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Local immune responses in colon from cattle infected with Fasciola hepatica
D F McCole1, M L Doherty, P R Torgerson
1Department of Pharmacology, University College Dublin, Belfield, Ireland.
Insights
Fasciola hepatica infection in cattle causes rapid electrical current changes in the colon. Bacterial components suggest immune cells contribute to this response, with increased eosinophils observed.
Area of Science:
- Veterinary immunology
- Gastrointestinal physiology
- Parasitology
Background:
- Fasciola hepatica is a significant liver fluke parasite affecting livestock.
- Gastrointestinal responses to parasitic infections are complex and not fully understood.
- Charolais heifers are a relevant model for studying bovine parasitic diseases.
Purpose of the Study:
- To investigate the colonic mucosal response to Fasciola hepatica infection in cattle.
- To characterize the electrical changes in the colon following parasitic antigen challenge.
- To explore the role of immune cells in the colonic response to infection.
Main Methods:
- Isolation of colonic mucosa from infected and control Charolais heifers.
- Voltage clamping of tissue in Ussing chambers to measure electrical currents.
- Challenge with Fasciola hepatica antigen and bacterial components (N-formyl-methionyl-leucyl-phenylalanine).
- Assessment of chloride secretion using bumetanide and eosinophil counts.
Main Results:
- Infected colonic tissue exhibited a rapid inward short-circuit current upon antigen challenge.
- Chloride secretion contributed significantly to the observed current, attenuated by bumetanide.
- Bacterial components mimicked antigen response and induced desensitization, suggesting immunocyte involvement.
- Fasciola hepatica infection led to increased eosinophil numbers in the colonic mucosa.
Conclusions:
- Fasciola hepatica infection induces significant electrical changes in the bovine colon.
- The response involves chloride secretion and is likely mediated by immunocytes.
- Increased eosinophils indicate an inflammatory response within the infected colonic tissue.
Abstract:
Colonic mucosae isolated from eight Charolais heifers 14 weeks after oral infection with Fasciola hepatica metacercariae were voltage clamped in Ussing chambers. Antigen challenge provoked a rapid-onset, inward short circuit current in infected but not in control tissue preparations. Chloride secretion accounted for part of the response as the loop diuretic bumetanide attenuated the response to antigen by 89%. The bacterial cell wall component n-formyl-methionyl-leucyl-phenylalanine induced a similar response to antigen and partly desensitised tissues to subsequent antigen challenge, consistent with the involvement of immunocytes in the response to antigen. Infection induced an elevation in the number of tissue eosinophils compared with control colon.