In vitroallergen challenge of peripheral blood induces differential gene expression in mononuclear cells of asthmatic patients: inhibition of cytosolic phospholipase A_2αovercomes the asthma‐associated response

Abstract

SummaryBackground Existing treatments for asthma are not effective in all patients and disease exacerbations are common, highlighting the need for increased understanding of disease mechanisms and novel treatment strategies. The leukotriene pathway including the enzyme responsible for arachidonic acid release from cellular phospholipids, cPLA 2 a, is a major contributor to asthmatic responses and an attractive target in asthma therapies. Objective The study reported here investigates (a) the differential effects of in vitro exposure of peripheral blood mononuclear cells (PBMCs) to allergen between asthma and healthy subjects, and (b) the contribution of cPLA 2 a to these differences in gene expression. Methods In vitro responses of asthma (N = 26) and healthy (N = 11) subject PBMC samples to allergen stimulation in the presence and absence of cPLA 2 a inhibition or 5-lipoxygenase inhibition were compared at the gene expression level using oligonucleotide arrays and at the protein level using ELISA. Results Subject samples within both asthma and healthy groups showed allergen-dependent cytokine production and allergen-dependent gene expression changes, although transcriptional profiling identified 153 genes that were modulated significantly differently by allergen between asthma and healthy subjects. Among these were genes previously associated with asthma, but the majority (about 80%) have not previously been associated with asthma. Conclusions Transcriptional profiling elucidated novel gene expression differences between the asthmatic and healthy subject samples. Although 5-lipoxygenase inhibition did not significantly affect allergen-modulated gene expression, the inhibition of cPLA 2 a activity affected many of the allergen-dependent, asthma-associated gene expression changes.

Exacerbating Factors Induce Different Gene Expression Profiles in Peripheral Blood Mononuclear Cells from Asthmatics, Patients with Chronic Obstructive Pulmonary Disease and Healthy Subjects

“…These results confirm those of a previous study where eosinophils isolated from asthmatics and challenged with Der p 1 and Fel d 1 showed increased activity and cPLA 2 phosphorylation [51]. In addition, Whalen et al [52] demonstrated that allergen-induced (Der p 1, Fel d 1 and ragweed) cytokine expression in PBMC is attenuated after inhibition of cPLA 2 α. These observations suggest that allergens may influence the expression or activity of cPLA 2 α.…”

The Involvement of Phospholipases A2in Asthma and Chronic Obstructive Pulmonary Disease

“…In addition, asthmatic patients with shorter microsatellite sequences demonstrate greater expression of cPLA 2 α mRNA, cPLA 2 α protein, PGE 2 and 15-HETE, but not LTC 4 [37]. cPLA 2 participates in intracellular signaling, leading to allergen-induced production of inflammatory cytokines in the PBMC of asthmatics [38]. Hallstrand et al [39] identified increased expression of three cPLA 2 s, including cPLA 2 α , cPLA 2 β , and cPLA 2 γ in induced sputum cells from subjects with asthma and exercise-induced bronchoconstriction.…”

“…It has been confirmed that they are strictly connected with inflammation. The inhibitors of particular PLA 2 s show the positive effect in treatment of inflammatory diseases [96] and they inhibit allergic reaction in vitro [38]. The cPLA 2 α that evolved together with receptors for eicosanoids, present only in vertebrate, seems to play crucial role in course of inflammation.…”

Cytosolic phospholipase A2: physiological function and role in disease

“…The indole cPLA 2 ␣ inhibitors reduced late phase bronchoconstriction and airway hyperreactivity in allergen-challenged sheep. The indole inhibitor also blocked allergen-dependent induction of novel genes expressed in cells from asthmatics ( 195 ). One of the most potent indole from collagen-induced arthritis ( 228 ).…”