Release of vasoactive intestinal polypeptide in mast cells by histamine liberators

Neuro-immune regulation in allergic Diseases: Role of neuropeptides

The role of neuro-immune interaction in allergic diseases, a group of common immune system diseases, has garnered increasing attention. Neuropeptides, as a crucial component of neuro-immune crosstalk with local neuroendocrine and signaling functions, play a significant role that must not be overlooked. Neuropeptides are released by neurons and even some immune cells, and mediate neuro-immune crosstalk by activating relevant specific receptors on immune cells. Recent studies have found that neuropeptides have a certain regulatory effect on allergic diseases, which could be beneficial or detrimental for the development of allergic diseases. Nevertheless, the precise mechanism of neuropeptides in allergic diseases remains unclear, particularly in the context of food allergy where their role is poorly understood. This review summarized the interplay between neuropeptides and different immune cells, as well as their current research progress in several common allergic diseases: atopic dermatitis, allergic asthma, and food allergy. It is evident that neuropeptides such as substance P, calcitonin gene-related peptide, vasoactive intestinal peptide, and neuromedin U, exert important regulatory effects on allergic diseases, yet further investigation is required to fully elucidate their mechanisms of action, which may contribute to better understanding of the onset and progression of allergic diseases and finding better immunomodulatory strategies.

Neuroimmune interplay during type 2 inflammation: Symptoms, mechanisms, and therapeutic targets in atopic diseases

Type 2 inflammation is characterized by overexpression and heightened activity of type 2 cytokines, mediators, and cells that drive neuroimmune activation and sensitization to previously subthreshold stimuli. The consequences of altered neuroimmune activity differ by tissue type and disease; they include skin inflammation, sensitization to pruritogens, and itch amplification in atopic dermatitis and prurigo nodularis; airway inflammation and/or hyperresponsiveness, loss of expiratory volume, airflow obstruction and increased mucus production in asthma; loss of sense of smell in chronic rhinosinusitis with nasal polyps; and dysphagia in eosinophilic esophagitis. We describe the neuroimmune interactions that underlie the various sensory and autonomic pathologies in type 2 inflammatory diseases and present recent advances in targeted treatment approaches to reduce type 2 inflammation and its associated symptoms in these diseases. Further research is needed to better understand the neuroimmune mechanisms that underlie chronic, sustained inflammation and its related sensory pathologies in diseases associated with type 2 inflammation.

Navigating the blurred path of mixed neuroimmune signaling

Evolution has created complex mechanisms to sense environmental danger and protect tissues, with the nervous and immune systems playing pivotal roles. These systems work together, coordinating local and systemic reflexes to restore homeostasis in response to tissue injury and infection. By sharing receptors and ligands, they influence the pathogenesis of various diseases. Recently, a less-explored aspect of neuroimmune communication has emerged: the release of neuropeptides from immune cells and cytokines/chemokines from sensory neurons. This article reviews evidence of this unique neuroimmune interplay and its impact on the development of allergy, inflammation, itch, and pain. We highlight the effects of this neuroimmune signaling on vital processes such as host defense, tissue repair, and inflammation resolution, providing avenues for exploration of the underlying mechanisms and therapeutic potential of this signaling.

Human Mast Cells Upregulate Cathepsin B, a Novel Marker of Itch in Psoriasis

Mast cells (MCs) contribute to skin inflammation. In psoriasis, the activation of cutaneous neuroimmune networks commonly leads to itch. To dissect the unique contribution of MCs to the cutaneous neuroinflammatory response in psoriasis, we examined their density, distribution, relation to nerve fibres and disease severity, and molecular signature by comparing RNA-seq analysis of MCs isolated from the skin of psoriasis patients and healthy volunteers. In involved psoriasis skin, MCs and Calcitonin Gene-Related Peptide (CGRP)-positive nerve fibres were spatially associated, and the increase of both MC and nerve fibre density correlated with disease severity. Gene set enrichment analysis of differentially expressed genes in involved psoriasis skin showed significant representation of neuron-related pathways (i.e., regulation of neuron projection along with dendrite and dendritic spine morphogenesis), indicating MC engagement in neuronal development and supporting the evidence of close MC-nerve fibre interaction. Furthermore, the analysis of 208 identified itch-associated genes revealed that CTSB, TLR4, and TACR1 were upregulated in MCs in involved skin. In both whole-skin published datasets and isolated MCs, CTSB was found to be a reliable indicator of the psoriasis condition. Furthermore, cathepsin B+ cells were increased in psoriasis skin and cathepsin B+ MC density correlated with disease severity. Therefore, our study provides evidence that cathepsin B could serve as a common indicator of the MC-dependent itch signature in psoriasis.

Neuropeptides in Cancer: Friend and Foe?

Neuropeptides are small regulatory molecules found throughout the body, most notably in the nervous, cardiovascular, and gastrointestinal systems. They serve as neurotransmitters or hormones in the regulation of diverse physiological processes. Cancer cells escape normal growth control mechanisms by altering their expression of growth factors, receptors, or intracellular signals, and neuropeptides have recently been recognized as mitogens in cancer growth and development. Many neuropeptides and their receptors exist in multiple subtypes, coupling with different downstream signaling pathways and playing distinct roles in cancer progression. The consideration of neuropeptide/receptor systems as anticancer targets is already leading to new biological and diagnostic knowledge that has the potential to enhance the understanding and treatment of cancer. In this review, recent discoveries regarding neuropeptides in a wide range of cancers, emphasizing their mechanisms of action, signaling cascades, regulation, and therapeutic potential, are discussed. Current technologies used to manipulate and analyze neuropeptides/receptors are described. Applications of neuropeptide analogs and their receptor inhibitors in translational studies and radio-oncology are rapidly increasing, and the possibility for their integration into therapeutic trials and clinical treatment appears promising.

Roles of gastrointestinal polypeptides in intestinal barrier regulation

The intestinal barrier is a dynamic entity that is organized as a multilayer system and includes various intracellular and extracellular elements. The gut barrier functions in a coordinated manner to impede the passage of antigens, toxins, and microbiome components and simultaneously preserves the balanced development of the epithelial barrier and the immune system and the acquisition of tolerance to dietary antigens and intestinal pathogens.Numerous scientific studies have shown a significant association between gut barrier damage and gastrointestinal and extraintestinal diseases such as inflammatory bowel disease, celiac disease and hepatic fibrosis. Various internal and external factors regulate the intestinal barrier. Gastrointestinal peptides originate from enteroendocrine cells in the luminal digestive tract and are critical gut barrier regulators. Recent studies have demonstrated that gastrointestinal peptides have a therapeutic effect on digestive tract diseases, enhancing epithelial barrier activity and restoring the gut barrier. This review demonstrates the roles and mechanisms of gastrointestinal polypeptides, especially somatostatin (SST) and vasoactive intestinal peptide (VIP), in intestinal barrier regulation.

Altered interaction between enteric glial cells and mast cells in the colon of women with irritable bowel syndrome

BACKGROUND

Enteric glial cells (EGC) and mast cells (MC) are intimately associated with gastrointestinal physiological functions. We aimed to investigate EGC-MC interaction in irritable bowel syndrome (IBS), a gut-brain disorder linked to increased intestinal permeability, and MC.

METHODS

Parallel approaches were used to quantify EGC markers in colonic biopsies from healthy controls (HC) and patients with IBS. Data were correlated with MC, vasoactive intestinal polypeptide (VIP) and VIP receptors (VPAC1/VPAC2) expressions, and bacterial translocation through biopsies mounted in Ussing chambers. In addition, we investigated the effects of EGC mediators on colonic permeability and the pharmacological-induced responses of EGC and MC cell lines.

KEY RESULTS

Immunofluorescence of IBS colonic mucosa, as well as Western blotting and ELISA of IBS biopsy lysates, revealed increased glial fibrillary intermediate filament (GFAP) expression, indicating EGC activation. Mucosal GFAP correlated with increased MC and VPAC1⁺ MC numbers and decreased VIP⁺ MC, which seemed to control bacterial translocation in HC. In the contrary, EGC activation in IBS correlated with less MC and VPAC1⁺ MC numbers, and more VIP⁺ MC. In vitro, MC and EGC cell lines showed intracellular calcium responses to each other's mediators. Furthermore, EGC mediators prevented VIP-induced MC degranulation, while MC mediators induced a reactive EGC phenotype. In Ussing chambers, EGC mediators decreased paracellular passage through healthy colonic biopsies.

CONCLUSIONS & INFERENCES

Findings suggest the involvement of EGC and MC in the control of barrier function in the human colon and indicate a potential EGC-MC interaction that seems altered in IBS, with detrimental consequences to colonic permeability. Altogether, results suggest that imbalanced EGC-MC communication contributes to the pathophysiology of IBS.

Sex differences in anatomic plasticity of gut neuronal-mast cell interactions

The gut wall houses mast cells that are anatomically situated near enteric neuronal fibers. Roles of specific neuropeptides in modulating function of immune components like mast cells in response to challenge with bacterial components are relatively unknown. Investigating such interactions requires models that include diverse cellular elements in native anatomic arrangements. Using an organotypic slice model that maintains gut wall cellular diversity ex vivo, the present study compared responses between tissues derived from male and female mice to examine neural-immune signaling in the gut wall after selected treatments. Ileum slices were treated with pharmacological reagents that block neuronal function (e.g., tetrodotoxin) or vasoactive intestinal peptide (VIP) receptors prior to challenge with lipopolysaccharide (LPS) to assess their influence on anatomic plasticity of VIP fibers and activation of mast cells. Sex differences were observed in the number of mucosal mast cells (c-kit/ACK2 immunoreactive) at baseline, regardless of treatment, with female ileum tissue having 46% more ACK2-IR mast cells than males. After challenge with LPS, male mast cell counts rose to female levels. Furthermore, sex differences were observed in the percentage of ACK2-IR cells within 1 µm of a VIP+ neuronal fiber, and mast cell size, a metric previously tied to activation, with females having larger cells at baseline. Male mast cell sizes reached female levels after LPS challenge. This study suggests sex differences in neural-immune plasticity and in mast cell activation both basally and in response to challenge with LPS. These sex differences could potentially impact functional neuroimmune response to pathogens.

Vasoactive Intestinal Peptide Promotes Fracture Healing in Sympathectomized Mice

Vasoactive intestinal peptide (VIP) as a neuromodulator and neurotransmitter played a significant role in modulating bone homeostasis. Our previous study reported an essential role of VIP in in vitro BMSCs osteogenesis and in vivo bone defect repair. VIP was also revealed to have a promoting effect on embryonic skeletal element development. However, the role of VIP in fracture healing is not known yet. We hypothesized that the disorder of sympathetic nervous system impairs bone structure and fracture healing, whereas VIP may rescue the sympathetic inhibition effects and promote fracture healing. We employed a 6-hydroxydopamine (6-OHDA) induced sympathectomy mice model (sympathectomized mice), in which successful sympathetic inhibition was confirmed by a decreased level of norephedrine (NE) in the spleen. In the sympathectomized mice, the femoral micro-architecture, bone density and mechanical properties were all impaired compared to the vehicle control mice. The femoral fracture was created in the vehicle or sympathectomized mice. Vehicle mice were locally injected with PBS as a negative control, and the sympathectomized mice were treated with injection of PBS or VIP. VIP expression at the fracture site was significantly decreased in sympathectomized mice. The fracture healing was repressed upon 6-OHDA treatment and rescued by VIP treatment. Micro-CT examination showed that the femoral bone micro-architecture at the fracture sites and mechanical properties were all impaired. Simultaneously, the expression level of osteogenic markers OCN and OPN were reduced in sympathectomized mice compared with vehicle group. While the VIP treatment rescued the repression effects of 6-OHDA on bone remodeling and significantly promoted bone quality and mechanical properties as well as increased osteogenesis marker expression in the sympathectomized mice. VIP administration promoted bone fracture healing by inhibiting bone resorption, making it a putative new alternative treatment strategy for fracture healing.

A Clinical Approach for the Use of VIP Axis in Inflammatory and Autoimmune Diseases

The neuroendocrine and immune systems are coordinated to maintain the homeostasis of the organism, generating bidirectional communication through shared mediators and receptors. Vasoactive intestinal peptide (VIP) is the paradigm of an endogenous neuropeptide produced by neurons and endocrine and immune cells, involved in the control of both innate and adaptive immune responses. Exogenous administration of VIP exerts therapeutic effects in models of autoimmune/inflammatory diseases mediated by G-protein-coupled receptors (VPAC1 and VPAC2). Currently, there are no curative therapies for inflammatory and autoimmune diseases, and patients present complex diagnostic, therapeutic, and prognostic problems in daily clinical practice due to their heterogeneous nature. This review focuses on the biology of VIP and VIP receptor signaling, as well as its protective effects as an immunomodulatory factor. Recent progress in improving the stability, selectivity, and effectiveness of VIP/receptors analogues and new routes of administration are highlighted, as well as important advances in their use as biomarkers, contributing to their potential application in precision medicine. On the 50th anniversary of VIP's discovery, this review presents a spectrum of potential clinical benefits applied to inflammatory and autoimmune diseases.

Targeting mast cell as a neuroprotective strategy

Background: Mast cells (MCs) are perivascularly located immune cells of haematopoietic origin. Emerging evidences suggest that the activation of MCs play important roles in the pathogenesis of blood brain barrier disruption, neuroinflammation, and neurodegeneration. Objectives: In this review, we aimed to discuss the detrimental effects of MCs in response to various types of brain injury, as well as the therapeutic potential and neuroprotective effects of targeting the activation and degranulation of MCs, particularly in the management of the acute phase. Methods: An extensive online literature search was conducted through Pubmed/Central on March 2018. Then, we comprehensively summarized the effects of the activation of brain MCs in acute brain injury along with current pharmacological strategies targeting at the activation of MCs. Results: The review of the current literature indicated that the activation and degranulation of brain MCs significantly contribute to the acute pathological process following different types of brain injury including focal and global cerebral ischaemia, intracerebral haemorrhage, subarachnoid haemorrhage, and traumatic brain injury. Conclusions: Brain MCs significantly contribute to the acute pathological processes following brain injury. In that regard, targeting brain MCs may provide a novel strategy for neuroprotection.

Gene expression analysis of neuropeptides in oral mucosa during periodontal disease in non-human primates

BACKGROUND

Neuropeptides (NPs) are innate pivotal regulators of the immunoinflammatory response. Nevertheless, their role in the pathogenesis of periodontal disease remains unknown. Changes in gene expression of 10 NPs and 16 NP receptors (NPRs) coincident with the initiation, progression, and resolution of periodontitis were determined.

METHODS

The ligature-induced periodontitis model was used in rhesus monkeys (n = 18). Gingival tissue samples were taken at baseline (preligatures), at 2 weeks and at 1 month (initiation), and at 3 months (progression) postligation. Ligatures were removed and samples taken 2 months later (resolution). Total RNA was isolated from tissues and NP/NPR gene expression microarray analysis was performed. Gene expression changes were validated by quantitative polymerase chain reaction and immunohistochemistry.

RESULTS

Unexpectedly, the expression of pro-inflammatory NPs/NPRs did not change during periodontitis or with resolution. However, increased expression of the anti-inflammatory NPs adrenomedullin (ADM) and galanin (GAL), and the NPRs calcitonin receptor-like (CALCRL) and receptor activity-modifying protein-2 and -3 (RAMP2 and RAMP3) were observed during initiation and progression of disease. The expression of the same NPs/NPRs exhibited a significant positive correlation with both molecular (interleukin-1ß, matrix mettaloproteinase-9, and receptor activator of nuclear factor-kappa B ligand) and clinical measures of gingival inflammation and tissue destruction.

CONCLUSION

Initiation and progression of periodontitis involve significant overexpression of ADM, GAL, CALCRL, RAMP2, and RAMP3. These anti-inflammatory NPs/NPRs could play a role in the unresolved infection and inflammation that normally drives tissue destruction in periodontitis. Both ADM and GAL potentially are new candidates to consider as biomolecules associated with periodontal disease activity.

Mesenteric Traction Syndrome or Gut in Distress

The mesenteric traction syndrome (MTS) remains, seventeen years after its first designation as a distinct pathologic entity, an aspect of surgical practice that has received limited attention. Apart from its symptomatology, there is mostly speculation about its exact causes and pathophysiologic mechanisms.

Even though full-blown MTS is rather rare, the advent of laparoscopic surgery has indicated that there are different stages of stress associated with open abdominal surgery. Some evidence points to the involvement of mast cell derived vasoactive mediators and suggests possible pharmacologic management.

Roads Less Traveled: Sexual Dimorphism and Mast Cell Contributions to Migraine Pathology

Migraine is a common, little understood, and debilitating disease. It is much more prominent in women than in men (~2/3 are women) but the reasons for female preponderance are not clear. Migraineurs frequently experience severe comorbidities, such as allergies, depression, irritable bowel syndrome, and others; many of the comorbidities are more common in females. Current treatments for migraine are not gender specific, and rarely are migraine and its comorbidities considered and treated by the same specialist. Thus, migraine treatments represent a huge unmet medical need, which will only be addressed with greater understanding of its underlying pathophysiology. We discuss the current knowledge about sex differences in migraine and its comorbidities, and focus on the potential role of mast cells (MCs) in both. Sex-based differences in pain recognition and drug responses, fluid balance, and the blood–brain barrier are recognized but their impact on migraine is not well studied. Furthermore, MCs are well recognized for their prominent role in allergies but much less is known about their contributions to pain pathways in general and migraine specifically. MC-neuron bidirectional communication uniquely positions these cells as potential initiators and/or perpetuators of pain. MCs can secrete nociceptor sensitizing and activating agents, such as serotonin, prostaglandins, histamine, and proteolytic enzymes that can also activate the pain-mediating transient receptor potential vanilloid channels. MCs express receptors for both estrogen and progesterone that induce degranulation upon binding. Furthermore, environmental estrogens, such as Bisphenol A, activate MCs in preclinical models but their impact on pain pathways or migraine is understudied. We hope that this discussion will encourage scientists and physicians alike to bridge the knowledge gaps linking sex, MCs, and migraine to develop better, more comprehensive treatments for migraine patients.

Inflammatory and immune pathways in the pathogenesis of periodontal disease

The pathogenesis of periodontitis involves a complex immune/inflammatory cascade that is initiated by the bacteria of the oral biofilm that forms naturally on the teeth. The susceptibility to periodontitis appears to be determined by the host response; specifically, the magnitude of the inflammatory response and the differential activation of immune pathways. The purpose of this review was to delineate our current knowledge of the host response in periodontitis. The role of innate immunity, the failure of acute inflammation to resolve (thus becoming chronic), the cytokine pathways that regulate the activation of acquired immunity and the cells and products of the immune system are considered. New information relating to regulation of both inflammation and the immune response will be reviewed in the context of susceptibility to, and perhaps control of, periodontitis.

Mast cell chymase reduces the toxicity of Gila monster venom, scorpion venom, and vasoactive intestinal polypeptide in mice

Mast cell degranulation is important in the pathogenesis of anaphylaxis and allergic disorders. Many animal venoms contain components that can induce mast cell degranulation, and this has been thought to contribute to the pathology and mortality caused by envenomation. However, we recently reported evidence that mast cells can enhance the resistance of mice to the venoms of certain snakes and that mouse mast cell-derived carboxypeptidase A3 (CPA3) can contribute to this effect. Here, we investigated whether mast cells can enhance resistance to the venom of the Gila monster, a toxic component of that venom (helodermin), and the structurally similar mammalian peptide, vasoactive intestinal polypeptide (VIP). Using 2 types of mast cell-deficient mice, as well as mice selectively lacking CPA3 activity or the chymase mouse mast cell protease-4 (MCPT4), we found that mast cells and MCPT4, which can degrade helodermin, can enhance host resistance to the toxicity of Gila monster venom. Mast cells and MCPT4 also can limit the toxicity associated with high concentrations of VIP and can reduce the morbidity and mortality induced by venoms from 2 species of scorpions. Our findings support the notion that mast cells can enhance innate defense by degradation of diverse animal toxins and that release of MCPT4, in addition to CPA3, can contribute to this mast cell function.

Vasoactive intestinal peptide signaling axis in human leukemia

The vasoactive intestinal peptide (VIP) signaling axis constitutes a master “communication coordinator” between cells of the nervous and immune systems. To date, VIP and its two main receptors expressed in T lymphocytes, vasoactive intestinal peptide receptor (VPAC)1 and VPAC2, mediate critical cellular functions regulating adaptive immunity, including arresting CD4 T cells in G₁ of the cell cycle, protection from apoptosis and a potent chemotactic recruiter of T cells to the mucosa associated lymphoid compartment of the gastrointestinal tissues. Since the discovery of VIP in 1970, followed by the cloning of VPAC1 and VPAC2 in the early 1990s, this signaling axis has been associated with common human cancers, including leukemia. This review highlights the present day knowledge of the VIP ligand and its receptor expression profile in T cell leukemia and cell lines. Also, there will be a discussion describing how the anti-leukemic DNA binding transcription factor, Ikaros, regulates VIP receptor expression in primary human CD4 T lymphocytes and T cell lymphoblastic cell lines (e.g. Hut-78). Lastly, future goals will be mentioned that are expected to uncover the role of how the VIP signaling axis contributes to human leukemogenesis, and to establish whether the VIP receptor signature expressed by leukemic blasts can provide therapeutic and/or diagnostic information.

Prospect of vasoactive intestinal peptide therapy for COPD/PAH and asthma: a review

There is mounting evidence that pulmonary arterial hypertension (PAH), asthma and chronic obstructive pulmonary disease (COPD) share important pathological features, including inflammation, smooth muscle contraction and remodeling. No existing drug provides the combined potential advantages of reducing vascular- and bronchial-constriction, and anti-inflammation. Vasoactive intestinal peptide (VIP) is widely expressed throughout the cardiopulmonary system and exerts a variety of biological actions, including potent vascular and airway dilatory actions, potent anti-inflammatory actions, improving blood circulation to the heart and lung, and modulation of airway secretions. VIP has emerged as a promising drug candidate for the treatment of cardiopulmonary disorders such as PAH, asthma, and COPD. Clinical application of VIP has been limited in the past for a number of reasons, including its short plasma half-life and difficulty in administration routes. The development of long-acting VIP analogues, in combination with appropriate drug delivery systems, may provide clinically useful agents for the treatment of PAH, asthma, and COPD. This article reviews the physiological significance of VIP in cardiopulmonary system and the therapeutic potential of VIP-based agents in the treatment of pulmonary diseases.

Neuropeptide physiology in insects

In a search for more environmentally benign alternatives to chemical pesticides, insect neuropeptides have been suggested as ideal candidates. Neuropeptides are neuromodulators and/or neurohormones that regulate most major physiological and behavioral processes in insects. The major neuropeptide structures have been identified through peptide purification in insects (peptidomics) and insect genome projects. Neuropeptide receptors have been identified and characterized in Drosophila and similar receptors are being targeted in other insects considered to be economically detrimental pests in agriculture and forestry. Defining neuropeptide action in different insect systems has been more challenging and as a consequence, identifying unique targets for potential pest control is also a challenge. In this chapter, neuropeptide biosynthesis as well as select physiological processes are examined with a view to pest control targets. The application of molecular techniques to transform insects with neuropeptide or neuropeptide receptor genes, or knockout genes to identify potential pest control targets, is a relatively new area that offers promise to insect control. Insect immune systems may also be manipulated through neuropeptides which may aid in compromising the insects ability to defend against foreign invasion.

Spatio-temporal localization of vasoactive intestinal peptide and neutral endopeptidase in allergic murine lungs

Vasoactive intestinal peptide (VIP) is a neuropeptide with cytokine properties that is abundant in the lung. VIP null mice exhibit spontaneous airway inflammation and hyperresponsiveness emphasizing VIP's "anti-asthma" potential. Although VIP's impending protective role in the lung has been demonstrated, its localization in the naïve and allergic murine lungs has not. To this aim, we analyzed the availability of VIP and its protease, neutral peptidase (NEP), in naïve and Aspergillus-sensitized and challenged murine lungs after 3, 7, and 14days. Both VIP and NEP were predominantly localized to the columnar epithelia of the airways in naïve lungs. A marked decrease in VIP occurred in these cells 3days after allergen challenge. NEP localization in the columnar epithelia decreased after allergen challenge. At day 14, VIP localization in the columnar epithelia and arteriolar smooth muscle increased while NEP localization at these sites remained low. This study provides new insights into the local regulation of VIP in the columnar epithelia of the allergic lung. Its altered availability in the context of allergy provides fresh evidence for the modulation of pulmonary inflammation by VIP.

Immunomodulation of innate immune responses by vasoactive intestinal peptide (VIP): its therapeutic potential in inflammatory disease

Since the late 1970s a number of laboratories have studied the role of vasoactive intestinal peptide (VIP) in inflammation and immunity. These studies have highlighted the dramatic effect of VIP on immune cell activation and function, and studies using animal models of disease have indicated that VIP has significant therapeutic and prophylactic potential. This review will focus on the effects of VIP on innate immune cell function and discuss the therapeutic potential for VIP in inflammatory diseases of humans.

The lung in relation to vasoactive polypeptides

Among the metabolic functions of the lungs are the formation, release, activation and inactivation of biologically active peptides. The following peptides may be present or formed in normal lung: vasoactive intestinal peptide or a peptide closely related to it, a spasmogenic peptide not yet fully identified, bradykinin, substance P, a bombesin-like peptide (especially in fetal and neonatal lung), and eosinophil-chemotactic peptides. These peptides are found in special neuroendocrine cells, in neurons, or in mast cells. Normal lung also inactivates bradykinin and activates angiotensin; both processes are catalysed by the same enzyme (kininase II or angiotensin-converting enzyme), located in pulmonary vascular endothelium. Pulmonary tumours and certain non-tumorous lesions can produce and release a variety of peptide hormones that are not normally generated by the lung in substantial amounts. This 'ectopic' secretion of hormones may be detectable only by sensitive assays or may result in specific clinical syndromes.

Vasoactive intestinal polypeptide enhances oral tolerance by regulating both cellular and humoral immune responses

Vasoactive intestinal polypeptide (VIP) is an important signal molecule of the neuroendocrine-immune network. In the immune system, VIP has been found to act as an endogenous anti-inflammatory mediator. In the current study, it was found that VIP administration regulated oral tolerance by inhibiting both cellular and humoral responses. Compared with vehicle-treated mice, mice treated with VIP during the development of ovalbumin (OVA)-induced oral tolerance exhibited the least delayed-type hypersensitivity (DTH), showed profoundly reduced proliferative capacity and produced less interferon (IFN)-gamma, interleukin (IL)-6, IL-5, IL-10 and interferon-inducible protein (IP-10). IgA-secreting cells in the gut as well as OVA-specific IgG and other isotypes levels in plasma were inhibited significantly after VIP-treatment. The VPAC2 receptor may be involved in VIP-mediated oral tolerance enhancement. Taken together, these results suggest that VIP enhanced oral tolerance via regulating both cellular and humoral responses.

Vasoactive intestinal peptide (VIP) prevents killing of virulent and phoP mutant Salmonella typhimurium by inhibiting IFN-γ stimulated NADPH oxidative pathways in murine macrophages

Vasoactive intestinal peptide is an immunomodulator with great potential in the treatment of inflammatory pathology. In this study, we have examined the effect of VIP on the growth dynamics of virulent Salmonella enterica. Serovar typhimurium (S. typhimurium) 14028 and 4/74 and an avirulent mutant (14028 phoP) in a murine, macrophage cell line (J774.2). In contrast to standard growth dynamics, in which phoP mutants do not survive in macrophages, we show that VIP (10(-10) M) significantly enhances phoP growth over a 24 h post-infection period even when the cells are co-cultured with IFN-gamma. We examined the effect of VIP on the generation of NADPH-induced reactive oxygen species (ROS) in Salmonella-infected/IFN-gamma cultured J774 cells. VIP inhibited gp91 mRNA levels, gp91 protein and subsequent ROS. The importance of ROS in killing of Salmonella by J774 cells was highlighted by experiments in which ROS production by J774 cells was inhibited using a conventional inhibitor, N-acetyl-L-cysteine captopril (ACC) and in which Salmonella growth significantly increased. Our findings suggest that although VIP inhibits inflammatory pathways in myeloid cells it also promotes the growth of avirulent (phoP) mutants.

Vasoactive intestinal polypeptide (VIP) and VPAC1 receptor in adult human dental pulp in relation to caries

OBJECTIVE

To quantitatively measure VIP levels and to qualitatively study the distribution of VIP fibres and demonstrate the presence of the VPAC1 receptor in human dental pulp from carious and non-carious adult human teeth.

DESIGN

Dental pulp samples were collected from non-carious, moderately carious and grossly carious adult human teeth. VIP levels were determined using radioimmunoassay. The distribution of VIP fibres was studied using immunohistochemistry. The VPAC1 receptor protein expression was determined by Western blotting.

RESULTS

VIP levels were found to be significantly elevated in the dental pulp of moderately carious compared with non-carious (p=0.0032) or grossly carious teeth (p=0.0029). The distribution of VIP fibres was similar in non-carious and carious teeth, except that nerve bundles appeared thicker in the pulp samples from carious compared with non-carious teeth. Western blotting indicated that the VPAC1 receptor proteins were detected in similar levels in pooled dental pulp samples from both carious and non-carious teeth.

CONCLUSION

It is concluded that quantitative changes in the levels of VIP in human dental pulp during the caries process and the expression of VPAC1 receptor proteins in membrane extracts from carious and non-carious teeth suggests a role for VIP in modulating pulpal health and disease.

Systemic Mastocytosis: Clinical Manifestations and Differential Diagnosis

Mast cells produce symptoms by local and remote effects of mediator release and by their presence in increased numbers in normal tissue and bone marrow, where they damage and impair normal organ function. Moreover, mast cells are long-lived and heterogeneous in their response to secretagogues and to inhibitors of mediator release. Clinicians sorting out the diagnosis of SM on the basis of presenting signs and symptoms continue to have their diagnostic skills challenged because of the rarity of this disorder, the fact that many symptoms of SM are present in more common disorders, and the multiple guises that SM may assume at the time of presentation.

Novel concepts of neuropeptide-based drug therapy: vasoactive intestinal polypeptide and its receptors

Chronic inflammatory airway diseases such as bronchial asthma or chronic obstructive pulmonary disease (COPD) are major contributors to the global burden of disease. Although inflammatory cells play the central role in the pathogenesis of the diseases, recent observations indicate that also resident respiratory cells represent important targets for pulmonary drug development. Especially targeting airway neuromediators offers a possible mechanism by which respiratory diseases may be treated in the future. Among numerous peptide mediators such as tachykinins, calcitonin gene-related peptide, neurotrophins or opioids, vasoactive intestinal polypeptide (VIP) is one of the most abundant molecules found in the respiratory tract. In human airways, it influences many respiratory functions via the receptors VPAC1, VPAC2 and PAC1. VIP-expressing nerve fibers are present in the tracheobronchial smooth muscle layer, submucosal glands and in the walls of pulmonary and bronchial arteries and veins. Next to its strong bronchodilator effects, VIP potently relaxes pulmonary vessels, and plays a pivotal role in the mediation of immune mechanisms. A therapy utilizing the respiratory effects of VIP would offer potential benefits in the treatment of obstructive and inflammatory diseases and long acting VIP-based synthetic non-peptide compounds may represent a novel target for drug development.

Morphological and immunocytochemical investigations on mast cells in porcine ureter

Morphological, morphometric, histochemical and immunocytochemical investigations on mast cells, located in the wall of ureter of 8 months aged pigs were performed. Mast cells were found in all three layers of ureteral wall, but their distribution was irregular and the number unequal. It was established that alcian blue (AB)-positive mast cells were significantly more than toluidine blue (TB)-positive mast cells. A statistically significant smaller number of both AB and TB-stained mast cells were observed in the tunica mucosa. The largest number of mast cells was found in the tunica muscularis. In the adventitia, mast cells were higher in number in the main connective tissue than in the connective tissue near the blood vessels. Mast cells stained with TB showed variably expressed gamma-metachromasia, which was best visible in those situated in the lamina propria of the mucosa. The prevailing parts of mast cells, however, were AB-positive after AB-safranin staining. This was mostly found in mast cells of the tunica muscularis and in mast cells of perivascular location in the tunica adventitia. Immunocytochemically, mast cells were found to be positive for histamine and vasoactive intestinal polypeptide in the muscle coat, and to histamine in the adventitia, as well. On the basis of obtained results it was presumed that the mast cells in porcine ureter most probably took part not only in keeping of local homeostasis, but played also an important role of mobility of smooth muscle cells in the middle layer of ureter on one hand, and, on the other, in the adventitial blood vessels.

The role of mast cells in migraine pathophysiology

Mast cells are critical players in allergic reactions, but they have also been shown to be important in immunity and recently also in inflammatory diseases, especially asthma. Migraines are episodic, typically unilateral, throbbing headaches that occur more frequently in patients with allergy and asthma implying involvement of meningeal and/or brain mast cells. These mast cells are located perivascularly, in close association with neurons especially in the dura, where they can be activated following trigeminal nerve, as well as cervical or sphenopalatine ganglion stimulation. Neuropeptides such as calcitonin gene-related peptide (CGRP), hemokinin A, neurotensin (NT), pituitary adenylate cyclase activating peptide (PACAP), and substance P (SP) activate mast cells leading to secretion of vasoactive, pro-inflammatory, and neurosensitizing mediators, thereby contributing to migraine pathogenesis. Brain mast cells can also secrete pro-inflammatory and vasodilatory molecules such as interleukin-6 (IL-6) and vascular endothelial growth factor (VEGF), selectively in response to corticotropin-releasing hormone (CRH), a mediator of stress which is known to precipitate or exacerbate migraines. A better understanding of brain mast cell activation in migraines would be useful and could lead to several points of prophylactic intervention.

Ganoderma lucidum polysaccharide fractions accelerate healing of acetic acid-induced ulcers in rats

The polysaccharide (PS) fractions from several medicinal herbs have been reported to have anti-ulcer effects against experimental ulcers in the rat. The water-soluble PS fractions from Ganoderma lucidum (Reishi mushroom) have been shown to inhibit indomethacin-induced gastric mucosal lesions in rats. This study aimed to investigate the effect of the PS fraction from G. lucidum on the healing of gastric ulcers induced by acetic acid in the rat and to elucidate the underlying mechanisms involved. The abdomen of rats was incised, and the stomach was treated with 10 M acetic acid (100 microL) for 1 minute, and then treated with G. lucidum PS (0.1, 0.5, or 1.0 g/kg) intragastrically, once a day for 14 consecutive days. The results indicated that the oral administration of G. lucidum PS at 0.5 and 1.0 g/kg for 2 weeks caused a significant acceleration of ulcer healing by 40.1% and 55.9%, respectively. In the mechanistic studies, additional rats were treated with 10 M acetic acid to induce acute ulcers, and then treated with G. lucidum PS (1.0 g/kg) for 3, 7, 10, or 14 days. Exposure of the rat stomach to acetic acid led to decreased mucus and increased prostaglandin levels. Treatment with G. lucidum PS at 1.0 g/kg significantly (P < .05) suppressed or restored the decreased gastric mucus levels and increased gastric prostaglandin concentrations compared with the control group. These results indicates that G. lucidum PS is an active component with healing efficacy on acetic acid-induced ulcers in the rat, which may represent a useful herbal preparation for the prevention and treatment of peptic ulcers.

Brain mast cells and therapeutic potential of vasoactive intestinal peptide in a Parkinson's disease model in rats: brain microdialysis, behavior, and microscopy

In the present study, the effect of systemically administered vasoactive intestinal peptide (VIP) (25 ng/kg i.p.) was investigated on drug-induced rotational behavior, extra-cellular dopamine levels and histology of corpus striatum in a 6-hydroxydopamine (6-OHDA)-induced rat model of Parkinson's disease. After 15 days of 6-OHDA lesion, apomorphine-induced (0.05 mg/kg s.c.) rotational behavior of the animals significantly increased and extra-cellular dopamine levels of corpus striatum were significantly reduced. VIP reversed the rotational deficits but did not alter the decrease in striatal dopamine levels. On the other hand, histological data indicate that VIP significantly reduced neuronal death and demyelination. Electron microscopic appearance of mast cells showed ultra-structural variety between VIP-treated and 6-OHDA lesioned groups. VIP activates mast cells without any evidence of typical exocytosis, and possibly mast cells could participate in neuroprotection. Our results suggest that systemically administered VIP can attenuate the motor response changes, neuronal cell death, and myelin sheet loss characteristically associated with 12 microg 6-OHDA administration into the rat striatum. Brain mast cells seem to participate in neuronal protection. Possibly, protective cues could be produced by brain mast cells.

Mast cells in human bile duct obstruction

Surgical biopsy specimens obtained from 50 patients with secondary cholangitis caused by obstruction of the common bile duct were studied immunohistochemically. Data on the number and ultrastructural appearances of mast cells positive for tryptase, chymase, vasointestinal polypeptide (VIP), and substance P (SP) were obtained. The bile ducts from patients presenting combined chronic exacerbated cholangitis and chronic sclerotic cholangitis showed significantly higher numbers of mast cell types compared to the controls (P < 0.0001). Cases with sclerotic cholangitis alone had significantly lower number of cells than patients with chronic exacerbated cholangitis alone (P < or = 0.0001). Morphometric measurements of electron micrographs showed that mast cell granules containing VIP, SP and chymase were commensurable in size. Electron-lucent granules without reaction product (altered granules) and granules with focal distribution of the reaction product were observed in all types of mast cells. Furthermore, some nerve fibers positive for SP and VIP and serotonin-positive endocrine cells were observed in close proximity to the mast cells. In conclusion, the results of our study demonstrate the existence of different populations of mast cells, nerve structures and endocrine cells in the lower part of the human large bile duct, and suggest their participation in the development of pathological processes.

The significance of vasoactive intestinal peptide in immunomodulation

First identified by Said and Mutt some 30 years ago, the vasoactive intestinal peptide (VIP) was originally isolated as a vasodilator peptide. Subsequently, its biochemistry was elucidated, and within the 1st decade, their signature features as a neuropeptide became consolidated. It did not take long for these insights to permeate the field of immunology, out of which surprising new attributes for VIP were found in the last years. VIP is rapidly transforming into something more than a mere hormone. In evolving scientifically from a hormone to a novel agent for modifying immune function and possibly a cytokine-like molecule, VIP research has engaged many physiologists, molecular biologists, biochemists, endocrinologists, and pharmacologists and it is a paradigm to explore mutual interactions between neural and neuroendocrine links in health and disease. The aim of this review is firstly to update our knowledge of the cellular and molecular events relevant to VIP function on the immune system and secondly to gather together recent data that support its role as a type 2 cytokine. Recognition of the central functions VIP plays in cellular processes is focusing our attention on this "very important peptide" as exciting new candidates for therapeutic intervention and drug development.

Neuromodulation of experimental Shigella infection reduces damage to the gut mucosa

Bacillary dysentery arises when Shigella invades the colonic and rectal mucosae of the human gut and elicits a strong inflammatory response, which may lead to life-threatening complications. Hence, downregulation of the host inflammatory response is an appealing therapeutical alternative. The gastrointestinal tract is densely innervated, and nerve endings are often found in the vicinity of leukocytes. We have assessed the impact of experimental Shigella infection on levels of neuropeptides in the intestinal mucosa of rabbits. Ligated small intestinal loops were created in rabbits, and either live, pathogenic Shigella flexneri, a nonpathogenic mutant of Shigella, or NaCl was injected into the loops. Infection was allowed to proceed for 8 or 16 h, after which the rabbits were sacrificed and intestinal biopsies collected. Tissue destruction, fluid secretion and degree of bacterial invasion were monitored. Intestinal biopsies were homogenized, and levels of the neuropeptides calcitonin gene-related peptide, substance P, peptide YY (PYY), vasoactive intestinal peptide, somatostatin, galanin, motilin and neurotensin were measured by radioimmunoassay. Loops exposed to invasive Shigella had 5.7 times lower levels of PYY (P = 0.0095) than loops exposed to NaCl, after 16 h of infection. The levels of the other neuropeptides tested were unchanged. Inhibition of nicotinic cholinergic neurotransmission partly protected the intestinal mucosa from destruction elicited by invasive Shigella. These findings indicate that a tissue-invasive bacterium such as Shigella, which is strictly localized to the intestinal mucosa, activates intramural nerve reflexes that presumably involve a nicotinic synapse as well as the neuropeptide PYY.

Gastric Antiulcer Activity of Syngonanthus arthrotrichus SILVEIRA

Syngonanthus arthrotrichus SILVEIRA, popularly known as "sempre-vivas mini-saia," is found in mountains of the Espinhaço range in the Brazilian states of Bahia and Minas Gerais. Extracts of this species contain several constituents, including flavonoids which may have antiulcerogenic activity. An ethanolic extract (EEOH), and flavonoid-rich (FRF) and flavonoid-deficient (FDF) fractions obtained from the scapes of S. arthrotrichus were investigated for their ability to prevent ulceration of the gastric mucosa in mice and rats. In the ethanol/HCl-induced ulcer model, lansoprazole (30 mg/kg), EEOH (50, 100, 250 mg/kg) given orally protected the gastric mucosal against injury in mice by 79%, 78%, 73%, and 64% respectively. In the ethanol-induced gastric ulcer model in rats, the lansoprazole (30 mg/kg), FRF and FDF (100 mg/kg) significantly protected the gastric mucosal of rats by 65%, 38% and 25% respectively when compared with the negative control group. In indomethacin/bethanechol-induced gastric ulcers, cimetidine (100 mg/kg) and the EEOH (100, 250 mg/kg) inhibited gastric ulcer formation by 73%, 55% and 32% respectively. In this exactly model other treatments as cimetidine, FRF and FDF (100 mg/kg) each caused 54%, 36% and 45% inhibition, respectively. In the stress-induced gastric ulcer model, cimetidine (100 mg/kg) and the EEOH (50, 100, 250 mg/kg), inhibited gastric ulcer formation by 63%, 73%, 68% and 69% respectively. In the same model, cimetidine, FRF and FDF (100 mg/kg) significantly protected the gastric mucosal of the mice by 60%, 51% and 47% when compared to the control group. In pylorus-ligated mice, cimetidine (positive control) and FRF significantly decreased gastric acid secretion, increased gastric pH and reduced the acid output when compared to the negative control. FDF had no significant effect on these parameters. The protection provided by FRF probably involved an antisecretory mechanism mediated by flavonoids which were absent in FDF. The amount of adherent mucous in the stomach contents was also evaluated with the treatments carbenoxolone (200 mg/kg), FRF and FDF (100 mg/kg) treatment. Each treatments significantly increased the amount of adherent mucous in the gastric juice (8.67+/-1.73, 3.35+/-1.59, 2.1+/-0.41 mg/g of wet tissue, respectively) compared to the control group, indicating a cytoprotective action on the gastric mucosa. Treatment with FRF plus indomethacin and FDF plus indomethacin reduced the prostaglandin biosyntesis (13.6+/-6.5, 27+/-5.5 pg/well) by the mucosa, indicating that the cytoprotective action on the gastric mucosa was not related to the level of prostaglandins. Only FDF (38+/-17 pg/well) maintained the level of prostaglandins and guaranteed the integrity of the mucosa. The results indicate that the EEOH, FRF and FDF have antisecretory and cytoprotective actions, that may be related to the presence of luteoline in the extract and active fractions.

NEUROPEPTIDES AND NEUROGENIC MECHANISMS IN ORAL AND PERIODONTAL INFLAMMATION

It is generally accepted that the nervous system contributes to the pathophysiology of peripheral inflammation, and a neurogenic component has been implicated in many inflammatory diseases, including periodontitis. Neurogenic inflammation should be regarded as a protective mechanism, which forms the first line of defense and protects tissue integrity. However, severe or prolonged noxious stimulation may result in the inflammatory response mediating injury rather than facilitating repair. This review focuses on the accumulating evidence suggesting that neuropeptides have a pivotal role in the complex cascade of chemical activity associated with periodontal inflammation. An overview of neuropeptide synthesis and release introduces the role of neuropeptides and their interactions with other inflammatory factors, which ultimately lead to neurogenic inflammation. The biological effects of the neuropeptides substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP), and neuropeptide Y (NPY) are summarized, and evidence for their involvement in the localized inflammatory lesions which characterize periodontitis is presented. In this context, the role of CGRP in bone metabolism is described in more detail. Recent research highlighting the role of the nervous system in suppressing pain and inflammation is also discussed.

Structural examination of tryptase- and chymase-positive mast cells in livers, containing metastases from gastrointestinal cancers

Human mast cells are categorized into mast cells positive only for tryptase (MC(T)) and mast cells positive for both tryptase and chymase (MC(TC)). The structural appearance of tryptase-, and chymase-positive mast cells in metastatic liver disease and the variations in MC(T) and MC(TC) numbers in accordance with the origin of the primary tumors have been described in the present study. Liver mast cells are analyzed immunocytochemically using tryptase and chymase and by quantitative morphometry in 30 patients with colorectal (n = 15), gastric (n = 8), and pancreatic (n = 7) cancers and in 5 control livers. The numbers of MC(T) and MC(TC) are increased in the extratumoral liver tissue (mainly portal tracts) as compared to controls. The numbers of MC(T) and MC(TC) in and around metastases with moderate or high grade of differentiation are statistically significantly higher, as compared to those with low grades of differentiation. The numbers of MC(TC) are greater than that of MC(T) in the extratumoral liver tissue and in metastases themselves. Ultrastructurally, mast cells immunostained with tryptase and chymase have three types of granules: electron dense granules with darkly precipitated reaction product, electron lucent granules without reaction product and electron lucent granules with sparse reaction product (altered granules). Both types of mast cells have small and large in size granules, resembling the MC(TC) phenotype described earlier. Tryptase-positive mast cells have granules with discrete scrolls and particulate and beaded pattern. Chymase-positive mast cells have granules with finely granular or particulate material. Substance P (SP)- and vasointestinal polypeptide (VIP)-positive mast cells are not observed in livers with metastases. The present study suggests that liver mast cells are mainly from the MC(TC) type, and are accumulated in peritumoral and metastatic areas. They may play a role in the formation of tumor stroma, or in tumor immunology in liver metastases from various primary gastrointestinal cancers.

Induced maturation of frog mast cells by nerve growth factor during ontogenesis

The effect of nerve growth factor (NGF) on ontogenesis of frog mast cells was investigated in vivo by histochemical, morphometric, and ultrastructural analysis. Three groups of tadpoles at various stages of development were used. In the first group, the larvae received i.p. injections of 1 ng NGF/g; the second group received 10 ng NGF/g, while the control group received only the vehicle. The first recognizable mast cells arose symmetrically in the tongue at stage 26 of Witschi's standard table. At stages 26 and 29, the mast cell number in the NGF-injected tadpoles was significantly higher than the control group. From stage 29 onward, the mast cell number rapidly increased in all groups. No significant differences in mast cell number were observed between the control group and the NGF-injected groups at stages 31 and 33. Electron microscopy revealed that at metamorphic climax (stage 33), the mast cells in the NGF-treated groups were more mature than those in the control group. Therefore, nerve growth factor at early stages of tadpole development is likely to induce differentiation of mast cell precursors, while at later stages it is likely to induce maturation of immature mast cells. The close anatomical association between mast cells and perineurium, observed during nerve development, is intriguing. Already in the early stages of nerve development, the mast cells form a network around Schwann cell-axon complexes, together with the perineurial cells. At climax, the mast cells are located between the perineurial layers, suggesting that they may play a role in the tissue-nerve barrier of the perineurium. Nerve growth factor also seems to induce perineurial cell maturation.

Stress-induced dura vascular permeability does not develop in mast cell-deficient and neurokinin-1 receptor knockout mice

Migraine headaches are often precipitated by stress and seem to involve neurogenic inflammation (NI) of the dura mater associated with the sensation of throbbing pain. Trigeminal nerve stimulation had been reported to activate rat dura mast cells and increase vascular permeability, effects inhibited by neonatal pretreatment with capsaicin implicating sensory neuropeptides, such as substance P (SP). The aim of the present study was to investigate NI, assessed by extravasation of 99-Technetium-gluceptate (99Tc-G), as well as the role of mast cells, SP and its receptor (NK-1R) in dura mater of mice in response to acute stress. Restraint stress for thirty min significantly increased 99Tc-G extravasation in the dura mater of C57BL mice. This effect was absent in W/W(v) mast cell-deficient mice and NK-1 receptor knockout mice (NK-1R-/-), but was unaltered in SP knockout mice (SP-/-). Acute restraint stress also resulted in increased dura mast cell activation in C57BL mice, but not in NK-1R-/- mice. These data demonstrate for the first time that acute stress triggers NI and mast cell activation in mouse dura mater through the activation of NK-1 receptors. The fact that SP-/- mice had intact vascular permeability response to stress indicates that some other NK-1 receptor agonist may substitute for SP. These results may help explain initial events in pathogenesis of stress-induced migraines.

VIP- and PACAP-mediated immunomodulation as prospective therapeutic tools

The immune system and the brain continuously signal to each other, often along the same pathways, which might explain the connection between immunity, the brain and disease. Neuropeptides and their receptors represent part of this communication network, and recent work has examined their relevance to health, proving a potentially crucial clinical significance. The structurally related neuropeptides, vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP), are emerging as a means of fine tuning in the maintenance a balanced steady state in the immune system. Murine knockout and transgenic models for a VIP receptor suggest that VIP is an endogenous anti-inflammatory mediator with characteristics resembling those of a T-helper-2 cytokine. Thus, through molecular mechanisms that are being discovered, VIP might extend the range of therapeutic treatments available for various disorders, including acute and chronic inflammatory diseases, septic shock and autoimmune diseases.

Down-regulation of vasoactive intestinal polypeptide receptor expression in atopic dermatitis

BACKGROUND

Receptors for vasoactive intestinal polypeptide (VIP) have recently been suggested to play a key role in immunomodulation with genetically modified mice. However, it is not known whether changes in receptor gene regulation are involved in the pathogenesis of human immune disorders.

OBJECTIVE

We studied the expression of VPAC(2) in acute lesions of the human immune disease atopic dermatitis.

METHODS

By using nonradioactive in situ hybridization, quantitative immunohistochemistry, RT-PCR, and gene array studies, the expression status of VPAC(2) was assessed in atopic dermatitis and control tissues and in the human mast cell line HMC-1.

RESULTS

In situ hybridization and immunohistochemistry demonstrated VPAC(2) mRNA and protein expression in human mast cells surrounded by VIP positive nerve fibers. Gene array experiments and RT-PCR studies showed high levels of VPAC(2) mRNA expression in mast cells that were increased compared to other receptors such as VPAC(1) or VIP in the human mast cell line HMC-1. Stimulation of HMC-1 cells led to a downregulation of VPAC(2). Similarly, quantitative immunohistochemistry for VPAC(2) in acute atopic dermatitis lesions showed a significantly decreased VPAC(2) immunoreactivity in mast cells.

CONCLUSION

The downregulation of VPAC(2) in human mast cells in acute lesions of atopic dermatitis suggests a role of this G-protein;coupled receptor in the pathophysiology of the disease.

IL-4 inhibits vasoactive intestinal peptide production by macrophages

In schistosomiasis, eggs induce granulomas that have a vasoactive intestinal peptide (VIP) immunoregulatory circuit. This study explored the regulation of VIP production at sites of inflammation. Splenocytes from uninfected C57BL/6 mice expressed VIP mRNA and protein, which stopped following egg deposition. Eggs induce a Th2 response, suggesting that Th2 cytokines like interleukin (IL)-4 can regulate VIP. To address this issue, splenocytes from uninfected mice were incubated for 4 h with or without recombinant IL-4. IL-4 inhibited VIP mRNA expression. F4/80+ macrophages were the source of constitutively expressed VIP, subject to IL-4 regulation. In IL-4 knockout mice, splenic VIP production did not downmodulate during schistosome infection, suggesting that IL-4 is a critical cytokine regulating VIP production in wild-type mouse spleen. IL-4-producing granulomas in schistosomiasis made VIP. Experiments showed that granuloma VIP derived from F4/80- (nonmacrophage) cell populations, explaining this paradox. Granuloma F4/80+ cells from IL-4 knockout mice expressed VIP. Thus macrophages can make VIP, which is subject to IL-4 regulation. However, in the Th2 granulomas, other cell types produce VIP, which compensates for loss of macrophages as a source of this molecule.

Vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide inhibit LPS-stimulated MIP-1alpha production and mRNA expression

Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) are neuropeptides with immunomodulatory properties, including the regulation of several proinflammatory mediators. Such mediators, for example chemokines, influence trafficking of inflammatory cells and contribute to shaping the immune response. In the present work, we studied the effect of VIP and PACAP on the CC chemokine macrophage inflammatory protein-1 alpha (MIP-1alpha) production in LPS-stimulated RAW 264.7 macrophage cell line. VIP and PACAP inhibited the production of MIP-1alpha in a dose-dependent manner and over a broad spectrum of LPS concentrations. The use of selective agonists and antagonists of VIP/PACAP receptors showed that type 1 VIP receptor (VPAC1) is the major receptor involved, but the type 2 VIP receptor (VPAC2) may be also implicated. By using selective PKA and PKC inhibitors and cAMP mimicked agents, we demonstrated a cAMP-dependent signalling pathway for the inhibitory effect of VIP/PACAP on MIP-1alpha production, although a minor non-mediated cAMP pathway was also involved. mRNA expression studies showed a down-regulation of MIP-1alpha gene expression by VIP and PACAP. Taken together, the present work strongly supports an anti-inflammatory role of VIP and PACAP by a new mechanism associated with impairment of a key component of the chemokine network.

Vasoactive intestinal polypeptide as mediator of asthma

Vasoactive intestinal polypeptide (VIP) is one of the most abundant, biologically active peptides found in the human lung. VIP is a likely neurotransmitter or neuromodulator of the inhibitory non-adrenergic non-cholinergic airway nervous system and influences many aspects of pulmonary biology. In human airways VIP-immunoreactive nerve fibres are present in the tracheobronchial airway smooth muscle layer, the walls of pulmonary and bronchial vessels and around submucosal glands. Next to its prominent bronchodilatory effects, VIP potently relaxes pulmonary vessels. The precise role of VIP in the pathogenesis of asthma is still uncertain. Although a therapy using the strong bronchodilatory effects of VIP would offer potential benefits, the rapid inactivation of the peptide by airway peptidases has prevented effective VIP-based drugs so far and non-peptide VIP-agonists did not reach clinical use.

Structural examination of tryptase-, and VIP-positive mast cells in the common bile duct of patients with lithiasis

The morphology of tryptase-, and vasoactive intestinal polypeptide (VIP)-positive mast cells was examined immunohistochemically in 38 common bile ducts collected from patients with secondary chronic cholangitis and varying degrees of inflammatory activity. Mast cells numbers in chronic exacerbated and chronic sclerotic cholangitis were significantly higher as compared with those in controls (72.4 cells/mm2 and 25.2 cells/mm2 vs. 5.9 cells/mm2; p < 0.0001, Student's t test). The increased number of tryptase-positive mast cells in chronic exacerbated cholangitis correlated with the severeness of inflammatory infiltration. In cases of chronic exacerbated cholangitis, the increased number of mast cells was detected in conjunction with active fibroplasia. In chronic sclerotic cholangitis mast cells were lower in number as compared with exacerbated cholangitis and were observed in relation with inactive fibrosis. Numerous VIP-positive mast cells were found in all patients with cholangitis. Ultrastructural immunocytochemistry showed tryptase positivity to be localized over either electron-dense or particulate granules with a mean diameter of 0.261+/-0.073 microm or 0.171+/-0.053 microm, respectively. VIP positivity was formed as a finely or coarsely granular pattern over larger electron-dense granules of 0.475+/-0.14 microm in diameter. Tryptase-positive mast cells were located mainly in and around surface and glandular epithelium. The involvement of tryptase- and VIP-positive mast cells in inflammation, fibrosis and epithelial reactions in the common bile duct is discussed.

Mast cell involvement in interstitial cystitis: a review of human and experimental evidence

Interstitial cystitis (IC) is a heterogeneous syndrome of unknown etiology. Altered bladder glycosaminoglycans lining and bladder mastocytosis have been documented in IC. The objective of this article is to critically examine the published data on bladder mastocytosis in clinical, experimental, and animal studies, with particular emphasis on morphologic evidence of mast cell increase and activation. The literature on bladder mastocytosis and mast cell activation in IC is critically reviewed with particular reference to staining methodology, tryptase immunoreactivity, and electron microscopy. Data from humans and animal models of IC are included. Mastocytosis in IC is best documented by tryptase immunocytochemical staining. Standard surgical stains such as Giemsa and toluidine blue routinely underestimate the degree of mastocytosis. Mast cells are 6- to 8-fold higher in the detrusor compared with controls in "classic IC," and 2- to 3-fold higher in "nonulcerative" IC. Detrusor mastocytosis occurs in both classic and nonulcer IC. Mucosal mast cell increase is present in nonulcerative IC. Mast cell activation without typical exocytosis occurs in the mucosa and submucosa. Activation of mast cells, irrespective of bladder location or degree of mastocytosis, is significant. Mast cell-derived vasoactive and proinflammatory molecules may contribute to the pathogenesis of IC.

Cutting edge: is vasoactive intestinal peptide a type 2 cytokine?

A component of the chemical language shared by the immune and nervous system is the expression of neuropeptides by immune cells. Vasoactive intestinal peptide (VIP) was shown to be produced by T lymphocytes. Here we investigate whether T cell subsets differentially express VIP. Our studies indicate that, upon specific Ag stimulation, Th2 and T2 cells, but not Th1 and T1 cells derived from TCR transgenic (Tg) mice, express VIP mRNA and protein, and secrete VIP. Following immunization with the specific Ag, significant levels of VIP are present in the serum of syngeneic, non-Tg hosts that receive Th2, but not Th1 Tg cells. Th2 Tg cells recovered from the non-Tg hosts immunized with the specific Ag, but not with an irrelevant Ag, express intracellular VIP. Because VIP is produced by Ag-stimulated type 2 T cells, and differentially affects Th1 and Th2 cells, could VIP be viewed as a type 2 cytokine?