Relationship between Endotoxin Content in Vaccine Preclinical Formulations and Animal Welfare: An Extensive Study on Historical Data to Set an Informed Threshold.

The most widely known pyrogen impurity in vaccines is the Gram-negative bacterial endotoxin lipopolysaccharide (LPS). When administered at toxic doses, endotoxin triggers inflammatory responses, which lead to endotoxic shock. The literature on endotoxic content (EC) for preclinical vaccines' formulations used in animal studies is very poor, and the recommended thresholds are solely based on commercial vaccine limits set for humans and are, therefore, not connected to the actual impact of EC on animal welfare for species used in preclinical research studies. An extensive study to evaluate the presence of a potential relationship between endotoxin content in formulations administered to mice (the most common species used in preclinical research studies) and their welfare was conducted to calculate an EC threshold for formulations of candidate vaccines. Three years of historical data, from more than 500 formulations of different antigen types (i.e., proteins, glycoconjugates, OMV/GMMA) injected into more than 5000 mice, was evaluated with two alternative statistical methodologies, both demonstrating that there is no significant relationship between actual endotoxin levels and mouse welfare. The calculation of thresholds was, therefore, performed by consistency versus formulations that demonstrated no impact on animal welfare.

Lung mucosal immunity to NTHi vaccine antigens: Antibodies in sputum of chronic obstructive pulmonary disease patients.

Chronic obstructive pulmonary disease (COPD) is a common chronic respiratory illness in older adults. A major cause of COPD-related morbidity and mortality is acute exacerbation of COPD (AECOPD). Bacteria in the lungs play a role in exacerbation development, and the most common pathogen is non-typeable Haemophilus influenzae (NTHi). A vaccine to prevent AECOPD containing NTHi surface antigens was tested in a clinical trial. This study measured IgG and IgA against NTHi vaccine antigens in sputum. Sputum samples from 40 COPD patients vaccinated with the NTHi vaccine were collected at baseline and 30 days after the second dose. IgG and IgA antibodies against the target antigens and albumin were analyzed in the sputum. We compared antibody signals before and after vaccination, analyzed correlation with disease severity and between sputum and serum samples, and assessed transudation. Antigen-specific IgG were absent before vaccination and present with high titers after vaccination. Antigen-specific IgA before and after vaccination were low but significantly different for two antigens. IgG correlated between sputum and serum, and between sputum and disease severity. Sputum albumin was higher in patients with severe COPD than in those with moderate COPD, suggesting changes in transudation played a role. We demonstrated that immunization with the NTHi vaccine induces antigen-specific antibodies in sputum. The correlation between IgG from sputum and serum and the presence of albumin in the sputum of severe COPD patients suggested transudation of antibodies from the serum to the lungs, although local IgG production could not be excluded.Clinical Trial Registration: NCT02075541.

What is the context? Chronic obstructive pulmonary disease (COPD) is the most common chronic respiratory illness in older adults and the third leading cause of death worldwide.One bacterium in the lungs, non-typeable Haemophilus influenzae (NTHi), is responsible for acute exacerbation of the disease, characterized by an increase in airway wall inflammation and symptoms, leading to high morbidity and mortality.A vaccine targeting NTHi was previously developed but did not show efficacy in reducing exacerbations in COPD patients, probably because the vaccine did not elicit an immune response in the lung mucosae, where the bacteria are located.What is the impact? Parenteral immunization with new vaccines targeting NTHi is able to elicit immune defense at the level of lung mucosae.Now that antibodies can be measured in sputum, new vaccines against COPD exacerbations or other lung infections can be tested for efficacy in the actual target tissue.Also, lung immunity against specific pathogens can now be tested.What is new? We determined that antigen-specific antibodies were present in the lungs after vaccination; these were assessed in sputum after vaccination with NTHi surface antigens.NTHi-specific IgG were present in the lungs and appeared to have arrived there primarily by transudation, a type of leakage from the serum to the lung mucosae.Transudation appeared to be stronger in severe than in moderate COPD patients.

Monocyte-activation test to reliably measure the pyrogenic content of a vaccine: An in vitro pyrogen test to overcome in vivo limitations.

Pyrogen content is one of the critical quality attributes impacting the safety of a product, and there is an increasing need for assays that can reliably measure this attribute in vaccines. The Limulus amebocyte lysate (LAL) assay and the rabbit pyrogen test (RPT) are the canonical animal-based pyrogen tests currently used to release vaccines; however, there are several drawbacks associated with these tests when applied to Bexsero, intrinsically pyrogenic product, containing a meningococcal Outer Membrane Vesicle component. While the RPT, as applied to Bexsero at its given dilution, ensures safe vaccine, it is highly variable and prone to false positive results. On the other hand, the LAL assay although quantitative, can detect only endotoxin pyrogens and is not sufficient for monitoring the safety of Bexsero, which contains both LPS and non-endotoxin pyrogens. Being aware of these limitations of the RPT and LAL when applied to Bexsero, the Monocyte Activation Test (MAT) which is sensitive to both endotoxin and non-endotoxin based pyrogens has been developed as an alternative pyrogen test. Here, the development and the validation of a MAT assay adapted from the European pharmacopoeia for Bexsero, is described. The MAT assay is then used for monitoring the safety and consistency of Bexsero vaccines at release, providing great advantages in terms of reduced variability with respect to RPT, reduction of animal use, in line with the 3Rs principle concerning the protection of animals and faster time to market. In addition the correlation of the MAT to the RPT has been demonstrated supporting the replacement of the in vivo method and the potential application of the assay to other intrinsically pyrogenic vaccines.

Extending large-scale forest inventories to assess urban forests.

Urban areas are continuously expanding today, extending their influence on an increasingly large proportion of woods and trees located in or nearby urban and urbanizing areas, the so-called urban forests. Although these forests have the potential for significantly improving the quality the urban environment and the well-being of the urban population, data to quantify the extent and characteristics of urban forests are still lacking or fragmentary on a large scale. In this regard, an expansion of the domain of multipurpose forest inventories like National Forest Inventories (NFIs) towards urban forests would be required. To this end, it would be convenient to exploit the same sampling scheme applied in NFIs to assess the basic features of urban forests. This paper considers approximately unbiased estimators of abundance and coverage of urban forests, together with estimators of the corresponding variances, which can be achieved from the first phase of most large-scale forest inventories. A simulation study is carried out in order to check the performance of the considered estimators under various situations involving the spatial distribution of the urban forests over the study area. An application is worked out on the data from the Italian NFI.