Mutations in sphingosine-1-phosphate lyase cause nephrosis with ichthyosis and adrenal insufficiency

Steroid-resistant nephrotic syndrome (SRNS) causes 15% of chronic kidney disease cases. A mutation in 1 of over 40 monogenic genes can be detected in approximately 30% of individuals with SRNS whose symptoms manifest before 25 years of age. However, in many patients, the genetic etiology remains unknown. Here, we have performed whole exome sequencing to identify recessive causes of SRNS. In 7 families with SRNS and facultative ichthyosis, adrenal insufficiency, immunodeficiency, and neurological defects, we identified 9 different recessive mutations in SGPL1, which encodes sphingosine-1-phosphate (S1P) lyase. All mutations resulted in reduced or absent SGPL1 protein and/or enzyme activity. Overexpression of cDNA representing SGPL1 mutations resulted in subcellular mislocalization of SGPL1. Furthermore, expression of WT human SGPL1 rescued growth of SGPL1-deficient dpl1. yeast strains, whereas expression of disease-associated variants did not. Immunofluorescence revealed SGPL1 expression in mouse podocytes and mesangial cells. Knockdown of Sgpl1 in rat mesangial cells inhibited cell migration, which was partially rescued by VPC23109, an S1P receptor antagonist. In Drosophila, Sply mutants, which lack SGPL1, displayed a phenotype reminiscent of nephrotic syndrome in nephrocytes. WT Sply, but not the disease-associated variants, rescued this phenotype. Together, these results indicate that SGPL1 mutations cause a syndromic form of SRNS

Early acute microvascular kidney transplant rejection in the absence of anti-HLA antibodies is associated with preformed IgG antibodies against diverse glomerular endothelial cell antigens

International audienceBACKGROUND: Although anti-HLA antibodies (Abs) cause most antibody-mediated rejections of renal allografts, non-anti-HLA Abs have also been postulated to contribute. A better understanding of such Abs in rejection is needed.METHODS: We conducted a nationwide study to identify kidney transplant recipients without anti-HLA donor-specific Abs who experienced acute graft dysfunction within 3 months after transplantation and showed evidence of microvascular injury, called acute microvascular rejection (AMVR). We developed a crossmatch assay to assess serum reactivity to human microvascular endothelial cells, and used a combination of transcriptomic and proteomic approaches to identify non-HLA Abs.RESULTS: We identified a highly selected cohort of 38 patients with early acute AMVR. Biopsy specimens revealed intense microvascular inflammation and the presence of vasculitis (in 60.5%), interstitial hemorrhages (31.6%), or thrombotic microangiopathy (15.8%). Serum samples collected at the time of transplant showed that previously proposed anti-endothelial cell Abs-angiotensin type 1 receptor (AT1R), endothelin-1 type A and natural polyreactive Abs-did not increase significantly among patients with AMVR compared with a control group of stable kidney transplant recipients. However, 26% of the tested AMVR samples were positive for AT1R Abs when a threshold of 10 IU/ml was used. The crossmatch assay identified a common IgG response that was specifically directed against constitutively expressed antigens of microvascular glomerular cells in patients with AMVR. Transcriptomic and proteomic analyses identified new targets of non-HLA Abs, with little redundancy among individuals.CONCLUSIONS: Our findings indicate that preformed IgG Abs targeting non-HLA antigens expressed on glomerular endothelial cells are associated with early AMVR, and that cell-based assays are needed to improve risk assessments before transplant

Contribution of vibrational spectroscopy in Nephrology

Contexte : L'histologie rénale est une pierre angulaire de la prise en charge néphrologique mais plusieurs facteurs en limitent les capacités nécessitant le développement de nouvelles techniques. La spectroscopie vibrationnelle (SV), Raman (SR) et infrarouge (FTIR), apporte des informations moléculaires et structurelles de manière reproductible sans préparation préalable des échantillons tissulaires la rendant apte à lever ces limitations. Objectif : L'objectif de ce travail est de démontrer l'intérêt de la SV et son potentiel à apporter des informations à partir des biopsies rénales, actuellement indisponibles via les techniques habituelles. Design : Nous avons recherché dans le rein : 1) Des molécules exogènes : Hydroxyethyl amidon (HEA) 2) Des molécules endogènes : les produits de glycation avancée (AGEs) 3) La quantification de structures pathologiques: fibrose et inflammation. Résultats : 1) L'HEA a été détectée par SR dans des biopsies rénales de patients exposés à cette molécule exogène affirmant son accumulation rénale. La quantification de l'HEA par SR sur des biopsies de greffons rénaux a permis d'associer son accumulation à une bonne qualité du greffon estimée par un score de risque du donneur (KDRI) et la fonction rénale à 3 mois de la greffe. 2) 4 AGEs ont été cartographiés et quantifiés dans des glomérules diabétiques et normaux par SR. Ils étaient augmentés dans les glomérules diabétiques vs normaux. Une faible proportion des AGEs a été retrouvée colocalisée au collagène dans les glomérules diabétiques et non dans les glomérules normaux. 3) La fibrose interstitielle et l'inflammation ont été automatiquement quantifiée par FTIR sur 166 biopsies de greffons rénaux de manière reproductible et robuste. La pertinence clinique de cette technique a été prouvée par une bonne corrélation avec la fonction rénale. Conclusion : La SV possède un fort potentiel en néphrologie avec de multiples applications en recherche comme en pratique clinique.Background: Renal biopsy is a main feature of diagnosis and prognosis in nephrology but it still have some limitation which need further techniques to be more reliable. Vibrational spectroscopy (VS) including Raman spectroscopy (RS) and Fourier-transformed infrared spectroscopy (FTIR) bring out some molecular and structural data from tissue analysis. Objective: We aimed to prove VS is able to provide histologic data actually unattainable by classical techniques. Design: We searched in renal biopsies: 1) Exogenous molecules: Hydroxyethyl starch (HES) 2) Endogenous molecules: Advanced glycation end-product (AGEs) 3) Reproducible quantification of interstitial fibrosis and inflammation in renal grafts. Results: 1) We reported an accumulation of HES by RS in renal biopsies from patients exposed to this molecule. Moreover, accumulation of HES in renal graft biopsies exposed to HES was dependent on good quality of graft defined by kidney donor risk index and renal function at 3 months. 2) 4 AGEs were mapped and quantified by RS in diabetic and normal glomeruli. Levels of each AGE were higher diabetic glomeruli vs controls. In diabetic glomeruli, some AGEs were collocated with collagen that was not found in normal glomeruli. 3) Interstitial fibrosis (IF) and inflammation were quantified in 166 renal graft biopsies by an automated FTIR technique. We assessed the robustness of this technique for discrimination of fibrosis and inflammation. We proved the clinical relevance of this technique by showing a good correlation of IF with renal graft function. Conclusion: Vibrational spectroscopy is a promising technique for nephrology both in basic research and in clinical practice

Détection et localisation des produits de glycation avancée (AGEs) tissulaires par micro-imagerie spectrale RAMAN dans les reins de patients diabétique

REIMS-BU Santé (514542104) / SudocSudocFranceF

Influence du VEGF sur la protéinurie en transplantation rénale

REIMS-BU Santé (514542104) / SudocSudocFranceF

New insights into spectral histopathology: infrared-based scoring of tumour aggressiveness of squamous cell lung carcinomas

International audienceSpectral histopathology, based on infrared interrogation of tissue sections, proved a promising tool for helping pathologists in characterizing histological structures in a quantitative and automatic manner. In cancer diagnosis, the use of chemometric methods permits establishing numerical models able to detect cancer cells and to characterize their tissular environment. In this study, we focused on exploiting multivariate infrared data to score the tumour aggressiveness in preneoplastic lesions and squamous cell lung carcinomas. These lesions present a wide range of aggressive phenotypes; it is also possible to encounter cases with various degrees of aggressiveness within the same lesion. Implementing an infrared-based approach for a more precise histological determination of the tumour aggressiveness should arouse interest among pathologists with direct benefits for patient care. In this study, the methodology was developed from a set of samples including all degrees of tumour aggressiveness and by constructing a chain of data processing steps for an automated analysis of tissues currently manipulated in routine histopathology

Renal Graft Fibrosis and Inflammation Quantification by an Automated Fourier–Transform Infrared Imaging Technique

International audienc

Raman-based detection of hydroxyethyl starch in kidney allograft biopsies as a potential marker of allograft quality in kidney transplant recipients

International audienc

Protein carbamylation is a hallmark of aging

International audienceAging is a progressive process determined by genetic and acquired factors. Among the latter are the chemical reactions referred to as nonenzymatic posttranslational modifications (NEPTMs), such as glycoxidation, which are responsible for protein molecular aging. Carbamylation is a more recently described NEPTM that is caused by the nonenzymatic binding of isocyanate derived from urea dissociation or myeloperoxidase-mediated catabolism of thiocyanate to free amino groups of proteins. This modification is considered an adverse reaction, because it induces alterations of protein and cell properties. It has been shown that carbamylated proteins increase in plasma and tissues during chronic kidney disease and are associated with deleterious clinical outcomes, but nothing is known to date about tissue protein carbamylation during aging. To address this issue, we evaluated homocitrulline rate, the most characteristic carbamylation-derived product (CDP), over time in skin of mammalian species with different life expectancies. Our results show that carbamylation occurs throughout the whole lifespan and leads to tissue accumulation of carbamylated proteins. Because of their remarkably long half-life, matrix proteins, like type I collagen and elastin, are preferential targets. Interestingly, the accumulation rate of CDPs is inversely correlated with longevity, suggesting the occurrence of still unidentified protective mechanisms. In addition, homocitrulline accumulates more intensely than carboxymethyl-lysine, one of the major advanced glycation end products, suggesting the prominent role of carbamylation over glycoxidation reactions in age-related tissue alterations. Thus, protein carbamylation may be considered a hallmark of aging in mammalian species that may significantly contribute in the structural and functional tissue damages encountered during aging