Streptococcus salivarius K12 is an oral probiotic known to contribute to protection against oral pathogenic bacteria in humans. Studies of immune responses to S. salivarius K12 have focused on the oral cavity, and systemic immune responses have not yet been reported. The aim of this study was to identify acute systemic immune responses to the commercial product, S. salivarius BLIS K12, in a double-blinded, placebo-controlled human clinical trial. It was hypothesised that consumption of S. salivarius BLIS K12 would induce an anti-inflammatory response and a decrease in pro-inflammatory cytokines. Blood samples were obtained from participants prior to a single dose of S. salivarius BLIS K12 or a placebo and then secondary blood samples were obtained 24 h and 7 days post-consumption. Samples were analysed using multi-parametric flow cytometry, to quantify immune cell frequency changes, and by a LEGENDplex assay of human inflammatory cytokines. Consumption of S. salivarius BLIS K12 was associated with increased levels of IL-8 at 24 h. The frequency of Tregs increased in samples taken 7 days after probiotic consumption, and IL-10 concentrations were higher at 7 days than 24 h after consumption. There was no difference in the frequency and/or activation of CD4⁺ T cells, CD8⁺ T cells, B cells and NK cells. Interestingly, there was an increase in IL-12, 7 days after the consumption of S. salivarius BLIS K12. Collectively, this research demonstrates that ingestion of the probiotic S. salivarius K12 can induce changes in the systemic immune response. The implications of the generation and type of immune response warrant further study to determine potential health benefits.

Streptococcus salivarius K12 是一种口腔益生菌，已知有助于保护人类免受口腔致病菌的侵害。对S. salivarius K12免疫反应的研究主要集中在口腔，尚未报道全身免疫反应。本研究的目的是在一项双盲、安慰剂对照的人体临床试验中确定对商业产品S. salivarius BLIS K12 的急性全身免疫反应。假设食用S. salivarius BLIS K12 会诱导抗炎反应和促炎细胞因子的减少。在单剂唾液链球菌之前从参与者那里获得血液样本服用后 24 小时和 7 天获得 BLIS K12 或安慰剂，然后获得二次血样。使用多参数流式细胞仪分析样本，以量化免疫细胞频率变化，并通过人类炎性细胞因子的 LEGENDplex 测定。消耗S. salivarius BLIS K12 与 24 小时 IL-8 水平升高有关。在益生菌摄入后 7 天采集的样本中 Tregs 的频率增加，并且在 7 天的 IL-10 浓度高于摄入后 24 小时。CD4 ⁺ T 细胞、CD8 ⁺ T 细胞、B 细胞和 NK 细胞的频率和/或激活没有差异。有趣的是，食用S. salivarius 7 天后，IL-12 有所增加极乐 K12。总的来说，这项研究表明，摄入益生菌S. salivarius K12 可以诱导全身免疫反应的变化。免疫反应的产生和类型的影响值得进一步研究以确定潜在的健康益处。