How gut microbiota affects ability to fight infections like coronavirus and flu

this respiratory infectious diseaseas Influenza and Coronaviruscan cause Serious photos and death. Therefore, vaccination is necessary. More than 3,100 people worldwide died from coronavirus infections last month.

A group of researchers from University of Tokyoget Discovery of a relationship between high body temperature and the body’s greater resistance to viruses. They published a study in the journal Nature Communications.

More commonly, infections such as the flu and COVID-19 affect older adults, leading to more severe illness. This can be explained by the fact that: These people’s white blood cells or monocytes have altered signaling Induces type I interferon (IFN) in response to influenza virus infection. However, the role of other age-related changes is unclear.

Scientists at the University of Tokyo have worked to investigate this unknown and have narrowed the gap by linking higher body temperature to greater capacity. Fighting infections from gut microbes or microbiota.

For the experiments, the team used mice that had been exposed to temperatures of 4°C, 22°C or 36°C a week before influenza virus infection. After induction of virus infection, most cold-stressed mice died due to severe hypothermia, while heat-stressed mice were highly resistant to infection even with increased virus doses.

“The animals’ basal body temperature increased above 38°C, which allowed them to produce more bile acids in a gut microbiota-dependent manner,” he said. Takeshi Ichito of Department of Viral Infection, The University of Tokyo.

The authors speculate that deoxycholic acid (DCA) signaling from the gut microbiota and its plasma membrane-bound receptor Takeda G-protein-coupled receptor 5 (TGR5) is enhanced by inhibiting viral replication and neutrophil-dependent tissue damage Host resistance to HIV infection. .

While conducting these experiments, the team noticed that mice infected with the influenza virus showed a drop in body temperature and huddled together for warmth nearly four days after infection.

They also recorded similar results after switching from influenza virus to SARS-CoV-2 coronavirus, and the conclusions of the study were also validated using the Syrian hamster model.

Their experiments showed that body temperature above 38°C can enhance the host’s resistance to influenza virus and SARS-CoV-2 infection.

Additionally, they found that elevated body temperature catalyzed key gut microbial responses that lead to the production of secondary bile acids. These acids can modulate the immune response and protect the host from viral infection.

Dr. Ichinohe explained, “DCA and its farnesoid X nuclear receptor (FXR) agonist protected Syrian hamsters from lethal SARS-CoV-2 infection. Furthermore, compared with patients with less severe disease, patients with moderate Certain bile acids were reduced in the plasma of COVID-19 patients with stage I/II disease.”

The team then performed a comprehensive analysis to gain insight into the precise mechanisms by which gut metabolism mediates host resistance to viral infection in heat-exposed rodents. In addition, they identified the role of secondary bile acids and their receptors in alleviating viral infection.

“Our finding that certain bile acids were reduced in the plasma of patients with moderate COVID-19 I/II may shed light on variability in clinical disease manifestations in humans and provide ways to mitigate infection outcomes,” Ichinohe noted.

Published studies have shown that hyperthermia-dependent activation of the gut microbiota increases serum and intestinal bile acid levels. The researchers clarified that this inhibits viral replication and the inflammatory response following influenza and SARS-CoV-2 infection.

Contributing scientists to the study were Minami Nagai, Miyu Moriyama, Chiharu Ishii, Hirotake Mori, Hikaru Watanabe, Taku Nakahara, Takuji Yamada, Dai Ishikawa, Takamasa Ishikawa, Akiyoshi Hirayama, Ikuo Kimura, Akihito Nagahara, Toshio Naito and Shinji Fukuda.

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