What are Cytokines?
Cytokines are a group of proteins, peptides and glycoproteins produced by specific cells of the immune system. They are signalling molecules that control and regulate immunity, inflammation and hematopoiesis.
Where are Cytokines Produced?
Cytokines are produced by a wide range of immune cells. This involves a broad range of cells, including macrophages, B lymphocytes, T lymphocytes and mast cells, as well as endothelial cells, fibroblasts, and various stromal cells. Some cytokines may be produced by more than one type of cell.
More can be learned about the various types of immune cells in another blog post.
Specific Types of Cytokines
The term cytokine is a general term – there are other special types of cytokines such as:
Inflammatory abnormalities are seen in a wide range of human disease, including certain autoimmune disease. Cytokines are regulators of our body’s response to infection, immune response, inflammation and trauma. Proinflammatory cytokines are those that worsen inflammation and promote it.
We have two main groups of inflammatory cytokines.
- Those involved in acute inflammation
- IL-1, TNF-α, IL-6, IL-11, IL-8
- Those involved in chronic inflammation
- Humoral inflammation: IL-3, IL-4, IL-5, IL-6, IL-7, IL-9, IL-10, IL-13, and transforming growth factor-b (TGF-b)
- Cellular inflammation: IL-1, IL-2, IL-3, IL-4, IL-7, IL-9, IL-10, IL-12, interferons (IFNs), IFN-g inducing factor (IGIF), TGF- β, and TNF- α and TNF-β
Target Inflammatory Cytokines in Treatment
By administering pro-inflammatory cytokines to humans: we will produce fever, inflammation, tissue destruction and in some cases shock and death.
We can target treatment through several ways:
- neutralizing antibodies
- blocking cytokine receptors
- Inhibiting proteases that convert inactive precursors to active, mature molecules
Blocking IL-1 and TNF has been found to be highly successful in patients suffering from rheumatoid arthritis, irritable bowel disease as well as graft-vs-host defense.
It may be difficult to target every one of the inflammatory cytokines listed above, but we can focus on IL-1 and TNF (and in some cases IFN- γ). These particular cytokines work together to initiate a cascade of inflammatory mediators. Think of these as triggers which get the whole process started.
Overall inflammation in the body is based on the balance between these anti-inflammatory cytokines and the pro-inflammatory cytokines discussed above.
The anti-inflammatory cytokines are:
- IL- receptor antagonist, IL-4, IL-6, IL-10, IL-11, IL-13
IL-6 is considered inflammatory or anti-inflammatory based on the circumstance. The immune system is a confusing network, where some of the anti-inflammatory cytokines can exert inflammatory properties as well.
IL-10 a Major Anti-inflammatory
Of all the above cytokines, IL-10 is the most anti-inflammatory. It represses the inflammatory cytokines (namely TNF-α, IL-6, IL-1)
When patients with neuropathic pain were given IL-10 (as a treatment, in a lab setting), it was found to be very helpful with pain.
Those with chronic widespread pain have been found to have low IL-10 and IL-4.