Changes with ageing in the modulation of murine lymphocyte chemotaxis by CCK-8S, GRP and NPY

CCK2-receptor deficiency impairs immune balance by influencing CD4+ T cells development by inhibiting cortical-thymic-epithelial-cells

Immune balance is crucial for an organism's survival and is inseparable from the regulation of the nervous system. Accumulating evidence indicates that cholecystokinin (CCK) plays an important role in mediating the immune response through the activation of cholecystokinin receptors (CCKRs). However, it remains unclear whether CCKRs deficiency may impair immune balance. Here, we showed that CCK2R-deficient adult mice were immunocompromised and had an increased risk of shock and even death in an endotoxemia (ETM)/endotoxin shock (ES) model. In addition, in both adult and juvenile mice, CCK2R deficiency not only influenced the development of CD4 single-positive (SP) thymocytes in thymic positive selection but also decreased the population of CD3+ CD4+ T cells in the spleen. More importantly, CCK2R deficiency inhibited the expression of major histocompatibility complex class II (MHC II) and CD83 on cortical thymic epithelial cells (cTECs) in juvenile and adult mice. Overall, our study suggests that CCK2R is essential for maintaining CD4+ T cell development in the thymus and reveals that CCK2R plays an important role in maintaining immune balance.

Neuropeptide Y Is an Immunomodulatory Factor: Direct and Indirect

Neuropeptide Y (NPY), which is widely distributed in the nervous system, is involved in regulating a variety of biological processes, including food intake, energy metabolism, and emotional expression. However, emerging evidence points to NPY also as a critical transmitter between the nervous system and immune system, as well as a mediator produced and released by immune cells. In vivo and in vitro studies based on gene-editing techniques and specific NPY receptor agonists and antagonists have demonstrated that NPY is responsible for multifarious direct modulations on immune cells by acting on NPY receptors. Moreover, via the central or peripheral nervous system, NPY is closely connected to body temperature regulation, obesity development, glucose metabolism, and emotional expression, which are all immunomodulatory factors for the immune system. In this review, we focus on the direct role of NPY in immune cells and particularly discuss its indirect impact on the immune response.

Protective effects of gastrin-releasing peptide receptor antagonist RC-3095 in an animal model of hepatic ischemia/reperfusion injury

AIM

We aimed to evaluate effects of RC-3095 on mice with hepatic ischemia followed by reperfusion (I/R) injury and further explore the possible underlying mechanism.

METHODS

Mice were subjected to partial hepatic ischemia for 60 min followed by different durations of reperfusion. Levels of gastrin-releasing peptide (GRP) and GRP receptor (GRPR) in the blood and liver were detected by enzyme-linked immunosorbent assay (ELISA) or western blotting (WB) after 3, 6, 12, or 24 h of reperfusion. RC-3095 or normal saline (control) was given i.p. at the time of reperfusion. Expressions of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and IL-10 in blood and liver samples were examined with ELISA. Neutrophil influx into the liver was assessed by flow cytometry and myeloperoxidase assay. Hematoxylin-eosin staining of the liver and terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling assay were used to determine hepatic injury and hepatocellular necrosis. Activation of nuclear factor (NF)-κB and p38/extracellular regulated protein kinase (ERK) mitogen activated protein kinase (MAPK) was investigated with WB.

RESULTS

The expression of GRP was upregulated within 3 h after reperfusion and remained elevated for up to 24 h in the liver, whereas GRPR was also upregulated after 3 or 6 h of reperfusion, but returned to baseline levels within 24 h. RC-3095 significantly reduced the inflammatory hepatic injury, liver neutrophil accumulation, and hepatocellular apoptosis, probably by inhibiting activation of NF-κB or p38/ERK MAPK.

CONCLUSION

These findings supported that GRP-GRPR played an important role in hepatic I/R injury, and RC-3095 ameliorated liver damage by suppressing the inflammatory response and hepatocellular necrosis.

The homeostatic role of neuropeptide Y in immune function and its impact on mood and behaviour

Neuropeptide Y (NPY), one of the most abundant peptides in the nervous system, exerts its effects via five receptor types, termed Y1, Y2, Y4, Y5 and Y6. NPY's pleiotropic functions comprise the regulation of brain activity, mood, stress coping, ingestion, digestion, metabolism, vascular and immune function. Nerve-derived NPY directly affects immune cells while NPY also acts as a paracrine and autocrine immune mediator, because immune cells themselves are capable of producing and releasing NPY. NPY is able to induce immune activation or suppression, depending on a myriad of factors such as the Y receptors activated and cell types involved. There is an intricate relationship between psychological stress, mood disorders and the immune system. While stress represents a risk factor for the development of mood disorders, it exhibits diverse actions on the immune system as well. Conversely, inflammation is regarded as an internal stressor and is increasingly recognized to contribute to the pathogenesis of mood and metabolic disorders. Intriguingly, the cerebral NPY system has been found to protect against distinct disturbances in response to immune challenge, attenuating the sickness response and preventing the development of depression. Thus, NPY plays an important homeostatic role in balancing disturbances of physiological systems caused by peripheral immune challenge. This implication is particularly evident in the brain in which NPY counteracts the negative impact of immune challenge on mood, emotional processing and stress resilience. NPY thus acts as a unique signalling molecule in the interaction of the immune system with the brain in health and disease.

Neuropeptide Y induces potent migration of human immature dendritic cells and promotes a Th2 polarization

Neuropeptide Y (NPY), a major autonomic nervous system and stress mediator, is emerging as an important regulator of inflammation, implicated in autoimmunity, asthma, atherosclerosis, and cancer. Yet the role of NPY in regulating phenotype and functions of dendritic cells (DCs), the professional antigen-presenting cells, remains undefined. Here we investigated whether NPY could induce DCs to migrate, mature, and polarize naive T lymphocytes. We found that NPY induced a dose-dependent migration of human monocyte-derived immature DCs through the engagement of NPY Y1 receptor and the activation of ERK and p38 mitogen-activated protein kinases. NPY promoted DC adhesion to endothelial cells and transendothelial migration. It failed to induce phenotypic DC maturation, whereas it conferred a T helper 2 (Th2) polarizing profile to DCs through the up-regulation of interleukin (IL)-6 and IL-10 production. Thus, during an immune/inflammatory response NPY may exert proinflammatory effects through the recruitment of immature DCs, but it may exert antiinflammatory effects by promoting a Th2 polarization. Locally, at inflammatory sites, cell recruitment could be amplified in conditions of intense acute, chronic, or cold stress. Thus, altered or amplified signaling through the NPY-NPY-Y1 receptor-DC axis may have implications for the development of inflammatory conditions.-Buttari, B., Profumo, E., Domenici, G., Tagliani, A., Ippoliti, F., Bonini, S., Businaro, R., Elenkov, I., Riganò, R. Neuropeptide Y induces potent migration of human immature dendritic cells and promotes a Th2 polarization.

CCK8 negatively regulates the TLR9-induced activation of human peripheral blood pDCs by targeting TRAF6 signaling

Plasmacytoid dendritic cells (pDCs) are specialized in rapid and massive secretion of type I interferon in response to foreign nuclei acids. Combined with their antigen presentation capacity, this powerful functionality enables pDCs to orchestrate innate and adaptive immune responses. Cholecystokinin octapeptide (CCK8) is a potent immunomodulator, whose role in pDCs function is unknown. In this study, we found that two different cholecystokinin receptors, CCK1R and CCK2R, are expressed on human peripheral blood pDCs. Exogenous CCK8 was able to modulate the TLR-induced activation of pDCs, including phenotypic maturation, IFN-α synthesis and secretion, and could also regulate the potential of pDCs to induce adaptive immune responses in vitro. CCK8 inhibited TLR9-induced activation of tumor-necrosis factor receptor-associated factor 6, which is an important adapter protein in activation of interferon-regulatory factor (IRF)5 and IRF7, possibly through CCK2R, by evoking the activity of protein kinase (PK)A and reducing the activity of PKC. All these results indicate that CCK8 can inhibit the TLR9-induced phenotypic maturation and activation of pDCs, acting through CCK2R by modulating the tumor-necrosis factor receptor-associated factor 6 signaling pathways.

Female mice lacking cholecystokinin 1 receptors have compromised neurogenesis, and fewer dopaminergic cells in the olfactory bulb

Neurogenesis in the adult rodent brain is largely restricted to the subependymal zone (SVZ) of the lateral ventricle and subgranular zone (SGZ) of the dentate gyrus (DG). We examined whether cholecystokinin (CCK) through actions mediated by CCK1 receptors (CCK1R) is involved in regulating neurogenesis. Proliferating cells in the SVZ, measured by 5-bromo-2-deoxyuridine (BrdU) injected 2 h prior to death or by immunoreactivity against Ki67, were reduced by 37 and 42%, respectively, in female (but not male) mice lacking CCK1Rs (CCK1R(-/-)) compared to wild-type (WT). Generation of neuroblasts in the SVZ and rostral migratory stream (RMS) was also affected, since the number of doublecortin (DCX)-immunoreactive (ir) neuroblasts in these regions decreased by 29%. In the SGZ of female CCK1R(-/-) mice, BrdU-positive (+), and Ki67-ir cells were reduced by 38 and 56%, respectively, while DCX-ir neuroblasts were down 80%. Subsequently, the effect of reduced SVZ/SGZ proliferation on the generation and survival of mature adult-born cells in female CCK1R(-/-) mice was examined. In the OB granule cell layer (GCL), the number of neuronal nuclei (NeuN)-ir and calretinin-ir cells was stable compared to WT, and 42 days after BrdU injections, the number of BrdU+ cells co-expressing GABA- or NeuN-like immunoreactivity (LI) was similar. Compared to WT, the granule cell layer of the DG in female CCK1R(-/-) mice had a similar number of calbindin-ir cells and BrdU+ cells co-expressing calbindin-LI 42 days after BrdU injections. However, the OB glomerular layer (GL) of CCK1R(-/-) female mice had 11% fewer NeuN-ir cells, 23% less TH-ir cells, and a 38% and 29% reduction in BrdU+ cells that co-expressed TH-LI or GABA-LI, respectively. We conclude that CCK, via CCK1Rs, is involved in regulating the generation of proliferating cells and neuroblasts in the adult female mouse brain, and mechanisms are in place to maintain steady neuronal populations in the OB and DG when the rate of proliferation is altered.

NPY suppressed development of experimental autoimmune encephalomyelitis in Dark Agouti rats by disrupting costimulatory molecule interactions

Neuropeptide Y (NPY) suppressed clinical experimental autoimmune encephalomyelitis (EAE) and reduced numbers of CD28+, CD11b+ and CD80+ cells among spinal cord infiltrating cells at the peak of disease in Dark Agouti rat strain. Suppression of EAE was accompanied by the reduced expression of costimulatory CD80 and CD86 molecules on ED1+ macrophages and OX62+ dendritic cells in draining lymph nodes during the inductive phase of EAE. An inhibitor of dipeptidyl peptidase 4, an enzyme which terminates the action of NPY on Y1 receptor subtype, did not sustain the suppressive effect of NPY on the EAE development, suggesting involvement of Y2 and Y5 receptors.

Semaphorins and neuropilins: new players in the neuroendocrine control of the intrathymic T-cell migration in humans

Cell migration is a key event for proper intrathymic T-cell differentiation, and several ligand-receptor interactions contribute to the well-co ordinated movement of developing thymocytes within the thymic lobules. Herein we summarize recent data that place semaphorin 3A (Sema3A) and its receptor neuropilin 1 (NRP1) as further players in the physiological process of cell migration in the human thymus. These molecules, as well as class A plexins (necessary for the intracellular signalling transduction triggered by Sema3A-NRP1 ligation), are constitutively expressed by both developing thymocytes and components of the thymic microenvironment, including epithelial and dendritic cells. Functionally, Sema3A decreases the adhesion of human thymocytes on thymic epithelial cell monolayers and exerts per se a dose-dependent chemorepulsive effect on human thymocytes. Moreover, Sema3A inhibits chemoattractant migratory responses induced by other ligands, including fibronectin, laminin and CXCL12 (chemokine CXC motif ligand 12). These data should be placed in the context of the concept that migration of developing T cells is a multivectorial system, in which the resulting migration vector derives from a balance of several simultaneous and/or sequential ligand-receptor pair interactions. Accordingly, semaphorins and neuropilins can be considered as further players in the system.

Impairment of non-muscle myosin IIA in human CD4+ T cells contributes to functional deficits in the elderly

Physiological aging imposes significant alterations in the repertoire of T cells and all associated functions. Although several studies have reported defects upon antigen-induced activation of T cells during aging, the molecular mechanisms that control T-cell receptor (TCR) downmodulation remain to be fully defined. While previous studies have assessed the role of F-actin in regulating activation-induced TCR internalization, few have delineated the roles of motor proteins, such as non-muscle myosin IIA (NMMIIA). In this study, we describe a series of experiments supporting the hypothesis that effective TCR downmodulation requires not only efficient reorganization of the actin cytoskeleton, but also functional NMMIIA. For the first time, we show that CD4(+) T cells from elderly human donors have dysfunctional NMMIIA that contributes to delaying activation-induced TCR internalization and impairing calcium mobilization. Additionally, our results demonstrate that chemical inhibition of NMMIIA in CD4(+) T cells from young donors also results in complete abrogation of TCR internalization, strongly supporting the fundamental role of NMMIIA in modulating this event. Recent observations that the generation of an efficient T-cell response requires migration prompted us to investigate whether NMMIIA also plays a regulatory role in CD4(+) T-cell migration. We show that chemical inhibition of NMMIIA downmodulates chemotactic migration in CD4(+) T cells from both young and elderly donors. Together, these data demonstrate a significant contribution of dysfunctional NMMIIA to TCR-mediated functional defects during aging.

Neuropeptide Y modulates functions of inflammatory cells in the rat: distinct role for Y1, Y2 and Y5 receptors

Neuropeptide Y (NPY) has been reported to be a potent anti-inflammatory peptide with ability to directly modulate activity of granulocytes and macrophages. The present study aimed to correlate the effects of NPY in vivo on lipopolysaccharide-induced air-pouch exudates cells and in vitro on peripheral blood leukocytes functions. The role of different Y receptors was examined using NPY-related peptides and antagonists with diverse subtype specificity and selectivity for Y receptors. Y1, Y2 and Y5 receptors were detected on air-pouch exudates cells (flow cytometry) and peripheral blood granulocytes (immunocytochemistry). NPY in vivo reduced inflammatory cells accumulation into the air pouch, and decreased their adherence and phagocytic capacity via Y2/Y5 and Y1/Y2 receptors, respectively. Quite the opposite, NPY in vitro potentiated adhesiveness and phagocytosis of peripheral blood granulocytes and monocytes by activating Y1 receptor. The differences between in vivo and in vitro effects of NPY on rat inflammatory cells functions are mostly due to dipeptidyl peptidase 4 activity. In addition, suppressive effect of NPY in vivo is highly dependent on the local microenvironment, peptide truncation and specific Y receptors interplay.

Protective effect of gastrin-releasing peptide receptor antagonist in carrageenan-induced pleural inflammation in rats

OBJECTIVE

We report the effects of the gastrin-releasing peptide (GRP) receptor antagonist RC-3095 in an acute inflammation model induced by carrageenan.

METHODS

Male Wistar rats received saline or saline containing 2% lambda-carrageenan into the pleural cavity, with some also receiving RC-3095 3 mg/kg subcutaneously, immediately after surgery. Four hours later, the rats were killed and pleural exudate was obtained for evaluation of total cell count, lactate dehydrogenase activity, total protein, cytokines analysis and nitrite/nitrate concentrations; myeloperoxidase (MPO) activity and oxidative stress were evaluated in the lung.

RESULTS

RC-3095 exhibited pronounced anti-inflammatory actions by inhibition of leukocyte influx and blockade of MPO, nitrite/nitrate and cytokine levels. Moreover, the results showed that RC-3095 elicits action against oxidative damage in lipids and proteins, as well as increasing cell viability.

CONCLUSION

The present findings suggest that GRP plays a role in acute inflammation that can be related with the reduction of oxidative damage and that it could be effective in therapeutic applications.

Neuropilins, semaphorins, and their role in thymocyte development

Some molecules described in the nervous system are also expressed in cells involved in the control of the immune response, suggesting they have a role as common mechanisms between neuroendocrine and immune systems. In this review, we focus on the expression and role of neuropilins (NPs) and their soluble ligands class 3 semaphorins in thymus physiology, particularly migration of developing thymocytes. We also discuss the concept of multivectorial thymocyte migration, including semaphorins, as a new individual cell migration vector.

Peptidergic influences on proliferation, migration, and placement of neural progenitors in the adult mouse forebrain

Neural progenitor proliferation, differentiation, and migration are continually ongoing processes in the subventricular zone (SVZ) and rostral migratory stream (RMS) of the adult brain. There is evidence that peptidergic systems may be involved in the molecular cascades regulating these neurogenic processes, and we examined a possible influence of neuropeptide Y (NPY) and cholecystokinin (CCK) systems in cell proliferation and neuroblast formation in the SVZ and RMS and generation of interneurons in the olfactory bulb (OB). We show that NPY and the Y1 and Y2 receptor (R) proteins are expressed in and surrounding the SVZ and RMS and that Y1R is located on neuroblasts in the anterior RMS. Mice deficient in Y1Rs or Y2Rs have fewer Ki-67-immunoreactive (ir) proliferating precursor cells and doublecortin-ir neuroblasts in the SVZ and RMS than WT mice, and less calbindin-, calretinin-, and tyrosine hydroxylase-ir interneurons in the OB. Mice lacking CCK1Rs have fewer proliferating cells and neuroblasts than normal and a shortage of interneurons in the OB. These findings suggest that both NPY and CCK through their receptors help to regulate the proliferation of precursor cells, the amount of neuroblast cells in the SVZ and RMS, and influence the differentiation of OB interneurons.

Plasticity of neuroendocrine-thymus interactions during ontogeny and ageing: role of zinc and arginine

Thymic re-growth and reactivation of thymic functions may be achieved in old animals by different endocrinological or nutritional manipulations such as, (a) treatment with melatonin, (b) implantation of a growth hormone (GH) secreting tumour cell line (GH3 cells) or treatment with exogenous GH, (c) castration or treatment with exogenous luteinizing hormone-releasing hormone (LHRH), (d) treatment with exogenous thyroxin or triiodothyronine, and (e) nutritional interventions such as arginine or zinc supplementation. These data strongly suggest that thymic involution is a phenomenon secondary to age-related alterations in neuroendocrine-thymus interactions and that it is the disruption of these interactions in old age that is responsible for age-associated immune-neuroendocrine dysfunctions. The targets involved in hormones-induced thymic reconstitution may directly or indirectly involve hormone receptors, cytokines, arginine, and a trace element such as zinc, which is pivotal for the efficiency of neuroendocrine-immune network during the whole life of an organism. The effect of GH, thyroid hormones, and LHRH may be due to specific hormone receptors on thymocytes and on thymic epithelial cells (TECs), which synthesize thymic peptides. Melatonin may also act through specific receptors on T-cells. In this context, the role of zinc, which turnover is reduced in old age, is pivotal because of its involvement through zinc fingers in the gene expression of hormone receptors. In addition, the effects of zinc are multifaceted: from the reactivation of zinc-dependent enzymes, to cell proliferation and apoptosis, to cytokines expression and to the reactivation of thymulin, which is a zinc-dependent thymic hormone required for intrathymic T-cell differentiation and maturation as well as for the homing of stem cells into the thymus. Zinc is also required for arginine action, via NO pathway. The role of zinc is therefore crucial in neuroendocrine-thymus interactions. According to data in animals and humans, the above reported endocrinological manipulations (GH, thyroid hormones, and melatonin) or arginine treatment may also act via zinc pool in restoring thymic activity in ageing allowing improvements on peripheral immune efficiency.

Nitric oxide released by accessory cells mediates the gastrin-releasing peptide effect on murine lymphocyte chemotaxis

Several neuropeptides, including gastrin-releasing peptide (GRP), modulate the immune response, specifically lymphocyte chemotaxis. In the present work the effect of GRP on the chemotaxis of murine lymphocytes from different immune locations in both, total leukocyte populations and populations depleted of adherent cells have been studied. Specificity of the GRP effect on chemotaxis using an antagonist of the GRP receptor, as well as the implication of nitric oxide (NO), using inhibitors of NO synthase and donors of NO, were investigated. The effects of GRP stimulating the chemotaxis of lymphocytes from peritoneum, axillary nodes and spleen and decreasing the chemotaxis from thymus were receptor-specific and disappeared in lymphocytes from populations depleted of adherent cells. NO synthase inhibitors blocked the GRP effect on lymphocyte chemotaxis, and this action was reversed in the presence of l-arginine. Thus, the effect of GRP on murine lymphocyte chemotaxis appears to be mediated by NO secreted by adherent cells.

Gastrin-releasing peptide receptor antagonist effects on an animal model of sepsis

RATIONALE

Several new therapeutic strategies have been described for the treatment of sepsis, but to date none are related to alterations in the bombesin/gastrin-releasing peptide (GRP) receptor pathways.

OBJECTIVES

To determine the effects of a selective GRP receptor antagonist, RC-3095, on cytokine release from macrophages and its in vivo effects in the cecal ligation and puncture (CLP) model of sepsis and in acute lung injury induced by intratracheal instillation of LPS.

METHODS

We determined the effects of RC-3095 in the CLP model of sepsis and in acute lung injury induced by intratracheal instillation of LPS. In addition, we determined the effects of RC-3095 on tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, IL-10, and nitric oxide release from activated macrophages.

MEASUREMENTS AND MAIN RESULTS

The GRP antagonist attenuated LPS- or CLP-induced TNF-alpha, IL-1beta, and nitric oxide release in cultured macrophages and decreased the mRNA levels of inducible nitric oxide synthase. The administration of RC-3095 (0.3 mg/kg) 6 h after sepsis induction improved survival in the CLP model, and diminished lung damage after intratracheal instillation of LPS. These effects were associated with attenuation on the circulating TNF-alpha and IL-1beta levels and decreased myeloperoxidase activity in several organs.

CONCLUSIONS

We report that a selective GRP receptor antagonist attenuates the release of proinflammatory cytokines in vitro and in vivo and improves survival in "established" sepsis. These are consistent with the involvement of a new inflammatory pathway relevant to the development of sepsis.

Modulation of neuropeptide Y and norepinephrine on several leucocyte functions in adult, old and very old mice

The age-related changes in the communication between the nervous and the immune system have been scarcely investigated, especially in very aged subjects. The present work deals with the in vitro effects of norepinephrine and neuropeptide Y, separately and jointly, on functions such as lymphoproliferation, NK activity, and IL-2 and TNF-alpha release of peritoneal leucocytes from adult (24+/-2 weeks), old (72+/-2 weeks) and very old (128+/-2 weeks) mice. The old mice showed a decrease in proliferation, NK activity and IL-2 release, and an increase in TNF-alpha, whereas in the very old mice these functions were more similar to those of the adults. The effects of neurotransmitters on these functions were different depending on the age of the animals.

Changes with ageing in several leukocyte functions of male and female rats

The impairment of the immune system with aging, or 'immunosenescence', appears to contribute to the increased morbidity and mortality of aged subjects. T cell functions and Natural Killer activity seem to be the immune responses most affected by ageing. Since the immune system works more efficiently in females than in males, we have studied the changes of several immune functions with age in rats of both sexes. In addition, we have investigated if ovariectomy, a model of menopause in rats, produces a loss of this gender-related advantage. In the present work, the changes with age (2, 6, 12, 14, 18, 22 and 24 months old) in lymphocyte chemotaxis, T lymphoproliferative response to the mitogen ConA, IL-2 release and Natural Killer activity of cells from axillary nodes and spleen of male and female rats as well as of females ovariectomized at 12 months of age have been studied. An age-related decrease was found in all investigated functions, with a slightly different evolution depending on the immune organ and gender considered. In general, the data obtained show that a certain degree of immunosenescence takes place with age in rats, with males being less immunocompetent than intact age-matched females, but showing an immune response similar to that of ovariectomized animals.

Cholecystokinin modulates migration of gonadotropin-releasing hormone-1 neurons

Expression of the brain-gut peptide cholecystokinin (CCK) in the developing olfactory-gonadotropin-releasing hormone-1 (GnRH-1) neuroendocrine systems was characterized, and the function of CCK in these systems was analyzed both in vivo and in vitro. We present novel data demonstrating that CCK transcript and protein are expressed in sensory cells in the developing olfactory epithelium and vomeronasal organ, with both ligand and receptors (CCK-1R and CCK-2R) found on olfactory axons throughout prenatal development. In addition, migrating GnRH-1 neurons in nasal regions express CCK-1R but not CCK-2R receptors. The role of CCK in olfactory-GnRH-1 system development was evaluated using nasal explants, after assessing that the in vivo expression of both CCK and CCK receptors was mimicked in this in vitro model. Exogenous application of CCK (10(-7) m) reduced both olfactory axon outgrowth and migration of GnRH-1 cells. This inhibition was mediated by CCK-1R receptors. Moreover, CCK-1R but not CCK-2R antagonism caused a shift in the location of GnRH-1 neurons, increasing the distance that the cells migrated. GnRH-1 neuronal migration in mice carrying a genetic deletion of either CCK-1R or CCK-2R receptor genes was also analyzed. At embryonic day 14.5, the total number of GnRH-1 cells was identical in wild-type and mutant mice; however, the number of GnRH-1 neurons within forebrain was significantly greater in CCK-1R-/- embryos, consistent with an accelerated migratory process. These results indicate that CCK provides an inhibitory influence on GnRH-1 neuronal migration, contributing to the appropriate entrance of these neuroendocrine cells into the brain, and thus represent the first report of a developmental role for CCK.

Autonomic innervation of immune organs and neuroimmune modulation

1. Increasing evidence indicates the occurrence of functional interconnections between immune and nervous systems, although data available on the mechanisms of this bi-directional cross-talking are frequently incomplete and not always focussed on their relevance for neuroimmune modulation. 2. Primary (bone marrow and thymus) and secondary (spleen and lymph nodes) lymphoid organs are supplied with an autonomic (mainly sympathetic) efferent innervation and with an afferent sensory innervation. Anatomical studies have revealed origin, pattern of distribution and targets of nerve fibre populations supplying lymphoid organs. 3. Classic (catecholamines and acetylcholine) and peptide transmitters of neural and non-neural origin are released in the lymphoid microenvironment and contribute to neuroimmune modulation. Neuropeptide Y, substance P, calcitonin gene-related peptide, and vasoactive intestinal peptide represent the neuropeptides most involved in neuroimmune modulation. 4. Immune cells and immune organs express specific receptors for (neuro)transmitters. These receptors have been shown to respond in vivo and/or in vitro to the neural substances and their manipulation can alter immune responses. Changes in immune function can also influence the distribution of nerves and the expression of neural receptors in lymphoid organs. 5. Data on different populations of nerve fibres supplying immune organs and their role in providing a link between nervous and immune systems are reviewed. Anatomical connections between nervous and immune systems represent the structural support of the complex network of immune responses. A detailed knowledge of interactions between nervous and immune systems may represent an important basis for the development of strategies for treating pathologies in which altered neuroimmune cross-talking may be involved.

Dipeptidyl-peptidase IV from bench to bedside: an update on structural properties, functions, and clinical aspects of the enzyme DPP IV

Dipeptidyl-peptidase IV/CD26 (DPP IV) is a cell-surface protease belonging to the prolyloligopeptidase family. It selectively removes the N-terminal dipeptide from peptides with proline or alanine in the second position. Apart from its catalytic activity, it interacts with several proteins, for instance, adenosine deaminase, the HIV gp120 protein, fibronectin, collagen, the chemokine receptor CXCR4, and the tyrosine phosphatase CD45. DPP IV is expressed on a specific set of T lymphocytes, where it is up-regulated after activation. It is also expressed in a variety of tissues, primarily on endothelial and epithelial cells. A soluble form is present in plasma and other body fluids. DPP IV has been proposed as a diagnostic or prognostic marker for various tumors, hematological malignancies, immunological, inflammatory, psychoneuroendocrine disorders, and viral infections. DPP IV truncates many bioactive peptides of medical importance. It plays a role in glucose homeostasis through proteolytic inactivation of the incretins. DPP IV inhibitors improve glucose tolerance and pancreatic islet cell function in animal models of type 2 diabetes and in diabetic patients. The role of DPP IV/ CD26 within the immune system is a combination of its exopeptidase activity and its interactions with different molecules. This enables DPP IV/CD26 to serve as a co-stimulatory molecule to influence T cell activity and to modulate chemotaxis. DPP IV is also implicated in HIV-1 entry, malignant transformation, and tumor invasion.

Neuropeptide Y effects on murine natural killer activity: changes with ageing and cAMP involvement

Changes in the bidirectional interaction between the nervous and the immune systems have been proposed as a cause of ageing. Neuropeptides, such as neuropeptide Y (NPY), could show different effects on immune function with age. In the present work, we have studied the in vitro action of a wide range of NPY concentrations, i.e. from 10(-13) to 10(-7) M, on natural killer (NK) activity, a function which decreases with age. Spleen, axillary nodes, thymus and peritoneum leukocytes from mice of different ages: young (12+/-2 weeks), adult (24+/-2 weeks), mature (50+/-2 weeks) and old (72+/-2 weeks) were used. Stimulation by NPY of NK activity was observed in adult and mature animals in axillary nodes and thymus, and an inhibition in the spleen from young mice. The specificity of the NPY effect on cytotoxic activity was confirmed using a C-terminal fragment of NPY. Furthermore, cAMP levels in leukocytes were found to be decreased by NPY in adult mice, suggesting an involvement of this messenger system in the NK modulation by this neuropeptide.

The NPY effects on murine leukocyte adherence and chemotaxis change with age. Adherent cell implication

The two-way communication between the nervous and immune system is currently well-known, but the age-related changes in this communication have been scarcely studied. In the present work, we have investigated the in vitro effects of neuropeptide Y (NPY) at concentrations ranging from 10(-13) to 10(-7) M on the adherence and chemotaxis capacities of spleen, axillary node, thymus and peritoneum leukocytes from BALB/c mice. The NPY effect on these functions was examined on cells from animals of four different ages, i.e. young (12+/-2 weeks old), adult (24+/-2 weeks old), mature (50+/-2 weeks old) and old (72+/-2 weeks old). In young animals, NPY stimulates the adherence of leukocytes from spleen, axillary nodes and thymus and inhibits it in cells from peritoneum. In adult animals NPY inhibits the adherence of leukocytes from thymus. These effects disappear with ageing in all locations. Chemotaxis is stimulated by this neuropeptide at all ages in cells from axillary nodes and peritoneum, but this effect is absent in old mice. NPY exerts an inhibitory effect on the chemotaxis of leukocytes from thymus at all ages studied. These NPY effects on leukocytes seem to be carried out through adherent cells.

Age-related changes in the neuropeptide Y effects on murine lymphoproliferation and interleukin-2 production

Neuropeptide Y (NPY) modulates several aspects of the immune response but it is not known whether NPY responsiveness is altered with aging. In this work, the in vitro effect of NPY at concentrations ranging from 10(-)(14) M to 10(-)(7) M on lymphoproliferation has been studied in spleen, axillary node and thymus leukocytes from young, adult, mature and old BALB/c mice. The spontaneous proliferation of spleen lymphocytes from young mice was significantly stimulated by NPY. In response to the mitogen Con A, lymphoproliferation and IL-2 release by lymphocytes were inhibited significantly by NPY, these effects disappearing with aging. The results show that NPY is a modulator of lymphoproliferation and that this effect disappears progressively with age. Moreover, this regulatory role of NPY may be carried out through a decrease in IL-2 production.