The interleukin (IL)-10 cytokine family includes IL-10, IL-19, IL-20, IL-22, IL-24, IL-26 and the lambda/type III interferons. They are highly pleiotropic and mediate a variety of activities, including immune suppression and antibacterial immunity. To exert their functions they signal through a heterodimeric receptor composed of a subunit with a long intracellular domain (R1 type receptors; IL-10R1, IL-20R1 or IL-22R1) and a subunit with a short intracellular domain (R2 type receptors; IL-10R2 or IL-20R2). In this study we report the identification of three R1 type receptors (named IL-10R1/CRFB7, IL-20R1a/CRFB8a and IL-20R1b/CRFB8b) and one R2 type receptor (named IL-10R2/CRFB4) in rainbow trout. The nomenclature of the receptors was supported by homology analysis, conserved motifs and phylogenetic tree analysis, confirming they belong to the piscine class 2 cytokine receptor family. For instance, they all displayed the presence of characteristic features, such as conserved fibronectin type-III domains. Expression analysis in tissues collected from healthy fish revealed different patterns of expression for each receptor, suggesting their potential involvement in different types of immune responses. When studying the modulation of the genes in cell lines and primary cultures, a greater effect was observed in the cell lines, where the expression of most receptors was affected by incubation with microbial mimics (LPS and PolyI:C) or the pro-inflammatory cytokine rIFN-γ. In addition, expression of the four receptors was modulated by viral infection, suggesting a potential involvement of such receptors and their ligands in antiviral defence.
Bibliographical noteThis work was supported financially by a PhD studentship from the FCT (Foundation for Science and Technology, Portugal) and POPH/FSE (Grant no. SFRH/ BD/ 38236/ 2007) to Milena M. Monte, and the European Commission Contract No. 007103 (IMAQUANIM-Improved immunity of aquacultured animals). Tiehui Wang received funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland). We also acknowledge Maria M. Costa and Patricia Díaz-Rosales for preparing the samples from the head kidney leucocyte experiment, and Wenshu Huang for the cell line samples.
- Oncorhynchus mykiss
- class 2 cytokine receptor family (CRF2)
- cell lines
- head kidney leucocytes
- in vitro stimulation
- viral infection