Sulforaphane reduces intracellular survival of Staphylococcus aureus in macrophages through inhibition of JNK and p38 MAPK‑induced inflammation

Abstract

Macrophages are active contributors to the innate immune defense system. As macrophage activation is clearly affected by the surrounding microenvironment, the present study investigated the effect of sulforaphane (SFN) on the bactericidal activity of macrophages and the underlying molecular mechanisms involved in this process. Human THP-1-derived macrophages, primary human peripheral blood mononuclear cell-derived macrophages, and primary mouse bone marrow derived-macrophages (BMdMs) pretreated with SFN or dMSO were utilized in a model of Staphylococcus aureus infection. The results suggested that SFN pretreatment of macrophages effectively repressed the intracellular survival of S. aureus through modulation of p38/JNK signaling and decreased S. aureus-induced caspases-3/7-dependent cell apoptosis, potentially through downregulation of microRNA (miR)-142-5p and miR-146a-5p. As SFN is a well-known activator of nuclear factor erythroid 2-related factor 2 (Nrf2), Nrf2 -/-BMdMs were used to demonstrate that the SFN-mediated inhibitory effect was independent of Nrf2. Nevertheless, an increase in intracellular bacterial survival in Nrf2-deficient macrophages was observed. In addition, SFN pretreatment suppressed S. aureus-induced transcriptional expression of genes coding for the proinflammatory cytokines interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α), as well as for the M1 markers c-c motif chemokine receptor 7, IL-23 and inducible nitric oxide synthase (iNOS). Western blot analysis indicated that S. aureus challenge activated p38 mitogen-activated protein kinase (MAPK) (p38) and c-Jun N-terminal kinase (JNK) MAPK signaling pathways, while SFN pretreatment prevented p38 and JNK phosphorylation. Pretreatment with 2 specific inhibitors of p38 and JNK, SB203580 and SP600125, respectively, resulted in a decrease in S. aureus-induced proinflammatory gene expression levels compared with those observed in the SFN-pretreated macrophages. Furthermore, THP-1-derived macrophages pretreated with SB203580 or SP600125 prior to bacterial infection exhibited a significant inhibition in intracellular S. aureus survival.In conclusion, we hypothesize that concomitant targeting of the p38/JNK-inflammatory response and the S. aureus-induced apoptosis with SFN may be a promising therapeutic approach in S. aureus infection.

Comparing the protective effects of resveratrol, curcumin and sulforaphane against LPS/IFN-γ-mediated inflammation in doxorubicin-treated macrophages

“…Based on these observations, we hypothesized that the anti-inflammatory effect of SFN can be extended to modulate the overexpression of these target miRNAs in LPS/IFN-γ-stimulated RAW 264.7 macrophages. In line with the study of Deramaudt et al 55 , our findings revealed that SFN significantly downregulated miR-146a levels (Fig. 12 A), which might be explained as dependent-downregulatory negative feedback in response to the SFN inhibitory effect on TLR4 signaling 56 .…”

Potential of Sulforaphane as a Natural Immune System Enhancer: A Review

“…SFN, as a potent Nrf2 activator, seems a promising therapeutic option for Gram (+) and Gram (−) bacterial infections since it modulates antioxidant and anti-inflammatory responses. Deramaudt et al [ 62 ] studied the intracellular survival of S. aureus in human and mice macrophages treated with SFN. They proposed a mechanism consisting in modulation of p38/JNK signal pathway induced by SFN in macrophages, thus reducing inflammatory response.…”

Dietary Isothiocyanates, Sulforaphane and 2-Phenethyl Isothiocyanate, Effectively Impair Vibrio cholerae Virulence

“…But yet, the detailed mechanism of this observation should be elucidated to define SFN-triggered cellular factors. Deramaudt et al [ 64 ] proposed a combinatory mechanism where reduction of the inflammatory response through modulation of p38 and JNK signaling pathways accompanied antibacterial action of SFN in mice macrophages infected with S. aureus . A similar mode of action may operate in G. mellonella, especially as this organism possesses counterpart MAP kinases, and they are activated in response to infection with the entomopathogenic bacterium Bacillus thuringiensis [ 65 , 66 ] Finally, the dosages chosen for in vivo virulence assay were comparable to those used and reported as safe to treat human diseases.…”