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PARTICLE NUMBER AND SURFACE CHARGE PREDICT THE BIOLOGICAL ACTIVATION OF HUMAN BRONCHIAL EPITHELIAL CELLS EXPOSED TO PARTICULATE MATTER.
Citation:
Veronesi, B, G. Wei, W. Brent, AND M. Oortgiesen. PARTICLE NUMBER AND SURFACE CHARGE PREDICT THE BIOLOGICAL ACTIVATION OF HUMAN BRONCHIAL EPITHELIAL CELLS EXPOSED TO PARTICULATE MATTER. Presented at Society of Toxicology, Nashville, NC, March 18-21, 2002.
Description:
Exposure to particulate matter (PM) produces a uniform degree of mortality in exposed populations, in spite of its diverse sources. This suggests a common mechanism of action to explain its initial toxicity. The present study relates certain physicochemical characteristics (i.e., size, number, surface charge, acidity) of PM particles to their biological activation (i.e., increases in intracellular calcium, [Ca2+]i), IL-6 release) in human, immortalized, tracheal bronchial epithelial cells (BEAS-2B). Urban ambient, volcanic, occupational and industrial PM were examined in suspension and after being passed through a 0.22 mm pore size, cellulose-acetate filter. The size, number and surface charge (i.e., zeta potential) of PM suspensions and their microfiltrates were measured using ZetaPALs technology. Linear regression analysis correlated the IL-6 release caused by field PM and their microfiltrates with their physicochemical characteristics. Of all of these, the surface charge (i.e., zeta potential) of particles in the suspended and microfiltrate fractions strongly correlated with the IL-6 released of their respective exposures. Similarly, the counts of microfiltrate particles also significantly correlated with IL-6 release associated with these fractions. To test whether the surface charge alone could stimulate cytokine release, polystyrene beads (SPM) of low and moderate zeta potentials were obtained. Exposing cells to 12-60 mg/cm2 concentration of SPM produced IL-6 release similar to PM which was sensitive to CPZ exposure, an antagonist of the VR1 irritant receptor. RT-PCR indicated that the charged BEADS activated the acid sensitive, VR1 receptor of the BEAS-2B cells. Together, these data suggest that the surface charge of particles can stimulate a measurable biological response in human respiratory target cells. (This abstract has been reviewed by NHEERL but does not necessarily reflect EPA policy).