Wan-Jun Zhu

Carbonyl stress induces hypertension and cardio-renal vascular injury in Dahl salt-sensitive rats.

One major precursor of carbonyl stress, methylglyoxal (MG), is elevated in the plasma of chronic kidney disease (CKD) patients, and this precursor contributes to the progression of vascular injury, hypertension and renal injury in diabetic nephropathy patients. This molecule induces salt-sensitive hypertension via a reactive oxygen species-mediated pathway. We examined the role of MG in the pathogenesis of hypertension and cardio–renal injury in Dahl salt-sensitive (Dahl S) rats, which is a rat model of CKD. Nine-week-old Dahl S rats were fed a 1% NaCl diet, and 1% MG was added to their drinking water for up to 12 weeks. Blood pressure and cardio–renal injuries were compared with rats treated with tap water alone. The angiotensin II receptor blocker (ARB), candesartan (10 mg kg−1 day−1), was administered to MG Dahl S rats to determine the impact of this drug on the pathogenesis of MG-induced CKD. A progressive increase in systolic blood pressure was observed (123±1–148±5 mm Hg) after 12 weeks of MG administration. MG administration significantly increased urinary albumin excretion, glomerular sclerosis, tubular injury, myocardial collagen content and cardiac perivascular fibrosis. MG also enhanced the renal expression of Nɛ-carboxyethyl-lysine (an advanced glycation end product), 8-hydroxydeoxyguanosine (a marker of oxidative stress), macrophage (ED-1) positive cells (a marker of inflammation) and nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase activity. Candesartan treatment for 4 weeks significantly reduced these parameters. These results suggest that MG-induced hypertension and cardio–renal injury and increased inflammation and carbonyl and oxidative stress, which were partially preventable by an ARB.

Biological Effects of Electrolyzed Water in Hemodialysis

Background/Aims: The application of electrolyzed water (EW) at the cathode side to manufacture reverse osmosis (RO) water and hemodialysis (HD) solution can actually lead to less oxidative capacity in chemical terms. The present study examined the biological actions of this water on human polymorphonuclear leukocytes (PMNs), and the clinical feasibility of applying this technology to HD treatment. Methods: RO water using EW (e-RO) exhibited less chemiluminescence in luminol-hydrogen peroxide and higher dissolved hydrogen levels (–99.0 ppb) compared with control RO water. The effects of e-RO on PMN viability were tested. HD using e-RO was performed for 12 consecutive sessions in 8 patients for the feasibility test. Results: Basal cellular viability and function to generate superoxide radicals of PMNs were better preserved by e-RO application. In the clinical trial, reductions of blood pressure were noted, but no adverse events were observed. There were no changes in the blood dialysis parameters, although methylguanidine levels were significantly decreased at the end of study. Conclusion: The present study demonstrated the capacity of e-RO to preserve the viability of PMNs, and the clinical feasibility of applying this water for HD treatment. The clinical application of this technology may improve the bio-compatibility of HD treatment.

Intake of water with high levels of dissolved hydrogen (H2) suppresses ischemia-induced cardio-renal injury in Dahl salt-sensitive rats

BACKGROUND Hydrogen (H(2)) reportedly produces an antioxidative effect by quenching cytotoxic oxygen radicals. We studied the biological effects of water with dissolved H(2) on ischemia-induced cardio-renal injury in a rat model of chronic kidney disease (CKD). METHODS Dahl salt-sensitive rats (7 weeks old) were allowed ad libitum drinking of filtered water (FW: dissolved H(2), 0.00 ± 0.00 mg/L) or water with dissolved H(2) produced by electrolysis (EW: dissolved H(2), 0.35 ± 0.03 mg/L) for up to 6 weeks on a 0.5% salt diet. The rats then underwent ischemic reperfusion (I/R) of one kidney and were killed a week later for investigation of the contralateral kidney and the heart. RESULTS In the rats given FW, unilateral kidney I/R induced significant increases in plasma monocyte chemoattractant protein-1, methylglyoxal and blood urea nitrogen. Histologically, significant increases were found in glomerular adhesion, cardiac fibrosis, number of ED-1 (CD68)-positive cells and nitrotyrosine staining in the contralateral kidney and the heart. In rats given EW, those findings were significantly ameliorated and there were significant histological differences between rats given FW and those given EW. CONCLUSION Consumption of EW by ad libitum drinking has the potential to ameliorate ischemia-induced cardio-renal injury in CKD model rats. This indicates a novel strategy of applying H(2) produced by water electrolysis technology for the prevention of CKD cardio-renal syndrome.

Polymorphonuclear leukocyte injury by methylglyoxal and hydrogen peroxide: a possible pathological role for enhanced oxidative stress in chronic kidney disease

BACKGROUND Accelerated burst of polymorphonuclear leukocytes (PMNs) may be involved in the primary pathology of enhanced oxidative stress in patients with chronic kidney disease (CKD); however, the precise mechanism remains unknown. Methylglyoxal (MGO), an alpha-oxoaldehyde reportedly elevated in CKD, could induce apoptosis in several cell lines, and generates radicals by the reaction with hydrogen peroxide (H(2)O(2)). Thus, we tested if a high MGO of uraemic milieu could play a role in PMN injury by interaction with H(2)O(2). METHOD Cellular viability of PMNs, isolated from healthy volunteers, was tested by ATP chemiluminescence levels under MGO and/or H(2)O(2), or 4-beta phorbol 12-beta-myristate 13-alpha-acetate (PMA). Superoxide anion (O(2)(-)) generation and apoptosis were measured by the reduction of ferricytochrome C and fluorocytometric analysis, respectively. Plasma MGO levels were measured by mass spectometry in 29 CKD patients. RESULTS At low levels of MGO (1-10 microM) and H(2)O(2) (12.5 microM), no differences were found in cellular viability as compared to controls, whereas their combination significantly decreased PMN viability. PMA stimulation enhanced cellular injury of MGO by a function of MGO levels and preincubation with 5,5-dimethyl-1-pyrroline-N-oxide (free radical trap agent) attenuated it. MGO suppressed O(2)(-) generation by PMA, while it accelerated apoptotic ratios in PMNs. Significant increases of plasma MGO and C-reactive protein levels were found by a function of CKD stage, and clinical level of MGO could induce PMN injury in combination with H(2)O(2). CONCLUSION These results indicate the combinatory effect of MGO and H(2)O(2) on PMN oxidative injury, and this pathology may be linked to enhanced oxidative stress in CKD.

Effect of a hydrogen (H2)-enriched solution on the albumin redox of hemodialysis patients

Elevated oxidative stress (OS) is associated with severe cardiovascular disease and premature death among patients treated with hemodialysis (HD). Oxidative stress is enhanced by contact between blood and dialysis membranes during HD sessions. This study aimed to clarify whether hydrogen (H2), which is a known antioxidant, is capable of suppressing increased OS induced during HD sessions. Eight patients on regular HD treatment were studied. Two HD sessions were performed in a cross‐over design trial using standard and hydrogen‐enriched solutions (mean of 50 p.p.b. H2; H2‐HD). Blood samples were obtained from the inlet and outlet of the dialyzer during HD to determine changes in plasma levels of glutathione, hydrogen peroxide, and albumin redox state as a marker of OS. Comparison of inlet and outlet blood revealed significant decreases in total glutathione and reduced glutathione, as well as significant increases in hydrogen peroxide in both HD treatments. However, the mean proportion of reversibly oxidized albumin in outlet serum was significantly lower than that in inlet serum following the H2‐HD session, whereas no significant changes were found in the standard solution session, suggesting that “intra‐dialyzer” OS is reduced by H2‐HD. In conclusion, the application of H2‐enriched solutions could ameliorate OS during HD.

Transperitoneal administration of dissolved hydrogen for peritoneal dialysis patients: a novel approach to suppress oxidative stress in the peritoneal cavity

BackgroundOxidative stress (OS) related to glucose degradation products such as methylglyoxal is reportedly associated with peritoneal deterioration in patients treated with peritoneal dialysis (PD). However, the use of general antioxidant agents is limited due to their harmful effects. This study aimed to clarify the influence of the novel antioxidant molecular hydrogen (H2) on peritoneal OS using albumin redox state as a marker.MethodsEffluent and blood samples of 6 regular PD patients were obtained during the peritoneal equilibrium test using standard dialysate and hydrogen-enriched dialysate. The redox state of albumin in effluent and blood was determined using high-performance liquid chromatography.ResultsMean proportion of reduced albumin (ƒ(HMA)) in effluent was significantly higher in H2-enriched dialysate (62.31 ± 11.10%) than in standard dialysate (54.70 ± 13.08%). Likewise, serum ƒ(HMA) after administration of hydrogen-enriched dialysate (65.75 ± 7.52%) was significantly higher than that after standard dialysate (62.44 ± 7.66%).ConclusionsTrans-peritoneal administration of H2 reduces peritoneal and systemic OS.

Characteristic effects of methylglyoxal and its degraded product formate on viability of human histiocytes: a possible detoxification pathway of methylglyoxal.

Methylglyoxal (MGO) is a toxic and highly reactive alpha-oxoaldehyde, elevated in the states of various diseases underlying enhanced oxidative stress. Furthermore, MGO has been reported to generate another aldehyde, formic acid (FA). In this sense, investigating the biological property of FA is crucially important. The present study examined the effects of MGO and FA on cell viability using the U937 human histiocytic cell line. FA showed a dose-dependent increase in cell viability at the concentrations of MGO in which cell viability decreased. The mechanism of the increase by FA involved the presence of endogenous hydrogen peroxide (H₂O₂) and tetrahydrofolate in the folate pathway, whereas that of the decrease in cell viability by MGO involved interaction with H₂O₂ and oxidative damage. These findings suggest that FA production by MGO degradation may play a role in attenuation of oxidative cellular injury caused by MGO. We hypothesize that FA generation pathway constitutes a detoxification system for MGO.

Ischemia/reperfusion of unilateral kidney exaggerates aging-induced damage to the heart and contralateral kidney.

Aims: We aimed to determine the impact of aging on ischemic acute kidney injury, especially in terms of the pathological mechanisms of kidney and heart crosstalk. Method: The effects of 45 min of unilateral ischemic reperfusion (IR) of the renal artery on the contralateral kidney and heart were histologically assessed in 7- and 40-week-old SD rats after 7 days. Results: Glomerular sclerosis, interstitial fibrosis and numbers of ED1 cells were significantly increased in the contralateral kidneys of the 40-, but not the 7-week-old rats. The numbers of ED1 cells in the heart significantly and similarly increased in both groups, but reactive fibrosis after IR was significant only in the 40-week-old rats. The exaggerated profibrotic response induced by aging seemed to be closely associated with the increased number of ED1 cells in the affected area. Conclusion: Aging could play a major role in exaggerating the pathological processes of inflammation to fibrosis in remote organs including the heart and the nonischemic kidney after IR stimulation of the unilateral kidney.

Successful treatment of encapsulating peritoneal sclerosis by hemodialysis and peritoneal lavage using dialysate containing dissolved hydrogen.

due to Kingella species, nothing has been mentioned about using intraperitoneal antibiotics with PD fluid. Although our patient attempted to maintain strict sterile precautions and took appropriate care of her PD catheter site, 1 possibility may be that she contaminated the PD set with her oral secretions while coughing. She did admit that maybe 1 – 2 times she failed to use a facemask. This is a hypothesis only, as there is no definitive evidence of causality in our case. There is also no evidence in our case of the organism traversing the gastrointestinal tract to gain entrance into the peritoneal cavity. The possibility of causation via blood borne entry from the oral cavity or aerosol contamination seems to be the most plausible. Figueiredo et al. (18) suggested that use of a face mask during CAPD bag exchange gives no extra protection against peritoneal contamination. More importantly, patients must be educated to perform the connect/disconnect operation carefully, and to strictly observe accidental contamination of the hands. But the description was limited to a single renal unit with a seemingly small number of patients. Also, the patients were healthy and not sick like our patient who was coughing intermittently. This stresses the importance of strict hand hygiene and using a mask, especially if sick, before doing PD exchanges. She will be continued on long-term antibiotics for 6 weeks, her PD catheter was removed, and she will undergo intermittent hemodialysis with a tunneled catheter. In retrospect, she may have had a better outcome with intraperitoneal antibiotics. After completing her 42 days of antibiotics and close follow-up with regard to the clinical response, she will be re-evaluated regarding timing for the placement of a new PD catheter.

Translational Research of Peritoneal Dialysis Solution with Dissolved Molecular Hydrogen

BACKGROUND Improved biocompatibility of peritoneal dialysis solution (PDS) is crucial for peritoneal membrane preservation, thereby ensuring long-term peritoneal dialysis (PD) and preventing encapsulating peritoneal sclerosis. We previously reported the protective effect of molecular hydrogen (H2) on mesothelial cells from PDS in nonuremic rats. SUMMARY In the present study, we examined the effect of H2-containing PDS (commercially available neutral pH type) regarding the protection of peritoneal tissue in experimental chronic kidney disease rats. Furthermore, we conducted a 2-week clinical trial in which H2-containing PDS was used in place of standard PDS and its feasibility was examined. In the experimental study, test solutions were injected through the subcutaneous port into the abdomen for 3 weeks. Histological study revealed a significant increase in the number of mesothelial cells and a significant decrease in peritoneal thickness in the H2-PD group as compared to the control and PD groups. Also, results of immunostaining analysis revealed increased vimentin and apoptotic cells in the membrane of the PD group, indicating that H2 may play a role in ameliorating PDS-induced peritoneal injury and preserving peritoneal integrity. In the clinical trial with 6 prevalent PD patients, all subjects completed the study with no adverse effects. Moreover, there were substantial changes in surrogate markers, such as increased CA125 and mesothelin, in the effluent in selected cases, suggesting enhanced mesothelial regeneration by H2. Key Message: H2-enriched PDS is a candidate novel PDS with improved biocompatibility. Further, our results support the significance of H2-PD clinical trials in the future.