Heat-Killed Lactobacillus brevis Enhances Phagocytic Activity and Generates Immune-Stimulatory Effects through Activating the TAK1 Pathway

• Published in: Journal of microbiology and biotechnology Vol. 30; no. 9; pp. 1395 - 1403
• Main Authors: Jeong, Minju, Kim, Jae Hwan, Lee, Ji Su, Kang, Shin Dal, Shim, Sangmin, Jung, Moon Young, Yang, Hee, Byun, Sanguine, Lee, Ki Won
• Format: Journal Article
• Language: English
• Published: Korea (South) The Korean Society for Microbiology and Biotechnology 28.09.2020; 한국미생물·생명공학회
• Subjects: Animals; Cells, Cultured; Hot Temperature; Immunomodulation - drug effects; Interleukin-6 - metabolism; Levilactobacillus brevis - immunology; Macrophages - drug effects; Macrophages - immunology; MAP Kinase Kinase Kinases - metabolism; Mice; Nitric Oxide - metabolism; Phagocytosis - drug effects; Probiotics - administration & dosage; Probiotics - pharmacology; RAW 264.7 Cells; Research article; Signal Transduction - drug effects; Spleen - drug effects; Spleen - immunology; Tumor Necrosis Factor-alpha - metabolism; 생물학; phagocytosis; immune stimulation; TAK1; Lactobacillus brevis; probiotics
• ISSN: 1017-7825; 1738-8872
• DOI: 10.4014/jmb.2002.02004

There is an increasing interest in using inactivated probiotics to modulate the host immune system and protect against pathogens. As the immunomodulatory function of heat-killed KCTC 12777BP (LBB) and its mechanism is unclear, we investigated the effect of LBB on immune response based on the hypothesis that LBB might exert stimulatory effects on immunity. In the current study, we demonstrate that administration of LBB can exert immune-stimulatory effects and promote clearance of foreign matters through enhancing phagocytosis. Treatment with LBB induced the production of TNF-α, IL-6, and nitric oxide in macrophages. Importantly, LBB directly increased the phagocytic activity of macrophages against bacterial particles. LBB was able to promote the production of TNF-α in bone marrow-derived macrophages and splenocytes and also increase the proliferation rate of splenocytes, suggesting that the immune-stimulating activity of LBB can be observed in primary immune cells. Investigation into the molecular mechanism responsible revealed that LBB upregulates TAK1 activity and its downstream ERK, p38, and JNK signaling pathways. To further confirm the immunomodulatory capability of LBB in vivo, we orally administered LBB to mice and assessed the effect on primary splenocytes. Splenocytes isolated from LBB-treated mice exhibited higher TNF-α expression and proliferative capacity. These results show that heat-killed , a wildly consumed probiotic, may provide protection against pathogens through enhancing host immunity.