Glycoproteomic Analysis of the Aortic Extracellular Matrix in Marfan Patients.

OBJECTIVE: Marfan syndrome (MFS) is caused by mutations in FBN1 (fibrillin-1), an extracellular matrix (ECM) component, which is modified post-translationally by glycosylation. This study aimed to characterize the glycoproteome of the aortic ECM from patients with MFS and relate it to aortopathy. Approach and Results: ECM extracts of aneurysmal ascending aortic tissue from patients with and without MFS were enriched for glycopeptides. Direct N-glycopeptide analysis by mass spectrometry identified 141 glycoforms from 47 glycosites within 35 glycoproteins in the human aortic ECM. Notably, MFAP4 (microfibril-associated glycoprotein 4) showed increased and more diverse N-glycosylation in patients with MFS compared with control patients. MFAP4 mRNA levels were markedly higher in MFS aortic tissue. MFAP4 protein levels were also increased at the predilection (convexity) site for ascending aorta aneurysm in bicuspid aortic valve patients, preceding aortic dilatation. In human aortic smooth muscle cells, MFAP4 mRNA expression was induced by TGF (transforming growth factor)-ß1 whereas siRNA knockdown of MFAP4 decreased FBN1 but increased elastin expression. These ECM changes were accompanied by differential gene expression and protein abundance of proteases from ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family and their proteoglycan substrates, respectively. Finally, high plasma MFAP4 concentrations in patients with MFS were associated with a lower thoracic descending aorta distensibility and greater incidence of type B aortic dissection during 68 months follow-up. CONCLUSIONS: Our glycoproteomics analysis revealed that MFAP4 glycosylation is enhanced, as well as its expression during the advanced, aneurysmal stages of MFS compared with control aneurysms from patients without MFS.

Aortic microcalcification is associated with elastin fragmentation in Marfan syndrome.

Marfan syndrome (MFS) is a connective tissue disorder in which aortic rupture is the major cause of death. MFS patients with an aortic diameter below the advised limit for prophylactic surgery (<5 cm) may unexpectedly experience an aortic dissection or rupture, despite yearly monitoring. Hence, there is a clear need for improved prognostic markers to predict such aortic events. We hypothesize that elastin fragments play a causal role in aortic calcification in MFS, and that microcalcification serves as a marker for aortic disease severity. To address this hypothesis, we analysed MFS patient and mouse aortas. MFS patient aortic tissue showed enhanced microcalcification in areas with extensive elastic lamina fragmentation in the media. A causal relationship between medial injury and microcalcification was revealed by studies in vascular smooth muscle cells (SMCs); elastin peptides were shown to increase the activity of the calcification marker alkaline phosphatase (ALP) and reduce the expression of the calcification inhibitor matrix GLA protein in human SMCs. In murine Fbn1C1039G/+ MFS aortic SMCs, Alpl mRNA and activity were upregulated as compared with wild-type SMCs. The elastin peptide-induced ALP activity was prevented by incubation with lactose or a neuraminidase inhibitor, which inhibit the elastin receptor complex, and a mitogen-activated protein kinase kinase-1/2 inhibitor, indicating downstream involvement of extracellular signal-regulated kinase-1/2 (ERK1/2) phosphorylation. Histological analyses in MFS mice revealed macrocalcification in the aortic root, whereas the ascending aorta contained microcalcification, as identified with the near-infrared fluorescent bisphosphonate probe OsteoSense-800. Significantly, microcalcification correlated strongly with aortic diameter, distensibility, elastin breaks, and phosphorylated ERK1/2. In conclusion, microcalcification co-localizes with aortic elastin degradation in MFS aortas of humans and mice, where elastin-derived peptides induce a calcification process in SMCs via the elastin receptor complex and ERK1/2 activation. We propose microcalcification as a novel imaging marker to monitor local elastin degradation and thus predict aortic events in MFS patients. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Resveratrol Inhibits Aortic Root Dilatation in the Fbn1C1039G/+ Marfan Mouse Model.

OBJECTIVE: Marfan syndrome (MFS) is a connective tissue disorder caused by mutations in the fibrillin-1 gene. Patients with MFS are at risk of aortic aneurysm formation and dissection. Usually, blood pressure-lowering drugs are used to reduce aortic events; however, this is not sufficient for most patients. In the aorta of smooth muscle cell-specific sirtuin-1-deficient mice, spontaneous aneurysm formation and senescence are observed. Resveratrol is known to enhance sirtuin-1 activity and to reduce senescence, which prompted us to investigate the effectiveness of resveratrol in inhibition of aortic dilatation in the Fbn1(C1039G/+) MFS mouse model. APPROACH AND RESULTS: Aortic senescence strongly correlates with aortic root dilatation rate in MFS mice. However, although resveratrol inhibits aortic dilatation, it only shows a trend toward reduced aortic senescence. Resveratrol enhances nuclear localization of sirtuin-1 in the vessel wall and, in contrast to losartan, does not affect leukocyte infiltration nor activation of SMAD2 and extracellular signal-regulated kinases 1/2 (ERK1/2). Interestingly, specific sirtuin-1 activation (SRT1720) or inhibition (sirtinol) in MFS mice does not affect aortic root dilatation rate, although senescence is changed. Resveratrol reduces aortic elastin breaks and decreases micro-RNA-29b expression coinciding with enhanced antiapoptotic Bcl-2 expression and decreased number of terminal apoptotic cells. In cultured smooth muscle cells, the resveratrol effect on micro-RNA-29b downregulation is endothelial cell and nuclear factor κB-dependent. CONCLUSIONS: Resveratrol inhibits aortic root dilatation in MFS mice by promoting elastin integrity and smooth muscle cell survival, involving downregulation of the aneurysm-related micro-RNA-29b in the aorta. On the basis of these data, resveratrol holds promise as a novel intervention strategy for patients with MFS.

Genotype impacts survival in Marfan syndrome.

AIMS: The aorta in Marfan syndrome (MFS) patients is variably affected. We investigated the assumed genotype-effect on protein production as a risk factor for a severe aortic phenotype in adult MFS patients. METHODS AND RESULTS: We collected clinical and genetic data from all 570 adults with MFS who had been included in the Dutch CONgenital CORvitia registry since the start in 2001. Mean age was 36.5 ± 13.5 years (51.2% male, 28.9% prior aortic surgery, 8.2% prior aortic dissection). Patients were prospectively followed for a mean duration of 8.2 ± 3.1 years. Men had more frequently aortic surgery at baseline (38.0 vs. 19.4%, P < 0.001) and during follow-up (24.0 vs. 15.1%, P = 0.008) compared with women. After 10-year follow-up cumulative survival was 93.8% and dissection-free survival was 84.2%. We found a pathogenic FBN1 mutation in 357 patients, of whom 146 patients (40.9%) were positive for a mutation causing haploinsufficiency (reduced fibrillin-1 protein) and 211 (59.1%) for a mutation leading to a DN effect (abnormal fibrillin-1 protein). Corrected for age, sex, and previous aortic complications, patients with a haploinsufficient (HI) mutation had a 2.5-fold increased risk for cardiovascular death (hazard ratio, HR: 2.5, 95% CI: 1.0-6.1, P = 0.049), a 2.4-fold increased risk for the combined endpoint comprising death and dissection (HR: 2.4, 95% CI: 1.4-4.2, P < 0.001) and a 1.6-fold increased risk for any aortic complication compared with patients with a DN mutation (HR: 1.6, 95% CI 1.1-2.3, P = 0.014). CONCLUSION: Marfan syndrome patients with an HI mutation are at increased risk for cardiovascular death and aortic dissection compared with patients with a DN mutation.

Histopathology of aortic complications in bicuspid aortic valve versus Marfan syndrome: relevance for therapy?

Patients with bicuspid aortic valve (BAV) and patients with Marfan syndrome (MFS) are more prone to develop aortic dilation and dissection compared to persons with a tricuspid aortic valve (TAV). To elucidate potential common and distinct pathways of clinical relevance, we compared the histopathological substrates of aortopathy. Ascending aortic wall biopsies were divided in five groups: BAV (n = 36) and TAV (n = 23) without and with dilation and non-dilated MFS (n = 8). General histologic features, apoptosis, the expression of markers for vascular smooth muscle cell (VSMC) maturation, markers predictive for ascending aortic dilation in BAV, and expression of fibrillin-1 were investigated. Both MFS and BAV showed an altered distribution and decreased fibrillin-1 expression in the aorta and a significantly lower level of differentiated VSMC markers. Interestingly, markers predictive for aortic dilation in BAV were not expressed in the MFS aorta. The aorta in MFS was similar to the aorta in dilated TAV with regard to the presence of medial degeneration and apoptosis, while other markers for degeneration and aging like inflammation and progerin expression were low in MFS, comparable to BAV. Both MFS and BAV aortas have immature VSMCs, while MFS and TAV patients have a similar increased rate of medial degeneration. However, the mechanism leading to apoptosis is expected to be different, being fibrillin-1 mutation induced increased angiotensin-receptor-pathway signaling in MFS and cardiovascular aging and increased progerin in TAV. Our findings could explain why angiotensin inhibition is successful in MFS and less effective in TAV and BAV patients.

Losartan reduces aortic dilatation rate in adults with Marfan syndrome: a randomized controlled trial.

AIM: Patients with Marfan syndrome have an increased risk of life-threatening aortic complications, mostly preceded by aortic dilatation. Treatment with losartan, an angiotensin-II receptor-1 blocker, may reduce aortic dilatation rate in Marfan patients. METHODS AND RESULTS: In this multicentre, open-label, randomized controlled trial with blinded assessments, we compared losartan treatment with no additional treatment in operated and unoperated adults with Marfan syndrome. The primary endpoint was aortic dilatation rate at any predefined aortic level after 3 years of follow-up, as determined by magnetic resonance imaging. A total of 233 participants (47% female) underwent randomization to either losartan (n = 116) or no additional treatment (n = 117). Aortic root dilatation rate after 3.1 ± 0.4 years of follow-up was significantly lower in the losartan group than in controls (0.77 ± 1.36 vs. 1.35 ± 1.55 mm, P = 0.014). Aortic dilatation rate in the trajectory beyond the aortic root was not significantly reduced by losartan. In patients with prior aortic root replacement, aortic arch dilatation rate was significantly lower in the losartan group when compared with the control group (0.50 ± 1.26 vs. 1.01 ± 1.31 mm, P = 0.033). No significant differences in separate clinical endpoints or the composite endpoint (aortic dissection, elective aortic surgery, cardiovascular death) between the groups could be demonstrated. CONCLUSION: In adult Marfan patients, losartan treatment reduces aortic root dilatation rate. After aortic root replacement, losartan treatment reduces dilatation rate of the aortic arch.

Aortic disease in patients with Marfan syndrome: aortic volume assessment for surveillance.

PURPOSE: To assess the reproducibility of aortic volume estimates and to serially test their use in patients with Marfan syndrome. MATERIALS AND METHODS: The study was approved by the medical ethics committee and all subjects gave written informed consent. In 81 patients with Marfan syndrome and seven healthy control subjects, aortic volumes and diameters at baseline were estimated by means of contrast material-enhanced magnetic resonance (MR) imaging. At 3 years of follow-up, aortic expansion rate were calculated in a subgroup of 22 patients with Marfan syndrome. Total aortic volume was defined as volume measurement from the level of the aortic annulus to the aortic bifurcation. Intra- and interobserver agreement of aortic volume were calculated by using the intraclass correlation coefficient. Differences in variables were analyzed with the Student t test and logistic regression. Effect size was calculated. RESULTS: Intra- and interobserver agreement of aortic volume calculation was 0.996 and 0.980, respectively. Mean aortic volume was significantly greater in patients with Marfan syndrome than in control subjects (104 mL/m(2); 95% confidence interval [CI]: 95, 114 mL/m(2) vs 74 mL/m(2); 95% CI: 62, 87 mL/m(2); P < .001). In 22 patients with Marfan syndrome, mean aortic volume was increased at 3 years of follow-up (17 mL; 95% CI: 8, 26 mL; P = .001; effect size, 0.29), while mean aortic diameter did not increase significantly (0.4 mm; 95% CI: 0.0, 0.9 mm; P = .171; effect size, 0.13). CONCLUSION: Assessment of aortic volume is highly reproducible and may be suited for use in the detection of aortic expansion in patients with Marfan syndrome. SUPPLEMENTAL MATERIAL: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13122310/-/DC1.

Clinical features differ substantially between Caucasian and Asian populations of Marfan syndrome.

BACKGROUND: Prevention of aortic dissection and sudden death in patients with Marfan syndrome (MFS) requires accurate diagnosis. MFS is diagnosed by the Ghent criteria, which are primarily based on clinical features of Caucasian MFS populations. We determined whether the Ghent criteria apply to Asian MFS populations. METHODS AND RESULTS: In this multicenter study, we included 255 adult MFS patients according to the Ghent criteria of 2010. Patients were excluded if they were neither Caucasian nor Asian. The Asian MFS population (n=49) had a smaller body surface area (BSA: 1.8 m² vs. 2.0 m², P<0.001), a more severely affected aortic root (absolute aortic diameter: 42.9 mm vs. 43.3mm, P=0.802; corrected for BSA: 24.9 mm vs. 21.7 mm, P<0.001; Z-score: 4.5 vs. 3.6, P=0.013), and more often a positive systemic score (75.5% vs. 60.0%, P=0.045), but less frequently ectopia lentis (24.5% vs. 48.1%, P=0.004) compared with the Caucasian population (n=206). CONCLUSIONS: The Ghent criteria do not necessarily apply to Asian MFS populations, resulting in a more severely affected cardiovascular system. This may be related to under diagnosis of MFS by multiple factors, including the use of Z-score, and genetic and racial differences. The Ghent criteria should be adapted for Asian populations in order to accurately diagnose MFS.

Relationship between fibrillin-1 genotype and severity of cardiovascular involvement in Marfan syndrome.

BACKGROUND: The effect of FBN1 mutation type on the severity of cardiovascular manifestations in patients with Marfan syndrome (MFS) has been reported with disparity results. OBJECTIVES: This study aims to determine the impact of the FBN1 mutation type on aortic diameters, aortic dilation rates and on cardiovascular events (ie, aortic dissection and cardiovascular mortality). METHODS: MFS patients with a pathogenic FBN1 mutation followed at two specialised units were included. FBN1 mutations were classified as being dominant negative (DN; incorporation of non-mutated and mutated fibrillin-1 in the extracellular matrix) or having haploinsufficiency (HI; only incorporation of non-mutated fibrillin-1, thus a decreased amount of fibrillin-1 protein). Aortic diameters and the aortic dilation rate at the level of the aortic root, ascending aorta, arch, descending thoracic aorta and abdominal aorta by echocardiography and clinical endpoints comprising dissection and death were compared between HI and DN patients. RESULTS: Two hundred and ninety patients with MFS were included: 113 (39%) with an HI-FBN1 mutation and 177 (61%) with a DN-FBN1. At baseline, patients with HI-FBN1 had a larger aortic root diameter than patients with DN-FBN1 (HI: 39.3±7.2 mm vs DN: 37.3±6.8 mm, p=0.022), with no differences in age or body surface area. After a mean follow-up of 4.9±2.0 years, aortic root and ascending dilation rates were increased in patients with HI-FBN1 (HI: 0.57±0.8 vs DN: 0.28±0.5 mm/year, p=0.004 and HI: 0.59±0.9 vs DN: 0.30±0.7 mm/year, p=0.032, respectively). Furthermore, patients with HI-FBN1 tended to be at increased risk for the combined endpoint of dissection and death compared with patients with DN-FBN1 (HR: 3.3, 95% CI 1.0 to 11.4, p=0.060). CONCLUSIONS: Patients with an HI mutation had a more severely affected aortic phenotype, with larger aortic root diameters and a more rapid dilation rate, and tended to have an increased risk of death and dissections compared with patients with a DN mutation.

Heterogeneity of aortic disease severity in patients with Loeys-Dietz syndrome.

OBJECTIVE: This study aimed to determine aortic disease severity in patients with Loeys-Dietz syndrome (LDS). METHODS: Thirty-three patients with LDS diagnosed and followed up at our unit were included. After reviewing all family trees, 25 deceased family members with clear clinical suspicion of having had LDS were also included. Clinical presentation, aortic dilation rate by echocardiography and age at aortic surgery, dissection or death were determined. RESULTS: Median aortic diameter at diagnosis was 36 mm, 43% of the patients aged >40 years had a z-score <2. Median aortic root dilation rate was 0.67 mm/year (maximum 2.0 mm/year) over a median follow-up of 2 years (IQR 1.0-4.0). In the global cohort, 31/58 patients reached a clinical endpoint; 19% death, median age: 52 years; 14% dissection, median age: 36 years; 21% aortic surgery, median age: 53 years. As expected, probands had a higher z-score (2.9 vs 1.5, p=0.019) and more often required aortic surgery (33.4% vs 18.2%, p=0.035) compared with family members. TGFBR2 carriers had a higher z-score compared with TGFBR1 carriers (3.2 vs 1.5, p=0.034) and younger age at aortic surgery (HR 4.9, 95% CI 1.5 to 123, p=0.026). Craniofacial severity index was inversely correlated with age at first event (r=-0.765, p=0.045). CONCLUSIONS: Although paediatric patients were not properly represented in our cohort, our patients with LDS presented a significant heterogeneity in the severity of aortic disease with large intrafamilial and interfamilial variability, aortic root aneurysm were less frequent and aortic complications less premature than previously depicted. Furthermore, aortic dilation rate was similar to that reported in Marfan syndrome and aortic root diameters appear to be larger in TGFBR2 carriers.

Increased aortic tortuosity indicates a more severe aortic phenotype in adults with Marfan syndrome.

BACKGROUND: Patients with Marfan syndrome (MFS) have a highly variable occurrence of aortic complications. Aortic tortuosity is often present in MFS and may help to identify patients at risk for aortic complications. METHODS: 3D-visualization of the total aorta by MR imaging was performed in 211 adult MFS patients (28% with prior aortic root replacement) and 20 controls. A method to assess aortic tortuosity (aortic tortuosity index: ATI) was developed and reproducibility was tested. The relation between ATI and age, and body size and aortic dimensions at baseline was investigated. Relations between ATI at baseline and the occurrence of a clinical endpoint (aortic dissection, and/or aortic surgery) and aortic dilatation rate during 3 years of follow-up were investigated. RESULTS: ATI intra- and interobserver agreements were excellent (ICC: 0.968 and 0.955, respectively). Mean ATI was higher in 28 age-matched MFS patients than in the controls (1.92 ± 0.2 vs. 1.82 ± 0.1, p=0.048). In the total MFS cohort, mean ATI was 1.87 ± 0.20, and correlated with age (r=0.281, p<0.001), aortic root diameter (r=0.223, p=0.006), and aortic volume expansion rate (r=0.177, p=0.026). After 49.3 ± 8.8 months follow-up, 33 patients met the combined clinical endpoint (7 dissections) with a significantly higher ATI at baseline than patients without endpoint (1.98 ± 0.2 vs. 1.86 ± 0.2, p=0.002). Patients with an ATI>1.95 had a 12.8 times higher probability of meeting the combined endpoint (log rank-test, p<0.001) and a 12.1 times higher probability of developing an aortic dissection (log rank-test, p=0.003) compared to patients with an ATI<1.95. CONCLUSIONS: Increased ATI is associated with a more severe aortic phenotype in MFS patients.

The risk for type B aortic dissection in Marfan syndrome.

BACKGROUND: Aortic dissections involving the descending aorta are a major clinical problem in patients with Marfan syndrome. OBJECTIVES: The purpose of this study was to identify clinical parameters associated with type B aortic dissection and to develop a risk model to predict type B aortic dissection in patients with Marfan syndrome. METHODS: Patients with the diagnosis of Marfan syndrome and magnetic resonance imaging or computed tomographic imaging of the aorta were followed for a median of 6 years for the occurrence of type B dissection or the combined end point of type B aortic dissection, distal aortic surgery, and death. A model using various clinical parameters as well as genotyping was developed to predict the risk for type B dissection in patients with Marfan syndrome. RESULTS: Between 1998 and 2013, 54 type B aortic dissections occurred in 600 patients with Marfan syndrome (mean age 36 ± 14 years, 52% male). Independent variables associated with type B aortic dissection were prior prophylactic aortic surgery (hazard ratio: 2.1; 95% confidence interval: 1.2 to 3.8; p = 0.010) and a proximal descending aorta diameter ≥27 mm (hazard ratio: 2.2; 95% confidence interval: 1.1 to 4.3; p = 0.020). In the risk model, the 10-year occurrence of type B aortic dissection in low-, moderate-, and high-risk patients was 6%, 19%, and 34%, respectively. Angiotensin II receptor blocker therapy was associated with fewer type B aortic dissections (hazard ratio: 0.3; 95% confidence interval: 0.1 to 0.9; p = 0.030). CONCLUSIONS: Patients with Marfan syndrome with prior prophylactic aortic surgery are at substantial risk for type B aortic dissection, even when the descending aorta is only slightly dilated. Angiotensin II receptor blocker therapy may be protective in the prevention of type B aortic dissections.

Beneficial Outcome of Losartan Therapy Depends on Type of FBN1 Mutation in Marfan Syndrome.

BACKGROUND: It has been shown that losartan reduces aortic dilatation in patients with Marfan syndrome. However, treatment response is highly variable. This study investigates losartan effectiveness in genetically classified subgroups. METHODS AND RESULTS: In this predefined substudy of COMPARE, Marfan patients were randomized to daily receive losartan 100 mg or no losartan. Aortic root dimensions were measured by MRI at baseline and after 3 years. FBN1 mutations were classified based on fibrillin-1 protein effect into (1) haploinsufficiency, decreased amount of normal fibrillin-1, or (2) dominant negative, normal fibrillin-1 abundance with mutant fibrillin-1 incorporated in the matrix. A pathogenic FBN1 mutation was found in 117 patients, of whom 79 patients were positive for a dominant negative mutation (67.5%) and 38 for a mutation causing haploinsufficiency (32.5%). Baseline characteristics between treatment groups were similar. Overall, losartan significantly reduced aortic root dilatation rate (no losartan, 1.3±1.5 mm/3 years, n=59 versus losartan, 0.8±1.4 mm/3 years, n=58; P=0.009). However, losartan reduced only aortic root dilatation rate in haploinsufficient patients (no losartan, 1.8±1.5 mm/3 years, n=21 versus losartan 0.5±0.8 mm/3 years, n=17; P=0.001) and not in dominant negative patients (no losartan, 1.2±1.7 mm/3 years, n=38 versus losartan 0.8±1.3 mm/3 years, n=41; P=0.197). CONCLUSIONS: Marfan patients with haploinsufficient FBN1 mutations seem to be more responsive to losartan therapy for inhibition of aortic root dilatation rate compared with dominant negative patients. Additional treatment strategies are needed in Marfan patients with dominant negative FBN1 mutations. CLINICAL TRIAL REGISTRATION: http://www.trialregister.nl/trialreg/index.asp; Unique Identifier: NTR1423.

No beneficial effect of general and specific anti-inflammatory therapies on aortic dilatation in Marfan mice.

AIMS: Patients with Marfan syndrome have an increased risk of life-threatening aortic complications, mostly preceded by aortic dilatation. In the FBN1(C1039G/+) Marfan mouse model, losartan decreases aortic root dilatation. We recently confirmed this beneficial effect of losartan in adult patients with Marfan syndrome. The straightforward translation of this mouse model to man is reassuring to test novel treatment strategies. A number of studies have shown signs of inflammation in aortic tissue of Marfan patients. This study examined the efficacy of anti-inflammatory therapies in attenuating aortic root dilation in Marfan syndrome and compared effects to the main preventative agent, losartan. METHODS AND RESULTS: To inhibit inflammation in FBN1(C1039G/+) Marfan mice, we treated the mice with losartan (angiotensin II receptor type 1 inhibitor), methylprednisolone (corticosteroid) or abatacept (T-cell-specific inhibitor). Treatment was initiated in adult Marfan mice with already existing aortic root dilatation, and applied for eight weeks. Methylprednisolone- or abatacept-treated mice did not reveal a reduction in aortic root dilatation. In this short time frame, losartan was the only treatment that significantly reduced aorta inflammation, transforming growth factor-beta (TGF-ß) signaling and aortic root dilatation rate in these adult Marfan mice. Moreover, the methylprednisolone-treated mice had significantly more aortic alcian blue staining as a marker for aortic damage. CONCLUSION: Anti-inflammatory agents do not reduce the aortic dilatation rate in Marfan mice, but possibly increase aortic damage. Currently, the most promising therapeutic drug in Marfan syndrome is losartan, by blocking the angiotensin II receptor type 1 and thereby inhibiting pSmad2 signaling.

Circulating transforming growth factor-ß as a prognostic biomarker in Marfan syndrome.

BACKGROUND: Patients with Marfan syndrome (MFS) are at risk for cardiovascular disease. Marfan associated mutations in the FBN1 gene lead to increased transforming growth factor-ß (TGF-ß) activation. The aim of this study was to investigate the role of plasma TGF-ß as a biomarker for progressive aortic root dilatation and dissection. METHODS: Plasma TGF-ß level and aortic root diameter by means of echocardiography were assessed in 99 MFS patients. After 38 months of follow-up measurement of the aortic root was repeated and individual aortic root growth curves were constructed. Clinical events were evaluated. The primary composite endpoint was defined as aortic dissection and prophylactic aortic root replacement. RESULTS: TGF-ß levels were higher in MFS patients as compared to healthy controls (109 pg/ml versus 54 pg/ml, p<0.001). Higher plasma TGF-ß levels correlated with larger aortic root dimensions (r=0.26, p=0.027), previous aortic root surgery (161 pg/ml versus 88 pg/ml, p=0.007) and faster aortic root growth rate (r=0.42, p<0.001). During 38 months of follow-up, 17 events were observed (four type B dissections and 13 aortic root replacements). Patients with TGF-ß levels above 140 pg/ml had a 6.5 times higher risk of experiencing the composite endpoint compared to patients with TGF-ß levels below 140 pg/ml (95% CI: 2.1 to 20.1, p=0.001) with 65% sensitivity and 78% specificity. CONCLUSION: Elevated TGF-ß level in patients with Marfan syndrome is correlated with larger aortic root diameters and faster aortic root growth. Level of plasma TGF-ß predicts cardiovascular events and might serve as a prognostic biomarker in MFS.

Current and future pharmacological treatment strategies with regard to aortic disease in Marfan syndrome.

INTRODUCTION: Marfan syndrome is a multisystemic connective tissue disorder caused mainly by mutations in the fibrillin-1 gene. The entire cardiovascular system is affected in patients with Marfan syndrome. Aortic root dilatation, aortic valve regurgitation or - the most feared and life-threatening symptom - aortic root dissection are the most common manifestations. Therapeutic strategies, such as prophylactic aortic root surgery and pharmacological therapy, focus on the prevention of aortic dissection. Currently, the standard medicinal treatments targeting aortic dilatation and dissection consist of agents generally used to lower blood pressure and/or the inotropic state of the heart. By these means, the cyclic repetitive forces exerted on the aortic wall are diminished and thus the onset of aortic dilatation is potentially prevented. Although these pharmacological agents may offer some benefit in reduction of aortic aneurysm expansion rate, they do not target the underlying cause of the progressive aortic degradation. AREAS COVERED: This review discusses the effectiveness of frequently prescribed medications used to prevent and delay aortic complications in Marfan syndrome. New insights on the biochemical pathways leading to aortic disease are also discussed to highlight new targets for pharmacological therapy. EXPERT OPINION: Recent insights in the transforming growth factor beta signaling pathway and inflammatory mechanisms in a well-established mouse model of Marfan syndrome, have led to studies exploring new pharmacological treatment strategies with doxycycline, statins and angiotensin II receptor blockers. Pharmacological therapy is focused more on prevention than on delay of aortic wall pathology in Marfan syndrome. Of the new pharmacological treatment strategies targeting aortic pathology in Marfan syndrome, angiotensin receptor type 1 blockers are promising candidates, with several clinical trials currently ongoing.