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R Coppo

Publications and source records attributed to R Coppo.

At least 37 records · Page 2Linked to original sources
PubMed1997

Processing of IgA aggregates in a rat model of chronic liver disease.

Heavy alcohol intake and/or lipotrope-deficient diet induced hepatocellular injury and mesangial deposition of IgA and often IgG in Lewis rats. The experimental animals showing more severe urinary abnormalities and histologic damage in the glomeruli had increased levels of IgA antibodies to dietary antigens and altered intestinal permeability. Based on human studies, the prolonged circulation of IgA-containing complexes associated with the liver disease could be envisaged as important for the development of mesangial IgA deposits. In order to verify this hypothesis, four groups (G) of Lewis rats were studied: G1 received thrice a weak an intragastric infusion of 1.5 ml/100 g body wt of whiskey; G2 rats were nourished with lipotrope-deficient diet; G3 rats were given both whiskey and LD diet; G4 rats were nourished with regular chow. After 12 weeks, heat-aggregated rat monomeric IgA was labeled with 133I and intravenously injected. Three control subgroups of rats, one given whiskey, one nourished with LD diet, and one with regular chow, were injected with radiolabeled heat-aggregated rat IgG. A large field-of-view digital gamma camera, equipped with an ultra-high-resolution collimator and interfaced to a dedicated computer, was used to analyze tracer kinetics and fate. The liver was the main organ involved in clearance of both test probes. The hepatic mean transit (MTT) was 11.4 +/- 11 min in G1 (proteinuria of 6.9 +/- 1.41 mg/day and hematuria +/+2), 221 +/- 19 min in G2 (proteinuria 9.1 +/- 0.64 mg/day and hematuria +2/+3), and 230 +/- 15 min in G3 (proteinuria 9.5 +/- 0.58 mg/day and hematuria +2/+3). In each case MTT value was found to be significantly prolonged compared to G4 (85 +/- 4 min). The multiple regression analysis showed that MTT values, proteinuria, and hematuria were significantly correlated (P < 0.01). Controls had trace amount proteinuria (0.82 +/- 0.17 mg/day, significantly lower than for each study group, P < 0.08) and undetectable hematuria. Similar results were obtained in control rats injected with aggregated IgG; i.e., MTT values were more prolonged in rats given whiskey or LD diet than normally nourished rats (P < 0.01). The lipotrope-deficient diet and the chronic alcohol abuse per se seem to lead to critical changes in hepatic uptake and catabolism of both an IgA and an IgG aggregate, which could account in turn for the reported appearance of renal immunoglobulin deposits in this experimental model. Due to the comparable delay in removal of IgA and IgG probes in equally nourished animals, additional factors are likely to be involved in the prominent deposition of IgA.

Animals↗
PubMed1997

Nonenzymatically glycated albumin (Amadori adducts) enhances nitric oxide synthase activity and gene expression in endothelial cells.

Hyperglycemia is considered to induce diabetic nephropathy through nonenzymatic glycation of proteins. Since hyperfiltration is likely to be the mechanism initiating the glomerular lesions, we investigated the effects of Amadori glucose adducts in serum albumin on the production of vasoactive mediators, including nitric oxide (NO) and eicosanoids, by endothelial cells (EC). Amadori adducts of glycated albumin induced a dose-response increase in NO synthase activity of murine endothelioma cells, up to 16.4 +/- 2.1-fold increase of basal values (P < 0.0001) at concentrations of 35 mg/ml mimicking physiological serum albumin concentration, and 4.6 +/- 0.8-fold increase at 17 mg/ml (P < 0.001). The effect was still detectable with glycated albumin 1.7 mg/ml, which approaches its estimated concentration in diabetic serum (1.6 +/- 0.3-fold increase, P < 0.05) The phenomenon was reproducible in human umbilical vein endothelial cells, though to a lesser extent, and further studies on murine EC were employed. The mRNA encoding for inducible NO synthase was overexpressed in EC incubated with Amadori adducts of glycated albumin in comparison to native albumin. Glycated albumin induced increased mRNA expression and synthesis of TNF-alpha. The stimulatory effect induced by glycated albumin on NO synthase activity was almost completely inhibited by anti TNF alpha antibodies. 3H-thymidine incorporation by EC was significantly inhibited when cells were grown in presence of glycated albumin (P < 0.001), and the phenomenon was abolished by the coincubation of the NO competitive inhibitor L-NAME. The early glycosylation products increased thromboxane production (P < 0.001), while prostaglandin E2 synthesis was unaffected. These data indicate that Amadori products of glycated albumin modulate NO synthase activity and eicosanoid balance in EC. These effects may be relevant to the hemodynamic changes in the early phases of diabetic nephropathy and in the lasting progression to sclerosis.

Albumins↗
PubMed1997

Immunogenetics of Henoch-Schoenlein disease.

In order to investigate the genetic basis of susceptibility to Henoch-Schoenlein purpura (HS), blood samples of 152 patients, 105 of whom had renal disease, were collected in a two-step study. The evaluation of DRB, DQB and DQA polymorphism was done by analysis of the restriction polymorphisms produced by TaqI enzyme. DRB1*07 was less frequent in patients than in the control group (gene frequency 0.09 and 0.18, respectively; P = 0.0023), whereas 64% of the patients were positive for DRB1*01 and/or DRB1*11 compared with 48% of the control group (P = 0.0069). Polymerase chain reaction-sequence-specific oligonucleotide (PCR-SSO) typing of DRB1*01- and DRB1*11-positive individuals did not show any deviation of frequencies of DRB1*01 subtypes between patients and controls, whereas among DRB1*11 subtypes DRB1*1104 was significantly increased in the patients (Pc = 0.033). The comparison between patients with renal disease and those without renal disease showed no significant differences in the frequency of the single DRB, DQB and DQA alleles. The study of restriction polymorphisms in the switch region of the constant genes alpha 1, alpha 2 and mu of the heavy chains of immunoglobulins, using the enzyme Sacl and a specific probe, did not show any difference between 44 patients and 54 controls. This study demonstrates that susceptibility to HS also has a genetic origin: on one hand, the presence of DRB1*01 or DRB1*11 makes disease onset easier; on the other hand, DRB1*07 could induce some resistance to the disease. It is suggested that, as well as for other diseases caused by an impaired immune response, single amino acids in a key position in the HLA-DRB molecule make it more or less easy to recognize some antigenic peptide, towards which an immune response leading to disease is triggered.

Adolescent↗
PubMed1997

Properties of circulating IgA molecules in Henoch-Schönlein purpura nephritis with focus on neutrophil cytoplasmic antigen IgA binding (IgA-ANCA): new insight into a debated issue. Italian Group of Renal Immunopathology Collaborative Study on Henoch-Schönlein purpura in adults and in children.

BACKGROUND: The presence and the pathogenetic role of circulating IgA reacting with neutrophil cytoplasmic antigens (IgA-ANCA) in patients with Henoch-Schönlein purpura (HSP) is still debated. This study was aimed to investigate some characteristics of serum IgA and macromolecular IgA in HSP patients, focusing on IgA-ANCA. METHODS: Eighty-seven HSP patients with biopsy proved renal involvement (51 adults and 36 children) enrolled in a multicentre study of the Italian Group of Immunopathology were investigated. RESULTS: Significantly high levels of IgA immune complexes were found in both adults (P < 0.05) and children (P < 0.01), while the binding of IgA to jacalin, was significantly low in children with HSP (P < 0.01) only. Two series of ELISA were done for IgA-ANCA, in two different laboratories. Increased binding to PMN crude extracts (P < 0.01) without any modification in IgA binding to proteinase 3 was found by either specific ELISA. Conversely, the binding of IgA to myeloperoxidase (MPO) was found to be significantly (P < 0.05) increased with positive values in 25% of patients by one assay only. Three of four sera with positive IgA-MPO ANCA exhibited binding in Western-blot studies with the MPO preparation used in ELISA to a 28-kDa species. D-galactose and N-acetyl-glucosamine decreased the binding of serum IgA to MPO more in HSP than in controls (P < 0.05). CONCLUSIONS: The conflicting reports on IgA-ANCA may reflect some atypical characteristics of the reaction which can be detected only by some ELISAs. We suggest that not an antigen-antibody reaction but a lectinic interaction due to abnormal composition of IgA carbohydrate side chains may account for the IgA-ANCA reaction in patients with HSP nephritis.

Adult↗
PubMed1997

Long-term prognosis of Henoch-Schönlein nephritis in adults and children. Italian Group of Renal Immunopathology Collaborative Study on Henoch-Schönlein purpura.

BACKGROUND: The aim of this multicentre collaborative study was to compare the progression of renal disease in children and adults with Henoch-Schönlein purpura (HPS) nephritis selected on the basis of IgA-dominant renal deposits and biopsy material available for review. METHODS: The analysis was performed in 152 patients (95 adults and 57 children < 16 years old at diagnosis) with a follow-up (> or = 1 year up to 20 years (4.9 +/- 3.4 years in adults and 4.8 +/- 3.9 years in children). RESULTS: Renal histology and clinical presentation were similar in both age groups: crescents were found in 36% of adults and 34.6% of children (in only 2.7% of adults and 1.9% of children involving > 50% of glomeruli), nephrotic-range proteinuria in 29.5% of adults and 28.1% of children and functional impairment in 24.1% of adults and 36.9% of children. The outcome was similar for both age groups (remission, 32.5% of adults and 31.6% of children; renal function impairment, 31.6% of adults and 24.5% of children). Endstage renal disease was observed in 15.8% of adults and in 7% of children. Renal function survival at 5 years was not significantly different in the two groups (85% in adults and 95% in children) and at 10 years it was approximately 75% in both groups. None of the children died and adult survival was 97% at 5 years. In adults at presentation, renal function impairment (P < 0.02) as well as proteinuria higher than 1.5 g/day (P < 0.02) and hypertension (P < 0.001) were negative prognostic factors. Multivariate analysis stressed the main statistical relevance of proteinuria (relative risk 2.37, P < 0.02). Conversely, in children no definite level of proteinuria, hypertension or other data were found to be associated with poor prognosis. CONCLUSIONS: Among patients with a clinical presentation which warrants renal biopsy, HSP nephritis has a similar prognosis in children and adults. The evolution is more predictable in adults than in children.

Adult↗
PubMed1997

Acetate intolerance is mediated by enhanced synthesis of nitric oxide by endothelial cells.

The clinical picture of acetate intolerance strictly mimics the nitric oxide (NO) effect, including smooth muscle relaxation and extreme vasodilation. Because acetate induces production of cAMP, which is a powerful stimulus of NO synthase (NOS), we evaluated the effect of different dialysate solutions with and without acetate on NOS activity in endothelial cells (EC). NOS activity of EC, evaluated as H3-citrulline produced from H3-arginine, was modulated by the dialysate composition (e.g., 38 mmol/L acetate produced an increase of 3.2 +/- 0.39-fold compared with basal values (P < 0.0005), and the small amount of acetate (4 mmol/L) in 35 mmol/L bicarbonate solution increased the NOS activity by 2 +/- 0.49-fold (P < 0.05). Conversely, the acetate-free solution produced no effect on NOS activity. The mRNA encoding for inducible NOS was highly expressed in EC incubated with acetate buffer and also with acetate in bicarbonate dialysis buffer. The EC proliferative index was depressed by acetate (P < 0.0005), and tumor necrosis factor synthesis was increased (P < 0.0005) compared with acetate-free buffer. This study suggests that dialytic "acetate intolerance" can be induced by the activation, through cAMP and tumor necrosis factor release, of NOS. The small amount of acetate in bicarbonate dialysate, although capable of inducing in vitro NOS activation, is likely to be rapidly metabolized, whereas the large amounts of this anion in acetate fluids overwhelm metabolism by the liver. Acetate-free dialysate is the only solution that provides an acceptable level of biocompatibility both in vivo and in vitro.

Acetates↗
PubMed1996

Tubulointerstitial responses in the progression of glomerular diseases: albuminuria modulates alpha v beta 5 integrin.

Proteinuria represents one of the most unfavorable prognostic factors in the progression of nephropathies. Several lines of evidence support a role for proteinuria per se in the development of interstitial fibrosis, albeit the molecular mechanisms are still unknown. We investigated the potential role of integrins expressed on tubular cells in regulating the synthesis and organization of interstitial matrix or as mediators of tubulointerstitial damage in conditions mimicking the nephrotic milieu. Under basal conditions, cultured tubular cells highly expressed alpha 3 beta 1 and, at focal contacts, alpha v beta 3. In contrast, alpha v beta 5 was weakly and diffusely distributed all over the plasma membrane. Cultures on a variety of matrix substrates (fibronectin, laminin, collagen types I and IV, vitronectin, von Willebrand factor, fibrinogen) did not induce any phenotypic change in integrin expression by tubular cells. Conversely, the addition of albumin resulted in a highly increased membrane expression of beta 5, which was organized in typical focal contacts and was related to the dose of albumin added. Immunofluorescence, flow cytometry, immunoprecipitation and RT-PCR experiments argue for a complex mechanism that includes increased post-transcriptionally regulated protein synthesis, accelerated conversion of precursors to mature forms, and increased surface delivery to discrete adhesive structures. Up-regulation of the beta 5 chain in tubular cells was confirmed in 9 out of 11 kidney biopsies from proteinuric glomerulonephritides including membranous and focal sclerosing glomerulonephritis, while it was not expressed in nonproteinuric kidneys including five biopsy specimens. This is the first report indicating that proteinuria up-regulates the surface expression and distribution of a specific integrin chain on tubular cells. These observations suggest the participation of integrins in a hitherto unexplored mechanism of tubulo-interstitial responses to glomerular injury.

Albuminuria↗
PubMed1996

Adriamycin-induced proteinuria in nude mice: an immune-system-mediated toxic effect.

BACKGROUND: The renal minimal lesion disease induced in rats by adriamycin (ADR) is generally thought to be consequent to a direct cytotoxic effect of this drug on glomerular epithelial cells. Only recently an altered synthesis of mediators, including reactive oxygen species and monocyte-macrophage cytokines, has been hypothesized. METHODS: A mouse strain (nude) bearing a congenital thymic aplasia is a suitable experimental animal to evaluate the role of immune reactions in the development of the ADR nephropathy, provided mouse susceptibility to its toxic effect. Therefore, experimental mice were divided into three groups (G) each receiving adriamycin 7.5 mg/kg b.w.: GA (15 heterozygous nu/O mice with normal immune system); GB (15 homozygous nu/nu athymic mice); GC (15 homozygous nu/nu mice which were also splenectomized, irradiated, and treated with anti-asialo Gm1 antibody to abolish NK and decrease macrophage activity). All animals were maintained under pathogen-free conditions. Urinary proteins, albumin and TNF-alpha excretion were measured. RESULTS: After 14 days the proteinuria was 43.8+/-1.7 microg/min in GA, 30.2+/-2.9 microg/min in GB (P<0.05) and 12.2+/-2.8 microg/min in GC (GA vs GC, P<0.0001; GB vs GC, P<0.05). Albuminuria gave a similar profile. TNG-alpha urinary excretion was significantly higher in GA (17.3+/-3.2 mU/min) than in GB (5+/-0.6 mU/min, P<0.001) and GC (3.2+/-0.9 mU/min, P<0.001). A significant correlation was found in GA between urinary TNF-alpha and protein losses (r2=0.63 P<0.0001). Kidney tissue homogenates failed to show in each experimental group any evidence of mRNA encoding for TNF-alpha, which was detectable in peripheral mononuclear cells from GA and GB, but undetectable in GC mice. Segmental effacements of glomerular epithelial cell foot process were observed by electron-microscopy in GA only, while they were minimal in GB and absent in GC. Iron colloidal staining for anionic sites on frozen sections always showed a normal pattern. CONCLUSIONS: Nude mice bearing cellular immunity deficiency are protected from proteinuria following ADR toxicity. An impaired synthesis and release of lymphomonocyte mediators including TNF-alpha could be envisaged.

Animals↗
PubMed1996

Complications linked to chronic peritoneal dialysis in children after kidney transplantation: experience of the Italian Registry of Pediatric Chronic Peritoneal Dialysis.

Our objective was to evaluate the infectious complications of the post-transplant period attributable to the persistence of catheter and other complications when chronic peritoneal dialysis (CPD) was performed post-transplantation. The design was a retrospective study, and the setting was an Italian registry of pediatric chronic peritoneal dialysis. There were 86 pediatric renal transplants (9/86 from living related donors, 2/86 simultaneous liver and kidney transplantation for oxalosis). Six of 86 transplants were lost at follow-up. Mean age of the children (n = 80) at transplantation was 9.3 years (range: 1.7-21 years). They had been on CPD for a mean period of 1.7 years (range: 0.2-4.6 years). During CPD, 67 peritonitis episodes (80% related to exit-site and/or tunnel infections) were observed, with an incidence of peritonitis of one episode per 16 months CPD. The mean safe interval of peritonitis and/or exit-site or tunnel infection was 208 days (range: 36-1897 days). The mean time of catheter removal was 80.3 days (range: 0-216 days) post-transplantation. During the first month post-transplantation, one episode of peritonitis secondary to a sepsis occurred in one child. No other episodes of peritonitis or exit-site and/or tunnel infections were observed. Two of 80 children returned to CPD (at four and at 12 months, respectively) because of persistent allograft failure. Furthermore, 12 patients were on CPD because of temporary graft failure. In all these patients the pretransplant peritoneal dialysis (PD) catheter was utilized, with no complications. These data show that the persistence of the PD catheter after kidney transplantation has produced no infections or other complications. What is more, the catheter was safely utilized during acute rejection or primary allograft nonfunction.

Adolescent↗
PubMed1996

[Is HCV RNA detectable in the ultrafiltrate?].

We investigated by molecular biology the possibility that the HC virus passes by the dialysis membranes into the ultrafiltrate, making the HD monitor a way of HCV transmission. HCV-RNA was tested in blood and in UF samples during 2 HD sessions at T-0, 30, 60, 120 min and at HD end. HCV-RNA was measured by RT-PCR. Viraemia in patients was > 10(-4) gen Eq/ml and remained unchanged along HD, HCV-RNA was not found in whole UF and its x100 concentrates during the HD. We failed to prove the passage of the HCV into the UF, at least in standard conditions.

Hemofiltration↗
PubMed1995

IgA serology in recurrent and non-recurrent IgA nephropathy after renal transplantation.

BACKGROUND: This study investigated whether abnormal circulation of macromolecular IgA and IgA with altered glycosylation or electrical charge plays a role in the recurrence of IgA nephropathy (IgAN) after transplantation. STUDY DESIGN: A total of 92 renal transplant patients were enrolled; 52 IgAN patients and 40 with other non-IgAN. The IgAN group included 10 patients showing IgA mesangial deposits in the grafted kidneys (recurrent group) and 10 who did not (immunohistochemically proven non-recurrent group). In addition another 22 IgAN transplant patients were clinically free of recurrent disease. METHODS: The analyses included macromolecular IgA (IgAIC) detected by the conglutinin assay (K), heavy IgA precipitated in 2.5% polyethylene glycol (PEG), IgA-fibronectin aggregates (IgA/F Aggr), mixed IgA/IgGIC, IgA binding to mesangial matrix components (fibronectin, laminin, type IV collagen) or polycations (poly-L-lysine) and IgA with altered glycosylation (Jacalin-binding assay). RESULTS: After transplantation, IgAN patients displayed significantly higher mean levels for each variable measured than non-IgAN (ANOVA, P < 0.05). By stepwise regression analysis, the binding of IgA to fibronectin had the highest coefficient. By comparing data in recurrent and clinically non-recurrent IgAN, we observed that two groups could be distinguished by the results of the two assays for macromolecular IgA (conglutinin IgAIC and IgA-fibronectin aggregates) and IgA with increased affinity for type IV collagen (P < 0.05). When the selected group of immunohistochemically proven non-recurrent IgAN was compared to the recurrent one, a statistically significant difference was found only for the binding of IgA to type IV collagen (P < 0.05). Data from this test were significantly related with proteinuria (P < 0.05) and microscopic haematuria (P < 0.04). CONCLUSIONS: Even though the IgA serology of renal transplant IgAN patients shows peculiar features and recurrent and non-recurrent IgAN differ in many aspects, the prevalence of positive data in the two groups had no predictive value. This suggests that the recurrence of IgAN is modulated by factors affecting the interaction between circulating abnormal IgA and mesangial cells and/or matrix.

Analysis of Variance↗
PubMed1995

Enhanced production of nitric oxide by blood-dialysis membrane interaction.

Nitric oxide (NO) is a powerful vasoactive product of endothelial origin, and one of its major effects is vasodilation, leading to hypotension. The role of NO in some complications of uremia is still debated. This study evaluated whether endothelial NO synthase activity could be modulated by the exposure of healthy blood to hemodialysis materials. In vitro hemodialysis sessions were performed with cuprophan and polymethylmethacrylate membranes. Blood samples from a healthy donor after recirculation for 0, 5, 15, 30, and 60 min were coincubated for 6 h with a murine endothelial cell line (t.End.1); mRNA for inducible NO synthase and enzyme activity, measured as (3H)citrulline produced from (3H)arginine, were detected. The release of interleukin (IL)-1 beta and tumor necrosis factor-alpha (TNF-alpha) from recirculating lymphomonocytes was measured, too. The NO synthase activity of endothelial cells was stimulated by blood dialyzed with cuprophan, peaking at 15 min (11-fold increase in comparison to the basal values), whereas polymethylmethacrylate was ineffective (P < 0.01 versus Cuprophan). Dialysis with cuprophan, but not with polymethylmethacrylate, induced in endothelial cells the expression of mRNA encoding for inducible NO synthase. The release of IL-1 beta and TNF-alpha after 6 h by recirculating lymphomonocytes paralleled the NO synthase activity profile in endothelial cells and was significantly higher after cuprophan exposure than after polymethylmethacrylate (P < 0.0001). In conclusion, the activity of endothelial NO synthase can be enhanced during the dialysis sessions by the interaction of lymphomonocytes with the membranes, possibly via TNF-alpha and IL-1 beta production.

Animals↗
PubMed1995

Macromolecular IgA and abnormal IgA reactivity in sera from children with IgA nephropathy. Italian Collaborative Paediatric IgA Nephropathy Study.

This multicenter study investigated the characteristics of circulating IgA molecules in 77 children: 42 had primary IgA nephropathy (IgAN), 20 were non-IgA glomerulonephritides (CGN) and 15 had urological problems (U). Fifteen assays were employed including the detection of macromolecular IgA [IgA immune complexes (IgAIC) by the conglutinin (K) assay, heavy molecular weight IgA in 2.5% polyethylene glycol (PEG), mixed IgA/IgGIC (Jacalin assay), IgA-Fibronectin (IgA-F) aggregates]IgA antibodies to alimentary antigens (gliadin, glycgli, glutein, ovalbumin, bovine serum albumin) and IgA binding to mesangial antigens (fibronectin, laminin, type IV collagen) or polycations (poly-L-lysine). Total IgA and IgA reacting with jacalin, supposed to bear an altered galactosylation, were measured as well. Mean levels of each kind of macromolecular IgA were significantly increased in children with IgAN in comparison to U disease (K-IgAIC p < 0.05, PEG-IgAIC p < 0.01, IgA/IgGIC p < 0.004, IgA-F aggregates p < 0.0003). However, IgA-F were the only macromolecular IgA significantly higher in IgAN than in CGN (p < 0.0005). IgA-F aggregates did not correlate with any urinary sign of activity, while K-IgAIC data were significantly related with microscopic hematuria (p < 0.05) and past history of gross hematuria (p < 0.02). Children with IgAN had mean levels of IgA reacting with the lectinic fractions of gliadin significantly higher than CGN (p < 0.01) and U groups (p < 0.003). IgAN displayed an enhanced production of IgA reacting with mesangial matrix components vs CGN (p < 0.03) and U (p < 0.0003) groups and showed altered interactions with positively charged molecules (poly-L-Lysine, p < 0.01) and carbohydrate residues (jacalin p < 0.05). In IgAN there is an increased circulation of altered IgA favouring the formation of macromolecular IgA, including true IgAIC or IgA aggregated by carbohydrate interactions. The affinity for the mesangial matrix glycoproteins and for the mesangial area electrical charge might further enhance the trapping and deposition of the immune material containing IgA. IgA-F aggregates seem to be a marker of this event, while complement binding molecules in IgAIC correspond to the hematuric manifestation of the nephritogenic process.

Adolescent↗