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Published on: January 17, 2012
Progranulin inhibits LPS-induced macrophage M1 polarization via NF-кB and MAPK pathways
Lianlian Liu1,2,3, Hongmei Guo1, Aimei Song1,2,3
1Department of Periodontology, School of Stomatology, Shandong University, 44 West Wenhua Road, Jinan, 250012, Shandong, People's Republic of China.
Background:
Macrophage M1 polarization plays a pivotal role in inflammatory diseases. Progranulin (PGRN) has potential anti-inflammation action, however, the effect of PGRN on macrophage M1 polarization has been poorly studied. Our study aimed to investigate the effect of PGRN on lipopolysaccharide (LPS)-induced macrophage M1 polarization and clarify the underlying mechanisms.
Methods:
RAW264.7 cells were polarized to M1 macrophage by LPS with or without recombinant PGRN (rPGRN) and tumor necrosis factor alpha antibody (anti-TNF-α). A cell counting kit-8 assay (CCK-8), flow cytometry, Quantitative Real-Time PCR assay (q-PCR), Western blot assay and enzyme-linked immunosorbent assay (ELISA) were used to determine the effect of different treatments on cell proliferation, expression of surface phenotype marker and expressions and secretion of inflammatory cytokines. The activation of NF-κB/mitogen-activated protein kinase (MAPK) pathways and the nuclear translocation of NF-κB p65 were detected by Western blot and immunofluorescence respectively. THP-1 and primary bone marrow-derived monocytes (BMDMs) were also used to demonstrate effect of PGRN on expressions and secretion of inflammatory cytokines induced by LPS.
Results:
In RAW264.7 cells, rPGRN at concentrations below 80 ng/ml significantly promoted cell proliferation in dose dependent fashion. rPGRN significantly inhibited LPS-induced change of phenotype (CD86/CD206 ratio) and function (tumor necrosis factor (TNF-α) and inducible nitric oxide synthase (iNOS) expressions). LPS-stimulated secretion of TNF-α and activated phosphorylation of IKKα/β, IкBα, p65, JNK and p38 and the nucleus translocation of NF-кB p65 were also significantly downregulated by rPGRN. In addition, recombinant TNF-α (rTNF-α) significantly boosted TNF-α and iNOS expression vs the control group. Moreover, anti-TNF-α significantly inhibited LPS-induced TNF-α and iNOS expression. In THP-1 and BMDM cells, reversing effect of rPGRN on LPS-enhanced expressions of TNF-α and iNOS and secretion of TNF-α was further demonstrated.
Conclusions:
PGRN down-regulates LPS-induced macrophage M1 polarization in phenotype and function via NF-κB/MAPK signaling pathways.
Insights
Progranulin (PGRN) inhibits lipopolysaccharide (LPS)-induced M1 macrophage polarization by suppressing inflammatory markers and NF-κB/MAPK pathways. This finding offers potential therapeutic strategies for inflammatory diseases.
Area of Science:
- Immunology
- Cell Biology
Background:
- Macrophage M1 polarization is crucial in inflammatory diseases.
- Progranulin (PGRN) exhibits anti-inflammatory properties, but its effect on M1 polarization is understudied.
Purpose of the Study:
- To investigate PGRN's effect on lipopolysaccharide (LPS)-induced M1 macrophage polarization.
- To elucidate the underlying molecular mechanisms of PGRN's action.
Main Methods:
- RAW264.7, THP-1, and bone marrow-derived monocyte (BMDM) cells were used.
- Cells were treated with LPS, recombinant PGRN (rPGRN), and anti-TNF-α.
- Assays included CCK-8, flow cytometry, q-PCR, Western blot, and ELISA.
- NF-κB/MAPK pathway activation and NF-κB p65 nuclear translocation were assessed.
Main Results:
- rPGRN promoted cell proliferation at concentrations below 80 ng/ml.
- rPGRN inhibited LPS-induced M1 phenotype (CD86/CD206 ratio) and function (TNF-α, iNOS).
- rPGRN downregulated LPS-stimulated TNF-α secretion and NF-κB/MAPK pathway activation.
- rPGRN's effects were confirmed in THP-1 and BMDM cells.
Conclusions:
- PGRN down-regulates LPS-induced M1 macrophage polarization in phenotype and function.
- The mechanism involves the suppression of NF-κB/MAPK signaling pathways.
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