Impact of body mass on outcomes of geriatric postoperative acute kidney injury patients.

BACKGROUND: Acute kidney injury (AKI) frequently occurs in hospitalized patients, particularly in the elderly. However, studies on outcome-modifying factors in geriatric patients with AKI are absent, especially the influence of body mass index (BMI). METHODS: We performed a retrospective analysis of a prospectively collected multicenter observational cohort, which enrolled elderly (≥65 years) who developed AKI after major surgery in the intensive care units. We analyzed in-hospital mortality within BMI category utilizing Cox proportional hazard regression analysis and generalized additive modeling. RESULTS: Data of a total of 2,015 postoperative elderly patients were retrieved and analyzed. Generalized additive modeling showed that elderly AKI patients with a BMI between 21 and 31 kg/m(2) ("normal") had a lower mortality risk than those with a BMI of less than 21 kg/m(2) ("underweight") or 31 kg/m(2) or greater ("obese"). Both "underweight" and "obese" individuals had a greater risk of mortality compared with patients with "normal" BMI. CONCLUSIONS: The U-shaped association of BMI with hospital mortality in geriatric AKI patients contains a widened base and a shifted nadir comparing with chronic dialysis and other AKI patients. This finding is interesting and warrants our attention.

Advanced age affects the outcome-predictive power of RIFLE classification in geriatric patients with acute kidney injury.

The RIFLE (risk, injury, failure, loss, and end-stage) classification is widely used to gauge the severity of acute kidney injury, but its efficacy has not been formally tested in geriatric patients. To correct this we conducted a prospective observational study in a multicenter cohort of 3931 elderly patients (65 years of age or older) who developed acute kidney injury in accordance with the RIFLE creatinine criteria after major surgery. We studied the predictive power of the RIFLE classification for in-hospital mortality and investigated the potential interaction between age and RIFLE classification. In general, the survivors were significantly younger than the nonsurvivors and more likely to have hypertension. In patients 76 years of age and younger, RIFLE-R, -I, or -F classifications were significantly associated with increased hospital mortality in a stepwise manner. There was no significant difference, however, in hospital mortality in those over 76 years of age between patients with RIFLE-R and RIFLE-I, although RIFLE-F patients had significantly higher mortality than both groups. Thus, the less severe categorizations of acute kidney injury per RIFLE classification may not truly reflect the adverse impact on elderly patients.

Endoplasmic reticulum stress implicated in the development of renal fibrosis.

Endoplasmic reticulum (ER) stress-associated apoptosis plays a role in organ remodeling after insult. The effect of ER stress on renal tubular damage and fibrosis remains controversial. This study aims to investigate whether ER stress is involved in tubular destruction and interstitial fibrosis in vivo. Renal cell apoptosis was proven by terminal deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) stain and poly-ADP ribose polymerase expression in the unilateral ureteral obstruction (UUO) kidney. ER stress was evoked and confirmed by the upregulation of glucose-regulated protein 78 (GRP78) and the common Lys-Asp-Glu-Leu (KDEL) motif of ER retention proteins after UUO. ER stress-associated proapoptotic signals, including B-cell chronic lymphocytic leukemia (CLL)/lymphoma 2-associated × protein (BAX) expression, caspase-12 and c-Jun N-terminal kinase (JNK) phosphorylation, were activated in the UUO kidney. Prolonged ER stress attenuated both unsplicing and splicing X-box binding protein 1 (XBP-1) protein expression, but continued to activate inositol-requiring 1α (IRE1α)-JNK phosphorylation, protein kinase RNA-like endoplasmic reticulum kinase (PERK), eukaryotic translation initiation factor 2α subunit (eIF2α), activating transcription factor (ATF)-4, CCAAT/enhancer binding protein (C/EBP) homologous protein (CHOP) and cleavage activating transcription factor 6 (cATF6)-CHOP signals, which induce ER stress-related apoptosis but attenuate adaptive unfolded protein responses in UUO kidneys. However, renal apoptosis and fibrosis were attenuated in candesartan-treated UUO kidney. Candesartan was associated with maintenance of XBP-1 expression and attenuated ATF4, cATF6 and CHOP protein expression. Taken together, results show that overwhelming ER stress leads to renal cell apoptosis and subsequent fibrosis; and candesartan, at least in part, restores renal integrity by blocking ER stress-related apoptosis. Reducing ER stress may present a way to attenuate renal fibrosis.

Honokiol ameliorates renal fibrosis by inhibiting extracellular matrix and pro-inflammatory factors in vivo and in vitro.

BACKGROUND AND PURPOSE: Renal fibrosis acts as the common pathway leading to the development of end-stage renal disease. The present study investigated, in vivo and in vitro, the anti-fibrotic and anti-inflammatory effects, particularly on the epithelial to mesenchymal transition of renal tubular cells, exerted by honokiol, a phytochemical used in traditional medicine, and mechanisms underlying these effects. EXPERIMENTAL APPROACH: Anti-fibrotic effects in vivo were assayed in a rat model of renal fibrosis [the unilateral ureteral obstruction (UUO) model]. A rat tubular epithelial cell line (NRK-52E) was stimulated by transforming growth factor-ß1 (TGF-ß1) and treated with honokiol to explore possible mechanisms of these anti-fibrotic effects. Gene or protein expression was analysed by Northern or Western blotting. Transcriptional regulation was investigated using luciferase activity driven by a connective tissue growth factor (CTGF) promoter. KEY RESULTS: Honokiol slowed development of renal fibrosis both in vivo and in vitro. Honokiol treatment attenuated tubulointerstitial fibrosis and expression of pro-fibrotic factors in the UUO model. Honokiol also decreased expression of the mRNA for the chemokine CCL2 and for the intracellular adhesion molecule-1, as well as accumulation of type I (α1) collagen and fibronectin in UUO kidneys. Phosphorylation of Smad-2/3 induced by TGF-ß1 and CTGF luciferase activity in renal tubular cells were also inhibited by honokiol. CONCLUSIONS AND IMPLICATIONS: Honokiol suppressed expression of pro-fibrotic and pro-inflammatory factors and of extracellular matrix proteins. Honokiol may become a therapeutic agent to prevent renal fibrosis.

Atorvastatin increases erythropoietin-stimulating agent hyporesponsiveness in maintenance hemodialysis patients: role of anti-inflammation effects.

Erythropoietin-stimulating agent (ESA) hyporesponsiveness is aggravated by chronic inflammation in maintenance hemodialysis (MHD) patients. Dyslipidemia is prevalent in MHD patients. Statin therapy has been demonstrated to not only be effective in lowering lipid levels, but also numerous pleiotropic effects including anti-inflammatory, anti-fibrotic and endothelial function improvement. Recently, a retrospective study has shown that statin therapy decreases ESA requirements in MHD patients. We conducted a prospective study to analyze the effect of statin therapy on ESA hyporesponsiveness, and especially emphasized its anti-inflammatory benefits in MHD patients. This prospective study enrolled 30 patients with baseline cholesterol >220 mg/dl. Low-dose atorvastatin (10 mg/day) was prescribed for 12 weeks. We prospectively recorded patients' biochemistry and hematological profiles, ESA prescription and some inflammatory markers at baseline, 4 weeks and 12 weeks. Statistically significant changes were noted after 4 and 12 weeks of statin therapy for cholesterol (272.5 +/- 41.1 to 184.4 +/- 37.6 and 196.4 +/- 40.2 mg/dl, p < 0.05) and ESA hyporesponsiveness, which demonstrated as erythropoietin to hematocrit ratio (EHR) (129.3 +/- 58.2 to 122.3 +/- 53.5 and 121.0 +/- 53.3 EPO U/Hct/week, p < 0.05). Mean values for proinflammatory cytokines included interleukin-6 and tumor necrotic factor-alpha levels decreased by 30.8 and 10.6%, respectively. Thus, these data suggest that statin therapy may improve ESA hyporesponsiveness in dialysis patients. This improvement in ESA hyporesponsiveness is associated with the effects of statins on inflammation.

In vitro study of peritoneal fibrosis.

Peritoneal fibrosis (PF) is an important issue in peritoneal dialysis (PD) because it remains one of the leading causes of patient drop-out from PD. In this review, we focus on in vitro approaches to the pathogenesis and therapeutic potential of PF and on associated clinical implications. Representative Asian studies, initiated since mid-1990s, that have investigated matrix accumulation in peritoneal tissue possibly leading to PF in the PD population will be highlighted as examples to learn how to apply this research tool. As compared with data from well-designed clinical trials, observations from in vitro models may be far from becoming solid evidence; however, they do cast new light on options for investigations into therapeutic pharmaceuticals.