62 research outputs found
The role of the macrophage in sentinel responses in intestinal immunity
Get PDFThe purpose of this review is to highlight macrophages as central mediators of intestinal immune homeostasis and inflammation
<html>Induction of Murine Intestinal Inflammation by Adoptive Transfer of Effector CD4<sup>+</sup>CD45RB<sup>high</sup> T Cells into Immunodeficient Mice</html>
Get PDFThere are many different animal models available for studying the pathogenesis of human inflammatory bowel diseases (IBD), each with its own advantages and disadvantages. We describe here an experimental colitis model that is initiated by adoptive transfer of syngeneic splenic CD4+CD45RBhigh T cells into T and B cell deficient recipient mice. The CD4+CD45RBhigh T cell population that largely consists of naïve effector cells is capable of inducing chronic intestinal inflammation, closely resembling key aspects of human IBD. This method can be manipulated to study aspects of disease onset and progression. Additionally it can be used to study the function of innate, adaptive, and regulatory immune cell populations, and the role of environmental exposures, i.e., the microbiota, in intestinal inflammation. In this article we illustrate the methodology for inducing colitis with a step-by-step protocol. This includes a video demonstration of key technical aspects required to successfully develop this murine model of experimental colitis for research purposes
Cutting Edge: IFN- Is a Negative Regulator of IL-23 in Murine Macrophages and Experimental Colitis
Get PDFIL-23 regulation is a central event in the pathogenesis of the inflammatory bowel diseases. We demonstrate that IFN-γ has anti-inflammatory properties in the initiation phase of IL-23–mediated experimental colitis. IFN-γ attenuates LPS-mediated IL-23 expression in murine macrophages. Mechanistically, IFN-γ inhibits Il23a promoter activation through altering NF-κB binding and histone modification. Moreover, intestinal inflammation is inhibited by IFN-γ signaling through attenuation of Il23a gene expression. In germ-free wild-type mice colonized with enteric microbiota, inhibition of colonic Il23a temporally correlates with induction of IFN-γ. IFN-γR1/IL-10 double-deficient mice demonstrate markedly increased colonic inflammation and IL23a expression compared with those of IL-10−/− mice. Colonic CD11b+ cells are the primary source of IL-23 and a target for IFN-γ. This study describes an important anti-inflammatory role for IFN-γ through inhibition of IL-23. Converging genetic and functional findings suggest that IL-23 and IFN-γ are important pathogenic molecules in human inflammatory bowel disease
Aberrant miR-29 is a predictive feature of severe phenotypes in pediatric Crohn’s disease
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Aberrant miR-29 is a predictive feature of severe phenotypes in pediatric Crohn’s disease
Get PDFFunding Information: This work was supported by 5P01DK094779 (NIH/NIDDK) awarded to SZS, TSF, and PS; the NIDDK R01 DK136262 awarded to SZS; and 5R21HD104922-02 (NIH/NICHD) awarded to PS. We would also like to thank BioRender for its help in creating our graphical abstract.Peer reviewe
An Anti-Inflammatory Role for Carbon Monoxide and Heme Oxygenase-1 in Chronic Th2-Mediated Murine Colitis
Get PDFCigarette smoking is a significant environmental factor in the human inflammatory bowel diseases, remarkably, conferring protection in ulcerative colitis. We previously demonstrated that a prominent component of cigarette smoke, CO, suppresses Th17-mediated experimental colitis in IL-10−/− mice through a heme oxygenase (HO)-1–dependent pathway. In this study, homeostatic and therapeutic effects of CO and HO-1 were determined in chronic colonic inflammation in TCR-α–deficient (−/−) mice, in which colitis is mediated by Th2 cytokines, similar to the cytokine milieu described in human ulcerative colitis. TCRα−/− mice exposed to CO or treated with the pharmacologic HO-1 inducer cobalt protoporphyrin demonstrated amelioration of active colitis. CO and cobalt protoporphyrin suppressed colonic IL-1β, TNF, and IL-4 production, whereas IL-10 protein secretion was increased. CO induced IL-10 expression in macrophages and in vivo through an HO-1–dependent pathway. Bacterial products regulate HO-1 expression in macrophages through MyD88- and IL-10–dependent pathways. CO exposure and pharmacologic HO-1 induction in vivo resulted in increased expression of HO-1 and IL-10 in CD11b+ lamina propria mononuclear cells. Moreover, induction of the IL-10 family member IL-22 was demonstrated in CD11b− lamina propria mononuclear cells. In conclusion, CO and HO-1 induction ameliorated active colitis in TCRα−/− mice, and therapeutic effects correlated with induction of IL-10. This study provides further evidence that HO-1 mediates an important homeostatic pathway with pleiotropic anti-inflammatory effects in different experimental models of colitis and that targeting HO-1, therefore, is a potential therapeutic strategy in human inflammatory bowel diseases
Molecular classification of Crohn's disease reveals two clinically relevant subtypes
Get PDFThe clinical presentation and course of Crohn’s disease (CD) is highly variable. We sought to better understand the cellular and molecular mechanisms that guide this heterogeneity, and characterize the cellular processes associated with disease phenotypes
Alterations to chromatin in intestinal macrophages link IL-10 deficiency to inappropriate inflammatory responses
Get PDFIntestinal macrophages are uniquely programmed to tolerate exposure to bacteria without mounting potent inflammatory responses. The cytokine IL-10 maintains the macrophage anti-inflammatory response such that loss of IL-10 results in chronic intestinal inflammation. To investigate how IL-10-deficiency alters intestinal macrophage programming and bacterial tolerance, we studied changes in chromatin accessibility in response to bacteria in macrophages from two distinct niches, the intestine and bone-marrow, from both wild-type and IL-10-deficient mice. In both bone-marrow-derived and intestinal macrophages, we identified chromatin accessibility changes associated with bacterial exposure and IL-10-deficiency. Surprisingly, IL-10-deficient intestinal macrophages adopted chromatin and gene expression patterns characteristic of an inflammatory response, even in the absence of bacteria. Further, if IL-10 protein was added to cells that had previously been IL-10-deficient, it could not revert the chromatin landscape to a normal state. Our results demonstrate that IL-10 deficiency results in stable chromatin alterations in macrophages, even in the absence of bacteria. This supports a model where IL-10-deficiency leads to chromatin alterations that contribute to a loss of intestinal macrophage tolerance to bacteria, which is a primary initiating event in chronic intestinal inflammation
IL-10 Regulates Il12b Expression via Histone Deacetylation: Implications for Intestinal Macrophage Homeostasis
Get PDFTo 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 the 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, as 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. While 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-κB activation or MAPK signaling to explain prolonged transcription of Il12b in Il10−/− BMDMs. However, acetylated histone H4 (AcH4) transiently associated with the Il12b promoter in WT BMDMs, whereas association of these factors was prolonged in Il10−/− BMDMs. Experiments utilizing histone deacetylase (HDAC) inhibitors and HDAC3 shRNA 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
Altered Macrophage Function Contributes to Colitis in Mice Defective in the Phosphoinositide-3 Kinase Subunit p110δ
Get PDFInnate immune responses are crucial for host defense against pathogens, but need to be tightly regulated to prevent chronic inflammation. Initial characterization of mice with a targeted inactivating mutation in the p110d subunit of phosphoinositide 3-kinase (PI3K p110δD910A/D910A) reveal defects in B- and T-cell signaling and chronic colitis. Here, we further characterize features of inflammatory bowel diseases (IBD) in these mice and investigate underlying innate immune defects
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