Eosinophil Granular Proteins Damage Bronchial Epithelial Cells Infected with Respiratory Syncytial Virus

Abstract

Background: Respiratory syncytial (RS) virus infection is an important exacerbating factor in acute bronchial asthma. However, the precise mechanisms responsible for viral infection-induced exacerbations of asthma are uncertain. To elucidate the role of eosinophilic inflammation in the pathogenesis of virus-induced asthma, we investigated the effects of eosinophil granule proteins on bronchial epithelial cell infected with RS virus. Methods: Morphological changes and cytopathic effects in human type II pulmonary alveolar epithelial cells (A549) infected with RS virus and/or eosinophil granule proteins such as major basic protein (MBP), eosinophil peroxidase (EPO), eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN) were observed by microscopy. Apoptosis/necrosis was evaluated by trypan blue exclusion test. We also measured 8 types of phosphorylated proteins in MBP-treated A549 cells infected with RS virus. Results: Although RS virus alone did not affect the cytopathic effects of A549 cells, high concentrations of MBP or a combination of 4 granule proteins resulted in cytopathic effects. MBP or EPO, but not ECP or EDN, induced cytotoxicity and necrosis of the infected A549 cells. Furthermore, MBP induced the phosphorylation of the extracellular signal-regulated kinase (ERK) 1/2, p38 mitogen-activated protein kinase (MAPK), Jun-N-terminal protein kinase (JNK), and signal transducer and activator of transcription (STAT)3 in the infected cells. Conclusions: These results suggest that eosinophil granule proteins, specifically MBP, damage bronchial epithelial cells infected with RS virus and that the MAPK family are involved in these responses, indicating that eosinophilic inflammation might be associated with the pathophysiology of RS virus-induced acute exacerbations of asthma.

Development of a suspension array assay in multiplex for the simultaneous measurement of serum levels of four eosinophil granule proteins

“…The eosinophil granule proteins, major basic protein (MBP), eosinophil cationic protein (ECP), eosinophil derived neurotoxin (EDN) and eosinophil peroxidase (EPO), are eosinophil effector molecules implicated in host defense (Malik and Batra, 2012), immunoregulatory responses (Yang et al, 2008) and allergic and inflammatory reactions (Sedgwick et al, 2004; Kato et al, 2012; Lee et al, 2013). These highly cationic proteins are stored preformed within the secondary granules of eosinophils, and can be released in intact membrane-bound granules during cell lysis or through a complex system of vesiculotubular structures during “piecemeal necrosis” (reviewed in (Muniz et al, 2012)).…”

Histomorphological and immunophenotypic features of pill-induced esophagitis

“…Further study is needed to clarify the implications. Meanwhile, other authors reported a positive relationship between eosinophil infiltration and STAT3 in nasal polyp [29] or bronchial epithelial damage by virus infection [30].…”

Elevated Macrophage Inflammatory Protein 1α and Interleukin-17 Production in an Experimental Asthma Model Infected with Respiratory Syncytial Virus

“…The viral titer of the pooled purified RSV was 2.0 × 10 8 TCID 50 (50% of tissue culture infectious dose)/0.1 ml. Full inactivation of RSV was achieved by exposing a sterile glass vial containing viral suspension to an ultra violet (UV) light source (302 nm) for 16 h at 4°C as previously reported [12,13]. …”