Prevention of autoimmune diabetes in nonobese diabetic female mice by treatment with recombinant glutamic acid decarboxylase (GAD 65).
The nonobese diabetic (NOD) mouse spontaneously develops insulin-dependent diabetes (IDDM or type I diabetes), resulting from T-lymphocyte-mediated destruction of pancreatic beta cells. This autoimmune phenomenon includes mononuclear cell infiltration of the islets of Langerhans (insulitis) and the presence of circulating autoantibodies. The specificity of the autoantibodies and of the autoreactive T cells was investigated and several autoantigens were proposed, in particular glutamic acid decarboxylase (GAD). This enzyme exists in two forms (GAD 65 and GAD 67) encoded by two independent genes. To explain the role of GAD in type I diabetes, we prepared recombinant rat GAD 65 as fusion protein, produced in an Escherichia coli expression system, and we treated NOD female mice from 4 to 7 weeks of age by repeated intraperitoneal injections of 5 micrograms fusion protein (3 injections per week); control groups received the fusion partner, maltose binding protein (MBP) or dissolving agent (NaCl 0.9%). We investigated two parameters, the degree of insulitis 5 weeks after the last injection and the overall incidence of the disease. Histological examination of the pancreata from GAD-treated mice revealed a significant reduction in the severity of insulitis compared with the two control groups. Furthermore, we observed that the time of onset and the frequency of diabetes in NOD females injected with GAD fusion protein differed significantly from the control groups receiving MBP or NaCl (P < 0.0001). These results show that a 3-week treatment of NOD female mice starting at 4 weeks of age protects them from diabetes, again emphasizing the crucial role of GAD as autoantigen in type I diabetes.
Pleau
J M
JM
Université René Descartes, Paris V, CNRS URA 1461, Hôpital Necker, France.
Fernandez-Saravia
F
F
Esling
A
A
Homo-Delarche
F
F
Dardenne
M
M
D018528:ATP-Binding Cassette Transporters; D000367:Age Factors; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000201:enzymology; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics; D003922:Diabetes Mellitus, Type 1 / Q000473:pathology / Q000517:prevention & control*; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D005260:Female; D005968:Glutamate Decarboxylase / Q000008:administration & dosage / Q000096:biosynthesis / Q000235:genetics / Q000627:therapeutic use*; D007108:Immune Tolerance; D015994:Incidence; D007274:Injections, Intraperitoneal; D007527:Isoenzymes / Q000008:administration & dosage / Q000096:biosynthesis / Q000235:genetics / Q000627:therapeutic use*; D058619:Maltose-Binding Proteins; D051379:Mice; D016688:Mice, Inbred NOD; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins; D010195:Pancreatitis / Q000473:pathology / Q000517:prevention & control*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage / Q000096:biosynthesis / Q000627:therapeutic use
D018528:ATP-Binding Cassette Transporters; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D007527:Isoenzymes; D058619:Maltose-Binding Proteins; D009004:Monosaccharide Transport Proteins; D011993:Recombinant Fusion Proteins; C461599:maltose transport system, E coli; D005968:Glutamate Decarboxylase