Dose Response Effect of Lipoarabinomannan from Mycobacterium smegmatis Stimulates RAW 264.7 Murine Macrophage Response

Mycobacterium smegmatis is closely related to the pathogenic M. tuberculosis. The precise mechanism by which M. tuberculosis is able to evade acidification by the phagosomes of macrophages is not yet known, so understanding the interactions between macrophages and the cell wall components on Mycobacteria is of great relevance. Lipoarabinomannan (LAM) is a glycolipid Toll-Like Receptor-2 ligand found on the cell wall of mycobacteria. The purpose of this research is to evaluate the optimal dose of LAM to elicit an inducible nitric oxide synthase (iNOS) and Tumor Necrosis Factor-alpha (TNF-α) response in RAW 264.7 murine macrophages. Concentrations of LAM are 10 ng/mL, 100 ng/mL, and 1000 ng/mL, with a positive control of 100 ng/mL Lipopolysaccharide (LPS) from E. coli. Nitrite response is measured using the Greiss reaction. Initial nitrite response indicates that LAM is less effective at stimulating RAW 264.7 macrophages compared to LPS. Understanding LAM as a stimulus to macrophage activation will advance our understanding of the potential mechanisms by which M. tuberculosis evades macrophage responses. This could lead to research that can explore new avenues for the treatment of M. tuberculosis infection