Non‑invasive proteome‑wide quantification of skin barrier‑related proteins using label‑free LC‑MS/MS analysis

Transcriptomics analysis reveals molecular alterations underpinning spaceflight dermatology

BACKGROUND

Spaceflight poses a unique set of challenges to humans and the hostile spaceflight environment can induce a wide range of increased health risks, including dermatological issues. The biology driving the frequency of skin issues in astronauts is currently not well understood.

METHODS

To address this issue, we used a systems biology approach utilizing NASA's Open Science Data Repository (OSDR) on space flown murine transcriptomic datasets focused on the skin, biochemical profiles of 50 NASA astronauts and human transcriptomic datasets generated from blood and hair samples of JAXA astronauts, as well as blood samples obtained from the NASA Twins Study, and skin and blood samples from the first civilian commercial mission, Inspiration4.

RESULTS

Key biological changes related to skin health, DNA damage & repair, and mitochondrial dysregulation are identified as potential drivers for skin health risks during spaceflight. Additionally, a machine learning model is utilized to determine gene pairings associated with spaceflight response in the skin. While we identified spaceflight-induced dysregulation, such as alterations in genes associated with skin barrier function and collagen formation, our results also highlight the remarkable ability for organisms to re-adapt back to Earth via post-flight re-tuning of gene expression.

CONCLUSION

Our findings can guide future research on developing countermeasures for mitigating spaceflight-associated skin damage.

Applications of Tandem Mass Spectrometry (MS/MS) in Protein Analysis for Biomedical Research

Mass Spectrometry (MS) allows the analysis of proteins and peptides through a variety of methods, such as Electrospray Ionization-Mass Spectrometry (ESI-MS) or Matrix-Assisted Laser Desorption Ionization-Mass Spectrometry (MALDI-MS). These methods allow identification of the mass of a protein or a peptide as intact molecules or the identification of a protein through peptide-mass fingerprinting generated upon enzymatic digestion. Tandem mass spectrometry (MS/MS) allows the fragmentation of proteins and peptides to determine the amino acid sequence of proteins (top-down and middle-down proteomics) and peptides (bottom-up proteomics). Furthermore, tandem mass spectrometry also allows the identification of post-translational modifications (PTMs) of proteins and peptides. Here, we discuss the application of MS/MS in biomedical research, indicating specific examples for the identification of proteins or peptides and their PTMs as relevant biomarkers for diagnostic and therapy.

Platelet-derived extracellular vesicles are increased in sera of Alzheimer's disease patients, as revealed by Tim4-based assays

Alzheimer's disease (AD) is the most common form of dementia, characterized by the accumulation of β‐amyloid plaques and the formation of neurofibrillary tangles. Extracellular vesicles (EVs) are small vesicles surrounded by a lipid bilayer membrane, which may be involved in the progression of AD. Glycans are essential building blocks of EVs, and we hypothesized that EV glycans may reflect pathological conditions of various diseases. Here, we performed glycan profiling of EVs prepared from sera of three AD patients (APs) compared to three healthy donors (HDs) using lectin microarray. Distinct glycan profiles were observed. Mannose‐binding lectins exhibited significantly higher signals for AP‐derived EVs than HD‐derived EVs. Lectin blotting using mannose‐binding lectin (rPALa) showed a single protein band at ~ 80 kDa exclusively in AP‐derived EVs. LC‐MS/MS analysis identified a protein band precipitated by rPALa as CD61, a marker of platelet‐derived exosomes (P‐Exo). Sandwich assays using Tim4 with specificity for phosphatidylserine on EVs and antibodies against P‐Exo markers (CD61, CD41, CD63, and CD9) revealed that P‐Exo is significantly elevated in sera of APs (n = 16) relative to age‐ and sex‐matched HDs (n = 16). Tim4‐αCD63 showed the highest value for the area under the curve (0.957) for discriminating APs from HDs, which should lead to a better understanding of AD pathology and may facilitate the development of a novel diagnostic method for AD.