Glomerular Immune Complex Research Articles

All-trans-retinoic acid aggravates cryoglobulin-associated membranoproliferative glomerulonephritis in mice

Transgenic (tg) mice overexpressing thymic stromal lymphopoietin (TSLP) develop mixed cryoglobulinaemia with renal disease closely resembling human cryoglobulinaemic membranoproliferative glomerulonephritis (MPGN), as well as systemic inflammation involving lung, liver and skin as a result of cryoglobulin deposits. We assessed the effect of all-trans-retinoic acid (ATRA), a powerful anti-inflammatory agent, on this model of cryoglobulinaemic MPGN. Groups of male TSLP tg mice and wild-type controls were treated with either ATRA (20 mg/kg) or vehicle 3 times weekly by intraperitoneal injection for 4 or 8 weeks, when mice were then sacrificed. Routine histology and immunohistochemistry for collagen IV, alpha-smooth muscle actin, Mac-2 and Ki67 were performed. Immunoglobulin levels were measured by enzyme-linked immunosorbent assay. ATRA unexpectedly exacerbated renal injury in TSLP tg mice with increased glomerular extracellular matrix, mesangial cell activation, glomerular cell proliferation, glomerular macrophage influx and immune complex deposition. Systemic injuries involving liver and lung, and the amount of circulating cryoglobulins were all worsened by ATRA treatment. Furthermore, ATRA resulted in increased IgG1 and IgM levels, the main components of the cryoglobulins in TSLP tg mice, and a manifestation of an enhanced Th2 immune response. ATRA is not protective but instead aggravates cryoglobulinaemic MPGN and its systemic manifestations in TSLP tg mice. We speculate these findings may be due to augmented production of pathogenic immunoglobulins and/or an enhanced systemic Th2 response. Although disappointing, our results also suggest caution in the application of retinoid therapy to human disease based on the largely positive animal data reported to date.

Treatment of lupus-prone NZB/NZW F1 mice with recombinant soluble Fcγ receptor II (CD32)

Objectives:Systemic lupus erythematosus (SLE) is a classical autoimmune disorder characterised by the production of IgG autoantibodies against double-stranded DNA (dsDNA). Activation of FcγR-bearing effector cells by immune complexes (ICs) is...

Production of M2000 (β- d-mannuronic acid) and its therapeutic effect on experimental nephritis

The present research introduces the method of Production of M2000 (β- d-mannuronic acid) and its therapeutic effect on experimental model of nephritis. M2000 was produced using enzymatic and chemical procedure on prepared alginate from Pseudomonas fluorescens. The experimental glomerulonephritis was induced in rats by a subcutaneous immunization and daily intravenous administration of bovine serum albumin (BSA). M2000 solution (30 mg/kg) was administered intraperitoneally at regular 48-h intervals for 4 weeks. Onset of treatment was day 56. Urinary protein was measured weekly and serum anti-BSA antibody was assessed by ELISA method at different intervals. Animals were killed on day 84 and blood samples and kidney specimens were obtained. Serum (creatinine, BUN, cholesterol, and triglyceride) and urine (protein, urea, and creatinine) determinants were measured at the time of sacrifice. Kidney specimens were processed for light and immunofluorescent microscopic examination. The fibrosarcoma cell line was used for assaying tolerability and matrix metalloproteinase type 2 (MMP-2) activity. MMP-2 activity was assessed using zymography. Our data showed that M2000 therapy could significantly reduce the urinary protein excretion in treated rats versus non-treated controls. Anti-BSA antibody titer was lower in treated rats than in controls at the 12th experimental week. PMN infiltration and glomerular immune complex deposition was less intense in treated rats than in controls. Cytotoxicity analysis of M2000 showed a much higher tolerability compared with other tested drugs (diclofenac, piroxicam and dexamethasone). The inhibitory effect of M2000 in MMP-2 activity was significantly greater than that of dexsamethasone and of piroxicam at a concentration of 200 μg/ml. Moreover, the toxicological study revealed that M2000 had no influence on serum (BUN, creatinine, triglyceride and cholesterol) determinants, urinary protein excretion and glomerular histology in healthy group receiving drug. Conclusions: In this research, for the first time we introduced the procedure of production of M2000 (β- d-mannuronic acid) and our data suggest that treatment with M2000, as a novel anti-inflammatory drug can reduce proteinuria, diminish antibody production and suppress the progression of disease in experimental model of glomerulonephritis.

Therapeutic Approach by a Novel Designed Anti-Inflammatory Drug, M2000, in Experimental Immune Complex Glomerulonephritis

The therapeutic efficacy of novel designed nonsteroidal anti-inflammatory drug, M2000 (ß- D- mannuronic acid) on experimental immune complex glomerulonephritis was evaluated. Bovine serum albumin (BSA) nephritis was induced in rats by a subcutaneous immunization and daily intravenous administration of BSA. M2000 solution (30 mg/kg) was administered intraperitoneally at regular 48-hr intervals for 4 weeks. Onset of treatment was day 56. Urinary protein was measured weekly and serum anti-BSA antibody was assessed by ELISA method at different intervals. Animals were killed on day 84 and blood samples and kidney specimens were obtained. Serum (creatinine, blood urea nitrogen, cholesterol, and triglyceride) and urine (protein, urea, and creatinine) determinants were measured at the time of sacrifice. Kidney specimens were processed for light and immunofluorescent microscopic examination. The fibrosarcoma cell line was used for assaying tolerability and matrix metalloproteinase type 2 (MMP-2) activity. MMP-2 activity was assessed using zymography. Our data showed that M2000 therapy could significantly reduce the urinary protein excretion in treated rats versus non-treated controls. Anti-BSA antibody titer was lower in treated rats than in controls at the 12th experimental week. Polymorphonuclear neutrophil leukocytes infiltration and glomerular immune complex deposition were less intense in treated rats than in controls. Cytotoxicity analysis of M2000 showed a much higher tolerability compared with other tested drugs (diclofenac, piroxicam and dexamethasone). The inhibitory effect of M2000 in MMP-2 activity was significantly greater than that of dexsamethasone and of piroxicam at a concentration of 200 μg/ml. Moreover, the toxicological study revealed that M2000 had no influence on serum (BUN, creatinine, triglyceride and cholesterol) determinants, urinary protein excretion and glomerular histology in healthy group receiving drug.Conclusions: These findings suggest that treatment with M2000 can reduce proteinuria, diminish antibody production, and suppress the progression of disease in a rat model of immune complex glomerulonephritis.

Role for Nephritogenic T Cells in Lupus Glomerulonephritis: Progression to Renal Failure Is Accompanied by T Cell Activation and Expansion in Regional Lymph Nodes

Autoreactive T cells are critical in the initiation and maintenance of autoantibody responses that are a hallmark of systemic lupus erythematosus. However, the direct contribution of T cells in end-organ disease like lupus glomerulonephritis (GN) is poorly understood. In this study, we investigated the role of T cells in progression of lupus GN in NZM2328 mice, a murine model of spontaneous systemic lupus erythematosus. At 26 wk of age, NZM2328 female mice showed glomerular immune complex deposits and acute proliferative GN. This was associated with up-regulation of MHC class II and the detection of T cells and CD11c(+) dendritic cells in the glomeruli. The regional lymph nodes (LN) showed preferential activation of T cells and an oligoclonal T cell response with skewed expansion of certain Vbeta families. This suggests an Ag-driven response occurring in the regional LN of nephritic mice during acute GN. In contrast, male NZM2328 mice developed glomerular immune complexes and acute GN, but rarely progressed to fatal chronic GN. Significantly, male kidneys at 40 wk of age did not have detectable dendritic cells and T cells in the glomeruli. Thus, glomerular immune complex deposition initiates an immune response against renal Ags in the regional LN, leading to T cell recruitment into the kidney during acute proliferative GN. This T cell activation and infiltration are influenced by gender-dependent end-organ factors and may determine the progression of acute GN to chronic GN and renal failure.

Role of MHC-Linked Genes in Autoantigen Selection and Renal Disease in a Murine Model of Systemic Lupus Erythematosus

We previously described a renal protective effect of factor B deficiency in MRL/lpr mice. Factor B is in the MHC cluster; thus, the deficient mice were H2b, the haplotype on which the knockout was derived, whereas the wild-type littermates were H2k, the H2 of MRL/lpr mice. To determine which protective effects were due to H2 vs factor B deficiency, we derived H2b congenic MRL/lpr mice from the 129/Sv (H2b) strain. Autoantibody profiling using autoantigen microarrays revealed that serum anti-Smith and anti-small nuclear ribonucleoprotein complex autoantibodies, while present in the majority of H2k/k MRL/lpr mice, were absent in the H2b/b MRL/lpr mice. Surprisingly, 70% of MRL/lpr H2b/b mice were found to be serum IgG3 deficient (with few to no IgG3-producing B cells). In addition, H2b/b IgG3-deficient MRL/lpr mice had significantly less proteinuria, decreased glomerular immune complex deposition, and absence of glomerular subepithelial deposits compared with MRL/lpr mice of any H2 type with detectable serum IgG3. Despite these differences, total histopathologic renal scores and survival were similar among the groups. These results indicate that genes encoded within or closely linked to the MHC region regulate autoantigen selection and isotype switching to IgG3 but have minimal effect on end-organ damage or survival in MRL/lpr mice.

FcR-Bearing Myeloid Cells Are Responsible for Triggering Murine Lupus Nephritis

Lupus glomerulonephritis is initiated by deposition of IgG-containing immune complexes in renal glomeruli. FcR engagement by immune complexes (IC) is crucial to disease development as uncoupling this pathway in FcRgamma(-/-) abrogates inflammatory responses in (NZB x NZW)F1 mice. To define the roles of FcR-bearing hemopoietic cells and of kidney resident mesangial cells in pathogenesis, (NZB x NZW)F1 bone marrow chimeras were generated. Nephritis developed in (NZB x NZW)F1 mice expressing activating FcRs in hemopoietic cells. Conversely, recipients of FcRgamma(-/-) bone marrow were protected from disease development despite persistent expression of FcRgamma in mesangial cell populations. Thus, activating FcRs on circulating hemopoietic cells, rather than on mesangial cells, are required for IC-mediated pathogenesis in (NZB x NZW)F1. Transgenic FcRgamma(-/-) mice expressing FcRgamma limited to the CD11b+ monocyte/macrophage compartment developed glomerulonephritis in the anti-glomerular basement disease model, whereas nontransgenic FcRgamma(-/-) mice were completely protected. Thus, direct activation of circulating FcR-bearing myeloid cells, including monocytes/macrophages, by glomerular IC deposits is sufficient to initiate inflammatory responses.

Effect of Palifermin in a Murine Model of Graft-Versus-Host Disease (GVHD) Associated with Th2 Cytokine Production, Autoantibody Production, and Glomerulonephritis

Palifermin (recombinant human keratinocyte growth factor) prevents the development of acute, lethal graft-versus-host disease (GVHD). It does so, at least in part, by protecting cells from injury. Another property of Palifermin is immune regulation. How the latter influences the evolution of GVHD remains uncertain. We explored the effect of Palifermin on GVHD in the DBA/2 --> ((DBA/2)x(C57BL/6))F(1)-hybrid strain combination, a model associated with autoantibody production and glomerulonephritis. Untreated recipients survived until at least day 150 post-induction. Palifermin-treated recipients succumbed between days 50 and 90 with levels of proteinuria of up to 20 g/L, ascites, and rapidly progressive, crescentic glomerulonephritis that was most severe in mice with the greatest levels of proteinuria. Kidney sections from both Palifermin-treated and untreated recipients showed the presence of granular deposits of IgG, IgM, IgA, and C3 in the mesangium and the glomerular basement membrane. Electron microscopy confirmed the extensive glomerular immune complex deposition. Antinuclear and anti-dsDNA antibodies were present in sera from both treated and untreated recipients; however, those in the latter were only detectable if the serum was kept at 37 degrees C, indicating that they were cryoglobulins. IL-4 was detectable only in cultures from Palifermin-treated recipients and the levels of IL-5 and IL-13 were significantly higher in the Palifermin-treated group than in untreated GVHD mice. IFN-gamma was only detectable in untreated GVHD mice. These data suggest that although Palifermin can protect mice with acute GVHD, it exacerbates GVHD in a model associated with autoantibody production and a preponderance of Th2 cytokines.

The Effect of Xenobiotic Exposure on Spontaneous Autoimmunity in (SWR × SJL)F1 Hybrid Mice

F1 hybrids of SWR (H-2 q ) and SJL (H-2 s ) mice spontaneously develop a lupuslike condition in an age-dependent manner, and these two H-2 haplotypes also confer susceptibility to induction of systemic autoimmunity by heavy metals such as mercury, silver, and gold with anti-fibrillarin antibodies (AFA) as marker. The aim of this study was to determine how the mixing of two susceptible genomes might influence expression of idiopathic and induced autoimmunity over a period of 14 mo of exposure to mercury and silver. Spontaneous autoimmunity first appeared as antinuclear antibodies (ANA) in females at 10 wk of age and in males at 10 mo of age, and was followed by development of anti-chromatin antibodies. Antibodies to double-stranded DNA developed in 60% of males and 20% of females. Thirty percent of males and 10% of females developed a coarsely speckled ANA pattern associated with high titers of anti-Sm antibodies. Glomerular immune complex (IC) deposits and a proliferative glomerulonephritis were seen at 17 mo of age. The F1 hybrids treated with metals showed no exaggeration of spontaneous autoimmunity. However, the metals suppressed the spontaneous development of anti-Sm and antichromatin antibodies. The metal-induced AFA, linked to the H-2 s and H-2 q haplotype, reached a maximum after 3–4 mo of treatment and then declined; 33% of the silver-treated hybrids finally became AFA-negative, despite continuous treatment. The decline in ANoA during metal treatment is contrary to the situation in metal-treated SJL mice. This indicates that dominant SWR background genes suppressed induction of certain autoimmune traits in the (SWR × SJL)F1 hybrid mice. This work was supported by a grant from the Swedish Research Council, Branch of Medicine (project 9453), to P.Hultman, and by NIH grants ES09802, ES08080, ES08666, and ES07511. We thank Robert L. Rubin, The Scripps Research Institute, for supplying chromatin preparations, and Elham Nikookhesal for technical assistance. Yngve Åberg, PhD, provided statistical assistance.

Amelioration of murine lupus by a peptide, based on the complementarity determining region-1 of an autoantibody as compared to dexamethasone: Different effects on cytokines and apoptosis

A peptide (hCDR1) based on the sequence of the complementarity-determining region-1 of an anti-DNA autoantibody ameliorates clinical manifestations of lupus. We analyzed the beneficial effects of hCDR1 when given alone or in combination with dexamethasone, while comparing the mechanisms of action of the latter. Treatment with either hCDR1 or dexamethasone, or a combination of the latter significantly reduced titers of dsDNA-specific autoantibodies, levels of proteinuria, and intensity of glomerular immune complex deposits. Both drugs down-regulated the secretion and expression of IFN-γ and IL-10, but only treatment with hCDR1 up-regulated TGF-β. While both drugs reduced the expression of Fas ligand (FasL) and caspase 8, treatment with hCDR1 resulted in reduced whereas dexamethasone administration resulted in increased rate of apoptosis. Furthermore, down-regulation of FasL appeared to play a role in cytokine modulation. We conclude that specific treatment with hCDR1 ameliorates murine lupus via distinct mechanisms of action than those of dexamethasone.

Accumulation of Immune Complexes in Glomerular Disease Is Independent of Locally Synthesized C3

Although complement activation can make immune complex glomerulonephritis worse, the third complement component also can solubilize immune complexes and thus reduce the severity of disease. How C3 that is produced within the kidney contributes to this balance is unknown. This study therefore investigated the relative roles of systemic and local C3 production in a model of glomerular immune complex disease. Injection of sheep anti-glomerular basement membrane antibody into preimmunized mice resulted in accumulation of immune complexes and progressive loss of function over 14 d that was much more marked in C3-deficient (C3-/-) mice. In C3-sufficient mice that received a transplant of a C3-/- mouse kidney and in C3-/- mice with C3-sufficient mouse kidney transplants, the severity and the pattern of injury went with the complement status of the recipient. That is, mice with deficient circulating C3 developed severe glomerular immune complex disease, whereas those with a high level of circulating C3 had well-preserved glomerular structure and function. It is concluded that circulating C3 is a critical factor in reducing the glomerular accumulation of immune complexes. Local synthesis of C3 did not have a major influence on this aspect of glomerular disease.

Alteration of the spontaneous systemic autoimmune disease in (NZB × NZW)F1 mice by treatment with thimerosal (ethyl mercury)

Inorganic mercury may aggravate murine systemic autoimmune diseases which are either spontaneous (genetically determined) or induced by non-genetic mechanisms. Organic mercury species, the dominating form of mercury exposure in the human population, have not been examined in this respect. Therefore, ethyl mercury in the form of thimerosal, a preservative recently debated as a possible health hazard when present in vaccines, was administered in a dose of 0.156-5 mg/L drinking water to female (NZB x NZW)F1 (ZBWF1) mice. These mice develop an age-dependent spontaneous systemic autoimmune disease with high mortality primarily due to immune-complex (IC) glomerulonephritis. Five mg thimerosal/L drinking water (295 microg Hg/kg body weight (bw)/day) for 7 weeks induced glomerular, mesangial and systemic vessel wall IC deposits and antinuclear antibodies (ANA) which were not present in the untreated controls. After 22-25 weeks, the higher doses of thimerosal had shifted the localization of the spontaneously developing renal glomerular IC deposits from the capillary wall position seen in controls to the mesangium. The altered localization was associated with less severe histological kidney damage, less proteinuria, and reduced mortality. The effect was dose-dependent, lower doses having no effect compared with the untreated controls. A different effect of thimerosal treatment was induction of renal and splenic vessel walls IC deposits. Renal vessel wall deposits occurred at a dose of 0.313-5 mg thimerosal/L (18-295 microg Hg/kg bw/day), while splenic vessel wall deposits developed also in mice given the lowest dose of thimerosal, 0.156 mg/L (9 microg Hg/kg bw/day). The latter dose is 3- and 15-fold lower than the dose of Hg required to induce vessel wall IC deposits in genetically susceptible H-2s mice by HgCl2 and thimerosal, respectively. Further studies on the exact conditions needed for induction of systemic IC deposits by low-dose organic mercurials in autoimmune-prone individuals, as well as the potential effect of these deposits on the vessel walls, are warranted.

Inhibition of (S)-armepavine from Nelumbo nucifera on autoimmune disease of MRL/MpJ- lpr/lpr mice

T cell immune responses play important roles in the pathogenesis of systemic lupus erythematosus (SLE). (S)-Armepavine (C 19H 23O 3N; MW313) from Nelumbo nucifera suppresses T cells proliferation. To study its potential benefit on SLE, we examined effects of (S)-armepavine on MRL/MpJ- lpr/lpr mice, which have similar disease features to human SLE. MRL/MpJ- lpr/lpr mice were treated orally with (S)-armepavine for 6 weeks and their SLE characteristics were evaluated. The results revealed that (S)-armepavine prevented lymphadenopathy and elongated life span of MRL/MpJ- lpr/lpr mice. It seemed to be mediated by inhibition of splenocytes proliferation, suppression of interleukin-2 (IL-2), interleukin-4, interleukin-10, and interferon-γ (IFN-γ) gene expressions, reduction of glomerular hypercellularity and immune complexes deposition, and decrease of urinary protein and anti-double stranded DNA autoantibody production. Furthermore, the data demonstrated (S)-armepavine impaired IL-2 and IFN-γ transcripts in human peripheral blood mononuclear cells. We suggest that (S)-armepavine may be an immunomodulator for the management of autoimmune diseases like SLE.

Concurrent Antiglomerular Basement Membrane Disease and Immune Complex Glomerulonephritis

Antiglomerular basement membrane (GBM) disease is characteristically described with linear deposition of IgG along GBM. However, the concurrent glomerular immune complex deposition was not rare and might be contributed to the development of anti-GBM disease. In the current series, glomerular immune complexes were identified in 10 of 47 patients who presented with renal-biopsy-proven anti-GBM disease. Six of the 10 patients complicated with a well-documented glomerulonephritis, including two patients with membranous nephropathy, one patient with IgA nephropathy, one patient with membranoproliferative glomerulonephritis, one patient with Schonlein–Henoch nephritis, and one patient with hepatitis B virus associated membranous nephritis. The other four patients had immune complexes with IgG or IgM predominance deposited in glomerular mesangium without a well-documented glomerulonephritis. Clinical and pathological data of patients with immune complex deposition (n = 10) were compared with those of patients with anti-GBM disease alone (n = 37). There was no significant difference in age, gender, clinical and pathological manifestations, and renal outcome between the two groups. In general, the association of glomerular immune complexes did not lead to a benign prognosis. Plasma exchange and extensive immunosuppressive therapy should be carried out as soon as possible. The immune complexes deposited in glomeruli might participate in the initiation of anti-GBM disease.

Prevention and reversal of nephritis in MRL/lpr mice with a single injection of C‐reactive protein

C-reactive protein (CRP) is an acute-phase serum protein with binding reactivity to nuclear autoantigens and immunomodulatory function. The MRL/lpr mouse is an important model of human systemic lupus erythematosus (SLE). These mice develop high-titer anti-DNA antibodies and immune complex-mediated nephritis and exhibit progressive lymphadenopathy. The mortality rate among these mice is 50% by age 18-20 weeks; the most frequent cause of death is glomerulonephritis. The present study was undertaken to determine whether treatment of mice with CRP would affect the course of lupus nephritis. MRL/lpr mice were treated with a single 200-mug injection of CRP at either age 6 weeks (before disease onset) or age 13 or 15 weeks (when proteinuria had reached high levels). Proteinuria was measured weekly, and levels of anti-double-stranded DNA autoantibodies and blood urea nitrogen were determined monthly. Glomerular immune complex deposition and renal pathology were assessed in mice ages 15 weeks and 17 weeks. Early CRP treatment markedly delayed the onset of proteinuria and lymphadenopathy, increased survival, and reduced levels of autoantibodies to DNA. Treatment of mice with active disease reversed proteinuria and prolonged survival. Renal disease was decreased in CRP-treated mice, with a marked suppression of glomerular pathology, tubular degeneration, and interstitial inflammation, which correlated with the decrease in proteinuria and azotemia. These findings demonstrate that systemic suppression of autoimmunity is initiated by a single injection of CRP. Long-term maintenance of CRP-mediated protection was reversed by injection of an anti-CD25 monoclonal antibody but not by macrophage depletion, suggesting that disease suppression is maintained by CD25-bearing T cells.

Nephrotic syndrome in African children: lack of evidence for ‘tropical nephrotic syndrome’?

Infections such as malaria, schistosomiasis, hepatitis B and HIV have been suggested as major causes of the nephrotic syndrome (NS) in African children. We retrospectively analysed the course of the NS in 32 children from Ghana and reviewed the literature on NS from 18 different African countries for the presence of 'the tropical nephrotic syndrome'. Thirty-two children (22 boys, 10 girls, median age 12 years, range 1-18 years) with NS were treated from 2000-2003 at Battor Hospital, Ghana. Thirteen out of 32 children underwent a renal biopsy which was investigated by light, immune and electron microscopy. All 32 patients were initially treated with oral prednisone (PRED) therapy (29 with standard therapy for 8 weeks and three individually tailored), and steroid-resistant children received also intravenous methylprednisolone pulses (three children) or oral cyclophosphamide (two children). All patients fulfilled the clinical and laboratory criteria of a NS. The initial median serum creatinine was 65 micromol/l (range 44-133 micromol/l). Renal biopsy was performed in 13/32 children and revealed focal and segmental glomerulosclerosis (FSGS) in 10 patients, minimal change disease (MCNs) in two and no conclusive result in one patient. Glomerular immune complex deposition was absent in all biopsies. After treatment with PRED, oedema disappeared in 24/32 patients; however, proteinuria normalized in 16/32 patients only. The NS relapsed in 9/16 steroid-sensitive patients after cessation of PRED therapy, and two children were frequent relapsers. The steroid-resistant NS did not respond to an intensified immunosuppression in 5/16 children receiving methylprednisolone or cyclophosphamide. Five out of 32 children died, all were steroid resistant. There was no evidence for a dominating role of steroid-resistant 'tropical glomerulopathies' in children with a NS in Ghana. Similar to South Africa, focal and segmental glomerulosclerosis (FSGS) and minimal change disease were the most frequent findings on histology. Contrary to Nigeria, membrano-proliferative glomerulonephritis was not found in these patients. We conclude from this data and from the literature that the histological pattern of NS may vary between different African countries. Concerning therapy of NS under tropical conditions, we emphasize that despite the limited therapeutic facilities half of these patients may benefit from corticosteroids; however, steroid resistance and FSGS resulted in a high mortality.

Experimental glomerulonephritis induced by hydrocarbon exposure: a systematic review.

BackgroundMuch epidemiological evidence suggests that hydrocarbon exposure may induce glomerulonephritis and worsen its course in many patients. The mechanisms are unknown, however, no specific microscopic pattern has been identified, and it has also been argued that hydrocarbon exposure causes tubular damage mainly. Studying experimental animals may best answer these questions, and as no systematic review of glomerulonephritis produced experimentally by hydrocarbon exposure has been performed previously, I found it relevant to search for and analyse such studies.MethodsAnimal experiments having mimicked human glomerulonephritis by hydrocarbon exposure were sought on Medline and ToxnetResultsTwenty-six experiments using thirteen different hydrocarbons were identified. Several human subtypes were observed including IgA nephritis, mesangial, proliferative and extracapillary glomerulonephritis, focal and focal-segmental sclerosis, minimal change nephropathy, anti-GBM and anti-TBM nephritis, and glomerulonephritis associated with peiarteritis nodosa. Glomerular proteinuria was seen in 10/12 experiments that included urine analyses, and renal failure in 5/8 experiments that included measurements of glomerular function. All experiments resulted in various degrees of tubular damage as well. In most studies, where the animals were examined at different times during or after the exposure, the renal microscopic and functional changes were seen immediately, whereas deposits of complement and immunoglobulins appeared late in the course, if at all.ConclusionThese experiments are in accord with epidemiological evidence that hydrocarbon exposure may cause glomerulonephritis and worsen renal function. Probable mechanisms include an induction of autologous antibodies and a disturbance of normal immunological functions. Also, tubular damage may increase postglomerular resistance, resulting in a glomerular deposition of macromolecules. In most models a causal role of glomerular immune complex formation was unlikely, but may rather have been a secondary phenomenon. As most glomerulonephritis subgroups were seen and as some of the hydrocarbons produced more than one subgroup, the microscopic findings in a patient cannot be used as a clue to the causation of his disease. By the same reason, the lack of a specific histological pattern in patients with glomerulonephritis assumed to have been caused by hydrocarbon exposure is not contradictive.

Toll-Like Receptor-7 Modulates Immune Complex Glomerulonephritis

Viral infections may trigger immune complex glomerulonephritis via Toll-like receptors (TLR), as certain TLR trigger immunity upon recognition of viral nucleic acids. On the basis of previous findings regarding viral double-stranded RNA and TLR3 in experimental lupus erythematosus, a similar role for TLR7 that recognizes viral single-stranded RNA was hypothesized. Immunostaining of kidney sections of nephritic MRLlpr/lpr mice revealed TLR7 expression in infiltrating ER-HR3-positive macrophages and few CD11c-positive dendritic cells but not in glomerular mesangial cells as observed for TLR3. This finding was consistent with the distribution pattern of intravenously injected single-stranded RNA in nephritic MRLlpr/lpr mice. TLR7 ligation activated monocytes and dendritic cells, both isolated from MRLlpr/lpr mice, to secrete IFN-alpha, IL-12p70, IL-6, and CCL2. In vivo, a single injection of the TLR7 ligand imiquimod increased serum levels of IL-12p70, IFN-alpha, and IL-6. A course of 25 microg of imiquimod given every other day from week 16 to 18 of age aggravated lupus nephritis in MRLlpr/lpr mice. This was associated with increased glomerular immune complex deposits as well as interstitial expression of CCL2 in imiquimod-treated MRLlpr/lpr mice. Different types of viral nucleic acids seem to modulate systemic autoimmunity through specific interactions with their respective TLR. Different TLR expression profiles on immune cell subsets and nonimmune parenchymal cell types determine the molecular mechanisms involved in viral infection-associated exacerbation of lupus nephritis and possibly other types of immune complex glomerulonephritis.

Inhibition of lupus disease by anti–double‐stranded DNA antibodies of the IgM isotype in the (NZB × NZW)F1 mouse

In systemic lupus erythematosus (SLE), immune complexes (ICs) containing pathogenic IgG anti-double-stranded DNA (anti-dsDNA) autoantibodies are deposited in renal capillaries and initiate glomerulonephritis (GN) by the activation of complement and effector cells. In contrast, it has been demonstrated that the presence of IgM anti-dsDNA antibodies correlates negatively with the development of GN in SLE. The aim of this study was to determine whether anti-dsDNA antibodies of the IgM isotype protect against IC-mediated organ damage in SLE. Lupus-prone (NZB x NZW)F(1) mice (females) were treated with murine monoclonal IgM anti-dsDNA antibodies. Treatment was delivered by subcutaneous injection at a dosage of 100 mug/week starting at 16 weeks of age (prophylactic) or at 24 weeks of age (therapeutic). Mice treated with IgM anti-dsDNA exhibited a delayed onset of proteinuria and a reduced degree of renal pathology, which resulted in significantly improved survival as compared with control mice. Serum concentrations of IgG anti-dsDNA antibodies were not significantly modified. However, glomerular deposition of ICs was markedly reduced in both treatment protocol groups. In contrast, higher amounts of IgG and IgM and increased expression of Fcgamma receptor were demonstrated in liver sections from the treated mice compared with the untreated mice, suggesting an enhanced clearance of soluble ICs from phagocytic cells of the reticuloendothelial system. These data demonstrate the efficacy of IgM anti-dsDNA treatment in inhibiting the pathologic changes of lupus in (NZB x NZW)F(1) mice. Lower glomerular IC deposition is associated with a reduced inflammatory response and impaired organ damage. The reduced frequency of GN in SLE patients who have IgM anti-dsDNA antibodies may therefore reflect a disease-modifying effect of this class of autoantibodies that has potential therapeutic implications. Our findings should encourage the development of new therapeutic modalities using IgM anti-dsDNA antibodies in humans with SLE.

Immune Complex Deposition in Adult Male Sprague–Dawley Rats Chronically Immunized with GnRH

This study was undertaken to evaluate whether the anti-GnRH antibodies and immune complexes (IC) generated by immunization with GnRH-TT cause cellular damage within the animal. Chronic immunization of rats with GnRH-TT injected i.m. was followed by tissue/organ analysis for immune complex deposition by immunofluorescence microscopy. Two groups were studied: (1) those immunized throughout the experiment until their ultimate demise, and (2) those given a chance to recover from the effects of chronic immunization before final analysis. GnRH-TT was effective in stopping spermatogenesis, which resumed after withdrawal of the immunogen. Most tissues from chronically immunized animals were not significantly different than controls, however the kidneys of treated animals exhibited a higher accumulation of IC. Despite increased IC deposition, pathologic effects were not detected at the cellular level. GnRH-TT is an effective immunocontraceptive although the accumulation of glomerular IC represents a potential deleterious side effect.