Cell: Common fungi in the gut are like vaccines and can cause an immune response to prevent pathogenic fungal infections

February 10, 2021 /--- In a new study, researchers from research institutions such as the Weill Cornell School of Medicine in the United States have found that common fungi commonly found in the gut train the immune system to respond to their more dangerous relatives.
failures in this process can make people vulnerable to deadly fungal infections.
it reveals a new twist in the complex relationship between humans and their associated microbes and points the way for the development of new therapies that could help fight rising drug-resistant pathogens.
results were published online February 5, 2021 in the journal Cell under the title "Human gut mycobiota tune immunity via CARD9-dependent induction of anti-fungal IgG antibodies".
from Cell, 2021, doi:10.1016/j.cell.2021.01.016.
the new findings stem from a study of inflammatory bowel disease, which usually causes patients to carry a larger number of fungi in their intestines than normal.
these patients tend to produce strong antibody responses to mannan molecules common to many fungi.
, however, dr.
Iliev, co-author of the paper and an associate professor of gastroenterology and healing immunology at the Weill Cornell School of Medicine, noted that healthy controls in these studies also had certain levels of antifultic antibodies.
Said Dr. Iliev, "There is no actual evidence of fungal infection in the healthy human body we are examining, so we started thinking about the potential function of these antibodies."
" Iliev and his team have developed a platform that allows them to determine which intestinal fungi are targeted by antifellar antibodies in a patient's blood.
they detected a strong reaction to white Candide.
In subsequent experiments in mice, Dr. Iliev and Iliev Lab Doctoral Student Itai Doron found that having white Candide embedded in the intestines of these mice allowed them to produce antibodies against the fungus in the blood, even if they did not develop a blood-based fungal infection.
, the mice's immune cells appear to transport fungal antigens to the spleen, stimulating the production of circulating antibodies in the blood.
Iliev said, "The fungus only trains this immune response."
in patients with suppressed immune systems, such as organ transplants and some cancer patients, fungi in the gut can invade the bloodstream and cause life-threatening infections.
Iliev and his colleagues simulated the process by treating mice with immunosuppressive drugs.
when a Candide species is planted in the intestines of these mice, the fungus moves into the bloodstream, causing a fatal infection.
mice treated with purified antifgyfic antibodies from the supply mice, which were treated with immunosuppressive drugs, to protect them from these infections.
the same strategy also protects them from white Candidas, or the emerging disease-ing yeast candida aurius, which has become a major cause of fungal disease in immunosuppressive patients and the elderly in recent years.
Iliev team, in collaboration with researchers at France's National Institute of Health and Medical Research (INSERM), also studied serums from patients with mutations in the CARD9 gene.
mutation affects a key bridging protein in the immune system, making affected people vulnerable to severe fungal infections.
Iliev team found that the serums of these patients lacked antifellar antibodies that were usually observed in the serums of patients without the mutation.
in mice have confirmed that CARD9 plays a crucial role in initiating the production of antifellar antibodies.
these results suggest that normal intestinal fungi may act as an intestinal vaccine to prevent fungal infections in healthy people by inducing the production of antibodies in the blood against a variety of potentially pathogenic fungi.
when these fungi enter the bloodstream, these antibodies bind to them and target them to damage immune system cells.
in patients with suppressed immunity, these antifellar antibodies may decline, making them vulnerable to fungal infections.
new treatments involving stimulating the production of antifulgal antibodies or injecting these purified antibodies directly into a patient's blood may help fight these increasingly common fungal infections.
this approach works, it would be a welcome development.
Iliev said, "Many fungal infections in immunosuppressive and elderly patients occur when pathogenic Candide species are transferred from the gastrointestinal tract, and survival rates after the spread of the whole body are alarmingly low.
" (Bioon.com) Reference: 1. Itai Doron et al. Human gut mycobiota tune immunity via CARD9-dependent induction of anti-fungal IgG antibodies. Cell, 2021, doi:10.1016/j.cell.2021.01.016.2.Fungi in the Gut Prime Immunity Against Infection