Loss of poly(ADP-ribose) polymerase 1 attenuates renal fibrosis and inflammation during unilateral ureteral obstruction

Abstract

Poly(ADP-ribose) polymerase 1 (PARP1) contributes to necrotic cell death and inflammation in several disease models; however, the role of PARP1 in fibrogenesis remains to be defined. Here, we tested whether PARP1 was involved in the pathogenesis of renal fibrosis using the unilateral ureteral obstruction (UUO) mouse model. UUO was performed by ligation of the left ureter near the renal pelvis in Parp1-knockout (KO) and wild-type (WT) male mice. After 10 days of UUO, renal PARP1 expression and activation were strongly increased by 6- and 13-fold, respectively. Interstitial fibrosis induced by UUO was significantly attenuated in Parp1-KO kidneys compared with that in WT kidneys at 10 days, but not at 3 days, based on collagen deposition, α-smooth muscle actin (α-SMA), and fibronectin expression. Intriguingly, the UUO kidneys in Parp1-KO mice showed a dramatic decrease in infiltration of neutrophil and reduction in expression of proinflammatory proteins including intercellular adhesion molecule-1, tumor necrosis factor-α, inducible nitric oxide synthase, and toll-like receptor 4 as well as phosphorylation of nuclear factor-κB p65, but not transforming growth factor-β1 (TGF-β1) at both 3 and 10 days. Pharmacological inhibition of PARP1 in rat renal interstitial fibroblast (NRK-49F) cell line or genetic ablation in primary mouse embryonic fibroblast cells did not affect TGF-β1-induced de novo α-SMA expression. Parp1 deficiency significantly attenuated UUO-induced histological damage in the kidney tubular cells, but not apoptosis. These data suggest that PARP1 induces necrotic cell death and contributes to inflammatory signaling pathways that trigger fibrogenesis in obstructive nephropathy.

Inhibition of soluble epoxide hydrolase prevents renal interstitial fibrosis and inflammation

“…Similarly, NF-B activation in the kidney was significantly attenuated in sEH-KO mice with DOCA-salt-induced hypertension (34). As we previously reported (25), in the absence of PARP1, NF-B mediated inflammatory mediators TNF-␣ and ICAM-1, and attenuated infiltration of inflammatory cells and the production of cytokines leading to reduced tubulointerstitial lesion and fibrosis in UUO-induced mouse kidneys. In our data, sEH deficiency downregulated TGF-␤1 level in the UUO kidneys.…”

“…All mouse experiments were performed in accordance with the animal protocols approved by the Institutional Animal Care and Use Committee of the University of Nebraska Medical Center. UUO was conducted as previously reported (25). Briefly, the mice were anesthetized with an intraperitoneal injection of a cocktail containing ketamine (200 mg/kg body wt) and xylazine (16 mg/kg body wt).…”

Renal Nerves Drive Interstitial Fibrogenesis in Obstructive Nephropathy

“…Renal denervation lessened the histologic damage score based on periodic acid-Schiff (PAS) staining and the number of apoptotic cells assessed by TUNEL staining during UUO, compared with intact kidneys (Supplemental Figure 3, A and B). Additionally, renal denervation abolished the UUO-induced increase in expression of full-length poly(ADP-ribose) polymerase 1 (PARP1), an indicator of necrosis, 14 as well as the expression of cleaved PARP1 and cleaved caspase-3, markers of apoptosis (Supplemental Figure 3C). In denervated kidneys, the treatment with norepinephrine or CGRP, but not NY or substance P, evoked significant histologic damage and TUNEL-positive apoptotic cell death at 10 days after UUO ( Figure 3C).…”

“…UUO was conducted as previously reported. 14,34 Briefly, the mice were anesthetized with an intraperitoneal injection of a cocktail containing ketamine (200 mg/kg body weight) and xylazine (16 mg/kg body weight). After the left kidney was exposed through the left flank incision, the left ureter was ligated completely near the kidney pelvis using a 5-0 silk tie.…”

“…14 The area of positive Sirius red staining was measured in five randomly chosen high-power (3200) fields per kidney using National Institutes of Health (NIH) ImageJ software (http://rsb.info.nih.gov/ij/).…”