The human milk oligosaccharide 3’sialyllactose (3’SL) has previously been shown to activate murine dendritic cells (DC) in a TLR4-mediated manner ex vivo. In this study we aimed to investigate whether 3’SL has similar immunomodulatory properties on human DC. 3’SL was shown to induce NF-κB activation via human TLR4. However, LPS was detected in the commercially obtained 3’SL from different suppliers. After the removal of LPS from 3’SL, we studied its ability to modify DC differentiation in vitro. In contrast to LPS and 3’SL, LPS-free 3’SL did not induce functional and phenotypical changes on immature DC (iDC). iDC that were differentiated in the presence of LPS or 3’SL showed a semi-mature phenotype (i.e., fewer CD83+CD86+ DC), produced IL-10 and abrogated IL-12p70 and TNF levels upon stimulation with several TLR ligands. Differentiation into these tolerogenic DC was completely abrogated by LPS removal from 3’SL. In contrast to previous reports in mice, we found that LPS-free 3’SL does not activate NF-κB via human TLR4. In conclusion, removing LPS from (oligo)saccharide preparations is necessary to study their potential immunomodulatory function.

中文翻译：

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LPS污染可解释3'-唾液乳糖通过TLR4诱导人耐受树突状细胞

先前已显示人乳寡糖3'唾液乳糖（3'SL）以TLR4介导的方式离体激活鼠树突状细胞（DC）。在这项研究中，我们旨在研究3'SL是否对人DC具有类似的免疫调节特性。显示3'SL经由人TLR4诱导NF-κB活化。但是，在商业上获得的来自不同供应商的3'SL中检测到LPS。从3'SL去除LPS后，我们研究了其在体外修饰DC分化的​​能力。与LPS和3'SL相比，不含LPS的3'SL不会在未成熟DC（iDC）上诱导功能和表型改变。在LPS或3'SL存在下分化的iDC表现出半成熟的表型（即，较少的CD83 + CD86 + DC），产生IL-10并在用几种TLR配体刺激后废除了IL-12p70和TNF水平。通过从3'SL去除LPS，完全消除了这些致耐受DC的分化。与以前的小鼠报道相反，我们发现不含LPS的3'SL不会通过人TLR4激活NF-κB。总之，从（寡糖）制剂中除去LPS对于研究其潜在的免疫调节功能是必要的。