Affiliation:
1. Department of Clinical and Molecular Biomedicine, University of Catania, Catania, Italy
2. Department of Bio-Medical Science, University of Catania, Catania, Italy
3. Department G. F. Ingrassia, Unit of General and Cellular Biology and Molecular Genetics G. Sichel, University of Catania, Catania, Italy
Abstract
ABSTRACT
Klebsiella pneumoniae
has become an important pathogen in recent years. Although most cases of
K. pneumoniae
endogenous endophthalmitis occur via hematogenous spread, it is not yet clear which microbial and host factors are responsible for the ability of
K. pneumoniae
to cross the blood-retinal barrier (BRB). In the present study, we show that in an
in vitro
model of BRB based on coculturing primary bovine retinal endothelial cells (BREC) and primary bovine retinal pericytes (BRPC),
K. pneumoniae
infection determines changes of transendothelial electrical resistance (TEER) and permeability to sodium fluorescein. In the coculture model, bacteria are able to stimulate the enzyme activities of endothelial cytosolic and Ca
2+
-independent phospholipase A
2
s (cPLA
2
and iPLA
2
). These results were confirmed by the incremental expression of cPLA
2
, iPLA
2
, cyclo-oxygenase-1 (COX1), and COX2 in BREC, as well as by cPLA
2
phosphorylation. In supernatants of
K. pneumoniae
-stimulated cocultures, increases in prostaglandin E
2
(PGE
2
), interleukin-6 (IL-6), IL-8, and vascular endothelial growth factor (VEGF) production were found. Incubation with
K. pneumoniae
in the presence of arachidonoyl trifluoromethyl ketone (AACOCF
3
) or bromoenol lactone (BEL) caused decreased PGE
2
and VEGF release. Scanning electron microscopy and transmission electron microscopy images of BREC and BRPC showed adhesion of
K. pneumoniae
to the cells, but no invasion occurred.
K. pneumoniae
infection also produced reductions in pericyte numbers; transfection of BREC cocultured with BRPC and of human retinal endothelial cells (HREC) cocultured with human retinal pericytes (HRPC) with small interfering RNAs (siRNAs) targeted to cPLA
2
and iPLA
2
restored the pericyte numbers and the TEER and permeability values. Our results show the proinflammatory effect of
K. pneumoniae
on BREC, suggest a possible mechanism by which BREC and BRPC react to the
K. pneumoniae
infection, and may provide physicians and patients with new ways of fighting blinding diseases.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
10 articles.
订阅此论文施引文献
订阅此论文施引文献，注册后可以免费订阅5篇论文的施引文献，订阅后可以查看论文全部施引文献