Table_1_Impaired macrophage and memory T-cell responses to Bacillus Calmette-Guerin nonpolar lipid extract.docx

IntroductionThe attenuation of BCG has led to the loss of not only immunogenic proteins but also lipid antigens.
MethodsThus, we compared the macrophage and T-cell responses to nonpolar lipid extracts harvested from BCG and Mycobacterium tuberculosis (Mtb) to better understand the role of BCG lipids in the already known diminished responses of the vaccine strain.
ResultsRelative to Mtb, nonpolar lipid extract from BCG presented a reduced capacity to trigger the expression of the genes encoding TNF, IL-1b, IL-6 and IL-10 in RAW 264.7 macrophages. Immunophenotyping of PBMCs isolated from healthy individuals revealed that lipids from both BCG and Mtb were able to induce an increased frequency of CD4+ and CD8+ T cells, but only the lipid extract from Mtb enhanced the frequency of CD4-CD8-double-negative, γσ+, CD4+HLA-DR+, and γσ+HLA-DR+ T cells relative to the nonstimulated control. Interestingly, only the Mtb lipid extract was able to increase the frequency of CD4+ memory (CD45RO+) T cells, whereas the BCG lipid extract induced a diminished frequency of CD4+ central memory (CD45RO+CCR7-) T cells after 48 h of culture compared to Mtb.
DiscussionThese findings show that the nonpolar lipids of the BCG bacilli presented diminished ability to trigger both proinflammatory and memory responses and suggest a potential use of Mtb lipids as adjuvants to increase the BCG vaccine efficacy.

引言：卡介苗（BCG）的减毒过程不仅造成了免疫原性蛋白的丢失，同时也导致了脂质抗原的缺失。
方法：为此，我们比较了巨噬细胞与T细胞对卡介苗（BCG）及结核分枝杆菌（Mycobacterium tuberculosis, Mtb）提取的非极性脂质提取物的应答反应，以期更深入阐明卡介苗脂质在该疫苗株已被证实的应答减弱现象中所发挥的作用。
结果：相较于结核分枝杆菌（Mtb），卡介苗的非极性脂质提取物在RAW 264.7巨噬细胞中诱导肿瘤坏死因子（TNF）、白细胞介素-1β（IL-1β）、IL-6及IL-10编码基因表达的能力有所减弱。对健康个体分离得到的外周血单个核细胞（PBMCs）进行免疫分型的结果显示，卡介苗与结核分枝杆菌的脂质提取物均可诱导CD4+及CD8+ T细胞的频率升高；但相较于未刺激对照组，仅结核分枝杆菌的脂质提取物可提升CD4-CD8-双阴性、γδ+、CD4+HLA-DR+及γδ+HLA-DR+ T细胞的频率。值得注意的是，仅结核分枝杆菌的脂质提取物能够升高CD4+记忆性（CD45RO+）T细胞的频率；而与结核分枝杆菌脂质提取物相比，卡介苗脂质提取物在体外培养48小时后会降低CD4+中央记忆性（CD45RO+CCR7-）T细胞的频率。
讨论：本研究结果表明，卡介苗杆菌的非极性脂质在触发促炎反应与记忆性应答两方面的能力均有所减弱，这提示结核分枝杆菌脂质有望作为佐剂以提升卡介苗的疫苗保护效力。