Concentrations of antibodies against β-amyloid 40/42 monomer and oligomers in Chinese intravenous immunoglobulins

Antibody Assay and Anti-Inflammatory Function Evaluation of Therapeutic Potential of Different Intravenous Immunoglobulins for Alzheimer's Disease

Alzheimer's disease (AD) is a common neurodegenerative disease that currently has no known cure. Intravenous immunoglobulin (IVIG), which contains AD-related antibodies and has anti-inflammatory properties, has shown potential as a treatment for AD. However, the efficacy of clinical trials involving AD patients treated with IVIG has been inconsistent. Our previous study found that different IVIGs had significantly varied therapeutic effects on 3xTg-AD mice. In order to investigate the relationship between the composition and function of IVIG and its efficacy in treating AD, we selected three IVIGs that showed notable differences in therapeutic effects. Then, the concentrations of specific antibodies against β-amyloid (Aβ)42, tau, and hyperphosphorylated tau (p-tau) in three IVIGs, as well as their effects on systemic inflammation induced by lipopolysaccharide (LPS) in Balb/c mice, were analyzed and compared in this study. The results indicated that these IVIGs differed greatly in anti-Aβ42/tau antibody concentration and anti-p-tau ratio, and improved LPS-stimulated peripheral inflammation, liver and kidney injury, and neuroinflammation in Balb/c mice to varying degrees. Combined with our previous results, the efficacy of IVIG against AD may be positively correlated with its level of AD-related antibodies and anti-inflammatory ability. AD-related antibody analysis and functional evaluation of IVIG should be given sufficient attention before clinical trials, as this may greatly affect the therapeutic effect of AD treatment.

Effect of Different Aβ Aggregates as Antigen on the Measure of Naturally Occurring Autoantibodies against Amyloid-β40/42 in IVIG

BACKGROUND

The specific Intravenous Immunoglobulin (IVIG) for Alzheimer's Disease (AD) is developing, which contains a high level of naturally occurring autoantibodies against amyloid-β (nAbs-Aβ), and the measure of nAbs-Aβ content is greatly essential. Though Enzyme-Linked Immunosorbent Assay (ELISA) has been widely used in detecting the nAbs-Aβ content, the impact of Aβ aggregates species chosen as antigen in ELISA on this measure has not been evaluated.

OBJECTIVE

To clarify the influence of different Aβ40/42 aggregates as antigen during ELISA on the content of nAbs-Aβ40/42 measured in IVIG.

METHOD

Preparation of various Aβ40/42 aggregates was performed by different aggregation solutions and various lengths of time, and analyzed by western blot. Different Aβ40/42 aggregates as antigen were adopted to measure the nAbs-Aβ40/42 content in IVIG by ELISA, and the control was carried out to reduce interference of nonspecific binding. The Bonferroni and Dunnett's T3 were used for statistical analysis.

RESULTS

The duration for the formation of Aβ40/42 aggregates had more effect on detecting nAbs-Aβ40/42 content in IVIG than the aggregation solution. Higher content of nAbs-Aβ40/42 in the same IVIG was displayed when measured with Aβ40/42 aggregates at day 3, instead of at day 0.5 and day 7.0. The nAbs- Aβ40/42 contents in the same IVIG measured with Aβ40/42 aggregates prepared in different solutions were obviously different, but there was no significant regularity among them.

CONCLUSION

The nAbs-Aβ40/42 content in the same IVIG is significantly different when measured with Aβ40/42 aggregated under different conditions. The nAbs-Aβ40/42 content in IVIG by antigen-dependent measures, like ELISA, is uncertain.

Content of anti-β-amyloid42 oligomers antibodies in multiple batches from different immunoglobulin preparations

Immunoglobulin preparations are one of the promising drugs for Alzheimer's disease (AD). Anti-β-amyloid (Aβ) oligomers antibodies in immunoglobulin preparations are considered to be critical for the therapeutic effect against Alzheimer's disease. However, the antibodies content in immunoglobulin preparations varies greatly. In order to determine which factor contributes to the difference of the antibodies content, the content of anti-Aβ oligomers antibodies in multiple batches of immunoglobulin preparations from two manufacturers were measured by enzyme-linked immunosorbent assay. The results showed that no significant difference was found in the antibodies content among different bathes of normal immunoglobulin preparations prepared by the same process from the same manufacturer, whereas significant difference was found in the antibodies content between normal immunoglobulin preparations prepared by ethanol fractionation and those by chromatography process from the same manufacturer. In addition, significant variation existed in the antibodies content between normal immunoglobulin preparations and specific immunoglobulin preparations that are produced by plasma pool of immunized donors. Based on analysis of these results, the preparation process and raw plasma could be the main contributing factors affecting the content of anti-Aβ oligomers antibodies in immunoglobulin preparations. This finding might help to develop AD-specific immunoglobulin preparation containing higher content of anti-Aβ oligomers antibodies.