heparitin-sulfate and Autoimmune-Diseases

Secreted phospholipases A(2) (sPLA(2)s) are enzymes detected in serum and biological fluids of patients with various inflammatory, autoimmune and allergic disorders. Different isoforms of sPLA(2)s are expressed and released by human inflammatory cells, such as neutrophils, eosinophils, T cells, monocytes, macrophages and mast cells. sPLA(2)s generate arachidonic acid and lysophospholipids thus contributing to the production of bioactive lipid mediators in inflammatory cells. However, sPLA(2)s also activate human inflammatory cells by mechanisms unrelated to their enzymatic activity. Several human and non-human sPLA(2)s induce degranulation of mast cells, neutrophils and eosinophils and activate exocytosis in macrophages. In addition some, but not all, sPLA(2) isoforms promote cytokine and chemokine production from macrophages, neutrophils, eosinophils, monocytes and endothelial cells. These effects are primarily mediated by binding of sPLA(2)s to specific membrane targets (heparan sulfate proteoglycans, M-type, N-type or mannose receptors) expressed on effector cells. Thus, sPLA(2)s may play an important role in the initiation and amplification of inflammatory reactions by at least two mechanisms: production of lipid mediators and direct activation of inflammatory cells. Selective inhibitors of sPLA(2)-enzymatic activity and specific antagonists of sPLA(2) receptors are current being tested for pharmacological treatment of inflammatory and autoimmune diseases.

Topics: Autoimmune Diseases; Cell Degranulation; Exocytosis; Heparitin Sulfate; Humans; Inflammation; Inflammation Mediators; Lectins, C-Type; Leukocytes; Macrophage Activation; Mannose Receptor; Mannose-Binding Lectins; Phospholipases A; Protein Binding; Proteoglycans; Receptors, Cell Surface

Several counterintuitive treatment paradoxes complicate the management of immune heparin-induced thrombocytopenia (HIT). For example, simple discontinuation of heparin often fails to prevent subsequent HIT-associated thrombosis. Thus, current treatment guidelines recommend substituting heparin with a rapidly acting alternative anticoagulant (eg, danaparoid, lepirudin, or argatroban) even when HIT is suspected on the basis of thrombocytopenia alone ("isolated HIT"). Another paradox-coumarin (warfarin) anticoagulation-can lead to venous limb gangrene in a patient with HIT-associated deep-vein thrombosis. Thus, warfarin is not recommended during acute thrombocytopenia secondary to HIT. However, warfarin can be given as overlapping therapy with an alternative anticoagulant, provided that (1) initiation of warfarin is delayed until substantial platelet count recovery has occurred (to at least above 100 x 10(9)/L); (2) low initial doses of warfarin are used; (3) at least 5 days of overlapping therapy are given; and (4) the alternative agent is maintained until the platelet count has normalized. It has recently been recognized that HIT antibodies are transient and usually do not recur upon subsequent re-exposure to heparin. This leads to a further paradox-patients with previous HIT can be considered for a brief re-exposure to heparin under exceptional circumstances; for example, heart surgery requiring cardiopulmonary bypass, if HIT antibodies are no longer detectable using sensitive assays. For patients with acute or recent HIT who require urgent heart surgery, other approaches include use of alternative anticoagulants (eg, lepirudin or danaparoid) for cardiopulmonary bypass or antiplatelet agents (eg, tirofiban or epoprostenol) to permit intraoperative use of heparin.

Topics: Anticoagulants; Antithrombins; Arginine; Autoimmune Diseases; Chondroitin Sulfates; Dermatan Sulfate; Drug Combinations; Heparin; Heparitin Sulfate; Hirudin Therapy; Hirudins; Humans; Pipecolic Acids; Recombinant Proteins; Sulfonamides; Thrombocytopenia; Warfarin

Beta2-glycoprotein I (beta2GPI) is a cofactor for anti-phospholipid (aPL) binding to cardiolipin (CL)-coated plates. Beta2GPI is also able to bind to endothelial cell (EC) membranes as supported by in-vivo as well as by in-vitro studies. The PL-binding site in the fifth domain of the molecule is involved in the adhesion to endothelium. Actually, specific mutations in this molecular portion abolish endothelium binding and a synthetic peptide spanning the sequence Glu274-Cys288 of the CL-binding site displays comparable adhesion to EC monolayers. Heparan sulphate appears to be one of the anionic EC membrane structures with which cationic beta2GPI interacts, as supported by studies with heparitinase-treated EC. Beta2GPI binding to EC might be related to its activity as endothelial growth factor or as a lipid-carrying glycoprotein. Adhesion of beta2GPI to endothelial membranes offers suitable epitopes for circulating aPL that, once bound, can induce cell activation

Topics: Amino Acid Substitution; Anions; Antibodies, Anticardiolipin; Antiphospholipid Syndrome; Autoantigens; Autoimmune Diseases; beta 2-Glycoprotein I; Binding Sites; Blood Coagulation; Cell Membrane; Endothelium, Vascular; Epitopes; Glycoproteins; Heparitin Sulfate; Humans; Macromolecular Substances; Point Mutation; Protein Binding; Protein Conformation; Proteoglycans; Surface Properties

Topics: Aggrecans; Alzheimer Disease; Amyloid beta-Protein Precursor; Animals; Autoantibodies; Autoimmune Diseases; Blood-Brain Barrier; Brain; Capillaries; Cell Death; Chondroitin Sulfate Proteoglycans; Extracellular Matrix Proteins; Glycoproteins; Heparan Sulfate Proteoglycans; Heparitin Sulfate; Humans; Immunoglobulin G; Lectins, C-Type; Models, Biological; Nerve Degeneration; Protein Processing, Post-Translational; Proteoglycans; Rats

Basement membranes support epithelial and endothelial cells, prevent the passage of proteins, and generate histologically distinct compartments in the body. Basement membranes contain a number of components, only some of which have been isolated and characterized. These include type IV collagen, heparan sulfate proteoglycan, laminin, entactin, and fibronectin. Some components, such as bullous pemphigoid antigen and Goodpasture antigen, are present only in specific tissues, such as the skin or the kidneys. Alterations in basement membranes are associated with various diseases. For example, metastatic cells are able to attach to basement membranes and to degrade them. Such interactions with basement membranes underlie the ability of these cells to penetrate tissues and to spread in the body. In diabetes, basement membranes are thickened but are more porous, which is possibly due to a decreased amount of heparan sulfate proteoglycan. Basement membranes are also the site of immunopathologic disorders.

Topics: Autoimmune Diseases; Basement Membrane; Chondroitin Sulfate Proteoglycans; Collagen; Diabetes Mellitus; Glycoproteins; Heparan Sulfate Proteoglycans; Heparitin Sulfate; Humans; Neoplasms; Proteoglycans

Patients who develop heparin-induced thrombocytopenia (HIT) frequently need further anticoagulation to treat an ongoing thromboembolic problem or to prevent one. Orgaran (Org 10172), a low-molecular-weight (LMW) glycosaminoglycuronan, has shown a low frequency (10%) of cross-reactivity in vitro with sera containing the HIT antibody, in contrast to the much higher frequency of cross-reactivity (approximately 80%) shown by the LMW heparins. This paper summarises the results of intravenous or subcutaneous Orgaran treatment in 57 of 67 Australian patients, in whom the diagnosis of HIT was reasonably confirmed by exclusion of other causes of thrombocytopenia and by objective tests. The presenting indications for Orgaran were: continuous venovenous haemofiltration and haemodialysis (n = 21), thrombo-embolism treatment (n = 23), thrombo-embolism prophylaxis (n = 10), and anticoagulation for coronary artery by-pass graft (n = 4), peripheral by-pass graft surgery and plasmapheresis (n = 1 each). The results showed Orgaran to be a safe, well-tolerated, effective (successful treatment in over 90% of patients) anticoagulant in patients with a high thrombotic and/or bleeding risk even if critically ill and requiring haemofiltration. The complete results of the world-wide study in 161 patients confirmed not only these clinical findings in the subgroup of 57 Australian patients, but also the low cross-reactivity (12%) of Orgaran with the HIT serum factor.

Topics: Antibody Specificity; Autoantibodies; Autoimmune Diseases; Chondroitin Sulfates; Cross Reactions; Dermatan Sulfate; Drug Evaluation; Glycosaminoglycans; Hemofiltration; Heparin; Heparinoids; Heparitin Sulfate; Humans; Postoperative Complications; Thrombocytopenia; Thromboembolism

Thrombin is a key factor in the stimulation of fibrin deposition, angiogenesis, proinflammatory processes, and proliferation of fibroblast-like cells. Abnormalities in these processes are primary features of rheumatoid arthritis (RA) in synovial tissues. Tissue destruction in joints causes the accumulation of large quantities of free hyaluronic acid (HA) in RA synovial fluid. The present study was conducted to investigate the effects of HA and several other glycosaminoglycans on antithrombin, a plasma inhibitor of thrombin. Various glycosaminoglycans, including HA, chondroitin sulfate, keratan sulfate, heparin, and heparan, were incubated with human antithrombin III in vitro. The residual activity of antithrombin was determined using a thrombin-specific chromogenic assay. HA concentrations ranging from 250 to 1000 mug/ml significantly blocked the ability of antithrombin to inhibit thrombin in the presence of Ca2+ or Fe3+, and chondroitin A, B and C also reduced this ability under the same conditions but to a lesser extent. Our study suggests that the high concentration of free HA in RA synovium may block antithrombin locally, thereby deregulating thrombin activity to drive the pathogenic process of RA under physiological conditions. The study also helps to explain why RA occurs and develops in joint tissue, because the inflamed RA synovium is uniquely rich in free HA along with extracellular matrix degeneration. Our findings are consistent with those of others regarding increased coagulation activity in RA synovium.

Topics: Antithrombin III; Arthritis, Rheumatoid; Autoimmune Diseases; Calcium; Chondroitin Sulfates; Chromogenic Compounds; Dermatan Sulfate; Glycosaminoglycans; Heparin; Heparitin Sulfate; Humans; Hyaluronic Acid; Iron; Keratan Sulfate; Synovial Fluid; Thrombin

Heparan sulfate, a glycosaminoglycan component of vascular endothelial proteoglycans, provides the anticoagulant functions associated with heparin on the endothelial cell surface. We have demonstrated the presence of spontaneous occurring antibodies to heparin polysaccharides (HPS) in humans. Elevation of serum anti-HPS antibodies were closely associated with the prevalence of thrombosis or fetal loss in patients with autoimmune disease. Affinity purified anti-HPS antibodies inhibited heparin dependent formation of thrombin-antithrombin III complexes. In order to further analyze these autoantibodies, a murine IgG monoclonal anti-HPS antibody, designated H16, was generated. H16 mAb specifically bound to heparin, heparan sulfate and human umbilical vascular endothelial cells (HUVEC). The binding of H16 mAb to HUVEC was specifically inhibited by heparin. Further, H16 mAb inhibited the binding of antithrombin III to heparin in a dose dependent manner. These results indicate that this mAb could recognize antithrombin III-binding sites on vascular endothelial heparan sulfate, leading to procoagulant states through the inhibition of heparin/heparan sulfate dependent anticoagulant process.

Topics: Abortion, Spontaneous; Animals; Antibodies, Monoclonal; Antithrombin III; Autoantibodies; Autoimmune Diseases; Binding Sites; Endothelium, Vascular; Female; Heparitin Sulfate; Humans; Mice; Peptide Hydrolases; Pregnancy; Thrombosis

Heparan sulfate proteoglycans have pleiotropic functions in the normal vasculature. Autoimmunity to heparan sulfate may play a role in vascular injury. In this study, monoclonal antibody (mb) 28C3-1 to heparan sulfate derived from autoimmune Tight skin (TSK) mice was investigated for its reactivity with endothelial cells. Mb 28C3-1 was previously demonstrated to inhibit the heparin-accelerated formation of antithrombin III-thrombin complexes. In the current studies it is shown that mAb 28C3-1 bound to heparan sulfate proteoglycan with the highest affinity in direct binding solid phase radioimmunoassay. Binding to the heparan sulfate was stronger than binding to the protein core, indicating that the primary epitope of 28C3-1 is the polysaccharide component. Using confocal fluorescent microscopy, mAb 28C3-1 was demonstrated to bind to the endothelial cell surface. Furthermore, treatment of endothelial cells with heparitinase abolished mAb 28C3-1 binding. These studies support the hypothesis that naturally occurring anti-heparan sulfate autoantibodies from autoimmune mice may cause vascular injury by initial interaction with endothelial cell surface heparan sulfate.

Topics: Animals; Antibodies, Monoclonal; Autoantibodies; Autoimmune Diseases; Cattle; Cells, Cultured; Endothelium; Heparitin Sulfate; Mice; Mice, Mutant Strains; Polysaccharide-Lyases; Radioimmunoassay; Skin Diseases

Heparin and heparan sulfate are related glycosaminoglycans which demonstrate high-affinity interactions with a number of proteins, including antithrombin III. The immunogenicity of heparin has been reported previously employing heparin-protein conjugates as immunogens and as antigens in solid-phase assays. Previous studies also demonstrate that anti-heparin antibodies play a role in autoimmune diseases including systemic lupus and anti-phospholipid syndrome and in patients who receive heparin for therapeutic purposes. In the current study, we investigated the expression of monoclonal anti-heparin antibodies in nonimmunized, autoimmune MRL/lpr/lpr++ mice employing a liquid-phase radioimmunoassay. The Kd of monoclonal IgG2b autoantibodies for heparin was approximately 10(-8)M. Anti-heparin antibodies were precipitating, and were not polyreactive. The IgG monoclonal antibodies described in this study represent an immunological instance of a specific, high-affinity heparin-protein interaction.

Topics: Animals; Antibodies, Monoclonal; Antibody Affinity; Antibody Specificity; Antigen-Antibody Reactions; Antiphospholipid Syndrome; Autoimmune Diseases; Female; Heparin; Heparitin Sulfate; Humans; Hybridomas; Immunoglobulin G; Kinetics; Lupus Erythematosus, Systemic; Mice; Mice, Mutant Strains; Radioimmunoassay

Autoantigen-reactive T cells might play an important role in the pathogenesis of systemic lupus erythematosus (SLE). Autoantigen-reactive T cell clones were generated from spleens of NZB x NZW F1 (BWF1) and normal control BALB/c mice with interleukin-2 (IL-2), a procedure that selects for in vivo activated antigen-reactive T cells. The antigen-specificity of the T cell clones was tested by using a panel of candidate autoantigens. The T cell clones from BWF1 mice but not those from BALB/c mice proliferated against heparan sulfate, the major glycosaminoglycan of glomerular basement membrane. None of the clones proliferated against dsDNA or cardiolipin. All the heparan sulfate-reactive T cell clones had the ability to selectively augment the production of IgG anti-dsDNA autoantibodies. When cultured with either heparan sulfate or Concanavalin A, the T cell clones produced high levels of IL-4 and IL-5 with no detectable IL-2 or IFN-gamma. In contrast, T cell clones derived from BALB/c mice augmented the production of total polyclonal IgG but not the production of anti-dsDNA antibodies. These studies indicate the existence of heparan sulfate-reactive T cells in BWF1 mice. Characterization of heparan sulfate-reactive T cells that could selectively augment anti-dsDNA production will permit the design of targeted and antigen-specific therapy.

Topics: Animals; Autoimmune Diseases; Cell Separation; Clone Cells; Epitopes; Female; Heparitin Sulfate; Immunophenotyping; Interleukin-2; Major Histocompatibility Complex; Mice; Mice, Inbred BALB C; Mice, Inbred DBA; Mice, Inbred NZB; Rats; T-Lymphocytes; T-Lymphocytes, Helper-Inducer

We tested sera of patients with various autoimmune rheumatic diseases for the presence of antibodies against sulphatide (an acidic glycosphingolipid), identified as a target antigen for antibodies against the liver cell membrane. Thirty-five percent (7/20) of patients with lupus in the active stage possessed anti-sulphatide antibodies, whereas 10% (2/20) of those in the inactive stage and 20% (4/20) of those in the stationary stage possessed such antibodies. Moreover, 10% (3/29) of patients with other autoimmune rheumatic diseases also possessed anti-sulphatide antibodies. The level of anti-sulphatide antibodies was significantly correlated with the levels of anti-double-stranded (ds) DNA antibodies (r = 0.634, P less than 0.001) and dextran sulphate-binding IgG (r = 0.407, P less than 0.001). The serum levels of antibodies against sulphatide were correlated with a history of seizures or psychosis in patients with autoimmune rheumatic diseases. Gels coupled with polyanionic dextran sulphate, monoanionic sulphanilic acid and DNA were shown effectively to adsorb anti-sulphatide antibodies in the sera of patients with active systemic lupus erythematosus (SLE) and autoimmune chronic active hepatitis (AI-CAH). These results suggest that the observed reactivity with sulphatide is due to the presence of antibodies capable of reacting with various anionic molecules in the sera of patients with autoimmune rheumatic diseases as well as those with AI-CAH.

Topics: Adsorption; Antibodies, Antinuclear; Autoimmune Diseases; Cardiolipins; Chromatography, Gel; Dextran Sulfate; Enzyme-Linked Immunosorbent Assay; Heparitin Sulfate; Hepatitis, Chronic; Humans; Immunoglobulin G; Rheumatic Diseases; Sulfoglycosphingolipids

Sera from patients with poststreptococcal glomerulonephritis (PSGN) known to have antibodies to proteoglycans were studied for the presence of antibodies against other basement membrane (BM) components. BM collagen (type IV) was isolated in the native state by extracting bovine anterior lens capsule (ALC) with 0.5 M acetic acid. The 7-S (collagenous) domain and the NC-1 (noncollagenous) domain of type IV collagen were obtained after bacterial collagenase digestion of ALC followed by gel filtration. Laminin was isolated from the mouse EHS tumor and fibronectin from human plasma. Immunologic studies, using an ELISA and electroimmunoblot, revealed the presence of antibodies that reacted with intact, native type IV collagen and the 7-S collagenous domain of this molecule. Reaction with the NC-1 (noncollagenous) domain was minimal, and not higher than that obtained with control sera. Laminin reaction strongly with the patients' sera, but fibronectin did not. Unlike sera from patients with Goodpasture syndrome, which contain antibodies primarily against the NC-1 (noncollagenous) domain of type IV collagen, sera from patients with acute PSGN contain antibodies against all the major macromolecular components of BM. This difference in immunologic reactivity may account for the observed differences in the pathologic picture at the glomerular level.

Topics: Anti-Glomerular Basement Membrane Disease; Autoimmune Diseases; Basement Membrane; Collagen; Extracellular Matrix; Fibronectins; Glomerulonephritis; Heparitin Sulfate; Humans; Laminin; Proteoglycans; Streptococcal Infections