Neutrophil elastase cleaves epithelial cadherin in acutely injured lung epithelium

International audienceAbstractBackgroundIn acutely injured lungs, massively recruited polymorphonuclear neutrophils (PMNs) secrete abnormally neutrophil elastase (NE). Active NE creates a localized proteolytic environment where various host molecules are degraded leading to impairment of tissue homeostasis. Among the hallmarks of neutrophil-rich pathologies is a disrupted epithelium characterized by the loss of cell-cell adhesion and integrity. Epithelial-cadherin (E-cad) represents one of the most important intercellular junction proteins. E-cad exhibits various functions including its role in maintenance of tissue integrity. While much interest has focused on the expression and role of E-cad in different physio- and physiopathological states, proteolytic degradation of this structural molecule and ensuing potential consequences on host lung tissue injury are not completely understood.MethodsNE capacity to cleave E-cad was determined in cell-free and lung epithelial cell culture systems. The impact of such cleavage on epithelial monolayer integrity was then investigated. Using mice deficient in NE in a clinically relevant experimental model of acute pneumonia, we examined whether degraded E-cad is associated with lung inflammation and injury and whether NE contributes to E-cad cleavage. Finally, we checked for the presence of both degraded E-cad and NE in bronchoalveolar lavage samples obtained from patients with exacerbated COPD, a clinical manifestation characterised by a neutrophilic inflammatory response.ResultsWe show that NE is capable of degrading E-cad in vitro and in cultured cells. NE-mediated degradation of E-cad was accompanied with loss of epithelial monolayer integrity. Our in vivo findings provide evidence that NE contributes to E-cad cleavage that is concomitant with lung inflammation and injury. Importantly, we observed that the presence of degraded E-cad coincided with the detection of NE in diseased human lungs.ConclusionsActive NE has the capacity to cleave E-cad and interfere with its cell-cell adhesion function. These data suggest a mechanism by which unchecked NE participates potentially to the pathogenesis of neutrophil-rich lung inflammatory and tissue-destructive diseases

A genetic landscape of familial predisposition to sarcoidosis identified by whole exome sequencing

International audienc

Variations in pockmark composition at the Vestnesa Ridge: Insights from marine controlled source electromagnetic and seismic data

The Vestnesa Ridge marks the northern boundary of a known submarine gas hydrate province in the west Svalbard margin. Several seafloor pockmarks at the eastern segment of the ridge are sites of active methane venting. Until recently, seismic reflection data were the main tool for imaging beneath the ridge. Coincident controlled source electromagnetic (CSEM), high-resolution two-dimensional (2-D) airgun, sweep frequency SYSIF, and three-dimensional (3-D) p-cable seismic reflection data were acquired at the south-eastern part of the ridge between 2011 and 2013. The CSEM and seismic data contain profiles across and along the ridge, passing several active and inactive pockmarks. Joint interpretation of resistivity models obtained from CSEM and seismic reflection data provides new information regarding the fluid composition beneath the pockmarks. There is considerable variation in transverse resistance and seismic reflection characteristics of the gas hydrate stability zone (GHSZ) between the ridge flanks and chimneys beneath pockmarks. Layered seismic reflectors on the flanks are associated with around 300 Ωm2 transverse resistance, whereas the seismic reflectors within the chimneys exhibit amplitude blanking and chaotic patterns. The transverse resistance of the GHSZ within the chimneys vary between 400 and 1200 Ωm2. Variance attributes obtained from the 3-D p-cable data also highlight faults and chimneys, which coincide with the resistivity anomalies. Based on the joint data interpretation, widespread gas hydrate presence is likely at the ridge, with both hydrates and free gas contained within the faults and chimneys. However, at the active chimneys the effect of gas likely dominates the resistive anomalies

Whole exome sequencing in three families segregating a pediatric case of sarcoidosis

International audienceAbstractBackgroundSarcoidosis (OMIM 181000) is a multi-systemic granulomatous disorder of unknown origin. Despite multiple genome-wide association (GWAS) studies, no major pathogenic pathways have been identified to date. To find out relevant sarcoidosis predisposing genes, we searched for de novo and recessive mutations in 3 young probands with sarcoidosis and their healthy parents using a whole-exome sequencing (WES) methodology.MethodsFrom the SARCFAM project based on a national network collecting familial cases of sarcoidosis, we selected three families (trios) in which a child, despite healthy parents, develop the disease before age 15 yr. Each trio was genotyped by WES (Illumina HiSEQ 2500) and we selected the gene variants segregating as 1) new mutations only occurring in affected children and 2) as recessive traits transmitted from each parents. The identified coding variants were compared between the three families. Allelic frequencies and in silico functional results were analyzed using ExAC, SIFT and Polyphenv2 databases. The clinical and genetic studies were registered by the ClinicalTrials.gov - Protocol Registration and Results System (PRS) (https://clinicaltrials.gov) receipt under the reference NCT02829853 and has been approved by the ethical committee (CPP LYON SUD EST – 2 – REF IRB 00009118 – September 21, 2016).ResultsWe identified 37 genes sharing coding variants occurring either as recessive mutations in at least 2 trios or de novo mutations in one of the three affected children. The genes were classified according to their potential roles in immunity related pathways: 9 to autophagy and intracellular trafficking, 6 to G-proteins regulation, 4 to T-cell activation, 4 to cell cycle and immune synapse, 2 to innate immunity. Ten of the 37 genes were studied in a bibliographic way to evaluate the functional link with sarcoidosis.ConclusionsWhole exome analysis of case-parent trios is useful for the identification of genes predisposing to complex genetic diseases as sarcoidosis. Our data identified 37 genes that could be putatively linked to a pediatric form of sarcoidosis in three trios. Our in-depth focus on 10 of these 37 genes may suggest that the formation of the characteristic lesion in sarcoidosis, granuloma, results from combined deficits in autophagy and intracellular trafficking (ex: Sec16A, AP5B1 and RREB1), G-proteins regulation (ex: OBSCN, CTTND2 and DNAH11), T-cell activation (ex: IDO2, IGSF3), mitosis and/or immune synapse (ex: SPICE1 and KNL1). The significance of these findings needs to be confirmed by functional tests on selected gene variants

Additional file 1: of Whole exome sequencing in three families segregating a pediatric case of sarcoidosis

Table S1. Recessive variants found in at least two affected children of different trios. Possibly pathogenic recessive variants (polymorphisms) found by whole-exome -sequencing in at least two affected children of the trios (T). Chr., chromosome; SNP, single nucleotide polymorphism; QUAL., a quality parameter measuring the probability p that the observation of the variant is due to chance (for ex: QUAL = n, p = 1/n). As detailed in the text, Alamut® Visual integrates missense variant pathogenicity prediction tools and in silico study of variants’ effect on RNA splicing, allowing the assessment of their potential impact on splice junctions and splicing regulatory sequences. Alamut® Visual helped us also to exclude well known mutations identified in recessive diseases for those genes which have been related to known genetic diseases (as shown in Table 3). (DOCX 23 kb

Additional file 6: of Whole exome sequencing in three families segregating a pediatric case of sarcoidosis

All recessive variants identified in cases T1, T2 and T3. The de novo dominant variants have been fully described in the manuscript. The datasets of cases T1, T2 and T3 extracted from VCF (Variant call Format) and extracted in XLS file. (XLSX 368 kb

Additional file 4: of Whole exome sequencing in three families segregating a pediatric case of sarcoidosis

Figure S1. CADD scoring of prioritized variants versus other variants in the selected genes. (PDF 71 kb

Additional file 2: of Whole exome sequencing in three families segregating a pediatric case of sarcoidosis

Table S2. Recessive variants shared by a common gene in at least two different trios. Possibly pathogenic recessive variants observed at different positions for a single gene in at least two affected children of the trios (T). Abbreviations are the same as in Tables 1, 2 and Additional file 1: Table S1. (DOCX 31 kb

Additional file 3: of Whole exome sequencing in three families segregating a pediatric case of sarcoidosis

Table S3. Composite heterozygocity observed in a common gene in at least two different trios. Possibly pathogenic compound heterozygous variants (allelic heterogeneity) observed in different positions of a common gene in at least two trios. The origin of either the paternal and maternal allele was detailed for each variant. Abbreviations are the same as in Tables 1, 2, Additional files 1 and 2: Tables S1 and S2. (DOCX 51 kb