Dataset Information

C-reactive protein polarizes human macrophages to an M1 phenotype and inhibits transformation to the M2 phenotype.

ABSTRACT: Inflammation is pivotal in atherosclerosis. Monocyte-macrophages are crucial in atherosclerosis. Monocytes can develop into subsets: classically (M1) or alternatively (M2) activated cells. Several studies point to a proinflammatory role for C-reactive protein (CRP). Because there is a paucity of data on the effects of CRP on macrophage phenotype, we tested effects of CRP on macrophage polarization.Monocytes were incubated with CRP (0 to 50 ?g/mL) and differentiated into macrophages for 7 days. Phenotypic characterization of M1 and M2 macrophages was performed using flow cytometry. CRP treatment resulted in increased population of M1 macrophages (tumor necrosis factor [TNF]/interleukin [IL]-12/C-C chemokine receptor 2, TNF/IL-12/monocyte chemotactic protein-1, or TNF/IL-1/IL-12). These effects were not abrogated by polymixin B or small interfering RNA to Toll-like receptor-4, but they were abrogated by boiled CRP. Administration of human CRP to rats in vivo increased polarization of macrophages to M1 phenotype compared with human serum albumin. When macrophages were primed to the M2 phenotype with IL-4, addition of CRP resulted in significantly increased secretion of TNF-?, MCP-1, and IL-1 and conversion of macrophages from the M2 to the M1 phenotype. CRP failed to prime macrophages to the M1 phenotype in presence of CD32/CD64 small interfering RNA or dominant-negative nuclear factor kappa B.Collectively, these results further support a role for CRP in promoting differentiation of human monocytes toward a proinflammatory M1 phenotype.

SUBMITTER: Devaraj S

PROVIDER: S-EPMC3099471 | biostudies-literature | 2011 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

C-reactive protein polarizes human macrophages to an M1 phenotype and inhibits transformation to the M2 phenotype.

Devaraj Sridevi S Jialal Ishwarlal I

Arteriosclerosis, thrombosis, and vascular biology 20110317 6

<h4>Objective</h4>Inflammation is pivotal in atherosclerosis. Monocyte-macrophages are crucial in atherosclerosis. Monocytes can develop into subsets: classically (M1) or alternatively (M2) activated cells. Several studies point to a proinflammatory role for C-reactive protein (CRP). Because there is a paucity of data on the effects of CRP on macrophage phenotype, we tested effects of CRP on macrophage polarization.<h4>Methods and results</h4>Monocytes were incubated with CRP (0 to 50 μg/mL) and ...[more]

PMID: 21415385

Similar Datasets

Project description:BackgroundToll-like receptors (TLRs) and macrophages play an important role in rheumatoid arthritis (RA). Currently, it is not clear whether inflammatory M1 or anti-inflammatory M2 predominate among the resident macrophages in the synovium. In the present study, we set out to investigate the impact of TLR stimulation on monocyte-derived M1 and M2 macrophage function and phenotype by mimicking the exposure to abundant TLR agonists as occurs in the context of RA. The response of macrophage subsets to TLR2 and TLR4 activation was evaluated on cluster of differentiation (CD) marker profile; cytokine secretion; gene expression; and NF-?B, interferon regulatory factors 3 and 7 (IRF3/7), and mitogen-activated protein kinase (MAPK) activation.MethodsHuman monocytes were isolated from peripheral blood of healthy individuals and patients with RA and differentiated into M1-like and M2-like macrophages by granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF), respectively. Cells were either (1) stimulated with TLR ligands Pam3 or lipopolysaccharide (LPS) or (2) classically activated via interferon (IFN)-?/LPS. Cytokine production was measured by enzyme-linked immunosorbent assay, and gene expression was measured by qPCR. Cells were stained for CD markers and analyzed by fluorescence-activated cell sorting. NF-?B, IRF3/7, and MAPKs were detected by Western blotting.ResultsMonocyte-derived macrophages of healthy donors (HD) or patients with RA displayed comparable subset-specific phenotypes upon exposure to TLR agonists. CD14 and CD163 marker expression on M2 macrophages did not change upon TLR2 and TLR4 engagement. By contrast, M2 gene markers HMOX1, FOLR2, and SLC40A1 were decreased. Importantly, M2 macrophages derived from HD or patients with RA showed both a decreased ratio of interleukin (IL)-10/IL-6 and IL-10/IL-8 upon stimulation with TLR2 ligand Pam3 compared with TLR4 ligand LPS. Gene expression of TLR2 was increased, whereas TLR4 expression was decreased, by TLR ligand stimulation. MAPKs p38, extracellular signal-regulated kinase 1/2, and c-Jun N-terminal kinase were activated more strongly in M2 than in M1 macrophages by Pam3 or LPS.ConclusionsWe show that the anti-inflammatory activity of M2 macrophages is reduced in the presence of abundant TLR2 ligands without significant changes in cell surface markers. Thus, the classical M1/M2 paradigm based on cellular markers does not apply to macrophage functions in inflammatory conditions such as RA.

Project description:BackgroundAlpha-momorcharin (α-MMC) is a natural medicine derived from bitter melon and has been found to exert immunomodulatory effects. Our previous study indicated that α-MMC can regulate cytokine release from monocytes, but it remains unknown about its regulatory effect on different types of cytokines, such as inflammatory cytokines or anti-inflammatory cytokines.MethodsLPS-induced M1-type macrophages model and IL-4-induced M2-type macrophages model were established, and the expression of proinflammatory cytokines and anti-inflammatory cytokines were assessed by ELISA after α-MMC was administered. Then, a LPS-induced acute pneumonia mouse model was established, the proinflammatory cytokines levels and inflammatory lesions in lung tissues were examined by ELISA or H&E staining. Furthermore, omics screening analysis and Western blotting verification were performed on TLR4 and JAK1-STAT6 signalling pathway-related proteins to elucidate the regulatory mechanism of α-MMC in those M1 macrophages and M2 macrophages.ResultsAt a noncytotoxic dose of 0.3 μg/mL, α-MMC significantly inhibited the LPS-induced expression of inflammatory cytokines, such as TNF-α, IL-1β, IL-6, IL-8, MIP-1α and MCP-1, by M1 macrophages in a time-dependent manner, but α-MMC did not inhibit the IL-4-induced synthesis of anti-inflammatory cytokines, such as IL-10, IL-1RA, EGF, VEGF, TGF-β and CCL22, by M2 macrophages. Moreover, α-MMC also inhibited inflammatory cytokine expression in an LPS-induced acute pneumonia mouse model and alleviated inflammation in lung tissues. Furthermore, omics screening and Western blotting analysis confirmed that α-MMC inhibited TAK1/p-TAK1 and subsequently blocked the downstream MAPK and NF-κB pathways, thus inhibiting the LPS-induced inflammatory cytokine expression.ConclusionOur results reveal that α-MMC inhibits proinflammatory cytokine expression by M1 macrophages but not anti-inflammatory cytokine expression by M2 macrophages. The efficacy of α-MMC in selectively inhibiting proinflammatory cytokine expression renders it particularly suitable for the treatment of severe inflammation and autoimmune diseases characterized by cytokine storms.

Dataset Information

C-reactive protein polarizes human macrophages to an M1 phenotype and inhibits transformation to the M2 phenotype.

Publications

C-reactive protein polarizes human macrophages to an M1 phenotype and inhibits transformation to the M2 phenotype.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets