Inflammation and the immune system
Inflammation is the medical term for swelling, a process that aims to protect an organism against infections, and physical and chemical damage. Inflammation is a complex reaction that is initiated when immune cells register neurotransmitters that reveal that something is wrong in an area of the body.
A normal inflammation process aims to both render harmless the infection agents and repair any tissue damage. To achieve these aims, delicate control of the transmitters is required that both strengthen and impair this process.
If the reaction is too weak, this may mean that the threat is not eliminated. If the inflammation is too strong, this may lead to tissue destruction and disease. A balanced immune response is therefore crucial for the outcome of the inflammation.
To achieve an optimum inflammatory process, it is important that both the activating inflammatory mechanisms and the deactivating anti-inflammatory mechanisms function, and that there is an optimum balance between them.
Omega-3/6 Controlling inflamattion
A balanced inflammatory process is important for the positive outcome of an infection. A key component is the balance between omega-3 and omega-6.
In brief, omega-3 fatty acids produce anti-inflammatory signals and omega-6 fatty acids produce inflammatory neurotransmitters.
We need omega-3 to stop the inflammatory process when the danger has passed and because inflammation is useful and necessary in the fight against disease, omega-6 fatty acids are also important.
Omega-6 has acquired a bad reputation but it is important that we have access to this group of fatty acids as well, but on a smaller scale. How much we have access to from each of these groups can determine the outcome of inflammation.
Many of the diseases that are relevant in the aquaculture industry today are caused by infections where tissue damage is partially caused by an unhindered inflammatory response.
The viral diseases CMS and HSMB are so described as they create inflammation and damage in the heart muscles, and it is this damage that probably causes death more than the virus itself.
If the body does not manage to produce signals that turn off the inflammatory response, this can lead to weakened heart tissue that in the long term will be harmful and make the fish more susceptible to stress.
Plenty of evidence indicates that proper access to the anti-inflammatory fatty acid omega-3 in feed will help to stop the harmful process when the danger has passed and will thereby contribute to limiting mortality in connection with these diseases.
THE IMMUNE SYSTEM IS A COLLABORATIVE PROJECT
Our immune system is divided into specific and non-specific defences. The non-specific or general defences primarily comprise physical barriers, such as the skin outside the body or the mucosa inside the body, that keep out pathogenic substances.
Inflammation is the body's reaction to these barriers being breached and the occurrence of a threatening situation. Tissue contains a range of immune cells that are ready to quickly detect, attack and raise the alarm if they discover something that may be harmful. Substances released by damaged cells will also trigger this reaction.
The specific defences comprise immune cells that combat specific infections through the production of antibodies. This defence is slow, but provides longer lasting protection.
The immune system is composed of a range of components. The skin is a part of the external defences and is a physical barrier that keeps out viruses, bacteria, parasites and fungi, substances that can cause damage if they enter the body.
Fish live in contact with water, which is an effective transport medium for pathogenic substances, and are therefore more dependent on non-specific defences that are ready and react quickly to a threat. The mucous layer of fish is part of the external defences and contains substances that make it less beneficial for infection agents to attach the fish.
There is also mucus on the surface of the digestive organs of the fish. Intake of food and water also leads to this surface being in direct contact with threats from the surroundings. Research shows that a thicker and stronger mucous layer can protect against many diseases and parasites.