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International audience; Carcinogenic risk of tattoo inks remains unclear, and their composition is poorly regulated. Various types of carcinogenic compounds can be found in tattoo inks, including primary aromatic amines (PAA), cleavage products of organic azo colourants, found in coloured inks.1 Many cases of skin cancers occurring within tattoos have been reported, including cases of keratoacanthoma (KA) developed on red ink.2 Pathogenesis of KA on tattoos remains unclear and is probably due to multiple factors: trauma induced by the needle during the tattoo itself, inflammatory reactions, ultraviolet radiation, direct carcinogenicity of the tattoo inks and individual background

International audience; Thyroid calcification is frequent in thyroid nodules. The aim of our study was to evaluate the prevalence of calcifications in thyroid tissue samples of patients with various thyroid diseases , and to identify their composition according to their localization. Among 50 thyroid samples included, 56% were malignant (papillary carcinoma) and 44% were benign (ade-noma, multinodular goiter, Graves' disease, sarcoidosis). Calcifications were found in 95% of samples using polarised light microscopy, whereas only 12% were described in initial pathological reports. Three types were individualised and analyzed by infrared spectrometry (μFTIR): colloid calcifications composed of calcium oxalate, capsular calcifications and psammoma bodies, both composed of calcium phosphate. Of notice, psammoma bodies characterized by FE-SEM were composed of concentric structure suggesting a slow process for crystal deposition. Calcium phosphates were found only in malignant samples whereas calcium oxalate was not associated with a define pathology. Proliferation assessed by KI67 staining was high (33% of positive follicles), and RUNX2, OPN, and CD44 positive staining were detected in thyrocytes with a broad variation between samples. However, thyr-ocyte proliferation and differentiation markers were not associated with the number of crystals. TRPV5 and CaSR expression was also detected in thyrocytes. mRNA transcripts expression was confirmed in a subgroup of 10 patients, altogether with other calcium transporters such as PMCA1 or Cav1.3. Interestingly, TRPV5 mRNA expression was significantly associated with number of colloid calcifications (rho =-0.72; p = 0.02). The high prevalence of calcium oxalate crystals within colloid gel raises intriguing issues upon follicle physiology for calcium and oxalate transport.

International audience; BACKGROUND: Sarcoidosis, characterized by epithelioid granulomas, is considered to be caused by a complex interplay between genetics and environmental agents. It has been hypothesized that exogenous inorganic particles as crystalline silica could be a causal or adjuvant agent in sarcoidosis onset.OBJECTIVES: To investigate the location, frequency and physicochemical characteristics of foreign materials and mineral tissue deposits in the granulomatous area of cutaneous sarcoidosis.METHODS: Skin biopsies (n = 14) from patients diagnosed with cutaneous sarcoidosis (mean age 43 years; 11 patients with extracutaneous involvement) were investigated using polarized light examination (PLE), μFourier Transform Infra-Red (μFT-IR) spectroscopy and Field Emission Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (FE-SEM/EDX).RESULTS: Combined PLE, μFT-IR, FE-SEM/EDX analysis allowed to characterize mineral deposits in 7/14 biopsies (50%). It identified crystalline silica (SiO2 ) inside granulomas in three biopsies and calcite (CaCO3 ) at their periphery in 4.CONCLUSION: This study emphasizes the need of using combined methods for assessment of mineral deposits in granulomatous diseases. According to the location and characteristics of deposits, we can hypothesize that SiO2 particles contribute to the granuloma formation, whereas CaCO3 deposits are related to the granuloma biology. However, the significance of the association between SiO2 deposits and sarcoidosis is still disputed.

International audience; Vancomycin is a widely prescribed antibiotic, but the exact nature of vancomycin-associated nephrotoxicity is unclear, in particular when considering the frequent coadministration of aminoglycosides. We describe here the initial case of a 56-year-old woman with normal renal function developing unexplained ARF without hypovolemia after administration of vancomycin without coadministration of aminoglycosides. Studying the patient’s renal biopsy specimen, we ascertained that obstructive tubular casts composed of noncrystal nanospheric vancomycin aggregates entangled with uromodulin explained the vancomycin-associated ARF. We developed in parallel a new immunohistologic staining technique to detect vancomycin in renal tissue and confirmed retrospectively that deleterious vancomycin-associated casts existed in eight additional patients with acute tubular necrosis in the absence of hypovolemia. Concomitant high vancomycin trough plasma levels had been observed in each patient. We also reproduced experimentally the toxic and obstructive nature of vancomycin-associated cast nephropathy in mice, which we detected using different in vivo imaging techniques. In conclusion, the interaction of uromodulin with nanospheric vancomycin aggregates represents a new mode of tubular cast formation, revealing the hitherto unsuspected mechanism of vancomycin-associated renal injury.

Because genetic background plays a pivotal role in humans and in various experimental models, we carefully monitored its impact on glomerular pathological characteristics during experimental anti-glomerular basement membrane glomerulonephritis (anti-GBM-GN), using two leading mouse strains, 129S2/SvPas (129Sv) and C57bl/6J (B6J). These mice exhibited different severities of renal failure, hypertension, and glomerular lesions, according to their genetic background. In addition to the classic glomerular proliferative lesions, glomerular thrombotic microangiopathy (TMA) was found as a common genetic background-dependent histopathological hallmark of anti-GBM-GN, combined with hemolytic anemia and thrombocytopenia. Glomerular expression profiling, using microarrays and Western blot analysis in B6J TMA-resistant and 129Sv TMA-prone mice, demonstrated major differences in vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) 2 pathways, despite similar Vegfa expression levels. Further analysis revealed a lower basal glomerular endothelial Vegfr2 expression level in 129Sv TMA-prone mice compared with B6J TMA-resistant mice. This difference was even more pronounced during anti-GBM-GN, explaining why an exogenous VEGFA supply failed to rescue any 129Sv TMA lesions. Conversely, the systemic blocking of Vegfr2 amplified TMA lesions only in B6J mice. Herein, we specified the role that genetic background plays in determining, in particular, the level of Vegfr2 expression. We also demonstrated that glomerular Vegfr2-dependent TMA lesions are an underevaluated common hallmark of anti-GBM-GN in mice.

Some recently published works contest the epithelial origin of myofibroblasts, which are the major extracellular matrix producers. However, our previous studies showed that, in tubular cells, some phenotypic changes reminiscent of epithelial-to-mesenchymal transition constitute an interesting early marker that predicts the progression of fibrosis in renal grafts. We hypothesized that activated epithelial cells could directly contribute to fibrogenesis, although they remain within the tubules. Using immunohistochemistry, we studied the association between epithelial phenotypic changes (de novo expression of vimentin and intracellular translocation of β-catenin) and the production of profibrotic molecules (connective tissue growth factor, HSP47, and laminin), in tubular epithelial cells from 93 renal grafts biopsied of 77 patients. We observed the de novo production of connective tissue growth factor, HSP47, and laminin in the tubular epithelial cells displaying epithelial phenotypic changes. The score of vimentin was significantly correlated with those of connective tissue growth factor (r = 0.785, P < .0001), HSP47 (r = 0.887, P < .0001), and laminin (r = 0.836, P < .0001). The level of tubular expression of mesenchymal cell markers and profibrogenic molecules, but not graft histologic lesions according to Banff acute or chronic scores, was correlated with graft dysfunction and proteinuria at the time of biopsy (r = -0.611, P < .0001 for vimentin with estimated glomerular filtration rate) (r = 0.42, P = .0006 for vimentin with proteinuria). Our results demonstrate that the epithelial phenotypic switch is associated with an active fibrogenic process in tubular epithelial cells and with graft injury indicators. Perpetuation of this tissue injury-repair response may drive fibrogenesis in renal grafts. This "repair response" represents an interesting marker for renal graft surveillance.

International audience; Calcium oxalate nephrolithiasis is a common ailment. Frequent risk factors associated with are low diuresis, dietary imbalance, inherited or acquired metabolic disorders. Another important factor, namely the presence of a mineral deposit made of apatite at the surface of the papilla, named Randall's plaque (RP), has been recently underlined. In most cases, RP which serves as a nidus for kidney stone formation is made of calcium phosphate apatite (CA). However, RP does not seem to be composed exclusively of CA. We would like to assess the case of RP where sodium hydrogen urate monohydrate (NaUr) is also present in its chemical composition. To attain this goal, a set of experiments including Environmental Scanning Electron Microscopy (ESEM) and Synchrotron Radiation Fourier Transform InfraRed (SR-FTIR) has been performed to analyze papillae of six kidneys randomly selected after they were surgically removed for cancer. NaUr crystals were found in two samples. We show through ESEM an usual morphology of RP present at the surface of kidney stones in the presence of NaUr. Moreover, we discuss the presence of NaUr in the renal parenchyma and its spatial repartition with CA. The complete set of data indicates that different biochemical mechanisms are probably involved in the pathogenesis of RP. The next step will be to establish a significant relationship between these physicochemical data and the clinical and biochemical data of the patients.

International audience; In this contribution, an approach developed previously for mice is used for human biopsy. In the case of patient 1, Pt detection is performed 6 days after the last oxaliplatin infusion, while for patient 2, the biopsy was performed more than 15 days after his first platin infusion and several dialysis. Even for these biological samples, experiments show that synchrotron mediated mXRF is a suitable tool to detect Pt in kidney biopsy, and thus probably for any organ exposed to Pt. Therefore, mXRF could also be of major interest to decipher the mechanism beyond Pt induced neurotoxicity, ototoxicity on human biopsy. Pharmacoavailability of chemotherapies is a major concern because some treatment failures are explained by poor tumor penetration of the active molecule. mXRF could be an elegant way to map the distribution of Pt inside cancerous cells at the micrometer scale. Pt and Zn are only two of the numerous trace elements that mXRF can detect; heavy metal intoxication diagnosis and the toxicity mechanism probably could also benefit from this innovative technique.

During human glomerulonephritis, the severity of injuries correlates with glomerular fibrin deposits, which are tightly regulated by the intraglomerular fibrinolytic system. Here, we evaluated the role of vitronectin (VTN; also known as complement S protein), the principal cofactor of the plasminogen activator inhibitor-1 (PAI-1), in a mouse model of acute glomerulonephritis. We found that in mice subjected to nephrotoxic serum, the absence of VTN resulted in a lower glomerular PAI-1 activity and a higher glomerular fibrinolytic activity. Challenged VTN(-/-) mice displayed significantly less fibrin deposits, proteinuria, and renal failure than their wild-type counterparts. Notably, this protective effect afforded by VTN deficiency was still observed after a C3 depletion. Finally, the injection of VTN(+/+) serum in VTN(-/-) mice induced the glomerular deposition of VTN, increased PAI-1 deposition, decreased glomerular fibrinolytic activity, and aggravated glomerular injury. As in mice, abundant glomerular VTN deposits were also observed in patients with severe glomerulonephritis. Here, we show that plasma-exchange therapy, admittedly beneficial in this clinical context, induces a significant depletion in circulating VTN, which might modulate PAI-1 activity locally and accelerate the clearance of fibrin deposits in the glomeruli. Collectively, these results demonstrate that VTN exerts a deleterious role independently from complement, by directing PAI-dependent fibrinolysis in the glomerular compartment.

Antibody-mediated rejection (ABMR) is a leading cause of allograft loss. Treatment efficacy depends on accurate diagnosis at an early stage. However, sensitive and reliable markers of antibody-endothelium interaction during ABMR are not available for routine use. Using immunohistochemistry, we retrospectively studied the diagnostic value of three markers of endothelial-to-mesenchymal transition (EndMT), fascin1, vimentin, and heat shock protein 47, for ABMR in 53 renal transplant biopsy specimens, including 20 ABMR specimens, 24 cell-mediated rejection specimens, and nine normal grafts. We validated our results in an independent set of 74 unselected biopsy specimens. Endothelial cells of the peritubular capillaries in grafts with ABMR expressed fascin1, vimentin, and heat shock protein 47 strongly, whereas those from normal renal grafts did not. The level of EndMT marker expression was significantly associated with current ABMR criteria, including capillaritis, glomerulitis, peritubular capillary C4d deposition, and donor-specific antibodies. These markers allowed us to identify C4d-negative ABMR and to predict late occurrence of disease. EndMT markers were more specific than capillaritis for the diagnosis and prognosis of ABMR and predicted late (up to 4 years after biopsy) renal graft dysfunction and proteinuria. In the independent set of 74 renal graft biopsy specimens, the EndMT markers for the diagnosis of ABMR had a sensitivity of 100% and a specificity of 85%. Fascin1 expression in peritubular capillaries was also induced in a rat model of ABMR. In conclusion, EndMT markers are a sensitive and reliable diagnostic tool for detecting endothelial activation during ABMR and predicting late loss of allograft function.

International audience; Noninfectious mixed cryoglobulinemic GN (MCGN) has been poorly investigated. We analyzed presentation and outcome of 80 patients with biopsy-proven MCGN, which were identified in the retrospective French CryoVas survey. MCGN was related to primary Sjögren's syndrome in 22.5% of patients and to lymphoproliferative disorders in 28.7% of patients, and was defined as essential in 48.8% of patients. At presentation, hematuria, proteinuria ≥1 g/d, hypertension, and renal failure were observed in 97.4%, 84.8%, 85.3%, and 82.3% of cases, respectively. Mean±eGFR was 39.5±20.4 ml/min per 1.73 m2. Membranoproliferative GN was the predominant histologic pattern, observed in 89.6% of cases. Renal interstitium inflammatory infiltrates were observed in 50% of cases. First-line treatment consisted of steroids alone (27.6%) or in association with rituximab (21.1%), alkylating agents (36.8%) or a combination of cyclophosphamide and rituximab (10.5%). After a mean follow-up of 49.9±45.5 months, 42.7% of patients relapsed with a renal flare in 75% of cases. At last follow-up, mean eGFR was 50.2±26.1 ml/min per 1.73 m2 with 9% of patients having reached ESRD; 59% and 50% of patients achieved complete clinical and renal remission, respectively. A rituximab+steroids regimen prevented relapses more effectively than steroids alone or a cyclophosphamide+steroids combination did, but was associated with a higher rate of early death when used as first-line therapy. Severe infections and new-onset B-cell lymphoma occurred in 29.1% and 8.9% of cases, respectively; 24% of patients died. In conclusion, noninfectious MCGN has a poor long-term outcome with severe infections as the main cause of death

Epithelial-to-mesenchymal transition (EMT) of tubular epithelial cells (TECs) may participate in the pathogenesis of renal fibrosis. We performed a prospective study of EMT markers in protocol biopsies obtained 3 months after engraftment from 56 patients who received deceased donor kidneys and who had stable renal function. The presence of EMT was examined, and quantified by immunohistochemical staining for vimentin and translocation of beta-catenin to the cytoplasm. EMT status was defined as the presence of EMT markers inor = 10% of TECs. EMT features were virtually absent in implantation biopsies, whereas 41% of the grafts were EMT-positive in the absence of advanced chronic allograft nephropathy. Thirteen patients (23%) had borderline changes or acute rejection. EMT features were more frequent in these patients than in those with normal kidney grafts (vimentin expression, p = 0.003; beta-catenin translocation, p = 0.002). EMT in grafts corresponded with elevated serum creatinine of the donor before the recovery of kidney (p = 0.02) and longer cold ischemia time (p = 0.02). In contrast, the donor age had no influence on the expression of EMT markers. These results suggest that EMT is an early and frequent phenomenon in kidney transplants that could be triggered by immunological and/or ischemic tubular injury.

The myelin protein 0 (MPZ or P0) is a transmembrane glycoprotein that represents the most abundant myelin component. Mutations in the P0 gene are associated with one form of autosomal dominant demyelinating peripheral neuropathy, Charcot-Marie-Tooth disease type 1B (CMT1B). Because CMT1 may be associated with renal involvement, mostly focal segmental glomerulosclerosis, we hypothesized that P0 could be expressed in the kidney. P0 mRNA was detected by reverse transcriptase–PCR in the human and mouse renal cortex. P0 transcripts were identified by in situ hybridization at different stages of the mouse kidney development, especially in embryonic structures that give rise to the glomerulus. P0 protein was also detected by Western blot in human and rat glomerular extracts and in a human podocyte cell line using a monoclonal anti-P0 antibody. Immunofluorescence studies on human kidney sections showed that the podocytes were intensely labeled. Immunogold electron microscopy disclosed a predominant staining of the membranes of intracellular vesicles in podocytes. P0 was also detected in the podocyte cell membrane, including at the foot processes. P0 −/− mice exhibited mild growth retardation and demyelinating neuropathy similar to the one observed in patients with CMT1B. They also presented mild albuminuria, without significant ultrastructural change of the glomerular basement membrane or the podocytes. These results demonstrate that P0, the major myelin protein, is also expressed during nephrogenesis and in mature kidney, mostly in podocytes. They suggest that P0 gene mutations might be involved in renal diseases.

Cyclosporine (CsA), a widely used immunosuppressive drug, is an effective treatment of sight-threatening posterior idiopathic uveitis. CsA's main side effect is nephrotoxicity. The aim of this single-center prospective cohort study (conducted in a tertiary care teaching hospital in Paris, France) was to assess the long-term renal tolerance of a low-dose CsA treatment in patients with previously healthy kidneys on clinical, biologic, and pathologic criteria. Forty-one patients treated with 4.3 +/- 1.6 mg/kg body wt per day CsA for 44.9 +/- 3.6 mo were included. Mean follow-up was 55.4 +/- 0.2 mo. BP, CsA trough level, and renal function were prospectively monitored together with blood urea, creatinine clearance, GFR, and effective renal plasma flow. Eleven patients underwent serial kidney biopsies before and after 2 yr of a 4 +/- 0.9 mg/kg daily CsA treatment. Sustained low-dose CsA treatment induced a significant increase in plasma creatinine (P < 0.0001), a significant decrease in creatinine clearance (P < 0.0001), and isotopic GFR (P < 0.0001) over time. The highest dose induced more severe alterations in any of the renal parameters than the lowest dose. Prevalence of hypertension was particularly high. Histopathologic data showed significant interstitial fibrosis (P < 0.003) and tubular atrophy (P < 0.003) after 2 yr. Low-dose long-term CsA treatment induces significant renal impairment and a high incidence of hypertension. Our study suggests that lowering daily dosage may prevent CsA-induced nephrotoxicity if a daily dose of < or =3 mg/kg is used. Whether once established it is reversible is still prospective, although the occurrence of interstitial fibrosis in the kidney would argue against reversibility.

Background. The epithelial response to injury is stereotypical and reminiscent of epithelial-to-mesenchymal transitions (EMTs), such as those observed during embryogenesis and tumour metastasis. In the context of solid organ transplantation, EMT-like features are often acquired by epithelial cells and are predictive of graft fibrosis. Here, we studied the possible involvement of several major transcriptional regulators, including snail1, phospho-Smad 2/3 and zeb1, in EMT induction in human renal grafts. Methods. We used immunohistochemistry to detect the presence of these EMT transcriptional regulators along with that of two validated EMT markers (intra-cytoplasmic translocation of β-catenin, de novo expression of vimentin), in 103 renal graft biopsy samples taken for routine surveillance or for a clinical indication. Results. We observed the nuclear accumulation of snail1 and phospho-smad2/3 in tubular cells displaying EMT. The level of snail1 was significantly correlated with the scores of EMT markers (β-catenin: ρ= 0.94, P < 0.0001; vimentin: ρ= 0.93, P < 0.0001) and with deteriorated graft function and proteinuria at the time of biopsy. Furthermore, intense staining for both snail1 and vimentin in tubular cells (≥10% of tubules) was predictive of graft dysfunction 21 months post-biopsy, independently of the other known risk factor for long-term graft dysfunction. In contrast, in both normal and diseased graft, zeb1 expression was detected exclusively in the endothelial cells of glomeruli and peritubular capillaries. Conclusion. This study suggests that snail1 is closely related to the fibrogenic, EMT-like response of the tubular epithelium in human renal grafts and predictive of graft function loss.

Background Erythropoietin (Epo) is a growth factor whose synthesis mainly takes place in the kidney. Epo has been shown to support the growth not only of erythroid progenitor cells but also of certain other cell types. We attempted to establish whether Epo enhances the recovery from acute renal failure induced by cisplatin. Methods Sprague-Dawley rats were randomized into three groups. In the cisplatin group, animals received one intraperitoneal injection of cisplatin (6 mg/kg) and a daily injection of placebo for 9 days. In the cisplatin+Epo group, animals received intrapertoneal cisplatin and a daily injection of Epo (100 IU/kg) for 9 days. In the control group, animals received both placebo preparations alone. Para-aminohippuric acid and inulin clearances were determined after 4 and 9 days to evaluate renal blood flow and glomerular filtration rate. In addition, light microscopy and immunohistochemistry examinations were performed, and in situ proliferating cell nuclear antigen (PCNA) staining was done to estimate the degree of renal tubular cell regenerative activity. The potential role of epithelial growth factor (EGF) was evaluated by semi-quantitative assessment of EGF immunostaining. Results Renal blood flow and glomerular filtration rate decreased significantly in cisplatin and cisplatin+Epo groups versus control group at day 4. However, at day 9, they both were significantly greater in cisplatin+Epo-treated animals than in rats that had received cisplatin alone. Tubular cell regeneration was significantly enhanced at day 4 in cisplatin+Epo group, compared with cisplatin and control groups respectively. EGF immunostaining was not significantly different between the three groups. Conclusion Epo significantly enhanced the rate of recovery from acute renal failure induced by cisplatin. PCNA staining indicated that Epo might act directly via stimulation of tubular cell regeneration.

The nephrotoxic potentials of a high-osmolar contrast medium, diatrizoate, and of a low-osmolar contrast medium, ioxaglate, were compared during early degenerative gentamicin-induced nephropathy in the rat. Male rats (13-22/group) were uninephrectomized. Six days later, the aorta was clamped above the renal artery, and either diatrizoate or ioxaglate was administered (1 ml/min for 3 min) via an aortic puncture into the remaining kidney. Some of the rats received chronic treatment with gentamicin (50 mg/kg/day i.m., 4 days), starting 2 days before and ending 1 day after contrast medium administration. Two control groups, only one of which received gentamicin, were subjected to a 3-min renal ischemia. The creatinine clearance (CrCl) per 100 g body weight was determined before and 24 and 48 h after contrast medium injection. A second study (6 rats/group) evaluated urinary N-acetyl-beta-D-glucosaminidase (NAG) excretion and the histologic appearance of the kidneys (blinded analysis) in the same experimental groups. Gentamicin induced a significant decrease in CrCl at baseline (0.35 +/- 0.19 vs. 0.41 +/- 0.19 ml/min; p0.01) and an increase in urinary NAG (128 +/- 92 vs. 39 +/- 57 mumol/h/mmol creatinine; p0.01). Taking into account these differences at baseline, univariate repeated-measures analysis showed that on day 1 diatrizoate caused a more marked decrease in CrCl than ioxaglate (p0.05), whether or not gentamicin was also administered. On day 2, the depressant effect of diatrizoate associated with gentamicin persisted (CrCl vs. day 0 = -0.19 +/- 0.10 ml/min), while that of diatrizoate alone returned to baseline (-0.05 +/- 0.24 ml/min).(ABSTRACT TRUNCATED AT 250 WORDS)

International audience; This study investigated the role of discoidin domain receptor 1 (DDR1), a collagen receptor that displays tyrosine-kinase activity, in the development of glomerulonephritis. Crescentic glomerulonephritis was induced in DDR1-deficient mice and their wild-type (WT) littermates as controls, by injection of alloimmune sheep nephrotoxic serum (NTS). Histological, functional and transcriptomic studies were performed. Glomerulonephritis produced a 17-fold increase of DDR1 expression, predominantly in glomeruli. DDR1 deletion protected NTS-treated mice against glomerular disease (proteinuria/creatininuria 5.5±1.1 vs. 13.2±0.8 g/mmol in WT, crescents 12±2 vs. 24±2% of glomeruli, urea 16±2 vs. 28±5 mM), hypertension (123±11 vs. 157±8 mmHg), and premature death (70 vs. 10% survival) (all P

International audience; Thrombospondin-1 (TSP-1) is an endogenous activator of transforming growth factor-β (TGF-β), and an anti-angiogenic factor, which may prevent kidney repair. Here we investigated whether TSP-1 is involved in the development of chronic kidney disease using rats with unilateral ureteral obstruction, a well-known model to study renal fibrosis. Obstruction of 10 days duration induced inflammation, tubular cell atrophy, dilation, apoptosis, and proliferation, leading to interstitial fibrosis. TSP-1 expression was increased in parallel to that of collagen III and TGF-β. Relief of the obstruction at day 10 produced a gradual improvement in renal structure and function, the reappearance of peritubular capillaries, and restoration of renal VEGF content over a 7- to 15-day post-relief period. TSP-1 expression decreased in parallel with that of TGF-β1 and collagen III. Mice in which the TSP-1 gene was knocked out displayed less inflammation and had better preservation of renal tissue and the peritubular capillary network compared to wild-type mice. Additional studies showed that the inflammatory effect of TSP-1 was mediated, at least in part, by monocyte chemoattractant protein-1 and activation of the Th17 pathway. Thus, TSP-1 is an important profibrotic and inflammatory mediator of renal disease. Blockade of its action may be a treatment against the development of chronic kidney disease.

International audience; Recent findings in idiopathic membranous nephropathy (MN) suggest that in most patients, the disease is because of anti-phospholipase A(2) receptor (PLA(2) R1) autoantibodies. Our aim was to analyze the prevalence and significance of anti-PLA(2) R1 antibodies in recurrent and de novo MN after transplantation. We assessed circulating PLA(2) R1 autoantibodies by a direct immunofluorescence assay based on human embryonic kidney cells transfected with a PLA(2) R1 cDNA, and the presence of PLA(2) R1 antigen in immune deposits. We showed that PLA(2) R1 was involved in 5 of 10 patients with recurrent MN, but in none of the 9 patients with de novo MN. We also showed a marked heterogeneity in the kinetics and titers of anti-PLA(2) R1, which may relate to different pathogenic potential. We provide evidence that some patients with PLA(2) R1-related idiopathic MN and anti-PLA(2) R1 antibodies at the time of transplantation will not develop recurrence. Because PLA(2) R1 autoantibody was not always associated with recurrence, its predictive value should be carefully analyzed in prospective studies.

The transcription factor Snail is an important repressor of E-cadherin gene expression. It plays a key role in the induction of epithelial-mesenchymal transition, an essential process important not only in embryonic development and tumor progression but also in organ fibrogenesis. We studied the expression of Snail by immunohistochemistry, along with several epithelial phenotypic changes suggestive of epithelial-mesenchymal transition, in 14 patients with multiple myeloma cast nephropathy. This nephropathy is characterized by a rapid progression toward fibrosis. As controls, we used normal kidneys and kidneys from patients displaying an idiopathic nephrotic syndrome, a syndrome unassociated with renal fibrosis. We discovered that, in all patients with multiple myeloma nephropathy, a drastic accumulation of Snail is seen in the nuclei from tubular epithelial cells showing epithelial phenotypic changes. In contrast, normal and idiopathic nephrotic syndrome kidneys did not exhibit either of these markers. Snail, a major player in the process of epithelial-to-mesenchymal transition, is highly expressed by tubular epithelial cells during multiple myeloma nephropathy. It is, therefore, a potential target to prevent multiple myeloma kidneys from fibrosing. Intranuclear accumulation of Snail is a characteristic in phenotypically altered tubular cells from multiple myeloma kidneys. The epithelial-mesenchymal transition pathway could, therefore, be involved in the rapid renal fibrogenesis observed in this setting.

Asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase (NOS) inhibitor, is accumulated in plasma during chronic kidney disease (CKD). It is considered an independent mortality and cardiovascular risk factor in CKD patients. To test the involvement of ADMA in CKD progression, we investigated the effects of chronic ADMA administration on renal structure and compared these effects with NG-nitro-L-arginine methyl ester (L-NAME) treatment, a widely used exogenous inhibitor of NOS that induces CKD. Three groups of uninephrectomized mice were studied: ADMA (60 mg/kg per day), L-NAME (60 mg/kg per day), and isotonic saline (control) were infused through osmotic mini-pumps for 8 weeks. ADMA and L-NAME induced hypertension (PAS 167 ± 16 and 168 ± 10 versus 100 ± 4 mmHg, p < 0.01, respectively). High level of ADMA was associated with increased renal oxidative stress. ADMA treatment induced glomerular and vascular fibrosis as evidenced by the elevated deposits of collagen I, III, and fibronectin (p < 0.01). A similar profile was observed in the L-NAME group. Mice treated with ADMA had reduced peritubular capillaries versus controls (p < 0.01). Collagen I mRNA expression and renal TGF-β1 concentrations were higher in the ADMA and L-NAME groups. Increased level of TGF-β1 was associated with a significant rise of HIF-1α and endothelin-1 expression. These results demonstrate for the first time that elevated concentrations of ADMA are associated with the development of renal fibrosis. These data suggest that in pathophysiological conditions of endothelial dysfunction, the exaggerated endogenous synthesis of ADMA could contribute to CKD progression by favouring hypertension, extracellular matrix synthesis, and rarefaction of peritubular capillaries.

Renal fibrosis is defined by the exaggerated accumulation of extracellular matrix proteins. Tissue transglutaminase (TG2) modifies the stability of extracellular matrix proteins and renders the extracellular matrix resistant to degradation. In addition, TG2 also activates transforming growth factor-beta (TGF-beta). We investigated the involvement of TG2 in the development of renal fibrosis using mice with a knockout of the TG2 gene (KO). These mice were studied at baseline and 12 days after unilateral ureteral obstruction, which induced a significant increase in interstitial TG2 expression in wild-type mice (P < 0.001). Interstitial fibrosis was evident in both groups, but total and fibrillar collagen was considerably lower in KO mice as compared with wild-type (P < 0.001). Similarly, mRNA and protein expression of collagen I were significantly lower in KO animals (P < 0.05). A statistically significant reduction in renal inflammation and fewer myofibroblasts were observed in KO mice (P < 0.01). Free active TGF-beta was decreased in KO mice (P < 0.05), although total (active + latent) TFG-beta concentration did not differ between groups. These results show that mice deficient in TG2 are protected against the development of fibrotic lesions in obstructive nephropathy. This protection results from reduced macrophage and myofibroblast infiltration, as well as from a decreased rate of collagen I synthesis because of decreased TGF-beta activation. Our results suggest that inhibition of TG2 may provide a new and important therapeutic target against the progression of renal fibrosis.

Renal hyperplasia and hypertrophy are early events after nephron reduction which precede progressive destruction of the remnant kidney. Restriction of dietary sodium content was shown to reduce renal lesions following nephron reduction. AP-1 is a transcription factor, resulting from heterodimerization of fos and jun proteins, which mediates the effects of mitogenic growth factors. To elucidate the role of AP-1 in growth processes involved in renal deterioration, we evaluated whether restriction of dietary sodium content (0.25 vs. 0.50% sodium w/w) affected AP-1-DNA binding and hyperplasia in the remnant kidney after nephron reduction (70% nephrectomy). Cell proliferation, evaluated by PCNA immunostaining, increased progressively from day 7 to day 60 in glomeruli, proximal and distal tubules and loops of Henle of nephrectomized (Nx) rats compared to control sham-operated (C) animals. AP-1-DNA binding activity increased 7 and 14 days after surgery, but it was reduced below C values at day 60. c-fos and c-jun expression were also reduced in Nx rats at day 60. Sodium restriction significantly reduced the number of PCNA-stained cells in glomeruli and tubules at days 14 and 60, but not at day 7, whereas it decreased AP-1 activation at all times of the study. This effect was associated to a marked reduction of renal lesions in Nx rats. In conclusion, we showed that, after nephron reduction, the beneficial effect of sodium restriction was associated with a reduction of hyperplasia and AP-1 activation, but that the latter did not parallel delayed cell proliferation rate in remaining nephrons. Thus, we propose that different transduction pathways are involved in cell proliferation after nephron reduction, according to the time of evolution of renal lesions.

Between November 1983 and December 1991, we undertook a systematic study of kidney in deceased AIDS patients using light and immunofluorescence microscopy. Among the 116 examined kidneys (from 106 men and 10 women), nine (7.75%) showed diffuse mesangial IgA deposits. By light microscopy, glomerular lesions were absent or moderate (mesangial hypertrophy or some mesangial deposits). Urinary abnormalities were mild in all cases. Our study shows that the association between IgA nephropathy and HIV infection is not rare, and a review of the literature disclosed 18 reported cases. Some reported immunopathogenic data support the possibility of a link between HIV infection and IgA nephropathy.

The long-term renal effects of cisplatin have been very poorly studied. Therefore we investigated the chronic renal effects of various doses of cisplatin in three groups of male Sprague-Dawley rats. Group I received two injections of 5 mg/kg body weight (bw) at 4-week intervals, group II four injections of 2.5 mg/kg bw at 4-weeks intervals, and group III one injection of 5 mg/kg bw and four injections of 2.5 mg/kg bw at 4-weeks intervals. Controls received an equivalent amount of isotonic saline. Each group was evaluated 1, 3, or 6 months after the last injection of cisplatin. One, 3 and 6 months after the last injection, cisplatin induced a marked decrease in glomerular filtration rate (GFR) evaluated as clearance of [99mTc]DTPA and creatinine clearance in all treated rats. Urinary NAG excretion remained unaltered. At 3 months post-cisplatin treatment GFR was significantly less (P < 0.05) in group III (0.18 +/- 0.02 ml/min/100 g bw) when compared with group I (0.23 +/- 0.02 ml/min/100 g bw) or II (0.23 +/- 0.04 ml/min/100 g bw). In group I GFR was similar 1 month (0.24 +/- 0.02), 3 months (0.23 +/- 0.02) and 6 months (0.23 +/- 0.03 ml/min/100 g bw) after cisplatin treatment. Cisplatin induced atrophy and dilatation of tubules with mononuclear cell infiltration associated with cyst formation. The glomerular and tubulointerstitial lesions were significantly enhanced in group III when compared with groups I and II. This study indicates that repeated administration of cisplatin may induce a chronic tubulointerstitial nephropathy associated with a marked decrease in GFR, which is stable over time. The incidence and severity of chronic cisplatin toxicity is dose-related and is not modified by dividing the dose.