The aetiology of human diseases is full of complexity, and so is our immune system. In the prevention of diseases, the human body depends on a process called the cell signaling pathway, which involves a chain of chemical reactions between a cluster of molecules within a cell that control the function of a cell, for instance, cell division or cell death.
When a substance, such as a hormone or growth factor attaches to a particular protein receptor on or in the cell, the cell gets signals from its environment. The first molecule receives a signal in the pathway, activating a subsequent molecule. This procedure is repeated along the whole signaling pathway until the final molecule is activated and the cell function is carried out.
Cellular signaling is essential in mediating immune response. Most often, defects and abnormalities in cellular pathways are the root cause of many diseases like cancer, respiratory and autoimmune disorders.
Studies confirm that cytokines are important in cellular signaling. These small proteins, released by cells, affect the behaviour of other cells. Cytokines, acting as messengers between cells, are responsible for regulating the development and function of other blood and immune system cells.
In this article, we demystify the role of cytokines by explaining how they work, their types, their functions, and their importance in health and disease.
What are Cytokines?
Medically speaking, cytokines are multifunctional polypeptide hormones or small proteins, non-structured and light in terms of molecular weight, that are released by several types of cells. These proteins influence and regulate a range of biological processes such as immunity and inflammation. Cytokine proteins are soluble and are vital to our immune system. Cytokine portfolio is crucial to the functions of macrophages that act as guards to the innate immune system and bring about the conversion from innate to adaptive immunity.
In other words, they act as messengers and mediate complex synergies between immune and non-immune cells, such as:
- hematopoietic cells,
- lymphoid cell, and
- various pro-inflammatory and anti-inflammatory cells that stimulate the growth of inflammatory and immune responses.
Cytokine activity was recognised and established between the years 1940- 1960. There are about 200 cytokines that have been recognized to date.
Based on their properties, their secretion, and effect on the immune response, cytokines can be broadly divided into the following categories:
Proinflammatory cytokines: These cytokines are associated with inflammatory responses (amplification and perpetuation of the inflammatory process).
Growth factors: These cytokines promote cell survival and bring about structural changes in the airways.
Anti-inflammatory: Anti-inflammatory cytokines control the pro-inflammatory cytokine reaction.
What are the different types of cytokines?
Since Cytokines have several diverse biological functions, there are many different types of Cytokines. Cytokines being a broad term, some of the more specific proteins that fall under this family based on their functions include:
- chemokines (CC, CXC, CX3C, and XC),
- interferons (IFN)
- interleukins (IL),
- tumour necrosis factor (TNF) and
- growth factors.
Chemokines play a vital role in the migration of leukocyte cells and are related to chemotactic effects for inflammatory cells.
Interferons aid the body’s defence against cancer and viral diseases.
Lymphokines are produced by lymphocytes. These cytokines attract immune cells such as macrophages. These cytokines are secreted by T cells (that grow from stem cells in the bone marrow) and control the immune response.
Interleukins are a group of cytokines that act as chemical signals between white blood cells and are produced by a single leukocyte. They can act on other leukocytes, mediating interactions among cells. Specific interleukins can have a significant impact on cell-cell communication.
Tumour necrosis factor or TNF cytokines are released in case an infection is detected by macrophages (specific white blood cells) to signal other cells of the immune system to trigger an inflammatory response.
When discussing cytokines as growth factors, it is necessary to note growth factors signal a positive effect on cell division, whereas cytokine is a term that is neutral for whether a molecule has an impact on reproduction. While some cytokines can operate as growth factors, others can impede cell growth. Some trigger programmed cell death in target cells by acting as “death” signals. For instance, cytokines promote anti-cancer activity and help prevent disease by releasing signals that can cause abnormal cells to die and normal cells to live longer.
What are the functions of cytokines?
Cytokine proteins act through receptors found on the membranes of responsive target cells and are essential in the immune system.
- modulate the balance between humoral and cell-based immune responses,
- induce inflammatory response,
- regulate hematopoiesis,
- differentiate and induce wound healing, and
- regulate certain cell populations’ maturation, growth, and responsiveness.
In addition, cytokines frequently trigger the production of new cytokines, causing a cascade of events in which the latter cytokines affect the activity of the previous cytokines that released them.
Lastly, due to their brief half-lives in the blood and extracellular fluids, they have a short functional range.
How are cytokines produced?
Cytokines are mainly produced by a broad range of cells, including immune cells like:
- B lymphocytes,
- T lymphocytes and
- mast cells.
These proteins can also be produced by endothelial cells, polymorphonuclear leukocytes (PMN), epithelial cells, connective tissue, and adipocytes.
What is the importance of cytokines in health and disease?
They are essential in health and disease, specifically in host responses to infection, immune cell differentiation and responses, trauma, inflammation, sepsis, reproduction, viral pathogenesis, neurobiology, angiogenesis, tumorigenesis, etc. Apart from innate and adaptive immunity, cytokines are now also significant in the fields of cancer and atherosclerosis.
Cytokines can therefore contribute in therapy and as prognostic and diagnostic agents while also being effective biomarkers for health and disease. Cytokines in therapy such as IL-1 and IL-2 are likely to act as natural immuno-stimulants to fight against the immune deficiency of AIDS. This hypothesis is supported by experimental and clinical studies which state that immune-stimulant cytokines have a potential to aid in the neutralisation of the immune-suppression of cancer and AIDS.
Specific cytokines used in treating cancer can be produced in a lab. Some cytokines are effective in reducing or controlling the side effects of chemotherapy. Interleukins and interferons are the most used.
Helvetica Health Care (HHC) specialises in the production and supply of CELLKINES™ product line that consists of Human Interleukin-2 (IL-2), also referred to as T-CELL GROWTH FACTOR (TCGF). Natural Human IL-2 remains the preferred choice for lymphocyte cell stimulation in culture. Additionally, Recombinant IL-2 produced in E. coli is also available.
At HHC, we strive to supply innovative life science products and technologies of the highest quality to manage health and improve the quality of life. Thanks to our successful partnerships with our collaborators, we guarantee timely and risk-free deliveries with optimal care within 48 hours from our warehouse in Geneva.
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