Vaccinations with amyloid-beta peptide (A beta) can dramatically reduce amyloid deposition in a transgenic mouse model of Alzheimer's disease. To determine if the vaccinations had deleterious or beneficial functional consequences, we tested eight months of A beta vaccination in a different transgenic model for Alzheimer's disease in which mice develop learning deficits as amyloid accumulates. Here we show that vaccination with A beta protects transgenic mice from the learning and age-related memory deficits that normally occur in this mouse model for Alzheimer's disease. During testing for potential deleterious effects of the vaccine, all mice performed superbly on the radial-arm water-maze test of working memory. Later, at an age when untreated transgenic mice show memory deficits, the A beta-vaccinated transgenic mice showed cognitive performance superior to that of the control transgenic mice and, ultimately, performed as well as nontransgenic mice. The A beta-vaccinated mice also had a partial reduction in amyloid burden at the end of the study. This therapeutic approach may thus prevent and, possibly, treat Alzheimer's dementia.

Proteolysis of the hyalectans (aggrecan, versican, brevican) in vivo appears to result from the activity of ADAMTS4 (aggrecanase-1, herein referred to as an hyalectanase). To examine the mode of activation of AD-AMTS4, a human chondrosarcoma cell line, JJ012, has been stably transfected with the full-length c-DNA for human ADAMTS4. The cells synthesized a high molecular weight form of the enzyme (p100), which in serumfree culture was processed to three truncated forms, p75, p60, and p50. Treatment of the p100 form with recombinant furin indicated that the p75 form is generated by the removal of the prodomain by a furin-like activity. Analysis with domain-specific antisera showed that the p60 and p50 forms are generated by C-terminal truncation of the p75 form. The appearance of the p60 and p50 forms in culture medium was prevented by inclusion of a furin inhibitor, inhibitors of glycosylphosphatidylinositol synthesis, glucosamine, a hydroxamate-based matrix metalloproteinase (MMP) inhibitor, and TIMP-1, but not by AEBSF (4-(2-aminoethyl)benzenesulfonyl fluoride) or E64. Only medium samples containing the p60/p50 forms exhibited aggrecanase activity, and isolation of the p75, p60, and p50 forms by preparative SDS-PAGE showed that only p60 and p50 were active in aggrecanase and versicanase assays. Pig synovium and human cartilages also contained AD-AMTS4 in the p75, p60, and p50 forms. We suggest that in vivo production of proteolytically active ADAMTS4 requires not only removal of the prodomain by a furin-like activity but also MMP-mediated removal of a portion of the C-terminal spacer domain.Aggrecan, versican, neurocan, and brevican are components of the extracellular matrix (ECM) 1 in a wide range of tissues. They are all members of the family of large aggregating proteoglycans (1), which are characterized by an N-terminal globular domain that binds to hyaluronan. They have therefore been included, along with related species such as link protein and CD44, in the molecular grouping termed hyaladherins (2). At the same time they are all synthesized with a C-terminal globular domain that is related structurally to selectins, consisting of a C-type lectin domain flanked by epidermal growth factor and complement regulatory protein domains. Because of this structural feature they have also been given the family name of lecticans (3). In an attempt to accommodate the functionality of both the N-terminal and C-terminal globular domains, and also to indicate their proteoglycan nature, the group has also been termed the hyalectans (4).Proteolytic degradation of the hyalectans in the ECM appears to result from the activity of a subgroup of the ADAMTS family of metalloproteinases, all of which exhibit some degree of glutamyl-endopeptidase activity for specific Glu-X bonds (where X is most often Ala or Gly) in these glycosaminoglycansubstituted substrates. Thus, ADAMTS1, -4, and -5 exhibit "aggrecanase" activity (5-7), ADAMTS1 and -4 exhibit "versicanase" activity (8), and ADAMTS4 exhibits "brevicanase" activity (9). Among...

Systemic administration of anti-amyloid-␤ (A␤) antibodies results in reduced parenchymal amyloid but increased vascular amyloid and microhemorrhage in amyloid precursor protein (APP) transgenic mice. Here, we evaluate the effects of reducing effector interactions of the antibody via deglycosylation. Mice aged 20 months were treated weekly for 4 months and tested behaviorally before they were killed. APP transgenic mice receiving either anti-A␤ (2H6) or deglycosylated anti-A␤ (de-2H6) showed significant improvement in radial arm water maze performance compared with mice receiving a control antibody. Both groups receiving anti-A␤ antibodies showed significant reductions in total A␤ immunochemistry and Congo red. Significantly fewer vascular amyloid deposits and microhemorrhages were observed in mice administered the de-2H6 antibody compared with those receiving unmodified 2H6 antibody. Deglycosylated anti-A␤ antibodies may be preferable to unmodified IgG because they retain the cognition-enhancing and amyloid-reducing properties of anti-A␤ immunotherapy, while greatly attenuating the increased vascular amyloid deposition and microhemorrhage observed with unmodified IgG.

A major question for gene therapy in brain concerns methods to administer therapeutic genes in a uniform manner over major portions of the brain. A second question in neuroimmunology concerns the extent to which monocytes migrate to the CNS in degenerative disorders. Here we show that CD11bϩ cells (largely monocytes) isolated from the bone marrow of GFP (green fluorescent protein)-expressing donors spontaneously home to compacted amyloid plaques in the brain. Injections of these cells as a single pulse show a rapid clearance from circulation (90 min half-life) and tissue residence half-lives of ϳ3 d. The uptake into brain was minimal in nontransgenic mice. In transgenic mice containing amyloid deposits, uptake was dramatically increased and associated with a corresponding decrease in monocyte uptake into peripheral organs comparedtonontransgeniclittermates.TwiceweeklyinfusionsoftheCD11bϩbonemarrowcellstransfectedwithageneticallyengineeredform of the protease neprilysin completely arrest amyloid deposition in an aggressively depositing transgenic model. Exploiting the natural homing properties of peripherally derived blood cells to deliver therapeutic genes has the advantages of access to the entire CNS, expression largely restricted to sites of injury, low risk of immune reactivity, and fading of expression if adverse reactions are encountered. These observations support the feasibility of testing autologous monocytes for application of therapeutic genes in human CNS disease. Moreover, these data support the results from bone marrow grafts that circulating CD11bϩ cells can enter the CNS without requiring the use of lethal irradiation.

Intravenous administration of recombinant human interleukin 1 beta (IL-1 beta, 1 micrograms/100 g body wt) resulted in a marked elevation of plasma adrenocorticotropic hormone (ACTH) levels, with peak levels at 10 min, in conscious unrestrained rats. One week after the placement of a lesion by radiofrequency or microinjection of kainic acid in the organum vasculosum of lamina terminalis (OVLT) but not in subfornical organ, ACTH response to intravenous IL-1 beta was enhanced, whereas both radiofrequency-induced lesion and kainic acid in the preoptic area (POA) suppressed the response. Indomethacin or a prostaglandin E (PGE) antagonist microinjected into the OVLT or POA suppressed or abolished the response. On the other hand, PGE, but not PGD2, microinjected into the POA increased plasma ACTH levels. These results suggest an important role for the OVLT, which lacks blood-brain barrier, as a possible site of entry of blood-borne IL-1 beta into the brain and for the POA, which may contain the neurons required for the response. Involvement of PGE in the OVLT and POA in the ACTH response to intravenous IL-1 beta is also suggested.