Meeting a microbe in the morning or in the evening: Is it all the same?

September 8, 2017, McGill University
Credit: McGill University

Does the time of day matter when our body is infected by a parasite? According to new research from McGill University, it matters a great deal.

Our body works differently at different times of the day following our internal clocks. Researchers from McGill University and the Douglas Mental Health University Institute have now established that parasitic infections are also controlled by these clocks. The severity of a microbe's will thus vary whether it is encountered during the day or at night, a discovery that scientists believe could pave the way to new treatment and prevention strategies for parasitic infections.

Nicolas Cermakian, a professor at McGill's Department of Psychiatry and researcher at the Douglas Institute, made the discovery using Leishmania, a parasite that causes leishmaniasis and that is transmitted at night by the female sandfly. Every year, Leishmania infects about 1 million people, killing thousands and leaving many others with scars. Although the parasite is mostly located in tropical areas, climate change could spread Leishmania far beyond where it is found today. The parasite has already spread to certain parts of southern Europe.

When mice were injected with the parasite, Professor Cermakian's team discovered that their immune response varied greatly depending on what time of day the infection occurred.

"Our previous work showed that our immune system has its own biological clocks. Our body's defence mechanisms are more or less active at different times of the day," says Nicolas Cermakian, lead author of the new study published in Scientific Reports in collaboration with McGill/RI-MUHC Professor Martin Olivier and Professor Nathalie Labrecque of Université de Montréal and Maisonneuve-Rosemont Hospital research centre.

Silke Kiessling, a former postdoctoral student in Professor Cermakian's lab, found that Leishmania's infection was more effective in the early night, a time when the immune response to the parasite was the strongest.

But why would the parasite be transmitted by a fly that bites at the exact time when our defences are at their strongest? Simply put, the parasite thrives when it elicits a strong , attracting inflammatory cells it uses to multiply (macrophages and neutrophils) to the infection site.

"We already knew that viral and bacterial infections were controlled by our immune system's circadian rhythms, but this is the first time this is shown for a , and for a vector-transmitted infection," Professor Cermakian adds.

Tools for better treatment and prevention

Professor Cermakian's team will now try to better define how Leishmania's circadian rhythm is controlled at the molecular and cellular levels. As a first step, they already found that the clock within cells of the immune system is directing the daily rhythm of response to Leishmania.

A better understanding of how the circadian clock controls Leishmania infection could contribute to the development of new therapeutics and better prevention approaches. Working out how time regulation of host-parasite interactions are controlled, Cermakian says, might also be useful in the fight against other diseases transmitted by insects.

Explore further: Targeting the biological clock could slow the progression of cancer

More information: Silke Kiessling et al. The circadian clock in immune cells controls the magnitude of Leishmania parasite infection, Scientific Reports (2017). DOI: 10.1038/s41598-017-11297-8

Related Stories

Targeting the biological clock could slow the progression of cancer

February 16, 2017
Does the biological clock in cancer cells influence tumour growth? Yes, according to a study conducted by Nicolas Cermakian, a professor in McGill University's Department of Psychiatry.

How the leishmania parasite sabotages the immune response

October 12, 2016
An international collaborative of researchers has identified a mechanism that allows the leishmania parasite, which causes leishmaniasis, to evade the immune system and thereby produce infection. The study, published in Immunity, ...

The human parasite Leishmania is a probiotic for the fly that carries it

July 22, 2014
The Leishmania parasite, which causes the human disease leishmaniasis, acts as a probiotic in the insect that transmits it to humans, protecting them from bacterial disease. Findings published in the open access journal Parasites ...

Recommended for you

Scientists shine new light on link between obesity and cancer

November 12, 2018
Scientists have made a major discovery that shines a new, explanatory light on the link between obesity and cancer. Their research confirms why the body's immune surveillance systems—led by cancer-fighting Natural Killer ...

Fecal transplant effective against immunotherapy-induced colitis

November 12, 2018
For the first time, transplanting gut bacteria from healthy donors was used to successfully treat patients suffering from severe colitis caused by treatment with immune checkpoint inhibitors (ICIs). The study from The University ...

Two-pronged device enables maverick immune cells to identify and kill cancers

November 12, 2018
Immune cells called Gamma Delta T cells can act independently to identify and kill cancer cells, defying the conventional view of the immune system, reveals new research from the Francis Crick Institute and King's College ...

Suicide handshakes kill precursor T cells that pose autoimmune dangers

November 12, 2018
Ball lands in cup; cup triggers spring; spring clamps lever onto ball and holds it tight. That's a rough description of newly discovered cellular mechanisms that eliminate T cells that may cause autoimmune disorders.

Exosomes 'swarm' to protect against bacteria inhaled through the nose

November 12, 2018
Bacteria are present in just about every breath of air we take in. How the airway protects itself from infection from these bacteria has largely remained a mystery—until now. When bacteria are inhaled, exosomes, or tiny ...

Researchers find new pathway to regulate immune response, control diseases

November 9, 2018
Researchers at The University of Texas at Arlington have found a potential new pathway to regulate immune response and potentially control inflammatory diseases of the central nervous system such as meningitis and sepsis.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.