2023-07-22 07:10:45
Japan University of Tokyo animal experiment results “high body temperature, increased resistance to pathogenic virus infection”
Enter 2023.07.22 16:10 Modify 2023.07.22 11:27 Hits 1,072 Enter 2023.07.22 16:10 Modify 2023.07.22 11:27 Hits 1,072
Active physical activity, such as exercise, generates heat from the muscles and raises the body temperature. This promotes the activity of immune cells and enhances immunity. The rise in body temperature due to disease has a different mechanism. [사진=게티이미지뱅크]Research has shown that a slightly higher body temperature can increase resistance to viral infections such as influenza A and COVID-19.
The University of Tokyo Medical Research Institute in Japan revealed that this was the result of animal experiments such as mice and Syrian hamsters.
Dr. Takeshi Ichinohe, a viral epidemiologist and co-author of the study, said, “It turns out that a higher body temperature may be closely related to an improved ability of gut microbes to fight infections.”
According to the results of previous clinical studies, the average body temperature of the elderly is lower than that of the younger people, and the risk of infection with viruses such as seasonal respiratory diseases is higher. Normally, the normal average body temperature is 36-37°C, but it varies from person to person. The effects of elevated body temperature on fighting viral infections are not well understood.
The research team examined mice exposed to 4°C, 22°C, and 36°C, respectively, one week before influenza virus infection, and then infected these mice with the virus. As a result, most of the mice exposed to low temperature (4°C) died of severe hypothermia, while the mice exposed to high temperature (36°C) survived well without being infected even when the virus dose was increased.
“Mice exposed to high temperatures had elevated basal body temperatures of more than 38°C and were able to produce more bile acids in a manner dependent on the gut microbiome,” explains Dr. Takeshi. Bile acids play an important role in regulating the immune response and protecting the host from viral infection.
The research team analyzed that the reason why mice with high basal body temperature are not easily infected with the influenza virus is that deoxycholic acid (DCA) signals suppress viral replication and neutrophil (neutrophil) dependence in intestinal microbes and plasma membrane-bound receptors, Takeda G-protein coupled receptor 5 (TGR5). Neutrophils are produced by hematopoietic stem cells in the bone marrow. It accounts for 55-70% of mammalian leukocytes and functions as an innate immune system.
During the experiment, the mice infected with the flu virus lowered their body temperature in regarding 4 days. Cooled down, these mice hugged each other to keep warm.
Similar results were obtained following replacing the flu virus with the Corona-19 (SARS-CoV-2) virus. In addition, Syrian hamsters, not mice, also showed increased host resistance to flu virus and COVID-19 virus infection when their body temperature was higher than 38°C. Although it is different from human body temperature, when the body temperature rises, the reaction of major intestinal microorganisms is promoted, resulting in the production of secondary bile acids.
The research team concluded that when the intestinal microflora is activated due to body temperature, the serum level of bile acids increases, which can suppress viral replication and inflammatory responses caused by flu and COVID-19 infection.
The results of this study (High body temperature increases gut microbiota-dependent host resistance to influenza A virus and SARS-CoV-2 infection) were published online in Nature Communications.
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