Increased IL-10-competent regulatory B cells in the decidua of early human pregnancy

Regulatory B cells (Bregs) may play a pivotal role in maintaining human pregnancy. For the first time, to the best of our knowledge, this study noted that cell percentages of CD24hiCD38hi Bregs and CD24hiCD27+ Bregs, which can potentially produce IL-10, are increased in human decidua compared with the mid-luteal phase endometrium. In each case of decidua, the correlation between Bregs and dendritic cell (DC) or natural killer (NK) cell expression was further explored. A positive correlation between the percentage of CD24hiCD38hi Bregs and CD123-CD11c+ myeloid DCs (mDCs) was noted. Furthermore, a significant positive correlation was also observed between the percentage of CD24hiCD27+ Bregs and CD94+CD56brightCD16- suppressive NK cells. These findings regarding decidual Bregs deepen the understanding of the harmonious immunological microenvironment that sustains early human pregnancy.

Refeeding activates neurons in the dorsomedial hypothalamus to inhibit food intake and promote positive valence

Objective

The regulation of food intake is a major research area in the study of obesity, which plays a key role in the development of metabolic syndrome. Gene targeting studies have clarified the roles of hypothalamic neurons in feeding behavior, but the deletion of a gene has a long-term effect on neurophysiology. Our understanding of short-term changes such as appetite under physiological conditions is therefore still limited.

Methods

Targeted recombination in active populations (TRAP) is a newly developed method for labeling active neurons by using tamoxifen-inducible Cre recombination controlled by the promoter of activity-regulated cytoskeleton-associated protein (Arc/Arg3.1), a member of immediate early genes. Transgenic mice for TRAP were fasted overnight, re-fed with normal diet, and injected with 4-hydroxytamoxifen 1 h after the refeeding to label the active neurons. The role of labeled neurons was examined by expressing excitatory or inhibitory designer receptors exclusively activated by designer drugs (DREADDs). The labeled neurons were extracted and RNA sequencing was performed to identify genes that are specifically expressed in these neurons.

Results

Fasting-refeeding activated and labeled neurons in the compact part of the dorsomedial hypothalamus (DMH) that project to the paraventricular hypothalamic nucleus. Chemogenetic activation of the labeled DMH neurons decreased food intake and developed place preference, an indicator of positive valence. Chemogenetic activation or inhibition of these neurons had no influence on the whole-body glucose metabolism. The labeled DMH neurons expressed prodynorphin (pdyn), gastrin-releasing peptide (GRP), cholecystokinin (CCK), and thyrotropin-releasing hormone receptor (Trhr) genes.

Conclusions

We identified a novel cell type of DMH neurons that can inhibit food intake and promote feeding-induced positive valence. Our study provides insight into the role of DMH and its molecular mechanism in the regulation of appetite and emotion.

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Fasting-refeeding activates a subset of neurons in the dorsomedial hypothalamus (DMH).

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Chemogenetic inhibition of the DMH neurons increases food intake.

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Chemogenetic activation of the DMH neurons inhibits food intake and promotes positive valence.

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The DMH neurons express pdyn, GRP, CCK and Trhr genes.

Prostaglandin in the ventromedial hypothalamus regulates peripheral glucose metabolism

The hypothalamus plays a central role in monitoring and regulating systemic glucose metabolism. The brain is enriched with phospholipids containing poly-unsaturated fatty acids, which are biologically active in physiological regulation. Here, we show that intraperitoneal glucose injection induces changes in hypothalamic distribution and amounts of phospholipids, especially arachidonic-acid-containing phospholipids, that are then metabolized to produce prostaglandins. Knockdown of cytosolic phospholipase A2 (cPLA2), a key enzyme for generating arachidonic acid from phospholipids, in the hypothalamic ventromedial nucleus (VMH), lowers insulin sensitivity in muscles during regular chow diet (RCD) feeding. Conversely, the down-regulation of glucose metabolism by high fat diet (HFD) feeding is improved by knockdown of cPLA2 in the VMH through changing hepatic insulin sensitivity and hypothalamic inflammation. Our data suggest that cPLA2-mediated hypothalamic phospholipid metabolism is critical for controlling systemic glucose metabolism during RCD, while continuous activation of the same pathway to produce prostaglandins during HFD deteriorates glucose metabolism.

The ventromedial hypothalamus regulates systemic glucose metabolism. Here the authors show that cytosolic phospholipase A2 mediated phospholipid metabolism contributes to this regulation in healthy animals but exert deteriorating effects on glucose homeostasis under high-fat-diet feeding.

Effector TH17 Cells Give Rise to Long-Lived TRM Cells that Are Essential for an Immediate Response against Bacterial Infection

Adaptive immunity provides life-long protection by generating central and effector memory T cells and the most recently described tissue resident memory T (T_RM) cells. However, the cellular origin of CD4 T_RM cells and their contribution to host defense remain elusive. Using IL-17A tracking-fate mouse models, we found that a significant fraction of lung CD4 T_RM cells derive from IL-17A-producing effector (T_H17) cells following immunization with heat-killed Klebsiella pneumonia (Kp). These exT_H17 T_RM cells are maintained in the lung by IL-7, produced by lymphatic endothelial cells. During a memory response, neither antibodies, γδ T cells, nor circulatory T cells are sufficient for the rapid host defense required to eliminate Kp. Conversely, using parabiosis and depletion studies, we demonstrated that exT_H17 T_RM cells play an important role in bacterial clearance. Thus, we delineate the origin and function of airway CD4 T_RM cells during bacterial infection, offering novel strategies for targeted vaccine design.

Immunological association of inducible bronchus-associated lymphoid tissue organogenesis in Ag85B-rHPIV2 vaccine-induced anti-tuberculosis mucosal immune responses in mice

We previously reported that Ag85B-expressing human parainfluenza type 2 virus (Ag85B-rHPIV2) was effective as a nasal vaccine against tuberculosis in mice; however, the mechanism by which it induces an immune response remains to be investigated. In the present study, we found that organogenesis of inducible bronchus-associated lymphoid tissue (iBALT) played a role in the induction of antigen-specific T cells and IgA antibody responses in the lung of mice intra-nasally administered Ag85B-rHPIV2. We found that expression of Ag85B was dispensable for the development of iBALT, suggesting that HPIV2 acted as an iBALT-inducing vector. When iBALT organogenesis was disrupted in Ag85B-rHPIV2-immunized mice, either by neutralization of the lymphotoxin pathway or depletion of CD11b⁺ cells, Ag85B-specific immune responses (i.e. IFN γ-producing T cells and IgA antibody) were diminished in the lung. Furthermore, we found that immunization with Ag85B-rHPIV2 induced neutrophil and eosinophil infiltration temporally after the immunization in the lung. Thus, our results show that iBALT organogenesis contributes to the induction of antigen-specific immune responses by Ag85B-rHPIV2 and that Ag85B-rHPIV2 provokes its immune responses without inducing long-lasting inflammation.

Migrant memory B cells secrete luminal antibody in the vagina

Antibodies secreted into mucosal barriers serve to protect the host from a variety of pathogens, and are the basis for successful vaccines1. In type I mucosa (such as the intestinal tract), dimeric IgA secreted by local plasma cells is transported through polymeric immunoglobulin receptors2 and mediates robust protection against viruses3,4. However, owing to the paucity of polymeric immunoglobulin receptors and plasma cells, how and whether antibodies are delivered to the type II mucosa represented by the lumen of the lower female reproductive tract remains unclear. Here, using genital herpes infection in mice, we show that primary infection does not establish plasma cells in the lamina propria of the female reproductive tract. Instead, upon secondary challenge with herpes simplex virus 2, circulating memory B cells that enter the female reproductive tract serve as the source of rapid and robust antibody secretion into the lumen of this tract. CD4 tissue-resident memory T cells secrete interferon-γ, which induces expression of chemokines, including CXCL9 and CXCL10. Circulating memory B cells are recruited to the vaginal mucosa in a CXCR3-dependent manner, and secrete virus-specific IgG2b, IgG2c and IgA into the lumen. These results reveal that circulating memory B cells act as a rapidly inducible source of mucosal antibodies in the female reproductive tract.

Memory B cell recruitment to the vaginal mucosa is required for luminal antibody secretion

Antibodies secreted into the mucosal barriers serve to protect the host from a variety of pathogens, and are the basis for successful vaccines. In type I mucosa such as the intestinal tract, dimeric IgA secreted by local plasma cells is transported through polymeric Ig receptors (pIgR). However, due to the paucity of pIgR and plasma cells, how and whether antibodies are delivered to the type II mucosa represented by the lower female reproductive tract (FRT) lumen remains unclear. Here, using genital herpes infection in mice, we show that primary infection does not establish plasma cells in the lamina propria of FRT. Instead, upon secondary challenge with herpes simplex virus 2 (HSV-2), circulating memory B cells that enter the FRT serve as the source of rapid and robust antibody secretion into the FRT lumen. CD4 tissue-resident memory T cells (TRM) secrete interferon gamma (IFN-γ), which induces expression of chemokines including CXCL9 and CXCL10. Circulating memory B cells are recruited to the vaginal mucosa in CXCR3-dependent manner, and secrete virus-specific IgG2b, IgG2c and IgA into the FRT lumen. These results reveal circulating memory B cells as a rapidly inducible source of mucosal antibodies for the FRT.

Rapid Quantification of NETs In Vitro and in Whole Blood Samples by Imaging Flow Cytometry

Neutrophil extracellular trap (NET) formation involves the release of DNA outside the cell to neutralize pathogens. Techniques such as live microscopy, flow cytometry, and intravital imaging allow the characterization of NETs, but these either cannot be applied in vivo, lack specificity or require invasive procedures. We developed an automated analysis method to rapidly acquire and characterize cells as NETs or NET precursors, as opposed to cells undergoing other forms of cell death, using imaging flow cytometry. NETs were maintained in solution using a novel three-dimensional cell culture system in which cells are suspended at the interface of two liquids of different density. Critically, we identify NETs using an image analysis algorithm based on morphological data showing the extrusion of DNA beyond the cell boundaries. In vitro, we used this technique to demonstrate different requirements for NET formation in human and mouse neutrophils. We also measured NETs in whole blood during infection of mice with the malaria parasite Plasmodium yoelii. We expect this technique will provide a valuable approach to better understand the process of NET formation and its importance in disease. © 2019 International Society for Advancement of Cytometry.

Characterisation of Kiss1r (Gpr54)-Expressing Neurones in the Arcuate Nucleus of the Female Rat Hypothalamus

Kisspeptin is essential in reproduction and acts by stimulating neurones expressing gonadotrophin-releasing hormone (GnRH). Recent studies suggest that kisspeptin has multiple roles in the modulation of neuronal circuits in systems outside the hypothalamic-pituitary-gonadal axis. Our recent research using in situ hybridisation (ISH) clarified the histological distribution of Kiss1r (Gpr54)-expressing neurones in the rat brain that were presumed to be putative targets of kisspeptin. The arcuate nucleus (ARN) of the hypothalamus is one of the brain regions in which Kiss1r expression in non-GnRH neurones is prominent. However, the characteristics of Kiss1r-expressing neurones in the ARN remain unclear. The present study aimed to determine the neurochemical characteristics of Kiss1r-expressing neurones in the ARN using ISH and immunofluorescence. We revealed that the majority (approximately 63%) of Kiss1r-expressing neurones in the ARN were pro-opiomelanocortin (POMC) neurones, which have an anorexic effect in mammals. Additionally, a few Kiss1r-expressing neurones in the dorsal ARN are tuberoinfundibular dopamine (TIDA) neurones, which control milk production by inhibiting prolactin secretion from the anterior pituitary. TIDA neurones showed a relatively weak Kiss1r ISH signal compared to POMC neurones, as well as low co-expression of Kiss1r (approximately 15%). We also examined the expression of Kiss1r in neuropeptide Y and kisspeptin neurones, which are reported to arise from POMC-expressing progenitor cells during development. However, the vast majority of neuropeptide Y and kisspeptin neurones in the ARN did not express Kiss1r. These results suggest that kisspeptin may directly regulate energy homeostasis and milk production by modulating the activity of POMC and TIDA neurones, respectively. Our results provide an insight into the wide variety of roles that kisspeptin plays in homeostatic and neuroendocrine functions.

Divergence of helper, cytotoxic, and regulatory T cells in the decidua from miscarriage

PROBLEM

The aim of this prospective study was to evaluate phenotypic differences of helper T (Th), cytotoxic T (Tc), and regulatory T (Treg) cells in the deciduae of missed miscarriage with a normal chromosome karyotype of a fetus (MN) and missed miscarriage with an abnormal chromosome karyotype of a fetus (MA).

METHODS OF STUDY

The decidua of 19 MN and 28 MA was obtained. Additionally, the decidua of 15 induced abortion (IA) and the endometrium of 19 non-pregnant women (EM) were obtained. IFN-γ(+) , IL-17(+) , CD25(high) Foxp3(+) cells in CD4(+) (Th) cells, and IFN-γ(+) cells in CD8(+) (Tc) cells were evaluated by flow cytometry.

RESULTS

The percentages of IFN-γ(+) Tc and CD4(+) CD25(high) Foxp3(+) (Treg) cells in MN were significantly increased as compared with MA and IA. The percentage of IFN-γ(+) Th in MN was increased as compared with IA.

CONCLUSION

Activation of IFN-γ(+) Tc and Treg cells in the decidua might be associated with the pathophysiology underlying MN.

Mapping of Kisspeptin Receptor mRNA in the Whole Rat Brain and its Co-Localisation with Oxytocin in the Paraventricular Nucleus

The neuropeptide kisspeptin and its receptor play an essential role in reproduction as a potent modulator of the gonadotrophin-releasing hormone (GnRH) neurone. In addition to its reproductive function, kisspeptin signalling is also involved in extra-hypothalamic-pituitary-gonadal (HPG) axis systems, including oxytocin and arginine vasopressin (AVP) secretion. By contrast to the accumulating information for kisspeptin neurones and kisspeptin fibres, the histological distribution and function of the kisspeptin receptor in the rat brain remain poorly characterised. Using in situ hybridisation combined with immunofluorescence, the present study aimed to determine the whole brain map of Kiss1r mRNA (encoding the kisspeptin receptor), and to examine whether oxytocin or AVP neurones express Kiss1r. Neurones with strong Kiss1r expression were observed in several rostral brain areas, including the olfactory bulb, medial septum, diagonal band of Broca and throughout the preoptic area, with the most concentrated population being around 0.5 mm rostral to the bregma. Co-immunofluorescence staining revealed that, in these rostral brain areas, the vast majority of the Kiss1r-expressing neurones co-expressed GnRH. Moderate levels of Kiss1r mRNA were also noted in the rostral periventricular area, paraventricular nucleus (PVN), and throughout the arcuate nucleus. Relatively weak Kiss1r expression was observed in the supraoptic nucleus and supramammillary nuclei. Moderate to weak expression of Kiss1r was also observed in several regions in the midbrain, including the periaqueductal gray and dorsal raphe nucleus. We also examined whether oxytocin and AVP neurones in the PVN co-express Kiss1r. Immunofluorescence revealed the co-expression of Kiss1r in a subset of the oxytocin neurones but not in the AVP neurones in the PVN. The present study provides a fundamental anatomical basis for further examination of the kisspeptin signalling system in the extra-HPG axis, as well as in reproductive function.

Tissue instruction for migration and retention of TRM cells

During infection, a subset of effector T cells seeds the lymphoid and non-lymphoid tissues and gives rise to tissue-resident memory T cells (TRM). Recent findings have provided insight into the molecular and cellular mechanisms underlying tissue instruction of TRM cell homing, as well as the programs involved in their retention and maintenance. We review these findings here, highlighting both common features and distinctions between CD4 TRM and CD8 TRM cells. In this context we examine the role of memory lymphocyte clusters (MLCs), and propose that the MLCs serve as an immediate response center consisting of TRM cells on standby, capable of detecting incoming pathogens and mounting robust local immune responses to contain and limit the spread of infectious agents.

T cell memory. A local macrophage chemokine network sustains protective tissue-resident memory CD4 T cells

CD8 tissue-resident memory T (T(RM)) cells provide efficient local control of viral infection, but the role of CD4 T(RM) is less clear. Here, by using parabiotic mice, we show that a preexisting pool of CD4 T(RM) cells in the genital mucosa was required for full protection from a lethal herpes simplex virus 2 (HSV-2) infection. Chemokines secreted by a local network of macrophages maintained vaginal CD4 T(RM) in memory lymphocyte clusters (MLCs), independently of circulating memory T cells. CD4 T(RM) cells within the MLCs were enriched in clones that expanded in response to HSV-2. Our results highlight the need for vaccine strategies that enable establishment of T(RM) cells for protection from a sexually transmitted virus and provide insights as to how such a pool might be established.

High-risk human papillomavirus E6 inhibits monocyte differentiation to Langerhans cells

High-risk human papillomaviruses (HPVs) cause a variety of malignancies of the mucosal epithelium. However, the local immune evasion strategies used by HPV-transformed cells remain unclear. Here, we examined the effect of HPV-positive cancer cells on human peripheral blood monocytes, which are precursors of Langerhans cells, key antigen-presenting cells in the squamous epithelium. HPV-positive cervical cancer cells and HPV-E6 expressing cells inhibited monocyte differentiation to Langerhans cells in a contact-dependent manner. Unlike Langerhans cells, monocytes that differentiated in the presence of HPV16 E6-expressing cells exhibited high levels of endocytic activity. Our results suggest that cells infected by high-risk HPV evade immune surveillance by blocking the differentiation of monocytes into competent antigen presenting cells.

Identification, localisation and functional implication of 26RFa orthologue peptide in the brain of zebra finch (Taeniopygia guttata)

Several neuropeptides with the C-terminal Arg-Phe-NH(2) (RFa) sequence have been identified in the hypothalamus of a variety of vertebrates. The present study was conducted to isolate novel RFa peptides from the zebra finch brain. Peptides were isolated by immunoaffinity purification using an antibody that recognises avian RFa peptides. The isolated peptide consisted of 25 amino acids with RFa at its C-terminus. The sequence was SGTLGNLAEEINGYNRRKGGFTFRFa. Alignment of the peptide with vertebrate 26RFa has revealed that the identified peptide is the zebra finch 26RFa. We also cloned the precursor cDNA encoding this peptide. Synteny analysis of the gene showed a high conservation of this gene among vertebrates. In addition, we cloned the cDNA encoding a putative 26RFa receptor, G protein-coupled receptor 103 (GPR103) in the zebra finch brain. GPR103 cDNA encoded a 432 amino acid protein that has seven transmembrane domains. In situ hybridisation analysis in the brain showed that the expression of 26RFa mRNA is confined to the anterior-medial hypothalamic area, ventromedial nucleus of the hypothalamus and the lateral hypothalamic area, the brain regions that are involved in the regulation of feeding behaviour, whereas GPR103 mRNA is distributed throughout the brain in addition to the hypothalamic nuclei. When administered centrally in free-feeding male zebra finches, 26RFa increased food intake 24 h after injection without body mass change. Diencephalic GPR103 mRNA expression was up-regulated by fasting for 10 h. Our data suggest that the hypothalamic 26RFa-its receptor system plays an important role in the central control of food intake and energy homeostasis in the zebra finch.

Prime and pull: establishing protective immunity in restrictive tissues (52.16)

Some of the world’s most pressing health concerns include sexually transmitted infections such as HIV and HSV. Thus far, vaccines against these pathogens, even those that elicit robust systemic cytotoxic responses, have been unsuccessful. The genital tract is a highly restrictive tissue that does not allow entry of activated CD8 T cells in the absence of infection or inflammation. Thus, it is possible that the failure of previous vaccination attempts reflects an inability to establish a tissue-resident population of cytotoxic T cells at the front line of infection within the genital tract. Thus, to address this issue, we have designed a novel vaccination method called ‘prime and pull’ to recruit antigen-specific effector CD8 T cells into the vaginal mucosa. After subcutaneous immunization (prime), very few effector CD8 T cells are observed in the genital tissue. However, a single topical application of the chemokines CXCL9 and CXCL10 in the vagina (pull) leads to robust recruitment of effector CD8 T cells, which is independent of CD4 T cell help. Furthermore, our ‘prime and pull’ method may generate a long-term population of memory CD8 T cells within the tissue that appears to enhance viral control after a lethal challenge. Thus, our studies suggest that ‘prime and pull’ is a promising method not only for providing protection against sexually transmitted infections, but also for directing immune responses to other restrictive microenvironments such as tumors.

Differential roles of migratory and resident DCs in T cell priming after mucosal or skin HSV-1 infection

Although mucosal surfaces represent the main portal of entry for pathogens, the mechanism of antigen presentation by dendritic cells (DCs) that patrol various mucosal tissues remains unclear. Instead, much effort has focused on the understanding of initiation of immune responses generated against antigens delivered by injection. We examined the contributions of migratory versus lymph node–resident DC populations in antigen presentation to CD4 and CD8 T cells after needle injection, epicutaneous infection, or vaginal mucosal herpes simplex virus (HSV) 1 infection. We show that upon needle injection, HSV-1 became lymph-borne and was rapidly presented by lymph node–resident DCs to CD4 and CD8 T cells. In contrast, after vaginal HSV-1 infection, antigens were largely presented by tissue-derived migrant DCs with delayed kinetics. In addition, migrant DCs made more frequent contact with HSV-specific T cells after vaginal infection compared with epicutaneous infection. Thus, both migrant and resident DCs play an important role in priming CD8 and CD4 T cell responses, and their relative importance depends on the mode of infection in vivo.

Dendritic cells and B cells maximize mucosal Th1 memory response to herpes simplex virus

Although the importance of cytotoxic T lymphocytes and neutralizing antibodies for antiviral defense is well known, the antiviral mechanism of Th1 remains unclear. We show that Th1 cells mediate noncytolytic antiviral protection independent of direct lysis through local secretion of IFN-gamma after herpes simplex virus (HSV) 2 infection. IFN-gamma acted on stromal cells, but not on hematopoietic cells, to prevent further viral replication and spread throughout the vaginal mucosa. Importantly, unlike other known Th1 defense mechanisms, this effector function did not require recognition of virally infected cells via MHC class II. Instead, recall Th1 response was elicited by MHC class II(+) antigen-presenting cells at the site of infection. Dendritic cells (DCs) were not required and only partially sufficient to induce a recall response from memory Th1 cells. Importantly, DCs and B cells together contributed to restimulating memory CD4 T cells to secrete IFN-gamma. In the absence of both DCs and B cells, immunized mice rapidly succumbed to HSV-2 infection and death. Thus, these results revealed a distinct mechanism by which memory Th1 cells mediate noncytolytic IFN-gamma-dependent antiviral protection after recognition of processed viral antigens by local DCs and B cells.

Dendritic cells and macrophages in the genitourinary tract

Dendritic cells (DCs) and macrophages are antigen-presenting cells (APCs) that are important in innate immune defense as well as in the generation and regulation of adaptive immunity against a wide array of pathogens. The genitourinary (GU) tract, which serves an important reproductive function, is constantly exposed to numerous agents of sexually transmitted infections (STIs). To combat these STIs, several subsets of DCs and macrophages are strategically localized within the GU tract. In the female genital mucosa, recruitment and function of these APCs are uniquely governed by sex hormones. This review summarizes the latest advances in our understanding of DCs and macrophages in the GU tract with respect to their subsets, lineage, and function. In addition, we discuss the divergent roles of these cells in immune defense against STIs as well as in maternal tolerance to the fetus.

Th1 or Th2 balance regulated by interaction between dendritic cells and NKT cells

If Th1 or Th2 polarization could be artificially manipulated, effective immune responses would be generated depending on nature of the targets. In this study we attempted to regulate CD40 expressions on dendritic cells (DCs) in order to modify the T cell response. It was found that reducing agents selectively inhibited surface expression of CD40 on DCs. This finding may provide a new strategy of DC-mediated modulation of the Th1/Th2 balance. It was also shown that NKT-produced Th1/Th2 cytokine balance was under control of negative feedback loop through DCs. Th1 cytokine-pretreated DCs mainly induced Th2 cytokine production, whereas Th2 cytokine-pretreated DCs induced Th1 cytokine production by alpha-galactosylceramide-stimulated NKT cells. The negative feedback regulation system could be applicable to therapeutics of various diseases based on immunological disorders.

Cutting Edge: Plasmacytoid dendritic cells provide innate immune protection against mucosal viral infection in situ

Dendritic cells (DCs) are powerful APCs capable of activating naive lymphocytes. Of the DC subfamilies, plasmacytoid DCs (pDCs) are unique in that they secrete high levels of type I IFNs in response to viruses but their role in inducing adaptive immunity remains divisive. In this study, we examined the importance of pDCs and their ability to recognize a virus through TLR9 in immunity against genital HSV-2 infection. We show that a low number of pDCs survey the vaginal mucosa at steady state. Upon infection, pDCs are recruited to the vagina and produce large amounts of type I IFNs in a TLR9-dependent manner and suppress local viral replication. Although pDCs are critical in innate defense against genital herpes challenge, adaptive Th1 immunity developed normally in the absence of pDCs. Thus, by way of migrating directly into the peripheral mucosa, pDCs act strictly as innate antiviral effector cells against mucosal viral infection in situ.

Low-dose lipopolysaccharide modifies the production of IL-12 by dendritic cells in response to various cytokines

Dendritic cell (DC) activation is triggered by cytokines, including tumor necrosis factor (TNF)-alpha, and microbe components, including lipopolysaccharide (LPS). During the initial stage of infection, the microbe components appear to be present at low concentration. To determine the role of low-dose microbe-components in DC activation during the initial stage of infection, we examined the effects of low-dose LPS on cytokine-induced maturation and function of DCs. Low-dose LPS (1 ng/ml) treatment of DCs had only additive effects on the expression of CD86 and major histocompatibility complex class II induced by various cytokines, including interleukin (IL)-1beta, TNF-alpha and interferon (IFN)-gamma. IL-1beta alone significantly induced IL-12 production in DCs, whereas TNF-alpha or IFN-gamma induced modest levels of IL-12 production. When low-dose LPS (1 ng/ml), which only slightly induced IL-12 production, was added to the culture, only an additive effect was seen on IL-1beta-induced IL-12 production. In contrast, low-dose LPS synergistically enhanced TNF-alpha- or IFN-gamma-induced IL-12 production. SB203580, a specific inhibitor of p38 MAPK, markedly inhibited TNF-alpha- or IFN-gamma-induced IL-12-production either in the absence or presence of LPS, but showed only modest effects on IL-beta-induced IL-12-production. These findings suggest that the p38 MAPK pathway is essential for the synergistic IL-12 production induced by TNF-alpha- or IFN-gamma in combination with low-dose LPS in DC.

CCR7-mediated c-Jun N-terminal kinase activation regulates cell migration in mature dendritic cells

c-Jun N-terminal kinase (JNK) is generally thought to be involved in inflammation, proliferation and apoptosis. However, functional role(s) of this molecule in dendritic cells (DCs) has not been well understood. CCR7 ligands, CCL19 and CCL21, induce not only chemotaxis but also endocytosis in mature DCs. In the present study, we examined the role of JNK for inducing chemotaxis and endocytosis in murine mature DCs. CCL19 rapidly enhanced endocytosis of mature DCs within a few minutes, whereas significant migration of mature DCs to this chemokine was detected 30 min or more after incubation. CCL19 significantly activated JNK in mature DCs at 15 min. CCL19 also increased interaction between phospho-JNK and phospho-mitogen-activated protein kinase kinase (MKK) 4 but not phospho-MKK7 in mature DCs, suggesting that the JNK activation is mediated via MKK4. Blocking of this JNK activation significantly inhibited the CCL19-induced migration of mature DCs. Blocking of Rho-associated kinase also inhibited the CCL19-induced migration without affecting the JNK activation. On the other hand, the inhibition of either JNK or Rho-associated kinase showed no significant effects on CCL19-induced endocytosis by mature DCs. These findings suggest that CCL19 activates JNK via a Rho-independent pathway, thereby inducing migration of mature DCs, whereas the JNK activation is dispensable for the CCL19-induced endocytosis. It seems that at least two different pathways, JNK pathway and Rho-associated kinase pathway, are involved in the CCR7-mediated migration of mature DCs. Thus, we demonstrate herein a novel role of JNK for regulating chemokine-induced DC migration.

Role of early- or late-phase activation of p38 mitogen-activated protein kinase induced by tumour necrosis factor-alpha or 2,4-dinitrochlorobenzene during maturation of murine dendritic cells

Dendritic cells (DCs) are maturated by a variety of stimuli. However, the precise mechanisms underlying the maturation of DCs are not fully understood. In the present study, we analysed the effects of tumour necrosis factor-alpha (TNF-alpha) and 2,4-dinitrochlorobenzene (DNCB) on phenotypic maturation and p38 mitogen activated protein kinase (MAPK) activity, using a murine DC line. TNF-alpha markedly increased the surface expression of major histocompatibility complex (MHC) and costimulatory molecules, CD86 and CD80, on DCs. DNCB more markedly enhanced the surface expression of costimulatory molecules, but showed less stimulatory capability on MHC molecules, compared with TNF-alpha. Simultaneous treatment of DCs with TNF-alpha and DNCB showed additive enhancement of costimulatory molecule expression. TNF-alpha activated p38 MAPK in DCs only at an early time-point (15 min). In contrast, DNCB activated p38 MAPK at later time-points (3-6 hr). SB203580, a specific inhibitor of p38 MAPK, partially or markedly inhibited the phenotypic changes of DCs induced by TNF-alpha or DNCB, respectively. In addition, N-acetyl-l-cysteine, a reducing supplier, completely inhibited the DNCB-induced expression of MHC and costimulatory molecules, but not those induced by TNF-alpha. These findings demonstrate that TNF-alpha and DNCB activate the p38 MAPK pathway at an early and a late phase, respectively, and thereby induce DC maturation through different signal pathways.

Selective regulation of CD40 expression in murine dendritic cells by thiol antioxidants

Interaction of CD40 on dendritic cells (DC) with CD40 ligand induces interleukin-12 (IL-12) production by these DC during the antigen presentation. Thus, the level of CD40 expression appears to influence the capability of DC to induce a T helper 1 (Th1) response. However, it is not fully understood how CD40 expression on DC is regulated. In the present study, we examined the effects of the reducing agents, N-acetyl-l-cysteine (NAC) and reduced glutathione (GSH), on tumour necrosis factor-alpha (TNF-alpha)-induced phenotypic changes in murine DC. TNF-alpha markedly increased the expression on DC of major histocompatibility complex (MHC) and the costimulatory molecules, CD40, CD80 and CD86. Both NAC and GSH completely abolished the TNF-alpha-induced enhancement of CD40 expression, but had no considerable effect on the expression of CD80, CD86 and MHC. The marked decrease of CD40 protein with NAC was also detected by Western blotting, but was not associated with the expression level of CD40 mRNA in DC. Thus, NAC appears to reduce CD40 expression on DC by regulating a post-transcriptional pathway. The inhibitory effect of NAC or GSH on TNF-alpha-induced CD40 expression was released by simply removing these agents from the culture. In contrast, culture of TNF-alpha-treated DC with NAC or GSH markedly decreased the expression of CD40 within 12 hr. These results demonstrate that reducing agents selectively, rapidly and reversibly regulate CD40 expression on DC, which may eventually affect the capability of DC for Th1/Th2 polarization.

Localization of group IB phospholipase A(2) isoform in the gills of the red sea bream, Pagrus (Chrysophrys) major

We previously reported that PLA(2) activity in the gills is higher than that in other tissues in red sea bream and purified PLA(2) from the gills belongs to the group IB PLA(2) as well as other red sea bream PLA(2)s. In this study, we reconfirmed that the level of PLA(2) activity is extremely high in the gills compared with other tissues, and gill PLA(2) was detected only in the gills by immunoblotting and inhibition test using anti-gill PLA(2) monoclonal antibody. The level of PLA(2) activity and protein expression in the gills are well correlated. Fish can be roughly divided into high and low groups based on the level of PLA(2) activity. Gill PLA(2) was detected in the gills of the high group, but not the low group by immunoblotting. In the gills of the high group, gill PLA(2) was detected in the mucous cells and pavement cells located on the surface of gill epithelia by immunohistochemistry. On the other hand, positive signals were observed only in the mucous cells by in situ hybridization. We also isolated inactive proPLA(2), having AR propeptide, preceding the mature enzyme from the gill extract. These results suggest that gill PLA(2) is synthesized as an inactive proPLA(2) in the mucous cells and is secreted to the surface of gill epithelia.

Activation of extracellular signal-related kinase by TNF-alpha controls the maturation and function of murine dendritic cells

Functional roles of extracellular signal-related kinase (ERK) activation in dendritic-cell (DC) maturation have been unclear. In the present study, we investigated the ERK pathway in tumor necrosis factor (TNF)-alpha-induced maturation of murine spleen-derived DC. TNF-alpha increased surface expressions of major histocompatibility (MHC) and costimulatory molecules on DC in a dose-dependent manner. High (40 ng/ml) and low (0.4 ng/ml) concentrations of TNF-alpha markedly enhanced ERK1/2 activation in DC, and this activation was blocked completely by PD98059, a selective inhibitor of the ERK pathway. When DC were treated with TNF-alpha at a low but not a high concentration, PD98059 notably enhanced surface expressions of the MHC and costimulatory molecules and allostimulatory capability of the DC. Interleukin (IL)-12 production was enhanced significantly by PD98059 in DC treated with low or high concentration of TNF-alpha. These findings suggest that TNF-alpha-induced ERK activation negatively controls maturation and IL-12 production in murine DC.

Characteristics and distribution of endogenous RFamide-related peptide-1

We have recently identified RFamide-related peptide (RFRP) gene that would encode three peptides (i.e., RFRP-1, -2, and -3) in human and bovine, and demonstrated that synthetic RFRP-1 and -3 act as specific agonists for a G protein-coupled receptor OT7T022. However, molecular characteristics and tissue distribution of endogenous RFRPs have not been determined yet. In this study, we prepared a monoclonal antibody for the C-terminal portion of rat RFRP-1. As this antibody could recognize a consensus sequence among the C-terminal portions of rat, human, and bovine RFRP-1, we purified endogenous RFRP-1 from bovine hypothalamus on the basis of immunoreactivity to the antibody. The purified bovine endogenous RFRP-1 was found to have 35-amino-acid length that corresponds to 37-amino-acid length in human and rat. We subsequently constructed a sandwich enzyme immunoassay using the monoclonal antibody and a polyclonal antibody for the N-terminal portion of rat RFRP-1, and analyzed the tissue distribution of endogenous RFRP-1 in rats. Significant levels of RFRP-1 were detected only in the central nervous system, and the highest concentration of RFRP-1 was detected in the hypothalamus. RFRP-1-positive nerve cells were detected in the rat hypothalamus by immunohistochemical analyses using the monoclonal antibody. In culture, RFRP-1 lowered cAMP production in Chinese hamster ovary cells expressing OT7T022 and it was abolished by pre-treatment with pertussis toxin, suggesting that OT7T022 couples G(i)/G(o) in the signal transduction pathway.

Endoscopic-assisted myringoplasty

An improved myringoplasty technique utilizing fibrin glue and carried out through the external auditory canal was recently introduced. This endoscopic-assisted technique allows exquisite views and avoids blind surgical procedures, thereby expanding the indications for minimally invasive myringoplasty. This technique was applied to patients in whom, due to the curved external auditory canal, the margin of the perforation of the tympanic membrane was not visible with an operating microscope. We summarized the results of 22 endoscopic-assisted myringoplasties and concluded that this technique provides satisfactory results both in the success rate of perforation closure and in hearing outcome.

A novel function of prolactin-releasing peptide in the control of growth hormone via secretion of somatostatin from the hypothalamus

The present study examined a novel function of PRL-releasing peptide (PrRP) on the neuroendocrine. PrRP-immunoreactive nerve fibers and nerve terminals were located in the vicinity of the somatostatin (SOM)-neurons in the hypothalamic periventricular nucleus (PerVN). Immuno-electron microscopy revealed that PrRP-immunoreactive nerve terminals made synaptic contacts with nonimmunoreactive neuronal elements in the PerVN. Intracerebroventricular (icv) administration of PrRP induced immediate early gene, NGFI-A, in SOM-neurons in the PerVN. Double-labeling in situ hybridization showed that some parts of SOM-neurons in the PerVN expressed PrRP receptor messenger RNA. Therefore, some parts of SOM-neurons in the PerVN are considered to be directly innervated by PrRP via PrRP receptor. In addition to the above morphological characteristics, icv administration of PrRP decreased plasma GH levels. Such inhibitory effects of PrRP on the secretion of GH from the anterior pituitary were diminished by depletion or neutralization of SOM. From these findings it was strongly suggested that SOM-neurons respond to PrRP and secrete SOM into the portal vessels and thus inhibit GH secretion from the anterior pituitary.

Developmental expression of prolactin releasing peptide in the rat brain: localization of messenger ribonucleic acid and immunoreactive neurons

Prolactin releasing peptide (PrRP) was recently identified as the stimulator of prolactin release from the anterior pituitary. PrRP mRNA is expressed in the medulla oblongata and the hypothalamus in the rat brain. The fibers containing PrRP are widely distributed in the brain, therefore, it was postulated that PrRP may act as a neurotransmitter or neuromodulator as well as an endocrine substance. To clarify the developmental changes in the expression of PrRP during brain development, we examined PrRP in rat fetuses and neonates using in situ hybridization and immunohistochemistry. The PrRP mRNA was expressed in the nucleus of the solitary tract (NTS) at embryonic day 18 (E18) and in the ventral and lateral reticular nucleus (VLRN) of the caudal medulla oblongata at E20. The PrRP mRNA in the hypothalamus was first expressed at postnatal day 13 (P13). Reverse transcription-polymerase chain reaction analysis (RT-PCR) for PrRP revealed that PCR product, a 268 bp band, was detected from either E18 in the medulla or P13 in the hypothalamus. Immunodetection with monoclonal antibody against prepro-PrRP revealed intensive staining of cells in the NTS at E18, in the VLRN at E20 or in the dorsomedial hypothalamus at P13. Immunohistochemistry using monoclonal antibody against mature PrRP at P6 showed PrRP fibers to be distributed in the paraventricular hypothalamic nucleus, periventricular hypothalamic nucleus, medial preoptic area, basolateral amygdaloid nucleus, dorsomedial hypothalamus, ventromedial hypothalamus, periventricular nucleus of the thalamus and bed nucleus of the stria terminalis as previously shown in the adult rat. PrRP fibers were also found in the optic chiasm, dorsal endopiriform nucleus, cingulum, intermediate reticular nucleus, and caudal ventrolateral reticular nucleus at P6 and P9. However, PrRP fibers were never found in the above regions in the adult animal. These findings suggest that PrRP fibers originating in the medulla oblongata have been widely distributed in the rat brain during the early postnatal day and PrRP may play various roles in the brain development.

Cloning and expression of group IB phospholipase A2 isoforms in the red sea bream, Pagrus major

Two cDNA encoding red sea bream DE-1 and DE-2 phospholipases A2 (PLA2) were cloned from the hepatopancreas of red sea bream, Pagrus (Chrysophrys) major. The cDNA of DE-1 PLA2 encoded a mature protein of 125 amino acid residues with an apparent signal peptide of 20 residues and propeptide of 5 residues, and that of DE-2 PLA2, a mature protein of 126 amino acid residues with an apparent signal peptide of 17 residues and propeptide of 6 residues. Comparison of the predicted amino acid sequences for mature DE-1 and DE-2 PLA2 showed that both proteins contain 14 cysteines including Cys 11 and 77 and a pancreatic loop, which are commonly conserved in group IB PLA2; however, the identity in amino acid sequence between DE-1 and DE-2 PLA2 was low (47%). A previous report concerning the cDNA cloning of red sea bream gill G-3 PLA2 and the present results represent the first cloning and sequencing of three distinct isoforms of group IB PLA2 in a single fish species, red sea bream. Reverse transcription-polymerase chain reaction analysis showed that DE-1 PLA2 mRNA was expressed in the hepatopancreas, pyloric ceca, intestine, spleen, gonad, stomach, and kidney, whereas gill G-3 PLA2 mRNA was expressed only in the gills and gonad. The expression of DE-2 PLA2 mRNA was detected in all of the tissues analyzed. These results indicate that three distinct isoforms of group IB PLA2, DE-1 and DE-2 PLA2 in hepatopanceas and gill G-3 PLA2, are expressed in a tissue-specific manner in red sea bream.

Gonadal regulation of PrRP mRNA expression in the nucleus tractus solitarius and ventral and lateral reticular nuclei of the rat

We investigated the prolactin-releasing peptide (PrRP) gene expression quantitatively in the rat brain and the involvement of estrogen and progesterone using in situ hybridization. The strongest signals were observed in the nucleus tractus solitarius (NTS), which showed approximately 70% of total PrRP mRNA in the brain. Moderate expression was observed in the ventral and lateral reticular nuclei (VLRN) of the medulla oblongata. PrRP mRNA signals in the hypothalamic ventromedial- and dorsomedial nuclei showed only 5% of total signals. The PrRP mRNA expression among female rats showing normal gonadal cycle and male rats showed that the highest levels were in female rats in proestrus. Administration of estrogen or progesterone after ovariectomy induced an increase in PrRP mRNA expression in the NTS. PrRP mRNA content in the NTS increased with the progress of the pregnancy and reached a peak on the 14th day, the mid-period of pregnancy, when plasma progesterone increases. We also observed the colocalization of PrRP and estrogen receptor alpha in the neurons distributed in the NTS by double labeling immunocytochemistry. These findings indicate that PrRP gene expression is regulated by gonadal steroid hormones in the medulla oblongata, and parts of PrRP synthesizing neurons are considered to be directly influenced by estrogen in the NTS.

[Therapeutic efficacy of amantadine hydrochloride in patients with epidemic influenza A virus infection]

A virus infection was studied using half of the normal oral dose of amantadine hydrochloride-100 mg/d instead of 200 mg/d. The patients in this study, who visited the clinics during January and February 1999, were confirmed within 48 hours to have influenza A virus infections by the Directigen FluA test. Using a quasi-randomized controlled trial, 26 patients were treated with amantadine hydrochloride in addition to the usual medication, while 23 were treated with only the ordinary medication. There were no significant differences in the mean age, 35.6 years old, or in clinical features between the two groups. The period of fever over 38 degrees C in the amantadine treated group was 1 day while that in the control group was 1.7 days, which shows a significant difference (p = 0.049). There was no significant difference in the duration of aching, such as arthralgia, or of general fatigue. There was no significant difference in the appearance of subsequent new symptoms after the onset of influenza A virus infection. In conclusion, it is expected that oral amantadine hydrochloride, 100 mg/d, together with the ordinary medication, will reduce the duration of the period of fever over 38 degrees C.

Purification, characterization, and molecular cloning of group I phospholipases A2 from the gills of the red sea bream, Pagrus major

Phospholipase A2 (PLA2) activity was investigated in various tissues of male and female red sea bream. In both male and female fishes, the specific activity of PLA2 in the gills was 70 times higher than that in other tissues, such as the adipose tissue, intestine, and hepatopancreas. Therefore, we tried to purify PLA2 from the gill filaments of red sea bream to near homogeneity by sequential chromatography on Q-Sepharose Fast Flow, Butyl-Cellulofine, and DEAE-Sepharose Fast Flow columns, and by reversed-phase high-performance liquid chromatography. Two minor and one major PLA2, tentatively named G-1, G-2 and G-3 PLA2, were purified, and all showed a single band with an apparent molecular mass of approximately 15 kDa by sodium dodecylsulfate-polyacrylamide gel electrophoresis. The exact molecular mass values of G-1, G-2, and G-3 PLA2 were 14,040, 14,040 and 14,005 Da, respectively. G-1, G-2, and G-3 PLA2 had a Cys 11 and were all identical in N-terminal amino acid sequences from Ala-1 to Glu-56. A full-length cDNA encoding G-3 PLA2 was cloned by reverse transcriptase-polymerase chain reaction and rapid amplification of cDNA ends methods, and G-3 PLA2 was found to be classified to group IB PLA2 from the deduced amino acid sequence. G-1, G-2, and G-3 PLA2 had a pH optimum in an alkaline region at around pH 9-10 and required Ca2+ essentially for enzyme activity, using a mixed-micellar phosphatidylcholine substrate with sodium cholate. These results demonstrate that three group I PLA2, G-1, G-2, and G-3 PLA2, are expressed in the gill filaments of red sea bream.

Morphological survey of prolactin-releasing peptide and its receptor with special reference to their functional roles in the brain

The gene of prolactin-releasing peptide (PrRP) was first cloned in 1998 and preproproteins encoded by cDNAs produced at least two isoforms of PrRP with different lengths; PrRP31 and PrRP20. PrRP has been shown to release prolactin from the anterior pituitary at least in vitro (Hinuma, Y.S., Habata, Y., Fuji, R., Hosoya, M., Fukusumi, S., Kitada, C., Masuo, Y., Asano, T., Matsumoto, H., Sekiguchi, M., Kurokawa, T., Nishimura, O., Onda, H., and Fujino, A., 1998. A prolactin-releasing peptide in the brain. Nature 393, 272-6). PrRP receptor has also been detected by quantitive reverse transcription polymerase chain reaction, and in situ hybridization histochernistry revealed that expression of PrRP receptor mRNA was found in the broad areas of the brain and in the anterior pituitary of the rat. This review surveys morphological studies on PrRP, PrRP mRNA and PrRP receptor mRNA in the rat brain and discusses the possible functional significance of PrRP in the brain. PrRP immunoreactive neuronal perikarya showed a similar distributional pattern to those with PrRP mRNA signals. However, distribution of nerve processes and terminals with PrRP immunoreactivity was broadly expanded in the forebrain and brainstem. They were hardly detected in the median eminence particularly in its external layer. PrRP receptor mRNA signals were distributed in the preoptic area, and the hypothalamic area, where PrRP immunoreactive nerve processes and terminals were also detected. The strongest signal of PrRP receptor mRNA was detected in the reticular nucleus of the thalamus where neither PrRP immunoreactive nerve processes nor axon terminals were distributed. From the distribution pattern of PrRP and its receptor, it is suggested that PrRP is involved in control of secretion of oxytocin, corticotropin releasing hormone and somatostatin.

Development of astroglial elements in the suprachiasmatic nucleus of the rat: with special reference to the involvement of the optic nerve

The development of astroglial cells and the effect of the retinohypothalamic tract on it were studied by vimentin and glial fibrillary acidic protein (GFAP) immunocytochemistry in the suprachiasmatic nucleus (SCN) of the rat. At the embryonic stage, vimentin-immunoreactive (VIM-IR) radial glia, precursors of astrocytes, were dominant. However, their filaments vanished in the first few postnatal days. Instead of VIM-IR glial filaments, GFAP-immunoreactive (GFAP-IR) astrocytes appeared at E20 and grew rapidly from the P3 stage. GFAP immunoreactivity in the ventrolateral portion of the SCN (VLSCN) was measured using a computer-assisted image analyzing system. In normal rats, GFAP immunoreactivity showed a stepwise pattern with two slopes at P3-P4 and P20-P25. Bilaterally eye-enucleated rats operated on the day of birth showed lower GFAP immunoreactivity than normal rats and the GFAP immunoreactivity did not increase between P20 and P25 when GFAP-IR glial processes rapidly expand. Electron microscopic investigation at P50 (adult stage) revealed that neurons in the VLSCN had often direct apposition without astroglial processes and the frequency of this finding was significantly higher in eye-enucleated rats than in the control rats. These findings strongly suggest that the postnatal development of astroglial elements, particularly the expansion of GFAP-IR processes in the SCN, is regulated by retinohypothalamic projection.

New neuropeptides containing carboxy-terminal RFamide and their receptor in mammals

Only a few RFamide peptides have been identified in mammals, although they have been abundantly found in invertebrates. Here we report the identification of a human gene that encodes at least three RFamide-related peptides, hRFRP-1-3. Cells transfected with a seven-transmembrane-domain receptor, OT7T022, specifically respond to synthetic hRFRP-1 and hRFRP-3 but not to hRFRP-2. RFRP and OT7T022 mRNAs are expressed in particular regions of the rat hypothalamus, and intracerebroventricular administration of hRFRP-1 increases prolactin secretion in rats. Our results indicate that a variety of RFamide-related peptides may exist and function in mammals.

Monoclonal antibodies to plasma high density lipoprotein (HDL) of eel (Anguilla japonica)

Six week-old female mice (Balb/c) injected intraperitonealy with 50 micrograms of eel high density lipoprotein (HDL) emulsified with equal volume of adjuvant three times every two weeks. Three weeks after the third injection, hyperimmunized mice were boosted by injection of 100 micrograms of HDL. After 5 days, the best responding mouse to injected HDL was sacrificed, and spleen cells were fused with mouse myeloma cells (Sp2/O-Ag14), and hybridomas were cultured in a selection medium. Monoclonal antibodies specific to apolipoprotein A-I or A-II (apoA-I or apoA-II) of HDL were obtained by cloning and recloning the hybridomas. Eighteen monoclonal antibodies specific to apoA-I and/or apoApII were isolated. Antibodies in the culture medium were purified by a HiTrap Protein G or an eel-HDL column. These purified antibodies belong to the subclass IgG1. The monoclonal antibodies specific to eel apoA-I and apoA-II secreted by clone 10D12 and 2G3, respectively, interact with serum proteins of some fish species such as red-sea bream and carp. The anti-eel apoA-I antibody of 10D12 did not bind to serum proteins of rat, rabbit, and chicken, while the anti-eel apoA-II of 2G3 antibody did.

NGFI-A gene expression induced in the rat suprachiasmatic nucleus by photic stimulation: spread into hypothalamic periventricular somatostatin neurons and GABA receptor involvement

We studied NGFI-A gene expression in response to photic stimulation in the rat suprachiasmatic nucleus (SCN) using in situ hybridization histochemistry. This gene expression spread within the SCN and extended dorsally into the anterior hypothalamus after 30 min-1 h of light exposure at circadian time (CT) CT18. It appeared first in the ventrolateral SCN where the retinohypothalamic tract (RHT) innervates, then it expanded dorsomedially in the SCN and beyond the SCN to the anterior hypothalamus. However, stimulation for 2 h light exposure decreased its expression in the SCN. NGFI-A expression in the somatostatin neurons in the periventricular nucleus increased from 8.7% to 41% with increasing exposure time from 5 to 30 min. NGFI-A mRNA expression in the SCN was suppressed by pretreatment with baclofen, the GABAB receptor agonist. The spread of photic information from the retina to the SCN was visualized at immediate early gene level not only in the SCN but also in the area beyond the SCN. Somatostatin neurons in the periventricular nucleus which project to the external layer of the median eminence and are involved in regulation of growth hormone release showed NGFI-A gene expression corresponding to the duration of photic stimulation. Photic-induced NGFI-A gene expression in the SCN was also shown to be regulated by GABAergic transmission via GABAB receptors. These NGFI-A gene-expressing cells in the SCN may be involved in the circadian entrainment by light and some of those outside the SCN may participate in the regulation of neuroendocrine function.

Expanded expression of heme oxygenase-1 (HO-1) in the hypothalamic median eminence of aged as compared with young rats: an immunocytochemical study

This study was performed to examine the differences in expression of heme oxygenase protein with age using immunocytochemistry. We compared the contents of HO-1 and HO-2 between young and aged rats using immunocytochemical methods. Stronger HO-1 expression was detected in the internal layer of the median eminence (ME) of aged than of young rats. Moreover, the cells expressing HO-1 were larger in the aged than the young animals. Electron microscopy indicated these cells with HO-1-like immunoreactivity (HO-1-LI) to be astrocytes. These findings suggested that the expression of HO-1 increased in the ME with age. The significance of this increased expression of HO-1 with age will be discussed briefly.

Functional morphology of the suprachiasmatic nucleus

In mammals, the biological clock (circadian oscillator) is situated in the suprachiasmatic nucleus (SCN), a small bilaterally paired structure just above the optic chiasm. Circadian rhythms of sleep-wakefulness and hormone release disappear when the SCN is destroyed, and transplantation of fetal or neonatal SCN into an arrhythmic host restores rhythmicity. There are several kinds of peptide-synthesizing neurons in the SCN, with vasoactive intestinal peptide, arginine vasopressin, and somatostatine neurons being most prominent. Those peptides and their mRNA show diurnal rhythmicity and may or may not be affected by light stimuli. Major neuronal inputs from retinal ganglion cells as well as other inputs such as those from the lateral geniculate nucleus and raphe nucleus are very important for entrainment and shift of circadian rhythms. In this review, we describe morphological and functional interactions between neurons and glial elements and their development. We also consider the expression of immediate-early genes in the SCN after light stimulation during subjective night and their role in the mechanism of signal transduction. The reciprocal interaction between the SCN and melatonin, which is synthesized in the pineal body under the influence of polysynaptic inputs from the SCN, is also considered. Finally, morphological and functional characteristics of clock genes, particularly mPers, which are considered to promote circadian rhythm, are reviewed.