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Depletion and Reconstitution of Macrophages in Mice
Published on: August 1, 2012
Geniposide inhibits SphK1 membrane targeting to restore macrophage polarization balance in collagen-induced arthritis
Pei-Rong Gan1, Rong-Hui Wang1, Ran Deng2
1College of Pharmacy, Anhui University of Chinese Medicine, Qian Jiang Road 1, Hefei, 230012, China; Key Laboratory of Xin'an Medicine, Ministry of Education, Hefei, 230012, China; Anhui Province Key Laboratory of Research & Development of Chinese Medicine, Hefei, 230012, China.
Abstract:
Imbalance of macrophage polarization plays a critical role in the progression of rheumatoid arthritis (RA). Geniposide (GE) has been shown to exert anti-inflammatory effects. However, the effect of GE on macrophage polarization remains unclear. Here, we investigated the regulation of GE on the imbalance of macrophage polarization in RA and how it functions. We established a mouse model of collagen-induced arthritis (CIA) and isolated bone marrow-derived macrophages (BMDMs). The results confirmed that pro-inflammatory M1 macrophages were dominant in CIA mice, but the polarization imbalance of macrophages was restored to a certain extent after GE treatment. Furthermore, the membrane targeting of sphingosine kinase 1 (SphK1) was increased in BMDMs of CIA mice, as manifested by increased membrane and cytoplasmic expression of p-SphK1 and high secretion level of sphingosine-1-phosphate (S1P). RAW264.7 cells were stimulated with lipopolysaccharide (LPS)-interferon (IFN)-γ or interleukin (IL)-4 to induce M1 or M2 phenotype, respectively, to revalidate the results obtained in BMDMs. The results again observed SphK1 membrane targeting in LPS-IFN-γ-stimulated RAW264.7 cells. Selective inhibition of SphK1 by PF543 or inhibition of the S1P receptors by FTY720 both restored the proportion of M1 and M2 macrophages in LPS-IFN-γ-stimulated RAW264.7 cells, confirming that SphK1 membrane targeting mediated a proportional imbalance in M1 and M2 macrophage polarization. In addition, GE inhibited SphK1 membrane targeting and kinase activity. Taken together, results confirmed that the inhibition of SphK1 membrane targeting by GE was responsible for restoring the polarization balance of macrophages in CIA mice.
Insights
Geniposide (GE) treatment restores macrophage polarization balance in rheumatoid arthritis (RA) by inhibiting sphingosine kinase 1 (SphK1) membrane targeting. This finding offers a potential therapeutic strategy for RA by modulating immune cell function.
Area of Science:
- Immunology
- Rheumatology
- Pharmacology
Background:
- Macrophage polarization imbalance is crucial in rheumatoid arthritis (RA) pathogenesis.
- Geniposide (GE) exhibits anti-inflammatory properties, but its effect on macrophage polarization is unknown.
Purpose of the Study:
- To investigate how GE regulates macrophage polarization imbalance in RA.
- To elucidate the functional mechanism of GE in modulating macrophage polarization.
Main Methods:
- Established a collagen-induced arthritis (CIA) mouse model and isolated bone marrow-derived macrophages (BMDMs).
- Utilized RAW264.7 cells stimulated with LPS-IFN-γ (M1) or IL-4 (M2) to validate findings.
- Assessed sphingosine kinase 1 (SphK1) membrane targeting and sphingosine-1-phosphate (S1P) secretion.
- Investigated the effects of SphK1 inhibition (PF543) and S1P receptor blockade (FTY720).
Main Results:
- CIA mice exhibited dominant pro-inflammatory M1 macrophages; GE treatment partially restored balance.
- Increased SphK1 membrane targeting and S1P secretion were observed in CIA mouse BMDMs and LPS-IFN-γ-stimulated RAW264.7 cells.
- Inhibition of SphK1 or S1P receptors normalized M1/M2 macrophage proportions.
- GE inhibited SphK1 membrane targeting and kinase activity, restoring macrophage polarization balance in CIA mice.
Conclusions:
- SphK1 membrane targeting is a key mechanism driving M1/M2 macrophage imbalance in RA.
- GE restores macrophage polarization balance in RA by inhibiting SphK1 membrane targeting.
- GE represents a potential therapeutic agent for RA by modulating macrophage polarization.
