TITLE:
Gα12 Regulates Interleukin-8 Expression after Epithelial Cell Injury
AUTHORS:
Alexandra K. Kim, Barrett Richard, Ilene Boucher, Wanfeng Yu, Tianqing Kong, Bradley M. Denker
KEYWORDS:
Gα12, Interleukin-8, Acute Kidney Injury, Inflammation, Fibrosis
JOURNAL NAME:
Open Journal of Pathology,
Vol.6 No.3,
July
11,
2016
ABSTRACT: Acute kidney injury (AKI) is common in
hospitalized patients and is strongly correlated with increased morbidity,
mortality, and prolonged hospitalization. However, signals that determine
whether injured tissues following AKI will repair or fibrose and lead to
chronic kidney disease (CKD) are not well defined. Numerous cytokines are
activated at various times after injury and recruit inflammatory cells.
Interleukin-8 (IL-8) is upregulated following activation of Gα12 by H2O2, a
reactive oxygen species (ROS). Herein, we study this occurrence in vitro and in
vivo. IL-8 was measured by ELISA in Gα12-silenced (si-Gα12) and inducible QLα12
(constitutively active Gα12) Madin-Darby Canine Kidney (QLα12-MDCK) cell lines
after H2O2/catalase cell injury. QLα12- and si-Gα12 MDCK cells showed time-,
agonist- and Gα12-dependent increases in IL-8 mRNA and protein. Gα12-silenced
MDCK cells demonstrated lower IL-8 expression and blunted IL-8 increases. In
transgenic mice (QLα12γGTCre+, proximal tubule Qα12 expression) ischemia
reperfusion injury led to significant upregulation of CXCL-1 (IL-8 homologue)
at 48 hours that was not observed in Gα12 knockout mice. Macrophages in renal
cells from these mice were imaged by immunofluorescent microscopy and
QLα12γGTCre+ showed increased macrophage infiltration. We demonstrate that IL-8
is a critical link between H2O2 stimulated Gα12 and renal injury. Gα12
activation led to increased IL-8 expression, a potent mediator of inflammation
after injury. Future studies targeting Gα12 for inhibition after injury may
blunt the IL-8 response and allow for organ recovery.