A global increase in antioxidant defences of the body may delay ageing and age-related diseases
The paper, published today in the journal ‘Nature
Communications’, offers a new view on the role of antioxidants in health and
longevity
For the first time, scientists have enhanced the global
antioxidant capacity of cells, leading to a delay in ageing and to an increase
in longevity
Research points to the use of drugs related to vitamin B3 as
a possible method to delay ageing and associated diseases
The gradual accumulation of cell damage plays a very
important role in the origin of ageing. There are many sources of cellular
damage, however, which ones are really responsible for ageing and which ones
are inconsequential for ageing is a question that still lacks an answer.
The Oxidative Hypothesis of Ageing — also known as the Free
Radicals Hypothesis — was put forward in 1956 by Denham Harman. Since then, the
large majority of attempts to prove that oxidative damage is relevant for
ageing have failed, including multiple clinical trials in humans with
antioxidant compounds. For this reason, although the accumulation of oxidative
damage with ageing is undisputed, most scientists believe that it is a minor,
almost irrelevant, cause of ageing.
However, this may change in light of the recently published
observations. A group of scientists from the Spanish National Cancer Research
Centre (CNIO) headed by Manuel Serrano, in collaboration with a group from the
University of Valencia, directed by José Viña, and researchers at IMDEA Food
from Madrid, have tried to increase the global antioxidant capacity of the
cells, rather than just one or a few antioxidant enzymes. To achieve this
global improvement in the total antioxidant capacity, researches have focused
on increasing the levels of NADPH, a relatively simple molecule that is of key
importance in antioxidant reactions and that, however, had not been studied to
date in relation to ageing.
The researchers used a genetic approach to increase NADPH
levels. In particular, they generated transgenic mice with an increased
expression throughout their bodies of one of the most important enzymes for the
production of NADPH, namely, glucose-6-phosphate dehydrogenase (or G6PD).
The results, published today in the journal Nature
Communications, indicate that an increase in G6PD and, therefore, in NADPH,
increases the natural antioxidant defences of the organism, protecting it from
oxidative damage, reducing ageing-related processes, such as insulin
resistance, and increasing longevity.
ANTIOXIDANTS THAT DELAY AGEING
"As anticipated, the cells in these transgenic animals
are more resistant to highly toxic artificial oxidative treatments, thus
proving that an increase in G6PD really improves antioxidant defences,"
explains Sandrina Nóbrega-Pereira, first author of the study and currently a
researcher at the Institute of Molecular Medicine of the University of Lisbon.
Furthermore, when researchers analysed long-lived transgenic
animals, they noted that their levels of oxidative damage were lower than in
non-transgenic animals of the same age. They also studied the propensity of
these animals to develop cancer and found no difference, suggesting that
enhancing G6PD activity does not have an important effect on the development of
cancer.
The greatest surprise for the team was when they measured
the ageing process in the transgenic mice: the animals with a high G6PD
expression and, therefore, high levels of NADPH, delayed their ageing,
metabolised sugar better and presented better movement coordination as they
aged. In addition, transgenic females lived 14% longer than non-transgenic
mice, while no significant effect on the longevity of males was observed.
"This increased longevity, although modest, is striking
taking into account that until now attempts to increase longevity by
manipulating individual antioxidant enzymes had failed," said Pablo
Fernández-Marcos, co-first author of the study and researcher at IMDEA Food.
OVERALL INCREASE IN THE ANTIOXIDANT CAPACITY OF CELLS
Perhaps the key is that the researchers involved in this
paper enhanced all antioxidant enzymes in a comprehensive manner.
"Compared to the traditional approach of administering antioxidants that
react directly with oxygen, we have stimulated all the cell’s natural
antioxidant mechanisms by raising G6PD levels, and its by-product, NADPH,"
emphasizes Mari Carmen Gómez-Cabrera, co-author of the paper and researcher at
the University of Valencia.
Based on these results, the authors of the study point to
the use of pharmacological agents or nutritional supplements that increase
NADPH levels as potential tools for delaying the ageing process in humans and
age-related diseases, such as diabetes, among others. More specifically,
vitamin B3 and its derivatives are responsible for the synthesis of NADPH
precursors and are suitable candidates for future studies.
The study was funded by the Spanish Ministry of Economy and
Competition, the Community of Madrid, the European Research Council, the Botín
Foundation and Banco Santander through Santander Universities, the Spanish
Association Against Cancer (AECC), the Ramón Areces Foundation, the AXA
Foundation, the Spanish Ageing and Fragility Network RETICEF, and the European
Regional Development Fund.
Reference article:
G6PD protects from
oxidative damage and improves healthspan in mice. Sandrina Nóbrega-Pereira,
Pablo J. Fernandez-Marcos, Thomas Brioche, Mari Carmen Gomez-Cabrera, Andrea
Salvador-Pascual, Juana M. Flores, Jose Viña, Manuel Serrano. Nature
Communications (2016). doi: 10.1038/ncomms10894