Fish skin adding new knowledge about the immune system
Researchers from the University of Copenhagen have studied immune responses in fish skin and mapped changes in mechanisms that occur in connection with immune diseases in humans and animals. The findings have been published in the scientific journal PNAS (Proceedings of the National Academy of Science).
The immune system of fish resembles that of humans, both in terms of the production of immune cells, antibodies and the many regulating molecules that make the entire system perform like a symphonic orchestra at its very best. A team of biologists and veterinarians recently made a new, promising discovery in infected trout while studying fish farming conditions:
“To our big surprise, we discovered that the immune response is milder when the fish has been in contact with a particular parasite, mitigating the effects of illnesses with for example reduced inflammation,” says professor Kurt Buchmann from the Department of Veterinary Disease Biology, at the Faculty of Health and Medical Sciences, University of Copenhagen.
He is leading the research team behind several fish skin studies, which were recently published in the Journal of Fish Diseases and PNAS.
Parasite reduces immune response
The new studies show that fish skin can initiate immune responses, and, perhaps more importantly; in one of the parasites studied, the researchers found that the change goes from a so-called type 1 response to a milder version called type 2, involving reduced inflammation. The finding is interesting because doctors and veterinarians have observed a similar type 1 response in immune diseases in humans and animals.
You might think, the ideal situation is as strong an immune system response as possible, but that is not the case. Inflammation is the body's way of healing itself, but there it is a fine line between a healing effect and a damaging effect.
Inflammation is a delicate balancing act, which may get out of control and pave the way for immune diseases such as intestinal inflammation and rheumatism. It may therefore prove very useful for a number of diseases, if we in the long term can alter the immune response.
The researchers initially set out to study how to most easily get rid of two unpleasant parasites (Ichthyophthirius multifiliis and Ichthyobodo necator), which both cause problems in the fish farming industry. But during their studies, they also – unexpectedly – discovered that the Ichthyobodo necator parasite changes and reduces the immune response in infected fish. This is the change, which biologists and veterinarians now wish to inspect closely.
Treatment tested in new zebra fish experiments
Fish originated as primitive vertebrates about 450 million years ago, and during evolution we humans have merely refined a number of the defence mechanisms of fish. The basic elements in our immune systems thus originate from fish. Kurt Buchmann therefore hopes, that the experiences from fish experiments can provide an insight into the potential for reducing inflammation in immune diseases in both humans and animals.
“We have now initiated a zebra fish experiment, in which we try to treat an immune disease in fish using specific parasites. It may bring us closer to an understanding of how we can reduce immune responses,” says Kurt Buchmann.
Professor Kurt Buchmann
Department of Veterinary Disease Biology
Cell phone: +45 23 98 30 65
Read the publication in PNAS (Proceedings of the National Academy of Science)
Fish as animal models
Since the early 1990s, the use of fish as a model for human diseases has become increasingly widespread. It may be less complicated to use fish than large animals as laboratory animals and, of course, far less complicated than conducting tests in humans. If the fish is subjected to interventions during the test, it is anaesthetised beforehand, explains Kurt Buchmann, who stresses that “fish should be treated with great care and respect”.