Tuesday January 21, 2020

Fatal Fungal Infection Weakens the Immune System- Study

Researchers have now discovered how the fungus knocks out the immune defences.

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Fungus, Immune System
Fungus knocks out the immune defences, enabling a potentially fatal fungal infection to develop. Pixabay

While, healthy people usually have no problem if microorganisms find their way into their bodies as their immune defence system will put the spores out of action, a specific type of fungus can threaten lives with a compromised immune system, such as AIDS patients or who are immunosuppressed following an organ transplantation, says a new study.

Researchers have now discovered how the fungus — Aspergillus fumigatus — knocks out the immune defences, enabling a potentially fatal fungal infection to develop.

Fungus, Immune System
A specific type of fungus can threaten lives with a compromised immune system, such as AIDS patients. Pixabay

Among other factors, it is gliotoxin — a potent mycotoxin — that is responsible for the pathogenicity of Aspergillus fumigatus.

Pathogenicity refers to the ability of an organism to cause disease.

“It was known that this substance has an immunosuppressive effect, which means that it weakens the activity of cells of the immune defence system. However, it had not been clear previously how exactly this happens,” said Oliver Werz, Professor at the University of Jena in Germany.

To achieve this, they brought immune cells into contact with synthetically produced gliotoxin. These cells — neutrophilic granulocytes — represent the first line of the immune defence system.

Fungus, Immune System
Fungus can impair the immune system. Pixabay

Their task is to detect pathogens and eliminate them. As soon as such a cell comes into contact with a pathogen, for example a fungus, it releases specific messenger substances (leukotrienes) into the blood, which attract other immune cells. Once a sufficiently large number of immune cells has gathered, they can render the intruder harmless, findings showed, published in the journal, Cell Chemical Biology.

This does not happen if the pathogen Aspergillus fumigatus is involved. Gliotoxin ensures that production of the messenger substance leukotrieneB4 in the neutrophilic granulocytes is inhibited, so that they are unable to send a signal to other immune cells. This is caused by a specific enzyme (LTA4 hydrolase) being switched off by the mycotoxin.

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“This interrupts communication between the immune cells and destroys the defence mechanism. As a result, it is easy for spores – in this case the fungus – that enter the organism to infiltrate tissues or organs,” said Werz. (IANS)

Next Story

Here’s how HIV Patients Lose Immunity to Smallpox Despite of Vaccinations

HIV patients lose smallpox immunity despite vaccine says a new study by health experts

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HIV immune
The study found the immune systems of HIV-positive women who were on antiretroviral therapy had a limited response when their blood was exposed to the vaccina virus. Pixabay

HIV patients lose immunity to smallpox even though they were vaccinated against the disease as children and have had much of their immune system restored with anti-retroviral therapy, says a new study.

Antiretroviral therapy (ART) is the use of HIV medicines to treat HIV infection. It helps people with HIV live longer, healthier lives and reduces the risk of HIV transmission.

The study, published in the Journal of Infectious Diseases on HIV-associated immune amnesia could explain why people living with HIV still tend to have shorter lives on average than their HIV-negative counterparts despite being on antiretroviral therapy.

The study follows other research recently published in the journals Science and Science Immunology that found the immune systems of children who contracted measles similarly ‘forgot’ their immunity against other illnesses such as influenza.

Immune system
Researchers have found that HIV patients lose immunity to smallpox even though they were vaccinated against the disease. Pixabay

For the study, lead researcher Mark K. Slifka from Oregon Health and Science University in US, and his colleagues compared the T-cell and antibody responses of a total of 100 HIV-positive and HIV-negative women who were vaccinated against smallpox in their youth.

The research team chose smallpox because its last known US case was in 1949, meaning study participants haven’t recently been exposed to its virus, which would have triggered new T-cell and antibody responses.

They found the immune systems of HIV-positive women who were on antiretroviral therapy had a limited response when their blood was exposed to the vaccina virus, which is used in the smallpox vaccine.

Normally, those vaccinated against smallpox have CD4 T cells that remember the virus and respond in large numbers when they’re exposed again.

Previous research has shown smallpox virus-specific CD4 T cells are maintained for up to 75 years after vaccination.

This finding happened despite the fact that antiretroviral therapy works by boosting CD4 T cell counts in HIV-positive patients.

This indicates that while antiretroviral therapy may boost total T cell counts overall, it can’t recover virus-specific T cells generated from prior childhood vaccinations.

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The research team plans to evaluate whether the same phenomenon occurs in HIV-infected men, and if people living with HIV also lose immune memory to other diseases.

Researchers from SUNY Downstate, Georgetown University, Cornell University, University of Southern California and John Hopkins University, also contributed to this study. (IANS)