Eugenios Daphnis

Incidence, Clinical, Microbiological Features and Outcome of Bloodstream Infections in Patients Undergoing Hemodialysis

Objectives: Infection is a common cause of death among hemodialysis patients. The study investigated incidence, risk factors, clinical features and outcome of bloodstream infections (BSIs) in haemodialysis patients. Methods: The records of haemodialysis patients from 1999 to 2005 were reviewed. Risk factors were investigated by multivariate analysis. Results: There were identified 148 bacteremic episodes, in 102 patients. The BSI rate was 0.52 per 1000 patient-days. Of the 148 episodes, 34 occurred in patients with permanent fistulae (0.18/1000 patient-days); 19 in patients with grafts (0.39/1000 patient-days); 28 in patients with permanent tunneled central catheters (1.03/1000 patient-days); and 67 in those with temporary-catheter (3.18/1000 patient-days). With fistula as reference, the BSI ratio was 1.84 with arteriovenous graft (P=.029), 4.85 with permanent central venous catheter (P<.001), and 14.88 with temporary catheter (P <.001). Catheter related were 41 episodes (28%). Gram positive organism were responsible for 96 episodes (65%), with S. aureus ( 55%) the most frequent, followed by S. epidermidis (26%) and Gram-negative for 36 (23%), with E. coli (39%) the most frequent. Infection was polymicrobial in 14 (9.5%). Diabetes (p<0.001), low serum albumin (p=0.040) and low hemoglobin (p<0.001) were significant risk factors. During hospitalization 18 patients (18%) died. Septic shock (p<0.001) and polymicrobial infection (p=0.041) were associated with in-hospital mortality. Conclusion: The risk of BSI in patients undergoing hemodialysis is related to the catheter type and vascular access. Septic shock and polymicrobial infection predispose to unfavourable outcome.

Peritoneal dialysis-associated peritonitis: clinical features and predictors of outcome

OBJECTIVES The objective of this study was to identify the epidemiological, clinical, and microbiological factors affecting the outcome of peritoneal dialysis (PD)-associated peritonitis. METHODS All patients with PD-associated peritonitis, cared for at the University Hospital of Heraklion from 1990 to 2007, were retrospectively studied. RESULTS A total of 247 episodes of PD-associated peritonitis occurring in 82 patients were evaluated. The median age of patients was 68 years (range 10-92 years); 51 (62%) were males. There were 104 episodes (42%) of Gram-positive peritonitis, 46 (19%) of Gram-negative peritonitis, 13 (5%) of polymicrobial peritonitis, and 11 (4%) of fungal peritonitis. There were 64 (26%) complicated episodes. The latter included 22 (8.9%) relapses, 13 (5.3%) repeated episodes, 18 (7.3%) catheter removals, and 11 (4.5%) deaths. In multivariate analysis, the presence of a purulent exit-site infection (p<0.001), peritoneal dialysis effluent cell count >100 x 10(6)/l for more than 5 days (p<0.001), use of antimicrobials during the preceding 3 months (p<0.05), and low serum total protein level on admission (p<0.05) were independent predictors of a complicated course. CONCLUSIONS Exit-site infection, more than 5 days with a peritoneal dialysis effluent cell count >100 x 10(6)/l, prior use of antimicrobials, and low serum total protein level are potential predictors of complicated PD-associated peritonitis and may distinguish high-risk cases.

X-linked Alport syndrome in Hellenic families: phenotypic heterogeneity and mutations near interruptions of the collagen domain in COL4A5.

Demosthenous P, Voskarides K, Stylianou K, Hadjigavriel M, Arsali M, Patsias C, Georgaki E, Zirogiannis P, Stavrou C, Daphnis E, Pierides A, Deltas C, Hellenic Nephrogenetics Research Consortium. X‐linked Alport syndrome in Hellenic families: Phenotypic heterogeneity and mutations near interruptions of the collagen domain in COL4A5.

Crescentic glomerulonephritis associated with vascular endothelial growth factor (VEGF) inhibitor and bisphosphonate administration

Bevacizumab, a vascular endothelial growth factor (VEGF) inhibitor, has been widely used in a variety of malignancies offering substantial clinical benefit. Hypertension and proteinuria are the most commonly reported manifestations of bevacizumab-related nephrotoxicity with the risk increasing along with the dose and with the concomitant use of bisphosphonates. We describe the first case of a patient with small-cell lung cancer who developed diffuse extracapillary necrotizing crescentic glomerulonephritis, temporarily necessitating haemodialysis, following administration of bevacizumab and zolendronate. Renal function improved without any specific treatment and the patient remained off dialysis after withdrawal of bevacizumab-zolendronate. Special caution is required when VEGF inhibitors are combined with bisphosphonates. Such a combination can cause crescentic necrotizing glomerular lesions. Withdrawal of the offending medications may be adequate for the alleviation of this severe glomerulonephritis.

Losartan Affects Glomerular AKT and mTOR Phosphorylation in an Experimental Model of Type 1 Diabetic Nephropathy

The AKT-mTOR pathway is activated in diabetic nephropathy. Renin-angiotensin system modulators exert beneficial effects on the diabetic kidney. We explored the action of losartan on AKT-mTOR phosphorylation in glomeruli and podocytes. Diabetes mellitus was induced to Sprague-Dawley rats by streptozotocin. Five months later, the rats were commenced on losartan and euthanized 2 months later. Kidneys were processed for immunofluorescence studies. Glomeruli were isolated for Western blot analysis. Diabetes increased activated forms of AKT and mTOR both in glomeruli and podocytes. In diabetic rats, losartan decreased phosphorylated/activated forms of AKT (Thr308) and mTOR (Ser2448) in glomeruli but decreased only activated mTOR in podocytes. However, in both glomeruli and podocytes of healthy animals, an inverse pattern was evident. In conclusion, a new body of evidence indicates the differential activation of AKT-mTOR in glomeruli and podocytes of healthy and diabetic animals in response to losartan.

A functional variant in NEPH3 gene confers high risk of renal failure in primary hematuric glomerulopathies. Evidence for predisposition to microalbuminuria in the general population

Background Recent data emphasize that thin basement membrane nephropathy (TBMN) should not be viewed as a form of benign familial hematuria since chronic renal failure (CRF) and even end-stage renal disease (ESRD), is a possible development for a subset of patients on long-term follow-up, through the onset of focal and segmental glomerulosclerosis (FSGS). We hypothesize that genetic modifiers may explain this variability of symptoms. Methods We looked in silico for potentially deleterious functional SNPs, using very strict criteria, in all the genes significantly expressed in the slit diaphragm (SD). Two variants were genotyped in a cohort of well-studied adult TBMN patients from 19 Greek-Cypriot families, with a homogeneous genetic background. Patients were categorized as “Severe” or “Mild”, based on the presence or not of proteinuria, CRF and ESRD. A larger pooled cohort (HEMATURIA) of 524 patients, including IgA nephropathy patients, was used for verification. Additionally, three large general population cohorts [Framingham Heart Study (FHS), KORAF4 and SAPHIR] were used to investigate if the NEPH3-V353M variant has any renal effect in the general population. Results and conclusions Genotyping for two high-scored variants in 103 TBMN adult patients with founder mutations who were classified as mildly or severely affected, pointed to an association with variant NEPH3-V353M (filtrin). This promising result prompted testing in the larger pooled cohort (HEMATURIA), indicating an association of the 353M variant with disease severity under the dominant model (p = 3.0x10-3, OR = 6.64 adjusting for gender/age; allelic association: p = 4.2x10-3 adjusting for patients’ kinships). Subsequently, genotyping 6,531 subjects of the Framingham Heart Study (FHS) revealed an association of the homozygous 353M/M genotype with microalbuminuria (p = 1.0x10-3). Two further general population cohorts, KORAF4 and SAPHIR confirmed the association, and a meta-analysis of all three cohorts (11,258 individuals) was highly significant (p = 1.3x10-5, OR = 7.46). Functional studies showed that Neph3 homodimerization and Neph3-Nephrin heterodimerization are disturbed by variant 353M. Additionally, 353M was associated with differential activation of the unfolded protein response pathway, when overexpressed in stressed cultured undifferentiated podocyte cells, thus attesting to its functional significance. Genetics and functional studies support a “rare variant-strong effect” role for NEPH3-V353M, by exerting a negative modifier effect on primary glomerular hematuria. Additionally, genetics studies provide evidence for a role in predisposing homozygous subjects of the general population to micro-albuminuria.

Epistatic Role of the MYH9/APOL1 Region on Familial Hematuria Genes

Familial hematuria (FH) is explained by at least four different genes (see below). About 50% of patients develop late proteinuria and chronic kidney disease (CKD). We hypothesized that MYH9/APOL1, two closely linked genes associated with CKD, may be associated with adverse progression in FH. Our study included 102 thin basement membrane nephropathy (TBMN) patients with three known COL4A3/COL4A4 mutations (cohort A), 83 CFHR5/C3 glomerulopathy patients (cohort B) with a single CFHR5 mutation and 15 Alport syndrome patients (cohort C) with two known COL4A5 mild mutations, who were categorized as “Mild” (controls) or “Severe” (cases), based on renal manifestations. E1 and S1 MYH9 haplotypes and variant rs11089788 were analyzed for association with disease phenotype. Evidence for association with “Severe” progression in CFHR5 nephropathy was found with MYH9 variant rs11089788 and was confirmed in an independent FH cohort, D (cumulative p value = 0.001, odds ratio = 3.06, recessive model). No association was found with APOL1 gene. Quantitative Real time PCR did not reveal any functional significance for the rs11089788 risk allele. Our results derive additional evidence supporting previous reports according to which MYH9 is an important gene per se, predisposing to CKD, suggesting its usefulness as a prognostic marker for young hematuric patients.

Frequent COL4 mutations in familial microhematuria accompanied by later-onset Alport nephropathy due to focal segmental glomerulosclerosis

Familial microscopic hematuria (FMH) is associated with a genetically heterogeneous group of conditions including the collagen‐IV nephropathies, the heritable C3/CFHR5 nephropathy and the glomerulopathy with fibronectin deposits. The clinical course varies widely, ranging from isolated benign familial hematuria to end‐stage renal disease (ESRD) later in life. We investigated 24 families using next generation sequencing (NGS) for 5 genes: COL4A3, COL4A4, COL4A5, CFHR5 and FN1. In 17 families (71%), we found 15 pathogenic mutations in COL4A3/A4/A5, 9 of them novel. In 5 families patients inherited classical AS with hemizygous X‐linked COL4A5 mutations. Even more patients developed later‐onset Alport‐related nephropathy having inherited heterozygous COL4A3/A4 mutations that cause thin basement membranes. Amongst 62 heterozygous or hemizygous patients, 8 (13%) reached ESRD, while 25% of patients with heterozygous COL4A3/A4 mutations, aged >50‐years, reached ESRD. In conclusion, COL4A mutations comprise a frequent cause of FMH. Heterozygous COL4A3/A4 mutations predispose to renal function impairment, supporting that thin basement membrane nephropathy is not always benign. The molecular diagnosis is essential for differentiating the X‐linked from the autosomal recessive and dominant inheritance. Finally, NGS technology is established as the gold standard for the diagnosis of FMH and associated collagen‐IV glomerulopathies, frequently averting the need for invasive renal biopsies.

The Effect of Sodium-Glucose Co-transporter-2 (SGLT-2) Inhibitors on Cardiometabolic Profile; Beyond the Hypoglycaemic Action

Type 2 diabetes mellitus (T2DM) has growing prevalence worldwide and major clinical implications, chiefly cardiovascular (CV) and renal disease burden. Sodium-glucose co-transporter (SGLT)-2 inhibitors are a new drug class in the management of T2DM with a mechanism of action independent of insulin. In addition to their hypoglycaemic effect, SGLT-2 inhibitors appear to have haemodynamic and nephroprotective effects. Studies have consistently showed a modest but significant blood pressure (BP) reduction. Metabolic benefits are also attributed to SGLT-2 inhibitors with a modest but consistent body weight decrease recorded along with improvements in lipid profile and uric acid levels. Remarkable findings of significant cardioprotective effects came from the recent EMPA-REG study with a particular focus on heart failure. In the kidney, SGLT-2 inhibitors reduce hyperfiltration, a precipitant of diabetic nephropathy.