乳酸菌Lactococcus lactis subsp. lactis JCM5805 含有飲料の摂取による抗ウイルス免疫応答および体調の維持に対する効果―プラセボ対照ランダム化二重盲検並行群間比較試験―

Objectives The objective of this study was to examine the effect of the beverage containing heat-killed Lactococcus lactis subsp. lactis JCM5805（Lc. lactis JCM5805）on anti-viral immune responses and maintenance of physical conditions. Methods A randomized, double-blind, placebo-controlled, parallel-group trial was conducted. One hundred subjects were divided into 2 groups and took 1 bottle （500 mL）daily of the beverage that did╱did not contain approximately 100 billion heat killed Lc. lactis JCM5805 for 8 weeks. To evaluate anti-viral immune responses, we measured CD86 and HLA-DR expression levels on plasmacytoid dendritic cells（pDC）, which are responsible for regulation of anti-viral immune responses in peripheral blood mononuclear cells（PBMC）and gene expression levels of anti-viral factors in PBMC stimulated by inactivated human influenza A virus（H1N1）. Also, cumulative incidence days of cold︱like symptoms were analyzed to evaluate effects on maintenance of physical conditions. Results After 8 weeks intake period, CD86 and HLA-DR expression levels on pDC in the Lc. lactis JCM5805 group were significantly higher compared to the placebo group. Additionally, gene expression level of ISG15, an anti-viral factor known to be induced by typeⅠ interferon, was significantly higher compared to the placebo group after the intake period. Furthermore, cumulative incidence days of cold-like symptoms during the intake period were significantly lower in the Lc. lactis JCM5805 group compared to the placebo group. Conclusions The beverage containing approximately 100 billion heat-killed Lc. lactis JCM5805 is suggested to be beneficial in enhancing anti-viral immune responses and maintaining physical conditions.