|Lee, Kyung Woo|
Submitted to: Research in Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2011
Publication Date: 9/28/2011
Citation: Lee, K., Li, G., Lillehoj, H.S., Lee, S.H., Jang, S.I., Babu, U.S., Lillehoj, E.P., Newumann, A.P., Siragusa, G.R. 2011. Bacillus subtilis-based direct-fed microbials augment macrophage function in broiler chickens. Research in Veterinary Science. 91:E87-91. Interpretive Summary: Direct-fed microbials (DFM), commonly known as probiotics, are live microorganisms that could confer a health benefit on the host. Feeding chickens with DFMs have shown to lead enhanced immunity and stronger epithelial barrier integrity. These activities of DFMs provide scientific basis for their use in augmenting the chicken’s protective immunity against pathogens at early ages in poultry production. In this collaborative study carried out in collaboration with scientists at the Danisco/Agtech company, ARS scientists demonstrated that young birds which were fed DFM-supplemented diet from hatch showed enhanced function of macrophages, a key component of host innate immunity which participates in host defense. Early dietary treatment of young birds with Bacillus subtilis-based direct-fed microbials (DFMs) consistently showed significant activation of macrophage functions, i.e., nitric oxide (NO) production and phagocytosis whereas untreated birds did not show any significant changes. Taken together, this study documented that early dietary DFM feeding is a beneficial way to improve gut health of young chickens and is an environmentally safe and rational method to enhance host innate immunity and to lessen the use of antibiotics in animal production. In view of increasing scientific evidence elucidating the role of the gut microbiota on host immunity, further studies to identify properties and biological effects of different bacterial strains on gut physiology and immune system development should be encouraged.
Technical Abstract: The present study was conducted to evaluate the function of Bacillus subtilis-based direct-fed microbials (DFMs) on macrophage functions, i.e., nitric oxide (NO) production and phagocytosis in broiler chickens. DFMs used in this study were eight single strains designated as Bs2084, LSSAO1, 3AP4, Bs18, 15AP4, 22CP1, Bs27, and Bs278, and one multiple strain DFM product (Avicorr™) containing equal amount of Bs2084, LSSAO1 and 15AP4. NO concentrations were monitored in plasma and in the supernatants from the peripheral blood-derived monocytic cells (PBMC)-derived macrophages stimulated by either chicken recombinant interferon gamma (IFN') or lipopolysaccharide (LPS) from Escherichia coli or Salmonella typhi. In addition, phagocytosis of fluorescent beads and green fluorescent protein (GFP)-labeled Salmonella by PBMC-derived macrophage was assayed. Plasma NO levels were significantly higher in groups given 3AP4 or Bs27 diets compared with the control group at days 7 and 14. NO production by PBMC-derived macrophages stimulated with IFN' or LPS was apparent, although the effect was strain-dependent. Phagocytosis of fluorescent beads or GFP-labeled Salmonella by macrophages was augmented in groups on DFM-supplemented diets compared with those fed the control diet. This study describes the immunomodulatory effects of Bacillus-based DFMs on innate immunity in broiler chickens.