Activation of the epidermal growth factor receptor in macrophages regulates cytokine production and experimental colitis.
ABSTRACT: 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:EGF receptor (EGFR) in tumor cells serves as a tumor promoter. However, information about EGFR activation in macrophages in regulating M2 polarization and tumor development is limited. This study aimed to investigate the effects of EGFR activation in macrophages on M2 polarization and development of gastrointestinal tumors. IL-4, a cytokine to elicit M2 polarization, stimulated release of an EGFR ligand, HB-EGF, and transactivation and down-regulation of EGFR in Raw 264.7 cells and peritoneal macrophages from WT mice. Knockdown of HB-EGF in macrophages inhibited EGFR transactivation by IL-4. IL-4-stimulated STAT6 activation, Arg1 and YM1 gene expression, and HB-EGF production were further enhanced by inhibition of EGFR activity in Raw 264.7 cells using an EGFR kinase inhibitor and in peritoneal macrophages from Egfr(wa5) mice with kinase inactive EGFR and by knockdown of EGFR in peritoneal macrophages from Egfr(fl/fl) LysM-Cre mice with myeloid cell-specific EGFR deletion. Chitin induced a higher level of M2 polarization in peritoneal macrophages in Egfr(fl/fl) LysM-Cre mice than that in Egfr(fl/fl) mice. Accordingly, IL-4-conditioned medium stimulated growth and epithelial-to-mesenchymal transition in gastric epithelial and colonic tumor cells, which were suppressed by that from Raw 264.7 cells with HB-EGF knockdown but promoted by that from Egfr(wa5) and Egfr(fl/fl) LysM-Cre peritoneal macrophages. Clinical assessment revealed that the number of macrophages with EGFR expression became less, indicating decreased inhibitory effects on M2 polarization, in late stage of human gastric cancers. Thus, IL-4-stimulated HB-EGF-dependent transactivation of EGFR in macrophages may mediate inhibitory feedback for M2 polarization and HB-EGF production, thereby inhibiting gastrointestinal tumor growth.
Project description:Disturbed activation of autophagy is implicated in the pathogenesis of inflammatory bowel disease. Accordingly, several autophagy-related genes have been identified as Crohn's disease susceptibility genes. We screened the autophagy activators from a library including 3,922 natural extracts using a high-throughput assay system. The extracts identified as autophagy activators were administered to mice with 2% dextran sodium sulfate (DSS). Among the autophagy inducers, Sanguisorba officinalis L. (SO) suppressed DSS-induced colitis. To identify the mechanism by which SO ameliorates colitis, epithelial cell and innate myeloid cells-specific Atg7-deficient mice (Villin-cre; Atg7<sup>f/f</sup> and LysM-cre; Atg7<sup>f/f</sup> mice, respectively) were analyzed. SO-mediated inhibition of colitis was observed in Villin-cre; Atg7<sup>f/f</sup> mice. However, SO and a mixture of its components including catechin acid, ellagic acid, gallic acid, and ziyuglycoside II (Mix<sub>4</sub>) did not suppressed colitis in LysM-cre; Atg7<sup>f/f</sup> mice. In large intestinal macrophages (M?) of Atg7<sup>f/f</sup> mice, SO and Mix<sub>4</sub> upregulated the expression of marker genes of anti-inflammatory M? including Arg1, Cd206, and Relma. However, these alterations were not induced in LysM-cre; Atg7<sup>f/f</sup> mice. These findings indicate that SO and its active components ameliorate DSS-induced colitis by providing intestinal M? with anti-inflammatory profiles via promotion of Atg7-dependent autophagy.
Project description:Tet methylcytosine dioxygenase 2 (Tet2) mediates demethylation of DNA. We here sought to determine the expression and function of Tet2 in macrophages upon exposure to lipopolysaccharide (LPS), and in the host response to LPS induced lung and peritoneal inflammation, and during <i>Escherichia (E.) coli</i> induced peritonitis. LPS induced <i>Tet2</i> expression in mouse macrophages and human monocytes in vitro, as well as in human alveolar macrophages after bronchial instillation in vivo. Bone marrow-derived macrophages from myeloid Tet2 deficient (<i>Tet2<sup>fl/fl</sup>LysM<sup>Cre</sup></i>) mice displayed enhanced production of IL-1β, IL-6 and CXCL1 upon stimulation with several Toll-like receptor agonists; similar results were obtained with LPS stimulated alveolar and peritoneal macrophages. Histone deacetylation was involved in the effect of Tet2 on IL-6 production, whilst methylation at the <i>Il6</i> promoter was not altered by Tet2 deficiency. <i>Tet2<sup>fl/fl</sup>LysM<sup>Cre</sup></i> mice showed higher IL-6 and TNF levels in bronchoalveolar and peritoneal lavage fluid after intranasal and intraperitoneal LPS administration, respectively, whilst other inflammatory responses were unaltered. <i>E. coli</i> induced stronger production of IL-1β and IL-6 by Tet2 deficient peritoneal macrophages but not in peritoneal lavage fluid of <i>Tet2<sup>fl/fl</sup>LysM<sup>Cre</sup></i> mice after in vivo intraperitoneal infection. <i>Tet2<sup>fl/fl</sup>LysM<sup>Cre</sup></i> mice displayed enhanced bacterial growth during <i>E. coli</i> peritonitis, which was associated with a reduced capacity of <i>Tet2<sup>fl/fl</sup>LysM<sup>Cre</sup></i> peritoneal macrophages to inhibit the growth of <i>E. coli</i> in vitro. Collectively, these data suggest that Tet2 is involved in the regulation of macrophage functions triggered by LPS and during <i>E. coli</i> infection.
Project description:Macrophages were derived from the bone-marrow of 3 x fl/+ Dicer LysCre +/- (wild-type) and 3 x fl/fl Dicer LysCre +/- mice and stimulated with IL-4 (50ng/mL) for 72h. Total RNA was isolated and analyzed by gene array. In this experiment, we derived Dicer deficient bone-marrow macrophages using Dicer fl/+ LysM-Cre by Dicer fl/+ crossed mice to obtain Dicer fl/fl LysM-cre progeny (and Dicer deficient macrophages). Next, we studied the effects of IL-4 stimulation in macrophage with a deficiency in Dicer/microRNAs.
Project description:Protein tyrosine phosphatase nonreceptor type 2 (PTPN2) plays a critical role in the pathogenesis of inflammatory bowel diseases (IBD). Mice lacking PTPN2 in dendritic cells (DCs) develop skin and liver inflammation by the age of 22 weeks due to a generalized loss of tolerance leading to uncontrolled immune responses. The effect of DC-specific PTPN2 loss on intestinal health, however, is unknown. The aim of this study was to investigate the DC-specific role of PTPN2 in the intestine during colitis development. PTPN2<sup>fl/fl</sup>xCD11c<sup>Cre</sup> mice were subjected to acute and chronic DSS colitis as well as T cell transfer colitis. Lamina propria immune cell populations were analyzed using flow cytometry. DC-specific PTPN2 deletion promoted infiltration of B and T lymphocytes, macrophages, and DCs into the lamina propria of unchallenged mice and elevated Th1 abundance during acute DSS colitis, suggesting an important role for PTPN2 in DCs in maintaining intestinal immune cell homeostasis. Surprisingly, those immune cell alterations did not translate into increased colitis susceptibility in acute and chronic DSS-induced colitis or T cell transfer colitis models. However, macrophage depletion by clodronate caused enhanced colitis severity in mice with a DC-specific loss of PTPN2. Loss of PTPN2 in DCs affects the composition of lamina propria lymphocytes, resulting in increased infiltration of innate and adaptive immune cells. However, this did not result in an elevated colitis phenotype, likely because increased infiltration of macrophages in the intestine upon loss of PTPN2 loss in DCs can compensate for the inflammatory effect of PTPN2-deficient DCs.
Project description:STAT3 is a master regulator of the immune responses. Here we show that M. tuberculosis-infected stat3fl/fl lysm cre mice, defective for STAT3 in myeloid cells, contained lower bacterial load in lungs and spleens, reduced granuloma extension but higher levels of pulmonary neutrophils. STAT3-deficient macrophages showed no improved control of intracellular mycobacterial growth. Instead, protection associated to elevated ability of stat3fl/fl lysm cre antigen-presenting cells (APCs) to release IL-6 and IL-23 and to stimulate IL-17 secretion by mycobacteria-specific T cells. The increased IL-17 secretion accounted for the improved control of infection since neutralization of IL-17 receptor A in stat3fl/fl lysm cre mice hampered bacterial control. APCs lacking SOCS3, which inhibits STAT3 activation via several cytokine receptors, were poor inducers of priming and of the IL-17 production by mycobacteria-specific T cells. In agreement, socs3fl/fl cd11c cre mice deficient of SOCS3 in DCs showed increased susceptibility to M. tuberculosis infection. While STAT3 in APCs hampered IL-17 responses, STAT3 in mycobacteria-specific T cells was critical for IL-17 secretion, while SOCS3 in T cells impeded IL-17 secretion. Altogether, STAT3 signalling in myeloid cells is deleterious in the control of infection with M. tuberculosis.
Project description:Gene expression analysis of sorted colon macrophages of Rictor fl/fl LysM+/+ and Rictor fl/fl LysM+/cre mice Dysregulations of immune and metabolic processes can lead to chronic inflammation, which is one of the driving forces for the development of cancer. Macrophages are regulators of these processes and therefore have a fundamental role for the initiation of cancer. Here we find that deletion of Rictor in myeloid cells increases tumor number and size in the colitis-associated colorectal cancer model and leads to a stronger inflammatory response in the underlying acute DSS-colitis model. OPN is shown to be upregulated in the serum of myeloid-specific Rictor-KO mice during the DSS-colitis and the more severe phenotype, characterized by decreased survival, increased weight loss, shorter colons and enhanced infiltration of immune cells into the colon, can be reverted by the neutralization of OPN in these mice. Microarray analysis reveals a change in inflammatory and metabolic gene signatures of Rictor-KO colon macrophages that is also seen in the Rictor-KO BMDM in vitro. Therefore, our data show that myeloid Rictor controls macrophage polarization and the cellular energy metabolism, thereby suppressing colitis and colitis-associated colorectal cancer. Overall design: Total RNA of sorted colon macrophages of Rictorfl/fl LysM+/+ and Rictorfl/fl LysM+/cre mice (n=3-4/group) was subjected to microarray analysis on Affymetrix GeneChip® Mouse Gene 2.0 ST arrays. Array data were processed using Affymetrix Expression Console. No technical replicates were performed.
Project description:Autophagy is a cell biological pathway affecting immune responses. In vitro, autophagy acts as a cell-autonomous defense against Mycobacterium tuberculosis, but its role in vivo is unknown. Here we show that autophagy plays a dual role against tuberculosis: antibacterial and anti-inflammatory. M. tuberculosis infection of Atg5(fl/fl) LysM-Cre(+) mice relative to autophagy-proficient littermates resulted in increased bacillary burden and excessive pulmonary inflammation characterized by neutrophil infiltration and IL-17 response with increased IL-1? levels. Macrophages from uninfected Atg5(fl/fl) LysM-Cre(+) mice displayed a cell-autonomous IL-1? hypersecretion phenotype, whereas T cells showed propensity toward IL-17 polarization during nonspecific activation or upon restimulation with mycobacterial antigens. Thus, autophagy acts in vivo by suppressing both M. tuberculosis growth and damaging inflammation.
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:Junctional adhesion molecule-A (JAM-A) is a transmembrane glycoprotein expressed on leukocytes, endothelia, and epithelia that regulates biological processes including barrier function and immune responses. While JAM-A has been reported to facilitate tissue infiltration of leukocytes under inflammatory conditions, the contributions of leukocyte-expressed JAM-A in vivo remain unresolved. We investigated the role of leukocyte-expressed JAM-A in acute peritonitis induced by zymosan, lipopolysaccharide (LPS), or TNF? using mice with selective loss of JAM-A in myelomonocytic cells (LysM-Cre;Jam-afl/fl). Surprisingly, in LysM-Cre;Jam-afl/fl mice, loss of JAM-A did not affect neutrophil (PMN) recruitment into the peritoneum in response to zymosan, LPS, or TNF? although it was significantly reduced in Jam-aKO mice. In parallel, Jam-aKO peritoneal macrophages exhibited diminished CXCL1 chemokine production and decreased activation of NF-kB, whereas those from LysM-Cre;Jam-afl/fl mice were unaffected. Using Villin-Cre;Jam-afl/fl mice, targeted loss of JAM-A on intestinal epithelial cells resulted in increased intestinal permeability along with reduced peritoneal PMN migration as well as lower levels of CXCL1 and active NF-kB similar to that observed in Jam-aKO animals. Interestingly, in germ-free Villin-Cre;Jam-afl/fl mice, PMN recruitment was unaffected suggesting dependence on gut microbiota. Such observations highlight the functional link between a leaky gut and regulation of innate immune responses.