Pollen-derived RNAs Are Found in the Human Circulation.

Area of Science:

• Molecular Biology
• Immunology
• Environmental Health

Background:

• The presence and origin of nonhuman RNAs, specifically microRNAs (miRNAs), in human circulation remain largely uncharacterized.
• Understanding the potential transfer of food- or environment-derived miRNAs into the human bloodstream is crucial for health and disease research.

Purpose of the Study:

• To investigate the presence of nonhuman miRNAs in human plasma.
• To determine the origin and mechanism of transfer of plant-derived miRNAs into circulation.
• To explore associations between detected plant miRNAs and human health conditions.

Main Methods:

• RNA sequencing was employed on plasma samples from a large population study.
• Quantitative real-time PCR (RT-qPCR) was used to validate specific pine-pollen miRNAs.
• In vivo and in vitro models were utilized to elucidate the transfer mechanism via pulmonary pathways.
• Platelet-pulmonary vascular cell interactions and platelet pollen-DNA uptake were examined.

Main Results:

• Nonhuman miRNAs were detected in human plasma.
• A subset of pine-pollen miRNAs was validated in 2,776 individuals.
• The presence of these pine-pollen miRNAs correlated with hay fever symptoms.
• No association was found with overt cardiovascular or pulmonary diseases.
• Mechanistic studies revealed pulmonary transfer mediated by platelets and vascular cells.

Conclusions:

• Pollen-derived plant miRNAs can be horizontally transferred into human circulation through the pulmonary system.
• Platelet-mediated interactions play a key role in the pulmonary transfer of plant miRNAs.
• While mechanistic plausibility is established, the current observational data do not link these plant miRNAs to major diseases or risk factors.