Uncoordinated production of Laminin-5 chains in airways epithelium of allergic asthmatics

Kawa Amin,Christer Janson,Per Venge,Ismo Virtanen,Kaoru Miyazaki,Lahja Sevéus

doi:10.1186/1465-9921-6-110

Abstract

BackgroundLaminins are a group of proteins largely responsible for the anchorage of cells to basement membranes. We hypothesized that altered Laminin chain production in the bronchial mucosa might explain the phenomenon of epithelial cell shedding in asthma. The aim was to characterize the presence of Laminin chains in the SEBM and epithelium in allergic and non-allergic asthmatics.Patients and methodsBiopsies were taken from the bronchi of 11 patients with allergic and 9 patients with non-allergic asthma and from 7 controls and stained with antibodies against the Laminin (ln) chains alpha1-alpha5, beta1-beta2 and gamma1-gamma2.ResultsLns-2,-5 and -10 were the main Laminins of SEBM. The layer of ln-10 was thicker in the two asthmatic groups while an increased thickness of lns-2 and -5 was only seen in allergic asthmatics. The ln gamma2-chain, which is only found in ln 5, was exclusively expressed in epithelial cells in association with epithelial injury and in the columnar epithelium of allergic asthmatics.ConclusionThe uncoordinated production of chains of ln-5 in allergic asthma could have a bearing on the poor epithelial cell anchorage in these patients.

Highlights

Laminins are a group of proteins largely responsible for the anchorage of cells to basement membranes
The layer of ln-10 was thicker in the two asthmatic groups while an increased thickness of lns-2 and -5 was only seen in allergic asthmatics
The ln gamma2-chain, which is only found in ln 5, was exclusively expressed in epithelial cells in association with epithelial injury and in the columnar epithelium of allergic asthmatics

Summary

Introduction

Laminins are a group of proteins largely responsible for the anchorage of cells to basement membranes. We hypothesized that altered Laminin chain production in the bronchial mucosa might explain the phenomenon of epithelial cell shedding in asthma. Structural changes and remodelling of the bronchial mucosa with signs of epithelial injury, subepithelial basement thickening, smooth muscle hypertrophy, increased vascularization and innervation are prominent features of the allergic type of asthma and less prominent in the non-allergic type [3]. Until today we know of five α-chains, three βchains and three γ-chains These chains combine into at least 14 different Laminins (lns) i.e. lns 1–14. The chains of laminins have different regions that function by binding to cellular receptor molecules among which the most abundant are integrins, dystroglycan and the recently characterized Lutheran blood group antigen [4,6]. Laminins interact with many other cells and promote migration and angiogenesis and their functions in tumour invasion is one of the hot research topics of today [4]

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