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BACKGROUND & AIMS Sonic Hedgehog (Shh) is expressed in the adult stomach, but its role as a gastric morphogen is unclear. We sought to identify mechanisms by which Shh might regulate gastric epithelial cell function and differentiation. METHODS Mice with a parietal cell–specific deletion of Shh (HKCre/ShhKO) were created. Gastric morphology and function were studied in control and HKCre/ShhKO mice between 1 and 8 months of age. RESULTS In contrast to control mice, HKCre/ShhKO mice developed gastric hypochlorhydria, hypergastrinemia, and a phenotype that resembled foveolar hyperplasia. The fundic mucosa of HKCre/ShhKO mice had an expanded surface pit cell lineage that was documented by increased incorporation of bromodeoxyuridine and was attributed to the hypergastrinemia. Compared with controls, numbers of total mucous neck and zymogen cells were significantly decreased in stomachs of HKCre/ShhKO mice. In addition, zymogen and neck cell markers were coexpressed in the same cell populations, indicating disrupted differentiation of the zymogen cell lineage from the mucous neck cells in the stomachs of HKCre/ShhKO mice. Laser capture microdissection of the surface epithelium, followed by quantitative reverse-transcription polymerase chain reaction, revealed a significant increase in expression of Indian Hedgehog, glioma-associated oncogene homolog 1, Wnt, and cyclin D1. Laser capture microdissection analysis also showed a significant increase in Snail with a concomitant decrease in E-cadherin. CONCLUSIONS In the stomachs of adult mice, loss of Shh from parietal cells results in hypochlorhydria and hypergastrinemia. Hypergastrinemia might subsequently induce increased Hedgehog and Wnt signaling in the surface pit epithelium, resulting in hyperproliferation.

Background & Aims Macrophages mediate the epithelial response to Helicobacter pylori and are involved in the development of gastritis. Sonic Hedgehog (Shh) regulates gastric epithelial differentiation and function, but little is known about its immunoregulatory role in the stomach. We investigated whether gastric Shh acts as a macrophage chemoattractant during the innate immune response to H pylori infection. Methods Mice with parietal cell-specific deletion of Shh (PC-ShhKO) and control mice were infected with H pylori. Levels of gastric Shh, cytokines, and chemokines were assayed by quantitative reverse-transcriptase PCR or by a Luminex®-based multiplex assay, 2, 7, or 180 days after infection. Circulating concentrations of Shh were measured by ELISA. Bone marrow chimera experiments were performed with mice that have myeloid cell-specific deletion of the Hedgehog signal transduction protein smoothened (LysMCre/SmoKO). Macrophage recruitment was measured in gastric tissue and peripheral blood by fluorescence-activated cell sorting analysis. Results Control mice infected with H pylori for 6 months developed an inflammatory response characterized by infiltration of CD4+ T cells and increased levels of interferon-γ and interleukin (IL)-1β in the stomach. PC-ShhKO mice did not develop gastritis, even after 6 months of infection with H pylori. Control mice had increased concentrations of Shh, accompanied by the recruitment of CD11b+F4/80+Ly6Chigh macrophages 2 days after infection. Control mice that received bone marrow transplants from control mice had an influx of macrophages to the gastric mucosa in response to H pylori infection; this was not observed in H pylori-infected control mice that received bone marrow transplants from LysMCre/SmoKO mice. Conclusion H pylori induces release of Shh from the stomach; Shh acts as a macrophage chemoattractant during initiation of gastritis.

Background The therapeutic potential of exosomes derived from stem cells has attracted increasing interest recently, because they can exert similar paracrine functions of stem cells and overcome the limitations of stem cells transplantation. Exosomes derived from bone mesenchymal stem cells (BMSC-Exos) have been confirmed to promote osteogenesis and angiogenesis. The magnetic nanoparticles (eg. Fe3O4, γ-Fe2O3) combined with a static magnetic field (SMF) has been commonly used to increase wound healing and bone regeneration. Hence, this study aims to evaluate whether exosomes derived from BMSCs preconditioned with a low dose of Fe3O4 nanoparticles with or without the SMF, exert superior pro-osteogenic and pro-angiogenic activities in bone regeneration and the underlying mechanisms involved. Methods Two novel types of exosomes derived from preconditioned BMSCs that fabricated by regulating the contents with the stimulation of magnetic nanoparticles and/or a SMF. Then, the new exosomes were isolated by ultracentrifugation and characterized. Afterwards, we conducted in vitro experiments in which we measured osteogenic differentiation, cell proliferation, cell migration, and tube formation, then established an in vivo critical-sized calvarial defect rat model. The miRNA expression profiles were compared among the exosomes to detect the potential mechanism of improving osteogenesis and angiogenesis. At last, the function of exosomal miRNA during bone regeneration was confirmed by utilizing a series of gain- and loss-of-function experiments in vitro. Results 50 µg/mL Fe3O4 nanoparticles and a 100 mT SMF were chosen as the optimum magnetic conditions to fabricate two new exosomes, named BMSC-Fe3O4-Exos and BMSC-Fe3O4-SMF-Exos. They were both confirmed to enhance osteogenesis and angiogenesis in vitro and in vivo compared with BMSC-Exos, and BMSC-Fe3O4-SMF-Exos had the most marked effect. The promotion effect was found to be related to the highly riched miR-1260a in BMSC-Fe3O4-SMF-Exos. Furthermore, miR-1260a was verified to enhance osteogenesis and angiogenesis through inhibition of HDAC7 and COL4A2, respectively. Conclusion These results suggest that low doses of Fe3O4 nanoparticles combined with a SMF trigger exosomes to exert enhanced osteogenesis and angiogenesis and that targeting of HDAC7 and COL4A2 by exosomal miR-1260a plays a crucial role in this process. This work could provide a new protocol to promote bone regeneration for tissue engineering in the future. Graphical abstract

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(5, 6). FADD has a carboxylterminal DD and an amino-terminal death effector domain (DED). Through its DED, FADD recruits the DED-containing apoptosis-initiating proteases caspase-8 (7, 8) and caspase-10 (9 -11) to the Fas receptor to assemble a DISC (12). In the DISC, caspase-8 is cleaved through autoproteolysis of caspase-8 molecules in close proximity (13). Active caspase-8 subunits are released into the cytoplasm to cleave downstream effector caspases such as caspase-3 (14), which subsequently cleaves its substrates such as DNA fragmentation factor 45 (DFF45) (15), to execute programmed cell death.Recently, the recruitment of other DED-containing proteins to the Fas-mediated DISC, which has been described, modulates DISC functions. These include a family of virus-encoded proteins referred to as v-FLIP (16, 17). v-FLIP contains two DEDs that can bind to the Fas/FADD complex to inhibit Fasmediated apoptosis by interfering with the recruitment of caspase-8 to the DISC. A mammalian cellular homolog of v-FLIP is termed c-FLIP (18), CASH (19), CASPER (20), CLARP (21), FLAME1 (22), I-FLICE (23), MRIT (24), and Usurpin (25). These studies, however, have generated controversy as to the functions of c-FLIP in apoptosis. Some groups have described it as pro-apoptotic (19 -21, 24), whereas others as anti-apoptotic (18,22,25). Recent analysis of Fas-mediated DISC in c-FLIPtransfected BJAB cells has shown that c-FLIP proteins are recruited to the Fas-mediated DISC to inhibit caspase-8 cleavage (26, 27), which supports the role of c-FLIP as an antiapoptotic molecule.The c-FLIP gene is composed of 13 exons that are clustered within ϳ200 kilobases within the caspase-8 and caspase-10 genes on human chromosome 2q33 to 34 (25, 28). c-FLIP is expressed as four main mRNA splice variants but only two forms of protein in human tissues (18,20). The short form protein (c-FLIP S , M r ϳ28) contains two DEDs and is structurally related to v-FLIP; the longer form (c-FLIP L , M r ϳ55) is structurally similar to caspase-8 and contains two DEDs and a caspase-like domain that lacks catalytic activity (18). c-FLIP L is expressed in many tissues, but c-FLIP S is found mainly in lymphatic tissue (18). Expression of c-FLIP mRNA and proteins is regulated by mitogen-activated protein kinase kinase in T lymphocytes (29)

Despite the important role for epidermal growth factor (EGF) in epithelial homeostasis and wound healing, it has not been investigated in atopic dermatitis (AD). We used AD animal models to explore the role of EGF in AD. In an acute AD model, skin trans-epidermal water loss (TEWL) was significantly attenuated in EGF treated mice. Blockade of EGFR signaling genetically or pharmacologically confirms a protective role for EGFR signaling in AD. In a chronic/relapsing AD model, EGF treatment of mice with established AD resulted in attenuation of AD exacerbation (skin epithelial thickness, cutaneous inflammation, and total and allergen specific IgE) following cutaneous allergen re-challenge. EGF treatment didn’t alter expression of skin barrier junction proteins or antimicrobial peptides in the AD model. However, EGF treatment attenuated allergen-induced expression of IL-17A, CXCL1 and CXCL2, and neutrophil accumulation in AD skin following cutaneous allergen exposure. IL-17A production was decreased in the in vitro re-stimulated skin-draining lymph node cells from the EGF-treated mice. Similarly, IL-17A was increased in waved-2 mice skin following allergen exposure. While IL-6 and IL-1β expression were attenuated in the skin of EGF-treated mice, EGF treatment also suppressed allergen-induced IL-6 production by keratinocytes. Given the central role of IL-6 in priming Th17 differentiation in the skin, this effect of EGF on keratinocytes may contribute to the protective roles for EGFR in AD pathogenesis. In conclusion, our study provides evidence for a previously unrecognized protective role for EGF in AD and a new role for EGF in modulating IL-17 responses in the skin.

Sonic hedgehog (Shh) is found within gastric parietal cells and processed from a 45-kDa to a 19-kDa bioactive protein by an acid- and protease-dependent mechanism. To investigate whether Shh is associated with the parietal cell membrane compartment that becomes exposed to both acid and proteolytic enzymes during acid secretion, the cellular location of Shh within resting and stimulated gastric parietal cells was examined. Immunofluorescence microscopy of rabbit stomach sections showed that Shh colocalized predominantly with parietal and pit, not chief/zymogen or neck, cell markers. In resting and histamine-stimulated rabbit gastric glands Shh was expressed only in parietal cells close to H+-K+-ATPase-containing tubulovesicular and secretory membranes with some colocalizing with gamma-actin at the basolateral membrane. Gastric gland microsomal membranes were prepared by differential and sucrose gradient centrifugation and immunoisolation with an anti-H+-K+-ATPase-alpha subunit antibody. The 45- and 19-kDa Shh proteins were detected by immunoblot in immunopurified H+-K+-ATPase-containing membranes from resting and stimulated gastric glands, respectively. Incubating glands with a high KCl concentration removed Shh from the membranes. Histamine stimulated 19-kDa Shh secretion from gastric glands into the medium. In human gastric cancer 23132/87 cells cultured on permeable membranes, histamine increased 19-kDa Shh secretion into both apical and basolateral media. These findings show that Shh is a peripheral protein associated with resting and stimulated H+-K+-ATPase-expressing membranes. In addition, Shh appears to be expressed at or close to the basolateral membrane of parietal cells.