Innate BALB/c Enteric Epithelial Responses to Trichinella spiralis: Inducible Expression of a Novel Goblet Cell Lectin, Intelectin-2, and Its Natural Deletion in C57BL/10 Mice

Abstract

Infection of mice with the nematode parasite Trichinella spiralis induces changes in the proteome of the jejunal epithelium, including substantial up-regulation of a novel variant of interlectin. In this study we sequence this novel lectin, termed intelectin-2, and compare expression levels during T. spiralis infection of resistant (BALB/c) with susceptible (C57BL/10) mouse strains. Intelectin-2 was cloned and sequenced from BALB/c mRNA extracted on day 14 of infection, and was found to have 91% amino acid identity with intelectin (within our study termed intelectin-1). Intelectin-2 transcripts were up-regulated early (day 3) during infection with T. spiralis in BALB/c mice, suggesting an innate response, and levels remained high through to day 14 (time of parasite rejection). Immunohistochemistry of jejunal sections with a rabbit polyclonal Ab to Xenopus laevis 35-kDa cortical granule lectin (XL35; 68% identity with intelectin-2) followed a similar pattern, with intense labeling of goblet and Paneth cells at day 14. However, intelectin-2 transcripts and protein were absent, and immunohistochemistry negative when C57BL/10 mice were infected with T. spiralis. Genomic PCR and Southern blotting confirmed that the intelectin-2 gene is absent from the C57BL/10 genome. The presence of intelectin-2 in resistant BALB/c mice, its absence from the susceptible C57BL/10 strain and the kinetics of its up-regulation during T. spiralis infection suggest that this novel lectin may serve a protective role in the innate immune response to parasite infection.