<i>Lactobacillus plantarum</i> CONDITIONED MEDIA REDUCES THE SEVERITY OF COLITIS AND INDUCES A SHIFT IN MACROPHAGE PHENOTYPE

• Main Author: TAYLOR, MICHELLE MARIE
• Other Authors: Queen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.))
• Language: en; en
• Published: 2011
• Subjects: colitis; probiotic; Salmonella; macrophage
• Online Access: http://hdl.handle.net/1974/6789

Lactobacillus plantarum is known to reduce the inflammatory response of macrophages in vitro and decrease inflammation in vivo during colitis. A predominance of M2, anti-inflammatory, macrophages correlates with a reduced severity of colitis. The purpose of this study was to determine if L. plantarum-conditioned media is able to produce an anti-inflammatory macrophage response during Salmonella-induced colitis while also reducing inflammation. Female C57BL/6 mice were infected with Salmonella after streptomycin pretreatment, then gavaged with L. plantarum-conditioned media (or a control) four hours prior to infection and twenty-four hours post-infection, they were sacrificed forty-eight hours post-infection. Samples of the intestines, blood, peritoneal exudate macrophages, spleen derived macrophages, and bone marrow-derived macrophages were collected. L. plantarum-conditioned media was found to limit inflammation in a dose related manner. Inflammation was measured by cecum histology, myeloperoxidase activity in the intestine, and monocyte chemoattractant protein-1 levels in the blood. IκB-α levels in the intestinal epithelium were measured by Western blot and degradation was reduced by L. plantarum-conditioned media treatment of Salmonella infected mice. Macrophages from L. plantarum-conditioned media treated Salmonella infected mice were found to have an M2 phenotype that was not found in any other treatment group. The phenotype markers arginase-1 and Ym-1 were found to be elevated in L. plantarum-conditioned media treated Salmonella infected mice by Western blot, while Src homology 2-containing inositol phosphatase-1 was reduced. Flow cytometry for the M2 markers CD206 and CD14 along with the M1 markers CD16 and CCR7 showed a similar M2 phenotype shift of macrophages from L. plantarum-conditioned media treated Salmonella infected mice. The cytokine profile of macrophages from L. plantarum-conditioned media treated Salmonella infected mice was anti-inflammatory with elevated IL-10 and decreased IL-6, IL-12, and TNF-α supporting the M2 phenotype. The protective effects of L. plantarum-conditioned media were found to be at least partially macrophage dependent in a macrophage transfer experiment. In vitro, L. plantarum-conditioned media was also found to produce M2 phenotype macrophages but have no effect on phagocytic or bactericidal function. In conclusion, L. plantarum-conditioned media provides a novel means of producing an anti-inflammatory immune response during Salmonella infection without compromising the host’s ability to combat infection. === Thesis (Master, Microbiology & Immunology) -- Queen's University, 2011-09-29 10:07:20.666