Anti-Inflammatory Activity of Bone Morphogenetic Protein Signaling Pathways in Stomachs of Mice

Abstract

BACKGROUND & AIMS Bone morphogenetic protein (BMP)4 is a mesenchymal peptide that regulates cells of the gastric epithelium. We investigated whether BMP signaling pathways affect gastric inflammation after bacterial infection of mice. METHODS We studied transgenic mice that express either the BMP inhibitor noggin or the β- galactosidase gene under the control of a BMP-responsive element and BMP4βgal/+ mice. Gastric inflammation was induced by infection of mice with either Helicobacter pylori or Helicobacter felis. Eight to 12 weeks after inoculation, gastric tissue samples were collected and immunohistochemical, quantitative, reverse-transcription polymerase chain reaction and immunoblot analyses were performed. We used enzyme-linked immunosorbent assays to measure cytokine levels in supernatants from cultures of mouse splenocytes and dendritic cells, as well as from human gastric epithelial cells (AGS cell line). We also measured the effects of BMP-2, BMP-4, BMP-7, and the BMP inhibitor LDN-193189 on the expression of interleukin (IL)8 messenger RNA by AGS cells and primary cultures of canine parietal and mucus cells. The effect of BMP-4 on NFkB activation in parietal and AGS cells was examined by immunoblot and luciferase assays. RESULTS Transgenic expression of noggin in mice increased H pylori– or H felis–induced inflammation and epithelial cell proliferation, accelerated the development of dysplasia, and increased expression of the signal transducer and activator of transcription 3 and activation-induced cytidine deaminase. BMP-4 was expressed in mesenchymal cells that expressed α-smooth muscle actin and activated BMP signaling pathways in the gastric epithelium. Neither BMP-4 expression nor BMP signaling were detected in immune cells of C57BL/6, BRE–β-galactosidase, or BMP-4βgal/+ mice. Incubation of dendritic cells or splenocytes with BMP-4 did not affect lipopolysaccharide-stimulated production of cytokines. BMP-4, BMP-2, and BMP-7 inhibited basal and tumor necrosis factor α–stimulated expression of IL8 in canine gastric epithelial cells. LDN-193189 prevented BMP4-mediated inhibition of basal and tumor necrosis factor α–stimulated expression of IL8 in AGS cells. BMP-4 had no effect on TNFα-stimulated phosphorylation and degradation of IκBα, or on TNFα induction of a NFκβ reporter gene. CONCLUSIONS BMP signaling reduces inflammation and inhibits dysplastic changes in the gastric mucosa after infection of mice with H pylori or H felis.

Regulation of Gastric Metaplasia, Dysplasia, and Neoplasia by Bone Morphogenetic Protein Signaling

“…Localization of cells receiving BMP-generated signals was determined in experiments with transgenic mice that express β-galactosidase under the control of a BMP-responsive element. In this system X-gal positively stained cells could be detected mostly at the level of the isthmus and neck of the glands but not in the mesenchyme in both the absence and presence of inflammation 20 . Similar results were observed when sections of the gastric mucosa of Helicobacter pylori –infected mice were stained with antibodies recognizing phosphorylated and active forms of the BMP-4 signal transducing proteins, Smad1, 5, and 8 20 .…”

“…In agreement with these observations, the gastric mucosa of H pylori– infected noggin transgenic mice exhibited enhanced production of cytokines, induction of cell proliferation and of STAT3 phosphorylation, and increased expression of activation-induced cytidine deaminase, 20 a molecule that has been shown to mediate some of the pro-oncogenic actions of H pylori in the stomach 76 (Figure 4). Thus, inhibition of BMP signaling in the gastric epithelium leads to the development of a pro-oncogenic environment characterized by increased cell proliferation, dysplasia, and by enhanced expression of STAT3 and activation-induced cytidine deaminase.…”

“…To analyze the pattern of expression of BMP-4 during inflammation, BMP-4 βgal/+ mice were infected with Helicobacter felis for 2 months. H felis induced the expression of TNF-α, MIP-2, and interferon-γ mRNAs in these mice, and it led to the development of significant foci of inflammatory infiltrates in the mucosa of the corpus 20 . Moreover, staining of corresponding sections with X-gal demonstrated that BMP-4 is expressed in clusters of cells that appear to be localized in the mesenchymal layers of the mucosa that are adjacent to but not in the inflammatory infiltrates 20 .…”

Bone morphogenetic proteins in inflammation, glucose homeostasis and adipose tissue energy metabolism

“…The anti-inflammatory effect of BMPs was also tested in a model of gastric inflammation after infection of transgenic mice (that express either BMP inhibitor noggin or the β galactosidase gene under the control of a BMP responsive element and BMP4 mice) with Helicobacter pylori or Helicobacter feolis [18]. BMP signalling reduces the inflammation and the presence of dysplastic changes in the gastric mucosa after infection.…”

Murine Models of Gastric Corpus Preneoplasia

“…Although there was increased proliferation in the mucosa, most of this proliferation was abolished when the transgenic mice were crossed onto a gastrin null background, a finding consistent with a role for proliferation in foveolar hyperplasia in these mice rather than SPEM 75 . Importantly, the overexpression of Noggin in the stomach caused an augmentation of metaplastic changes after infection with H felis or H pylori 100 . These findings suggest that BMP signaling generally is anti-inflammatory and that loss of this signaling may promote metaplasia development.…”