Peter West

Temporal Interleukin-1β Secretion from Primary Human Peripheral Blood Monocytes by P2X7-independent and P2X7-dependent Mechanisms

The processing and regulated secretion of IL-1β are critical points of control of the biological activity of this important pro-inflammatory cytokine. IL-1β is produced by both monocytes and macrophages, but the rate and mechanism of release differ according to the differentiation status and the origin of these cells. We aimed to study the control of processing and release in human blood monocytes and human monocyte-derived macrophages. Toll-like receptor (TLR)-induced IL-1β production and release were investigated for dependence upon caspase-1, P2X7 receptor activation, and loss of membrane asymmetry associated with microvesicle shedding. TLR agonists induced P2X7 receptor-dependent IL-1β release in both monocytes and macrophages; however, only monocytes also showed P2X7 receptor-independent release of mature IL-1β. Furthermore, in monocytes ATP-mediated PS exposure could be activated independently of IL-1β production. Release of IL-1β from monocytes showed selectivity for specific TLR agonists and was accelerated by P2X7 receptor activation. Human monocytes released more IL-1β/cell than macrophages. These data have important implications for inflammatory diseases that involve monocyte activation and IL-1 release.

Morphologic Characterization of Nerves in Whole-Mount Airway Biopsies

RATIONALE Neuroplasticity of bronchopulmonary afferent neurons that respond to mechanical and chemical stimuli may sensitize the cough reflex. Afferent drive in cough is carried by the vagus nerve, and vagal afferent nerve terminals have been well defined in animals. Yet, both unmyelinated C fibers and particularly the morphologically distinct, myelinated, nodose-derived mechanoreceptors described in animals are poorly characterized in humans. To date there are no distinctive molecular markers or detailed morphologies available for human bronchopulmonary afferent nerves. OBJECTIVES Morphologic and neuromolecular characterization of the afferent nerves that are potentially involved in cough in humans. METHODS A whole-mount immunofluorescence approach, rarely used in human lung tissue, was used with antibodies specific to protein gene product 9.5 (PGP9.5) and, for the first time in human lung tissue, 200-kD neurofilament subunit. MEASUREMENTS AND MAIN RESULTS We have developed a robust technique to visualize fibers consistent with autonomic and C fibers and pulmonary neuroendocrine cells. A group of morphologically distinct, 200-kD neurofilament-immunopositive myelinated afferent fibers, a subpopulation of which did not express PGP9.5, was also identified. CONCLUSIONS PGP9.5-immunonegative nerves are strikingly similar to myelinated airway afferents, the cough receptor, and smooth muscle-associated airway receptors described in rodents. These have never been described in humans. Full description of human airway nerves is critical to the translation of animal studies to the clinical setting.

Differential and cell-type specific regulation of responses to Toll-like receptor agonists by ISO-1

Macrophage migration inhibitory factor (MIF) plays vital roles in the regulation of responses to stimuli acting via Toll‐like receptor (TLR)‐4. Recently, a specific small molecule inhibitor of MIF (ISO‐1) has been described. We investigated the effects of ISO‐1 on TLR responses in primary human monocytes and monocyte‐derived macrophages (MDM). In monocytes, ISO‐1 caused marked suppression of TLR4‐induced proinflammatory cytokine production, and to a lesser extent suppression of TLR2‐induced responses. The lipopolysaccharide (LPS)‐induced activation of cocultures of monocytes and endothelial cells was strongly inhibited by ISO‐1. Suppression of monocyte TLR4 signalling by ISO‐1 was associated with alterations in extracellular signal‐related kinase (ERK)‐1/2 activation status. Previously, regulation of TLR4 signalling by MIF has been noted to be through control of TLR4 expression, but we observed that the actions of ISO‐1 were mediated without changes in cell surface TLR4 levels. In contrast, ISO‐1 pretreatment did not inhibit responses of MDM to LPS. ISO‐1 is a promising parent molecule which inhibits TLR‐induced ERK activation and inflammatory cytokine production in monocytes, whose role may be complicated by cell‐type specificity.

Promising approaches for the treatment and prevention of viral respiratory illnesses

&NA; Viral respiratory tract infections are the most common human ailments, leading to enormous health and economic burden. Hundreds of viral species and subtypes have been associated with these conditions, with influenza viruses, respiratory syncytial virus, and rhinoviruses being the most frequent and with the highest burden. When considering prevention or treatment of viral respiratory tract infections, potential targets include the causative pathogens themselves but also the immune response, disease transmission, or even just the symptoms. Strategies targeting all these aspects are developing concurrently, and several novel and promising approaches are emerging. In this perspective we overview the entire range of options and highlight some of the most promising approaches, including new antiviral agents, symptomatic or immunomodulatory drugs, the re‐emergence of natural remedies, and vaccines and public health policies toward prevention. Wide‐scale prevention through immunization appears to be within reach for respiratory syncytial virus and promising for influenza virus, whereas additional effort is needed in regard to rhinovirus, as well as other respiratory tract viruses.

Contributing factors to the development of childhood asthma: working toward risk minimization

Asthma is the most common chronic disease in childhood, and considerable research has been undertaken to find ways to prevent its development and reduce its prevalence. For such interventions to be successful, risk factors for asthma emergence should be identified and clearly defined. Data are robust for some of them, including atopy, viral infections and exposure to airborne irritants, whereas it is less conclusive for others, such as aeroallergen exposure and bacterial infections. Several interventions for asthma prevention, including avoidance and pharmacotherapy, have been attempted. However, most of them have furnished equivocal results. Various issues hinder the establishment of risk factors for asthma development and reduce the effectiveness of interventions, including the complexity of the disease and the fluidity of the developing systems in childhood. In this review, we revisit the evidence on pediatric asthma risk factors and prevention and discuss issues that perplex this field.

PCR based bronchoscopic detection of common respiratory pathogens in chronic cough: a case control study

BackgroundViral respiratory tract infection is the most frequent cause of acute cough and is reported at onset in about one third of patients with chronic cough. Persistent infection is therefore one possible explanation for the cough reflex hypersensitivity and pulmonary inflammation reported in chronic cough patients.MethodsBronchoscopic endobronchial biopsies and bronchoalveolar lavage cell counts were obtained from ten healthy volunteers and twenty treatment resistant chronic cough patients (10 selected for lavage lymphocytosis). A screen for known respiratory pathogens was performed on biopsy tissue. Chronic cough patients also underwent cough reflex sensitivity testing using citric acid.ResultsThere was no significant difference in incidence of infection between healthy volunteers and chronic cough patients (p = 0.115) or non-lymphocytic and lymphocytic groups (p = 0.404). BAL cell percentages were not significantly different between healthy volunteers and chronic cough patients without lymphocytosis. Lymphocytic patients however had a significantly raised percentage of lymphocytes (p < 0.01), neutrophils (p < 0.05), eosinophils (p < 0.05) and decreased macrophages (p < 0.001) verses healthy volunteers. There was no significant difference in the cough reflex sensitivity between non-lymphocytic and lymphocytic patients (p = 0.536).ConclusionsThis study indicates latent infection in the lung is unlikely to play an important role in chronic cough, but a role for undetected or undetectable pathogens in either the lung or a distal site could not be ruled out.Trials registrationCurrent Controlled Trials ISRCTN62337037 & ISRCTN40147207