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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

Wt mice treated with C5a-peptide vaccines show normal contextual learning and memory skills and are healthy with normal motor and sensor function. 129S6 wt mice immunized with AFF1- (n = 12) and AFF2- (n = 12) containing vaccines were compared to vehicle immunized mice (n = 12) for a contextual memory function using a contextual fear conditioning test, b general health status, c body weight, d sensory functions, and e motor functions using the modified SHIRPA test. All tests were performed at the age of 15 months. Bars represent the group means ± SEM of n animals
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Fig2: Wt mice treated with C5a-peptide vaccines show normal contextual learning and memory skills and are healthy with normal motor and sensor function. 129S6 wt mice immunized with AFF1- (n = 12) and AFF2- (n = 12) containing vaccines were compared to vehicle immunized mice (n = 12) for a contextual memory function using a contextual fear conditioning test, b general health status, c body weight, d sensory functions, and e motor functions using the modified SHIRPA test. All tests were performed at the age of 15 months. Bars represent the group means ± SEM of n animals

Mentions: Before testing the C5a-peptide vaccines for their efficacy in a mouse model of AD, we investigated whether these vaccines had any effect on the contextual learning and memory in 129S6 wt mice by using the contextual fear conditioning test. After four immunizations, no differences between the control and the C5a-AFFITOPE® immunized mice were observed all showing around 60 % time freezing within a 2-min period of analysis (Fig. 2a). Furthermore, potential side effects of the vaccines were evaluated by a modified SHIRPA test including general health, muscle, and sensory functions. C5a-peptide and vehicle-immunized 129S6 wt mice were all healthy (Fig. 2b), had comparable body weight (Fig. 2c), and no abnormalities in sensory and motor functions were observed (Fig. 2d, e). In addition, different safety parameters were elucidated by in silico analyses. The absence of target-specific T cell response and cross-reactivity of vaccine-induced antibodies to other endogenous proteins are a prerequisite for an immunotherapy against self-proteins in order to avoid the risk of autoimmunity. In silico analysis by online available T cell epitope prediction algorithms (e.g., http://www.syfpeithi.de or http://www.iedb.org/counts.php) did not predict any relevant T cell epitope for the peptides AFF1 and AFF2. Potential cross-reactivity of the AFF1- and AFF2-induced antibodies to other proteins was evaluated by BLAST searches against the murine proteome. AFF1 did not show any relevant homology to other murine proteins. For AFF2, a homology of 6 amino acids to FYN binding protein was found, however, based on its intracellular location, it is not anticipated to be accessible for antibody binding.Fig. 2


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)

Wt mice treated with C5a-peptide vaccines show normal contextual learning and memory skills and are healthy with normal motor and sensor function. 129S6 wt mice immunized with AFF1- (n = 12) and AFF2- (n = 12) containing vaccines were compared to vehicle immunized mice (n = 12) for a contextual memory function using a contextual fear conditioning test, b general health status, c body weight, d sensory functions, and e motor functions using the modified SHIRPA test. All tests were performed at the age of 15 months. Bars represent the group means ± SEM of n animals
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig2: Wt mice treated with C5a-peptide vaccines show normal contextual learning and memory skills and are healthy with normal motor and sensor function. 129S6 wt mice immunized with AFF1- (n = 12) and AFF2- (n = 12) containing vaccines were compared to vehicle immunized mice (n = 12) for a contextual memory function using a contextual fear conditioning test, b general health status, c body weight, d sensory functions, and e motor functions using the modified SHIRPA test. All tests were performed at the age of 15 months. Bars represent the group means ± SEM of n animals
Mentions: Before testing the C5a-peptide vaccines for their efficacy in a mouse model of AD, we investigated whether these vaccines had any effect on the contextual learning and memory in 129S6 wt mice by using the contextual fear conditioning test. After four immunizations, no differences between the control and the C5a-AFFITOPE® immunized mice were observed all showing around 60 % time freezing within a 2-min period of analysis (Fig. 2a). Furthermore, potential side effects of the vaccines were evaluated by a modified SHIRPA test including general health, muscle, and sensory functions. C5a-peptide and vehicle-immunized 129S6 wt mice were all healthy (Fig. 2b), had comparable body weight (Fig. 2c), and no abnormalities in sensory and motor functions were observed (Fig. 2d, e). In addition, different safety parameters were elucidated by in silico analyses. The absence of target-specific T cell response and cross-reactivity of vaccine-induced antibodies to other endogenous proteins are a prerequisite for an immunotherapy against self-proteins in order to avoid the risk of autoimmunity. In silico analysis by online available T cell epitope prediction algorithms (e.g., http://www.syfpeithi.de or http://www.iedb.org/counts.php) did not predict any relevant T cell epitope for the peptides AFF1 and AFF2. Potential cross-reactivity of the AFF1- and AFF2-induced antibodies to other proteins was evaluated by BLAST searches against the murine proteome. AFF1 did not show any relevant homology to other murine proteins. For AFF2, a homology of 6 amino acids to FYN binding protein was found, however, based on its intracellular location, it is not anticipated to be accessible for antibody binding.Fig. 2

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