Fasting strengthens the immune system's natural killer cells and increases their attack on cancer
Cancer cells have been shown to have the ability to use lipids to evade attack by immune cells, and a new study in mice has found that fasting trains immune system cells to be more resistant to lipids.
Fasting reshapes tissue-specific niches to improve NK cell-mediated anti-tumor immunity: Immunity
Fasting Primes the Immune System's Natural Killer Cells to Better Fight Cancer, New Study in Mice Finds | Memorial Sloan Kettering Cancer Center
https://www.mskcc.org/news/fasting-primes-immune-systems-natural-killer-cells-to-better-fight-cancer-new-study-in-mice-finds
Fasting not only helps improve a person's metabolism and lose fat, but it is also emerging as a way to enhance cancer treatment by depriving cancer cells of nutrients they need to grow.
Furthermore, the study, published in the medical journal Immunity on June 14, 2024, suggests that fasting may optimize the performance of immune cells and strengthen the body's immune system's ability to eliminate tumors.
'Cancer tumors are extremely hungry, absorbing nutrients and creating a lipid-rich environment that is harmful to immune cells,' said lead author Joseph Sun of the Memorial Sloan Kettering Cancer Center in the US. 'We now show that fasting reprograms natural killer (NK) cells to survive in such an environment.'
The NK cells mentioned by Sun are a type of white blood cell that have the ability to kill cancer cells and virus-infected cells. Generally, the more NK cells present in a tumor, the better the prognosis for cancer patients.
In this study, the team fasted mice with cancer for 24 hours twice a week, but allowed them to eat as much as they wanted between fasts. This helped the mice maintain their weight, but it caused a major change in their NK cells.
Just like in humans, the glucose concentration in the fasted mice decreased, and the
'With each fasting cycle, the NK cells learned to use fatty acids instead of glucose as a fuel source,' said Rebecca DelConte, a member of the research team. 'This training allowed the NK cells to survive longer in tumors, which contain high concentrations of lipids.'
The team also found that fasting optimizes the body's immune system: When the mice fasted, more of their NK cells migrated to the bone marrow, where they were exposed to a signaling protein called interleukin-12 produced by bone marrow cells, which enabled the NK cells to produce more interferon -gamma, a cytokine important in anti-cancer responses.
Meanwhile, NK cells also migrated to the spleen, where they were trained to use lipids as a fuel source. It is not yet clear whether NK cells are divided into the bone marrow and the spleen and trained separately in each location, or whether they are trained in both over time, but the research team believes that fasting reduces the number of free NK cells that do not go to the bone marrow or spleen in humans, just as it does in mice.
Clinical trials are already underway to test the safety and efficacy of fasting in combination with standard cancer treatments, and in the future, drugs may be developed that mimic this mechanism. It is also possible that patients' NK cells could be fasted ex vivo and then reinjected into the body, without the need for patients to fast themselves.
However, because research into cancer and fasting is still in its infancy, experts caution patients not to start fasting abruptly. 'There are many different types of fasting, some of which are beneficial and some of which are harmful, so patients should talk to their doctors about what is safe and healthy for them,' said Neil Iyengar, a researcher at Memorial Sloan Kettering Cancer Center who was not directly involved in the study.
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