HSP27 elevated in mild allergic inflammation protects airway epithelium from H2SO4 effects

Abstract

Inflammation in allergic individuals is hypothesized to elevate stress proteins [heat shock proteins (HSP)] in airway epithelium, which may protect cells from further adverse conditions. Allergic, either asthmatic or not, and normal volunteers participated in a 2-day segmental allergen challenge bronchoscopic procedure. Bronchial epithelium was obtained before and after challenge. Epithelium was exposed to medium with H2SO4 (pH5), returned to medium at pH 7.4, and finally harvested for Western blotting with anti-27-kDa HSP (HSP27) antibody. Prechallenge epithelium of all subjects had significantly inhibited ciliary function by H2SO4 (pH 5) conditions (P < 0.001); only epithelium of normals recovered (P = 0.02). Allergic subjects with mild inflammation (< 50 micrograms/ml increase in albumin in bronchoalveolar lavage) had significantly increased HSP27 postchallenge (P = 0.01) and little ciliary dysfunction at pH 5, whereas subjects with severe inflammation (> 50 micrograms/ml increase in albumin) had little change in HSP27 and significant ciliary inhibition (P = 0.02). Normal epithelium had similar trends in HSP27 and equivalent inhibition of ciliary activity at pH 5 before and after allergen challenge. These data indicate that mild inflammation to allergen elevates HSP27 stress protein levels, thereby potentially protecting epithelial function from additional adverse conditions.

Interactions of allergens and irritants in susceptible populations in producing lung dysfunction: implications for future research.

“…To that well-established practice, we would add the caveat that it could be informative to observe both beneficial as well as detrimental effects. Second, in both our studies (15,16) as well as in those of others (4,6,7,13), large intersubject variability has been noted. Efforts to examine reasons for such variability using molecular and genetic approaches, including the use of genetically altered animals, could prove to be most informative.…”

“…Bronchoscopy, segmental allergen challenge, and bronchial brush biopsy are described in detail elsewhere (16,17). Briefly, baseline samples (bronchoalveolar lavage, followed by bronchial brush biopsy to obtain epithelial cells) in one lung were collected from subjects, followed by segmental ragweed challenge in the contralateral lung during a first bronchoscopy.…”

“…Sample Handling, Cell and Albumin Quantitation, and Quantitation of 27-kDa HSP and Ciliary Activity These procedures are described in detail elsewhere (16). Briefly, bronchoalveolar lavage cells were counted, and cell differential counts were performed on Wrightstained cytospins (Accustain; Sigma Diagnostics, St. Louis, MO, USA).…”

“…Our strategy was to perform segmental allergen challenge of volunteers in vivo as a first stress of the epithelial cells and harvest bronchial epithelial cells 24 hr after antigen challenge by bronchial brush biopsy. Then we would provide a second stress by exposing epithelial cells to an acid environment (pH 5 for 3 hr, in vitro) to simulate an acid aerosol exposure (16). We further sought to determine the extent to which these exposures produced stress in the epithelium by quantitating the 27-kDa HSP in epithelial cells, a protein abundant in unstressed lung that has been implicated in actin polymerization.…”

Heat shock response and acute lung injury☆

“…Hsp27, like many of the other stress proteins discussed below, is highly inducible in the lung following exposure to a variety of stressors, thereby enhancing cellular resistance to heat shock, oxidative stress, and inflammatory mediators such as tumor necrosis factor (TNF)-α in vitro and in vivo (74)(75)(76)(77)(78)(79). Hsp27 has been shown in severl in vitro models to inhibit apoptosis, especially following oxidative stress (79).…”