METHODS FOR INHIBITING DIAZEPAM BINDING PROTEIN
Autophagy is typically activated by starvation, allowing cells and organisms to mobilize their energy reserves. It is known that pharmacological modulation of autophagy represents a therapeutic potential. Here the inventors report that a protein that is released from cells in an unconventional, autophagy-dependent manner, namely, diazepam binding inhibitor (DBI), regulates autophagy. In particular, the inventors demonstrate that DBI inhibits autophagy and that the supply of recombinant DBI to mice enhanced glycolysis, enhanced lipogenesis, and inhibited fatty acid oxidation. The inventors show that neutralisation of DBI by a monoclonal antibody and an active immunization by means of an immunogenic DBI derivative eliciting autoantibodies induce autophagy and lead to metabolic changes that increase starvation-induced weight loss, reduce food intake upon refeeding, and reduce weight gain in response to hypercaloric diets. Accordingly, the present invention relates to methods and pharmaceutical compositions for modulating autophagy based on the modulation of the activity or expression of DBI.
1 .- 27 . (canceled)
28 . A method of stimulating autophagy in a human subject in need thereof, the method comprising administering to the human subject an antibody that binds human extracellular diazepam binding inhibitor (DBI) at a dosage sufficient to block the activity of human extracellular DBI and stimulate autophagy, as determined in an in vitro assay performed on a sample obtained from the human subject,
wherein the administering of the antibody that binds human extracellular DBI does not result in depletion of human intracellular DBI.
29 . The method of claim 28 , wherein the dosage is sufficient to increase microtubule-associated proteins 1A/1B light chain 3B-II (LC3-II) in the human subject, relative to an amount of LC3-II in the human subject prior to the administering, as measured in an in vitro enzyme-linked immunosorbent assay (ELISA).
30 . The method of claim 28 , wherein the suffers from obesity.
31 . The method of claim 28 , wherein the human subject suffers from type 2 diabetes.
32 . The method of claim 28 , wherein the human subject suffers from cancer, neurodegenerative disease, infectious disease, pulmonary disease, cystic fibrosis, liver disease, pancreatitis, or a proteinopathy.
33 . The method of claim 32 , wherein the human subject suffers from cancer and the method further comprises administering a therapeutically effective amount of a chemotherapeutic agent.
34 . The method of claim 28 , wherein the antibody that binds human extracellular DBI is directed against a peptide fragment starting at the amino acid residue at position 43 and ending at the amino acid residue at position 50 of human DBI as set forth in SEQ ID NO: 1.
35 . The method of claim 28 , wherein the antibody that binds human extracellular DBI is a monoclonal chimeric antibody, a monoclonal humanised antibody, or a monoclonal human antibody.
36 . A method of treating a wasting disorder in a human subject in need thereof, the method comprising administering to the human subject a recombinant human diazepam binding inhibitor (DBI) polypeptide at a dosage sufficient to treat the wasting disorder in the human subject.
37 . The method of claim 36 , wherein the human subject is underweight.
38 . The method of claim 37 , wherein the human subject has a BMI of less than 17.5 kg/m 2 .
39 . The method of claim 36 , wherein the wasting disorder is selected from the group consisting of: anorexia, cachexia, anorexia nervosa, cachexia associated with cancer, cachexia associated with AIDS, cachexia associated with heart failure, cachexia associated with cystic fibrosis, cachexia associated with rheumatoid arthritis, cachexia associated with kidney disease, cachexia associated with chronic obstructive pulmonary disease (COPD), cachexia associated with ALS, and cachexia associated with renal failure.
40 . The method of claim 36 , wherein the wasting disorder is anorexia nervosa.
41 . The method of claim 36 , wherein the recombinant DBI polypeptide has i) an amino acid sequence having at least 80% identity with SEQ ID NO: 1, or ii) an amino acid sequence having at least 80% identity with the amino acid sequence ranging from the amino acid residue at position 17 to the amino acid residue at position 50 in SEQ ID NO: 1, or iii) an amino acid sequence having at least 80% identity with the amino acid sequence ranging from the amino acid residue at position 33 to the amino acid residue at position 50 in SEQ ID NO: 1, or iv) an amino acid sequence having at least 80% identity with the amino acid sequence ranging from the amino acid residue at position 43 to the amino acid residue at position 50 in SEQ ID NO: 1.
42 . The method of claim 36 , wherein the administering results in hypoglycemia in the human subject.
43 . The method of claim 36 , wherein the administering results in increased levels of glucose transporter 1 (GLUT1), relative to a level of GLUT1 prior to the administering.
44 . The method of claim 36 , wherein the administering results in increased levels of peroxisome proliferator-activated receptor gamma-7 (PPARG), relative to a level of PPARG prior to the administering.
45 . The method of claim 36 , wherein the administering results in increased levels of lipogenesis, relative to a level of lipogenesis prior to the administering.
46 . The method of claim 36 , wherein the administering results in increased levels of glycolysis, relative to a level of glycolysis prior to the administering.
47 . The method of claim 36 , wherein the administering results in reduced levels of fatty acid oxidation, relative to a level of fatty acid oxidation prior to the administering.