Impact of Heat-Killed Lactobacillus casei Strain IMAU60214 on the Immune Function of Macrophages in Malnourished Children

Abstract

Malnutrition is commonly associated with immunological deregulation, increasing the risk of infectious illness and death. The objective of this work was to determine the in vitro effects of heat-killed <i>Lactobacillus casei</i> IMAU60214 on monocyte-derived macrophages (MDMs) from well-nourished healthy children, well-nourished infected children and malnourished infected children, which was evaluated by an oxygen-dependent microbicidal mechanism assay of luminol-increase chemiluminescence and the secretion of tumor necrosis factor (TNF-α), interleukin (IL-1β), IL-6 and IL-10, as well as phagocytosis using zymosan and as its antibacterial activity against <i>Salmonella typhimurium</i>, <i>Escherichia coli</i> and <i>Staphylococcus aureus</i>. We found that reactive oxygen species (ROS), secretion cytokines (TNFα, IL-1β, IL-6 and IL-10 levels), phagocytosis and bactericidal capacity increased in all groups after pre-treatment with heat-killed <i>L. casei</i> IMAU60214 at a ratio of 500:1 (bacteria:MDM) over 24 h compared with MDM cells without pre-treatment. The results could indicate that heat-killed <i>L. casei</i> IMAU60214 is a potential candidate for regulating the immune function of macrophages.