Mast cells and tumour necrosis factor alpha (TNF-α): partners in crime in asthma pathogenesis

Altered mast cell activity in response to rhinovirus infection provides novel insight into asthma

Objective: Human rhinoviruses (RVs) are a type of common respiratory virus capable of inducing an asthma attack. Although mast cells are important effector cells involved in allergic disease, little is known about the direct effects of an RV infection on mast cells. The aim of this study is to investigate mast cell behavior in response to RV infection and gain insight into the effects of RVs on mast cells. Methods: Viral replication, cell viability, apoptosis and cytokine release were quantified in Human mast cell-1 (HMC-1) cells following RV16 infection. Results: The results revealed that the viral RNA copy number increased substantially over time. Intercellular cell adhesion molecule-1 (ICAM-1) transcripts were significantly upregulated from 1.79 to 6.37 times following RV16 infection compared to the controls (p ≤ 0.05). Lactate dehydrogenase (LDH) activity was significantly increased, whereas the cell viability decreased following RV16 infection. Examination of the early cellular response to infection revealed that RV16 increased caspase 3 activity and aggravated apoptotic responses. Furthermore, detection of the innate immune response to RV infection revealed that the release of IL-6, IL-8, TNF-α, and IFN-α by HMC-1 cells increased significantly compared to the control groups. Conclusions: RV infection influences mast cell functionality and promotes the innate immune response of mast cells following viral infection. These results provide a novel insight which mast cells have the potential to be involved in the pathogenesis of RV-induced exacerbations of asthma.

HMGB1 binding to receptor for advanced glycation end products enhances inflammatory responses of human bronchial epithelial cells by activating p38 MAPK and ERK1/2

The proinflammatory factor high mobility group box protein 1 (HMGB1) has been implicated as an important mediator of many chronic inflammatory diseases, including asthma. Human bronchial epithelial cells (HBECs) play a central role in the pathogenesis of asthma. However, the effects of HMGB1 on HBECs and the underlying mechanisms remain unknown. Here, we investigated receptor expression and proinflammatory cytokine production by primary cultures of HBECs stimulated by HMGB1. We then examined the effects of specific receptor blockade and inhibition of p38 MAPK, ERK1/2, or PI3-K on HMGB1-induced expression of proinflammatory cytokines. HMGB1 increased the expression and secretion of TNF-α, TSLP, MMP-9, and VEGF in a dose- and time-dependent manner. HMGB1 also induced elevated expression of RAGE protein. Secretion of TNF-α, VEGF, MMP-9, and TSLP was significantly decreased by RAGE blockade and p38 MAPK pathway inhibition, while a less pronounced effect was mediated by ERK1/2 inhibition. These observations suggest that HMGB1 binds RAGE and promotes activities of p38 MAPK and ERK1/2 pathways in HBECs. This then enhances the expression of TNF-α, VEGF, MMP-9, and TSLP, which are the important inflammatory factors in asthma. These results demonstrate that HMGB1 enhances the inflammatory responses of HBECs, which are involved in the modulation of inflammatory processes in asthma.

Topical Review: The Emerging Field of Epigenetics: Informing Models of Pediatric Trauma and Physical Health

OBJECTIVE

Trauma experienced during childhood and adolescence has been linked to a number of chronic medical concerns. We highlight major findings from the pediatric trauma literature to provide a model for understanding this association.

METHODS

Studies examining the effects of trauma were systematically reviewed and synthesized into a model proposing a central role for epigenetics in the ways that childhood experiences can affect health.

RESULTS

Early hypothalamic pituitary adrenal (HPA) axis response may impact initial trauma experience, with downstream effects on posttrauma adjustment reflected in posttrauma neurobiology, psychological health, and physical health.

CONCLUSIONS

Prospective research with children and adolescents exposed to trauma is needed to better characterize the genetic and epigenetic influences on the course of HPA and immune processes as related to posttrauma psychological and physical health outcomes.

Recent advance in investigation of gene polymorphisms in Japanese patients with aspirin-exacerbated respiratory disease

Aspirin-exacerbated respiratory disease (AERD) is a complex clinical syndrome characterised by severe asthmatic attack upon treatment with aspirin and/or non-steroidal anti-inflammatory drugs (NSAIDs). Genetic predisposition has been considered as a crucial determinant and candidate genes have concentrated especially on cysteinyl leukotrienes (LTs)-related genes as the inhibitory action of aspirin and NSAIDs on cyclooxygenase activity may cause overproduction of cysteinyl LTs. However, conflicting results have been reported, in parallel with replication studies in different ethnic groups. Thus, future areas of investigations need to focus on comprehensive approaches towards the discovery of other genetic biomarkers. Unfortunately, few papers have been reported about gene polymorphisms in Japanese patients with AERD. Here, we described on our recent genetic investigations on B2ADR, IL-13, IL-17A, CYP2C19, TBXA2R, CRTH2 and HSP70. This review indicates potential genetic biomarkers contributing to the early diagnosis of AERD, which may include CYP2C19 and HSP70 gene polymorphisms, and future validation studies in independent population are required to provide reassurance about our findings.