Role of thrombin receptors in the kidney: lessons from PAR1 knock-out mice.
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Animals↗
Biomedical subjects
E Rondeau
Publications and source records attributed to E Rondeau.
Induction of urokinase receptor expression in nephrotoxic nephritis.
The urokinase receptor (uPAR) is a multifunctional molecule involved in pericellular, fibrinolytic, and proteolytic activities, as well as in cell adhesion and chemotaxis and may play a role in the pathogenesis of tissue remodeling occurring during glomerulonephritis. We analyzed sequentially the expression of uPAR by immunohistochemistry and in situ hybridization in an accelerated model of nephrotoxic nephritis in rats. A strong induction of uPAR mRNA expression was observed in glomeruli as soon as 1 h after nephrotoxic serum injection. The intensity of glomerular uPAR mRNA and antigen expression increased and peaked at 24 h. At that time, numerous glomerular fibrin deposits, monocyte/marcrophage infiltration, and heavy proteinuria were observed. Fibrin deposition was detected at 6 h, peaked at 24 h, and progressively declined over the next 3 weeks, while uPAR antigen expression remained elevated until the end of the study (3 weeks). By double labeling, we showed that the expression of uPAR was mediated by both intrinsic glomerular cells and infiltrating macrophages. Severe podocytic lesions developed within 3 days after antiserum injection, and glomerulosclerosis rapidly progressed within 2-3 weeks. These results show that glomerular uPAR expression is induced in nephrotoxic nephritis and suggest that uPAR may promote local proteolysis and also tissue remodeling, leading to the late development of glomerulosclerosis.
Animals↗
Internalisation of the protease-activated receptor 1: role of the third intracellular loop and of the cytoplasmic tail.
To analyse the mechanisms of PAR-1 internalisation, we constructed several PAR-1 mutants and stably expressed them in CHO cells. Our study shows that the Ser(306)-->Ala mutation (S306A), which eliminates a potential site of phosphorylation by PKC in the third intracellular loop of PAR-1, did not change the rate of phosphorylation but reduced the rate of thrombin-induced internalisation of the PAR-1 mutant (58 versus 78% of membrane PAR-1 in 15 min, p<0.005). Deletion of the last 43 amino acid residues of the PAR-1 cytoplasmic tail completely suppressed the thrombin phosphorylation of the mutated receptor and significantly reduced its internalisation upon activation. This deletion also inhibited the PMA-induced and the agonist-independent internalisation of the receptor. The Tyr(371)--> Ala mutation (Y371A), in a NPXXY motif of the seventh transmembrane domain of the receptor had no effect on the receptor behaviour. Our results indicate that both the C-tail and the third intracellular loop are involved in PAR-1 internalisation induced by thrombin while only the C-tail plays a role in the PMA-induced and in the agonist-independent PAR-1 internalisation.
Alanine↗
Role of the third intracellular loop and of the cytoplasmic tail in the mitogenic signaling of the protease-activated receptor 1.
The activation of the protease-activated receptor 1 (PAR-1) by thrombin has been shown to induce an activation of the MAP kinase cascade and to stimulate cell proliferation. To examine the mechanisms of signal transduction by PAR-1, we constructed several PAR-1 mutants which were stably expressed in CHO cells. When compared to wild-type PAR-1, mutation of Ser306-->Ala (S306A) in the third intracellular loop of PAR-1 inhibited MAP kinase activation and cell proliferation stimulated by thrombin. The thrombin activation of MAP kinase was inhibited by pertussis toxin, suggesting a role for a Gi-like protein. As shown by calcium signaling and inosotol trisphosphate generation, the Ser306-mutated PAR-1 induced a strong activation of phospholipase C after thrombin addition. Deletion of the cytoplasmic tail of PAR-1 also inhibited thrombin-induced DNA synthesis but the MAP kinase pathway was activated as with wild-type PAR-1. In contrast, the deletion of the C-tail of PAR-1 prevented almost completely the activation of the phospholipase C pathway. Taken together these results suggest that the C-tail of PAR-1 is a critical site for PAR-1 coupling to phospholipase C activation, while the third intracellular loop of PAR-1 is implicated in PAR-1 coupling to Gi and MAP kinase activation. In addition, these results also show that MAP kinase activation is necessary but not sufficient for thrombin to induce cell proliferation.
Animals↗
[Plasminogen activator inhibitor type 1: physiology and role in renal physiopathology].
Plasminogen activator inhibitor type 1 plays a prominent part in the regulation of extra and intra-vascular fibrinolysis through the inhibition of plasmin formation. In addition to its role in the resolution of blood clots, PAI-1 is involved in a variety of other biological processes including extracellular remodeling, cellular mobility, embryo implantation, development and tumoral proliferation. Moreover, PAI-1 is also implicated in various pathological processes such as thromboembolic diseases, atherosclerosis and fibrosis formation, particularly in the kidney and the lung. Inhibition of PAI-1 activity or of PAI-1 synthesis by specific antibodies, peptidic antagonists, antisens oligonucleotides or decoy oligonucleotides has been obtained in vitro but need to be evaluated in vivo. All these findings may have new therapeutical implications, explaining the importance of studies on PAI-1 production and regulation.
Aldosterone↗
Regulation of the paired type IV collagen genes COL4A5 and COL4A6. Role of the proximal promoter region.
Tissue-specific expression patterns of the paired type IV collagen genes COL4A5 and COL4A6 form the basis for organ involvement in X-linked Alport syndrome, a disorder in which these genes are mutated. We investigated the proximal promoter region of COL4A5 and COL4A6 using glomerular visceral epithelial cells, in which COL4A5 alone is transcribed; keratinocytes, in which the genes are co-transcribed; and additional model cell lines. By RNase protection assays, the intergenic region is 292 base pairs. Transcription start sites for two 5' splice variants of COL4A6 are 1 kilobase apart. Transient transfections with reporter gene constructs revealed that the minimal promoters for COL4A5 and COL4A6 are within 100 base pairs of their respective transcription start sites and are functionally distinct. In further transfection, gel shift and footprinting assays, we defined a bidirectional positive regulatory element, which functions in several cell types, but not in glomerular visceral epithelial cells selectively transcribing COL4A5. The existence of separate promoters for COL4A5 and COL4A6 permits fine control over their expression. Activation through the bidirectional element can bring about co-expression of the genes, exploiting their paired arrangement. Features of the proximal promoter region frame its roles in a hierarchy regulating type IV collagen gene expression.
Base Sequence↗
[Rapidly progressive acute renal failure. A rare complication of primary Sjogren syndrome].
BACKGROUND: Renal impairment, usually due to tubulointerstitial and rarely glomerular disorders occurs in 10 to 30% of patients with primary Sjögren's syndrome. Extracapillary proliferation may also be observed. CASE REPORT: A 62-year-old woman with primary Sjogren's syndrome diagnosed 12 years earlier, developed microscopic polyangeitis leading to rapidly progressive renal failure. Antipolynuclear anticyclosine antibody (ANCA) serology was positive (pANCA, anti MPO) and the renal biopsy evidenced necrotizing glomerulonephrities with extracapillary proliferation. Outcome was favorable despite a recurrence one year after onset. DISCUSSION: Extracapillary proliferative glomerulonephritis is characterized by hematuria and proteinuria associated with renal failure. Renal impairment may worsen rapidly, sometimes leading to an emergency situation because the renal prognosis is directly related to delay to treatment. This case illustrates an uncommon complication of Sjögren's syndrome, compared with the usual tubulointerstitial disorders. The mechanism remains unknown, but outcome can be favorable with rapidly initiated immunosuppressor treatment.
Acute Kidney Injury↗
[Hematuria. Diagnostic orientation].
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Diagnosis, Differential↗
Protease-activated receptor 1 mediates thrombin-dependent, cell-mediated renal inflammation in crescentic glomerulonephritis.
Protease-activated receptor (PAR)-1 is a cellular receptor for thrombin that is activated after proteolytic cleavage. The contribution of PAR-1 to inflammatory cell-mediated renal injury was assessed in murine crescentic glomerulonephritis (GN). A pivotal role for thrombin in this model was demonstrated by the capacity of hirudin, a selective thrombin antagonist, to attenuate renal injury. Compared with control treatment, hirudin significantly reduced glomerular crescent formation, T cell and macrophage infiltration, fibrin deposition, and elevated serum creatinine, which are prominent features of GN. PAR-1-deficient (PAR-1(-/-)) mice, which have normal coagulation, also showed significant protection from crescentic GN compared with wild-type mice. The reductions in crescent formation, inflammatory cell infiltration, and serum creatinine were similar in PAR-1(-/-) and hirudin-treated mice, but hirudin afforded significantly greater protection from fibrin deposition. Treatment of wild-type mice with a selective PAR-1-activating peptide (TRAP) augmented histological and functional indices of GN, but TRAP treatment did not alter the severity of GN in PAR(-/-) mice. These results indicate that activation of PAR-1 by thrombin or TRAP amplifies crescentic GN. Thus, in addition to its procoagulant role, thrombin has proinflammatory, PAR-1-dependent effects that augment inflammatory renal injury.
Animals↗
Acute renal failure in patients over 80 years old: 25-years' experience.
OBJECTIVE: To determine the epidemiological trends, spectrum of etiologies, morbidity and mortality of acute renal failure (ARF) in patients over 80 years old. DESIGN: Historical cohort analysis. SETTING: Intensive care unit (ICU) of nephrology, Tenon Hospital, Paris. PATIENTS AND PARTICIPANTS: The criteria of inclusion was ARF, defined on the basis of a creatinine value over 120 mumol/l, in patients over 80 years of age admitted between October 1971 and September 1996. When moderate chronic nephropathy was pre-existing, ARF was defined by the increase of at least 50% over the basal creatininemia. MEASUREMENTS AND RESULTS: Three hundred and eighty-one patients over 80 years of age were included. The etiology and mechanism of ARF are detailed. 29% of the patients received dialysis. Global mortality at the hospital was 40%. Factors significantly associated with a poor prognosis are identified. Mean survival after hospitalization was 19 months. CONCLUSION: The frequency of admission to ICUs for ARF in patients older than 80 years seems to be on the increase. Mortality is less severe than expected. These patients could benefit from the renal replacement therapy of modern intensive care medicine.
Acute Kidney Injury↗
What is the value of procurement biopsy lipid peroxidation lesions in the assessment of kidney graft function?
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Aldehydes↗
Tacrolimus-induced hemolytic uremic syndrome and end-stage renal failure after liver transplantation.
BACKGROUND: Hemolytic uremic syndrome (HUS) is a rare complication in solid organ transplantation. It can be associated with severe hypertension. Several risk factors have been identified including immunosuppressive drugs such as cyclosporin A and, more recently, tacrolimus. METHODS: Here we report a case of tacrolimus-induced HUS in a 61-yr-old woman after liver transplantation. Hypertension, microangiopathic anemia and end-stage renal failure occurred 2 yr after liver transplantation. RESULTS: At admission, she had malignant hypertension with a severe hypertensive retinopathy, renal failure (creatininemia: 800 micromol/L) and microangiopathic anemia (Hb: 7.3 g/dL, a low platelet count and elevated lactate dehydrogenase). At renal biopsy, histologic findings were ischemic and sclerotic glomeruli with hyaline thrombi, severe mesangiolysis and interstitial fibrosis. CONCLUSION: Despite steroid treatment, antihypertensive agents and fresh frozen plasma therapy, end-stage renal failure was observed and chronic hemodialysis treatment was required.
Female↗
Hemolytic uremic syndrome. Recurrence after renal transplantation. Groupe Coopératif de l'Ile-de-France (GCIF).
Hemolytic uremic syndrome (HUS) is an uncommon cause of end-stage renal failure in adults, and few data are available concerning the outcome of renal transplantation in these patients. We conducted this retrospective multicentric study to appreciate the outcome of adult renal transplant recipients whose primary disease was HUS. Sixteen patients, transplanted between 1975 and 1995, were included in the study. In each case, initial diagnosis of HUS was documented by a kidney biopsy. These 16 patients received a total of 25 allografts: 1 graft for 9 patients, 2 grafts for 5 patients, and 3 grafts for 2 patients. Nine patients (56%) developed definite clinical and pathologic evidence of recurrence on at least 1 graft. Four additional patients (25%) demonstrated only some clinical or pathologic evidence of recurrence which could not be distinguished from acute vascular rejection. Three patients had no sign of recurrence of the initial disease. The 1-year graft survival rate was 63% and the 5-year graft survival rate was 18.5%. In the group of patients with proven or possible recurrence (n = 13), the 1-year and 5-year graft survival rates were 49% and less than 10%, respectively. The recurrence was an early event, occurring before the end of the first month after transplantation in half the cases. The recurrence rate was 92% in non-nephrectomized patients and 50% in patients with bilateral nephrectomy. In the literature, 71 adult patients with primary HUS had received a total of 90 kidney grafts. Among them, 54% had a recurrence on their graft, which was diagnosed in 52% of the kidney transplants. It is note-worthy that when data from the literature are pooled with our results, the rate of recurrence appears to be significantly lower in binephrectomized patients than in patients with their native kidneys at the time of transplantation (5 of 14 versus 27 of 35 patients, respectively, p = 0.0155). By univariate analysis, no other risk factor for recurrence could be identified. Treatment with cyclosporine A did not influence the recurrence rate. We conclude that recurrence of HUS after renal transplantation is a frequent, early, and severe complication, leading rapidly to graft loss. Prospective studies are needed to confirm that bilateral nephrectomy prior to transplantation decreases the rate of recurrence.
Actuarial Analysis↗
[Should acute kidney failure be treated in people over 80 years of age at an intensive care unit?].
This is the first retrospective study aimed to analyze the clinical symptoms, the etiology, the morbidity and the lethality of acute renal failure in patients over 80 years. The criterion of inclusion was the occurrence of acute renal failure defined on the basis of high plasma creatinine associated with normal kidney size in patients of this class of age who had been hospitalized in an intensive care unit between October 1971 and September 1996. In the case of a preexisting moderate nephropathy, acute renal failure was defined by an increase of plasma creatinine of at least 50% over its basal value. Three hundred and eighty-one patients over 80 years out of a total of 2,111 patients with acute renal failure were included in this study. The various etiologies and mechanisms of the disease are described. Twenty-nine% of the patients underwent dialysis. The global lethality reached 40% during the time of hospitalization. The factors significantly associated with a poor prognosis were identified as cancer essentially, but also sepsis and preexisting cardiovascular diseases. The mean survival after hospitalization was of 19 months. In summary, the frequency of admission for acute renal failure of patients over eighty in intensive care units is increasing but the rate of lethality observed is less than expected. A pattern of pathological associations leading to death in these patients cannot be defined with certitude. Therefore, the methods of renal replacement therapy available in modern intensive care units must be utilized in this class of age as it is the case in younger patients.
Acute Kidney Injury↗
[Hypokalemic periodic paralysis revealing hyperthyroidism].
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Adult↗
Acute renal failure in the course of HIV infection: a single-institution retrospective study of ninety-two patients and sixty renal biopsies.
BACKGROUND: Acute renal failure syndromes are frequently encountered in patients with human immunodeficiency virus (HIV) infection. Most reported cases of acute renal failure are related to acute tubular necrosis, but many other causes of renal failure have been described in these patients. METHODS: The present work is a single-institution retrospective study of 92 HIV-infected patients with acute or rapidly progressing renal failure. In 60 cases, a renal biopsy was performed. For each patient we analysed clinical and pathological data, as well as the short-term prognosis. RESULTS: Ten different causes of acute or rapidly progressing renal failure were documented: (i) haemolytic uraemic syndrome (32 patients); (ii) acute tubular necrosis either of ischaemic-toxic origin (18 patients) or due to rhabdomyolysis (six patients); (iii) obstructive renal failure which was either extrinsic (two patients), drug-induced (13 patients) or secondary to paraprotein precipitation (one patient); (iv) HIV-associated nephropathy (14 patients); (v) acute interstitial nephritis (two patients); (vi) various glomerulonephritis (four patients). In most cases, renal failure was severe (the mean creatinine clearance at entry was 12 ml/min). Most patients had a significant improvement in renal function with only symptomatic treatment. Eighteen per cent of the patients died within 2 months of the diagnosis of renal failure. Renal biopsy seems important for the diagnosis but also for the prognosis, at least in the cases of haemolytic-uraemic syndrome, HIV-associated nephropathy and drug-induced micro-obstructive renal failure. CONCLUSION: Vascular and glomerular diseases are frequent causes of acute or rapidly progressing renal failure in HIV-infected patients. Renal biopsy appears to be safe and useful for the diagnosis and the prognosis of the renal failure. High mortality rate is only observed in patients with ischaemic/toxic causes of acute renal failure.
Acute Kidney Injury↗
Role of thrombin and its receptor, the protease-activated receptor 1, in the pathophysiology of glomerular injury.
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Animals↗
Bacterial endocarditis associated with crescentic glomerulonephritis in a kidney transplant patient: first case report.
BACKGROUND: Endocarditis-induced crescentic glomerulonephritis is a well-described complication in nontransplant patients. Its occurrence in transplant patients has not been reported to date. METHODS: A 50-year-old man who had received a renal allograft 13 years before and been treated with prednisone, 10 mg/day, was admitted for progressive renal failure, purpura, edema of the lower limbs, and fever. RESULTS: Blood cultures isolated Streptococcus bovis and cardiac ultrasound examination revealed a 23-mm-large vegetation on the mitral valve. His plasma creatinine level was 478 micromol/L and his proteinuria was 5.5 g/day. A renal biopsy showed diffuse crescentic glomerulonephritis. Long-term antibiotic treatment and three methylprednisolone pulses were effective in treating the endocarditis and glomerulonephritis. CONCLUSION: Endocarditis-induced glomerulonephritis is an immune-mediated disease that can also occur on a renal allograft. It is likely that a low daily dose of immunosuppressive treatment may have been a facilitating factor.
Creatinine↗