Losing Weight Helps With Sleeping Sickness

Scientists revealed a novel tactic used by the host to manage Trypanosoma brucei infection, which causes sleeping sickness.

The parasite that causes nagana in cattle and sleeping sickness in people is called Trypanosoma brucei, and it continues to be a severe economic burden and public health issue in Sub-Saharan Africa.

The parasite illness known as sleeping sickness, or human African trypanosomiasis, is spread via vectors. It is brought on by parasites of the genus Trypanosoma that are transferred to people by the biting of tsetse flies, which diseased people or animals have infected.


Only a few species of tsetse flies in sub-Saharan Africa carry the illness, and the most vulnerable rural communities depend on agriculture, fishing, animal husbandry, or hunting.

The sickness may affect a single village or an entire area, and the incidence varies from one community to the next.

Now, novel therapeutic approaches can be developed by comprehending the afflicted organism's reaction as the sickness progresses. The findings, published in the journal Nature Microbiology and headed by Luísa Figueiredo, group leader at the Instituto de Medicina Molecular João Lobo Antunes, say the parasites enter the mammalian hosts through interstitial spaces after being bitten by an infected tsetse fly. If the infection is not treated, the host will perish.

Some years ago, our laboratory found that the parasite that causes sleeping sickness, Trypanosoma brucei, accumulates disproportionately high numbers in the adipose tissue. We found this very intriguing, and directed our research to the understanding of how adipose tissue colonization affects disease progression.

-Leader of the lab Luísa Figueiredo

She adds that the accumulation of the parasites in these tissues is accompanied by weight loss. The team found that weight loss is mainly due to the loss of adipose tissue by lipolysis. This metabolic process breaks triacylglycerols into their constituent molecules, including free fatty acids.

The loss of fatty tissue can occur due to many different signals.

The team found that, in this case, the lipolysis is largely induced by the host immune response to the infection. The study's first author, Henrique Machado, says they infected immunocompromised mice and mice with impaired lipolysis and saw that, in both cases, there was less body weight loss despite having a higher number of parasites.

The authors then set out to determine whether lipolysis aids in the development of the illness.


According to Figueiredo, the scientists discovered that the diseased mice live longer when fatty tissue is lost by lipolysis. This, together with the fact that the parasite population is controlled by lipolysis, suggests that this reaction serves some protective function.

The team concludes that it's intriguing that this protective effect results from producing free fatty acids during lipolysis, which are poisonous to parasites and cause parasite death. It appears the host body sacrifices itself to eradicate the parasites by decreasing fat mass.

Since the significance of this tissue was previously unknown, these results might lead to an entirely new line of therapies for sleeping sickness and nagana that target the infection in the adipose tissue.


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