ABSTRACT
Different studies described the antibacterial properties of Lavandula angustifolia (Mill.) essential oil and its anti-inflammatory effects. Besides, no data exist on its ability to activate human macrophages during the innate response against Staphylococcus aureus. The discovery of promising regulators of macrophage-mediated inflammatory response, without side effects, could be useful for the prevention of, or as therapeutic remedy for, various inflammation-mediated diseases. This study investigated, by transcriptional analysis, how a L. angustifolia essential oil treatment influences the macrophage response to Staphylococcus aureus infection. The results showed that the treatment increases the phagocytic rate and stimulates the containment of intracellular bacterial replication by macrophages. Our data showed that this stimulation is coupled with expression of genes involved in reactive oxygen species production (i.e., CYBB and NCF4). Moreover, the essential oil treatment balanced the inflammatory signaling induced by S. aureus by repressing the principal pro-inflammatory cytokines and their receptors and inducing the heme oxygenase-1 gene transcription. These data showed that the L. angustifolia essential oil can stimulate the human innate macrophage response to a bacterium which is responsible for one of the most important nosocomial infection and might suggest the potential development of this plant extract as an anti-inflammatory and immune regulatory coadjutant drug.
Subject(s)
Anti-Bacterial Agents/pharmacology , Anti-Inflammatory Agents/pharmacology , Lavandula/chemistry , Macrophages/drug effects , Macrophages/immunology , Oils, Volatile/pharmacology , Plant Extracts/chemistry , Staphylococcus aureus/immunology , Anti-Bacterial Agents/chemistry , Anti-Inflammatory Agents/chemistry , Cytokines/metabolism , Cytotoxicity, Immunologic/drug effects , Cytotoxicity, Immunologic/immunology , Free Radical Scavengers/chemistry , Free Radical Scavengers/pharmacology , Gas Chromatography-Mass Spectrometry , Gene Expression Regulation/drug effects , Humans , Immunity, Innate/genetics , Inflammation Mediators/metabolism , Macrophages/metabolism , Macrophages/microbiology , Microbial Sensitivity Tests , Oils, Volatile/chemistry , Phagocytosis/drug effects , Phagocytosis/immunology , Receptors, Interleukin-1/metabolism , Signal Transduction/drug effects , Toll-Like Receptors/metabolismABSTRACT
Environmental antibiotic contamination is due mainly to improper and illegal disposal of these molecules that, yet pharmacologically active, are excreted by humans and animals. These compounds contaminate soil, water and plants. Many studies have reported the bioaccumulation of antibiotics in plants and their negative effects on photosynthesis, cell growth and oxidative balance. Therefore, the principal objective of this paper was the study of antibiotic accumulation sites in plants and its uptake modality. Iberis sempervirens L., grown in soil and in agar in the presence or absence of tetracycline, were used as a model system. Using confocal and transmission electron microscopy, we demonstrated that tetracycline was absorbed and propagated in plants through apoplastic transport and also accumulated in intercellular spaces. Tetracycline was rarely detected inside cells (in cytoplasm and mitochondria where, coherent to its pharmacological activity, it probably affected ribosomes), except in stomata. Moreover, we verified and clarified further the phytotoxic effects of tetracycline on plants. We observed that the antibiotic induced a large reduction in plant growth and development and inhibition of photosynthetic activity. As tetracycline may lead to oxidative stress in plants, plant cells tried to balance this disequilibrium by increasing the amount and activity of some endogenous enzyme antioxidant agents (superoxide dismutase 1 and catalase) and levels of antiradical secondary metabolites.