Naho Kato

Interleukin-6 modulates oxidative stress produced during the development of cisplatin nephrotoxicity.

AIMS We reported that interleukin-6 (IL-6) plays a protective role in the development of cisplatin-induced acute renal failure (ARF) through upregulation of anti-oxidative stress factors. In this study, we examined the effects of dimethylthiourea (DMTU), a hydroxyl radical scavenger, on the development of cisplatin-induced ARF in wild-type (WT) and IL-6(-/-) mice to determine how IL-6 contributes to modulation of oxidative stress caused by cisplatin. MAIN METHODS WT and IL-6(-/-) male mice were given either cisplatin (30 mg/kg) or saline intraperitoneally. DMTU (100mg/kg) or saline was given 30 min before cisplatin or saline administration. Blood and kidney samples were collected on days 1 and 3 after cisplatin administration. KEY FINDINGS In WT mice, DMTU markedly improved cisplatin-induced renal dysfunction and survival rate. DMTU reduced the expression levels of TNF-α, Bax and c-fos and increased the expression levels of IL-6, Bcl-xL and Nrf2 in WT mice. Reduced reactive oxygen species (ROS) by DMTU resulted in increases of IL-6, anti-apoptosis and anti-oxidant gene expression levels. In IL-6(-/-) mice, DMTU also improved cisplatin-induced renal dysfunction and reduced expression levels of TNF-α, Bax and c-fos, but not Bcl-xL and Nrf2. Since Nrf2 induces IL-6 expression, IL-6 and Nrf2 may influence each other during anti-oxidant responses. The basal level of HO-1 in IL-6(-/-) mice was higher than that in WT mice. SIGNIFICANCE In IL-6(-/-) mice, overproduction of ROS by cisplatin results in upregulation of HO-1 expression in order to eliminate oxidative stress. IL-6 mediates the generation and elimination of ROS during cisplatin-induced ARF.

Interleukin-6 deficiency accelerates cisplatin-induced acute renal failure but not systemic injury

Cisplatin (CDDP), a major chemotherapeutic agent used to treat solid tumors, is known to induce acute renal failure (ARF). The progression of tissue injury involves the coordination of inflammatory and repair responses. Interleukin-6 (IL-6) has been suggested to modulate inflammatory and repair processes in various tissue injuries. In this study, we analyzed IL-6 regulation during CDDP-induced ARF in wild-type (WT) mice and determined the pathological role of IL-6 using IL-6 knockout ((-/-)) mice. A correlation between increase in serum IL-6 level and blood urea nitrogen level was found in WT mice. Renal IL-6 expression in most proximal tubular cells and suppressor of cytokine signaling 3 (SOCS3) gene expression significantly increased in WT mice after administration of CDDP, suggesting active IL-6 signaling during CDDP-induced ARF development. Interestingly, renal dysfunction occurred soon after administration of CDDP and became more severe in IL-6(-/-) mice than that in WT mice. In contrast, the survival rate of IL-6(-/-) mice (50% at 8 days) was better than that of WT mice (10%). Induction levels of proapoptotic Bcl-2 associated X protein (Bax) in renal proximal tubular cells was significantly higher in IL-6(-/-) mice than in WT mice at 24h after CDDP injection. Levels of antiapoptotic proteins, Bcl-2 and Bcl-extra large (Bcl-x(L)), in IL-6(-/-) groups were significantly higher than those in CDDP-treated WT groups throughout the experimental period. Bax might contribute to the development of CDDP-induced ARF at 24h; however, high expression levels of Bcl-x(L) and Bcl-2 might overcome the proapoptosis signaling at 72 h in IL-6(-/-) mice. These results indicated that local and systemic elevation of IL-6 contributes to the development of CDDP-induced ARF and that IL-6 produced in renal tubular cells prevents progression of ARF at the early stage. IL-6 deficiency accelerates CDDP-induced ARF but not development of systemic injury.

Interleukin-6 plays a protective role in development of cisplatin-induced acute renal failure through upregulation of anti-oxidative stress factors

AIMS Cisplatin, a major chemotherapeutic agent, accumulates in proximal tubules of the kidneys and causes acute renal failure dose-dependently. We previously reported that cisplatin induced more severe renal dysfunction in interleukin-6 (IL-6) knockout (IL-6(-/-)) mice than in wild-type (WT) mice. Expression of a pro-apoptotic protein was significantly increased with cisplatin in IL-6(-/-) mice compared to that in WT mice. IL-6, locally expressed in renal tubular cells after cisplatin administration, prevents the development of renal dysfunction at an early stage. In the present study, we focused on downstream signals of IL-6 and oxidative stress induced by cisplatin in order to evaluate the protective role of IL-6 in the development of acute renal failure. MAIN METHODS WT and IL-6(-/-) mice were given either cisplatin (30 mg/kg) or saline intraperitoneally. Blood and kidney samples were collected at 24h and 72 h after cisplatin administration. The changes in expression of 4-hydroxy-2-nonenal protein (4-HNE, oxidative stress marker) and cyclooxygenase-2 (cox-2), activities of superoxide dismutases and caspase-3, and phosphorylation of extracellular signal-regulated kinase (ERK) were examined. KEY FINDINGS Cisplatin increased the expression of 4-HNE and cox-2, and phosphorylation of ERK in IL-6(-/-) mice than in WT mice. On the other hand, activity of superoxide dismutase, an anti-oxidative enzyme, was significantly decreased in the kidney obtained from IL-6(-/-) mice after cisplatin administration. SIGNIFICANCE Our findings suggest that IL-6 plays a protective role in the development of cisplatin-induced acute renal failure through upregulation of anti-oxidative stress factors.

Fatal human poisoning with PadanTM: a cartap-containing pesticide

We report a patient who ingested about 13 g of Padan SG™, a cartap-containing pesticide. After ingestion, the patient developed multiple seizures and dyspnea and lost consciousness. The patient did not recover and died on the fifth hospital day despite treatment at the early stage of poisoning. The cause of death was multisystem organ failure. Results of toxicological analysis were as follows: concentrations of nereistoxin (cartap metabolite) were 10.6 μg/mL in plasma, 18.2 μg/mL in urine, and 2.6 mg/mL in gastric fluid. Results of drug screening of urine by Triage® DOA Panels and using an organophosphate detection kit were negative.

PCR detection of bacterial genes provides evidence of death by drowning

We have developed a sensitive and specific PCR method for detecting plankton DNA in cases of death by drowning. However, this PCR method could not be used for cases of drowning in water containing no plankton. Bacteria species are normally localized in the throat and trachea and they may invade into blood through the respiratory tract in people who have drowned as well as species localized in water. The aim of this study was to establish a novel and expedient PCR method for detecting bacterial genes in samples from drowning cases. We designed primer pairs for Streptococcus salivarius (SL1) and Streptococcus sanguinis (SN1), which are common species in the throat, and for Aeromonas hydrophila (AH1), which has been found in various water samples. With SL1, SN1, and AH1, we detected 10, 0.1, and 1 pg of target DNA, respectively. Among 19 drowned cases within 3 days postmortem, SL-DNA was detected in all of the blood samples from hearts with SL1 and AH-DNA was detected in several samples with AH1. In a case of drowning in a bathtub, use of the conventional acid digestion method for diatom analyses and the PCR method for identifying plankton DNA revealed no plankton, but our PCR method for detecting bacterial DNA showed a positive result for SL-DNA in a blood sample from the heart. In conclusion, our novel PCR method is highly specific and sensitive for detecting bacterial DNA and is useful for cases of death by drowning in water containing no plankton.

Comparison of renal dysfunction in wild-type, IL-6 KO and iNOS KO mice hind limb tourniquet-reperfusion model.

The release of a tourniquet after hind limb ischemia results in vital organ injury, which progresses to multiple organ failure with a high mortality rate. Many events are involved in ischemia-reperfusion (I/R) injury. The purpose of this study was to determine how IL-6 or iNOS is involved in I/R injury using IL-6 knockout (KO) and iNOS KO mice. Male C57BL/6J wild-type (WT), IL-6 knockout (KO) and iNOS KO mice were anesthetized with pentobarbital, and rubber bands were fastened to the inguinal region of both hind limbs for 3h. Blood and kidney samples were obtained before reperfusion and at 1, 2, 3, and 12h after reperfusion. For the control group, mice were kept for 6h under an anesthetized condition without rubber bands. Blood gases and biochemical parameters were analyzed by i-STAT300F. Real-time PCR analyses were performed to examine the expression levels of IL-6 and iNOS mRNA in kidneys. Metabolic acidosis, hemoconcentration and renal dysfunction were significantly developed after reperfusion regardless of mouse genotype, and progression of this condition was earlier in IL-6 KO and iNOS KO mice than in WT mice. The expression level of kidney IL-6 mRNA increased and that of iNOS mRNA decreased after reperfusion. It is possible that late decrease recovery of iNOS mRNA expression in IL-6 KO mice and early progress of IL-6 mRNA expression in iNOS KO mice after reperfusion induce renal dysfunction.

Oxidative stress may be involved in distant organ failure in tourniquet shock model mice

Crush syndrome is characterized by prolonged shock resulting from extensive muscle damage and multiple organ failure. However, the pathogenesis of multiple organ failure has not yet been completely elucidated. Therefore, we investigated the molecular biological and histopathological aspects of distant organ injury in crush syndrome by using tourniquet shock model mice. DNA microarray analysis of the soleus muscle showed an increase in the mRNA levels of Cox-2, Hsp70, c-fos, and IL-6, at 3h after ischemia/reperfusion injury at the lower extremity. In vivo staining with hematoxylin and eosin (HE) showed edema and degeneration in the soleus muscle, but no change in the distant organs. Immunohistological staining of the HSP70 protein revealed nuclear translocation in the soleus muscle, kidney, liver, and lung. The c-fos mRNA levels were elevated in the soleus muscle, kidney, and liver, displaying nuclear translocation of c-FOS protein. Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) analysis suggested the involvement of apoptosis in ischemia/reperfusion injury in the soleus muscle. Apoptotic cells were not found in greater quantities in the kidney. Oxidative stress, as determined using a free radical elective evaluator (d-ROM test), markedly increased after ischemia/reperfusion injury. Therefore, examination of immunohistological changes and determination of oxidative stress are proposed to be useful in evaluating the extent of tourniquet shock, even before changes are observed by HE staining.

Apocynin reduced doxycycline-induced acute liver injury in ovariectomized mice

Highlights • Ovariectomy accelerates doxycycline-induced acute liver injury.• The expression levels of IL-6, IL-10, c-fos, cox-2 and HO-1 genes were strongly upregulated in ovx mice.• Apocynin, totally improved DOXY-induced liver injury in both sham and ovx mice.• NADPH oxidase is responsible for the development of drug-induced acute liver injury

Sudden infant deaths from undiagnosed ventricular septal defect - Report of two autopsy cases

Ventricular septal defect (VSD) has a relatively non-aggressive clinical course; either spontaneous closure or causing congestive heart failure treatable with surgical intervention. We present two autopsy cases of sudden infant deaths from clinically undiagnosed VSDs. Case 1 was an 18-day-old boy. As the deceased coughed and became limp after feeding, he was carried to a hospital. Heart murmur was not auscultated there, so he was brought back to home. He presented severe dyspnea and then he was pronounced dead the next day. Case 2 was a 3-week-old boy. Any abnormality was pointed out at physical examination, although his mother felt his wheeze. He developed respiratory arrest at home in the morning and then he was confirmed dead at the hospital. Heart weights of these babies were heavier than mean weights of each normal development. There were perimembranous VSDs in both cases. Histology revealed that the pulmonary arterial walls were thickened. We diagnosed the cause of death in these cases was cardiac collapse with pulmonary hypertension due to VSD. Congenital heart diseases can be diagnosed as early as before birth, because echocardiograph and fetal echography are prevalent in these days. Most VSDs can be noticed by systolic murmur even today. We consider that the failure of initial clinical diagnosis of VSD in primary physical assessment could lead unexpected sudden death. These two cases reminded us to the importance of auscultation which is conventional but as one of the indispensable measure to find a clue for the congenital abnormality.