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Active immunization against complement factor C5a: a new therapeutic approach for Alzheimer's disease.

Landlinger C, Oberleitner L, Gruber P, Noiges B, Yatsyk K, Santic R, Mandler M, Staffler G - J Neuroinflammation (2015)

Bottom Line: Especially, complement factor C5a and its receptor have been found to be up-regulated in microglia in the immediate surroundings of cerebral amyloid plaques and blocking of C5aR resulted in a reduction of pathological markers in a model of AD.Both C5a-targeting vaccines were highly immunogenic and induced sustained antibody titers against C5a.C5a-peptide vaccines represent a safe and well-tolerated immunotherapy, which is able to induce a strong and specific immune response against the pro-inflammatory molecule C5a.

View Article: PubMed Central - PubMed

Affiliation: AFFiRiS AG, Karl-Farkas-Gasse 22, Vienna, 1030, Austria. christine.landlinger@affiris.com.

ABSTRACT

Background: Alzheimer's disease (AD) is the most common neurodegenerative disease characterized by neuronal loss due to amyloid beta aggregations, neurofibrillary tangles, and prominent neuroinflammation. Recently, interference with neuroinflammation as a new therapeutic approach for AD treatment gained great interest. Microglia cells, one of the major contributors in neuroinflammation, are activated in response to misfolded proteins such as amyloid β and cell debris leading to a sustained release of pro-inflammatory mediators. Especially, complement factor C5a and its receptor have been found to be up-regulated in microglia in the immediate surroundings of cerebral amyloid plaques and blocking of C5aR resulted in a reduction of pathological markers in a model of AD. Here, we investigate the effect of active vaccination against the complement factor C5a to interfere with neuroinflammation and neuropathologic alterations in a mouse model of AD.

Methods: Short antigenic peptides AFF1 and AFF2, which mimic a C-terminal epitope of C5a, were selected and formulated to vaccines. These vaccines are able to induce a highly specific antibody response to the target protein C5a. Tg2576 mice, a common model of AD, were immunized with these two C5a-peptide vaccines and the induced immune response toward C5a was analyzed by ELISA and Western blot analysis. The influence on memory retention was assessed by a contextual fear conditioning test. Microglia activation and amyloid plaque deposition in the brain was visualized by immunohistochemistry.

Results: Both C5a-targeting vaccines were highly immunogenic and induced sustained antibody titers against C5a. Tg2576 mice vaccinated at early stages of the disease showed significantly improved contextual memory accompanied by the reduction of microglia activation in the hippocampus and cerebral amyloid plaque load compared to control mice. Late-stage immunization also showed a decrease in the number of activated microglia, and improved memory function, however, had no influence on the amyloid β load.

Conclusion: C5a-peptide vaccines represent a safe and well-tolerated immunotherapy, which is able to induce a strong and specific immune response against the pro-inflammatory molecule C5a. In a mouse model of AD, C5a-peptide vaccines reduce microglia activation and thus neuroinflammation, which is supposed to lead to reduced neuronal dysfunction and AD symptomatic decline.

No MeSH data available.


Related in: MedlinePlus

Contextual memory is significantly improved following C5a-peptide vaccination. A CFC test was performed with AFF1 (n = 23), AFF2 (n = 23), and control (n = 14) immunized Tg2576 mice, as well as wt littermates (n = 12), all at the age of 15 months. Mice were exposed to electric foot shocks and the memory to recall these shocks was assessed by the percent time freezing in a 2-min interval. Bars represent the group means ± SEM of n animals. The p value was determined using one-way ANOVA test followed by a Dunn’s multiple comparison Test (non-parametric test). The p values are expressed as *p < 0.05 and **p < 0.01
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Fig5: Contextual memory is significantly improved following C5a-peptide vaccination. A CFC test was performed with AFF1 (n = 23), AFF2 (n = 23), and control (n = 14) immunized Tg2576 mice, as well as wt littermates (n = 12), all at the age of 15 months. Mice were exposed to electric foot shocks and the memory to recall these shocks was assessed by the percent time freezing in a 2-min interval. Bars represent the group means ± SEM of n animals. The p value was determined using one-way ANOVA test followed by a Dunn’s multiple comparison Test (non-parametric test). The p values are expressed as *p < 0.05 and **p < 0.01

Mentions: In a first set of experiments, anti-C5a immunization of Tg2576 mice by AFF1- and AFF2-containing vaccines was started at the age of 8 months, where first memory deficits are reported to become apparent in this model, but amyloid plaques in the brain are not yet present. A contextual fear conditioning test was performed at the age of 15 months in order to investigate the impact of C5a-targeting vaccines on the progression of AD-like cognitive decline. The time freezing was used to measure mice’s ability to recall the shocks they received on the previous day. Both AFF1- and AFF2-vaccinated mice showed significantly increased memory retention with 32 and 27 % time freezing, respectively, whereas control-treated mice spent only 10 % time freezing indicating an almost complete loss of contextual learning and memory (Fig. 5). However, vaccination was not able to restore the contextual learning and memory conditions which were found in untreated wt littermates (47 % time freezing) (Fig. 5). Non-AD wt littermates have not been included in this study. To evaluate that the memory improvements in AFF1- and AFF2-vaccinated Tg2576 mice can be attributed to the neutralization of excessive C5a which was provoked by the APP transgene, an independent control experiment was performed. Wt mice were immunized 4 times with AFF1 and AFF2 vaccines and tested for memory retention by a contextual fear conditioning test. No differences between the control and the C5a-AFFITOPE®-immunized mice were found as already shown in Fig. 2a.Fig. 5


Active immunization against complement factor C5a: a new therapeutic approach for Alzheimer's disease.

Landlinger C, Oberleitner L, Gruber P, Noiges B, Yatsyk K, Santic R, Mandler M, Staffler G - J Neuroinflammation (2015)

Contextual memory is significantly improved following C5a-peptide vaccination. A CFC test was performed with AFF1 (n = 23), AFF2 (n = 23), and control (n = 14) immunized Tg2576 mice, as well as wt littermates (n = 12), all at the age of 15 months. Mice were exposed to electric foot shocks and the memory to recall these shocks was assessed by the percent time freezing in a 2-min interval. Bars represent the group means ± SEM of n animals. The p value was determined using one-way ANOVA test followed by a Dunn’s multiple comparison Test (non-parametric test). The p values are expressed as *p < 0.05 and **p < 0.01
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4537556&req=5

Fig5: Contextual memory is significantly improved following C5a-peptide vaccination. A CFC test was performed with AFF1 (n = 23), AFF2 (n = 23), and control (n = 14) immunized Tg2576 mice, as well as wt littermates (n = 12), all at the age of 15 months. Mice were exposed to electric foot shocks and the memory to recall these shocks was assessed by the percent time freezing in a 2-min interval. Bars represent the group means ± SEM of n animals. The p value was determined using one-way ANOVA test followed by a Dunn’s multiple comparison Test (non-parametric test). The p values are expressed as *p < 0.05 and **p < 0.01
Mentions: In a first set of experiments, anti-C5a immunization of Tg2576 mice by AFF1- and AFF2-containing vaccines was started at the age of 8 months, where first memory deficits are reported to become apparent in this model, but amyloid plaques in the brain are not yet present. A contextual fear conditioning test was performed at the age of 15 months in order to investigate the impact of C5a-targeting vaccines on the progression of AD-like cognitive decline. The time freezing was used to measure mice’s ability to recall the shocks they received on the previous day. Both AFF1- and AFF2-vaccinated mice showed significantly increased memory retention with 32 and 27 % time freezing, respectively, whereas control-treated mice spent only 10 % time freezing indicating an almost complete loss of contextual learning and memory (Fig. 5). However, vaccination was not able to restore the contextual learning and memory conditions which were found in untreated wt littermates (47 % time freezing) (Fig. 5). Non-AD wt littermates have not been included in this study. To evaluate that the memory improvements in AFF1- and AFF2-vaccinated Tg2576 mice can be attributed to the neutralization of excessive C5a which was provoked by the APP transgene, an independent control experiment was performed. Wt mice were immunized 4 times with AFF1 and AFF2 vaccines and tested for memory retention by a contextual fear conditioning test. No differences between the control and the C5a-AFFITOPE®-immunized mice were found as already shown in Fig. 2a.Fig. 5

Bottom Line: Especially, complement factor C5a and its receptor have been found to be up-regulated in microglia in the immediate surroundings of cerebral amyloid plaques and blocking of C5aR resulted in a reduction of pathological markers in a model of AD.Both C5a-targeting vaccines were highly immunogenic and induced sustained antibody titers against C5a.C5a-peptide vaccines represent a safe and well-tolerated immunotherapy, which is able to induce a strong and specific immune response against the pro-inflammatory molecule C5a.

View Article: PubMed Central - PubMed

Affiliation: AFFiRiS AG, Karl-Farkas-Gasse 22, Vienna, 1030, Austria. christine.landlinger@affiris.com.

ABSTRACT

Background: Alzheimer's disease (AD) is the most common neurodegenerative disease characterized by neuronal loss due to amyloid beta aggregations, neurofibrillary tangles, and prominent neuroinflammation. Recently, interference with neuroinflammation as a new therapeutic approach for AD treatment gained great interest. Microglia cells, one of the major contributors in neuroinflammation, are activated in response to misfolded proteins such as amyloid β and cell debris leading to a sustained release of pro-inflammatory mediators. Especially, complement factor C5a and its receptor have been found to be up-regulated in microglia in the immediate surroundings of cerebral amyloid plaques and blocking of C5aR resulted in a reduction of pathological markers in a model of AD. Here, we investigate the effect of active vaccination against the complement factor C5a to interfere with neuroinflammation and neuropathologic alterations in a mouse model of AD.

Methods: Short antigenic peptides AFF1 and AFF2, which mimic a C-terminal epitope of C5a, were selected and formulated to vaccines. These vaccines are able to induce a highly specific antibody response to the target protein C5a. Tg2576 mice, a common model of AD, were immunized with these two C5a-peptide vaccines and the induced immune response toward C5a was analyzed by ELISA and Western blot analysis. The influence on memory retention was assessed by a contextual fear conditioning test. Microglia activation and amyloid plaque deposition in the brain was visualized by immunohistochemistry.

Results: Both C5a-targeting vaccines were highly immunogenic and induced sustained antibody titers against C5a. Tg2576 mice vaccinated at early stages of the disease showed significantly improved contextual memory accompanied by the reduction of microglia activation in the hippocampus and cerebral amyloid plaque load compared to control mice. Late-stage immunization also showed a decrease in the number of activated microglia, and improved memory function, however, had no influence on the amyloid β load.

Conclusion: C5a-peptide vaccines represent a safe and well-tolerated immunotherapy, which is able to induce a strong and specific immune response against the pro-inflammatory molecule C5a. In a mouse model of AD, C5a-peptide vaccines reduce microglia activation and thus neuroinflammation, which is supposed to lead to reduced neuronal dysfunction and AD symptomatic decline.

No MeSH data available.


Related in: MedlinePlus