| Summary: | 碩士 === 臺北醫學大學 === 醫學科學研究所 === 98 === Toxocara canis is one of the most commonly reported zoonotic helminth infections in the world. Humans can get toxocariasis by ingesting infective embryonated eggs. In current studies of T. canis infections using the murine model, researchers found that T. canis larvae could live in paratentic host such as mice for a long time. However, there’s no evidence to prove that T. canis larvae can evade the killing reaction controlled by host immunity.
Here, we intended to investigate whether human visceral larva migrans pathogen Toxocara canis may trigger apoptosis in inflammatory cells by releasing excretory-secretory (TcES) antigens that benefit larval evasion of immunological attacks, or whether there exists anti-apoptosis mechanisms in inflammatory cells that lead to chronic inflammation.
We use different concentrations (5、15、25、50、100 μg/ml) of TcES or different amount (150 or 300) of T. canis larvae co-cultured with human Jurkat T lymphocytes cell line (clone E6-1) for 12~72 hrs to explore the underline mechanism of larval evasion in host as assessed by flow cytometry and western blotting approaches. Our results indicated that 25 μg/ml TcES posed the strongest apoptotic effects on human Jurkat T lymphocyte for 24 hrs co-culture; whereas the expression of anti-apoptotic proteins of Bcl-2 and Bcl-xL increased with the increased concentration of TcES and co-culture time as well. In addition, 300 T. canis larvae are able to trigger apparently apoptosis of human Jurkat T lymphocyte for co-culture of 72 hrs due to enhanced caspase-8 expression.
Based on above findings, we postulate that T. canis larvae may evade immunological attacks by releasing excretory-secretory materials or larvae per se through triggering human Jurkat T lymphocyte apoptosis.
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