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Background: Macrophages produce many inflammation-associated molecules, released by matrix metalloproteinases, such as adhesion molecules, and cytokines, as well, which play a crucial role in atherosclerosis. In this context, we investigated the relationship between Ninjurin-1 (Ninj1 [nerve injury-induced protein]), a novel matrix metalloproteinase 9 substrate, expression, and atherosclerosis progression., Methods: Ninj1 expression and atherosclerosis progression were assessed in atherosclerotic aortic tissue and serum samples from patients with coronary artery disease and healthy controls, and atheroprone apolipoprotein e-deficient ( Apoe -/- ) and wild-type mice, as well. Apoe -/- mice lacking systemic Ninj1 expression ( Ninj1 specifically in bone marrow-derived cells. Mice were fed a Western diet for 5 to 23 weeks, and atherosclerotic lesions were investigated. The anti-inflammatory role of Ninj1 was verified by treating macrophages and mice with the peptides Ninj1 -/- Apoe -/- ) were generated to assess the functional effects of Ninj1. Bone marrow transplantation was also used to generate low-density lipoprotein receptor-deficient ( Ldlr -/- ) mice that lack Ninj1 specifically in bone marrow-derived cells. Mice were fed a Western diet for 5 to 23 weeks, and atherosclerotic lesions were investigated. The anti-inflammatory role of Ninj1 was verified by treating macrophages and mice with the peptides Ninj1 1 -56 (ML56) and Ninj1 26 -37 (PN12), which mimic the soluble form of Ninj1 (sNinj1)., Results: Our in vivo results conclusively showed a correlation between Ninj1 expression in aortic macrophages and the extent of human and mouse atherosclerotic lesions. Ninj1 -deficient macrophages promoted proinflammatory gene expression by activating mitogen-activated protein kinase and inhibiting the phosphoinositide 3-kinase/Akt signaling pathway. Whole-body and bone marrow-specific Ninj1 deficiencies significantly increased monocyte recruitment and macrophage accumulation in atherosclerotic lesions through elevated macrophage-mediated inflammation. Macrophage Ninj1 was directly cleaved by matrix metalloproteinase 9 to generate a soluble form that exhibited antiatherosclerotic effects, as assessed in vitro and in vivo. Treatment with the sNinj1-mimetic peptides, ML56 and PN12, reduced proinflammatory gene expression in human and mouse classically activated macrophages, thereby attenuating monocyte transendothelial migration. Moreover, continuous administration of mPN12 alleviated atherosclerosis by inhibiting the enhanced monocyte recruitment and inflammation characteristics of this disorder in mice, regardless of the presence of Ninj1., Conclusions: Ninj1 is a novel matrix metalloproteinase 9 substrate in macrophages, and sNinj1 is a secreted atheroprotective protein that regulates macrophage inflammation and monocyte recruitment in atherosclerosis. Moreover, sNinj1-mediated anti-inflammatory effects are conserved in human macrophages and likely contribute to human atherosclerosis.

Activated macrophages show increased expression of vimentin, an intermediate filament protein. Macrophages secrete vimentin into extracellular space; however, the functions of extracellular vimentin and the process of vimentin secretion are not clearly defined. We found that oxidized low-density lipoproteins (oxLDL) via CD36 induced vimentin secretion in macrophages. We also revealed that extracellular vimentin induced macrophages to release inflammatory cytokines and augmented oxLDL-induced release of TNF-α and IL-6. Extracellular vimentin activated NF-κB signaling via phosphorylation of focal adhesion kinase (p-FAK) and IκB kinase (p-IκK). Extracellular vimentin also amplified the oxLDL-induced p-IκK increase and IκB decrease. Vimentin-induced TNF-α release was not dependent on Dectin-1, which is known to bind vimentin. We measured serum vimentin concentrations and found that patients with atherosclerotic coronary artery disease had higher levels of serum vimentin than normal subjects. Circulating oxLDL and vimentin concentrations showed a high degree of correlation. In mouse experiments, vimentin concentration was higher in the sera of apoE null mice with western diet-induced atherosclerosis than in the sera of chow diet-fed apoE null mice without atherosclerosis. We concluded that vimentin is secreted by oxLDL/CD36 interaction in macrophages and extracellular vimentin promotes macrophage release of pro-inflammatory cytokines. This may contribute to atherosclerotic inflammation and based on our analysis of serum vimentin, we suggest serum vimentin as a predictive marker for atherosclerosis. KEY MESSAGES: OxLDL via CD36 induces secretion of vimentin, a cytoskeletal protein in macrophages. Extracellular vimentin induces macrophages to release proinflammatory cytokines such as tumor necrotizing factor-alpha (TNF-α) and this process is mediated by activation of focal adhesion kinase (FAK) and NF-ƙB signaling. Serum concentrations of vimentin in coronary artery disease patients are higher than that in control group. Vimentin concentration is strongly correlated with oxLDL concentration in serum.

Oxidative stress activates macroautophagy/autophagy and contributes to atherogenesis via lipophagic flux, a form of lipid removal by autophagy. However, it is not known exactly how endogenous antioxidant enzymes are involved in lipophagic flux. Here, we demonstrate that the antioxidant PRDX1 (peroxiredoxin 1) has a crucial role in the maintenance of lipophagic flux in macrophages. PRDX1 is more highly expressed than other antioxidant enzymes in monocytes and macrophages. We determined that Prdx1 deficiency induced excessive oxidative stress and impaired maintenance of autophagic flux in macrophages. Prdx1-deficient macrophages had higher intracellular cholesterol mass and lower cholesterol efflux compared with wild type. This perturbation in cholesterol homeostasis was due to impaired lipophagic cholesterol hydrolysis caused by excessive oxidative stress, resulting in the inhibition of free cholesterol formation and the reduction of NR1H3 (nuclear receptor subfamily 1, group H, member 3) activity. Notably, impairment of both lipophagic flux and cholesterol efflux was restored by the 2-Cys PRDX-mimics ebselen and gliotoxin. Consistent with this observation, apoe -/- mice transplanted with bone marrow from prdx1 -/- apoe -/- mice had increased plaque formation compared with apoe -/- BM-transplanted recipients. This study reveals that PRDX1 is crucial to regulating lipophagic flux and maintaining macrophage cholesterol homeostasis against oxidative stress. We suggest that PRDX1-dependent control of oxidative stress may provide a strategy for treating atherosclerosis and autophagy-related human diseases.

Oxidized LDL (oxLDL) performs critical roles in atherosclerosis by inducing macrophage foam cell formation and promoting inflammation. There have been reports showing that oxLDL modulates macrophage cytoskeletal functions for oxLDL uptake and trapping, however, the precise mechanism has not been clearly elucidated. Our study examined the effect of oxLDL on non-muscle myosin heavy chain IIA (MHC-IIA) in macrophages. We demonstrated that oxLDL induces phosphorylation of MHC-IIA (Ser1917) in peritoneal macrophages from wild-type mice and THP-1, a human monocytic cell line, but not in macrophages deficient for CD36, a scavenger receptor for oxLDL. Protein kinase C (PKC) inhibitor-treated macrophages did not undergo the oxLDL-induced MHC-IIA phosphorylation. Our immunoprecipitation revealed that oxLDL increased physical association between PKC and MHC-IIA, supporting the role of PKC in this process. We conclude that oxLDL via CD36 induces PKC-mediated MHC-IIA (Ser1917) phosphorylation and this may affect oxLDL-induced functions of macrophages involved in atherosclerosis.

It has been reported that Rhusverniciflua exhibits anti-inflammatory, anti-oxidant and anti-cancer activities. However, little is known about biological activity of sulfuretin, a flavonoid isolated from R.verniciflua. In the present study, we investigated the anti-inflammatory effect and the underlying molecular mechanisms of sulfuretin in lipopolysaccharide (LPS)-induced RAW 264.7 cells. Sulfuretin dose-dependently reduced the productions of nitric oxide (NO), prostaglandin E(2) (PGE(2)), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1 beta (IL-1 beta) induced by LPS. Consistent with these findings, sulfuretin significantly suppressed the LPS-induced expressions of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), TNF-alpha, and IL-1 beta. In addition, sulfuretin attenuated LPS-induced DNA binding and the transcriptional activities of nuclear factor-kappa B (NF-kappaB), which was accompanied by a parallel reduction of degradation and phosphorylation of inhibitory kappa B-alpha (I kappaB-alpha) and consequently by decreased nuclear translocation of p65 subunit of NF-kappaB. Furthermore, pretreatment with sulfuretin significantly inhibited the LPS-stimulated activation of I kappaB kinase beta (IKK beta). Taken together, these results suggest that the anti-inflammatory effect of sulfuretin in LPS-treated RAW 264.7 macrophages is associated with the suppression of NF-kappaB transcriptional activity via the inhibitory regulation of IKKbeta phosphorylation., ((c) 2010 Elsevier B.V. All rights reserved.)

Fraxinellone is formed by the natural degradation of limonoids isolated from the root bark of Dictamnus dasycarpus. Fraxinellone has been reported to possess neuroprotective and vasorelaxing activities, but the effects and the mechanism of fraxinellone in inflammation have not been fully characterized. In the present study, the anti-inflammatory effect of fraxinellone was evaluated in lipopolysaccharide (LPS)-treated RAW 264.7 macrophages. Fraxinellone was found to inhibit LPS-induced nitric oxide (NO) and prostaglandin E(2) (PGE(2)) production, and to reduce the LPS-induced expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at the mRNA and protein levels in a dose-dependent manner. Furthermore, fraxinellone significantly attenuated LPS-induced DNA binding activity and the transcription activity of nuclear factor-kappa B (NF-kappaB). Consistent with these findings, pretreatment with fraxinellone significantly suppressed the LPS-stimulated phosphorylation of inhibitory kappa B-alpha (IkappaB-alpha) and the subsequent translocation of p65 to the nucleus. Fraxinellone also suppressed the IkappaB kinase (IKK) activity and the phosphorylation of extracellular-signal-related kinase (ERK1/2), whereas the phosphorylations of Jun N-terminal kinase (JNK1/2) and p38 were unaffected. These results suggest that the anti-inflammatory properties of fraxinellone are related to the down-regulations of iNOS and COX-2 due to NF-kappaB inhibition through the negative regulations of IKK and ERK1/2 phosphorylations in RAW 264.7 cells.

During our ongoing efforts to identify bioactive natural products with anti-inflammatory activity, we produced an extract from Ginkgo biloba (GBB) which contains higher levels of the active principles terpene and biflavonoid than EGb, the standard commercially available extract. In the present study, we examined and compared the effects of these two extracts on lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin E2 (PGE2) production by the RAW 264.7 macrophage cell line. Our data indicate that GBB is a more potent inhibitor of NO and PGE2 production than EGb 761, and it also significantly decreased tumor necrosis factor (TNF)-alpha release. Consistent with these observations, the protein and mRNA expression levels of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) were found to be inhibited by GBB in a dose-dependent manner. Furthermore, GBB inhibited the LPS-induced DNA binding activity of nuclear factor-kappaB (NF-kappaB), which was associated with the prevention of IkappaB degradation, and subsequently with decreased p65 protein level in the nucleus. These results suggest that GBB inhibits LPS-induced iNOS, COX-2 and TNF-alpha expressions through the down-regulation of NF-kappaB-DNA binding activity.

The anti-inflammatory effects of the methanol extract of the roots of Morinda officinalis (MEMO) (Rubiaceae) were evaluated in-vitro and in-vivo. The effects of MEMO on lipopolysaccharide (LPS)induced responses in the murine macrophage cell line RAW 264.7 were examined. MEMO potently inhibited the production of nitric oxide (NO), prostaglandin E2 and tumour necrosis factor-alpha (TNF-alpha) in LPS-stimulated RAW 264.7 macrophages. Consistent with these results, the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at the protein level, and of iNOS, COX-2 and TNF-alpha at the mRNA level, was also inhibited by MEMO in a concentration-dependent manner. Furthermore, MEMO inhibited the nuclear factor kappa B (NF-kappaB) activation induced by LPS, and this was associated with the prevention of degradation of the inhibitor kappaB (IkappaB), and subsequently with attenuated p65 protein in the nucleus. The anti-inflammatory effect of MEMO was examined in rats using the carrageenan-induced oedema model. The antinociceptive effects of MEMO were assessed in mice using the acetic acid-induced abdominal constriction test and the hot-plate test. MEMO (100, 200 mg kg-1 per day, p.o.) exhibited anti-inflammatory and antinociceptive effects in these animal models. Taken together, the data demonstrate that MEMO has anti-inflammatory and antinociceptive activity, inhibiting iNOS, COX-2 and TNF-alpha expression by down-regulating NF-kappaB binding activity.

Atherosclerosis, the major pathology of cardiovascular disease, is caused by multiple factors involving psychological stress. Corticotropin-releasing hormone (CRH), which is released by neurosecretory cells in the hypothalamus, peripheral nerve terminals and epithelial cells, regulates various stress-related responses. Our current study aimed to verify the role of CRH in macrophage foam cell formation, the initial critical stage of atherosclerosis. Our quantitative real-time reverse transcriptase PCR (qRT-PCR), semi-quantitative reverse transcriptase PCR, and Western blot results indicate that CRH down-regulates ATP-binding cassette transporter-1 (ABCA1) and liver X receptor (LXR)-α, a transcription factor for ABCA1, in murine peritoneal macrophages and human monocyte-derived macrophages. Oil-red O (ORO) staining and intracellular cholesterol measurement of macrophages treated with or without oxidized LDL (oxLDL) and with or without CRH (10 nM) in the presence of apolipoprotein A1 (apoA1) revealed that CRH treatment promotes macrophage foam cell formation. The boron-dipyrromethene (BODIPY)-conjugated cholesterol efflux assay showed that CRH treatment reduces macrophage cholesterol efflux. Western blot analysis showed that CRH-induced down-regulation of ABCA1 is dependent on phosphorylation of Akt (Ser473) induced by interaction between CRH and CRH receptor 1(CRHR1). We conclude that activation of this pathway by CRH accelerates macrophage foam cell formation and may promote stress-related atherosclerosis. [ABSTRACT FROM AUTHOR]

The trapping of lipid-laden macrophages in the arterial intima is a critical but reversible step in atherogenesis. However, the mechanism by which this occurs is not clearly defined. Here, we tested in mice the hypothesis that CD36, a class B scavenger receptor expressed on macrophages, has a role in this process. Using both in vivo and in vitro migration assays, we found that oxidized LDL (oxLDL), but not native LDL, inhibited migration of WT mouse macrophages but not CD36-deficient cells. We further observed a crucial role for CD36 in modulating the in vitro migratory response of human peripheral blood monocyte-derived macrophages to oxLDL. oxLDL also induced rapid spreading and actin polymerization in CD36-sufficient but not CD36-deficient mouse macrophages in vitro. The underlying mechanism was dependent on oxLDL-mediated CD36 signaling, which resulted in sustained activation of focal adhesion kinase (FAK) and inactivation of Src homology 2-containing phosphotyrosine phosphatase (SHP-2). The latter was due to NADPH oxidase-mediated ROS generation, resulting in oxidative inactivation of critical cysteine residues in the SHP-2-active site. Macrophage migration in the presence of oxLDL was restored by both antioxidants and NADPH oxidase inhibitors, which restored the dynamic activation of FAK. We conclude therefore that CD36 signaling in response to oxLDL alters cytoskeletal dynamics to enhance macrophage spreading, inhibiting migration. This may induce trapping of macrophages in the arterial intima and promote atherosclerosis. [ABSTRACT FROM AUTHOR]