MICA VACCINE FAPESP MICA: Pulmonary Delivery of a Targeted Mucosal Nanocarrier Vaccine for Pneumonia

Streptococcus pneumoniae is a bacterium that uses the lungs as a route of entry into the body causing community acquired-pneumonia (CAP). It is a leading cause of ill-health and death in children, elderly and immunocompromised worldwide. Moreover, amongst adults, it is the leading cause of CAP which is likely to rise with increasing life expectancy and escalating resistance towards antibiotics. Furthermore, if S. pneumoniae is not treated it can gain entry into the blood resulting in life-threatening septicaemia and meningitis. The health service costs associated with pneumococcal infection is £1 billion (UK), $5.5 billion (USA), 10 billion Euros (Europe) and $240 million (Brazil). The World Health Organization regards vaccination as an important public health strategy to combat infectious diseases. Vaccines should be safe, effective, practical and affordable.

The current vaccine only offers protection against 13 most common strains of S. pneumoniae and has limited effectiveness against CAP. To be effective multiple vaccine candidates are required offering cross-protection against the many different strains. However, this is not practical due to high costs and lengthy timescale for production. Furthermore, it is administered via injection resulting in poor immune protection within the lungs. Therefore, there is a need for a more effective vaccine candidate that can be given safely and practically directly to the lungs providing better protection against S. pneumoniae.

Vaccination via the lungs is an attractive avenue as it mimics the natural infection route of S. pneumoniae and can lead to immune protection over the whole body via other connected sites, such as nose and intestines. Inhalation offers the advantage of eliminating syringes and needles, removing the hazard of safe disposal and lowering the risk of blood-borne infections.

Various parts of bacteria known as antigens can stimulate an immune response. Researchers in Institute Butantan, Brazil are proposing proteins common to all strains: PspA, from the surface of S. pneumoniae, genetically detoxified pneumolysin (PdT) and PspA-PdT fusion protein. The three proteins will be separately incorporated into small particles (nanoparticles, NPs) and compared to each other with regards to activity, immune response and aerosolisation efficiency into the lungs. The NPs are safe and have adjuvant properties which help activate an immune response, hence can result in a stronger immune response using lower protein concentrations. Moreover, due to the NPs size (~200nm) they can cross barriers in the lungs and promote the uptake of proteins by antigen presenting cells that can effectively initiate an immune response in the lungs.

In order to increase delivery of NPs into the lungs, they are embedded within larger microparticle carriers prepared using pharmaceutically inert amino-acids or sugars, resulting in dry powder nanocomposite microparticle carriers (NCMPs) of suitable particle size (1-5micron) for deposition within the lung. In addition, we will also test the NCMPs via nebulisation, which is of benefit to children and elderly who have difficulty with using conventional dry powder inhalers. Furthermore, the formation of dry powder NCMPs will increase the stability of NPs and antigen, and eliminate cold temperature transport and storage.

This project will evaluate vaccine delivery of NPs/NCMPs as carriers of PspA or PdT or PspA-PdT, for the prevention of pneumococcal diseases via inhalation enhancing immune response in mice compared to needle-based vaccination of free antigen as control. We will investigate the immune responses after single and booster injections through this route, and evaluate the protection against S. pneumoniae challenge in the lungs. If successful, our vaccine nanocarrier technology platform can be applied to a range of different infectious agents not only in human health but also for veterinary use.

Streptococcus pneumoniae enters the body via the lung mucosal surfaces causing community acquired-pneumonia and if untreated enters the blood resulting in life-threatening septicaemia and meningitis. Despite the use of current pneumococcal conjugate vaccines, pneumococcal disease continues to have a high burden due to variation in serotype global distribution and non-vaccine serotype replacement in S. pneumoniae carriage. This has led to evaluation of protein antigens, pneumococcal surface protein A (PspA), genetically detoxified pneumolysin (PdT), PspA-PdT fusion protein which are present in virtually all strains.

We will develop a pulmonary mucosal vaccine nanocarrier technology platform composed of layer-by-layer nanoparticles (NPs) spraydried to produce dry powder nanocomposite microparticle carriers (NCMPs). The NPs have adjuvant properties initiating adaptive and innate immunity through uptake by lung dendritic cells (DCs), with enhanced magnitude and duration of immunity using lower antigen concentrations. The NCMPs will enhance the stability of NPs, protein during storage and allow dry powder inhalation (DPI) (which will release the NPs within the lung fluid, which can then interact with DCs) and nebulisation for specific patient groups (children and elderly).

We will test this technology through a series of experiments:
1. Production of PspA, PdT, PspA-PdT
2. Assessment of uptake, activation by DCs & B cells
3. Assessment of spraydrying parameters to produce NCMPs suitable for DPI & nebulisation
4. Determine the antibody & cellular responses & pneumococcal protection in mice

We will communicate results to the general public via organised events at LJMU, LSTM, IB and to the scientific community via publications, workshops and conferences. The outcome will be the development of a pulmonary mucosal vaccine nanocarrier technology platform for pneumococcal vaccination with potential application to other human and animal diseases

The World Health Organization (WHO) regards vaccination as an important public health strategy. The current pneumococcal conjugate vaccines have limited efficacy against pneumonia due to poor immunity at lung mucosal sites, variation in serotype global distribution and non-vaccine serotype replacement in S. pneumoniae carriage. In this project we will develop a dry powder vaccine technology platform containing nanoparticles (NPs) adsorbed with antigen and formulated into nanocomposite microparticles (NCMPs) for inhalation.

Who will benefit from this research
This research has potential in improving our knowledge, development and delivery of novel NPs formulations and dry powder NCMPs of pneumococcal vaccines. Immediate beneficiaries include academics, scientists, pharmaceutical companies, public research funders, policy makers and clinicians in vaccine research and development programmes, human immunology, pulmonary antigen delivery systems. The future impact will benefit Bill & Melinda Gates Foundation, the pharmaceutical industry, WHO and IB (produces vaccines for the Brazilian Ministry of Health) which could invest in this technology platform for further research or implementing vaccine programmes.

Benefits from this research
Health and economic value:
There is a huge cost to the health service and wider economy due to days lost at work, treatment and hospital admissions. The costs associated with pneumococcal infection have been estimated at £1 billion (UK), $5.5 billion (USA), 10 billion Euro (Europe), $240 million (Brazil). Hence an improved pneumococcal vaccine formulation delivered to the respiratory tract would lead to better quality of life and result in economic gain on an already over-stretched healthcare system in the developed world but more so in low-middle income countries.

Scientific & economic value:
This project is multidisciplinary in nature and will train a graduate students (IB) and postdoctoral scientist (LJMU, LSTM) in the scientific disciplines of cell and molecular biology, pharmaceutical sciences, drug delivery, microbiology and animal models for vaccine evaluation, leading to cross-fertilisation of ideas and expertise. Consequently, the individuals will be equipped with the necessary skills to play a part in enhancing the UK and Brazilian scientific intellect and economic profile.

Pharmaceutical companies:
GlaxoSmithKline and Pfizer have large research and development programme in vaccines, pulmonary drug delivery and specifically pneumococcal diseases. This work will generate information following NPs-antigen pulmonary delivery that will provide new knowledge that links immune response to protection and can potentially be applied to other infectious diseases.

Respiratory medical device companies:
New knowledge will be gained around "drug/device" combinations using DPI and nebulisers to deliver vaccines to the respiratory tract. Specific work in this space has been limited, and with increasing focus on mucosal targeting of vaccines, this work shall have application beyond the proposed NP-antigen.

Advances in vaccine delivery systems:
A major advancement would be the development of a protein-based/protein-fusion vaccine that provides serotype-independent protection against pneumococcal diseases, including pneumonia, and delivered directly to the respiratory tract via NPs systems. Such a vaccine would provide broad protection and have a lower production cost compared to the current protein-polysaccharide conjugate vaccines.

Enhanced public health:
Government health agencies, policy makers and the general public will benefit from the development of enhanced vaccine delivery systems that can be applied to the control of a range of pathogens which is essential for the promotion of healthy ageing, lifestyle and decreasing the economic health burden associated with pneumococcal diseases which is a major health problem in humans.