The challenge of obtaining correct data for cellular release of inflammatory mediators after in vitro exposure to particulate matter

Abstract

Exposure to ambient particulate matter (PM) has been associated with adverse cardiopulmonary effects where inflammation seems to play an important role. Cellular release of inflammatory mediators is therefore commonly measured in in vitro studies of PM-induced effects. However, adsorption of such mediators to PM may interfere with these measurements and thereby possibly also influence the conclusions of such studies. The aim of the present mini review is to provide the reader with an update on what is currently known about adsorption of inflammatory mediators to PM. We also present a step-by-step method for correction of in vitro results, based on mediator adsorption experiments. Moreover, mediator adsorption and its possible consequences are exemplified with a case study demonstrating adsorption of long pentraxin 3 (PTX3) and vascular endothelial growth factor (VEGF) to a selection of PM samples. The highest degree of adsorption was determined to be 65 and 95% for PTX3 and VEGF respectively, and for the various PM samples the degree of adsorption was highly variable. In conclusion, the data and results discussed in this review underscore the importance of assessing and correcting for mediator adsorption, especially in studies involving comparison of effects induced by several different PM samples.

Keywords: Cytokines; ELISA; Inflammation; Mediator adsorption; Particulate matter.