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Antiproteinuric therapy while preventing the abnormal protein traffic in proximal tubule abrogates protein- and complement-dependent interstitial inflammation in experimental renal disease.

In proteinuric glomerulopathies, the excess traffic of proteins into the renal tubule is a candidate trigger of interstitial inflammatory and immune events leading to progressive injury, and a key target for the renoprotective action of antiproteinuric drugs. Among proteins trafficked to the proximal tubule, the third component of complement (C3) can be activated locally and contribute to inflammation at sites of protein reabsorption. Experiments were performed in rats with renal mass reduction (RMR, 5/6 nephrectomy) with the following aims: (1) to study Ig (IgG) and complement deposition in proximal tubules, and interstitial macrophage infiltration and MHC class II expression at intervals after surgery by double immunofluorescence analysis; (2) to assess whether lisinopril (angiotensin-converting enzyme inhibitor [ACEi], 25 mg/L in the drinking water, from either day 1 or day 7) limited IgG and C3 accumulation and interstitial inflammation at day 30. In 7-d remnant kidneys, intracellular staining for both IgG and C3 was detectable in proximal tubules in focal areas; C3 was restricted to IgG-positive tubular cells, and there were no interstitial ED-1 macrophage and MHC II-positive cellular infiltrates. In 14-d and 30-d remnant kidneys, proximal tubular IgG and C3 staining was associated with the appearance of interstitial infiltrates that preferentially localized to areas of tubules positive for both proteins. RMR rats given ACEi had no or limited increases in levels of urinary protein excretion, tubular IgG, and C3 reactivity, and interstitial cellular infiltrates in kidneys at 30 d, even when ACEi was started from day 7 after surgery. These findings document that (1) in RMR, IgG and C3 accumulation in proximal tubular cells is followed by leukocyte infiltration and MHC II overexpression in the adjacent interstitium; (2) ACEi while preventing proteinuria limits both tubular accumulation of IgG and C3 and interstitial inflammation. The data suggest that ACE inhibition can be renoprotective by limiting the early abnormal protein traffic in proximal tubule and consequent deleterious effects of excess protein reabsorption, including the accumulation and local activation of complement as well as the induction of chemokines and endothelin genes known to promote interstitial inflammation and fibrosis.

Analysis of Variance↗

[Partial lipodystrophy with C3 complement deficiency in 8 years old girl].

Lipodystrophy is a rare, heterogenic disorder, leading to the loss of adipose tissue. Several main types of the disease are distinguished according to age of onset and localization of fat atrophy. The authors present the case of 8 years old girl with partial lipodystrophy, C3 complement deficiency and autoimmunologic disorder.

Brain↗

[Partial lipodystrophy and membranoproliferative glomerulonephritis. Apropos of a case].

We have studied a girl seven and a half years old with a renal disease manifested by proteinuria and nephrotic syndrome combined with initial macroscopic hematuria normal blood pressure and persistent depression of the complement C3 levels with the complement activating gamma globulin (C3 Nef) present in serum. The anatomopathological study showed findings of membranoproliferative glomerulonephritis type II with intramembranous deposit (dense deposit disease). An unusual association with partial lipodystrophy was present in this case. A follow-up of five years, and a few considerations about etiopathogenic theories were presented.

Child↗

Mesangial proliferative glomerulonephritis with unusual intramembranous granular dense deposits.

We have studied two patients with histories of upper respiratory tract infection. Hematuria and proteinuria were the presenting renal symptoms in one patients and an acute nephritic syndrome in the other. Serological findings disclosed depression of total hemolytic complement activity with low levels of C3 and the presence of C3Nef activity. Light microscopy showed diffuse mesangial cell proliferation. By immunofluorescence, diffuse deposits of C3 were found in the glomeruli. Ultrastructural studies revealed segmental thickening of the glomerular basement membrane due to the deposition of granular electron-dense deposits in a laminar pattern. We suggest that our cases may represent a variant of hypocomplementemic glomerulonephritis or perhaps the early stages of dense deposit disease.

Adult↗

[Clinical immunology and immunopathology of glomerulonephritis (author's transl)].

Many problems of clinical immunology with regard to glomerulonephritis become evident only when basic immunopathological principles are taken into consideration. The objective of this paper is to contribute to a deeper understanding of both clinical and immunological problems concerning glomerulonephritis and its prognosis and immunotherapy by a presentation and discussion of immunopathological processes.

Animals↗

Membranoproliferative glomerulonephritis (MPGN type I) and dense deposit disease (DDD) in children.

A review of the histologic findings in 27 patients originally classified as having some form of membranoproliferative glomerulonephritis (MPGN) revealed 13 with MPGN Type I and 14 with dense deposit disease (DDD). In all 14 cases where electron microscopy was performed, the histologic diagnosis was confirmed. In nine cases the diagnosis of DDD was easily made in histologic sections on the basis of ribbon-like, brightly PAS positive thickening of the GBM, without "splitting" and with relatively slight mesangial proliferation. However, in five cases the picture closely resembled MPGN Type I, with hypercellularity, "splitting" and only focal ribbon-like thickening of the GBM, which required oil immersion for recognition. There was no correlation between the serum C3 levels and the morphologic diagnosis: nine (4 MPGN Type I, 5DDD) had persistently low C3 levels, two (1 MPGN Tye I, 1DDD) were normocomplementemic, and in 16, the C3 levels varied. C3 levels increased with time in nearly all patients. The clinical course was similar in patients with MPGN Type I and DDD. Significant correlations between the rate of development of renal failure and sex, age of onset, nephrotic syndrome or therapy could not be made. The five year survival rate was 87%; 12 developed renal insufficiency by five years. Although morphologically distinct, these findings suggest that DDD is clinically indistinguishable from MPGN Type I.

Cell Membrane↗

[Partial lipodystrophy (cephalothoracic type) with asymptomatic dense deposit disease (author's transl)].

We report a case of partial lipodystrophy (P.L.D.) of the cephalothoracic type associated with low C3 serum level. In spite of the absence of renal symptom a renal biopsy was performed which demonstrated dense deposits disease characterized by the lack of cellular proliferation and highly segmentary deposits similar to those observed in remission after renal transplantation for these disease. A review of the literature shows the frequent occurrence of this pathological association. In general P.L.D. and complement abnormalities are thought to precede nephropathy. However chronological relationship between the former and the later must be interpreted cautiously as our case shows that dense deposits disease can be associated with P.L.D. in the lack of clinical evidence of renal disorder.

Adolescent↗

Induction of different types of glomerulonephritis by monoclonal antibodies derived from an MRL/lpr lupus mouse.

MRL/Mp-lpr/lpr(MRL/lpr) lupus mice develop glomerulonephritis in which the histopathological manifestations of the disease are characterized by diffuse cell-proliferative, crescentic, and/or wire loop-like lesions, resembling those of human lupus nephritis. Although these lesions are thought to be mediated by antibodies, little data is available to explain these regular variations in glomerular lesions induced by antibodies at the monoclonal level. We studied glomerular lesions of normal or severe combined immunodeficient mice injected with nephritogenic immunoglobulin G3-producing hybridoma clones (2B11.3 and 7B6.8), which we previously established from an unmanipulated MRL/lpr mouse. Both clones caused increased serum levels of immunoglobulin G3 with identical patterns over time and both induced glomerular deposits of immunoglobulin G3 and C3. However, 2B11.3 and 7B6.8 induced glomerular lesions that differed in their histopathological manifestations. The 2B11.3 clone generated cell-proliferative lesions associated with marked Mac-2-positive macrophage infiltrates, but the 7B6.8 clone induced lesions characterized by subendothelial hyaline deposits resembling wire loops. The latter was not associated with significant inflammatory cell infiltrates at any point throughout the progression of the lesion. Thus, our findings suggest that the histopathological variation in glomerulonephritis seen in MRL/lpr mice results from clonally expanded B cell clones that produce nephritogenic antibodies with different pathogenic potencies.

Animals↗

[Progressive partial lipodystrophy; an external problem with internal anomalies].

Progressive partial lipodystrophy (PPL) was diagnosed in two girls aged 6 and 8 years. PPL is characterized by loss of subcutaneous fat, starting in the face and progressing to trunk and arms. Diagnosis is based upon the cachectic appearance and the normal growth parameters. It is a rare disease of unknown aetiology, usually beginning in childhood and more frequent in females. An association with diabetes mellitus, hypertriglyceridaemia and glomerulonephritis has been described. Follow-up should be focused on these and on psychological effects. No causal therapy is available. The facial appearance can be restored by injection of liquid silicones. Life expectancy does not appear to be affected.

Child↗

Complement analysis in children with idiopathic membranoproliferative glomerulonephritis: a long-term follow-up.

Fifty children with idiopathic membranoproliferative glomerulonephritis (MPGN), aged 2-14 years at apparent onset, were monitored for the presence of C3 nephritic factor (C3 NeF) and signs of complement activation in serum. In addition, C3 allotyping was performed in 32 patients. Observation time ranged from 2 to 20 (median 11) years. C3 NeF activity was detected at least once in 60% of the patients (in 11 of 26 with type I, in 15 of 17 with type II, and in four of seven with type III). C3 NeF-positive patients had significantly reduced levels of CH50 and C3 and elevated levels of C3dg/C3d. During follow-up, C3 levels were persistently normal in 62% of the patients with MPGN type I and in 43% with type III but in only 18% with type II. C3 allotype frequencies differed from those found in healthy controls with a significant shift to the C3F/C3FS variants in C3 NeF-positive patients. C3b(Bb)P as a marker for alternative pathway activation was not increased in C3 NeF-positive patients. Despite the presence of C3 NeF activity, C3 levels remained normal in six patients throughout the observation period. C3 NeF became undetectable in six patients, whereas seven developed C3 NeF activity during follow-up. There was no significant difference in renal survival probability in patients with or without C3 NeF activity. Neither C3 variants nor continuous low C3 or low CH50 levels had any prognostic value for the clinical outcome. No factor H deficiency was detected.

Adolescent↗

Differences between membranoproliferative glomerulonephritis types I and III in clinical presentation, glomerular morphology, and complement perturbation.

Data for 26 patients with membranoproliferative glomerulonephritis, type I (MPGN I) and 22 with membranoproliferative glomerulonephritis, type III (MPGN III), as distinguished by glomerular ultrastructure, were analyzed to determine differences in presentation, complement perturbation, and glomerular morphology by light microscopy. MPGN III was detected with greater frequency by the chance discovery of hematuria and proteinuria in the otherwise healthy individual (MPGN III, 63%; MPGN I, 30%; P = .01) and never, in the absence of renal failure, presented with systemic symptoms such as ease of fatigue, weight loss, and pallor, as may patients with MPGN I. The more frequent detection of MPGN III by chance is evidence that its onset is insidious and that for long periods it produces no symptoms or signs. Glomerular proliferation is also less than in MPGN I. Further, in MPGN III, the complement perturbation and glomerular immunofluorescence give no evidence of classical pathway activation, for which there is abundant evidence in MPGN I. Even with severe hypocomplementemia in MPGN III, C3 nephritic factor, another cause of hypocomplementemia, is rarely detectable and then in very low concentration. The cause of the complement perturbation in MPGN III has so far escaped identification. Although these observations give evidence that MPGN III is distinct from MPGN I, there is compelling evidence from other studies that a predisposition to both types is inherited and that similar genetic factors are operative in the two types. Because their genetic basis appears to be the same, it must be concluded that despite their differences, types I and III are variants of the same disease.

Complement C3↗