Reduction of collagen VII anchoring fibrils in the airway basement membrane zone of infant rhesus monkeys exposed to house dust mite

Abstract

Collagen VII anchoring fibrils in the basement membrane zone (BMZ) are part of a supracellular anchoring network that attaches the epithelium to the BMZ. Sloughing of airway epithelium in asthmatics (creola bodies) is a pathology associated with the supracellular anchoring network. In a rhesus monkey model of house dust mite (HDM)-induced allergic asthma, we found increased deposition of collagen I in the BMZ. In this study, we determine whether HDM also affected deposition of collagen VII in the BMZ. In the developing airway of rhesus monkeys, the width of collagen VII anchoring fibrils in the BMZ was 0.02 ± 0.04 μm at 1 mo of age. At 6 mo the width had increased to 1.28 ± 0.34 μm and at 12 mo 2.15 ± 0.13 μm. In animals treated with HDM, we found a 42.2% reduction in the width of collagen VII layer in the BMZ at 6 mo (0.74 ± 0.15 μm; P < 0.05). During recovery, the rate of collagen VII deposition returned to normal. However, the amount of collagen VII lost was not recovered after 6 mo. We concluded that normal development of the collagen VII attachment between the epithelium and BMZ occurs in coordination with development of the BMZ. However, in HDM-treated animals, the collagen VII attachment with the epithelium was significantly reduced. Such a reduction in collagen VII may weaken the supracellular anchoring network and be associated with sloughing of the epithelium and formation of creola bodies in asthmatics.