Byssinosis: Role of Polymer Length on the Effect of Tannin on the Airway β-Adrenergic Receptor

Abstract

Tannin, isolated from cotton bracts and implicated in the pathogenesis of byssinosis, inhibits isoproterenol and forskolin-stimulated cAMP release from airway cells in part by decreasing cell surface beta-adrenergic receptor number and uncoupling the beta-adrenergic receptor from its stimulatory G-protein (Gs) and in part by inhibiting adenylyl cyclase activity. We have hypothesized that cotton tannin, because of its long polymer length, interacts with the hydrophobic binding pocket of the beta-adrenergic receptor and alters beta-adrenergic receptor binding and Gs coupling. In these studies, tannins of three different polymer lengths and molecular masses were isolated from cotton bracts using sequential Amicon ultrafiltration [molecular mass > 10, 000 (YM10 retentate), 1,000-10,000 (YM10 filtrate), and 1,000-5,000 Da (YM2 retentate)]. The YM10 retentate (25 microg/ml) decreased chloride secretion (Jnet = 1.11 +/- 0.28 (control) to 0.59 +/- 0.18 microEq/cm2.h, p < 0.05, n = 6), decreased cell surface beta-adrenergic receptor number (18.0 +/- 1.8 (control) to 10.6 +/- 0.9 fmol/mg protein, p < 0.02, n = 4), and inhibited forskolin-stimulated cAMP release (5,254 +/- 1,290 (control) to 2, 968 +/- 620 pmol/mg protein, p < 0.01, n = 8). In contrast, neither the YM10 filtrate nor the YM2 retentate had any effect on net chloride secretion, beta-adrenergic cell surface receptor number, or forskolin-stimulated cAMP release. We conclude that polymer length is essential for the effect of tannin on the beta-adrenergic receptor and on adenylyl cyclase.

In Vivo and In Vitro Effects of Tea Extracts on Enterotoxigenic Escherichia coli‐induced Intestinal Fluid Loss in Animal Models

“…A similar dampening effect of isoproterenol‐induced cAMP formation was found when human INT‐407 cells were preincubated with BTE and GTE. Cloutier and Guernsey (31) proposed that PP molecules may span the receptor domain and affect the coupling between the receptor and the G S protein responsible for activation of adenylate cyclase. A molecular mass greater than 10,000 d or a polymerisation degree of longer than 6 monomers in tannins was essential in their capacity to inhibit forskolin‐induced cAMP‐mediated Cl − secretion in airway epithelial cells.…”

Arrest in ciliated cell expansion on the bronchial lining of adult rats caused by chronic exposure to industrial noise

“…Workers of the textile industry show enhanced prevalence of respiratory disorders that have been interpreted as a consequence of organic dust inhalation (Fishwick et al, 1996;Cloutier and Guernsey, 1998;Simpson et al, 1998;Raza et al, 1999). This may lead to a pneumoconiosis known as byssinosis that has a complex etiology involving other factors in addition to the inhalation of textile fibers Douwes et al, 2003).…”

“…Investigation of VAD prevalence is of particular importance in workers of industries where noise prevails (e.g., airplane and textile plants). Taking into account that textile workers show increased frequency of respiratory infections (Fishwick et al, 1996;Cloutier and Guernsey, 1998;Simpson et al, 1998;Raza et al, 1999), this investigation aimed at finding out whether the bronchial epithelium undergoes any cytological change in animals chronically exposed to cottonmill-room noise. Scanning electron microscopy (SEM) was used to perform quantitative cytology of the bronchial epithelium of noise-exposed and control rats.…”