DataSheet_5_Macrophage-infectivity potentiator of Trypanosoma cruzi (TcMIP) is a new pro-type 1 immuno-stimulating protein for neonatal human cells and vaccines in mice.pdf

This work identifies the protein “macrophage infectivity potentiator” of Trypanosoma cruzi trypomastigotes, as supporting a new property, namely a pro-type 1 immunostimulatory activity on neonatal cells. In its recombinant form (rTcMIP), this protein triggers the secretion of the chemokines CCL2 and CCL3 by human umbilical cord blood cells from healthy newborns, after 24h in vitro culture. Further stimulation for 72h results in secretion of IFN-γ, provided cultures are supplemented with IL-2 and IL-18. rTcMIP activity is totally abolished by protease treatment and is not associated with its peptidyl-prolyl cis-trans isomerase enzymatic activity. The ability of rTcMIP to act as adjuvant was studied in vivo in neonatal mouse immunization models, using acellular diphtheria-tetanus-pertussis-vaccine (DTPa) or ovalbumin, and compared to the classical alum adjuvant. As compared to the latter, rTcMIP increases the IgG antibody response towards several antigens meanwhile skewing antibody production towards the Th-1 dependent IgG2a isotype. The amplitude of the rTcMIP adjuvant effect varied depending on the antigen and the co-presence of alum. rTcMIP did by contrast not increase the IgE response to OVA combined with alum. The discovery of the rTcMIP immunostimulatory effect on neonatal cells opens new possibilities for potential use as pro-type 1 adjuvant for neonatal vaccines. This, in turn, may facilitate the development of more efficient vaccines that can be given at birth, reducing infection associated morbidity and mortality which are the highest in the first weeks after birth.

本研究鉴定了克氏锥虫（Trypanosoma cruzi）三角锥虫的“巨噬细胞感染性增强因子”蛋白，并揭示了其一种新型特性，即对新生儿细胞具有促进型1免疫刺激活性。在重组形式（rTcMIP）中，该蛋白能够通过24小时体外培养后的人脐带血细胞分泌趋化因子CCL2和CCL3。进一步刺激72小时，在添加IL-2和IL-18的培养液中，可诱导干扰素-γ（IFN-γ）的分泌。rTcMIP的活性被蛋白酶处理完全消除，且与其肽基脯氨酸顺反异构酶的酶活性无关。rTcMIP作为佐剂的能力在新生儿小鼠免疫模型中进行了体内研究，使用了无细胞百白破疫苗（DTPa）或卵蛋白，并与传统的铝佐剂进行了比较。与后者相比，rTcMIP增加了针对多种抗原的IgG抗体反应，同时使抗体产生偏向Th-1依赖的IgG2a同种型。rTcMIP佐剂效应的幅度根据抗原和铝的共存情况而变化。然而，rTcMIP并未增加与铝结合的卵蛋白的IgE反应。rTcMIP在新生儿细胞上的免疫刺激效应的发现，为作为促进型1佐剂在新生儿疫苗中的潜在应用开辟了新的可能性。这反过来又可能促进更有效疫苗的开发，这些疫苗可以在出生时给予，以降低出生后第一周内感染相关的发病率和死亡率。