Cytokines' Role in Health and Disease

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),

• lymphokines,

• 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.