Potent effects of, and mechanisms for, modification of crosstalk between macrophages and adipocytes by lactobacilli.

The murine macrophage-like cell line J774.1 was treated with heat-killed cells of Lactobacillus GG (LGG) and L. gasseri TMC0356 (TMC 0356). Interleukin (IL)-6, IL-12, and tumor necrosis factor-α were profiled from the J774.1 cells using enzyme-linked immunosorbent assay methods. The conditioned medium from cultured J774.1 cells was transferred to the preadipocyte cell line 3T3-L1 (which is a mouse embryonic fibroblast-adipose-like cell line). Growth and differentiation of 3T3-L1 cells were monitored by analyzing lipid accumulation and expression of peroxisome proliferator-activated receptor (PPAR)-γ mRNA. The medium conditioned by 3T3-L1 cells was added to J774.1 cells and the cytokines in the supernatant analyzed. Compared with that of cells exposed to a PBS-conditioned medium, lipid accumulation in 3T3-L1 cells was significantly suppressed in a dose-dependent manner by each medium that had been conditioned with LGG and TMC0356. PPAR-γ mRNA expression in 3T3-L1 cells was also significantly downregulated (P < 0.01, P < 0.05, respectively). The conditioned medium of 3T3-L1 adipose phenotype significantly stimulated production of IL-6 and IL-12 in J774.1 cells treated with LGG and TMC0356. These results suggest that lactobacilli may suppress differentiation of preadipocytes through macrophage activation and alter the immune responses of macrophages to adipose cells.