Objective—To evaluate the cytopathic effects of
Tritrichomonas foetus and a purified cysteine protease
(ie, CP30) of T foetus on cultured bovine uterine
epithelial cells (BUECs) in vitro.
Sample Population—10 reproductive tracts were
obtained from late-term bovine fetuses at a commercial
Procedure—An in vitro culture system of BUECs was
developed to study the cytopathic effects of T foetus
and purified CP30 of T foetus on host cells.
Cytotoxicity of T foetus or CP30 on exposed BUECs
was determined. Fluorescence microscopy and flow
cytometry analyses were used to detect apoptosis. A
fluorometric assay was used to detect BUEC caspase
3 activation. The CP inhibitor E-64 and a caspase
inhibitor were used to inhibit apoptosis.
Results—Cytopathic effects were observed in
BUECs treated with parasites or CP30 and were concentration
and time dependent. The BUECs underwent
apoptosis in the presence of parasites or CP30.
The specific CP inhibitor E-64 abolished the induction
of apoptosis in BUECs by CP30. The caspase inhibitor
reduced the amount of apoptosis in BUECs.
Conclusions and Clinical Relevance—T foetus and
its CP30 induce apoptosis in cultured BUECs in vitro.
Induction of apoptosis by CP30 is correlated with protease
activity. Endometrial cell death as a result of a
T foetus infection is likely to be more important in
mediating infertility than a direct effect on the conceptus.
Provoking an apoptotic reaction in the host may
mitigate an inflammatory reaction or immune
response and therefore favor survival of the parasite in
a chronic infection. (Am J Vet Res 2005;66:1181–1186)