AUTHOR=Gierlikowska Barbara , Gierlikowski Wojciech , Demkow Urszula 

TITLE=Alantolactone Enhances the Phagocytic Properties of Human Macrophages and Modulates Their Proinflammatory Functions

JOURNAL=Frontiers in Pharmacology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2020.01339

DOI=10.3389/fphar.2020.01339

ISSN=1663-9812

ABSTRACT=<sec><title>Aim of the Study</title><p>Phagocytosis is a crucial element of innate immune defense involved in bacterial killing. The aim of our study was to evaluate the influence of alantolactone on phagocytosis and cytokines release by THP1-derived macrophages. We assessed whether antimicrobial compound alantolactone (a sesquiterpene lactone present in <italic>Inula helenium L</italic>.) is able to stimulate immune functions of macrophages by increase of <italic>S. aureus</italic> uptake, phagosome acidification and further stimulation of phago-lysosomes formation. Simultaneously, we tested influence of alantolactone on cytokines/chemokines production and p65 NF-κB concentration. The activity of alantolactone was compared with clarithromycin at concentration 20 µM.</p></sec><sec><title>Methods</title><p>The cytotoxicity of alantolactone as well as <italic>S. aureus</italic> uptake, pH of phagosomes and phago-lysosomes fusion were analysed with flow cytometry. Reactive oxygen species and superoxide production were evaluated spectrophotometrically. The efficiency of phagocytosis was evaluated <italic>via</italic> quantifying viable bacteria (CFU). The effect on p65 protein concentration and cytokine production by macrophages were measured by enzyme-linked immunosorbent assay (ELISA).</p></sec><sec><title>Results</title><p>Alantolactone enhanced phagocytosis <italic>via</italic> increase of <italic>S. aureus</italic> uptake, acidification of phagosomes, and later stimulation of phago-lysosomes fusion. Alantolactone treatment resulted in ROS and superoxide production decrease. Furthermore, alantolactone inhibited production of pro-inflammatory cytokines TNF-α, IL-1β, IL-6, and IL-8 as well as decreased p65 concentration, the subunit responsible for NF-κB activation and cytokine production and simultaneously stimulated release of anti-inflammatory mediators (IL-10 and TGF-β).</p></sec><sec><title>Conclusion</title><p>Results of our study indicate that alantolactone enhances clearance of <italic>S. aureus</italic>, and simultaneously modulates immune response, preventing collateral damage of the surrounding tissues. Considering the importance of phagocytosis in the pathogen killing, alantolactone may have a great potential as the supportive treatment of <italic>S. aureus</italic> infections. Further <italic>in vivo</italic> studies are warranted to confirm this hypothesis.</p></sec>