Rudolf A. de Boer

Identification of seven loci affecting mean telomere length and their association with disease

Interindividual variation in mean leukocyte telomere length (LTL) is associated with cancer and several age-associated diseases. We report here a genome-wide meta-analysis of 37,684 individuals with replication of selected variants in an additional 10,739 individuals. We identified seven loci, including five new loci, associated with mean LTL (P < 5 × 10−8). Five of the loci contain candidate genes (TERC, TERT, NAF1, OBFC1 and RTEL1) that are known to be involved in telomere biology. Lead SNPs at two loci (TERC and TERT) associate with several cancers and other diseases, including idiopathic pulmonary fibrosis. Moreover, a genetic risk score analysis combining lead variants at all 7 loci in 22,233 coronary artery disease cases and 64,762 controls showed an association of the alleles associated with shorter LTL with increased risk of coronary artery disease (21% (95% confidence interval, 5–35%) per standard deviation in LTL, P = 0.014). Our findings support a causal role of telomere-length variation in some age-related diseases.

Predictive value of plasma galectin-3 levels in heart failure with reduced and preserved ejection fraction

Abstract Aims. Galectin-3 is an emerging biomarker which has been studied in relatively small heart failure (HF) cohorts with predominantly systolic HF. We studied the prognostic value of base-line galectin-3 in a large HF cohort, with preserved and reduced left ventricular ejection fraction (LVEF), and compared this to other biomarkers. Methods. We studied 592 HF patients who had been hospitalized for HF and were followed for 18 months. The primary end-point was a composite of all-cause mortality and HF hospitalization. Results. A doubling of galectin-3 levels was associated with a hazard ratio (HR) of 1.97 (1.62–2.42) for the primary outcome (P < 0.001). After correction for age, gender, BNP, eGFR, and diabetes the HR was 1.38 (1.07–1.78; P = 0.015). Galectin-3 levels were correlated with higher IL-6 and CRP levels (P < 0.002). Changes of galectin-3 levels after 6 months did not add prognostic information to the base-line value (n = 291); however, combining plasma galectin-3 and BNP levels increased prognostic value over either biomarker alone (ROC analysis, P < 0.05). The predictive value of galectin-3 was stronger in patients with preserved LVEF (n = 114) compared to patients with reduced LVEF (P < 0.001). Conclusions. Galectin-3 is an independent marker for outcome in HF and appears to be particularly useful in HF patients with preserved LVEF.

Galectin-3: a novel mediator of heart failure development and progression

Galectins are a family of soluble β‐galactoside‐binding lectins that play many important regulatory roles in inflammation, immunity, and cancer. Recently, a role for galectin‐3 in the pathophysiology of heart failure (HF) has been suggested. Numerous studies have demonstrated the up‐regulation of galectin‐3 in hypertrophied hearts, its stimulatory effect on macrophage migration, fibroblast proliferation, and the development of fibrosis. The latter observation is particularly relevant as cardiac remodelling is an important determinant of the clinical outcome of HF and is linked to disease progression and poor prognosis. Because galectin‐3 expression is maximal at peak fibrosis and virtually absent after recovery, routine measurement in patients with HF may prove valuable to identify those patients at highest risk for readmission or death, thus enabling physicians to tailor the level of care to individual patient needs. This review summarizes the most recent advances in galectin‐3 research, with an emphasis on the role galectin‐3 plays in the development and progression of HF.

Common variants near TERC are associated with mean telomere length

We conducted genome-wide association analyses of mean leukocyte telomere length in 2,917 individuals, with follow-up replication in 9,492 individuals. We identified an association with telomere length on 3q26 (rs12696304, combined P = 3.72 × 10−14) at a locus that includes TERC, which encodes the telomerase RNA component. Each copy of the minor allele of rs12696304 was associated with an ∼75-base-pair reduction in mean telomere length, equivalent to ∼3.6 years of age-related telomere-length attrition.

Incidence and epidemiology of new onset heart failure with preserved vs. reduced ejection fraction in a community-based cohort: 11-year follow-up of PREVEND

AIMS Differences in clinical characteristics and outcome of patients with established heart failure with preserved ejection fraction (HFpEF) and heart failure with reduced ejection fraction (HFrEF) are well established. Data on epidemiology and prediction of new onset HFpEF, compared with HFrEF, have not been described. METHODS AND RESULTS In 8592 subjects of the Prevention of Renal and Vascular End-stage Disease (PREVEND), a community-based, middle-aged cohort study, we performed cause-specific hazard analyses to study the predictive value of risk factors and established cardiovascular biomarkers on new onset HFrEF vs. HFpEF (left ventricular ejection fraction ≤ 40 and ≥ 50%, respectively). A P-value for competing risk (Pcr) <0.10 between HFrEF and HFpEF was considered statistically significant. All potential new onset heart failure cases were reviewed and adjudicated to HFrEF or HFpEF by an independent committee. During a median follow-up of 11.5 years, 374 (4.4%) subjects were diagnosed with heart failure, of which 125 (34%) with HFpEF and 241 (66%) with HFrEF. The average time to diagnosis of new onset HFrEF was 6.6 ± 3.6 years; it was 8.3 ± 3.3 years for HFpEF (P < 0.001). Male gender was associated with new onset HFrEF, whereas female gender with new onset HFpEF (Pcr < 0.001). Higher age and increased N-terminal pro-B-type natriuretic peptide (NT-proBNP) increased the risk for both HFpEF and HFrEF, although for age this was stronger for HFpEF (Pcr = 0.018), whereas NT-proBNP was stronger associated with risk for HFrEF (Pcr = 0.083). Current smokers, increased highly sensitive troponin T, and previous myocardial infarction conferred a significantly increased risk for HFrEF, but not for HFpEF (Pcr = 0.093, 0.091, and 0.061, respectively). Conversely, a history of atrial fibrillation, increased urinary albumin excretion (UAE), and cystatin C were significantly more associated with the risk for HFpEF, but not for HFrEF (Pcr < 0.001, 0.061, and 0.033, respectively). The presence of obesity at baseline was associated with comparable prognostic information for both HFpEF and HFrEF. CONCLUSION Higher age, UAE, cystatin C, and history of atrial fibrillation are strong risk factors for new onset HFpEF. This underscores differential pathophysiological mechanisms for both subtypes of heart failure.

Genetic and Pharmacological Inhibition of Galectin-3 Prevents Cardiac Remodeling by Interfering with Myocardial Fibrogenesis

Background— Galectin-3 has been implicated in the development of organ fibrosis. It is unknown whether it is a relevant therapeutic target in cardiac remodeling and heart failure. Methods and Results— Galectin-3 knock-out and wild-type mice were subjected to angiotensin II infusion (2.5 µg/kg for 14 days) or transverse aortic constriction for 28 days to provoke cardiac remodeling. The efficacy of the galectin-3 inhibitor N-acetyllactosamine was evaluated in TGR(mREN2)27 (REN2) rats and in wild-type mice with the aim of reversing established cardiac remodeling after transverse aortic constriction. In wild-type mice, angiotensin II and transverse aortic constriction perturbations caused left-ventricular (LV) hypertrophy, decreased fractional shortening, and increased LV end-diastolic pressure and fibrosis (P<0.05 versus control wild type). Galectin-3 knock-out mice also developed LV hypertrophy but without LV dysfunction and fibrosis (P=NS). In REN2 rats, pharmacological inhibition of galectin-3 attenuated LV dysfunction and fibrosis. To elucidate the beneficial effects of galectin-3 inhibition on myocardial fibrogenesis, cultured fibroblasts were treated with galectin-3 in the absence or presence of galectin-3 inhibitor. Inhibition of galectin-3 was associated with a downregulation in collagen production (collagen I and III), collagen processing, cleavage, cross-linking, and deposition. Similar results were observed in REN2 rats. Inhibition of galectin-3 also attenuated the progression of cardiac remodeling in a long-term transverse aortic constriction mouse model. Conclusions— Genetic disruption and pharmacological inhibition of galectin-3 attenuates cardiac fibrosis, LV dysfunction, and subsequent heart failure development. Drugs binding to galectin-3 may be potential therapeutic candidates for the prevention or reversal of heart failure with extensive fibrosis.

Universal risk factors for multifactorial diseases: LifeLines: a three-generation population-based study.

The risk for multifactorial diseases is determined by risk factors that frequently apply across disorders (universal risk factors). To investigate unresolved issues on etiology of and individual’s susceptibility to multifactorial diseases, research focus should shift from single determinant-outcome relations to effect modification of universal risk factors. We present a model to investigate universal risk factors of multifactorial diseases, based on a single risk factor, a single outcome measure, and several effect modifiers. Outcome measures can be disease overriding, such as clustering of disease, frailty and quality of life. “Life course epidemiology” can be considered as a specific application of the proposed model, since risk factors and effect modifiers of multifactorial diseases typically have a chronic aspect. Risk factors are categorized into genetic, environmental, or complex factors, the latter resulting from interactions between (multiple) genetic and environmental factors (an example of a complex factor is overweight). The proposed research model of multifactorial diseases assumes that determinant-outcome relations differ between individuals because of modifiers, which can be divided into three categories. First, risk-factor modifiers that determine the effect of the determinant (such as factors that modify gene-expression in case of a genetic determinant). Second, outcome modifiers that determine the expression of the studied outcome (such as medication use). Third, generic modifiers that determine the susceptibility for multifactorial diseases (such as age). A study to assess disease risk during life requires phenotype and outcome measurements in multiple generations with a long-term follow up. Multiple generations will also enable to separate genetic and environmental factors. Traditionally, representative individuals (probands) and their first-degree relatives have been included in this type of research. We put forward that a three-generation design is the optimal approach to investigate multifactorial diseases. This design has statistical advantages (precision, multiple-informants, separation of non-genetic and genetic familial transmission, direct haplotype assessment, quantify genetic effects), enables unique possibilities to study social characteristics (socioeconomic mobility, partner preferences, between-generation similarities), and offers practical benefits (efficiency, lower non-response). LifeLines is a study based on these concepts. It will be carried out in a representative sample of 165,000 participants from the northern provinces of the Netherlands. LifeLines will contribute to the understanding of how universal risk factors are modified to influence the individual susceptibility to multifactorial diseases, not only at one stage of life but cumulatively over time: the lifeline.

Galectin-3 Mediates Aldosterone-Induced Vascular Fibrosis

Objective—Aldosterone (Aldo) is involved in arterial stiffness and heart failure, but the mechanisms have remained unclear. Galectin-3 (Gal-3), a &bgr;-galactoside-binding lectin, plays an important role in inflammation, fibrosis, and heart failure. We investigated here whether Gal-3 is involved in Aldo-induced vascular fibrosis. Methods and Results—In rat vascular smooth muscle cells Gal-3 overexpression enhanced specifically collagen type I synthesis. Moreover Gal-3 inhibition by modified citrus pectin or small interfering RNA blocked Aldo-induced collagen type I synthesis. Rats were treated with Aldo-salt combined with spironolactone or modified citrus pectin for 3 weeks. Hypertensive Aldo-treated rats presented vascular hypertrophy, inflammation, fibrosis, and increased aortic Gal-3 expression. Spironolactone or modified citrus pectin treatment reversed all the above effects. Wild-type and Gal-3 knock-out mice were treated with Aldo for 6 hours or 3 weeks. Aldo increased aortic Gal-3 expression, inflammation, and collagen type I in wild-type mice at both the short- and the long-term, whereas no changes occurred in Gal-3 knock-out mice. Conclusion—Our data indicate that Gal-3 is required for inflammatory and fibrotic responses to Aldo in vascular smooth muscle cells in vitro and in vivo, suggesting a key role for Gal-3 in vascular fibrosis.

An evaluation of the beta-1 adrenergic receptor Arg389Gly polymorphism in individuals with heart failure: a MERIT-HF sub-study.

The Glycine389 variant of the beta‐1 adrenergic receptor (β1AR) generates markedly less cAMP when stimulated in vitro than the more prevalent Arginine389 variant.

Phospholamban R14del mutation in patients diagnosed with dilated cardiomyopathy or arrhythmogenic right ventricular cardiomyopathy: evidence supporting the concept of arrhythmogenic cardiomyopathy

To investigate whether phospholamban gene (PLN) mutations underlie patients diagnosed with either arrhythmogenic right ventricular cardiomyopathy (ARVC) or idiopathic dilated cardiomyopathy (DCM).