Immunostimulatory Effect of Heat-Killed Probiotics on RAW264.7 Macrophages

• Published in: Journal of microbiology and biotechnology Vol. 32; no. 5; pp. 638 - 644
• Main Authors: Noh, Hye-Ji, Park, Jung Min, Kwon, Yoo Jin, Kim, Kyunghwan, Park, Sung Yurb, Kim, Insu, Lim, Jong Hyun, Kim, Byoung Kook, Kim, Byung-Yong
• Format: Journal Article
• Language: English
• Published: Korea (South) The Korean Society for Microbiology and Biotechnology 28.05.2022; 한국미생물·생명공학회
• Subjects: Animals; Cytokines; Hot Temperature; Macrophages; Mice; Nitric Oxide; Probiotics - pharmacology; RAW 264.7 Cells; Research article; 생물학; Immunostimulatory effect; macrophages; heat-killed probiotics
• ISSN: 1017-7825; 1738-8872
• DOI: 10.4014/jmb.2201.01015

Probiotics modulate the gut microbiota, which in turn regulate immune responses to maintain balanced immune homeostasis in the host. However, it is unclear how probiotic bacteria regulate immune responses. In this study we investigated the immunomodulatory effects of heat-killed probiotics, including KC3 (LP3), CKDB008 (LP8), and SRK414 (LF4), via phagocytosis, nitric oxide (NO), and pro-inflammatory cytokine production in macrophages. We thus found that heat-killed LP8 could promote the clearance of foreign pathogens by enhancing the phagocytosis of macrophages. Treatment with heat-killed LP8 induced the production of NO and pro-inflammatory cytokines, including TNF-α, IL-6, and IL-1β. In addition, heat-killed LP8 suppressed the production of NO and cytokines in LPS-induced RAW264.7 cells, suggesting that heat-killed LP8 exerts immunomodulatory effects depending on the host condition. In sum, these results indicate that heat-killed LP8 possesses the potential for immune modulation while providing a molecular basis for the development of functional probiotics prepared from inactivated bacterial cells.