Hereditary erythrocytosis (HE) is a rare hematological disorder characterized by an excess of red blood cell production. Here we describe a European collaborative study involving a collection of 2160 ...patients with erythrocytosis sequenced in 10 different laboratories. We focused our study on the EGLN1 gene and identified 39 germline missense variants including one gene deletion in 47 probands. EGLN1 encodes the PHD2 prolyl 4-hydroxylase, a major inhibitor of the Hypoxia-Inducible Factor. We performed a comprehensive study to evaluate the causal role of the identified PHD2 variants: in silico study of localization, conservation, and deleterious effects; analysis of hematological parameters of carriers identified in the UK Biobank; functional studies of the protein activity and stability; and comprehensive study of PHD2 splicing. Altogether, this study allowed the classification of 16 pathogenic or likely pathogenic mutants in a total of 48 patients and relatives. The in silico studies extented to the variants described in the literature showed that a minority of PHD2 variants can be classified as pathogenic (36/96), without any differences with the variants of unknown significance regarding the severity of the developed disease (hematological parameters and complications). Here, we demonstrated the great value of federating laboratories working on such rare pathology to implement the criteria required for genetic classification, a strategy that should be extended to all hereditary hematological diseases.
Faecalibacterium prausnitzii, a member of the Clostridium IV group of the Firmicutes phylum that is abundant in the intestinal microbiota, has anti-inflammatory effects. The relative level of F ...prausnitzii is decreased in fecal samples from patients with inflammatory bowel diseases (IBDs) compared with healthy individuals. Reduced F prausnitzii was correlated with relapse of Crohn’s disease after surgery. We identified, in human colonic mucosa and blood, a population of T regulatory type 1–like T regulatory (TREG) cells that express CD4 and CD8α (DP8α T cells) and are specific for F prausnitzii. We aimed to determine whether they are altered in patients with IBD.
We isolated DP8α T cells from human colon lamina propria and blood samples and used flow cytometry to detect markers of cells that are of colon origin. We quantified DP8α cells that express colon-specific markers in blood samples from 106 patients with IBD, 12 patients with infectious colitis, and 35 healthy donors (controls). We identified cells that respond to F prausnitzii. Cells were stimulated with anti-CD3, and their production of interleukin 10 was measured by enzyme-linked immunosorbent assay. We compared the frequency and reactivity of cells from patients vs controls using the 2-sided Student t test or 1-way analysis of variance.
Circulating DP8α T cells that proliferate in response to F prausnitzii express the C-C motif chemokine receptor 6 (CCR6) and C-X-C motif chemokine receptor 6 (CXCR6). These cells also have features of TREG cells, including production of IL-10 and inhibition of T-cell proliferation via CD39 activity. The proportion of circulating CCR6+/CXCR6+ DP8α T cells was significantly reduced (P < .0001) within the total population of CD3+ T cells from patients with IBD compared with patients with infectious colitis or controls. A threshold of <7.875 CCR6+/CXCR6+ DP8α T cells/10,000 CD3+ cells discriminated patients with IBD from those with infectious colitis with 100% specificity and 72.2% sensitivity.
We identified a population of gut-derived TREG cells that are reduced in blood samples from patients with IBD compared with patients with infectious colitis or controls. These cells should be studied further to determine the mechanisms of this reduction and how it might contribute to the pathogenesis of IBD and their prognostic or diagnostic value.
Gain-of-function mutations in the EPAS1/HIF2A gene have been identified in patients with hereditary erythrocytosis that can be associated with the development of paraganglioma, pheochromocytoma and ...somatostatinoma. In the present study, we describe a unique European collection of 41 patients and 28 relatives diagnosed with an erythrocytosis associated with a germline genetic variant in EPAS1. In addition we identified two infants with severe erythrocytosis associated with a mosaic mutation present in less than 2% of the blood, one of whom later developed a paraganglioma. The aim of this study was to determine the causal role of these genetic variants, to establish pathogenicity, and to identify potential candidates eligible for the new hypoxia-inducible factor-2 α (HIF-2α) inhibitor treatment. Pathogenicity was predicted with in silico tools and the impact of 13 HIF-2b variants has been studied by using canonical and real-time reporter luciferase assays. These functional assays consisted of a novel edited vector containing an expanded region of the erythropoietin promoter combined with distal regulatory elements which substantially enhanced the HIF-2α-dependent induction. Altogether, our studies allowed the classification of 11 mutations as pathogenic in 17 patients and 23 relatives. We described four new mutations (D525G, L526F, G527K, A530S) close to the key proline P531, which broadens the spectrum of mutations involved in erythrocytosis. Notably, we identified patients with only erythrocytosis associated with germline mutations A530S and Y532C previously identified at somatic state in tumors, thereby raising the complexity of the genotype/phenotype correlations. Altogether, this study allows accurate clinical follow-up of patients and opens the possibility of benefiting from HIF-2α inhibitor treatment, so far the only targeted treatment in hypoxia-related erythrocytosis disease.
To investigate the abundance and the prevalence of
J115
, a novel butyrate-producing bacterium isolated from the human gut both in the general population and in subjects with metabolic syndrome. To ...study the impact of this bacterium on host metabolism using diet-induced obese and diabetic mice.
We analysed the presence and abundance of the bacterium in 11 984 subjects using four human cohorts (ie, Human Microbiome Project, American Gut Project, Flemish Gut Flora Project and Microbes4U). Then, we tested the effects of daily oral gavages with live
J115
on metabolism and several hallmarks of obesity, diabetes, inflammation and lipid metabolism in obese/diabetic mice.
This newly identified bacterium was detected in 62.7%-69.8% of the healthy population. Strikingly, in obese humans with a metabolic syndrome, the abundance of
genus correlates negatively with body mass index, fasting glucose and glycated haemoglobin. In mice, supplementation with live
J115
, but not with the pasteurised bacteria, partially counteracted diet-induced obesity development, fat mass gain, insulin resistance and white adipose tissue hypertrophy and inflammation. In addition, live
J115
administration protected the mice from brown adipose tissue inflammation in association with increased mitochondria number and non-shivering thermogenesis. These effects occurred with minor impact on the mouse intestinal microbiota composition.
These results suggest that
J115
directly and beneficially influences host metabolism and is a strong candidate for the development of next-generation beneficial bacteria targeting obesity and associated metabolic diseases.
To reduce the cost of genomic selection, a low-density (LD) single nucleotide polymorphism (SNP) chip can be used in combination with imputation for genotyping selection candidates instead of using a ...high-density (HD) SNP chip. Next-generation sequencing (NGS) techniques have been increasingly used in livestock species but remain expensive for routine use for genomic selection. An alternative and cost-efficient solution is to use restriction site-associated DNA sequencing (RADseq) techniques to sequence only a fraction of the genome using restriction enzymes. From this perspective, use of RADseq techniques followed by an imputation step on HD chip as alternatives to LD chips for genomic selection was studied in a pure layer line.
Genome reduction and sequencing fragments were identified on reference genome using four restriction enzymes (EcoRI, TaqI, AvaII and PstI) and a double-digest RADseq (ddRADseq) method (TaqI-PstI). The SNPs contained in these fragments were detected from the 20X sequence data of the individuals in our population. Imputation accuracy on HD chip with these genotypes was assessed as the mean correlation between true and imputed genotypes. Several production traits were evaluated using single-step GBLUP methodology. The impact of imputation errors on the ranking of the selection candidates was assessed by comparing a genomic evaluation based on ancestry using true HD or imputed HD genotyping. The relative accuracy of genomic estimated breeding values (GEBVs) was investigated by considering the GEBVs estimated on offspring as a reference. With AvaII or PstI and ddRADseq with TaqI and PstI, more than 10 K SNPs were detected in common with the HD SNP chip, resulting in an imputation accuracy greater than 0.97. The impact of imputation errors on genomic evaluation of the breeders was reduced, with a Spearman correlation greater than 0.99. Finally, the relative accuracy of GEBVs was equivalent.
RADseq approaches can be interesting alternatives to low-density SNP chips for genomic selection. With more than 10 K SNPs in common with the SNPs of the HD SNP chip, good imputation and genomic evaluation results can be obtained. However, with real data, heterogeneity between individuals with missing data must be considered.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
With the availability of the 600K Affymetrix Axiom high-density (HD) single nucleotide polymorphism (SNP) chip, genomic selection has been implemented in broiler and layer chicken. However, the cost ...of this SNP chip is too high to genotype all selection candidates. A solution is to develop a low-density SNP chip, at a lower price, and to impute all missing markers. But to routinely implement this solution, the impact of imputation on genomic evaluation accuracy must be studied. It is also interesting to study the consequences of the use of low-density SNP chips in genomic evaluation accuracy. In this perspective, the interest of using imputation in genomic selection was studied in a pure layer line. Two low-density SNP chip designs were compared: an equidistant methodology and a methodology based on linkage disequilibrium. Egg weight, egg shell color, egg shell strength, and albumen height were evaluated with single-step genomic best linear unbiased prediction methodology. The impact of imputation errors or the absence of imputation on the ranking of the male selection candidates was assessed with a genomic evaluation based on ancestry. Thus, genomic estimated breeding values (GEBV) obtained with imputed HD genotypes or low-density genotypes were compared with GEBV obtained with the HD SNP chip. The relative accuracy of GEBV was also investigated by considering as reference GEBV estimated on the offspring. A limited reordering of the breeders, selected on a multitrait index, was observed. Spearman correlations between GEBV on HD genotypes and GEBV on low-density genotypes (with or without imputation) were always higher than 0.94 with more than 3K SNP. For the genetically closer, top 150 individuals for a specific trait, with imputation, the reordering was reduced with correlation higher than 0.94 with more than 3K SNP. Without imputation, the correlations remained lower than 0.85 with less than 3K and 16K SNP for equidistant and linkage disequilibrium methodology, respectively. The differences in GEBV correlations between both methodologies were never significant. The conclusions were the same for all studied traits.
Conceptual models underpin river ecosystem research. However, current models focus on continuously flowing rivers and few explicitly address characteristics such as flow cessation and drying. The ...applicability of existing conceptual models to nonperennial rivers that cease to flow (intermittent rivers and ephemeral streams, IRES) has not been evaluated. We reviewed 18 models, finding that they collectively describe main drivers of biogeochemical and ecological patterns and processes longitudinally (upstream‐downstream), laterally (channel‐riparian‐floodplain), vertically (surface water‐groundwater), and temporally across local and landscape scales. However, perennial rivers are longitudinally continuous while IRES are longitudinally discontinuous. Whereas perennial rivers have bidirectional lateral connections between aquatic and terrestrial ecosystems, in IRES, this connection is unidirectional for much of the time, from terrestrial‐to‐aquatic only. Vertical connectivity between surface and subsurface water occurs bidirectionally and is temporally consistent in perennial rivers. However, in IRES, this exchange is temporally variable, and can become unidirectional during drying or rewetting phases. Finally, drying adds another dimension of flow variation to be considered across temporal and spatial scales in IRES, much as flooding is considered as a temporally and spatially dynamic process in perennial rivers. Here, we focus on ways in which existing models could be modified to accommodate drying as a fundamental process that can alter these patterns and processes across spatial and temporal dimensions in streams. This perspective is needed to support river science and management in our era of rapid global change, including increasing duration, frequency, and occurrence of drying.
This article is categorized under:
Water and Life > Nature of Freshwater Ecosystems
Water and Life > Stresses and Pressures on Ecosystems
Science of Water > Hydrological Processes
Alternating flowing and non‐flowing states of the Calavon River, France. Photo credits: Bertrand Launay.
Limited macrolide and fluoroquinolone resistance data are available in France for
. We performed a multicentre cross-sectional study to investigate the prevalence of macrolide and fluoroquinolone ...resistance-associated mutations in
-positive patients in metropolitan France between 2018 and 2020 and in overseas France in 2018 and 2019.
Each year, a 1-month prospective collection of
-positive specimens was proposed to metropolitan French microbiology diagnostic laboratories, and a similar 3-month collection was proposed to overseas French laboratories. Resistance-associated mutations were detected using commercial kits and sequencing.
A total of 1630
.
-positive specimens were analysed. In metropolitan France, the prevalence of macrolide resistance-associated mutations ranged between 34.7% (95% CI 29.4% to 40.4%) and 42.9% (95% CI 37.1% to 49.0%) between 2018 and 2020 and was significantly higher in men (95% CI 52.4% to 60.2%) than in women (95% CI 15.9% to 22.2%) (p<0.001). These prevalences were significantly higher than those of 6.1% (95% CI 3.7% to 10.3%) and 14.7% (95% CI 10.9% to 19.6%) observed in overseas France in 2018 and 2019 (p<0.001), where no difference between genders was noted. The prevalence of fluoroquinolone resistance-associated mutations was also significantly higher in metropolitan France (14.9% (95% CI 11.2% to 19.5%) to 16.1% (95% CI 12.1% to 21.2%)) than in overseas France (1.3% (95% CI 0.4% to 3.7%) and 2.6% (95% CI 1.3% to 5.3%) in 2018 and 2019, respectively) (p<0.001), with no difference between men and women regardless of the location.
This study reports the high prevalence of macrolide and fluoroquinolone resistance-associated mutations in
in metropolitan France and highlights the contrast with low prevalence in overseas France. In metropolitan France, macrolide resistance-associated mutation prevalence was three times higher in men than in women, which was likely to be driven by the proportion of men who have sex with men. This suggests that gender and sexual practice should also be taken into account for the management of
infections.
Alterations in glycosylation cause the emergence of tumor-associated carbohydrate antigens (TACAs) during tumorigenesis. Truncation of O-glycans reveals the Thomsen nouveau (Tn) antigen, an ...N-acetylgalactosamine (GalNAc) frequently attached to serine or threonine amino acids, that is accessible on the surface of cancer cells but not on healthy cells. Interestingly, GalNac can be recognized by macrophage galactose lectin (MGL), a type C lectin receptor expressed in immune cells. In this study, recombinant MGL fragments were tested in vitro for their cancer cell-targeting efficiency by flow cytometry and confocal microscopy and in vivo after administration of fluorescent MGL to tumor-bearing mice. Our results demonstrate the ability of MGL to target Tn-positive human tumors without inducing toxicity. This outcome makes MGL, a fragment of a normal human protein, the first vector candidate for in vivo diagnosis and imaging of human tumors and, possibly, for therapeutic applications.
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