Journal of Microbiology

Journal Article

Low-density lipoprotein as an opsonin promoting the phagocytosis of Pseudomonas aeruginosa by U937 cells: Yuxin Li , Zhi Liu , Jinli Yang , Ling Liu , Runlin Han; J. Microbiol. 2019;57(8):711-716. Published online May 11, 2019; DOI: https://doi.org/10.1007/s12275-019-8413-3

Abstract: Low-density lipoprotein (LDL) was recently reported to be an opsonin, enhancing the phagocytosis of group A Streptococcus (GAS) by human monocytic leukemia U937 cells due to the binding of LDL to some GAS strains. We postulated that LDL might also promote the opsonophagocytosis of Pseudomonas aeruginosa by U937 cells since this bacterium interacts with LDL. In this study, P. aeruginosa (CMCC10104), U937 cells, and human LDL were used in phagocytosis assays to test our hypothesis. Escherichia coli strain BL21, which does not interact with LDL, was used as a negative control. Colony counting and fluorescence microscopy were used to determine the bacterial quantity in the opsonophagocytosis assays. After incubation of U937 cells and P. aeruginosa with LDL (100 μg/ml) for 15 and 30 min, phagocytosis was observed to be increased by 22.71% and 32.90%, respectively, compared to that seen in the LDL-free group. However, LDL did not increase the phagocytosis of E. coli by U937 cells. In addition, we identified CD36 as a major opsonin receptor on U937 cells, since an anti-CD36 monoclonal antibody, but not an anti- CD4 monoclonal antibody, almost completely abolished the opsonophagocytosis of P. aeruginosa by U937 cells.

Research Support, Non-U.S. Gov't

NOTE] Initial Acidic pH Is Critical for Mycelial Cultures and Functional Exopolysaccharide Production of an Edible Mushroom, Laetiporus sulphureus var. miniatus JM 27: Min Jeong Seo , Min Jeong Kim , Hye Hyeon Lee , Sung Ryeal Kim , Byoung Won Kang , Jeong Uck Park , En Ju Rhu , Yung Hyun Choi , Yong Kee Jeong; J. Microbiol. 2010;48(6):881-884. Published online January 9, 2011; DOI: https://doi.org/10.1007/s12275-010-0410-5

Abstract: We conducted a time course experiment on mycelial cultures of Laetiporus sulphureus var. miniatus. The strain showed significant survival in an initial pH range of 2.0 to 7.0 for 24 days, during which time oxalic acid was accumulated. A structural analysis of purified exopolysaccharide suggested that it contained 96.1% glucose, and the mode of linkage was mainly-4-Glcp-(1-units, with branches at the C-6 position consisting of a Glcp-(1-4) linked side chain. An exopolysaccharide purified from the acidophilic strain was added to cultured U937 cells, resulting in significantly increased transcription levels of p53 and p21 genes.

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