chondroitin-sulfates and Autoimmune-Diseases

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

Approximately 10% of patients with peripheral neuropathy of otherwise unknown etiology have an associated monoclonal gammopathy. Both the neuropathies and the monoclonal gammopathies in these patients are heterogeneous, but several distinct clinical syndromes that may respond to specific therapies can be recognized. It is important to recognize these syndromes because monoclonal gammopathies also occur in 1% of the normal adult population, and in some cases, monoclonal gammopathies are coincidental and unrelated to the neuropathy. In patients with IgM monoclonal gammopathies, IgM M proteins frequently have autoantibody activity and are implicated in the pathogenesis of the neuropathy. IgM M proteins that bind to myelin-associated glycoprotein (MAG) have been shown to cause demyelinating peripheral neuropathy; anti-GM1 antibody activity is associated with predominantly motor neuropathy, and anti-sulfatide or chondroitin sulfate antibodies are associated with sensory neuropathy. The IgM monoclonal gammopathies may be malignant or nonmalignant, and polyclonal antibodies with the same specificities are associated with similar clinical presentations in the absence of monoclonal gammopathy. IgG or IgA monoclonal gammopathies are associated with neuropathy in patients with osteosclerotic myeloma or the POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy myeloma, and skin changes). Amyloidosis or cryoglobulinemic neuropathies can occur with either IgM or IgG and IgA monoclonal gammopathies. Therapeutic intervention depends on the specific clinical syndrome but is generally directed at removing the autoantibodies, reducing the number of monoclonal B cells, and interfering with the effector mechanisms.

Topics: Adult; Aged; Amyloidosis; Antibody Specificity; Antineoplastic Agents; Autoantibodies; Autoantigens; Autoimmune Diseases; Chondroitin Sulfates; Gangliosides; Humans; Immunoglobulin A; Immunoglobulin G; Immunoglobulin M; Immunoglobulins, Intravenous; Middle Aged; Myelin-Associated Glycoprotein; Paraneoplastic Syndromes; Paraproteinemias; Paraproteins; Peripheral Nervous System Diseases; Plasmapheresis; Sulfoglycosphingolipids

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

Heparin-induced thrombocytopenia with thrombosis (HITT) is the most severe side effect of heparin administration. Patients with HITT may die or have permanent sequelae such as stroke or limb amputation. Contaminated heparin is associated with anaphylactic reactions and deaths by activating the contact system. It is also associated with high incidence of HIT via a yet unknown mechanism. This study showed that although oversulfated heparin byproduct induced thrombin activities in both normal and HIT patient plasmas through the contact system activation, authentic heparin induced thrombin activities only in HIT patient plasmas containing autoantibodies against protein/ heparin complex. These data suggest that the negatively charged immunoglobulin G (IgG)/platelet factor 4 (PF4)/heparin complex activate the contact system and produce thrombin in human plasma, and thrombin partially activates the platelets allowing subsequent platelet activation through IgG/Fc receptor II signaling. The newly discovered mechanism of heparin-induced thrombin activity could explain the increased incidence of HIT in patients exposed to contaminated heparin. Furthermore, the assays used in these studies would be valuable for HIT diagnosis, prevention, and treatment.

Topics: Adult; Aged; Aged, 80 and over; Anaphylaxis; Animals; Anticoagulants; Autoantibodies; Autoimmune Diseases; CHO Cells; Chondroitin Sulfates; Cricetinae; Cricetulus; Disease Outbreaks; Drug Contamination; Enzyme Activation; Female; Heparin; Humans; Immunoglobulin G; Kallikreins; Male; Middle Aged; Platelet Activation; Platelet Factor 4; Prekallikrein; Prothrombin; Thrombin; Thrombocytopenia

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