Isolation and Characterization of a Novel Eosinophil-specific Galectin Released into the Lungs in Response to Allergen Challenge

Abstract

A novel galectin cDNA (galectin-14) was cloned from ovine eosinophil-rich leukocytes by low stringency reverse transcriptase-PCR and cDNA library screening. Data base searches indicate that this gene encodes a novel prototype galectin that contains one putative carbohydrate recognition domain and exhibits most identity to galectin-9/ecalectin, a potent eosinophil chemoattractant. The sugar binding properties of the recombinant molecule were confirmed by a hemagglutination assay and lactose inhibition. The mRNA and protein of galectin-14 are expressed at high levels in eosinophilrich cell populations. Flow cytometry and cytospot staining demonstrate that the protein localizes to the cytoplasmic, but not the granular, compartment of eosinophils. In contrast, galectin-14 mRNA and protein were not detected in neutrophils, macrophages, or lymphocytes. Western blot analysis of bronchoalveolar lavage fluid indicates that galectin-14 is released from eosinophils into the lumen of the lungs after challenge with house dust mite allergen. The restricted expression of this novel galectin to eosinophils and its release into the lumen of the lung in a sheep asthma model indicates that it may play an important role in eosinophil function and allergic inflammation.The immune response of mammals to multicellular parasite infections and allergens is characterized by the recruitment of eosinophils (1, 2). The role eosinophils play in both parasite infections and allergic reactions remains controversial, and little is known of the specific function of eosinophil constituents in combating multicellular parasites or exacerbating allergic responses. The presence of eosinophils and eosinophil-derived products in the respiratory tract does, however, correlate with the pathological manifestations of allergic asthma (2-4).One of the limitations in the study of eosinophils is the scarcity of this cell population in normal individuals and the difficulty in obtaining sufficient numbers of unmanipulated cells from allergic tissues. Sheep offer a unique experimental system in which large numbers of eosinophils can be obtained using the relatively non-invasive procedure of mammary infusion of allergens followed by "milking" of the mammary gland to obtain the inflammatory cells recruited into the lumen (5, 6). Using this experimental system, the present study describes the identification of a novel galectin (galectin-14) specifically expressed by eosinophils. The expression of galectin-14 was up-regulated in the lung tissue of sensitized sheep challenged with house dust mite extract (HDM), 1 and the protein was released into the bronchoalveolar lavage (BAL) fluid.Galectins are carbohydrate binding proteins that have been increasingly implicated in both adaptive and innate immune responses. The eosinophil-specific expression of galectin-14 and its secretion into the lumen of the lung in a sheep asthma model indicates that it may play an important role in regulating the activity of eosinophils during allergic responses and further highlights the i...

Galectins and collectinis expression are increased in Haemonchus contortus-infected corriedale sheep

“…This galectin is considered to be an eosinophil-specific protein (DUNPHY et al, 2002): it is abundantly present in the mucus of the gastrointestinal tract after parasite challenge (ROBINSON et al, 2011) and has a strong ability to promote adhesion and alter mucus properties during infection (YOUNG et al, 2009). Interestingly, no strong correlation between eosinophil counts and Gal14 gene expression levels was observed, thus coinciding with the results found by Robinson et al, (2011) in sheep after experimental infection with H. contortus.…”

Galectin-15 in ovine uteroplacental tissues

“…In the present study, analysis of galectin-15 in uterine flushes indicated that secreted extracellular galectin-15 is in a multimeric form, particularly as the amount of galectin-15 mRNA increases in the endometrial LE and sGE and galectin-15 protein increases in the uterine lumen on days 14 and 16 of pregnancy (Gray et al 2004). Other galectin family members are known to homodimerize and form multimers (Cho & Cummings 1996, Yang et al 1998, Dunphy et al 2002. The effects of galectin multimerization on biological function are not well understood, particularly in regard to ability of galectins to bind to glycoproteins and/or glycolipid receptors and initiate biological responses.…”

Galectin-1 is a stromal cell ligand of the pre-B cell receptor (BCR) implicated in synapse formation between pre-B and stromal cells and in pre-BCR triggering

“…Galectins are a large family of calciumindependent S-type lectins, widely conserved in animals, plants, and microorganisms and with specificity for galactose derivatives. Fourteen galectins have been identified in mammals (25,26). GAL1 consists of a single carbohydrate recognition domain (CRD) with a short NH 2 sequence and occurs naturally as noncovalently bonded dimers (27).…”