Abstract
Inflammation plays a crucial role in the defense response of the innate immune system against pathogen infection. In this study, we selected 4 compounds for their potential or proven anti-inflammatory and/or anti-microbial properties to test on our in vitro model of bacteria-infected THP-1-derived macrophages. We first compared the capacity of sulforaphane (SFN), wogonin (WG), oltipraz (OTZ), and dimethyl fumarate (DMF) to induce the nuclear factor erythroid 2-related factor 2 (Nrf2), a key regulator of the antioxidant, anti-inflammatory response pathways. Next, we performed a comparative evaluation of the antioxidant and anti-inflammatory efficacies of the 4 selected compounds. THP-1-derived macrophages and LPS-stimulated macrophages were treated with each compound and expression levels of genes coding for inflammatory cytokines IL-1β, IL-6, and TNF-α were quantified by RT-qPCR. Moreover, expression levels of genes coding for M1 (IL-23, CCR7, IL-1β, IL-6, and TNF-α) and M2 (PPARγ, MRC1, CCL22, and IL-10) markers were determined in classically-activated M1 macrophages treated with each compound. Finally, the effects of each compound on the intracellular bacterial survival of gram-negative E. coli and gram-positive S. aureus in THP-1-derived macrophages and PBMC-derived macrophages were examined. Our data confirmed the anti-inflammatory and antioxidant effects of SFN, WG, and DMF on LPS-stimulated THP-1-derived macrophages. In addition, SFN or WG treatment of classically-activated THP-1-derived macrophages reduced expression levels of M1 marker genes, while SFN or DMF treatment upregulated the M2 marker gene MRC1. This decrease in expression of M1 marker genes may be correlated with the decrease in intracellular S. aureus load in SFN- or DMF-treated macrophages. Interestingly, an increase in intracellular survival of E. coli in SFN-treated THP-1-derived macrophages that was not observed in PBMC-derived macrophages. Conversely, OTZ exhibited pro-oxidant and proinflammatory properties, and affected intracellular survival of E. coli in THP-1-derived macrophages. Altogether, we provide new potential therapeutic alternatives in treating inflammation and bacterial infection.
Highlights
Inflammation is a defense response of the innate immune system triggered by pathogen and non-pathogen infections or by tissue damage
In order to compare the effect of the multifunctional compounds SFN, WG, OTZ, and dimethyl fumarate (DMF) on nuclear factor erythroid 2-related factor 2 (Nrf2), THP-1-derived macrophages were incubated with specific concentrations of SFN (10 μM), WG (25 μM), OTZ (25 μM), and DMF (20 μM) selected after dose-dependent response assays (S1 Fig) according to those used in the literature [23,32,33,34,35]
Western blot analysis of total protein lysates revealed a significant increase in Nrf2 protein level in THP-1-derived macrophages treated with SFN, OTZ, and DMF, while treatment with WG did not modulate Nrf2 protein level when compared to dimethyl sulfoxide (DMSO) treated macrophages (Fig 1A and 1B)
Summary
Inflammation is a defense response of the innate immune system triggered by pathogen and non-pathogen infections or by tissue damage. This acute and coordinated inflammatory mechanism serves in the resolution of infection or tissue repair, followed by the return to homeostasis. Depending on the surrounding environment, macrophages can adopt very distinct functional phenotypes, including a classically activated phenotype (M1) and an alternatively activated phenotype (M2). M1 macrophages are characterized by a production of proinflammatory cytokines, chemokines, and reactive oxygen and nitrogen species (ROS/RNS) [1]. M2 macrophages are characterized by a production of antiinflammatory cytokines, chemokines, and activation of antioxidant and anti-inflammatory signaling pathways, favoring tissue healing and a return to homeostasis [2,3]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
