What are NK cells?
The NK or Natural Killer cell is an immune cell with small particles that contain enzymes with the ability to eliminate tumor cells or cells infected with a virus. NK cell can also be viewed as a white blood cell, often labeled NK-LGL (1).
How do NK cells work?
NK cells are beneficial to the immune system by helping the body fight against viruses and infections. NK cells are lymphocytes within the immune system classified as Innate Lymphocytes (ILCs); these cells act fast when dealing with various pathological contests. It boosts your body's ability to attack challenging cell function to keep the body functioning at an optimal level. Some pathological contests may include virally infected cells, identifying and controlling early signs of cancer. The knowledge of pathological contests can enhance protection against disease. Data shows NK cell activity may play an essential role in pregnancy regarding the placenta (2).
NK cells are known for their capability to eliminate tumor cells without any prior activation. This means an extra step is required when comparing cytotoxic T cells to B cells, such as priming by antigen-presenting cells before the act of attacking is complete. NK cells can reach the attacker at a faster rate to enhance immune response (2). While the NK cells scan the body for an attack, NK cells constantly communicate with other cells. At the same time, all this is in motion; the official elimination of the cell rests on a balance of signals from activating receptors and inhibitory receptors located on the NK cell surface. Activating receptors make out molecules articulated on the surface of tumor cells and infected cells; this will then turn on defense mechanisms from the NK cell. Inhibitory receptors proceed to assess NK cell killing. Comparing a normal/non-infected cell will convey MHC I receptors which notify these cells not to attack themselves. Inhibitory receptors of the NK cell will concede to similar MHC I and turn off the NK cell, inhibiting it from killing. Abnormal/cancer cells often drop their MHC I, making them susceptible to NK cell killing. As the NK cell concludes attacking cancerous cells, the NK cell will discharge cytotoxic granules that contain specific enzymes, leading to the elimination of the target cell (2).
MHC I and NK cell inhibitory receptors vary between everyone. The genetic code of everyone can be carriers of the ability to fight against HIV infection and many autoimmune diseases. NK cell assortments also transform as people age and can be affected by chronic viral infections like cytomegalovirus (CMV). Due to NK's capabilities to fight against tumor cells, NK cell is an appealing focus for cancer immunotherapies (2).
What weaken NK cell functions?
While NK cells and their distinct functions operate many vital roles in several animal models of disease, the same concept is associated with human clinical conditions. NK cells also experience a deficiency known as Natural Killer Cell Deficiency (NKD); it exemplifies a small but highly valued subdivision of primary immunodeficiencies (PIDs). PIDs can have challenges in diagnosis and clinical management. NKD additionally arranges excellent insight into the value of and contrivance essential human NK cell function (3). To be considered NKD, the patient must present significant immunologic abnormality even though many diseases, infections, drugs, and physiologic states can affect NK cell data; proper NKD diagnosis is reserved for abnormalities fixed over time and not secondary (3). NKDs can be separated into two major types reliant on whether NK cells are present in the peripheral blood. The first type is Classical Natural Killer cell deficiency (CNKD). This is explained as an absence of NK cells and their function between peripheral blood lymphocytes. Secondly, Functional natural killer cell deficiency (FNKD) is presented as NK cells within peripheral blood lymphocytes having malfunctioning NK cell activity. This can be simplified by looking at patients with diagnosed CNKD, the NK cells are deficient, and patients with FNKD, their NK cells are present but do not function properly. Looking at both patients with CNKD and FNKD, NK cell abnormality is a primary immunologic deficit resulting in insufficient power of defense (3).
NK cells are immune defense mechanisms that play a vital role in anti-infection or viral host defense. However, due to tumor progression and chronic infections, they most likely will lead to exhaustion of NK cells, limiting the anti-tumor or anti-infection potential of NK cells (4). Immune cell exhaustion terns the status of dysfunction of immune cells, frequently seen in vigorous tumors or chronic infections settings. This occurs because of constant control of tumors or conditions and is characterized by impaired effector functions. When comparing T cells, exhaustion is convoyed biphenyl typic changes, genetic modifications, and changes in transcriptional profiles (4). Progression of molecular characteristics of T cell exhaustion has increased the understanding of T cell biology and has given a rise in T cell-based anti-tumor or anti-infection immunotherapy and can be seen as an immune checkpoint and T cell therapy that can be adaptive (4).
How can I strengthen NK cell activity naturally?
Recent studies lead us to believe increasing NK cell production will increase immune defense responses to eliminate cancerous cells or infected cells and improve overall health. The use of probiotics has shown results of potentially increasing NK cell count. Utilizing NK cell supplements has been acclaimed for their therapeutic benefits even though the consumption of probiotics is narrowly understood. First, probiotic supplements may be able to provoke a reaction from NK cells at a micro-level. Secondly, modifications can make significant lifestyle changes to increase NK cell count putatively. Such lifestyle changes include regular cardio exercises, consumption increases of antioxidants, massage therapy, and strength training to increase NK cell levels. When making these lifestyle changes, even though research isn't strong enough to support the stimulation of NK cell activity, it may rise and encourage the body to provide more NK cells production (5). In Unique circumstances, stem cell therapy might help people increase the shows of NK cells present in their immune system. NK cells begin their life as stem cells; theoretically, supplying the body with extra stem cells may produce different NK cells; however, the research on stem cells is relatively new and not widely understood.
In addition to the utilization of probiotic supplements, recent studies highlight the use of mushrooms as a healing agent against H1N1 influenza virus and increasing NK cell activity. This mushroom is named Agaricus blazei Murill, and its history for successful medicinal usage stems from traditional Chinese and Japanese medicine. Consumption of Agaricus blazei Murill modifies immune responses for the prevention of cancerous cells, nutritional support during cancer treatments, as well as chronic inflammatory conditions like hepatitis or arthritis. Clinical studies on humans utilizing Agaricus blazei Murill illustrate a reduction in proinflammatory cytokines, amended quality of life in patients with inflammatory bowel disease (IBM), and diminished allergy and asthma indications. Agaricus blazei mushroom reports strong antimicrobial and anti-inflammatory effects as well as naturally strengthening NK cell activity (6). NK cells are a part of our innate immune system and can be depleted with age, increased stress, and pollution. Research from UCLA in 1994 explains strengthening NK cells naturally can be done by consuming Agaricus blazei mushroom extract. Mice were given injections of Agaricus blazei mushroom extract and resulted in the mice having an increased NK cell count after a month of injections. Another study also revealed ten years later Agaricus blazei Murill consumption increased 3 out 5 control groups NK cell function (7). The world is full of triggers; anything from pollution to stress levels can lead to a decline in the number of activated NK cells to create a robust immune response to infections. Agaricus blazei Murill mushroom is an excellent food ingredient to boost the immune response system and enhance the quality of daily life.
References:
- https://www.cancer.gov/publications/dictionaries/cancer-terms/def/natural-killer-cell
- https://www.immunology.org/public-information/bitesized-immunology/cells/natural-killer-cells
- https://primaryimmune.org/wp-content/uploads/2015/07/JACI-Natural-killer-cell-deficiency-September-2013.pdf
- https://www.frontiersin.org/articles/10.3389/fimmu.2017.00760/full
- https://www.frontiersin.org/articles/10.3389/fimmu.2019.03026/full
- Geir Hetland et al., Can Medicinal mushrooms have prophylactic or therapeutic effect against COVID-19 and its pneumonic superinfection and complicating inflammation?, https://doi.org/10.1111/sji.12937,Immunology, 2020
- https://www.superfoodscience.com/blogs/health-blog/natural-killer-cell-deficiency