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Diminishment of alpha-MSH anti-inflammatory activity in MC1r siRNA-transfected RAW264.7 macrophages.

ABSTRACT: The neuropeptide alpha-melanocyte-stimulating hormone (alpha-MSH) is a powerful suppressor of inflammation mediated by macrophages, which express at least two receptors, melanocortin 1 and 3 receptors (MC1r and MC3r) that bind alpha-MSH. Albeit, the anti-inflammatory activity of alpha-MSH has been well documented in macrophages, the mechanisms of alpha-MSH activity in macrophages are not clearly understood. This study is to investigate which of the MCr expressed on macrophages is associated with the immunosuppressive activities of alpha-MSH on LPS-stimulated macrophages. To address this question, we transfected RAW264.7 macrophage cells with MC1r small interfering (si)RNA, which specifically targets mouse MC1r mRNA. The diminution of MC1r mRNA expression was 82% at 24 h and 67% at 48 h after transfection. There was a significant loss in alpha-MSH suppression of NO generation and TNF-alpha production by MC1r siRNA-transfected macrophages stimulated with LPS. There was an equally diminished alpha-MSH suppression of LPS-stimulated intracellular activation of NF-kappaB and p38 phosphorylation. In addition, the diminishment of MC1r expression by siRNA transfection had no influence on MC3r expression and function in the macrophages. These findings demonstrate that alpha-MSH suppression of LPS-induced inflammatory activity in macrophages requires expression of MC1r. The results imply that although all of the MCr are G-coupled proteins, they may not necessarily function through the same intracellular pathways in macrophages.

SUBMITTER: Li D

PROVIDER: S-EPMC3178503 | biostudies-literature | 2008 Jul

REPOSITORIES: biostudies-literature

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Diminishment of alpha-MSH anti-inflammatory activity in MC1r siRNA-transfected RAW264.7 macrophages.

Li Dayu D Taylor Andrew W AW

Journal of leukocyte biology 20080403 1

The neuropeptide alpha-melanocyte-stimulating hormone (alpha-MSH) is a powerful suppressor of inflammation mediated by macrophages, which express at least two receptors, melanocortin 1 and 3 receptors (MC1r and MC3r) that bind alpha-MSH. Albeit, the anti-inflammatory activity of alpha-MSH has been well documented in macrophages, the mechanisms of alpha-MSH activity in macrophages are not clearly understood. This study is to investigate which of the MCr expressed on macrophages is associated with ...[more]

PMID: 18388300

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Project description:Defense and protection to multiple harmful stimuli are the inflammation, when is self-amplified and uncontrolled is the basis of the pathogenesis of a wide variety of inflammatory illness. The aim of this study was to evaluate if Petiveria alliacea could attenuate inflammation in a murine model of RAW264 macrophages the involved model and its involved mechanism.The ethanol extract from P. alliacea was precipitated with water and supernatant was used for this study (PW). The anti-inflammatory effects of PW were investigated through evaluating of the production of several cytokines, chemokines, and expression of nuclear factor-kappa B (NF-κB) in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Also was determined the ability to decrease the oxidative stress in RAW264.7 cells with carboxy-2',7'-dichloro-dihydro-fluorescein diacetate.PW significantly suppress the secretion of prostaglandin E2, leukotriene C4, interleukin (IL)-1 β, IL-6, IL-10, interferon gamma nitric oxide (NO), inducible NO synthase, IL-1 β, IL-4, in RAW264.7 cells in a dose-dependent manner. In addition, PW also markedly inhibited the transcriptional activity of NF-κB. PW produced significant anti-inflammatory activity through inhibiting the production of inflammatory mediators through the NF-κB inactivation in the LPS-stimulated RAW24.7 cells.PW exerts significant antioxidant and anti-inflammatory activities, and this effect can be attributed in part, to the presence of dibenzyl disulfide, dibenzyl trisulfide pinitol, coumarin, myricetin, glutamyl-S-benzyl cysteine, and petiveriins A and B.Treatment with ethanol extract from Petiveria alliacea which was previously precipitated with water and supernatant (PE) was tested in LPS-stimulated RAW264.7 cells. PE suppressed the level of oxidative stress and the induction of proinflammatory mediators, as PGE2, LTC4, IL-1 ß, IL-6, IL-10, IFN- NO, iNOS, IL-1 ß, IL-4, in RAW264.7 macrophages through NF-B inactivation. These findings suggest that P. alliacea affords promising therapeutic in inflammatory diseases. Abbreviation used: COX-2: Ciclooxigenasa 2; DCFHDA: Carboxy-2',7'-dichloro-dihydro-fluorescein diacetate; DMEM: Dulbecco's modified eagle's medium; FBS: Fetal bovine serum; HSP70: Heat shock protein; IFN-γ: Interferon gamma; IL-1 β: Interleukin 1 β, IL-6: Interleukin 6; IL-10: Interleukin 10; IL-4: Interleukin 4; iNOS: Nitric oxide synthase; KCl: Potassium chloride; LPS: Lipopolysaccharides; LTC4: leukotriene C 4; MgCl2: Magnesium chloride; MTT: 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl-tetrazolium bromide; NF-κB: Nuclear factor kappa-light-chain-enhancer of activated B-cells or transcriptional activity of nuclear factor-kB; NO: Nitric oxide; PBS: Phosphate-buffered saline; PGE2: Prostaglandin E2, PMSF: Phenylmethylsulfonyl fluoride; PTC: Chloroform extract from Petiveria alliacea; PE: Ethanol extract from Petiveria alliacea; PTH: Hexane extract from Petiveria alliacea; PW: Supernatant of PTE precipitated with water; RAW264.7: Cell line murine macrophages; ROS: Reactive oxygen species; TNF-α: Tumor necrosis factor.

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Project description:RNA interference (RNAi) has an unprecedented potential as a therapeutic strategy for reversibly silencing the expression of any gene. Therapeutic delivery of the RNAi mediator, i.e., small interfering RNA (siRNA), can be used to address diseases characterized by gene overexpression, for example inflammatory conditions like chronic obstructive pulmonary disease (COPD). Macrophages play a key role in COPD pathogenesis and are recruited to the airways and lung parenchyma, where they release proinflammatory cytokines, e.g., tumor necrosis factor-alpha (TNF-α). Hence, targeting TNF-α with siRNA is a promising therapeutic approach for COPD management. However, a safe and effective delivery system is required for delivery of TNF-α siRNA into the cytosol of hard-to-transfect macrophages. The purpose of this study was to optimize the intracellular delivery of TNF-α siRNA to the lipopolysaccharide-activated murine macrophage cell line RAW 264.7 using lipidoid-polymer hybrid nanoparticles (LPNs) composed of the lipid-like transfection agent lipidoid 5 (L5) and the biodegradable polymer poly (D,L-lactide-co-glycolide). Applying a quality-by-design approach, the influence of critical formulation variables, i.e., the L5 content and the L5:siRNA ratio (w/w), on critical quality attributes (CQAs) was investigated systematically using risk assessment and design of experiments, followed by delineation of an optimal operating space (OOS). The CQAs were identified based on the quality target product profile and included size, polydispersity index, zeta potential, encapsulation efficiency and loading for achieving efficient and safe TNF-α gene silencing in activated RAW 264.7 cells. Formulations inducing efficient gene silencing and low cytotoxicity were identified, and the optimal formulations displayed L5 contents of 15 and 20% (w/w), respectively, and an L5:siRNA weight ratio of 15:1. All tested formulations within the OOS mediated efficient and sequence-specific TNF-α gene silencing in RAW 264.7 cells at TNF-α-siRNA concentrations, which were significantly lower than the concentrations required of non-encapsulated TNF-α-siRNA, highlighting the benefit of the delivery system. The results also demonstrate that increasing the loading of siRNA into the delivery system does not necessarily imply enhanced gene silencing. This opens new avenues for further exploitation of LPNs as a robust platform technology for delivering TNF-α siRNA to macrophages, e.g., in the management of COPD.

Dataset Information

Diminishment of alpha-MSH anti-inflammatory activity in MC1r siRNA-transfected RAW264.7 macrophages.

Publications

Diminishment of alpha-MSH anti-inflammatory activity in MC1r siRNA-transfected RAW264.7 macrophages.

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