Dramatic increase of telomerase activity during dendritic cell differentiation and maturation

Area of Science:

• Immunology
• Molecular Biology
• Gerontology

Background:

• Telomerase, an enzyme maintaining telomere length, is typically absent in adult tissues but present in embryonic cells, cancers, and activated lymphocytes.
• The role of telomerase in myeloid cells, particularly dendritic cells (DCs), during differentiation and maturation remains largely unexplored.

Purpose of the Study:

• To investigate telomerase activity during the differentiation and maturation of dendritic cells (DCs).
• To compare telomerase activity and DC responses to microbial stimulation in young versus old mice.

Main Methods:

• Bone marrow (BM) cells were cultured with granulocyte-macrophage colony-stimulating factor and interleukin-4 to induce DC differentiation.
• Dendritic cell maturation was triggered using microbial components like lipopolysaccharide (LPS).
• Telomerase activity and cell-surface activation markers were measured in vitro and in vivo (splenic DCs) in young and old mice.

Main Results:

• In vitro differentiation of BM cells into DCs significantly increased telomerase activity.
• LPS stimulation augmented telomerase activity in DCs, indicating enhanced activity during maturation.
• Splenic DCs from old mice exhibited higher basal telomerase activity but a diminished response to LPS compared to young mice.
• Old mice showed poor LPS-induced activation of splenic and BM-derived DCs, suggesting impaired immune responses.

Conclusions:

• Dendritic cell differentiation and maturation are associated with increased telomerase activity.
• Aging impairs dendritic cell responsiveness to microbial stimuli, characterized by reduced activation marker expression and altered telomerase activity modulation.
• These age-related deficits in DC function may contribute to increased susceptibility to microbial infections in elderly individuals.