Neuroprotective effects of the amylin analogue pramlintide on Alzheimer's disease pathogenesis and cognition.

Amylin is a metabolic peptide hormone that is co-secreted with insulin from beta cells in the pancreas and activates many of the downstream targets of insulin. To investigate the relationship between this hormone and Alzheimer's disease (AD), we measured plasma human amylin levels in 206 subjects with AD, 64 subjects with mild cognitive impairment, and 111 subjects with no cognitive impairment and found significantly lower amylin levels among subjects with AD and mild cognitive impairment compared with the cognitively intact subjects. To investigate mechanisms underlying amylin's effects in the brain, we administered chronic infusions of the amylin analog pramlintide in the senescence-accelerated prone mouse, a mouse model of sporadic AD. Pramlintide administration improved performance in the novel object recognition task, a validated test of memory and cognition. The pramlintide-treated mice had increased expression of the synaptic marker synapsin I and the kinase cyclin-dependent kinase-5 in the hippocampus, as well as decreased oxidative stress and inflammatory markers in the hippocampus. A dose-dependent increase in cyclin-dependent kinase-5 and activation of extracellular-signal-regulated-kinases 1/2 by pramlintide treatment in vitro was also present indicating functionality of the amylin receptor in neurons. Together these results suggest that amylin analogs have neuroprotective properties and might be of therapeutic benefit in AD.

Optimization of phage-immobilized ELISA for autoantibody profiling in human sera.

Phage libraries displaying cDNA or random peptides have been used for profiling autoantibodies in cancer. The detection of autoantibodies in human sera using phages displaying specific epitopes is usually performed by phage-immobilized ELISAs which can detect specific antibodies without identification of whole antigens. However, these ELISAs can give feeble detection signals that are indistinguishable from background signals which are caused by human sera. To improve the usefulness of phage ELISA for human sera, the conditions for each step in phage ELISA were optimized. The antigenicity of phage antigens was maximal when using coating buffer of neutral pH. By using protein-free blocking buffer and pre-adsorbing human sera with phage host cell ER2738 extracts significantly decreased non-specific signals. Finally, when these conditions were applied to phage ELISA using K10P1, the values of the negative controls were concentrated near cutoff values, which made the assay more reliable. The optimized phage ELISA conditions described here would increase the efficacy of detection specific autoantibodies in human sera.