Charles Dechenne

Proliferative glomerulonephritis in rats: evidence that mononuclear phagocytes infiltrating the glomeruli stimulate the proliferation of endothelial and mesangial cells

Abstract. A proliferative, non‐crescentic, glomerulonephritis (GN) was induced in rats preimmunized with rabbit IgG by injecting a sub‐nephrotoxic dose of rabbit anti‐GBM IgG. Control rats either received anti‐GBM IgG only, or were totally irradiated (800 rads, kidneys protected) 2 days before the second injection. All the GN rats developed a severe proteinuria within 2–4 days after the injection of anti‐GBM IgG, contrarily to the control rats. At the same time, many mononuclear cells, of predominantly extra‐renal origin, infiltrated the glomeruli. Glomeruli were isolated from GN, normal and control rats and were cultivated in RPMI medium. In normal and control rat cultures, epithelial and mesangial cells were observed. In GN rat cultures, not only epithelial and mesangial cells, but also endothelial and macrophagic cells were identified; the outgrowth capacity of the mesangial cells was enhanced. These data were particularly evident in cultures of GN glomeruli isolated within 2–4 days after the induction of the renal disease, exactly when the glomeruli were infiltrated by a large number of mononuclear phagocytes. It is suggested that the mononuclear phagocytes infiltrating the glomeruli of rats with this model of GN stimulate the proliferation of endothelial and mesangial cells in vitro.

Acute experimental glomerulonephritis induced by the glomerular deposition of circulating polymeric IGA-concanavalin A complexes

The perfusion of polymeric or secretory IgA-Concanavalin A complexes into the aorta of rats led to a mannose-dependent binding of both IgA and lectin to the glomerular capillary wall, as shown by double immunolocalization experiments, by quantitative analysis of the amount of radiolabelled complexes bound per g of kidney, and by blocking experiments with the corresponding carbohydrate. Rats injected with amounts of those complexes as low as 500 micrograms developed, one hour later, a focal and segmental proliferative glomerulonephritis characterized by the deposition of injected complexes and of rat C3 and rat fibrin/fibrinogen in most glomeruli; focal thrombosis and small areas of necrosis in 10 to 15% of glomeruli, confined to the periphery of a single lobule of the tuft and segmental infiltration of these glomeruli by polymorphonuclear leucocytes and platelets. At the same time, many mesangial cells exhibited a hyperactive appearance, and red blood cells were noted in tubular lumens. In contrast, rats similarly injected with either monomeric IgA-ConA complexes, multimeric or secretory IgA-peanut agglutinin complexes or polymeric or monomeric IgA aggregates of comparable apparent molecular weight did not develop obvious glomerular lesions within one hour. The data indicate that performed polymeric IgA-ConA complexes can specifically bind to glomerular structures in vivo and trigger acute glomerular lesions locally, analogous to those observed in some glomerular diseases associated with a cryoglobulinaemia.The perfusion of polymeric or secretory IgA-Concanavalin A complexes into the aorta of rats led to a mannose-dependent binding of both IgA and lectin to the glomerular capillary wall, as shown by double immunolocalization experiments, by quantitative analysis of the amount of radiolabelled complexes bound per g of kidney, and by blocking experiments with the corresponding carbohydrate. Rats injected with amounts of those complexes as low as 500 µg developed, one hour later, a focal and segmental proliferative glomerulonephritis characterized by the deposition of injected complexes and of rat C3 and rat fibrin/ fibrinogen in most glomeruli; focal thrombosis and small areas of necrosis in 10 to 15% of glomeruli, confined to the periphery of a single lobule of the tuft and segmental infiltration of these glomeruli by polymorphonuclear leucocytes and platelets. At the same time, many mesangial cells exhibited a hyperactive appearance, and red blood cells were noted in tubular lumens. In contrast, rats similarly injected with either monomeric IgA-ConA complexes, multimeric or secretory IgA-peanut agglutinin complexes or polymeric or monomeric IgA aggregates of comparable apparent molecular weight did not develop obvious glomerular lesions within one hour. The data indicate that preformed polymeric IgA-ConA complexes can specifically bind to glomerular structures in vivo and trigger acute glomerular lesions locally, analogous to those observed in some glomerular diseases associated with a cryoglobulinaemia.

Tissue culture of normal rat glomeruli. Basement membrane biosynthesis by homogeneous epithelial and mesangial cell lines.

Abstract 1. 1. The biosynthesis of basement membrane polypeptides by confluent cultures of normal rat glomerular epithelial or mesangial cells has been studied by immunological and biochemical techniques. 2. 2. The epithelial cells synthesize and secrete GBM polypeptides, sharing some antigenic determinants with type IV collagen, into the culture medium. 3. 3. On the contrary, the mesangial cells synthesize and secrete GBM polypeptides different from type IV collagen into the culture medium.

Evidence for a particular binding capacity of rat peritoneal macrophages to rat glomerular mesangial cells in vitro.

Abstract. The adhesion of normal rat peritoneal macrophages to normal rat glomerular epithelial or mesangial cells has been studied in vitro after a 60 min incubation at 37°C. After washing, the cell preparations were examined by phase contrast or scanning electron microscopy. Quantitative studies were also performed using macrophages labelled with 99mTc tin colloids. Peritoneal macrophages predominantly adhered to the cultured mesangial cells. The percentage of labelled macrophages adhering to these cells was about 10 times higher than that of labelled macrophages adhering to the cultured epithelial cells. This percentage increased proportionally to the number of labelled macrophages added, and was strongly reduced by the prior incubation of macrophagic cells with aggregated IgG, with anti‐fibronectin IgG, or with F(ab)2 fragments of anti‐fibronectin IgG. Furthermore, the macrophage‐mesangial cell interaction was significantly reduced by the prior incubation of mesangial cells with anti‐fibronectin IgG or with F(ab)2 fragments of anti‐fibronectin IgG. The data demonstrate that normal rat peritoneal macrophages preferentially adhere in vitro to normal rat glomerular mesangial cells, and that this binding may be modulated, at least, by: (a) the Fc receptor binding activity of macrophages; (b) the fibronectin molecules available at the surface of macrophages and of mesangial cells.

Increased incidence of cerebral hemorrhage mortality in patients with analgesic nephropathy on hemodialysis

Dr. A. Chachati, Hôpital de Bavière, Institut de Médecine B, 66, bd de la Constitution, B-4020 Liège (Belgium) Dear Sir, Analgesic nephropathy (A) is a serious problem in Belgium with an incidence of 18,4% of patients with end-stage renal failure [1]. We wish to report here a retrospective autopsic analysis of 75 hemodialyzed patients: 12 with A and 63 with nonanalgesic nephropathy (NA). The results of this study showed a significantly higher incidence of cerebral hemorrhage as a cause of death (table I) in the A group: 25%) (3/12) as compared to 3%) (2/63) in the NA group. (Yates corrected χ2 = 4.43, p < 0.025). The mean age at death of patients was comparable in both groups: 51 ± 12 years in the A and 56 ± 11 years in the NA group. Female preponderance, as already described [2], was observed in the A group with a female/male ratio of 75% as compared to 38% in the NA group (χ2 = 5.57, p < 0.025). In order to explain the reasons of such a higher incidence of cerebral hemorrhage, various autopsic (left ventricular thickness, aortic and coronary atherosclerosis appreciated macroscopically – (score 0–5) -‚ presence of acute or healed myocardial and cerebral infarction) and clinical parameters (blood pressure before and during hemodialysis treatment and analysis of the clinical causes of death of patients with A on hemodialysis dying during the same period, but not autopsied) were compared in each group. First, the analysis of the blood pressure levels prior to the start of hemodialysis treatment showed no difference between both groups in the relative number of patients presenting hypertension (74% in the A vs. 83% in the NA group), in the severity (17% of the A group patients presented a blood pressure > 200/120 mm Hg as compared to 18% in the NA group), and in the duration of hypertension (42% of the A group patients were known to have blood pressure levels > 160/95 mm Hg for at least 2 years as compared to 49%) in the NA group). Second the thickness of the left ventricle of the A group patients, measured at autopsy, showed values similar to that of the NA patients (1.90 ± 0.18 vs. 1.94 ± 0.18 cm). The relative percentage of analgesic patients presenting severe aortic atherosclerosis (score 4–5) Table I. Causes of death Causes of death NA

Isolation and characterization of rat renal glomerular cells in vitro.

Glomerular tufts were isolated from normal rat kidneys and were cultivated in RPMI 1640 medium supplemented with 15% fetal bovine serum. Studies on DNA synthesis demonstrated two peaks (A and B) of cell division. The cells of peak A grew as a monolayer until confluency, exhibited many junctional complexes and microvilli. They were very susceptible to the aminonucleoside of puromycin, as glomerular epithelial cells in vivo. They did not contain many bundles of intracellular microfilaments and were not stained by an anti-factor VIII serum. The cells of peak B formed both monolayered sheets and multilayered bands, exhibited no junctional complexes, but contained large bundles of intracellular fibrillar structures, which were strongly stained by an antimyosin antiserum. They were not stained by an anti-factor VIII antiserum. The B cells exhibited a contractile activity in response to 10(-9) M angiotensin II and were very susceptible to mitomycin C treatment, as glomerular mesangial cells in vivo. They synthesized large amounts of prostaglandins (mainly PGE2). The data suggest that the A cells are visceral epithelial cells, and that the B cells are smooth muscle-like cells derived from the glomerular mesangium.

Electron Microscopic Studies in a Long-Term Follow-Up of a Case of Congenital Nephrotic Syndrome

A boy presenting with a severe congenital nephrotic syndrome diagnosed by histological analysis at the age of 3 weeks was biopsied again 7 years later. The ultrastructural glomerular basement membrane abnormalities depicted in the first biopsy were no longer present in the second one. The number of completely hyalinized glomeruli was not significantly decreased. The GFR remained normal, but a moderate persistent, non-selective proteinuria (800 mg/24 h) was noted without oedema. The patient however developed a progressive perceptive deficit of hearing.

Back pain and renal failure.

A 40-year-old plumber was admitted to the emergency room of our hospital in October, 2003, with bilateral backache for 1 week. He had no other complaints. He had no previous medical history and was not on any treatment. On examination, his temperature (36 ·5°C), heart rate (80 beats per min), and blood pressure (140/70 mm Hg) were normal. There was no rash and no lympha-denopathy. Lungs were clear and heart sounds were normal. There was no oedema and he was passing urine normally. Abdomen was unremarkable except for tenderness of both costovertebral angles. Laboratory tests showed normal blood-cell counts but a severe renal failure: serum creatinine 390 µmol/L (normal: 35-106), with raised uric acid (2268 µmol/L: 200-500). Urinalysis showed microscopic haematuria and moderate proteinuria (600 mg/L). Neither crystals nor amorphous material was detected in the urinary sediment. Abdominal ultrasound showed enlarged kidneys (14 cm in length). A renal biopsy was done and haemodialysis started. The biopsy specimen showed a massive interstitial tumour infiltrate (figure, A) composed of a monomorphous population of small to medium-sized cells with round to oval nuclei, very fine chromatin, and scanty cytoplasm (figure, B). The widened interstitium compressed the tubular luminae but neither urate crystals nor tubular necrosis were seen; there were some mitotic figures. Immunohistochemical studies identified these cells as precursor T lymphoblasts because they were positive for several T-cell antigens, including CD2, CD3, and CD5, as well as for terminal deoxynucleotidyltransferase (TdT) (figure, C and D). The diagnosis of precursor T-lymphoblastic lymphoma was then made. Cytological examination of a bone-marrow aspirate showed massive lymphoblastic involvement, indicative of acute lymphoblastic leukaemia. A positron emission transaxial tomography (PET) scan showed increased metabolic activity in all bone-marrow areas, liver, spleen, and kidneys (figure, E). High doses of corticosteroids (intravenous methylprednisolone, 80 mg twice a day for 1 week) led up to a rapid return to normal of renal function. Tumour lysis secondary to corticosteroids could have been responsible for worsening of hyperuricaemia. Rasburicase (0·2 mg/kg/day for 1 week) was given. Once the final diagnosis was established, standard chemotherapy was started. As of October, 2004, he is on maintenance treatment, feels well, is in complete remission, and his serum creatinine is normal. Severe acute renal failure is a rare presentation of malignant haemopathies. There are two pathophysiological mechanisms. Hyperuricaemia due to increased nucleic-acid catabolism is the most frequent. Uric-acid nephropathy is characterised by tubular necrosis due to uric-acid crystallisation in the tubular lumen. In this setting, urate crystals are easily detectable by light microscopy, the size of the kidneys is within normal range, and patients are usually oliguric.

Relation between urinary proteinases and proteinuria in rats with a glomerular disease.

Electronegative charges of the glomerular filtration barrier play probably an important role in its impermeability to anionic proteins 1–9. Sialic acid 10 (present in laminin) and glycosaminoglycans 11 seem to be the major molecules responsible for this propriety. Neutral proteinases synthetized either by mesangial cells or by monocytes and neutrophils, infiltrating glomeruli in some pathologic states, are able to degrade GBM glycoproteins in vitro 12–14.

BASEMENT MEMBRANE BIOSYNTHESIS BY HOMOGENEOUS EPITHELIAL AND MESANGIAL CELL LINES

Abstract1. The biosynthesis of basement membrane polypeptides by confluent cultures of normal rat glomerular epithelial or mesangial cells has been studied by immunological and biochemical techniques. 2. The epithelial cells synthesize and secrete GBM polypeptides, sharing some antigenic determinants with type IV collagen, into the culture medium. 3. On the contrary, the mesangial cells synthesize and secrete GBM polypeptides different from type IV collagen into the culture medium.