TET2-Driven Clonal Hematopoiesis and Response to Canakinumab: An Exploratory Analysis of the CANTOS Randomized Clinical Trial.

Importance: Clonal hematopoiesis of indeterminate potential (CHIP) is associated with increased risk of atherosclerotic cardiovascular disease, and mouse experiments suggest that CHIP related to Tet2 loss of function in myeloid cells accelerates atherosclerosis via augmented interleukin (IL) 1ß signaling. Objective: To assess whether individuals with CHIP have greater cardiovascular event reduction in response to IL-1ß neutralization in the Canankinumab Anti-inflammatory Thrombosis Outcomes Trial (CANTOS). Design, Setting, and Participants: This randomized clinical trial took place from April 2011 to June 2017 at more than 1000 clinical sites in 39 countries. Targeted deep sequencing of genes previously associated with CHIP in a subset of trial participants using genomic DNA prepared from baseline peripheral blood samples were analyzed. All participants had prior myocardial infarction and elevated high-sensitivity C-reactive protein level above 0.20 mg/dL. Analysis took place between June 2017 and December 2021. Interventions: Canakinumab, an anti-IL-1ß antibody, given at doses of 50, 150, and 300 mg once every 3 months. Main Outcomes and Measures: Major adverse cardiovascular events (MACE). Results: A total of 338 patients (8.6%) were identified in this subset with evidence for clonal hematopoiesis. As expected, the incidence of CHIP increased with age; the mean (SD) age of patients with CHIP was 66.3 (9.2) years and 61.5 (9.6) years in patients without CHIP. Unlike other populations that were not preselected for elevated C-reactive protein, in the CANTOS population variants in TET2 were more common than DNMT3A (119 variants in 103 patients vs 86 variants in 85 patients). Placebo-treated patients with CHIP showed a nonsignificant increase in the rate of MACE compared with patients without CHIP using a Cox proportional hazard model (hazard ratio, 1.32 [95% CI, 0.86-2.04]; P = .21). Exploratory analyses of placebo-treated patients with a somatic variant in either TET2 or DNMT3A (n = 58) showed an equivocal risk for MACE (hazard ratio, 1.65 [95% CI, 0.97-2.80]; P = .06). Patients with CHIP due to somatic variants in TET2 also had reduced risk for MACE while taking canakinumab (hazard ratio, 0.38 [95% CI, 0.15-0.96]) with equivocal difference compared with others (P for interaction = .14). Conclusions and Relevance: These results are consistent with observations of increased risk for cardiovascular events in patients with CHIP and raise the possibility that those with TET2 variants may respond better to canakinumab than those without CHIP. Future studies are required to further substantiate this hypothesis. Trial Registration: ClinicalTrials.gov Identifier: NCT01327846.

LLF580, an FGF21 Analog, Reduces Triglycerides and Hepatic Fat in Obese Adults With Modest Hypertriglyceridemia.

PURPOSE: To evaluate the safety and potential efficacy of LLF580, a genetically engineered variant of human fibroblast growth factor-21, for triglyceride lowering, weight loss, and hepatic fat reduction. METHODS: A multicenter, double-blind, parallel design trial in obese, mildly hypertriglyceridemic adults randomized (1:1) to LLF580 300 mg or placebo subcutaneously every 4 weeks for 3 doses. RESULTS: Of 64 randomized study participants, 61 (mean ± SD: age 45 ± 11 years, 49% male, 80/15/5% Caucasian/African American/other, body mass index 36.1 ± 3.8 kg/m2) received LLF580 (n = 30) or placebo (n = 31) at 7 research sites in the United States. LLF580 lowered serum triglycerides by 54% (least square mean placebo adjusted change from baseline), total cholesterol 7%, low-density lipoprotein cholesterol 12%, and increased high-density lipoprotein cholesterol 36% compared with placebo (all P < 0.001) over 12 weeks. Substantial reduction of liver fat of 52% over placebo (P < 0.001) was also demonstrated in the setting of improved liver function tests including alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase, the composite enhanced liver fibrosis score, and N-terminal type III collagen propeptide (all P < 0.05). Insulin and C-peptide levels and insulin resistance by homeostatic model assessment for insulin resistance were all lower, and adiponectin higher with LLF580 treatment compared with placebo, whereas fasting glucose and glycated hemoglobin were unchanged. Reductions in biomarkers of bone formation without differences in markers of bone resorption were observed. LLF580 was generally safe and well tolerated, except for higher incidence of generally mild to moderate gastrointestinal adverse effects. CONCLUSIONS: In obese, mildly hypertriglyceridemic adults, LLF580 was generally safe and demonstrated beneficial effects on serum lipids, liver fat, and biomarkers of liver injury, suggesting it may be effective for treatment of select metabolic disorders including hypertriglyceridemia and nonalcoholic fatty liver disease. Assessments of longer term safety and efficacy are warranted. CLINICALTRIALS.GOV IDENTIFIER: NCT03466203.

Constitutively Activating GNAS Somatic Mutation in Right Ventricular Outflow Tract Tachycardia.

[Figure: see text].

Licogliflozin versus placebo in women with polycystic ovary syndrome: A randomized, double-blind, phase 2 trial.

Polycystic ovary syndrome (PCOS) is characterized by hyperandrogenism and insulin resistance. The dual sodium-glucose co-transporter 1/2 inhibitor (SGLT1/2i) licogliflozin (LIK066) ameliorates hyperinsulinism in patients with diabetes and obesity. This study examines the effect of licogliflozin on androgens in women with PCOS. In a multicentre, randomized, placebo-controlled, double-blind, 2-week trial, patients with PCOS received licogliflozin 50 mg or placebo three times a day (TID). Changes in free testosterone (FT), other androgens and variables of insulin resistance were analysed. Concentration of FT did not change (TRLIK066 :TRPCB [FT]: 0.88; 90% CI: 0.70-1.11; P = .353). Licogliflozin reduced androstendione (A4) by 19% (TRLIK066 :TRPCB [A4]: 0.81; 90% CI: 0.68-0.99; P = .089) and dehydroepiandrosteron sulphate (DHEAS) by 24% (TRLIK066 :TRPCB [DHEAS]: 0.76; 90% CI: 0.65-0.89; P = .008). Hyperinsulinaemia was reduced by 70% by licogliflozin (highest insulin concentration [MAXI]; TRLIK066 :TRPCB [MAXI]: 0·26; 90% CI:0.20-0.34; P < .001 and area under the curve insulin [AUCI]; TRLIK066 :TRPCB [AUCI]: 0.32; 90% CI: 0.25-0.41; P < .001). Diarrhoea and nausea occurred as common adverse events. Dual inhibition of SGLT1/2 ameliorates hyperinsulinaemia and hyperandrogenaemia in women with PCOS. Licogliflozin may represent a promising novel treatment option for PCOS.

A randomized, placebo-controlled trial of canakinumab in patients with peripheral artery disease.

Extensive atherosclerotic plaque burden in the lower extremities often leads to symptomatic peripheral artery disease (PAD) including impaired walking performance and claudication. Interleukin-1ß (IL-1ß) may play an important pro-inflammatory role in the pathogenesis of this disease. Interruption of IL-1ß signaling was hypothesized to decrease plaque progression in the leg macrovasculature and improve the mobility of patients with PAD with intermittent claudication. Thirty-eight patients (mean age 65 years; 71% male) with symptomatic PAD (confirmed by ankle-brachial index) were randomized 1:1 to receive canakinumab (150 mg subcutaneously) or placebo monthly for up to 12 months. The mean vessel wall area (by 3.0 T black-blood magnetic resonance imaging (MRI)) of the superficial femoral artery (SFA) was used to measure plaque volume. Mobility was assessed using the 6-minute walk test. Canakinumab was safe and well tolerated. Markers of systemic inflammation (interleukin-6 and high-sensitivity C-reactive protein) fell as early as 1 month after treatment. MRI (32 patients at 3 months; 21 patients at 12 months) showed no evidence of plaque progression in the SFA in either placebo-treated or canakinumab-treated patients. Although an exploratory endpoint, placebo-adjusted maximum and pain-free walking distance (58 m) improved as early as 3 months after treatment with canakinumab when compared with placebo. Although canakinumab did not alter plaque progression in the SFA, there is an early signal that it may improve maximum and pain-free walking distance in patients with symptomatic PAD. Larger studies aimed at this endpoint will be required to definitively demonstrate this. ClinicalTrials.gov Identifier: NCT01731990.

MAA868, a novel FXI antibody with a unique binding mode, shows durable effects on markers of anticoagulation in humans.

A large unmet medical need exists for safer antithrombotic drugs because all currently approved anticoagulant agents interfere with hemostasis, leading to an increased risk of bleeding. Genetic and pharmacologic evidence in humans and animals suggests that reducing factor XI (FXI) levels has the potential to effectively prevent and treat thrombosis with a minimal risk of bleeding. We generated a fully human antibody (MAA868) that binds the catalytic domain of both FXI (zymogen) and activated FXI. Our structural studies show that MAA868 traps FXI and activated FXI in an inactive, zymogen-like conformation, explaining its equally high binding affinity for both forms of the enzyme. This binding mode allows the enzyme to be neutralized before entering the coagulation process, revealing a particularly attractive anticoagulant profile of the antibody. MAA868 exhibited favorable anticoagulant activity in mice with a dose-dependent protection from carotid occlusion in a ferric chloride-induced thrombosis model. MAA868 also caused robust and sustained anticoagulant activity in cynomolgus monkeys as assessed by activated partial thromboplastin time without any evidence of bleeding. Based on these preclinical findings, we conducted a first-in-human study in healthy subjects and showed that single subcutaneous doses of MAA868 were safe and well tolerated. MAA868 resulted in dose- and time-dependent robust and sustained prolongation of activated partial thromboplastin time and FXI suppression for up to 4 weeks or longer, supporting further clinical investigation as a potential once-monthly subcutaneous anticoagulant therapy.

Arterial Effects of Canakinumab in Patients With Atherosclerosis and Type 2 Diabetes or Glucose Intolerance.

BACKGROUND: Evidence suggests that interleukin (IL)-1ß is important in the pathogenesis of atherosclerosis and its complications and that inhibiting IL-1ß may favorably affect vascular disease progression. OBJECTIVES: The goal of this study was to evaluate the effects of IL-1ß inhibition with canakinumab versus placebo on arterial structure and function, determined by magnetic resonance imaging. METHODS: Patients (N = 189) with atherosclerotic disease and either type 2 diabetes mellitus or impaired glucose tolerance were randomized to receive placebo (n = 94) or canakinumab 150 mg monthly (n = 95) for 12 months. They underwent magnetic resonance imaging of the carotid arteries and aorta. RESULTS: There were no statistically significant differences between canakinumab compared with placebo in the primary efficacy and safety endpoints. There was no statistically significant change in mean carotid wall area and no effect on aortic distensibility, measured at 3 separate anatomic sites. The change in mean carotid artery wall area was -3.37 mm2 after 12 months with canakinumab versus placebo. High-sensitivity C-reactive protein was significantly reduced by canakinumab compared with placebo at 3 months (geometric mean ratio [GMR]: 0.568; 95% confidence interval [CI]: 0.436 to 0.740; p < 0.0001) and 12 months (GMR: 0.56; 95% CI: 0.414 to 0.758; p = 0.0002). Lipoprotein(a) levels were reduced by canakinumab compared with placebo (-4.30 mg/dl [range: -8.5 to -0.55 mg/dl]; p = 0.025] at 12 months), but triglyceride levels increased (GMR: 1.20; 95% CI: 1.046 to 1.380; p = 0.01). In these patients with type 2 diabetes mellitus or impaired glucose tolerance, canakinumab had no effect compared with placebo on any of the measures assessed by using a standard oral glucose tolerance test. CONCLUSIONS: There were no statistically significant effects of canakinumab on measures of vascular structure or function. Canakinumab reduced markers of inflammation (high-sensitivity C-reactive protein and interleukin-6), and there were modest increases in levels of total cholesterol and triglycerides. (Safety & Effectiveness on Vascular Structure and Function of ACZ885 in Atherosclerosis and Either T2DM or IGT Patients; NCT00995930).

Aortic Dissection in Patients With Genetically Mediated Aneurysms: Incidence and Predictors in the GenTAC Registry.

BACKGROUND: Aortic dissection (AoD) is a serious complication of thoracic aortic aneurysm (TAA). Relative risk for AoD in relation to TAA etiology, incidence, and pattern after prophylactic TAA surgery are poorly understood. OBJECTIVES: This study sought to determine the incidence, pattern, and relative risk for AoD among patients with genetically associated TAA. METHODS: The population included adult GenTAC participants without AoD at baseline. Standardized core laboratory tests classified TAA etiology and measured aortic size. Follow-up was performed for AoD. RESULTS: Bicuspid aortic valve (BAV) (39%) and Marfan syndrome (MFS) (22%) were the leading diagnoses in the studied GenTAC participants (n = 1,991). AoD occurred in 1.6% over 3.6 ± 2.0 years; 61% of AoD occurred in patients with MFS. Cumulative AoD incidence was 6-fold higher among patients with MFS (4.5%) versus others (0.7%; p < 0.001). MFS event rates were similarly elevated versus those in patients with BAV (0.3%; p < 0.001). AoD originated in the distal arch or descending aorta in 71%; 52% of affected patients, including 68% with MFS, had previously undergone aortic grafting. In patients with proximal aortic surgery, distal aortic size (descending thoracic, abdominal aorta) was larger among patients with AoD versus those without AoD (both p < 0.05), whereas the ascending aorta size was similar. Conversely, in patients without previous surgery, aortic root size was greater in patients with subsequent AoD (p < 0.05), whereas distal aortic segments were of similar size. MFS (odds ratio: 7.42; 95% confidence interval: 3.43 to 16.82; p < 0.001) and maximal aortic size (1.86 per cm; 95% confidence interval: 1.26 to 2.67; p = 0.001) were independently associated with AoD. Only 4 of 31 (13%) patients with AoD had pre-dissection images that fulfilled size criteria for prophylactic TAA surgery at a subsequent AoD site. CONCLUSIONS: Among patients with genetically associated TAA, MFS augments risk for AoD even after TAA grafting. Although increased aortic size is a risk factor for subsequent AoD, events typically occur below established thresholds for prophylactic TAA repair.

Tbx5 is required for avian and Mammalian epicardial formation and coronary vasculogenesis.

RATIONALE: Holt-Oram syndrome is an autosomal dominant heart-hand syndrome caused by mutations in the TBX5 gene. Overexpression of Tbx5 in the chick proepicardial organ impaired coronary blood vessel formation. However, the potential activity of Tbx5 in the epicardium itself, and the role of Tbx5 in mammalian coronary vasculogenesis, remains largely unknown. OBJECTIVE: To evaluate the consequences of altered Tbx5 gene dosage during proepicardial organ and epicardial development in the embryonic chick and mouse. METHODS AND RESULTS: Retroviral-mediated knockdown or upregulation of Tbx5 expression in the embryonic chick proepicardial organ and proepicardial-specific deletion of Tbx5 in the embryonic mouse (Tbx5(epi-/)) impaired normal proepicardial organ cell development, inhibited epicardial and coronary blood vessel formation, and altered developmental gene expression. The generation of epicardial-derived cells and their migration into the myocardium were impaired between embryonic day (E) 13.5 to 15.5 in mutant hearts because of delayed epicardial attachment to the myocardium and subepicardial accumulation of epicardial-derived cells. This caused defective coronary vasculogenesis associated with impaired vascular smooth muscle cell recruitment and reduced invasion of cardiac fibroblasts and endothelial cells into myocardium. In contrast to wild-type hearts that exhibited an elaborate ventricular vascular network, Tbx5(epi-/-) hearts displayed a marked decrease in vascular density that was associated with myocardial hypoxia as exemplified by hypoxia inducible factor-1α upregulation and increased binding of hypoxyprobe-1. Tbx5(epi-/-) mice with such myocardial hypoxia exhibited reduced exercise capacity when compared with wild-type mice. CONCLUSIONS: Our findings support a conserved Tbx5 dose-dependent requirement for both proepicardial and epicardial progenitor cell development in chick and in mouse coronary vascular formation.

Keratin gene expression profiles after digit amputation in C57BL/6 vs. regenerative MRL mice imply an early regenerative keratinocyte activated-like state.

Mouse strains C57BL/6 (B6) and MRL were studied by whole mouse genome chip microarray analyses of RNA isolated from amputation sites at different times pre- and postamputation at the midsecond phalange of the middle digit. Many keratin genes were highly differentially expressed. All keratin genes were placed into three temporal response classes determined by injury/preinjury ratios. One class, containing only Krt6 and Krt16, were uniquely expressed relative to the other two classes and exhibited different temporal responses in MRL vs. B6. Immunohistochemical staining for Krt6 and Krt16 in tissue sections, including normal digit, flank skin, and small intestine, and from normal and injured ear pinna tissue exhibited staining differences in B6 (low) and MRL (high) that were consistent with the microarray results. Krt10 staining showed no injury-induced differences, consistent with microarray expression. We analyzed Krt6 and Krt16 gene association networks and observed in uninjured tissue several genes with higher expression levels in MRL, but not B6, that were associated with the keratinocyte activated state: Krt6, Krt16, S100a8, S100a9, and Il1b; these data suggest that keratinocytes in the MRL strain, but not in B6, are in an activated state prior to wounding. These expression levels decreased in MRL at all times postwounding but rose in the B6, peaking at day 3. Other keratins significantly expressed in the normal basal keratinocyte state showed no significant strain differences. These data suggest that normal MRL skin is in a keratinocyte activated state, which may provide it with superior responses to wounding.

TGFßRIIb mutations trigger aortic aneurysm pathogenesis by altering transforming growth factor ß2 signal transduction.

BACKGROUND: Thoracic aortic aneurysm (TAA) is a common progressive disorder involving gradual dilation of the ascending and/or descending thoracic aorta that eventually leads to dissection or rupture. Nonsydromic TAA can occur as a genetically triggered, familial disorder that is usually transmitted in a monogenic autosomal dominant fashion and is known as familial TAA. Genetic analyses of families affected with TAA have identified several chromosomal loci, and further mapping of familial TAA genes has highlighted disease-causing mutations in at least 4 genes: myosin heavy chain 11 (MYH11), α-smooth muscle actin (ACTA2), and transforming growth factor ß receptors I and II (TGFßRI and TGFßRII). METHODS AND RESULTS: We evaluated 100 probands to determine the mutation frequency in MYH11, ACTA2, TGFßRI, and TGFßRII in an unbiased population of individuals with genetically mediated TAA. In this study, 9% of patients had a mutation in one of the genes analyzed, 3% of patients had mutations in ACTA2, 3% in MYH11, 1% in TGFßRII, and no mutations were found in TGFßRI. Additionally, we identified mutations in a 75 base pair alternatively spliced TGFßRII exon, exon 1a that produces the TGFßRIIb isoform and accounted for 2% of patients with mutations. Our in vitro analyses indicate that the TGFßRIIb activating mutations alter receptor function on TGFß2 signaling. CONCLUSIONS: We propose that TGFßRIIb expression is a regulatory mechanism for TGFß2 signal transduction. Dysregulation of the TGFß2 signaling pathway, as a consequence of TGFßRIIb mutations, results in aortic aneurysm pathogenesis.

The National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions (GenTAC): results from phase I and scientific opportunities in phase II.

BACKGROUND: Genetically triggered thoracic aortic conditions (GenTACs) represent an important problem for patients and their families. Accordingly, the National Heart, Lung, and Blood Institute established the first phase of its national GenTAC Registry in 2006. ENROLLMENT AND DIAGNOSES: Between 2007 and 2010, 6 enrolling centers established the GenTAC I Registry consisting of 2,046 patients (Marfan syndrome 576 [28.2%], bicuspid aortic valve disease 504 [24.6%], aneurysm or dissection age <50 years 369 [18%], and others). Biologic samples for DNA analyses (white blood cells or saliva) are available in 97%, and stored plasma is available in 60% of enrollees. RESULTS: Initial scientific inquiry using the GenTAC Registry has included validation studies of genetic causes for aortic syndromes, potential usefulness of transforming growth factor beta (TGFB) blood levels in Marfan subjects, and current surgical approaches to ascending aortic conditions. FUTURE OPPORTUNITY: The second phase of GenTAC will allow biannual follow-up of GenTAC I enrollees for up to 9 years, enrollment of an additional 1,500 subjects, further integration of imaging findings with clinical and genetic data through utilization of an imaging core laboratory, important validation of phenotype-genotype correlations through a phenotyping core laboratory, and integration of a scientific advisory committee to help define the full range and depth of the Registry's scientific capabilities. The registry resources are available to the external scientific community through an application process accessible at https://gentac.rti.org.

Impact of image analysis methodology on diagnostic and surgical classification of patients with thoracic aortic aneurysms.

BACKGROUND: For patients with thoracic aortic aneurysms (TAA), aortic size on imaging is widely used to guide clinical decision making. This study examined the impact of methodological variance on aortic quantification. METHODS: We studied enrollees in the National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions. Aortic size on computed tomography was quantified by 2 linear methods; cross-sectional dimensions in axial (AX) and double oblique (DO) plane. Calculated area was compared to planimetry. Established cutoffs (area/height>10 cm2/m, diameter≥5 cm) for prophylactic TAA repair were used to compare surgical eligibility by each method. RESULTS: Fifty subjects were studied. Aortic size differed between AX and DO at all locations (p≤0.001), with magnitude greatest at the sinotubular junction (4.8±1.1 vs 4.0±1.0 cm, p<0.001). The difference between AX and DO correlated with aortic angular displacement (r=0.37, p<0.01), which was threefold larger at the sinotubular junction (37±12 degrees) than the ascending aorta (12±5 degrees; p<0.001). At all locations, aortic area calculated using DO yielded smaller differences with planimetry than AX (p<0.05). DO and planimetry yielded equal prevalence (24%) of subjects eligible for prophylactic TAA repair based on area-height cutoff, whereas AX prevalence was higher (44%; p=0.006). Using a linear cutoff, AX yielded over a twofold greater prevalence of surgically eligible subjects (56%) than did DO (24%; p<0.001). CONCLUSIONS: Established linear methods for aortic measurement yield different results that impact surgical eligibility. DO yielded improved agreement with planimetry and differed with AX in proportion to aortic geometric obliquity. Findings support DO measurements for imaging evaluation of subjects with TAA.

The molecular genetics of congenital heart disease: a review of recent developments.

PURPOSE OF REVIEW: Our understanding of the interactions of genes and pathways during heart development continues to expand with our knowledge of the genetic basis of congenital heart disease. Along with the discovery of specific genes that cause lesions, recent research has focused on the interactions of some previously identified genes. This review focuses on the progress made during the last year. RECENT FINDINGS: T-box, NK, and GATA transcription factors have known associations with a variety of syndromic and isolated congenital heart defects. Discovery of novel interactions of GATA and T-box transcription factors highlights the direction of recent research. In addition, the critical yet somewhat redundant roles of nkx2.5 and nkx2.7, along with the interaction of nkx2.7 with tbx20, have been elucidated. The contributions of still other transcription factor classes are being elucidated. Further understanding of 22q11.2 deletion and microduplication syndromes and their genetic interactions has also been studied. Recent work also highlights PTPN11 and NOTCH1 in Noonan syndrome. SUMMARY: The recent developments in the genetics of congenital heart disease are reviewed. In many cases, it is the novel interactions of previously known genes that highlight this year's developments. These interactions will ultimately lead to better understanding of downstream transcriptional or signaling pathways.

Specification of the cardiac conduction system by transcription factors.

Diseases of the cardiovascular system that cause sudden cardiac deaths are often caused by lethal arrhythmias that originate from defects in the cardiac conduction system. Development of the cardiac conduction system is a complex biological process that can be wrought with problems. Although several genes involved in mature conduction system function have been identified, their association with development of specific subcomponents of the cardiac conduction system remains challenging. Several transcription factors, including homeodomain proteins and T-box proteins, are essential for cardiac conduction system morphogenesis and activation or repression of key regulatory genes. In addition, several transcription factors modify expression of genes encoding the ion channel proteins that contribute to the electrophysiological properties of the conduction system and govern contraction of the surrounding myocardium. Loss of transcriptional regulation during cardiac development has detrimental effects on cardiogenesis that may lead to arrhythmias. Human genetic mutations in some of these transcription factors have been identified and are known to cause congenital heart diseases that include cardiac conduction system malformations. In this review, we summarize the contributions of several key transcription factors to specification, patterning, maturation, and function of the cardiac conduction system. Further analysis of the molecular programs involved in this process should lead to improved diagnosis and therapy of conduction system disease.

Surgical treatment of patients enrolled in the national registry of genetically triggered thoracic aortic conditions.

BACKGROUND: Genetic disorders are an important cause of thoracic aortic aneurysms (TAAs) in young patients. Despite advances in the treatment of genetically triggered TAAs, the optimal syndrome-specific treatment approach remains undefined. We used data from the National Institutes of Health-funded, multicenter National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions (GenTAC) to characterize the contemporary surgical treatment of patients with genetically triggered TAAs. METHODS: GenTAC's aim is to collect longitudinal clinical data and banked biospecimens from 2800 patients with genetically triggered TAAs. We analyzed data from the 606 patients (mean age, 37.5 years) enrolled in GenTAC to date whose clinical data were available. RESULTS: The patients' primary diagnoses included Marfan syndrome (35.8%), bicuspid aortic valve with aneurysm (29.2%), and familial TAAs and dissections (10.7%). Of these, 56.4% had undergone at least one operation; the most common indications were aneurysm (85.7%), valve dysfunction (65.8%), and dissection (25.4%). Surgical procedures included replacement of the aortic root (50.6%), ascending aorta (64.8%), aortic arch (27.9%), and descending or thoracoabdominal aorta (12.4%). Syndrome-specific differences in age, indications for operation, and procedure type were identified. CONCLUSIONS: Patients with genetically transmitted TAAs evaluated in tertiary care centers frequently undergo surgical repair. Aneurysm repairs most commonly involve the aortic root and ascending aorta; distal repairs are less common. Like TAAs themselves, complications of TAAs, including dissection and aortic valve dysfunction, are important indications for intervention. Future studies will focus on syndrome- and gene-specific phenotypes, biomarkers, treatments, and outcomes to improve the treatment of patients with TAAs.

Secreted Frizzled-related protein 2 is a procollagen C proteinase enhancer with a role in fibrosis associated with myocardial infarction.

Secreted Frizzled-related proteins (sFRPs) have emerged as key regulators of a wide range of developmental and disease processes. Most of the known functions of mammalian sFRPs have been attributed to their ability to antagonize Wnt signalling. Recently however, Xenopus laevis and zebrafish sFRP, Sizzled, was shown to function as an antagonist of Chordin processing by Tolloid-like metalloproteinases. This has led to the proposal that sFRPs may function as evolutionarily conserved antagonists of chordinase activities of this class of proteinases. In contrast to this proposal, we show here that the mammalian sFRP, sFRP2, does not affect Chordin processing, but instead, can serve as a direct enhancer of procollagen C proteinase activity of Tolloid-like metalloproteinases. We also show that the level of fibrosis, in which procollagen processing by Tolloid-like proteinases has a rate-limiting role, is markedly reduced in Sfrp2-null mice subjected to myocardial infarction. Importantly, this reduced level of fibrosis is accompanied by significantly improved cardiac function. This study thus uncovers a function for sFRP2 and a potential therapeutic application for sFRP2 antagonism in controlling fibrosis in the infarcted heart.