Identification of sheep lncRNAs related to the immune response to vaccines and aluminium adjuvants

Background Long non-coding RNAs (lncRNAs) are involved in several immune processes, including the immune response to vaccination, but most of them remain uncharacterised in livestock species. The mechanism of action of aluminium adjuvants as vaccine components is neither not fully understood. Results We built a transcriptome from sheep PBMCs RNA-seq data in order to identify unannotated lncRNAs and analysed their expression patterns along protein coding genes. We found 2284 novel lncRNAs and assessed their conservation in terms of sequence and synteny. Differential expression analysis performed between animals inoculated with commercial vaccines or aluminium adjuvant alone and the co-expression analysis revealed lncRNAs related to the immune response to vaccines and adjuvants. A group of co-expressed genes enriched in cytokine signalling and production highlighted the differences between different treatments. A number of differentially expressed lncRNAs were correlated with a divergently located protein-coding gene, such as the OSM cytokine. Other lncRNAs were predicted to act as sponges of miRNAs involved in immune response regulation. Conclusions This work enlarges the lncRNA catalogue in sheep and puts an accent on their involvement in the immune response to repetitive vaccination, providing a basis for further characterisation of the non-coding sheep transcriptome within different immune cells.

Was amorphous aluminium hydroxyphosphate sulfate adequately evaluated before authorisation in Europe?

The Merck Sharp & Dohme Corp aluminium adjuvant ‘amorphous aluminium hydroxyphosphate sulfate’ (AAHS), primarily used in the Gardasil vaccines against human papilloma virus, has been criticised for lack of evidence for its safety. Documentation from Danish authorities and answers from the European Medicines Agency (EMA) suggest that AAHS may not have been sufficiently evaluated. Documentation from the Danish Medicines Agency shows discrepancies in the trial documents of two prelicensure clinical trials with Gardasil in 2002 and 2003. For both trials, the Agency seems to have authorised potassium aluminium sulfate as the adjuvant and not AAHS. In addition, the participants in the trial launched in 2002 were informed that the comparator was saline, even though the comparator was AAHS in an expedient consisting of L-histidine, polysorbate-80, sodium borate and sodium chloride. According to the EMA, AAHS was first introduced in Europe in 2004 as the adjuvant in Procomvax, a vaccine against the hepatitis B virus and Haemophilus influenza type b. The EMA reports that AAHS was introduced without any prelicensure safety evaluation. The adjuvant is described by the company to be both physically and functionally distinct from all other previously used aluminium adjuvants. There is a need for rigorous evaluation of benefits and harms of the adjuvant AAHS.

Aluminium Adjuvants – A Nanomaterial used as Adjuvants in Human Vaccines for Decades

Background:Aluminium salts have been used for decades in vaccines as adjuvants to facilitate the adaptive immune response against co-administered antigens. Two types of aluminium adjuvant are mostly used, aluminium oxyhydroxide and aluminium hydroxyphosphate. Both types of aluminium adjuvant consist of nanoparticles that form loose, micrometre sized aggregates at circumneutral pH.Aluminium adjuvants constitute a well-documented example of administration of nanomaterials to humans with infrequent side effects and a safety record generally regarded as excellent. However, despite its prolonged use in human and veterinary medicine, the mechanisms behind the enhanced response and the immune stimulatory effect are still by and large unknown.Methods:The present paper reviews existing ideas regarding the immunostimulatory effects of aluminium adjuvants, with a focus on the induction of an inflammatory response by cellular stress. Reviewed information was obtained from peer-reviewed scientific papers published in 1988 to date with one exception, a paper published 1931.Results:Cellular stress causes extra cellular signalling of Danger Associated Molecular Patterns (DAMPs) and upon phagocytosis of aluminium adjuvants the cells need to manage the ingested particles.Conclusion:A persistent intracellular accumulation of aluminium adjuvants will be a solid depository of sparingly soluble aluminium salts maintaining a constant concentration of Al3+ions in the cytoplasm and this will affect multiple biochemical processes. The cell will be under constant stress and DAMP signalling will occur and we would like to suggest the maintenance of a constant concentration Al3+ions in the cytoplasm as a general underlying feature of the immune stimulation properties of aluminium adjuvants.