Canine Interleukin-5: Molecular Characterization of the Gene and Expression of Biologically Active Recombinant Protein

Abstract

Interleukin-5 (IL-5), which is produced primarily by type 2 T helper lymphocytes (Th2), is an eosinophil differentiation and activation factor. Increased numbers of eosinophils in peripherial blood or tissues (eosinophilia) are observed in asthmatic human patients, in animals with helminth infections, and in dogs with allergic diseases. Antagonism of IL-5 activity is being explored as a potential treatment of a number of disease conditions associated with eosinophils in animal models. In order to study the expression and function of this cytokine in the dog, we have isolated and characterized the canine IL-5 gene. The canine IL-5 polypeptide deduced from the cDNA is composed of 134 amino acids that share varying degrees of homology with IL-5 isolated from several mammals. The genomic structure of the canine IL-5 gene consists of four exons and three introns in the coding region, similar to that of the previously characterized human and mouse IL-5 genes. Recombinant canine IL-5 protein, expressed in Pichia pastoris, is biologically active in a cell proliferation assay. Canine IL-5 gene sequences and the biologically active protein described in this study will be useful reagents for future studies of this cytokine in physiologic processes and in pathologic conditions of the dog.

Canine eosinophilic gastrointestinal disorders

“…They originate and develop from pluripotent stem cells in the bone marrow. The regulation of eosinophil expansion is controlled by eosinophilopoietins, interleukin-1 (IL-1), IL-3, IL-5, and granulocyte-macrophage colony-stimulating factor (GM-CSF) (Yang et al, 2001; Rothenberg and Hogan, 2006). Primitive stem cells become eosinophilic precursor myeloblasts in the presence of IL-1, IL-3, and GM-CSF (Yan and Shaffer, 2009).…”

“…Eosinophilia is not pathognomonic of eosinophilic enteritis, so intestinal biopsies are needed for diagnosis (Yang et al, 2001; Yan and Shaffer, 2009). Biopsies of both the duodenum and ileum should be evaluated for a diagnosis of small intestinal inflammation (Dossin et al, 2007).…”