Reduced circulating levels of angiotensin-(1--7) in systemic sclerosis: a new pathway in the dysregulation of endothelial-dependent vascular tone control

Steroid hormones in systemic sclerosis: associations with disease characteristics and modifications during scleroderma renal crisis

OBJECTIVE

The renin-angiotensin-aldosterone system (RAAS) and glucocorticoids (GCs) are involved in vascular remodeling and fibrosis but have not been extensively studied in systemic sclerosis (SSc). Our aim was to investigate the RAAS and GC hormones in SSc patients.

METHODS

Serum levels of renin (dosage and activity), aldosterone and its precursors (DOC, B, 18-OH-DOC, 18-OH-B), and GCs (cortisol, cortisone, 11-deoxycortisol, 18-OH-F) were assessed in 122 SSc patients and 52 healthy controls. After applying stringent inclusion criteria aimed at ensuring accurate hormone assessments (exclusion of interfering drugs, strict sampling conditions), we analysed RAAS hormones in 61 patients, and GCs in 96 patients. Hormone levels were compared between patients and controls; and associations with disease characteristics were assessed in patients.

RESULTS

Regarding RAAS hormones, SSc patients displayed significantly lower aldosterone levels (although within normal range), similar renin levels, and higher B levels than controls. Abnormal RAAS hormone levels were associated with a more severe SSc phenotype (lung and skin fibrosis, heart and pulmonary vascular involvements, inflammation). Regarding GC hormones, SSc patients had higher levels of cortisol, 11-desoxycortisol (precursor) and 18-OH-F (metabolite) but lower levels of cortisone (inactive counterpart) than controls. RAAS hormone levels were assessed in five SSc patients before and during scleroderma renal crisis (SRC): concentrations varied considerably between patients, but consistently included normal/increased aldosterone levels and elevated renin levels.

CONCLUSION

RAAS and GC hormones are abnormally produced in SSc patients, especially in patients with severe SSc and during SRC. This could suggest a participation of these hormonal systems in SSc pathogenesis.

Poor Performance of Angiotensin II Enzyme-Linked Immuno-Sorbent Assays in Mostly Hypertensive Cohort Routinely Screened for Primary Aldosteronism

Primary aldosteronism (PA) is the most common, but broadly underdiagnosed, form of hormonal hypertension. To improve screening procedures, current biochemical approaches aim to determine newly appreciated angiotensin II (Ang II) and calculate the aldosterone-to-angiotensin II ratio (AA2R). Thus, the aim of this study was to assess the diagnostic performance of these screening tests in comparison to the aldosterone-to-direct renin ratio (ADRR), which is routinely used. Cheap and available ELISA was used for Ang II measurement. To our knowledge, this is the first study of this laboratory method’s usage in PA. The study cohort included 20 PA patients and 80 controls. Ang II concentrations were comparable between PA and non-PA patients (773.5 vs. 873.2 pg/mL, p = 0.23, respectively). The AA2R was statistically significantly higher in PA group when compared with non-PA (0.024 vs. 0.012 ng/dL/pg/mL, p < 0.001). However, the diagnostic performance of the AA2R was significantly worse than that of the ADRR (AUROC 0.754 vs. 0.939, p < 0.01). The sensitivity and specificity of the AA2R were 70% and 76.2%, respectively. Thus, the AA2R was not effective as a screening tool for PA. Our data provide important arguments in the discussion on the unsatisfactory accuracy of renin−angiotensin system evaluation by recently repeatedly used ELISA tests.

Similarities between COVID-19 and systemic sclerosis early vasculopathy: A "viral" challenge for future research in scleroderma

OBJECTIVE

To review similarities between COVID-19 and systemic sclerosis (SSc) early vasculopathy to provide novel insights into both diseases.

METHODS

A narrative review of the literature supplemented with expert opinion.

RESULTS

There is clear evidence that the endothelium is at the centre stage in SSc and COVID-19, with endothelial cell activation/injury and dysfunction creating the crucial evolving step in the pathogenesis of both diseases. The angiotensin system has also been implicated in the early stages of both COVID-19 and SSc. Autoptic studies provide novel insights into the effects of SARS-CoV-2 on the endothelium. Normal endothelium and endothelial dysfunction in COVID-19 and SSc are discussed. It is debated whether SARS-CoV-2 infection triggers autoimmunity with production of autoantibodies which is of mechanistic interest because other viral illnesses are potentially involved in endothelial dysfunction and in SSc pathogenesis.

CONCLUSION

COVID-19 is due to a direct assault of SARS-CoV-2 on the vascular system as an acute infection, whereas SSc remains a chronic/sub-acute autoimmune disease of largely unknown etiology Further study and exploration of the SARS-CoV-2 pathogenic mechanisms might provide further useful milestones in the understanding of the early SSc pathogenesis.

Effects of Statins on Renin-Angiotensin System

Statins, a class of drugs for lowering serum LDL-cholesterol, have attracted attention because of their wide range of pleiotropic effects. An important but often neglected effect of statins is their role in the renin–angiotensin system (RAS) pathway. This pathway plays an integral role in the progression of several diseases including hypertension, heart failure, and renal disease. In this paper, the role of statins in the blockade of different components of this pathway and the underlying mechanisms are reviewed and new therapeutic possibilities of statins are suggested.

The prevalence and role of functional autoantibodies to angiotensin-converting-enzyme-2 in patients with systemic sclerosis

INTRODUCTION

Systemic sclerosis (SSc) is an autoimmune disease caused by the imbalance between the activity of angiotensin II and angiotensin-(1-7). Their balance should be controlled by angiotensin-converting enzyme 2 (ACE2), which degrades angiotensin II into angiotensin-(1-7). Previously, autoantibodies to ACE2 (anti-ACE2) were identified in patients with vasculopathy due to different connective tissue diseases, including SSc, but their frequency in SSc was not further analyzed. The aim of the research was to investigate the prevalence and potential role of those anti-ACE2 antibodies in SSc patients.

MATERIALS AND METHODS

There were enrolled 27 patients with SSc and 23 healthy donors. ELISA assay determined the presence of anti-ACE2 autoantibodies in serum samples. The results were compared to plasma measurements of angiotensin-(1-7) level via commercial ELISA.

RESULTS

The presence of anti-ACE2 autoantibodies was confirmed in five patients with SSc and two healthy controls. Two of those SSc subjects were anti-Scl70+, another two were double anti-Scl70+ and anti-Ro/SSA+, and anti-PM/Scl antibodies were detected in one patient. Median plasma level of Ang-(1-7) in anti-ACE2 negative patients was 47.4 pg/ml and stayed below the detection level in anti-ACE2 positive subjects. The plasma level of Ang-(1-7) was undetectable in four SSc patients, and three of them were anti-ACE2 positive.

CONCLUSIONS

Anti-ACE2 antibodies appear to be other functional autoantibodies with the potential to dysregulate the balance between Ang II and Ang-(1-7). They are non-specific for SSc and probably result from polyautoimmunity which affect some of SSc patients. Their occurrence in SSc settings may be associated with a severe depletion of plasma Ang-(1-7).

Role of Renin-Angiotensin System Components in Atherosclerosis: Focus on Ang-II, ACE2, and Ang-1-7

Atherosclerosis is the leading cause of vascular disease worldwide and contributes significantly to deaths from cardiovascular complications. There is a remarkably close relationship between atherosclerotic plaque formation and the activation of renin-angiotensin system (RAS). However, depending on which RAS pathway is activated, pro- or anti-atherogenic outcomes may be observed. This brief review focuses on the role of three of the most important pieces of RAS axis, angiotensin II (Ang-II), angiotensin converting enzyme type 2 (ACE2), and angiotensin 1-7 (Ang-1-7) and their involvement in atherosclerosis. We focused on the effects of these molecules on vascular function and inflammation, which are important determinants of atherogenesis. Furthermore, we highlighted potential pharmacological approaches to treat this disorder.

Significance of the angiotensin I/angiotensin II/angiotensin-(1-7) axis in the pathogenesis of systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is a multisystemic disease with an extensive microvasculopathy. Previously, disturbances in plasma levels of angiotensin II (Ang II) and its antagonistic angiotensin-(1-7) (Ang-(1-7)) were found in patients with SSc. Their significance in a pathogenesis of SSc stays unclear due to discrepancies of earlier studies.

OBJECTIVES

To evaluate a significance of disturbances in production pathway of angiotensins in a development of SSc.

METHODS

There were enrolled 27 patients with established SSc, 23 subjects with very early SSc and 23 healthy controls. The diagnosis of SSc was established in patients who met EULAR/ACR 2013 classification criteria. Very early SSc described patients with Raynaud's phenomenon having SSc-specific antinuclear antibodies and SSc-like abnormalities in nailfold videocapillaroscopy. Patients were submitted to evaluation of internal organ involvement and blood sampling to assay plasma levels of angiotensin I, angiotensin II and angiotensin-(1-7) with ELISA technique.

RESULTS

Plasma level of angiotensin-(1-7) was significantly reduced in both SSc group (median = 47.2 pg/mL; P < 0.001) and ones with very early SSc (median = 102.7 pg/mL; P = 0.002) when compared to healthy controls (median = 176.1 pg/mL). A tendency to higher than in control group (median = 214 pg/mL) plasma level of angiotensin I was seen in SSc group (median = 392 pg/mL; P = 0.059). Differences in plasma level of angiotensin II were insignificant between all study groups. Those disturbances produced unfavourable angiotensin-(1-7)/angiotensin II (%) ratio in both groups of patients, which achieved statistical significance in subjects with established SSc (P < 0.001). Production pathway of angiotensins showed a dependence on a subtype of SSc, immune profile and a presence of interstitial lung disease.

CONCLUSIONS

Production of angiotensin-(1-7) was significantly reduced in both SSc patients and those ones with very early SSc, although a significant imbalance between angiotensin II and angiotensin-(1-7) occurred only in subjects with established disease.

Association between preterm birth and the renin-angiotensin system in adolescence: influence of sex and obesity

OBJECTIVES

Preterm birth appears to contribute to early development of cardiovascular disease, but the mechanisms are unknown. Prematurity may result in programming events that alter the renin-angiotensin system. We hypothesized that prematurity is associated with lower angiotensin-(1-7) in adolescence and that sex and obesity modify this relationship.

METHODS

We quantified angiotensin II and angiotensin-(1-7) in the plasma and urine of 175 adolescents born preterm and 51 term-born controls. We used generalized linear models to estimate the association between prematurity and the peptides, controlling for confounding factors and stratifying by sex and overweight/obesity.

RESULTS

Prematurity was associated with lower plasma angiotensin II (β: -5.2 pmol/l, 95% CI: -10.3 to -0.04) and angiotensin-(1-7) (-5.2 pmol/l, 95% CI: -8.4 to -2.0) but overall higher angiotensin II:angiotensin-(1-7) (3.0, 95% CI: 0.9-5.0). The preterm-term difference in plasma angiotensin-(1-7) was greater in women (-6.9 pmol/l, 95% CI: -10.7 to -3.1) and individuals with overweight/obesity (-8.0 pmol/l, 95% CI: -12.2 to -3.8). The preterm-term difference in angiotensin II:angiotensin-(1-7) was greater among those with overweight/obesity (4.4, 95% CI: 0.6-8.1). On multivariate analysis, prematurity was associated with lower urinary angiotensin II:angiotensin-(1-7) (-0.13, 95% CI: -0.26 to -0.003), especially among the overweight/obesity group (-0.38, 95% CI: -0.72 to -0.04).

CONCLUSION

Circulating angiotensin-(1-7) was diminished whereas urinary angiotensin-(1-7) was increased relative to angiotensin II in adolescents born preterm, suggesting prematurity may increase the risk of cardiovascular disease by altering the renin-angiotensin system. Perinatal renin-angiotensin system programming was more pronounced in women and individuals with overweight/obesity, thus potentially augmenting their risk of developing early cardiovascular disease.

[Updates in systemic sclerosis pathogenesis: Toward new therapeutic opportunities]

Systemic sclerosis is a rare connective tissue disease characterized by skin and several internal organ fibrosis, systemic vasculopathy and immune abnormalities. Even if fibroblasts and endothelial cells dysfunction, as well as lymphocytes and other immune cells implication are now well described, the exact origin and chronology of the disease pathogenesis remain unclear. Oxidative stress, influenced by genetic and environmental factors, seems to play a key role. Indeed, it seems to be implicated in the early phases of fibrosis development, vasculopathy and in immune tolerance abnormalities shared by all patients, although disease expression is heterogeneous. To date, no curative treatment is available. Even if immunosuppressive treatment or drugs acting on vascular system are proposed for some patients, overall, treatment efficiency remains modest. Only autologous hematopoietic stem cells transplantation, reserved for patients with severe or rapidly progressive fibrosis, has recently demonstrated efficiency, with lasting regression of fibrosis. Nevertheless, this treatment can expose to important, life-threatening toxicity. In the last decade, new mechanisms implicated in the pathogenesis of systemic sclerosis have been unraveled, bringing new therapeutic opportunities. In this review, we offer to focus on recent insights in the knowledge of systemic sclerosis pathogenesis and its implication in current and future medical care.

Mas Receptor Activation Slows Tumor Growth and Attenuates Muscle Wasting in Cancer

Cancer cachexia is a multifactorial syndrome characterized by a progressive loss of skeletal muscle mass associated with significant functional impairment. Cachexia robs patients of their strength and capacity to perform daily tasks and live independently. Effective treatments are needed urgently. Here, we investigated the therapeutic potential of activating the "alternative" axis of the renin-angiotensin system, involving ACE2, angiotensin-(1-7), and the mitochondrial assembly receptor (MasR), for treating cancer cachexia. Plasmid overexpression of the MasR or pharmacologic angiotensin-(1-7)/MasR activation did not affect healthy muscle fiber size in vitro or in vivo but attenuated atrophy induced by coculture with cancer cells in vitro. In mice with cancer cachexia, the MasR agonist AVE 0991 slowed tumor development, reduced weight loss, improved locomotor activity, and attenuated muscle wasting, with the majority of these effects dependent on the orexigenic and not antitumor properties of AVE 0991. Proteomic profiling and IHC revealed that mechanisms underlying AVE 0991 effects on skeletal muscle involved miR-23a-regulated preservation of the fast, glycolytic fibers. MasR activation is a novel regulator of muscle phenotype, and AVE 0991 has orexigenic, anticachectic, and antitumorigenic effects, identifying it as a promising adjunct therapy for cancer and other serious muscle wasting conditions. SIGNIFICANCE: These findings demonstrate that MasR activation has multiple benefits of being orexigenic, anticachectic, and antitumorigenic, revealing it as a potential adjunct therapy for cancer.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/4/706/F1.large.jpg.See related commentary by Rupert et al., p. 699.

The role of endothelial cells in the vasculopathy of systemic sclerosis: A systematic review

INTRODUCTION

Systemic sclerosis (SSc) is an autoimmune connective tissue disorder characterized by fibroproliferative vasculopathy, immunological abnormalities and progressive fibrosis of multiple organs including the skin. In this study, all English speaking articles concerning the role of endothelial cells (ECs) in SSc vasculopathy and representing biomarkers are systematically reviewed and categorized according to endothelial cell (EC) (dys)function in SSc.

METHODS

A sensitive search on behalf of the EULAR study group on microcirculation in Rheumatic Diseases was developed in Pubmed, The Cochrane Library and Web of Science to identify articles on SSc vasculopathy and the role of ECs using the following Mesh terms: (systemic sclerosis OR scleroderma) AND pathogenesis AND (endothelial cells OR marker). All selected papers were read and discussed by two independent reviewers. The selection process was based on title, abstract and full text level. Additionally, both reviewers further searched the reference lists of the articles selected for reading on full text level for supplementary papers. These additional articles went through the same selection process.

RESULTS

In total 193 resulting articles were selected and the identified biomarkers were categorized according to description of EC (dys)function in SSc. The most representing and reliable biomarkers described by the selected articles were adhesion molecules for EC activation, anti-endothelial cell antibodies for EC apoptosis, vascular endothelial growth factor (VEGF), its receptor VEGFR-2 and endostatin for disturbed angiogenesis, endothelial progenitors cells for defective vasculogenesis, endothelin-1 for disturbed vascular tone control, Von Willebrand factor for coagulopathy and interleukin (IL)-33 for EC-immune system communication. Emerging, relatively new discovered biomarkers described in the selected articles, are VEGF₁₆₅b, IL-17A and the adipocytokines. Finally, myofibroblasts involved in tissue fibrosis in SSc can derive from ECs or epithelial cells through a process known as endothelial-to-mesenchymal transition.

CONCLUSION

This systematic review emphasizes the growing evidence that SSc is primarily a vascular disease where EC dysfunction is present and prominent in different aspects of cell survival (activation and apoptosis), angiogenesis and vasculogenesis and where disturbed interactions between ECs and various other cells contribute to SSc vasculopathy.

Angiotensin (1-7) and Alamandine: Similarities and differences

A primary peptide of the renin angiotensin system (RAS), Angiotensin (Ang) II, is a vasoconstrictor and promotor of atherosclerosis. To counter this, the RAS also consists of peptides and receptors which increase nitric oxide release from the endothelium and decrease nicotinamide adenine dinucleotide phosphate oxidase-related superoxide production. Two peptides, Ang (1-7) and alamandine are vasodilators, by activating the nitric oxide pathway via different receptors in the endothelium. Thus, herein we focus on the similarities and differences between alamandine and Ang (1-7) and the counterbalancing hypothesis on Ang II during endothelial dysfunction and atherosclerosis.

MMP-12 deficiency attenuates angiotensin II-induced vascular injury, M2 macrophage accumulation, and skin and heart fibrosis

MMP-12, a macrophage-secreted elastase, is elevated in fibrotic diseases, including systemic sclerosis (SSc) and correlates with vasculopathy and fibrosis. The goal of this study was to investigate the role of MMP-12 in cardiac and cutaneous fibrosis induced by angiotensin II infusion. Ang II-induced heart and skin fibrosis was accompanied by a marked increase of vascular injury markers, including vWF, Thrombospondin-1 (TSP-1) and MMP-12, as well as increased number of PDGFRβ⁺ cells. Furthermore Ang II infusion led to an accumulation of macrophages (Mac3⁺) in the skin and in the perivascular and interstitial fibrotic regions of the heart. However, alternatively activated (Arg 1⁺) macrophages were mainly present in the Ang II infused mice and were localized to the perivascular heart regions and to the skin, but were not detected in the interstitial heart regions. Elevated expression of MMP-12 was primarily found in macrophages and endothelial cells (CD31⁺) cells, but MMP-12 was not expressed in the collagen producing cells. MMP-12 deficient mice (MMP12KO) showed markedly reduced expression of vWF, TSP1, and PDGFRβ around vessels and attenuation of dermal fibrosis, as well as the perivascular fibrosis in the heart. However, MMP-12 deficiency did not affect interstitial heart fibrosis, suggesting a heterogeneous nature of the fibrotic response in the heart. Furthermore, MMP-12 deficiency almost completely prevented accumulation of Arg 1⁺ cells, whereas the number of Mac3⁺ cells was partially reduced. Moreover production of profibrotic mediators such as PDGFBB, TGFβ1 and pSMAD2 in the skin and perivascular regions of the heart was also inhibited. Together, the results of this study show a close correlation between vascular injury markers, Arg 1⁺ macrophage accumulation and fibrosis and suggest an important role of MMP-12 in regulating these processes.

UPLC-DAD/Q-TOF-MS Based Ingredients Identification and Vasorelaxant Effect of Ethanol Extract of Jasmine Flower

Chinese people commonly make jasmine tea for recreation and health care. Actually, its medicinal value needs more exploration. In this study, vasorelaxant effect of ethanol extract of jasmine flower (EEJ) on isolated rat thoracic aorta rings was investigated and [Ca(2+)] was determined in vascular smooth muscle cells by laser scanning confocal microscope (LSCM). The result of aorta rings showed that EEJ could cause concentration-dependent relaxation of endothelium-intact rings precontracted with phenylephrine or KCl which was attenuated after preincubation of the rings with L-NAME and three different K(+) channel inhibitors; however, indomethacin and glibenclamide did not affect the vasodilatation of EEJ. In addition, EEJ could inhibit contraction induced by PE on endothelium-denuded rings in Ca(2+)-free medium as well as by accumulation of Ca(2+) in Ca(2+)-free medium with high K(+). LSCM also showed that EEJ could lower the elevated level of [Ca(2+)] induced by KCl. These indicate that the vasodilation of EEJ is in part related to causing the release of nitric oxide, activation of K(+) channels, inhibition of influx of excalcium, and release of calcium from sarcoplasmic reticulum. A total of 20 main ingredients, were identified in EEJ by UPLC-DAD/Q-TOF-MS. The vasodilation activity should be attributed to the high content of flavonoid glycosides and iridoid glycosides found in EEJ.

A systematic review to investigate whether Angiotensin-(1-7) is a promising therapeutic target in human heart failure

Context. Heart failure (HF) is a common condition causing much morbidity and mortality despite major advances in pharmacological and device therapies. Preclinical data suggest a cardioprotective role of Angiotensin-(1-7) in animal models of HF. Objective. Perform a systematic review on the effects of Angiotensin-(1-7) on humans, focusing on HF. Results. 39 studies were included in the review (4 in human HF and (35) in non-HF patients). There is only one intervention study on 8 patients with human HF, using Angiotensin-(1-7), with forearm blood flow (FBF) as the endpoint. Angiotensin-(1-7) caused no significant effect on FBF in this HF study but caused vasodilation in 3 out of 4 non-HF studies. In one other non-HF study, Angiotensin-(1-7) infusion led to a significant increase in blood pressure in normal men; however, effects were <0.03% that of angiotensin II. Cardioprotective effects seen in non-HF studies include for instance beneficial actions against atherosclerosis and myocardial fibrosis. Conclusions. The main finding of our systematic review is that Angiotensin-(1-7) plays an important cardioprotective role in HF in animals and in patients without heart failure. More research is required to test the hypothesis that Angiotensin-(1-7) benefits patients with heart failure.

Enhanced proteolytic clearance of plasma Aβ by peripherally administered neprilysin does not result in reduced levels of brain Aβ in mice

Accumulation of β-amyloid (Aβ) in the brain is believed to contribute to the pathology of Alzheimer's Disease (AD). Aβ levels are controlled by the production of Aβ from amyloid precursor protein, degradation by proteases, and peripheral clearance. In this study we sought to determine whether enhancing clearance of plasma Aβ with a peripherally administered Aβ-degrading protease would reduce brain Aβ levels through a peripheral sink. Neprilysin (NEP) is a zinc-dependent metalloprotease that is one of the key Aβ-degrading enzymes in the brain. We developed a NEP fusion protein with in vitro degradation of Aβ and a 10 day plasma half-life in mouse. Intravenous administration of NEP to wild-type and APP23 transgenic mice resulted in dose-dependent clearance of plasma Aβ. However, this did not correspond to reduced levels of soluble brain Aβ with treatment up to 5 weeks in WT mice or formic acid-extractable brain Aβ with 3 month treatment in aged APP23. In contrast, intracranial injection of NEP resulted in an acute decrease in soluble brain Aβ. We found no change in amyloid precursor protein gene expression in mice treated with intravenous NEP, suggesting that the lack of effects in the brain following this route of administration was not caused by compensatory upregulation of Aβ production. Taken together, these results suggest a lack of a robust peripheral Aβ efflux sink through which brain amyloid burdens can be therapeutically reduced.

Angiotensin II induces skin fibrosis: a novel mouse model of dermal fibrosis

Introduction

Systemic sclerosis (SSc) is an autoimmune inflammatory disorder of unknown etiology characterized by fibrosis of the skin and internal organs. Ang II (angiotensin II), a vasoconstrictive peptide, is a well-known inducer of kidney, heart, and liver fibrosis. The goal of this study was to investigate the profibrotic potential of Ang II in the mouse skin.

Methods

Ang II was administered by subcutaneous osmotic mini pumps to C57BL/6 male mice. Collagen-content measurements were performed with Gomori Trichrome staining and hydroxyproline assay. The mRNA expression level of collagens, TGF-β1, TGF-β2, TGF-β3, CTGF, αSMA, CD3, Emr1, CD45/B220, MCP1, and FSP1 were quantified with real-time polymerase chain reaction (PCR). Immunostaining was performed for markers of inflammation and fibrosis, including, phospho-Smad2, αSMA, CD3, Mac3, CD45/B220, and CD163B. Fibrocytes were identified by double staining with CD45/FSP1 and CD45/PH4. Endothelial cells undergoing endothelial-to-mesenchymal transition (EndoMT) were identified by double staining with VE-cadherin/FSP1.

Results

Ang II-infused mice develop prominent dermal fibrosis in the area proximal to the pump, as shown by increased collagen and CTGF mRNA levels, increased hydroxyproline content, and more tightly packed collagen fibers. In addition, elevated mRNA levels of TGF-β2 and TGF-β3 along with increased expression of pSmad2 were observed in the skin of Ang II-treated mice. Dermal fibrosis was accompanied by an increased number of infiltrating fibrocytes, and an increased number of αSMA-positive cells, as well as CD163B⁺ macrophages in the upper dermis. This correlated with significantly increased mRNA levels of αSMA, Emr1, and MCP1. Infiltration of CD3-, CD45/B220-, and Mac3-positive cells was observed mainly in the hypodermis. Furthermore, an increased number of double-positive VE-cadherin/FSP1 cells were detected in the hypodermis only.

Conclusions

This work demonstrates that Ang II induces both inflammation and fibrosis in the skin via MCP1 upregulation and accumulation of activated fibroblasts. Additionally, our data suggest that populations of these fibroblasts originate from circulating blood cells. Ang II infusion via osmotic minipumps could serve as a useful mouse model of skin fibrosis to gain new insights into pathogenic mechanisms and to test new antifibrotic therapies.

The pathogenesis, diagnosis and treatment of Raynaud phenomenon

The past 10 years have seen the publication of results from several multicentre clinical trials in primary and systemic sclerosis (SSc)-related Raynaud phenomenon. The publication of these studies has occurred as a result of new insights into the pathogenesis of Raynaud phenomenon, which are directing new treatment approaches, and increased international collaboration between clinicians and scientists. Although the pathogenesis of Raynaud phenomenon is complex, abnormalities of the blood vessel wall, of neural control mechanisms and of intravascular (circulating) factors are known to interact and contribute. Key players relevant in drug development include nitric oxide, endothelin-1, alpha adrenergic receptor activation, abnormal signal transduction in vascular smooth muscle, oxidative stress and platelet activation. The main advances in diagnosis have been a clearer understanding of autoantibodies and of abnormal nailfold capillary patterns as independent predictors of SSc, and widespread use and increased availability of capillaroscopy. The ultimate aim is to translate the advances made in the pathophysiology and early diagnosis into development of treatments to prevent and reverse digital vascular dysfunction and injury. This Review provides an update of the pathogenesis, diagnosis and treatment of Raynaud phenomenon. Current and future treatment approaches are discussed, and some key unanswered questions are highlighted.

ACE2: more of Ang-(1-7) or less Ang II?

PURPOSE OF REVIEW

Previous concepts regarding the pathways involved in the generation of angiotensin II (Ang II) have been challenged by studies showing the existence of a peptide acting as an endogenous antagonist of Ang II. The discovery that angiotensin-(1-7) [Ang-(1-7)] opposes the pressor, proliferative, profibrotic, and prothrombotic actions mediated by Ang II has contributed to the realization that the renin-angiotensin system is composed of two opposing arms: the pressor arm constituted by the enzyme angiotensin-converting enzyme (ACE), Ang II as the product, and the Ang II type 1 (AT1) receptor as the main protein mediating the biological actions of Ang II; the second arm is composed of the monocarboxypeptidase angiotensin-converting enzyme 2 (ACE2), Ang-(1-7) produced through hydrolysis of Ang II, and the Mas receptor as the protein conveying the vasodilator, antiproliferative, antifibrotic, and antithrombotic effects of Ang-(1-7).

RECENT FINDINGS

Experimental and clinical studies demonstrate a role for the Ang-(1-7)/ACE2/Mas axis in the evolution of hypertension, the regulation of renal function, and the progression of renal disease including diabetic nephropathy. Additional evidence suggests that a reduction in the expression and activity of this vasodepressor component may be a critical factor in mediating the progression of cardiovascular disease.

SUMMARY

Further research on the contribution of the Ang-(1-7)/ACE2/Mas axis to cardiovascular pathology will lead to the development of new pharmacological approaches resulting in the design of molecular or genetic means to increase the expression of ACE2, allow for increased tissue levels of Ang-(1-7), or both.

COX-2 Inhibition by Use of Rofecoxib or High Dose Aspirin Enhances ADP-Induced Platelet Aggregation in Fresh Blood

Aim:

Increased cardiovascular risk after use of selective or nonselective cyclooxygenase-2 (COX-2)-inhibitors might partly be caused by enhanced platelet aggregability. However, an effect of COX-2 inhibition on platelets has so far not been observed in humans.

Methods:

We tested in healthy volunteers the effect of COX-2-inhibition nearly in-vivo, i.e. immediately after and even during blood sampling.

Results:

Measurement within 2 minutes after venipuncture, but not 60 minutes later, showed that 50 mg of rofecoxib (n=12) or 500 (n=8) or 1000 (n=8) mg of aspirin increased ADP-induced platelet aggregation in a whole-blood aggregometer to, respectively, 152, 176 and 204 % of basal level (p<0.01). No significant differences in aggregability were observed after ingestion of 80 mg of aspirin (n=16), or placebo (n=8). Plasma 6-keto-PGF1α was decreased to 74 % after rofecoxib and to 76 and 70 % after 500 and 1000 mg of aspirin but did not change after low dose aspirin. Continuous photometrical measurement of aggregation in blood flowing from a cannulated vein revealed that high dose aspirin did not elicit aggregation by itself, but increased ADP-induced aggregation in proportion to the decrease in prostacyclin formation (r=0.68, p = 0.004). Since in these experiments thromboxane production was virtually absent, the enhanced aggregation after partial COX-2 inhibition was not caused by unopposed thromboxane formation.

Conclusions:

We conclude that both selective and nonselective COX-2 inhibition enhances ADP-induced platelet aggregation in humans. This effect can only be detected during or immediately after venipuncture, possibly because of the short half-life of prostacyclin.

The ANG-(1-7)/ACE2/mas axis in the regulation of nephron function

The study of experimental hypertension and the development of drugs with selective inhibitory effects on the enzymes and receptors constituting the components of the circulating and tissue renin-angiotensin systems have led to newer concepts of how this system participates in both physiology and pathology. Over the last decade, a renewed emphasis on understanding the role of angiotensin-(1-7) and angiotensin-converting enzyme 2 in the regulation of blood pressure and renal function has shed new light on the complexity of the mechanisms by which these components of the renin angiotensin system act in the heart and in the kidneys to exert a negative regulatory influence on angiotensin converting enzyme and angiotensin II. The vasodepressor axis composed of angiotensin-(1-7)/angiotensin-converting enzyme 2/mas receptor emerges as a site for therapeutic interventions within the renin-angiotensin system. This review summarizes the evolving knowledge of the counterregulatory arm of the renin-angiotensin system in the control of nephron function and renal disease.

Advances in the renin angiotensin system focus on angiotensin-converting enzyme 2 and angiotensin-(1-7)

The contribution of the renin angiotensin system to physiology and pathology is undergoing a rapid reconsideration of its mechanisms from emerging new concepts implicating angiotensin-converting enzyme 2 and angiotensin-(1-7) as new elements negatively influencing the vasoconstrictor, trophic, and pro-inflammatory actions of angiotensin II. This component of the system acts to oppose the vasoconstrictor and proliferative effects on angiotensin II through signaling mechanisms mediated by the mas receptor. In addition, a reduced expression of the vasodepressor axis composed by angiotensin-converting enzyme 2 and angiotensin-(1-7) may contribute to the expression of essential hypertension, the remodeling of heart and renal function associated with this disease, and even the physiology of pregnancy and the development of eclampsia.