heparitin-sulfate and Lupus-Nephritis

The glomerular basement membrane (GBM) is an essential component of the glomerular filtration barrier. Heparan sulfate proteoglycans such as agrin are major components of the GBM, along with α345(IV) collagen, laminin-521 and nidogen. A loss of GBM heparan sulfate chains is associated with proteinuria in several glomerular diseases and may contribute to the underlying pathology. As the major determinants of the anionic charge of the GBM, heparan sulfate chains have been thought to impart charge selectivity to the glomerular filtration, a view challenged by the negligible albuminuria in mice that lack heparan sulfate in the GBM. Recent studies provide increasing evidence that heparan sulfate chains modulate local complement activation by recruiting complement regulatory protein factor H, the major inhibitor of the alternative pathway in plasma. Factor H selectively inactivates C3b bound to surfaces bearing host-specific polyanions such as heparan sulfate, thus limiting complement activation on self surfaces such as the GBM, which are not protected by cell-bound complement regulators. We discuss mechanisms whereby the acquired loss of GBM heparan sulfate can impair the local regulation of the alternative pathway, exacerbating complement activation and glomerular injury in immune-mediated kidney diseases such as membranous nephropathy and lupus nephritis.

Topics: Agrin; Animals; Collagen Type IV; Complement Activation; Complement C3b; Complement Factor H; Gene Expression Regulation; Glomerular Basement Membrane; Glomerulonephritis, Membranous; Heparitin Sulfate; Humans; Laminin; Lupus Nephritis; Membrane Glycoproteins; Signal Transduction; Static Electricity

The cardinal feature of systemic lupus erythematosus is the formation of anti-nuclear antibodies. In recent years, it has become clear that the nucleosome is a major autoantigen that drives this T cell-dependent autoimmune response, as exemplified by the presence of nucleosome-specific T helper cells and the high prevalence of nucleosome-specific autoantibodies. The only way to generate nucleosomes in vivo is by the process of apoptosis. There is growing evidence that in systemic lupus erythematosus apoptosis is disturbed, leading to the release of nucleosomes. Moreover, apoptosis-induced modifications of these autoantigens may render them more immunogenic, especially if the removal of apoptotic cells is insufficient. The first indications for the impaired clearance of apoptotic cells in systemic lupus erythematosus are emerging. Nucleosomes are also important for mediating tissue lesions, especially glomerulonephritis. In lupus nephritis nucleosomes, nucleosome-specific antibodies and nucleosome/IgG complexes have been identified in the glomerular immune deposits. Via their cationic histone part nucleosomes mediate the binding of anti-nuclear antibodies to intrinsic constituents of the glomerular basement membrane, such as the anionic heparan sulfate and collagen IV. Appreciation of this binding mechanism may lead to new treatment strategies, as shown for non-coagulant heparinoids.

Topics: Animals; Antibodies, Antinuclear; Apoptosis; Autoantibodies; Collagen; Cross Reactions; Heparitin Sulfate; Humans; Kidney Glomerulus; Lupus Erythematosus, Systemic; Lupus Nephritis; Lymphocyte Activation; Nucleosomes; T-Lymphocytes, Helper-Inducer

It has been suggested that crossreactivity of anti-DNA antibodies plays a central role in the development of lupus nephritis. Experiments with monoclonal anti-DNA antibodies initially seemed to sustain this intriguing hypothesis but such studies may easily lead to incorrect conclusions. In this short article, Kees Brinkman and colleagues discuss the validity of these studies and challenge the role of crossreactivity in the pathogenesis of lupus nephritis.

Topics: Antibodies, Antinuclear; Antibodies, Monoclonal; Antibody Affinity; Antigen-Antibody Complex; Basement Membrane; Cross Reactions; Heparitin Sulfate; Histones; Humans; Immune Complex Diseases; Lupus Nephritis

Antibodies against heparan sulfate (HS) were detected in sera from patients with active systemic lupus erythematosus (SLE) and in sera from MRL/l mice with a spontaneous SLE-like disease. By inhibition studies it was shown that this reactivity towards HS was due to cross-reactivity of anti-DNA antibodies. Immunoglobulin eluted from human and mouse kidneys with diffuse proliferative SLE glomerulonephritis also bound to HS. This crossreaction of anti-DNA antibodies was further substantiated by the finding that 17 out of 42 anti-DNA monoclonal antibodies (mAb) also bound to HS, 11 out of 17 HS positive mAb bound to heparan sulfate proteoglycan (HSPG) purified from human glomerular basement membranes (GBM) and 7 out of 42 bound directly to isolated human GBM-loops. The binding to HS, HSPG, and GBM could be inhibited in a dose-dependent manner by DNA. In a retrospective analysis of sera from 10 SLE patients, in which 6-16 serum samples per patient were studied, we found in all 5 episodes of onset or exacerbation of a SLE nephritis an anti-HS activity in the serum, prior to onset of the nephritis. In 4 episodes of onset or exacerbation of non-renal manifestations, anti-HS activity was only found in the serum during one episode. Based on these studies we postulate that binding of anti-DNA antibodies to HS within the GBM may be an important immunopathological event in the development of SLE nephritis.

Topics: Animals; Antibodies, Monoclonal; Basement Membrane; DNA; Glycosaminoglycans; Heparitin Sulfate; Humans; Kidney Glomerulus; Lupus Erythematosus, Systemic; Lupus Nephritis

Background The purpose of this study was to evaluate the features of heparan sulfate proteoglycans (HSPGs) as agrins of the glomerular basement membrane (GBM) and circulating anti-heparan sulfate (HS) antibodies in lupus nephritis, comparing titers among the following groups: lupus nephritis (LN), non-renal lupus, non-lupus nephritis, and healthy controls. Methods The stage of nephritis was determined based on the kidney biopsy. Alcian blue staining and immunohistochemical (IHC) staining for agrin were performed for histological evaluation of GBM HSPGs in normal glomeruli, non-lupus membranous glomerulonephritis (MGN), and lupus MGN. The results were used for measurement of the serum anti-HS antibody titers using an enzyme-linked immunosorbent assay (ELISA) in the following groups: 38 healthy controls, 38 non-lupus nephritis, 37 non-renal lupus, and 38 LN. Results Glomerulus HSPGs were stained bluish-green along the GBM with Alcian blue. However, IHC staining against agrin was almost completely negative in the lupus MGN group compared with the normal and non-lupus MGN groups, which showed brown staining of GBM. A higher level of anti-HS IgG was detected in LN compared with other groups, respectively. Higher titers were associated with the presence of SLE and nephritis. A higher degree of proteinuria normalized to glomerular filtration rate (eGFR) was observed in association with higher anti-HS antibody titers in LN. Conclusion This study demonstrated a functional loss of GBM HSPGs and higher levels of circulating anti-HS antibodies as a characteristic feature of lupus nephritis, suggesting their involvement in the pathogenesis of lupus nephritis and proteinuria.

Topics: Adult; Basement Membrane; Case-Control Studies; Enzyme-Linked Immunosorbent Assay; Female; Glomerular Filtration Rate; Glomerulonephritis, Membranous; Heparan Sulfate Proteoglycans; Heparitin Sulfate; Humans; Immunoglobulin G; Kidney Glomerulus; Lupus Erythematosus, Systemic; Lupus Nephritis; Male; Middle Aged; Nephritis; Proteinuria; Young Adult

Recently, we identified specific N- and 6-O-sulphated heparan sulphate (HS) domains on activated glomerular endothelial cells. In this study, we evaluated in lupus nephritis the expression of different HS domains on glomerular endothelium and in the glomerular basement membrane (GBM).. The expression of specific glomerular HS domains and the presence of immunoglobulins (Ig) were determined by immunofluorescence staining of kidney sections of patients with nephritis due to systemic lupus erythematosus (SLE) and MRL/lpr lupus mice. The expression/presence of glomerular HS domains and Ig was also evaluated after eluting Ig from renal sections of lupus mice using two elution methods, and in renal sections of lupus mice treated with heparinoids.. Both MRL/lpr mice and patients with lupus nephritis showed a decreased expression of HS in the GBM. The expression of N- and 6-O-sulphated HS domains on glomerular endothelium was decreased in MRL/lpr mice, but increased in SLE patients. MRL/lpr mice had more extensive glomerular Ig deposits than SLE patients. After elution of Ig, the glomerular endothelial expression of N- and 6-O-sulphated HS domains in MRL/lpr mice was recovered and even increased above normal levels, while the expression of HS in the GBM was restored to normal levels. Treatment with heparinoids prevented Ig deposition and preserved the expression of glomerular HS domains at normal levels in lupus mice.. The expression of specific HS domains on glomerular endothelium and in the GBM is changed during lupus nephritis due to masking by Ig deposits and induction of inflammatory N- and 6-O-sulphated HS domains.

Topics: Adult; Albuminuria; Animals; Basement Membrane; Endothelial Cells; Female; Fluorescent Antibody Technique; Heparin, Low-Molecular-Weight; Heparitin Sulfate; Humans; Immunoglobulins; Kidney Glomerulus; Lupus Erythematosus, Systemic; Lupus Nephritis; Male; Mice; Mice, Inbred MRL lpr; Staining and Labeling; Tissue Distribution

Urinary glycosaminoglycans (GAG) and heparan sulfate (HS) are considered to be markers of early renal involvement. This study was undertaken to demonstrate their excretion patterns in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) with and without arthritis. Serum creatinine and urinary GAG, HS, microalbumin, and creatinine measurements were made in 51 biopsy-proven lupus nephritis (LN) cases, 12 RA patients, and 21 healthy controls. Urinary GAG and HS levels were higher in the LN and RA groups than in controls. Heparan sulfate excretions and SLE disease activity index (SLEDAI) scores were no different between SLE patients with classes 1 and 2 (group A) and those with classes 3, 4, and 5 (group B) renal involvement. However, GAG and microalbumin excretions were significantly high in the latter. There were no differences in GAG and HS excretions between normoalbuminuric, microalbuminuric, and macroproteinuric SLE patients or between those with and without arthritis. In conclusion, urinary GAG and HS, being unrelated to the presence of arthritis, are independent markers of LN. Extrarenal causes or subclinical renal involvement may be responsible in RA due to their increased excretion in these patients.

Topics: Adolescent; Arthritis, Rheumatoid; Female; Glycosaminoglycans; Heparitin Sulfate; Humans; Lupus Erythematosus, Systemic; Lupus Nephritis; Male; Middle Aged

Renal involvement in systemic lupus erythematosus (SLE) affects the disease outcome. In order to advance the diagnosis and the initiation of therapy, non-invasive diagnostic techniques are required. In this study, urinary glycosaminoglycans (GAG) and heparan sulphate (HS) were measured in 26 patients with biopsy-proven lupus nephritis and compared to 16 healthy controls. Uronic acid as a representative of GAGs in urine was determined spectrophotometrically with the meta-hydroxydiphenyl, following acid treatment. HS was determined as hexosamine by the method of Smith and Gilkerson. The median values of GAG (3.99 mg/g crea./day) and HS (2.41 mg/g crea./day) in patients were significantly ( P = 0.001) higher than in the control group (1.98 and 0.87, respectively). There was a positive correlation between GAG and HS values ( P = 0.000, r = 0.924) in SLE patients. There were no differences in HS excretion, microalbuminuria and SLE-DAI scores between different classes of lupus nephritis. However, GAG values in class 3 nephritis were significantly ( P = 0.033) higher than from both class 2 and class 4 lupus nephritis. There were no differences in all the measured parameters between normoalbuminuric, microalbuminuric and macroproteinuric patients. Furthermore, there were no correlations between GAG, HS excretions and SLE-DAI scores or microalbuminuria. These results suggest that urinary GAG and HS may serve as useful, independent and non-invasive markers of lupus nephritis.

Topics: Adolescent; Adult; Disability Evaluation; Female; Glycosaminoglycans; Heparitin Sulfate; Hexosamines; Humans; Lupus Nephritis; Male; Middle Aged; Severity of Illness Index; Uronic Acids

To establish the correlation between lupus nephritis-associated autoantibody levels and the presence/activity of lupus nephritis and global disease activity using cross-sectional data in patients with systemic lupus erythematosus (SLE).. Disease activity was assessed using the British Isles Lupus Assessment Group (BILAG) index. Antibody levels against single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), histones, nucleosomes and heparan sulphate (HS) were analysed by ELISA in SLE patients with (n=11) and without (n=22) nephritis and in normal controls (n=21). Antibody subclasses were also analysed.. Higher levels of anti-dsDNA and anti-HS antibodies were found in patients with lupus nephritis, the level of anti-HS antibodies correlating with the BILAG renal score. Predominant subclasses were IgG1 and IgG3 for dsDNA antibodies, IgG2 for anti-nucleosome antibodies, and IgG2 and IgG3 for anti-HS antibodies.. Correlation was demonstrated between antibodies to dsDNA, ssDNA, histones, nucleosomes and HS. There is a strong correlation between the level of anti-HS antibodies and disease activity in patients with lupus nephritis as measured by BILAG.

Topics: Adult; Antibodies, Antinuclear; Cross-Sectional Studies; DNA; DNA, Single-Stranded; Enzyme-Linked Immunosorbent Assay; Female; Heparitin Sulfate; Histones; Humans; Immunoglobulin G; Lupus Erythematosus, Systemic; Lupus Nephritis; Male; Nucleosomes; Severity of Illness Index

Recently we showed that antinuclear autoantibodies complexed to nucleosomes can bind to heparan sulphate (HS) in the glomerular basement membrane (GBM) via the histone part of the nucleosome. Histones have been identified in glomerular deposits in human and murine lupus nephritis. In addition, a decreased HS staining in the GBM was found, most probably due to masking by deposition of antibodies complexed to nucleosomes.. In this study we first investigated whether histones or nucleosomes could be identified in glomerular deposits in human lupus nephritis, and secondly whether the presence of these nuclear components was correlated with absence of HS staining. Kidney biopsies of SLE patients (11 with diffuse proliferative glomerulonephritis (DPGN) and six with membranous glomerulonephritis (MGN)) and non-SLE glomerular diseases were stained for histones. DNA, nucleosomes, IgG and HS.. Using a polyclonal anti-H3 1 21 antiserum, histones were detected in all patients with DPGN and in two of six patients with SLE-MGN (P < 0.01). Using a monoclonal antihistone antibody, histones were stained in three patients with DPGN, but in none of the biopsies with MGN. Using nucleosome specific monoclonal antibodies, nucleosomes were detected in five patients with DPGN, in two patients with MGN, but in none of the biopsies with non-SLE glomerulonephritis. HS staining was nearly absent in DPGN, whereas staining was only moderately reduced in patients with MGN and controls (P = 0.001).. Using polyclonal and monoclonal antihistone antisera, histones were identified in all patients with DPGN and their presence was associated with a decrease of HS staining. Nucleosomes were identified in five of 11 patients with DPGN and in two of six patients with MGN. This is the first demonstration of nucleosomes in glomerular deposits in SLE nephritis.

Topics: Adolescent; Adult; Animals; Antibodies, Monoclonal; Antigen-Antibody Complex; DNA; Female; Fluorescent Antibody Technique, Indirect; Glomerulonephritis, Membranoproliferative; Glomerulonephritis, Membranous; Heparitin Sulfate; Histones; Humans; Immunoglobulin G; Kidney Glomerulus; Lupus Nephritis; Male; Mice; Middle Aged; Nucleosomes

Recently we found in biopsies of human lupus nephritis a nearly complete loss of heparan sulfate (HS) staining in the glomerular basement membrane (GMB). To clarify the relationship between HS staining and albuminuria in lupus nephritis, we studied MRL/lpr mice with short (< 7 days) or prolonged duration of albuminuria (14-21 days) and compared these with mice of different ages without albuminuria. Kidney sections were stained for mouse immunoglobulin (Ig), HS, heparan sulfate proteoglycan (HSPG)-core protein and laminin in immunofluorescence. In mice with prolonged albuminuria HS staining in the glomerular capillary loops had almost completely disappeared, whereas staining was unaltered in non-albuminuric mice (P = 0.001). In mice with short duration of albuminuria, there was a tendency toward a decrease of HS staining (P = 0.06). The expression of HSPG-core protein and other extra cellular matrix (ECM) components was unaltered in all groups. HS staining correlated inversely with albuminuria (rs = -0.55; P < 0.001) and with staining of Ig deposits in the capillary loops (rs = -0.74; P < 0.001). Despite the nearly complete loss of HS staining in the GBM in mice with prolonged albuminuria, there was no change in glomerular HS content as assessed by agarose electrophoresis and HS inhibition ELISA. We conclude that the development of albuminuria in MRL/lpr mice is accompanied by a loss of HS staining in the GBM, probably due to the masking of HS by deposits of Ig. In vitro studies revealed that autoantibodies complexed to nucleosomal antigens can inhibit the binding of the anti-HS monoclonal antibody to HS. Whether this also occurs in vivo remains to be determined.

Topics: Albuminuria; Animals; Basement Membrane; Enzyme-Linked Immunosorbent Assay; Fluorescent Antibody Technique; Heparitin Sulfate; Kidney; Kidney Glomerulus; Lupus Nephritis; Mice; Mice, Inbred Strains; Staining and Labeling

Heparan sulphate-reactive antibodies in lupus sera have been suggested to be anti-DNA-DNA/histone immune complexes and to be associated with lupus nephritis. In this study, 23 anti-DNA-positive lupus sera including 13 active nephritis sera were tested for the presence of circulating anti-DNA-DNA/histone immune complexes by solid phase heparan sulphate-ELISA. Because of high background binding to protamine chloride-linked heparan sulphate plates, poly-L-lysine (PLL) was used as a linker and the remaining active sites of PLL were blocked with poly-L-glutamic acid. The ELISA was capable of detecting small amounts of anti-DNA IgG-DNA/histone immune complexes formed in vitro. However, only three active nephritis sera of the 23 sera tested showed significant binding to heparan sulphate plates. This binding was found to be non-specific, the result of high background binding of IgG to PLL. Anti-heparan sulphate ELISA using positively charged linkers detects non-specific binding when lupus sera are tested. Specific assays need to be developed for DNA/histone-related immune complexes present in lupus sera.

Topics: Animals; Antigen-Antibody Complex; Autoantibodies; Binding Sites; Binding Sites, Antibody; Cattle; DNA; Enzyme-Linked Immunosorbent Assay; False Positive Reactions; Heparitin Sulfate; Histones; Lupus Erythematosus, Systemic; Lupus Nephritis; Polyglutamic Acid

The presence of anti-heparan sulphate (HS) reactivity in serum is closely related to the occurrence of nephritis in patients with systemic lupus erythematosus (SLE). Since patients with lupus nephritis in general also have high titres of anti-DNA antibodies, we wanted to clarify the relationship between anti-HS and anti-DNA reactivity in serum. Therefore, we studied longitudinally six patients with lupus nephritis who experienced 12 exacerbations of their disease, and five SLE patients without nephritis experiencing 10 periods of non-renal disease exacerbations. In addition, we tested single serum samples of another 24 patients obtained during a renal disease exacerbation and 22 sera of patients without nephritis. The sera of all patients were tested for anti-DNA (Farr assay) and anti-HS reactivity (ELISA). We confirmed that SLE patients during renal exacerbations have a significantly higher anti-HS reactivity than patients without nephritis (P < 0.003). In addition, patients with nephritis also had higher titres of anti-DNA antibodies during renal exacerbations than during non-renal exacerbations (P < 0.01). A correlation between anti-DNA and anti-HS reactivity was observed (r = 0.40, P < 0.02), which in itself explains the correlation between nephritis and anti-HS reactivity. Comparing sera from nephritis and non-nephritis patients matched for anti-DNA titre, we found no difference in anti-HS reactivity, and therefore must conclude that the anti-HS reactivity is a direct reflection of anti-DNA reactivity.

Topics: Antibodies, Antinuclear; DNA; Heparitin Sulfate; Humans; Longitudinal Studies; Lupus Nephritis

Autoantibodies reacting with a great variety of autoantigens are characteristic for the autoimmune disease systemic lupus erythematosus (SLE). Although reactivity with heparan sulfate (HS) in sera of patients with SLE is found in association with the occurrence of nephritis, the aetiological significance of this association is not clear. The assay which is generally used to measure anti-HS reactivity is subject to false-positive results, as a consequence of the binding of negatively charged moieties within immune complexes to the precoat employed (protamine sulfate). Therefore, we have developed a new ELISA in which photobiotinylated HS is efficiently and reproducibly bound to streptavidin-coated wells. We compared the new ELISA with the classical anti-HS ELISA by testing culture supernatants of 20 murine monoclonal antibodies (mAb) to DNA (containing free anti-DNA and anti-DNA/nucleosome immune complexes) and preparations of these mAb (containing only free anti-DNA), purified under dissociating conditions. In the classical anti-HS ELISA, 14 out of 20 of the culture supernatants reacted positively with HS; after purification no reactivity remained. The discrepancy must be due to anti-DNA/nucleosome immune complexes present in the culture supernatants. In the new ELISA only four out of 20 culture supernatants and one of the purified preparations reacted with HS. This latter reactivity is probably not specific, since this mAb also reacted with streptavidin alone. To find out whether there is a correlation between the occurrence of nephritis and anti-HS reactivity, measured in this new anti-HS ELISA, we tested sera of patients with a renal- or non-renal exacerbation of SLE in the newly developed anti-HS ELISA. We observed a correlation between anti-HS reactivity and nephritis.

Topics: Animals; Antibodies, Antinuclear; Antibodies, Monoclonal; Autoantibodies; Biotin; Cross Reactions; DNA; Enzyme-Linked Immunosorbent Assay; Heparitin Sulfate; Humans; Lupus Erythematosus, Systemic; Lupus Nephritis; Mice

Cross-reactive antibodies against heparan sulphate (HS) have been suggested to play a role in initiating renal disease in SLE. Recently, we found that HS-reactivity is mediated by anti-DNA antibodies complexed with DNA and histones. To evaluate the clinical significance of anti-HS reactivity, we studied prospectively a cohort of 72 consecutive SLE patients, of whom 22 experienced 40 exacerbations. In 20 of these exacerbations renal symptoms were present. In these 20 exacerbations significantly higher anti-DNA (median 1:160) and anti-HS (median 1:30) titres were detected compared with exacerbations without renal manifestations (median 1:60 for anti-DNA and negative for anti-HS). There were no correlations with other symptoms of SLE. Anti-HS titres showed a significant correlation with anti-DNA antibody titres (rs = 0.57, P < 0.05). Anti-HS without anti-DNA reactivity was never detected. Some SLE patients showed a high anti-DNA titre without anti-HS reactivity, suggesting that not all anti-DNA antibodies are able to bind to histone/DNA complexes and thus to exhibit anti-HS reactivity. Our findings indicate that anti-HS reactivity is correlated with renal disease in SLE.

Topics: Antibodies, Antinuclear; Cross Reactions; Enzyme-Linked Immunosorbent Assay; Female; Heparitin Sulfate; Humans; Incidence; Longitudinal Studies; Lupus Erythematosus, Systemic; Lupus Nephritis; Male; Prospective Studies

Extensive studies in murine models of lupus nephritis have shown that cationic anti-DNA autoantibodies have nephritogenic potential. We have investigated whether cationic anti-DNA antibodies of IgG class are also produced in vivo in patients with active lupus nephritis. Antibodies against DNA in the sera from patients with SLE were purified by affinity chromatography on DNA-cellulose, followed by nonequilibrium pH gradient electrophoresis and SDS-PAGE. The highly cationic anti-DNA antibodies of IgG class were prominent in the nonequilibrium pH gradient electrophoresis-immunoblots of the antibodies from the patients with active lupus nephritis. Decreased proteinuria after successful treatment with prednisolone was associated with disappearance of the cationic anti-DNA antibodies in the circulation. The cationic anti-DNA antibodies did bind to heparan sulfate, which is a major glycosaminoglycan in glomerular basement membrane, much better than did neutral anti-DNA antibodies. The results suggest that the cationic anti-DNA autoantibodies may play a certain role in the development of lupus nephritis. Our study demonstrates the strong association between the presence of cationic anti-DNA antibody and the development of lupus nephritis in humans.

Topics: Adolescent; Adult; Animals; Antibodies, Antinuclear; Antibody Specificity; Basement Membrane; Cattle; Chromatography, Affinity; DNA; Electrophoresis; Female; Heparitin Sulfate; Humans; Kidney Glomerulus; Lupus Erythematosus, Systemic; Lupus Nephritis; Male; Middle Aged

Cross-reactivity between anti-DNA antibodies and heparan sulfate (HS)/heparan sulfate-proteoglycan (HS-PG) of glomerular basement membrane has been previously reported. Conceivably, this determines the final outcome of glomerular injury in lupus nephritis.. We investigated the status of glomerular injury in NZB/NZW F1 mice after the administration of rabbit anti-HS-PG antibody (experiment group). The controls received normal rabbit IgG only.. All experimental animals became proteinuric 2 weeks after the administration of anti-HS-PG. The animals of the older age group (16 weeks) had significant hematuria as well. Their glomeruli exhibited hypercellularity with a heavy influx of polymorphonuclear leukocytes and monocytes into their capillaries, and some of them exhibited crescentic changes. Electron-dense deposits were present in subepithelial, subendothelial, and mesangial regions of the glomeruli. The control group had normocellular glomeruli with a few mesangial deposits. Mouse IgG and C3 displayed a granular pattern of immunofluorescence in the experimental group. Anti-rabbit IgG titers in the serum were higher in the control group, which lower in the renal glomerular eluates. No significant differences were observed in the concentrations of anti-dsDNA and -ssDNA either in the sera or in the eluates. There was also no difference between the control and experimental group in terms of antibody synthesis by the splenic lymphocytes and their proliferation subsequent to antigenic challenge.. Data suggest that administration of anti-HS-PG accentuates the glomerular injury during the natural course of lupus nephritis in (NZB/NZW F1 mice; seemingly these two antibodies (anti-HS-PG and -DNA) do not competitively inhibit the binding of the other to the same anionic sites of glomerular basement membrane enriched with heparan sulfate in vivo.

Topics: Animals; Antibodies; Antibodies, Antinuclear; Antibody Affinity; Antibody Formation; Disease Models, Animal; Female; Fluorescent Antibody Technique; Heparan Sulfate Proteoglycans; Heparitin Sulfate; Immunoglobulin G; In Vitro Techniques; Kidney Glomerulus; Lupus Nephritis; Lymphocyte Activation; Mice; Proteinuria; Proteoglycans; Rabbits

Vascular injury and microvascular thrombosis are prominent features of systemic lupus erythematosus, as are circulating DNA-binding antibodies (DNAb). Experimental glomerulonephritis can be induced by anti-endothelial cell antibodies, and polyreactive DNAb might be pathogenetic by binding to endothelial cells, perhaps influencing their non-thrombogenic nature. To test this hypothesis, eight monoclonal antibodies (mAb) that bind to DNA derived from (NZB x NZW)F1 or MRL/Mp-lpr/lpr mice, were tested for their ability to bind to human umbilical vein endothelial cells (HUVEC). Binding was assessed using flow cytometry, fluorescence microscopy and cellular ELISA. Three of the eight mAb, at concentrations employed in this study, bound to HUVEC and dermal fibroblasts. Of these three mAb, one bound also to platelets. Two of the three demonstrated strong binding to (1) freshly isolated, collagenase-digested HUVEC, (2) 2nd passage HUVEC in suspension after trypsinization and, (3) 2nd passage HUVEC growing on plastic plates. To determine whether DNA itself acted as a ligand in this binding, prior treatment with DNAase was studied. Treatment of the endothelial cells with DNAase had no effect on the binding of one mAb, but DNAase treatment of this monoclonal itself resulted in a 60% reduction in binding to HUVEC, suggesting that the binding might be mediated through DNA in the form of a DNA/anti-DNA immune complex. In contrast, DNAase digestion of the endothelial cells caused a 40% reduction in the binding of the other two monoclonal antibodies. Furthermore, one of the two mAb bound 30% more to HUVEC after themselves being subjected to DNAase treatment. These two monoclonals may therefore be binding directly to HUVEC, possibly to DNA associated with the membrane. Prior DNAase digestion of dermal fibroblasts had a more profound effect on the binding of all three autoantibodies compared to HUVEC after similar treatment. Therefore, DNA can bind independently to either antibody or cell, thus supporting build up of complexes and capture of preformed complexes. Functionally, the binding of mAb to HUVEC did not influence thrombin-induced prostacyclin synthesis, in contrast to a control monoclonal anti-endothelial cell antibody EN4, which did.

Topics: Animals; Antibodies, Antinuclear; Antibodies, Monoclonal; Cross Reactions; Deoxyribonucleases; DNA; Endothelium, Vascular; Epoprostenol; Heparitin Sulfate; Humans; Lupus Nephritis; Mice

The nature of immune complexes and their relationship to the normal glomerular basement membrane (GBM) components type IV collagen, fibronectin, and heparan sulphate proteoglycans (HSPG) have been examined in the glomeruli of 7 cases of systemic lupus erythematosus (SLE) glomerulonephritis using an ultrastructural immunogold technique. In paraformaldehyde-fixed, Lowicryl resin-embedded tissue, the electron-dense deposits contained IgG, IgM, IgA, and C3 whether they were subepithelial, intramembranous, subendothelial, or mesangial and there was no particular relationship between the class of immunoglobulin and site of immune complex localization within the glomerulus. The normal GBM components type IV collagen, fibronectin, and HSPG were found within all the glomeruli, but did not have the same distribution. Type IV collagen and fibronectin were found predominantly on the inner aspect of the GBM and diffusely throughout the more central regions of the mesangial matrix. By contrast the HSPG was seen mainly on the outer aspect of the GBM and at the periphery of the mesangial matrix. In none of the cases were GBM antigens localized within the electron-dense deposits, results which suggest that autoantibodies to these GBM components may not play a role in the development of the glomerulonephritis.

Topics: Adult; Antigen-Antibody Complex; Basement Membrane; Collagen; Female; Fibronectins; Heparitin Sulfate; Humans; Immunohistochemistry; Kidney Glomerulus; Lupus Nephritis; Male; Microscopy, Electron; Microscopy, Fluorescence; Microscopy, Immunoelectron

Previously, we have shown that anti-DNA can bind to heparan sulphate (HS), a constituent of the glomerular basement membrane (GBM). We hypothesized that binding of anti-DNA to HS in the GBM plays a role in the onset of systemic lupus erythematosus (SLE) nephritis. To test this hypothesis we measured the anti-HS reactivity in cross-sectional and longitudinal studies of SLE patients with or without nephritis. In the transverse serum study single serum samples from 26 SLE patients were studied. We found no correlation between anti-HS reactivity and previously development of nephritis (anti-HS positive: seven out of 16 with history of nephritis, two out of 10 without nephritis). However, six of the seven anti-HS positive sera in the nephritis group were obtained within 1 month of the onset of nephritis, suggesting a temporal relationship between anti-HS reactivity and onset of nephritis. In the longitudinal serum study between six and 16 serum samples were studied from each of 10 SLE-patients. In five out of five episodes of nephritis we found anti-HS reactivity before the onset or exacerbation of the nephritis. In four non-renal manifestations anti-HS reactivity was found in only one episode; in none of the three patients who remained clinically stable did serum samples show anti-HS reactivity. Anti-HS reactivity was only found in sera positive for anti-DNA by Farr assay but the anti-HS titre was not a mere reflection of the reactivity measured in the Farr assay. This indicates that only a subpopulation of anti-DNA can bind to HS. We found a high correlation (r = 0.99) between anti-HS reactivities in plasma and serum and we conclude that anti-HS reactivity in serum samples from SLE patients is not due to in vitro complex formation during clotting. Although further prospective analysis is necessary, our data suggest that measurement of anti-HS reactivity in SLE patients might identify patients at risk for the development of nephritis.

Topics: Adult; Aged; Antibodies, Antinuclear; Autoantibodies; Chi-Square Distribution; Cross Reactions; Cross-Sectional Studies; Enzyme-Linked Immunosorbent Assay; Female; Heparitin Sulfate; Humans; Longitudinal Studies; Lupus Erythematosus, Systemic; Lupus Nephritis; Male; Middle Aged; Netherlands