Requirement for lymphoid tissue-inducer cells in isolated follicle formation and T cell-independent immunoglobulin A generation in the gut.

Immunoglobulin A (IgA) is generated in the gut by both T cell-dependent and T cell-independent processes. The sites and the mechanisms for T cell-independent IgA synthesis remain elusive. Here we show that isolated lymphoid follicles (ILFs) were sites where induction of activation-induced cytidine deaminase (AID) and IgA class switching of B cells took place in the absence of T cells. We also show that formation of ILFs was regulated by interactions between lymphoid tissue-inducer cells expressing the nuclear receptor ROR gamma t (ROR gamma t(+)LTi cells) and stromal cells (SCs). Activation of SCs by ROR gamma t(+)LTi cells through lymphotoxin (LT)-beta receptor (LT beta R) and simultaneously by bacteria through TLRs induced recruitment of dendritic cells (DCs) and B cells and formation of ILFs. These findings provide insight into the crosstalk between bacteria, ROR gamma t(+)LTi cells, SCs, DCs, and B cells required for ILF formation and establish a critical role of ILFs in T cell-independent IgA synthesis in gut.

Regulation of B1 cell migration by signals through Toll-like receptors.

Peritoneal B1 cells are known to generate large amounts of antibodies outside their residential site. These antibodies play an important role in the early defense against bacteria and viruses, before the establishment of adaptive immune responses. Although many stimuli, including antigen, lipopolysaccharide, or cytokines, have been shown to activate B1 cells and induce their differentiation into plasma cells, the molecular signals required for their egress from the peritoneal cavity are not understood. We demonstrate here that direct signals through Toll-like receptors (TLRs) induce specific, rapid, and transient down-regulation of integrins and CD9 on B1 cells, which is required for detachment from local matrix and a high velocity movement of cells in response to chemokines. Thus, we revealed an unexpected role for TLRs in governing the interplay between integrins, tetraspanins, and chemokine receptors required for B1 cell egress and, as such, in facilitating appropriate transition from innate to adaptive immune responses.

RBP-J promotes neuronal differentiation and inhibits oligodendroglial development in adult neurogenesis.

Neurogenesis persists in restricted regions of the adult vertebrate brain. However, the molecular mechanisms supporting adult neurogenesis are not fully understood. Here we demonstrated that C cell-specific deletion of RBP-J in the adult subventricular zones (SVZs) caused reduction in numbers of mature granule cells in the olfactory bulbs (OBs) with concomitant increase in Olig2(+) oligodendroglial progenitors, although generation of immature neurons was enhanced in the SVZs. Adenovirus-mediated Cre introduction to the SVZs of RBP-J-floxed mice indicated that Olig2(+) cells in the OBs can be generated from RBP-J-deficient SVZs, although no oligodendroglial cells in the OBs are derived from the normal SVZs. This preferential differentiation to oligodendroglial progenitor cells and reduction in differentiation of mature neurons were also confirmed by in vitro culture of RBP-J-deficient SVZ-derived neural progenitor cells, in addition to defects in the maintenance of adult neural stem cell population. The defects in maturation of RBP-J-deficient neurons could be partly rescued by knockdown of Olig2 in vivo. Our findings suggest that RBP-J might regulate neuronal maturation at least in part through transcriptional repression of Olig2.

Inhibition of Notch/RBP-J signaling induces hair cell formation in neonate mouse cochleas.

Mammalian inner ear hair cells in cochleas are believed to be incapable of regeneration after birth, which hampers treatment of sensorineural hearing impairment mainly caused by hair cell loss. Sensory epithelia of cochleas are composed of hair cells and supporting cells, both of which originate from common progenitors. Notch/RBP-J signaling is an evolutionally conserved pathway involved in specification of various cell types in developmental stage and even in some of postnatal mammalian organs. The specification of hair cell fate from the progenitors is inhibited by Notch/RBP-J signaling in embryonic inner ears. However, its function in postnatal inner ears is unknown. We showed that inhibition of Notch/RBP-J signaling, by either conditional disruption of the Rbpsuh gene or treatment with a gamma-secretase inhibitor, could give rise to ectopic hair cells in the supporting cell region in organs of Corti from neonatal mouse cochleas where hair cells have not been considered to regenerate after birth. We also showed that down-regulation of Hes5 and up-regulation of Math1 were associated with ectopic hair cell induction. These results suggest that Notch/RBP-J signaling inhibits supporting cells from differentiation into hair cells even in postnatal days, implying that inhibitors of Notch/RBP-J signaling can be used to help regenerating hair cells after birth and thus serve for potential treatment of intractable sensorineural hearing impairment caused by hair cell loss without genetical manipulation.

Two cases of subcutaneous trichoblastoma.

This report concerns two Japanese women, 54 and 53 years old, with trichoblastoma. Histopathologically, these neoplasms were mainly composed of follicular germinative cells with fibrotic stroma. One of them was a giant lesion, but the other was small. Because both lesions were located in the subcutis, we termed them subcutaneous trichoblastoma.

Ocular neuromyotonia treated by microvascular decompression: usefulness of preoperative 3D imaging: case report.

Ocular neuromyotonia is a rare ocular motility disorder characterized by involuntary contraction of extraocular muscles resulting in paroxysmal diplopia. Although ocular neuromyotonia is reported as a rare complication after radiation therapy, there are a few cases of ocular neuromyotonia in the absence of irradiation. In the reported cases the possibility of vascular compression has been suggested on radiological imaging. The authors report a case of ocular neuromyotonia treated by microvascular decompression of the third cranial nerve, supporting the hypothesis that neurovascular compression may play a role in its pathogenesis. The usefulness of preoperative 3D imaging for microvascular decompression is also discussed.

Preferential generation of follicular B helper T cells from Foxp3+ T cells in gut Peyer's patches.

Most of the immunoglobulin A (IgA) in the gut is generated by B cells in the germinal centers of Peyer's patches through a process that requires the presence of CD4+ follicular B helper T(TFH) cells. The nature of these T(FH) cells in Peyer's patches has been elusive. Here, we demonstrate that suppressive Foxp3+CD4+ T cells can differentiate into TFH cells in mouse Peyer's patches. The conversion of Foxp3+ T cells into TFH cells requires the loss of Foxp3 expression and subsequent interaction with B cells. Thus, environmental cues present in gut Peyer's patches promote the selective differentiation of distinct helper T cell subsets, such as TFH cells.

Dynamic interactions between bacteria and immune cells leading to intestinal IgA synthesis.

The gastrointestinal tract is colonized by an immense number of bacteria that are in a constant dialog with our immune cells. One obvious question is how the mucosal immune system maintains a state of hypo-responsiveness toward the commensal bacteria and a state of readiness that allows efficient and prompt responses against pathogens. The answers have important implications for immunologists who seek to understand the fundamental aspects of bacteria-immune cell interactions in the steady-state condition and wish to elucidate the patho-physiologic mechanisms in immune disregulations, such as inflammatory bowel diseases. An important adjustment of the immune system to bacterial colonization of the gut is the "constitutive" production of IgA by the gut-associated lymphoid tissues (GALT). In this review, we summarize the sites and mechanisms for IgA synthesis in mice. We emphasize the important role played by secretory IgAs in maintenance of an appropriate intestinal microbiota, which is required for local and systemic immune homeostasis.

Intestinal IgA synthesis: a primitive form of adaptive immunity that regulates microbial communities in the gut.

Our intestine is colonized by an impressive community of bacteria, that has profound effects on the immune functions. The relationship between gut microbiota and the immune system is one of reciprocity: bacteria have important contribution in nutrient processing and education of the immune system and conversely, the immune system, particularly gut-associated lymphoid tissues (GALT) plays a key role in shaping the repertoire of gut microbiota. In this review we discuss new insights into the role of IgA in the maintenance of immune homeostasis and the reciprocal interactions between gut B cells and intestinal bacteria.

Msx2-interacting nuclear target protein (Mint) deficiency reveals negative regulation of early thymocyte differentiation by Notch/RBP-J signaling.

Notch/RBP-J signaling is required for generation of early T progenitors (ETP) and promotion of double-negative (DN) 4 cells from DN3 cells in thymocyte differentiation. However, whether Notch affects other steps during thymocyte differentiation remains unknown. Msx2-interacting nuclear target protein (Mint) is an endogenous inhibitor of Notch regulation. Concordantly, by ex vivo analyses of embryonic thymi and in vitro differentiation studies of fetal liver progenitors, we find that Mint deficiency enhances generation of ETP and DN4 cells. Unexpectedly, however, Mint deficiency impairs differentiation of ETP into DN2 cells, suggesting that Notch/RBP-J signaling negatively regulates DN1-DN2 transition.

The interleukin-4 enhancer CNS-2 is regulated by Notch signals and controls initial expression in NKT cells and memory-type CD4 T cells.

Epigenetic changes in chromatin structure at the T helper (Th2) locus correlate with interukin-4 (IL-4) and IL-13 expression during Th2 differentiation. By using a transgenic green fluorescence protein (GFP) reporter system, we show that conserved noncoding sequence-2 (CNS-2), located downstream of the Il4 locus, is a constitutively active enhancer in NKT cells as well as in a subset of CD44(hi) memory phenotype CD4+ T cells. CNS-2 enhancer activity and initial IL-4 expression in CD44(hi) CD4+ T cells were abolished in mice with a CD4-specific deletion of the transcriptional mediator of Notch signaling, Rbp-j. Depletion of CNS-2 active CD4+ T cells markedly decreased Th2 differentiation from naive CD4 T cells and antigen-specific IgE production after in vivo priming. These findings indicate that Notch-regulated CNS-2 enhancer controls initial IL-4 expression in NKT and memory phenotype CD4+ T cells and that CNS-2 active CD44(hi) memory phenotype T cells are important in facilitating Th2 differentiation of naive CD4+ T cells in allergic responses.

Solitary myofibromatosis of the skull: a case report and review of literature.

CASE REPORT: We present a case of solitary myofibromatosis of the skull in a 4-year-old girl. Surgery was performed and the final diagnosis of myofibromatosis was made histopathologically. DISCUSSION: Solitary myofibromatosis of the skull is rare and we found approximately 20 reported cases in the English-language literature. We reviewed eight well-described cases. CONCLUSION: Neuroradiologically, common features such as a lytic lesion with a sclerotic rim on roentgenogram and intra-diploic lesion with periosteal new bone formation both in the outer and inner table of the skull on computed assisted tomography are noticed.

Expression of messenger RNA for prostaglandin E receptor subtypes EP4/EP2 and cyclooxygenase isozymes in mouse periovulatory follicles and oviducts during superovulation.

Prostaglandin (PG) E(2) is synthesized from arachidonic acid by cyclooxygenase (COX) and acts as a regulator in ovulation and fertilization reactions. We present the temporal and regional expression patterns of mRNAs for the two Gs-coupled PGE receptors, EP2 and EP4, and for COX-1 and COX-2 in mouse periovulatory follicles and oviducts during superovulation. Analysis using reverse transcription polymerase chain reaction revealed that the mouse ovaries express a significant amount of EP4 mRNA in addition to EP2 mRNA during superovulation. In situ hybridization results revealed that the signals for EP4 mRNA were localized mostly to oocytes in the preantral follicles. Three hours after hCG injection, the signals for EP4 and EP2 mRNA were present in both granulosa and cumulus cells. However, 9 h after hCG injection, just before ovulation, the signals for EP4 mRNA were still detectable in both cell types, whereas those for EP2 mRNA were found only in cumulus cells. COX-2 mRNA expression was present in both granulosa and cumulus cells at 3 h but was present only in cumulus cells at 9 h. COX-1 mRNA expression was not found in granulosa cells at 3 h but was found in these cells at 9 h. In the oviduct, the expression of EP4 and COX-1 mRNA was localized to epithelial cells, whereas expression of EP2 mRNA was localized to the smooth muscle layer. The tightly regulated expression of both EP2 and EP4 in the preovulatory follicles may reflect the essential role of PGE(2) in the ovulation process.

Regulation of alphabeta/gammadelta T cell lineage commitment and peripheral T cell responses by Notch/RBP-J signaling.

RBP-J is a key mediator of Notch signaling that regulates a large spectrum of cell fate determinations. To elucidate the functions of Notch signaling in T cell development, we inactivated RBP-J specifically at two stages of T cell development by crossing RBP-J floxed mice with lck-cre or CD4-cre transgenic mice. The loss of RBP-J at an earlier developmental stage resulted in enhanced generation and accelerated emigration of gammadelta T cells, whereas alphabeta T cell development was arrested at the double-negative 3 stage. The loss of RBP-J at a later stage did not affect the absolute number or the production rate of CD4 or CD8-positive mature T cells but enhanced Th1 cell response and reduced CD4(+) T cell proliferation. Our data demonstrated that Notch/RBP-J signaling regulates gammadelta T cell generation and migration, alphabeta T cell maturation, terminal differentiation of CD4(+) T cells into Th1/Th2 cells, and activation of T cells.

Neural precursor cells derived from human embryonic brain retain regional specificity.

Recent studies have revealed that neural precursor cells can be expanded not only from the subventricular zone and hippocampus but also from other regions of the human embryonic brain. To determine the regional differences of these precursor cells, we divided the brain of a 9-week-old human embryo into four parts, i.e., telencephalon, diencephalon, mesencephalon, and rhombencephalon. All cultures of the tissues yielded neurospheres, and these spheres gave rise to neurons, astrocytes, and oligodendrocytes. An analysis of clonal populations revealed that these precursor cells were multipotent, and two region-specific differences in neural precursor cells were revealed: 1) The precursor cells from the rostral part of the brain tended to proliferate faster than those from the caudal part, and 2) the precursor cells from the diencephalon and mesencephalon gave rise to more tyrosine hydoxylase (TH)-positive neurons than those from the telencephalon and rhombencephalon. When 50-day-cultured spheres were caused to differentiate, the percentage of TH-positive cells per total cell population was 1.2% for diencephalic and mesencephalic precursors, whereas it was 0.4% for telencephalic and rhombencephalic ones. Furthermore, the TH-positive cells from diencephalic and mesencephalic precursors were large, multipolar, and gamma-aminobutyric acid (GABA)-negative, which suggested that these cells were midbrain dopaminergic neurons. In contrast, TH-positive cells from telencephalic and rhombencephalic precursors were small, bipolar, and GABA-positive. These results suggest that human neural precursor cells might have the potential to differentiate into a variety of cells but retain regional specificity.

Stem cell-derived neural stem/progenitor cell supporting factor is an autocrine/paracrine survival factor for adult neural stem/progenitor cells.

Recent evidence suggests that adult neural stem/progenitor cells (ANSCs) secrete autocrine/paracrine factors and that these intrinsic factors are involved in the maintenance of adult neurogenesis. We identified a novel secretory molecule, stem cell-derived neural stem/progenitor cell supporting factor (SDNSF), from adult hippocampal neural stem/progenitor cells by using the signal sequence trap method. The expression of SDNSF in adult central nervous system was localized to hippocampus including dentate gyrus, where the neurogenesis persists throughout life. In induced neurogenesis status seen in ischemically treated hippocampus, the expression of SDNSF was up-regulated. As functional aspects, SDNSF protein provided a dose-dependent survival effect for ANSC following basic fibroblast growth factor 2 (FGF-2) withdrawal. ANSCs treated by SDNSF also retain self-renewal potential and multipotency in the absence of FGF-2. However, SDNSF did not have mitogenic activity, nor was it a cofactor that promoted the mitogenic effects of FGF-2. These data suggested an important role of SDNSF as an autocrine/paracrine factor in maintaining stem cell potential and lifelong neurogenesis in adult central nervous system.