Neuropeptide-induced inhibition of IL-16 release from eosinophils

An underlying mechanism behind interventional pulmonology techniques for refractory asthma treatment: Neuro-immunity crosstalk

Asthma is a common disease that seriously threatens public health. With significant developments in bronchoscopy, different interventional pulmonology techniques for refractory asthma treatment have been developed. These technologies achieve therapeutic purposes by targeting diverse aspects of asthma pathophysiology. However, even though these newer techniques have shown appreciable clinical effects, their differences in mechanisms and mutual commonalities still deserve to be carefully explored. Therefore, in this review, we summarized the potential mechanisms of bronchial thermoplasty, targeted lung denervation, and cryoablation, and analyzed the relationship between these different methods. Based on available evidence, we speculated that the main pathway of chronic airway inflammation and other pathophysiologic processes in asthma is sensory nerve-related neurotransmitter release that forms a "neuro-immunity crosstalk" and amplifies airway neurogenic inflammation. The mechanism of completely blocking neuro-immunity crosstalk through dual-ablation of both efferent and afferent fibers may have a leading role in the clinical efficacy of interventional pulmonology in the treatment of asthma and deserves further investigation.

Chromogranin B (CHGB) is dimorphic and responsible for dominant anion channels delivered to cell surface via regulated secretion

Regulated secretion is conserved in all eukaryotes. In vertebrates granin family proteins function in all key steps of regulated secretion. Phase separation and amyloid-based storage of proteins and small molecules in secretory granules require ion homeostasis to maintain their steady states, and thus need ion conductances in granule membranes. But granular ion channels are still elusive. Here we show that granule exocytosis in neuroendocrine cells delivers to cell surface dominant anion channels, to which chromogranin B (CHGB) is critical. Biochemical fractionation shows that native CHGB distributes nearly equally in soluble and membrane-bound forms, and both reconstitute highly selective anion channels in membrane. Confocal imaging resolves granular membrane components including proton pumps and CHGB in puncta on the cell surface after stimulated exocytosis. High pressure freezing immuno-EM reveals a major fraction of CHGB at granule membranes in rat pancreatic β-cells. A cryo-EM structure of bCHGB dimer of a nominal 3.5 Å resolution delineates a central pore with end openings, physically sufficient for membrane-spanning and large single channel conductance. Together our data support that CHGB-containing (CHGB+) channels are characteristic of regulated secretion, and function in granule ion homeostasis near the plasma membrane or possibly in other intracellular processes.

Control of myeloid cell functions by nociceptors

The immune system has evolved to protect the host from infectious agents, parasites, and tumor growth, and to ensure the maintenance of homeostasis. Similarly, the primary function of the somatosensory branch of the peripheral nervous system is to collect and interpret sensory information about the environment, allowing the organism to react to or avoid situations that could otherwise have deleterious effects. Consequently, a teleological argument can be made that it is of advantage for the two systems to cooperate and form an “integrated defense system” that benefits from the unique strengths of both subsystems. Indeed, nociceptors, sensory neurons that detect noxious stimuli and elicit the sensation of pain or itch, exhibit potent immunomodulatory capabilities. Depending on the context and the cellular identity of their communication partners, nociceptors can play both pro- or anti-inflammatory roles, promote tissue repair or aggravate inflammatory damage, improve resistance to pathogens or impair their clearance. In light of such variability, it is not surprising that the full extent of interactions between nociceptors and the immune system remains to be established. Nonetheless, the field of peripheral neuroimmunology is advancing at a rapid pace, and general rules that appear to govern the outcomes of such neuroimmune interactions are beginning to emerge. Thus, in this review, we summarize our current understanding of the interaction between nociceptors and, specifically, the myeloid cells of the innate immune system, while pointing out some of the outstanding questions and unresolved controversies in the field. We focus on such interactions within the densely innervated barrier tissues, which can serve as points of entry for infectious agents and, where known, highlight the molecular mechanisms underlying these interactions.

The Role of Neurotrophins in Inflammation and Allergy

Allergic inflammation is the result of a specific pattern of cellular and humoral responses leading to the activation of the innate and adaptive immune system, which, in turn, results in physiological and structural changes affecting target tissues such as the airways and the skin. Eosinophil activation and the production of soluble mediators such as IgE antibodies are pivotal features in the pathophysiology of allergic diseases. In the past few years, however, convincing evidence has shown that neurons and other neurosensory structures are not only a target of the inflammatory process but also participate in the regulation of immune responses by actively releasing soluble mediators. The main products of these activated sensory neurons are a family of protein growth factors called neurotrophins. They were first isolated in the central nervous system and identified as important factors for the survival and differentiation of neurons during fetal and postnatal development as well as neuronal maintenance later in life. Four members of this family have been identified and well defined: nerve growth factor, brain-derived neurotrophic factor, neurotrophin 3, and neurotrophin 4/5. Neurotrophins play a critical role in the bidirectional signaling mechanisms between immune cells and the neurosensory network structures in the airways and the skin. Pruritus and airway hyperresponsiveness, two major features of atopic dermatitis and asthma, respectively, are associated with the disruption of the neurosensory network activities. In this chapter, we provide a comprehensive description of the neuroimmune interactions underlying the pathophysiological mechanisms of allergic and inflammatory diseases.

Identification of Relationships Between Interleukin 15 mRNA and Brain-Derived Neurotrophic Factor II mRNA Levels With Formal Components of Temperament in Asthmatic Patients

Asthma is a chronic inflammatory and heterogeneous disease developing mostly through allergic inflammation, which modifies the expression of various cytokines and neurotrophins. Previous studies suggest the involvement of interleukin (IL)-15 in the regulation of immune response in asthma. Brain-derived neurotrophic factor (BDNF) II plays an important role as a regulator of development and survival of neurons as well as maintenance of their physiological activity. Chronic stress associated with asthma and elevated IL-15 mRNA and BDNFII mRNA levels may affect the mood and a subjective sensation of dyspnoea-inducing anxiety. Psychopathological variables and numerous cytokine/neurotrophin interactions influence the formation of temperament and strategies of coping with stress. The aim of the study was to identify the role of IL-15 mRNA and BDNFII mRNA expressions and their effect on components of temperament and strategies of coping with stress in asthmatics. A total of 352 subjects (176 healthy volunteers and 176 asthmatic patients) participated in the study. The Formal Characteristic of Behaviour-Temperament Inventory (FCB-TI), Coping Inventory for Stressful Situations (CISS), Beck Depression Inventory, State-Trait Anxiety Inventory, and Borg Rating of Perceived Exertion (RPE) Scale were applied in all the subjects. The expression of IL-15 and BDNFII gene was measured using quantitative real-time polymerase chain reaction (qRT-PCR). Different levels of IL-15 and BDNFII expressions between healthy volunteers and patients were revealed in the study. IL-15 enhanced the BDNFII mRNA expression among patients with bronchial asthma. The depression level negatively correlated with the BDNFII mRNA expression. This neurotrophin modified the temperament variable. BDNFII significantly affected (proportional relationship) the level of briskness in asthmatic patients. BDNFII might influence the level and style of coping with stress (emotion-oriented style). This hypothesis requires further studies on protein functional models. The obtained data confirms the role of IL-15 and BDNFII in the pathomechanisms of depression and formation of selected traits defining the temperament in asthmatics.

Cellular bases for interactions between immunocytes and enteroendocrine cells in the intestinal mucosal barrier of rhesus macaques

The roles of the interactions between nervous, endocrine, and immune systems have been well established in human health and diseases. At present, little is known about the cellular bases for neural-endocrine-immune networks in the gastrointestinal mucosa. In the current study, duodenum, jejunum, ileum, cecum, colon, and rectum autopsies from 15 rhesus macaques and endoscopic duodenal biopsies from 12 rhesus macaques were collected, and the spatial relationships between the endocrine cells and immune cells in the intestinal mucosa were examined by transmission electron microscopy. Eight types of enteroendocrine cells similar to human enterochromaffin cells (EC), D1, G, I, K, L, N, and S cells were found to lie within a one-cell-size distance from immunocytes, in particular the eosinophils in the epithelia or lamina propria. Close apposition of large areas of plasma membranes between many types of enteroendocrine cells and immunocytes, especially between EC, K, S cells and eosinophils, were observed in the epithelia for the first time. These data indicate that complex interactions occur between diverse types of enteroendocrine cells and various immune cells through paracrine mechanisms or via mechanisms dependent on cell-to-cell contact; such interactions might play key roles in maintaining the gut mucosal barrier integrity of rhesus macaques.

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.

Sensory neuropeptides are potent chemoattractants for human basophils in vitro

The sensory neuropeptides secretoneurin (SN) and substance P (SP) are involved in "neurogenic" inflammatory processes as they occur in bronchial asthma or allergic rhinitis. A possible interaction with basophils has not been reported to date. Basophils were isolated from healthy donors by magnetic cell sorting technique and migration was explored using Boyden microchemotaxis chambers. SN [10(-8)M] and SP [10(-6) to 10(-8)M] proved to be chemoattractants equally potent to FMLP [10(-8)M] or LPS [10 pg/ml]. Specific anti-SN antibodies and a trypsinization preparation of SN were used to determine the specificity of the SN effect on basophils. The preincubation of basophils with neurokinin-1 (NK-1) or -2 (NK-2) receptor antagonists revealed the SP effect to act via NK-1 receptors in basophils. In addition, we were able to show phosphodiesterases and phosphoinositide-3 kinases to be engaged in the downstream signalling pathway. Our observations reveal for the first time a link between basophils, which are engaged in allergic processes, and the neuropeptides SN and SP. Furthermore, our data might suggest phosphodiesterases or phosphoinositide-3 kinases to be new therapeutic targets for the treatment of allergic diseases such as asthma or allergic rhinitis.

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.

A new paradigm of eosinophil granulocytes: neuroimmune interactions

Eosinophil granulocytes have long been regarded as potent effector cells with the potential to release an array of inflammatory mediators involved in cytotoxicity to helminths and tissue destruction in chronic inflammatory diseases such as asthma. However, it has become evident that eosinophils are also involved in regulatory mechanisms modulating local tissue immune responses. Eosinophils take part in remodelling and repair mechanisms and contribute to the localized innate and acquired immune response as well as systemic adaptive immunity. In addition, eosinophils are involved in neuroimmune interactions modulating the functional activity of peripheral nerves. Neuromediators can also modulate the functional activity of eosinophils, revealing bidirectional interactions between the two cell types. Eosinophils are tissue-resident cells and have been found in close vicinity of peripheral nerves. This review describes neuroimmune interactions between eosinophil granulocytes and peripheral nerves and highlights why eosinophils are important in allergic diseases such as asthma.

A gel-based dual antibody capture and detection method for assaying of extracellular cytokine secretion: EliCell

A distinguishing feature of eosinophils is their ability to rapidly release preformed cytokines from intracellular pools. Cytokines are delivered to the cell surface from granule stores by transport vesicles and are released in small packets at discrete locations along the cell surface through a process termed "piecemeal" degranulation. The study of this process has been hindered by lack of an assay sensitive enough to register minute protein concentrations and the inability to visualize morphology of cytokine secreting cells. These hindrances have necessitated our development of the EliCell assay, an agarose-based dual cytokine capture and detection system through which cytokine secretion and cellular morphology may be analyzed in concert. Cells are embedded within capture antibody-containing agarose and stimulated under conditions of interest. Extracellularly released cytokine is captured within the matrix at the point of release from the cell and can be labeled with a fluorochrome-conjugated antibody. Cytokine release and cellular morphology are visualized in parallel by phase contrast and fluorescence microscopy, respectively.