Chien-Ya Hung

The New Comorbidity Index for Predicting Survival in Elderly Dialysis Patients: A Long-Term Population-Based Study

Background The worldwide elderly (≥65 years old) dialysis population has grown significantly. This population is expected to have more comorbid conditions and shorter life expectancies than the general elderly population. Predicting outcomes for this population is important for decision-making. Recently, a new comorbidity index (nCI) with good predictive value for patient outcomes was developed and validated in chronic dialysis patients regardless of age. Our study examined the nCI outcome predictability in elderly dialysis patients. Methods and Findings For this population-based cohort study, we used Taiwans National Health Insurance Research Database of enrolled elderly patients, who began maintenance dialysis between January 1999 and December 2005. A total of 21,043 incident dialysis patients were divided into 4 groups by nCI score (intervals ≤3, 4–6, 7–9, ≥10) and followed nearly for 10 years. All-cause mortality and life expectancy were analyzed. During the follow-up period, 11272 (53.55%) patients died. Kaplan-Meier curves showed significant group difference in survival (log-rank: P<0.001). After stratification by age, life expectancy was found to be significantly longer in groups with lower nCI scores. Conclusion The nCI, even without the age component, is a strong predictor of mortality in elderly dialysis patients. Because patients with lower nCI scores may predict better survival, more attention should paid to adequate dialysis rather than palliative care, especially in those without obvious functional impairments.

CD36 is a novel and potential anti‐fibrogenic target in albumin‐induced renal proximal tubule fibrosis

Albumin is not only a risk factor for diabetic nephropathy (DN), but also a therapeutic target. Hence, scientists have long sought ways to elucidate the interactions between albumin and diabetic renal tubule fibrosis. CD36, a surface receptor for thrombospondin‐1, has been reported to interact with latent transforming growth factor‐beta1 (TGF‐β1) and activate its fibrogenic bioactivity. This study elucidates the interactions between CD36 and renal tubule fibrosis. LLC‐PK1 cells were applied to represent renal proximal tubule cells. The expression of CD36 was evaluated by flow cytometry. Fibronectin was assayed by Western blot and enzyme‐linked immunosorbent assay (ELISA). Bioactive TGF‐β1 was assayed by ELISA. We demonstrated that albumin was shown significantly to inhibit cell growth without affecting hypertrophy status since protein content and cell size remained unaffected under albumin treatment. Moreover, albumin dose‐dependently (0, 1, or 10 mg/ml) enhanced the secretion of bioactive TGF‐β1 and fibronectin with the upregulation of CD36. Intriguingly, CD36 siRNA, a potent silencer for CD36 effectively suppressed the albumin‐induced increase in CD36, TGF‐β1, and even fibronectin level. Accordingly, albumin is a pro‐fibrogenic factor for proximal tubule cells since albumin per se markedly upregulated the expression of TGF‐β1 and fibronectin. Most importantly, CD36 may mediate albumin‐induced cellular fibrosis since CD36 siRNA appeared to have anti‐fibrosis effects. This work suggests that CD36 is a novel and potential therapeutic target for diabetic renal tubule fibrosis. J. Cell. Biochem. 101: 735–744, 2007.

Dioscorea alata Attenuates Renal Interstitial Cellular Fibrosis by Regulating Smad- and Epithelial-Mesenchymal Transition Signaling Pathways

Renal interstitial fibrosis is characterized by increased extracellular matrix (ECM) synthesis. Epithelial-mesenchymal transition (EMT) in kidneys is driven by regulated expression of fibrogenic cytokines such as transforming growth factor-beta (TGF-β). Yam, or Dioscorea alata (DA) is an important herb in Chinese medicine widely used for the treatment of clinical diabetes mellitus. However, the fibrosis regulatory effect of DA is unclear. Thus, we examined TGF-β signaling mechanisms against EMT in rat fibroblast cells (NRK-49F). The characterization of DA water-extracts used various methods; after inducing cellular fibrosis in NRK-49F cells by treatment with β-hydroxybutyrate (β-HB) (10 mM), we used Western blotting to examine the protein expression in the TGF-β-related signal protein type I and type II TGF-β receptors, Smads2 and Smad3 (Smad2/3), pSmad2 and Smad3 (pSmad2/3), Smads4, Smads7, and EMT markers. These markers included E-cadherin, alpha-smooth muscle actin (α-SMA), and matrix metalloproteinase-2 (MMP-2). Bioactive TGF-β and fibronectin levels in the culture media were determined using ELISA. Expressions of fibronectin and Snail transcription factor, an EMT-regulatory transcription factor, were assessed by immunofluorescence staining. DA extract dose-dependently (50–200 µg/mL) suppressed β-HB-induced expression of fibronectin in NRK-49F cells concomitantly with the inhibition of Smad2/3, pSmad2/3, and Smad4. By contrast, Smad7 expression was significantly increased. DA extract caused a decrease in α-SMA (α-smooth muscle actin) and MMP-2 levels, and an increase in E-cadherin expression. We propose that DA extract might act as a novel fibrosis antagonist, which acts partly by down regulating the TGF-β/smad signaling pathway and modulating EMT expression.

Safflower extract: A novel renal fibrosis antagonist that functions by suppressing autocrine TGF‐beta

Progressive renal disease is characterized by the accumulation of extracellular matrix proteins in the renal interstitium. Hence, developing agents that antagonize fibrogenic signals is a critical issue facing researchers. The present study investigated the blood‐circulation‐promoting Chinese herb, safflower, on fibrosis status in NRK‐49F cells, a normal rat kidney interstitial fibroblast, to evaluate the underlying signal transduction mechanism of transforming growth factor‐beta (TGF‐β), a potent fibrogenic growth factor. Safflower was characterized and extracted using water. Renal fibrosis model was established both in vitro with fibroblast cells treated with β‐hydroxybutyrate and in vivo using rats undergone unilateral ureteral obstruction (UUO). Western blotting was used to examine protein expression in TGF‐β‐related signal proteins such as type I and type II TGF‐β receptor, Smads2/3, pSmad2/3, Smads4, and Smads7. ELISA was used to analyze bioactive TGF‐β1 and fibronectin levels in the culture media. Safflower extract (SE) significantly inhibited β‐HB‐induced fibrosis in NRK cells concomitantly with dose‐dependent inhibition of the type I TGF‐β1 receptor and its down‐stream signals (i.e., Smad). Moreover, SE dose‐dependently enhanced inhibitory Smad7. Thus, SE can suppress renal cellular fibrosis by inhibiting the TGF‐β autocrine loop. Moreover, remarkably lower levels of tissue collagen were noted in the nephron and serum TGF‐β1 of UUO rats receiving oral SE (0.15 g/3 ml/0.25 kg/day) compared with the untreated controls. Hence, SE is a potential inhibitor of renal fibrosis. We suggest that safflower is a novel renal fibrosis antagonist that functions by down‐regulating TGF‐β signals. J. Cell. Biochem. 104: 908–919, 2008.

The effects of diosgenin in the regulation of renal proximal tubular fibrosis.

Fibrosis is the important pathway for end-stage renal failure. Glucose has been demonstrated to be the most important fibrogenesis-inducing agent according to previous studies. Despite diosgenin has been demonstrated to be anti-inflammatory, the possible role in fibrosis regulation of diosgenin remain to be investigated. In this study, renal proximal tubular epithelial cells (designated as HK-2) were treated with high concentration of glucose (HG, 27.5mM) to determine whether diosgenin (0.1, 1 and 10 μM) has the effects to regulate renal cellular fibrosis. We found that 10 μM of diosgenin exert optimal inhibitory effects on high glucose-induced fibronectin expression in HK-2 cells. In addition, diosgenin markedly inhibited HG-induced increase in α-smooth muscle actin (α-SMA) and HG-induced decrease in E-cadherin. In addition, diosgenin antagonizes high glucose-induced epithelial-to-mesenchymal transition (EMT) signals partly by enhancing the catabolism of Snail in renal cells. Collectively, these data suggest that diosgenin has the potential to inhibit high glucose-induced renal tubular fibrosis possibly through EMT pathway.

20-Hydroxyecdysone attenuates TGF-β1-induced renal cellular fibrosis in proximal tubule cells

UNLABELLED Renal fibrosis progresses to end stage of diabetes kidney disease, which causes irreversible progressive proximal tubular injury. In a previous study, 20-hydroxyecdysterone (20-HE), a phytoecdysteroid, attenuated renal injury in diabetes models. However, the fibrosis regulatory role remains to be investigated. METHODS The proximal tubular epithelial cells (designated as HK-2) were treated for 48 h with TGF-β1 (5 ng/ml) in different concentrations of 20-HE (0 to 500 nM/ml) in the last 24 h of culture. The extracellular fibronectin was measured by ELISA assay. Western blot and immunofluorescence were used to evaluate the expression of TGF-β1/Smads transducer (including Smad2/3, 4, and 7), epithelial and mesenchymal markers (e.g. E-cadherin and α-smooth muscle actin) and Snail (transcriptional regulators for EMT). RESULTS 20-HE reverses TGF-β1-induced increase in fibronectin (both intracellular and extracellular fibronectin). Simultaneously, 20-HE reverses TGF-β1-induced down-regulation of Smad7. In addition, 20-HE significantly attenuates TGF-β1-induced upregulation of Smad2/3 and pSmad2/3, and downregulation of E-Cadherin. Moreover, 20-HE dramatically suppresses TGF-β1-induced increases in the expression of Snail. CONCLUSION We propose that 20-HE is a potential fibrosis antagonist for renal proximal tubule cells. 20-HE might act through suppressing post-receptor signaling of TGF-β1 and restoring tubule epithelial character by blocking the expression of Snail.

Hyperosmolarity enhanced susceptibility to renal tubular fibrosis by modulating catabolism of type I transforming growth factor‐β receptors

Hyperosmolarity plays an essential role in the pathogenesis of diabetic tubular fibrosis. However, the mechanism of the involvement of hyperosmolarity remains unclear. In this study, mannitol was used to evaluate the effects of hyperosmolarity on a renal distal tubule cell line (MDCK). We investigated transforming growth factor‐β receptors and their downstream fibrogenic signal proteins. We show that hyperosmolarity significantly enhances the susceptibility to exogenous transforming growth factor (TGF)‐β1, as mannitol (27.5 mM) significantly enhanced the TGF‐β1‐induced increase in fibronectin levels compared with control experiments (5.5 mM). Specifically, hyperosmolarity induced tyrosine phosphorylation on TGF‐β RII at 336 residues in a time (0–24 h) and dose (5.5–38.5 mM) dependent manner. In addition, hyperosmolarity increased the level of TGF‐β RI in a dose‐ and time‐course dependent manner. These observations may be closely related to decreased catabolism of TGF‐β RI. Hyperosmolarity significantly downregulated the expression of an inhibitory Smad (Smad7), decreased the level of Smurf 1, and reduced ubiquitination of TGF‐β RI. In addition, through the use of cycloheximide and the proteasome inhibitor MG132, we showed that hyperosmolarity significantly increased the half‐life and inhibited the protein level of TGF‐β RI by polyubiquitination and proteasomal degradation. Taken together, our data suggest that hyperosmolarity enhances cellular susceptibility to renal tubular fibrosis by activating the Smad7 pathway and increasing the stability of type I TGF‐β receptors by retarding proteasomal degradation of TGF‐β RI. This study clarifies the mechanism underlying hyperosmotic‐induced renal fibrosis in renal distal tubule cells. J. Cell. Biochem. 109: 663–671, 2010.

Epidemiology of cancer in end-stage renal disease dialysis patients: a national cohort study in Taiwan.

The incidence and mortality of site-specific cancers in patients with end-stage renal disease (ESRD) on maintenance dialysis have been rarely studied for Asian populations. We tapped Taiwan`s National Health Insurance Research Database to identify and recruit patients starting maintenance dialysis between 1999 and 2004. They were followed from initiation of dialysis until death, discontinuation of dialysis, or the end of 2008. We calculated the survival rate and mortality risk of dialysis patients with cancer. Of 40,833 dialysis patients, 2352 (5.8%) had been newly diagnosed with cancer. Being older, being male, and having chronic liver disease were factors associated with a higher risk for new cancer in ESRD dialysis patients. In men, liver cancer (20.63%) was the most frequent, followed by cancers of the bladder (16.88%) and kidney (11.61%). In women, bladder cancer (25.57%) was the most frequent, followed by cancers of the kidney (16.31%) and breast (11.20%). The 5-year survival rates for kidney and bladder cancer were higher than for other cancers; the survival rates for lung, stomach, and liver cancer were lower. In conclusion, the distribution of site-specific cancer was different between men and women in patients with ESRD on dialysis. More attention should be paid to teaching dialysis patients how to avoid the well-known cancer risks and carcinogens and individualized regular cancer screenings.

Treatment with cytokine thymic stromal lymphopoietin short hairpin RNA substantially reduces TGF-β1-induced interstitial cellular fibrosis

Thymic stromal lymphopoietin (TSLP) has previously been linked to allergic inflammatory diseases, and tissue fibrosis and organ dysfunction may also arise from such inflammation. It remains unclear, however, whether TSLP plays any role in the occurrence of renal fibrosis, so this study investigated that possibility. An in vitro fibrosis model was established by treating normal rat kidney fibroblast (NRK-49F) cells with transforming growth factor-β1 (TGF-β1), after which the levels of various fibrogenic markers (e.g., fibronectin) and downstream fibrogenic signal proteins (e.g., smad 7) were investigated. Also, TSLP shRNA was used to silence the effects of TSLP, while an ELISA was conducted to evaluate the fibronectin secretions. The level of fibronectin in the NRK-49F cells was dose- and time-dependently increased by the administration of exogenous TSLP (P<0.05). TSLP also significantly increased the level of fibrosis signaling, in addition to inducing a marked decrease in the down-regulation of Smad7. Interestingly, the application of TSLP shRNA caused a stark reversal of the TGF-β1-induced cellular fibrosis while simultaneously leading to the suppression of fibronectin and fibrogenic signal proteins. Taken together, these observations provide insights into how extracellular matrices develop and could thus lead to potential therapeutic interventions for the suppression of renal fibrosis.

Elucidation of the therapeutic role of mitochondrial biogenesis transducers NRF-1 in the regulation of renal fibrosis.

BACKGROUND Mitochondrial dysfunction is a newly established risk factor for the development of renal fibrosis. Cell survival and injury repair is facilitated by mitochondrial biogenesis. Nuclear respiratory factor 1 (NRF-1) is a transcriptional regulation factor that plays a central role in the regulation of mitochondrial biogenesis. However, the transcription factor of this process in renal fibrosis is unknown. Thus, we hereby discussed the correlations of NRF-1 and renal interstitial fibrosis. MATERIALS AND METHODS In vitro fibrosis model was established by treatment with transforming growth factor-β1 (TGF-β1) in NRK-49F (Normal Rat kidney fibroblast). We investigated the ROS production, mitochondrial biogenesis and fibrogenic marker (e.q. fibronectin) during the progression of renal fibrosis by kit and Western blotting assay. Here, we used that two distinct mechanisms regulate NRF-1 activation and degradation of NRF-1. NRF-1 was transfect by pcDNA-NRF-1 overexpression gene to evaluate the NRF-1 activity of the therapeutic effect in renal fibrosis. In addition, NRF-1 was silenced by shRNA-NRF-1 to evaluate the significance of NRF-1. ELISA was used to evaluate the secreted fibronectin. Immunofluorescence staining was used to assay the in situ expression of proteins (e.g. fibronectin, NRF-1). RESULTS Under renal fibrosis conditions, TGF-β1 (5ng/ml) increased ROS. Simultaneously, TGF-β1-induced extracellular fibronectin by ELISA assay. In addition, TGF-β1 decreased expression of mitochondrial biogenesis. This is the first time to demonstrate that expression of NRF-1 is significantly decreased in renal fibrosis. However, NRK49F was a transfection with pcDNA-NRF-1 (2μg/ml) expression vector dramatically reverse TGF-β1-induced cellular fibrosis concomitantly with the suppression of fibronectin (both intracellular and extracellular fibronectin). More importantly, transfection with shRNA-NRF-1 (2μg/ml) significantly increased the expression of fibronectin of both intercellular and extracellular origins in NRK-49F cells. DISCUSSION These finding suggest that NRF-1 plays a pivotal role on renal cellular fibrosis. Moreover, NRF-1 might act as a novel renal fibrosis antagonist by down-regulating fibrosis signaling in renal fibroblast cells.