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SUMMARY Mesothelial cells (MC) from human peritoneal omentum fragments obtained during surgical insertion of peritoneal catheters for continuous peritoneal dialysis in end stage renal failure (ESRF) patients were cultured in vitro. MC exhibited a phenotype different from macrophages, but MHC class II molecules were well expressed. Therefore MC lines were tested for antigen-presenting capacity by pulsing with soluble antigens (tetanus toxoid and purified protein derivative (PPD)) or with a corpusculate antigen (Candida albicans bodies). Autologous peripheral blood mononuclear cells (PBMC) depleted of adherent monocytes and cloned T cells generated from an individual matched for the MHC class II antigen DR2 were used to test antigen-presenting function. MC effectively presented the soluble and corpusculate antigens to autologous and MHC-compatible allogeneic lymphocytes, indicating that they are endowed with both endocytic/phagocytic activity and with processing/presenting capacity. Preincubation of MC with human recombinant interferon-gamma (IFN-γ) up-regulated MHC class II and intercellular adhesion molecule-I (ICAM-I) expression, but the effect on antigen-presenting function was not consistent. Since MC are an important component of the peritoneal environment, they may participate, along with macrophages, in activation of specific T cells and in the generation of local cell-mediated immunity to various pathogens.

A high incidence of α1-antitrypsin (AAT) deficiency has been reported in patients with C-ANCA systemic vasculitis in association with antibodies against proteinase-3 (PR3). To clarify the role of AAT deficiency in the acute vasculitic process as well as in progression of the disease, we studied 84 patients with either C-ANCA or P-ANCA vasculitis with special reference to: (a) the AAT gene, (b) the phenotypic (Pi) variants and (c) the serum levels during both acute illness and remission. The PiZ gene was found in six patients (8% vs. 1.5% controls) irrespective of the type of autoantibodies (C-ANCA vs. P-ANCA). All PiZ patients displayed the ability to raise their AAT serum levels up to the normal range during acute illness. In contrast, 24 patients with the PiM phenotype presented low AAT serum levels during acute illness. In all these patients, the AAT levels returned to normal values during the remission. Low AAT levels were associated with low levels of C- reactive protein (PCR) (P < 0.001), with a leSS severe renal involvement or a minor risk of death, and, in one tested patient, with a novel point mutation (TCGA →, TCAA) at the enhancer-promoter region of the AAT gene. Low AAT serum levels did not correlate with either type/titre of autoantibody or distribution/severity of the vasculitis process. In the case-control study, high AAT levels emerged as a major determinant of progression towards end- stage renal failure [odds ratio 3 (95% CI 1.1-8.4)]. These results indicate: (a) a high incidence of the PiZ gene of AAT in systemic vasculitis irrespective of the type of autoantibodies; (b) a novel form of AAT deficiency associated with the normal PiM phenotype becoming manifest only during acute illness; (c) dysregulation of the acute-phase response affecting selectively AAT or both AAT and PCR; (d) correlation between low plasma levels of AAT and less severe renal involvement or risk of death.

Autosomal-dominant Alport syndrome: Natural history of a disease due to COL4A3 or COL4A4 gene. Background Alport syndrome is a clinically and genetically heterogeneous nephropathy. The majority of cases are transmitted as an X-linked semidominant condition due to COL4A5 mutations. In this form males are more severely affected than females. Less than 10% of cases are autosomal recessive due to mutation in either COL4A3 or COL4A4 . In this rarer form, both males and females are severely affected. Only two cases of autosomal-dominant Alport syndrome have been reported, one due to a COL4A3 mutation and the other due to a COL4A4 mutation. Because of the paucity of the reported families, the natural history of autosomal-dominant Alport syndrome is mostly unknown. Methods Four families with likely autosomal-dominant Alport syndrome were investigated. COL4A3 and COL4A4 genes were analyzed by denaturing high-performance liquid chromatography (HPLC). Automated sequencing was performed to identify the underlying mutation. Results Two families had a mutation in the COL4A4 gene and two in the COL4A3 . Accurate clinical evaluation of family members showed interesting results. Affected individuals (22 persons) had a wide range of phenotypes from end-stage renal disease (ESRD) in the fifth decade to a nonprogressive isolated microhematuria. Finally, three heterozygous individuals (90, 22 and 11years old, respectively) were completely asymptomatic. Conclusion This paper demonstrated that patients affected by autosomal-dominant Alport syndrome have a high clinical variability. Moreover, a reduced penetrance of about 90% (3 of 25) may be considered for the assessment of recurrence risk during genetic counseling of these families.

HSA functions as a physiological transporter of solutes and small molecules that induce structural transitions 'in vitro'. Analysis of these transitions requires prior purification of HSA that could introduce bias due to conformational changes. We utilized electrophoretic titration curves to describe a neutral to acid (N-A) transition of HSA directly in sera of seven patients with active focal segmental glomerulosclerosis (FSGS). The divergent electrophoretic profile of HSA was characterized by a shift in the range of pHs between 4.5 and 7.5 with an average variation of free electrophoretic mobility corresponding to loss of 1 positive charge in the pK a protonation range of histidyl residues and should involve domain I of HSA. 'In-gel' determination by maleimide-PEO2-biotin of free SH 34 of domain I showed inaccessibility of the dye at this site in pathological HSA and alkylation with the same complex induced N-A transition in normal HSA. Potential binders of free imidazoles such as Ca ++ and/or of SH 34 such as NO were excluded on the basis of direct titration and studies on binding stimulation. This is the first report describing a transition of HSA directly 'in vivo', and the utilization of electrophoretic titration curves was critical to this purpose. This transition appears to be specific to FSGS and is unrelated to the nephrotic syndrome, Ca ++ and NO binding. Spectroscopic analysis will elucidate the structural implication.

The putative mechanisms of proteinuria in idiopathic focal glomerulosclerosis and of its post-transplant recurrence are discussed. It is proposed that a balance between circulating factors with permeability activity on glomeruli and putative inhibitors play a key role. The characterization of inductors is currently in progress; most inhibitors appear to be apolipoproteins (mainly apoJ and apo E) but we cannot exclude other substances. The goal is now to evaluate the concentration of both inducers and inhibitors of glomerular permeability in vivo. Permeability activity in plasma of patients with FSGS with and without recurrence of the disease may be evaluated by an in vitro functional essay with isolated glomeruli. Published data on permeability activity evaluated with this method in different proteinuric states gave, however, controversial results and this test cannot be readily considered of clear clinical utility. Only the definitive characterization and quantification in vivo of the different molecules that play a role in FSGS may furnish adequate answer.

Focal segmental glomerulosclerosis (FSGS) is a degenerative renal disease characterized by the accumulation of extracellular matrix and lipids within the glomerular tuft. It has been proposed that an abnormal renal permeabilization towards proteins induced by a putative plasma factor is, in some way, involved in the pathogenesis of the disease. In this paper, we measured the plasma permeability activity (Palb) in several sera of patients with FSGS and found a mean activity of 0.82+/-0.03 which means a marked increase compared to a mean Palb of 0.16+/-0.03 in normal controls. Coincubation of FSGS and normal serum reduced the permeability activity within the normal range; normal serum added to the incubation medium after the glomeruli had already been exposed to the FSGS serum had no effect, suggesting the presence of inhibitory substances with a direct effect on a circulating substrate. Finally, the antipermeability activity was retained when heated to 60 degrees C but not to 100 degrees C. By serial fractionations of normal serum and reported activity measurements at each step, five natural occurring inhibitors of albumin permeabilization were purified and characterized by matrix assisted laser desorption/ionization-mass spectrometry (MALDI-MS), as components of apolipoproteins (apo) (apo E2 and E4, apo L, the high Mr apo J and a 28 kDa fragment of apo A-IV). Coincubation of each apolipoprotein with FSGS serum inhibited permeability, but only apo J and apo E2 and E4 were found to be crucial for the process. In conclusion, we have purified from normal serum five inhibitors of permeability induced by FSGS serum, all corresponding to apolipoproteins. An imbalance between permeability factors and apolipoproteins may play a pathogenetic role in FSGS.

failure. The exclusion of linkage to the NPH1 locus suggests the existence of an MCD responsible locus, Background. The nephronophthisis‐medullary cystic disease (NPH/MCD) complex represents a heterogen- still to be mapped. eous group of hereditary tubulointerstitial nephritis. Key words: gout; hyperuricaemia; linkage analysis; The most common variant is juvenile recessive NPH, medullary cystic disease; nephronophthisis; NPH1 for which a gene locus (NPH1) has been mapped on locus chromosome 2q13. MCD is a less common dominant condition usually recognized later in life, which resembles NPH in many aspects, still presenting remarkable clinical diVerences. Nothing is known Introduction about the chromosome locus of MCD. Methods. Five MCD families were studied. Diagnosis The nephronophthisis‐medullary cystic disease was made by inference from family history, type of (NPH/MCD) complex represents a heterogeneous inheritance, clinical signs and histology. Multipoint group of inherited renal diseases sharing some histopalinkage analysis was performed by markers D2S293, thological lesions and a few clinical similarities [1,2]. D2S340 and D2S160 spanning the entire NPH1 locus. The most common variant is juvenile nephronophthisis Results. Diagnosis of MCD was made in 28 aVected (NPH ), a disease with an autosomal recessive inheritmembers (16 males; 12 females), belonging to five ance. Clinical signs of NPH typically are present in families. Histological diagnosis was available in 10 early childhood and invariably lead to end-stage renal patients; clinical diagnosis in 11; seven deceased relat- failure within the second decade of life. A gene locus ives had diagnosis of chronic nephritis. The age at for the purely renal form of NPH (NPH1) has been diagnosis ranged from 8 to 65 years. Renal medullary located on chromosome 2q13, where 65‐75% of cysts were found in a minority of patients. In family NPH1 patients exhibit a large homozygous deletion 1, the disease was associated with hyperuricaemia and (~250 kb) at which site a candidate gene has been gouty arthritis. Progression of renal disease presented identified [3‐7]. NPH occurring in association with intra- and extra-family variability with members of the extrarenal symptoms, such as retinitis pigmentosa, does same family showing mild elevation of creatinine or not map on 2q13 [3‐5]. terminal renal failure. The NPH1 locus associated to Medullary cystic disease (MCD) is a less common recessive NPH was excluded from linkage to the dom- condition, with autosomal dominant inheritance. inant MCD. MCD is recognized later in life, usually in the third Conclusions. MCD might be more common than previ- decade, and leads to end-stage renal failure at the age ously assumed. Variability in clinical presentation and of 40‐50 years [1,2]. Nothing is known about the absence of histopathological hallmarks contribute to chromosome loci or defective gene of the MCD. make the diagnosis uncommon. The most remarkable The clinical heterogeneity of NPH/MCD complex clinical diVerence with NPH is the age of onset in has been a matter of debate. Originally, the diseases some kindreds and a delayed progression towards renal were assumed to be diVerent disorders [8‐10].

Objective To analyze the data from 347 peritoneal catheters implanted in 249 pediatric patients aged ≤ 15 years at start of chronic peritoneal dialysis (CPD). Design Restrospective study of the data collected between 1986 and 1995, in 20 dialysis centers, from the Italian Registry of Pediatric Chronic Peritoneal Dialysis. Data collection for each pediatric catheter included: catheter type, site and technique of insertion, complications, duration, and reason for removal or replacement. Results Fifty catheters were inserted in patients under 2 years of age, 50 in patients aged 2 5 years and 247 in patients over 5 years of age. Catheter types included 307 (88.5%) Tenckhoff (286 double cuff, 21 single cuff) and 40 (11.5%), double-cuff, Valli-type catheters. All catheters were surgically implanted and omentectomy was performed in 83.5% of cases; the entry-site was in the midline in 136 cases (39.2%) and paramedian in 211 (60.8%). During 6076 CPD months we observed 274 catheter related complications: 182 catheter infections (exit-site and/or tunnel infection), 23 leakages, 19 obstructions, 19 cuff-extrusions, 14 dislocations, 6 hemoperitoneum, 10 other (incidence of one complication every 21.8 dialysis months). A significant reduction of catheter-related complications occurred in the last five years, compared with the first 5 years. One hundred and six catheters were removed due to catheter-related causes: infection (83 cases), obstruction (11), dislocation (4), outer-cuff extrusion (3), leakage (2), bowel incarceration (2), and bowel infarction (1). Catheter survival was 72.2% at 12 months, 52.3% at 24 months, 32.8% at 36 months, and 25.7% at 48 months. Significantly lower catheter survival was found in younger children (0 2 years) compared with two other age groups (2 5 years, and > 5 years). No significant correlation was found between catheter survival and catheter entry-site (midline vs paramedian). Conclusions Catheter-related infections were confirmed to be the most common complication and most frequent cause of peritoneal catheter removal. In addition, catheter survival rate was worse in younger children, indicating that more effort should be made to improve peritoneal catheter survival particularly in this age group.

Glomerular albumin permeability alterations can be induced in vitro by serum from patients with end-stage renal disease caused by primary focal segmental glomerulosclerosis (FSGS). It was hypothesized that inhibitory substances may be present in normal serum, which may prevent the permeability alterations in isolated glomeruli, and the present study sought to isolate and characterize these factors. Albumin permeability was determined from the change in glomerular volume induced by applying oncotic gradients across the basement membrane of healthy isolated rat glomeruli preincubated with FSGS serum and normal serum fractionated using standard techniques. Fractions of normal serum with inhibitory activity obtained by a multistep chromatographic procedure underwent two-dimensional electrophoresis and staining. Approximately 50 protein spots were recovered, renatured, and tested for antipermeability activity. Five of these proteins demonstrated consistent inhibitory activity, and desorption ionization and mass spectrometry proved them to be components of high-density lipoprotein: apolipoproteins (apo) E(2) and E(4), high-molecular-weight J and L, and a 28-kD fragment of A-IV. Polyclonal antibodies to apo E or apo J added to the whole normal serum restored the permeability activity of the FSGS serum in the bioassay. Commercially available apo E and apo J also demonstrated antipermeability activity when added to FSGS serum. Cyanogen bromide digestion of apo A-IV produced fragments that inhibited the permeability activity of the FSGS serum, whereas the intact protein did not. Thus, components of high-density lipoprotein are capable of preventing glomerular albumin permeability induced by serum from patients with FSGS in an in vitro system. The specificity and mechanism of the inhibition remain to be determined; the alteration of normal inhibitory activity in vivo may be a component in the pathophysiology of FSGS.