified into the losartan group (LG) and nonlosartan group (NLG) on the basis of whether they had a coded prescription for losartan within 1 year before surgery or 3 months after surgery. The 2 cohorts were propensity scored and matched to reduce confounding biases. Specifically, cohorts were matched on the basis of age, gender, obesity, nicotine use, hyperlipidemia, diabetes, hypertensive diseases, ischemic heart disease, heart failure and valvular disease, and peripheral arterial disease. The incidence of additional shoulder surgeries associated with stiffness and rotator cuff healing was analyzed and compared at 1-year and 2-year time points.

RESULTS

After propensity score matching, both the LG and NLG contained 3,970 patients. There was no difference in the rate of lysis of adhesions or manipulation under anesthesia at 1-or 2-year postoperatively between patients in the LG and LG. Patients in the LG were less likely undergo arthroscopic debridement (odds ratio 0.71; confidence interval 0.56-0.91; P = .006) and rotator cuff repair (odds ratio 0.71; confidence interval 0.58-0.87; P = .001) 1-year postoperatively than patients in the NLG group. At 1-year postoperatively, there was no difference in the rate of arthroplasty, arthroscopic synovectomy, and diagnostic arthroscopy between groups. At 2-year postoperatively, there was no difference in the rate of rotator cuff repair, arthroplasty, arthroscopic debridement, synovectomy, and diagnostic arthroscopy between groups.

CONCLUSIONS

Patients undergoing arthroscopic rotator cuff repair with or without a perioperative prescription for losartan had no significant difference in the rate of lysis of adhesions or manipulation under anesthesia at 1- or 2-year postoperatively, indicating that the antifibrotic properties of losartan may not have a clinically significant impact on shoulder stiffness after arthroscopic rotator cuff repair. However, patients with a prescription for losartan were less likely to undergo additional arthroscopic debridement and rotator cuff repair 1-year postoperatively than a matched cohort of patients without a prescription for losartan.

LEVEL OF EVIDENCE

Level III, case control study.

Angiotensin II receptor blockers and their applications in orthopaedic surgery and musculoskeletal medicine

Angiotensin II receptor blockers (ARBs) are commonly prescribed for hypertension and heart failure, and have well-described antifibrotic properties throughout medical literature. The etiology and pathogenesis of fibrosis is biologically complex with a multitude of factors playing a role in the process. Consequently, pathologic fibrosis may be significant within orthopaedics contributing to post-operative stiffness and, ultimately, negative patient outcomes. The pharmacology of ARBs has been described to combat fibrosis in preclinical settings, while the literature of ARBs antifibrotic properties in relation to orthopaedics remains scarce. However, fibrosis is one of the primary factors contributing to tissue healing and functional recovery in the field of orthopaedic surgery. Fibrosis has specifically been described in relation to shoulder surgery, knee arthroplasty and hip arthroscopy. As such, outcomes of various orthopaedic surgeries are dependent upon a balance between tissue healing and stiffness, both of which may be mediated by a fibrotic response. Importantly, ARBs have recently emerged as a potential therapy to combat fibrosis-mediated stiffness in orthopaedic surgery patients. Thus, the following review article seeks to highlight the basic and clinical science of ARBs with emphasis on their implications and indications for orthopaedic surgery and musculoskeletal medicine.

Periostin regulates lysyl oxidase through ERK1/2 MAPK-dependent serum response factor in activated cardiac fibroblasts

Collagen crosslinking, mediated by lysyl oxidase, is an adaptive mechanism of the cardiac repair process initiated by cardiac fibroblasts postmyocardial injury. However, excessive crosslinking leads to cardiac wall stiffening, which impairs the contractile properties of the left ventricle and leads to heart failure. In this study, we investigated the role of periostin, a matricellular protein, in the regulation of lysyl oxidase in cardiac fibroblasts in response to angiotensin II and TGFβ1. Our results indicated that periostin silencing abolished the angiotensin II and TGFβ1-mediated upregulation of lysyl oxidase. Furthermore, the attenuation of periostin expression resulted in a notable reduction in the activity of lysyl oxidase. Downstream of periostin, ERK1/2 MAPK signaling was found to be activated, which in turn transcriptionally upregulates the serum response factor to facilitate the enhanced expression of lysyl oxidase. The periostin-lysyl oxidase association was also positively correlated in an in vivo rat model of myocardial infarction. The expression of periostin and lysyl oxidase was upregulated in the collagen-rich fibrotic scar tissue of the left ventricle. Remarkably, echocardiography data showed a reduction in the left ventricular wall movement, ejection fraction, and fractional shortening, indicative of enhanced stiffening of the cardiac wall. These findings shed light on the mechanistic role of periostin in the collagen crosslinking initiated by activated cardiac fibroblasts. Our findings signify periostin as a possible therapeutic target to reduce excessive collagen crosslinking that contributes to the structural remodeling associated with heart failure.

The effect of losartan on the development of post-traumatic joint stiffness in a rat model

Post-traumatic joint stiffness (PTJS) is accompanied by a multidimensional disturbance of joint architecture. Pharmacological approaches represent promising alternatives as the traumatic nature of current therapeutic standards may lead to PTJS' progression. Losartan is an auspicious candidate, as it has demonstrated an antifibrotic effect in other organs. Forty-eight Sprague Dawley rats were randomized into equally sized losartan or control groups. After a standardized knee trauma, the joint was immobilized for either 2 weeks (n = 16), 4 weeks (n = 16) or 4 weeks with re-mobilization for an additional 4 weeks (n = 16). Pharmacotherapy with losartan or placebo (30 mg/kg/day) was initiated on the day of trauma and continued for the entire course. Joint contracture was measured alongside histological and molecular biological assessments. There were no significant biomechanical changes in joint contracture over time, comparing short-term (2 weeks) with long-term losartan therapy (4 weeks). However, comparing the formation of PTJS with that of the control, there was a trend toward improvement of joint mobility of 10.5° (p 0.09) under the influence of losartan. During the re-mobilization phase, no significant effect of losartan on range of motion (ROM) was demonstrated. At a cellular level, losartan significantly reduced myofibroblast counts by up to 72 % (4 weeks, p ≤ 0.001) without effecting the capsular configuration. Differences in expression levels of profibrotic factors (TGF-β, CTGF, Il-6) were most pronounced at week 4. The antifibrotic properties of losartan are not prominent enough to completely prevent the development of PTJS after severe joint injury.

Effects of Adjunct Antifibrotic Treatment within a Regenerative Rehabilitation Paradigm for Volumetric Muscle Loss

The use of a rehabilitation approach that promotes regeneration has the potential to improve the efficacy of pro-regenerative therapies and maximize functional outcomes in the treatment of volumetric muscle loss (VML). An adjunct antifibrotic treatment could further enhance functional gains by reducing fibrotic scarring. This study aimed to evaluate the potential synergistic effects of losartan, an antifibrotic pharmaceutical, paired with a voluntary wheel running rehabilitation strategy to enhance a minced muscle graft (MMG) pro-regenerative therapy in a rodent model of VML. The animals were randomly assigned into four groups: (1) antifibrotic with rehabilitation, (2) antifibrotic without rehabilitation, (3) vehicle treatment with rehabilitation, and (4) vehicle treatment without rehabilitation. At 56 days, the neuromuscular function was assessed, and muscles were collected for histological and molecular analysis. Surprisingly, we found that the losartan treatment decreased muscle function in MMG-treated VML injuries by 56 days, while the voluntary wheel running elicited no effect. Histologic and molecular analysis revealed that losartan treatment did not reduce fibrosis. These findings suggest that losartan treatment as an adjunct therapy to a regenerative rehabilitation strategy negatively impacts muscular function and fails to promote myogenesis following VML injury. There still remains a clinical need to develop a regenerative rehabilitation treatment strategy for traumatic skeletal muscle injuries. Future studies should consider optimizing the timing and duration of adjunct antifibrotic treatments to maximize functional outcomes in VML injuries.

Cardiac Fibrosis in the Pressure Overloaded Left and Right Ventricle as a Therapeutic Target

Myocardial fibrosis is a remodeling process of the extracellular matrix (ECM) following cardiac stress. "Replacement fibrosis" is a term used to describe wound healing in the acute phase of an injury, such as myocardial infarction. In striking contrast, ECM remodeling following chronic pressure overload insidiously develops over time as "reactive fibrosis" leading to diffuse interstitial and perivascular collagen deposition that continuously perturbs the function of the left (L) or the right ventricle (RV). Examples for pressure-overload conditions resulting in reactive fibrosis in the LV are systemic hypertension or aortic stenosis, whereas pulmonary arterial hypertension (PAH) or congenital heart disease with right sided obstructive lesions such as pulmonary stenosis result in RV reactive fibrosis. In-depth phenotyping of cardiac fibrosis has made it increasingly clear that both forms, replacement and reactive fibrosis co-exist in various etiologies of heart failure. While the role of fibrosis in the pathogenesis of RV heart failure needs further assessment, reactive fibrosis in the LV is a pathological hallmark of adverse cardiac remodeling that is correlated with or potentially might even drive both development and progression of heart failure (HF). Further, LV reactive fibrosis predicts adverse outcome in various myocardial diseases and contributes to arrhythmias. The ability to effectively block pathological ECM remodeling of the LV is therefore an important medical need. At a cellular level, the cardiac fibroblast takes center stage in reactive fibrotic remodeling of the heart. Activation and proliferation of endogenous fibroblast populations are the major source of synthesis, secretion, and deposition of collagens in response to a variety of stimuli. Enzymes residing in the ECM are responsible for collagen maturation and cross-linking. Highly cross-linked type I collagen stiffens the ventricles and predominates over more elastic type III collagen in pressure-overloaded conditions. Research has attempted to identify pro-fibrotic drivers causing fibrotic remodeling. Single key factors such as Transforming Growth Factor β (TGFβ) have been described and subsequently targeted to test their usefulness in inhibiting fibrosis in cultured fibroblasts of the ventricles, and in animal models of cardiac fibrosis. More recently, modulation of phenotypic behaviors like inhibition of proliferating fibroblasts has emerged as a strategy to reduce pathogenic cardiac fibroblast numbers in the heart. Some studies targeting LV reactive fibrosis as outlined above have successfully led to improvements of cardiac structure and function in relevant animal models. For the RV, fibrosis research is needed to better understand the evolution and roles of fibrosis in RV failure. RV fibrosis is seen as an integral part of RV remodeling and presents at varying degrees in patients with PAH and animal models replicating the disease of RV afterload. The extent to which ECM remodeling impacts RV function and thus patient survival is less clear. In this review, we describe differences as well as common characteristics and key players in ECM remodeling of the LV vs. the RV in response to pressure overload. We review pre-clinical studies assessing the effect of anti-fibrotic drug candidates on LV and RV function and their premise for clinical testing. Finally, we discuss the mode of action, safety and efficacy of anti-fibrotic drugs currently tested for the treatment of left HF in clinical trials, which might guide development of new approaches to target right heart failure. We touch upon important considerations and knowledge gaps to be addressed for future clinical testing of anti-fibrotic cardiac therapies.

Investigation of the Antihypertrophic and Antifibrotic Effects of Losartan in a Rat Model of Radiation-Induced Heart Disease

Radiation-induced heart disease (RIHD) is a potential late side-effect of thoracic radiotherapy resulting in left ventricular hypertrophy (LVH) and fibrosis due to a complex pathomechanism leading to heart failure. Angiotensin-II receptor blockers (ARBs), including losartan, are frequently used to control heart failure of various etiologies. Preclinical evidence is lacking on the anti-remodeling effects of ARBs in RIHD, while the results of clinical studies are controversial. We aimed at investigating the effects of losartan in a rat model of RIHD. Male Sprague-Dawley rats were studied in three groups: (1) control, (2) radiotherapy (RT) only, (3) RT treated with losartan (per os 10 mg/kg/day), and were followed for 1, 3, or 15 weeks. At 15 weeks post-irradiation, losartan alleviated the echocardiographic and histological signs of LVH and fibrosis and reduced the overexpression of chymase, connective tissue growth factor, and transforming growth factor-beta in the myocardium measured by qPCR; likewise, the level of the SMAD2/3 protein determined by Western blot decreased. In both RT groups, the pro-survival phospho-AKT/AKT and the phospho-ERK1,2/ERK1,2 ratios were increased at week 15. The antiremodeling effects of losartan seem to be associated with the repression of chymase and several elements of the TGF-β/SMAD signaling pathway in our RIHD model.

Irbesartan, an angiotensin II type 1 receptor blocker, inhibits colitis-associated tumourigenesis by blocking the MCP-1/CCR2 pathway

The introduction of anti-inflammatory therapies has enabled substantial improvement of disease activity in patients with inflammatory bowel diseases (IBD). However, IBD can lead to serious complications such as intestinal fibrosis and colorectal cancer. Therefore, novel therapies reducing the development of these complications are needed. Angiotensin II (Ang II) promotes tissue inflammation by stimulating the production of monocyte chemoattractant protein-1 (MCP-1) or proinflammatory cytokines. It plays a pivotal role in IBD progression. Although blockade of Ang II has been reported to ameliorate experimental colitis and reduce colorectal cancer risk, the cellular and molecular mechanisms remain poorly understood. Our previous work showed that irbesartan, an Ang II type 1 receptor blocker, reduced the number of C-C chemokine receptor 2-positive (CCR2+) monocytic cells in the inflamed pancreas. This study aimed to investigate the possible antifibrotic and antitumour effects of irbesartan using the azoxymethane/dextran sodium sulphate mouse model. Irbesartan suppressed MCP-1 production and the accumulation of Ly6C+CCR2+ monocytes and fibrocytes in the inflamed colon, downregulated the expression of type 1 collagen and matrix metalloproteinase 9 and inhibited the development of intestinal fibrosis and tumours. Our observations suggest that blocking the MCP-1/CCR2 pathway using irbesartan might be beneficial in preventing colitis-associated colon tumours.

Therapeutic and diagnostic targeting of fibrosis in metabolic, proliferative and viral disorders

Fibrosis is a common denominator in many pathologies and crucially affects disease progression, drug delivery efficiency and therapy outcome. We here summarize therapeutic and diagnostic strategies for fibrosis targeting in atherosclerosis and cardiac disease, cancer, diabetes, liver diseases and viral infections. We address various anti-fibrotic targets, ranging from cells and genes to metabolites and proteins, primarily focusing on fibrosis-promoting features that are conserved among the different diseases. We discuss how anti-fibrotic therapies have progressed over the years, and how nanomedicine formulations can potentiate anti-fibrotic treatment efficacy. From a diagnostic point of view, we discuss how medical imaging can be employed to facilitate the diagnosis, staging and treatment monitoring of fibrotic disorders. Altogether, this comprehensive overview serves as a basis for developing individualized and improved treatment strategies for patients suffering from fibrosis-associated pathologies.

Losartan to reduce inflammation and fibrosis endpoints in HIV disease

BACKGROUND

Persistent inflammation and incomplete immune recovery among persons with HIV (PHIV) are associated with increased disease risk. We hypothesized that the angiotensin receptor blocker (ARB) losartan would reduce inflammation by mitigating nuclear factor (NF)κB responses and promote T-cell recovery via inhibition of transforming growth factor-beta (TGFβ)-mediated fibrosis.

METHODS

Losartan (100 mg) versus placebo over 12 months was investigated in a randomized (1 : 1) placebo-controlled trial, among PHIV age at least 50 years, receiving antiretroviral therapy (ART), with HIV RNA less than 200 copies/ml and CD4+ cell count 600 cells/μl or less. Inflammation, fibrosis and myocardial biomarkers were measured in blood using ELISA, electrochemiluminescence and immunoturbidimetric methods, and T-cell and monocyte phenotypes were assessed with flow cytometry among a subset of participants. Changes over follow-up in (log-2 transformed) biomarkers and cell phenotypes (untransformed) were compared between losartan and placebo arms using linear mixed models.

RESULTS

Among 108 PHIV (n = 52 to losartan; n = 56 to placebo), 97% had a month 12 visit. Median age was 57 years and baseline CD4+ cell count was 408 cells/μl. Losartan treatment was not associated with an improvement in interleukin-6 levels, or other blood measures of inflammation, immune activation, fibrosis activity or myocardial function. CD4+ and CD8+ T cells also did not differ by treatment group. Losartan reduced SBP and DBP by 6 and 5 mmHg, respectively.

CONCLUSION

Among older PHIV with viral suppression, losartan did not improve blood measures of inflammation nor T-cell immune recovery. Losartan treatment is unlikely to reduce inflammation associated comorbidities to a clinically meaningful degree, beyond the benefits from lowering blood pressure.

CLINICALTRIALSGOV

NCT02049307.

Nebivolol is more effective than atenolol for blood pressure variability attenuation and target organ damage prevention in L-NAME hypertensive rats

β-Adrenergic blockers are no longer recommended as first-line therapy due to the reduced cardioprotection of traditional β-blockers compared with other antihypertensive drugs. It is unknown whether third-generation β-blockers share the limitations of traditional β-blockers. The aim of the present study was to compare the effects of nebivolol or atenolol on central and peripheral systolic blood pressure (SBP) and its variability and target organ damage (TOD) in N-nitro-L-arginine methyl ester (L-NAME) hypertensive rats. Male Wistar rats were treated with L-NAME for 8 weeks together with oral administration of nebivolol 30 mg/kg (n = 8), atenolol 90 mg/kg (n = 8), or vehicle (n = 8). The control group was composed of vehicle-treated Wistar rats. SBP and its variability, as well as echocardiographic parameters, were assessed during the last 2 weeks of treatment. Tissue levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and transforming growth factor β (TGF-β), and histopathological parameters were evaluated in the left ventricle and aorta. Nebivolol had a greater ability than atenolol to decrease central SBP and mid-term and short-term blood pressure variability (BPV) in L-NAME rats. Echocardiographic analysis showed that nebivolol was more effective than atenolol on E/A wave ratio normalization. Compared with atenolol treatment, nebivolol had a greater protective effect on different TOD markers, inducing a decrease in collagen deposition and a reduction in the proinflammatory cytokines IL-6 and TNF-α in the left ventricle and aorta. Our findings suggest that the adverse hemodynamic profile and the reduced cardiovascular protection reported with traditional β-blockers must not be carried forward to third-generation β-blockers.

Effect of Oral Losartan on Orthobiologics: Implications for Platelet-Rich Plasma and Bone Marrow Concentrate-A Rabbit Study

Recent efforts have focused on customizing orthobiologics, such as platelet-rich plasma (PRP) and bone marrow concentrate (BMC), to improve tissue repair. We hypothesized that oral losartan (a TGF-β1 blocker with anti-fibrotic properties) could decrease TGF-β1 levels in leukocyte-poor PRP (LP-PRP) and fibrocytes in BMC. Ten rabbits were randomized into two groups (N = 5/group): osteochondral defect + microfracture (control, group 1) and osteochondral defect + microfracture + losartan (losartan, group 2). For group 2, a dose of 10mg/kg/day of losartan was administrated orally for 12 weeks post-operatively. After 12 weeks, whole blood (WB) and bone marrow aspirate (BMA) samples were collected to process LP-PRP and BMC. TGF-β1 concentrations were measured in WB and LP-PRP with multiplex immunoassay. BMC cell populations were analyzed by flow cytometry with CD31, CD44, CD45, CD34, CD146 and CD90 antibodies. There was no significant difference in TGF-β1 levels between the losartan and control group in WB or LP-PRP. In BMC, the percentage of CD31+ cells (endothelial cells) in the losartan group was significantly higher than the control group (p = 0.008), while the percentage of CD45+ cells (hematopoietic cells-fibrocytes) in the losartan group was significantly lower than the control group (p = 0.03).

Role of the lysyl oxidase enzyme family in cardiac function and disease

Heart diseases are a major cause of morbidity and mortality world-wide. Lysyl oxidase (LOX) and related LOX-like (LOXL) isoforms play a vital role in remodelling the extracellular matrix (ECM). The LOX family controls ECM formation by cross-linking collagen and elastin chains. LOX/LOXL proteins are copper-dependent amine oxidases that catalyse the oxidation of lysine, causing cross-linking between the lysine moieties of lysine-rich proteins. Dynamic changes in LOX and LOXL protein-expression occur in a variety of cardiac pathologies; these changes are believed to be central to the associated tissue-fibrosis. An awareness of the potential pathophysiological importance of LOX has led to the evaluation of interventions that target LOX/LOXL proteins for heart-disease therapy. The purposes of this review article are: (i) to summarize the basic biochemistry and enzyme function of LOX and LOXL proteins; (ii) to consider their tissue and species distribution; and (iii) to review the results of experimental studies of the roles of LOX and LOXL proteins in heart disease, addressing involvement in the mechanisms, pathophysiology and therapeutic responses based on observations in patient samples and relevant animal models. Therapeutic targeting of LOX family enzymes has shown promising results in animal models, but small-molecule approaches have been limited by non-specificity and off-target effects. Biological approaches show potential promise but are in their infancy. While there is strong evidence for LOX-family protein participation in heart failure, myocardial infarction, cardiac hypertrophy, dilated cardiomyopathy, atrial fibrillation and hypertension, as well as potential interest as therapeutic targets, the precise involvement of LOX-family proteins in heart disease requires further investigation.

Eyeing the Extracellular Matrix in Vascular Development and Microvascular Diseases and Bridging the Divide between Vascular Mechanics and Function

The extracellular matrix (ECM) is critical in all aspects of vascular development and health: supporting cell anchorage, providing structure, organization and mechanical stability, and serving as a sink for growth factors and sustained survival signals. Abnormal changes in ECM protein expression, organization, and/or properties, and the ensuing changes in vascular compliance affect vasodilator responses, microvascular pressure transmission, and collateral perfusion. The changes in microvascular compliance are independent factors initiating, driving, and/or exacerbating a plethora of microvascular diseases of the eye including diabetic retinopathy (DR) and vitreoretinopathy, retinopathy of prematurity (ROP), wet age-related macular degeneration (AMD), and neovascular glaucoma. Congruently, one of the major challenges with most vascular regenerative therapies utilizing localized growth factor, endothelial progenitor, or genetically engineered cell delivery, is the regeneration of blood vessels with physiological compliance properties. Interestingly, vascular cells sense physical forces, including the stiffness of their ECM, through mechanosensitive integrins, their associated proteins and the actomyosin cytoskeleton, which generates biochemical signals that culminate in a rapid expression of matricellular proteins such as cellular communication network 1 (CCN1) and CCN2 (aka connective tissue growth factor or CTGF). Loss or gain of function of these proteins alters genetic programs of cell growth, ECM biosynthesis, and intercellular signaling, that culminate in changes in cell behavior, polarization, and barrier function. In particular, the function of the matricellular protein CCN2/CTGF is critical during retinal vessel development and regeneration wherein new blood vessels form and invest a preformed avascular neural retina following putative gradients of matrix stiffness. These observations underscore the need for further in-depth characterization of the ECM-derived cues that dictate structural and functional properties of the microvasculature, along with the development of new therapeutic strategies addressing the ECM-dependent regulation of pathophysiological stiffening of blood vessels in ischemic retinopathies.

The Role of Lysyl Oxidase Enzymes in Cardiac Function and Remodeling

Lysyl oxidase (LOX) proteins comprise a family of five copper-dependent enzymes (LOX and four LOX-like isoenzymes (LOXL1-4)) critical for extracellular matrix (ECM) homeostasis and remodeling. The primary role of LOX enzymes is to oxidize lysyl and hydroxylysyl residues from collagen and elastin chains into highly reactive aldehydes, which spontaneously react with surrounding amino groups and other aldehydes to form inter- and intra-catenary covalent cross-linkages. Therefore, they are essential for the synthesis of a mature ECM and assure matrix integrity. ECM modulates cellular phenotype and function, and strikingly influences the mechanical properties of tissues. This explains the critical role of these enzymes in tissue homeostasis, and in tissue repair and remodeling. Cardiac ECM is mainly composed of fibrillar collagens which form a complex network that provides structural and biochemical support to cardiac cells and regulates cell signaling pathways. It is now becoming apparent that cardiac performance is affected by the structure and composition of the ECM and that any disturbance of the ECM contributes to cardiac disease progression. This review article compiles the major findings on the contribution of the LOX family to the development and progression of myocardial disorders.

Myocardial interstitial fibrosis in the era of precision medicine. Biomarker-based phenotyping for a personalized treatment

Myocardial interstitial fibrosis is a constant pathological finding in structural heart diseases of various etiologies that evolve with heart failure. Although fibrosis facilitates heart failure progression, until now no therapeutic strategy has been developed that ensures its reversal. A possible explanation for this may lie in the vision of myocardial interstitial fibrosis as a homogeneous lesion instead of a heterogeneous lesion in which different phenotypes can be distinguished using appropriate criteria. In addition, the notion that the heterogeneity of myocardial interstitial fibrosis may be cardiac disease-specific must be also considered when approaching this entity. Therefore, we propose that myocardial interstitial fibrosis represents a true challenge for transitioning from usual care to biomarker-based personalized treatment and precision medicine in heart failure. As a proof-of-concept, in this review we discuss the phenotyping of myocardial interstitial fibrosis in patients with heart failure attributable to hypertensive heart disease based on its histomolecular alterations and provide evidence of the prognostic relevance of the resulting stratification. Furthermore, we discuss the available information on some circulating biomarkers and certain pharmacological agents useful for noninvasive identification and personalized treatment, respectively, of those phenotypes.

Emerging Roles of Lysyl Oxidases in the Cardiovascular System: New Concepts and Therapeutic Challenges

Lysyl oxidases (LOX and LOX-likes (LOXLs) isoenzymes) belong to a family of copper-dependent enzymes classically involved in the covalent cross-linking of collagen and elastin, a pivotal process that ensures extracellular matrix (ECM) stability and provides the tensile and elastic characteristics of connective tissues. Besides this structural role, in the last years, novel biological properties have been attributed to these enzymes, which can critically influence cardiovascular function. LOX and LOXLs control cell proliferation, migration, adhesion, differentiation, oxidative stress, and transcriptional regulation and, thereby, their dysregulation has been linked to a myriad of cardiovascular pathologies. Lysyl oxidase could modulate virtually all stages of the atherosclerotic process, from endothelial dysfunction and plaque progression to calcification and rupture of advanced and complicated plaques, and contributes to vascular stiffness in hypertension. The alteration of LOX/LOXLs expression underlies the development of other vascular pathologies characterized by a destructive remodeling of the ECM, such as aneurysm and artery dissections, and contributes to the adverse myocardial remodeling and dysfunction in hypertension, myocardial infarction, and obesity. This review examines the most recent advances in the study of LOX and LOXLs biology and their pathophysiological role in cardiovascular diseases with special emphasis on their potential as therapeutic targets.

Reprint of "The complex dynamics of myocardial interstitial fibrosis in heart failure. Focus on collagen cross-linking"

Myocardial interstitial fibrosis (MIF) is a common finding in heart failure (HF) patients, both with preserved and reduced ejection fraction, as well as in HF animal models. MIF is associated with impaired cardiac function and worse clinical outcome. The impact of MIF is influenced not only by the quantity but also by changes in the quality of collagen fibers and in the extracellular matrix components, such as a shift in collagen types proportion, increased fibronectin polymerization and increased degree of collagen cross-linking (CCL). In particular, CCL, a process that renders collagen fibers stiffer and more resistant to degradation, is increased both in patients and animal models of HF. Importantly, in HF patients increased cardiac CCL is directly associated with increased left ventricular stiffness and a higher risk of hospitalization for HF. The aim of this review is to address the complexity of MIF in HF, focusing on CCL.

The effects of losartan on cytomegalovirus infection in human trabecular meshwork cells

Background

Human cytomegalovirus (CMV) has been emerged as one of the causes of acute recurrent or chronic hypertensive anterior uveitis in immunocompetent. In hypertensive anterior uveitis, human trabecular meshwork (TM) cells are considered a focus of inflammation. We investigated the effects of losartan, a selective angiotensin II receptor antagonist, on CMV infection in human TM cells.

Methods

Human TM cells were infected with CMV AD169. Virus infected and mock-infected cells were treated with losartan or dexamethasone or ganciclovir with or without transforming growth factor (TGF)-β1. Viral DNA accumulation and host cell response were analyzed using real-time PCR. Levels of secreted TGF-β1 were measured by determining its concentration in conditioned medium using a commercially available sandwich enzyme-linked immunosorbent assay (ELISA) kits.

Results

CMV infection significantly increased the concentrations of the secreted TGF-β1 at 3, 5, and 7 day post infection in TM cells. Treatment with dexamethasone or losartan significantly decreased the levels of TGF-β1, whereas treatment with ganciclovir did not affect TGF-β1 levels. TM cells treated with TGF-β1 along with the presence of losartan for 48 hours showed marked decrease in the expression of α-smooth muscle actin (SMA), lysyl oxidase (LOX), connective tissue growth factor (CTGF), fibronectin and collagen-1A, compared with cells treated with TGF-β1 alone. CMV-infected TM cells stimulated by TGF-β1 significantly increased the expression of α-SMA and CTGF, which were attenuated by additional treatment with losartan.

Conclusion

Losartan inhibited the expression of TGF-β1 and fibrogenic molecules in human TM cells. Thus, losartan has the potential to decrease TM fibrosis in patients with CMV-induced hypertensive anterior uveitis.

The complex dynamics of myocardial interstitial fibrosis in heart failure. Focus on collagen cross-linking

Myocardial interstitial fibrosis (MIF) is a common finding in heart failure (HF) patients, both with preserved and reduced ejection fraction, as well as in HF animal models. MIF is associated with impaired cardiac function and worse clinical outcome. The impact of MIF is influenced not only by the quantity but also by changes in the quality of collagen fibers and in the extracellular matrix components, such as a shift in collagen types proportion, increased fibronectin polymerization and increased degree of collagen cross-linking (CCL). In particular, CCL, a process that renders collagen fibers stiffer and more resistant to degradation, is increased both in patients and animal models of HF. Importantly, in HF patients increased cardiac CCL is directly associated with increased left ventricular stiffness and a higher risk of hospitalization for HF. The aim of this review is to address the complexity of MIF in HF, focusing on CCL.

Balance and circumstance: The renin angiotensin system in wound healing and fibrosis

The tissue renin angiotensin system (tRAS) is a locally-acting master-modulator of tissue homeostasis and regeneration. Through these abilities, it is emerging as an attractive target for therapies aiming to restore tissue homeostasis in conditions associated with disturbed wound healing. The tRAS can be divided into two axes - one being pro-inflammatory and pro-fibrotic and one being anti-inflammatory and anti-fibrotic. However, the division of the axes is fuzzy and imperfect as the axes are codependent and the outcome of tRAS activation is determined by the context. Although the tRAS is a local system it shares its key enzymes, ligands and receptors with the systemic RAS and is consequently also targeted by repurposing of drugs developed against the systemic RAS to manage hypertension. With a focus on the skin we will here discuss the tRAS, its involvement in physiological and pathological wound healing, and the therapeutic aptitude of its targeting to treat chronic wounds and fibrosis.

Biomarker-based phenotyping of myocardial fibrosis identifies patients with heart failure with preserved ejection fraction resistant to the beneficial effects of spironolactone: results from the Aldo-DHF trial

BACKGROUND

Myocardial fibrosis is characterized by excessive cross-linking and deposition of collagen type I and is involved in left ventricular stiffening and left ventricular diastolic dysfunction (LVDD). We investigated whether the effect of spironolactone on LVDD in patients with heart failure with preserved ejection fraction (HFpEF) depends on its effects on collagen cross-linking and/or deposition.

METHODS AND RESULTS

We investigated 381 HFpEF patients from the multicentre, randomized, placebo-controlled Aldo-DHF trial with measures of the E:e' ratio. The ratio of serum carboxy-terminal telopeptide of collagen type I to serum matrix metalloproteinase-1 (CITP:MMP-1, an inverse index of myocardial collagen cross-linking) and serum carboxy-terminal propeptide of procollagen type I (PICP, a direct index of myocardial collagen deposition) were determined at baseline and after 1-year treatment with spironolactone 25 mg once daily or placebo. Patients were classified by CITP:MMP-1 and PICP tertiles at baseline. While CITP:MMP-1 tertiles at baseline interacted (P < 0.05) with spironolactone effect on E:e', PICP tertiles did not. In fact, while spironolactone treatment did not modify E:e' in patients with lower CITP:MMP-1 levels, this ratio was significantly reduced in the remaining spironolactone-treated patients. In addition, PICP was unchanged in patients with lower CITP:MMP-1 levels but was reduced in the remaining spironolactone-treated patients.

CONCLUSIONS

A biochemical phenotype of high collagen cross-linking identifies HFpEF patients resistant to the beneficial effects of spironolactone on LVDD. It is suggested that excessive collagen cross-linking, which stabilizes collagen type I fibres, diminishes the ability of spironolactone to reduce collagen deposition in these patients.