Heritable induced resistance in Arabidopsis thaliana: Tips and tools to improve effect size and reproducibility

Over a decade ago, three independent studies reported that pathogen- and herbivore-exposed Arabidopsis thaliana produces primed progeny with increased resistance. Since then, heritable induced resistance (h-IR) has been reported across numerous plant-biotic interactions, revealing a regulatory function of DNA (de)methylation dynamics. However, the identity of the epi-alleles controlling h-IR and the mechanisms by which they prime defense genes remain unknown, while the evolutionary significance of the response requires confirmation. Progress has been hampered by the relatively high variability, low effect size, and sometimes poor reproducibility of h-IR, as is exemplified by a recent study that failed to reproduce h-IR in A. thaliana by Pseudomonas syringae pv. tomato (Pst). This study aimed to improve h-IR effect size and reproducibility in the A. thaliana-Pst interaction. We show that recurrent Pst inoculations of seedlings result in stronger h-IR than repeated inoculations of older plants and that disease-related growth repression in the parents is a reliable marker for h-IR effect size in F1 progeny. Furthermore, RT-qPCR-based expression profiling of genes controlling DNA methylation maintenance revealed that the elicitation of strong h-IR upon seedling inoculations is marked by reduced expression of the chromatin remodeler DECREASE IN DNA METHYLATION 1 (DDM1) gene, which is maintained in the apical meristem and transmitted to F1 progeny. Two additional genes, MET1 and CHROMOMETHYLASE3 (CMT3), displayed similar transcriptional repression in progeny from seedling-inoculated plants. Thus, reduced expression of DDM1, MET1, and CMT3 can serve as a marker of robust h-IR in F1 progeny. Our report offers valuable information and markers to improve the effect size and reproducibility of h-IR in the A. thaliana-Pst model interaction.

Evaluation of the Classification Accuracy of the Kidney Biopsy Direct Immunofluorescence through Convolutional Neural Networks

BACKGROUND AND OBJECTIVES

Immunohistopathology is an essential technique in the diagnostic workflow of a kidney biopsy. Deep learning is an effective tool in the elaboration of medical imaging. We wanted to evaluate the role of a convolutional neural network as a support tool for kidney immunofluorescence reporting.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

High-magnification (×400) immunofluorescence images of kidney biopsies performed from the year 2001 to 2018 were collected. The report, adopted at the Division of Nephrology of the AOU Policlinico di Modena, describes the specimen in terms of "appearance," "distribution," "location," and "intensity" of the glomerular deposits identified with fluorescent antibodies against IgG, IgA, IgM, C1q and C3 complement fractions, fibrinogen, and κ- and λ-light chains. The report was used as ground truth for the training of the convolutional neural networks.

RESULTS

In total, 12,259 immunofluorescence images of 2542 subjects undergoing kidney biopsy were collected. The test set analysis showed accuracy values between 0.79 ("irregular capillary wall" feature) and 0.94 ("fine granular" feature). The agreement test of the results obtained by the convolutional neural networks with respect to the ground truth showed similar values to three pathologists of our center. Convolutional neural networks were 117 times faster than human evaluators in analyzing 180 test images. A web platform, where it is possible to upload digitized images of immunofluorescence specimens, is available to evaluate the potential of our approach.

CONCLUSIONS

The data showed that the accuracy of convolutional neural networks is comparable with that of pathologists experienced in the field.

Reproducibility of the Oxford classification of immunoglobulin A nephropathy, impact of biopsy scoring on treatment allocation and clinical relevance of disagreements: evidence from the VALidation of IGA study cohort

BACKGROUND

The VALidation of IGA (VALIGA) study investigated the utility of the Oxford Classification of immunoglobulin A nephropathy (IgAN) in 1147 patients from 13 European countries. Methods. Biopsies were scored by local pathologists followed by central review in Oxford. We had two distinct objectives: to assess how closely pathology findings were associated with the decision to give corticosteroid/immunosuppressive (CS/IS) treatments, and to determine the impact of differences in MEST-C scoring between central and local pathologists on the clinical value of the Oxford Classification. We tested for each lesion the associations between the type of agreement (local and central pathologists scoring absent, local present and central absent, local absent and central present, both scoring present) with the initial clinical assessment, as well as long-term outcomes in those patients who did not receive CS/IS.

RESULTS

All glomerular lesions (M, E, C and S) assessed by local pathologists were independently associated with the decision to administer CS/IS therapy, while the severity of tubulointerstitial lesions was not. Reproducibility between local and central pathologists was moderate for S (segmental sclerosis) and T (tubular atrophy/interstitial fibrosis), and poor for M (mesangial hypercellularity), E (endocapillary hypercellularity) and C (crescents). Local pathologists found statistically more of each lesion, except for the S lesion, which was more frequent with central review. Disagreements were more likely to occur when the proportion of glomeruli affected was low. The M lesion, assessed by central pathologists, correlated better with the severity of the disease at presentation and discriminated better with outcomes. In contrast, the E lesion, evaluated by local pathologists, correlated better with the clinical presentation and outcomes when compared with central review. Both C and S lesions, when discordant between local and central pathologists, had a clinical phenotype intermediate to double absent lesions (milder disease) and double present (more severe).

CONCLUSION

We conclude that differences in the scoring of MEST-C criteria between local pathologists and a central reviewer have a significant impact on the prognostic value of the Oxford Classification. Since the decision to offer immunosuppressive therapy in this cohort was intimately associated with the MEST-C score, this study indicates a need for a more detailed guidance for pathologists in the scoring of IgAN biopsies.

Is there long-term value of pathology scoring in immunoglobulin A nephropathy? A validation study of the Oxford Classification for IgA Nephropathy (VALIGA) update

Background

It is unknown whether renal pathology lesions in immunoglobulin A nephropathy (IgAN) correlate with renal outcomes over decades of follow-up.

Methods

In 1130 patients of the original Validation Study of the Oxford Classification for IgA Nephropathy (VALIGA) cohort, we studied the relationship between the MEST score (mesangial hypercellularity, M; endocapillary hypercellularity, E; segmental glomerulosclerosis, S; tubular atrophy/interstitial fibrosis, T), crescents (C) and other histological lesions with both a combined renal endpoint [50% estimated glomerular filtration rate (eGFR) loss or kidney failure] and the rate of eGFR decline over a follow-up period extending to 35 years [median 7 years (interquartile range 4.1–10.8)].

Results

In this extended analysis, M1, S1 and T1–T2 lesions as well as the whole MEST score were independently related with the combined endpoint (P < 0.01), and there was no effect modification by age for these associations, suggesting that they may be valid in children and in adults as well. Only T lesions were associated with the rate of eGFR loss in the whole cohort, whereas C showed this association only in patients not treated with immunosuppression. In separate prognostic analyses, the whole set of pathology lesions provided a gain in discrimination power over the clinical variables alone, which was similar at 5 years (+2.0%) and for the whole follow-up (+1.8%). A similar benefit was observed for risk reclassification analyses (+2.7% and +2.4%).

Conclusion

Long-term follow-up analyses of the VALIGA cohort showed that the independent relationship between kidney biopsy findings and the risk of progression towards kidney failure in IgAN remains unchanged across all age groups and decades after the renal biopsy.

The prevalence of autosomal dominant polycystic kidney disease (ADPKD): A meta-analysis of European literature and prevalence evaluation in the Italian province of Modena suggest that ADPKD is a rare and underdiagnosed condition

Background and objectives

ADPKD is erroneously perceived as a not rare condition, which is mainly due to the repeated citation of a mistaken interpretation of old epidemiological data, as reported in the Dalgaard's work (1957). Even if ADPKD is not a common condition, the correct prevalence of ADPKD in the general population is uncertain, with a wide range of estimations reported by different authors. In this work, we have performed a meta-analysis of available epidemiological data in the European literature. Furthermore we collected the diagnosis and clinical data of ADPKD in a province in the north of Italy (Modena). We describe the point and predicted prevalence of ADPKD, as well as the main clinical characteristics of ADPKD in this region.

Methods

We looked at the epidemiological data according to specific parameters and criteria in the Pubmed, CINAHL, Scopus and Web of Science databases. Data were summarized using linear regression analysis. We collected patients’ diagnoses in the Province of Modena according to accepted clinical criteria and/or molecular analysis. Predicted prevalence has been calculated through a logistic regression prediction applied to the at-risk population.

Results

The average prevalence of ADPKD, as obtained from 8 epidemiological studies of sufficient quality, is 2.7: 10,000 (CI95 = 0.73–4.67). The point prevalence of ADPKD in the province of Modena is 3.63: 10,000 (CI95 = 3.010–3.758). On the basis of the collected pedigrees and identification of the at-risk subjects, the predicted prevalence in the Province of Modena is 4.76: 10,000 (CI 95% = 4.109–4.918).

Conclusion

As identified in our study, point prevalence is comparable with the majority of the studies of literature, while predicted prevalence (4.76: 10,000) generally appears higher than in the previous estimates of the literature, with a few exceptions. Thus, this could suggest that undiagnosed ADPKD subjects, as predicted by our approach, could be relevant and will most likely require more clinical attention. Nevertheless, our estimation, in addition to the averaged ones derived from literature, not exceeding the limit of 5:10,000 inhabitants, are compatible with the definition of rare disease adopted by the European Medicines Agency and Food and Drug Administration.

Lipoprotein glomerulopathy associated with a mutation in apolipoprotein e

Lipoprotein glomerulopathy is a pathological condition characterized by lipid accumulation in the glomerular capillaries that has been associated with the presence of rare mutants of apolipoprotein E (ApoE). We describe a 51-year-old Italian patient presenting Type III hyperlipidemia and proteinuria in whom renal biopsy showed capillary ectasia and intraluminal lipid deposits, suggesting the diagnosis of lipoprotein glomerulopathy. The patient, who had elevated plasma ApoE level, was found to be heterozygous for a mutation in ApoE (Arg150Cys), designated apoE_MODENA. This mutation induces the formation of ApoE dimers that are detectable under non-reducing conditions. Treatment with hypolipidemic drugs did not result in a complete remission of the proteinuria and was accompanied by a slow but progressive worsening of renal function with the persistence of intracapillary lipid thrombi. The introduction of low-density lipoprotein aphaeresis combined with a more aggressive lipid lowering and antihypertensive therapy resulted in the remission of proteinuria and a substantial improvement of renal function. Switching from low-density lipoprotein aphaeresis to plasma filtration did not result in an equivalent control of renal damage. The patient died of intracranial hemorrhage during an acute episode of malignant hypertension.

Identification and characterization of a new autoimmune protein in membranous nephropathy by immunoscreening of a renal cDNA library

Membranous Nephropathy (MN) represents a large amount of Nephrotic Syndromes in the adult population and its definitive diagnosis is currently carried out through biopsy. An autoimmune condition has been demonstrated in idiopathic MN (iMN) in which some kidney structures are targeted by patient autoantibodies. Some candidate antigens have been described and other likely involved target proteins responsible for the disease are not known yet. In this work our aim is to identify these proteins by screening a lambda-phage library with patients' sera. We enrolled four groups of patients: two MN groups of 12 full iMN patients; one control group of 15 patients suffering from other renal diseases; one control group of 15 healthy individuals. A commercial cDNA phagemide library was screened using the above described sera, in order to detect positive signals due to antigen-antibody bond. We detected one phagemide clone expressing a protein which was shown to be targeted by the antibodies of the iMN sera only. Control sera were negative. The sequence analysis of cDNA matched the Synaptonemal Complex protein 65 (SC65) coding sequence. Further proteomic analyses were carried out to validate our results. We provide evidence of an involvement of SC65 protein as an autoimmune target in iMN. Considering the invasiveness and the resulting risk coming from renal biopsy, our ongoing aim is to set a procedure able to diagnose affected patients through a little- or non-invasive method such as blood sampling rather than biopsy.

Coexistence of different circulating anti-podocyte antibodies in membranous nephropathy

BACKGROUND AND OBJECTIVES

The discovery of different podocyte autoantibodies in membranous nephropathy (MN) raises questions about their pathogenetic and clinical meaning. This study sought to define antibody isotypes and correlations; to compare levels in MN, other glomerulonephritides, and controls; and to determine their association with clinical outcomes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Serum IgG(1), IgG(3), and IgG(4) against aldose reductase (AR), SOD2, and α-enolase (αENO) were measured at diagnosis in 186 consecutive MN patients, in 96 proteinuric controls (36 with FSGS, and 60 with IgA nephropathy), and in 92 healthy people recruited in four Italian nephrology units. Anti-phospholipase A2 receptor (PLA2r) and anti-neutral endopeptidase (NEP) IgG(4) were titrated in the same specimens. Association with 1-year follow-up clinical parameters was studied in 120 patients.

RESULTS

IgG(4) was the most common isotype for all antibodies; IgG(1) and IgG(3) were nearly negligible. IgG(4) levels were positive in a significant proportion of MN patients (AR, 34%; SOD2, 28%; αENO, 43%). Antibody titers were higher in MN than in healthy and pathologic controls (P<0.005). Anti-NEP IgG(4) did not differ from normal controls (P=0.12). Anti-PLA2r IgG(4) was detected in 60% of patients and correlated with anti-AR, anti-SOD2, and anti-αENO IgG(4) (P<0.001). In MN patients negative for the whole antibody panel (20%), 1-year proteinuria was lower compared with patients with at least one antibody positivity (P<0.05).

CONCLUSIONS

Our data suggest that IgG(4) is the prevalent isotype for antibodies against cytoplasmic antigens of podocytes (AR, SOD2, αENO). Their levels were higher than in other proteinuric glomerulonephritides and in normal controls and were correlated with anti-PLA2r. Only baseline negativity for all known antibodies predicted lower 1-year proteinuria.

Urine proteome analysis may allow noninvasive differential diagnosis of diabetic nephropathy

OBJECTIVE

Chronic renal insufficiency and/or proteinuria in type 2 diabetes may stem from chronic renal diseases (CKD) other than classic diabetic nephropathy in more than one-third of patients. We interrogated urine proteomic profiles generated by surface-enhanced laser desorption/ionization-time of flight/mass spectrometry with the aim of isolating a set of biomarkers able to reliably identify biopsy-proven diabetic nephropathy and to establish a stringent correlation with the different patterns of renal injury.

RESEARCH DESIGN AND METHODS

Ten micrograms of urine proteins from 190 subjects (20 healthy subjects, 20 normoalbuminuric, and 18 microalbuminuric diabetic patients and 132 patients with biopsy-proven nephropathy: 65 diabetic nephropathy, 10 diabetic with nondiabetic CKD [nd-CKD], and 57 nondiabetic with CKD) were run using a CM10 ProteinChip array and analyzed by supervised learning methods (Classification and Regression Tree analysis).

RESULTS

The classification model correctly identified 75% of patients with normoalbuminuria, 87.5% of those with microalbuminuria, and 87.5% of those with diabetic nephropathy when applied to a blinded testing set. Most importantly, it was able to reliably differentiate diabetic nephropathy from nd-CKD in both diabetic and nondiabetic patients. Among the best predictors of the classification model, we identified and validated two proteins, ubiquitin and β2-microglobulin.

CONCLUSIONS

Our data suggest the presence of a specific urine proteomic signature able to reliably identify type 2 diabetic patients with diabetic glomerulosclerosis.

Lipoprotein glomerulopathy treated with LDL-apheresis (Heparin-induced Extracorporeal Lipoprotein Precipitation system): a case report

Introduction

Lipoprotein glomerulopathy is a glomerulonephritis which was described for the first time by Saito in 1989 and is currently acknowledged as a separate nosological entity. It is histologically characterized by a marked dilatation of the glomerular capillaries and the presence of lipoprotein thrombi in the glomerular lumens. The dyslipidemic profile is similar to that of type III dyslipoproteinemia with Apolipoprotein E values that are often high; proteinuria and renal dysfunction are present. Proteinuria often does not respond to steroid and cytostatic treatments.

The phenotypic expression of lipoprotein glomerulopathy is most probably correlated to a genetic alteration of the lipoprotein metabolism (mutation of the Apolipoprotein E coding gene). In literature, lipoprotein glomerulopathies have mainly been reported in Japanese and Chinese subjects, except for three cases in the Caucasian race, reported in France and the USA.

Case presentation

We describe the case of a 60-year-old female, Caucasian patient suffering from lipoprotein glomerulopathy, carrier of a new mutation on the Apolipoprotein E gene (Apolipoprotein E_MODENA), and treated successfully with low density lipoprotein-apheresis with the Heparin induced extracorporeal lipoprotein precipitation system. After a first phase of therapeutic protocol with statins, the patient was admitted for nephrotic syndrome, renal failure and hypertension. Since conventional treatment alone was not able to control dyslipidemia, aphaeretic treatment with heparin-induced Extracorporeal Lipoprotein Precipitation - apheresis (HELP-apheresis) was started to maintain angiotensin converting enzyme inhibitor therapy for the treatment of hypertension. Treatment with HELP-apheresis led to a complete remission of the proteinuria in a very short time (four months), as well as control of hypercholesterolemia and renal function recovery.

Conclusion

According to this case of lipoprotein glomerulopathy, we believe that renal damage expressed by proteinuria correlates to the levels of lipids and, furthermore, the treatment with HELP-apheresis, by lowering low-density lipoprotein cholesterol and triglycerides, may be considered as a therapeutic option in synergy with pharmacological treatment in the treatment of lipoprotein glomerulopathy.

Primary IgA nephropathy is more severe in TGF-beta1 high secretor patients

BACKGROUND

IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide and is characterized by extremely variable clinical and morphological features and outcome. TGF-beta1 has a key role in fibrogenesis and the progression of renal damage. Its production is under genetic control.

METHODS

We recruited 105 Italian biopsy-proven IgAN patients for genotyping for the TGF-beta1 C-509T, T869C (COD 10) and G915C (COD 25) polymorphisms; 200 healthy blood donors were used as normal controls. Glomerular and interstitial mRNA levels of TGF-beta1 were assessed by real-time PCR in 34 patients to seek relationships with clinical, renal histopathological features and outcome.

RESULTS

The genotype distributions in the IgAN population were not statistically different from the controls. The COD 10 TT genotype was associated with more severe histological damage as assessed by Lee's classification (CC 50%, CT 39.6% and TT 17.2% were graded as mild; CC 35.7%, CT 43.7% and TT 44.8% as moderate, and CC 14.3%, CT 16.7% and TT 37.9% as severe [p=0.0049]) and with severe interstitial infiltrates (CC 10.4%, CT 35.2% and TT 54.2% [p=0.03]). A higher interstitial immunodeposition was observed for TGF-beta1, collagen IV and alpha-SMA in patients with the COD 10 T allele (p=0.045, p=0.049, p=0.032, respectively). The T allele was associated with significantly higher TGF-beta1 mRNA levels in the interstitium (TT+CT vs. CC: 0.52 +/- 0.16 vs. 0.18 +/- 0.10 copies/mL, respectively; p=0.000). The T allele was also associated with higher mRNA levels in glomeruli, though the difference was not statistically significant. Finally, the T allele was significantly associated with a worse prognosis, the end points being reached by 40% of TT+CT and 32% of CC patients (p=0.009).

CONCLUSIONS

In primary IgA nephropathy, the T allele of the TGF-beta1 COD 10 C/T polymorphism seems to be associated with more severe histological lesions, higher renal TGF-beta1 mRNA levels and a worse prognosis. This polymorphism seems to be functionally relevant and to have a prognostic impact.

Proteomic analysis of urine from proteinuric patients shows a proteolitic activity directed against albumin

BACKGROUND

Nephrotic syndrome is a condition that is clinically associated with poor outcome. In this study, we compared different techniques of urine sample preparation in order to develop a robust analytical protocol to define the differential urinary proteome of urinary abnormalities compared to nephrotic proteinuria.

METHODS

We recruited 5 normal control subjects, 16 patients with urinary abnormalities and 16 patients with nephrotic syndrome. Proteins from normal urine were processed using three different protocols [acetone, ultrafiltration and trichloroacetic acid (TCA) precipitation], depletion of albumin and IgGs and then analysed by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) gels and mass spectrometry.

RESULTS

Comparing the three extraction methods by visual inspection of gels after 2D gel electrophoresis, the acetone precipitation and TCA methods yielded the best quality of protein extraction, while the acetone precipitation method was the most efficient. Furthermore, we tested three commercial kits for albumin and IgG depletion. We applied the optimized acetone extraction protocol to compare urinary samples from nephrotic patients (NP) to urinary samples obtained from patients presenting with urinary abnormalities (UAP). We observed a proteolytic activity directed against albumin. This observation was more prevalent in urinary samples from NP than from UAP. Within both groups, there was some inter-individual variability in the observed proteolytic activity. An increased concentration of alpha1 antitrypsin was also observed in urine of NP. We analysed albumin fragmentation by 1D and 2D western blots in the same samples skipping the albumin and IgG depletion steps to avoid the possible confound of albumin fragment removal. The analysis confirmed a stronger proteolytic activity in the nephrotic group.

CONCLUSIONS

The proteolytic activity against albumin and the anti-proteolytic activity of alpha1 antitrypsin are likely linked and could play an important role in the nephrotic process. If replicated in larger samples, this methodology may lead to a better understanding of the underlying pathophysiological process of nephrotic syndrome.

[Autosomal dominant polycystic kidney disease: from genes to cilium]

Autosomal dominant polycystic kidney disease (ADPKD) is a quite frequent monogenic hereditary disease. The incidence has been reported to range between 1:400 and 1:1000 life births. The disease is caused by a mutation of the PKD1 gene in 85% of the cases and by a mutation of the PKD2 gene in the remaining 15%. The main characteristic of this condition is the development of renal cysts. Observations regarding various cystic kidney diseases sustained by mutations of different genes are steadily converging to a common point. This unifying element is the primary cilium. The cilium, which has long been considered a mere biological oddity, has lately become the focus of intense scientific attention because it may turn out to be the key to the understanding of cystic degeneration. The cilia can be regarded as sensors projecting out of the cell. In particular in the kidney they are located in an ideal place to capture information from the tubular lumen. One of the roles the cilia may play is the reception of chemical signals. An alternative hypothesis attributes to the cilia the role of mechanosensors capable of detecting variations of the urine flux in the tubular lumen. The cilium projects itself into the lumen where it can readily capture variations in the external environment and transmit them to the cell by as yet undefined pathways. This is the still largely unexplored frontier that will provide the elements needed to understand and treat renal cystic diseases.

A validated model of disease progression in IgA nephropathy

BACKGROUND

IgA nephropathy (IgAN) is the most common primary glomerulonephritis in the general population. There is accumulating evidence that immunosuppressive treatment is efficacious in IgAN. However, it is critical to define appropriate indicators for this therapy especially in the wake of potentially deleterious side effects to immunosuppressives.

METHODS

This study retrospectively reviewed IgAN cases collected since 1981 to identify clinical and/or histological parameters for disease progression; 310 patients with biopsy proven IgAN, diagnosed from January 1981 to March 2004, were included.

RESULTS

We defined a clinical prognostic index (CPI) using multivariate analysis, which incorporated these clinical/ histological parameters. Semiquantitative scores were assigned as follows: 2 points if creatinine (Cr) was >1.4 mg/dL, 1 point if proteinuria was >1 g/24 hr, 1 point if a patient was affected by hypertension, and 1 point if a patient was older than 30 yrs. Dividing our population into two groups (scores 0-2 = low CPI group; scores 3-5 = high CPI group), we demonstrated a significantly different 10-yr renal survival rate; in the low CPI group, renal survival since time of biopsy at 10 yrs was 91.7%; in the high CPI group the renal survival at 10 yrs was 35%. We validated the CPI in an independent sample from Verona (validation group) and demonstrated similar results for the CPI.

CONCLUSIONS

The CPI is convenient to use for defining the risk of disease progression.

Precocious activation of genes of the renin-angiotensin system and the fibrogenic cascade in IgA glomerulonephritis

BACKGROUND

The renin-angiotensin system (RAS) seems to play a pivotal role in progression of immunoglobulin A (IgA) nephropathy (IgAN). Accordingly, in patients with IgAN a relationship between the RAS and the fibrogenic cascade triggered by transforming growth factor-beta1 (TGF-beta1) should be observed. This study was carried out to obtain deeper insight into the regulation of RAS and the interaction with TGF-beta1 in the diseased kidney.

METHODS

Twenty renal biopsies from IgAN patients and five from renal cancer patients (controls) were analyzed in both microdissected glomerular and tubulointerstitial compartments by reverse transcription-polymerase chain reaction (RT-PCR). All patients had normal renal function. The expression of the following genes was determined: angiotensinogen (Agtg), renin, angiotensin-converting enzyme (ACE), angiotensin II (Ang II) type 1 and type II (AT1 and AT2 receptors), TGF-beta1, collagen IV (Coll IV), alpha-smooth muscle actin (alpha-SMA). Quantitative data were confirmed for TGF-beta1 and ACE genes by real-time PCR. Results. RAS genes were overexpressed in IgAN patients vs. control subjects. There was no difference between glomerular and tubulointerstitial RAS gene expression levels. On the contrary, the overactivation of fibrogenic cascade genes (TGF-beta1, Coll IV, alpha-SMA) in the tubulointerstitium was observed (TGF-beta1, glomerular 0.14 +/- 0.10 SD; tubulointerstial 0.34 +/- 0.20; P = 0.000) (alpha-SMA, glomerular 0.08 +/- 0.07; tubulointerstitial 0.35 +/- 0.19; P = 0.000) (Coll IV, glomerular 0.12 +/- 0.11; tubulointerstitial 0.22 +/- 0.10; P = 0.03). This fibrogenic cascade seems to be triggered by RAS as indicated by statistically significant correlations between the expression of their respective genes. A direct relationship between the putative Ang II activity and the expression of AT receptor genes was found in the tubulointerstitium, whereas in the glomeruli this relationship was negative. In the interstitium, statistically significant positive relationships emerged between interstitial infiltrates and the gene expression of Agtg, AT1 receptor, Coll IV, and TGF-beta1.

CONCLUSION

This study demonstrates that a tight regulation of the intrarenal RAS exists in IgAN and that it follows the general rules disclosed in animal models. Moreover, the RAS seems to be activated early in the diseased kidney and it appears that such activation drives inflammation and a parallel stimulation of the TGF-beta fibrogenic loop, particularly at the tubulointerstitial level.

Epidermal growth factor receptor polymorphism and autosomal dominant polycystic kidney disease

BACKGROUND

The clinical variability in the rate of progression of autosomal dominant polycystic kidney disease (ADPKD) has been attributed to genetic heterogeneity, though environmental factors and modifying genes very likely play an important role as well. We examined the association between clinical outcome, defined by age at onset of end-stage renal disease (ESRD) in 46 ADPKD patients, and a polymorphism in the epidermal growth factor receptor (EGFR) gene, a candidate modifying gene. EGFR is a key element in renal tubular proliferation.

METHODS

This study comprised 46 unrelated patients with ADPKD and ESRD, and 58 healthy controls. The patients had prevalently PKD 1 mutations. The EGFR microsatellite polymorphism was genotyped according to Gebhardt et al (11).

RESULTS

The allele frequencies of the EGFR polymorphism were different in the ADPKD sample and the control population (G2=17.19; P=0.009). In particular, the frequencies of the 122 and 118bp length alleles had a different distribution (P=0.010 and P=0.047 respectively). Patients with the 122bp length polymorphism had ESRD at an earlier age,but this finding was not statistically significant.

CONCLUSIONS

These findings suggest an association between the EGFR microsatellite polymorphism and ADPKD. However, it is difficult to establish which alleles are protective and which harmful. A larger, multicenter study may help clarify these results and is also required to replicate our preliminary finding of an association between ADPKD and the EGFR polymorphism.

Liver and kidney foreign bodies granulomatosis in a patient with malocclusion, bruxism, and worn dental prostheses

Granulomatous reactions caused by foreign bodies have been described in drug abusers, in subjects exposed to occupational pollutants, and more rarely, in association with the use of prosthetic devices. We describe a 62-year-old patient with multiorgan parenchymal granulomatosis caused by inorganic debris of unknown origin. The patient presented with fever, hepatosplenomegaly, progressive cholestasis, and acute renal failure. Liver and kidney biopsies showed the presence of noncaseating epithelioid giant-cell granulomas containing scattered polarizable particles. Similar particles were also present in stools. Studies by innovative scanning electron microscopy and energy-dispersive microanalytical techniques showed that the particles isolated in liver, kidney, and stools were made by feldspars, the main component of porcelain. No occupational or environmental exposure to these materials could be identified in this patient and the only reliable source of the porcelain debris turned out to be constituted by 2 dental bridges evidently worn because of a possible inappropriate construction, malocclusion, and bruxism. The porcelain of the dental prostheses had the same elemental spectrum of the particles isolated from stool specimens and liver-kidney granuloma. After identification of the dental prostheses as the most likely source of ceramic debris, and after their removal, the particles from stool specimens disappeared. The patient was then treated with steroids leading to a remission of the clinical symptoms and a decrease in granulomatous inflammatory reaction in both liver and kidney. This is the first report suggesting that a foreign body systemic granulomatosis can be associated with worn dental prostheses.

Androgen responsiveness and intrarenal localization of transcripts coding for the enzymes of polyamine metabolism in the mouse

Polyamines, spermidine (SPD), and spermine (SPM) are intracellular polycations required for cell growth and differentiation. Their biosynthetic precursor, the diamine putrescine (PUT), is produced by regulatory ornithine decarboxylase (ODC). Spermidine/spermine N1-acetyltransferase (SSAT) is the ODC counterpart in the degradation pathway which retroconverts SPM and SPD into PUT. Castration of male mice for 7 days resulted in a 40% decrease of the renal levels of both SSAT and ODC transcripts. Administration of 5-alpha-dihydrotestosterone (DHT) to castrated mice for the last 3 days before sacrifice caused the levels of ODC and SSAT mRNAs to increase by 250% and 180%, respectively. Thus activation of the retroconversion pathway of polyamine metabolism appears to contribute towards the increase in PUT production known to be caused by androgens in the mouse kidney. In situ hybridization histochemistry experiments showed that the SSAT transcript is expressed only by the epithelial cells of the straight and convoluted distal tubules of the nephron, while the expression of the ODC transcript is confined to the epithelium of the convoluted and straight portion of the proximal tubules. The separation of the biosynthetic from the degradation pathway along the nephron suggests that PUT is mostly produced in the distal tubule, where it may play a physiological role, independent of androgen action, in protecting tubular cells from the very low osmolarity to which they are exposed in this nephron segment.

Infection of circulating CD34+ cells by HHV-8 in patients with Kaposi's sarcoma

Human herpesvirus type 8 (HHV-8) has been identified as the most likely candidate to be involved in the development of Kaposi's Sarcoma (KS). HHV-8 has been associated with all forms of KS, primary effusion lymphoma, and multicentric Castleman's disease and detected in various non-neoplastic cells. Its presence in cells of the different hemopoietic lineages has not yet been investigated in a comprehensive and systematic manner. In this study we searched for the presence of HHV-8 in different subpopulations of peripheral blood mononuclear cells (PBMC) from patients with classic and AIDS-associated KS, as well as from HIV-1 sero-positive and sero-negative persons without KS. Thirty-four samples of PBMC were isolated from 30 patients. Subpopulations were isolated with immunomagnetic beads. Polymerase chain reaction for HHV-8 DNA was performed on PBMC and subpopulations with a primer pair selected from ORF26 of the viral genome. Polymerase chain reaction products were subsequently Southern blotted and hybridized. In patients with KS, HHV-8 DNA was detected in nine of 11 (81%) CD19+ cells, four of 11 (36%) CD2+ cells, three of 11 (27%) CD14+ cells, and nine of 11 (81%) of the remaining depleted cell populations (DP) that contain CD34 positive cells. In a subsequent set of experiments HHV-8 DNA was detected in 10 of 12 (83%) CD34 positive cell fractions. All cell subpopulations from the non-KS group were HHV-8 negative, with the exception of one positive B cell sample obtained from an HIV-infected patient. Our data demonstrate that in peripheral blood HHV-8 is detectable not only in CD19+ cells, as previously reported, but also in other cells, including T cells, monocytes, and cells devoid of specific lineage markers. We also show for the first time that CD34+ cells in peripheral blood of KS patients are a predominant HHV-8-harboring population, suggesting that they represent an additional important reservoir for this virus in vivo.

Acute renal failure of medical type in an elderly population

One hundred and nine unselected patients with Acute Renal Failure (ARF) of medical aetiology were hospitalized at the Nephrological Unit of Policlinico University Hospital (Modena) during a 30-month period. ARF was considered as a rapid increase of serum creatinine > 2mg/dl over the baseline level or the doubling of pre-existing value in chronic renal failure. Mean age of patients was 67+/-17 years and median age was 72; 64.2% needing dialytic treatment. Four main causes of ARF were identified: 33 patients had reduced renal perfusion by dehydration, hypotension etc.; 20 multifactorial aetiology; 14 biopsy-investigated renal parenchymal diseases and 39 had drug-related acute renal failure (D-ARF). The clinical outcome was significantly worse in elderly patients as regard mortality (P < 0.02), chronic dialytic treatment (P < 0.04) and complete recovery (P < 0.004). The mean age of D-ARF patients was significantly greater than remaining ARF patients (72.6+/-12.8 vs 63.2+/-18.5: P < 0.004. Nonsteroidal antiinflammatory drugs (NSAIDs) and ACE-inhibitors (Ace-i) caused ARF in 24 and 8 patients respectively. Elderly age, vascular disease and monoclonal gammopathy represented the main risk factors and were significantly more frequent in D-ARF patients (P<001, <0.01, <0.04 respectively). Our data confirm the high susceptibility of ageing kidneys to nephrotoxic damage caused by drugs affecting glomerular autoregulation by microvascular mechanisms. Greater attention to renal changes in ageing and an increased dissemination of preventative measures among nephrologists, could reduce the incidence of these serious and potentially lethal diseases.

Human immunodeficiency virus type 1 glycoprotein 120-specific T lymphocytes provide intermolecular help for anti-CD4 autoantibody production in exposed uninfected subjects

Anti-CD4 antibodies have been documented in about 10-20% of HIV-infected patients. This autoimmune response could be triggered by increased CD4 processing and unveiling of hidden (cryptic) epitopes. Multiple markers of exposure to HIV have been described in exposed uninfected individuals. Here, we investigated the mechanisms underlying the generation of anti-CD4 antibodies in a cohort of 54 seronegative exposed uninfected individuals. We identified anti-CD4 antibodies above normal levels in 16 of 47 (34%) exposed uninfected subjects. The fine specificity of these antibodies was different in this cohort when compared with those found in HIV+ patients. This suggested the possibility of different mechanisms underlying the generation of anti-CD4 antibodies in these two groups. Indeed, in exposed uninfected subjects, we found circulating CD4 T cells specific for gp120, but not for CD4. In contrast, HIV-1-seropositive patients had peripheral blood T cells specific for both molecules. Noncovalent binding of gp120 to soluble CD4 enhanced activation of gp120-specific T lymphocytes in exposed uninfected subjects, but not in HIV+ subjects. Moreover, gp120-specific T cells isolated from exposed uninfected, but not from HIV+, subjects provided help for anti-CD4 antibody production by B cells pulsed with CD4-gp120 complex. We conclude that gp120-specific T cells are present in exposed uninfected individuals, and can provide intermolecular help for anti-CD4 antibody production. This mechanism is distinct from that found in HIV-1-seropositive patients and may play a protective role against HIV-1 infection in vivo.

Antigen-driven C-C chemokine-mediated HIV-1 suppression by CD4(+) T cells from exposed uninfected individuals expressing the wild-type CCR-5 allele

Despite repeated exposure to HIV-1, certain individuals remain persistently uninfected. Such exposed uninfected (EU) people show evidence of HIV-1-specific T cell immunity and, in rare cases, selective resistance to infection by macrophage-tropic strains of HIV-1. The latter has been associated with a 32-base pair deletion in the C-C chemokine receptor gene CCR-5, the major coreceptor of macrophage-tropic strains of HIV-1. We have undertaken an analysis of the HIV-specific T cell responses in 12 EU individuals who were either homozygous for the wild-type CCR-5 allele or heterozygous for the deletion allele (CCR-5Delta32). We have found evidence of an oligoclonal T cell response mediated by helper T cells specific for a conserved region of the HIV-1 envelope. These cells produce very high levels of C-C chemokines when stimulated by the specific antigen and suppress selectively the replication of macrophage-tropic, but not T cell-tropic, strains of HIV-1. These chemokine-producing helper cells may be part of a protective immune response that could be potentially exploited for vaccine development.

Increased plasma levels of the C-C chemokine RANTES in patients with primary HIV-1 infection

To investigate the role played by chemokines in the natural history of human immunodeficiency virus (HIV) infection, we measured the plasma levels of RANTES. MIP-1 alpha and MIP-1 beta in a cohort of patients with primary HIV-1 infection (PHI) followed longitudinally. The cohort included 17 patients with well-documented history of acute HIV syndrome within two months of the first observation. The mean plasma concentration of RANTES, but not that of MIP-1 alpha or MIP-1 beta, was significantly higher in patients with PHI (192.3 ng/ml) than in five HIV-seronegative controls (8.0 ng/ml) studied during the same time period. Treatment of blood with a cocktail of drugs preventing platelet activation, followed by high-speed centrifugation, reduced the levels of RANTES by approximately 2 logs both in patients and in controls, indicating that the bulk of RANTES was released by platelets, which are known to store this chemokine in their alpha-granules, in the immediate aftermath of blood drawing. No correlation was seen between the levels of RANTES and the number of HIV genome equivalents in plasma. These data suggest that large amounts of pre-formed RANTES are stored in platelets and, possibly, in other blood cells during the early phases of HIV infection. The possible role of this HIV-suppressive chemokine in the control of viral replication during PHI remains to be established.

Heterogeneity in exposed uninfected individuals

In spite of repeated exposures to HIV, some individuals remain seronegative and apparently uninfected. A variety of mechanisms potentially able to confer resistance to HIV infection, including cell-mediated and (unconventional) humoral immune responses, as well as mutations affecting receptors for virus entry have been considered and analysed. In this article, we want to discuss recent reports on specific immune responses and genetic factors potentially involved in mechanisms of protection, and to present some of our data relative to a cohort of people sexually exposed to HIV-1, but persistently seronegative. These EU (exposed uninfected) individuals can be distinguished from "normal" unexposed controls on the basis of significantly increased frequencies of a number of immunological parameters that might be considered "unconventional" correlates of HIV infection/protection. However, EU individuals are highly heterogeneous since the various unconventional immune responses considered can be present in all possible combinations. Aim of future research will be to ascertain the role of such immune responses in the maintenance of the protection state, or their secondary nature as signals of a particular kind of infection.

HIV-1-specific immunity in persistently seronegative individuals at high risk for HIV infection

A growing number of reports indicates that certain groups of individuals who almost certainly have been exposed to human immunodeficiency virus (HIV), yet continue to exhibit no signs or symptoms of infection, often have subtle evidence of specific immunity. We studied such a high-risk (HR) cohort of persistently seronegative individuals with histories of long-term sexual exposure to an HIV-infected partner to look for evidence of both humoral and cellular immunity that might have been induced by exposure to the virus. Twenty-three heterosexual and four homosexual monogamous couples with discordant HIV status were included in the study. Twelve of the HR partners were studied for in vitro stimulation of peripheral blood mononuclear cells (PBMC) by HIV envelope-derived peptides. All 12 responded overwhelmingly to a peptide containing the fifth conserved region of gp120. By generating and cloning T cell lines specific for this peptide, we concluded that in these individuals the T cell response to the envelope is mainly focused on the carboxy-terminus region of gp120 and is characterized by an oligoclonal expansion of CD4+ T cells expressing the same TCR Eighteen HR partners and 37 HIV-1 seropositive subjects were tested for the presence of anti-CD4 antibodies (anti-CD4 Abs) using a recombinant CD4-based enzyme-linked immunosorbent assay (ELISA). Anti-CD4 Abs were detected in eight of the HR partners (six confirmed by Western blot) and in nine of the HIV-1 seropositive subjects (eight confirmed by Western blot). Results from binding competition assays with a panel of monoclonal anti-CD4 Abs suggested that the anti-CD4 Abs detected in the HR partners are directed toward epitopes that are induced by gp120 binding. Twenty-seven of the HR partners were tested for the presence of antibodies that cross-react with HLA class I and gp120 (anti-HLA Abs). Anti-HLA Abs were detected in 16 of the HR partner sera and in 4/94 sera from a control population of normal healthy blood donors. Taken together, the results suggest that in some individuals with a history of long-term exposure to HIV, specific immunity may develop in the absence of overt infection. The common trigger for these responses is gp120.

Beta-1 integrins in the normal human glomerular capillary wall: an immunoelectron microscopy study

The localization of the alpha 2, alpha 3 and alpha 6 subunits of the beta 1 integrin family on different cells of the glomerular capillary wall and on juxta-capillary mesangium was investigated using an immunoelectron microscopic technique on freshly harvested normal human glomeruli. Alpha 2 beta 1, alpha 3 beta 1 and alpha 6 beta 1 were weakly expressed on both luminal and abluminal surfaces of glomerular endothelial cells; alpha 2 beta 1 and alpha 3 beta 1 were also found on the mesangium of the juxta-capillary areas. Alpha 3 beta 1 was regularly present in great density on the basal and lateral surface of podocyte foot processes, confirming alpha 3 beta 1 as the unique beta 1 integrin on glomerular epithelial cells. None of these integrins was strictly polarized along the glomerular basement membrane, thus suggesting, in agreement with recent literature, that these molecules perform other biological functions in addition to adhesivity.

Cloning and expression of a cDNA for the human prostaglandin E receptor EP1 subtype

A functional cDNA clone coding for the human prostaglandin E receptor EP1 subtype has been isolated from a human erythroleukemia cell cDNA library probed by low-stringency hybridization using a polymerase chain reaction fragment of the human thromboxane receptor. The human EP1 receptor is comprised of 402 amino acids with a predicted molecular mass of 41,858 and has the topography common to all G-protein-coupled receptors with seven predicted transmembrane spanning domains. Prostaglandin (PG) E2 challenge of Xenopus oocytes injected with EP1 cDNA resulted in an increase in intracellular Ca2+. In addition, the rank order of potency for prostaglandins in competition for [3H]PGE2 specific binding to membranes prepared from EP1 cDNA transfected COS cells was PGE2 > PGE1 > PGF2 alpha > PGD2. Furthermore, the EP1 receptor-selective antagonists AH 6809 and SC19220 were more potent than the EP2 receptor-selective agonist butaprost in these competition binding assays. In summary, therefore, we have cloned the human EP1 receptor subtype which is functionally coupled to an increase in intracellular Ca2+.

Point mutation in the seventh hydrophobic domain of the human thromboxane A2 receptor allows discrimination between agonist and antagonist binding sites

Thromboxane A2, a potent platelet agonist and vasoconstrictor, exerts its actions via specific G protein-coupled receptors. cDNAs encoding the full length thromboxane receptor have been isolated from human placenta mRNA by reverse transcriptase-polymerase chain reaction. An expression construct, under control of the cytomegalovirus promoter, was introduced into human embryonic kidney 293 cells. Membranes from transfected cells bound the thromboxane antagonist SQ29,548 and the agonist [15-(1 alpha,2 beta(5z)-3 alpha(1E,3S)-4 alpha)]-7-[3-(3-hydroxy-4-(p- iodophenoxy)-1-butenyl)-7-oxabicyclo[2,2,1]hept-2-yl]-5-heptenoic acid) with high affinities, and significantly more receptors were expressed in these cells, compared with platelet preparations. The putative seventh transmembrane segment is highly related in all cloned members of the eicosanoid receptor family and forms a critical portion of the ligand binding pocket for G protein-coupled receptors. Several point mutations in this segment were generated. Binding of SQ29,548 was virtually abolished in cells transfected with all the variant receptor constructs. However, one receptor variant (TxR-W299L), in which a tryptophan at position 299 was substituted for a leucine residue, allowed a definite discrimination between agonist and antagonist binding sites in competition and saturation binding experiments. An antibody directed toward the third intracellular loop of the thromboxane receptor was able to immunoprecipitate native thromboxane receptor in solubilized membranes from human erythroleukemia cells and transfected cells.

Very late activation-3 integrin is the dominant beta 1-integrin on the glomerular capillary wall: an immunofluorescence study in nephrotic syndrome

The expression of alpha 2; alpha 3; alpha 5; alpha 6-subunits of the beta 1 [very late activation (VLA)] integrin family was studied in kidney specimens using an immunofluorescent technique. 6 specimens from normal kidney were compared with 10 specimens from patients affected by various glomerulopathies [minimal change nephropathy (MCN), membranous nephropathy (MN) and systemic lupus erythematosus nephritis (SLEN)]. On normal glomeruli, alpha 3 was the dominant integrin, being mainly present on podocytes and showing a linear fluorescent pattern codistributed with laminin. In MCN and SLEN, alpha 3 presented a normal pattern. In MN, alpha 3 revealed a trabecular picture on thickened glomerular basement membranes. Moreover, in stage-III MN, a segmental loss of alpha 3-integrin was detected. In our opinion, VLA-3 may offer an interesting approach to the study of the relationships between podocytes and their substrate.

Heterogeneity of prostaglandin H2/thromboxane A2 receptors: distinct subtypes mediate vascular smooth muscle contraction and platelet aggregation

Studies of the hierarchies of agonist and antagonist affinity for the prostaglandin (PG)H2/thromboxane (Tx)A2 receptor have been performed to establish whether distinct receptor subtypes exist in platelets and vascular smooth muscle cells (VSMC). They have yielded conflicting results. The pattern of homologous desensitization of phospholipase C activation and [Ca++i] increase induced by the PGH2/TxA2 agonist U46619 in rat aortic SMC was similar to that previously observed in human platelets: rapid desensitization of both responses followed by a delayed loss of binding sites from the cell membrane. Recently, the pattern of receptor inactivation by the antagonist ligand, GR 32191, has identified two subtypes in platelets. GR 32191 binds reversibly (GRr) to a site that mediates platelet shape change and an increase [Ca++i] and irreversibly (GRirr) to a site linked to phospholipase C activation and aggregation. In contrast to platelets, studies of ligand dissociation only identified GRr sites in rat aortic SMC and GR 32191 failed to inactivate PGH2/TxA2 receptors as detected by the PGH2/TxA2 receptor antagonist, [3H]SQ 29548. Inhibition of U46619-induced contraction of both rat aortic and human saphenous vein was competitive, consistent with the absence of GRirr sites in VSMC. Platelet activating factor, which heterologously desensitizes U46619-evoked phospholipase C activation in platelets, had no such effect in VSMC. The biochemical events attendant to PGH2/TxA2 receptor desensitization are similar in SMC and platelets. However, both the pattern of receptor inactivation by GR 32191 and of heterologous desensitization by PAF, suggest that VSMC lack the receptor subtype that transduces aggregation of platelets.

Molecular cloning, primary structure, and expression of the human platelet/erythroleukemia cell 12-lipoxygenase

The major pathway of arachidonic acid metabolism in human platelets proceeds via a 12-lipoxygenase enzyme; however, the biological role of the product of this reaction, 12-hydro(pero)xyeicosatetraenoic acid [12-H(P)ETE], is unknown. Using a combination of the polymerase chain reaction and conventional screening procedures, we have isolated cDNA clones encoding the human platelet/human erythroleukemia (HEL) cell 12-lipoxygenase. From the deduced primary structure, human platelet/HEL 12-lipoxygenase would encode a Mr 75,000 protein consisting of 663 amino acids. The cDNA encoding the full-length protein (pCDNA-121x) under the control of the cytomegalovirus promoter was expressed in simian COS-M6 cells. Intact cells and lysed-cell supernatants were able to synthesize 12-H(P)ETE from arachidonic acid, whereas no 12-H(P)ETE synthesis was detected in mock-transfected cells. A single 2.4-kilobase mRNA was detected in erythroleukemia cells but not in several other tissues and cell lines evaluated by Northern blot analysis. Comparison of the human platelet/HEL 12-lipoxygenase sequence with that of porcine leukocyte 12-lipoxygenase and human reticulocyte 15-lipoxygenase revealed 65% amino acid identity to both enzymes. By contrast, the leukocyte 12-lipoxygenase is 86% identical to human reticulocyte 15-lipoxygenase. Sequence data and previously demonstrated immunochemical and biochemical evidence support the existence of distinct 12-lipoxygenase isoforms. The availability of cDNA probes for human platelet/HEL cell 12-lipoxygenase should facilitate elucidation of the biological role of this pathway.

Induction of prostacyclin receptor expression in human erythroleukemia cells

We have identified both high-affinity (KD = 36 +/- 3 nM) and low-affinity (KD = 2.1 +/- 0.8 microM) prostacyclin (PGI2)-receptor sites on human erythroleukemia (HEL) cells using the radiolabelled prostacyclin analogue. [3H]iloprost. The addition of the phorbol ester, TPA, to the culture medium caused a 5-10-fold increase in the number of both the low- and the high-affinity sites, without any change in their affinity constants. Iloprost stimulated HEL cell membrane adenylate cyclase activity 5-fold. This stimulation was potentiated in the presence of GTP, indicating a conventional PGI2 receptor-G2-adenylate cyclase system. HEL cells represent a source of prostacyclin receptor mRNA which may be of value in expression cloning of this receptor.

Increased urinary excretion of thromboxane B2 and 2,3-dinor-TxB2 in cyclosporin A nephrotoxicity

Cyclosporin A (CsA) administration to rats is associated with a selective increase in urinary excretion of immunoreactive thromboxane B2 (i-TxB2), the stable breakdown product of TxA2. The exaggerated synthesis of TxA2 may play a role in the reduction of glomerular filtration rate (GFR) observed both in animals and humans undergoing CsA treatment. The present study was designed to get further insight into the origin of the abnormal i-TxB2 urinary excretion. Rats given orally CsA (50 mg/kg/day) for 30 days had a significant increase in the urinary excretion of both 2,3-dinor-TxB2 and TxB2 measured by technique of capillary column gas chromatography-negative ion chemical ionization mass spectrometry (HRGC-NICIMS). Urinary TxB2 is more likely to reflect the renal synthesis of the parent compound, whereas 2,3-dinor-TxB2 is considered to reflect the amount of TxB2 formed in the circulation. Experiments in isolated perfused kidney (IPK) taken from animals given CsA for 30 days showed a lower percentage increase in urinary TxB2 over vehicle treated animals. Moreover in IPK the ratio 2,3-dinor-TxB2/TxB2 was lower than in vivo. The amount of i-TxB2 detectable in serum of animals given CsA was not different from that of control animals. In contrast, isolated glomeruli taken from rats given CsA had an increase in their TxA2 synthesis measured as i-TxB2 in the supernatants. Ultrastructural studies on kidney specimens from animals given CsA showed a focal glomerular endothelial damage together with a marked infiltration of blood borne cells of monocyte-macrophage type in the glomerular tuft. In contrast, kidney specimens taken from IPK preparations were devoid of inflammatory cells. In vitro CsA did not interfere with platelet arachidonic acid (AA) metabolism as shown by a normal i-TxB2 generation in vitro by rat platelet-rich plasma (PRP) exposed to CsA and then challenged with AA or ADP. Similarly isolated glomeruli and isolated proximal tubules from normal rats when challenged with CsA in vitro converted AA into TxA2 normally. It is suggested that the cause of the increased urinary excretion of 2,3-dinor-TxB2 is the consequence of intrarenal platelet and macrophage activation, probably triggered by the endothelial damage. The parallel increase in the urinary excretion of unmetabolized TxB2 is likely to reflect a concomitant activation of resident renal cell AA metabolism induced by CsA.

Prognostic factors and effectiveness of treatment in acute renal failure due to multiple myeloma: a review of 50 cases. Report of the Italien Renal Immunopathology Group

We studied 50 patients with myeloma acute renal failure to investigate possible prognostic factors and to evaluate the effectiveness of the various treatment schedules used. Renal failure was reversible 1 month after the onset in 50% of the patients considered. The patients treated with chemotherapy and plasma exchange recovered renal function more frequently (61% of the cases) than those treated only with chemotherapy (27%). The most important clinical prognostic factors were total proteins, serum creatinine values and myeloma type. Considering the histological findings, the prognosis correlated with the severity of the lesions and number of tubular casts. Survival at 1 year was higher in the patients who regained renal function than in those in whom renal function did not improve.

Cyclosporin-induced endothelial cell injury

The administration of Cyclosporin-A (CyA) to animals and humans may induce an arteriolar damage. It has also been reported that CyA in some instances may cause an hemolytic uremic-like syndrome. This is a syndrome of vascular damage with thrombotic occlusions of the microcirculation. Endothelial injury is considered the first event in the pathogenetic cascade leading to hemolytic-uremic syndrome. We have used bovine aortic endothelial cells in culture to address the issue of CyA-induced arteriolar damage. Exposure of endothelial cells to different concentrations of CyA induced a time- and dose-dependent cell injury in vitro. The damage induced by CyA was characterized by an early cell detachment from culture substrate followed by cell lysis as documented by the increase in lactate dehydrogenase (LDH) and 51Cr release. Both detachment and lysis were negligible after short-term incubation of 1 microM CyA with endothelial cells. One micromolar CyA only induced lysis if incubations were prolonged above 6 hours. Ten and 50 microM CyA both induced marked endothelial cell detachment and lysis; lysis started 3 hours after incubation of endothelial cells with CyA and was maximal at the end of 24 hours incubation. CyA-induced injury was associated with dose- and time-dependent increase in prostacyclin and thromboxane A2 release by endothelial cells exposed to CyA independently from the concentrations of CyA used. CyA-induced generation of prostacyclin and thromboxane A2 was inhibited when the incubations were performed in the presence of aspirin (500 microM). These studies indicate that CyA exerts a direct cytotoxic effect on endothelial cells and might help in understanding the pathogenesis of CyA-induced vascular damage.