Eugenia Pedagogos

Double-Blind, Placebo-Controlled Study on the Effect of the Aldosterone Receptor Antagonist Spironolactone in Patients Who Have Persistent Proteinuria and Are on Long-Term Angiotensin-Converting Enzyme Inhibitor Therapy, with or without an Angiotensin II Receptor Blocker

Studies have shown that dual therapy with angiotensin-converting enzyme inhibitors (ACEI) and either angiotensin II receptor blockers or aldosterone receptor antagonists is more effective in reducing proteinuria than either agent used alone. The questions that remain are as follows: (1) Which of these agents should be used as dual therapy with the ACEI? (2) Does a higher level of blockade of the renin-angiotensin-aldosterone system with triple therapy offer an advantage over dual blockade? A 3-mo randomized, double-blind, placebo-controlled study was performed in 41 patients with proteinuria >1.5 g/d. Four treatment groups were compared: (1) Ramipril + spironolactone placebo + irbesartan placebo, (2) ramipril + irbesartan + spironolactone placebo, (3) ramipril + irbesartan placebo + spironolactone, and (4) ramipril + irbesartan + spironolactone. The percentage change in protein excretion differed according to treatment arm (ANOVA: F(3,35) = 8.6, P < 0.001). Pair-wise comparison showed that greater reduction in protein excretion occurred in treatment regimens that incorporated spironolactone. The reduction in proteinuria at 3 mo was as follows: Group 1, 1.4%; group 2, 15.7%; group 3, 42.0%; and group 4, 48.2%. The reduction in proteinuria among patients who were taking spironolactone-containing regimens was sustained at 6 and 12 mo. This study suggests that aldosterone receptor blockade offers a valuable adjuvant treatment when used with ACEI therapy for the reduction of proteinuria. Results suggest no advantage of triple blockade over dual blockade of the renin-angiotensin-aldosterone system to reduce proteinuria.

Barriers to Timely Arteriovenous Fistula Creation: A Study of Providers and Patients

BACKGROUND Current clinical practice guidelines recommend a native arteriovenous fistula (AVF) as the vascular access of first choice. Despite this, most patients in western countries start hemodialysis therapy using a catheter. Little is known regarding specific physician and system characteristics that may be responsible for delays in permanent access creation. STUDY DESIGN Multicenter cohort study using mixed methods; qualitative and quantitative analysis. SETTING & PARTICIPANTS 9 nephrology centers in Australia and New Zealand, including 319 adult incident hemodialysis patients. PREDICTOR Identification of barriers and enablers to AVF placement. OUTCOMES Type of vascular access used at the start of hemodialysis therapy. MEASUREMENTS Prospective data collection included data concerning predialysis education, interviews of center staff, referral times, and estimated glomerular filtration rate (eGFR) at AVF creation and dialysis therapy start. RESULTS 319 patients started hemodialysis therapy during the 6-month period, 39% with an AVF and 59% with a catheter. Perceived barriers to access creation included lack of formal policies for patient referral, long wait times for surgical review and access placement, and lack of a patient database for management purposes. eGFR thresholds at referral for and creation of vascular accesses were considerably lower than appreciated (in both cases, median eGFR of 7 mL/min/1.73 m(2)), with median wait times for access creation of only 3.7 weeks. First assessment by a nephrologist less than 12 months before dialysis therapy start was an independent predictor of catheter use (OR, 8.71; P < 0.001). Characteristics of the best performing centers included the presence of a formalized predialysis pathway with a centralized patient database and low nephrologist and surgeon to patient ratios. LIMITATIONS A limited number of patient-based barriers was assessed. Cross-sectional data only. CONCLUSIONS A formalized predialysis pathway including patient education and eGFR thresholds for access placement is associated with improved permanent vascular access placement.

Myofibroblast involvement in chronic transplant rejection.

BACKGROUND Chronic rejection remains the major cause of late graft failure. We studied the renal tissue of 10 renal transplant patients with chronic rejection in whom biopsies had been performed at various time points over a 15-year posttransplant period to ascertain whether myofibroblasts (MF) have a role in this process. METHODS Biopsies were grouped into five categories with respect to time after vascular anastomosis: 0 (n=10); 1 day to 3 months (n=7); 6-24 months (n=5); 36-72 months (n=7); and >72 months (n=5). A control group consisted of patients who had undergone routine biopsies at 0 (n=10), 3 (n=10), 12 (n=6), 60 (n=5), and >60 months (n=6) with no rejection. MF were identified by morphology and alpha-smooth muscle actin immunostaining. T cells and macrophages (MF) were identified using an antisera to CD3 and CD68, respectively. Collagen III deposition was similarly quantified by immunohistochemistry. Interstitial fractional area was measured by point counting. RESULTS At all time points studied beyond time 0, there were significant increases in interstitial fractional area, collagen III staining, MF, and T-cell staining in patients with chronic rejection compared with the controls. Staining for alpha-smooth muscle actin increased with time in conjunction with worsening fibrosis and collagen deposition. CONCLUSIONS In this study, MF were a major component of the interstitial infiltrate of the 10 patients with chronic transplant rejection. Abnormal persistence of these cells in the interstitium is one of the events that contributes to pathologic scarring of the kidney.

Myofibroblasts and arteriolar sclerosis in human diabetic nephropathy

We examined the biopsy specimens of 62 patients with diabetic nephropathy to establish whether the myofibroblast (MF) has a role in progressive interstitial fibrosis and to ascertain whether a relationship existed between MF activity and severity of arteriolosclerosis. MF were identified by morphology and alpha smooth muscle actin (alpha SMA) immunostaining. Analysis of vascular injury was performed by counting the number of interstitial arterioles after staining endothelial cells with von Willebrand factor (VWF) antibody. Arteriosclerosis was quantified by using a computer-aided image analyzer to measure the arteriolar wall surface and total arteriolar surface area, and the ratio of wall to total surface area was expressed as the index of arteriosclerosis (IA). Fractional area of interstitium (IFA), alpha SMA, and collagen III (Coll III) were quantitated by point counting. Results were related to structural and functional parameters using rank correlation coefficients. There was a strong correlation between IFA and Coll III staining (r = 0.83; P < 0.001). The alpha SMA staining correlated with IFA (r = 0.56; P < 0.001) and Coll III (r = 0.47; P < 0.001), and there were significant correlations between alpha SMA and total urinary protein (r = 0.47; P < 0.001), renal function (plasma creatinine) at time of biopsy (r = 0.51; P < 0.001), and the percent change in plasma creatinine after 4 years (delta Cr) (r = 0.37; P = 0.01). The IA correlated significantly with Coll III (r = 0.29; P = 0.02), glomerular filtration rate (GFR) (r = 0.39; P = 0.008), and creatinine (r = 0.33; P = 0.01), but no correlation was observed between alpha SMA and IA (r = 0.16; P = 0.23) or IA and delta Cr (r = -0.04; P = 0.6). Strong correlations could be shown between arteriolar density, IFA (r = 0.75; P < 0.001), alpha SMA (r = -0.36; P = 0.034), and Coll III (r = -0.66; P < 0.0001). The MF appears to have a significant role in the progression of diabetic nephropathy. Ischemia secondary to arteriosclerosis may contribute to interstitial fibrosis through fibroblast modulation into MF.

Pentoxifylline Reduces in vitro Renal Myofibroblast Proliferation and Collagen Secretion

Interstitial myofibroblasts (MF) are cells with features of both smooth muscle cells and fibroblasts. They have been universally recognized in situations of tubulointerstitial injury, where their presence has been shown to be a marker of disease progression. The objective of this study was to determine if functions of MF relevant to fibrogenesis can be modified in vitro by the phosphodiesterase inhibitor pentoxifylline (PTX). MF were obtained from sub-culture of normal rat kidney explant outgrowths maintained in DMEM + 20% fetal calf serum (FCS), supplemented with antibiotics. Cells were characterized on the basis of growth characteristics and immunohistochemistry. MF constituted >95% of cells at passage 3. Cell culture media was supplemented with the potential antagonist PTX alone (0, 1, 10, 100 μg/ml) and in combination with TGFβ1 (5 ng/ml). Population kinetics, proliferation and collagen production were determined from cell growth, [3H]thymidine incorporation and [3H]proline incorporation in collagenous proteins, respectively. Both serum-stimulated population growth and proliferation were reduced in a linear fashion by 1, 10 and 100 μg/ml PTX (all p < 0.05 versus 0 μg/ml). Effect of PTX on cell population growth was however reversible when PTX was removed. Basal collagen secretion was decreased by PTX at 10 and 100 μg/ml (p < 0.05 versus 0 μg/ml), although cell layer collagen remained unchanged. Collagen production (secreted and cell layer) was augmented by 5 ng/ml TGFβ1. These effects on collagen production were partially reduced when 100 μg/ml PTX was added. The authors conclude that myofibroblast function can be altered with agonists/antagonists. Attempts to down-regulate fibrogenic functions of MF may therefore offer a valuable therapeutic strategy.

A case of craniomandibular dermatodysostosis associated with focal glomerulosclerosis

This paper reports an isolated case of the exceedingly rare cutaneo-skeletal condition craniomandibular dermatodysostosis, in which focal glomerular sclerosis and end-stage renal failure developed and renal transplantation was required.

Renal Myofibroblasts Contract Collagen I Matrix Lattices in vitro

Myofibroblasts, cells with both fibroblastic and smooth muscle cell features, have been implicated in renal scarring. In addition to synthetic properties, contractile features and integrin expression may allow myofibroblasts to rearrange and contract interstitial collagenous proteins. Myofibroblasts from normal rat kidneys were grown in cell-populated collagen lattices to measure cell generated contraction. Following detachment of cell populated collagen lattices, myofibroblasts progressively contracted collagen lattices, reducing lattice diameter by 42% at 24 h. Alignment of myofibroblasts, rearrangement of fibrils and β1 integrin expression were observed within lattices. We postulate that interstitial myofibroblasts contribute to renal scarring through manipulation of collagenous proteins.

Hyaluronan and Rat Renal Fibroblasts: In vitro Studies

Hyaluronic acid (HA) is a ubiquitous component of extracellular matrix. After tissue injury, HA appears in greater abundance during the inflammatory response and the phase of clearance of cell and matrix debris, before collagen production and matrix degradation. The aim of this study was to examine whether normal rat renal fibroblasts were capable of HA synthesis and to determine the effect of HA on in vitro collagen production in a series of normal rat cortical fibroblast cultures. Fibroblast cultures from both renal cortex and medulla were established from adult Sprague-Dawley rats. HA synthesis was measured by radioimmunoassay, and incorporation of 3H-proline into collagen was used to determine collagen synthesis. Fibroblasts were defined on the basis of morphology and alpha smooth muscle actin immunohistochemistry. HA synthesis was measured in both renal cortical and medullary fibroblasts at passage 3 for both 24 and 48 h in 5 animals and expressed as a fraction of protein content. HA was synthesized by both cortical and medullary fibroblasts; however, cortical fibroblasts produced less HA than medullary fibroblasts at both 24 h (p = 0.05) and 48 h (p = 0.02). In normal cortical fibroblasts, exogenous HA suppressed overall total (cell and media) collagen production after a 22-hour labelling period (p = 0.002 compared to controls). Decreased collagen production was also found individually in cell (p = 0.02) and media fractions (p = 0.01). Both cortical and medullary fibroblasts are capable of synthesizing HA in vitro. Furthermore, the findings in this study suggest that HA may be an important mediator in reducing renal cortical fibroblast collagen production and may play an important role in limiting renal interstitial scarring.

Lymphoproliferative disorder post renal transplantation: Recent experience at a single centre

Summary: Post‐transplant lymphoproliferative disorder was diagnosed in six renal transplant recipients at the Royal Melbourne Hospital over a 5 year period to December 1994. This constituted a detection rate of 2.2%. All patients were treated with cyclosporine, azathioprine, prednisolone and orthoclone (OKT3). the median time of onset was 2 months (range 0.3 months‐3 years) after transplant. Two patients who ultimately died presented with the diffuse form of the disease where immunoblasts massively infiltrated all organs. These tumours were monoclonal B cell lymphomas and Epstein‐Barr virus (EBV) reactivation could be demonstrated. One patient developed a polyclonal B cell tumour with primary EBV infection and the remaining 3 patients tresented with T cell polyclonal proliferations and were EBV negative. No cytomegalovirus (CMV) infections, primary or reactionary were observed. Therapy in all cases consisted of reducing or ceasing immunosuppressive treatment and in three patients ganciclovir was used. Four polyclonal tumours responded to the treatment measures.

A Randomized, Placebo-Controlled Trial of Pentoxifylline On Erythropoiesis Stimulating Agent Resistance in Anaemic Patients with Chronic Kidney Disease - the Hero Trial

Aims: To identify the indications for fistulograms and determine correlation between indication and radiological findings. Background: Dialysis access stenosis is the most common cause of access dysfunction. Clinical monitoring or vascular access surveillance abnormalities prompt a fistulogram. At our institution, fistulogram is primarily used to confirm stenosis. Methods: A retrospective observational study was conducted on 245 fistulograms performed at our institution over a two year period from January 2012 to December 2013. The indication for referral, fistulogram findings, type of fistula and demographic data were obtained. Results: Total of 75.5% (185 of 245) fistulograms performed confirmed stenosis. The most frequent clinical indication was high venous pressures – 18.4% (45 of 245) and the most common surveillance indication was abnormal access flow (Transonic®) – 17.1% (42 of 245). The average age was 57 years, with 35.9% Aboriginal and 28.2% Torres Straight Islander ethnicity. The most common type of vascular access was radiocephalic fistula (49.8%) followed by brachiocephalic fistula (43.3%). Further analysis of variables, using bivariate logistic regression analysis, failed to reveal any significant correlation between indications for referral and finding of stenosis. However, increased venous pressure tends to be associated with stenosis (Odds ratio 2.0, 95% CI = 0.84–4.7, P = 0.12). Both venous hypertension (Odds ratio 0.10, 95% CI = 0.011–1.0, P = 0.052) and development of collaterals (Odds ratio 0.077, 95% CI = 0.0084–0.70, P = 0.023) were associated with negative fistulograms. Conclusions: At our institution, the majority of fistulograms demonstrated access stenosis, based on established referral indications. Both venous hypertension and development of collaterals as referral indications were associated with less likelihood of finding vascular access stenosis in this cohort.Aim: To examine the value of neutrophil-lymphocyte ratio (NLR) as a marker of inflammation and predictor of all-cause mortality in patients with end-stage kidney disease (ESKD). Background: NLR is a marker of systemic inflammation that has been shown to predict mortality in patients with coronary and peripheral vascular disease. In contrast to albumin, NLR is unlikely to be affected by nutritional status. Its prognostic value in ESKD patients is unclear. Methods: We retrospectively reviewed all consecutive haemodialysis patients between January 2007 and December 2011 at a single centre. We recorded patients full blood count and other biochemistry three months after commencement of dialysis. Correlations between NLR and other metabolic and inflammatory markers were evaluated using Pearsons r coefficient. The prognostic value of NLR was tested using Kaplan Meier, univariate and multivariate Cox analyses adjusted for Australian and New Zealand Dialysis and Transplant Registry data. Results: 140 haemodialysis patients were included with median follow-up of 36 months and overall mortality of 41% (58 patients). Neutrophil-lymphocyte ratio was positively correlated with C-reactive protein (r = 0.48, P < 0.01) and negatively correlated with haemoglobin (r = -0.32, P < 0.01) and albumin (r = -0.40, P < 0.01). In Kaplan Meier analysis, NLR (stratified into tertiles) was associated with all-cause mortality (log-rank, P = 0.01). In multivariate Cox analysis, NLR was independently associated with all-cause mortality (HR 1.09, 95% CI 1.01– 1.17 P = 0.03). Other predictors of all-cause mortality in multivariate analysis were low albumin (HR 0.89, 95% CI 0.89–0.94 P < 0.01) and history of cardiovascular disease (HR 2.29, 95% CI 1.25–4.48 P = 0.01). Conclusions: Neutrophil-lymphocyte ratio correlates with other markers of systemic inflammation in ESKD patients and is associated with poor survival. The extent to which other confounding factors affect these results is unknown.Aim: To determine whether: (1) systemic expression of endogenous secretory RAGE (esRAGE) after the induction of diabetes can prevent the development of diabetic nephropathy (DN) in mice with streptozotocin-induced diabetes; (2) the protective effects of esRAGE are attributable to interruption of signaling via the HMGB1receptors (TLR2, TLR4 and RAGE). Background: We have reported that systemic overexpression of esRAGE attenuates diabetic kidney injury. esRAGE is a soluble decoy receptor that can competitively bind ligands for TLRs/RAGE, including HMGB1. Here we test the hypothesis that the protective effects of esRAGE are attributable to interruption of signaling via the HMGB1 receptors (TLR2, TLR4 and RAGE). Methods: DN was induced in WT, TLR4−/− and TLR2−/− mice by intraperitoneal injection of streptozotocin. At 2 weeks after streptozotocin injection, mice received an IP injection of 5 × 1011 vector genome copies (VGC) rAAV encoding either esRAGE or HSA, or saline-control. Samples were collected at week 12 post-induction of diabetes. Results: Diabetic mice that received rAAV-esRAGE, rAAV-HSA or saline developed equivalent degrees of hyperglycaemia. Diabetic WT-mice given rAAVHSA or saline developed significant albuminuria versus non-diabetic WT-mice (ACR309 ± 213 & 313 ± 215 versus 55 ± 10, P < 0.05–0.01), whilst rAAVesRAGE treated-diabetic-mice were protected (118 ± 42, P < 0.05). WT diabetic-mice developed histological damage including glomerular hypertrophy, podocyte injury, macrophage accumulation and interstitial fibrosis. These changes were significantly attenuated in diabetic mice given rAAV-esRAGE versus rAAV-HSA (P < 0.05–0.01).While both TLR2−/− mice and TLR4−/−mice were partially protected against diabetic nephropathy, esRAGE treatment provided additional protection to TLR2−/− mice, but not TLR4−/− mice. A further study of esRAGE treatment in RAGE−/− mice is underway. Conclusions: High-level expression of serum esRAGE after the induction of diabetes provided partial protection against the development of DN in mice with streptozotocin-induced diabetes, which may operate through the TLR4 pathway.