The Aachen Minipig: Phenotype, Genotype, Hematological and Biochemical Characterization, and Comparison to the Göttingen Minipig.

Background: The pig is one of the most frequently used large animal models for biomedical research, especially in the field of translational research and surgical models. While standard livestock breeds are used in short-term and acute studies, minipig breeds are the preferred breeds in long-term and chronic studies due to their limited growth and body weight.

Objective: In consideration of the 3R principle (refinement, reduction, replacement) and the increasing demand, the aim of this study was to generate a new, robust, non-specific-pathogen-free minipig breed, the Aachen minipig.

Divergent functions of the Rho GTPases Rac1 and Cdc42 in podocyte injury.

Podocytes are highly specialized epithelial cells with complex actin cytoskeletal architecture crucial for maintenance of the glomerular filtration barrier. The mammalian Rho GTPases Rac1 and Cdc42 are molecular switches that control many cellular processes, but are best known for their roles in the regulation of actin cytoskeleton dynamics. Here, we employed podocyte-specific Cre-lox technology and found that mice with deletion of Rac1 display normal podocyte morphology without glomerular dysfunction well into adulthood.

A molecular signature of proteinuria in glomerulonephritis.

Proteinuria is the most important predictor of outcome in glomerulonephritis and experimental data suggest that the tubular cell response to proteinuria is an important determinant of progressive fibrosis in the kidney. However, it is unclear whether proteinuria is a marker of disease severity or has a direct effect on tubular cells in the kidneys of patients with glomerulonephritis. Accordingly we studied an in vitro model of proteinuria, and identified 231 "albumin-regulated genes" differentially expressed by primary human kidney tubular epithelial cells exposed to albumin.

Renal gene and protein expression signatures for prediction of kidney disease progression.

Although chronic kidney disease (CKD) is common, only a fraction of CKD patients progress to end-stage renal disease. Molecular predictors to stratify CKD populations according to their risk of progression remain undiscovered. Here we applied transcriptional profiling of kidneys from transforming growth factor-beta1 transgenic (Tg) mice, characterized by heterogeneity of kidney disease progression, to identify 43 genes that discriminate kidneys by severity of glomerular apoptosis before the onset of tubulointerstitial fibrosis in 2-week-old animals.

A pilot study of gene expression-based categorization of pancreas transplant biopsies.

Gene expression profiling has emerged as a powerful strategy to define transcriptional mechanism activated in organ transplantation. We performed a pilot feasibility study of mRNA-based pancreas transplant biopsy stratification. The mRNAs expression of 32 genes, observed in renal transplant dysfunction, and 10 pancreas-specific genes were evaluated in 26 pancreas transplant biopsy specimens by quantitative real-time polymerase chain reaction using TaqMan Low Density Array technology.

Enhanced expression of Janus kinase-signal transducer and activator of transcription pathway members in human diabetic nephropathy.

Objective: Glomerular mesangial expansion and podocyte loss are important early features of diabetic nephropathy, whereas tubulointerstitial injury and fibrosis are critical for progression of diabetic nephropathy to kidney failure. Therefore, we analyzed the expression of genes in glomeruli and tubulointerstitium in kidney biopsies from diabetic nephropathy patients to identify pathways that may be activated in humans but not in murine models of diabetic nephropathy that fail to progress to glomerulosclerosis, tubulointerstitial fibrosis, and kidney failure.

Research Design And Methods: Kidney biopsies were obtained from 74 patients (control subjects, early and progressive type 2 diabetic nephropathy).

Maternal environment interacts with modifier genes to influence progression of nephrotic syndrome.

Mutations in the NPHS2 gene, which encodes podocin, are responsible for some cases of sporadic and familial autosomal recessive steroid-resistant nephrotic syndrome. Inter- and intrafamilial variability in the progression of renal disease among patients bearing NPHS2 mutations suggests a potential role for modifier genes. Using a mouse model in which the podocin gene is constitutively inactivated, we sought to identify genetic determinants of the development and progression of renal disease as a result of the nephrotic syndrome.

The death ligand TRAIL in diabetic nephropathy.

Apoptotic cell death contributes to diabetic nephropathy (DN), but its role is not well understood. The tubulointerstitium from DN biopsy specimens was microdissected, and expression profiles of genes related to apoptosis were analyzed. A total of 112 (25%) of 455 cell death-related genes were found to be significantly differentially regulated.

A complex pattern of chemokine receptor expression is seen in osteosarcoma.

Background: Osteosarcoma is the most frequent bone tumor in childhood and adolescence. Patients with primary metastatic disease have a poor prognosis. It is therefore important to better characterize the biology of this tumor to define new prognostic markers or therapeutic targets for tailored therapy.

Modification of kidney barrier function by the urokinase receptor.

Podocyte dysfunction, represented by foot process effacement and proteinuria, is often the starting point for progressive kidney disease. Therapies aimed at the cellular level of the disease are currently not available. Here we show that induction of urokinase receptor (uPAR) signaling in podocytes leads to foot process effacement and urinary protein loss via a mechanism that includes lipid-dependent activation of alphavbeta3 integrin.

Nitric oxide modulates expression of extracellular matrix genes linked to fibrosis in kidney mesangial cells.

Mesangial cells are thought to be important mediators of glomerular inflammation and fibrosis. Studies have established a direct role for nitric oxide (NO) in the regulation of gene expression in mesangial cells. Representational difference analysis was used to investigate changes in gene expression elicited by the treatment of S-nitroso-L-glutathione in rat mesangial cells.

Interstitial vascular rarefaction and reduced VEGF-A expression in human diabetic nephropathy.

Diabetic nephropathy (DN) is a frequent complication in patients with diabetes. Although the majority of DN models and human studies have focused on glomeruli, tubulointerstitial damage is a major feature of DN and an important predictor of renal dysfunction. This study sought to investigate molecular markers of pathogenic pathways in the renal interstitium of patients with DN.

Induction of TRPC6 channel in acquired forms of proteinuric kidney disease.

Injury to podocytes and their slit diaphragms typically leads to marked proteinuria. Mutations in the TRPC6 gene that codes for a slit diaphragm-associated, cation-permeable ion channel have been shown recently to co-segregate with hereditary forms of progressive kidney failure. Herein is shown that induced expression of wild-type TRPC6 is a common feature of human proteinuric kidney diseases, with highest induction observed in membranous nephropathy.

Modular activation of nuclear factor-kappaB transcriptional programs in human diabetic nephropathy.

Diabetic nephropathy (DN) is the leading cause of end-stage renal failure and a major risk factor for cardiovascular mortality in diabetic patients. To evaluate the multiple pathogenetic factors implicated in DN, unbiased mRNA expression screening of tubulointerstitial compartments of human renal biopsies was combined with hypothesis-driven pathway analysis. Expression fingerprints obtained from biopsies with histological diagnosis of DN (n = 13) and from control subjects (pretransplant kidney donors [n = 7] and minimal change disease [n = 4]) allowed us to segregate the biopsies by disease state and stage by the specific expression signatures.

Expression and regulation of Toll-like receptors in lupus-like immune complex glomerulonephritis of MRL-Fas(lpr) mice.

Background: How microbial infections exacerbate immune complex glomerulonephritis remains speculative. Toll-like receptors (TLRs) may be involved in this phenomenon, because TLRs have potent immunostimulatory functions when exposed to selected pathogen-associated molecules.

Methods: We addressed this issue by characterizing the expression of TLR1-9 in MRLlpr/lpr mice that spontaneously develop immune complex glomerulonephritis as part of a systemic lupus-like autoimmune syndrome.

Gene expression profiling analysis in nephrology: towards molecular definition of renal disease.

The increase in progressive kidney disease, resulting in a constantly rising prevalence of endstage renal disease (ESRD), urgently warrants the development of more effective strategies to diagnose, prevent, and intervene in renal disease. Histological information obtained by renal biopsies (RBx) is a cornerstone of the current management of kidney disease. Renal tissue can provide critical information on the disease process not available by nontissue-based approaches.

Podocyte-specific deletion of integrin-linked kinase results in severe glomerular basement membrane alterations and progressive glomerulosclerosis.

Alterations in glomerular podocyte cell-cell and cell-matrix contacts are key events in progressive glomerular failure. Integrin-linked kinase (ILK) has been implicated in podocyte cell-matrix interaction and is induced in proteinuria. For evaluation of ILK function in vivo, mice with a Cre-mediated podocyte-specific ILK inactivation were generated.

Comparative promoter analysis allows de novo identification of specialized cell junction-associated proteins.

Shared transcription factor binding sites that are conserved in distance and orientation help control the expression of gene products that act together in the same biological context. New bioinformatics approaches allow the rapid characterization of shared promoter structures and can be used to find novel interacting molecules. Here, these principles are demonstrated by using molecules linked to the unique functional unit of the glomerular slit diaphragm.

Expression of the chemokine receptor CXCR1 in human glomerular diseases.

Leukocyte infiltration, a hallmark of renal diseases, is orchestrated in part by the actions of chemokines. The chemokine CXCL8/interleukin (IL)-8 is expressed during renal diseases and allograft rejection, whereas the corresponding receptor CXCR1 has not been described previously. Expression of CXCR1 was characterized in peripheral blood using multicolor fluorescence-activated cell sorter analysis (FACS).

Molecular approaches to chronic kidney disease.

Purpose Of Review: The progression of chronic kidney disease to terminal renal failure remains a major challenge in nephrology. Definition of the dynamic differences in gene regulation, protein interaction and protein function in this process might allow the development of rationally designed management strategies for the individual patient. Current approaches to identifying the molecular markers required to implement this 'personalized medicine' concept in progressive renal failure will be presented in this review.

Novel role of toll-like receptor 3 in hepatitis C-associated glomerulonephritis.

Hepatitis C virus (HCV) infection is frequently complicated by glomerulonephritis with immune complexes containing viral RNA. We examined the potential influence of Toll-like receptors (TLRs), specifically TLR3 recognition of viral dsRNA exemplified by polyriboinosinic:polyribocytidylic acid [poly(I:C) RNA]. Normal human kidney stained positive for TLR3 on mesangial cells (MCs), vascular smooth muscle cells, and collecting duct epithelium.

Stereospecific and redox-sensitive increase in monocyte adhesion to endothelial cells by homocysteine.

Objective: Previous studies have shown that elevated homocysteine (Hcy) levels promote the development of atherosclerotic lesions in atherosclerosis-prone animal models. There is evidence that oxidant stress contributes to Hcy's deleterious effects on the vasculature. The accumulation and adhesion of monocytes to the vascular endothelium is a critical event in the development of atherosclerosis.

Toll-like receptor-4: renal cells and bone marrow cells signal for neutrophil recruitment during pyelonephritis.

Background: The molecular mechanisms of pathogen recognition that initiate infective pyelonephritis are poorly understood. Toll-like receptor-4 (TLR4) mutant mice infected with uropathogenic Escherichia coli lack renal CXCL2 mRNA expression, subsequent neutrophil recruitment, and renal abscess formation.

Methods: We used a bone marrow transplant approach in order to investigate the contribution of TLR4 in intrinsic renal cells or bone-marrow-derived immune cells to neutrophil recruitment during infective pyelonephritis.

Polyomavirus DNA and RNA detection in renal allograft biopsies: results from a European multicenter study.

Polyomavirus mediated nephropathy is an increasingly recognized complication in renal transplant recipients. In all, 362 renal biopsies collected from 15 European transplant centers were analyzed for presence of Polyomavirus nucleic acid (BK virus [BKV] and JC virus [JCV]). We evaluated 302 biopsies of patients with renal allograft dysfunction, including three with known BKV allograft nephropathy (BKVAN), and 60 native kidney biopsies.

CD20-positive infiltrates in human membranous glomerulonephritis.

Membranous glomerulonephritis (MGN), histologically defined by subepithelial immune deposits, is the most common cause of nephrotic syndrome in Caucasian adults. The current hypothesis of the underlying disease mechanism postulates production of antibodies against podocyte-derived antigens. Respective antigens could be demonstrated in different animal models and recently in human neonatal MGN.