Probiotic Lactobacillus Strains Stimulate the Inflammatory Response and Activate Human Macrophages

Figure 3

Effect of heat-killed lactobacillus on phagocytosis in human macrophages. Cells (1 × 10⁴) were treated with heat-killed strains of lactobacillus at a MOI of 1 : 500 for 1 h before zymosan particles, S. aureus, S. typhimurium, or E. coli (each at a MOI of 1 : 10) were added. Phagocytosis was allowed to proceed for 1 h at 37°C in an atmosphere containing 5% C0₂, before phagocytosis was terminated. The cells were then fixed, and the nuclei were stained with DAPI. Macrophages, untreated (a) and treated (b) cells. Fluorescence photomicroscopy in macrophages treated with different stimuli was performed using an epifluorescence Zeiss Axioskop2 microscope equipped with a Zeiss Axiocam (Zeiss AG, Oberkochen, DE). This figure shows the representative results with the strain (L. casei IMAU60214). (c) Heat-killed lactobacillus enhanced the phagocytic index of human macrophages. The ingestion of cells was determined in macrophages that were incubated in medium alone or preincubated with lactobacillus strains. The following formula was used: the percentage of cells undergoing phagocytosis × the number of particles per cells. The cells were incubated with zymosan, S. typhimurium, S. aureus, and E. coli, as indicated. Asterisks indicate a significant difference between conditions ().

(a)

(b)

(c)