Monocytes/macrophages (MΦ), considered as plastic cells, can differentiate into either a pro-inflammatory (M1) subtype, also known as a classically activated subtype, or an anti-inflammatory ...alternatively activated subtype (M2) according to their microenvironment. Phenotypic markers of mouse polarized MΦ have been extensively studied, whereas their human counterparts remain less characterized. The main goal of this study was therefore to carefully characterize phenotypic and genomic markers of primary human MΦ generated from M-CSF-treated blood monocytes and polarized towards M1 or M2 subtype upon the action of lipopolysaccharide and interferon-γ (for M1) or interleukin (IL)-4 (for M2). Membrane expression of the markers CD80 and CD200R was found to be specific of human M1 and M2 polarized MΦ, respectively, whereas, by contrast, mannose receptor (CD206) expression did not discriminate between M1 and M2. mRNA expression analysis further identified six markers of M1 polarization (IL-12p35, CXCL10, CXCL11, CCL5, CCR7 and IDO1), five markers of M2 polarization (TGF-β, CCL14, CCL22, SR-B1 and PPARγ) and transcription factors involved in MΦ polarization. Ability of human M-CSF-generated MΦ to polarize toward M1 or M2 subtype was also associated with enhanced secretion of TNFα, IL-1β, IL-12p40, CXCL10 and IL-10 (for M1) or CCL22 (for M2). Moreover, the comparison of the expression of M1 markers in M-CSF- and GM-CSF-MΦ polarized towards M1 subtype has revealed similarities. In conclusion, we demonstrated that human M-CSF MΦ can polarize toward a M1 type after IFNγ/LPS stimulation. Moreover, the M1 and M2 markers of human polarized MΦ identified in the present study may be useful to better identify human MΦ subtypes, particularly at the tissue level, in order to better understand their respective roles in the development of pathologies.
Crystalline silica (cSiO
) is a mineral found in rocks; workers from the construction or denim industries are particularly exposed to cSiO
through inhalation. cSiO
inhalation increases the risk of ...silicosis and systemic autoimmune diseases. Inhaled cSiO
microparticles can reach the alveoli where they induce inflammation, cell death, auto-immunity and fibrosis but the specific molecular pathways involved in these cSiO
effects remain unclear. This systematic review aims to provide a comprehensive state of the art on omic approaches and exposure models used to study the effects of inhaled cSiO
in mice and rats and to highlight key results from omic data in rodents also validated in human.
The protocol of systematic review follows PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Eligible articles were identified in PubMed, Embase and Web of Science. The search strategy included original articles published after 1990 and written in English which included mouse or rat models exposed to cSiO
and utilized omic approaches to identify pathways modulated by cSiO
. Data were extracted and quality assessment was based on the SYRCLE's Risk of Bias tool for animal studies.
Rats and male rodents were the more used models while female rodents and autoimmune prone models were less studied. Exposure of animals were both acute and chronic and the timing of outcome measurement through omics approaches were homogeneously distributed. Transcriptomic techniques were more commonly performed while proteomic, metabolomic and single-cell omic methods were less utilized. Immunity and inflammation were the main domains modified by cSiO
exposure in lungs of mice and rats. Less than 20% of the results obtained in rodents were finally verified in humans.
Omic technics offer new insights on the effects of cSiO
exposure in mice and rats although the majority of data still need to be validated in humans. Autoimmune prone model should be better characterised and systemic effects of cSiO
need to be further studied to better understand cSiO
-induced autoimmunity. Single-cell omics should be performed to inform on pathological processes induced by cSiO
exposure.
Objective and design
To determine whether inflammatory hepatocytes may constitute primary targets for ruxolitinib, a Janus kinase (JAK) inhibitor, its effects towards expression of hepatic ...acute-phase proteins, especially C-reactive protein (CRP), were assessed.
Materials
Ruxolitinib effects were analysed in primary human hepatocytes and human hepatoma HepaRG cells exposed to various inflammatory stimuli.
Results
Ruxolitinib was found to fully inhibit lipopolysaccharide (LPS)-induced CRP secretion and mRNA expression, at concentrations (IC
50
= 12.9 nM) achievable in human blood. It similarly repressed CRP up-regulation due to several Toll-like receptor agonists or pro-inflammatory cytokines interleukin (IL) 1β, IL6 and tumour necrosis factor α and counteracted LPS-mediated induction of serum amyloid A, fibrinogen, haptoglobin and serpin. Ruxolitinib was additionally found to block the activation of the IL6/JAK/signal transducer and activator of transcription (STAT) pathway triggered by LPS and whose inhibition by the neutralizing anti-IL6 receptor antibody tocilizumab prevented CRP induction.
Conclusion
Ruxolitinib can potently repress induction of CRP in inflammatory human hepatocytes, most likely through targeting the IL6/JAK/STAT signalling cascade. Hepatic production of acute-phase proteins during liver inflammation may, therefore, constitute a target for ruxolitinib.
The tyrosine kinase inhibitor, Nintedanib (NTD), has been approved for the treatment of idiopathic pulmonary fibrosis (IPF). In cell-free systems, NTD was recently shown to inhibit kinase activity of ...the human recombinant colony-stimulating factor 1 (CSF1) receptor (CSF1R) which mediates major functions of pulmonary macrophages. In the present study, we have investigated the effects of NTD on the phenotype of human monocyte-derived macrophages controlled by CSF1 in order to identify its anti-inflammatory properties via CSF1R inhibition. NTD (0.01 to 1 μM) prevented the CSF1-induced phosphorylation of CSF1R and activation of the downstream signaling pathways. NTD, like the CSF1R inhibitor GW2580, significantly decreased the adhesion of macrophages and production of the chemokine ligand (CCL) 2. NTD also altered the polarization of macrophages to classical M1 and alternative M2a macrophages. It reduced the secretion of several pro-inflammatory and/or pro-fibrotic cytokines (IL-1β, IL-8, IL-10 and CXCL13) by M1 macrophages but did not prevent the expression of M1 markers. While NTD (50–200 nM) partially blocked the synthesis of M2a markers (CD11b, CD200R, CD206, and CD209), it did not reduce synthesis of the M2a pro-fibrotic cytokines CCL22 and PDGF-BB, and increased CCL18 release when used at its highest concentration (1 μM). The effects of NTD on macrophage polarization only was partially mimicked by GW2580, suggesting that the drug inhibits other molecules in addition to CSF1R. In conclusion, NTD alters the CSF1-controlled phenotype of human macrophages mainly by blocking the activation of CSF1R that thus constitutes a new molecular target of NTD, at least in vitro.
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•Nintedanib inhibits the activation of CSF1R in human macrophages.•Nintedanib reduces the adherence of human macrophages through CSF1R inhibition.•Nintedanib prevents CCL2 gene expression induced by CSF1 in M0 macrophages.•Nintedanib decreases the production of IL-1b and IL-8 in M1 macrophages.•Nintedanib reduces the expression of M2 markers.
Inhalation of crystalline silica (SiO
) is a risk factor of systemic autoimmune diseases such as systemic sclerosis (SSc) and fibrotic pulmonary disorders such as silicosis. A defect of apoptotic ...cell clearance (i.e., efferocytosis, a key process in the resolution of inflammation) is reported in macrophages from patients with fibrotic or autoimmune diseases. However, the precise links between SiO
exposure and efferocytosis impairment remain to be determined. Answering to this question may help to better link innate immunity and fibrosis. In this study, we first aim to determine whether SiO
might alter efferocytosis capacities of human and mouse macrophages. We secondly explore possible mechanisms explaining efferocytosis impairment, with a specific focus on macrophage polarization and on the RhoA/ROCK pathway, a key regulator of cytoskeleton remodeling and phagocytosis. Human monocyte-derived macrophages (MDM) and C57BL/6J mice exposed to SiO
and to CFSE-positive apoptotic Jurkat cells were analyzed by flow cytometry to determine their efferocytosis index (EI). The effects of ROCK inhibitors (Y27632 and Fasudil) on EI of SiO
-exposed MDM and MDM from SSc patients were evaluated
. Our results demonstrated that SiO
significantly decreased EI of human MDM
and mouse alveolar macrophages
. In human MDM, this SiO
-associated impairment of efferocytosis, required the expression of the membrane receptor SR-B1 and was associated with a decreased expression of M2 polarization markers (CD206, CD204, and CD163). F-actin staining, RhoA activation and impairment of efferocytosis, all induced by SiO
, were reversed by ROCK inhibitors. Moreover, the EI of MDM from SSc patients was similar to the EI of
- SiO
-exposed MDM and Y27632 significantly increased SSc MDM efferocytosis capacities, suggesting a likewise activation of the RhoA/ROCK pathway in SSc. Altogether, our results demonstrate that SiO
exposure may contribute to the impairment of efferocytosis capacities of mouse and human macrophages but also of MDM in SiO
-associated autoimmune diseases and fibrotic disorders such as SSc; in this context, the silica/RhoA/ROCK pathway may constitute a relevant therapeutic target.
Ruxolitinib is a Janus kinase (JAK) 1/2 inhibitor, currently used in the treatment of myeloproliferative neoplasms. It exerts potent anti-inflammatory activity, but the involved molecular and ...cellular mechanisms remain poorly understood. In order to gain insights about this point, ruxolitinib effects towards expression of main inflammatory cytokines were studied in human macrophages, which constitute a key-cell type implicated in inflammation. Analysis of mRNA expression of cytokines (n=84) by PCR array indicated that, among those induced by the pro-inflammatory stimulus lipopolysaccharide (LPS) (n=44), 61.4% (n=27) were repressed by 5μM ruxolitinib. The major inflammatory cytokines, interleukin (IL) 6 and tumor necrosis factor α, were notably down-regulated by ruxolitinib at both the mRNA and protein level. Other repressed cytokines included IL27 and the chemokines CCL2, CXCL9, CXCL10 and CXCL11, but not IL1β. The interferon (IFN) β/JAK/signal transducer and activator of transcription (STAT) pathway, well-activated by LPS in human macrophages as demonstrated by increased secretion of IFNβ, STAT1 phosphorylation, and up-regulation of reference IFNβ-responsive genes, was concomitantly blocked by the JAK inhibitor. Most of cytokines targeted by ruxolitinib were shown to be regulated by IFNβ in a JAK-sensitive manner. In addition, counteracting the IFNβ/JAK/STAT cascade using a blocking monoclonal antibody directed against IFNβ receptor resulted in a similar profile of cytokine repression to that observed in response to the JAK inhibitor. Overall, these data provide evidence for ruxolitinib-mediated repression of inflammatory cytokines in human macrophages through inhibition of the LPS/IFNβ/JAK/STAT signalling pathway, which probably contributes to the anti-inflammatory effects of the JAK inhibitor.
•The JAK inhibitor ruxolitinib represses cytokine induction in LPS-treated macrophages•Most of inflammatory cytokines targeted by ruxolitinib are regulated by IFNβ•Ruxolitinib impairs cytokine expression by inhibiting LPS/TLR4/IFNβ signaling pathway•Cytokine repression likely contributes to the anti-inflammatory effect of ruxolitinib
Lung diseases are aggravated by exposure to diesel exhaust particles (DEPs) found in air pollution. Macrophages are thought to play a crucial role in lung immune response to these pollutants, even if ...the mechanisms involved remain incompletely characterized. In the present study, we demonstrated that classically and alternative human macrophages (MΦ) exhibited increased secretion of PDGF-B in response to DEP extract (DEPe). This occurred via aryl hydrocarbon receptor (AhR)-activation because DEPe-induced PDGF-B overexpression was abrogated after AhR expression knock-down by RNA interference, in both M1 and M2 polarizing MΦ. In addition, TCDD and benzo(a)pyrene, two potent AhR ligands, also significantly increased mRNA expression of PDGF-B in M1 MΦ, whereas some weak ligands of AhR did not. We next evaluated the impact of conditioned media (CM) from MΦ culture exposed to DEPe or of recombinant PDGF-B onto lung fibroblast proliferation. The tyrosine kinase inhibitor, AG-1295, prevents phosphorylations of PDGF-Rβ, AKT and ERK1/2 and the proliferation of MRC-5 fibroblasts induced by recombinant PDGF-B and by CM from M1 polarizing MΦ, strongly suggesting that the PDGF-BB secreted by DEPe-exposed MΦ is sufficient to activate the PDGF-Rβ pathway of human lung fibroblasts. In conclusion, we demonstrated that human MΦ, whatever their polarization status, secrete PDGF-B in response to DEPe and that PDGF-B is a target gene of AhR. Therefore, induction of PDGF-B by DEP may participate in the deleterious effects towards human health triggered by such environmental urban contaminants.
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•PDGF-B expression and secretion are increased by DEPe exposure in human M1 and M2 MΦ.•DEPe-induced PDGF-B expression is aryl-hydrocarbon-dependent.•DEPe-exposed M1 MΦ secrete sufficient PDGF-B to increase lung fibroblast proliferation.
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