Haseeb M A, Agrawal Raag, Fried Bernard
Acta Parasitol. 2017 Mar 1;62(1):164-170. doi: 10.1515/ap-2017-0019.
Recombinant human TNFα (rhTNFα) has previously been shown to reduce fecundity in Schistosoma mansoni adult females maintained in vitro without males, and adversely affect the uptake of [14C]-tyrosine, an amino acid required for schistosome vitellogenesis. Here we report on the effect of rhTNFα on [14C]-methionine uptake in both separated and paired females, and the effect of three different preparations of rTNFα on schistosome oviposition in vitro. In the absence of rhTNFa, separated females incorporated only 30% of the [14C]-methionine incorporated by paired females in a dose and time-dependent manner, suggesting low metabolic activity of females in the absence of males. Separated females and worm-pairs were treated with increasing doses of rhTNFα for 2 or 4 hr and then incubated in RPMI 1640 containing 10% fetal calf serum (FCS) and 5 µCi ml-1[14C]-methionine for 1 hr. Separated females treated with rhTNFa for 4 hr incorporated less methionine than those treated for 2 hr. In contrast, paired females treated with rhTNFa incorporated significantly smaller amounts of [14C]-methionine in a TNFa dose-dependent but time-independent manner [2 hr (P = 0.001) or 4 hr (P = 0.027) One-Way ANOVA]. Worm-pairs maintained in RPMI 1640 containing 10% FCS and 100 ng ml-1 of any of the three rTNFa preparations laid significantly fewer eggs than the worms cultured without rTNFα(P = 0.001; Kruskal-Wallis Test). We also observed that among rTNFα-treated worm-pairs, females were sluggish and tended to separate from their male partners. These observations suggest that TNFa inhibits [14C]-methionine uptake and reduces fecundity in females paired with males. Since paired females incorporate substantially greater amounts of [14C]-methionine, the role of males in stimulating metabolic activity in females is affirmed. Reduced amino acid uptake, and possibly other nutrients, may contribute to the diminished fecundity observed in TNFa-treated females.
重组人肿瘤坏死因子α（rhTNFα）此前已被证明可降低体外培养的无雄曼氏血吸虫成年雌虫的繁殖力，并对血吸虫卵黄生成所需的氨基酸[14C]-酪氨酸的摄取产生不利影响。在此，我们报告rhTNFα对分离雌虫和配对雌虫摄取[14C]-蛋氨酸的影响，以及三种不同制剂的重组肿瘤坏死因子α（rTNFα）对血吸虫体外产卵的影响。在无rhTNFα的情况下，分离的雌虫摄取的[14C]-蛋氨酸仅为配对雌虫的30%，且呈剂量和时间依赖性，这表明无雄虫时雌虫的代谢活性较低。将分离的雌虫和虫对用递增剂量的rhTNFα处理2或4小时，然后在含有10%胎牛血清（FCS）和5μCi/ml[14C]-蛋氨酸的RPMI 1640中孵育1小时。用rhTNFα处理4小时的分离雌虫摄取的蛋氨酸比处理2小时的少。相比之下，用rhTNFα处理的配对雌虫摄取的[14C]-蛋氨酸量显著减少，呈TNFα剂量依赖性但与时间无关[2小时（P = 0.001）或4小时（单向方差分析，P = 0.027）]。在含有10%FCS和100 ng/ml三种rTNFα制剂中任何一种的RPMI 1640中培养的虫对产卵量显著少于未用rTNFα培养的虫（P = 0.001；Kruskal-Wallis检验）。我们还观察到，在rTNFα处理的虫对中，雌虫行动迟缓，且往往与雄虫分开。这些观察结果表明，TNFα抑制[14C]-蛋氨酸摄取，并降低与雄虫配对的雌虫的繁殖力。由于配对雌虫摄取的[14C]-蛋氨酸量显著更多，雄虫在刺激雌虫代谢活性中的作用得到证实。氨基酸摄取减少以及可能的其他营养物质摄取减少，可能是导致TNFα处理的雌虫繁殖力下降的原因。
