Primary Myofibroblasts Maintain Short-Term Viability following Submucosal Injection in Syngeneic, Immune-Competent Mice Utilizing Murine Colonoscopy.
ABSTRACT: The myofibroblast is an important stromal cell of the gastrointestinal tract. Current in vitro and in vivo models either do not accurately recreate stromal-epithelial interactions or are not specific to myofibroblasts. We sought to create an animal model that would allow the study of myofibroblast-epithelial interactions. We isolated and cultured colonic myofibroblasts from FVB mice. Cells were ?-SMA and vimentin positive but desmin negative on immunoblot analysis. We injected the myofibroblasts into the colonic submucosa of syngeneic adult mice (n = 8) via a miniendoscopic system. We then isolated green fluorescent protein (GFP) positive colonic myofibroblasts from C57BL/6-Tg(CAG-EGFP)1Osb/J mice and injected them into the colonic lamina propria of C57BL/6J mice at 1x10(5) (n = 14), 1x10(6) (n = 9), or 5x10(6) cells/mL (n = 4). A subset of mice were injected with serum-free media and ink without cells (n = 3). Mice underwent repeat endoscopy and euthanasia one or 7 days after injection. Colons were isolated and either fixed in 10% formalin or the inked sites were individually excised and lysed for DNA. We assessed the injection sites via histology and immunohistochemical stains for ?-SMA and GFP. We used qPCR to quantify GFP DNA transcripts at the lamina propria injection sites. Submucosal injection of myofibroblasts resulted in the formation of a subepithelial wheal on endoscopy, which persisted to day 7. Myofibroblasts injected either into the submucosa or lamina propria maintained viability on post-injection day 7 as evidenced by positive ?-SMA staining. qPCR of lamina propria injections showed a dose-dependent increase in GFP DNA transcripts on post-injection day 1, whereas the number of transcripts on day 7 was equivalent for the concentrations injected. We demonstrate short-term survival of primary cultured colonic myofibroblasts in syngeneic mice. This may prove to be a valuable model for studying the role of myofibroblasts in states of health and disease.
Project description:The colonic lamina propria contains a distinct population of Foxp3+ T regulatory cells (Tregs) that modulate responses to commensal microbes. Analysis of gene expression revealed that the transcriptome of colonic Tregs is distinct from splenic and other tissue Tregs. Rorγ and Helios in colonic Tregs mark distinct populations: Rorγ+Helios- or Rorγ-Helios+ Tregs. We uncovered an unanticipated role for Rorγ, a transcription factor generally considered to be antagonistic to Foxp3. Rorγ in colonic Tregs accounts for a small but specific part of the colon-specific Treg signature. (1) Total colonic and splenic Foxp3+ Treg comparison: Lymphocytes were isolated from colonic lamina propria and spleens of Foxp3-ires-GFP mice, where GFP reports Foxp3 expression. TCRb+CD4+GFP+ cells were double sorted into Trizol. (2) Colonic Rorγ+ and Rorγ- Treg comparison: Foxp3-ires-Thy1.1 reporter mice were crossed to Rorc-GFP reporter mice to generate mice that report both Foxp3 and Rorγ expression. Rorγ+Foxp3+ Tregs (TCRb+CD4+Thy1.1+GFP+) and Rorγ-Foxp3+ Tregs (TCRb+CD4+Thy1.1+GFP-) from colonic lamina propria were double sorted into Trizol.To reduce variability and increase cell number, cells from multiple mice were pooled for sorting and at least three replicates were generated for all groups. RNA from 1.5-3.0 x104 cells was amplified, labeled and hybridized to Affymetrix Mouse Gene 1.0 ST Arrays.
Project description:To further development of our gene expression approach to CD300a deficiency on dendritic cells (DCs) in colonic lamina propria, we have employed whole genome microarray expression profiling as a discovery platform to identify genes with the potential to distinguish CD300a deficiency on DCs in colonic lamina propria from those of WT mice. Colonic lamina propria DCs were obtained by cell sorter from WT and CD300a deficient mice raised under SPF and GF condition. Expression of Ifnb1 was significantly higher in CD300a deficient DCs, quantified in the same RNA samples by real-time PCR. Gene expression in WT and CD300a colonic lamina propria DCs raised under SPF and GF conditions were measured. Colonic lamina propria cells were obtained from 5 mice in each conditions. Takara-Bio
Project description:?-Smooth muscle actin (?-SMA) is used as a marker for a subset of activated fibrogenic cells, myofibroblasts, which are regarded as important effector cells of tissue fibrogenesis. We address whether ?-SMA-expressing myofibroblasts are detectable in fibrotic muscles of mdx5cv mice, a mouse model for Duchenne muscular dystrophy (DMD), and whether the ?-SMA expression correlates with the fibrogenic function of intramuscular fibrogenic cells. ?-SMA immunostaining signal was not detected in collagen I (GFP)-expressing cells in fibrotic muscles of ColI-GFP/mdx5cv mice, but it was readily detected in smooth muscle cells lining intramuscular blood vessel walls. ?-SMA expression was detected by quantitative RT-PCR and Western blot in fibrogenic cells sorted from diaphragm and quadriceps muscles of the ColI-GFP/mdx5cv mice. Consistent with the more severe fibrosis in the ColI-GFP/mdx5cv diaphragm, the fibrogenic cells in the diaphragm exerted a stronger fibrogenic function than the fibrogenic cells in the quadriceps as gauged by their extracellular matrix gene expression. However, both gene and protein expression of ?-SMA was lower in the diaphragm fibrogenic cells than in the quadriceps fibrogenic cells in the ColI-GFP/mdx5cv mice. We conclude that myofibroblasts are present in fibrotic skeletal muscles, but their expression of ?-SMA is not detectable by immunostaining. The level of ?-SMA expression by intramuscular fibrogenic cells does not correlate positively with the level of collagen gene expression or the severity of skeletal muscle fibrosis in the mdx5cv mice. ?-SMA is not a functional marker of fibrogenic cells in skeletal muscle fibrosis associated with muscular dystrophy.
Project description:The aim of this study was to determine whether bone marrow-derived fibrocytes migrate into the cornea after stromal scar-producing injury and differentiate into alpha-smooth muscle actin (?SMA) + myofibroblasts. Chimeric mice expressing green fluorescent protein (GFP) bone marrow cells had fibrosis (haze)-generating irregular phototherapeutic keratectomy (PTK). Multiplex immunohistochemistry (IHC) for GFP and fibrocyte markers (CD34, CD45, and vimentin) was used to detect fibrocyte infiltration into the corneal stroma and the development of GFP+ ?SMA+ myofibroblasts. IHC for activated caspase-3, GFP and CD45 was used to detect fibrocyte and other hematopoietic cells undergoing apoptosis. Moderate haze developed in PTK-treated mouse corneas at 14 days after surgery and worsened, and persisted, at 21 days after surgery. GFP+ CD34+ CD45+ fibrocytes, likely in addition to other CD34+ and/or CD45+ hematopoietic and stem/progenitor cells, infiltrated the cornea and were present in the stroma in high numbers by one day after PTK. The fibrocytes and other bone marrow-derived cells progressively decreased at four days and seven days after surgery. At four days after PTK, 5% of the GFP+ cells expressed activated caspase-3. At 14 days after PTK, more than 50% of GFP+ CD45+ cells were also ?SMA+ myofibroblasts. At 21 days after PTK, few GFP+ ?SMA+ cells persisted in the stroma and more than 95% of those remaining expressed activated caspase-3, indicating they were undergoing apoptosis. GFP+ CD45+ SMA+ cells that developed from 4 to 21 days after irregular PTK were likely developed from fibrocytes. After irregular PTK in the strain of C57BL/6-C57/BL/6-Tg(UBC-GFP)30Scha/J chimeric mice, however, more than 95% of fibrocytes and other hematopoietic cells underwent apoptosis prior to the development of mature ?SMA+ myofibroblasts. Most GFP+ CD45+ ?SMA+ myofibroblasts that did develop subsequently underwent apoptosis-likely due to epithelial basement membrane regeneration and deprivation of epithelium-derived TGF? requisite for myofibroblast survival.
Project description:The commensal microbiota is believed to have an important role in regulating immune responsiveness and preventing intestinal inflammation. Intestinal microbes produce signals that regulate inflammation via Toll-like receptor (TLR) signaling, but the mechanisms of this process are poorly understood. We investigated the role of the anti-inflammatory cytokine interleukin (IL)-10 in this signaling pathway using a mouse model of colitis.Clinical, histopathologic, and functional parameters of intestinal inflammation were evaluated in TLR4(-/-), IL-10(-/-), and TLR4(-/-) x IL-10(-/-) mice that were free of specific pathogens and in TLR4(-/-) x IL-10(-/-) mice following eradication and reintroduction of Helicobacter hepaticus. Regulatory T-cell (Treg) function was evaluated by crossing each of the lines with transgenic mice that express green fluorescent protein under control of the endogenous regulatory elements of Foxp3. Apoptotic cells in the colonic lamina propria were detected by a TUNEL assay.TLR4-mediated signals have 2 interrelated roles in promoting inflammation in TLR4(-/-) x IL-10(-/-) mice. In the absence of TLR4-mediated signals, secretion of proinflammatory and immunoregulatory cytokines is dysregulated. Tregs (Foxp3(+)) that secrete interferon-gamma and IL-17 accumulate in the colonic lamina propria of TLR4(-/-) x IL-10(-/-) mice and do not prevent inflammation. Aberrant control of epithelial cell turnover results in the persistence of antigen-presenting cells that contain apoptotic epithelial fragments in the colonic lamina propria of Helicobacter-infected TLR4(-/-) mice.In mice that lack both IL-10- and TLR4-mediated signals, aberrant regulatory T-cell function and dysregulated control of epithelial homeostasis combine to exacerbate intestinal inflammation.
Project description:The enteroinvasive bacterium Shigella is a facultative intracellular bacterium known, in vitro, to invade a large diversity of cells through the delivery of virulence effectors into the cell cytoplasm via a type III secretion system (T3SS). Here, we provide evidence that the injection of T3SS effectors does not necessarily result in cell invasion. Indeed, we demonstrate through optimization of a T3SS injection reporter that effector injection without subsequent cell invasion, termed the injection-only mechanism, is the main strategy used by Shigella to target human immune cells. We show that in vitro-activated human peripheral blood B, CD4+ T, and CD8+ T lymphocytes as well as switched memory B cells are mostly targeted by the injection-only mechanism. B and T lymphocytes residing in the human colonic lamina propria, encountered by Shigella upon its crossing of the mucosal barrier, are also mainly targeted by injection-only. These findings reveal that cells refractory to invasion can still be injected, thus extending the panel of host cells manipulated to the benefit of the pathogen. Future analysis of the functional consequences of the injection-only mechanism toward immune cells will contribute to the understanding of the priming of adaptive immunity, which is known to be altered during the course of natural Shigella infection.
Project description:To identify the role of chemokine receptor in inflammation of colon, we isolated CD3+CD4+ helper T cells harboring CXCR6 from colonic lamina propria of mice We used microarrays to identify the differentially expressed genes between CXCR6Hi Tcells and CXCR6Lo Tcells CXCR6 Hi or CXCR6 Lo T cells were isolated from colonic lamina propria for RNA extraction and hybridization on Affymetrix microarrays.
Project description:The IL-33 receptor ST2 is differentially expressed by colonic lamina propria Treg cells Microarray of sort-purified Foxp3+ Treg cells from colonic lamina propria over mesenteric lymph node
Project description:Regulation of innate inflammatory responses against the enteric microbiota is essential for the maintenance of intestinal homeostasis. Key participants in innate defenses are macrophages. In these studies, the basic leucine zipper protein, NFIL3, is identified as a regulatory transcription factor in macrophages, controlling IL-12 p40 production induced by bacterial products and the enteric microbiota. Exposure to commensal bacteria and bacterial products induced NFIL3 in cultured macrophages and in vivo. The Il12b promoter has a putative DNA-binding element for NFIL3. Basal and LPS-activated NFIL3 binding to this site was confirmed by chromatin immunoprecipitation. LPS-induced Il12b promoter activity was inhibited by NFIL3 expression and augmented by NFIL3-short hairpin RNA in an Il12b-bacterial artificial chromosome-GFP reporter macrophage line. Il12b inhibition by NFIL3 does not require IL-10 expression, but a C-terminal minimal repression domain is necessary. Furthermore, colonic CD11b(+) lamina propria mononuclear cells from Nfil3(-/-) mice spontaneously expressed Il12b mRNA. Importantly, lower expression of NFIL3 was observed in CD14(+) lamina propria mononuclear cells from Crohn's disease and ulcerative colitis patients compared with control subjects. Likewise, no induction of Nfil3 was observed in colons of colitis-prone Il10(-/-) mice transitioned from germ-free to a conventional microbiota. In conclusion, these experiments characterize NFIL3 as an Il12b transcriptional inhibitor. Interactions of macrophages with the enteric microbiota induce NFIL3 to limit their inflammatory capacity. Furthermore, altered intestinal NFIL3 expression may have implications for the pathogenesis of experimental and human inflammatory bowel diseases.