Local lung responses following local lung challenge with recombinant lungworm antigen in systemically sensitized sheep.
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-beta(1)) were significantly increased in 3xDVA:SAL segments and a trend towards an increase was apparent in 3xDVA:DVA segments. Total TGF-beta1 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.


CONCLUSIONS
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.
Collie
D D
DD
Wellcome Trust Centre for Research in Comparative Respiratory Medicine, The University of Edinburgh, Easter Bush Veterinary Centre, Roslin, Midlothian, UK. dcollie@vet.ed.ac.uk
MacAldowie
C N
CN
Pemberton
A D
AD
Woodall
C J
CJ
McLean
N
N
Hodgson
C
C
Kennedy
M W
MW
Miller
H R
HR
D000818:Animals; D000947:Antigens, Helminth / Q000494:pharmacology*; D001985:Bronchial Provocation Tests; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D002452:Cell Count; D053818:Chymases; D004021:Dictyocaulus / Q000276:immunology*; D004804:Eosinophils / Q000378:metabolism; D005260:Female; D007114:Immunization; D007074:Immunoglobulin G / Q000378:metabolism; D007150:Immunohistochemistry; D007958:Leukocyte Count; D008168:Lung / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008407:Mast Cells / Q000378:metabolism; D023421:Models, Animal; D009504:Neutrophils / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D012697:Serine Endopeptidases / Q000378:metabolism; D012756:Sheep; D016212:Transforming Growth Factor beta / Q000378:metabolism
D000947:Antigens, Helminth; D007074:Immunoglobulin G; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D012697:Serine Endopeptidases; D053818:Chymases