One study reports that nausea from food toxins and some chemotherapy drugs is caused by a similar nerve message. This discovery paves the way for new drugs capable of reducing this very important side effect of the treatment of several cancers.
During food poisoning, the presence of contaminated food (usually with a bacterial toxin) is detected by the brain and triggers a series of defensive responses. These responses include motor reflexes such as retching and vomiting to promote the expulsion of the toxin from the body, as well as an unpleasant feeling of being sick (nausea) which serves to develop an aversion to the flavors responsible. of this unfortunate episode and thus prevent future ingestion of the same toxin. It is for this reason that a person who has been ill following the ingestion of a contaminated food can be disgusted for long periods by the mere thought of eating this food again.
Major side effects
Although essential for survival, these defensive responses to protect the body from toxins paradoxically represent the main cause of the serious side effects of chemotherapy drugs. Certain drugs commonly used to treat several types of cancers (cisplatin, carboplatin, cyclophosphamide, irinotecan and several others) do indeed cause nausea and vomiting in a significant number of patients, and although antiemetic drugs can reduce these side effects, it nonetheless, they represent a major problem for the quality of life of patients and can reduce their adherence to treatment (1).
Nerve circuits
Although the phenomenon is very common, the way the brain receives the alarm signal and then sends another to tell the stomach to initiate vomiting remains surprisingly poorly understood.
A new study, recently published in the prestigious journal Cellprovides many answers to this question by showing that bacterial toxins and chemotherapy drugs seem to trigger similar neuronal messages in the intestine, resulting in both cases in the onset of nausea (2).
The researchers first showed that mice that ingested a bacterial toxin retched, characterized by contractions of their abdominal muscles, like the stomachs of humans do when they are about to be sick. This behavior has also been observed following the administration of a chemotherapy drug, suggesting that a common mechanism is at work.
Further studies led to the discovery of cells in the small intestine that reacted to the presence of these harmful substances and sent a message to the brain, more specifically to a group of neurons located in the solitary tract, a region of the medulla oblongata. in the brain. This gut-brain link is thought to involve the production of an immune system molecule called interleukin 33 (IL-33), because genetic manipulation of animals to prevent the manufacture of this molecule reduces the emetic response to bacterial toxins and chemotherapy drugs.
The identification of this immunoneuroendocrine axis raises the interesting possibility that drugs that interfere with IL-33 (or other players in this pathway) may help alleviate the suffering of people treated with chemotherapy and thus greatly improve their quality. of life. One more step in a better therapeutic management of cancer.
(1) Hesketh PJ. Chemotherapy-induced nausea and vomiting. N.Engl. J.Med. 2008; 358: 2482-2494.
(2) Xie Z et al. The gut-to-brain axis for toxin-induced defensive responses. Cell 2022; 185:4298-4316.e21.