The effect of endotoxin and Lactobacillus pretreatment on peritoneal macrophage behavior in acute liver injury in rat

The effect of endotoxin and Lactobacillus R2LC pretreatment in acute liver injury, induced by D-galactosamine was studied. Administration of D-galactosamine resulted in much higher luminescent activity than the control (49.24 mV vs 19.75 mV), while there was no change detected on the metabolic response to phorbol-12-myristate-13-acetate (PMA) stimulation in the calorimeter. Pretreatment of animals with intraperitoneal administration of heat-killed Lactobacillus resulted in higher oxygen free radical production (105.46 mV) and a much higher metabolic response to PMA in microcalorimeter (24.63 pW per cell vs 13.03 in the control). On the other hand pretreatment with endotoxin resulted in higher luminometric response to PMA compared to liver injury group (65.87 mV), and no response in the microcalorimeter at all. Phagocytic activity was decreased from 86 to 59% after administration of D-galactosamine, and was not significantly influenced by any of the pretreatment modalities. This experiment showed that pretreatment with Lactobacillus resulted in increased macrophage metabolic activity, while endotoxin pretreatment rendered the macrophages unresponsive to subsequent stimulation. These findings may explain why pretreatment with endotoxin is beneficial in acute liver injury induced by D-galactosamine, but not with gram-positive bacteria including Lactobacillus.