Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0409974 (lupus)
 22,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the present study, we sought evidence for a surface nucleosome receptor in the fibroblastic cell line CV-1, and questioned whether anti-double-stranded (ds) DNA and/or anti-histone autoantibodies could recognize and influence the fate of cell surface-bound nucleosomes. 125I-labeled mononucleosomes were shown to bind to the cell layer in a specific, concentration-dependent and a saturable manner. Scatchard analysis revealed the presence of two binding sites: a high-affinity site with a Kd of approximately 7nM and a low-affinity site (Kd approximately 400 nM) with a high capacity of 9 x 10(7) sites. Visualization of bound mononucleosomes by fluorescence revealed staining on both the cell surface and the extracellular matrix (ECM). Purified mononucleosome-derived ds DNA (180-200 bp) was found to complete for binding of 125I-mononucleosomes on the low-affinity site, to stain exclusively the ECM in immunofluorescence, and to precipitate three specific proteins of 43, 180 and 240 kDa from 125-I-labeled cell lysates. Nucleosomes were found to precipitate not only the 180-kDa ds DNA-reactive component, but also a unique protein of 50 kDa, suggesting that this protein is a cell surface receptor for nucleosomes on these fibroblasts. Once bound on the cell surface, mononucleosomes were recognized and secondarily complexed by lupus anti-ds DNA or anti-histone antibodies (i.e. anti-nucleosome antibodies), thus forming immune complexes in situ. The presence of these complexing auto-antibodies was found dramatically to enhance the kinetics of mononucleosome internalization. Following the internalization of the nucleosome-anti-nucleosome complexes by immunofluorescence, we observed the formation of vesicles at the edge of the cells by 5-10 min which moved toward the perinuclear region by 20-30 min. By means of double-fluorescence labeling and proteolytic treatment, these fluorescent vesicles were shown to be in the cytoplasm, suggesting true endocytosis of nucleosome-anti-nucleosome immune complexes. As shown by confocal microscopy, at no stage of this endocytic process was there any indication that coated pits or coated vesicles participated. Co-distribution of the endocytic vesicles with regions rich in actin filaments and inhibition of endocytosis of nucleosome-anti-nucleosome complexes by disruption of the microfilament network with cytochalasin D suggest a mechanism mediated by the cytoskeleton. Taken together, our data provide evidence for the presence of a surface nucleosome receptor. We also show that anti-ds DNA and anti-histone antibodies can form nucleosome-anti-nucleosome immune complexes in situ at the cell surface, and thus dramatically enhance the kinetics of nucleosome endocytosis.
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PMID:Binding of nucleosomes to a cell surface receptor: redistribution and endocytosis in the presence of lupus antibodies. 861 20

Immunoglobulins were eluted from glomeruli of 50 lupus-prone, lpr mice and their physicochemical properties and specificity were compared with those in sera pooled from the same mice. Although immunoglobulins in glomeruli had higher isoelectric points than those in sera, there were no appreciable differences in the relative contents of neutral and acidic immunoglobulins between them. The proportion of IgG3 subclass was slightly higher in glomerular than serum immunoglobulins. Both anti-single-stranded and anti double-stranded DNA antibodies were twofold higher in glomerular than serum immunoglobulins, while anti-Sm antibodies were not recovered in glomerular eluate despite their high activity in serum. Antibodies in glomerular eluate reacted most strongly with histones, especially with core histones, while those in sera bound preferentially with histone H1, Sm-B, -B', and -D antigens. Since histones are very basic, they would have a higher affinity for negatively charged glomerular constituents, leading to an in situ formation of immune complexes involving fixed histones and their binding with antibodies for the induction of nephritides. Otherwise, such immune complexes themselves might retain positive charges sufficient for an affinity with the glomerular basement membrane. These results indicate that histone-anti-histone antibody system may play a role in the perpetuation of murine lupus nephritis.
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PMID:Selective accumulation of anti-histone antibodies in glomeruli of lupus-prone lpr mice. 867 43

Despite observations linking the severity of lupus nephritis to the quantity and location of glomerular immune deposits, it had been difficult to decipher the primary role of B cells and autoantibodies in this process. Newer technologies have provided the means to evaluate the roles of whole B cell populations and individual immunoglobulins in lupus lesions. In this review, recent advances in this area are summarized, with particular emphasis on work from the authors' laboratories. The results implicate a primary role for B cells and immunoglobulins in lupus nephritis, including glomerular, interstitial, and vascular lesions. Multiple antibody-ligand interactions participate in glomerular immune deposit formation in individuals with lupus nephritis. Recent evidence suggests that in situ formation of immune deposits by either cross-reactivity of autoantibodies with intrinsic glomerular antigens (i.e., anti-DNA antibodies with laminin) or direct interaction of autoantibodies with circulating autoantigens lodged within glomeruli (i.e., anti-DNA antibodies with histone/DNA). The predominant autoantibody-glomerular antigen interaction(s) in a given individual influences the principal location of immune deposition, which in turn influences the pathologic and clinical expression of disease. It is believed that these phenomena contribute to the phenotypic diversity commonly observed among individuals with lupus nephritis. Furthermore, these consequences are dependent on properties unique to both subsets of lupus autoantibodies and to their target antigen ligands within the glomerulus. Thus, the autoantibody variable or antigen binding region, along with the nature and location of the target glomerular antigen (or site of circulating antigen deposition), are influential in initiating these perturbations.
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PMID:Emerging concepts regarding B cells and autoantibodies in murine lupus nephritis. B cells have multiple roles; all autoantibodies are not equal. 870 3

F1 hybrids of New Zealand Black (NZB) and New Zealand White (NZW) mice are genetically predisposed to develop a lupus-like autoimmune disease characterized by IgG autoantibody production and an immune complex glomerulonephritis. Genes from both parental strains contribute to autoimmunity in the F1 animal. NZW mice produce mostly non-pathogenic autoantibodies to ssDNA and histones as their major autoimmune trait. We studied the genetics of this trait in order to gain insight into the NZW contribution to F1 disease. Genome-wide mapping of (NZW x BALB/c)F1 x NZW backcross mice showed that four NZW non-MHC loci on chromosomes 1, 11, 16, and 19 were linked with IgG autoantibody production. Another NZW locus on chromosome 14 appeared to be selectively linked with IgG anti-histone Abs. In this backcross, contributions from the nonautoimmune BALB/c strain were also apparent. Heterozygosity for the BALB/c MHC (H2d) was linked with IgG autoantibody production. This influence of H2d is therefore similar to that seen in (NZW x NZB)F1 mice, in which heterozygosity for H2d enhances autoantibody production and disease. Surprisingly, two non-MHC BALB/c loci were linked with IgM autoantibody levels, whereas no NZW loci had such an effect. Neither of these two loci have been previously linked with autoimmunity in lupus-prone mice. These data show that autoantibody production in NZW mice is a polygenic trait that is influenced by contributions from MHC and non-MHC genes. The results also support the hypothesis that NZW genes act to class-switch the autoantibody response, an effect that appears to contribute to disease in (NZB x NZW)F1 mice.
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PMID:Backcross analysis of genes linked to autoantibody production in New Zealand White mice. 880 79

The study was made of lisine- and arginine-rich histone fractions and DNA in lymphocytes of peripheral blood in patients with lupus erythematosus. The findings showed intranuclear changes of immunocompetent cells in various forms of the disease. The above parameters may be used in the diagnosis, evaluation of treatment efficacy, prognosis.
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PMID:[An analysis of the lymphoid cell histones in patients with different forms of lupus erythematosus]. 905 53

Programmed cell death, an essential function in all cells, plays a central role in maintaining immune system homeostasis and controlling autoimmune reactions. Cell death may be an essential element in disseminated lupus erythematosus: defective cell death could lead to the development of autoreactive lymphocyte clones and degradation products of cell death could be implicated in autoimmunity induction and onset of renal lesions. Anomalies in programmed cell death have been demonstrated in murine models of lupus: mutations of the fas and fas-ligand genes, which play a known role in programmed cell death, produce the lpr and gld phenotypes associating lymphoproliferation and lupus. Transgenic mice which express Bcl-2 (the product of Bcl-2 inhibits programmed cell death) on B lymphocytes develop a lupus-type autoimmune disease. The role of these types of anomalies in human disease is not yet elucidated. However, cell death, via the degradation fragments of chromatin, could play a role in inducing antibody production and development of renal lesions. The anti-DNA antibodies, with characteristic antigen-induced immune response (clone expansion, class computation and somatic mutations) could be induced by nucleosomes released during cell death. Several arguments favor this mechanism including cation residues of histone nucleosomes which would bind to anionic residues of sulfate heparan and lead to deposit of autoantibodies in the glomerulus. The dual role of cell death is not really contradictory in autoimmune disease controlled by several independent genes, but would be compatible with several different genetic backgrounds.
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PMID:[Cell death and lupus]. 909 57

It is generally assumed that anti-dsDNA antibodies play an important role in the pathogenesis of lupus nephritis. This is mainly based on the facts that an increase in anti-dsDNA titer often precedes onset of renal disease, that immune deposits are present in glomeruli and that eluates of glomeruli are enriched for anti-dsDNA. This led to the classical concept that deposition of DNA-anti-DNA complexes incites the glomerular inflammation. However, important pieces of evidence are lacking to support this hypothesis. Free, naked, DNA is not present in the circulation. The existence of DNA/anti-DNA complexes is highly questionable and injection of these complexes hardly leads to glomerular localization. As an alternative concept cross-reactivity of anti-dsDNA with glomerular constituents like heparan sulfate (HS) and laminin has been proposed. However, subsequent research has indicated that this cross-reactivity is due to nucleosomal antigens (histones and DNA) complexed to the auto-antibodies. The cationic histone part of the complex is responsible for the binding to the anionic HS. This binding also occurs in vivo since renal perfusion of nucleosome complexed antibodies leads to abundant binding of auto-antibodies to the GBM, while enzymatic removal of HS from the GBM, decreases this binding considerably. Non-complexed antibodies did not bind at all. This mechanism of binding is also consistent with the decrease of HS staining in the GBM in human and murine lupus due to masking of HS with nucleosome-complexed auto-antibodies. Furthermore the presence of histones and nucleosomes in glomerular deposits in lupus nephritis was recently shown. Elution of auto-antibodies from glomeruli not only showed anti-dsDNA but also anti-nucleosome specificities. Nucleosomes are not only important for the induction of glomerular lesions, but there is now also increasing evidence that the nucleosome is the auto-antigen that drives the auto-immune response in SLE. There is ample evidence that this response is antigen-driven and T cell dependent. However immunization with DNA in general fails to induce pathogenic anti-dsDNA antibodies. Recently, in SLE T helper cells were identified specific for nucleosomes. These nucleosome specific T helper cells were not only able to induce anti-nucleosome antibodies but also anti-dsDNA and anti-histone antibodies. This is in line with the finding that in SLE nucleosome specific antibodies are formed. These antibodies react exclusively with nucleosomes and not with its constituents DNA or histones. The formation of these nucleosome specific antibodies precedes the development of anti-dsDNA or anti-histone suggesting that the loss of tolerance for nucleosomes is a primary event. The systemic release of nucleosomes is due to an aberrant apoptosis. There is now growing evidence that apoptosis is disturbed both in certain murine lupus models as well as in human lupus. In conclusion, nucleosomes seem to play a central role in the induction and the effector phase of SLE.
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PMID:Autoimmunity against nucleosomes and lupus nephritis. 909 59

Recently, anti-nucleosome antibodies, which do not bind to DNA or to individual histones, have been identified in longitudinal studies in lupus mice. These anti-nucleosome antibodies occur early in spontaneous SLE and are formed prior to other anti-nuclear specificities. However, nucleosomal epitopes are yet to be fully characterized. We selected a panel of six monoclonal anti-nucleosome antibodies (mAbs) (#2, #32, #34, PL2-6, LG8-1 and LG10-1) derived from lupus mice. These mAbs were tested in ELISA on subnucleosome structures and on a panel of 53 histone peptides, covering the entire sequence of the five histones. Two mAbs reacted with one of these peptides, but the reactivity hardly exceeded the background reactivity. Based on the nucleosome and subnucleosome ELISA we identified different recognition patterns. Three mAbs showed the highest reactivity towards the intact nucleosome. For two of them (#32 and LG8-1) the nucleosomal epitope was primarily located on H2A-H2B/DNA, whereas for mAb #34 this primary epitope was located on H3/H4/DNA. Two mAbs (#2 and PL2-6) showed the highest reactivity with H2A-H2B/DNA and one mAb (LG10-1) recognized H3-H4/DNA. In the subnucleosome ELISA all but one (mAb #32) recognized more than one epitope, including DNA complexed to a variety of cationic molecules. Comparing these reactivities we identified for all mAbs one specific nucleosomal epitope, whereas reactivity with other subnucleosomes was comparable to the reactivity towards DNA complexed with cationic molecules. In inhibition experiments both in ELISA and in immunofluorescence it was found that only one of the mAbs (i.e. PL2-6), recognizing an epitope on H2A-H2B/DNA as primary epitope, could be inhibited by H2A-H2B/DNA in fluid phase. The two mAbs recognizing an epitope on H3-H4/DNA as primary epitope could be inhibited by H3-H4/DNA in fluid phase. From these analyses, we conclude first that for these nucleosome specific mAbs linear histone peptides are not very important. Second, that these mAbs all recognize different epitopes on both H2A/H2B-DNA and H3/H4-DNA and third that some solid phase H2A/H2B-DNA epitopes are not expressed on fluid phase H2A/H2B-DNA. Our findings suggest that in SLE the nucleosome can act as auto-antigen and that there is no immunodominant beta cell epitope within the nucleosome.
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PMID:Specificity of monoclonal anti-nucleosome auto-antibodies derived from lupus mice. 911 74

In the process of positionally cloning a candidate gene responsible for hereditary hemochromatosis (HH), we constructed a 1.1-Mb transcript map of the region of human chromosome 6p that lies 4.5 Mb telomeric to HLA-A. A combination of three gene-finding techniques, direct cDNA selection, exon trapping, and sample sequencing, were used initially for a saturation screening of the 1.1-Mb region for expressed sequence fragments. As genetic analysis further narrowed the HH candidate locus, we sequenced completely 0.25 Mb of genomic DNA as a final measure to identify all genes. Besides the novel MHC class 1-like HH candidate gene HLA-H, we identified a family of five butyrophilin-related sequences, two genes with structural similarity to a type 1 sodium phosphate transporter, 12 novel histone genes, and a gene we named RoRet based on its strong similarity to the 52-kD Ro/SSA lupus and Sjogren's syndrome auto-antigen and the RET finger protein. Several members of the butyrophilin family and the RoRet gene share an exon of common evolutionary origin called B30-2. The B30-2 exon was originally isolated from the HLA class 1 region, yet has apparently "shuffled" into several genes along the chromosome telomeric to the MHC. The conservation of the B30-2 exon in several novel genes and the previously described amino acid homology of HLA-H to MHC class 1 molecules provide further support that this gene-rich region of 6p21.3 is related to the MHC. Finally, we performed an analysis of the four approaches for gene finding and conclude that direct selection provides the most effective probes for cDNA screening, and that as much as 30% of ESTs in this 1.1-Mb region may be derived from noncoding genomic DNA.
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PMID:A 1.1-Mb transcript map of the hereditary hemochromatosis locus. 914 41

An NZB locus on distal chromosome 1 has been linked to murine lupus nephritis in backcross analyses of New Zealand mice. This locus, designated Nba2 for New Zealand Black autoimmunity 2, was found to colocalize in both (NZB x SM/J)F1 x NZW and (B6.H2z x NZB)F1 x NZB backcrosses, and was most likely situated between 92 and 97 cM from the centromere. This region of mouse chromosome 1 encodes several candidate genes, including the low affinity Fc gamma receptor genes. Both backcrosses were examined by interval mapping for quantitative trait loci linked with autoantibody and total Ig production. Nba2 was linked with elevated serum levels of multiple autoantibodies, including a variety of antinuclear Abs (anti-dsDNA, anti-chromatin and anti-histone) and autoantibodies to gp70, in both backcrosses. Nba2 was also linked (or showed a trend for linkage) with hypergammaglobulinemia and IgG1, IgG2a, and/or IgG3 levels in each backcross. In the (B6.H2z x NZB)F1 x NZB backcross, MHC was an additional genetic contribution that interacted with Nba2 in the production of autoantibodies and the development of nephritis. Together, these data provide new insight into the nature of one important genetic contribution to murine lupus and suggest that Nba2 may act as an immune response gene that influences Ag-driven B cell responses to self and possibly to exogenous Ags.
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PMID:Control of multiple autoantibodies linked with a lupus nephritis susceptibility locus in New Zealand black mice. 916 82


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