Sf. Ali et al., Eicosanoid production by adult Fasciola hepatica and plasma eicosanoid patterns during fasciolosis in sheep, INT J PARAS, 29(5), 1999, pp. 743-748
Fasciola hepatica infection in sheep is known to cause anaemia, fever and e
levated levels of liver enzymes. It was hypothesised that eicosanoids play
a role in these pathophysiological changes, so the pattern of plasma eicosa
noids during the course of acute and chronic fasciolosis was studied in she
ep infected with a single dose of 800 F. hepatica metacercariae. Blood plas
ma was collected weekly until week 17 p.i. from infected sheep, and from un
infected controls. Adult F. hepatica were then recovered from bile ducts an
d incubated for production of ES products. Eicosanoids were determined by e
nzyme immune-assay in blood plasma, fluke homogenates and ES products after
chromatographic purification of the samples. Fever and anaemia a ere seen
from 3 to 12 weeks p.i, and from 8 to 17 weeks p.i., respectively. Onset of
fever was accompanied by elevated liver enzyme activities (aspartate amino
transferase and gamma glutamyl transferase) in the plasma. In general, the
plasma levels of prostaglandin E2 (PGE2), prostaglandin I2 (PGI2) and leuk
otriene B4 (LTB4) were reduced during the acute and chronic stages of the i
nfection, whereas thromboxane B2 (TXB2) was reduced only at 8 weeks p.i. Th
e TXB2/PGI2 ratio was increased in favour of TSB2 at 3 and 11 weeks p.i. Ad
ditionally, TXB2, PGI2, PGE2 and LTB4 were detected both in ES products and
in homogenates of F. hepatica. It was concluded that eicosanoid depletion
in the plasma is caused by parasite-induced liver damage. The changes in ei
cosanoid levels are highly correlated to the clinical signs of the disease.
Changes in the pattern of host plasma eicosanoids during fasciolosis, as w
ell as parasite-derived eicosanoids, may reflect or contribute tn the patho
logy of the disease. (C) 1999 Australian Society for Parasitology. Publishe
d by Elsevier Science Ltd. All rights reserved.