Hisashi Kaneda

Oxidative stress causes enhanced endothelial cell injury in human heme oxygenase-1 deficiency

The first known human case of heme oxygenase-1 (HO-1) deficiency is presented in this report. The patient is a six-year-old boy with severe growth retardation. He has been suffering from persistent hemolytic anemia characterized by marked erythrocyte fragmentation and intravascular hemolysis, with paradoxical increase of serum haptoglobin and low bilirubin. An abnormal coagulation/fibrinolysis system, associated with elevated thrombomodulin and von Willebrand factor, indicated the presence of severe, persistent endothelial damage. Electron microscopy of renal glomeruli revealed detachment of endothelium, with subendothelial deposition of an unidentified material. Iron deposition was noted in renal and hepatic tissue. Immunohistochemistry of hepatic tissue and immunoblotting of a cadmium-stimulated Epstein-Barr virus-transformed lymphoblastoid cell line (LCL) revealed complete absence of HO-1 production. An LCL derived from the patient was extremely sensitive to hemin-induced cell injury. Sequence analysis of the patients HO-1 gene revealed complete loss of exon-2 of the maternal allele and a two-nucleotide deletion within exon3 of the paternal allele. Growth retardation, anemia, iron deposition, and vulnerability to stressful injury are all characteristics observed in recently described HO-1 targeted mice. This study presents not only the first human case of HO-1 deficiency but may also provide clues to the key roles played by this important enzyme in vivo.

Distinct cytokine profiles of systemic-onset juvenile idiopathic arthritis-associated macrophage activation syndrome with particular emphasis on the role of interleukin-18 in its pathogenesis

OBJECTIVES To compare the pro-inflammatory cytokine profiles and the cytokine kinetics in patients with secondary macrophage activation syndrome (MAS) due to systemic-onset juvenile idiopathic arthritis (s-JIA) and in both active and inactive disease states of s-JIA (but no MAS), with those demonstrated in EBV-induced haemophagocytic lymphohistiocytosis (HLH) and Kawasaki disease (KD), and to investigate the significance of IL-18 in the pathogenesis of s-JIA. METHODS Five patients with MAS complicating s-JIA (MAS/s-JIA), 10 with HLH due to EBV infection (EBV-HLH), 22 with KD and 28 healthy controls were analysed. Cytokine concentrations (IL-18, IL-6, neopterin and TNF-alpha receptor Types I and II) were quantified in serum by ELISA. Results were compared with clinical features of MAS/s-JIA, including ferritin concentrations. RESULTS Serum IL-18 concentrations in MAS/s-JIA patients were significantly higher than those in EBV-HLH or KD patients (P < 0.05). Serum IL-6 concentrations in KD patients were significantly higher than those in EBV-HLH or MAS/s-JIA patients. Serum neopterin concentrations in EBV-HLH patients were significantly higher than those in MAS/s-JIA or KD patients. Serum IL-18 correlated positively with the following measurements of disease activity: CRP, ferritin, lactate dehydrogenase and other cytokines (P < 0.05). Serum concentrations of IL-18 in s-JIA patients remained elevated in the inactive phase of disease, whereas clinical parameters and other cytokines normalized. CONCLUSIONS IL-18 may be an important mediator in s-JIA. Although serum Il-18 concentrations correlated with markers of the disease activity, IL-18 concentrations remained elevated even when other markers of disease activity normalized. Serum IL-18 concentration may be a promising indicator of the disease activity. The cytokine release pattern in MAS/HLH is different among patients with different aetiologies. Monitoring the cytokine profile, including IL-18, may be useful for differentiation of MAS/HLH and evaluation of disease activity in s-JIA.

Tubular Injury as a Cardinal Pathologic Feature in Human Heme Oxygenase-1 Deficiency

Heme oxygenase (HO) catalyzes degradation of heme to biliverdin, iron, and carbon monoxide. It consists of three isoforms: an inducible form (HO-1), a constitutive form (HO-2), and the third isoform (HO-3), with properties similar to HO-2. There is limited evidence to suggest that the induction of HO-1 may have anti-inflammatory effects in an in vivo model of oxidative stress-mediated renal injury. We experienced the first human case of HO-1 deficiency. The patient had persistent proteinuria and hematuria, with biochemical evidence of renal tubular injury. We obtained three consecutive renal specimens: two from renal biopsies at 2 and 5 years of age and the third from autopsy at 6 years of age. The patient had systemic vascular endothelial-cell injury with massive intravascular hemolysis. The serum was loaded with heme and a large amount of heme-conjugated haptoglobin. A high concentration of haptoglobin was also detectable in urine. Mesangial proliferation or change in glomerular capillary-wall thickness was relatively mild to moderate in all specimens. Electron microscopic examination showed widespread endothelial detachment and subendothelial deposits of an unidentifiable material. It was striking that tubulointerstitial injury, with tubular dilatation and/or atrophy, interstitial fibrosis, and inflammatory cell infiltration, advanced progressively. Tubular epithelial cells were injured, and massive deposition of iron and haptoglobin was detectable. Bowmans capsules were dilated significantly, probably secondary to the collapse of atrophic tubuli. This is the first report to show that HO-1 has critical roles in vivo in protecting renal tubuli, in addition to vascular endothelium, from oxidative injury.

Structural Evidence of Genomic Exon-Deletion Mediated by Alu-Alu Recombination in a Human Case with Heme Oxygenase-1 Deficiency

We previously reported a family affected by heme oxygenase‐1 (HO‐1) deficiency [Yachie et al., 1999]. The proband was a compound heterozygote for a complete loss of exon 2 (the maternal allele) and a two‐nucleotide deletion within exon 3 (the paternal allele). In this report, we describe a large genomic deletion (1730 bp) including entire exon 2 in this family as a specific mechanism generating exon‐2 absence observed in the HO‐1 mRNA. Analysis of the deletion junction demonstrated fusion of a 5′ portion of Alu‐Sx element with a 3′ portion of Alu‐Sq element. The junction contained sequences with high homology to the recombinogenic Alu “core” sequence. These structural features of the HO‐1 gene suggest homologous recombination associated with Alu element. This study presents the initial characterization of the HO‐1 gene defect causing a human case of HO‐1 deficiency and provides the molecular basis for understanding this genetic disease. Hum Mutat 16:178–179, 2000.

Cytokine profiles of patients with enterohemorrhagic Escherichia coli O111-induced hemolytic-uremic syndrome

Proinflammatory cytokines are related to the pathogenesis of enterohemorrhagic Escherichia coli (EHEC) infection and hemolytic-uremic syndrome (HUS). We assessed the kinetics of the release of cytokines such as neopterin, interleukin (IL)-6, IL-8 and tumour necrosis factor (TNF)-α and the soluble forms of type I and II TNF receptors during EHEC O111-induced HUS (EHEC O111/HUS). Fourteen patients with EHEC O111/HUS were enrolled in this study. Serum concentrations of all cytokines other than TNF-α were significantly elevated in patients with severe HUS compared with those in patients with mild HUS. Although serum concentrations of TNF-α were not significantly higher in patients with severe HUS, most patients with acute encephalopathy showed elevated TNF-α levels. Serum concentrations of these cytokines rapidly and markedly increased, and massive hypercytokinaemia developed 1 day before the diagnosis of HUS in patients with severe HUS. Changes in the number of white blood cells and concentration of serum lactate dehydrogenase were significantly larger between the onset of hemorrhagic colitis and the time of the diagnosis of HUS in patients with severe HUS compared with those in patients with mild HUS. Proinflammatory cytokines play an important role in the pathogenesis of EHEC infection and development of severe complications, including HUS and encephalopathy. Monitoring the cytokine profile may be useful for assessing disease activity of EHEC O111 infections.

Z‐values of tricuspid annular plane systolic excursion in Japanese children

The aim of this study was to establish growth‐related standard values and z‐values for tricuspid annular plane systolic excursion (TAPSE) for Japanese children.

Serum tau protein as a marker of disease activity in enterohemorrhagic Escherichia coli O111-induced hemolytic uremic syndrome

Tau protein levels in cerebrospinal fluid (CSF) and serum are elevated in patients with various central nervous system diseases. We investigated whether serum tau protein levels are useful for predicting and assessing disease activity of acute encephalopathy (AE) in enterohemorrhagic Escherichia coli (EHEC) O111-induced hemolytic uremic syndrome (HUS; EHEC encephalopathy). Serum samples were obtained from 14 patients with EHEC O111/HUS, 20 patients with non-EHEC-related AE, and 20 age- and sex-matched healthy controls. CSF samples were obtained from 2 patients with EHEC encephalopathy and 20 patients with non-EHEC-related AE. Tau protein levels and levels of several proinflammatory cytokines were quantified by enzyme-linked immunosorbent assays. Results were compared with the clinical features of EHEC encephalopathy, including magnetic resonance image (MRI) findings. Serum tau levels in patients with EHEC encephalopathy were significantly elevated compared with those in patients with EHEC O111/HUS without encephalopathy, patients with non-EHEC-related AE, and healthy controls. The ratio of CSF tau levels to serum tau levels was >1.0 in all patients with non-EHEC-related AE but <1.0 in 2 patients with EHEC encephalopathy. Serum tau protein levels increased rapidly and markedly in patients with severe EHEC 0111/HUS and encephalopathy when HUS occurred, but were not elevated in mild patients, even in the HUS phase. Furthermore, changes in serum tau protein levels in patients with EHEC encephalopathy were consistent with abnormalities on brain MRI and were positively correlated with proinflammatory cytokine levels. Our results indicate that serum tau protein might be useful to predict and assess disease activity of EHEC encephalopathy.

Successful Treatment of Enterohemorrhagic Escherichia coli‐Induced Acute Encephalopathy and Hemolytic‐Uremic Syndrome With Polymyxin‐B Direct Hemoperfusion

Peritoneal effluent and blood cultures for aerobic bacteria, anaerobic bacteria, fungi and mycobacteriae were taken, and 1 g/day/intraperitoneal (IP) and 4 g day/IP ampicillin-sulbactam were empirically initiated. On the second day of treatment, the abdominal pain and cloudy PD effluent resolved. On the third day of treatment, S. vestibularis was identified in the peritoneal effluent culture, which was sensitive for amoxicillin, vancomycin, penicillin G, clindamycin and chloramphenicol. Treatment with combined IP ampicillin-sulbactam and ceftazidime was continued for 14 days and resulted in total cure. Streptococcus vestibularis was described as a new microorganism by Whiley et al. in 1988, and it was first isolated from the vestibular mucosa of the human oral cavity (3). It is a Gram-positive, alpha hemolytic, catalasenegative, non motile, 1 μm diameter facultative anaerobe organism and that grows in chains. It produces urease and hydrogen peroxide. It has been uncommonly associated with human diseases including meningitis, prosthetic and native valve endocarditis, dental infections, bacteremia and septicemia in immunosuppressed organisms (4). S. vestibularis is susceptible to vancomycin and resistant to optochin. In the study by Doyuk et al., treatment was initiated with 2 g day intravenous ceftriaxone and 1 mg/kg tid gentamicin, and was switched to 500mgbid vancomycinwith a good clinical response (4). Infections are likely attributable to hematogenous spread from dental procedures or transluminal contamination with oral flora. Considering the poor dental hygiene in our patient, we suggest that our case was related to contamination originating from the oral cavity. Despite evidence that streptococcal peritonitis cases in general may have a lower mortality rate and less catheter loss than peritonitis cases caused by other Grampositive bacteria, some studies have reported that S. viridans peritonitis may have a higher rate of recurrence and slower response to treatment than peritonitis cases caused by other Streptococcus spp. (1,2). Our patient’s response to treatment was excellent, with no eventual catheter loss and no relapse. Although S. vestibularis is a very rare cause of PDrelated peritonitis, until now, undefined types of Streptococcus spp. might have been the cause of some PD-related peritonitis cases. Some of them may be have been caused by S. vestibularis, however, ours is the first published case on PD-related peritonitis.