Amyloid fibril structure from the vascular variant of systemic AA amyloidosis.

Systemic AA amyloidosis is a debilitating protein misfolding disease in humans and animals. In humans, it occurs in two variants that are called 'vascular' and 'glomerular', depending on the main amyloid deposition site in the kidneys. Using cryo electron microscopy, we here show the amyloid fibril structure underlying the vascular disease variant. Fibrils purified from the tissue of such patients are mainly left-hand twisted and contain two non-equal stacks of fibril proteins. They contrast in these properties to the fibrils from the glomerular disease variant which are right-hand twisted and consist of two structurally equal stacks of fibril proteins. Our data demonstrate that the different disease variants in systemic AA amyloidosis are associated with different fibril morphologies.

Deceased Donor Kidney Transplantation in the Eurotransplant Senior Program (ESP): A Single-Center Experience from 2008 to 2013.

BACKGROUND: The aim of this study was to evaluate the outcome after transplantation of deceased allografts in donor/recipient pairs aged ≥65 years enrolled in the Eurotransplant Senior Program (ESP). MATERIAL AND METHODS: In this retrospective cohort study we evaluated data from 89 patients transplanted under the ESP protocol from 2008 to 2013. Outcome parameters included graft and patient survival, rate of biopsy-proven acute rejections (BPAR), peri- and post-operative complications, tumor development, development of donor-specific antibodies (DSA), and the prognostic role of preimplantation biopsies. RESULTS: One-year patient and allograft survival rates were 92.1% and 84.3%, respectively. During follow-up, 23 (26%) patients died; the major cause of death was sepsis, followed by cardiovascular events and malignancies. BPAR episodes were frequent within the first year (~33%) and overall were less common in patients treated with tacrolimus. Post-transplant malignancies were seen in 15 (17%) patients. During follow-up, 16 (18%) patients developed DSA; patients with delayed graft function (DGF) were more likely to develop DSA (p=0.029). A higher preimplantation biopsy score was associated with DGF but did not predict later graft outcome. CONCLUSIONS: The results highlight increased risks in ESP transplant candidates and the importance of careful surveillance of this patient group.

Mutations in WDR19 encoding the intraflagellar transport component IFT144 cause a broad spectrum of ciliopathies.

BACKGROUND: An emerging number of clinically and genetically heterogeneous diseases now collectively termed ciliopathies have been connected to the dysfunction of primary cilia. We describe an 8-year-old girl with a complex phenotype that did not clearly match any familiar syndrome. CASE-DIAGNOSIS/TREATMENT: Hypotonia, facial dysmorphism and retardation were noted shortly after birth. Other features included short stature, mild skeletal anomalies, strabism, deafness, subdural hygroma, hepatosplenomegaly and end-stage renal failure. Renal biopsy revealed tubular atrophy, interstitial fibrosis and segmental glomerulosclerosis. After exclusion of a chromosomal abnormality by array-comparative genomic hybridization (CGH), we performed next-generation sequencing (NGS) using a customized panel that targeted 131 genes known or hypothesized to cause ciliopathies. We identified the novel homozygous WDR19 mutation c.1483G > C (p.Gly495Arg) that affects an evolutionarily highly conserved residue in the intraflagellar transport protein IFT144, is absent from databases and is predicted to be pathogenic by all bioinformatic sources used. CONCLUSION: Mutations in WDR19 encoding the intraflagellar transport component IFT144 have recently been described in single families with the clinically overlapping skeletal ciliopathies Jeune and Sensenbrenner syndromes, combined or isolated nephronophthisis (NPHP) and retinitis pigmentosa (RP) (Senior-Loken syndrome). Our patient emphasizes the usefulness and efficiency of a comprehensive NGS panel approach in patients with unclassified ciliopathies. It further suggests that WDR19 mutations can cause a broad spectrum of ciliopathies that extends to Jeune and Sensenbrenner syndromes, RP and renal NPHP-like phenotypes.

BK viremia and polyomavirus nephropathy in 352 kidney transplants; risk factors and potential role of mTOR inhibition.

BACKGROUND: Polyomavirus BK nephropathy (PyVAN) remains an important cause of early graft dysfunction and graft loss in kidney transplantation. METHODS: In this retrospective, single centre cohort study we studied the incidence and outcome of BK viral infection in 352 patients transplanted in 2008-2011. RESULTS: During follow-up viral replication was detected in 48 patients (13.6%); 22 patients (6.2%) had biopsy proven PyVAN.In multivariate logistic regression analyses risk factors for BK-viremia were lack of enrolment into randomized controlled trials (RCTs), biopsy proven acute rejections, cytomegaly virus (CMV) serostatus of both donor and recipient and previous transplantation.In patients without PyVAN reduction or switch of immunosuppression was associated with rapid viral clearance and stable graft function. In contrast, in most patients with PyVAN graft function deteriorated and 5 patients prematurely lost their allograft. Switch of immunosuppression to a low dose cyclosporine plus mTOR inhibitor based regimen in patients with PyVAN was safe, well tolerated and tended to be associated with a better short-term outcome in terms of graft function compared to reduction of existing immunosuppression alone. CONCLUSIONS: With the lack of licensed anti-polyoma viral drugs reduction or conversion of immunosuppression remains the mainstay of therapy in patients with PyVAN. The combination of low dose cyclosporine plus mTOR inhibition appears to be safe and warrants further investigation.

Oncofertility: combination of ovarian stimulation with subsequent ovarian tissue extraction on the day of oocyte retrieval.

BACKGROUND: New anticancer treatments have increased survival rates for cancer patients, but often at the cost of sterility. Several strategies are currently available for preserving fertility. However, the chances of achieving a pregnancy with one technique are still limited. A combination of methods is therefore recommended in order to maximize women's chances of future fertility. In this retrospective study, ovarian stimulation with subsequent ovarian tissue extraction on the day of oocyte retrieval were combined and the quality of the ovarian tissue, the numbers and quality of oocytes, time requirements, and the safety of the strategy were examined. METHODS: Fourteen female patients suffering from malignant diseases underwent one in vitro fertilization cycle. Different stimulation protocols were used, depending on the menstrual cycle. Transvaginal oocyte retrieval was scheduled 34-36 h after human chorionic gonadotropin administration. Immediately afterwards, ovarian tissue was extracted laparoscopically. RESULTS: A mean of 10 oocytes were retrieved per patient, and 67% of the oocytes were successfully fertilized using intracytoplasmic sperm injection. No periprocedural complications and no complications leading to postponement of the start of chemotherapy occurred. The ovarian tissues were of good quality, with a normal age-related follicular distribution and without carcinoma cell invasion. CONCLUSIONS: An approach using ovarian stimulation first, followed by laparoscopic collection of ovarian tissue, is a useful strategy for increasing the efficacy of fertility preservation techniques. The ovarian tissue is not affected by prior ovarian stimulation.

From red to white urine: a patient's nightmare with a rather benign outcome.

BACKGROUND: Chyluria is a medical condition with presence of chyle in the urine. The disease is most prevalent in endemic regions of Africa and the Indian subcontinent where it is mostly caused by parasitic infections, particularly lymphatic filariasis due to wucheria bancrofti. Non-parasitic chyluria, however, is a very rare finding. CASE PRESENTATION: We report the case of a 48 year old woman who developed a lymphorenal fistula with chyluria following ureterrenoscopy with biopsies taken for urological work-up of persistent macrohematuria. Renal biopsy confirmed the diagnosis of benign familial hematuria due to thin basement nephropathy, a condition frequently associated with episodes of macrohematuria. CONCLUSIONS: This case highlights a rare case of non-parasitic chyluria as a complication of urological work-up for macrohematuria of benign nature.

Severe metabolic alkalosis and recurrent acute on chronic kidney injury in a patient with Crohn's disease.

BACKGROUND: Diarrhea is common in patients with Crohn's disease and may be accompanied by acid base disorders, most commonly metabolic acidosis due to intestinal loss of bicarbonate. CASE PRESENTATION: Here, we present a case of severe metabolic alkalosis in a young patient suffering from M. Crohn. The patient had undergone multiple resections of the intestine and suffered from chronic kidney disease. He was now referred to our clinic for recurrent acute kidney injury, the nature of which was pre-renal due to profound volume depletion. Renal failure was associated with marked hypochloremic metabolic alkalosis which only responded to high volume repletion and high dose blockade of gastric hypersecretion. Intestinal failure with stomal fluid losses of up to 5.7 litres per day required port implantation to commence parenteral nutrition. Fluid and electrolyte replacement rapidly improved renal function and acid base homeostasis. CONCLUSIONS: This case highlights the important role of gastrointestinal function to maintain acid base status in patients with Crohn's disease.

Autocrine VEGF-VEGF-R loop on podocytes during glomerulonephritis in humans.

BACKGROUND: Vascular endothelial growth factor (VEGF) is the most important and tightly regulated angiogenic cytokine in the kidney. Its activity is critical for capillary/glomerular preservation and repair, and recent studies have also demonstrated its relevance for the preservation of podocytes. METHODS: The present study investigated a large number (n = 153) of renal biopsies from patients with glomerulonephritis (GN) and evaluated the expression and activity of the glomerular VEGF system [VEGF, VEGF-R1, VEGF-R2 and biologically active VEGF as identified by VEGF-VEGF receptor complexes (VEGF-VEGF-R)] in parallel with markers of renal function, injury and repair. RESULTS: Whereas glomerular VEGF expression was clearly elevated, VEGF-R expression levels were widely unchanged. In parallel to the overall VEGF expression, the biological activity of VEGF on its receptors was uniformly significantly enhanced. Interestingly, the expression pattern of VEGF-R1 and VEGF-R2 significantly changed during GN where a very prominent podocytic pattern appeared, which was also detected for receptor-bound VEGF. VEGF expression and activity could be linked with indicators of renal injury such as glomerular proliferation and creatinine, respectively. CONCLUSIONS: This study shows, for the first time, increased podocytic VEGF-VEGF-R binding during human GN, suggesting not only the existence of a glomerular paracrine proangiogenic, but also an autocrine role of the VEGF-VEGF-R system in diseased podocytes.

Influence of cyclooxygenase inhibitors on the function of the prostaglandin transporter organic anion-transporting polypeptide 2A1 expressed in human gastroduodenal mucosa.

The human organic anion-transporting polypeptide 2A1 (OATP2A1) is a prostaglandin transporter expressed in several tissues and plays an important role for local distribution of prostaglandins, which contribute to the integrity of gastric mucosa. Blockade of prostaglandin pathways by cyclooxygenase (COX) inhibitors has been associated with serious side effects such as gastrointestinal ulceration and bleeding. However, little is known regarding OATP2A1 expression in the upper gastrointestinal tract and the potential impact of cyclooxygenase inhibitors on OATP2A1 function. We first investigated the expression of OATP2A1 mRNA and protein in human gastroduodenal mucosa using human biopsy specimens obtained from antrum, corpus, and duodenum. The results indicate that OATP2A1 is expressed in the neck region and deep pyloric glands of antrum and in parietal cells of gastric corpus. Second, we examined various COX inhibitors for their effects on OATP2A1 transporter activity. Using HEK293 cells expressing OATP2A1, we found that diclofenac and lumiracoxib are potent inhibitors of OATP2A1-mediated transport of prostaglandin (PG) E(2) with IC(50) values of 6.2 +/- 1.2 and 3.1 +/- 1.2 microM. In contrast, indomethacin, ketoprofen, and naproxen led to significant stimulation of OATP2A1-mediated PGE(2) transport by 162.7 +/- 13.9, 77.2 +/- 3.6, and 32.3 +/- 4.9%, respectively. Taken together, our results suggest that various clinically used COX inhibitors have differential impact on the function of the prostaglandin transporter OATP2A1 in human stomach and that these effects may contribute to differences in the gastrointestinal side effects of COX inhibitors.

An unusual case of hyponatraemia.

The differential diagnosis of hyponatraemia is manifold and includes hormonal disorders such as primary adrenal insufficiency or hypothyroidism. The diagnosis of adrenal insufficiency is always suggestive in cases of hypotension associated with hyponatraemia, hyperkalaemia and metabolic acidosis. We herein report a case of severe hyponatraemia in a patient with Addison's disease. The underlying cause was disseminated adrenal tuberculosis without any evidence of other organ involvement. To date, tuberculosis remains a frequent cause of adrenal insufficiency although the pathophysiology of adrenal tropism is poorly understood.

Angiostatic immune reaction in colorectal carcinoma: Impact on survival and perspectives for antiangiogenic therapy.

Angiogenesis and inflammation are the 2 major stroma reactions in colorectal carcinoma (CRC). Guanylate binding protein-1 (GBP-1) is a key mediator of angiostatic effects of inflammation. Therefore, we hypothesized that GBP-1 may be a biomarker of intrinsic angiostasis associated with an improved outcome in CRC patients. GBP-1 was strongly expressed in endothelial cells and immune cells in the desmoplastic stroma of 32% of CRC as determined by immunohistochemical investigation of 388 sporadic CRC. Cancer-related 5-year survival was highly significant (p < 0.001) increased (16.2%) in patients with GBP-1-positive CRC. Multivariate analysis showed that GBP-1 is an independent prognostic factor indicating a reduction of the relative risk of cancer-related death by the half (p = 0.032). A comparative transcriptome analysis (22,215 probe sets) of GBP-1-positive (n = 12) and -negative (n = 12) tumors showed that particularly IFN-gamma-induced genes including the major antiangiogenic chemokines CXCL9, CXCL10 and CXCL11 were coexpressed with GBP-1. Altogether our findings indicated that GBP-1 may be a novel biomarker and an active component of a Th-1-like angiostatic immune reaction in CRC. This reaction may affect patient's response to antiangiogenic therapy and the identification of such tumors may provide a novel criterion for patient selection. Moreover, the induction of a Th-1-like angiostatic immune reaction may be a promising approach for the clinical treatment of CRC.

A murine model of site-specific renal microvascular endothelial injury and thrombotic microangiopathy.

Despite the importance of endothelial injury and healing for primary and secondary renal disease and the availability of genetically engineered mouse models, to date no generally applicable murine disease model with site-specific renal endothelial injury has been established. We induced specific microvascular renal injury via selective renal arterial perfusion of the lectin concanavalin A (Con A) followed by sheep anti-concanavalin A and harvested tissues after 4 h, 24 h, days 3 and 7. Compared to control kidneys, histological evaluation demonstrated endothelial cell injury with subsequent complement, and platelet activation and thrombosis by light and electron microscopy. Mouse kidneys showed histologic evidence of severe glomerular and peritubular microvascular thrombosis with acute tubular necrosis, proteinuria, increased BUN and presence of schistocytes. Initial cell death of intrinsic renal cells resulted in a decrease of the glomerular cell count by 50% after 4 h followed by a proliferative response of glomerular (day 3, P < 0.05), interstitial (day 3, P < 0.05) and tubular cells leading to increased total glomerular cell count by day 7. This study establishes the Con A anti-Con A model as specific endothelial injury model in the mouse kidney providing a novel tool for investigating endothelial injury and repair mechanisms as well as elucidating the role of platelets in genetically engineered mice.

P2Y1 gene deficiency protects from renal disease progression and capillary rarefaction during passive crescentic glomerulonephritis.

The metabotropic receptor P2Y1 is necessary for full ADP-induced platelet activation and is localized on various intrinsic renal cells, including mesangial cells, podocytes, and endothelial cells. To date, nothing is known about the role of the P2Y1 receptor during inflammatory renal disease. The role of the P2Y1 receptor was investigated using 22 P2Y1 gene-deficient (-/-) and 27 wild-type (wt) mice during the time course of passive crescentic nephrotoxic glomerulonephritis. Six P2Y1 -/- and six wt mice served as undiseased controls. Renal tissues were harvested on days 1, 10, and 28 after disease induction. No renal phenotype was found in P2Y1 -/- versus wt mice. In contrast, during crescentic glomerulonephritis, approximately 50% of all wt mice died, whereas all P2Y1 -/- mice survived. Renal function as assessed by creatinine clearance measurements, glomerulosclerosis, and tubulointerstitial injury indices as well as glomerular and interstitial matrix expansion were improved significantly in P2Y1 -/- compared with wt mice. These changes were preceded by reduced glomerular and peritubular capillary rarefaction indices in P2Y1 -/- compared with wt mice. The alteration of the rates of both peritubular apoptosis and endothelial cell proliferation suggests improved capillary preservation in P2Y1 -/- mice early in disease (day 10) and an additional enhanced repair reaction in P2Y1 -/- mice at the late time point (day 28), whereas injury on day 1 seemed to be equivalent in both groups. It is concluded that loss of P2Y1 receptor function safeguards against capillary loss, fibrosis, and death by renal failure during experimental crescentic glomerulonephritis.