The genetic architecture of membranous nephropathy and its potential to improve non-invasive diagnosis

Membranous Nephropathy (MN) is a rare autoimmune cause of kidney failure. Here we report a genome-wide association study (GWAS) for primary MN in 3,782 cases and 9,038 controls of East Asian and European ancestries. We discover two previously unreported loci, NFKB1 (rs230540, OR = 1.25, P = 3.4 × 10-12) and IRF4 (rs9405192, OR = 1.29, P = 1.4 × 10-14), fine-map the PLA2R1 locus (rs17831251, OR = 2.25, P = 4.7 × 10-103) and report ancestry-specific effects of three classical HLA alleles: DRB1*1501 in East Asians (OR = 3.81, P = 2.0 × 10-49), DQA1*0501 in Europeans (OR = 2.88, P = 5.7 × 10-93), and DRB1*0301 in both ethnicities (OR = 3.50, P = 9.2 × 10-23 and OR = 3.39, P = 5.2 × 10-82, respectively). GWAS loci explain 32% of disease risk in East Asians and 25% in Europeans, and correctly re-classify 20-37% of the cases in validation cohorts that are antibody-negative by the serum anti-PLA2R ELISA diagnostic test. Our findings highlight an unusual genetic architecture of MN, with four loci and their interactions accounting for nearly one-third of the disease risk

The kidney as a target organ in pharmaceutical research

Kidney diseases are a major source of morbidity and mortality in humans. In developed countries, mortality owing to chronic kidney disease (CKD) terminating in end-stage renal failure is comparable with that associated with cancer. A full understanding of the mechanisms implicated in the progression of CKD is needed to achieve its prevention and to delay the need for support strategies based on dialysis and transplantation. Renal fibrosis is the unifying feature of progressive renal alterations. In this review, we discuss the current status of possible mechanisms, tools and targets in CKD. Pathophysiological compound identification, biomarker discovery and accurate selection of clinical validation criteria appear to be three key elements needed to develop a successful innovative pharmaceutical approach to treating kidney diseases

Renal fibrosis and proteomics: current knowledge and still key open questions for proteomic investigation

Renal tubulo-interstitial fibrosis is a non-specific process, representing the final common pathway for all kidney diseases, irrespective of their initial cause, histological injury, or etiology, leading to gradual expansion of the fibrotic mass which destroys the normal structure of the tissue and results in organ dysfunction and, ultimately, in end-stage organ failure. Proteomic studies of the fibrotic pathophysiological mechanisms have been performed in cell cultures, animal models and human tissues, addressing some of the key issues. This article will review proteomic contribution to the raising current knowledge on renal fibrosis biology and also mention seminal open questions to which proteomic techniques and proteomists could fruitfully contribute

The human urinary exosome as a potential metabolic effector cargo

Exosomes are nanovesicles, derived from the endocytic pathway, released by most cell types and found in many body fluids, including urine. A variety of exosomal functions have been reported, including transfer of RNA, cell communication, control of apoptosis and protein lifespan. Exosomes from mesenchymal stem cells can rescue bioenergetics of injured cells. Here the urinary exosome proteome, non-urinary exosome proteome and urinome are compared. A consistent number of identified proteins cluster to metabolic functions. Cytoscape software analysis based on biological processes gene ontology database shows that metabolic pathways such as aerobic glycolysis and oxidative phosphorylation have a high probability (p 64 0.05) of being expressed and therefore functional. A metabolic function appears to be associated with human urinary exosomes, whose relevance experimental studies can assess

Proteome of Bovine Mitochondria and Rod Outer Segment Disks: Commonalities and Differences

The retinal rod outer segment (OS) is a stack of disks surrounded by the plasma membrane, housing proteins related to phototransduction, as well as mitochondrial proteins involved in oxidative phosphorylation (OxPhos). This prompted us to compare the proteome of bovine OS disks and mitochondria to assess the significant top gene signatures of each sample. The two proteomes, obtained by LTQ-Orbitrap Velos mass spectrometry, were compared by statistical analyses. In total, 4139 proteins were identified, 2045 of which overlapping in the two sets. Nonhierarchical Spearman's correlogram revealed that the groups were clearly discriminated. Partial least square discriminant plus support vector machine analysis identified the major discriminative proteins, implied in phototransduction and lipid metabolism, respectively. Gene Ontology analysis identified top gene signatures of the disk proteome, enriched in vesiculation, glycolysis, and OxPhos proteins. The tricarboxylic acid cycle and the electron transport proteins were similarly enriched in the two samples, but the latter was up regulated in disks. Data suggest that the mitochondrial OxPhos proteins may represent a true OS proteome component, outside the mitochondrion. This knowledge may help the scientific community in the further studies of retinal physiology and pathology

Endocellular polyamine availability modulates epithelial-to-mesenchymal transition and unfolded protein response in MDCK cells

Epithelial-to-mesenchymal transition (EMT) is involved in embryonic development as well as in several pathological conditions. Literature indicates that polyamine availability may affect transcription of c-myc, matrix metalloproteinase (MMP)1, MMP2, TGFbeta(1), and collagen type I mRNA. The aim of this study was to elucidate polyamines role in EMT in vitro. Madin-Darby canine kidney (MDCK) cells were subjected to experimental manipulation of intracellular levels of polyamines. Acquisition of mesenchymal phenotype was evaluated by means of immunofluorescence, western blots, and zymograms. MDCK cells were then subjected to 2D gel proteomic study and incorporation of a biotinilated polyamine (BPA). Polyamine endocellular availability modulated EMT process. Polyamine-depleted cells treated with TGFbeta(1) showed enhanced EMT with a marked decrease of E-cadherin expression at plasma membrane level and an increased expression of mesenchymal markers such as fibronectin and alpha-smooth muscle actin. Polyamine-depleted cells showed a twofold increased expression of the rough endoplasmic reticulum (ER)-stress proteins GRP78, GRP94, and HSP90 alpha/beta in 2D gels. The latter data were confirmed by western blot analysis. Administration of BPA showed that polyamines are covalently linked, within the cell, to ER-stress proteins. Intracellular polyamine availability affects EMT in MDCK cells possibly through the modulation of ER-stress protein homeostasis

Exosomes from human mesenchymal stem cells conduct aerobic metabolism in term and preterm newborn infants

Exosomes are secreted nanovesicles that are able to transfer RNA and proteins to target cells. The emerging role ofmesenchymal stemcell (MSC) exosomes as promoters of aerobic ATP synthesis restoration in damaged cells, prompted us to assess whether they contain an extramitochondrial aerobic respiration capacity. Exosomes were isolated from culture medium of human MSCs from umbilical cord of \ue2\u80 37-wk-old newborns or between 28-to 30-wk-old newborns (i.e., term or preterm infants). Characterization of samples was conducted by cytofluorometry. Oxidative phosphorylation capacity was assessed by Western blot analysis, oximetry, and luminometric and fluorometric analyses.MSC exosomes express functional respiratory complexes I, IV, and V, consuming oxygen. ATP synthesis was only detectable in exosomes from term newborns, suggestive of a specific mechanism that is not completed at an early gestational age. Activities are outward facing and comparable to those detected in mitochondria isolated from term MSCs. MSC exosomes display an unsuspected aerobic respiratory ability independent of whole mitochondria. This may be relevant for their ability to rescue cell bioenergetics. The differential oxidativemetabolismof pretermvs. term exosomes sheds new light on the preterm newborn's clinical vulnerability. A reduced ability to repair damaged tissue and an increased capability to cope with anoxic environment for preterm infants can be envisaged