Relationships between the metabolome and the fatty acid composition of human saliva; effects of stimulation

Saliva is a biological fluid that is easy to collect and is of considerable interest as a source of biomarkers. To date, its protein composition has been the most extensively studied but its metabolic composition is also of real interest. However, the composition of saliva is complex and dependent on numerous factors, among which stimulation is source of many variations. The aim of this work was to study the effects of a stimulating condition (chewing) versus a resting condition on the human salivary metabolome. Saliva from 16 subjects was collected on three occasions and studied using nuclear magnetic resonance. The two conditions could be separated by PLS-DA analysis. Fatty acids, some organic acids and amino acids, probably arising from the degradation of prolin-rich proteins, were over-represented in stimulated saliva, whereas taurine, and propionate were over-represented in resting saliva. To clarify further the identification of fatty acids, the free and total fatty acid contents were studied by gas chromatography. The principal fatty acids identified were oleic, stearic and palmitic acids. It was also possible to separate the two conditions of stimulation by PLS-DA. These results show that the regulation of saliva and sampling conditions must be taken into account when studying markers in saliva.     

Cross-Serotype Immunity Induced by Immunization with a Conserved Rhinovirus Capsid Protein

Human rhinovirus (RV) infections are the principle cause of common colds and precipitate asthma and COPD exacerbations. There is currently no RV vaccine, largely due to the existence of ∼150 strains. We aimed to define highly conserved areas of the RV proteome and test their usefulness as candidate antigens for a broadly cross-reactive vaccine, using a mouse infection model. Regions of the VP0 (VP4+VP2) capsid protein were identified as having high homology across RVs. Immunization with a recombinant VP0 combined with a Th1 promoting adjuvant induced systemic, antigen specific, cross-serotype, cellular and humoral immune responses. Similar cross-reactive responses were observed in the lungs of immunized mice after infection with heterologous RV strains. Immunization enhanced the generation of heterosubtypic neutralizing antibodies and lung memory T cells, and caused more rapid virus clearance. Conserved domains of the RV capsid therefore induce cross-reactive immune responses and represent candidates for a subunit RV vaccine.     

How much can a T-cell antigen receptor adapt to structurally distinct antigenic peptides?

Binding degeneracy is thought to constitute a fundamental property of the T-cell antigen receptor (TCR), yet its structural basis is poorly understood. We determined the crystal structure of a complex involving the BM3.3 TCR and a peptide (pBM8) bound to the H-2K(bm8) major histocompatibility complex (MHC) molecule, and compared it with the structures of the BM3.3 TCR bound to H-2K(b) molecules loaded with two peptides that had a minimal level of primary sequence identity with pBM8. Our findings provide a refined structural view of the basis of BM3.3 TCR cross-reactivity and a structural explanation for the long-standing paradox that a TCR antigen-binding site can be both specific and degenerate. We also measured the thermodynamic features and biological penalties that incurred during cross-recognition. Our data illustrate the difficulty for a given TCR in adapting to distinct peptide-MHC surfaces while still maintaining affinities that result in functional in vivo responses. Therefore, when induction of protective effector T cells is used as the ultimate criteria for adaptive immunity, TCRs are probably much less degenerate than initially assumed.     

Comparison of human papillomavirus genotypes in archival cervical cancer specimens from Alaska natives, Greenland natives and Danish Caucasians

Archival, formalin-fixed, paraffin-embedded cervical cancer specimens from 53 Alaska natives, 32 Greenland natives and 34 Danish Caucasians were analyzed for human papillomavirus (HPV) genotypes 16, 18, 31, 33, 35 and 45 and unidentified genotypes (HPV X) using PCR. The specimens were from the time period 1980-1989. No significant differences were observed in the overall HPV detection rates among cases from Alaska (98.1%), Greenland (84.4%) and Denmark (85.3%). HPV genotype 16 was the most prevalent type: 78.8% in Alaska natives, 96.3% in Greenland natives and 82.8% in Danish Caucasians. A prevalence of 21.2% HPV 31 and 30.8% HPV 33 was found in Alaska natives, of which most were coinfections with HPV 16. Only 3.7% HPV 31 and 3.7% HPV 33 were found in Greenland natives and no HPV 31 and 6.9% HPV 33 were found in Danish Caucasians. HPV 18 was only detected in Alaska natives and HPV 35 and 45 were not detected in any of the three populations. Infections with multiple genotypes were prevalent in Alaskan (36.5%) but not in Greenland natives (3. 7%) and Danish Caucasians (6.9%). The Eskimo subgroup of the Alaska native population has a significantly higher prevalence of HPV genotypes 31 and 33 associated with mixed infections in invasive cancer than the two other native subgroups (P = 0.04) and Greenland and Danish populations, reflecting genotype distributions in dysplasia and normal cervical cytology. The reason for HPV genotype diversity, although unknown, may be relevant to the current development of HPV vaccines.