Bromosulfophthalein suppresses inflammatory effects in lipopolysaccharide-stimulated RAW264.7 macrophages

Abstract

Objective

It has been reported that glutathione (GSH), the most abundant cellular antioxidant, can inhibit production of pro-inflammatory cytokines by activated macrophages. Bromosulfophthalein (BSP) has been recognized as an inhibitor of the efflux of reduced GSH from cells, leading to an increase in the intracellular GSH level. In this study, we evaluated, for the first time, whether BSP possessed anti-inflammatory effects in lipopolysaccharide (LPS)-stimulated macrophages.

Materials and methods

RAW 264.7 cells were treated with BSP and the levels of proinflammatory cytokines, GSH, and nitrite were assessed. Gene expression of inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF α), interleukin-1beta (IL-1β), and interleukin-6 (IL-6) was analyzed via quantitative RT-PCR. We also examined various inflammatory signaling pathways including Akt/forkhead box protein O1 (FoxO1)/toll-like receptor 4 (TLR4), mitogen-activated protein kinases (MAPKs), and Fas protein by Western blot and flow cytometry analysis.

Results

Our study demonstrated that BSP induced an increase in intracellular GSH level in LPS-stimulated macrophages. BSP inhibited production of nitric oxide and proinflammatory cytokines. BSP increased phosphorylation of Akt and nuclear exclusion of FoxO1 and suppressed TLR4 expression. Additionally, BSP decreased MAPKs activation and Fas expression.

Discussion and conclusion

Taken together, these data suggest that BSP can attenuate inflammation through multiple signaling pathways. These findings highlight the potential of BSP as a new anti-inflammatory agent.

Keywords:

• Bromosulfophthalein
• glutathione
• macrophages
• inflammatory responses
• signal pathways

Author contributions

Fuai Cui: data harvesting; Sean B. Sequeira: draft writing/editing; Zhenyue Huang: data harvesting; Guowei Shang: data harvesting; Quanjun Cui: experimental design/manuscript reviewing; Xinlin Yang: draft writing/editing/experimental design.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Institutes of Health [Grant No. 5R21AR070987] and by Research Fund from University of Virginia School of Medicine.