Treatment combining aliskiren with paricalcitol is effective against progressive renal tubulointerstitial fibrosis via dual blockade of intrarenal renin

<div><p>The aim of this study was to assess any potential additive effects of a treatment combining aliskiren with paricalcitol on reducing renal fibrosis. C57BL/6J mice were treated individually with aliskiren and/or paricalcitol until 7 days after initiation of unilateral ureteral obstruction (UUO).In obstructed kidneys of UUO mice, monotherapy with aliskiren or paricalcitol significantly attenuated interstitial fibrosis, collagen IV accumulation, and α-smooth muscle actin- and terminal deoxynucleotidyl transferase-mediated biotin nick end-labeling-positive cells. The combination treatment showed additive efficacy in inhibition of these parameters. Renal NADPH oxidase (Nox)1 and Nox2 were significantly decreased by aliskiren or paricalcitol alone or in combination, while renal Nox4 expression was significantly reduced by paricalcitol mono- or combination treatment. Increased levels of p-Erk and p-p38 MAPK, and NF-κB in UUO kidneys were also significantly reduced by either aliskiren or paricalcitol treatment alone or in combination. Aliskiren or paricalcitol monotherapy significantly reduced the expression of (pro)renin receptor in UUO kidneys. In addition, aliskiren tended to augment renin expression in UUO kidneys, but paricalcitol reduced its expression level. The combination treatment effectively blocked both (pro)renin receptor and renin expression induced by aliskiren, and resulted in a further reduction of the renal expression of angiotensin II AT1 receptor. Aliskiren failed to increase the expression of vitamin D receptor in UUO kidneys, but the combination treatment restored its expression level. Taken together, a treatment combining aliskiren with paricalcitol better inhibits UUO-induced renal injury. The mechanism of this synergy may involve more profound inhibition of the intrarenal renin-angiotensin system.</p></div

Effect of aliskiren or paricalcitol monotherapy or combination treatment with both drugs on vitamin D receptor activation in the obstructed kidney.

<p>Representative Western blot (upper) and its quantitative analysis (lower) showing VDR expression in obstructive nephropathy. *P = 0.005 versus UUO and P = 0.008 versus UUO+A and P = 0.025 versus UUO+A+P; **P = 0.040 versus UUO and P = 0.048 versus UUO+A. VDR, vitamin D receptor.</p

Synergistic effect of combination treatment with aliskiren and paricalcitol on the expression of myofibroblasts in the obstructed kidney.

<p>(A) Representative renal sections stained with α-SMA(original magnification, x200). (B) Quantitative analysis of the results for α-SMA in the renal tubulointerstitium. *P<0.001 versus UUO; **P = 0.001 versus UUO; ^#P = 0.001 versus UUO+A and P<0.001 versus UUO+P. α-SMA, α-smooth muscle actin.</p

Differential effects of aliskiren or paricalcitol monotherapy or combination treatment with both drugs on the status of the renin-angiotensin system in the obstructed kidney.

<p>(A) Immunoblotting (left) and its quantitative analysis of PRR (center) and renin (right) showing the effect of monotherapy with aliskiren or paricalcitol or their combination in obstructive nephropathy. *P = 0.011 versus UUO; **P = 0.002 versus UUO and P = 0.024 versus UUO+A (for PRR). *P<0.001 versus UUO and UUO+A; **P<0.001 versus UUO and UUO+A and P = 0.001 versus UUO+P (for rennin). (B) Immunoblotting (left) and its quantitative analysis (right) of AT1R. *P<0.001 versus UUO; **P = 0.014 versus UUO+A; ^#P<0.001 versus UUO+P. PRR, (pro)renin receptor; AT1R, angiotensin II AT1 receptor.</p

Effects of aliskiren or paricalcitol monotherapy or combination treatment with both drugs on NADPH oxidase isoforms in the obstructed kidney.

<p>(A) Representative immunoblot showing the expression of Nox1, Nox2, and Nox4. (B) Quantitative analysis for the expression of Nox1 (upper), Nox2 (lower right), and Nox4 (lower left). *P<0.001 versus UUO; **P = 0.001 versus UUO+A (for Nox1). *P <0.001 versus UUO (for Nox2).*P<0.001 versus UUO and UUO+A (for Nox4).</p

Greater beneficial effect of combination treatment with aliskiren and paricalcitol on renal fibrosis in the obstructed kidney.

<p>(A) Representative renal sections stained with Masson-trichrome (original magnifications, x200). (B) Quantitative analysis of the results for fibrotic area in the renal tubulointerstitium. *P<0.001 versus UUO; **P = 0.001 versus UUO; ^#P<0.001 versus UUO+A or UUO+P.</p

Effects of aliskiren or paricalcitol monotherapy or combination treatment with both drugs on MAPKs and NF-κB in the obstructed kidney.

<p>(A) Immunoblotting and its quantitative analysis of p-Erk and Erk showing the effect of monotherapy with aliskiren or paricalcitol or their combination in obstructive nephropathy. *P = 0.027 versus UUO. (B) Immunoblotting and its quantitative analysis of p-p38 and p38. *P<0.001 versus UUO. (C) Immunoblotting and its quantitative analysis of total NF-κB and p-NF-κB. *P<0.001 versus UUO; **P = 0.003 versus UUO+A; ^#P<0.001 versus UUO+A and P = 0.043 versus UUO+P (for NF-κB). *P<0.001 versus UUO; **P<0.001 versus UUO+A and UUO+P (for p-NF-κB). MAPK, mitogen-activated protein kinase; NF-κB, nuclear factor kappa B; p-Erk, phosphorylated extracellular signal-regulated kinase; Erk, extracellular signal-regulated kinase; p-NF-κB, phosphorylated nuclear factor kappa B.</p

Additive effect of combination treatment with aliskiren and paricalcitol on apoptosis in the obstructed kidney.

<p>(A) Representative renal sections stained with TUNEL (original magnification, x200). (B) Quantitative analysis of the results for TUNEL assay in the renal tubulointerstitium. *P<0.001 versus UUO; **P = 0.021 versus UUO+A. TUNEL, terminal deoxynucleotidyl transferase-mediated biotin nick end-labeling.</p

Efficacy of combination treatment with aliskiren and paricalcitol on tubulointerstitial expression of collagen IV in the obstructed kidney.

<p>Representative Western blot (upper) and its quantitative analysis (lower) showing Col IV expression in obstructive nephropathy. *P = 0.010 versus UUO; **P = 0.022 versus UUO; ^#P = 0.031 versus UUO+A and P = 0.043 versus UUO+P. Col IV, type IV collagen.</p

Serum Gamma-Glutamyltransferase Levels Predict Clinical Outcomes in Hemodialysis Patients

<div><p>Background</p><p>Gamma-glutamyltransferase (GGT) is a biomarker of liver injury. GGT has also been reported to be a marker of oxidative stress and a predictor of mortality in the general population. Hemodialysis (HD) patients suffer from oxidative stress. The aim of our study was to investigate the relationship between serum GGT levels and clinical outcomes in HD patients.</p><p>Methods</p><p>A total of 1,634 HD patients were enrolled from the Clinical Research Center registry for end-stage renal disease, a prospective cohort in Korea. Patients were categorized into three groups by tertiles of serum GGT levels. The primary outcome was all-cause, cardiovascular, or infection-related mortality and hospitalization.</p><p>Results</p><p>During the median follow-up period of 30 months, the highest tertile of serum GGT levels had a significantly higher risk for all-cause mortality (hazard ratio (HR) 2.39, 95% confidence interval (CI), 1.55–3.69, P<0.001), cardiovascular mortality (HR 2.14, 95% CI, 1.07–4.26, P = 0.031) and infection-related mortality (HR 3.07, 95% CI, 1.30–7.25, P = 0.011) using tertile 1 as the reference group after adjusting for clinical variables including liver diseases. The highest tertile also had a significantly higher risk for first hospitalization (HR 1.22, 95% CI, 1.00–1.48, P = 0.048) and cardiovascular hospitalization (HR 1.42, 95% CI, 1.06–1.92, P = 0.028).</p><p>Conclusions</p><p>Our data demonstrate that high serum GGT levels were an independent risk factor for all-cause, cardiovascular, and infection-related mortality, as well as cardiovascular hospitalization in HD patients. These findings suggest that serum GGT levels might be a useful biomarker to predict clinical outcomes in HD patients.</p></div