Cotton dust-mediated lung epithelial injury.

Abstract

To determine if constituents of cotton plants might play a role in byssinosis by injuring pulmonary epithelium, we added extracts of cotton dust, green bract, and field-dried bract to human A549 and rat type II pneumocytes. Injury was measured as pneumocyte lysis and detachment, and inhibition of protein synthesis. Extracts of cotton dust and field-dried bract produced significant doseand time-dependent lysis and detachment of both target cells, while green bract extract was less damaging. Extracts treated with polyvinylpolypyrrolidone to remove tannins produced significantly less injury. In contrast, purified 5,7,3',4'-tetrahydroxyflavan 3,4-diol (THF), a tannin in cotton dust and bract, caused substantial cell damage. Field-dried bract extract and THF also produced dose-dependent inhibition of pneumocyte protein synthesis. Endotoxin levels did not correlate with observed injury. THF added to rat tracheal explants caused epithelial disruption and desquamation, whereas endotoxin did not. Instillation of cotton dust and field-dried bract extract in rat lungs produced disruption of bronchial epithelium and smooth muscle constriction, while polyvinylpolypyrrolidone-treated cotton dust extract produced no injury. These findings suggest that extracts of cotton plants are toxic to alveolar, tracheal, and bronchial epithelium and that THF or other tannins may be the responsible agents.

Apoptotic Neutrophils Undergoing Secondary Necrosis Induce Human Lung Epithelial Cell Detachment

“…The mechanisms are inducer-specific in part. The disruption and desquamation of airway and lung epithelial cells resulting from cellular damage can increase the permeability of the lung parenchyma to fluid and cells [2,4,58]. Many biological cascades follow, resulting in acute airway narrowing and pulmonary inflammatory edema or chronic airway remodeling and lung fibrosis [2,4,58].…”

“…Related symptoms, including dyspnea, cough and wheezing, can occur. The pulmonary function test will reveal airway obstruction, limited lung expansion and decreased gas diffusion [2,4,48].…”

“…Previous studies showed that serine proteinase inhibitors blocked A549 cell detachment induced by activated neutrophils, and that exogenous elastase restored this detachment [3]. Because the disruption and desquamation of airway and lung epithelial cells have been widely observed in a variety of immunological, infectious and inflammatory pulmonary diseases [2,8,10,23], we used lung epithelial cell detachment as a bioassay in this study [9] to investigate the effect of early apoptotic neutrophils on airway epithelial cells and the role of elastase activity in causing the effect. Because CD18 is a ß2 integrin subunit critical to the firm adhesion and the subsequent degranulation response of activated neutrophils [5,57], and because apoptotic neutrophils have been demonstrated to accumulate CD18 on the cell surface [16], we also investigated the role of the integrin CD18 in the cytotoxic effect of apoptosing neutrophils.…”

Airway Responses to the Inhalation of Cotton Dust and Cotton Bract Extracts

“…[15] failed to document a dose-response relationship with endotoxin.Studies by Ayars at al. [40] on the toxicity of cotton mill dust extract, green bract extract and field-dried bract extract, and their components, tannins and endotoxin, to rat and human pneumocytes failed to correlate endotoxin levels with pneumocyte injury.…”

History, current status, and collaborative research projects for Bemisia tabaci

“…Sticky cotton reduces harvesting and ginning efficiency (Johnson et al, 1982;Hector and Hodkinson, 1989). Sticky cotton may also contain leaf trash and dirt causing health problems for textile mill workers (Ayars et al, 1986). Sticky cotton is a serious problem in many cotton production areas in the world (Strolz, 1992).…”