S layer protein A of Lactobacillus acidophilus NCFM regulates immature dendritic cell and T cell functions
S layer protein A of Lactobacillus acidophilus NCFM regulates immature dendritic cell and T cell functions
复制标题
DOI：
10.1073/pnas.0810305105
复制
发表时间：
2008-12-09
影响因子：
11.1
通讯作者：
van Kooyk, Yvette
中科院分区：
文献类型：
--
作者：
Konstantinov, Sergey R.;Smidt, Hauke;van Kooyk, Yvette
树突状细胞（Dendritic cells，DC）是一种抗原提呈细胞，在黏膜免疫耐受中起重要作用。他们经常遇到有益的肠道细菌，但这些细胞接触的性质和细菌引起的免疫反应尚未完全阐明。在这里，我们研究了嗜酸乳杆菌NCFM及其细胞表面化合物与DC的相互作用。L.嗜酸乳杆菌NCFM附着于DC并诱导浓度依赖性IL-10和低IL-12p70的产生。我们进一步证明了该细菌与DC特异性受体DC特异性ICAM-3-抓取非整合素（DC-SIGN）结合。为了鉴定存在于细菌上的DC-SIGN配体，我们利用产生的L.嗜酸乳杆菌NCFM突变体。L.缺乏表面（S）层A蛋白（SlpA）的嗜酸乳杆菌NCFM与DC-SIGN的结合显著降低。该突变体引起染色体倒位，导致第二S层蛋白SlpB的显性表达。在SlpB优势菌株中，该细菌与DC的相互作用的性质发生了显著变化。与亲本NCFM菌株相比，与SlpB-显性菌株相互作用的DC产生更高浓度的促炎细胞因子，如IL-12 p70、TNF α和IL-1 β。与SlpA敲除突变体不同，用L.嗜酸乳杆菌NCFM刺激的DC产生更多的IL-4。SlpA-DC-SIGN相互作用进一步证实为纯化的SlpA蛋白直接连接至DC-SIGN。因此，L.嗜酸乳杆菌NCFM是第一个被鉴定的益生菌DC-SIGN配体，其在功能上参与DC和T细胞功能的调节。
Dendritic cells (DCs) are antigen-presenting cells that play an essential role in mucosal tolerance. They regularly encounter beneficial intestinal bacteria, but the nature of these cellular contacts and the immune responses elicited by the bacteria are not entirely elucidated. Here, we examined the interactions of Lactobacillus acidophilus NCFM and its cell surface compounds with DCs. L. acidophilus NCFM attached to DCs and induced a concentration-dependent production of IL-10, and low IL-12p70. We further demonstrated that the bacterium binds to DC-specific ICAM-3-grabbing nonintegrin (DC-SIGN), a DC-specific receptor. To identify the DC-SIGN ligand present on the bacterium, we took advantage of a generated array of L. acidophilus NCFM mutants. A knockout mutant of L. acidophilus NCFM lacking the surface (S) layer A protein (SlpA) was significantly reduced in binding to DC-SIGN. This mutant incurred a chromosomal inversion leading to dominant expression of a second S layer protein, SlpB. In the SlpB-dominant strain, the nature of the interaction of this bacterium with DCs changed dramatically. Higher concentrations of proinflammatory cytokines such as IL-12p70, TNF alpha, and IL-1 beta were produced by DCs interacting with the SlpB-dominant strain compared with the parent NCFM strain. Unlike the SlpA-knockout mutant, T cells primed with L. acidophilus NCFM stimulated DCs produced more IL-4. The SlpA-DC-SIGN interaction was further confirmed as purified SlpA protein ligated directly to the DC-SIGN. In conclusion, the major S layer protein, SlpA, of L. acidophilus NCFM is the first probiotic bacterial DC-SIGN ligand identified that is functionally involved in the modulation of DCs and T cells functions.