Our fountain of youth

One of the oldest desire of man kind is to increase its life expectancy and if possible be immortal. In pursuit of this dream countless have spent their lives searching for elixir of immortality to fountains of youth, often leading to pain and animosity between fellow humans.
Japan, a country owing to its cultural, behavioral and numerous genetic factors has been blessed with many centenarians and currently has the greatest number of known centenarians of any nation with 67,824 according to their 2017 census, along with the highest proportion of centenarians at 34.85 per 100,000 people. Thus Japan becomes the primal choice for conducting studies reflecting on the secrets of longer life  and it can be performed with accuracy and a larger statistical sample size compared to other nations.
In a latest set of findings research teams of scientists from the RIKEN Center for Integrative Medical Science (IMS) and Keio University School of Medicine in Japan have shown us that all the while we have been looking in the wrong direction and the solution and clue to long life was within our body's own defense / the immune system.
   Supercentenarians -- meaning people over the age of 110 --as their study interest  the teams have discovered an interesting finding that the supercentenarians proved to be an unique group of people having a higher count of specific immune cells cytotoxic CD4+ T-cells, when they compared their cell count with a group of supercentenarians and younger controls. They acquired a total of 41,208 cells from seven supercentenarians (an average of 5,887 per subject) and 19,994 cells for controls (an average of 3,999 per subject) from five controls aged in their fifties to eighties.
The study revealed two interesting findings:

• The number of B-cells was lower in the supercentenarians, the number of other T-cells were approximately the same.
• Supercentenarians had a very high level of cytotoxic T-cells that can kill other cells, sometimes amounting to 80 percent of all T-cells, compared to just 10 or 20 percent in the controls.
• Usually the T-cells with markers known as CD8 are known to show cytotoxicity, while those with the CD4 marker are not cytotoxic, so the authors first thought that perhaps CD8-positive cells were increased, however that turned out to not be the case. Rather, it seems that the CD4-positive cells of the supercentenarians had acquired cytotoxic status.
• On the other hand the younger participants had less population of CD4+ T-cells, thus indicating that it might be a characteristic of the supercentenarians.

​ To investigate the origin of these special cells, the team examined the blood cells of two supercentenarians in detail, and found that they had arisen from a process of clonal expansion, meaning that many of the cells were the progeny of a single ancestor cell.
Kosuke Hashimoto of IMS, the first author of the paper, expressed the team's stand as "We were especially interested in studying this group of people, because we consider them to be a good model of healthy aging, and this is important in societies like Japan where aging is proceeding rapidly."
IMS Deputy Director Piero Carninci, one of the leaders of the groups, says, "This research shows how single-cell transcription analysis can help us to understand how individuals are more or less susceptible to diseases. CD4-positive cells generally work by generating cytokines, while CD8-positive cells are cytotoxic, and it may be that the combination of these two features allows these individuals to be especially healthy. We believe that this type of cells, which are relatively uncommon in most individuals, even young, are useful for fighting against established tumors, and could be important for immunosurveillance. This is exciting as it has given us new insights into how people who live very long lives are able to protect themselves from conditions such as infections and cancer."
Their research, is published in journal of Proceedings of the National Academy of Sciences (PNAS), and the study was performed by a collaboration including scientists from the RIKEN Center for Integrative Medical Sciences and Keio University School of Medicine.

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References

1. Kosuke Hashimoto, Tsukasa Kouno, Tomokatsu Ikawa, Norihito Hayatsu, Yurina Miyajima, Haruka Yabukami, Tommy Terooatea, Takashi Sasaki, Takahiro Suzuki, Matthew Valentine, Giovanni Pascarella, Yasushi Okazaki, Harukazu Suzuki, Jay W. Shin, Aki Minoda, Ichiro Taniuchi, Hideyuki Okano, Yasumichi Arai, Nobuyoshi Hirose, Piero Carninci. Single-cell transcriptomics reveals expansion of cytotoxic CD4 T cells in supercentenarians. Proceedings of the National Academy of Sciences, 2019; 201907883 DOI: 10.1073/pnas.1907883116
2. Original Article published in RIKEN, the content is edited for style and length.
3. Image courtesy: Pixabay