Authors: Chih-Hsuan Hsia, Ssu-Wei Cheng, Fang-I Hsieh, Li-Ming Lien.
Macrophages are essential immune cells involved in maintaining physiological homeostasis and mediating pathological responses. Activation of macrophages by lipoteichoic acid (LTA) from Gram-positive bacteria triggers inflammatory pathways, leading to the production of pro-inflammatory cytokines such as interleukin-1 beta (IL-1β) and inducible nitric oxide synthase (iNOS). Understanding the regulation of these pathways is crucial for developing therapeutic strategies for inflammatory diseases. Our previous study has demonstrated that rutaecarpine (Rut), an alkaloid from the traditional Chinese medicinal herb Evodia rutaecarpa, can modulate inflammatory responses in macrophages. This study further investigates the effects of Rut on LTA-induced activation of RAW 264.7 macrophages, focusing on cell morphology, IL-1β secretion, and iNOS expression. Cell morphology was observed using a phase-contrast microscope, and IL-1β and iNOS expressions were assessed using immunofluorescence staining and confocal microscopy. The results showed that Rut treatment did not alter the morphology of RAW 264.7 cells at concentrations up to 20 μM. At 20 μM, Rut significantly inhibited LTA-induced IL-1β secretion and iNOS expression in macrophages. Confocal microscopy revealed that LTA stimulation markedly increased IL-1β and iNOS fluorescence intensities, which were significantly reduced by Rut pre-treatment. These findings suggest that Rut effectively inhibits LTA-induced inflammatory responses in RAW 264.7 macrophages by reducing IL-1β secretion and iNOS expression without affecting cell morphology, highlighting its potential as a therapeutic agent for treating inflammatory diseases associated with Gram-positive bacterial infections.
View/Download pdf