Immunity is the body's natural defense system against various pathogenic agents. One of the tasks of the immune system is to control the presence of cancer cells. The normal functioning of the immune system does not allow the formation of tumors and metastases and, for sure, underlies all the so-called «spontaneous remissions». Conversely, immune deficiency due to various causes increases the risk of cancer occurrence and metastasis *.
Overcoming the immune resistance of cancer cells opens up the possibility of their destruction, and is considered a promising direction in modern cancer therapy. Firstly, immune therapy is natural, as opposed to external interventions such as surgery, chemotherapy, or radiation. Secondly, immune therapy is desirable because, after all, only the immune response provides the final result, while all other therapies, even the strongest, are insufficient.
It has long been noted that after severe infectious diseases accompanied by fever, spontaneous remissions sometimes occur in cancer patients *. This may be evidence that a sufficiently strong and adequate immune response of the body is able to turn the tide of the fight against the tumor in favor of the body.
However, relying solely on immune therapy, without combining it with other therapies, would be unwise. First, combination therapy is more effective than any monotherapy. And secondly, immune therapy may show insufficient success. No matter how strong immune cells are, they are not always predators, and cancer cells are victims. Between immune and cancer cells there is a struggle, the result of which is not unambiguous. In some cases, cancer cells themselves are able to engulf immune T cells * and NK cells *. In addition, immune cells are also suspected of spreading cancer cells throughout the body (metastasis).
How the immune system works. The immune system is one of the most complex human biological systems. It protects the body from destructive pathogens by recognizing them by their characteristic molecular fragments and then destroying them through the coordinated work of specialized cells *. Immunity is divided into innate (non-specific) and acquired (adaptive, specific) *.
Innate immunity recognizes cells or microorganisms to be destroyed by the specific protein structures inherent in each of them, which are called antigens. Innate immunity has a genetically written list of antigens of the most common classes of pathogens. Antigens can be figuratively compared with the barcode of the country of manufacture, pasted on the product. After their identification, phagocytes (devourer cells), such as neutrophils, macrophages, dendritic and mast cells, instantly involve the carriers of these antigens inside themselves and then destroy them by dissolution (the so-called lysis).
There can be many more variations of antigens than are recorded in the database of innate immunity. Therefore, such a mechanism does not always successfully cope with its protective function. In this case, an adaptive mechanism is activated, tailored for each specific pathogen that has proteins. Adaptive immunity is acquired by gene rearrangement of B- and T-lymphocytes, and by their acquisition of the ability to produce specific antigens for a particular pathogen. This process can take several days and is accompanied by a painful condition of varying severity.
Antigen-presenting cells are the first to enter the fray. They can be dendritic cells or macrophages (translated as «big eaters»). Having absorbed the pest, they decompose it into fragments. Having isolated an antigen specific for a given foreign agent, antigen-presenting cells place (expose) it on their cell surface and present (show) it to lymphocytes (T-cells) as a sign of an object to be destroyed.
Cytotoxic T cells (Tc, CD8), having received the characteristics of a new target, immediately begin to multiply and destroy pathogens with the described antigens. They do this directly by releasing aggressive substances (perforin). However, they may need reinforcement because the number of cytotoxic T cells is limited, and the number of pathogens can multiply faster than the number of cytotoxic T cells.
To do this, helper T cells (Th, CD4), contacting with antigens, are activated and begin to produce hormone-like substances – interferons, chemokines and cytokines (such as IL-8, IL-1 and TNF-α). In obedience to these signals, the number of macrophages and neutrophils in the infected tissue increases, which destroy any pathogens by capturing, absorbing and subsequent decomposition and assimilation. Some cytokines stimulate T cell division, boosting the immune response.
Helper T cells present B cells with antigens to be detected; it's like a «wanted poster» for police agents. In addition, they stimulate the multiplication of task executors – B-cell clones oriented to the «wanted» antigen. Those rapidly divide and secrete antibodies – serum proteins that are highly specialized to bind to the desired antigen (immunoglobulins).
Antibodies released by B cells are attached to their antigens on the surface of a pathogenic agent with the help of complementary proteins. Thus, they mark the carrier of antigens as a target for attack by killer cells. Thanks to these marks, macrophages and other killer cells attracted to the infected tissue easily find and destroy their prey. And in order to prevent overexcited killer cells from infecting healthy cells in their own body, regulatory T-cells, otherwise called T-suppressors, are produced. They restrain the excessive zeal of the performers and extinguish the immune reaction after its cause has been eliminated.
As soon as clones of T- and B-cells appear in the body, targeting some specific antigens, they acquire the ability to quickly and directly (without the help of T-helpers) respond when they encounter these specific antigens again. In other words, they acquire a long-term «memory» for these antigens – they form a stable immunity against them. Figuratively speaking, they add to the «stop list» not a sub-sanctioned manufacturing country, as innate immunity does, but a specific product.
Immune reactions against malignant cells are possible due to the fact that specific molecular components are expressed on their cell surface somewhat differently than on similar normal cells.
Some of them have chemical structures unique to cancer cells. Others may have chemical structures that are common to both malignant and normal cells, but more pronounced on malignant ones. Still others are present on embryonic cells but disappear from normal adult cells. Some others do not qualitatively differ from the antigens present on normal cells, but are present in malignant cells in much larger quantities.
These tumor-specific antigens, otherwise known as tumor antigens, are recognized by the immune system as signs of hostile cells, and naturally trigger a cascade of immune actions.
A person is attacked every second by various pathogens, but thanks to the work of the immune system, he remains healthy for most of his life. Similarly, tumor cells can repeatedly appear throughout a person's life, and each time they are destroyed without a trace by means of immunity. However, when the work of the immune mechanism loses its effectiveness, the risk of various diseases increases.
Immune system dysfunction can be chronic or age-related, and predispose to various infectious or autoimmune diseases. But even a temporary dysfunction of the immune system may be enough for a tumor to appear. If the number of tumor cells is large enough to be able to overcome the strength of the immune response, then even the subsequent restoration of adequate functioning of the immune system may be unsuccessful.
Evasion of cancer cells from the body's immune response is a critical condition for tumor development *. The weakening of the immune response of cancer cells can have several causes. For example:
- absence of tumor antigen or its weak expression;
- weakening the ability of immune cells to detect their target;
- the inability of the body's immune cells to reach the tumor;
- antigenic masking of the tumor;
- production by the tumor of substances that suppress and/or disorientate immune cells;
- high activity of immunosuppressive cells;
- a decrease in the number and/or weak activity of killer cells.
Accordingly, the immune fight against a tumor should include all these points.
Immunotherapy. In recent years, the use of the body's immune system to fight cancer has received increasing interest, although so far it has not justified the hopes originally placed on it. Some cancers respond well to immunotherapy alone, while other cancers respond better when combined with other treatments, such as chemotherapy.
Immunotherapy can use several strategies:
- activation and normalization of immune cells;
- improved recognition of natural antigens of cancer cells;
- improved recognition of cancer cells using monoclonal antibodies;
- production of antibodies with the help of vaccine therapy;
- adoptive cell transfer – a method in which a patient's T cells are removed, genetically modified to recognize cancer cells, and then transferred back to the patient;
- other strategies.
Most of these strategies require highly specialized equipment and specialists.
Although the immune system is able to deal with cancer cells on its own, this ability can be suppressed or disoriented enough to allow the tumor to use immune cells for its own defense. In addition, the possibilities of immune defense in a tumor are much less than in normal tissue.
If the immune system is not working adequately, the strengthening of the body's immune response will do harm instead of good. For example, in patients with autoimmune diseases, the immune system is already abnormally activated and difficult to control. Therefore, they may have trouble tolerating immunotherapy drugs that stimulate immune cells to better recognize and fight cancer.
Thus, in the presence of autoimmune diseases, both latent and overt (eg, type I diabetes, rheumatoid arthritis, lupus, psoriasis, Crohn's disease, ulcerative colitis, Basedow's disease, Addison's disease, celiac disease), autoimmune therapy may be counterproductive. And even in patients who do not have such contraindications, the use of specialized immunotherapy drugs can undermine the immune system's tolerance for healthy tissues.
The number of such people in the population can reach 20-25%. This means that you need to be careful when using immune cell stimulants. Real strengthening of immunity means its normalization, and not necessarily activation.
Substances capable of stimulating, suppressing or modulating any aspect of the immune system, including both adaptive and innate parts of the immune system, are called immunomodulators. Clinically, they fall into three categories: immunoadjuvants, which are used to improve the effectiveness of vaccines; immunostimulants, which are used as non-specific enhancers of both innate and adaptive immune responses; and immunosuppressants, which are used to reduce immune responses, usually in autoimmune diseases.
Unmasking of cancer cells can be achieved by dissolving the fibrin film and glycoproteins covering the cancer cells. Cleansing the surface of the cell membrane exposes the molecular markers inherent in the cancer cell (tumor antigens), which improves the identification of cancer cells by dendritic cells. In addition, it will also allow antibodies to better bind to their antigens. Both the first and second can increase the chances of immune damage to cancer cells. The advantage of this approach is that it does not directly interfere with the work of the immune system itself, but helps it determine the detection of the target.
• Proteolytic enzymes of animal origin, such as trypsin and chymotrypsin, as well as plant origin, such as papain and bromelain, are able to improve the immune response to a certain extent. Rectal administration of two pro-enzymes (trypsinogen and chymotrypsinogen in a ratio of 1:6) to patients with advanced forms of various types of cancer improved their survival rates by more than 50% compared to expected survival *.
In the group of breast cancer patients treated with a complex of proteolytic enzymes (trypsin, chymotrypsin, papain) for at least 10 months as an adjunct to the main treatment, survival, recurrence and metastasis rates were markedly better than in the control group * with very good tolerance of additives. Bromelain, a plant-derived enzyme, also stimulated the immune response in breast cancer patients *.
Leukocyte stimulants. Leukocytes, or white blood cells, are the main cells of the body's immune system. These are cells of rapid response to the inflammatory response related to the innate immune system. Once in the focus of inflammation, they recognize pathogenic microorganisms and destroy them using various mechanisms. Cells capable of eating pathogens are called phagocytes.
Leukocytes can be divided into lymphocytes (T cells, B cells, and NK cells), neutrophils, and monocytes/macrophages. Lymphocytes produce antibodies designed for a specific antigen, and monocytes, after moving from the blood to the tissue, turn into macrophages that destroy pathogens in the same way as neutrophils – by absorbing them (phagocytosis).
• Cat's claw (Uncaria tomentosa, Uncaria guianensis) increases the production of white blood cells *, T- and B-lymphocytes *, and also increases their survival *. All plant alkaloids show a pronounced effect of enhancing phagocytosis *. Cat's claw bark extract improves the quality of life and stabilizes the condition of patients with various types of advanced solid tumor * and allows women with breast cancer to maintain a high level of neutrophils during chemotherapy *, which significantly reduces its side effects. At the same time, the extract repairs single-strand (SSB) and double-strand (DSB) DNA strand breaks within 3 hours after radiation exposure, which can weaken the therapeutic effects of standard therapy *. Dosage: inside from 300 mg/day * to 1'500 mg/day * of dry extract extracted from the bark of a tree with 70% ethyl alcohol.
• Red chili pepper (Capsicum annuum, Capsicum frutescens). Intratumoral injections of an aqueous extract of capsicum into a grafted tumor caused tumor growth to slow down in mice, regardless of tumor size. Direct injection of capsaicin (1-10 μg/mL, 100-200 μg) into the tumor enhances T-cell function and selectively targets tumor cells *.
• Piperine, contained in Long pepper (Piper longum), up to 40% increases the total number of leukocytes and the production of antibodies. Intraperitoneal administration of an alcoholic extract of pepper (equiv. 3 g/day) or piperine (equiv. 350 mg/day) virtually stops the development of grafted carcinoma in mice. Treatment with pepper extract increased lifespan in animals by 37%, and treatment with piperine by 59% compared to control *.
• Asian Centella, also known as Gotu Kola (Centella asiatica), increases the number of leukocytes and enhances phagocytosis. The plant extract (equiv. 10 mg/kg) elicited a higher immune response in mice compared to untreated mice *. Feeding centella to piglets slightly increased their level of leukocytes *.
• Chicory (Cichorium intybus). In mice, oral ingestion of an ethanol extract of the plant's root at a dose of 300 mg/kg showed a significant increase in circulating leukocytes and a relative increase in the weight of the liver, spleen, and thymus. There was also an increase in the activity of phagocytes, natural killer (NK), as well as the production of interferon-γ *. The human equivalent dosage will be 1'800 mg/day of the dry fraction of the extract.
Macrophage activity modulators. Macrophages are phagocytic cells that capture, engulf and assimilate viruses, bacteria, cancer cells, the remains of dead cells, and other foreign, garbage, or toxic agents. One of the most important functions of macrophages is the removal of apoptotic cells.
During an immune response, bone marrow-derived monocytes can migrate from the blood into tissues, where they differentiate into macrophages. Cell differentiation requires adequate mitochondrial function. Controlling macrophage activity can improve the immune response to cancer cells.
• Organic germanium significantly increases the level of cytokine (interferon-γ) activity in mice, and also activates macrophages and NK cells (natural killer cells) *. Human equivalent dosage: 2 g/day.
• Deodeok (Codonopsis lanceolata) in the form of a water-alcohol extract is able to control the immune responses of macrophages, thereby contributing to their anti-inflammatory activity *. Mice treated with aqueous extracts of codonopsis (50 mg/kg po every other day for 4 weeks) increased immune function by increasing cytokine production by activated macrophages *. Equivalent human dosage: 350 mg/day.
• Eleutherococcus (Acanthopanax senticosus) activates macrophages and natural killers against cancer cells. Intravenous injections of an aqueous extract of Eleutherococcus (25 mg/kg) into mice significantly suppressed metastasis by enhancing the body's immune response *. In human equivalent, this dosage will be 150 mg/day of dry extract, or 3 g of plant stem bark powder.
• Licorice (Glycyrrhiza glabra). Plant root polysaccharides in vitro increase macrophage phagocytosis, stimulate macrophages to produce interleukin IL-1, enhance NK activity, and increase antibody-dependent cytotoxicity *. Grind the roots, mix with water in a ratio of 1:15, hold for 2 hours at a temperature of 99 °С.
• Diosgenin at a concentration of 20 μg/mL in vitro can enhance the phagocytic ability of macrophages, as well as stimulate the transformation of lymphocytes *.
• Bovine colostrum is rich in IgA, IgG and IgM immunoglobulins and can quickly recruit and activate macrophages, lymphocytes and dendritic cells.
Despite the success of preclinical studies, the practical benefits of these plants and substances have not yet been reported.
Lymphocyte stimulators. Lymphocytes are a subspecies of leukocytes, the leading cells of the immune system. Functionally, there are three types of lymphocytes: B cells, T cells, and natural killer (NK) cells.
NK lymphocytes do not destroy foreign pathogens; they destroy the cells of their own body – infected with pathogens, damaged or mutated.
B-lymphocytes recognize foreign structures (antigens), and produce specific antibodies against them, due to which the pathogen is destroyed by T-lymphocytes.
CD4 T-lymphocytes (helper T-lymphocytes) provide recognition and subsequent destruction of cells bearing foreign antigens, and also enhance the action of monocytes and NK cells. There are four major subsets of CD4 cells. Of these, Th1, Th2, and Th17 are effector T cells, and Treg prevents autoimmunity and exacerbates immune responses.
CD8 T-lymphocytes (cytotoxic T-lymphocytes), like natural killer cells, destroy the cells of their own body. But unlike the latter, they destroy only cells that carry specific antigens.
Cytokines, which are produced by T-lymphocytes, are essential for the effectiveness of the body's immune response.
Peripheral blood levels of T-lymphocytes that produce type 1 cytokines (IL-2, IFN-γ or TNF-α) and type 2 cytokines (IL-4) are significantly lower in patients with breast cancer than in healthy individuals *, which correlates with the presence of micrometastatic cells in the bone marrow.
• White mistletoe (Viscum album), an aqueous infusion of leaves and berries. It is assumed that the immunomodulatory effects of mistletoe are caused by its three components – lectins, alkaloids and viscotoxins.
The combination of mistletoe with chemotherapy (complex: cyclophosphamide/doxorubicin/5-fluorouracil) results in clinical improvements in quality of life *. Mistletoe extract has been very effective in regression of breast cancer tumors in separate studies *. In addition to its toxic effects that inhibit proliferation and metastasis, mistletoe also enhances the body's immune response by increasing the production of interleukins and white blood cells. Mistletoe shows immunomodulatory effects, predominantly stimulating the cytotoxic activity of lymphocytes * *.
Subcutaneous injections of 5 mg of the extract during chemotherapy reduce the side effects of chemotherapy (such as neutropenia) in patients with early stage breast cancer and have been studied in several randomized clinical trials * *.
In a clinical study, subcutaneous injections of mistletoe extract at 20 mg twice a week markedly improved a number of parameters of general and cellular immunity in cancer patients *. Mistletoe extract also contributes to an increase in the number and activity of natural killer cells in the peripheral blood in a dose-dependent manner * *. Tumor regression has been reported after mistletoe ingestion, but only at high doses and when injected into the tumor * and not due to ingestion.
Mistletoe extract was used in doses of 20-100 mg dry extract; maximum dose: 1'500 mg *. Mistletoe extract is available in several commercial formulations including Cefalexin, Isorel™, Lektinol™, Eurixor™, Iscador™, Helixor™, Iscucin™, Aviscumine™ and Abnobaviscum™, which are sold as prescription injections and can be used as additional therapy.
• Cimetidine (an anti-ulcer drug, a histamine H2 blocker), taken before and during surgery, significantly increased the level of lymphocytes in patients within one week *. Taken for a year as an adjunct to 5-fluorouracil, cimetidine (800 mg/day) provided 10-year survival in 84.6% of patients versus 49.8% in the no-treatment group *.
Desloratadine and other second-generation antihistamines counteract histamine, which suppresses lymphocyte function, and significantly increase patient survival regardless of age, ER status, and tumor stage *.
• Ginseng (Panax ginseng). Healthy volunteers who received 2x100mg of standardized ginseng extract (Ginsana®) for 8 weeks showed an increase in immune system activity, in particular, statistically significant improvements in phagocytosis and total T-helper and T-suppressor cell counts *.
Regular long-term intake of 1.3 g/day of ginseng root (240 mg dry root extract) can improve patients' quality of life and increase both overall and disease-free survival after therapy by 10% *. Dosage: 50-100 drops/day of 10% alcohol tincture of the plant root.
However, ginseng may have steroidal (hormone-like) effects * and may require special consideration for use in women with breast cancer.
• Ashwagandha (Withania somnifera). Steroidal alkaloids and steroidal ashwagandha lactones significantly increased, compared to baseline, the expression of lymphocytes (CD4+) and NK cells in healthy volunteers. Here, the daily dosage was 2×6 ml of 50% ethanol extract of ashwagandha root dissolved in milk *.
• Mongolian milkvetch (Astragalus membranaceus) stimulates the development and transformation of bone marrow and lymphatic tissue stem cells into active immune cells. The alcohol-soluble polysaccharides of the root and rhizome can in vivo significantly improve serum cytokine levels (TNF-α, IL-2 and IFN-γ) and increase the activity of immune cells (macrophages, lymphocytes and NK cells), thereby promoting tumor cell death *. In a clinical study, 15mg/day astragalus root extract significantly increased serum levels of TNF-α, IL-8, IL-1β, and IL-32 after 14 days of administration compared to controls *.
• Turkey tail (Trametes versicolor) and Sage (Salvia miltiorrhiza). In breast cancer patients who took the polysaccharides of this combination daily for 6 months after chemotherapy, the absolute number of T-helper lymphocytes (CD4+), the ratio of T-helper (CD4+) to T-suppressor lymphocytes, and the percentage and absolute number of B-lymphocytes were significantly elevated. The dosage of polysaccharides was 50 mg/kg and 20 mg/kg, respectively *.
• Water-soluble polysaccharides from the root of Greater galangal (Alpinia galanda) at 25 mg/kg more than doubled T-cell and splenocyte proliferation in mice compared to controls *. The human equivalent dosage is 150 mg/day of the polysaccharide portion of the extract.
• Iodine (3-6 mg/day) increases the number of CD8+ lymphocytes in patients, enhancing the immune antitumor response *.
• Zinc at 12 mg/day has been shown to increase CD4+ cell counts in women with AIDS *.
• White birch (Betula alba). Betulinic acid, a pentacyclic triterpene from the bark of a tree, administered orally at a dose of 0.5 mg/kg, increased the total number of thymocytes, splenocytes, and lymphocytes in mice. It also positively changed the percentage of subgroups of T-cells in the thymus and T- and B-lymphocytes in peripheral lymphatic organs *.
• Beta-sitosterol, especially when mixed with its glucoside, in vitro accelerates the division of T-cells *. Beta-sitosterone at a dosage of 400 mg/day is used to treat prostatic hyperplasia.
Natural killer stimulators. NK cells are a type of lymphocyte that, without prior stimulation, recognize abnormal host cells, either damaged or infected with a virus or malignant cells, and destroy them. NK activation is regulated by the balance between activating and inhibitory signals from receptors present on their surface. When activated, NKs release cytokines such as interferon and TNF-α, as well as release perforin, a protein that breaks down cell membranes to be killed.
At the same time, NK is often deficient or dysfunctional in cancer patients * * *. Thus, NK-based immunotherapy may be beneficial for such patients. In addition, it may hold promise for targeting cancer stem cell (CSC) populations *.
• Beta-glucan (600-1'000 mg/day) significantly enhances the production and activity of T-cells and NK-cells * *. Beer yeast, wild rice bran (1 g/day) *, shiitake mushroom mycelium extract (5-10 g/day dry powder) *, or turkey tail (3 g/day dry aqueous extract) * can be a source of beta-glucan, as well as cordyceps (1.7 g/day) * *.
Activation of NK cells with beta-glucan can increase their activity several times *. Taking just 20 mg of beta-glucan in the form of brewer's yeast for 2 weeks increased the number and activity of monocytes in the blood by 1.5 times compared to baseline in women with breast cancer *.
Daily consumption of 5-10 fresh shiitake mushrooms by healthy volunteers for four weeks resulted in a 60% increase in γ-δ T-lymphocyte proliferation and a doubling of NK cell numbers *. While γ-δ T cells act as the first line of immunological defense, natural killer cells kill cancer cells, resulting in lower markers of systemic inflammation.
A review of controlled clinical trials found that cancer patients who combined reishi mushrooms with chemotherapy or radiation therapy responded to cancer treatment 50% more often than patients who did not. The beta-glucans found in reishi increased the percentage of several subsets of T cells and may have slightly increased NK cell activity *.
In animal studies, the immune effect of glucans was synergistically enhanced when they were combined with resveratrol and vitamin C. While resveratrol and glucan alone had a moderate effect, the combination of all three components stimulated phagocytosis, antibody formation, and demonstrated a strong antitumor effect *. In addition, this combination reduced the risk of lung cancer metastasis in animals treated with cyclophosphamide. In this experiment, mice were injected intraperitoneally with 100 μg of glucan, resveratrol and vitamin C daily. In human terms, this is approximately 30 mg of each of the components.
Beta-glucan is one of the most powerful and studied natural remedies for enhancing innate and, to a lesser extent, acquired immunity. However, people with a predisposition to autoimmune disease should be wary of beta-glucans, as they can increase the already high activity of immune cells against the body's own cells.
• Phytic acid (inositol hexaphosphate, IP6), found in large quantities in vegetables, bran and germ of cereals, especially corn and wild rice, has a stimulating effect on NK cells. In rats fed with water containing 2% IP6, the activity of NK cells increased by 2.6 times, and the growth rate of a colon tumor caused by a carcinogen decreased several times *. Combining IP6 with green tea or inositol produced a synergistic effect *.
• Indomethacin, a well-known NSAID, after intraperitoneal injection (100-400 µg) caused a marked increase in NK cell activity in mice, which was maximal within 3 days and lasted a total of 6 days. A similar, though less pronounced, effect has been observed with other cyclooxygenase inhibitors such as aspirin *. Unfortunately, NSAIDs with long-term use show noticeable negative side effects.
• Purple coneflower (Echinacea purpurea). Echinacea polysaccharides directly activate innate immune cells such as monocytes, macrophages and natural killer cells *. While indomethacin was ineffective in stimulating NK cells in older animals, the effectiveness of echinacea did not depend on the age of the organism. In healthy people, oral administration of 30 drops/day of Echinacea root tincture (Echinacin®) for 5 days increases phagocytic activity by 120% *, which slowly decreases after administration is stopped *. However, it has been observed that using echinacea for more than 5 days in a row causes a decrease in its effectiveness due to overstimulation *. Therefore, the maximum duration of treatment with Echinacea is 2 weeks *, after which a minimum of 1 week is required to restore the immune response *.
The dosage of dry raw materials is 3 g/day.
The question of a solvent for the preparation of echinacea root extract remains open. The alcoholic solution of the plant inhibits the activity of macrophages *. Hexane extract shows inhibition of ER+ breast cancer cells (MCF-7). The aqueous solution contains polysaccharides that stimulate NK cells and increase the antitumor and antimetastatic activity of cyclophosphamide *; but at the same time it also contains some polyphenols, which can promote proliferation and reduce the therapeutic effect of doxorubicin *. Thus, the question of the effectiveness of echinacea in breast cancer is not completely clear.
• Black cumin (Nigella sativa), aka nigella, kalonji, due to the thymoquinone contained in its seeds, enhances the cytotoxic activity of T-lymphocytes and NK-cells * *. In addition, oral administration of non-essential nigella oil (2 ml/kg) for 12 weeks in vivo results in a significant decrease in the number of leukocytes and platelets *, an increase in the number of lymphocytes *, monocytes * and neutrophils *, as well as an improvement in the ratio of Th1:Th2 lymphocytes *.
Daily intraperitoneal injections of thymoquinone (10 mg/kg) in mice with mouse breast cancer (EMT6/P) resulted in tumor regression by 27%. And the combination of thymoquinone with piperine (25 mg/kg) reduced the volume of the existing tumor even more – up to 48%. Tumor regression was observed in 60% of the treated mice, and no experimental animals died *. In the control group, during the same period (14 days), an increase in tumor volume up to 80% was observed, and 20% of the animals died. The dosage of thymoquinone used here for mice is 10 times lower than the lethal *, and the dosage of piperine is two times lowerr than the lethal *.
Dosage of essential nigella oil: 5 ml/day (1 tsp) * * *. The dosage of non-essential nigella oil (human equivalent) taken by mouth is 5-25 ml/day (2 tbsp) *, but never more than 175 ml/day (3/4 cup) *. The oil extracted by supercritical CO2 extraction has the highest biological value *.
• Naltrexone is an opioid receptor inhibitor that increases the number and activity of NK cells * and activated T lymphocytes *. To do this, use low doses of naltrexone (1.5-4.5 mg), which are 1/10 or less of the usual dose used in the treatment of opioid dependence. Taken at bedtime for at least 2 months, low doses of naltrexone have, in addition to immunomodulatory, also analgesic and anti-inflammatory effects. Higher doses of naltrexone do not provide this effect. It is worth noting, however, that this effect of naltrexone does not occur with insufficient levels of vitamin D.
• Garlic (Allium sativum) and its active component ajoene (from the Spanish ajo – garlic). A double-blind study showed that 500 mg/day of aged garlic dry extract taken for 6 months significantly increased both NK cell count and activity in patients with advanced cancer *. Ingestion aged garlic increases the growth and activity of cytotoxic T cells and NK cells *. The combination of aged garlic with low doses of naltrexone synergistically enhances NK cell activity *.
To prepare an aged extract at home, 350 g of raw garlic cloves are mixed in a blender with 250 ml of 40% ethyl alcohol, then the resulting mass is kept in a refrigerator in a vessel with a closed lid for 5 days and filtered; further aging of the extract is carried out at a temperature of -18 °C for no more than 6 months *. The dosage of this extract: from 15 ml/day (1 tablespoon).
• Eleutherococcus (Eleutherococcus senticosus). Ingestion three times a day of 10 ml of the root extract of the plant causes a sharp increase in the number and activity of T-lymphocytes, mainly of the helper/inducer type, as well as cytotoxic cells and NK cells *.
• Sage (Salvia Miltiorrhiza). In mice, sage, at 0.5% of total food intake, inhibited serum IgE levels; and does not interfere with antibody production. And at a dosage of 2% of the total food intake, sage significantly improves the protection of rodents from pathogens without causing detrimental effects. The increased protection was associated with a significant increase in the number of peripheral monocytes and NK cells *.
An oral combination of 20mg/kg dried aqueous sage root extract and 50mg/kg polysaccharopeptide from turkey tail (Trametes versicolor) taken for 6 months improved post-treatment immune function in patients with breast cancer. This was achieved by significantly increasing the absolute values of T-helper lymphocytes, the ratio of T-helper:T-suppressor, as well as the number of B-lymphocytes in plasma *.
• One cross-sectional study compared the effects of regular black tea infusion with the addition of five Ayurvedic herbs: Ashwagandha (Withania somnifera), Licorice (Glycyrrhzia glabra), Ginger (Zingiber officinale), Basil (Ocimum sanctum), and Cardamom (Elettaria cardamomum) by weight ratio 1:1:3:1:3, respectively. The total weight of the dry mixture in one serving of the drink was 2 grams (4.5 g per 100 g of water), the daily intake was 3 cups of the drink. Although green tea also increased T-cell and NK-cell activity, confirming the results of other studies * *, in the Ayurvedic tea group after 2 months of intake their activity was even higher *.
• Metformin *, imidazole * * and xanthohumol * can decrease VEGF production in NK cells and increase their production of perforin. Levamisole, an anthelmintic and immunomodulator taken between chemotherapy courses (150 mg/day on two consecutive days per week), demonstrated higher therapeutic response and survival rates than the control group *. Levamisole gave a similar result with radiation therapy *. However, in 10% of cases, treatment with levamisole was associated with the risk of a temporary, albeit reversible, decrease in the level of leukocytes *.
• The percentage of NK cells and/or their activity is directly related to the serum concentration of zinc, selenium *, melatonin *, as well as vitamin A, vitamin D *; at least this applies to the elderly, whose levels are usually reduced. A complex supplement containing zinc (elemental zinc from 20mg/day), selenium (100 μg/day) and vitamin E (200 mg/day) helps them to strengthen the body's immune function *.
Taking 45 mg of zinc daily for one year in older people resulted in a 67% reduction in their infection rate compared to placebo *. The changes included a reduction in plasma markers of inflammation, including IL-6 and C-reactive protein *. Supplementation with 200mg of vitamin E per day, especially with vitamin C, significantly improved immune parameters, including neutrophil, T cell, B cell, and NK cell function *.
Not only chemical compounds affect the activity of natural killers. Stress affects them depressingly, and good mood, walks in nature, massage, yoga, moderate exercise, quality sleep, on the contrary, are stimulating. A leisurely two-hour walk in the woods every day can increase NK * cell activity and expression of anti-cancer proteins by up to 50% * *. Watching comedies also markedly increases the activity of natural killers *.
• Coenzyme Q10 enhances the synthesis of antibodies, macrophages, increases T-cell activity, and generally increases the survival of patients. It should be natural ubiquinone (stable ketone), not ubiquinol (chemically unstable alcohol). Ubiquinone also exhibits strong antioxidant activity. Dosage: 300-600 mg/day.
• Vitamin C. Even a small increase in blood glucose levels, such as after ingestion of simple carbohydrates, reduces the transport of ascorbic acid to immune cells *. This necessitates supplemental vitamin C (200 mg/day).
• A complex containing Reishi (Ganoderma lucidum), Dangshen (Codonopsis pilosula), Dong quai (Angelicae sinensis) and citronellol (Geranium) citronellol significantly reduced the depletion of leukocytes, neutrophils, CD4 lymphocytes and cells in a clinical study natural killer (NK) cells, improving the body's immune function and its ability to fight both cancer and secondary infections *.
• Dehydroepiandrosterone (DHEA) is a steroid hormone that plays an active role in the healthy functioning of the immune system by counteracting cortisone. It may be especially beneficial for older people, as levels of this hormone decrease with age. While DHEA levels decline drastically with age, cortisol levels remain relatively constant, resulting in an imbalance of these two hormones, which is hypothesized to contribute to immune aging *. DHEA supplementation (50 mg at night) for 20 weeks in older men with low serum DHEAS levels resulted in improved immune parameters, including monocyte levels, B and T cell function, and NK cell levels *.
• Desert-broomrape (Cistanche deserticola) *. Water-extractable cistanche polysaccharides promote maturation and function of bone marrow dendritic cells, improve IgG, IgG1, and IgG2a titers, and markedly increase T- and B-cell proliferation, IFN-γ and IL-4 production in CD4+ T cells, and expression levels IFN-γ in CD8+ T cells. In addition, cistanche reduces the activity of regulatory T cells, which will be discussed below. All together, this significantly enhances the action of both innate and specific immunity *.
The plant passed a clinical trial as part of a complex that, in addition to the ethanolic extract of cistanche (100 mg/day), included vitamin E (200 mg/day), vitamin B6 (1.4 mg/day), coenzyme Q10 (60 mg/day), zinc (15 mg/day) and fucoidan (10 mg/day). The complex was taken for 12 weeks by 25 aging people. There was an increase in the number of T helper cells, an improvement in the relative proportions of T cell types, and an increase in NK cell activity. In addition, there was a subjective reduction in fatigue as well as significant improvements in vascular function *.
• Arjuna (Terminalia arjuna) significantly increases the strength of acquired immunity in rodents *. At a dosage of 2×500mg, arjuna powder reduces immune-inflammatory markers in coronary heart disease in humans *.
• Extracts of Siberian sorbus (Sorbus sibirica), Pot marigold (Calendula officinalis) and Marshmallow (Althaea officinalis) in vitro are not inferior to tincture of Purple coneflower (Echinacea purpurea) in terms of immune response stimulation *. However, this mixture has not been clinically tested.
Other plant combinations have also been used in various studies. For example, spices such as Mint (Mentha longifolia), Cumin (Carum carvi), Black cumin (Nigella sativa) and Fennel (Foeniculum vulgare). The ethanol extract of this mixture in animals increases the phagocytic index, the number of leukocytes and lymphocytes, as well as an increase in the percentage of granulocytes *, however, the dosage of the extract, equivalent to a human, will be 5 mg/day, and in terms of the raw weight of the raw material will be prohibitively high.
In animal experiments, many medicinal plants have demonstrated the ability to control immunity through various mechanisms * *. Immunomodulatory plants * are able to suppress the growth of breast cancer cells using both innate immunity (macrophages, natural killers, neutrophils, dendritic cells) and adaptive immunity (leukocytes, T- and B-lymphocytes); especially due to cytotoxic T cells and natural killer cells (NK cells). They modulate cytokine secretion, histamine release, immunoglobulin secretion, lymphocyte expression, phagocytosis, etc. *.
Many food components have a positive effect on the normalization of immune function. For example, ω-3 polyunsaturated fatty acids, zinc, vitamins D and E, as well as probiotics, spirulina (Spirulina platensis), tea, turmeric and many others *.
The thymus gland, which plays an important role in the body's immune system, begins to decrease with age. This leads to a decrease in the production of the hormone thymulin, which promotes the creation of T-cells. Consuming just 30 mg/day of zinc rejuvenates the thymus gland in people over 65 years of age, which promotes thymulin production and improves immune function.
It is important to note that the stimulation of immune cells can reduce the concentration of vitamin D in the blood, which will entail a number of negative side effects, including those of an immune nature. Thus, a comprehensive approach should be taken to the problem of an adequate immune response, including maintaining a safe level of 25(OH)D (60-75 nM/L).
Immune cells can not only destroy a malignant tumor, but vice versa, contribute to its development.
The behavior of immune cells depends on conditions determined by external signals. Thus, in the microenvironment of an inflamed wound, inflammatory signals weaken the immune activity of macrophages. Some immunosuppressive cells are also involved in the temporary suppression of the immune response. Reducing the risk of being destroyed allows normal cells to actively divide, restoring damaged tissue.
A similar phenomenon is observed in the tumor microenvironment, which is considered by the body as a chronic wound. However, here the decrease in immune surveillance allows already cancer cells to actively divide and evade destruction.
Inappropriate behavior of immune cells contributes to the development of a tumor instead of its defeat. During tumor inception, macrophages create an inflammatory environment that promotes the growth of transforming cells. As the tumor becomes malignant, they can stimulate angiogenesis, enhance invasion and migration of malignant cells. At sites of metastasis, one subpopulation of macrophages prepares the local tissue to receive tumor cells, while the other promotes their establishment, survival, and subsequent growth *.
Thus, a simple excitation of the work of immune cells may not always provide an adequate immune response. If the performers are incompetent, or do not understand the task, then instead of a well-coordinated team, they will become an unorganized mass. And if they are aimed at a different result, then an increase in their number or an increase in their activity may have an effect opposite to the desired *. In other words, we need to properly instruct immune cells rather than spurring them on.
Macrophage phenotype modulators. There are at least 6 different macrophage phenotypes that macrophages can switch between *. Two of these are the most significant: M1 (classically activated macrophages), which are associated with pro-inflammatory tissue responses and microbial killing, and M2 (alternatively activated macrophages), which are associated with anti-inflammatory responses and wound healing.
M1 macrophages are stimulated by T-helper cell type 1 (Th1) cytokines such as interferon-gamma (IFN-γ) or tumor necrosis factor (TNF). They increase the production of pro-inflammatory cytokines (such as TNF and IL-2) as well as the concentration of free radicals. By increasing inflammation in the microenvironment, which can cause nuclear and mitochondrial damage, M1 macrophages promote early tumor development.
M2 macrophages are stimulated by T-helper cell type 2 (Th2) cytokines such as IL-4, IL-10 and IL-13. They promote tissue remodeling and repair by releasing anti-inflammatory cytokines and promoting the migration and proliferation of matrix cells. However, they are immunosuppressive and are poor antigen presenters. Most tumor-associated macrophages (TAMs) in the tumor microenvironment are closely associated with an M2-like phenotype.
Inflammatory signals (mainly cytokines * *) present at the site of injury and inflammation alter the phenotype of tumor-associated macrophages in such a way that their antitumor activity decreases. On the other hand, non-steroidal anti-inflammatory drugs (NSAIDs) and antioxidants incline them to reverse modification – from pro-tumor phenotype (M2) to anti-tumor (M1). At the same time, an increase in M1 macrophages increases inflammation, which is an unfavorable factor.
Thus, the modification of TAM phenotypes plays a complex role.
• Beta glucan. In addition to enhancing the activity of neutrophils and macrophages, beta-glucan also contributes to the phenotypic switching of macrophages *. Contained in the shell of cereals (bran), cell walls of fungi, brewer's yeast. Dosage: 200mg/day of pure beta-glucan, which is equivalent to about 200g/day of bran.
From food mushrooms, you can choose the most affordable: Oyster mushroom (Pleurotus ostreatus), Shiitake (Lentinus edodes), Maitake (Grifola frondosa). Beta-glucans and polysaccharides contained in aqueous extracts of such common tinder fungus species as Turkey tail (Trametes versicolor), real Tinder fungus (Fomes fomentarius), Red-belted conk (Fomitopsis pinicola) and Chaga fungus (Inonotus obliquus) also show high antiproliferative activity in vitro, especially the first one (Oyster) *. Dosage: 2-3 tablespoons/day of dry mushroom powder (boil for about 2 hours). While aqueous solutions of fungi increase the cytotoxic activity of natural killer cells, alcohol solutions of the same fungi can inhibit their activity *. This, in general, applies to most immunomodulatory plants *.
• Cordyceps, in addition to beta-glucan, contains a unique set of other synergistically acting bioactive substances that increase the number of killer cells *. Dosage: from 10 ml/day of cordyceps liquid extract, or 1.5-2 g/day of dry powder.
• Interferon-gamma (IFN-γ) * and interferon-alpha (IFN-α) * are a necessary element for reversing the phenotype of M2-like macrophages to M1-like. Interferon-γ (100'000-500'000 IU/day) and celecoxib (200 mg/day) reduced the M2:M1 macrophage ratio in NSCLC-grafted mice *. Interferon-γ reduced the ratio to 1.1:1, celecoxib to 1.7:1, and the combination to 0.8:1, while the ratio was 4.4:1 in the control group.
• EGCG in vitro significantly activates miR-16 in tumor cells, which can be carried by exosomes into TAMs and then prevent their accumulation and suppress their differentiation into the M2 phenotype. Intraperitoneal administration of EGCG (10 mg/kg) to mice with a grafted mammary tumor (4T1) doubled the growth of tumor volume in them *.
• Curcumin suppresses metastatic breast cancer in mice by improving the balance of M1:M2 macrophages in the tumor microenvironment *. Supplementation of curcumin to the diet of mice caused a reduction in the volume of the grafted mammary tumor compared to the control * *.
• Baicalein (50mg/kg oral every other day) is able to regulate M2 polarization in grafted mammary tumors (MDA-MB-231 and MCF-7) in mice and also attenuate TGF-β1 production *.
Unfortunately, no clinical studies have been reported for all of the above active substances in relation to the modification of macrophage phenotypes.
Another strategy is the regulation of mitochondrial respiration. Suppression of mitochondrial energy production blocks the M2 phenotype, and forces macrophages to switch to the M1 state; while an increase in oxidative metabolism, on the contrary, enhances the M2 phenotype *.
• Metformin, a well-known mitochondrial inhibitor, induces macrophages to the M2 phenotype, increasing the ratio of M1:M2 in the tumor * *, and also reduces the ratio of neutrophils to lymphocytes in the tissue after 8-16 months of administration *. The human equivalent dose, based on animal studies, is 1'500 mg/day, which is the same dosage used in the treatment of moderate type II diabetes *.
Regulatory T cell modulators. Treg cells (a subgroup of CD4+ T cells) play the role of the conductor of the immune system, trying to maintain a balance between its excitation and inhibition. They express a number of proteins that inhibit the activity of neutrophils and macrophages *. This property of Treg cells inhibits the autoimmune response, but it allows the tumor to evade detection * *. Therefore, it can be assumed that a decrease in the number or activity of Treg can enhance antitumor immunity and probably provide a better treatment outcome. However, it is worth fearing the strengthening of autoimmune processes.
Regulatory T cells suppress immune functions through various mechanisms such as immune checkpoint molecules (CTLA-4) as well as through IL-2 depletion, production of immunosuppressive cytokines and immunosuppressive metabolites *. CTLA-4 antagonists such as ipilimumab (ipilimumab), in combination with chemotherapy, improve survival in patients with metastatic progressive melanoma *. CCR4 antagonists, such as mogamulizumab, significantly reduce peripheral blood Treg cells in patients with advanced or recurrent solid tumors *.
Most currently known treatments are not able to selectively deplete or inhibit Treg cells.
Cimetidine (Tagamet™) may counteract the ability of histamine to increase the activity of regulatory T cells. Due to this, cimetidine prevents the decrease in the number of T-cells, B-cells and NK cells caused by antitumor therapy, as well as the overall antitumor immune activity * * * * * *. Interestingly, other H2 blockers such as ranitidine (Zantac™) and famotidine (Pepcid™) do not show the same immunomodulatory effects as cimetidine *.
Spirulina (1'500mg of extract for 6 weeks) has a minor Treg-lowering effect *. Another possible Treg cell modulator could be vitamin A.
Immunosuppressive myeloid cells (iMC). All-trans retinoic acid (ATRA) induces iMC differentiation into macrophages and correlates with increased antitumor immunity in mouse models *. In clinical studies, the addition of ATRA to standard chemotherapy improved the prognosis for patients with advanced non-small cell lung cancer *.
Progesterone-induced blocking factor (PIBF) is a protein that suppresses the function of immune cells (NK, T- and B-lymphocytes) and is produced in highly proliferating tissues. PIBF deactivates perforin, an aggressive protein released by immune cells to destroy the membrane of cells to be killed. Thanks to PIBF, the production of anti-inflammatory cytokines (IL-10) increases and the production of pro-inflammatory cytokines (IL-1, IL-6, TNF-α) decreases.
High expression of PIBF during pregnancy, caused by an increase in the concentration of progesterone, can protect the fetus from immune rejection and avoid miscarriage. However, the same mechanism helps the cancerous tumor to defend itself against damage by immune cells. It appears that cancer cells are able to produce PIBF themselves to increase their viability *. Temporary blocking of protesterone receptors could possibly be useful in neoplastic diseases, especially for postmenopausal women.
• Mifepristone (200 mg/day) is used clinically as an abortifacient. Mifepristone blocks progesterone receptors, preventing the release of PIBF, making cancer cells more vulnerable to an immune response. Higher doses may cause adrenal insufficiency.
• Aglepristone, another progesterone receptor blocker given by subcutaneous injection, has been shown to promote remission in animals with fibroadenomatous hyperplasia of the mammary glands *.
Clinical studies using progesterone receptor blockers have not been conducted. Only isolated cases of its effectiveness have been reported at a dosage of 200 mg/day.
In rapidly progressive lymphocytic leukemia after treatment with mifepristone, a complete remission was observed lasting 12 months *.
In end-stage colon cancer, mifepristone stabilized the condition, improved quality of life and increased patient survival *.
In advanced non-small cell lung cancer and in bilateral renal cell carcinoma, mifepristone stabilized the disease for 5 and 12 years, respectively, with a good quality of life * *.
It is hypothesized that the best time to use PR modulators is in early stage PR+ breast cancer, and that their suppression of the switch from paracrine to autocrine control will suppress CSC proliferation *. Although progesterone receptor blockers have worked well for blood cancers and some solid tumors, there is still no clinical evidence of their effectiveness in breast cancer. In addition, mifepristone has been reported to decrease free thyroxine levels *.
Nagalase inhibitors. Macrophages can be in a passive state due to their insufficient activation. The activation of macrophages is carried out by the so-called Group Macrophage Activating Factor (Gc-MAF). It is a glycosylated form of the vitamin D binding protein (Gc-globulin). Gc-MAF, which stimulates the work of macrophages, is formed from Gc-globulin as a result of its glycosylation by enzymes that are secreted by T- and B-lymphocytes.
Many cancer cells produce an enzyme called nagalase (α-N-acetylgalactosaminidase) that deglycosizes Gc-MAF back into Gc-globulin, rendering it inactive *. Thanks to nagalase, Gc-MAF levels do not increase, macrophages remain dormant, and cancer cells manage to evade attack by the body's immune cells. Inhibition of nagalase could significantly enhance the uptake of cancer cells by phagocytes.
Unfortunately, effective inhibitors of extracellular nagalase have not yet been developed, and natural inhibitors are extremely few and not strong enough. One of them is the alkaloid steviamine from Candyleaf (Stevia rebaudiana) *, however, the content of steviamine in the stevia leaf is only 15 mg per 1 kg of raw weight *. An alternative suggestion to increase the amount of Gc-MAF in the blood is the oral intake of MAF from bovine colostrum. It also ensures high phagocytic activity of macrophages *.
Gc-MAF production requires vitamin D and oleic acid (olive oil); without them, Gc-MAF deficiency can be observed even in the absence of nagalase activity. The addition of chondroitin sulfate to oral colostrum also looks very promising.
An adequate immune response requires the timely and consistent interaction of several cell types. For example, each cytokine performs several functions, and in addition, there are cross-links between different immune signals, so targeting a single one may not have a noticeable effect.
Apparently, the most effective immune therapy will be in the case of simultaneous activation of several components of the immune system *, and precisely those that show their insufficiency in each specific case. It is to be expected that combinations of different natural immune stimulants, such as those discussed above, will be more successful at lower dosages than would be the case with any of them alone.
However, the use of any additives is a last resort. Improving overall health, normalizing diet, keeping insulin and cortisol levels in check, reducing latent inflammation, getting enough exercise, normalizing circadian rhythm and exercise/rest, positive thinking, achieving your life goal, taken together, can be no less successful strategy than additives mentioned above.
And last but not least, a note. As in the case of supplements that are required only to eliminate the deficiency of vital substances, immune correction is also aimed only at eliminating the existing immunodeficiency and ensuring the coordinated and adequate work of all components of immunity. But not to an excessive strengthening of the immune response, which can lead to the most negative consequences.