MOLECULAR BIOLOGY OF HUMAN PATHOGENS ASSOCIATED WITH FOOD
Location: Produce Safety and Microbiology Research
Title: Hericium erinaceus mushroom extracts protect infected mice against Salmonella typhimurium induced liver damage and mortality by activation of innate immune cells
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 14, 2012
Publication Date: May 24, 2012
Citation: Kim, S., Moon, E., Nam, S., Friedman, M. 2012. Hericium erinaceus mushroom extracts protect infected mice against Salmonella typhimurium induced liver damage and mortality by activation of innate immune cells. Journal of Agricultural and Food Chemistry. 60:5590-5596. doi: 10.1021/jf300897w.
Interpretive Summary: In a collaborative study with Korean scientists,we used a series of in vitro and in vivo bacterial and other bioassays to demonstrate the protective effect of extracts of the edible mushroom Hericium erinaceus against adverse effects of the foodborne pathogen Salmonella Typhimurium in murine macrophage cells and against liver necrosis and mortality in infected mice. Liver morphology and life expectancy were improved in Salmonella-infected mice by peritoneal administration of these extracts. The beneficial effects were accompanied by changes in several biomarkers in cultured murine macrophage cells associated with the immune system. Because the bioactive extracts did not inactivate the Salmonella in laboratory media in vitro but did protect mice administered a lethal dose of the bacteria against liver damage and mortality, we may assume that the protective effect is associated with a stimulation of the immune system. These beneficial results suggest that the bioactive mushroom extracts merit further study for their potential to improve microbial food safety and for their application in veterinary and human infections. This study complements our recently published related study on the inactivation of Salmonella in mice by a newly developed rice hull smoke extract (Journal of Food Science, Volume 77,pages M80-M85, 2012).
The present study investigated the antibacterial effect of four extracts from the fruitbody of the edible medicinal mushroom Hericium erinaceus (Hot water extract, HWE; Microwave/50% ethanol extract, MWE; Acid extract, ACE; and Alkaline extract, AKE) against murine salmonellosis. The extracts had no effect on Salmonella enterica Typhimurium growth in culture. The lifespan of mice infected with a lethal dose of S. Typhimurium (1 × 105 colony-forming units, CFU) was significantly extended when the mice were injected with daily intraperitoneal doses of HWE and MWE, but not with ACE and AKE. Histology assays showed that HWE and MWE also protected liver tissues of infected mice against Salmonella-induced necrosis. HWE and MWE stimulated uptake of the bacteria into the macrophage cells, as indicated by disappearance of the bacteria from the media and by increased initial CFU counts of the contents of the lysed macrophages, followed by lower counts as time progressed. HWE- and MWE-treated non-infected macrophages had altered morphology and elevated inducible nitric oxide (NO) synthase (iNOS) mRNA expression. In the presence of Salmonella Typhimurium, iNOS mRNA expression was further increased, accompanied by an increase in NO production by the macrophages. Bioactivities of the extracts were related to their composition. These results suggest that HWE and MWE extracts of the mushroom H. erinaceus are beneficial in the treatment of bacterial infection through the activation of innate immune cells, such as macrophages, and could be used to prevent or treat bacterial infections.