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Liverpool, United Kingdom

Gritzfeld J.F.,Respiratory Infection Group
Journal of visualized experiments : JoVE

Experimental human pneumococcal carriage (EHPC) is scientifically important because nasopharyngeal carriage of Streptococcus pneumoniae is both the major source of transmission and the prerequisite of invasive disease. A model of carriage will allow accurate determination of the immunological correlates of protection, the immunizing effect of carriage and the effect of host pressure on the pathogen in the nasopharyngeal niche. Further, methods of carriage detection useful in epidemiologic studies, including vaccine studies, can be compared. We aim to develop an EHPC platform that is a safe and useful reproducible method that could be used to down-select candidate novel pneumococcal vaccines with prevention of carriage as a surrogate of vaccine induced immunity. It will work towards testing of candidate vaccines and descriptions of the mechanisms underlying EHPC and vaccine protection from carriage. Current conjugate vaccines against pneumococcus protect children from invasive disease although new vaccines are urgently needed as the current vaccine does not confer optimal protection against non-bacteraemic pneumonia and there has been evidence of serotype replacement with non-vaccine serotypes. We inoculate with S. pneumoniae suspended in 100 μl of saline. Safety is a major factor in the development of the EHPC model and is achieved through intensive volunteer screening and monitoring. A safety committee consisting of clinicians and scientists that are independent from the study provides objective feedback on a weekly basis. The bacterial inoculum is standardized and requires that no animal products are inoculated into volunteers (vegetable-based media and saline). The doses required for colonization (10(4)-10(5)) are much lower than those used in animal models (10(7)). Detecting pneumococcal carriage is enhanced by a high volume (ideally > 10 ml) nasal wash that is relatively mucus free. This protocol will deal with the most important parts of the protocol in turn. These are (a) volunteer selection, (b) pneumococcal inoculum preparation, (c) inoculation, (d) follow-up and (e) carriage detection. Our current protocol has been safe in over 100 volunteers at a range of doses using two different bacterial serotypes. A dose ranging study using S. pneumoniae 6B and 23F is currently being conducted to determine the optimal inoculation dose for 50% carriage. A predicted 50% rate of carriage will allow the EHPC model to have high sensitivity for vaccine efficacy with small study numbers. Source

Kunda N.K.,Liverpool John Moores University | Somavarapu S.,University College London | Gordon S.B.,Respiratory Infection Group | Hutcheon G.A.,Liverpool John Moores University | Saleem I.Y.,Liverpool John Moores University
Pharmaceutical Research

Pulmonary vaccine delivery has gained significant attention as an alternate route for vaccination without the use of needles. Immunization through the pulmonary route induces both mucosal and systemic immunity, and the delivery of antigens in a dry powder state can overcome some challenges such as cold-chain and availability of medical personnel compared to traditional liquid-based vaccines. Antigens formulated as nanoparticles (NPs) reach the respiratory airways of the lungs providing greater chance of uptake by relevant immune cells. In addition, effective targeting of antigens to the most 'professional' antigen presenting cells (APCs), the dendritic cells (DCs) yields an enhanced immune response and the use of an adjuvant further augments the generated immune response thus requiring less antigen/dosage to achieve vaccination. This review discusses the pulmonary delivery of vaccines, methods of preparing NPs for antigen delivery and targeting, the importance of targeting DCs and different techniques involved in formulating dry powders suitable for inhalation. © 2012 Springer Science+Business Media New York. Source

Wright A.K.A.,National Health Research Institute | Christopoulou I.,University of Liverpool | El Batrawy S.,National Health Research Institute | Limer J.,BD Bioscience Oxford Science Park | Gordon S.B.,Respiratory Infection Group

Conjugate pneumococcal vaccines offer suboptimal protection against mucosal infections and are restricted in serotype and geographical coverage. New protein-based vaccines using conserved pneumococcal antigens and better mucosal adjuvant technology are urgently needed. Interleukin-12 (IL-12) has shown efficacy as a pneumococcal protein vaccine adjuvant in murine models of pneumococcal infection. Systemic administration of recombinant human (rh) IL-12 to humans, however, has been associated with adverse clinical and laboratory side effects. Inhaled forms of IL-12 have improved the safety profiles in humans, as suggested by animal models. Here we evaluated rhIL-12 as an adjuvant on ex vivo human BAL cells when stimulated with pneumococcal whole cells. We show that co-incubation of ex vivo human BAL cells with pneumococcal whole cell antigen (WCA) and a low dose of rhIL-12 (2ng) can elevate TNF production compared to treatment with WCA (p=0.06) or rhIL-12 (p=0.03) alone. The production of IFNγ was also increased but not in an antigen specific manner, suggesting perhaps a predominant Th 1 response. Our data suggest that 100-200-fold lower doses of inhaled rhIL-12 than those previously tested for systemic use may be adequate in a phase 1 study and commend further evaluation of rhIL-12 as a potential mucosal adjuvant in human vaccine studies. © 2011 Elsevier GmbH. Source

Jambo K.C.,Malawi Liverpool Wellcome Trust Clinical Research Programme | Jambo K.C.,Respiratory Infection Group | Sepako E.,Malawi Liverpool Wellcome Trust Clinical Research Programme | Sepako E.,University of Liverpool | And 2 more authors.
Trends in Microbiology

Pneumococcal pneumonia is a life-threatening disease with high mortality and morbidity among children under 5 years of age, the elderly and immunocompromised individuals worldwide. Protection against pneumococcal pneumonia relies on successful regulation of colonisation in the nasopharynx and a brisk alveolar macrophage-mediated immune response in the lung. Therefore, enhancing pulmonary mucosal immunity (which includes a combination of innate, humoral and cell-mediated immunity) through mucosal vaccination might be the key to prevention of pneumococcal infection. Current challenges include a lack of information in humans on mucosal immunity against pneumococci and a lack of suitable adjuvants for new vaccines. Data from mouse models, however, suggest that mucosally active vaccines will enhance mucosal and systemic immunity for protection against pneumococcal infection. © 2009 Elsevier Ltd. All rights reserved. Source

Wright A.K.A.,Respiratory Infection Group | Wright A.K.A.,National Health Research Institute | Wright A.K.A.,University of Leicester | Bangert M.,Respiratory Infection Group | And 8 more authors.
PLoS Pathogens

Pneumococcal carriage is both immunising and a pre-requisite for mucosal and systemic disease. Murine models of pneumococcal colonisation show that IL-17A-secreting CD4+ T-cells (Th-17 cells) are essential for clearance of pneumococci from the nasopharynx. Pneumococcal-responding IL-17A-secreting CD4+ T-cells have not been described in the adult human lung and it is unknown whether they can be elicited by carriage and protect the lung from pneumococcal infection. We investigated the direct effect of experimental human pneumococcal nasal carriage (EHPC) on the frequency and phenotype of cognate CD4+ T-cells in broncho-alveolar lavage and blood using multi-parameter flow cytometry. We then examined whether they could augment ex vivo alveolar macrophage killing of pneumococci using an in vitro assay. We showed that human pneumococcal carriage leads to a 17.4-fold (p = 0.007) and 8-fold (p = 0.003) increase in the frequency of cognate IL-17A+ CD4+ T-cells in BAL and blood, respectively. The phenotype with the largest proportion were TNF+/IL-17A+ co-producing CD4+ memory T-cells (p<0.01); IFNγ+ CD4+ memory T-cells were not significantly increased following carriage. Pneumococci could stimulate large amounts of IL-17A protein from BAL cells in the absence of carriage but in the presence of cognate CD4+ memory T-cells, IL-17A protein levels were increased by a further 50%. Further to this we then show that alveolar macrophages, which express IL-17A receptors A and C, showed enhanced killing of opsonised pneumococci when stimulated with rhIL-17A (p = 0.013). Killing negatively correlated with RC (r = -0.9, p = 0.017) but not RA expression. We conclude that human pneumococcal carriage can increase the proportion of lung IL-17A-secreting CD4+ memory T-cells that may enhance innate cellular immunity against pathogenic challenge. These pathways may be utilised to enhance vaccine efficacy to protect the lung against pneumonia. © 2013 Wright et al. Source

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