Identification and regulation of reticulon 4B (Nogo-B) in renal tubular epithelial cells.

Nogo-B is a member of the reticulon family of proteins that has been implicated in diverse forms of vascular injury. Although Nogo-B is expressed in renal tissues, its localization and function in the kidney have not been examined. Here, we report that Nogo-B is expressed specifically in the epithelial cells of the distal nephron segments in the murine kidney. After unilateral ureteral obstruction (UUO) and ischemia/reperfusion, Nogo-B gene and protein levels increased dramatically in the kidney. This increase was driven in part by injury-induced de novo expression in proximal tubules. Examination of Nogo-B immunostaining in human biopsy specimens from patients with acute tubular necrosis showed similar increases in Nogo-B in cortical tubules. Mice genetically deficient in Nogo-A/B were indistinguishable from wild-type (WT) mice based on histological appearance and serum analyses. After UUO, there was a significant delay in recruitment of macrophages to the kidney in the Nogo-A/B-deficient mice. However, measurements of fibrosis, inflammatory gene expression, and histological damage were not significantly different from WT mice. Thus, Nogo-B is highly expressed in murine kidneys in response to experimental injuries and may serve as a marker of diverse forms of renal injury in tissues from mice and humans. Furthermore, Nogo-B may regulate macrophage recruitment after UUO, although it does not greatly affect the degree of tissue injury or fibrosis in this model.

[Intracranial hypertension and lupus]. / Hypertension intracrânienne et lupus.

INTRODUCTION: Idiopathic intracranial hypertension (IH) occurs most commonly in women and overweight subjects. It must be reported associated to general diseases, like systemic lupus erythematosus (SLE). METHODS: We report an observation of a patient with lupus complicated by glomerulonephritis and IH. OBSERVATION: A 29 years old woman, without overweight, was followed for a SLE with skin and arthritic involvement . Four years after onset, a renal complication appeared with severe nephrotic syndrome. Six weeks after, bilateral papillar oedema was discovered, revealing an IH, as the patient was treated by oral steroids at 1mg/kg/d and bimonthly intravenous cyclophosphamide. The patient was completely asymptomatic. Brain MRI with veino-RMN was normal, without cerebral venous thrombosis. Lumbar punction showed an elevated opening pressure of 30,5 cmH(2)0 but with normal cerebrospinal fluid (CSF) contents. Evacuation of 30 mL of CSF and immunosuppressive treatment allowed symptoms regression. DISCUSSION/CONCLUSION: Twenty-seven cases of IH associated to SLE with nephritis have been reported in literature. Young women are more frequently involved with in half of cases a diffuse proliferative glomerulonephritis. Predisposing factors, like anaemia, must be associated. IH allows SLE diagnose in more than the third of the cases. Then, SLE has to be searched as an etiology of IH, in particular in non-obese patients and when nephritis is associated.

Characterization of renal papillary antigen 1 (RPA-1), a biomarker of renal papillary necrosis.

Renal papillary necrosis (RPN) is a relatively common toxicity observed in preclinical drug safety testing. It is also observed in a variety of human diseases. RPN is difficult to diagnose without expensive scanning methods or histopathology. A noninvasive biomarker that could be detected at early stages of kidney damage would be of great value both to preclinical drug safety testing and in the clinic. An antibody raised to an unknown epitope of an antigen in rat kidney papilla was found to be specific for collecting duct cells in the kidney; this was termed renal papillary antigen 1 (RPA-1). In this study, the authors show that RPA-1 is an early biomarker of RPN in two different rat models of toxicity: 2-bromoethanamine (BEA) and N-phenylanthranilic acid (NPAA). RPA-1 can be detected in urine at early stages of toxicity and correlates well with the histopathology observed. We also characterized the biochemical properties of RPA-1 and found that the antigen is a high molecular weight membrane bound glycoprotein, with the epitope likely to be carried on an N-linked carbohydrate structure. This study demonstrates that RPA-1 is an excellent marker of RPN that can be used to detect this toxicity in preclinical safety testing.

An unusual cause of renal allograft dysfunction: graft papillary necrosis.

A 43-year-old nondiabetic man, 5 years post-renal transplantation, presented complaining of oliguria, fever and dysuria of 1-day duration. Graft ultrasound did not reveal any obstructive changes. Graft function did not improve in spite of 3 days of antibiotics. On the fourth day he passed fleshy material in urine subsequent to which his urine output improved and fever recovered. His graft function settled near to the previous baseline. Histological analysis of the material revealed necrosed renal papillary tissue. Renal papillary necrosis in allograft is uncommon and generally reported in the immediate postoperative phase, but it can still occur later in transplant follow-up. It is a potentially treatable cause for acute allograft dysfunction and should be suspected in transplant patients presenting with acute pyelonephritis but not getting relief from antibiotic therapy.

Renal papillary necrosis in patients with IDDM.

Although diabetes mellitus is reported in 29% of patients with renal papillary necrosis (RPN), the frequency of RPN among patients with insulin-dependent diabetes mellitus (IDDM) has from autopsy studies been estimated to be only 4.4%. In vivo data on the prevalence of RPN in patients with IDDM have been lacking. We therefore studied the prevalence of RPN in 76 patients with long-standing IDDM and in 34 age-matched control subjects by intravenous urography. None of the control subjects showed radiographic signs of papillary necrosis. RPN was observed in 18 patients (23.7%); 15 were women (83.3%). Age and duration of diabetes was not different between patients with and without papillary necrosis, and there was no significant difference between the two groups regarding the prevalence of microangiopathic complications, i.e., proliferative retinopathy and diabetic nephropathy. Microscopic hematuria was three times more frequent in patients with than without RPN (44 vs. 16%; P less than .02). In addition, pyuria was reported in 40% of patients with papillary necrosis, and 61% of them gave a positive history of urinary tract infection compared to 16% (P less than 05) and 32% (P less than .02), respectively, in patients without papillary necrosis. It is concluded that RPN is a more frequent complication of long-standing IDDM than appreciated from autopsy studies, and being female and having a history of urinary tract infection are associated with an increased risk of RPN.

Evolution of experimentally induced papillary necrosis to focal segmental glomerulosclerosis and nephrotic proteinuria.

Bromoethylamine (BEA)-induced papillary necrosis is a reproducible model for analgesic nephropathy. We induced this lesion in groups of male Sprague-Dawley rats and followed the functional and histological changes for 1 year. We found that by 1 month, necrosis of the papilla was complete, glomerular filtration rate was depressed, and urine albumin excretion was increased. There was an extensive interstitial fibrosis characterized by a mononuclear cell infiltrate and patchy tubular atrophy. By 6 months, there was re-epithelialization of the papillary stump accompanied by a marked increase in albuminuria and an improvement in concentrating ability. Changes seen at 9 months were more advanced. There was extensive cortical fibrosis manifested by pitting of the surface of the kidney. At 1 year, renal function remained impaired (creatinine clearance reduced by 65% to 0.26 mL/min/100 g), and the animals were now markedly nephrotic, with albuminuria of 254 mg of albumin/24 h. In the BEA rats, there was selective destruction of the deep nephrons leading to an increase in the volume-ratio of superficial to deep nephrons. Glomerular changes, affecting approximately 60% of the glomeruli, were characteristic of focal segmental glomerular sclerosis. This model of papillary necrosis/interstitial fibrosis is associated with chronic renal insufficiency and leads to the development of focal glomerular sclerosis and nephrotic proteinuria by 6 to 12 months after its induction.

Renal papillary necrosis associated with Wegener's granulomatosis.

Review of the kidneys from 23 cases of Wegener's granulomatosis revealed necrosis of the renal papillae in five (21.7 per cent). These cases took a fulminant course of the disease consistent with the classic description of Wegener's granulomatosis, prevalence in the older age group, and rapid deterioration of renal function. Morphologic examination of the kidneys uniformly disclosed a variety of lesions in the blood vessels supplying the renal papilla. The most conspicuous was the widely distributed glomerular lesion represented by thrombotic and necrotic occlusion of capillary loops and crescent formation. A medullary interstitial lesion characterized by fibrinoid necrosis of the vasa recta was invariably found in the outer portion of the necrotic papilla. In addition, acute segmental and diffuse necrosis and occlusion by thrombosis were identified in the branches of spiral arteries in the adjoining papilla. The results provide an anatomic basis for the assumption that papillary ischemia due to impairment of the dual blood supply from the vasa recta and the calyceal arteries is the essential factor in papillary necrosis.

Experimental renal papillary necrosis in rats: microangiographic and tubular micropuncture injection studies.

Proposed causes of renal papillary necrosis (RPN) include tubular toxicity due to hyperconcentration of toxins in the renal medulla and vasoconstriction of medullary vessels with ischemic necrosis. The authors studied these mechanisms in bromoethylamine hydrobromide-induced RPN in rats by microvascular and tubular micropuncture injection studies. During early stages of RPN, microvascular studies revealed reduced perfusion of vasa recta, and tubular injection studies showed unobstructed tubules and collecting ducts. In the late stage, medullary vascular obliteration and intratubular debris with tubular obstruction were seen. This evidence suggests that RPN in this model is initiated by vasoconstriction rather than direct tubular toxicity.

Candida-associated renal papillary necrosis.

An autopsy series of 42 patients who had visceral candidiasis was studied to determine the incidence and clinicopathologic features of Candida-associated renal papillary necrosis. Papillary necrosis was found in nine patients (21%), associated in all instances with fungal invasion of the kidney. The single most common associated condition was prematurity, present in three neonates, and antibiotic or immunosuppressive therapy was a contributing factor in most instances. The clinical significance of candidal papillary necrosis is unclear because most patients had other causes of renal failure. Antemortem diagnosis is exceptionally difficult and had not been made in any of these patients. Pyelograms have aided in the diagnosis in only one well-documented case in the literature. This study shows that the pathologic features of candidal renal papillary necrosis correlate well with the findings in experimentally induced disease, and that this lesion appears to be more common than previously suspected.

Infection and papillary necrosis. Scanning electron microscopic comparison with bladder infection.

A case of papillary necrosis in a diabetic patient with Escherichia coli urinary tract infection is reported. Infectious contribution to the disease is presented, and the electron microscopic similarities of bladder response to infection are discussed.

Renal papillary necrosis in thyroid carcinoma.

A thirty-four-year-old man with progressive visual impairment was found to have thyromegaly and renal insufficiency at the time of admission. Subsequent evaluation demonstrated bilateral optic neuritis and a thyroid nodule which proved to be a follicular carcinoma. Nephrologic studies revealed bilateral papillary necrosis and chronic interstitial nephritis on biopsy. The patient's renal function stabilized and twenty-four-hour protein excretion diminished after hemithyroidectomy. Carcinoma-related protein production may have played a role in the development of the observed renal lesions. Carcinoma should be a consideration in patients with unexplained papillary necrosis.

Simultaneous occurrence of transitional cell carcinoma and urothelial adenocarcinoma associated with xanthogranulomatous pyelonephritis.

We report on a patient with xanthogranulomatous pyelonephritis, in situ transitional cell carcinoma, and focal prosoplasia revealing abrupt conversion of transitional epithelium to moderately well-differentiated adenocarcinoma. The etiology and pathogenesis of mucinous adenocarcinoma in the renal pelvis very likely involves the prosoplastic transition of pre-existing transitional carcinoma to adenocarcinoma. The urologist should be aware of the increased possibility of this tumor developing in a patient with longstanding infection, and frozen section should be performed more often because the gross structure of the tumor frequently appears normal. This permits the urologist to change his surgical strategy if frozen section is positive for tumor.

Comprehensive evaluation of canine renal papillary necrosis induced by nefiracetam, a neurotransmission enhancer.

The effects of nefiracetam, a neurotransmission enhancer, on renal biochemistry and morphology with toxicokinetic disposition were investigated in both in vivo and in vitro systems. In the in vivo studies with rats, dogs, and monkeys, only the dog exhibited renal papillary necrosis. Namely, when beagle dogs were orally administered with 300 mg/kg/day of nefiracetam over 11 weeks, decreased urinary osmotic pressure was noted from week 5, followed by increases in urine volume and urinary lactate dehydrogenase from week 8. The first morphological change was necrosis of ductal epithelia in the papilla in week 8. In toxicokinetics after 3 weeks of repeated oral administration to dogs, nefiracetam showed somewhat high concentrations in serum and the renal papilla as compared with rats and monkeys. As for metabolites, although metabolite-18 (M-18) concentration in the renal papilla of dogs was between that in rats and monkeys, the concentration ratios of M-18 in the papilla to cortex and papilla to medulla were remarkably high. In the in vitro studies, while nefiracetam itself showed no effects on the synthesis of prostaglandin E2 and 6-keto-prostaglandin F1alpha, a stable metabolite of prostaglandin I2, in canine renal papillary slices, only M-18 among the metabolites clearly decreased both prostaglandin syntheses. The basal prostaglandin synthesis in canine renal papillary slices was extremely low relative to those in rats and monkeys. Taken together, certain factors such as basal prostaglandin synthesis, M-18 penetration into the renal papilla leading to an intrarenal gradient, and inhibitory potential of M-18 on prostaglandin synthesis were considered to be crucial for the occurrence of renal papillary necrosis in dogs.

Effect of 16,16-dimethyl PGE2 on renal papillary necrosis and gastrointestinal ulcerations (gastric, duodenal, intestinal) produced in rats by mefenamic acid.

Mefenamic acid, given orally to rats at a single dose of 1200 mg/kg, produced renal papillary necrosis (RPN) in 63% of animals. The incidence was reduced to 27% by 16,16-dimethyl PGE2 (dmPGE2), given at an oral dose of 0.75 mg/kg t.i.d. RPN is likely to be caused by the renal prostaglandin depletion elicited by mefenamic acid, an inhibitor of prostaglandin cyclooxygenase. Substitution with dmPGE2 reduces RPN presumably by preventing the prostaglandin depletion. We conclude that the prostaglandin used is cytoprotective for the kidney. Mefenamic acid, like most nonsteroidal anti-inflammatory compounds (NOSAC), produced ulcerations of the small intestine (jejunum and ileum). These were prevented by dmPGE2 (intestinal cytoprotection). Unlike most other NOSAC, however, mefenamic acid produced duodenal ulcers in nearly all animals (80%). Of these ulcers, 88% were perforated. Twenty-five of the twenty-six animals that died had a perforated ulcer. These duodenal ulcers were also prevented by dmPGE2. Mefenamic acid-induced ulcers could be used as an experimental model for testing agents with a potential for preventing or healing duodenal ulcers.

Pattern of renal cortical scarring after experimental papillary necrosis.

Three types of renal cortical damage were found in rats 2 mth after papillary necrosis had been induced by ethylenimine: (1) Circumscribed areas of interstitial nephritis affecting either deep or superficial nephrons. (2) Wedge-shaped or conical scars, extending from capsule to inner medulla. (3) Widespread tubular dilatation and cyst formation with a diffuse increase in interstitial tissue, usually associated with dense fibrous repair of the papillary remnant. The extent and character of the cortical changes did not appear to be determined by the severity of the papillary necrosis, and even the more severe cortical lesions were not accompanied by any major reduction in kidney size. Although these chronic experimental cortical lesions are the products of a less complex and less protracted natural history than end stage cortical damage in analgesic nephropathy, some of the factors influencing their evolution, such as infection, may also determine the natural history of the clinical lesion.

Papillary necrosis in experimental renal transplantation in the rat.

Renal papillary necrosis is a frequent complication of unsuccessful renal transplantation in rats, occurring in both isografts and allografts. Papillary necrosis does not occur alone, but only and inevitably in association with severe cortical damage. The pattern of the lesion is different from other forms of papillary necrosis in that the least severe lesions occur in the outer medulla and the more severe lesions involve both medulla and papilla. The incidence of papillary necrosis is increased in isografts, but not in allografts, by longer preservation times. It is suggested that the principal underlying cause may be damage to medullary capillaries, occurring either during preservation or as a consequence of rejection and leading to medullary ischemia.

Experimental pyelonephritis and papillary necrosis in the Gunn rat.

Homozygous and heterozygous female Gunn rats show increased susceptibility to experimental urinary infection. The strain develops pyelonephritis after intravesical inoculation of Proteus mirabilis in numbers which fail to induce the lesion in albino rats, and severe pyelonephritis is frequently complicated by papillary necrosis. The basis for this enhanced susceptibility has not been defined, but the occurrence of the phenomenon in both homozygous and heterozygous rats indicates that it is not caused primarily by high plasma levels of unconjugated bilirubin or by the deposition of bilirubin in the tip of the renal papilla. The increased susceptibility of the homozygous Gunn rat to ascending urinary tract infection provides supporting evidence for the suggestion that infection may complicate the natural history of experimental analgesic nephropathy in this strain and is relevant to the clinical association of analgesic nephropathy and urinary infection.

Spontaneous papillary necrosis in the heterozygous Gunn rat.

Spontaneous papillary necrosis develops in aging heterozygous non-jaundiced Gunn rats. The lesion is situated in the subapical or mid papilla and in its earliest stages is manifest by the appearance of amorphous material in the interstitial space. This is seen in plastic-embedded sections taken from rats 6 months old. In its later stages, the accumulation of amorphous material is accompanied by loss of interstitial cells and cyst formation, but there is no associated inflammatory reaction. The largest lesions are found in the oldest rats, but even in these animals the macroscopic appearance of the papilla is normal. Similar papillary changes were not found in albino or homozygous Gunn rats, but in aging albino rats there was loss of papillary interstitial cells without accumulation of amorphous material.

Localization of medullary functional abnormalities in experimental papillary necrosis.

Renal function was investigated in rats 3 d or 4 wk after an injection of 2-bromoethylamine hydrobromide (BEA) 40-125 mg/kg body weight. Animals developed necrosis of renal papillary structures other than collecting ducts (subtotal renal papillary necrosis) (RPN) or necrosis of all structures in the distal papilla, including collecting ducts (total RPN). Glomerular filtration rate (GFR) was reduced in animals with total RPN (667 +/- SD 168 microliters/min/100 g body weight, n = 5) in comparison with controls (1065 +/- 103, n = 5; P less than 0.001) but was unimpaired in animals with subtotal RPN (1162 +/- 200, n = 4; P greater than 0.3). Maximum urinary osmolality (Umax) was significantly decreased in subtotal RPN (1241 +/- 388 mOsm/kg, n = 4) and in total RPN (626 +/- 293, n = 5) in comparison with controls (2216 +/- 293, n = 5). Free water reabsorption (TcH2O) was impaired in animals with total RPN but was not significantly reduced in the presence of subtotal RPN. Total RPN did not affect free water formation (CH2O). It is concluded that impaired TcH2O occurs in RPN because of the damage to the collecting duct, and not because of necrosis of the thin limbs juxtamedullary nephrons.

Further studies of the acute effects of phenylbutazone, oxyphenbutazone and indomethacin on the rat kidney.

Experiments were donducted on rats to determine the lowest dose of either phenylbutazone or indomethacin capable of producing papillary necrosis and in each case it was found to be 50 mg/kg body weight. A single dose of oxyphenbutazone (444 mg/kg), a major metabolite of phenylbutazone in man, produced patchy cortical necrosis, which became more extensive during daily administration for 4 days, despite evidence of regeneration. Although papillary necrosis as such was never seen with this substance, there was evidence of damage to the lower nephron in the form of tubular necrosis and calcification.