Translating knowledge of the human genome into clinical practice in nephrology dialysis and transplantation: the renal genome network (ReGeNet).
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Animals↗
Biomedical subjects
Paul E C Brenchley
Publications and source records attributed to Paul E C Brenchley.
Activation of transforming growth factor-beta1 and early atherosclerosis in systemic lupus erythematosus.
The efficiency of activating latent transforming growth factor (TGF)-beta1 in systemic lupus erythematosus (SLE) may control the balance between inflammation and fibrosis, modulating the disease phenotype. To test this hypothesis we studied the ability to activate TGF-beta1 in SLE patients and control individuals within the context of inflammatory disease activity, cumulative organ damage and early atherosclerosis. An Activation Index (AI) for TGF-beta1 was determined for 32 patients with SLE and 33 age-matched and sex-matched control individuals by quantifying the increase in active TGF-beta1 under controlled standard conditions. Apoptosis in peripheral blood mononuclear cells was determined by fluorescence-activated cell sorting. Carotid artery intima-media thickness was measured using standard Doppler ultrasound. These measures were compared between patients and control individuals. In an analysis conducted in patients, we assessed the associations of these measures with SLE phenotype, including early atherosclerosis. Both intima-media thickness and TGF-beta1 AI for SLE patients were within the normal range. There was a significant inverse association between TGF-beta1 AI and levels of apoptosis in peripheral blood mononuclear cells after 24 hours in culture for both SLE patients and control individuals. Only in SLE patients was there a significant negative correlation between TGF-beta1 AI and low-density lipoprotein cholesterol (r = -0.404; P = 0.022) and between TGF-beta1 AI and carotid artery intima-media thickness (r = -0.587; P = 0.0004). A low AI was associated with irreversible damage (SLICC [Systemic Lupus International Collaborating Clinics] Damage Index > or = 1) and was inversely correlated with disease duration. Intima-media thickness was significantly linked to total cholesterol (r = 0.371; P = 0.037). To conclude, in SLE low normal TGF-beta1 activation was linked with increased lymphocyte apoptosis, irreversible organ damage, disease duration, calculated low-density lipoprotein levels and increased carotid IMT, and may contribute to the development of early atherosclerosis.
Apoptosis↗
Interaction between genetic control of vascular endothelial growth factor production and retinoid responsiveness in psoriasis.
Vascular endothelial growth factor (VEGF) promotes angiogenesis, and elevated levels are found in plaques of psoriasis. Two VEGF polymorphisms, +405 and -460, are associated with early-onset psoriasis and are close to the functional activator protein-1 site (+419) through which retinoids, an established systemic therapy for psoriasis, can block production of VEGF. We report that peripheral blood mononuclear cells (PBMCs) and epidermal keratinocytes (KC) from patients with psoriasis demonstrate differential, genotype-dependent, regulation of VEGF. For PBMCs, VEGF genotype distinguishes two groups of patients with psoriasis - "high and low VEGF producers" (P < 0.001). In contrast, KC production of VEGF is not genotype dependent. However, the effects of all-trans retinoic acid (RA) on cellular expression of VEGF are determined by both cell type and genotype. RA inhibits KC production of VEGF in a genotype-dependent manner (P < 0.005) whereas RA stimulates PBMCs production irrespective of VEGF genotype (P < 0.001). We also report that the -460 VEGF polymorphism appears to have a clinical pharmacogenetic role in predicting response or non-response of psoriasis to acitretin (P = 0.01). In future, determination of VEGF gene polymorphisms and thus individual patient VEGF "signatures" may be used as a prognostic factor for psoriasis susceptibility/severity and as a means for optimizing treatment response.
Acitretin↗
VEGF -460 genotype plays an important role in progression to chronic kidney disease stage 5.
BACKGROUND: Changes in renal vasculature, with vascular and interstitial fibrosis, are hallmarks of progression to chronic kidney disease (CKD) stage 5. Vascular endothelial growth factor (VEGF) is a potent angiogenic and vascular permeability factor. Transforming growth factor-beta1 (TGF-beta1) plays a critical role in promoting extracellular matrix (ECM) deposition and fibrosis. This study investigates whether genetic polymorphisms of VEGF or TGF-beta1 are associated with (i) progressive decline in renal function in patients with glomerular disorders (cohort 1) and (ii) predisposition to CKD stage 5 in a separate group of renal transplant recipients with various primary diseases (cohort 2). METHODS: Two patient groups were studied. Cohort 1 comprised 91 patients with biopsy-proven glomerular disease who were followed-up for 5 years before categorization as either non-progressors (with stable serum creatinine or < or =30% increase over 5 years, n = 39) or progressors (requiring dialysis, transplantation or whose serum creatinine increased by >30% over 5 years, n = 52). Cohort 2 comprised 107 patients with various primary renal diseases, who had reached CKD stage 5 and undergone renal transplantation at the time of study. All patients were genotyped for the VEGF polymorphisms at positions -460 (C/T) and +405 (G/C). Linkage disequilibrium (LD) was established using EHplus. SNPHAP was used to estimate haplotype frequency and to infer haplotypes to all patients. Cohort 1 patients were genotyped for the TGF-beta1 polymorphisms at positions -800, -509, codons 10 and 25. Genotyping was performed by polymerase chain reaction-restriction length polymorphism (PCR-RFLP). RESULTS: In cohort 1, there was a significant increase in frequency of the -460 VEGF CC genotype 30.8 vs 5.1%, P = 0.008; odds ratio (OR), CC vs TT 10.67, 95% confidence interval (CI), 1.94-58.72 and C allele 56.7 vs 37.2%, P = 0.009; OR 2.22, 95% CI, 1.21-4.04, in the progressor patients when compared with the non-progressors. In cohort 2, there was a significant increase in the VEGF -460 CC genotype when compared with healthy volunteers 37 vs 20.8%, P = 0.011; OR CC vs TT 1.59, 95% CI, 0.72-3.51. The -460 and +405 polymorphisms were in LD P < 0.00007. There were significant differences in diplotype (haplotype pair) frequencies in cohort 1 and 2, P = 0.018, which confirmed the importance of the -460C allele. There were no associations between the VEGF +405 or TGF-beta1 polymorphisms and progressive renal disease. CONCLUSION: In this study, we have demonstrated an association between the VEGF -460 polymorphism and progression to CKD stage 5. The function of this polymorphism remains unclear although previous evidence suggests that promoter constructs containing this single nucleotide polymorphism (SNP) have been associated with increased activity. Clearly there is a role for TGF-beta1 in chronic kidney disease. However, this study found no associations with four TGF-beta1 polymorphisms in this cohort.
Biopsy↗
Heparanase activity is dysregulated in children with steroid-sensitive nephrotic syndrome.
BACKGROUND: Immune cells express heparanase, an endoglycosidase, able to degrade heparan sulfate glycosaminoglycan (HSGAG) in the glomerular capillary wall (GCW) and potentially induce proteinuria. The aim of this study was to determine whether dysregulated heparanase expression is associated with the heavy proteinuria of childhood steroid-sensitive nephrotic syndrome (SSNS). METHODS: Plasma and urinary heparanase activity and peripheral blood mononuclear cell (PBMC) mRNA heparanase levels [real-time polymerase chain reaction (PCR)] were measured in children with SSNS in relapse and remission. Plasma and urinary heparanase activity was determined in adult patients with nephrotic syndrome and in age- and gender-matched controls. RESULTS: Plasma heparanase activity was reduced in SSNS with relapse (811.2 units) compared to remission (1147.96 units) (P= 0.003) and control subjects (1390.51 units) (P < 0.001). In adult nephrotic syndrome, plasma heparanase activity was significantly lower in patients compared to controls. However, there was no difference between remission and relapse states. In children, urinary heparanase activity/urinary creatinine ratio was highest in SSNS relapse (14.26 units/mg) compared with remission (7.43 units/mg) (P= 0.016) and controls (2.29) (P < 0.001). However, PBMC heparanase mRNA expression was not different between these three groups. In adult nephrotic syndrome, urinary heparanase activity/urinary creatinine levels were lower in both remission and relapse compared to controls and there was no difference between remission and relapse states. CONCLUSION: In childhood SSNS, there is a qualitative and quantitative difference in urinary heparanase activity expression that is not paralleled in adult nephrotic syndrome. These data suggest that dysregulated heparanase expression may play a significant role in the pathogenesis of SSNS, possibly through an abnormality in post-translational control of latent heparanase activation.
Adult↗
Single-center experience of encapsulating peritoneal sclerosis in patients on peritoneal dialysis for end-stage renal failure.
BACKGROUND: Encapsulating peritoneal sclerosis (EPS) is a rare but serious complication in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) or automated peritoneal dialysis (APD). It is characterized by a progressive, intra-abdominal, inflammatory process resulting in sheets of fibrous tissue that cover, bind, and constrict the viscera, thereby compromising the motility and function of the bowel. Although recent therapeutic approaches have been reported with variable success, the ability to detect reliably at an early stage patients at risk for EPS would be beneficial and allow treatment standardization. The aim of this study was to evaluate the clinical features of EPS and identify possible risk factors for its development in CAPD and APD patients. METHODS: This was a review of all cases of EPS in a single center over the last 5 years. RESULTS: There were 810 CAPD and APD patients, managed in our program over this period. We identified 27 cases of EPS, giving an overall of 3.3% in this population. The mean duration of CAPD before diagnosis of EPS was 72.6 +/- 39.7 months (range 16-172). Sixteen cases required surgical treatment and were classified as severe; others were treated conservatively (mild to moderate group). Ten patients received tamoxifen treatment with apparent benefit. The overall mortality rate was 29.6%. Eight patients from the severe group and the entire moderate group survived on hemodialysis or transplantation at 48.71 and 27.63 months follow-up, respectively. Peritonitis rates were not different between the 2 groups and peritoneal history was unremarkable compared to overall peritonitis rates in the unit. Data on small solute transport were not available in all patients in this retrospective analysis. CONCLUSION: EPS is a serious, life-threatening complication of CAPD. Most cases had PD duration of more than 4 years. Careful monitoring by CT scans of the peritoneal membrane in patients beyond 5 years, and early catheter removal in patients with peritoneal thickening should be considered for long-term CAPD patients. Treatment with tamoxifen may be of benefit in these patients.
Adult↗
Hypoxia increases heparanase-dependent tumor cell invasion, which can be inhibited by antiheparanase antibodies.
The beta-endoglucuronidase heparanase plays an important role in tumor invasion, a process that is significantly enhanced by hypoxia. We have used a strategy of stable transfection with antisense to derive ovarian carcinoma cell lines that express different levels of heparanase and used these to demonstrate that invasion correlates with heparanase activity. Secreted heparanase activity was increased by reduction, hypoxia, and growth of cells under reduced oxygen (1%) augmented heparanase activity and invasion, both of which are inhibited by treatment with antiheparanase antibodies. This is the first demonstration that heparanase activity may be regulated by microenvironmental redox conditions, which influence invasion, and that invasion can be blocked with specific heparanase-neutralizing antibodies.
Antibodies↗
Single-nucleotide polymorphisms of vascular endothelial growth factor in psoriasis of early onset.
Vascular endothelial growth factor (VEGF)--a stimulus of angiogenesis--is produced by epidermal keratinocytes, and elevated levels have been found in plaques of psoriasis. Polymorphisms in the VEGF gene regulate production of VEGF. We postulated that patients with psoriasis may have altered systemic expression of VEGF consequent upon programming at the genomic level. We investigated the genetic basis of VEGF expression in patients with type 1 (onset before age 40 y) chronic plaque psoriasis compared to healthy controls and also measured plasma levels of VEGF and its receptors flt-1 and KDR. Patients with severe disease, and those with onset of psoriasis between the ages of 20 and 40 y showed significantly increased frequency of the +405 CC genotype (p=0.04 and p=0.02) and the C allele (p=0.03 and p=0.02), respectively, compared to healthy controls. Plasma levels of VEGF and flt-1 were significantly detectable in patients with psoriasis compared with controls (p<0.001); by contrast, mean plasma levels of KDR in psoriatic patients were comparable with controls. These results suggest that alterations in the biology of VEGF may be involved in the pathogenesis of psoriasis. VEGF, flt-1, and KDR could provide attractive targets for future psoriasis therapy.
Adolescent↗
Cytokines and cell adhesion molecules in the inflammatory response during acute pyelonephritis.
Urinary tract infection is a common bacterial infection of childhood. Renal parenchymal scarring, a recognised complication of urinary tract infection, is responsible for up to 24% of children entering end-stage renal failure. Why acute inflammation results in renal scarring in some children whilst in others complete resolution occurs without scarring is at present poorly understood. This article reviews the role of the cytokines, adhesion molecules and growth factors in the inflammatory response during acute pyelonephritis and renal parenchymal scarring. We hypothesize that inter-individual variability in cellular response may in part be responsible for this variable clinical outcome.
Acute Disease↗
A multiwell format assay for heparanase.
This assay employs a biotinylated heparan sulfate glycosaminoglycan (HSGAG) substrate that is covalently linked to the surface of 96-well immunoassay plates. The ratio of biotin:HSGAG and the coating concentration of substrate bound to the wells have been optimized and allow removal of biotin HSGAG within 60 min of incubation at 37 degrees C in assay buffer with a standard dilution of bacterial heparitinase or platelet heparanase. Loss of biotin signal from the well surface is detected on incubation with peroxidase-streptavidin followed by color development using 3,3',5,5'-tetramethylbenzidine as the peroxidase substrate. The new assay allows specific detection of heparanase activity in multiple samples in a total time of 3 h including a 1-h substrate digestion step and is a significant improvement with regard to sensitivity, specificity, and ease of handling of multiple samples compared to other described assays. Heparanase specifically degrades the biotinylated HSGAG substrate, when used with an optimized assay buffer. A range of enzymes including collagenase, trypsin, plasmin, pepsin, chondroitinases, hyaluronidase, and neuraminidase show no effect on the substrate under optimized assay conditions. The covalent linkage of the substrate to the well prevents leaching of substrate and allows preparation and long-term storage of substrate-coated plates. The assay can be used to detect heparanase levels in clinical samples and cell culture supernatants and is ideal as a screening method for antagonists of enzyme activity.
Blood Platelets↗
Vascular permeability factors in steroid-sensitive nephrotic syndrome and focal segmental glomerulosclerosis.
The concept that some forms of proteinuria may be induced by the action of circulating systemic permeability factors on the glomerular capillary wall is intriguing. First proposed in the 1970s in the context of steroid-sensitive nephrotic syndrome, the immune system was proposed as a source of such a vascular permeability factor (VPF). More recently, some forms of focal segmental glomerular sclerosis appear to be associated with another type of systemic factor. This paper reviews the evidence for such factors and compares the properties of a number of candidate VPFs.
Glomerulosclerosis, Focal Segmental↗
Role of TGF-beta1 in renal parenchymal scarring following childhood urinary tract infection.
BACKGROUND: Significant variability exists in the outcome of renal parenchymal inflammation following urinary tract infection (UTI) in childhood as some children experience renal parenchymal scarring (RPS) while others do not scar. Since TGF-beta1 is pro-fibrotic, we examined the role of this cytokine in RPS following UTI. METHODS: Five polymorphisms of the TGF-beta1 gene were investigated as well as the relationship between these polymorphisms and TGF-beta1 production by peripheral blood mononuclear cells (PBMC) in vitro. DNA was isolated from 91 children shown to have developed RPS, 43 children with no evidence of scarring (NS) following UTI, and 171 healthy controls. Genotyping was performed by restriction fragment length polymorphism (RFLP). PBMC were isolated from a subgroup of 24 patients from the total population. Cells were stimulated with LPS + PMA + PHA and then TGF-beta1 production was determined by ELISA. RESULTS: Comparing the NS with the RPS group, there was an increase in the -800 GA genotypes (18.6 vs. 7.4%, P=0.05; chi2) and the Leu10-->Pro CT (62.8 vs. 41.5%, P=0.021), and a decrease in the -509 TT genotype (0.0 vs. 8.5%, P=0.049). PBMC TGF-beta1 production was higher in those patients with the -800 GG compared to those with a GA genotype stimulation index [stimulated/unstimulated TGF-beta1 levels were 1.54 interquartile range (IQR) 1.42 to 1.75 vs. 1.19, IQR 0.94 to 1.51, P=0.031]. CONCLUSIONS: There is an association between the TGF-beta1 -800 GA, -509 TT and Leu10-->Pro CT genotypes and the presence or absence of RPS. The low TGF-beta1 producer status of the -800 GA genotype may protect against the development of a pro-fibrotic pathology.
Child↗
An international encapsulating peritoneal sclerosis registry and DNA bank: why we need one now.
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DNA↗
Paraoxonase gene polymorphism and serum activity in progressive IgA nephropathy.
BACKGROUND: HDL-associated paraoxonase (PON1) reduces oxidation of lipids in LDL, and activity is inversely related to coronary heart disease risk with a beneficial effect on the development of atherosclerosis. Risk factors associated with atherosclerosis, such as hypertension, dyslipidemia and smoking, also promote the progression of chronic glomerulonephritides which may therefore be associated with perturbations in PON1 activity. METHODS: We performed a genetic association study in patients with IgA nephropathy (IgAN) (n=115) compared with control subjects (n=118). The aim was to test whether polymorphisms in the PON1 coding region (Q192R and L55M) and its promoter (-108C/T and -162A/G) are associated with either IgAN or with the progression. We measured serum paraoxonase activity in 60 out of 115 patients. All patients had been followed up for more than 4 years. RESULTS: There were no differences in the genotype frequency at 3 of the polymorphic sites (Q192R, L55M and -108C/T) between the patients and controls. However, the frequency distribution at -162 position (A/G) was significantly diffe-rent in IgAN (p=0.028, chi-square test) with a higher frequency of the heterozygote (0.017, Fisher exact test [FE]; odds ratio [OR] = 1.99; 95% confidence interval [95% CI], 1.14-3.47). Although there were no differences in the genotype frequency at 3 of the polymorphic sites (Q192R, L55M and -162C/T) between the patients with progressive IgA and the nonprogressive patients, we found that the frequency of the C allele for the -108C/T polymorphism was elevated in those patients with nonprogressive disease (n=85) compared with those with progressive disease (n=30) (61% vs. 47%; p=0.070, FE; OR=1.75, 95% CI, 0.97-3.18). Furthermore, PON1 activity was significantly higher in nonprogressive patients compared with progressors (206 +/- 71 vs. 136 +/- 48; p<0.001), and activity significantly correlated with 1/serum creatinine (SCr) (p<0.001; r=0.38). CONCLUSIONS: The results of this study suggest that in IgAN, lower PON1 activity may be associated with the deterioration of kidney function. This could be due to variable expression of the PON1 gene, or a functional effect of the gene product.
Adult↗