It has long been known that while extremely low temperatures can be harmful to organisms, a moderate reduction in body temperature can have very positive effects.
For example, a lower body temperature prolongs the longevity of cold-blooded animals such as worms, flies or fish, whose body temperature fluctuates with the temperature of the environment. And the same phenomenon applies to mammals as well, which maintain their body temperatures within a narrow range regardless of what cold or warm whatever your environment is.
Specifically, cold activates a cellular cleansing mechanism that breaks down harmful protein aggregates responsible for various diseases associated with aging. In fact, in recent years, various studies on model organisms have already shown that life expectancy increases significantly when body temperature is reduced.
However, in many areas it is still not clear how exactly it works. Now, a team of researchers from the Group of Excellence in Research on Aging (CECAD) of the University of Cologne (Germany) has discovered one of the mechanisms responsible. The study has appeared in ‘Nature Aging’.
ALS and Huntington’s Disease
Professor David Vílchez and his work group used a non-vertebrate model organism, the ‘Caenorhabditis elegans’ nematode, and cultured human cells. Both carried the genes for two neurodegenerative diseases that often appear in old age: Amyotrophic Lateral Sclerosis (ALS) and Huntington’s disease.
Both diseases are characterized by the accumulation of noxious and harmful protein deposits, the so-called pathological protein aggregates. In both model organisms, cold actively removed protein clumps, thus preventing the protein aggregation which is pathological in both ALS and Huntington’s disease.
More specifically, the scientists explored the impact of cold on the activity of proteasomes, a cellular mechanism It removes damaged proteins from cells. The research revealed that a proteasome activator mitigated deficits caused by aging in both nematode and human cells.
In both cases, it was possible to activate the activity of the proteasome by means of a moderate decrease in temperature. “Taken together, these results show how, throughout evolution, cold has retained its influence on proteasome regulationwith therapeutic implications for aging and diseases associated with it”, stated Professor Vílchez.
Aging is one of the main risk factors for several neurodegenerative diseases associated with protein aggregation, such as Alzheimer’s, Parkinson’s, Huntington’s disease and ALS. In this regard, Vílchez has stated that these results can be applied to other age-related neurodegenerative diseases, as well as to other animal species.
A key finding was that proteasome activity can also be increased by gene overexpression of the activator. In this way, disease-causing proteins can be eliminated even at the normal body temperature of 37 degrees Celsius. Thus, these results may provide therapeutic targets for aging and diseases associated with it.
Temperature reduction and longevity
In this way, the nematode lives much longer if it is moved from the standard temperature of 20 degrees Celsius to a cooler temperature of 15 degrees Celsius. And in mice, a slight drop in body temperature of just 0.5 degrees significantly prolongs their lives. This supports the hypothesis that temperature reduction plays a central role in longevity in the animal kingdom and is a well-conserved evolutionary mechanism.
Even in humans, a correlation between body temperature and life expectancy has been observed. The normal temperature of the human body ranges between 36.5 and 37 degrees Celsius. While a sharp drop in body temperature below 35 degrees causes hypothermiahuman body temperature fluctuates slightly during the day and even reaches a cool 36 degrees during sleep.
Interestingly, a previous study indicated that human body temperature has steadily fallen by 0.03 degrees Celsius per decade since the Industrial Revolution, which suggests a possible relationship with the progressive increase in human life expectancy in the last 160 years.