Eating Healthy Might Help the Immune System Fight Cancer

Obesity has been known for years to be a major health problem. Rates of obesity have been steadily increasing all over the world. Many factors, including healthy eating habits and exercise, play important roles in controlling obesity. In our study, we compared the function of cells of the immune system called natural killer (NK) cells between healthy and obese groups of mice. We found that obese mice have lower numbers of NK cells and that NK cells from obese mice are less functional. Lower NK cell activity is related to a higher risk of infections and cancer in the obese group. This research could show a relationship between what we eat and our ability to defend ourselves against diseases like cancer.


Figure Figure
Where do immune cells come from? The immune system contains many types of cells, all of which originate from cells called multipotent hematopoietic stem cells, which are found in the bone marrow. As HSCs divide, they develop into the many cell types shown in this diagram. In our research, we were interested in NK cells, which are one of the three kinds of lymphocytes.
contribute to a person's likelihood of becoming obese, but other things, like lack of exercise and eating a high-fat diet, can also contribute to obesity. The number of obese people in the world is steadily increasing, and obesity is now treated as a disease. We know that obesity causes many health issues. For example, obesity can cause heart problems, because the excess weight makes the heart work too hard, so it gets tired sooner. When the heart gets too tired and weak, it might stop beating and pumping the blood, which can cause death. cardiac arrest or heart failure While we know obesity a ects the heart, we do not know everything that it does to other parts of our body. Obese people have also been found to have a higher risk of cancer. Increased risk of cancer could be related to a decreased ability of the immune system to protect us from cancerous cells. Therefore,

IMMUNE SYSTEM
A system of the body that protects it from dangers, such as bacteria, viruses, etc.
we decided to study cells of the immune system, to see if they are somehow di erent in healthy mice than in obese mice.

WHAT IS THE IMMUNE SYSTEM?
The immune system is extremely important to keep us healthy. It helps defend against infections and diseases caused by bacteria and viruses, and it is also believed to help defend us against cancer. Since we depend on the immune system so much, it makes sense to keep it working at its best. The immune system needs several di erent kinds of cells to successfully defend our bodies. Figure shows a list of the many kinds of immune cells the body uses to defend itself. All immune cells originate from cells called hematopoietic stem cells, which are found in the bone marrow. All of these immune cells are important, but our study focused on one type of cells, called lymphocytes. ). Lymphocytes can remember what they attack. These memories allow the immune system to respond faster the next time they see the same threat. Faster responses mean we get sick less. Did you ever

PROTEASES
A type of protein that assists in breaking down other proteins.
Perforins are used to punch holes in the outside walls of cancer cells. The holes allow proteases to invade the cancer cells. Once inside, the proteases attack and break down important cell parts that the cancer needs to spread and survive. If cancer is not able to spread and renew itself, it is much less dangerous. To successfully fight cancer cells, NK cells need to be healthy and fully functional (Figure ).

OBESE MICE HAVE FEWER, LESS ACTIVE NK CELLS
To see if diet could a ect the number of NK cells, we fed mice with either a high fat-calorie diet (HFCD) or a control, healthy diet (CD). In -weeks, mice fed HFCD gained -times more weight compared to mice fed CD. Using flow cytometric analysis, we counted the number of NK cells in both obese HFCD mice and CD mice and found that there were fewer NK cells in obese mice ( Figure A) [ , ].
To see whether the NK cells from healthy and obese mice could kill cancer cells, we ran cytotoxicity assay in which NK cells are e ector cells and tumor cells are targets. We found that NK cells from obese mice were less capable of killing cancer cells ( Figure B). We think this means that, if the obese mice had cancer, the cancer could spread very easily because the NK cells of those mice are weaker and would not be able to destroy the cancer cells [ ]. Although this finding still needs to be confirmed in humans, the results obtained from mice suggest that obese people might also have a smaller number of NK cells and that those NK cells might be less functional than NK cells from non-obese people. This could help explain why obese people have a higher risk of getting cancer compared to healthy people.

PUTTING IT ALL TOGETHER
The immune system is important. We use it every day for everything from fighting o infections that cause the sni es up to more serious things, like protecting us from cancer. So, it is in our best interest to keep the immune system in great shape. When our bodies get out of shape and become obese, our natural killer cells may show signs of being out of shape, too. In obese mice, there are fewer NK cells and those cells do not do their job of defending mice very well. If these findings hold true in humans, this could make obese humans more vulnerable to cancer, perhaps making it easier for the cancer to spread from one organ to another. It is possible that simply eating a little less fat every day and keeping your body a little healthier may be enough to help your NK cells fight o your body's enemies-even something as dangerous as cancer.

CONFLICT OF INTEREST:
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.