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Introduction
Respiratory tract infections are a worldwide health problem for humans and animals. Different cell types produce lipid mediators in response to infections, which consist of eicosanoids like hydroxyeicosatetraenoic acids (HETEs) or oxylipins like hydroxydocosahexaenoic acids (HDHAs). Both substance classes possess immunomodulatory functions. However, little is known about their role in respiratory infections.
Objectives
Here, we aimed to analyze the lipid mediator imprint of different organs of C57BL/6J mice after intranasal mono-infections with Streptococcus pneumoniae (pneumococcus), Staphylococcus aureus or Influenza A virus (IAV) as wells as pneumococcal-IAV co-infection.
Methods
C57BL/6J mice were infected with different pathogens and lungs, spleen, and plasma were collected. Lipid mediators were analyzed using HPLC-MS/MS. In addition, spatial-distribution of sphingosine 1-phosphate (S1P) and ceramide 1-phosphates (C1P) in tissue samples was examined using MALDI-MS-Imaging. The presence of bacterial pathogens in the lung was confirmed via immunofluorescence staining.
Results
We found IAV specific changes for different HDHAs and HETEs in mouse lungs as well as enhanced levels of 20-HETE in severe S. aureus infection. Moreover, MALDI-MS-Imaging analysis showed an accumulation of C1P and a decrease of S1P during co-infection in lung and spleen. Long chain C1P was enriched in the red and not in the white pulp of the spleen.
Conclusions
Lipid mediator analysis showed that host synthesis of bioactive lipids is in part specific for a certain pathogen, in particular for IAV infection. Furthermore, MS-Imaging displayed great potential to study infections and revealed changes of S1P and C1P in lungs and spleen of co-infected animals, which was not described before.
Impact of different oral treatments on the composition of the supragingival plaque microbiome
(2022)
Background
Antiseptics are used to inhibit oral biofilm growth. However, they affect not only pathogenic but also commensal bacteria, which are a natural barrier against oral diseases.
Objective
Using a metaproteome approach combined with a standard plaque-regrowth study, this pilot study examined the impact of different concentrations of lactoperoxidase (LPO)-system containing lozenges on early plaque formation, and active biological processes.
Design
Sixteen orally healthy subjects received four local treatments as a randomized single-blind study based on a cross-over design. Two lozenges containing components of the LPO-system in different concentrations were compared to a placebo and Listerine®. The newly formed dental plaque was analyzed by mass spectrometry (nLC-MS/MS).
Results
On average 1,916 metaproteins per sample were identified, which could be assigned to 116 genera and 1,316 protein functions. Listerine® reduced the number of metaprotein groups and their relative abundance, confirming the plaque inhibiting effect. The LPO-lozenges triggered mainly higher metaprotein abundances of early and secondary colonizers as well as bacteria associated with dental health but also periodontitis. Functional information indicated plaque biofilm growth.
Conclusion
The effects of Listerine® and LPO-system containing lozenges used for plaque inhibition are different. In contrast to Listerine®, the lozenges allowed maintenance of a higher bacterial diversity.
Extracellular vesicles (EVs) are reminiscent of their cell of origin and thus represent a
valuable source of biomarkers. However, for EVs to be used as biomarkers in clinical practice, simple,
comparable, and reproducible analytical methods must be applied. Although progress is being
made in EV separation methods for human biofluids, the implementation of EV assays for clinical
diagnosis and common guidelines are still lacking. We conducted a comprehensive analysis of
established EV separation techniques from human serum and plasma, including ultracentrifugation
and size exclusion chromatography (SEC), followed by concentration using (a) ultracentrifugation,
(b) ultrafiltration, or (c) precipitation, and immunoaffinity isolation. We analyzed the size, number,
protein, and miRNA content of the obtained EVs and assessed the functional delivery of EV cargo.
Our results demonstrate that all methods led to an adequate yield of small EVs. While no significant
difference in miRNA content was observed for the different separation methods, ultracentrifugation
was best for subsequent flow cytometry analysis. Immunoaffinity isolation is not suitable for
subsequent protein analyses. SEC + ultracentrifugation showed the best functional delivery of
EV cargo. In summary, combining SEC with ultracentrifugation gives the highest yield of pure
and functional EVs and allows reliable analysis of both protein and miRNA contents. We propose
this combination as the preferred EV isolation method for biomarker studies from human serum
or plasma.