Peritoneal dialysis (PD) is a life-sustaining
therapy for
end-stage renal disease (
ESRD), used by 10-15% of the dialysis population worldwide.
Peritoneal fibrosis (PF) is a known complication of long-term PD and frequently follows episodes of
peritonitis, rendering the peritoneal membrane inadequate for dialysis.
Transforming growth factor (TGF)-β is an inducer of
fibrosis in several tissues and organs, and its overexpression has been correlated with PF. Animal models of
peritonitis have shown an increase in expression of TGF-β in the peritoneal tissue.
Decorin, a
proteoglycan and component of the extracellular matrix, inactivates TGF-β, consequently reducing
fibrosis in many tissues. Recently,
gold nanoparticles (GNP) have been used for drug delivery in a variety of settings. In the present study, we tested the possibility that GNP-delivered
decorin gene therapy ameliorates
zymosan-mediated PF. We created a PF model using
zymosan-induced
peritonitis. Rats were treated with no
decorin, GNP-
decorin, or adeno-associated virus-
decorin (AAV-
decorin) and compared with controls. Tissue samples were then stained for Masson's trichrome, enface
silver, and
hematoxylin and
eosin, and immunohistochemistry was carried out with
antibodies to TGF-β1, α-smooth muscle actin (α-SMA), and
VEGF. Animals which were treated with GNP-
decorin and AAV-
decorin gene therapy had significant reductions in PF compared with untreated animals. Compared with untreated animals, the treated animals had better preserved peritoneal mesothelial cell size, a significant decrease in peritoneal thickness, and decreased α-SMA. Quantitative PCR measurements showed a significant decrease in the peritoneal tissue levels of α-SMA, TGF-β, and
VEGF in treated vs. untreated animals. This study shows that both GNP-delivered and AAV-mediated
decorin gene
therapies significantly decrease PF in vivo in a rodent model. This approach has important clinical translational potential in providing a therapeutic strategy to prevent PF in PD patients.