Gaudichaudione H Inhibits Inflammatory Responses in Macrophages and Dextran Sodium Sulfate-Induced Colitis in Mice.
ABSTRACT: Macrophages-involved inflammation is considered to induce the damage in various diseases. Herein, novel therapeutics inhibiting over-activation of macrophages could prove an effective strategy to prevent inflammation-related diseases. Gaudichaudione H (GH), which is a natural small molecular compound isolated from Garcinia oligantha Merr. (Clusiaceae) has previously been demonstrated its anti-cancer effects on several cancer cell lines. However, no report has been published about the anti-inflammatory effect of GH to date. This study aims to examine the anti-inflammatory effects and potential molecular mechanism of GH, and provide new insights toward the treatment of inflammation. GH inhibited nitric oxide (NO) production, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression, cytokine interleukin-6 (IL-6) and tumor necrosis factor-? (TNF-?) production, and messenger RNA (mRNA) expression to attenuate inflammatory responses in lipopolysaccharide (LPS)-induced RAW 264.7 cells or stimulated bone marrow-derived macrophages (BMDMs). GH inhibited nuclear factor-?B (NF-?B) and mitogen-activated protein kinase (MAPK) pathways, the nuclear translocation of transcription factors NF-?B and activator protein 1 (AP-1), as well as upstream signaling of the toll-like receptor 4 (TLR4)-myeloid differentiation primary response 88 (MyD88) pathway in stimulated macrophages. Furthermore, the result of the intracellular signaling array showed that the phosphorylation of adenosine 5'-monophosphate-activated protein kinase-? (AMPK?), proline-rich Akt substrate of 40 kDa (PRAS40), and p38 could be down regulated by GH in BMDMs, indicating that the mechanism by which GH inhibited inflammation may be also associated with the energy metabolism pathway, PRAS40-mediated NF-?B pathway, cell proliferation, apoptosis, and autophagy, etc. In addition, GH alleviated dextran sodium sulfate (DSS)-induced colitis in mice by ameliorating weight loss, stool consistency change, blood in the stool, and colon shortening. GH decreased the protein and mRNA levels of IL-6 and TNF-?, iNOS and COX-2 mRNA expression, the activation of NF-?B and MAPK pathways, the phosphorylation of AMPK? and PRAS40, histological damage, and infiltration of macrophages in the colons of mice with DSS-induced colitis. Taken together, our results support that GH exerts the anti-inflammatory effects in macrophages in vitro through regulation of NF-?B and MAPK pathways, and DSS-induced colitis mouse model in vivo. These findings suggest that GH may be a promising candidate in treating macrophage-related inflammatory disease.
Project description:Superoxide dismutase 1 (SOD1) binds copper and zinc ions and is one of three superoxide dismutases responsible for destroying free superoxide radicals in the body. Reactive oxygen species (ROS), including free superoxide radicals, play important roles in colitis. However, the role of SOD1 in oxidative stress under colitis remains unclear. Here, we examined the role of SOD1 in the DSS-induced mouse model of colitis. SOD1 deficiency resulted in severe oxidative stress with body weight loss, epithelial barrier disruption and decreased antioxidant enzyme activities. The levels of neutrophils, monocytes, pro-inflammatory CD11c+ macrophages and CD11b+CD103- dendritic cells (DCs) were increased, while anti-inflammatory CD206+ macrophages and CD11b-CD103+ DCs were decreased, in DSS-treated SOD1-knockout (KO) mice compared to DSS-treated wild-type mice. Furthermore, rescue of SOD activity in SOD1-KO mice by oral gavage of B. amyloliquefaciens SOD (BA SOD) significantly ameliorated enhanced DSS-induced colitis in these mice by suppressing p38-MAPK/NF-?B signaling, which can induce inflammation and apoptosis. Taken together, our results suggest that SOD1-mediated inhibitory responses play a crucial role in limiting the development of DSS-induced colitis, and that BA SOD is a promising candidate for treating colitis.
Project description:We investigated the role of the PI3K p85? subunit in the development of acute colitis with a focus on intestinal macrophages. Experimental acute colitis was induced using 3% dextran sulfate sodium (DSS) in drinking water for 7 days. The severity of DSS-induced acute colitis was significantly attenuated in p85? hetero-deficient (p85?+/-) mice compared with WT mice. The expression of proinflammatory mediators in intestinal macrophages isolated from the inflamed colonic mucosa was significantly suppressed in p85?+/- colitis mice compared with WT colitis mice. Interestingly, we found that bone marrow-derived macrophages (BMDMs) from p85?+/- mice produced a significantly higher amount of IL-10 than BMDMs from WT mice. The adoptive transfer of p85?+/- BMDMs, but not WT BMDMs, significantly improved the severity in WT colitis mice, and this effect was reversed by anti-IL-10 antibody. Furthermore, the expression of IL-10 in the intestinal macrophages of p85?+/- normal colonic mucosa was significantly higher than that in the intestinal macrophages of WT normal colonic mucosa. The present results demonstrate that p85?+/- mice exhibit a reduced susceptibility to DSS-induced acute colitis. Our study suggests that a deficiency of PI3K p85? enhances the production of IL-10 in intestinal macrophages, thereby suppressing the development of DSS-induced acute colitis.
Project description:Macrophages regulate innate immunity to maintain intestinal homeostasis and play pathological roles in intestinal inflammation. Activation of the epidermal growth factor receptor (EGFR) promotes cellular proliferation, differentiation, survival, and wound closure in several cell types. However, the impact of EGFR in macrophages remains unclear. This study was to investigate whether EGFR activation in macrophages regulates cytokine production and intestinal inflammation. We found that EGFR was activated in colonic macrophages in mice with dextran sulfate sodium (DSS)-induced colitis and in patients with ulcerative colitis. DSS-induced acute colitis was ameliorated, and recovery from colitis was promoted in Egfr(fl/fl)LysM-Cre mice with myeloid cell-specific deletion of EGFR, compared with LysM-Cre mice. DSS treatment increased IL-10 and TNF levels during the acute phase of colitis, and increased IL-10 but reduced TNF levels during the recovery phase in Egfr(fl/fl)LysM-Cre mice. An anti-IL-10 neutralizing Ab abolished these effects of macrophage-specific EGFR deletion on DSS-induced colitis in Egfr(fl/fl)LysM-Cre mice. LPS stimulated EGFR activation and inhibition of EGFR kinase activity enhanced LPS-stimulated NF-?B activation in RAW 264.7 macrophages. Furthermore, induction of IL-10 production by EGFR kinase-blocked RAW 264.7 cells, in response to LPS plus IFN-?, correlated with decreased TNF production. Thus, although selective deletion of EGFR in macrophages leads to increases in both pro- and anti-inflammatory cytokines in response to inflammatory stimuli, the increase in the IL-10 level plays a role in suppressing proinflammatory cytokine production, resulting in protection of mice from intestinal inflammation. These results reveal an integrated response of macrophages regulated by EGFR in intestinal inflammatory disorders.
Project description:S100A4 plays important roles in tumor development and metastasis, but its role in regulating inflammation and colitis-associated tumorigenesis has not been well characterized. Here, we report that S100A4 expression was increased in azoxymethane (AOM) and dextran sulfate sodium (DSS) induced colorectal cancer (CRC) in mice. After AOM/DSS treatment, both S100A4-TK mice with the selective depletion of S100A4-expressing cells and S100A4-deficient (S100A4-/-) mice developed fewer and smaller tumors than wild-type (WT) control littermates. Furthermore, S100A4-/- mice were resistant to DSS-induced colitis, reduced infiltration of macrophages, and the diminished production of proinflammatory cytokines. Further studies revealed that reduced colon inflammation and colorectal tumor development in S100A4-/- mice were partly due to the dampening of nuclear factor (NF)-?B activation in macrophages. Furthermore, the administration of a neutralizing S100A4 antibody to WT mice significantly decreased AOM/DSS-induced colon inflammation and tumorigenesis. These results indicate that S100A4 amplifies an inflammatory microenvironment that promotes colon tumorigenesis and provides a promising therapeutic strategy for treatment of inflammatory bowel disease and prevention of colitis-associated colorectal carcinogenesis.
Project description:NLRP3 inflammasome is a novel therapeutic target for inflammatory bowel disease (IBD). The aim of this study was to investigate the anti-inflammatory effect of a bioactive flavonoid-oroxylin A on the treatment of dextran sulfate sodium (DSS)-induced murine colitis via targeting NLRP3 inflammasome. In this study, we found that oroxylin A attenuated experimental colitis in mice, including loss of body weights, shortening of the colon lengths and infiltration of inflammatory cells. The production of IL-1?, IL-6 and TNF-? in colon was also markedly reduced by oroxylin A. Moreover, oroxylin A significantly decreased the expression of NLRP3 in intestinal mucosal tissue. In addition, NLRP3-/- mice were observably protected from DSS-induced acute colitis, and oroxylin A treatment had no effects on attenuating inflammation in NLRP3-/- mice. Further study found that the activation of NLRP3 inflammasome was dose-dependently inhibited by oroxylin A in both THP-Ms and BMDMs, followed by decrease in the cleavage of caspase-1 and secretion of IL-1?. This inhibitory effect of oroxylin A was due to restraint of the NLRP3 protein expression and the inflammasome formation in macrophages. Furthermore, the reduction of NLRP3 protein expression by oroxylin A was dependent on the inhibition of NF-?B p65 expression and nuclear translocation. Besides, oroxylin A directly suppressed the ASC speck formation and the inflammasome assembly which in turn restrained the activation of NLRP3 inflammasome. Our findings demonstrated that oroxylin A inhibited NLRP3 inflammasome activation and could potentially be used for the treatment of IBD.
Project description:In inflammatory bowel diseases (IBDs), particularly ulcerative colitis, intestinal macrophages (M?s), eosinophils, and the eosinophil-selective chemokine CCL11, have been associated with disease pathogenesis. M?s, a source of CCL11, have been reported to be of a mixed classical (NF-?B-mediated) and alternatively activated (STAT-6-mediated) phenotype. The importance of NF-?B and STAT-6 pathways to the intestinal M?/CCL11 response and eosinophilic inflammation in the histopathology of experimental colitis is not yet understood. Our gene array analyses demonstrated elevated STAT-6- and NF-?B-dependent genes in pediatric ulcerative colitis colonic biopsies. Dextran sodium sulfate (DSS) exposure induced STAT-6 and NF-?B activation in mouse intestinal F4/80(+)CD11b(+)Ly6C(hi) (inflammatory) M?s. DSS-induced CCL11 expression, eosinophilic inflammation, and histopathology were attenuated in RelA/p65(?mye) mice, but not in the absence of STAT-6. Deletion of p65 in myeloid cells did not affect inflammatory M? recruitment or alter apoptosis, but did attenuate LPS-induced cytokine production (IL-6) and Ccl11 expression in purified F4/80(+)CD11b(+)Ly6C(hi) inflammatory M?s. Molecular and cellular analyses revealed a link between expression of calprotectin (S100a8/S100a9), Ccl11 expression, and eosinophil numbers in the DSS-treated colon. In vitro studies of bone marrow-derived M?s showed calprotectin-induced CCL11 production via a p65-dependent mechanism. Our results indicate that myeloid cell-specific NF-?B-dependent pathways play an unexpected role in CCL11 expression and maintenance of eosinophilic inflammation in experimental colitis. These data indicate that targeting myeloid cells and NF-?B-dependent pathways may be of therapeutic benefit for the treatment of eosinophilic inflammation and histopathology in IBD.
Project description:Innate and adaptive immune responses are regulated by cross talk between activation and inhibitory signals. Dysregulation of the inhibitory signal can lead to aberrant chronic inflammatory diseases such as the inflammatory bowel diseases (IBD). Little is known about negative regulation of innate intestinal immune activation. We examined the role of the inhibitory receptor paired immunoglobulin-like receptor B (PIR-B) in the regulation of macrophage function in innate intestinal immunity.We examined the susceptibility of Pirb-/- and wild-type (WT) mice to dextran sodium sulfate (DSS)-induced colitis. We assessed proinflammatory cytokine release and mitogen-activated protein kinase (MAPK) and nuclear factor kappaB (NF-kappaB) activation in Pirb-/- and WT macrophages following Escherichia coli stimulation. Macrophage transfer experiments were performed to define the role of PIR-B in the negative regulation of macrophage function in DSS-induced colitis. We also assessed expression of PIR-B human homologues (immunoglobulin-like transcript [ILT]-2 and ILT-3) in colon biopsy samples from healthy individuals (controls) and patients with IBD.Pirb-/- mice had increased susceptibility to DSS-induced colitis. In vitro analysis showed increased production of proinflammatory cytokines (interleukin-6, interleukin-1beta, and tumor necrosis factor alpha) and activation of MAPK and NF-kappaB in Pirb-/- macrophages following bacterial activation. Adoptive transfer of bone marrow-derived Pirb-/- macrophages into WT mice was sufficient to increase disease susceptibility. ILT-2 and ILT-3 were expressed on CD68+ and CD68- mononuclear cells and intestinal epithelium in colon biopsy samples from patients and controls.PIR-B negatively regulates macrophage functions in response to pathogenic bacteria and chronic intestinal inflammatory responses. Inhibitory receptors such as PIR-B might be used as therapeutic targets for treatment of patients with IBD.
Project description:To prevent excessive inflammatory responses to commensal microbes, intestinal macrophages, unlike their systemic counterparts, do not produce inflammatory cytokines in response to enteric bacteria. Consequently, loss of macrophage tolerance to the enteric microbiota plays a central role in the pathogenesis of inflammatory bowel diseases. Therefore, we examined whether the hyporesponsive phenotype of intestinal macrophages is programmed by prior exposure to the microbiota. IL-10, but not in vivo exposure to the microbiota, programs intestinal macrophage tolerance, because wild-type (WT) colonic macrophages from germ-free and specific pathogen-free (SPF)-derived mice produce IL-10, but not IL-12 p40, when activated with enteric bacteria. Basal and activated IL-10 expression is mediated through a MyD88-dependent pathway. Conversely, colonic macrophages from germ-free and SPF-derived colitis-prone Il10(-/-) mice demonstrated robust production of IL-12 p40. Next, mechanisms through which IL-10 inhibits Il12b expression were investigated. Although Il12b mRNA was transiently induced in LPS-activated WT bone marrow-derived macrophages (BMDMs), expression persisted in Il10(-/-) BMDMs. There were no differences in nucleosome remodeling, mRNA stability, NF-?B activation, or MAPK signaling to explain prolonged transcription of Il12b in Il10(-/-) BMDMs. However, acetylated histone H4 transiently associated with the Il12b promoter in WT BMDMs, whereas association of these factors was prolonged in Il10(-/-) BMDMs. Experiments using histone deacetylase (HDAC) inhibitors and HDAC3 short hairpin RNA indicate that HDAC3 is involved in histone deacetylation of the Il12b promoter by IL-10. These results suggest that histone deacetylation on the Il12b promoter by HDAC3 mediates homeostatic effects of IL-10 in macrophages.
Project description:Here, we investigated the impact of mulberry fruit (MBF) extracts on lipopolysaccharide (LPS)-induced inflammatory responses in RAW 264.7 macrophages, and the therapeutic efficacy of MBF diet in mice with dextran sulfate sodium (DSS)-induced acute colitis and MUC2(-/-) mice with colorectal cancer. In vitro, LPS-induced nitric oxide (NO) production was significantly inhibited by MBF extracts via suppressing the expression of proinflammatory molecules, including inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-1 beta (IL-?) and IL-6. Particularly, a dose-dependent inhibition on LPS-induced inflammatory responses was observed following treatment with MBF dichloromethane extract (MBF-DE), in which linoleic acid and ethyl linolenate were identified as two active compounds. Moreover, we elucidated that MBF-DE attenuated LPS-induced inflammatory responses by blocking activation of both NF-?B/p65 and pERK/MAPK pathways. In vivo, DSS-induced acute colitis was significantly ameliorated in MBF-fed mice as gauged by weight loss, colon morphology and histological damage. In addition, MBF-fed MUC2(-/-) mice displayed significant decrease in intestinal tumor and inflammation incidence compared to control diet-fed group. Overall, our results demonstrated that MBF suppressed the development of intestinal inflammation and tumorgenesis both in vitro and in vivo, and supports the potential of MBF as a therapeutic functional food for testing in human clinical trials.
Project description:Chronic inflammation is a risk factor for colorectal cancer. The MAPK-activated protein kinase 2 (MK2) pathway controls multiple cellular processes including p38-dependent inflammation. This is the first study to investigate the role of MK2 in development of colitis-associated colon cancer (CAC). Herein, we demonstrate that MK2(-/-) mice are highly resistant to neoplasm development when exposed to AOM/DSS, while wild type (WT) C57BL/6 develop multiple neoplasms with the same treatment. MK2-specific cytokines IL-1, IL-6 and TNF-? were substantially decreased in AOM/DSS treated MK2(-/-) mouse colon tissues compared with WT mice, which coincided with a marked decrease in macrophage influx. Restoring MK2-competent macrophages by injecting WT bone marrow derived macrophages into MK2(-/-) mice led to partial restoration of inflammatory cytokine production with AOM/DSS treatment; however, macrophages were not sufficient to induce neoplasm development. These results indicate that MK2 functions as an inflammatory regulator to promote colonic neoplasm development and may be a potential target for CAC.