Antiproliferative activities through accelerating autophagic flux by basidalin and its analogs in human cancer cells.

Basidalin, isolated from the basidiomycete Leucoagaricus naucina, has previously demonstrated antibacterial and antitumor properties against murine cancer cells in vivo, but its effects on human cancer cells remain unknown. In this study, we found that basidalin possesses antiproliferative activity against human cancer cell lines. To elucidate the antiproliferative mechanism of basidalin, we focused on autophagy. Treatment with basidalin led to an increase in LC3-II expression level, and accelerated autophagic flux through an mTOR-independent pathway. Moreover, according to the structure-activity relationship analysis-including newly synthesized basidalin analogs-the formyl group, not the amino group, contributes to the antiproliferative activities of basidalin against human cancer cells. Additionally, the antiproliferative activity of basidalin analogs was strongly correlated with autophagy-inducing activity, indicating that basidalin exhibits antiproliferative activity through autophagy induction. These data suggest that basidalin, characterized by its ability to upregulate autophagic flux, emerges as a novel anticancer drug.

Biological evaluation for anti-inflammatory effect of africane-type sesquiterpenoids.

Africane-type sesquiterpenoids are a unique tricyclic carbon architecture sesquiterpenoid isolated as natural products. Δ9(15) -africanene has been reported to exhibit anti-inflammatory activity for carrageenan-induced rat foot edema. In this study, we reported structure-activity relationship study of africane-type sesquiterpenoids and found that some africane-type sesquiterpenoid analogs and their synthetic intermediate showed potent anti-inflammatory activity. To identify the mode of action of africane-type sesquiterpenoids and their synthetic intermediate, we evaluated the anti-inflammatory activity using lipopolysaccharide (LPS)-stimulated mouse macrophage RAW264.7 cells. Treatment with the africane-type compounds and their synthetic intermediate suppressed LPS-induced expressions of Cox-2 protein and mRNAs of the inflammatory cytokines IL-1ß and IL-6 at the concentrations that did not affect cell viability. Interestingly, although these africane-type compounds and their synthetic intermediate suppressed the pro-inflammatory cytokines' expressions, the compounds did not modulate NF-κB activation. These results suggest that the africane-type compounds and their synthetic intermediate are anti-inflammatory compounds that suppress the expression of LPS-induced inflammatory mediators independently of NF-κB activation.

Scalable Syntheses and Biological Evaluation of Africane-Type Sesquiterpenoids.

Practical total syntheses of africane-type sesquiterpenoids were realized by reexamination of a divergent strategy employing optimized three-component coupling followed by ring-closing metathesis and substrate-controlled cyclopropanation. This sequential eight-step conversion provided Δ9(15) -africanene, a common bicyclo[5.3.0]decane intermediate for the syntheses of africane derivatives, in more than twice the yield as in the previous approach. The scalability and robustness of this improved synthetic route were confirmed by gram-scale preparation of Δ9(15) -africanene. In vitro cell-based assays of the synthesized africane-type sesquiterpenoids disclosed that ester-incorporating derivatives showed cytotoxic activity against HeLa cells. The effect of relative and absolute configuration of africane-9,15-diol monoacetates on the cytotoxicity against HeLa cells was also investigated.

Mannose and phosphomannose isomerase regulate energy metabolism under glucose starvation in leukemia.

Diverse metabolic changes are induced by various driver oncogenes during the onset and progression of leukemia. By upregulating glycolysis, cancer cells acquire a proliferative advantage over normal hematopoietic cells; in addition, these changes in energy metabolism contribute to anticancer drug resistance. Because leukemia cells proliferate by consuming glucose as an energy source, an alternative nutrient source is essential when glucose levels in bone marrow are insufficient. We profiled sugar metabolism in leukemia cells and found that mannose is an energy source for glycolysis, the tricarboxylic acid (TCA) cycle, and the pentose phosphate pathway. Leukemia cells express high levels of phosphomannose isomerase (PMI), which mobilizes mannose to glycolysis; consequently, even mannose in the blood can be used as an energy source for glycolysis. Conversely, suppression of PMI expression or a mannose load exceeding the processing capacity of PMI inhibited transcription of genes related to mitochondrial metabolism and the TCA cycle, therefore suppressing the growth of leukemia cells. High PMI expression was also a poor prognostic factor for acute myeloid leukemia. Our findings reveal a new mechanism for glucose starvation resistance in leukemia. Furthermore, the combination of PMI suppression and mannose loading has potential as a novel treatment for driver oncogene-independent leukemia.

Identification of madangamine A as a novel lysosomotropic agent to inhibit autophagy.

Madangamines are marine natural products isolated from Xestospongia ingens, and madangamine A-E with a different D-ring structure have been reported. We have reported that madangamine A has strong anti-proliferative activity against various human cancer cell lines. In this study, to clarify the anti-proliferative activity of madangamine A, we searched for molecular target of the madangamine A in human cells. Treatment with madangamine A increased the levels of LC3-II and p62, autophagy-related proteins, concomitant with growth inhibition. Moreover, madangamine A resulted in lysosome enlargement and increase in lysosomal pH, which are same phenomena observed in chloroquine-treated cells. These results suggest that madangamine A is a novel lysosome inhibitor, and the anti-proliferative activity of madangamine A is due to the inhibition of lysosome function.

Seven-Step Synthesis of All-Nitrogenated Sugar Derivatives Using Sequential Overman Rearrangements.

All-nitrogenated sugars (ANSs), in which all hydroxy groups in a carbohydrate are replaced with amino groups, are anticipated to be privileged structures with useful biological activities. However, ANS synthesis has been challenging due to the difficulty in the installation of multi-amino groups. We report herein the development of a concise synthetic route to peracetylated ANSs in seven steps from commercially available monosaccharides. The key to success is the use of the sequential Overman rearrangement, which enables formal simultaneous substitution of four or five hydroxy groups in monosaccharides with amino groups. A variety of ANSs are available through the same reaction sequence starting from different initial monosaccharides by chirality transfer of secondary alcohols. Transformations of the resulting peracetylated ANSs such as glycosylation and deacetylation are also demonstrated. Biological studies reveal that ANS-modified cholesterol show cytotoxicity against human cancer cell lines, whereas each ANS and cholesterol have no cytotoxicity.

Three cases of late-onset anthracycline-related cardiomyopathy due to chemotherapies for hematological malignancy.

BACKGROUND: Although anthracycline-related cardiomyopathy is a life-threatening complication during intensive treatment for hematological malignancies, clinical features and outcomes of this type of cardiomyopathy have been unclear because of limited reports in the literature. METHODS: We analyzed three cases of anthracycline-related cardiomyopathy among 996 patients with either acute myelogenous leukemia (285), acute lymphoblastic leukemia (37), or malignant lymphoma (674) at our hospital during the period from 2006 to 2016. RESULTS: All patients showed accumulation of anthracycline within a proper range (< 500 mg/sqm). Two patients (Hodgkin lymphoma and acute lymphoblastic leukemia) showed acute heart failure (AHF) with ejection fraction (EF) of 30 and 40% after 4.5 and 5 years after diagnosis, respectively. For AHF, diuretics and carperitide were administered to control in-out balance. The remaining patient (follicular lymphoma) showed ventricular fibrillation (VF)/ventricular tachycardia (VT) with EF of 40% at 5 years after diagnosis. In this patient, immediate cardioversion made VF/VT to normal sinus rhythm, and then, amiodarone was given. Furthermore, implantable cardioverter defibrillator was set up for VF/VT. In all patients, ß blocker and/or angiotensin-converting enzyme inhibitor (ACE-I) were administrated to prevent recurrence of anthracycline-related cardiomyopathy. Consequently, two of three patients showed mild improvement of cardiac function. CONCLUSION: Our study indicates that late-onset (4 to 5 years) anthracycline-related cardiomyopathy can develop, though range of anthracycline accumulation is in proper range. Thus, a cautious follow-up by ECG and UCG is required. Furthermore, the early treatment after the onset of anthracycline-related cardiomyopathy should be also needed to improve the poor outcome.

Uterine relapse of Philadelphia chromosome-negative acute lymphoblastic leukemia.

The relapse of acute lymphoblastic leukemia (ALL) usually involves the bone marrow, with the central nervous system being the most frequent extramedullary site. The relapse of ALL in the female genital organs, particularly the uterus, is markedly rare. We report such a patient who developed relapse in the bone marrow and uterus. The uterine lesion, which presented as abnormal uterine bleeding, consisted of a mass on MRI and proliferation of ALL cells on histology. MRI revealed a heterogeneous high-intensity mass (T2-WI/D-WI) with a diameter of 6.8 cm, a notable decrease in the apparent diffusion coefficient (ADC), and mild enhancement by contrast enhancement study. Histological findings of the uterine cervix demonstrated the infiltration of ALL. The patient achieved remission by allogeneic haplo-identical hematopoietic stem-cell transplantation, but died of complications of the transplantation. This case suggested that attention should be paid to the uterus as a site of extramedullary relapse. In addition, abnormal uterine bleeding, which is a common sign of hormonal imbalance and hormone replacement therapy after chemotherapy, may be an initial sign of extramedullary recurrence. To confirm uterine relapse as an intractable disease, the accumulation of more cases is required.

Clinical Features, Pathological Features, and Treatment Outcomes of 22 Patients with Aggressive Adult T-cell Leukemia-lymphoma Treated with a Humanized CCR4 Antibody (Mogamulizumab) at a Single Institution during a 6-year Period (2012-2018).

Objective To elucidate the clinical impact of humanized CCR4 antibody (mogamulizumab) on adult T-cell leukemia-lymphoma (ATL), we retrospectively analyzed the clinical and pathological features and treatment outcomes of aggressive ATL. Methods Twenty-two patients (median age: 65 years) with aggressive ATL [acute- (n=16) or lymphoma-type (n=6)] had their characteristics analyzed. All cases were treated with mogamulizumab at our institution from 2012 to 2018. In addition, we subjected 14 specimens of ATL to histological, immunological, and genetic analyses. Results Regarding the patient outcomes, the overall response rates were 68.1% and 31.8% after 4 and 8 courses (or after the final courses), respectively. The median overall survival (OS) was 95.5 days, while the OS rates at 6 and 12 months were 31.5% and 21.1%, respectively. Concerning patient pathological characteristics, 6 of the 14 patients examined (42.9%) had CCR4 mutations. Regarding the clinicopathological findings related to the mogamulizumab response, notably, the cases with somatic CCR4 mutation tended to have a poorer response (16.7%) than those with wild-type CCR4 (62.5%) after 4 cycles of mogamulizumab. Furthermore, the CCR4 global score tended to be higher in the responder cases than in the non-responder cases. Conclusion The present findings suggest that the CCR4 expression may be related to the mogamulizumab response, although no other significant predictive markers were identified in this study. Further studies will be needed in order to identify more markers related to the mogamulizumab response.

The clinical impact of human T-lymphotrophic virus type 1 (HTLV-1) infection on the development of adult T-cell leukemia-lymphoma (ATL) or HTLV-1-associated myelopathy (HAM) / atypical HAM after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and renal transplantation.

Because there are limited clinical reports on the impact of human T-lymphotropic virus type 1 (HTLV-1) on organ transplantation, its effects on the development of adult T-cell leukemia-lymphoma (ATL), post-transplantation lymphoproliferative disorder (PTLD) and HTLV-1-associated myelopathy (HAM) or atypical HAM after organ transplantation remain unclear.We retrospectively analyzed the impact of HTLV-1 in 54 allogeneic hematopoietic stem cell transplantation (allo-HSCT) cases and 31 renal transplantation cases between January 2006 and December 2016.Among the 54 allo-HSCT cases, nine recipients with ATL tested positive for HTLV-1, and one was found to be an HTLV-1 carrier. All donors tested negative for HTLV-1. Only one HTLV-1 carrier did not present with ATL or HAM development after allo-HSCT. Among nine ATL cases after allo-HSCT, four eventually relapsed due to proliferation of recipient-derived ATL cells. However, in one ATL case, atypical HAM developed rapidly at 5 months after allo-HSCT.Among the 31 renal transplantation cases, all donors tested negative for HTLV-1, and only recipients tested positive. Only one HTLV-1 carrier recipient did not present with ATL or HAM development after renal transplantation. However, one HTLV-1-negative recipient developed PTLD in the brain 10 years after renal transplantation.In clinical practice, careful follow-up of HTLV-1 infected recipients after organ transplantation is important because atypical HAM can develop in ATL patients after allo-HSCT. Furthermore, to clarify the risk of ATL or HAM development in HTLV-1 infected recipients, we prospectively followed up our cohort.

The Impact of a Humanized CCR4 Antibody (Mogamulizumab) on Patients with Aggressive-Type Adult T-Cell Leukemia-Lymphoma Treated with Allogeneic Hematopoietic Stem Cell Transplantation.

Although a humanized CCR4 antibody (mogamulizumab) was reported to be effective for refractory adult T-cell leukemia-lymphoma (ATL), several reports regarding the use of mogamulizumab before allo-hematopoietic stem cell transplantation (HSCT) strongly indicated a high incidence of severe acute graft-versus-host-disease (GVHD) and treatment-related mortality (TRM). We retrospectively analyzed nine aggressive-type ATL patients who underwent allo-HSCT at a single institution in Miyazaki from 2006.1.1 to 2015.7.31. Among nine ATL patients, three had used mogamulizumab before treatment with allo-HSCT because of the poor control of refractory ATL. All three patients were treated with four to eight cycles of mogamulizumab. The interval from last administration of mogamulizumab to allo-HSCT was two to five months. All three patients with prior mogamulizumab treatment developed mild-moderate acute GVHD (grade 2) 28, 34, or 40 days after allo-HSCT. Acute GVHD was controlled by prednisolone treatment. Two patients in complete remission before allo-HSCT exhibited relatively prolonged survival (survival rate, 66%). Moreover, one patient developed human T-cell leukemia virus type 1-associated myelopathy-mimicking myelitis at five months after allo-HSCT. In contrast, two of six ATL patients without a history of mogamulizumab use survived (survival rate 33%). Thus, in cases of mogamulizumab use before treatment with allo-HSCT for refractory ATL, an appropriately long interval from the last administration of mogamulizumab to allo-HSCT may be one of factors to reduce TRM by acute GVHD, and to subsequently enhance graft-versus-tumor effects in ATL cases. Furthermore, caution is needed when administering mogamulizumab before allo-HSCT for severe GVHD and TRM.

Clinical Features and Treatment Outcomes of 51 Patients with Chronic Myeloid Leukemia Treated with a Tyrosine Kinase Inhibitor at a Single Institution from 2002 to 2014.

Although clinical trials of first- and second-generation tyrosine kinase inhibitors (TKIs) have been shown to improve the prognosis of chronic myeloid leukemia (CML), there is still uncertainty about the clinical features, treatment outcomes, adverse effects, and other possible problems of their use in the clinical setting. We retrospectively analyzed 51 CML patients treated with TKIs at a single institution between 2002 and 2014. The patients (median age: 53.8 years) were classified as having chronic (n = 48), accelerated (n = 2), or blastic phase (n = 1) CML. Our treatments included both 1st generation TKIs (60.8%) and 2nd generation TKIs (39.2%). We found that the overall response rates of complete cytogenetic response (CCyR), major molecular response (MMR), and MR4 (molecular response 4) were 90.2%, 78.4%, and 64.7%, respectively. Second line 2nd generation TKIs had response rates equivalent to those of 1st line 1st generation TKIs. Moreover, 1st line 2nd generation TKIs tended to achieve an early response rate. Overall survival (OS) at 5 years was 93.2%. Sudden blastic crisis (BC) occurred in 2 CML patients receiving TKI with CCyR status. Hematopoietic stem cell transplantation was performed for BC (n = 1) and sudden BC (n = 2). Side effects of all grades (1-3) and grade 3 alone were 64.7% and 11.8%, respectively. Dose reduction, replacement with another TKI, or low dose TKI treatment may be useful methods to control side effects. Further reasons of TKI discontinuation were economic problems (n = 3) and pregnancy (n = 1). Consequently, our treatment strategy for CML demonstrated good response rate and OS. Currently, treatment discontinuation due to intolerance, resistance, economic problems, pregnancy, and sudden BC remains a concern in clinical practice.

Gender-related alterations in plasma adrenomedullin level and its correlation with body weight gain.

Plasma levels of adrenomedullin (AM), a bioactive peptide produced in adipose tissue, have been shown to be higher in obese patients than in non-obese patients, but little is known about gender differences in plasma AM levels. The aims of this study were to clarify gender-related alterations in plasma AM levels and to examine the body weight (BW) gain-plasma AM relationship in the general population. We measured plasma AM levels of 346 local residents (62.0±8.9 years, mean±s.d.) in the Kiyotake area, Japan, who underwent a regular health check-up, by a specific fluorescence immunoassay. Plasma AM levels in the female residents were lower than that in the males, and multiple regression analysis revealed a possible gender difference in plasma AM. The AM levels were significantly correlated with BMI or waist circumference in women, but such a relationship was not seen in men. When the subjects were divided into two groups by results of a questionnaire about BW gain of 10 kg or more since the age of 20 years, the plasma AM level of women with BW gain ≧10 kg was significantly higher than that in those without BW gain, although no difference was noted between the men with and without BW gain. In conclusion, possible gender differences were noted in the plasma AM levels and in the BW gain-plasma AM relationship in the general population. The plasma AM levels in the female residents without BW gain seem partly attributable to the lower AM of women.

Clinical features and outcomes of 9 patients with immunodeficiency-associated lymphoproliferative disorders treated at a single institution.

Immunodeficiency-associated lymphoproliferative disorders (LPD) represent a rare life-threatening clinical entity characterized by heterogeneous histological findings that range from polymorphic to monomorphic proliferated abnormal lymphocytes. Currently, there is no standard treatment for LPD. To elucidate the clinical features and treatment outcomes of immunodeficiency-associated LPD patients with rheumatoid arthritis (RA), we retrospectively evaluated 9 cases observed over a 5-year period. The diagnoses of these patients included 5 diffuse large B-cell lymphomas, 3 LPD, and 1 mucosa-associated lymphoid tissue lymphoma. At initial diagnosis, 6 patients had advanced-stage RA, and half of these underwent total knee arthroplasty. All patients with RA received methotrexate (MTX) and low-dose prednisolone. Biologics were administered to 4 of 9 patients. After the development of immunodeficiency-associated LPD, MTX discontinuation resulted in 5 complete remissions (CR), 1 partial remission, and 3 cases of stable disease. Relapse was observed in 3 of 5 CR patients in the MTX-withdrawal remission group. Subsequently, conventional chemotherapy, rituximab, and radiation were administered to 4, 3, and 1 patient, respectively. These treatments induced a second CR. In the chemotherapy group, 1 patient developed acute myocardial infarction and another experienced ileus and pulmonary abscess. In the rituximab group, no severe complications were observed. Consequently, all patients remained disease-free during the median 23-month follow-up period. Our results indicate that, depending on the RA disease stage, performance status, and extent of treatment response, less intensive treatments than those commonly indicated for non-Hodgkin lymphoma, involving MTX discontinuation and subsequent therapy containing rituximab, might be an efficient therapeutic strategy for immunodeficiency-associated LPD.

Sarcoidosis manifesting as cardiac sarcoidosis and massive splenomegaly.

Sarcoidosis is a multisystemic granulomatous disease of unknown etiology. We report an unusual case of sarcoidosis in a woman presenting with cardiac sarcoidosis and massive splenomegaly with a familial history of cardiac sarcoidosis. Cardiac sarcoidosis was diagnosed based on electrocardiogram, echocardiogram, 18F-fluoro-2-deoxyglucose positron emission tomography (18F-FDG-PET) and skin histological findings. We performed splenectomy to rule out malignant lymphoma, and histological findings confirmed sarcoidosis. After splenectomy, we initiated prednisolone therapy. After 20 months of diagnosis, she was symptom free. Echocardiography and 18F-FDG-PET may be a key diagnostic tool and prednisolone therapy may be safe, effective, and feasible for cardiac sarcoidosis.

Clinical features and outcomes of eosinophilic myocarditis patients treated with prednisolone at a single institution over a 27-year period.

BACKGROUND: Eosinophilic myocarditis is a rare clinical entity characterized by eosinophilia and myocardial inflammation with infiltrating eosinophils. The prognosis of patients with eosinophilic myocarditis is difficult to determine due the disease's rarity and varied causes; consequently, standard treatment has not been established. OBJECTIVE: To elucidate the clinical characteristics and treatment outcome of eosinophilic myocarditis, we retrospectively studied 7 patients fulfilling the criteria of the Japanese Circulation Society for eosinophilic myocarditis from among 64 patients admitted to our institution with eosinophilia over a 27-year period. RESULTS: The patients' ages at diagnosis ranged from 36 to 83 years (median: 52 years). The etiologies of the eosinophilic myocarditis were found to be idiopathic (3 patients), Churg-Strauss syndrome (2 patients), parasitic infection (1 patient) and chronic eosinophilic leukemia (CEL) (1 patient). In addition to treatment for the underlying disease, we also administered prednisolone at a dose appropriate to the disease severity (6 of 7 patients). The patient who was diagnosed with a parasitic infection was treated only with albendazole, because eosinophilic myocarditis was mild. The patient with CEL was positive for the FIP1 L1-PDGFRα fusion gene and was treated with imatinib. Eosinophilic cationic protein was a useful marker for assessing disease activity and treatment efficacy. At the end of the study, of the seven patients treated, six were alive (86%), giving a mean survival time of 37 ± 40 months (mean ± SD). CONCLUSION: Because eosinophilic myocarditis has various etiologies, it is essential to identify the etiology of the underlying disease. In the majority of eosinophilic myocarditis patients, administration of prednisolone may be an effective therapeutic modality producing a good outcome.

Successful treatment of non-Hodgkin's lymphoma with rituximab and dose-adjusted CHOP therapy in a patient with concomitant end-stage renal disease requiring haemodialysis.

Although malignancy is a fatal complication of end-stage renal disease (ESRD) requiring haemodialysis, successful treatment of haematological malignancies has been rarely reported. We describe the case of a 64-year-old man who presented with non-Hodgkin's lymphoma (NHL; clinical stage, IVB) concomitant with ESRD. Before chemotherapy, haemodialysis was initiated, and one course of dose-adjusted CHOP (cyclophosphamide, doxorubicin, vincristine and prednisolone) therapy followed by eight courses of rituximab therapy were administered according to the performance status and degree of organ dysfunction. Consequently, the patient was disease free for 27 months. Thus, rituximab plus CHOP combination therapy was effective for NHL concomitant with ESRD.

M-Sec promotes membrane nanotube formation by interacting with Ral and the exocyst complex.

Cell-cell communication is essential for the development and homeostasis of multicellular organisms. Recently, a new type of cell-cell communication was discovered that is based on the formation of thin membranous nanotubes between remote cells. These long membrane tethers, termed tunneling nanotubes (TNTs), form an intercellular conduit and have been shown to enable the transport of various cellular components and signals. However, the molecular basis for TNT formation remains to be elucidated. Here we report that a mammalian protein, M-Sec, induces de novo formation of numerous membrane protrusions extending from the plasma membrane, some of which tether onto adjacent cells and subsequently form TNT-like structures. Depletion of M-Sec by RNA interference (RNAi) greatly reduced endogenous TNT formation as well as intercellular propagation of a calcium flux in a macrophage cell line. Furthermore, blockage of the interaction of M-Sec with Ral and the exocyst complex, which serves as a downstream effector of Ral, attenuated the formation of membrane nanotubes. Our results reveal that M-Sec functions as a key regulator of membrane nanotube formation through interaction with the Ral-exocyst pathway.

Uptake through glycoprotein 2 of FimH(+) bacteria by M cells initiates mucosal immune response.

The mucosal immune system forms the largest part of the entire immune system, containing about three-quarters of all lymphocytes and producing grams of secretory IgA daily to protect the mucosal surface from pathogens. To evoke the mucosal immune response, antigens on the mucosal surface must be transported across the epithelial barrier into organized lymphoid structures such as Peyer's patches. This function, called antigen transcytosis, is mediated by specialized epithelial M cells. The molecular mechanisms promoting this antigen uptake, however, are largely unknown. Here we report that glycoprotein 2 (GP2), specifically expressed on the apical plasma membrane of M cells among enterocytes, serves as a transcytotic receptor for mucosal antigens. Recombinant GP2 protein selectively bound a subset of commensal and pathogenic enterobacteria, including Escherichia coli and Salmonella enterica serovar Typhimurium (S. Typhimurium), by recognizing FimH, a component of type I pili on the bacterial outer membrane. Consistently, these bacteria were colocalized with endogenous GP2 on the apical plasma membrane as well as in cytoplasmic vesicles in M cells. Moreover, deficiency of bacterial FimH or host GP2 led to defects in transcytosis of type-I-piliated bacteria through M cells, resulting in an attenuation of antigen-specific immune responses in Peyer's patches. GP2 is therefore a previously unrecognized transcytotic receptor on M cells for type-I-piliated bacteria and is a prerequisite for the mucosal immune response to these bacteria. Given that M cells are considered a promising target for oral vaccination against various infectious diseases, the GP2-dependent transcytotic pathway could provide a new target for the development of M-cell-targeted mucosal vaccines.

Activation-induced cytidine deaminase deficiency causes organ-specific autoimmune disease.

Activation-induced cytidine deaminase (AID) expressed by germinal center B cells is a central regulator of somatic hypermutation (SHM) and class switch recombination (CSR). Humans with AID mutations develop not only the autosomal recessive form of hyper-IgM syndrome (HIGM2) associated with B cell hyperplasia, but also autoimmune disorders by unknown mechanisms. We report here that AID-/- mice spontaneously develop tertiary lymphoid organs (TLOs) in non-lymphoid tissues including the stomach at around 6 months of age. At a later stage, AID-/- mice develop a severe gastritis characterized by loss of gastric glands and epithelial hyperplasia. The disease development was not attenuated even under germ-free (GF) conditions. Gastric autoantigen -specific serum IgM was elevated in AID-/- mice, and the serum levels correlated with the gastritis pathological score. Adoptive transfer experiments suggest that autoimmune CD4+ T cells mediate gastritis development as terminal effector cells. These results suggest that abnormal B-cell expansion due to AID deficiency can drive B-cell autoimmunity, and in turn promote TLO formation, which ultimately leads to the propagation of organ-specific autoimmune effector CD4+ T cells. Thus, AID plays an important role in the containment of autoimmune diseases by negative regulation of autoreactive B cells.