Clinical and Functional Characterization of a Novel Mutation in Lamin A/C Gene in a Multigenerational Family with Arrhythmogenic Cardiac Laminopathy

Mutations in the lamin A/C gene (LMNA) were associated with dilated cardiomyopathy (DCM) and, recently, were related to severe forms of arrhythmogenic right ventricular cardiomyopathy (ARVC). Both genetic and phenotypic overlap between DCM and ARVC was observed; molecular pathomechanisms leading to the cardiac phenotypes caused by LMNA mutations are not yet fully elucidated. This study involved a large Italian family, spanning 4 generations, with arrhythmogenic cardiomyopathy of different phenotypes, including ARVC, DCM, system conduction defects, ventricular arrhythmias, and sudden cardiac death. Mutation screening of LMNA and ARVC-related genes PKP2, DSP, DSG2, DSC2, JUP, and CTNNA3 was performed. We identified a novel heterozygous mutation (c.418_438dup) in LMNA gene exon 2, occurring in a highly conserved protein domain across several species. This newly identified variant was not found in 250 ethnically-matched control subjects. Genotype-phenotype correlation studies suggested a co-segregation of the LMNA mutation with the disease phenotype and an incomplete and age-related penetrance. Based on clinical, pedigree, and molecular genetic data, this mutation was considered likely disease-causing. To clarify its potential pathophysiologic impact, functional characterization of this LMNA mutant was performed in cultured cardiomyocytes expressing EGFP-tagged wild-type and mutated LMNA constructs, and indicated an increased nuclear envelope fragility, leading to stress-induced apoptosis as the main pathogenetic mechanism. This study further expands the role of the LMNA gene in the pathogenesis of cardiac laminopathies, suggesting that LMNA should be included in mutation screening of patients with suspected arrhythmogenic cardiomyopathy, particularly when they have ECG evidence for conduction defects. The combination of clinical, genetic, and functional data contribute insights into the pathogenesis of this form of life-threatening arrhythmogenic cardiac laminopathy.     

Paternal age and telomere length in twins: the germ stem cell selection paradigm

Telomere length, a highly heritable trait, is longer in offspring of older fathers. This perplexing feature has been attributed to the longer telomeres in sperm of older men and it might be an ‘epigenetic’ mechanism through which paternal age plays a role in telomere length regulation in humans. Based on two independent (discovery and replication) twin studies, comprising 889 twin pairs, we show an increase in the resemblance of leukocyte telomere length between dizygotic twins of older fathers, which is not seen in monozygotic twins. This phenomenon might result from a paternal age‐dependent germ stem cell selection process, whereby the selected stem cells have longer telomeres, are more homogenous with respect to telomere length, and share resistance to aging.     

Characterisation of a label‐free biosensor based on long period grating

Optical fibre gratings, especially long period gratings, have been recently proposed as optical devices for biochemical sensing. A biochemical interaction along the grating portion induces a refractive index change and hence a change in the fiber transmission spectrum. This provides an alternative methodology with respect to other label‐free optical approaches, such as surface plasmon resonance, interferometric configurations and optical resonators. The fibre biofunctionalization has been carried out by means of a novel chemistry using Eudragit L100 copolymer as opposed to the commonly used silanization procedure. Antigen‐antibody interaction has been analysed by means of an IgG/anti‐IgG bioassay. The biosensor was fully characterised, monitoring the kinetics during the antibody immobilization and the antigen interaction and achieving the calibration curve of the assay. A comparison of the biosensor performance was made by using two different long period gratings with distinct periods. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Phenotyping COPD by 1H NMR metabolomics of exhaled breath condensate

Spirometry is used to establish the diagnosis of chronic obstructive pulmonary disease (COPD) and to assess disease progression, but it seems inadequate to characterize COPD phenotypes. Metabolomics has been introduced for molecular fingerprinting of biosamples in a variety of clinical disorders. The aim of the study was to establish whether exhaled breath condensate (EBC) in COPD features a distinct metabolic fingerprint, and to identify the metabolites that characterize the EBC profile in COPD. EBC was collected using a home-made glass condenser in 37 stable COPD patients, and 25 non-obstructed controls. Samples were analyzed using proton nuclear magnetic resonance spectroscopy (¹H NMR). Random forest was applied for both supervised and unsupervised learning, using spectral buckets as input variables. Metabolomics of EBC discriminated COPD patients from controls with an overall accuracy of 86 %. As compared to controls, EBC from COPD featured significantly lower (p < 0.05) levels of acetone, valine and lysine, and significantly higher (p < 0.05) levels of lactate, acetate, propionate, serine, proline, and tyrosine. Based on unsupervised analysis of NMR spectra, the COPD sample was split in three clusters, one of which had the highest prevalence of radiologic emphysema. NMR spectroscopy of EBC holds promise in COPD fingerprinting. It may prove valuable in outcome studies, and in assessing the efficacy of therapeutic interventions.     

Forced IDO1 expression in dendritic cells restores immunoregulatory signalling in autoimmune diabetes

Indoleamine 2,3‐dioxygenase (IDO1), a tryptophan catabolizing enzyme, is recognized as an authentic regulator of immunity in several physiopathologic conditions. We have recently demonstrated that IDO1 does not merely degrade tryptophan and produce immunoregulatory kynurenines, but it also acts as a signal‐transducing molecule, independently of its enzymic function. IDO1 signalling activity is triggered in plasmacytoid dendritic cells (pDCs) by transforming growth factor‐β (TGF‐β), an event that requires the non‐canonical NF‐κB pathway and induces long‐lasting IDO1 expression and autocrine TGF‐β production in a positive feedback loop, thus sustaining a stably regulatory phenotype in pDCs. IDO1 expression and catalytic function are defective in pDCs from non‐obese diabetic (NOD) mice, a prototypic model of autoimmune diabetes. In the present study, we found that TGF‐β failed to activate IDO1 signalling function as well as up‐regulate IDO1 expression in NOD pDCs. Moreover, TGF‐β‐treated pDCs failed to exert immunosuppressive properties in vivo. Nevertheless, transfection of NOD pDCs with Ido1 prior to TGF‐β treatment resulted in activation of the Ido1 promoter and induction of non‐canonical NF‐κB and TGF‐β, as well as decreased production of the pro‐inflammatory cytokines, interleukin 6 (IL‐6) and tumour necrosis factor‐α (TNF‐α). Overexpression of IDO1 in TGF‐β‐treated NOD pDCs also resulted in pDC ability to suppress the in vivo presentation of a pancreatic β‐cell auto‐antigen. Thus, our data suggest that a correction of IDO1 expression may restore its dual function and thus represent a proper therapeutic manoeuvre in this autoimmune setting.     

Podocyte Developmental Defects Caused by Adriamycin in Zebrafish Embryos and Larvae: A Novel Model of Glomerular Damage

The zebrafish pronephros is gaining popularity in the nephrology community, because embryos are easy to cultivate in multiwell plates, allowing large number of experiments to be conducted in an in vivo model. In a few days, glomeruli reach complete development, with a structure that is similar to that of the mammalian counterpart, showing a fenestrated endothelium and a basement membrane covered by the multiple ramifications of mature podocytes. As a further advantage, zebrafish embryos are permeable to low molecular compounds, and this explains their extensive use in drug efficacy and toxicity experiments. Here we show that low concentrations of adriamycin (i.e. 10 and 20 µM), when dissolved in the medium of zebrafish embryos at 9 hours post-fertilization and removed after 48 hours (57 hpf), alter the development of podocytes with subsequent functional impairment, demonstrated by onset of pericardial edema and reduction of expression of the podocyte proteins nephrin and wt1. Podocyte damage is morphologically confirmed by electron microscopy and functionally supported by increased clearance of microinjected 70 kDa fluorescent dextran. Importantly, besides pericardial edema and glomerular damage, which persist and worsen after adriamycin removal from the medium, larvae exposed to adriamycin 10 and 20 µM do not show any myocardiocyte alterations nor vascular changes. The only extra-renal effect is a transient delay of cartilage formation that rapidly recovers once adriamycin is removed. In summary, this low dose adriamycin model can be applied to analyze podocyte developmental defects, such as those observed in congenital nephrotic syndrome, and can be taken in consideration for pharmacological studies of severe early podocyte injury.     

Gain of ALK Gene Copy Number May Predict Lack of Benefit from Anti-EGFR Treatment in Patients with Advanced Colorectal Cancer and RAS-RAF-PI3KCA Wild-Type Status

Introduction

Although cetuximab and panitumumab show an increased efficacy for patients with KRAS-NRAS-BRAF and PI3KCA wild-type metastatic colorectal cancer, primary resistance occurs in a relevant subset of molecularly enriched populations.

Patients and Methods

We evaluated the outcome of 68 patients with advanced colorectal cancer and RAS, BRAF and PI3KCA status according to ALK gene status (disomic vs. gain of ALK gene copy number – defined as mean of 3 to 5 fusion signals in ≥10% of cells). All consecutive patients received cetuximab and irinotecan or panitumumab alone for chemorefractory disease.

Results

No ALK translocations or amplifications were detected. ALK gene copy number gain was found in 25 (37%) tumors. Response rate was significantly higher in patients with disomic ALK as compared to those with gain of gene copy number (70% vs. 32%; p = 0.0048). Similarly, progression-free survival was significantly different when comparing the two groups (6.7 vs. 5.3 months; p = 0.045). A trend was observed also for overall survival (18.5 vs. 15.6 months; p = 0.885).

Conclusion

Gain of ALK gene copy number might represent a negative prognostic factor in mCRC and may have a role in resistance to anti-EGFR therapy.