Prokaryotic RNA activates endothelial cells promoting neutrophil transmigration

CASTILLO, LUIS A.; BIRNBERG WEISS, FEDERICO; RODRIGUEZ?RODRIGUES, NAHUEL; PITTALUGA, JOSÉ R.; MARTIRE?GRECO, DAIANA; MILILLO, M. AYELÉN; GRINSTEIN, SEBASTIAN F.; CAMELLI, MARÍA R.; MENA AYBAR, ANA J.; LANDONI, VERÓNICA I.; FERNÁNDEZ, GABRIELA C.

IMMUNOLOGY AND CELL BIOLOGY

NATURE PUBLISHING GROUP

Lugar: Londres; Año: 2019

0818-9641

Endothelial cell (EC)-neutrophil (PMN) interactions are crucial in the resolution of bacterial infections. Prokaryotic RNA (pRNA) has been reported as a pathogen-associated molecular pattern that is released from bacteria upon death and is able to activate PMN. In this work, we studied the effects of pRNA on EC and investigated whether these effects could modulate EC-PMN interaction. For this purpose, we purified total pRNA from E. coli and used it as a stimulus for Human Umbilical Vein Endothelial Cells (HUVEC). We found that incubationof pRNA with HUVEC caused the increase of surface ICAM-1 (CD54) expression onHUVEC, and the secretion of IL-8 and von Willebrand factor (vWF),characteristicsconsistent with HUVEC activation, without causing toxic effects. Moreover, pRNA-treated HUVEC also induced PMN adhesion and the conditioned medium (CM) obtained from treated-HUVEC was chemotactic for PMN and caused their activation, as determined by CD11b up-regulation. As reported previously, degradation products of pRNA induced similar biological effects. Treatment of HUVEC with endocytosis inhibitors revealed that the entry of pRNA partially relied on a clathrin-dependent mechanism, whereas the effects of degradation products could not be inhibited by any of the inhibitors tested. Using a transwell system, we found that pRNA or degraded pRNA were also able to stimulate HUVEC whenrecognized from the basolateral side. Our results indicate that pRNA activates EC, resulting in the modulation of EC-PMN interaction by inducing PMN chemotaxis, adhesion, and activation. In the context of infection, pRNA sensed by EC and PMN could favor bacterial clearance.