Researchers at McGill University have made a discovery that could improve the prevention and treatment of malaria and other parasitic diseases.
Research teams from McGill University, the Douglas Research Centre, and the Research Institute of the McGill University Health Centre found that mice infected by malaria-causing parasites in the middle of the night exhibited less severe disease symptoms and limited parasite proliferation compared to those infected during the day.
Illustration from Pixabay
Malaria is a mosquito-borne disease affecting hundreds of millions of people worldwide, causing more than half a million deaths each year, most of whom are children. Cerebral malaria is the deadliest form of the disease.
These findings could lead to the development of new treatments that take circadian rhythms into account.
The interaction between host and parasite circadian rhythms
Circadian rhythms are cycles in physiology and behavior that last about 24 hours, the time it takes the Earth to complete one rotation, and they persist even in the absence of external time cues. These rhythms are controlled by a biological clock located in the brain, as well as other clocks in most organs and cells of the body.
"We studied the effect of the interaction between the host's circadian rhythms and those of the malaria parasites on disease severity and the host's ability to fight infection," explains Priscilla Carvalho Cabral, newly awarded a PhD from McGill University, who led the experiments described in two recent studies on the subject.
"The observed differences in host responses to infection depending on the time of day suggest that circadian rhythms influence disease progression," says Nicolas Cermakian, director of the Laboratory of Molecular Chronobiology and lead author supervising the two studies. "The role of these immune biological clocks in malaria had never been investigated before."
Important new findings
In parasites and their animal hosts, as well as in most living organisms, circadian rhythms regulate many physiological functions. We already know, for example, that the replication of malaria parasites inside the host's red blood cells follows a daily rhythm.
Previous work by the same team demonstrated that another serious parasitic disease, leishmaniasis, was influenced by the host's biological clocks: the timing of infection affects parasite replication as well as the immune response. The new studies showed the same is true for cerebral malaria.
"The new data we've obtained are significant as the mechanisms governing the rhythms of disease susceptibility, particularly to parasitic diseases, remain largely unknown," says Martin Olivier, director of the Host-Parasite Interaction Study Laboratory, professor in the Department of Microbiology and Immunology at McGill University, and co-author of the two studies.
The studies
The article "
Time of Day and Circadian Disruption Influence Host Response and Parasite Growth in a Mouse Model of Cerebral Malaria," by Priscilla Carvalho Cabral et al., was published in
iScience.
DOI: https://doi.org/10.1016/j.isci.2024.109684
The article "
Circadian Control of the Response of Macrophages to Plasmodium spp.-Infected Red Blood Cells," by Priscilla Carvalho Cabral et al., was published in
ImmunoHorizons.
DOI: https://doi.org/10.4049/immunohorizons.2400021