Projects / Programmes
Development of NOD2 agonists and dual NOD2/TLR7 agonistic conjugates as novel vaccine adjuvants
| Code |
Science |
Field |
Subfield |
| 3.01.00 |
Medical sciences |
Microbiology and immunology |
|
| Code |
Science |
Field |
| B740 |
Biomedical sciences |
Pharmacological sciences, pharmacognosy, pharmacy, toxicology |
| Code |
Science |
Field |
| 3.01 |
Medical and Health Sciences |
Basic medicine |
adjuvants, NOD2 agonists, NOD2/TLR7 conjugates, structure-based design, liposomes, homology modeling
Researchers (15)
Organisations (2)
Abstract
Currently, our world is facing an acute shortage of novel vaccine adjuvants. Adjuvants enhance the immunogenicity of vaccines, therefore they constitute essential components of vaccines. They are needed not only to increase the magnitude of the response but also to guide the type of response to produce the most effective type of immunity against distinct pathogens/tumors. The recent progress in our understanding of innate immunity and its potential for tailoring adaptive immunity has opened up new avenues for vaccine development. Pattern recognition receptors (PRRs) are evolutionarily conserved innate immune sensors that orchestrate the initial defense response as part of the innate immune process. Nucleotide-binding oligomerization domain-containing protein 2 (NOD2), that belongs to a cytosolic class of PRRs, the NOD-like receptors (NLR), plays a key role in both innate as well as adaptive immunity. Muramyl dipeptide (MDP) is the smallest structural subunit of bacterial peptidoglycan capable of eliciting NOD2 activation, and known as an effective adjuvant, however its use has been abandoned due to several drawbacks (rapid elimination, low absorption and pyrogenicity). Up until now, structure-based design has not been used in the discovery of NOD2 ligands. The crystal structure of rabbit NOD2 was only recently determined and a hydrophobic pocket proposed as a potential MDP-binding site. Moreover, the homology model of human NOD2, which would allow for structure-based design of NOD2 ligands as well as screening for non-peptide fragments with high binding affinity, has yet to be constructed. Thus, no small molecule NOD2 agonists of non-peptide nature have been reported. Desmuramylpeptides are MDP derivatives lacking the sugar N-acetylmuramyl moiety (MurNAc). Our past work established the essential structural requirements of desmuramylpeptides for achieving NOD2 agonistic activity, identifying trans-feruloyl moiety as an excellent MurNAc mimetic. Although our best compound was twice as potent as MDP in vitro, it proved to be a weaker adjuvant in vivo, due to ester hydrolysis, affording free acid, a much weaker NOD2 agonist. While activation of NOD2 itself is sufficient to shape adaptive immune responses, more importantly, NOD2 agonists synergistically amplify the adjuvant potential of other PRR ligands such as Toll-like receptor (TLR) ligands and alters the magnitude, persistence and the type of response.
A critical research goal is to develop innovative new adjuvants capable of enhancing the immunogenicity of different vaccines. In the scope of this project, we will design and prepare novel NOD2 agonists and chimeric NOD2/TLR7 agonistic conjugates and their liposomal formulations with in vivo adjuvant activities. First, we will construct a homology model of human NOD2 based on the reported NOD2 crystal structure, which will then be used in structure-based design and virtual screening. The major drawbacks of previously synthesized molecules are the in vivo metabolic instability of the ethyl ester group and low permeation capacity. To remedy these issues, our work will focus on the development of more lipophilic and metabolically more stable NOD2 agonists incorporating ester bioisosteres and lipophilic moieties to improve permeation. Since nobody has raised the question of whether there is possible favourable synergy between NOD2 and TLR7 agonists in terms of potency of adjuvant activity and the type of induced response, chimeric NOD2/TLR7 agonistic conjugates will be designed by covalently linking our NOD2 agonists to known TLR7 agonists, affording innovative adjuvants. Finally, liposomal vaccines have successfully been used as carriers of antigens and adjuvants. Specifically, they were recognized as ideal carriers for MDP and its derivatives by promoting potent cellular response and improving compound stability against enzymatic stress, thus we aim to exploit them and improve the in vivo bioavailability of our compounds.
Significance for science
Relevance and potential impact of the results. Development of tailored vaccine adjuvants/vaccines remains underexplored. Only four vaccine adjuvants are currently on the market in the US and Europe. A critical research goal is to develop innovative new adjuvants specifically tailored to enhance the immunogenicity of different vaccines, based on the understanding of underlying cellular and biomolecular disease mechanisms. The project requires interaction of experts from the fields of pharmacy and immunology and will benefit from highly focused areas of expertise of researchers from Faculty of Pharmacy, Blood Transfusion Centre of Slovenia and University of Zagreb .
At the level of basic knowledge, this project will allow for the identification of the structural features pivotal for adjuvant activity of NOD2 agonists. This knowledge will provide an excellent basis for the development of novel adjuvants and their formulations. The formulation of synthesized adjuvants and a model antigen into delivery systems based on liposomes will increase adjuvant activity. Hence, a collaborative effort will lead to new knowledge on strategies for activation of the innate immune system via agonistic activity on NOD2 receptor (and dual NOD2/TLR7 agonism). The work proposed has significant clinical relevance since millions of infections worldwide (HCV, HIV, malaria) each year could be avoided using suitable vaccines, therefore a direct impact on human health is expected. Of note, the project may also pave the way for the development of tailored vaccines for animal use, which could also impact on animal health and possibly prevent an economic loss caused by animal diseases. The results of the proposed project will lead to joint publications in top-tier journals. Further, we will disseminate our results on several levels, via conference communications and posters as well as via project web-page, which will be constructed to reach as wide a scientific audience as possible. At the level of higher education – the experience and knowledge gained will be directly translated into the teaching process at the university environment, both as Master and PhD research projects. The results will also be presented at lectures to the students enrolled to pharmacy. The project will also result in the training of PhD researchers who will gain highly interdisciplinary and competitive skills in various laboratories. A high level of interaction is foreseen and researchers will be encouraged to visit partner laboratories. The project research will further strengthen the link between the collaborating research groups, thereby fostering long-term partnership that will outlive the project. Furthermore, it will contribute to the integration of Slovenian science into the international research community and thus contribute to the recognition of Slovenia. Following the successful outcome of this project, we also plan to apply for international funding, such as Horizon2020, which is in accordance with the national strategy and allows Slovenia scientists to collaborate in the international environment.
Significance for the country
Relevance and potential impact of the results. Development of tailored vaccine adjuvants/vaccines remains underexplored. Only four vaccine adjuvants are currently on the market in the US and Europe. A critical research goal is to develop innovative new adjuvants specifically tailored to enhance the immunogenicity of different vaccines, based on the understanding of underlying cellular and biomolecular disease mechanisms. The project requires interaction of experts from the fields of pharmacy and immunology and will benefit from highly focused areas of expertise of researchers from Faculty of Pharmacy, Blood Transfusion Centre of Slovenia and University of Zagreb .
At the level of basic knowledge, this project will allow for the identification of the structural features pivotal for adjuvant activity of NOD2 agonists. This knowledge will provide an excellent basis for the development of novel adjuvants and their formulations. The formulation of synthesized adjuvants and a model antigen into delivery systems based on liposomes will increase adjuvant activity. Hence, a collaborative effort will lead to new knowledge on strategies for activation of the innate immune system via agonistic activity on NOD2 receptor (and dual NOD2/TLR7 agonism). The work proposed has significant clinical relevance since millions of infections worldwide (HCV, HIV, malaria) each year could be avoided using suitable vaccines, therefore a direct impact on human health is expected. Of note, the project may also pave the way for the development of tailored vaccines for animal use, which could also impact on animal health and possibly prevent an economic loss caused by animal diseases. The results of the proposed project will lead to joint publications in top-tier journals. Further, we will disseminate our results on several levels, via conference communications and posters as well as via project web-page, which will be constructed to reach as wide a scientific audience as possible. At the level of higher education – the experience and knowledge gained will be directly translated into the teaching process at the university environment, both as Master and PhD research projects. The results will also be presented at lectures to the students enrolled to pharmacy. The project will also result in the training of PhD researchers who will gain highly interdisciplinary and competitive skills in various laboratories. A high level of interaction is foreseen and researchers will be encouraged to visit partner laboratories. The project research will further strengthen the link between the collaborating research groups, thereby fostering long-term partnership that will outlive the project. Furthermore, it will contribute to the integration of Slovenian science into the international research community and thus contribute to the recognition of Slovenia. Following the successful outcome of this project, we also plan to apply for international funding, such as Horizon2020, which is in accordance with the national strategy and allows Slovenia scientists to collaborate in the international environment.
