More sympathy for autoimmunity with neuropeptide Y?

Cross talk about the role of Neuropeptide Y in CNS disorders and diseases

A peptide composed of a 36 amino acid called Neuropeptide Y (NPY) is employed in a variety of physiological processes to manage and treat conditions affecting the endocrine, circulatory, respiratory, digestive, and neurological systems. NPY naturally binds to G-protein coupled receptors, activating the Y-receptors (Y1-Y5 and y6). The findings on numerous therapeutic applications of NPY for CNS disease are presented in this review by the authors. New targets for treating diseases will be revealed by medication combinations that target NPY and its receptors. This review is mainly focused on disorders such as anxiety, Alzheimer's disease, Parkinson's disease, Huntington's disease, Machado Joseph disease, multiple sclerosis, schizophrenia, depression, migraine, alcohol use disorder, and substance use disorder. The findings from the preclinical studies and clinical studies covered in this article may help create efficient therapeutic plans to treat neurological conditions on the one hand and psychiatric disorders on the other. They may also open the door to the creation of novel NPY receptor ligands as medications to treat these conditions.

Neuron-derived neuropeptide Y fine-tunes the splenic immune responses

The nervous and immune systems are closely entwined to maintain the immune balance in health and disease. Here, we showed that LPS can activate suprarenal and celiac ganglia (SrG-CG) neurons and upregulate NPY expression in rats. Single-cell sequencing analysis revealed that knockdown of the NPY gene in SrG-CG altered the proliferation and activation of splenic lymphocytes. In a neuron and splenocyte coculture system and in vivo experiments, neuronal NPY in SrG-CG attenuated the splenic immune response. Notably, we demonstrated that neuronal NPF in Drosophila exerted a conservative immunomodulatory effect. Moreover, numerous SNPs in NPY and its receptors were significantly associated with human autoimmune diseases, which was further supported by the autoimmune disease patients and mouse model experiments. Together, we demonstrated that NPY is an ancient language for nervous-immune system crosstalk and might be utilized to alleviate inflammatory storms during infection and to modulate immune balance in autoimmune diseases.

The Influence of Modern Neurophysiology on the Previous Definitions of "Segment" and "Interference Field" in Neural Therapy

BACKGROUND

In neural therapy, local anesthetics are injected for diagnostic and therapeutic purposes. Up until now, a distinction has been made between "local/segmental neural therapy" and "interference field therapy". This division dating back to the middle of the last century was based on the assumption that anatomical and clinical segments were identical. However, this is only true for the projection symptoms, which are limited to metamerism. All pathophysiological processes beyond this segment were called "interference field events" ("outside of any segmental order" and "not explainable by neuroanatomical circuitry").

SUMMARY

However, modern neurophysiology no longer recognizes segmental boundaries, taking into account the occurrence of cross-segmental sensitization processes, neuroplastic changes, immune processes, and neurogenic inflammation. In addition, new insights into neuroanatomical circuitry have also contributed to segmental expansion. Thus, the former definition of the interference field effect (considered to be outside any segmental order) is considered obsolete. Nowadays, interference fields are called "neuromodulatory triggers". They can act anywhere, both locally and fairly distant, and even systemically. Key Message: Thus, it is no longer tenable to classify interference field therapy as "unscientific" and "not recognized" while local and segmental neural therapy is being scientifically recognized.

Serum Neuropeptide Y Levels Are Associated with TNF-α Levels and Disease Activity in Rheumatoid Arthritis

Background

Neuropeptide Y (NPY) is a sympathetic neurotransmitter with effects on the regulation of inflammatory cells. The role of NPY on autoimmune inflammatory diseases such as rheumatoid arthritis (RA) is not completely understood. Therefore, we evaluate if NPY levels are markers of disease activity in RA and if there is a correlation between NPY levels and tumor necrosis factor-alpha (TNF-α), leptin, and interleukin 6 (IL-6) levels.

Methods

Cross-sectional design, including 108 women with RA. We assessed disease activity by DAS28-ESR (considering active disease a score of ≥2.6). Serum NPY levels and anti-CCP2 antibody, TNF-α, IL-6, and leptin levels were quantified (ELISA).

Results

Sixty-eight RA had an active disease (RA-active), and 40 were in remission (RA-remission). RA-active patients had higher NPY levels vs. RA-remission (22.8 ± 13.6 vs. 17.8 ± 10.3; p = 0.04). NPY levels correlated with increased TNF-α levels (r = 0.32, p = 0.001). Leptin or IL-6 did not correlate with NPY levels. In the logistic regression analysis, NPY increased the risk of disease activity (OR: 1.04, 95% CI 1.006-1.09, and p = 0.03).

Conclusion

Higher NPY levels are an independent marker of disease activity in RA. This study encourages the quantification of NPY levels as a surrogate marker for RA-active. Future studies evaluating the role of NPY levels interacting with other proinflammatory cytokines are required.

Roles of Neuropeptide Y in Neurodegenerative and Neuroimmune Diseases

Neuropeptide Y (NPY) is a neurotransmitter or neuromodulator that mainly exists in the nervous system. It plays a neuroprotective role in organisms and widely participates in the regulation of various physiological processes in vivo. Studies in both humans and animal models have been revealed that NPY levels are altered in some neurodegenerative and neuroimmune disorders. NPY plays various roles in these diseases, such as exerting a neuroprotective effect, increasing trophic support, decreasing excitotoxicity, regulating calcium homeostasis, and attenuating neuroinflammation. In this review, we will focus on the roles of NPY in the pathological mechanisms of neurodegenerative and neuroimmune diseases, highlighting NPY as a potential therapeutic target in these diseases.

Novel role of NPY in neuroimmune interaction and lung growth after intrauterine growth restriction

Individuals with intrauterine growth restriction (IUGR) are at risk for chronic lung disease. Using a rat model, we showed in our previous studies that altered lung structure is related to IL-6/STAT3 signaling. As neuropeptide Y (NPY), a coneurotransmitter of the sympathetic nervous system, regulates proliferation and immune response, we hypothesized that dysregulated NPY after IUGR is linked to IL-6, impaired myofibroblast function, and alveolar growth. IUGR was induced in rats by isocaloric low-protein diet; lungs were analyzed on embryonic day (E) 21, postnatal day (P) 3, P12, and P23. Finally, primary neonatal lung myofibroblasts (pnF) and murine embryonic fibroblasts (MEF) were used to assess proliferation, apoptosis, migration, and IL-6 expression. At E21, NPY and IL-6 expression was decreased, and AKT/PKC and STAT3/AMPKα signaling was reduced. Early reduction of NPY/IL-6 was associated with increased chord length in lungs after IUGR at P3, indicating reduced alveolar formation. At P23, however, IUGR rats exhibited a catch-up of body weight and alveolar growth coupled with more proliferating myofibroblasts. These structural findings after IUGR were linked to activated NPY/PKC, IL-6/AMPKα signaling. Complementary, IUGR-pnF showed increased survival, impaired migration, and reduced IL-6 compared with control-pnF (Co-pnF). In contrast, NPY induced proliferation, migration, and increased IL-6 synthesis in fibroblasts. Additionally, NPY^-/- mice showed reduced IL-6 signaling and less proliferation of lung fibroblasts. Our study presents a novel role of NPY during alveolarization: NPY regulates 1) IL-6 and lung STAT3/AMPKα signaling, and 2) proliferation and migration of myofibroblasts. These new insights in pulmonary neuroimmune interaction offer potential strategies to enable lung growth.

Association study of two functional single nucleotide polymorphisms of neuropeptide y gene with multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system characterized by brain inflammation, demyelination and axonal loss. Neuropeptide Y (NPY) has a critical role in the maintenance of homeostasis in the immune system and coping of stress condition. In the current study we analyzed 188 patients suffering from MS and 204 unrelated healthy controls for two functional single nucleotide polymorphisms (SNPs), NPY 20T>C (rs16139) and NPY -485T>C (rs16147) using PCR-RFLP and Mismatch PCR-RFLP methods. Our results demonstrated that homozygocity in the minor allele for NPY -485T>C polymorphism is associated with the MS risk in patients in compare with healthy controls (CC vs. TT, P=0.033; CC vs. TT+TC, P=0.02). In addition, by comparison with allele T, the frequency of NPY -485C allele was higher in cases than in control subjects and present increased risk of MS, but statistically significant was borderline (P=0.053). The stratification for disease progression revealed a significant difference in the allelic and genotypic distribution between subgroups of MS and controls. The frequency of the CC genotype and C allele was higher in the primary progressive MS patients when compared with control group (CC vs. TT, P=0.019; CC vs. TT+TC, P=0.008; C vs. T, P=0.022). In addition, the frequency of CC genotype was higher in the relapsing remitting MS patients when compared with control group (CC vs. TT, P=0.034; CC vs. TT+TC, P=0.016). Haplotype analysis demonstrated that the haplotype 3 (CT) is more common in RR MS (P=0.041), and PP MS (P=0.031) than control group. In conclusion, the obtained results demonstrate the probable role of NPY SNPs in susceptibility to MS within the Iranian population.

Modulation of Dental Inflammation by the Sympathetic Nervous System

Recent findings have indicated that immune responses are subjected to modulation by the sympathetic nervous system (SNS). Moreover, the findings show that the SNS inhibits the production of pro-inflammatory cytokines, while stimulating the production of anti-inflammatory cytokines. The present review is an attempt to summarize the current results on how the SNS affects inflammation in dental tissues. In dental tissues, it has been found that the SNS is significant for recruitment of inflammatory cells such as CD 43+ granulocytes. Sympathetic nerves appear to have an inhibitory effect on osteoclasts, odontoclasts, and on IL-1α production. The SNS stimulates reparative dentin production, since reparative dentin formation was reduced after sympathectomy. Sprouting of sympathetic nerve fibers occurs in chronically inflamed dental pulp, and neural imbalance caused by unilateral sympathectomy recruits immunoglobulin-producing cells to the dental pulp. In conclusion, this article presents evidence in support of interactions between the sympathetic nervous system and dental inflammation.

Association of neuropeptide Y (NPY), interleukin-1B (IL1B) genetic variants and correlation of IL1B transcript levels with vitiligo susceptibility

BACKGROUND

Vitiligo is a depigmenting disorder resulting from loss of functional melanocytes in the skin. NPY plays an important role in induction of immune response by acting on a variety of immune cells. NPY synthesis and release is governed by IL1B. Moreover, genetic variability in IL1B is reported to be associated with elevated NPY levels.

OBJECTIVES

Aim of the present study was to explore NPY promoter -399T/C (rs16147) and exon2 +1128T/C (rs16139) polymorphisms as well as IL1B promoter -511C/T (rs16944) polymorphism and to correlate IL1B transcript levels with vitiligo.

METHODS

PCR-RFLP method was used to genotype NPY -399T/C SNP in 454 patients and 1226 controls; +1128T/C SNP in 575 patients and 1279 controls and IL1B -511C/T SNP in 448 patients and 785 controls from Gujarat. IL1B transcript levels in blood were also assessed in 105 controls and 95 patients using real-time PCR.

RESULTS

Genotype and allele frequencies for NPY -399T/C, +1128T/C and IL1B -511C/T SNPs differed significantly (p<0.0001, p<0.0001; p = 0.0161, p = 0.0035 and p<0.0001, p<0.0001) between patients and controls. 'TC' haplotype containing minor alleles of NPY polymorphisms was significantly higher in patients and increased the risk of vitiligo by 2.3 fold (p<0.0001). Transcript levels of IL1B were significantly higher, in patients compared to controls (p = 0.0029), in patients with active than stable vitiligo (p = 0.015), also in female patients than male patients (p = 0.026). Genotype-phenotype correlation showed moderate association of IL1B -511C/T polymorphism with higher IL1B transcript levels. Trend analysis revealed significant difference between patients and controls for IL1B transcript levels with respect to different genotypes.

CONCLUSION

Our results suggest that NPY -399T/C, +1128T/C and IL1B -511C/T polymorphisms are associated with vitiligo and IL1B -511C/T SNP influences its transcript levels leading to increased risk for vitiligo in Gujarat population. Up-regulation of IL1B transcript in patients advocates its possible role in autoimmune pathogenesis of vitiligo.

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.

Neuropeptide analysis of oral mucosa in diabetic rats

OBJECTIVE

Increasing evidence indicates that different neuropeptide-containing nerve elements are involved in the immune system and influence the inflammation of the gastrointestinal tract. The aim of this study was to investigate the morphological localization and distribution of the different immunoreactive (IR) nerve fibers and immunocompetent cells in the oral mucosa (e.g. tongue, gingiva) and compare the results with data received from streptozotocin (STZ)-induced diabetic rats.

MATERIALS AND METHODS

The different nerve elements and immunocytes were detected by ABC immunohistochemistry.

RESULTS

The IR nerve fibers were found in the tunica propria of oral mucosa with different densities. These IR nerve fibers were mainly located beneath the epithelial lining, around the blood vessels and glands, and some of them were also located in the taste buds. After 2 weeks of STZ treatment the total number of IR nerve fibers, especially the SP and neuropeptide Y (NPY) IR ones, was significantly increased (p < 0.05), as was also the number of immunocytes (lymphocytes, plasma cells, mast cells). Some of these cells also showed immunoreactivity for substance P (SP) and NPY. In several cases the SP IR nerve fibers were found in close proximity to the immunocytes. Electron microscopic investigation also revealed the close association between the IR nerve fibers and immunocompetent cells where the gap was 1 µm or even less.

CONCLUSIONS

The close anatomical associations suggest communication between nerve fibers and immune cells which can be crucial for maintaining mucosal homeostasis and for ensuring an appropriate response to injury.

Analysis of nerve supply pattern in human lymphatic vessels of young and old men

BACKGROUND

The present work deals with innervation patterns along collector lymphatic vessels from cervical, mesenteric, and femoral regions, and lymph capillaries in young and elderly subjects.

METHODS AND RESULTS

Morphological and morphometric analysis of nerve fibers along lymph vessels was performed by immunohistochemistry for PGP 9.5, NPY, TH, ChAT, VIP, SP, and dopamine. Nerves containing NPY and TH were frequent, whereas immunoreactivity for ChAT and VIP were few. SP-positive fibers were widely distributed in the medial and endothelial layers. Dopamine neurotransmitters were observed in a few short nerve fibers. A more diffuse presence of nerve fibers in mesenteric and femoral lymph vessels, compared to cervical ones, was detected. In lymph capillary vessels, a few nerve fibers positive for neuropeptides and neurotransmitters were detected, whereas no dopamine and VIP immunoreactive fibers were detected. A wide reduction of all specific nerve fibers analyzed was detected in lymph vessels from elderly subjects.

CONCLUSIONS

The presence on lymph vessels of sympathetic and parasympathetic nerve systems can be declared. The differences observed in lymphatic vessel innervation patterns may note the involvement in lymph flow regulation, calling attention in aging, when nerve fibers reduction may cause functional default of lymph vessels.

NPY and NPY receptors in airway structural and inflammatory cells in allergic asthma

PURPOSE

Neuropeptide Y (NPY) level is elevated in allergic asthmatic airways and activation of NPY receptor-1 (NPY-Y1) on antigen-presenting cells (APCs) is essential for T cell priming. Paradoxically, NPY-Y1 modulates hyper-responsiveness in T cells, suggesting a bimodal role for NPY in APCs and T cells. Therefore, determination of the temporal and spatial expression pattern of NPY and its receptors in asthmatic airways is essential to further understand the role of NPY in allergic asthma.

METHODS

Lungs were isolated from control and acute and chronic stages of OVA-sensitized and challenged mice (OVA). Stains, including H&E, PAS, and trichrome, were used to determine the severity of lung pathology. The expression patterns of NPY and NPY-Y receptors in the airways were determined using ELISA and immunofluorescence. Cytokine levels in the BALF were also measured.

RESULTS

NPY levels were undetectable in the BALF of control mice, but significantly increased in the OVA group at day 80. Levels of IL-4, TGF-β1 and TGF-β2, significantly increased and peaked on day 45 and decreased on day 80 in the OVA group, exhibiting an inverse correlation with NPY levels. NPY expression was localized to macrophage-like cells in the peri-bronchial and peri-vascular areas in the lung tissue. NPY-Y1 and -Y5 receptors were constitutively expressed by both structural and inflammatory cells in the lung tissue.

CONCLUSIONS

NPY produced by activated macrophage-like cells may be involved in regulating cytokine production and cellular activities of immune cells in asthma. However, it remains unclear whether such an increase in NPY is a defensive/compensatory mechanism to modulate the effects of inflammatory cytokines.

Neuropeptide Y inhibits interleukin-1β-induced phagocytosis by microglial cells

Background

Neuropeptide Y (NPY) is emerging as a modulator of communication between the brain and the immune system. However, in spite of increasing evidence that supports a role for NPY in the modulation of microglial cell responses to inflammatory conditions, there is no consistent information regarding the action of NPY on microglial phagocytic activity, a vital component of the inflammatory response in brain injury. Taking this into consideration, we sought to assess a potential new role for NPY as a modulator of phagocytosis by microglial cells.

Methods

The N9 murine microglial cell line was used to evaluate the role of NPY in phagocytosis. For that purpose, an IgG-opsonized latex bead assay was performed in the presence of lipopolysaccharide (LPS) and an interleukin-1β (IL-1β) challenge, and upon NPY treatment. A pharmacological approach using NPY receptor agonists and antagonists followed to uncover which NPY receptor was involved. Moreover, western blotting and immunocytochemical studies were performed to evaluate expression of p38 mitogen-activated protein kinase (MAPK) and heat shock protein 27 (HSP27), in an inflammatory context, upon NPY treatment.

Results

Here, we show that NPY inhibits phagocytosis of opsonized latex beads and inhibits actin cytoskeleton reorganization triggered by LPS stimulation. Co-stimulation of microglia with LPS and adenosine triphosphate also resulted in increased phagocytosis, an effect inhibited by an interleukin-1 receptor antagonist, suggesting involvement of IL-1β signaling. Furthermore, direct application of LPS or IL-1β activated downstream signaling molecules, including p38 MAPK and HSP27, and these effects were inhibited by NPY. Moreover, we also observed that the inhibitory effect of NPY on phagocytosis was mediated via Y₁ receptor activation.

Conclusions

Altogether, we have identified a novel role for NPY in the regulation of microglial phagocytic properties, in an inflammatory context.

Neuropeptides of human thymus in normal and pathological conditions

Human thymus of healthy subjects and patients affected by thymoma-associated Myastenia Gravis were studied in order to visualize and compare the morphological distributive pattern of four neuropeptides: vasoactive intestinal peptide, substance P, neuropeptide Y, and neurotensin. Based on our observations, we formulated hypotheses on their relations in neuro-immunomodulation under physiological and pathophysiological conditions. Immuno-histochemical staining for neuropeptides was performed and morphological and morphometrical analyses were conducted on healthy and diseased thymus. In normal thymus, a specific distributive pattern was observed for the several neuropeptide-positive nerves in different thymus lobular zones. In particular substance P-positive fibers were observed in subcapsular zone, specifically located into parenchyma, where they represent the almost total amount of fibers; neurotensin-positive fibers were observed primarily located in parenchyma than perivascular site of several thymus lobular zones, and more abundant the cortico-medullary and medullary zones. Instead VIP- and NPY-positive fibers were widely distributed in perivascular and parenchymal sites of several thymus lobular zones. In thymoma, the distribution of neuropeptide-positive fibers was quantitatively reduced, while cells immunopositive to VIP and substance P were quantitatively increased and dispersed. Observation of the perivascular and parenchymal distribution of the analyzed neuropeptides suggests evidence that a regulatory function is performed by nerves and cells that secrete neuropeptide into the thymus. The alteration of neuropeptide patterns in thymoma suggests that these neurotransmitters play a role in autoimmune diseases such as Myastenia Gravis.

Attenuation of pain-related behavior evoked by injury through blockade of neuropeptide Y Y2 receptor

Neuropeptide Y (NPY) has an important but still insufficiently defined role in pain modulation. We therefore examined the ability of NPY to modulate experimentally induced neuropathic pain by injecting it directly into dorsal root ganglion (DRG) immediately following spinal nerve ligation (SNL) injury. We have found that this application exacerbates pain-related behavior induced by SNL in a modality-specific fashion. When saline was injected after SNL, the expected increase in hyperalgesia responses to needle stimulation was present on the 8th postoperative day. When we injected NPY, hyperalgesic responses were increased in a manner similar to the SNL/saline group. To characterize NPY action, specific Y1 and Y2 antagonists were also delivered directly to DRG, which revealed that behavioral actions of NPY were abolished by Y2 receptor antagonist. We tested whether NPY effects were the result of its role in immunity by immunohistochemical staining for glial fibrillary acidic protein, in order to identify activation of DRG satellite cells and dorsal horn astrocytes. Exacerbation of pain-related behavior following NPY injection was accompanied by astrocyte activation in ipsilateral dorsal horn and with satellite cells activation in the DRG proximal to injury. This activation was reduced following Y2 receptor antagonist application. These findings indicate an important link between pain-related behavior and neuroimmune activation by NPY through its Y2 receptor.

Neuropeptide Y modulation of interleukin-1{beta} (IL-1{beta})-induced nitric oxide production in microglia

Given the modulatory role of neuropeptide Y (NPY) in the immune system, we investigated the effect of NPY on the production of NO and IL-1β in microglia. Upon LPS stimulation, NPY treatment inhibited NO production as well as the expression of inducible nitric-oxide synthase (iNOS). Pharmacological studies with a selective Y(1) receptor agonist and selective antagonists for Y(1), Y(2), and Y(5) receptors demonstrated that inhibition of NO production and iNOS expression was mediated exclusively through Y(1) receptor activation. Microglial cells stimulated with LPS and ATP responded with a massive release of IL-1β, as measured by ELISA. NPY inhibited this effect, suggesting that it can strongly impair the release of IL-1β. Furthermore, we observed that IL-1β stimulation induced NO production and that the use of a selective IL-1 receptor antagonist prevented NO production upon LPS stimulation. Moreover, NPY acting through Y(1) receptor inhibited LPS-stimulated release of IL-1β, inhibiting NO synthesis. IL-1β activation of NF-κB was inhibited by NPY treatment, as observed by confocal microscopy and Western blotting analysis of nuclear translocation of NF-κB p65 subunit, leading to the decrease of NO synthesis. Our results showed that upon LPS challenge, microglial cells release IL-1β, promoting the production of NO through a NF-κB-dependent pathway. Also, NPY was able to strongly inhibit NO synthesis through Y(1) receptor activation, which prevents IL-1β release and thus inhibits nuclear translocation of NF-κB. The role of NPY in key inflammatory events may contribute to unravel novel gateways to modulate inflammation associated with brain pathology.

Dental pulp fibroblasts express neuropeptide Y Y1 receptor but not neuropeptide Y

AIM

To investigate whether dental pulp fibroblasts express neuropeptide Y (NPY) and NPY-Y1 in vitro and to determine the effects of the cytokines including interleukin-1β (IL-1β), TGF- β(1) , substance P and NPY on the expression of NPY Y1.

METHODOLOGY

Three primary fibroblast cell strains were obtained from freshly extracted human third molar teeth. RT-PCR was utilized to detect expression of NPY and mRNA expression. Membrane protein samples were isolated, and protein expression was determined by Western blotting. Radioimmunoassay was used to quantify NPY expression in healthy (n = 35) and carious (n = 39) whole pulp samples, and the student's t-test was used to test for statistical significance. In addition, the 3-(4,5-Dimethylthiazol,2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to assay fibroblast cell growth.

RESULTS

mRNA transcripts were found in all three fibroblast cell populations with the cytokines having a stimulatory effect on its expression (P < 0.05). NPY mRNA was not detected in the cell strains. NPY-Y1 receptor protein expression was visualized by Western blotting, and there was no effect of IL-1β or TGF- β(1) on its expression. The mean concentration of NPY-Ir determined by radioimmunoassay in non-carious teeth was 19.40 ng x g(-1) (±17.03 SD) compared to 29.95 ng x g(-1) (±20.99 SD) in carious teeth (P < 0.05).

CONCLUSION

Human dental pulp fibroblasts express, but do not synthesize, NPY, demonstrating that the fibroblast is a target cell for NPY. The effect of proinflammatory cytokines suggests that fibroblasts play a neuroimmunomodulatory role in the pulpal response to dental caries and injury.

The anti-inflammatory effect of neuropeptide Y (NPY) in rats is dependent on dipeptidyl peptidase 4 (DP4) activity and age

Neuropeptide Y (NPY)-induced modulation of the immune and inflammatory responses is regulated by tissue-specific expression of different receptor subtypes (Y1-Y6) and the activity of the enzyme dipeptidyl peptidase 4 (DP4, CD26) which terminates the action of NPY on Y1 receptor subtype. The present study investigated the age-dependent effect of NPY on inflammatory paw edema and macrophage nitric oxide production in Dark Agouti rats exhibiting a high-plasma DP4 activity, as acknowledged earlier. The results showed that NPY suppressed paw edema in adult and aged, but not in young rats. Furthermore, plasma DP4 activity decreased, while macrophage DP4 activity, as well as macrophage CD26 expression increased with aging. The use of NPY-related peptides and Y receptor-specific antagonists revealed that anti-inflammatory effect of NPY is mediated via Y1 and Y5 receptors. NPY-induced suppression of paw edema in young rats following inhibition of DP4 additionally emphasized the role for Y1 receptor in the anti-inflammatory action of NPY. In contrast to the in vivo situation, NPY stimulated macrophage nitric oxide production in vitro only in young rats, and this effect was mediated via Y1 and Y2 receptors. It can be concluded that age-dependant modulation of inflammatory reactions by NPY is determined by plasma, but not macrophage DP4 activity at different ages.

Autonomic renal denervation ameliorates experimental glomerulonephritis

Increasing evidence indicates that inflammation of visceral organs is significantly affected by the autonomic nervous system. Such neuroimmune interactions have not been studied in the kidney. Here, we show that the rat kidney is innervated by both tyrosine hydroxylase-positive sympathetic efferent nerve fibers and calcitonin gene-related peptide-positive primary afferent nerve fibers, both of which are found in proximity to macrophages and dendritic cells. Complete surgical bilateral renal denervation was performed 2 d before glomerulonephritis was induced by injecting the monoclonal anti-Thy-1.1 antibody OX-7. Denervation significantly reduced albuminuria, mesangiolysis, formation of microaneurysms, deposition of glomerular collagen IV, and expression of TGF-beta compared with sham-operated controls. Accordingly, inflammation, identified by accumulation of interstitial macrophages and renal expression of TNF-alpha, and mesangial cell proliferation were significantly reduced. These findings indicate that autonomic renal denervation ameliorates and, by inference, innervation exacerbates acute inflammation in the kidney; therefore, neurotransmitters or neuropeptides and their receptors might represent novel targets for the treatment of acute glomerulonephritis.

Review: Brain—immune communication psychoneuroimmunology of multiple sclerosis

The central nervous system (CNS) and the immune system are two extremely complex and highly adaptive systems. In the face of a real or anticipated threat, be it physical (eg, infection) or psychological (eg, psychosocial stress) in nature, the two systems act in concert to provide optimal adaptation to the demanding internal or environmental conditions. During instances of well being, the communication between these two systems is well tuned and balanced. However, a disturbed crosstalk between the CNS and the immune system is thought to play a major role in a wide series of disorders characterized by a hyporesponsive or hyperresponsive immune system. In multiple sclerosis (MS), a chronic inflammatory and neurodegenerative disease, an excess of inflammatory processes seems to be a hallmark and there is growing evidence for a disturbed communication between the CNS and the immune system as a crucial pathogenic factor. While the exact mechanisms for these phenomena are still poorly understood, the young discipline of psychoneuroimmunology (PNI), which focuses on the mechanism underlying the brain to immune crosstalk, might offer some insights into the existing pathogenic mechanisms. Findings from the field of PNI might also help to gain a better understanding regarding the origin and course of MS clinical symptoms such as fatigue and depression.

Beta-adrenoceptor blockade ameliorates the clinical course of experimental allergic encephalomyelitis and diminishes its aggravation in adrenalectomized rats

As glucocorticoids influence both catecholamine synthesis and adrenoceptor expression by immune cells, the current study was undertaken to distinguish their direct effects on the development of experimental allergic encephalomyelitis from those induced by alteration of catecholamine signaling. We examined the influence of 16-day-long beta-adrenoceptor blockade with propranolol (0.40 mg/100 g body weight/day, s.c.) beginning 3 days before immunization on the development of experimental allergic encephalomyelitis in adrenalectomized (7 days before immunization) and in non-operated male Dark Agouti rats. Adrenalectomy aggravated the clinical course of experimental allergic encephalomyelitis. In contrast, propranolol attenuated both the clinical signs of the disease and decreased the number of lesions in the spinal cord. Furthermore, propranolol prevented adrenalectomy-induced aggravation of the disease course without affecting mortality. We also found that the percentage of CD4(+)CD25(+) T lymphocytes (recently activated or regulatory cells) was increased in peripheral blood of experimental allergic encephalomyelitis rats over that in the corresponding non-immunized and bovine serum albumin immunized rats. However, the percentage of these cells was reduced in adrenalectomized and/or propranolol-treated experimental allergic encephalomyelitis rats compared to control experimental allergic encephalomyelitis rats. Our findings, coupled with the clinical course of the disease and the underlying pathomorphological changes, clearly suggest that differential mechanisms were responsible for the changes in the percentage of CD4(+)CD25(+) T lymphocytes in propranolol-treated adrenalectomized rats and only propranolol-treated rats with experimental allergic encephalomyelitis. Our results, when viewed globally, indicate that: i) beta-adrenoceptor-dependent mechanisms are involved in the immunopathogenesis of experimental allergic encephalomyelitis, ii) experimental allergic encephalomyelitis has a more severe course in adrenalectomized rats and iii) beta-adrenoceptor-mediated mechanisms operate in adrenalectomy-induced aggravation of the disease.

A novel range based QSAR study of human neuropeptide Y (NPY) Y5 receptor inhibitors

A conventional QSAR study has been carried out using thermodynamic and other descriptors, on a set of arylsulfonamidomethylcyclohexyl derivatives as antagonists of potential obesity drug target human neuropeptide Y Y5 receptor. In addition, a novel range based method was applied to obtain a QSAR model so that the information contained in the compounds for which an approximate value instead of exact value of inhibitory activity was available could be included in the model. Analysis of models suggests that range based model is better in screening biologically active compounds from chemical library. The conventional model is able to predict activity accurately only for active compounds whereas the range based method is better in discriminating active and inactive compounds.

Cytokines and the immune–neuroendocrine network: What did we learn from infection and autoimmunity?

The initial view of the neuroendocrine-immune communication as the brake of immune activation is changing. Recent evidence suggests that the optimization of the body's overall response to infection could be actually the role of the immune-endocrine network. In gradually more complex organisms, the multiplicity of host-pathogen interfaces forced the development of efficient and protective responses. Molecules such as cytokines and Toll-like receptors (TLRs) are distributed both in the periphery and in the brain to participate in a coordinated adaptive function. When sustained release of inflammatory mediators occurs, as in autoimmune diseases, undesirable pathological consequences become evident with different manifestations and outcomes. Clearly, organisms are not well adapted to that disregulated condition yet, suggesting that additional partners within neuroendocrine-immune interactions might emerge from the evolutionary road.

The Y1 receptor for NPY: a key modulator of the adaptive immune system

Growing evidence suggests that the neuropeptide Y (NPY) system plays an important role in the immune system. Yet, little is known about the expression of NPY and receptors in the immune system. Moreover, original contradicting results have confused the picture and hampered a clear understanding of its role in the immune system. The use of Y(1) receptor-deficient mice, combined with advanced methods to investigate immune functions, have provided the solution to the problem raised by previous disparities. From results obtained using Y(1)-deficient mice (Y(1)(-/-)), we uncovered a bimodal role for Y(1) on immune cells. Y(1) expression on antigen-presenting cells (APC) is essential for their function as T cell priming elements. Conversely, Y(1) signaling in T cells plays a regulatory role without which T cells are hyper-responsive. The opposite role of Y(1) on APC and T cells has reconciled previous disparities by showing that signaling via Y(1) protects against inflammation by inhibiting T cell responses, whereas Y(1)(-/-) mice are protected in the same inflammatory models due to defective APCs.

A role for neuropeptide Y (NPY) in phagocytosis: implications for innate and adaptive immunity

Although it is broadly accepted that the immune system and the nervous system functionally interact with each other at various levels, many aspects of this crosstalk still remain unclear. One player in this interaction is neuropeptide Y (NPY), a sympathetic neurotransmitter, which has been demonstrated to regulate a broad variety of immune functions. In this review we will outline key findings on the effects NPY exerts on phagocytosis by neutrophils and monocytes/macrophages and its relevance to the elimination of invading pathogens. Furthermore, we will discuss the implications of these findings for antigen presentation by dendritic cells and the induction of adaptive immune responses.

G protein-coupled receptor 83 overexpression in naive CD4+CD25- T cells leads to the induction of Foxp3+ regulatory T cells in vivo

Foxp3 functions as a lineage specification factor for the development of naturally occurring thymus-derived CD4+CD25+ regulatory T (Treg) cells. Recent evidence suggests that naive Foxp3-CD4+CD25- T cells can be converted in the periphery into Foxp3+ Treg cells. In this study, we have identified the G protein-coupled receptor (GPR)83 to be selectively up-regulated by CD4+CD25+ Treg cells of both murine and human origin in contrast to naive CD4+CD25- or recently activated T cells. Furthermore, GPR83 was induced upon overexpression of Foxp3 in naive CD4+CD25- T cells. Transduction of naive CD4+CD25- T cells with GPR83-encoding retroviruses did not confer in vitro suppressive activity. Nevertheless, GPR83-transduced T cells were able to inhibit the effector phase of a severe contact hypersensitivity reaction of the skin, indicating that GPR83 itself or GPR83-mediated signals conferred suppressive activity to conventional CD4+ T cells in vivo. Most strikingly, this in vivo acquisition of suppressive activity was associated with the induction of Foxp3 expression in GPR83-transduced CD4+ T cells under inflammatory conditions. Our results suggest that GPR83 might be critically involved in the peripheral generation of Foxp3+ Treg cells in vivo.

Sympathetic nervous system plays an important role in the relationship between immune mediated diseases

T helper (Th) lymphocytes have been classified into distinct subsets, Th1 and Th2 on the basis of the cytokines they produce. According to the cross-regulatory properties of Th1 and Th2 cells, one would assume that to be affected by a Th1 type disease increases susceptibility to a Th1 type disease and inhibits a Th2 type disease and vice versa about being affected by a Th2 type disease. However, the pattern of related diseases does not necessarily follow the conventional pattern of inhibitory effects of Th1 and Th2 immune responses on each other. For example, Mycobacteria including BCG, that induce Th1 immune responses; can modulate some Th1 type autoimmune diseases including MS, experimental autoimmune encephalomyelitis (EAE; an animal model for Multiple Sclerosis) and insulin-dependent diabetes mellitus (IDDM) thereby leading to an alleviation of their symptoms. Also BCG precipitates a syndrome similar to systemic lupus erythematosus (SLE), a Th2 type disease; in NOD mice. The coexistence of the major Th2-mediated atopic diseases such as asthma, eczema and allergic rhinitis with the Th1-mediated autoimmune conditions including; coeliac disease (CD), IDDM, rheumatoid arthritis (RA) and psoriasis is another example that is in apparent disagreement with counter-regulatory effects of Th1/Th2 phenotypes.

HYPOTHESIS

SNS can be stimulated by pro-inflammatory cytokines, production of which is induced by mycobacteria including BCG. Although these cytokines can inhibit SNS activity in the site of inflammation and secondary lymphoid organs, they increase sympathetic tone in other places. Increased sympathetic tone can induce an anti-inflammatory and Th2 type milieu. This milieu can inhibit MS and IDDM and provide a susceptible environment for starting of SLE. Atopic diseases are Th2 type immune mediated diseases; therefore, they increase the production of Th2 type cytokine and decrease production of pro-inflammatory cytokines in the site of allergic reaction and also in secondary lymphoid organs. Therefore, atopic diseases decrease sympathetic tone in all tissues except in the sites of allergic reaction and secondary lymphoid organs. Decreased sympathetic tone results in a pro-inflammatory milieu and in such an environment, Th1 type autoimmune diseases can affect tissues.

Quantitative structure activity relationship of benzoxazinone derivatives as neuropeptide Y Y5 receptor antagonists

Quantitative structure activity relationship (QSAR) has been established for 30 benzoxazinone derivatives acting as neuropeptide Y Y5 receptor antagonists. The genetic algorithm and multiple linear regression were used to generate the relationship between biological activity and calculated descriptors. Model with good statistical qualities was developed using four descriptors from topological, thermodynamic, spatial and electrotopological class. The validation of the model was done by cross validation, randomization and external test set prediction.

A neuropeptide in immune-mediated inflammation, Y?

Disturbances in crosstalk between the immune system and the sympathetic nervous system (SNS) can contribute to the pathogenesis of Th1-mediated autoimmunity. Recent studies indicate that neuropeptide Y (NPY) has a major role in the regulation of Th1 responses. The precise role of NPY has been an enigma, but a recent study provides a breakthrough, demonstrating that NPY has a bimodal role as a negative regulator of T cells and an activator of antigen-presenting cell function.

A fundamental bimodal role for neuropeptide Y1 receptor in the immune system

Psychological conditions, including stress, compromise immune defenses. Although this concept is not novel, the molecular mechanism behind it remains unclear. Neuropeptide Y (NPY) in the central nervous system is a major regulator of numerous physiological functions, including stress. Postganglionic sympathetic nerves innervating lymphoid organs release NPY, which together with other peptides activate five Y receptors (Y1, Y2, Y4, Y5, and y(6)). Using Y1-deficient (Y1(-/-)) mice, we showed that Y1(-/-) T cells are hyperresponsive to activation and trigger severe colitis after transfer into lymphopenic mice. Thus, signaling through Y1 receptor on T cells inhibits T cell activation and controls the magnitude of T cell responses. Paradoxically, Y1(-/-) mice were resistant to T helper type 1 (Th1) cell-mediated inflammatory responses and showed reduced levels of the Th1 cell-promoting cytokine interleukin 12 and reduced interferon gamma production. This defect was due to functionally impaired antigen-presenting cells (APCs), and consequently, Y1(-/-) mice had reduced numbers of effector T cells. These results demonstrate a fundamental bimodal role for the Y1 receptor in the immune system, serving as a strong negative regulator on T cells as well as a key activator of APC function. Our findings uncover a sophisticated molecular mechanism regulating immune cell functions that can lead to stress-induced immunosuppression.

The role of stress-response systems for the pathogenesis and progression of MS

Disease progression in multiple sclerosis (MS)--an inflammatory demyelinating and neurodegenerative disease with a presumed T-cell driven autoimmune origin--has long been hypothesized to be associated with stress. However, this notion has only recently been supported by prospective clinical studies. Several clinical and molecular studies in MS and its animal models have recently shown disruptions in the communication between the immune system and the two major stress response systems, the hypothalamo-pituitary-adrenal (HPA) axis and the autonomic nervous system. Insensitivity to glucocorticoid and beta-adrenergic modulation might be involved in overshooting inflammation in MS, whereas hyperactivity of the HPA axis has been linked to neurodegeneration and increased disability. Here, we integrate findings from molecular, cellular, experimental, clinical and epidemiological research to describe the involvement of stress response systems in MS pathogenesis and progression.

Without nerves, immunology remains incomplete -in vivo veritas

Interest in the interactions between nervous and immune systems involved in both pathological and homeostatic mechanisms of host defence has prompted studies of neuroendocrine immune modulation and cytokine involvement in neuropathologies. In this review we concentrate on a distinct area of homeostatic control of both normal and abnormal host defence activity involving the network of peripheral c-fibre nerve fibres. These nerve fibres have long been recognized by dermatologists and gastroenterologists as key players in abnormal inflammatory processes, such as dermatitis and eczema. However, the involvement of nerves can all too easily be regarded as that of isolated elements in a local phenomenon. On the contrary, it is becoming increasingly clear that neural monitoring of host defence activities takes place, and that involvement of central/spinal mechanisms are crucial in the co-ordination of the adaptive response to host challenge. We describe studies demonstrating neural control of host defence and use the specific examples of bone marrow haemopoiesis and contact sensitivity to highlight the role of direct nerve fibre connections in these activities. We propose a host monitoring system that requires interaction between specialized immune cells and nerve fibres distributed throughout the body and that gives rise to both neural and immune memories of prior challenge. While immunological mechanisms alone may be sufficient for local responsiveness to subsequent challenge, data are discussed that implicate the neural memory in co-ordination of host defence across the body, at distinct sites not served by the same nerve fibres, consistent with central nervous mediation.

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.

Gastrin-releasing peptide, substance P and cytokines in rheumatoid arthritis

Many studies have shown that modulation of cytokine function is effective in ameliorating symptoms of rheumatoid arthritis. Neuropeptides have recently been shown to have powerful effects on the production and release of cytokines and have also been shown to exert potent proinflammatory and anti-inflammatory effects in animal models of inflammatory diseases. An analysis of cytokine and neuropeptide content of synovial fluid from patients with rheumatoid arthritis has revealed a significant correlation between two neuropeptides, bombesin/gastrin-releasing peptide and substance P, and the proinflammatory cytokine interleukin-6 as well as the erythrocyte sedimentation rate. These findings provide further evidence for a role of neuropeptides and cytokines in the pathophysiology of rheumatoid arthritis, as well as suggesting additional approaches for the development of novel therapeutic interventions.

Effects of Some Kampo Medicines on Plasma Levels of Neuropeptide Y under Venipuncture Stress

Some traditional Chinese herbal (Kampo) medicines have recently been evaluated for their clinical usefulness in stress and depression. These medicines have modulatory effects on the hypothalamic-pituitary-adrenal axis and sympathetic nervous system (SNS). We examined the effects of Rikkunshi-to, Hange-shashin-to, Hange-koboku-to, and Ninjin-to on plasma levels of neuropeptide Y (NPY), which is the representative neurotransmitter of the SNS, under venipuncture stress. Rikkunshi-to and Hange-shashin-to suppressed increases in plasma NPY-immunoreactive substance levels compared with the response to a placebo. In this study, Rikkunshi-to and Hange-shashin-to altered plasma levels of NPY under venipuncture stress. These effects might be beneficial in stress-related diseases and our results suggest that these medicines have clinical pharmacologic activity.