Aortic Dimensions, Biophysical Properties, and Plasma Biomarkers in Children and Adults with Marfan or Loeys-Dietz Syndrome

An exploration of alternative therapeutic targets for aortic disease in Marfan syndrome

Marfan syndrome is a rare connective tissue disorder that causes aortic dissection-related sudden death. Current conventional treatments, beta-blockers, and type 1 angiotensin II receptor blockers are prescribed to slow down aortic aneurysm progression and delay (prophylactic) aortic surgery. However, neither of these treatments ceases aortic growth completely. This review focuses on potential alternative therapeutic leads in the field, ranging from widely used medication with beneficial effects on the aorta to experimental inhibitors with the potential to stop aortic growth in Marfan syndrome. Clinical trials are warranted to uncover their full potential.

Impact of Genotype-Phenotype Interactions on Cardiovascular Function in Paediatric Loeys-Dietz Syndrome

Background

The relationship between genotype and phenotypical vascular and cardiac properties in paediatric Loeys-Dietz syndrome (LDS) patients are not well characterized. This study explores the phenotypical differences in aortic properties and cardiac structural and functional parameters between paediatric LDS patients with TGFBR1 and TGFBR2 mutations.

Methods

We included 32 LDS patients with either TGFBR1 (n = 17) or TGFBR2 (n = 15) mutations. Echocardiographic data included aortic dimensions, distensibility, strain, and stiffness at the level of the annulus, sinuses of Valsalva, sinotubular junction, ascending aorta, and descending aorta. Parameters for left ventricular size and function were also recorded.

Results

Demographics were similar between the groups. Patients with TGFBR2 were more likely to have undergone aortic surgery (47% vs 12%, P = 0.057) and use angiotensin receptor blockers (93% vs 47%, P = 0.015). Aortic z scores were significantly larger in the TGFBR2 group at the level of the aortic valve annulus (P = 0.007), sinuses of Valsalva (P = 0.001), sinotubular junction (P = 0.001), and ascending aorta (P = 0.054). Patients with TGFBR2 also had significantly lower aortic distensibility and strain coupled with higher stiffness index at the level of the annulus, sinotubular junction, and ascending aorta. Parameters for the descending aorta, cardiac morphology, and cardiac function were similar between the groups.

Conclusions

Paediatric LDS patients with TGFBR2 present with more severe cardiovascular phenotypes than patients with TGFBR1 with larger aortic dimensions and increased aortic stiffness. Our findings suggest that genotypes should be taken into consideration in the clinical management of paediatric LDS patients.

TGFβ level in healthy and children with Marfan syndrome-effective reduction under sartan therapy

Introduction

Transforming growth factor β (TGFβ) metabolism plays an important role in the pathogenesis of Marfan syndrome (MFS). Accordingly, drug therapy uses TGFβ receptor blockade to slow down the cardiovascular manifestations, above all aortic root dilatation. Angiotensin II type 1 receptor blockers (ARBs) have been shown to reduce TGFβ levels in adults. Data on childhood are lacking and are now being investigated in the TiGer For Kids study presented here.

Methods

We examined 125 children without chronic disease and 31 pediatric Marfan patients with a proven FBN1 variant with regard to TGFβ levels. In addition, we measured TGFβ levels during the initiation of ARB therapy in pediatric Marfan patients.

Results

In children without chronic disease, TGFβ levels were found to decrease from childhood to adolescence (p < 0.0125). We could not measure a relevantly increased TGFβ level in pediatric Marfan patients. However, we showed a significant suppression of the TGFβ level after treatment with ARBs (p < 0.0125) and a renewed increase shortly before the next dose.

Discussion

The TGFβ level in childhood changes in an age-dependent manner and decreases with age. The TGFβ level drops significantly after taking ARBs. Based on our experience and data, a TGFβ receptor blockade in childhood seems reasonable. So far, TGFβ level cannot be used as an MFS screening biomarker.

A phenotypic screen of Marfan syndrome iPSC-derived vascular smooth muscle cells uncovers GSK3β as a new target

Marfan syndrome (MFS) is a rare connective tissue disorder caused by mutations in FBN1. Patients with MFS notably suffer from aortic aneurysm and dissection. Despite considerable effort, animal models have proven to be poorly predictive for therapeutic intervention in human aortic disease. Patient-derived induced pluripotent stem cells can be differentiated into vascular smooth muscle cells (VSMCs) and recapitulate major features of MFS. We have screened 1,022 small molecules in our in vitro model, exploiting the highly proteolytic nature of MFS VSMCs, and identified 36 effective compounds. Further analysis identified GSK3β as a recurring target in the compound screen. GSK3β inhibition/knockdown did not ameliorate the proliferation defect in MFS-VSMCs but improved MFS-VSMC proteolysis and apoptosis and partially rescued fibrillin-1 deposition. To conclude, we have identified GSK3β as a novel target for MFS, forming the foundation for future work in MFS and other aortic diseases.

Markers of extracellular matrix remodeling and systemic inflammation in patients with heritable thoracic aortic diseases

Background

In approximately 20% of patients with thoracic aortic aneurysms or dissections a heritable thoracic aortic disease (HTAD) is suspected. Several monogenic connective tissue diseases imply high risk of aortic disease, including both non-syndromic and syndromic forms. There are some studies assessing inflammation and extracellular matrix remodeling in patients with non-hereditary aortic disease, but such studies in patients with hereditary diseases are scarce.

Aims

To quantify markers of extracellular matrix (ECM) and inflammation in patients with vascular connective tissue diseases versus healthy controls.

Methods

Patients with Loeys-Dietz syndrome (LDS, n = 12), Marfan syndrome (MFS, n = 11), and familial thoracic aortic aneurysm 6 (FTAA6, n = 9), i.e., actin alpha 2 (ACTA2) pathogenic variants, were recruited. Exome or genome sequencing was performed for genetic diagnosis. Several markers of inflammation and ECM remodeling were measured in plasma by enzyme immunoassays. Flow cytometry of T-cell subpopulations was performed on a subgroup of patients. For comparison, blood samples were drawn from 14 healthy controls.

Results

(i) All groups of HTAD patients had increased levels matrix metalloproteinase-9 (MMP-9) as compared with healthy controls, also in adjusted analyses, reflecting altered ECM remodeling. (ii) LDS patients had increased levels of pentraxin 3 (PTX3), reflecting systemic inflammation. (iii) LDS patients have increased levels of soluble CD25, a marker of T-cell activation.

Conclusion

Our data suggest that upregulated MMP-9, a matrix degrading enzyme, is a common feature of several subgroups of HTAD. In addition, LDS patients have increased levels of PTX3 reflecting systemic and in particular vascular inflammation.

Can 10 000 Healthy Steps a Day Slow Aortic Root Dilation in Pediatric Patients With Marfan Syndrome?

Background Stiffer aortas are associated with a faster rate of aortic root (AoR) dilation and higher risk of aortic dissection in patients with Marfan syndrome. We have previously shown that mild aerobic exercise reduces aortic stiffness and rate of AoR dilation in a Marfan mouse model. In this study, we investigated if these results could be translated to pediatric patients with Marfan syndrome. Methods and Results We enrolled 24 patients with Marfan syndrome aged 8 to 19 years to participate in a 6-month physical activity intervention, excluding those with ventricular dysfunction or prior history of aortic surgery. We instructed patients to take 10 000 steps per day, tracked by an activity tracker. At baseline and 6 months, we measured AoR dimension, arterial stiffness, endothelial function, physical activity indices, inflammatory biomarkers, and coping scores. Controls consisted of 15 age-matched patients with Marfan syndrome. Twenty-four patients with Marfan syndrome (median age, 14.4 years [interquartile range {IQR}, 12.2-16.8], 14 male patients) were enrolled. Baseline assessment demonstrated that the majority of these patients were sedentary and had abnormal arterial health. Twenty-two patients completed the intervention and took an average of 7709±2177 steps per day (median, 7627 [IQR, 6344-9671]). Patients wore their Garmin trackers at a median of 92.8% (IQR, 84%-97%) of their intervention days. AoR Z score in the intervention group had a significantly lower rate of change per year compared with the controls (rate of change, -0.24 versus +0.008; P=0.01). Conclusions In this clinical intervention in pediatric patients with Marfan syndrome, we demonstrated that a simple physical activity intervention was feasible in this population and has the potential to decrease the AoR dilation rate. REGISTRATION URL: https://www.clinicaltrials.gov; Unique identifier: NCT03567460.

[Latest advances in the diagnosis and treatment of Marfan syndrome]

Marfan syndrome (MFS) is a multisystem connective tissue disease with autosomal dominant inheritance. It is mainly caused by FBN1 gene mutation and often has different clinical manifestations. Neonatal MFS is especially rare with severe conditions and a poor prognosis. At present, there is still no radical treatment method for MFS, but early identification, early diagnosis, and early treatment can effectively prolong the life span of patients. This article reviews the latest advances in the diagnosis and treatment of MFS.

Comprehensive Characterization of Arterial and Cardiac Function in Marfan Syndrome-Can Biomarkers Help Improve Outcome?

Background: Marfan Syndrome (MFS) has been associated with increased aortic stiffness and left ventricular dysfunction. The latter may be due to the underlying genotype and/or secondary to aortic stiffening (vascular-ventricular interaction). The aim of this study was to characterize arterial and cardiac function in MFS using a multimodal approach.

Methods: Prospective observational study of MFS patients and healthy controls. Methods included echocardiography, ascending aortic distensibility, common carotid intima media thickness [cIMT], parameters of wave reflection, carotid-femoral pulse wave velocity [cfPWV]), reactive hyperemia index [RHI], and biomarker analysis (Olink, CVII panel).

Results: We included 20 patients with MFS and 67 controls. Ascending aortic distensibility, cIMT and RHI were decreased, while all parameters of arterial wave reflection, stiffness and BNP levels were increased in the MFS group. Both systolic and diastolic function were impaired relative to controls. Within the MFS group, no significant correlation between arterial and cardiac function was identified. However, cfPWV correlated significantly with indexed left ventricular mass and volume in MFS. Bran natriuretic peptide (BNP) was the only biomarker significantly elevated in MFS following correction for age and sex.

Conclusions: MFS patients have generally increased aortic stiffness, endothelial dysfunction and BNP levels while cIMT is decreased, supporting that the mechanism of general stiffening is different from acquired vascular disease. CfPWV is associated with cardiac size, blood pressure and BNP in MFS patients. These may be early markers of disease progression that are suitable for monitoring pharmacological treatment effects in MFS patients.

The Predictive Role of Plasma Biomarkers in the Evolution of Aortopathies Associated with Congenital Heart Malformations

Dilatation of the aorta is a constantly evolving condition that can lead to the ultimate life-threatening event, acute aortic dissection. Recent research has tried to identify quantifiable biomarkers, with both diagnostic and prognostic roles in different aortopathies. Most studies have focused on the bicuspid aortic valve, the most frequent congenital heart disease (CHD), and majorly evolved around matrix metalloproteinases (MMPs). Other candidate biomarkers, such as asymmetric dimethylarginine, soluble receptor for advanced glycation end-products or transforming growth factor beta have also gained a lot of attention recently. Most of the aortic anomalies and dilatation-related studies have reported expression variation of tissular biomarkers. The ultimate goal remains, though, the identification of biomarkers among the serum plasma, with the upregulation of circulating MMP-1, MMP-2, MMP-9, tissue inhibitor of metalloproteinase-1 (TIMP-1), asymmetric dimethylarginine (ADMA), soluble receptor for advanced glycation end-products (sRAGE) and transforming growth factor beta (TGF-β) being reported in association to several aortopathies and related complications in recent research. These molecules are apparently quantifiable from the early ages and have been linked to several CHDs and hereditary aortopathies. Pediatric data on the matter is still limited, and further studies are warranted to elucidate the role of plasmatic biomarkers in the long term follow-up of potentially evolving congenital aortopathies.

Nitric oxide in the Marfan vasculature: Friend or foe?

Marfan syndrome (MFS) is a connective tissue disorder caused by mutations in the FBN1 gene, which encodes fibrillin-1, a protein essential for the formation and stabilization of elastic fibers as well as signaling homeostasis. Progressive aortic root widening is the most serious manifestation of MFS as it can lead to aortic dissection, aneurysm formation and rupture. However, despite their ability to decrease the hemodynamic stress the aorta is subjected to, anti-hypertensive medications often lead to underwhelming reductions in the rate of aortic root dilation, which illustrates how fragmental our understanding of MFS-associated aortic remodeling is. This manuscript summarizes recent evidence that document nitric oxide (NO) synthase (NOS)-related changes to the vasculature during the pathogenesis of MFS and how they result in a unique state of vascular dysfunction that likely plays a causal role in the aortic root widening process. We also review how clinic-approved and experimental therapies as well lifestyle approaches may promote aortic root stability by correcting NO homeostasis, which if properly optimized may improve outcomes in this population afflicted by a notoriously refractory type of aortopathy.