Molecular cloning of the Swine IL-4 receptor α and IL-13 receptor 1-chains: effects of experimental Toxoplasma gondii, Ascaris suum and Trichuris suis infections on tissue mRNA levels

IL-4 and IL-13 are multi-functional cytokines with overlapping roles in the host defense against infection. Equally important in the regulation of IL-4 and IL-13 are their associated receptors. Though, their functional receptor complexes and signaling pathways are intricate and in some cases, share common elements, the specificity of the responses, nonetheless, resides in the structure and binding of the α-chain components. This report presents the cloning of the swine receptors IL-4Rα and IL-13Rα1 and the effects of parasite infection on their transcription. Pairwise alignment of predicted amino acid sequences indicates that the swine IL-13Rα1 is 86, 83, and 72% similar to canine, human and mouse sequences, respectively. Amino acid sequence conservation is appreciably lower between the swine IL-4Rα sequence and those from equine (72%), human (66%), and mouse (49%); however, noteworthy similarities were observed in their overall predicted secondary structures predominantly among the swine, equine, and human homologues. Relative levels of receptor mRNA in tissues from swine experimentally infected with the protozoan, Toxoplasma gondii (T. gondii) or the nematodes Ascaris suum (A. suum) or Trichuris suis (T. suis), which are known to induce Th1 or Th2 host responses, respectively, were measured by real-time PCR. Results indicated that within 14 days following infection, overall mRNA levels for IL-4Rα and IL-13Rα1 were elevated in T. gondii-infected animals and reduced in A. suum-infected animals. Levels of swIL-4Rα and swIL-13Rα1 mRNA in T. suis-infected animals varied coincidentally with the course of the infection and the location of the analyzed tissue.