Local lung responses following local lung challenge with recombinant lungworm antigen in systemically sensitized sheep

• Published in: Clinical and experimental allergy Vol. 31; no. 10; pp. 1636 - 1647
• Main Authors: Collie, D. D. S., MacAldowie, C. N., Pemberton, A. D., Woodall, C. J., McLean, N., Hodgson, C., Kennedy, M. W., Miller, H. R. P.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science, Ltd 01-10-2001; Blackwell
• Subjects: Animals; antigen challenge; Antigens, Helminth - pharmacology; Biological and medical sciences; Bronchial Provocation Tests; Bronchoalveolar Lavage Fluid - cytology; Cell Count; Chymases; Dictyocaulus - immunology; Dictyocaulus viviparus; DvA-1 antigen; Eosinophils - metabolism; Female; General aspects; immune response; Immunization; Immunoglobulin G - metabolism; Immunohistochemistry; Immunopathology; inflammation mast cell proteases; Leukocyte Count; Lung - cytology; Lung - metabolism; lung segment; Male; Mast Cells - metabolism; Medical sciences; Models, Animal; Neutrophils - metabolism; Recombinant Proteins - pharmacology; Serine Endopeptidases - metabolism; Sheep; TGF-β1; Transforming Growth Factor beta - metabolism; Animal model; Immune response; Enzyme; Antibody; Lung; Inflammation; Antigen; Peptidases; Vertebrata; Local immunity; Mammalia; Bronchoalveolar lavage; Animal; Endopeptidase; Hydrolases; Sheep; Mast cell; Sensitization; Artiodactyla; Transforming growth factor β1; Ungulata; Provocation test
• ISSN: 0954-7894; 1365-2222
• DOI: 10.1046/j.1365-2222.2001.01225.x

Background Chronic mast cell‐mediated inflammation may contribute significantly towards the extensive tissue remodelling that is a feature of lungworm infection in ruminants. Understanding the factors that control tissue remodelling is a necessary step toward effective management and treatment of conditions that feature such pathology.
Objective We sought to define in a novel ovine model system, the cellular, immune and mast cell phenotypic events that occur following local lung challenge with a recombinant protein antigen, DvA‐1, derived from the ruminant lungworm nematode, Dictyocaulus viviparus.
Methods Two spatially disparate lung segments in systemically sensitized sheep were challenged on three occasions with DvA‐1 (3xDVA) and two further segments were challenged with saline (3xSAL). Two months after the third challenge, one of the two segments previously repeatedly challenged with DvA‐1 was challenged again with DvA‐1 (3xDVA:DVA) whilst the other was challenged with saline (3xDVA:SAL). A similar protocol was followed with the saline challenged segments (3xSAL:SAL and 3xSAL:DVA). Bronchoalveolar lavage fluid (BALF) (n = 16) and tissue (n = 3) were collected after the last challenge.
Results Cellular changes 24 h after the fourth challenge were characterized by an increase in the absolute numbers of neutrophils and eosinophils in BALF from 3xDVA:DVA and 3xSAL:DVA segments. Local antibody production was implied through increased levels of antibody in both 3xDVA:DVA and 3xDVA:SAL segments, with the latter being unaffected by inflammation. Levels of active transforming growth factor beta‐1 (TGF‐β1) were significantly increased in 3xDVA:SAL segments and a trend towards an increase was apparent in 3xDVA:DVA segments. Total TGF‐β1 levels were significantly correlated with eosinophil counts in all except the 3xDVA:SAL segments. Such changes in the bronchoalveolar space were complemented by increased ratios of sheep mast cell proteinase‐1 expressing cells and tryptase expressing cells, to toluidine blue positive cells in airways from 3xDVA:DVA segments.
Conclusion Mast cell phenotypic events occurring as a consequence of antigen challenge were limited to segments in which changes in BALF were characterized by neutrophil influx and increased local antibody production.