Escudero-Lourdes Claudia, Martínez Fernando Diaz-Barriga, Medina de la Garza Carlos Eduardo, Calvillo Roberto Quezada
Laboratorio de Inmunología y Biología Celular y Molecular, CIEP/FCQ/Universidad Autónoma de San Luis Potosi, Mexico.
Proc West Pharmacol Soc. 2005;48:92-9.
Chronic exposure to toxicants alters immune function that can affect the ability of the host to mount a response to infection. Giardiasis is a gastrointestinal disease in which subtle alteration in immunity of the host can transform the normal acute infection into a chronic one. In this work we used a murine giardiasis model to evaluate the effect of chronic oral intoxication with sodium arsenite on the characteristics of giardiasis. BALB/c mice were intoxicated during 45 days with water containing 50, 125 or 250 microg/mL sodium arsenite. Each group was then inoculated with G. muris cysts. Cysts excreted in the feces were isolated and quantified. The toxic effect of arsenic on intestinal trophozoites was evaluated using G. lamblia trophozoites cultured in vitro with different arsenic concentrations, corresponding to equivalent concentrations of arsenic found in the gut lumen of intoxicated mice. Mice intoxicated with 125 and 250 microg/mL of sodium arsenite and infected with G. muris cysts displayed a shorter period of cysts excretion and were resistant to secondary infection with the parasite. In vitro studies showed that G. lamblia trophozoites were able to grow in presence of high sodium arsenite concentrations, suggesting the absence of a direct toxic effect on the parasite in the gut. Since a longer period of Giardia cysts excretion is associated with suppression of the immune system, the earlier clearance of primary G. muris infection in intoxicated mice suggests the induction of an immune modification that leads to an improved ability of mice to overcome the infection.
长期接触毒物会改变免疫功能，进而影响宿主对感染作出反应的能力。贾第虫病是一种胃肠道疾病，宿主免疫力的细微改变可使正常的急性感染转变为慢性感染。在这项研究中，我们使用小鼠贾第虫病模型来评估亚砷酸钠慢性口服中毒对贾第虫病特征的影响。将BALB/c小鼠用含有50、125或250微克/毫升亚砷酸钠的水进行45天的中毒处理。然后每组接种鼠贾第虫囊肿。分离并定量粪便中排出的囊肿。使用在体外不同砷浓度下培养的蓝氏贾第鞭毛虫滋养体评估砷对肠道滋养体的毒性作用，这些浓度对应于中毒小鼠肠腔中发现的等效砷浓度。用125和250微克/毫升亚砷酸钠中毒并感染鼠贾第虫囊肿的小鼠囊肿排出期较短，且对该寄生虫的二次感染具有抗性。体外研究表明，蓝氏贾第鞭毛虫滋养体能够在高浓度亚砷酸钠存在的情况下生长，这表明对肠道中的寄生虫没有直接毒性作用。由于贾第虫囊肿排出时间延长与免疫系统抑制有关，中毒小鼠中初次鼠贾第虫感染的较早清除表明诱导了免疫调节，从而导致小鼠克服感染的能力提高。
