Cavefish Immune System Study Provides Insights into Autoimmune Diseases

Researchers from the Stowers Institute for Medical Research studied the impact of decreased parasite abundance and infection on the immune system and evolution of cavefish. Their results were published today in Nature Ecology & Evolution.

The study characterized the immune responses of Pachón cavefish to environmental threats while drawing comparisons to a closely related species, Río Choy. While both species native to Mexico live in the river, Río Choy stay closer to the surface, which is naturally a more biodiverse enviroment. Specifically, the team wanted to understand how and why their immune responses might differ in relation to overall parasite presence. 

"One hypothesis is that certain parasites help to balance our immune system responses. In the absence of these parasites, this balance can be disturbed and as a consequence the immune system attacks our own cells in the body," co-author Robert Peuss says. "We found an incredible number of parasites in surface fish—in the gut, skin, liver, gall bladder—everywhere. But we didn't find any parasites in the cavefish," he adds.

Further examination showed reduced innate immune cells, "The reduction of innate immune cells in cavefish compared to surface fish is probably the cause for the lack of the inflammatory response," Peuss says. "This is particularly interesting since we know that in humans, higher levels of fatty tissue often mean a higher degree of inflammation, which can lead to secondary diseases such as type 2 diabetes."

Although the parallels of immune sensitivity to threats between humans and other vertebrates had been shown, "With the cavefish, we have an example to study how it developed in an environmental setting, and to look for a genetic basis of these traits,” Peuss concludes.