IL-1β Expression In Macrophages Research Articles

Identification and analysis of key microRNAs derived from osteoarthritis synovial fluid exosomes.

Identification and analysis of key microRNAs derived from osteoarthritis synovial fluid exosomes.

Follicle-Stimulating Hormone Provokes Macrophages to Secrete IL-1β Contributing to Atherosclerosis Progression.

Abnormally high follicle-stimulating hormone (FSH) has been reported to associate with cardiovascular diseases in prostate cancer patients with specific androgen deprivation therapy and in menopausal women. All of the cardiovascular diseases were involved in atherosclerosis. However, the pathogenic mechanism of FSH-associated atherosclerosis remains uncertain. Apolipoprotein E-deficient mice were chosen to develop atherosclerosis, of which the plaques were analyzed with administration of short- and long-term FSH imitating androgen deprivation therapy-induced and menopausal FSH elevation. The study showed that short- and long-term exposure of FSH significantly accelerated atherosclerosis progression in apolipoprotein E-deficient mice, manifested as strikingly increased plaques in the aorta and its roots, increased macrophage content, reduced fibrin, and an enlarged necrotic core, suggesting a decrease in plaque stability. Furthermore, expression profiles from the Gene Expression Omnibus GSE21545 dataset revealed that macrophage inflammation was tightly associated with FSH-induced atherosclerotic progression. The human monocyte cell line THP-1 was induced by PMA and worked as a macrophage model to detect inflammatory factors and cellular functions. FSH remarkably promoted the expression of IL-1β in macrophages and strikingly increased the chemotactic migratory capacity of macrophages toward MCP-1, but the promigratory capacity of FSH was attenuated in foam cells. Overall, we revealed that FSH significantly promoted the inflammatory response and migration of macrophages, thereby provoking atherosclerosis development.

Regulatory Effect of All-Trans Retinoic Acid on the Expression of IL-1β in Macrophages and the Mechanisms Involved

To investigate the regulatory effect of all-trans retinoic acid (ATRA) on the expression interleukin-1β (IL-1β) in macrophages and the mechanisms involved. Macrophages were treated with 1 μmol/L ATRA for 24 h before RNA-Sequence. Differentially expressed genes (DEGs) were screened out and analyzed by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, gene ontology (GO) functional analysis, and protein-protein interaction networks (PPI) analysis. After treatment with different doses of ATRA for 24 h, the expression of IL-1β was examined with qRT-PCR and Western blot. The activation of NF-κB signaling and caspase-1 was observed by Western blot and immunofluorescence staining. Compared with the blank control group, a total of 71 DEGs of macrophages were upregulated in the ATRA treatment group. KEGG analysis showed that the up-regulated DEGs were involved in IL-17 signaling pathway, tumor necrosis factor (TNF) signaling pathway, etc. GO analysis indicated that the up-regulated DEGs were involved in the biological processes of the production of IL-1β, response to lipopolysaccharide, etc. PPI analysis revealed that inflammatory cytokines, adhesion molecules, and chemokines were the key genes that ATRA acted on. In vitro experiments showed that ATRA promoted IL-1β expression in macrophages in a concentration-dependent manner. The expression of p-NF-κB, NF-κB, and caspase-1 were significantly increased by ATRA compared with those of the control group ( P<0.05), and p-NF-κB translocated to the cell nucleus in the ATRA group. ATRA may promote the expression of IL-1β by activating NF-κB signaling and caspase-1 in macrophages, this study may provide evidence for the immune regulatory function of ATRA on macrophages.

Macrophage IL-1β promotes arteriogenesis by autocrine STAT3- and NF-κB-mediated transcription of pro-angiogenic VEGF-A.

SUMMARYPeripheral artery disease (PAD) leads to considerable morbidity, yet strategies for therapeutic angiogenesis fall short of being impactful. Inflammatory macrophage subsets play an important role in orchestrating post-developmental angiogenesis, but the underlying mechanisms are unclear. Here, we find that macrophage VEGF-A expression is dependent upon the potent inflammatory cytokine, IL-1β. IL-1β promotes pro-angiogenic VEGF-A165a isoform transcription via activation and promoter binding of STAT3 and NF-κB, as demonstrated by gene-deletion, gain-of-function, inhibition, and chromatin immunoprecipitation assays. Conversely, IL-1β-deletion or inhibition of STAT3 or NF-κB increases anti-angiogenic VEGF-A165b isoform expression, indicating IL-1β signaling may also direct splice variant selection. In an experimental PAD model of acute limb ischemia, macrophage IL-1β expression is required for pro-angiogenic VEGF-A expression and for VEGF-A-induced blood flow recovery via angio- or arteriogenesis. Though further study is needed, macrophage IL-1β-dependent transcription of VEGF-A via STAT3 and NF-κB may have potential to therapeutically promote angiogenesis in the setting of PAD.

Macrophages activated by hepatitis B virus have distinct metabolic profiles and suppress the virus via IL-1β to downregulate PPARα and FOXO3.

SUMMARYMacrophages display phenotypic plasticity and can be induced by hepatitis B virus (HBV) to undergo either M1-like pro-inflammatory or M2-like anti-inflammatory polarization. Here, we report that M1-like macrophages stimulated by HBV exhibit a strong HBV-suppressive effect, which is diminished in M2-like macrophages. Tran-scriptomic analysis reveals that HBV induces the expression of interleukin-1β (IL-1β) in M1-like macrophages, which display a high oxidative phosphorylation (OXPHOS) activity distinct from that of conventional M1-like macrophages. Further analysis indicates that OXPHOS attenuates the expression of IL-1β, which suppresses the expression of peroxisome proliferator-activated receptor α (PPARα) and forkhead box O3 (FOXO3) in hepatocytes to suppress HBV gene expression and replication. Moreover, multiple HBV proteins can induce the expression of IL-1β in macrophages. Our results thus indicate that macrophages can respond to HBV by producing IL-1β to suppress HBV replication. However, HBV can also metabolically reprogram macrophages to enhance OXPHOS to minimize this host antiviral response.

Dec2 inhibits macrophage pyroptosis to promote periodontal homeostasis.

PurposeMacrophages play crucial roles as early responders to bacterial pathogens and promote/ or impede chronic inflammation in various tissues. Periodontal macrophage-induced pyroptosis results in physiological and pathological inflammatory responses. The transcription factor Dec2 is involved in regulating immune function and inflammatory processes. To characterize the potential unknown role of Dec2 in the innate immune system, we sought to elucidate the mechanism that may alleviate macrophage pyroptosis in periodontal inflammation.Methods Porphyromonas gingivalis lipopolysaccharide (LPS) was used to induce pyroptosis in RAW 264.7 macrophages. Subsequently, we established an LPS-stimulated Dec2 overexpression cellular model in macrophages. Human chronic periodontitis tissues were employed to evaluate potential changes in inflammatory marker expression and pyroptosis. Finally, the effects of Dec2 deficiency on inflammation and pyroptosis were characterized in a P. gingivalis-treated experimental periodontitis Dec2-knockout mouse model.ResultsMacrophages treated with LPS revealed significantly increased messenger RNA expression levels of Dec2 and interleukin (IL)-1β. Dec2 overexpression reduced IL-1β expression in macrophages treated with LPS. Overexpression of Dec2 also repressed the cleavage of gasdermin D (GSDMD), and the expression of caspase-11 was concurrently reduced in macrophages treated with LPS. Human chronic periodontitis tissues showed significantly higher gingival inflammation and pyroptosis-related protein expression than non-periodontitis tissues. In vivo, P. gingivalis-challenged mice exhibited a significant augmentation of F4/80, tumor necrosis factor-α, and IL-1β. Dec2 deficiency markedly induced GSDMD expression in the periodontal ligament of P. gingivalis-challenged mice.ConclusionsOur findings indicate that Dec2 deficiency exacerbated P. gingivalis LPS-induced periodontal inflammation and GSDMD-mediated pyroptosis. Collectively, our results present novel insights into the molecular functions of macrophage pyroptosis and document an unforeseen role of Dec2 in pyroptosis.

Conditioned Media from Ultrasound‐treated C2C12 Myotubes Regulate Macrophage Inflammatory Responses

Background Macrophages play important roles in innate immunity and regulate inflammatory responses. It is necessary to tightly regulate inflammation to avoid excessive tissue damage. Therefore, the therapeutic approaches to regulate the inflammatory responses of macrophages are essential to maintain cell functions. Skeletal muscle is the largest organ of the human body and releases anti-inflammatory/immune-modulatory factors. The facilitatory effects of ultrasound (US) on the release of extracellular vesicles (EVs) have been elucidated in cultured myotubes in our previous study. Purpose The aim of this study was to investigate the effects of EV-containing conditioned media from US-treated myotubes on inflammatory responses in macrophages. Methods Conditioned media from C2C12 myotubes with/without US irradiation were applied to murine bone marrow-derived macrophages for 1.5 hours. The mRNA expressions of pro- and anti-inflammatory factors were measured by quantitative real-time PCR. Results Conditioned media from both US-treated and untreated myotubes significantly suppressed the expression of IL-1β in macrophages without causing cell damage. US irradiation significantly increased the concentration level of EVs in conditioned media. In addition, the US-treated conditioned media decreased the expression levels of IL-1β and IL-6 by 23% and 28% compared to the US-untreated media, respectively. Furthermore, US treatment increased the expression level of Mgl, an anti-inflammatory marker, by 12% compared to US-untreated media. Discussion Ultrasound increased EV release from myotubes and fortified the anti-inflammatory effects of the conditioned media. These results suggest that ultrasound stimulation to myotubes could promote the anti-inflammatory effects via the enhancements in EV release. Conclusion Ultrasound-induced EVs in conditioned media from C2C12 myotubes could suppress the expression of the inflammatory factors in macrophages.

Presence of the house dust mite allergen in the gastrointestinal tract of dogs with chronic enteropathy: A potential inducer of interleukin-1β

House dust mite (HDM) is an environmental allergen ubiquitously present indoors, causing allergic inflammation in dogs. However, it is unclear whether HDM allergens can be detected in the gastrointestinal (GI) tract of dogs. In addition, although expression of interleukin (IL)-1β is increased in the intestinal mucosa of dogs with chronic enteropathy (CE), the role of HDM allergens in the production of IL-1β has not been evaluated. The objectives of this study were to determine the presence of HDM allergens in the GI tract of dogs and to elucidate the effect of HDM on IL-1β expression in canine macrophages. HDM allergen, Dermatophagoides pteronyssinus (Der p) 1, was quantified in the gastric and duodenal fluids and the duodenal and colonic mucosae of dogs with CE and healthy laboratory dogs, and faeces of dogs with CE, healthy laboratory dogs and healthy client-owned dogs. Gene expression and protein levels of IL-1β were measured in HDM-stimulated canine peripheral macrophages from healthy laboratory dogs. Der p 1 was detected in the gastric and duodenal fluids of dogs with CE and healthy laboratory dogs, and faeces of all dogs examined. Der p 1 levels in the duodenal and colonic mucosae were significantly higher in dogs with CE than in healthy laboratory dogs. HDM increased both gene expression and protein levels of IL-1β in canine macrophages. These findings demonstrate the presence of HDM allergens in the GI tract of dogs and the possible involvement of HDM allergens in the pathogenesis of CE by promoting IL-1β expression in macrophages.

HDAC6 inhibitor accelerates wound healing by inhibiting tubulin mediated IL-1β secretion in diabetic mice

Delayed wound healing in diabetes is characterized by sustained activation of inflammasome and increased expression of IL-1β in macrophages. Identification and validation of novel pathways to regulate IL-1β expression will provide therapeutic targets for diabetic wounds. Here we report sustained over-expression of histone deacetylase 6 (HDAC6) in wounds of diabetic mice and its role in delayed wound healing. Topical application of HDAC6 inhibitor; Tubastatin A (TSA) gel promoted the wound healing in diabetic mice. TSA hydrogel reduced the infiltration of neutrophils, T-cells and macrophages in the early phase of wound healing. TSA treatment promoted the wound healing by inducing collagen deposition, angiogenesis (CD31) and fibrotic factors (TGF-β1) in the late phase of healing. Protein analysis of the diabetic wounds treated with TSA showed increased acetylated α-tubulin and decreased levels of mature IL-1β with no significant effect on the expression of pro-IL-1β, pro-caspase-1 and active caspase-1. In in vitro assays, macrophages exhibited upregulation of HDAC6, IL-1β and downregulation of IL-10 upon stimulation with high glucose and LPS. TSA inhibited the IL-1β secretion and promoted IL-10 in stimulated macrophages with high glucose and LPS. Further investigations showed that TSA inhibits IL-1β release by inhibiting tubulin dependent lysosomal exocytosis without affecting its transcription and maturation. Nocodazole (known acetylation inhibitor) pre-treatment inhibited TSA effect on IL-1β secretion in high glucose stimulated macrophages. Overall, our findings indicate that sustained HDAC6 expression in diabetic wounds contributes to impaired healing responses and HDAC6 may represent a new therapeutic target for diabetic wounds.

Decreased Jagged1 expression in vascular smooth muscle cells delays endothelial regeneration in arteriovenous graft.

It is well-established that endothelial dysfunction promotes activation of vascular smooth muscle cell (VSMC). Whether decreased accumulation of VSMCs affects endothelial regeneration and functions in arteriovenous graft (AVG) remodelling has not been studied. We sought to identify mechanisms by which the Notch ligand, Jagged1, in VSMCs regulates endothelial cell (EC) functions in AVGs. AVGs were created in transgenic mice bearing VSMC-specific knockout (KO) or overexpression of Jagged1. VSMC migration, EC regeneration, and its barrier functions as well as AVG remodelling were evaluated. Jagged1 expression was induced in VSMCs of neointima in the AVGs. Jagged1 KO in VSMCs inhibited the accumulation of extracellular matrix as well as VSMC migration. Fewer α-SMA-positive VSMCs were found in AVGs created in VSMC-specific Jagged1 KO mice (VSMCJagged1 KO mice) vs. in WT mice. Decreased VSMCs in AVGs were associated with deterioration of EC functions. In AVGs created in transgenic mice bearing Jagged1 KO in VSMCs exhibited delayed EC regeneration and impaired EC barrier function. Barrier dysfunction of ECs increased inflammatory cell infiltration and dysregulation of AVG remodelling and arterialization. The increased expression of IL-1β in macrophages was associated with expression of adhesion markers in ECs in AVGs created in VSMCJagged1 KO mice. In contrast, AVGs created in mice with overexpression of Jagged1 in VSMCs exhibited improved EC regeneration plus decreased macrophage infiltration. This led to AVG remodelling and arterialization. In co-cultures of ECs and VSMCs, Jagged1 deficiency in VSMCs suppressed N-cadherin and integrin β3 expression in ECs. Inhibition of integrin β3 activation delayed EC spreading and migration. Notably, Jagged1 overexpression in VSMCs or treatment with recombinant Jagged1 stimulated the expression of N-cadherin and integrin β3 in ECs. Jagged1-induced responses were blocked by inhibition of Notch signalling. Jagged1 expression in VSMCs maintains EC barrier functions and blocks infiltration of macrophages. These responses promote remodelling and arterialization of AVGs.

Legumain-deficient macrophages promote senescence of tumor cells by sustaining JAK1/STAT1 activation.

Macrophages serve as the first line of communication between tumors and the rest of the immune system, and understanding the interplay between macrophage and tumor cells is essential for developing novel macrophage-based strategy against tumor. Here, we show that deletion of legumain in macrophages activates senescence of tumor cells. Macrophage derived IL-1β mediates the pro-senescent effect of Lgmn-/- macrophages since blockage of IL-1β reverses the senescence phenotype in both a coculture model of macrophage and tumor cells and an orthotopic mouse model of breast cancer. Sustained activation of JAK1/STAT1 signaling and increased iNOS were found in the tumor cell-cocultured Lgmn-/- macrophages, which were necessary for IL-1β expression and secretion. Applying a specific STAT1 agonist mimics the inductive effect of legumain deletion on IL-1β expression in macrophages, and the effect can be blocked via inhibition of iNOS. Legumain and integrin αvβ3 interact to prevent STAT1 signaling in macrophages, and blockage of integrin αvβ3 stimulates STAT1 activation. Therapeutically, transplantation of bone marrow from Lgmn-/- mice suppresses the malignant growth of tumor by upregulating tumor cell senescence. Therefore, our finding highlights legumain in macrophages as a potential therapeutic target for tumors.

Abstract 215: Rac-Signaling as a Critical Determinant of IL-1beta-Dependent Atherosclerotic Calcification

Coronary artery disease caused by atherosclerosis is the leading cause of morbidity and mortality in the world. Calcification of atherosclerotic plaque has predictive value in terms of cardiovascular event risk and mortality. Plaque calcium composition appears critical to determining cardiovascular risk; microcalcification has been associated with more vulnerable plaque phenotypes, while somewhat paradoxically, densely calcified plaque is associated with more stable disease. Inflammation can influence calcification of plaque, but immune modulators of plaque calcification are minimally defined. Rac1 and Rac2 are small GTPases that influence cytokine expression in plaque macrophages. We have defined a Rac-based signaling mechanism that regulates macrophage IL-1β expression. Using an atherosclerotic-prone mouse model, we identified that progressive calcification depends on altered Rac expression and activation (GTP-binding) through consequent effects on macrophage IL-1β production and IL-1R signaling. IL-1β production and its downstream signaling were critical determinants of atherosclerotic plaque calcification. In short, Rac2 expression determined the degree of Rac1 GTP-binding, acting as a brake on Rac1-dependent IL-1β production, whereas macrophage IL-1β production and atherosclerotic calcification depended on myeloid Rac1. Therapeutic inhibition of macrophage Rac-mediated IL-1β expression has the potential to be a treatment strategy for progressive, inflammatory atherosclerotic calcification.

Nutritionally relevant concentrations of resveratrol and hydroxytyrosol mitigate oxidative burst of human granulocytes and monocytes and the production of pro-inflammatory mediators in LPS-stimulated RAW 264.7 macrophages

The health benefits of bio-active phenolic compounds have been largely investigated in vitro at concentrations which exceed those reachable in vivo. We investigated and compared the anti-inflammatory effects of resveratrol, hydroxytyrosol and oleuropein at physiologically relevant concentrations by using in vitro models of inflammation.Human granulocytes and monocytes were stimulated with phorbol myristate acetate (PMA) and the ability of resveratrol, hydroxytyrosol and oleuropein to inhibit the oxidative burst and CD11b expression was measured. Nitric oxide (NO), prostaglandin E2 (PGE2) levels, COX-2, iNOS, TNFα, IL-1β and miR-146a expression and activation of the transcription factor Nrf2 were evaluated in macrophages RAW 264.7 stimulated with LPS (1μg/ml) for 18h, exposed to resveratrol, hydroxytyrosol and oleuropein (5 and 10μM). Synergistic effects were explored as well, together with the levels of PGE2, COX-2 and IL-1β expression in macrophages after 6h of LPS stimulation. PGE2 and COX-2 expression were also assessed on human monocytes.All the tested compounds inhibited granulocytes oxidative burst in a concentration dependent manner and CD11b expression was also significantly counteracted by resveratrol and hydroxytyrosol. The measurement of oxidative burst in human monocytes produced similar effects being resveratrol more active. Hydroxytyrosol and resveratrol inhibited the production of NO and PGE2 but did not reduce iNOS, TNFα or IL-1β gene expression in LPS-stimulated RAW 264.7 for 18h. Resveratrol slightly decreased COX-2 expression after 18h but not after 6h, but reduced PGE2 levels after 6h. Resveratrol and hydroxytyrosol 10μM induced NRf2 nuclear translocation and reduced miR-146a expression in LPS treated RAW 264.7.Overall, we reported an anti-inflammatory effect of resveratrol and hydroxytyrosol at low, nutritionally relevant concentrations, involving the inhibition of granulocytes and monocytes activation, the modulation of miR-146a expression and the activation of Nrf2. A regular dietary intake of resveratrol and hydroxytyrosol may be a useful complementary strategy to control inflammatory diseases.

TSC1 controls IL-1β expression in macrophages via mTORC1-dependent C/EBPβ pathway.

The tuberous sclerosis complex 1 (TSC1) is a tumor suppressor that inhibits the mammalian target of rapamycin (mTOR), which serves as a key regulator of inflammatory responses after bacterial stimulation in monocytes, macrophages, and primary dendritic cells. Previous studies have shown that TSC1 knockout (KO) macrophages produced increased inflammatory responses including tumor necrosis factor-α (TNF-α) and IL-12 to pro-inflammatory stimuli, but whether and how TSC1 regulates pro-IL-1β expression remains unclear. Here using a mouse model in which myeloid lineage-specific deletion of TSC1 leads to constitutive mTORC1 activation, we found that TSC1 deficiency resulted in impaired expression of pro-IL-1β in macrophages following lipopolysaccharide stimulation. Such decreased pro-IL-1β expression in TSC1 KO macrophages was rescued by reducing mTORC1 activity with rapamycin or deletion of mTOR. Rictor deficiency has no detectable effect on pro-IL-1β synthesis, suggesting that TSC1 positively controls pro-IL-1β expression through mTORC1 pathway. Moreover, mechanism studies suggest that mTORC1-mediated downregulation of the CCAAT enhancer-binding protein (C/EBPβ) critically contributes to the defective pro-IL-1β expression. Overall, these findings highlight a critical role of TSC1 in regulating innate immunity by control of the mTOR1-C/EBPβ pathway.

Abstract 142: Rac2 Modulates Macrophage IL-1β Production, Atherosclerotic Plaque Inflammation, and Calcific Atherosclerosis

Ischemic heart disease caused by atherosclerosis is the leading cause of morbidity and mortality in the world. Calcification of atherosclerotic plaques is a well-described pathologic finding that has predictive value in terms of atherosclerotic burden, cardiovascular event risk, and mortality. Inflammation is critical to atherogenesis, but inflammatory mechanisms that drive atherosclerotic calcification are minimally understood. The Rho/Rac family of low molecular weight GTPases regulates the activation, recruitment, and differentiation of monocytes. Racs compete for similar regulatory elements, indicating that targeted modulation of specific family members may influence the role of other members in biologic processes. The hypothesis is that Rac2 can modulate atherosclerotic plaque inflammation and calcium composition via consequent effects on the activation of Rac1. Rac2 gene deletion results in elevated activation (GTP-binding) of Rac1 in macrophages. Increased activation of Rac1 is associated with higher macrophage IL-1β production in response to LPS-coupled cholesterol crystal exposure. In fact, macrophage IL-1β production is dependent on Rac1. When subjected to a high fat diet for 14 weeks, Rac2 -/-ApoE -/- mice demonstrate similar weight gain, serum cholesterol levels, circulating inflammatory monocyte levels, and aortic atherosclerotic lipid burden relative to Rac2 +/+ApoE -/- mice. Atherosclerotic plaques from Rac2 -/-ApoE -/- mice contain increased inflammatory cellular infiltration by histology and relative RNA expression. Ex vivo microCT imaging reveals calcified aortic plaques, and quantification of calcification by near-infrared imaging demonstrates increased calcium composition in plaques from Rac2 -/-ApoE -/- mice relative to Rac2 +/+ApoE -/- mice. Calcified aortic plaques are associated with an increase in IL-1β mRNA expression in the aortic tissue. In summary, Rac2 is a critical modulator of signaling mechanisms that regulate the activation state of Rac1, resulting in enhanced macrophage IL-1β expression in vitro and inflammatory calcification of atherosclerotic plaques in vivo. Targeting the balance of Rac regulation has therapeutic potential in modulation of atherosclerotic plaque composition.

FANCA and FANCC modulate TLR and p38 MAPK–dependent expression of IL-1β in macrophages

AbstractHematopoietic stem and progenitor cells with inactivated Fanconi anemia (FA) genes, FANCA and FANCC, are hypersensitive to inflammatory cytokines. One of these, tumor necrosis factor α (TNF-α), is also overproduced by FA mononuclear phagocytes in response to certain Toll-like receptor (TLR) agonists, creating an autoinhibitory loop that may contribute to the pathogenesis of progressive bone marrow (BM) failure and selection of TNF-α–resistant leukemic stem cell clones. In macrophages, the TNF-α overproduction phenotype depends on p38 mitogen-activated protein kinase (MAPK), an enzyme also known to induce expression of other inflammatory cytokines, including interleukin 1β (IL-1β). Reasoning that IL-1β might be involved in a like autoinhibitory loop, we determined that (1) TLR activation of FANCA- and FANCC-deficient macrophages induced overproduction of both TNF-α and IL-1β in a p38-dependent manner; (2) exposure of Fancc-deficient BM progenitors to IL-1β potently suppressed the expansion of multipotent progenitor cells in vitro; and (3) although TNF-α overexpression in FA cells is controlled posttranscriptionally by the p38 substrate MAPKAPK-2, p38-dependent overproduction of IL-1β is controlled transcriptionally. We suggest that multiple inflammatory cytokines overproduced by FANCA- and FANCC-deficient mononuclear phagocytes may contribute to the progressive BM failure that characterizes FA, and that to achieve suppression of this proinflammatory state, p38 is a more promising molecular therapeutic target than either IL-1β or TNF-α alone.

Macrophages play a unique role in the plaque calcification by enhancing the osteogenic signals exerted by vascular smooth muscle cells

Vascular calcification is a major risk factor for the cardiovascular disease, yet its underlying molecular mechanisms remain to be elucidated. Recently, we identified that osteogenic signals via bone morphogenetic protein (BMP)-2 exerted by vascular smooth muscle cells (VSMCs) play a crucial role in the formation of atherosclerotic plaque calcification. Here we report a synergistic interaction between macrophages and VSMCs with respect to plaque calcification. Treatment with conditioned medium (CM) of macrophages dramatically enhanced BMP-2 expression in VSMCs, while it substantially reduced the expression of matrix Gla-protein (MGP) that inhibits the BMP-2 osteogenic signaling. As a result, macrophages significantly accelerated the osteoblastic differentiation of C2C12 cells induced by VSMC-CM. In contrast, macrophage-CM did not enhance the osteoblastic gene expressions in VSMCs, indicating that macrophages unlikely induced the osteoblastic trans-differentiation of VSMCs. We then examined the effect of recombinant TNF-α and IL-1β on the VSMC-derived osteogenic signals. Similar to the macrophage-CM, both cytokines enhanced BMP-2 expression and reduced MGP expression in VSMCs. Nevertheless, only the neutralization of TNF-α but not IL-1β attenuated the effect of macrophage-CM on the expression of these genes in VSMCs, due to the very low concentration of IL-1β in the macrophage-CM. On the other hand, VSMCs significantly enhanced IL-1β expression in macrophages, which might in turn accelerate the VSMC-mediated osteogenic signals. Together, we identified a unique role of macrophages in the formation of plaque calcification in coordination with VSMCs. This interaction between macrophages and VSMCs is a potential therapeutic target to treat and prevent the atherosclerotic plaque calcification.

Bone morphogenetic protein 6-induced interleukin-1β expression in macrophages requires PU.1/Smad1 interaction

Interleukin 1β (IL-1β) is a pro-inflammatory cytokine secreted by activated macrophages and monocytes. Previously, we have reported that bone morphogenetic protein-6 (BMP-6) induces inducible nitric oxide synthase (iNOS) expression via IL-1β in macrophages. In the present study, we demonstrate that BMP-6 increases IL-1β expression in macrophages via the receptors ALK3 and BMPRII as well as the downstream signaling protein Smad1. Surprisingly though, inhibition of the ERK and JNK non-Smad pathways also completely blocked the induction of IL-1β by BMP-6 in macrophages. Further analysis revealed that a physical interaction between the transcription factor PU.1 and Smad 1 is necessary for the upregulation of IL-1β expression by BMP-6 in macrophages. Taken together, these results demonstrate that BMP-6-induced IL-1β expression in macrophages is mediated via a cross-talk between the Smad and the non-Smad pathways through Smad1 and PU.1.

Inter-strain differences in glucocorticoid and mineralocorticoid effects on macrophage and lymphocyte functions in mice

We showed previously and we confirm here that macrophages from three mouse strains are differentially sensitive to the inhibition of expression of key inflammatory proteins (iNOS-II, IL-1β) by dexamethasone, a specific glucocorticoid receptor agonist (C57BL/6 > DBA/2 > BALB/c). Here we show that aldosterone (a specific mineralocorticoid agonist) has no effect on iNOS-II or IL-1β expression in macrophages from these mouse strains but decreases IL-1ra expression, with small inter-strain differences. This mechanism may be involved in the pro-inflammatory effect of this hormone. Concanavalin A-stimulated lymphocytes proliferation is also differentially sensitive to dexamethasone according to the strain, but insensitive to aldosterone.

Facilitating action of asiaticoside at low doses on burn wound repair and its mechanism

Some reports published from 1967 to 1999 describe the use of ointments containing high doses (0.1 to 0.2%, w/w) C. asiataica herb extracts to enhance wound repair. Lower doses at which burn wound repair is enhanced by such topical applications have not been established yet. We found that the application of asiaticoside at low doses of 10−8 to 10−12% (w/w) facilitated burn wound repair. To clarify the accelerating mechanisms of asiaticoside on burn wound repair, we examined the effects of asiaticoside on the levels of various cytokines produced at the site of the burn wound. The topical application of a low dose (10 pg, 1 ng, or 100 ng/wound area) of asiaticoside increased monocyte chemoattractant protein-1 (MCP-1), vascular endothelial growth factor (VEGF), and interleukin (IL)-1β levels in burn wound exudates. Asiaticoside (10 pg to 100 ng/ml) enhanced MCP-1 production in HaCaT cells, but it had no direct effect on VEGF production. Furthermore, asiaticoside (10 pg to 100 ng/ml) increased the IL-1β production in THP-1 macrophages with MCP-1, but it had no effect on IL-1β production without MCP-1 or with lipopolysaccharide (LPS). These findings suggest that the enhancement of burn wound healing by asiaticoside might be due to the promotion of angiogenesis during skin wound repair as a result of the stimulation of VEGF production caused by the increase in MCP-1 expression in keratinocytes and the increase in IL-1β expression in macrophages induced cooperatively by asiaticoside plus MCP-1.