The circulating microRNome demonstrates distinct lymphocyte subset-dependent signatures

Area of Science:

• Immunology
• Molecular Biology
• Genetics

Background:

• Lymphocytes release microRNAs (miRNAs) upon activation.
• The impact of lymphocyte-derived miRNAs on the circulating serum miRNome is largely unknown.
• Identifying lymphocyte subset-specific miRNA signatures could reveal novel biomarkers.

Purpose of the Study:

• To identify specific microRNA (miRNA) signatures in the serum miRNome associated with distinct lymphocyte subsets.
• To investigate whether the absence of specific lymphocyte populations alters the circulating miRNome.
• To establish a link between miRNA function in lymphocyte development and their serum levels.

Main Methods:

• Serum miRNA expression profiling in wild-type mice.
• Analysis of serum miRNA profiles in mice lacking specific lymphocyte subsets (CD4+ T cells, CD8+ T cells, iNKT cells, B cells).
• Assessment of serum miRNA profiles in T lymphocytes with Dicer ablation.

Main Results:

• Distinct serum miRNA profiles were observed when specific lymphocyte subsets were absent.
• The serum level of miR-181b-5p was significantly reduced in mice lacking invariant natural killer T (iNKT) cells.
• miR-181b-5p's role in iNKT cell development correlates with its altered serum level.

Conclusions:

• Specific lymphocyte subsets contribute distinct miRNA signatures to the circulating serum miRNome.
• Even rare lymphocyte populations, like iNKT cells, measurably influence serum miRNA levels.
• Serum miRNA profiling can reflect the status of specific lymphocyte populations in vivo.