BACKGROUND OF THE INVENTION
The therapeutic use of antibodies is generally limited to: (a) immunotherapy, where a specific antibody directed against a discreet antigen is used to counter the effect of that antigen, e.g., using an antitoxin administered to neutralize a toxin, or antibody against an infectious agent to interrupt the pathophysiological process induced by that target organism; (b) the administration, often i.v., of high levels of antibody (gamma globulin therapy) to compensate for transient or permanent immune deficiency; and (c) monoclonal antibody therapy to combat cancer, certain autoimmune disorders and metabolic diseases. In all these cases, antibody is provided in relatively high concentrations for the purpose of having that antibody combine directly with its target antigen to render that antigen inoperable, non-infectious or neutralized. For example, Gamimune™ (Bayer Biological) contains 50 mg protein (immunoglobin) per mL and normal dosing can be up to 1000 mg/kg body weight. Gammar-P™ I.V. (Aventis Behring) is administered at dosages up to 400 mg/kg body weight. Bayhep B™ (Hepatitis B Immunoglobulin) (Bayer Biological) is 15-18% protein [immunoglobulin] is administered at dosages of up to 0.6 ml/kg body weight=0.01 g/kg=100 mg/kg. Further, Imogam Rabies-IIT™ (Aventis Pasteur) is 10-18% protein and is administered at a dosage of 0.133 ml/kg (240 mg/kg) body weight.
Diabetes mellitus is a metabolic disease state that is caused by a deficiency of insulin (Type I diabetes) or by the body's resistance to diabetes (Type II diabetes). The disease is characterized by chronic hyperglycemia, glycosuria, water and electrolyte loss, ketoacidosis, neuropathy, retinopathy, nephropathy, increased susceptibility to infection, and coma. Type I diabetes results from the autoimmune destruction of beta cells of the pancreas. Thus, proteins produced by beta cells have been a prime target in the study of diabetes as potential autoantigens that serve as the target for the immune response against the beta cells. One autoantigen found to correspond to the onset of Type I diabetes is glutamic acid decarboxylase (GAD) [Tisch, Roland, et al., Nature, 366:72-75 (1993)]. Another example of a beta cell autoantigen is insulin.
Much of the research involving the autoimmune response against beta cells or the autoantigens thought to be involved in the autoimmune response has included the administration of autoantigens, immunogenic portions of autoantigens, or molecules that mimic the autoantigens. Tian, Jide, et al.,Nat Med, 2(12): 1348-53 (1996) discusses administration of GAD to alter the diverse immune response that can lead to diabetes. Ramiya, Vijayakumar K., et al., Autoimmunity, 26:139-151 (1997) discussed administration of insulin and GAD in nonobese diabetic mouse to achieve anti-diabetic affects.
Of interest to the present application is the disclosure of co-owned U.S. Pat. No. 6,187,309, which is directed to the administration of anti-rubeola antibodies for the treatment of symptoms of various central nervous system diseases including autism, multiple sclerosis, attention deficit disorder (ADD) and attention deficit hyperactivity disorder (ADHD). Examples therein demonstrated the efficacy of treating the symptoms of those disease states with dosages of from 0.1 mg to 1 mg of anti-rubeola antibody per dose.
While the administration of larger quantities of immunoglobulins is effective in the treatment of many disease states, there remains a desire in the art for methods for the treatment and prevention of diabetes.
SUMMARY OF THE INVENTION
The present invention is directed to the discovery that the symptoms of diabetes may be effectively treated by administration of very low levels of a combination of anti-glutamic acid decarboxylase (anti-GAD) antibodies and anti-insulin antibodies. Specifically, the antibodies may be administered in one or in multiple dosages but the sum of antibodies administered in any 24 hour period (or daily period) is less than 10 mg each of anti-GAD and anti-insulin antibodies, with preferred daily dosages being less than 1.0 mg and more preferably less than 0.1 mg.
While the antibody may be monoclonal or polyclonal, it is preferably monoclonal according to one aspect of the invention. The antibody maybe administered by a variety of manners but is preferably administered subcutaneously and orally. Suitable methods of oral administration include oral drench and sublingual administration. According to another aspect of the invention the antibody is administered in an enterically protected form.
The invention provides methods for treating the symptoms of diabetes comprising the method of administering an effective amount of a combination of an antibody directed against GAD and antibody directed against insulin. The term “effective amounts of an antibody” is used herein to describe the amount of antibody administered to a subject to result in the reduction or elimination of the pathogenic autoimmune response associated with the onset of diabetes, thereby alleviating symptoms of diabetes. Preferred amounts of anti-GAD and anti-insulin antibodies for use according to the disclosed method are less than 1.0 mg of anti-GAD antibodies and less than 1.0 mg of anti-insulin antibodies, and more preferably less than 0.1 mg of anti-GAD antibodies and less than 0.1 mg of anti-insulin antibodies. A still more preferred daily dosage ranges from 1×10−6 to 1×10−2 mg of anti-GAD antibodies and 1×10−6 to 1×10−2 mg of anti-insulin antibodies. An even more preferred daily dosage ranges from 1×10−5 to 1×10−3 mg of anti-GAD antibodies and 1×10−5 to 1×10−'mg of anti-insulin antibodies.
The invention also provides pharmaceutical compositions for administration to subjects for treatment of the symptoms of diabetes comprising a dosage unit of less than 10 mg of anti-GAD antibodies and less than 10 mg of anti-insulin antibodies. A preferred dosage unit is less than 1.0 mg of anti-GAD antibodies and less than 1.0 mg of anti-insulin antibodies, and more preferably less than 0.1 mg of anti-GAD antibodies and less than 0.1 mg of anti-insulin antibodies. A still more preferred dosage unit ranges from 1×10−6 to 1×10−2 mg of anti-GAD antibodies and 1×10−6 to 1×10−2 mg of anti-insulin antibodies. An even more preferred dosage unit ranges from 1×10−5 to 1×10−3 mg of anti-GAD antibodies and 1×10−5 to 1×10−3 mg of anti-insulin antibodies.
The methods and compositions described herein relate to low levels of antibodies specific for the autoantigens of pancreatic beta cells that can reduce or eliminate the pathological consequences caused by the autoimmune response against the pancreatic beta cells. The mechanism by which this is accomplished is not completely understood and is the focus of ongoing research. Without intending to be bound by any particular theory of the invention, it is thought that the low levels of the antibodies specific for the autoantigens are able to prevent the pathogenic cascade that results from the destruction of the autoantigens by the immune system, possibly by redirecting the host immune system or by providing a negative feedback to prevent further autoimmune response. Particularly, the use of antibodies against GAD and insulin can be used as a systemic signal to specifically inhibit the body's aberrant, pathogenic response to the autoimmune response against GAD and insulin. In addition to the use of the disclosed method to alleviate symptoms of diabetes, it is further contemplated that practice of the methods disclosed herein will prove useful in the prevention of diabetes.
Antibodies of the invention can be produced using any method well known and routinely practiced in the art. Such antibodies include monoclonal and polyclonal antibodies, single chain antibodies, chimeric antibodies, bifunctional/bispecific antibodies, humanized antibodies, human antibodies, and complementary determining region (CDR)-grafted antibodies, including compounds which include CDR and/or antigen-binding sequences, which specifically recognize a polypeptide of the invention. A preferred anti-GAD antibody and anti-insulin antibody is available from Chemicon International Inc., Temecula, Calif.
Symptoms of diabetes which can be treated according to the methods of the invention include elevated blood sugar level, elevated hemoglobin A1c level, neuropathy, retinopathy, ketoacidosis, and glycosuria. With respect to blood sugar levels, normal levels are <140 mg/dl, and diabetic levels are considered to be levels >140 mg/dl.
The following examples are illustrative and are not intended to limit either the scope or spirit of the invention.