At a glance

This study:

• Demonstrates that a specific fluorescence emitted from the body of Caenorhabditis elegans increases with age and that the fluorescence is derived from glycation end products, which are indicators of aging.
• Develops a noninvasive method for monitoring fluorescent substances in the body.
• Develops a simple experimental system to search and evaluate materials with anti-glycation activity using this fluorescence measurement method.

Summary

　Professor Emeritus Yoshikazu Nishikawa of Osaka City University's Graduate School of Human Life Science (at the time of the research) (currently a specially appointed professor at Tezukayamagakuin University), Research Associate Tomomi Komura of the Graduate School of Human Life and Environmental Sciences, Nara Women's University (at the time of the research) (also a visiting researcher at Osaka City University, currently a Research Associate at the University of Hyogo's Faculty of Environment and Humanity), Associate Professor Mikihiro Yamanaka of the Faculty of Agriculture, Tokai University, Associate Professor Koji Nishimura of the Faculty of Life and Environmental Sciences, Shimane University, and Dr. Keita Hara of Air Water Inc., using C. elegans, which is often used as a model animal in aging research, have found that a substance that emits a specific fluorescence in vivo increases with age. The fluorescence is derived from advanced glycation end products (AGEs) and correlates with the life expectancy of C. elegans. The measurement technology of this model is expected to be utilized for the search and evaluation of anti-glycation materials in the future.

　The results of this research were published in the international academic journal npj Aging and Mechanisms of Disease on Monday, June 7, 2021.?

?　　　　　　　 　? ? ? ? ? ? ? ? ? ? ?Figure 1: C. elegans

?Background of the research

?　As the global population ages and preventive measures against age-related diseases such as dementia and cancer become increasingly important, glycation in the body is attracting attention as an important risk factor for aging and lifestyle-related diseases. It is known that the amount of AGEs in the body increases with aging and age-related diseases such as diabetes and arteriosclerosis, and measuring the amount of AGEs in the body is expected to be an indicator for predicting aging and age-related diseases. However, experiments on natural aging using humans and mammals require several years, and AGEs detection methods are mainly invasive blood tests, which require expensive and special experimental operations using antibodies, such as ELISA^*1. The relationship between glycation and aging in the body is still unclear and a simple method for evaluation has not yet been established.

　This research group hypothesized that AGEs could be indirectly assessed by measuring the fluorescence of some AGEs, and succeeded in clarifying the relationship between AGEs and fluorescence in vivo using the model organism Caenorhabditis elegans^*2, and in developing a high-throughput^*3 evaluation method.?

^*1 ELISA: An immunological assay method using antibodies to quantify trace amounts of biological substances in samples using antigen-antibody reactions.

^*2 C. elegans (Fig. 1): a small worm with a body length of about 1 mm and a cell count of about 1,000. It has a variety of tissues including reproductive, digestive, nervous, and muscular systems. Since about 70% of human genes are also present in C. elegans, they are used in various research fields to understand human biological mechanisms.??????????????????????????????????????????

^*3 High-throughput: A method for finding useful things from a huge number of samples quickly, efficiently, and at a low cost.

Research outline

　In this study, the research team first conducted fluorescence spectrum analysis using protein extracts from young and old C. elegans and found that specific fluorescence was enhanced in protein extracts from old worms (Fig. 2). They developed a method to detect the fluorescence in vivo and following the same worm over time, they found that the fluorescence value increased with age. In addition, they found that fluorescence decreased in long-lived C. elegans mutants and in ones treated with rifampicin, which has an anti-glycation effect, the lifespan was extended, while fluorescence increased in C. elegans treated with ribose, which has a strong glycation effect. Furthermore, when protein extracts from young C. elegans, which did not fluoresce, were artificially glycated, they fluoresced at the same wavelength as old C. elegans, suggesting a strong relationship between this fluorescence, AGEs, and aging. As a result of comparison by analysis of all proteins expressed in old and young worms and observing this with fluorescence microscopy, the team found that this fluorescence was derived from AGEs-derived vitellogenin^*4 (Fig. 3).

　This suggests that the fluorescence at specific wavelengths emitted from the body of the worm reflects AGEs, and by measuring this fluorescence, the amount of AGEs in the body can be estimated, suggesting the possibility of using it as an indicator of aging.

^*4 Vitellogenin: A precursor of an egg yolk protein, involved in the formation of an egg yolk.

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Figure 2: Fluorescence intensity of young and old C. elegans

　　????? (Red indicates higher fluorescence intensity.)

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Figure 3: Fluorescence microscope images of young and old C. elegans

(fluorescent area: blue)

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In the future

　Since the body of C. elegans is transparent, the fluorescence intensity inside the body can be observed while the animal is still alive and they have a life span of about three weeks. In the future, the method laid out in this research is expected to be utilized on C. elegans to search for food materials related to anti-glycation and anti-aging.

?Funding

　This work was supported by a Grant-in-Aid for Scientific Research (19K15788) from the Japan Society for the Promotion of Science (JSPS), the Futaba Electronics Memorial Foundation, and the Mishima-Kaiun Memorial Foundation.

Journal information

Journal: ?npj Aging and Mechanisms of Disease

Article title: Autofluorescence as a non-invasive biomarker of senescence and advanced glycation end products in Caenorhabditis elegans

Authors: Tomomi Komura, Mikihiro Yamanaka, Kohji Nishimura, Keita Hara, and Yoshikazu Nishikawa?

URL: https://www.nature.com/articles/s41514-021-00061-y