November 28, 2021

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Toxoplasma gondii has become a new hope for tumor treatment

Parasites cure cancer: Toxoplasma gondii has become a new hope for tumor treatment

Parasites cure cancer: Toxoplasma gondii has become a new hope for tumor treatment



Parasites cure cancer: Toxoplasma gondii has become a new hope for tumor treatment

Speaking of Toxoplasma gondii, people may first think of cats and the risks this parasite brings to pregnant women. Laboratory studies have shown that this small parasite may stimulate the immune system and play a role in future cancer treatments.

Parasites cure cancer: Toxoplasma gondii has become a new hope for tumor treatment

Speaking of Toxoplasma gondii, people may first think of cats and the risks this parasite brings to pregnant women. Laboratory studies have shown that this small parasite may stimulate the immune system and play a role in future cancer treatments.

Toxoplasma gondii , a single-celled parasite, is an intestinal coccidian of cats. The worm has a worldwide distribution and can be infected by humans and many animals. With the increase in the number of cat owners, nearly one-third of the world’s population is infected. The positive infection rate in China is 5%-20%, and in some areas it is as high as More than 30%.

A healthy immune system responds positively to the invading Toxoplasma gondii, and this immune response is similar to the immune response required to fight tumors. From a biological point of view, these parasites have found a way for us to stimulate an immune response against cancer.

In response to Toxoplasma gondii, the body produces natural killer cells and T cells. These immune cells can also fight tumor cells. Tumors can suppress the immune defense response in the body, and if Toxoplasma gondii is introduced, it can stimulate the immune system. This is completely different from other microbial-based immunotherapy strategies, which can restart the immune system and rely on their natural power to eliminate tumor cells.

On November 1, 2021, researchers from the University of Nottingham in the United Kingdom and Affiliated Hospital of Ningbo University School of Medicine published a research paper in the BMJ sub-journal ” Journal for ImmunoTherapy Cancer “.

The study showed that in mouse models of melanoma, lung cancer and colon adenocarcinoma, treatment with modified Toxoplasma gondii and anti-PD-L1 significantly prolonged the survival time of mice and inhibited tumor growth. The reduced tumor growth detected in injected tumors and distant tumors can induce systemic effects, improve the immune response of mice, and sensitize immune “cold” tumors, and make them susceptible to immune checkpoint blocking therapy .

Parasites cure cancer: Toxoplasma gondii has become a new hope for tumor treatment

In this study, the researchers first modified a mutant strain of Toxoplasma gondii to have a limited growth ability, causing diseases in cultured cells or in mice, but at the same time being able to manipulate the host immune system.

In a mouse model, direct injection of this mutant parasite can induce an inflammatory response in the injected tumor or even in a tumor located far away in the mouse . In addition, this treatment method makes tumors more sensitive to immune checkpoint inhibitor therapy.

Treatment with modified Toxoplasma gondii and anti-PD-L1 significantly prolonged the survival time of mice and reduced tumor growth in mouse models of melanoma, lung cancer and colon adenocarcinoma .

Parasites cure cancer: Toxoplasma gondii has become a new hope for tumor treatment

Intratumoral administration of Toxoplasma inhibits the growth of non-injected distant tumors

The researchers said that the study confirmed the effectiveness of intratumoral injection of mutant Toxoplasma strains to enhance anti-tumor immunity and checkpoint suppression therapy.

In summary, the results show that intratumoral injection of mutant Toxoplasma gondii can induce systemic effects, improve the immune response of mice, and sensitize immune “cold” tumors, and make them susceptible to immune checkpoint blocking therapy.

Paper link:

http://dx.doi.org/10.1136/jitc-2021-002970

Parasites cure cancer: Toxoplasma gondii has become a new hope for tumor treatment

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