Abstract
In nature, many plants or their extracted compounds have been found to possess anti-inflammatory features and therapeutic properties against infectious as well as non-infectious diseases, including cancer. In this study, we analysed the immunomodulatory effects on innate immune cells of hydroalcoholic extract from Origanum vulgare L. ssp. hirtum (HyE-Ov), a plant traditionally known for its anti-oxidative properties. The effects of HyE-Ov were tested on human monocyte derived dendritic cells (DC), type-1 (M1) and type-2 macrophages (M2) infected with M. bovis Bacille Calmette-Guérin (BCG), used as a model of persistent intracellular bacterium. DC, M1 and M2 treated with HyE-Ov significantly enhanced their mycobactericidal activity, which was associated with phagosomal acidification in M1 and M2 and increase of phagosomal, but not mitochondrial ROS production in M1, M2, and DC. Treatment of BCG-infected DC with HyE-Ov significantly reduced TNF-α and IL-12 production and increased TGF-β synthesis. Finally, experiments were repeated using eight different HPLC fractions of HyE-Ov. Results showed that the capability to activate anti-microbial and anti-inflammatory response is shared by different fractions, suggesting that diverse bioactive molecules are present within the hydroalcoholic extract. Altogether, these results show that HyE-Ov promotes anti-mycobacterial innate immunity and limits inflammatory response in vitro and suggest that this plant extract may be exploitable as phytocomplex or nutraceutical for novel host-directed therapeutic approaches.
Highlights
Since ancient times, man has used plants to obtain therapeutic benefits and there is an increasing scientific interest for their biological properties as they can provide a plethora of novel molecules of pharmacological interest [1]
In order to evaluate the capability of hydroalcoholic extract of O. vulgare (HyE-Ov) to induce anti-mycobacterial activity, dendritic cells (DC), M1 and M2 cells were infected with Bacille Calmette-Guerin (BCG)-lux at the multiplicity of infection (MOI) of 5 or 10, and stimulated for 3 days with HyE-Ov
Either of natural or of synthetic origin, able to suppress or stimulate the immune system, are known as immunomodulators and the interest for their identification among plants is increased during the last years [34]. Plants or their extracts may represent a source of products with immunomodulatory activity and, as such, can be used as nutraceuticals, substances that have a beneficial effect on health, or in phytotherapy, an ancient practice consisting of use of plants for the prevention or treatment of diseases
Summary
Man has used plants to obtain therapeutic benefits and there is an increasing scientific interest for their biological properties as they can provide a plethora of novel molecules of pharmacological interest [1]. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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