Immunity and Cancer

Cancer is one of the most significant health challenges that kill millions of people every year. It is considered a large group of diseases characterized by uncontrolled growth and proliferation of abnormal cells with the ability to infiltrate other tissues and organs of the body. Several therapeutic approaches are available for cancer treatment, including surgery, radiation, chemotherapy, hormone therapy, and other therapies with success up to some extent. However, it is challenging to treat advanced cancer, and research is still going on to develop novel strategies such as stimulation of the inherent ability of our immune system to attack tumour cells. It has been observed that the immune system plays a vital role in the fight against diseases by recognizing native and non-native cells. These foreign cells may be exogenous microbes or endogenous altered or transformed cells. The immune system, which recognises foreign particles as non-native and responds by destroying these disease-causing agents, also plays a similar role in protecting the body from cancer. The mutated cancer cells frequently produce abnormal proteins known as tumour antigens. The immune system likely encounters and eliminates these cancer cells considering them as non-self. Cancer could affect the body when the immune system misses identifying and responding to these cells. Cancer cells that evade detection can be explained by many proposed mechanisms such as:

• Down-regulation of primary histocompatibility class 1 (MHC) expression that allows antigen not to be recognised
• Loss or alteration of the MHC molecule due to lack of co-stimulatory signals needed for antigen presentation
• Secretion of immunosuppressive products by cancer cells that inhibit the immune response of the body
• Causing antigen modulation, where the antigen either enters the cell or leaves it completely, limiting the ability of the immune system to recognise the cancer cells as non-self
• Cancer cells not giving off inflammatory warning signals.

Types of Immunity

Immunity can be active or passive. Active immunity targets cancer cells explicitly via the body's immune system. Active immunity includes cancer vaccines, cell-mediated CAR-T cell therapy, and targeted antibody therapies. Passive immunity does not directly target cancer cells but enhances the immune system's ability to attack cancer cells. Passive immunity includes checkpoint inhibitors and cytokines. Checkpoint inhibitors target proteins that usually dampen the immune response, whereas cytokines directly stimulate the immune system and increase immune activity.

In the late 19th century and the beginning of the 20th century, the concept emerged that activating the immune system might be a strategy for attacking cancer cells. Many scientists engaged in intense basic research, uncovered fundamental mechanisms for regulating immunity, and showed how the immune system could recognize cancer cells. In 2018, the Nobel Laureates Allison and Honjo used different methods for inhibiting the brakes on the immune system to treat cancer, which constitutes a landmark in our fight against cancer.

Accelerators and Brakes in our Immune System

Our immune system, mainly T cells, can discriminate self from non-self, attack and eliminate invading bacteria, viruses, and other microorganisms. T cells have receptors that bind to structures recognized as non-self, and such interactions trigger the immune system to engage in defense. But additional proteins acting as T-cell accelerators are also required to start a full-blown immune response, whereas other proteins that function as brakes on the T cells inhibit immune activation. This complex balance between accelerators and brakes is essential for tight control.

A new principle for Immunotherapy

Cancer immunotherapy, also known as immune-oncology, stimulates the immune system and improves its natural ability to fight cancer. It is becoming a subspecialty of oncology and an application of the fundamental research of cancer immunology. Cancer immunotherapy works because cancer cells often have antigens on their surface that the immune system's antibody can detect. The cancer cell antigens are usually proteins or other macromolecules. Normal antibodies bind to external pathogens, but the modified immunotherapy antibodies bind to the cancer cell antigens, marking and identifying the cancer cells for the immune system to inhibit or kill.

Current research is identifying new potential targets to enhance immunity. Different types of immune-enhancing herbs and medicinal plants have been described in Ayurveda that are quite helpful in improving overall immunity. Herbs are beneficial for health due to their antioxidants, anti-inflammatory, immunomodulatory, and anti-microbial properties. Some of the commonly described herbs which help to boost immunity are as follows:

1. Ashwagandha (Withania somnifera)

Ashwagandha effectively improves brain cell function, nervous exhaustion, anxiety, and depression. It also relieves fatigue. Ashwagandha acts as an adaptogen and anti-stress, which helps to bring the body's stress response to normal levels. Ashwagandha plays a vital role in immunity as it improves the action of natural killer cells which are a part of the innate immune system. Studies show that Ashwagandha also helps to increase the natural killer cells. The antioxidants found in ashwagandha help in boosting the immune system. Due to its inflammatory property, Ashwagandha helps reduce the number of C-reactive proteins in the body.

2. Amla (Emblica officinalis)

It is one of the richest sources of vitamin C and enhances overall immunity due to its rejuvenating and revitalising properties. Amla stimulates the regeneration of red blood cells and helps improve haemoglobin content in the body, and it also helps reduce mental and physical fatigue and boost immunity.

3. Ginger (Zingiber officinalis)

Anti-microbial compounds in ginger help fight infections and boost immunity. Ginger is also recommended for many respiratory ailments like cold, cough, pneumonia, asthma, and bronchitis. Ginger has potent anti-inflammatory and antioxidant properties. Studies show that ginger significantly reduces levels of inflammatory proteins like tumour necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6), interleukin-1 beta (IL-1-beta), and C-reactive protein (CRP).

4. Tulsi (Ocimum sanctum)

Tulsi is used in respiratory tract infections like cough, cold, sore throat, asthma, etc. This natural stimulant energizes our body, increases circulation, and has been proven beneficial in many diseases. Fresh tulsi juice helps to improve immunity.

5. Giloy (Tinospora cordifolia)

Giloy, commonly known as Guduchi, improves learning and memory. It works as an immunomodulator, stimulates natural killer cells, B cells, and T cells, and helps produce various immune-stimulatory cytokines. Giloy also reduces the elevated total leucocyte count (TLC), neutrophil and eosinophil counts. In another study, giloy showed an increase in the white blood cell (WBC) counts, bone marrow cellularity, serum Immunoglobulin concentrations which further validated the immunomodulatory potential of giloy.

6. Turmeric (Curcuma longa)

Turmeric, the "Indian saffron," shows a pivotal role in modulating the immune system. Turmeric lowers cortisol levels which in turn help in maintaining balance in the immune system. Studies also proved that turmeric helps in regulating the activity of immune cells.

7. Mulethi (Glycyrrhiza glabra)

Mulethi is an excellent home remedy for its anti-microbial action. The root helps improve immunity and is a natural revitaliser and anti-ageing agent. Some studies have also shown a positive effect of mulethi concerning brain functions.