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Sci Rep. 2017 Sep 7;7(1):10892. doi: 10.1038/s41598-017-11297-8.

The circadian clock in immune cells controls the magnitude of Leishmania parasite infection.

Author information

Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada.
Chair of Nutrition and Immunology, Technical University of Munich, Freising, Germany.
Maisonneuve-Rosemont Hospital Research Centre, Department of Medicine and Department of Microbiology, Infectiology and Immunology, University of Montreal, Montreal, Quebec, Canada.
Department of Medicine, Microbiology and Immunology, McGill University, and Infectious Diseases and Immunity in Global Health Program, Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada.
Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada.


The intracellular parasite Leishmania uses neutrophils and macrophages as host cells upon infection. These immune cells harbour their own intrinsic circadian clocks, known to influence many aspects of their functions. Therefore, we tested whether the host circadian clocks regulate the magnitude of Leishmania major infection in mice. The extent of parasitic infection varied over 24 h in bone marrow-derived macrophages in vitro and in two different in vivo models, footpad and peritoneal cavity infection. In vivo this was paralleled by time of day-dependent neutrophil and macrophage infiltration to the infection site and rhythmic chemokine expression. Thus, rhythmic parasitic infection observed in vivo was likely initiated by the circadian expression of chemoattractants and the subsequent rhythmic infiltration of neutrophils and macrophages. Importantly, all rhythms were abolished in clock-deficient macrophages and when mice lacking the circadian clock in immune cells were infected. Therefore we demonstrated a critical role for the circadian clocks in immune cells in modulating the magnitude of Leishmania infection. To our knowledge this is the first report showing that the circadian clock controls infection by protozoan parasites in mammals. Understanding the timed regulation of host-parasite interactions will allow developing better prophylactic and therapeutic strategies to fight off vector-borne diseases.

[Indexed for MEDLINE]
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