Zebrafish il-4 il-10 regulated immunity in gills

The evolutionary origin of vertebrate type 2 immunity is a topic of great interest. Several studies have focused on the immune cell components of evolutionary older vertebrates such as fish. However, how fish cytokines function and whether they have similar roles as in mammals is still a matter of speculation. Here, we have used the zebrafish (Danio rerio) to gain insights into il4/13a and il4/13b genes and characterized their role under both homeostatic and inflammatory conditions. We established knockouts for both il4/13a and il4/13b genes and showed that they are needed to suppress inflammation in larvae and in the gill mucosa. As a counterpoint, we examined the gills of il10 defective zebrafish and revealed the importance of il10 in maintaining homeostasis in this mucosal tissue. As in mammals, zebrafish il10 appears to have an anti-inflammatory function.