Immunostimulatory activity of Lactococcus lactis LM1185 isolated from Hydrangea macrophylla

The lactic acid bacteria, Lactococcus lactis subsp. lactis LM1185 was isolated from Hydrangea macrophylla. Strain LM1185 showed 50.5% of acid tolerance at pH 2.5 for 2 h and 30.4% of 0.3% (w/v) bile salt tolerance for 24 h. The antioxidant activity of this strain was measured at 99.4% of 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity. When RAW 264.7 macrophage cells were treated with strain LM1185, there was no observed cytotoxicity. This strain showed high nitric oxide production and mRNA expression levels of cytokines such as tumor necrosis factor-α and inducible nitric oxide synthase (iNOS). The nuclear factor-kB signaling pathway was activated by this strain resulting in the production of iNOS and cyclooxygenase-2 determined by western blotting. The present results indicated that L. lactis subsp. lactis LM1185 could be used as potential probiotics and may play a crucial role in the immunostimulatory effect on macrophages.