The researchers found that the negative destructive properties of eosinophil type white blood cells can also be used to damage and destroy cancerous tumors * The researchers discovered that eosinophils fight cancer cells in two ways: they are able to kill cancer cells directly, and also recruit T cells of the immune system that fight cancer
A new study by Tel Aviv University found that white blood cells of the eosinophil type are recruited to fight cancer metastases in the lungs. According to the research, the white blood cells secrete destructive proteins and at the same time recruit T cells of the immune system to jointly fight the cancerous tumors. According to the researchers, their findings may contribute to the development of innovative approaches to cancer immunotherapy based on the cooperation between T cells and eosinophils.
The research was conducted under the leadership of Prof. Ariel Munitz and PhD student Sharon Grisero, from the Department of Clinical Microbiology and Immunology at the Sackler School of Medicine. The study was published inCancer Research, a prestigious journal of the American Cancer Society.
The researchers explain that eosinophils are white blood cells of the immune system, which secrete proteins with destructive power, whose role in evolution is to fight parasites. However, in the modern western world, when parasites are diminishing due to strict hygiene, eosinophils often become a negative factor, causing allergies and asthma.
However, the researchers believed that the ability of the eosinophils to wreak havoc may in a sense become a positive factor that eliminates the "bad" cancer cells. Prof. Munitz explains: "We chose to focus on lung metastases for two main reasons: first, one of the main problems in the fight against cancer is the cancer metastases and not necessarily the primary tumor, and the lungs are the main target for metastases of many types of cancer. Secondly, in a preliminary study we showed that eosinophils reach cancerous tumors that develop in mucous tissues such as the lungs, so we believed that they would also reach lung metastases."
In the first phase, the research examined human cancer tissues - biopsies of lung metastases taken from patients with metastatic breast cancer. The researchers found that the eosinophils do reach the lungs, penetrate the cancerous tissues, and release the destructive substances they carry.
To examine the role of eosinophils in metastasis, the researchers used an animal model and found that lung metastases that developed without eosinophils were much larger than those metastases attacked by eosinophils. These findings led to the conclusion that eosinophils fight effectively against cancer, but the question still remains: how do they do this?
Prof. Munitz: "During the research we noticed that when there are no eosinophils in the tissue, T cells are also absent from it - white blood cells that are known to fight cancer. From this we assumed that the eosinophils act against the cancerous tumor through T cells, and we sought to understand the mechanism that makes this possible."
To this end, the researchers performed an extensive analysis to characterize the eosinophils found in metastases, and brought up two significant findings: first, eosinophils found in a cancerous environment release a large amount of substances called chemokines, which summon the T cells; And secondly, the chemokines are released in response to two other substances found in the cancer environment: IFN-g and TNF-a. That is, eosinophils exposed to IFN-g and TNF-a recruit T cells. In the last phase of the study, the researchers identified that this causes the development of T cells in the metastatic lungs and slows down the development of cancerous tumors.
Prof. Munitz: "Increasing the number and strength of T cells is one of the main goals of immunotherapy treatments given to cancer patients today. We have discovered a new interaction that recruits large numbers of T cells to cancerous tissues, and these findings may have therapeutic implications. Our research may form the basis for the development of improved immunotherapy drugs that use eosinophils to eradicate cancer: on the one hand, the eosinophils will release their destruction proteins against the cancer, and on the other hand, they will increase the number of T cells in the cancer environment. We hypothesize that the combined effect will be able to significantly increase the effectiveness of the treatment."
The research was funded by ICRF (Israel Cancer Research Fund), the Cancer Society, ISF (National Science Foundation), BSF (Binational Science Foundation of the USA and Israel), and the GSK company.
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