Hirochika Toyama

Memory B cells without somatic hypermutation are generated from Bcl6-deficient B cells.

After immunization with T cell-dependent antigens, the high-affinity B cells selected in germinal centers differentiate into memory B cells or long-lived antibody-forming cells. However, a role for germinal centers in development of these B lineage cells is still controversial. We show here that Bcl6-deficient B cells, which cannot develop germinal centers, differentiated into IgM and IgG1 memory B cells in the spleen but barely differentiated into long-lived IgG1 antibody-forming cells in the bone marrow. Mutation in the V-heavy gene was null in these memory B cells. Therefore, Bcl6 and germinal center formation are essential for somatic hypermutation, and generation of memory B cells can occur independently of germinal center formation, somatic hypermutation, and Ig class switching.

Suppression of human pancreatic carcinoma cell growth and invasion by epigallocatechin-3-gallate.

Introduction The consumption of green tea is associated with a lower risk of several types of human carcinomas. A number of studies have focused on the possible mechanisms of cancer prevention by tea extracts, especially polyphenols such as epigallocatechin-3-gallate (EGCG). Aims and Methodology Green tea–derived EGCG was tested in human pancreatic carcinoma cells. The cells (PANC-1, MIA PaCa-2, and BxPC-3) were treated with different doses of EGCG (0, 25, 50, 100, and 200 &mgr;mol/L) for 48 hours in culture medium. Proliferation of pancreatic carcinoma cells was measured by means of the WST-1 colorimetric assay. For the study of cell invasion, the cells were incubated with 100 &mgr;mol/L EGCG for 2 hours. Then, the cells were added into the cell insert, coated with Matrigel basement membrane matrix. After incubation at 37°C for 24 hours, the cells that had invaded through the Matrigel were counted visually under the microscope. Results The growth of all three pancreatic carcinoma cells was significantly suppressed by EGCG treatment in a dose-dependent manner. EGCG treatment caused significant suppression of the invasive ability of pancreatic carcinoma cells PANC-1, MIA PaCa-2, and BxPC-3 but did not affect the cell cycle protein cyclin D1. Conclusion EGCG may be a potent biologic inhibitor of human pancreatic carcinomas, reducing their proliferative and invasive activities.

Pancreas preservation by the 2-layer cold storage method before islet isolation protects isolated islets against apoptosis through the mitochondrial pathway

BACKGROUND Apoptosis in isolated islets has been implicated in primary nonfunction or early graft failure after islet transplantation. Recently, pancreas preservation by the 2-layer method (TLM) before islet isolation has been proved to improve the islet yield, quality, and transplant results not only in experimental models, but also in clinical settings. We examined the influence of TLM on apoptosis of isolated islets. METHOD Rat islets freshly isolated and after pancreas preservation by TLM or conventional cold storage in University of Wisconsin solution (UW) were examined and compared. Islet apoptosis was assessed by TUNEL and annexin V assays. The apoptosis pathways involved were investigated by measurement of caspase 3, 8, and 9 activities and by immunoblotting for total and phosphorylated c-Jun NH2-terminal kinase (JNK) and p38. RESULTS Islet apoptosis in the UW group was significantly increased compared with the fresh and TLM groups. Both caspase 3 and 9 activities in the UW group were higher than in the fresh and TLM groups with an approximate increase of 2- to 3-fold. On the other hand, there was no significant difference in caspase 8 activity among these 3 groups. JNKs were strongly activated both in the TLM and UW groups; although they were not activated in the fresh group, p38 was activated to almost the same levels in these 3 groups. CONCLUSIONS Pancreas preservation by TLM before islet isolation protects isolated islets against apoptosis mainly through the mitochondrial pathway. Pancreas storage before islet isolation even with TLM triggers activation of JNKs in isolated islets.

Multicenter comparative study of laparoscopic and open distal pancreatectomy using propensity score-matching

Laparoscopic distal pancreatectomy has been shown to be associated with favorable postoperative outcomes using meta‐analysis. However, there have been no randomized controlled studies yet. This study aimed to compare laparoscopic and open distal pancreatectomy using propensity score‐matching.

Activation of macrophage-associated molecules after brain death in islets.

Islet transplantation is now established as an optional treatment for type I diabetes. However, rates of insulin independence in islet transplant recipients are still low. Although the major source of allograft is derived from brain-dead patient, the nonphysiologic state of brain death (BD) deteriorates organs such as liver and kidney. To determine the effects of BD on islets, a rodent model of BD has been used. Histologically, islets of BD rats showed decreased permeability and impaired integrity of the cell membranes. Flow cytometric analysis showed that CD11b/c-positive cells within islets were slightly increased in BD. This result suggests that BD induces macrophage infiltration into the islets. Moreover, RT-PCR revealed significant augmentation of macrophages-associated inflammatory molecules (IL-1β, IL-6, TNF-α, and MCP-1) in islets from a BD donor. Inducible nitric oxide synthase (iNOS) was weakly expressed, although not reaching statistical significance compared with control. Our results indicate that islets from a BD donor are immunologically activated and have a potential risk factor for early graft loss and a poor long-term function of grafts in clinical setting of islet transplantation. Immunomodulation, to eliminate intraislet immunocytes and/or activated macrophage-associated molecules, might be necessary for the better outcome after islet graft from BD donors.

A Focal Mass-Forming Autoimmune Pancreatitis Mimicking Pancreatic Cancer with Obstruction of the Main Pancreatic Duct

Introduction and backgroundAutoimmune pancreatitis (AIP) is a rare disease that closely mimics pancreatic cancer (PC) in its presentation. It is very important for clinicians to distinguish one from the other because their treatment and prognosis are vastly different. Typical radiological imaging findings, in particular observation of diffusely or segmentally narrowed main pancreatic duct (MPD) with an irregular wall by endoscopic retrograde cholangiopancreatography (ERCP), are essential for making the diagnosis of AIP. On the other hand, MPD obstruction is one of the most frequent features on ERCP.Case reportWe report a rare case of a patient with focal mass-forming AIP strongly suspected of being PC because of MPD obstruction on ERCP.ConclusionIt was difficult to distinguish PC from AIP with current diagnostic modalities. We will continue to make an effort to distinguish between the two disorders to prevent unnecessary surgery.

Mucinous cystic neoplasm of the pancreas presenting with hemosuccus pancreaticus: Report of a case

Hemosuccus pancreaticus (HP) is mostly induced by a ruptured pseudoaneurysm or hemorrhage from a pseudocyst in chronic pancreatitis. We herein report a rare case with HP induced by tumor hemorrhage. The present patient is a 71-year-old woman referred to us with a diagnosis of severe progressive anemia. Endoscopy revealed hemorrhage from the papilla of Vater. Computed tomography showed a multilocular cystic tumor in the tail of the pancreas. The patient underwent a distal pancreatectomy. The histopathological diagnosis was carcinoma in mucinous cystadenoma. No cancer infiltration into the pancreatic duct was detected. Pancreatography of the resected specimen demonstrated an overt communication between the main pancreatic duct and the cystic cavity of the tumor, which was not demonstrated preoperatively by endoscopic retrograde pancreatography. Although the cause of HP is mainly acute or chronic pancreatitis, we should bear in mind that a pancreatic tumor may be a possible cause of HP and that, as such, prompt and proper treatment is mandatory.

Characterization of islet-infiltrating immunocytes after pancreas preservation by two-layer (UW/perfluorochemical) cold storage method.

Clinical islet transplantation offers the prospect of good blood glycemic control without major surgical risks. Nevertheless, long-term function of the transplanted islets is seldom appreciated because rejection is followed by the graft failure. Although it has been implicated that islets have high immunogenicity, characterization of the islet-infiltrating immunocytes, such as leukocytes and macrophages, has not been extensively studied. Rat islets were isolated by the collagenase digestion method and separated by handpicking under the microscope. The islets were further dispersed into individual cells for flow cytometric analysis. Monoclonal antibodies directed toward T cells, B cells, and macrophages as well as ICAM-1, and MHC class I and II were used to enumerate cells. Pancreatic islets contained 6.3 +/- 2.9% immunocytes; T cells (39.6 +/- 4.2%), B cells (44.7 +/- 5.8%), and macrophages (1.7 +/- 0.6%). MHC class I was expressed on 85.6 +/- 2.8%, MHC class II on 36.8 +/- 2.9%, and ICAM-1 on 39.9 +/- 7.0%. The results of islets from preserved pancreas also showed the same tendency. As these islet-infiltrating immunocytes within the grafts may contribute to the rejection, one potential strategy to prevent early graft loss might start to eliminate or inactivate the islet-infiltrating immunocytes.

Second primary pancreatic ductal carcinoma in the remnant pancreas after pancreatectomy for pancreatic ductal carcinoma: High cumulative incidence rates at 5 years after pancreatectomy

OBJECTIVES The aim of this study was to determine the incidence rate and clinical features of second primary pancreatic ductal carcinoma (SPPDC) in the remnant pancreas after pancreatectomy for pancreatic ductal carcinoma (PDC). METHODS Data of patients undergoing R0 resection for PDC at a single high-volume center were reviewed. SPPDC was defined as a tumor in the remnant pancreas after R0 resection for PDC, and SPPDC met at least one of the following conditions: 1) the time interval between initial pancreatectomy and development of a new tumor was 3 years or more; 2) the new tumor was not located in contact with the pancreatic stump. We investigated the clinical features and treatment outcomes of patients with SPPDC. RESULTS This study included 130 patients who underwent surgical resection for PDC between 2005 and 2014. Six (4.6%) patients developed SPPDC. The cumulative 3- and 5-year incidence rates were 3.1% and 17.7%, respectively. Four patients underwent remnant pancreatectomy for SPPDC. They were diagnosed with the disease in stage IIA or higher and developed recurrence within 6 months after remnant pancreatectomy. One patient received carbon ion radiotherapy and survived 45 months. One patient refused treatment and died 19 months after the diagnosis of SPPDC. CONCLUSIONS The incidence rate of SPPDC is not negligible, and the cumulative 5-year incidence rate of SPPDC is markedly high. Post-operative surveillance of the remnant pancreas is critical for the early detection of SPPDC, even in long-term survivors after PDC resection.

Effect of Oxygenated Perfluorocarbon on Isolated Islets During Transportation

BACKGROUND Previous studies demonstrated the efficacy of the two-layer method (TLM) using oxygenated perfluorochemicals (PFC) for pancreas preservation. The current study investigated the effect of oxygenated PFC on isolated islets during transportation. MATERIALS AND METHODS Purified rat islets were stored in an airtight conical tube for 24h in RPMI culture medium at 22 degrees C or University of Wisconsin solution (UW) at 4 degrees C, either with or without oxygenated PFC. After storage, the islets were assessed for in vitro viability by static incubation (SI), FDA/PI staining, and energy status (ATP, energy charge, and ADP/ATP ratio) and for in vivo viability by a transplantation study. RESULTS UW at 4 degrees C and RPMI medium at 22 degrees C maintained islet quality almost equally in both in vitro and in vivo assessments. The ATP levels and energy status in the groups with PFC were significantly lower than those without PFC. The groups with PFC showed a significantly higher ADP/ATP ratio than those without PFC. In the transplantation study, blood glucose levels and AUC in the UW+PFC group were significantly higher than those in UW group. CONCLUSIONS UW at 4 degrees C and RPMI medium at 22 degrees C maintained islet quality equally under the conditions for islet transportation. The addition of oxygenated PFC, while advantageous for pancreas preservation, is not useful for islet transportation.