Post-Transplant Bone Disease in Kidney Transplant Recipients: Diagnosis and Management.

Kidney transplantation is the preferred gold standard modality of treatment for kidney failure. Bone disease after kidney transplantation is highly prevalent in patients living with a kidney transplant and is associated with high rates of hip fractures. Fractures are associated with increased healthcare costs, morbidity and mortality. Post-transplant bone disease (PTBD) includes renal osteodystrophy, osteoporosis, osteonecrosis and bone fractures. PTBD is complex as it encompasses pre-existing chronic kidney disease-mineral bone disease and compounding factors after transplantation, including the use of immunosuppression and the development of de novo bone disease. After transplantation, the persistence of secondary and tertiary hyperparathyroidism, renal osteodystrophy, relative vitamin D deficiency and high levels of fibroblast growth factor-23 contribute to post-transplant bone disease. Risk assessment includes identifying both general risk factors and kidney-specific risk factors. Diagnosis is complex as the gold standard bone biopsy with double-tetracycline labelling to diagnose the PTBD subtype is not always readily available. Therefore, alternative diagnostic tools may be used to aid its diagnosis. Both non-pharmacological and pharmacological therapy can be employed to treat PTBD. In this review, we will discuss pathophysiology, risk assessment, diagnosis and management strategies to manage PTBD after kidney transplantation.

What should the characteristics and attributes of an accredited nephrology training programme be? Looking for high standards.

The Renal Section of the European Union of Medical Specialists is working towards harmonization and optimization of nephrology training across Europe and its Mediterranean borders. In addition to the need for harmonization of the heterogeneous time dedicated to training, it is necessary to ensure that the learning environment is of a sufficiently high standard to develop skilled specialists. Thus, there is a need to review the core educational infrastructure and resources that should be provided to trainees in order to be considered centres of excellence for nephrology training. This review addresses most of the characteristics and attributes that constitute a high-calibre training centre of excellence, considering that a training centre might not represent a single institution, but a network of institutions that provide a coordinated and complete curriculum to the trainee. The training institution should provide, apart from the classical current nephrological facilities (clinical nephrology, haemodialysis, peritoneal dialysis and transplantation), a number of other complementary facilities, including immunology, nephropathology-with a dedicated and expert renal pathologist-all the specialities of general medicine and general surgery and, in particular, vascular surgery, radiology and interventional radiology specialist services (renal biopsy, renal ultrasound and permanent vascular access) and intensive care unit. In addition to clinical training, a training centre of excellence should offer research facilities to allow trainees the opportunity to be involved in epidemiological, clinical, translational or basic scientific research. The training centres should ideally hold a certification of training accreditation. If the European and its Mediterranean border countries wish to guarantee a high standard of training in nephrology, their national health services need to recognize their responsibility towards the importance of doctor training, providing enough time for educational activities and investing in the resources required for high-standard specialist training.

Updated programme for harmonization of training in nephrology in the European Union.

In 1996, the first European Union of Medical Specialists (UEMS) minimum standards programme in nephrology was published. Since then, medical practice in an expanded European Union (EU) has evolved significantly. These changes have prompted the UEMS Nephrology Section to update and review the programme on harmonization of nephrology training in the EU. Although directives of the EU indicate that a specialist from one EU member state must be recognized in all EU member states, the current practical implications of these directives are limited due to the important existing differences in the EU member states' training programmes. Although not exhaustive, the present document aims to profile a minimum common framework of nephrology training in the EU for both trainers and higher-specialty trainees. The nephrology programme addresses several topics, among them enrolment requirements, duration and organization of the training and a detailed description of the knowledge, competences, practical skills and attitudes necessary to become a specialist in nephrology. Whilst the development of a standard, pan-EU nephrology training programme is not realistic, the UEMS Nephrology section believes that this does not diminish the need for improving harmonization of training in the EU.

Gene expression profiling in glomeruli from human kidneys with diabetic nephropathy.

BACKGROUND: Diabetic nephropathy (DN) is a frequent complication in patients with diabetes mellitus. To find improved intervention strategies in this disease, it is necessary to investigate the molecular mechanisms involved. To obtain more insight into processes that lead to DN, messenger RNA expression profiles of diabetic glomeruli and glomeruli from healthy individuals were compared. METHODS: Two morphologically normal kidneys and 2 kidneys from patients with DN were used for the study. Glomerular RNA was hybridized in duplicate on Human Genome U95Av2 Arrays (Affymetrix, Santa Clara, CA). Several transcripts were tested further in independent patient groups and at the protein level by immunohistochemistry. RESULTS: Ninety-six genes were upregulated in diabetic glomeruli, whereas 519 genes were downregulated. The list of overexpressed genes in DN includes aquaporin 1, calpain 3, hyaluronoglucosidase, and platelet/endothelial cell adhesion molecule. The list of downregulated genes includes bone morphogenetic protein 2, vascular endothelial growth factor (VEGF), fibroblast growth factor 1, insulin-like growth factor binding protein 2, and nephrin. A decrease in VEGF and nephrin could be validated at the protein level and also at the RNA level in renal biopsy specimens from 5 additional patients with diabetes. CONCLUSION: Results of oligonucleotide microarray analyses on control and diabetic glomeruli are presented and discussed in their relation to vascular damage, mesangial matrix expansion, proliferation, and proteinuria. Our findings suggest that progression of DN might result from diminished tissue repair capability.

DNA oligonucleotide microarray technology identifies fisp-12 among other potential fibrogenic genes following murine unilateral ureteral obstruction (UUO): modulation during epithelial-mesenchymal transition.

BACKGROUND: Tubulointerstitial inflammation and fibrosis are pathologic hallmarks of end-stage renal disease (ESRD). Here we have used DNA microarray technology to monitor the transcriptomic responses to murine unilateral ureteral obstruction (UUO) with a view to identifying molecular modulators of tubulointerstitial fibrosis. METHODS: Using Affymetrix Mu74Av2 microarrays, gene expression 4 and 10 days postobstruction was investigated relative to control contralateral kidneys. Candidate profibrogenic genes were further investigated in epithelial cells undergoing epithelial to mesenchymal transition (EMT) in vitro. RESULTS: mRNA levels for 1091 gene/EST sequences, of a total of 12,488 displayed on the microarray, were altered twofold or greater by days 4 and 10 postobstruction compared to contralateral control kidneys. Genes were categorised into functional groups, including modulators of cytoskeletal and extracellular matrix metabolism, cell growth, signalling, and transcription/translational events. Among the potentially profibrogenic genes, whose mRNA levels were increased after UUO, were fibroblast-inducible secreted protein (fisp-12), the murine homologue of connective tissue growth factor (CTGF), collagen XVIIIalpha1, secreted protein acidic and rich in cysteine (SPARC), and src-suppressed C-kinase substrate (SSeCKS). A sustained increase in fisp-12 mRNA level was observed during EMT induced by transforming growth factor-beta1 (TGF-beta1) and epidermal growth factor (EGF). CONCLUSION: Altered gene expression in murine UUO has been demonstrated. Increased expression of fisp-12, SPARC, and SSeCKS has been shown in response to TGF-beta1 treatment and during EMT, suggesting that these genes may offer potential therapeutic targets against tubulointerstitial fibrosis.

Gremlin: an example of the re-emergence of developmental programmes in diabetic nephropathy.

The past two decades have yielded major advances in our understanding of the pathogenetic mechanisms that cause diabetic nephropathy. Of particular interest is the emerging paradigm of the recapitulation of developmental programmes within the diabetic kidney. Recently we have used the complementary techniques of suppression subtractive hybridization and Affymetrix GeneChips to assess changes in gene expression in human mesangial cells subjected to high ambient glucose concentrations and cyclic mechanical strain in vitro, the latter being models of hyperglycaemia and glomerular hypertension, respectively. In this review, we will focus on the potential role of one such differentially expressed gene, namely gremlin, in the pathogenesis of diabetic nephropathy. In the context of developmental nephrology, gremlin warrants special mention. Gremlin is a 184 amino acid protein and a member of the cysteine knot superfamily. The protein is highly conserved during evolution and is present in soluble and cell-associated forms. It belongs to a novel family of bone morphogenetic protein (BMP) antagonists that includes the head-inducing factor Cerberus and the tumour suppressor DAN. These proteins play important roles in limb development and neural crest cell differentiation. Evidence will be presented that mesangial cell gremlin expression is up-regulated by high ambient glucose, cyclic mechanical strain and transforming growth factor-beta (TGF-beta) and that gremlin may be an important modulator of mesangial cell proliferation and epithelial-mesenchymal transdifferentiation in a diabetic milieu.

Gremlins: is this what renal fibrogenesis has come to?

Gremlin is a member of the differential screening-selected gene aberrative in the neuroblastoma (DAN) family of bone morphogenetic protein (BMP) antagonists. Gremlin influences diverse processes in growth, differentiation and development. Increased expression of gremlin has recently been demonstrated in several models of diabetic nephropathy. Gremlin arrests the cell cycle in mesangial cells and has also been shown to be upregulated in transdifferentiated renal proximal tubular cells. This review summarizes emerging evidence implicating gremlin in the pathophysiology of glomerulosclerosis and tubulointerstitial fibrosis. Gremlin is a potential novel therapeutic target in progressive renal diseases.

15-Epi-16-(para-fluorophenoxy)-lipoxin A(4)-methyl ester, a synthetic analogue of 15-epi-lipoxin A(4), is protective in experimental ischemic acute renal failure.

Lipoxins are endogenous lipoxygenase-derived eicosanoids, generated during inflammatory, hypersensitivity, and vascular events, that display vasodilatory, antiinflammatory, and pro-resolution activity. Here, we evaluated the efficacy of 15-epi-16-(para-fluorophenoxy)-lipoxin A(4)-methyl ester (15-epi-16-(FPhO)-LXA(4)-Me), a stable synthetic analogue of aspirin-triggered 15-epi-lipoxin A(4) in ischemic acute renal failure (ARF) in NIH Swiss mice. ARF was induced by 30-min crossclamping of renal pedicles and was associated with elevated serum creatinine, morphologic injury, polymorphonuclear leukocyte (PMN) recruitment, and increased mRNA levels for adhesion molecules (intercellular adhesion molecule-1 [ICAM-1] and vascular cell adhesion molecule-1 [VCAM-1]), chemokines (growth regulated oncogene-1 [GRO1]), and cytokines (interleukin-1beta [IL-1beta] and IL-6) after 24-h reperfusion. A single bolus of 15-epi-16-(FPhO)-LXA(4)-Me afforded striking functional (mean +/- SEM creatinine in mg/dl: sham-operated, 0.77 +/- 0.04; ARF + vehicle, 2.49 +/- 0.19; ARF + 15-epi-16-(FPhO)-LXA(4)-Me, 0.75 +/- 0.12; P < 0.001) and morphologic protection and reduced PMN infiltration. Treatment with 15-epi-16-(FPhO)-LXA(4)-Me was also associated with lower IL-1beta, IL-6, and GRO1 mRNA levels, whereas ICAM-1 and VCAM-1 mRNA levels were unchanged. Compatible with these results, LXA(4) blunted chemoattractant-stimulated PMN migration across HK-2 renal epithelial cell monolayers in vitro, but it did not inhibit cytokine-induced HK-2 ICAM-1 expression or adhesiveness for PMN. Interestingly 15-epi-16-(FPhO)-LXA(4)-Me-treated animals also displayed increased renal mRNA levels for suppressors of cytokine signaling-1 (SOCS-1) and SOCS-2, but not CIS-1, endogenous inhibitors of cytokine-elicited Jak/Stat-signaling pathways. These results indicate that 15-epi-16-(FPhO)-LXA(4)-Me is protective in renal ischemia reperfusion injury in vivo, at least partially by modulating cytokine and chemokine expression and PMN recruitment, and provides a rationale for further exploration of the efficacy of LXA(4) structural analogues in ischemic ARF and other renal diseases.

Gene responses to hyperglycaemia.

The rising tide of diabetic nephropathy (DN) is arguably the most challenging clinical problem confronting nephrologists at the beginning of the new century. Central to the development of novel diagnostic and therapeutic strategies will be the elucidation of the molecular events that drive this complex disease. In this review, we briefly discuss the major growth factors and cytokines identified as mediators of tissue injury in DN in the "pre-gene subtraction" era. We then highlight the remarkable array of new molecular players already identified with the introduction of gene subtraction techniques, such as differential-display PCR, suppression-subtractive hybridization, and nucleotide micro-arrays, and discuss the likely impact of these technologies going forward. Finally, we summarize the current knowledge on the cell signalling events triggered by high glucose levels that influence gene expression in DN and that represent additional therapeutic targets in this setting.