Particulate matter disrupts human lung endothelial cell barrier integrity via Rho‐dependent pathways

Abstract

Increased exposure to ambient particulate matter (PM) is associated with elevated morbidity and mortality in patients with cardiopulmonary diseases and cancer. We and others have shown that PM induces lung microvascular barrier dysfunction which potentially enhances the systemic toxicity of PM. However, the mechanisms by which PM disrupts vascular endothelial integrity remain incompletely explored. We hypothesize that PM induces endothelial cell (EC) cytoskeleton rearrangement via Rho GTPase-dependent pathways to facilitate vascular hyperpermeability. Fine PM induced time-dependent activation of cytoskeletal machinery with increases in myosin light chain (MLC) phosphorylation and EC barrier disruption measured by transendothelial electrical resistance (TER), events attenuated by the Rho-dependent kinase (ROCK) inhibitor Y-27632 or the reactive oxygen species (ROS) scavenger, N-acetylcysteine (NAC). Both Y-27632 and NAC prevented PM-induced stress fiber formation and phospho-MLC accumulation in human lung ECs. PM promotes rapid accumulation of Rho-GTP. This event is attenuated by NAC or knockdown of RhoA (siRNA). Consistent with ROCK activation, PM induced phosphorylation of myosin light chain phosphatase (MYPT) at Thr850, a post-translational modification known to inhibit phosphatase activity. Furthermore, PM activates the guanine nucleotide exchange factor (GEF) for Rho, p115, with p115 translocation to the cell periphery, in a ROS-dependent manner. Together these results demonstrate that fine PM induces EC cytoskeleton rearrangement via Rho-dependent pathways that are dependent upon the generation of oxidative stress. As the disruption of vascular integrity further contributes to cardiopulmonary physiologic derangements, these findings provide pharmacologic targets for prevention of PM-induced cardiopulmonary toxicity.

Microtubule destabilization caused by particulate matter contributes to lung endothelial barrier dysfunction and inflammation

“…1C). These results are also consistent with a recent study which showed Rho-dependent disruption of EC barrier by PM [16]. …”

“…The contribution of oxidative stress, Rho, and IL-6-dependent pathways in PM-induced EC dysfunction has been reported [16, 17, 47], but the interplay between these signaling cascades and crucial mediators in the suggested mechanisms was lacking. The present study shows that PM is another inducer of ROS production and oxidant stress, and LPS and PM share the mechanism of EC barrier disruption via ROS-dependent depolymerization of MT.…”

“…It has long been suggested that EC could be the target of PM exposure, but underlying mechanisms of PM-induced EC dysfunction are less understood. Nevertheless, IL-6 and Rho-mediated disruption of EC barrier function by PM has been reported [16, 17]. …”

Biapenem as a Novel Insight into Drug Repositioning against Particulate Matter-Induced Lung Injury

“…Because PM has been reported to disrupt the integrity of the vascular barrier [18,19], the effects of BIPM on PM-induced vascular disruptive responses were evaluated. As shown in Figure 4A, dye leakage in the BALF was significantly higher following PM 2.5 treatment, which was subsequently suppressed by BIPM or DEX.…”

Deciphering the Code between Air Pollution and Disease: The Effect of Particulate Matter on Cancer Hallmarks

“…Fine PM induced endothelial cell barrier disruption measured by trans-endothelial electrical resistance. PM 2.5 induces endothelial cell cytoskeleton rearrangement causing a disruption of vascular integrity [43]. PAHs and metal components in PM 2.5 promote the activation of pro-angiogenic factors [20,21].…”