Alzheimer Disease: Cao C

Sanchez-Ramos J, Song S, Cao C, Arendash G. · Department of Neurology, University of South Florida, Tampa, FL 33612, USA. · BMC Neurosci. · Pubmed #19090991 links to  free full text

Abstract: There are no effective interventions that significantly forestall or reverse neurodegeneration and cognitive decline in Alzheimer's disease. In the past decade, the generation of new neurons has been recognized to continue throughout adult life in the brain's neurogenic zones. A major challenge has been to find ways to harness the potential of the brain's own neural stem cells to repair or replace injured and dying neurons. The administration of hematopoietic growth factors or cytokines has been shown to promote brain repair by a number of mechanisms, including increased neurogenesis, anti-apoptosis and increased mobilization of bone marrow-derived microglia into brain. In this light, cytokine treatments may provide a new therapeutic approach for many brain disorders, including neurodegenerative diseases like Alzheimer's disease. In addition, neuronal hematopoietic growth factor receptors provide novel targets for the discovery of peptide-mimetic drugs that can forestall or reverse the pathological progression of Alzheimer's disease.

Olcese JM, Cao C, Mori T, Mamcarz MB, Maxwell A, Runfeldt MJ, Wang L, Zhang C, Lin X, Zhang G, Arendash GW. · Florida State University College of Medicine, Tallahassee, FL, USA. · J Pineal Res. · Pubmed #19538338 No free full text.

Abstract: The neurohormone melatonin has been reported to exert anti-beta-amyloid aggregation, antioxidant, and anti-inflammatory actions in various in vitro and animal models. To comprehensively determine the potential for long-term melatonin treatment to protect Alzheimer's transgenic mice against cognitive impairment and development of beta-amyloid (Abeta) neuropathology, we administered melatonin (100 mg/L drinking water) to APP + PS1 double transgenic (Tg) mice from 2-2.5 months of age to their killing at age 7.5 months. A comprehensive behavioral battery administered during the final 6 weeks of treatment revealed that Tg mice given melatonin were protected from cognitive impairment in a variety of tasks of working memory, spatial reference learning/memory, and basic mnemonic function; Tg control mice remained impaired in all of these cognitive tasks/domains. Immunoreactive Abeta deposition was significantly reduced in hippocampus (43%) and entorhinal cortex (37%) of melatonin-treated Tg mice. Although soluble and oligomeric forms of Abeta1-40 and 1-42 were unchanged in the hippocampus and cortex of the same melatonin-treated Tg mice, their plasma Abeta levels were elevated. These Abeta results, together with our concurrent demonstration that melatonin suppresses Abeta aggregation in brain homogenates, are consistent with a melatonin-facilitated removal of Abeta from the brain. Inflammatory cytokines such as tumor necrosis factor (TNF)-alpha were decreased in hippocampus (but not plasma) of Tg+ melatonin mice. Finally, the cortical mRNA expression of three antioxidant enzymes (SOD-1, glutathione peroxidase, and catalase) was significantly reduced to non-Tg levels by long-term melatonin treatment in Tg mice. Thus, melatonin's cognitive benefits could involve its anti-Abeta aggregation, anti-inflammatory, and/or antioxidant properties. Our findings provide support for long-term melatonin therapy as a primary or complementary strategy for abating the progression of Alzheimer disease.

Cao C, Arendash GW, Dickson A, Mamcarz MB, Lin X, Ethell DW. · The Johnnie B. Byrd Sr. Alzheimer's Center and Research Institute, Tampa, FL 33613, USA. · Neurobiol Dis. · Pubmed #19167499 No free full text.

Abstract: We have found that a small number of purified Th2-biased Abeta-specific T cells are sufficient to provide profound cognitive and pathological benefits in an APP+PS1 mouse model for Alzheimer's disease. Six weeks after receiving T cell infusions, cognitively-impaired mice performed significantly better in working memory tasks, which correlated with higher plasma levels of soluble Abeta. Pathological analysis of the hippocampus revealed a 30% decrease of plaque-associated microglia and less vascular amyloidosis in T cell treated mice. The infusion of Abeta-specific Th2 cells also reduced plasma levels of IFN-gamma, TNF-alpha, GM-CSF, IL-2 and IL-4, which are elevated in untreated APP+PS1 mice. No significant immune cell infiltration and no anti-Abeta antibody titers occurred in the T cell treated mice. These results demonstrate that Abeta-specific Th2 cells are sufficient to reverse cognitive impairment and provide multiple pathological benefits in an Alzheimer's mouse model.

Cao C, Lin X, Zhang C, Wahi MM, Wefes I, Arendash G, Potter H. · Johnnie B. Byrd, Sr., Alzheimer's Center and Research Institute, 4001 East Fletcher Avenue, Tampa, FL 33613, United States. · J Neuroimmunol. · Pubmed #18649951 No free full text.

Abstract: Vaccines using bone marrow-derived dendritic cells (DCs) sensitized to Abeta 1-42 peptide and other mutant peptides were tested on BALB/c and APP(SW) transgenic mice. Wild type Abeta 1-42-sensitized DC vaccine (DCSV) produced no response, but all peptides with a T-cell epitope mutation induced antibody responses without inflammation. DCSV with Abeta 1-25 peptide with mutated T-cell epitope failed to induce antibody response, while DCSV with Abeta 1-35 with mutated T-cell epitope produced a strong antibody response. The entire T-cell epitope is required in a DC vaccine to induce antibody response. DCSV with Abeta peptide carrying the entire mutant T-cell epitope may be an appropriate vaccine against AD.

Cao C, Lin X, Wahi MM, Jackson EA, Potter H. · Johnnie B, Byrd Alzheimer's Center and Research Institute, 4001 E, Fletcher Ave,, Third Floor, Tampa, FL 33613, USA. · BMC Neurosci. · Pubmed #18282292 links to  free full text

Abstract: BACKGROUND: A recent human clinical trial of an Alzheimer's disease (AD) vaccine using amyloid beta (Abeta) 1-42 plus QS-21 adjuvant produced some positive results, but was halted due to meningoencephalitis in some participants. The development of a vaccine with mutant Abeta peptides that avoids the use of an adjuvant may result in an effective and safer human vaccine. RESULTS: All peptides tested showed high antibody responses, were long-lasting, and demonstrated good memory response. Epitope mapping indicated that peptide mutation did not lead to epitope switching. Mutant peptides induced different inflammation responses as evidenced by cytokine profiles. Ig isotyping indicated that adjuvant-free vaccination with peptides drove an adequate Th2 response. All anti-sera from vaccinated mice cross-reacted with human Abeta in APP/PS1 transgenic mouse brain tissue. CONCLUSION: Our study demonstrated that an adjuvant-free vaccine with different Abeta peptides can be an effective and safe vaccination approach against AD. This study represents the first report of adjuvant-free vaccines utilizing Abeta peptides carrying diverse mutations in the T-cell epitope. These largely positive results provide encouragement for the future of the development of human vaccinations for AD.

Ethell DW, Shippy D, Cao C, Cracchiolo JR, Runfeldt M, Blake B, Arendash GW. · Biomedical Sciences, University of California Riverside, 92521-0121, USA. · Neurobiol Dis. · Pubmed #16733088 No free full text.

Abstract: Active and passive Abeta immunotherapy provide behavioral benefits in AD transgenic mice, but they can also induce adverse immune over-activation and neuropathological effects. Here, we show that a restricted Abeta-specific immune re-activation can provide cognitive and pathological benefits to APPsw + PS1 transgenic mice for at least 2 1/2 months. A single infusion of Abeta-specific immune cells from Abeta-vaccinated littermates improved performance in cognitively impaired APP + PS1 mice. Recipients had lower levels of soluble Abeta in the hippocampus, less plaque-associated microglia, and more intense synaptophysin immunoreactivity, compared with untreated controls. However, Abeta-specific infusates enriched for Th1 or depleted of CD4(+) T-cells were not effective, nor were ovalbumin-specific infusates. These benefits occurred without global or brain-specific inflammatory responses. Chronically high levels of Abeta can cause immune tolerance, hypo-responsiveness, or anergy to Abeta, but our findings demonstrate that Abeta-specific immune cells can resume endogenous Abeta-lowering processes and may be an effective Abeta therapeutic.