During chronic infection with Helicobacter pylori , Schlafen 4-expressing myeloid-derived suppressor cells (SLFN4 + MDSCs) create a microenvironment favoring intestinal metaplasia and neoplastic transformation. SLFN4 can be induced by IFN-α, which is mainly secreted from plasmacytoid dendritic cells (pDCs). This study tested the hypothesis that Helicobacter pylori infection promotes SLFN4 + MDSC differentiation by inducing pDCs to secrete IFN-α. C57BL/6 mice were gavaged with H. pylori and infection lasted 2, 4, or 6 months. The mouse pDCs were isolated from the bone marrow from wild type C57BL/6J mice. The results showed that H. pylori infection increased the number of SLFN4 + MDSCs by inducing IFN-α expression in mice. Further mechanistic experiments unraveled that IFN-α induced SLFN4 transcription by binding to the SLFN4 promoter. Furthermore, H. pylori infection stimulated pDCs to secrete IFN-α by activating the TLR9-MyD88-IRF7 pathway. Collectively, Helicobacter pylori infection promotes SLFN4 + MDSC differentiation by inducing secretion of IFN-α from pDCs.

Pancreatic acinar cell carcinoma (PACC) is a rare tumor of the exocrine pancreas. It accounts for only 1% of all pancreatic malignancies. A 39-year woman sought treatment for repeated abdominal pain and jaundice. The computed tomography (CT) and magnetic resonance imaging (MRI) suggested diffuse enlargement of the pancreas. 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT showed diffuse enlargement of the pancreas and increased glucose uptake. The endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) biopsy of the pancreas was performed, and the case was finally diagnosed as PACC. After the sixth course of chemotherapy with gemcitabine and albumin paclitaxel, a CT scan showed significant shrinkage of the pancreas. PACC very rarely presents with diffuse enlargement of the pancreas. This case illustrates a rare presentation of PACC with diffuse pancreatic enlargement, which was effectively treated with gemcitabine and albumin paclitaxel chemotherapy.