| RESEARCH HIGHLIGHTS |
that a number of vinegar fly genes pertain to fly anxiety, including several genes related to serotonin, a neuromodulator. “There are no human genes known
to be associated with anxiety disorders,” Claridge-Chang notes, “we don’t know very
much about the genetic or molecular underpin- nings of either anxiety or depression. However, clearly neuromodulators like serotonin have enormous effects on emotional state, so it is a priority to understand how these systems work.” The team is now using their fly anxiety
assay to elucidate basic neurogenetic mecha- nisms of anxiety.
1. Mohammad, F., Aryal, S., Ho, J., Stewart, J. C., Norman, N. A. et al. Ancient anxiety pathways influence drosophila defense behaviors. Current Biology 26, 981–986 (2016).
Immunology
SEARCHING FOR THE SECRET OF YOUTH
NOT ALL TYPES OF T CELLS FOLLOW THE SAME TRAJECTORY AS WE AGE. UNDERSTANDING WHY COULD HELP IMPROVE IMMUNITY IN THE ELDERLY
As people age, their immune system gradually deteriorates and their ability to respond opti- mally to infections declines, a process called ‘immunosenescence’. A*STAR research shows that not all types of T cells, a type of immune cell that matures in the thymus, follow the same trajectory with age. There are two main subtypes of T cells.
The majority are α/β T cells, which help mediate immunity to infections. While γ/δ T cells represent approximately 1 to 10 per cent of all circulating T cells, they differ from α/β cells in that they recognize fewer foreign elements, or antigens, entering the body, explains immunologist Anis Larbi of A*STAR’s Singapore Immunology Network. They are, however, vital for fighting infections and targeting cancer cells. “We wanted to understand whether
all T cells were equal toward the process of cell differentiation and senescence,” says Larbi.
www.astar-research.com Larbi and colleagues in Singapore and
Germany compared the blood levels of α/β T cells with those of a subtype of γ/δ T cells, called Vδ2 cells, in thirty-six 18- to 23-year-olds and seventy-two 55- to 85-year-olds. Vδ2 T cells represent 60 to 80 per cent of all γ/δ T cells. When T cells emerge from the thymus, they
are ‘naïve’ as they have not yet encountered an antigen. Once introduced, however, they turn into ‘memory’ T cells that can proliferate to deal with the current emergency and then survey the circulation for similar future ones. The team found significant differences between the two cohorts in the percentages of naïve and memory α/β and Vδ2 T cells and in the amounts of proteins, called cytokines, secreted by the cells. The data suggests that Vδ2 cells sustain their functionality with age, unlike other types of T cells. “This study raises the question of whether Vδ2 T cells are resistant to
Understanding why immune cells age at different rates could help improve immunity in the elderly.
senescence,” explains Larbi. “Some cells potentially could be used as models to better understand senescence and identify pathways to resist the phenomenon, and not only on immune cells”. Further studies are needed to understand
the pathways that reduce susceptibility to senescence in T cells. Studies should also include other T cell populations to better understand the clinical importance and biological significance of immunosenescence, the researchers say. Studies that aim to control the proportion and function of Vδ2 T cells may be of clinical value. For example, a drug used to treat Crohn’s disease was found to selectively eliminate Vδ2 T cells and so may help moderate inflammatory diseases.
1. Tan, C. T. Y., Wistuba-Hamprecht, K., Xu, W., Nyunt, M. S. Z., Vasudev, A. et al. Vδ2+ and α/β T cells show divergent trajectories during human aging. Oncotarget 7, 44906–44918 (2016).
A*STAR RESEARCH 7
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