Background & Aims During aging, physiological changes in the stomach result in more tenuous gastric tissue that is less capable of repairing injury, leading to an increased susceptibility to chronic ulceration. Spasmolytic polypeptide/TFF2-expressing metaplasia (SPEM) is known to emerge following parietal cell loss and during Helicobacter pylori infection, however its role in gastric ulcer repair is unknown. Therefore, we sought to investigate if SPEM plays a role in epithelial regeneration. Methods Acetic acid ulcers were induced in young (2-3 months) and aged (18-24 months) C57BL/6 mice to determine the quality of ulcer repair with advancing age. Yellow chameleon 3.0 mice were used to generate YFP expressing organoids for transplantation. YFP+ gastric organoids were transplanted into the submucosa and lumen of the stomach immediately after ulcer induction. Gastric tissue was collected and analyzed to determine the engraftment of organoid-derived cells within the regenerating epithelium. Results Wound healing in young mice coincided with the emergence of SPEM within the ulcerated region, a response that was absent in the aged stomach. While aged mice exhibited less metaplasia surrounding the ulcerated tissue, organoid-transplanted aged mice showed regenerated gastric glands containing organoid-derived cells. Organoid transplantation in the aged mice led to the emergence of SPEM and gastric regeneration. Conclusions These data demonstrate the development of SPEM during gastric repair in response to injury that is absent in the aged stomach. In addition, gastric organoids in an injury/transplantation mouse model promoted gastric regeneration.

Collagen-producing myofibroblast transdifferentiation is considered a crucial determinant in the formation of scar tissue in the lungs of patients with idiopathic pulmonary fibrosis (IPF). Multiple resident pulmonary cell types and bone marrow-derived fibrocytes have been implicated as contributors to fibrotic lesions due to the transdifferentiation potential of these cells into myofibroblasts. In this study, we assessed the expression of Wilms’ tumor 1 (WT1), a known marker of mesothelial cells, in various cell types in normal and fibrotic lungs. We demonstrate that WT1 is expressed by both mesothelial and mesenchymal cells in IPF lungs, but has limited or no expression in normal human lungs. We also demonstrate that WT1-positive cells accumulate in fibrotic lung lesions, using two different mouse models of pulmonary fibrosis and WT1 promoter-driven fluorescent reporter mice. Reconstitution of bone-marrow cells into a transforming growth factor-α transgenic-mouse model demonstrated that fibrocytes do not transform into WT1-positive mesenchymal cells, but do augment accumulation of WT1-positive cells in severe fibrotic lung disease. Importantly, the number of WT1-positive cells in fibrotic lesions were correlated with severity of lung disease as assessed by changes in lung function, histology, and hydroxyproline levels in mice. Finally, inhibition of WT1 expression was sufficient to attenuate collagen and other extracellular-matrix gene production by mesenchymal cells from both murine and human fibrotic lungs. Thus, the results of this study demonstrate a novel association between fibrocyte-driven WT1-positive cell accumulation and severe fibrotic lung disease.

Although most high-risk neuroblastomas are responsive to chemotherapy, relapse is common and long-term survival is less than 40%, underscoring the need for more effective treatments. We evaluated the responsiveness of 12 neuroblastoma cell lines to the Δγ134.5 attenuated oncolytic HSV, Seprehvir (HSV1716), which is currently used in pediatric phase I trials. We found that entry of Seprehvir in neuroblastoma cells is independent of the expression of nectin-1 and the sum of all four known major HSV entry receptors. We observed varying levels of sensitivity and permissivity to Seprehvir, suggesting that the cellular anti-viral response, not virus entry, is the key determinant of efficacy with this virus. In vivo, we found significant anti-tumor efficacy following Seprehvir treatment, which ranged from 6/10 complete responses in the CHP-134 model to a mild prolonged median survival in the SK-N-AS model. Taken together, these data suggest that anti-tumor efficacy cannot be solely predicted based on in vitro response. Whether or not this discordance holds true for other viruses or tumor types is unknown. Our results also suggest that profiling the expression of known viral entry receptors on neuroblastoma cells may not be entirely predictive of their susceptibility to Seprehvir therapy.

Biliary atresia (BA) is a fibro-inflammatory obstruction of the extrahepatic biliary tree in newborns. It leads to rapid biliary fibrosis and is the most common indication for pediatric liver transplantation. In a model of rhesus rotavirus (RRV)-induced murine BA, plasmacytoid dendritic cells (DC) initiate NK-cell mediated hepatobiliary injury at 3 days post infection (dpi). We hypothesize that myeloid (m)DC coordinate T-cell driven injury during the later obstructive phase of BA. Following RRV injection into CD11c-DTR GFP pups on day 1 of life, frequency of hepatic DC increased 6fold at 12dpi compared with non-infected controls. Expansion of mDCs was accompanied by accumulation of activated CD4 cells in the liver. Plasma IL17A/F levels were increased at 8 and 12dpi (p<0.01) and hepatic IL17A mRNA increased 9fold between 8 and 12dpi. In vitro coculture of DC from 12dpi pups with naïve CD4 cells induced IL17A/6 production. DC-depletion following RRV infection with diphtheria toxin reduced the number of hepatic CD4 cells by 3fold which was associated with 2fold decrease in hepatic IL17A mRNA expression and plasma Th17-associated cytokine levels (IL-17F/6) at 12dpi. Importantly, diminished Th17 responses correlated with reduced plasma total bilirubin levels (6.1 vs 11.3mg/dL in control; p<0.01), a biomarker for biliary obstruction. We conclude that mDC maintain hepatic Th17 responses and regulate cholestatic liver injury during the obstructive phase of experimental BA.

GBA1 mutations lead to defective lysosomal glucocerebrosidase resulting in accumulation of glucosylceramide (GC) in Gaucher disease (GD). Patients with GD have an increased risk to develop B cell lymphomas. The exact mechanistic bases for this propensity remain elusive. Recently, we uncovered formation of GC-specific IgG autoantibodies in Gba1 D409V/knockout (Gba19V/−) mice, which recapitulate features of human GD, and in humans with untreated GD. In vivo formation of IgG-GC immune complexes induced massive complement activation and C5a generation. Importantly, C5a-mediated activation of its cognate C5a receptor 1 (C5aR1) on immune cells enhanced GC synthesis, thereby fueling GC accumulation and excess tissue recruitment and activation of inflammatory myeloid and lymphoid immune cells, leading to visceral tissue damage in GD. Here, the expression of Runt-related transcription factor 1 (RUNX-1) was determined in Gba19V/− mice, to evaluate if C5a/C5aR1 axis activation may control the development of lymphomas in GD. RUNX-1 is a member of the Runt oncogene family linked to hematologic malignancies. We determined RUNX-1 expression in tissue from C5aR1 sufficient (+/+) and deficient (−/−) Gba19V/− mice as well as strain-matched control WT and C5aR1−/− mice. Compared to WT, Gba19V/− mice had increased RUNX-1 expression. Strikingly, RUNX-1 expression was markedly downregulated in C5aR−/−Gba19V/− vs. C5aR1+/+Gba19V/− mice. Our findings suggest that the C5a-C5aR1 axis activation in GD drives RUNX1 expression as a novel mechanism to control the development of hematologic malignancies in GD that may be diminished by targeting the C5aR1 axis in GD.