Light-heavy chain deposition disease progressing to multiple myeloma

Light chain deposition disease (LCDD) and light and heavy chain deposition disease (LHCDD) are rare clinical entities that have been associated with multiple myeloma, with monoclonal gammopathy of unknown significance (MGUS), or without any detectable protein abnormality. Renal failure is common, the diagnosis is difficult and prolonged survival is rare. The first patient with LHCDD and MGUS who progressed to multiple myeloma after 11 years is presented. A rising level of monoclonal IgA immunoglobulin, bone marrow plasmacytosis, and the presence of multiple bone marrow lesions on magnetic resonance imaging provided the first evidence of disease evolution. When management of serious complications permits a long survival, some patients with LCDD or LHCDD will develop multiple myeloma.

Glomerular antigens in severe hereditary nephrosis

In search of the basic defect and cell type responsible for the massive treatment-resistant proteinuria of congenital nephrotic syndrome of the Finnish type (CNF), we examined tissue samples of CNF kidneys using established antibody and lectin markers of various glomerular cell types. Markers of vascular endothelium (antibodies to factor VIII and a human homologue of podocalyxin (anti-PHM5) and UEA I lectin) showed no qualitative changes in the endothelial cells of glomeruli or peritubular areas in CNF as compared with controls. Markers of glomerular mesangial cells (antibodies to desmin, smooth muscle actin, RCA I lectin) revealed a secondary increase in mesangial reactivity reflecting the sclerosis and expansion of the mesangial areas in CNF. Markers of visceral epithelial cells (antibodies to a human homologue of podocalyxin, C3b receptor, vimentin, common lymphocytic leukemia antigen, gp44, and the WGA, LFA and, after neuraminidase treatment, PNA lectin) failed to show appreciable qualitative changes in CNF kidney samples. Interestingly, the alpha 2 beta 1 integrins appeared greatly reduced in all CNF samples studied, possibly explaining the mechanisms of CNF-associated proteinuria.

Spatial arrangement of IgA and C3 as a prognostic indicator of IgA nephropathy

The histological picture of primary glomerulonephritis with glomerular IgA deposition (IgA nephropathy and Henoch-Schönlein disease) can vary from minimal mesangial involvement to severe endocapillary and/or extracapillary proliferation. Local activation of the complement cascade by glomerular IgA deposits and release of anaphylactoid factor are considered to be major triggers of inflammation, but clear-cut correlations between the severity of the histological findings and the intensity of glomerular deposition of immunoglobulin and complement fractions are still lacking. The purpose of this study was to investigate the spatial distribution of IgA and complement in mesangial deposits with confocal laser scanning microscopy (CLSM) and to correlate specific patterns of IgA-complement interaction with glomerular damage. Two groups of patients have been studied, one with mild to moderate diffuse mesangial proliferation and the other with diffuse proliferative endocapillary and/or extracapillary patterns. In milder forms of the disease, the majority of the immune deposits are composed of both IgA and C3, coated by an outer layer of IgA alone. Large C3 deposits, or deposits composed of IgA and C3 without an outer coat of IgA, were associated with more severe histological lesions. The results suggest that free access of active complement components to cell and/or mesangial matrix receptors could trigger a cytolytic reaction and that immunoglobulins seem to act as a protective layer on C3 components.

In situ hybridization of interleukin 6 in diabetic nephropathy

Increased mesangial expansion is one of the most characteristic histological changes in diabetic nephropathy (DN). Although the pathogenesis of DN remains unclear, recent studies associate interleukin (IL) 6 with mesangial proliferative glomerulonephritis. To elucidate the expression and localization of IL-6 mRNA in renal tissues of patients with DN, a high-resolution in situ hybridization using digoxigenin-labeled oligonucleotide was performed. Patients were divided into three groups based on light microscopy findings: mild (group 1), moderate (group 2), and severe (group 3) mesangial expansion. The relationship between the expression of IL-6 mRNA and the degree of glomerular mesangial expansion in DN was examined. Individual cells positive for IL-6 mRNA were observed in glomeruli. These cells were mesangial cells, glomerular epithelial cells, and Bowman's capsule. The signal intensity was strongest in tissues from group 2 but was weak in those from groups 1 and 3. Most cells in the area of mesangial proliferation were strongly stained for IL-6 mRNA, and few positive cells were found in the Kimmelstiel-Wilson nodular lesion. In the interstitium, some tubules, particularly atrophic tubules, and some infiltrating cells were positively stained for IL-6 mRNA. The interstitial expression of IL-6 mRNA correlated significantly with the degree of interstitial injury and was remarkable in tissues from groups 2 and 3. We conclude that IL-6 mRNA is expressed by glomerular resident cells and interstitial cells in the renal tissue of patients with DN and that its expression may be associated with mesangial proliferation and may be involved in the tissue injury of DN.

The role of a complement regulatory protein in rat mesangial glomerulonephritis

The host cells are protected from the indiscriminate attack of homologous complement by the membrane-associated complement regulatory proteins. A mouse monoclonal antibody (mAb) 512 (immunoglobulin G1 subclass) has recently been described that recognizes and inhibits the function of a rat complement regulatory protein, a rat homologue of mouse Crry/p65. The aim of this work is to assess the role of a complement regulatory protein (512Ag) recognized by mAb 512 in the complement-dependent glomerular injury induced by mAb OX7 against rat Thy-1.1. For the induction of mesangial injury, the left kidney of a rat was perfused with a combination of OX7 and 512 and the perfusate was discarded from the renal vein (Group I). After the renal artery and vein were restored, the left kidney was connected to the systemic circulation. Rats were euthanized 3 h, 2 days, and 14 days later. Rats perfused either with OX7 (Group II) or with 512 (Group III) or with vehicle only (Group IV) were used as controls. At 3 h, rats of Group I showed more prominent cellular infiltration and mesangial lysis and more C3 deposition in the glomeruli than rats of Group II. Rats of Groups III and IV showed no significant changes. At Day 2, there was still significant mesangial lysis and leukocyte infiltration in Group I rats, whereas rats in other groups showed an almost normal appearance. Glomerular injury in Group I rats returned to normal by Day 14.

Atrial natriuretic peptide stimulates the expression of transforming growth factor-beta in cultured murine mesangial cells: relationship to suppression of proliferation

Atrial natriuretic peptide (ANP) is a growth suppressor for a variety of different cell types including cultured mesangial cells. This study examined the effects of ANP on the expression and synthesis of transforming growth factor-beta (TGF-beta) in a cultured murine mesangial cell line (MMC). Full-length rat ANP as well as 8-bromo-cGMP, but not ring-deleted ANP analogues, induced, in a dose-dependent manner, TGF-beta 1 mRNA expression in MMC. Moreover, full-length ANP and 8-bromo-cGMP stimulated the synthesis and release of TGF-beta 1 into cell culture supernatants as measured by a specific enzyme-linked immunosorbent assay and mink cell bioassay. The induction of TGF-beta 1 by 10(-6) M ANP and 10(-4) M 8-bromo-cGMP for 24 h was also documented by western blotting of MMC culture supernatants. However, transient transfection studies in MMC with three different murine TGF-beta 1 reporter gene constructs revealed only little stimulation of activity after ANP treatment, suggesting that posttranscriptional activation may mainly contribute to TGF-beta mRNA induction. Functional studies demonstrated that the ANP-mediated inhibition of mitosis, induced by 5% fetal calf serum, is partly abolished in the presence of a neutralizing anti-TGF-beta 1-3 antibody. In addition, the antiproliferative effects of exogenous 8-bromo-cGMP are also attenuated by anti-TGF-beta 1-3 antibody. These findings indicate that ANP stimulates TGF-beta expression in MMC and that the antiproliferative effects of ANP in this cell line may be mediated, at least to some extent, by the endogenous induction of TGF-beta. An increase in intracellular cGMP is most likely the mediator of this TGF-beta 1 induction. Considering the fibrogenic effects of TGF-beta, these findings may be important in the development of glomerulosclerosis in situations with an increase in local or systemic ANP.

Anti-mesangial and anti-endothelial cell antibodies in IgA mesangial nephropathy

In the present study we verified by solid phase ELISA the presence of antibodies against mesangial and endothelial cell constituents in patients with IgA-GN and Schoenlein-Henoch syndrome (SH). An antigen extract was prepared by sonication of human mesangial cell (MC) monolayers between third and fifth subculture and coated at 20 micrograms/ml on microtiter plates where sera were tested by incubation for 2 h at 37 degrees C and addition of peroxidase-conjugated anti-human IgG or IgA. In comparison to 86 normal controls, increased levels of IgG anti-MC antibodies were found in 15/84 patients with IgA-GN and 4/11 with SH. IgA antibodies were always negative. Furthermore anti-endothelial cell antibodies (AECA) were sought in the same patients and controls by ELISA as previously described. Increased levels of IgG and IgA AECA were found in 25/62 and 24/46 patients respectively. A cross-inhibition test showed that preadsorbment of positive sera for both IgG anti-MC and IgG AECA on endothelial cells in culture resulted in an inhibited binding of IgG to MC. HPLC-ELISA and Western blot analysis of the MC extract showed a significant binding of IgG from ELISA-positive sera to a protein band of 25-50 kD. Similar results were obtained by Western blot analysis of an endothelial cell extract. These results suggest the identity of the antigens recognized by IgG antibodies on endothelial cells and MC in patients with IgA-GN.

A clinicopathological study of idiopathic nephrotic syndrome in children

This paper retrospectively examines the association of outcome with histological and clinical manifestations in 107 pediatric patients with idiopathic nephrotic syndrome (INS). At the time of renal biopsy, the patients were between 2 and 15 years of age. The interval from the onset of the disease to renal biopsy ranged from 1 to 156 months with a mean of 21 months. Continuous clinical follow-up was successfully conducted in 96 patients. The average duration of INS in these patients was 86.6 months (31 to 208 months). IgM deposition in the mesangium may play an important role in the pathogenesis of INS and our data showed that even in a minor glomerular abnormality (MCNS) subgroup, nearly half of the cases (42.9%) showed mesangial IgM deposition. However, the severity of hematuria, response to drug therapy with either steroids or cyclophosphamide, and the outcome, were not related to the presence or absence of IgM deposition, but were more closely associated with the type of histological category. The subgroup of patients with focal segmental glomerulosclerosis (FSGS) and diffuse mesangial proliferation (FSGS + DP) showed the most significant ultrastructural changes with positive mesangial IgM deposition (73.6%). The presence of IgM deposition in most of the patients in the subgroups with diffuse mesangial proliferative glomerulonephritis (DPGN) and FSGS + DP closely corresponded to the presence of electron-dense mesangial deposition. The FSGS + DP subgroup had a high incidence of denudation, vacuolization and detachment of podocytes, partial collapse of the glomerular basement membrane, and a very high incidence of resistance to steroid therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Progression from Goodpasture's disease to membranous glomerulonephritis

An unusual case of a patient with Goodpasture's disease presenting with hemoptysis, severe iron deficiency anemia and microscopic hematuria and proteinuria is described. Both circulating and tissue anti-glomerular basement membrane (GBM) antibodies were present, and renal function remained normal throughout. Immunosuppressive therapy was given for subclinical pulmonary hemorrhage with successful resolution of anemia and disappearance of the circulating anti-GBM antibody. Nine months after presentation he developed nephrotic range proteinuria and a repeat renal biopsy revealed membranous glomerulonephritis with no evidence of his original disease. Both the Goodpasture's associated HLA-DR2 and the membranous associated HLA-DR3 class II antigens were present. The association of antibody mediated and immune complex glomerulonephritis is discussed. The simultaneous presence of HLA-DR2 and HLA-DR3 may predispose to this association.

Effects of complement activation on the expression of CD59 by human mesangial cells

Human mesangial cells (HMC) were analyzed for their expression of 20-kDa homologous restriction factor (CD59), a glycophospholipid-anchored regulatory protein of the complement cascade. Flow cytometric analysis showed that CD59 was expressed on the HMC membrane and, following the activation of the terminal pathway complement components, CD59 expression on the HMC membrane increased. Northern blot analysis showed that CD59 mRNA levels increased by complement activation. Of interest, CD59 mRNA levels increased by soluble complement activation product, zymosan-activated C8-depleted serum, but not zymosan-activated C5-depleted serum. This effect of soluble complement activation product was due to the presence of the action of C5a. Thus, recombinant C5a increased CD59 mRNA levels. The capacity of CD59 to reinsert into rat E and inhibit C-mediated lysis was inhibited by mAb against CD59 (1F5). Metabolic labeling using [35S]cysteine showed that the molecular mass of CD59 in HMC was 20 kDa. In conclusion, CD59 is present on HMC and the expression of CD59 is controlled by at least two steps of complement activation pathway, C5 and C8.

Paramesangial glomerular deposits in membranoproliferative glomerulonephritis type II correlate with hypocomplementemia

To gain support for a previously proposed hypothesis that nephritic factors predispose to chronic glomerulonephritis, the glomerular deposits of patients with membranoproliferative glomerulonephritis type II have been studied by electron microscopy and immunofluorescence and the results correlated with the C3 level at the time of biopsy. If, as hypothesized, circulating convertase predisposes to nephritis, finding that the glomeruli of patients hypocomplementemic at biopsy, presumably with nephritic factor-stabilized convertase in their circulation, differ from those of patients normocomplementemic at biopsy would suggest that circulating convertase in some way alters the glomerulus. Among 25 biopsy specimens from 12 patients, hypocomplementemia did not correlate with capillary loop deposits, but there was strong correlation with deposits in the paramesangial region as detected by electron microscopy. Of 11 patients who were normocomplementemic at biopsy, none had paramesangial deposits in their glomeruli. Of 14 patients who were hypocomplementemic at biopsy, deposits were present in the paramesangium in 12 patients (P < 0.001). The deposits were either on both sides of the paramesangial segment of the basement membrane (waist basement membrane related) or in apposition to the paramesangial basement membrane in a subepithelial position only. The detection of paramesangial deposits in the ultrastructure correlated with the detection of C3-containing mesangial granules by immunofluorescence; immunoglobulin G, C5, properdin, and factor B could not be demonstrated in these granules. The study identifies the mesangial deposits described by others in membranoproliferative glomerulonephritis type II as paramesangial deposits and, more importantly, demonstrates that their presence correlates closely with hypocomplementemia. It is likely that these deposits in some way result from the presence in the circulation of convertase stabilized by the nephritic factor of the amplification loop.

Effects of dihydrotestosterone and estradiol on experimental IgA nephropathy induced by vomitoxin

Ingestion of the trichothecene vomitoxin (VT) by mice induces effects that mimic the common human glomerulonephritis, IgA nephropathy (IgAN). These include elevation of serum IgA, IgA immune complexes, and mesangial IgA deposition. Based on previous observations that male mice are more prone to VT-induced IgAN, the effects of castration of male and female B6C3F1 mice and sex hormone supplementation on several immunopathologic indicators of the disease were compared. In the first study, castrated and intact male and female mice were fed control AIN-76A diet or the same diet containing 10 ppm VT for 12 weeks. At Week 12, all but the intact female group fed VT exhibited increased serum IgA, with castrated female mice having greater levels than intact females. When microscopic hematuria was used as an indicator of disease severity in intact VT-fed mice, erythrocyte counts for males exceeded those for females at weeks 4 and 12. VT-fed, castrated females exhibited greater hematuria than intact counterparts, whereas VT-fed, castrated males had lower urinary erythrocyte counts than intact counterparts. In a second study, castrated male and female mice were implanted with controlled release pellets of placebo, 5 alpha-dihydrotestosterone (DHT), or 17 beta-estradiol (E2) and then were fed either control diet or a 10 ppm VT diet for 8 weeks. Castrated male and female mice treated with VT and DHT pellet exhibited more severe hematuria, higher IgA levels, and greater mesangial IgA deposition than mice exposed to the same diet with placebo or E2 pellet at Week 8. While VT-fed animals with an E2 pellet exhibited greater hematuria and mesangial IgA deposition at Week 8 than the placebo groups, their IgA levels were not significantly elevated over those for VT-fed mice with a placebo pellet. Relative to two other pathologic markers for IgAN, the aforementioned effects in both studies were generally consistent with mesangial deposition of complement component C3 but not IgG. The results suggest that (1) enhanced male susceptibility to VT-induced IgAN may be related to modulation by the biologically active androgen DHT and (2) while castration of females increased severity of VT-induced IgAN, supplementation of castrated male or female mice with E2 did not reverse this effect but rather increased disease severity.

Systemic autoimmunity due to mercury vapor exposure in genetically susceptible mice: dose-response studies

Six groups of genetically mercury-susceptible female SJL/N (H-2s) mice were exposed to mercury vapor at a concentration of 0.3-1.0 mg Hg/m3 air for 0.5-19 hr/day 5 days a week for 10 weeks. The absorbed doses were calculated to be between 75 and 2365 micrograms Hg/week/kg body wt (micrograms Hg/week/kg). The correlation between the dose and the concentration of Hg in kidney, spleen, and thymus was highly significant (p < 0.0001; Spearman's rank correlation test). The lowest observed adverse effect level (LOAEL) for serum IgG antinucleolar antibodies (ANoA) was 170 micrograms Hg/week/kg, corresponding to a renal mercury concentration of 4.0 +/- 0.76 micrograms Hg/g wet wt. The correlation between the absorbed dose and the ANoA titer was highly significant (p < 0.0001; Spearman's rank correlation test), and all mice were ANoA-positive at a dose of 480 micrograms Hg/week/kg. High-titer ANoA targeted the nucleolar 34-kDa protein fibrillarin. The LOAEL for B-cell stimulation, measured as an increase in serum IgG2a and IgG1 concentrations, was 360 micrograms Hg/week/kg, but the increase was fivefold higher and also included IgE at a dose of 690 and 2365 micrograms Hg/week/kg. The serum Ig concentrations peaked after 2-4 weeks and then slowly declined but, except for IgE, remained significantly increased during the entire exposure time. Glomerular, mesangial IgG immune complex (IC) deposits, accompanied by systemic vessel wall IC deposits, were first detected at a dose of 480 micrograms Hg/week/kg. The mesangium also showed increased titers of IgM IC deposits and complement factor C3c. The correlation between the absorbed dose, and the individual titer of IgG, IgM, and C3c, was highly significant (p < 0.0001; Spearman's rank correlation test). In conclusion, mercury vapor efficiently induced an autoimmune syndrome in genetically susceptible mice, and the LOAEL for the adverse effects varied in the order ANoA < B-cell stimulation < IC deposits. Comparing the body burden of mercury in mice at the LOAEL for autoantibodies with the body burden in populations of occupationally exposed humans suggests that the safety margin may be narrow for genetically susceptible individuals.

The glomerular mesangium: studies of its developmental origin and markers in vivo and in vitro

Cultured mesangial cells are widely used to explore their role in kidney glomerular functions, but methods to reliably identify these cells in vivo and in vitro are lacking. Furthermore, the proposed relationship of mesangial cells to e.g. fibroblasts and smooth muscle cells has not been systematically studied. Here we wanted to search for markers of practical use also in identifying cultured mesangial cells, and to apply these markers in a study of the origin of glomerular mesangium. No epitopes specific for only mesangial cells could be identified, and no evidence of their true relationship with neural or lymphocytic lineages could be found. Findings with the variety of markers used suggest that mesangial cells may be indistinguishable from smooth muscle cells and fibroblasts. A panel of antibodies, including those against Thy1.1, smooth muscle actin, desmin, cellular fibronectin and beta 1 integrin alpha 1 and alpha 5 chains, and Wistaria floribunda (WFA) and Ricinus communis (RCA I) lectins, were found useful for mesangial cell detection in vivo and in vitro. The origin of glomerular mesangial cells could not be conclusively determined, although the results indirectly suggest that mesangial cells together with endothelial cells migrate to the glomerulus from the outside.

[Prominent subepithelial deposits detected on 2nd renal biopsy in a boy with membranoproliferative glomerulonephritis type I: a case report]

The first renal biopsy of a 7-year-old boy with microscopic hematuria, hypocomplementemia (CH50 20 U/ml, C3 33 mg/dl, C4 13 mg/dl) and otherwise normal renal function revealed lobular, but not diffuse, expansion of glomerular mesangial areas showing mild to marked mesangial cell proliferation and thickening of the capillary walls with double contours as seen on light microscopic examination. Granular C3 deposition along the capillary wall and in the mesangium was observed on immunofluorescent microscopy. Further, electron microscopy showed subendothelial dense deposits and circumferential mesangial interposition. Thus, he was diagnosed as membranoproliferative glomerulonephritis (MPGN) type I. Thereafter, high-dose, alternate-day administration of prednisolone was started. A few months after treatment, microscopic hematuria disappeared and hypocomplementemia improved. The second renal biopsy at 11 years of age showed markedly decreased mesangial cell proliferation and subendothelial dense deposits. However, C3 deposition still persisted and subepithelial dense deposits had increased in number prominently at this time. Whether MPGN type III is a distinct disease entity or a variant of MPGN type I has not yet been established. The morphological changes in this reported case might justify the notion that MPGN type III is a variant form of MPGN type I.

Long-term evolution of patients with isolated C3 mesangial glomerulonephritis

Isolated mesangial C3 proliferative glomerulonephritis is a nephropathy poorly defined among glomerular diseases. Clinical picture is characterized by episodes of gross hematuria and/or persistent or recurrent microhematuria and/or proteinuria. Short-term prognosis (less than 3 years) is considered to be benign, although not much information is available in reference to long-term follow-up. We reviewed all renal biopsies performed in our center between 1978 and 1992 (n = 2,200) in order to study clinical course of these patients. Isolated mesangial C3 deposition was found in 11 cases (0.5%). Isolated proteinuria (> 0.5 g/d) was present in 3 patients and nephrotic syndrome in 2. Hematuria with proteinuria was detected in 5 patients. In one patient hematuria was the only clinical finding. Arterial hypertension was observed in 4 cases. At the time of renal biopsy, renal function was accurately normal in all but one patient. In our series, renal function showed no changes during the first 3 years, accordingly to data referred to in the literature. After 7 years of follow-up, however, renal function was declining in 4 of 5 patients who developed terminal renal failure up to requiring hemodialysis. Therefore, initial benign prognosis ascribed to this glomerulonephritis would not be confirmed in a long-term follow-up.

Glomerular epithelial and mesangial cells differentially modulate the binding specificities of VLA-1 and VLA-2

BACKGROUND

Maintenance of glomerular cell interaction with the complex basement membrane is crucial for the normal functioning of the kidney. Because little is known about the receptors utilized by glomerular cells, we examined the attachment of cultured glomerular cells to extracellular matrix proteins.

EXPERIMENTAL DESIGN

We produced monoclonal antibodies that inhibited the function of rat VLA-1 and VLA-2 and used these antibodies alone and in combination to explore the attachment of glomerular epithelial cells (GEC) and mesangial cells to extracellular matrix proteins in vitro.

RESULTS

Cultured GEC utilize only VLA-2 for attachment to collagen but use it together with VLA-1 for adhesion to laminin. In contrast, mesangial cells use both receptors for their attachment to collagen but utilize only VLA-1 in their interaction with laminin. The use of VLA-1 by GEC and of VLA-2 by mesangial cells was unexpected because the expression of these receptors was barely detectable in an enzyme-linked immunosorbent assay and by immunocytochemistry.

CONCLUSIONS

VLA-1, VLA-2, and VLA-3 are integrin receptors with overlapping specificities in that all have the potential to interact with collagen and laminin. Our studies demonstrate that cultured GEC use VLA-1 and VLA-2 almost exclusively for their adhesion to these ligands, and thus VLA-3 appears to play a negligible role in such attachment. Interestingly, GEC and mesangial cells differentially modulate the ligand binding specificities of VLA-1 and VLA-2. In situ, VLA-1 has been localized within the mesangium, whereas VLA-2 has not been detected within the glomerulus leading to the conclusion that GEC do not use VLA-1 or VLA-2 and that mesangial cells fail to utilize VLA-2. However, our studies have shown that, even when such receptors are barely detectable on the surface of cultured cells by sensitive techniques, they can play a functional role. These results suggest either that the levels of expression in situ are too low for the relatively insensitive immunohistochemical techniques employed, and thus the importance of these receptors to glomerular cell attachment in vivo is under appreciated or that such receptors are the result of de novo expression by glomerular cells when they are subjected to in vitro culture conditions. Because it is known that such conditions may mimic pathologic stress, we are presently examining the expression of these receptors by glomerular cells in various disease models.

Activation of the renin-angiotensin system in anti-glomerular basement membrane antibody-induced glomerulonephritis

Activity of the renin-angiotensin system in the nephrotic syndrome was investigated in rats with acute nephritis induced by anti-glomerular basement membrane (GBM) antibody. Injection of anti-GBM antibody resulted in a transient 2-fold elevation of both plasma renin and angiotensinogen with a peak at 12 h. Angiotensinogen mRNA levels in the liver also rapidly and transiently increased 4-fold at 3 h. The manifestation of acute nephritis, indicated by proteinuria, hypoalbuminemia, hypercholesterolemia and an increase in serum creatinine, following injection of anti-GBM antibody, was inhibited by a single administration of the selective angiotensin II type 1 receptor antagonist TCV-116 (1 mg/kg, p.o.) 2 h before an injection with the antibody, but not by successive administration of this drug for 1 week from 3 d after the injection of antibody. These results suggested that the enhanced generation of angiotensin II by elevated levels of both renin and its substrate in the early phase of anti-GBM nephritis promotes the evolution of acute nephritis via angiotensin II type 1 receptor.

In vitro effects of interleukins on human mesangial cells: implications for glomerulonephritis

Intrinsic glomerular cells, especially mesangial cells, are considered to be actively involved in the pathogenesis of glomerulonephritis (GN), but the precise mechanism(s) remains elusive. We have previously demonstrated that nephritogenic IgA immune complex can stimulate human mesangial cells (HMCs) to increase their production of interleukin-1 (IL-1) and interleukin-6 (IL-6). In order to evaluate the roles of cytokines such as IL-1 and/or IL-6 and mesangial cells as mediators of renal injury in GN, we have now examined the changes of HMCs and their secreted products in vitro, after stimulation with various concentrations of IL-1 and IL-6. Cytokine-activated HMCs showed the following changes: (1) increased cell size, with intracytoplasmic vacuoles, dilated endoplasmic reticulum, increased free ribosomes and polysomes, and mitochondrial swelling; (2) increased cell proliferation, reflected in thymidine incorporation and an increased proportion of S and G2/M phase cells by cell cycle analysis; (3) enhancement of IL-6 mRNA expression in HMCs with stimulation of IL-6 alone or IL-1 plus IL-6; and (4) release of large amounts of platelet activating factor (PAF), thromboxane B2 (TxB2), and superoxide anion. Taken together, these results strongly suggest that mesangial cell proliferation and increased production of immune/chemical mediators and superoxide anion can be directly induced by IL-1 plus IL-6. These changes may lead to ongoing renal injury.

Nephrotic syndrome and acute renal failure associated with hepatitis A virus infection

Acute renal failure has been documented in association with hepatitis A virus (HAV) infection. This report describes a temporal relationship between HAV infection and immune complex mesangial proliferative glomerulonephritis associated with nephrotic syndrome. Animal experimental data have already shown that this is indeed a histological lesion associated with HAV infection. This case report is the first English documentation associating HAV infection with immune complex mesangial proliferative glomerulonephritis.

Nitric oxide mediates immunologic injury to kidney mesangium in experimental glomerulonephritis

BACKGROUND

Nitric oxide (NO), produced from L-arginine by an inducible NO synthase, is an important effector molecule in inflammatory and immunologic tissue injury. The role of NO generation in immunologic injury to glomerular mesangial cells and the effect of dietary restriction of L-arginine on this injury was investigated.

EXPERIMENTAL DESIGN

Acute glomerulonephritis was induced by injection of anti-thymocyte serum (ATS) which binds to an antigen on the glomerular mesangial cell. Complement-mediated mesangial cell lysis follows. The effect of blocking NO production in vivo by administration of the NOS inhibitor NG-monomethyl-L-arginine (L-NMMA) 60 minutes before ATS injection on mesangial cell lysis, and on the severity of disease was assessed. The effect of dietary restriction of L-arginine on mesangial cell lysis in response to ATS injection was also determined.

RESULTS

We report here that blocking NO production in vivo with L-NMMA prevented mesangial cell lysis by 90%. Injection of L-NMMA caused transiently elevated systolic blood pressure, but did not diminish ATS binding to mesangial cells or recruitment of monocyte/macrophages into glomeruli indicating that L-NMMA pretreatment did not limit injury by insufficient glomerular perfusion. ATS-induced proteinuria and increases in urinary nitrite excretion were prevented. Glomerular expression of transforming growth factor-beta and accumulation of extracellular matrix were suppressed by the L-NMMA treatment. Low protein diet (6%), but also selective dietary L-arginine restriction, given for 7 days before induction of the disease mimicked L-NMMA treatment, significantly decreasing mesangial cell lysis. The effect of a low protein diet was abolished by dietary L-arginine supplementation.

CONCLUSIONS

This study strongly implicates NO as a mediator in immune-mediated mesangial cell lysis. The data suggest that limiting NO production by limiting arginine intake might decrease glomerular injury and subsequent glomerulosclerosis.

Morphine enhances deposition of ferritin-antiferritin complexes in the glomerular mesangium

Since increased mesangial accumulation of matrix has been considered to be an important event in the development of focal glomerulosclerosis, we investigated whether morphine, an active metabolite of heroin, can modulate mesangial accumulation of immune complexes. Control or morphine-dependent rats were administered intraperitoneal ferritin (8 mg/100 g body weight) daily for 6 weeks. Body weight, blood pressure, serum creatinine, 24-hour urinary protein and creatinine excretion rates were measured at 3-week intervals. Rats were sacrificed at the end of 6 weeks and kidney tissue was studied by light, immunofluorescence and electron microscopy. Serum creatinine levels and urinary protein excretion rates were not different between control and morphine-dependent rats. All morphine-dependent rats developed hematuria, whereas only 1 control rat developed hematuria. Light microscopy revealed no proliferation of mesangial cells and only a minimal increase in the mesangial matrix. Electron-microscopic studies showed deposition of immune complexes in the mesangial region. Mesangial cells showed aggregation of ferritin in lysosomes. Immunofluorescence studies revealed the presence of IgG staining predominantly in the mesangial region. The majority (60%) of morphine-dependent rats showed a diffuse mesangial deposition of IgG when compared to control rats (83%) who showed only focal deposition. These results indicate that morphine enhances deposition of immune complexes in the mesangium. Morphine-induced matrix but may also change its quality. This may play a pathogenic role in the development of glomerular lesions in patients who abuse opiates.

Ultrastructural and histochemical mesangial alterations in Callitrichid IgM nephropathy (primates: platyrrhina)

The ultrastructural and histochemical alterations during different stages of spontaneously occurring IgM nephropathy in Callitrichidae were determined. Callitrichid IgM nephropathy was classified according to the light microscopic sequence of the mesangial lesions in the individual glomeruli. In minimal disease and axial proliferation mesangial cells and mesangial matrix were symmetrically increased, whereas in panmesangial disease matrix deposition exceeded the cellular responses. However, ultrastructural matrix changes such as deposition of electron-dense particles, dilatation of the matrix channel system, and slightly increased collagen fiber expression were present also in minimal disease and axial proliferation. Histochemically collagen I and III phenotypes could only be verified in glomerular sclerosis, at that time accompanied by diminution of collagen IV. The mesangial cellular lesions, in contrast, were very limited. The numerical increase in mesangial cells was associated with increased bleb formation and increased heterolysosome contents, whereas the amount of microfilaments was never increased.