Identification of inflammatory biomarkers in IgA nephropathy using the NanoString technology: a validation study in Caucasians.

OBJECTIVE AND DESIGN: Immunoglobulin A nephropathy (IgAN) is a kidney disease characterized by the accumulation of IgA deposits in the glomeruli of the kidney, leading to inflammation and damage to the kidney. The inflammatory markers involved in IgAN remain to be defined. Gene expression analysis platforms, such as the NanoString nCounter system, are promising screening and diagnostic tools, especially in oncology. Still, their role as a diagnostic and prognostic tool in IgAN remains scarce. In this study, we aimed to validate the use of NanoString technology to identify potential inflammatory biomarkers involved in the progression of IgAN. SUBJECTS: A total of 30 patients with biopsy-proven IgAN and 7 cases of antineutrophil cytoplasmic antibody (ANCA)-associated pauci-immune glomerulonephritis were included for gene expression measurement. For the immunofluorescence validation experiments, a total of 6 IgAN patients and 3 controls were included. METHODS: Total RNA was extracted from formalin-fixed paraffin-embedded kidney biopsy specimens, and a customized 48-plex human gene CodeSet was used to study 29 genes implicated in different biological pathways. Comparisons in gene expression were made between IgAN and ANCA-associated pauci-immune glomerulonephritis patients to delineate an expression profile specific to IgAN. Gene expression was compared between patients with low and moderate risk of progression. Genes for which RNA expression was associated with disease progression were analyzed for protein expression by immunofluorescence and compared with controls. RESULTS: IgAN patients had a distinct gene expression profile with decreased expression in genes IL-6, INFG, and C1QB compared to ANCA patients. C3 and TNFRSF1B were identified as potential biomarkers for IgAN progression in patients early in their disease course. Protein expression for those 2 candidate genes was upregulated in IgAN patients compared to controls. Expression of genes implicated in fibrosis (PTEN, CASPASE 3, TGM2, TGFB1, IL2, and TNFRSF1B) was more pronounced in IgAN patients with severe fibrosis compared to those with none. CONCLUSIONS: Our findings validate our NanoString mRNA profiling by examining protein expression levels of two candidate genes, C3 and TNFRSF1B, in IgAN patients and controls. We also identified several upregulated mRNA transcripts implicated in the development of fibrosis that may be considered fibrotic markers within IgAN patients.

Tungsten toxicity on kidney tubular epithelial cells induces renal inflammation and M1-macrophage polarization.

Tungsten is widely used in medical, industrial, and military applications. The environmental exposure to tungsten has increased over the past several years, and few studies have addressed its potential toxicity. In this study, we evaluated the effects of chronic oral tungsten exposure (100 ppm) on renal inflammation in male mice. We found that 30- or 90-day tungsten exposure led to the accumulation of LAMP1-positive lysosomes in renal tubular epithelial cells. In addition, the kidneys of mice exposed to tungsten showed interstitial infiltration of leukocytes, myeloid cells, and macrophages together with increased levels of proinflammatory cytokines and p50/p65-NFkB subunits. In proximal tubule epithelial cells (HK-2) in vitro, tungsten induced a similar inflammatory status characterized by increased mRNA levels of CSF1, IL34, CXCL2, and CXCL10 and NFkB activation. Moreover, tungsten exposure reduced HK-2 cell viability and enhanced reactive oxygen species generation. Conditioned media from HK-2 cells treated with tungsten induced an M1-proinflammatory polarization of RAW macrophages as evidenced by increased levels of iNOS and interleukin-6 and decreased levels of the M2-antiinflammatory marker CD206. These effects were not observed when RAW cells were exposed to conditioned media from HK-2 cells treated with tungsten and supplemented with the antioxidant N-acetylcysteine (NAC). Similarly, direct tungsten exposure induced M1-proinflammatory polarization of RAW cells that was prevented by NAC co-treatment. Altogether, our data suggest that prolonged tungsten exposure leads to oxidative injury in the kidney ultimately leading to chronic renal inflammation characterized by a proinflammatory status in kidney tubular epithelial cells and immune cell infiltration.

Subchronic oral exposure of tungsten induces myofibroblast transformation and various markers of kidney fibrosis.

Tungsten is a naturally occurring transition element used in a broad range of applications. As a result of its extensive use, we are increasingly exposed to tungsten from our environment, including potable water, since tungsten can become bioaccessible in ground sources. The kidneys are particularly susceptible to tungsten exposure as this is the main site for tungsten excretion. In this study, we investigated the prolonged effects of tungsten on the kidneys and how this may impact injury and function. When mice were exposed to tungsten in their drinking water for 1 mo, kidney function had not significantly changed. Following 3-mo exposure, mice were presented with deterioration in kidney function as determined by serum and urine creatinine levels. During 3 mo of tungsten exposure, murine kidneys demonstrated significant increases in the myofibroblast marker α-smooth muscle actin (αSMA) and extracellular matrix products: fibronectin, collagen, and matricellular proteins. In addition, Masson's trichrome and hematoxylin-eosin (H&E) staining revealed an increase in fibrotic tissue and vacuolization of tubular epithelial cells, respectively, from kidneys of tungsten-treated mice, indicative of renal injury. In vitro treatment of kidney fibroblasts with tungsten led to increased proliferation and upregulation of transforming growth factor ß1 (TGFß1), which was consistent with the appearance of fibroblast-to-myofibroblast transition (FMT) markers. Our data suggest that continuous exposure to tungsten impairs kidney function that may lead to the development of chronic kidney disease (CKD).

The non-steroidal mineralocorticoid receptor antagonist finerenone is a novel therapeutic option for patients with Type 2 diabetes and chronic kidney disease.

Despite strong preclinical data supporting the use of mineralocorticoid receptor antagonists (MRAs) to provide cardiorenal protection in rodent models of diabetes, the clinical evidence of their utility in treating chronic kidney disease (CKD) has been limited. Two major clinical trials (FIDELIO-DKD and FIGARO-DKD) including more than 13,000 patients with albuminuric CKD and Type 2 diabetes randomized to placebo or finerenone (MRA) have recently provided exciting results showing a significant risk reduction for kidney and cardiovascular outcomes. In this review, we will summarize the major findings of these trials, together with post-hoc and pooled analyses that have allowed evaluation of the efficacy and safety of finerenone across the spectrum of CKD, revealing significant protective effects of finerenone against kidney failure, new-onset atrial fibrillation or flutter, new-onset heart failure, cardiovascular death, and first and total heart-failure hospitalizations. Moreover, we will discuss the current evidence that supports the combined use of MRAs with sodium-glucose co-transporter-2 inhibitors, either by providing an additive cardiorenal benefit or by decreasing the risk of hyperkalemia. Although the mechanisms of protection by finerenone have only been partially explored in patients, rodent studies have shed light on its anti-inflammatory and anti-fibrotic effects in models of kidney disease, which is one of the main drivers for testing the efficacy of finerenone in non-diabetic CKD patients in the ongoing FIND-CKD trial.

Seq2Neo: A Comprehensive Pipeline for Cancer Neoantigen Immunogenicity Prediction.

Neoantigens derived from somatic DNA alterations are ideal cancer-specific targets. In recent years, the combination therapy of PD-1/PD-L1 blockers and neoantigen vaccines has shown clinical efficacy in original PD-1/PD-L1 blocker non-responders. However, not all somatic DNA mutations result in immunogenicity among cancer cells and efficient tools to predict the immunogenicity of neoepitopes are still urgently needed. Here, we present the Seq2Neo pipeline, which provides a one-stop solution for neoepitope feature prediction using raw sequencing data. Neoantigens derived from different types of genome DNA alterations, including point mutations, insertion deletions and gene fusions, are all supported. Importantly, a convolutional neural network (CNN)-based model was trained to predict the immunogenicity of neoepitopes and this model showed an improved performance compared to the currently available tools in immunogenicity prediction using independent datasets. We anticipate that the Seq2Neo pipeline could become a useful tool in the prediction of neoantigen immunogenicity and cancer immunotherapy. Seq2Neo is open-source software under an academic free license (AFL) v3.0 and is freely available at Github.

Emerging Roles of Matricellular Proteins in Systemic Sclerosis.

Systemic sclerosis is a rare chronic heterogenous disease that involves inflammation and vasculopathy, and converges in end-stage development of multisystem tissue fibrosis. The loss of tight spatial distribution and temporal expression of proteins in the extracellular matrix (ECM) leads to progressive organ stiffening, which is a hallmark of fibrotic disease. A group of nonstructural matrix proteins, known as matricellular proteins (MCPs) are implicated in dysregulated processes that drive fibrosis such as ECM remodeling and various cellular behaviors. Accordingly, MCPs have been described in the context of fibrosis in sclerosis (SSc) as predictive disease biomarkers and regulators of ECM synthesis, with promising therapeutic potential. In this present review, an informative summary of major MCPs is presented highlighting their clear correlations to SSc- fibrosis.

Targeting Phospholipase D4 Attenuates Kidney Fibrosis.

Phospholipase D4 (PLD4), a single-pass transmembrane glycoprotein, is among the most highly upregulated genes in murine kidneys subjected to chronic progressive fibrosis, but the function of PLD4 in this process is unknown. Here, we found PLD4 to be overexpressed in the proximal and distal tubular epithelial cells of murine and human kidneys after fibrosis. Genetic silencing of PLD4, either globally or conditionally in proximal tubular epithelial cells, protected mice from the development of fibrosis. Mechanistically, global knockout of PLD4 modulated innate and adaptive immune responses and attenuated the upregulation of the TGF-ß signaling pathway and α1-antitrypsin protein (a serine protease inhibitor) expression and downregulation of neutrophil elastase (NE) expression induced by obstructive injury. In vitro, treatment with NE attenuated TGF-ß-induced accumulation of fibrotic markers. Furthermore, therapeutic targeting of PLD4 using specific siRNA protected mice from folic acid-induced kidney fibrosis and inhibited the increase in TGF-ß signaling, decrease in NE expression, and upregulation of mitogen-activated protein kinase signaling. Immunoprecipitation/mass spectrometry and coimmunoprecipitation experiments confirmed that PLD4 binds three proteins that interact with neurotrophic receptor tyrosine kinase 1, a receptor also known as TrkA that upregulates mitogen-activated protein kinase. PLD4 inhibition also prevented the folic acid-induced upregulation of this receptor in mouse kidneys. These results suggest inhibition of PLD4 as a novel therapeutic strategy to activate protease-mediated degradation of extracellular matrix and reverse fibrosis.

Human epidermal growth factor receptor 4 (Her4) Suppresses p53 Protein via Targeting the MDMX-MDM2 Protein Complex: IMPLICATION OF A NOVEL MDMX SER-314 PHOSPHOSITE.

Deregulated receptor tyrosine kinase (RTK) signaling is frequently associated with tumorigenesis and therapy resistance, but its underlying mechanisms still need to be elucidated. In this study, we have shown that the RTK human epidermal growth factor receptor 4 (Her4, also known as Erbb4) can inhibit the tumor suppressor p53 by regulating MDMX-mouse double minute 2 homolog (MDM2) complex stability. Upon activation by either overexpression of a constitutively active vector or ligand binding (Neuregulin-1), Her4 was able to stabilize the MDMX-MDM2 complex, resulting in suppression of p53 transcriptional activity, as shown by p53-responsive element-driven luciferase assay and mRNA levels of p53 target genes. Using a phospho-proteomics approach, we functionally identified a novel Her4-induced posttranslational modification on MDMX at Ser-314, a putative phosphorylation site for the CDK4/6 kinase. Remarkably, inhibition of Ser-314 phosphorylation either with Ser-to-Ala substitution or with a specific inhibitor of CDK4/6 kinase blocked Her4-induced stabilization of MDMX-MDM2 and rescued p53 activity. Our study offers insights into the mechanisms of deregulated RTK-induced carcinogenesis and provides the basis for the use of inhibitors targeting RTK-mediated signals for p53 restoration.

Prostaglandin E2-Dependent Phosphorylation of RAS Inhibition 1 (RIN1) at Ser 291 and 292 Inhibits Transforming Growth Factor-ß-Induced RAS Activation Pathway in Human Synovial Fibroblasts: Role in Cell Migration.

Prostaglandin E2 (PGE2 )-stimulated G-protein-coupled receptor (GPCR) activation inhibits pro-fibrotic TGFß-dependent stimulation of human fibroblast to myofibroblast transition (FMT), though the precise molecular mechanisms are not fully understood. In the present study, we describe the PGE2 -dependent suppression and reversal of TGFß-induced events such as α-sma expression, stress fiber formation, and Ras/Raf/ERK/MAPK pathway-dependent activation of myofibroblast migration. In order to elucidate post-ligand-receptor signaling pathways, we identified a predominant PKA phosphorylation motif profile in human primary fibroblasts after treatment with exogenous PGE2 (EC50 30 nM, Vmax 100 nM), mimicked by the adenyl cyclase activator forskolin (EC50 5 µM, Vmax 10 µM). We used a global phosphoproteomic approach to identify a 2.5-fold difference in PGE2 -induced phosphorylation of proteins containing the PKA motif. Deducing the signaling pathway of our migration data, we identified Ras inhibitor 1 (RIN1) as a substrate, whereby PGE2 induced its phosphorylation at Ser291 and at Ser292 by a 5.4- and 4.8-fold increase, respectively. In a series of transient and stable over expression studies in HEK293T and HeLa cells using wild-type (wt) and mutant RIN1 (Ser291/292Ala) or Ras constructs and siRNA knock-down experiments, we showed that PGE2 -dependent phosphorylation of RIN1 resulted in the abrogation of TGFß-induced Ras/Raf signaling activation and subsequent downstream blockade of cellular migration, emphasizing the importance of such phosphosites in PGE2 suppression of wound closure. Overexpression experiments in tandem with pull-down assays indicated that specific Ser291/292 phosphorylation of RIN1 favored binding to activated Ras. In principal, understanding PGE2 -GPCR activated signaling pathways mitigating TGFß-induced fibrosis may lead to more evidence-based treatments against the disease. J. Cell. Physiol. 232: 202-215, 2017. © 2016 Wiley Periodicals, Inc.

Myofibroblast repair mechanisms post-inflammatory response: a fibrotic perspective.

INTRODUCTION: Fibrosis is a complex chronic disease characterized by a persistent repair response. Its pathogenesis is poorly understood but it is typically the result of chronic inflammation and maintained with the required activity of transforming growth factor-ß (TGFß) and extracellular matrix (ECM) tension, both of which drive fibroblasts to transition into a myofibroblast phenotype. FINDINGS: As the effector cells of repair, myofibroblasts migrate to the site of injury to deposit excessive amounts of matrix proteins and stimulate high levels of contraction. Myofibroblast activity is a decisive factor in whether a tissue is properly repaired by controlled wound healing or rendered fibrotic by deregulated repair. Extensive studies have documented the various contributing factors to an abrogated repair response. Though these fibrotic factors are known, very little is understood about the opposing antifibrotic molecules that assist in a successful repair, such as prostaglandin E2 (PGE2) and ECM retraction. The following review will discuss the general development of fibrosis through the transformation of myofibroblasts, focusing primarily on the prominent profibrotic pathways of TGFß and ECM tension and antifibrotic pathways of PGE2 and ECM retraction. CONCLUSIONS: The idea is to understand the ways in which the cell, after an injury and inflammatory response, normally controls its repair mechanisms through its homeostatic regulators so as to mimic them therapeutically to control abnormal pathways.

Quantitative phosphoproteomic analysis of signaling downstream of the prostaglandin e2/g-protein coupled receptor in human synovial fibroblasts: potential antifibrotic networks.

The Prostaglandin E2 (PGE2) signaling mechanism within fibroblasts is of growing interest as it has been shown to prevent numerous fibrotic features of fibroblast activation with limited evidence of downstream pathways. To understand the mechanisms of fibroblasts producing tremendous amounts of PGE2 with autocrine effects, we apply a strategy of combining a wide-screening of PGE2-induced kinases with quantitative phosphoproteomics. Our large-scale proteomic approach identified a PKA signal transmitted through phosphorylation of its substrates harboring the R(R/X)X(S*/T*) motif. We documented 115 substrates, of which 72 had 89 sites with a 2.5-fold phosphorylation difference in PGE2-treated cells than in untreated cells, where approximately half of such sites were defined as being novel. They were compiled by networking software to focus on highlighted activities and to associate them with a functional readout of fibroblasts. The substrates were associated with a variety of cellular functions including cytoskeletal structures (migration/motility), regulators of G-protein coupled receptor function, protein kinases, and transcriptional/translational regulators. For the first time, we extended the PGE2 pathway into an elaborate network of interconnecting phosphoproteins, providing vital information to a once restricted signalosome. These data provide new insights into eicosanoid-initiated cell signaling with regards to the regulation of fibroblast activation and the identification of new targets for evidenced-based pharmacotherapy against fibrosis.

Prostaglandin E(2)-dependent blockade of actomyosin and stress fibre formation is mediated through S1379 phosphorylation of ROCK2.

Prostaglandin E2 is a pleiotropic bioactive lipid that controls cytoskeletal alterations, although the precise G-protein coupled EP receptor signalling mechanisms remain ill defined. We adopted a phosphoproteomic approach to characterize post-receptor downstream signalling substrates using antibodies that selectively recognize and immunoprecipitate phosphorylated substrates of a number of kinases. Using human synovial fibroblasts in monolayer cell culture, PGE2 induced rapid and sustained changes in cellular morphology and reduction in cytoplasmic volume that were associated with disassembly of the phalloidin-stained stress fibres as judged by light and confocal microscopy. Furthermore, PGE2 induced a rapid dephosphorylation of myosin light chain II (MLC) at S19 under basal or cytokine-induced conditions that was linked to an activation of myosin light chain phosphatase. The use of specific synthetic EP agonists suggested that the response was mediated by EP2 receptors, as other EP agonists did not manifest the same effect on MLC phosphorylation. In addition, PGE2 induced sustained Y118 dephosphorylation of phospho-paxillin and loss of focal adhesions as observed by confocal microscopy and Western analysis. Phosphoproteomic analysis of PGE2 /GPCR/PKA phosphosubstrates identified a unique, non-redundant, phosphorylated (>30-fold) site on rho-associated coiled coil-containing kinase 2 (ROCK2) at S1379. Analysis of ROCK2 mutant behaviour (e.g. S1379A) in overexpression studies revealed that PGE2 -dependent phosphorylation of ROCK2 resulted in the inhibition of the kinase, since induced MLC phosphorylation was no longer blocked by PGE2 nor could PGE2 induce disassembly of stress fibres. Thus, PGE2 -dependent blockade of actomyosin fibre formation, characteristic of myofibroblasts, may be mediated through specific ROCK2 S1379 phosphorylation.

Holistic exploration of CHGA and hsa-miR-137 in colorectal cancer via multi-omic data Integration.

Colorectal cancer (CRC) ranks among the most widespread malignancies globally, with early detection significantly influencing prognosis. Employing a systems biology approach, we aimed to unravel the intricate mRNA-miRNA network linked to CRC pathogenesis, potentially yielding diagnostic biomarkers. Through an integrative analysis of microarray, Bulk RNA-seq, and single-cell RNA-seq data, we explored CRC-related transcriptomes comprehensively. Differential gene expression analysis uncovered crucial genes, while Weighted Gene Co-expression Network Analysis (WGCNA) identified key modules closely linked to CRC. Remarkably, CRC manifested its strongest correlation with the turquoise module, signifying its pivotal role. From the cohort of genes showing high Gene Significance (GS) and Module Membership (MM), and Differential Expression Genes (DEGs), we highlighted the downregulated Chromogranin A (CHGA) as a notable hub gene in CRC. This finding was corroborated by the Human Protein Atlas database, which illustrated decreased CHGA expression in CRC tissues. Additionally, CHGA displayed elevated expression in primary versus metastatic cell lines, as evidenced by the CCLE database. Subsequent RT-qPCR validation substantiated the marked downregulation of CHGA in CRC tissues, reinforcing the significance of our differential expression analysis. Analyzing the Space-Time Gut Cell Atlas dataset underscored specific CHGA expression in epithelial cell subclusters, a trend persisting across developmental stages. Furthermore, our scrutiny of colon and small intestine Enteroendocrine cells uncovered distinct CHGA expression patterns, accentuating its role in CRC pathogenesis. Utilizing the WGCNA algorithm and TargetScan database, we validated the downregulation of hsa-miR-137 in CRC, and integrated assessment highlighted its interplay with CHGA. Our findings advocate hsa-miR-137 and CHGA as promising CRC biomarkers, offering valuable insights into diagnosis and prognosis. Despite proteomic analysis yielding no direct correlation, our multifaceted approach contributes comprehensive understanding of CRC's intricate regulatory mechanisms. In conclusion, this study advances hsa-miR-137 and CHGA as promising CRC biomarkers through an integrated analysis of diverse datasets and network interactions.

Preventing bad behavior in academia.

We gave young scientists this prompt: Describe one change to scientific policy or culture that would substantially decrease incidents of scientific misconduct or other unethical behavior.

SMOC2 promotes an epithelial-mesenchymal transition and a pro-metastatic phenotype in epithelial cells of renal cell carcinoma origin.

Renal Cell Carcinoma (RCC) is the most common form of all renal cancer cases, and well-known for its highly aggressive metastatic behavior. SMOC2 is a recently described non-structural component of the extracellular matrix (ECM) that is highly expressed during tissue remodeling processes with emerging roles in cancers, yet its role in RCC remains elusive. Using gene expression profiles from patient samples, we identified SMOC2 as being significantly expressed in RCC tissue compared to normal renal tissue, which correlated with shorter RCC patient survival. Specifically, de novo protein synthesis of SMOC2 was shown to be much higher in the tubular epithelial cells of patients with biopsy-proven RCC. More importantly, we provide evidence of SMOC2 triggering kidney epithelial cells into an epithelial-to-mesenchymal transition (EMT), a phenotype known to promote metastasis. We found that SMOC2 induced mesenchymal-like morphology and activities in both RCC and non-RCC kidney epithelial cell lines. Mechanistically, treatment of RCC cell lines ACHN and 786-O with SMOC2 (recombinant and enforced expression) caused a significant increase in EMT-markers, -matrix production, -proliferation, and -migration, which were inhibited by targeting SMOC2 by siRNA. We further characterized SMOC2 activation of EMT to occur through the integrin ß3, FAK and paxillin pathway. The proliferation and metastatic potential of SMOC2 overexpressing ACHN and 786-O cell lines were validated in vivo by their significantly higher tumor growth in kidneys and systemic dissemination into other organs when compared to their respective controls. In principle, understanding the impact that SMOC2 has on EMT may lead to more evidence-based treatments and biomarkers for RCC metastasis.

Advancing Discovery Research in Nephrology in Canada: A Conference Report From the 2021 Molecules and Mechanisms Mediating Kidney Health and Disease (M3K) Scientific Meeting and Investigator Summit.

Purpose of conference: New discoveries arising from investigations into fundamental aspects of kidney development and function in health and disease are critical to advancing kidney care. Scientific meetings focused specifically on fundamental biology of the kidney can facilitate interactions, support the development of collaborative groups, and accelerate translation of key findings. The Canadian fundamental kidney researcher community has lacked such a forum. On December 3 to 4, 2021, the first Molecules and Mechanisms Mediating Kidney Health and Disease (M3K) Scientific Meeting and Investigator Summit was held to address this gap with the goal of advancing fundamental kidney research nationally. The meeting was held virtually and was supported by a planning and dissemination grant from the Canadian Institutes of Health Research. Attendees included PhD scientists, nephrology clinician scientists, engineers, industry representatives, graduate students, medical residents, and fellows. Sources of information: This report was prepared from the scientific program, registration numbers, and details obtained from the online platform WHOVA, and summaries written by organizers and participants of the 2021 meeting. Methods: A 21-person team, consisting of the organizing committee members and participants from the meeting, was assembled. Key highlights of the meeting and future directions were identified and the team jointly assembled this report. Key findings: Participation in the meeting was strong, with more than 140 attendees across a range of disciplines. The program featured state-of-the-art presentations on diabetic nephropathy, the immune system, kidney development, and fibrosis, and was heavily focused on trainee presentations. The moderated "Investigator Summit" identified key barriers to research advancement and discussed strategies for overcoming them. These included establishment of a pan-Canadian fundamental kidney research network, development of key resources, cross-pollination with clinical nephrology, better reintegration into the Canadian Society of Nephrology, and further establishment of identity and knowledge translation. Limitations and implications: The 2021 M3K meeting represented a key first step in uniting fundamental kidney researchers in Canada. However, it was universally agreed that regular meetings were necessary to sustain this momentum. The proceedings of this meeting and future actions to sustain the M3K Scientific Meeting and Investigator Summit are presented in this article.

Objectif de la conférence: De nouvelles découvertes découlant des enquêtes sur les aspects fondamentaux du développement et de la fonction des reins en santé ou malades sont essentielles pour faire progresser les soins rénaux. Les réunions scientifiques axées spécifiquement sur la biologie fondamentale du rein peuvent faciliter les interactions, appuyer le développement de groupes de collaboration et accélérer l'application des principaux résultats. La communauté canadienne des chercheurs fondamentaux en néphrologie a manqué d'un tel forum. Les 3 et 4 décembre 2021, le premier Sommet des chercheurs et la réunion scientifique M3K (Molecules and Mechanisms Mediating Kidney Health and Disease) sur les molécules et les médiateurs de la santé et des maladies rénales ont eu lieu pour combler cette lacune; l'objectif était de faire progresser la recherche fondamentale en néphrologie à l'échelle nationale. La réunion s'est tenue virtuellement et était financée par une subvention de planification et de diffusion des Instituts de recherche en santé du Canada. Des doctorants, cliniciens-chercheurs en néphrologie, ingénieurs, représentants de l'industrie, étudiants diplômés, résidents en médecine et en surspécialisation figuraient parmi les participants. Sources: Ce rapport a été préparé à partir du program scientifique, des informations et des numéros d'inscription tirés de la plateforme en ligne WHOVA, et des résumés rédigés par les organisateurs et les participants à la réunion de 2021. Méthodologie: Une équipe de 20 personnes composée de membres du comité organisateur et de participants à la réunion a été formée. Les principaux points saillants de la réunion et les orientations futures ont été déterminés, puis l'équipe a rédigé conjointement le présent rapport. Principaux résultats: La réunion s'est avérée un succès; plus de 140 personnes provenant d'un large éventail de disciplines y ont participé. Le program comprenait des présentations de pointe sur la néphropathie diabétique, le système immunitaire, le développement des reins et la fibrose, et était fortement axé sur des présentations par des stagiaires. Le « Sommet des chercheurs ¼, animé par un modérateur, a permis de déterminer les principaux obstacles à l'avancement de la recherche et de discuter des stratégies pour les surmonter. Ces dernières incluent notamment la création d'un réseau pancanadien de recherche fondamentale en néphrologie, le développement de ressources clés, la pollinisation croisée avec la néphrologie clinique, une « meilleure réintégration dans la Société canadienne de néphrologie ¼ et la poursuite de l'établissement de l'identité et de l'application des connaissances. Limites et implications: La réunion M3K de 2021 a constitué une première étape clé dans l'unification des chercheurs fondamentaux en néphrologie au Canada. On a cependant universellement convenu que des réunions régulières étaient nécessaires pour maintenir cet élan. Le compte rendu de cette réunion ainsi que les actions futures pour soutenir la réunion scientifique M3K et le Sommet des chercheurs sont présentés dans le présent article.

Reversible blockade of thymic output: an inherent part of TLR ligand-mediated immune response.

TLRs constitute a first set of sensors that detect viral nucleic acids including dsRNA which triggers TLR3. We report the early, direct, and detrimental effect of polyinosine-polycytidilic acid treatment on T cell development. Inhibition of thymopoiesis was targeted to several thymocyte subpopulations. First, both a blockade of the double negative (DN)1-DN2 transition and a severe down-regulation of DN3-DN4 thymocyte proliferation were observed. In addition, an important decrease in the absolute numbers of double-positive thymocytes, concomitant with an increase in frequencies of apoptotic cells in this population were shown. This inhibition of thymopoiesis resulted in a reduced thymic output, as evidenced by a drop of the absolute numbers of naive T cells and TCR excision circles levels. The decrease in thymic cellularity and defects in thymic development were severely reduced, but not completely abolished in IFN-alpha/betaR(-/-) mice, showing a direct contribution of type I IFNs, known to be massively up-regulated in viral infections, to the inhibition of T cell development. Strikingly, the TCR repertoire in treated mice was biased toward shorter CDR3 lengths as a result of a decreased expression of TdT and Rag2. However, thymic integrity remained intact since thymopoiesis was restored both quantitatively and qualitatively 14 days after the cessation of polyinosine-polycytidilic acid treatment. These results demonstrate a novel immunomodulatory role for virally encoded TLR ligands and RNA sensors; they further illustrate the diversity of mechanisms that viruses use to interfere with the development of a pathogen-specific immune responses.

The Matrix Revolution: Matricellular Proteins and Restructuring of the Cancer Microenvironment.

The extracellular matrix (ECM) surrounding cells is indispensable for regulating their behavior. The dynamics of ECM signaling are tightly controlled throughout growth and development. During tissue remodeling, matricellular proteins (MCP) are secreted into the ECM. These factors do not serve classical structural roles, but rather regulate matrix proteins and cell-matrix interactions to influence normal cellular functions. In the tumor microenvironment, it is becoming increasingly clear that aberrantly expressed MCPs can support multiple hallmarks of carcinogenesis by interacting with various cellular components that are coupled to an array of downstream signals. Moreover, MCPs also reorganize the biomechanical properties of the ECM to accommodate metastasis and tumor colonization. This realization is stimulating new research on MCPs as reliable and accessible biomarkers in cancer, as well as effective and selective therapeutic targets.

Alk1 haploinsufficiency causes glomerular dysfunction and microalbuminuria in diabetic mice.

Endothelial dysfunction has been shown to play an important role in the pathogenesis of glomerular damage during diabetic kidney disease (DKD). As such, a better understanding of the molecular mechanisms involved in glomerular endothelial dysfunctions could provide novel therapeutic strategies for the prevention of DKD. We have previously shown that Alk1/BMP9 signaling plays an important function to maintain vascular integrity in diabetic animals. As such, we evaluated the effects of Alk1 suppression on glomerular endothelial function in diabetic mice. In the present study, we used mice with conditional heterozygote deletion of Alk1 in the endothelium (Alk1ΔEC) to evaluate the role of Alk1 on kidney function during STZ-induced diabetes. DKD was investigated in diabetic control and Alk1ΔEC mice euthanized eight weeks after the onset of diabetes. We showed that Alk1 expression is reduced in the glomeruli of human DKD patients. While renal function was not altered in Alk1ΔEC non-diabetic mice, we showed that Alk1 haploinsufficiency in the glomerular endothelium leads to microalbuminuria, thickening of the glomerular basement membrane, glomerular apoptosis and podocyte loss in diabetic mice. These data suggest that Alk1 is important for the proper function of glomerular endothelial cells and that decreased Alk1 combined with chronic hyperglycemia can impair renal function.

Found in Translation: Reasons for Optimism in the Pursuit to Prevent Chronic Kidney Disease After Acute Kidney Injury.

PURPOSE OF REVIEW: The current review will discuss on the progress of studying the transition phase between acute kidney injury (AKI) and chronic kidney disease (CKD) through improved animal models, common AKI and CKD pathways, and how human studies may inform different translational approaches. SOURCES OF INFORMATION: PubMed and Google Scholar. METHODS: A narrative review was performed using the main terms "acute kidney injury," "chronic kidney disease," "end-stage renal disease," "animal models," "review," "decision-making," and "translational research." KEY FINDINGS: The last decade has shown much progress in the study of AKI, including evidence of a pathophysiological link between AKI and CKD. We are now in a phase of redesigning animal models and discovering mechanisms that can replicate the pathological conditions of the AKI-to-CKD continuum. Translating these findings into the clinic is a barrier that must be overcome. To this end, current efforts include prediction of AKI onset and maladaptive repair, detecting patients susceptible to the progression of chronic maladaptive repair, and understanding shared signaling mechanisms between AKI and CKD. LIMITATIONS: This is a narrative review of the literature that is partially influenced by the knowledge, perspectives, and experiences of the authors and their research background. IMPLICATIONS: Overall, this new knowledge from the AKI-to-CKD continuum will help bridge the discontinuity that exists between animal models and patients, resulting in more effective translational biomarkers and therapeutics to test in known AKI pathologies thereby preventing the chronicity of kidney injury progression.

JUSTIFICATION: La présente revue porte sur l'avancement des connaissances relatives à la phase de transition entre l'insuffisance rénale aiguë (IRA) et l'insuffisance rénale chronique (IRC) grâce à des modèles animaux améliorés, à l'étude des mécanismes communs à l'IRA et l'IRC, et à la contribution que la recherche chez l'humain peut apporter aux différentes approches translationnelles. SOURCES: PubMed et Google Scholar. MÉTHODOLOGIE: Une revue narrative a été réalisée à l'aide des principaux termes suivants : insuffisance rénale aiguë (acute kidney disease), insuffisance rénale chronique (chronic kidney disease), insuffisance rénale terminale (end-stage renal disease), modèles animaux (animal models), revue (review), prise de décision (decision making) et recherche translationnelle (translational research). PRINCIPAUX RÉSULTATS: La dernière décennie a été marquée par de nombreux progrès dans l'étude de l'IRA, notamment par la mise en évidence d'un lien physiopathologique entre l'IRA et l'IRC. Nous en sommes actuellement à développer de nouveaux modèles animaux et à élaborer des mécanismes pouvant reproduire les conditions pathologiques du continuum IRA-IRC. Transposer ces résultats en clinique est un obstacle à surmonter. C'est pourquoi, les efforts déployés actuellement incluent la prédiction du début de l'IRA et d'une récupération rénale inadéquate, la détection des patients susceptibles de progresser vers une récupération rénale inadéquate à long terme et la compréhension des mécanismes de signalisation communs à l'IRA et l'IRC. LIMITES: Il s'agit d'une revue narrative de la littérature qui est en partie influencée par les connaissances, les perceptions et les expériences des auteurs, de même que par leur formation antérieure en recherche. CONCLUSION: Dans l'ensemble, ces nouvelles connaissances tirées du continuum menant de l'IRA à l'IRC aideront à combler les lacunes entre les modèles animaux et les patients, ce qui permettra de mettre au point des biomarqueurs translationnels et des traitements plus efficaces à tester sur les pathologies menant à l'IRA, dans le but de prévenir la progression et la chronicité de la maladie.