Effect of heme oxygenase-1 on the kidney during septic shock in rats

Heme oxygenase‑1 inhibits renal tubular epithelial cell pyroptosis by regulating mitochondrial function through PINK1

Endotoxin-induced acute kidney injury (AKI) is commonly observed in clinical practice. Renal tubular epithelial cell (RTEC) pyroptosis is one of the main factors leading to the development of endotoxin-induced AKI. Mitochondrial dysfunction can lead to pyroptosis. However, the biological pathways involved in the potential lipopolysaccharide (LPS)-induced pyroptosis of RTECs, notably those associated with mitochondrial dysfunction, are poorly understood. Previous studies have demonstrated that heme oxygenase (HO)-1 confers cell protection via the induction of PTEN-induced putative kinase 1 (PINK1) expression through PTEN to regulate mitochondrial fusion/fission during endotoxin-induced AKI in vivo. Therefore, the present study investigated the role of HO-1/PINK1 in maintaining mitochondrial function and inhibiting the pyroptosis of RTECs exposed to LPS. Primary cultures of RTECs were obtained from wild-type (WT) and PINK1-knockout (PINK1KO) rats. An in vitro model of endotoxin-associated RTEC injury was established following treatment of the cells with LPS. The WT RTECs were divided into the control, LPS, Znpp + LPS and Hemin + LPS groups, and the PINK1KO RTECs were divided into the control, LPS and Hemin + LPS groups. RTECs were exposed to LPS for 6 h to assess cell viability, inflammation, pyroptosis and mitochondrial function. In the LPS-treated RTECs, the mRNA and protein expression levels of HO-1 and PINK1 were upregulated. Cell viability, adenosine triphosphate (ATP) levels and the mitochondrial oxygen consumption rate were decreased, whereas the inflammatory response, pyroptosis and mitochondrial reactive oxygen species (ROS) levels were increased. The cell inflammatory response and the induction of pyroptosis were inhibited, whereas the levels of mitochondrial ROS were decreased. In addition, the cell viability and ATP levels were increased in the WT RTECs following the upregulation of HO-1 expression. These effects were reversed by the downregulation of HO-1 expression. However, no statistically significant differences were noted between the LPS and the Hemin + LPS groups in the PINK1KO RTECs. Collectively, the findings of the present study indicate that HO-1 inhibits inflammation and regulates mitochondrial function by inhibiting the pyroptosis of LPS-exposed RTECs via PINK1.

Protective Effect of Electroacupuncture on the Barrier Function of Intestinal Injury in Endotoxemia through HO-1/PINK1 Pathway-Mediated Mitochondrial Dynamics Regulation

Background and Aims

Endotoxemia (ET) is a common critical illness in patients receiving intensive care and is associated with high mortality and prolonged hospital stay. The intestinal epithelial cell dysfunction is regarded as the "engine" of deteriorated ET. Although electroacupuncture (EA) can mitigate endotoxin-induced intestinal epithelial cell dysfunction in ET, the mechanism through which EA improves endotoxin-induced intestinal injury for preventing ET deterioration needs further investigation.

Methods

An in vivo ET model was developed by injecting lipopolysaccharide (LPS) in wild-type and PINK1-knockout mice. An in vitro model was also established by incubating epithelial cells in the serum samples obtained from both groups of mice. Hemin and zinc protoporphyrin IX (ZnPP) were applied to activate or inhibit heme oxygenase 1 (HO-1) production. EA treatment was performed for 30 min consecutively for 5 days before LPS injection, and on the day of the experiment, EA was performed throughout the process. Samples were harvested at 6 h after LPS induction for analyzing tissue injury, oxidative stress, ATP production, activity of diamine oxidase (DAO), and changes in the levels of HO-1, PTEN-induced putative kinase 1 (PINK1), mitochondrial fusion and fission marker gene, caspase-1, and interleukin 1 beta (IL-1β).

Results

In the wild-type models (both in vivo and vitro), EA alleviated LPS-induced intestinal injury and mitochondrial dysfunction, as indicated by decreased reactive oxygen species (ROS) production and oxygen consumption rate (OCR) and reduced levels of mitochondrial fission proteins. EA treatment also boosted histopathological morphology, ATP levels, DAO activity, and levels of mitochondrial fusion proteins in vivo and vitro. The effect of EA was enhanced by hemin but suppressed by Znpp. However, EA + AP, Znpp, or hemin had no effects on the LPS-induced, PINK1-knocked out mouse models.

Conclusion

EA may improve the HO-1/PINK1 pathway-mediated mitochondrial dynamic balance to protect the intestinal barrier in patients with ET.

Sevoflurane inhibits ferroptosis: A new mechanism to explain its protective role against lipopolysaccharide-induced acute lung injury

Sevoflurane (Sev) has protective effects in acute lung injury (ALI), but the relevant mechanisms are still not fully understood. The present study aimed to determine whether Sev exerts a protective effect on lipopolysaccharide (LPS)-induced ALI by regulating ferroptosis. In this study, we found that Sev could protect mice from lung injury caused by LPS stimulation, including extenuating lung histological damage, pulmonary edema and pulmonary vascular permeability, and the content of inflammatory factors in Bronchoalveolar lavage fluid (BALF), as well as improving the survival rate of ALI mice, which was in line with the effects of ferroptosis inhibitor ferrostatin-1. Simultaneously, Sev could eliminate the worsening effects of ferroptosis inducer Fe-citrate on LPS-induced ALI to a certain extent. Additionally, the administration of Sev could inhibit ferroptosis caused by LPS, which was manifested by reducing the accumulation of MDA and Fe²⁺, and increasing the levels of GSH and GPX4 in the lung tissues of ALI mice. It was also observed in BEAS-2B cells that the increased MDA and Fe²⁺ levels and the decreased GSH and GPX4 levels caused by LPS could be rescued by ferrostatin-1 and Sev. LPS stimulation compensatory up-regulated heme oxygenase-1 (HO-1) expression in mouse lung tissues and BEAS-2B cells, which could be enhanced by Sev. Moreover, HO-1 depletion could offset the inhibitory effect of Sev on LPS-induced ferroptosis and inflammation in BEAS-2B cells. Taken together, Sev inhibited ferroptosis by up-regulating HO-1 expression to reduce LPS-induced ALI, which may provide a possible mechanism for the application of Sev in clinical anesthesia.

Isoflurane reduces septic neuron injury by HO‑1‑mediated abatement of inflammation and apoptosis

Sepsis-associated encephalopathy (SAE) frequently occurs in critically ill patients with severe systemic infections. Subanesthetic isoflurane (0.7% ISO) possesses anti-inflammatory, antioxidant and anti-apoptotic properties against a number of human diseases, including brain injury. The activation of heme oxygenase-1 (HO-1) impedes inflammation, oxidation and apoptosis, thus alleviating sepsis-induced brain damage. However, whether 0.7% ISO affords protection against septic neuronal injury involving HO-1 activation is unclear. The present study aimed to investigate the neuroprotective effects of 0.7% ISO and its potential underlying mechanisms in SAE using a mouse model established by cecal ligation and puncture (CLP). The results indicated that the expression and activity of HO-1 in the mouse hippocampus were increased by CLP, and further enhanced by ISO. ISO reduced the death rate, brain water content and blood-brain barrier disruption, but improved the learning and memory functions of CLP-treated mice. ISO significantly decreased the production of pro-inflammatory cytokines and the levels of oxidative indictors in the serum and hippocampus, as well as the number of apoptotic neurons and the expression of pro-apoptotic proteins in the hippocampus. Inversely, anti-inflammatory factors, antioxidative enzymes and anti-apoptotic proteins were markedly increased by ISO administration. However, the neuroprotective effects of ISO were abolished by a HO-1 inhibitor. Overall, these findings suggested that 0.7% ISO alleviated SAE via its anti-inflammatory, antioxidative and anti-apoptotic properties, which involved the activated form of HO-1.

HO-1/PINK1 Regulated Mitochondrial Fusion/Fission to Inhibit Pyroptosis and Attenuate Septic Acute Kidney Injury

Background

Endotoxin-associated acute kidney injury (AKI), a disease characterized by marked oxidative stress and inflammation disease, is a major cause of mortality in critically ill patients. Mitochondrial fission and pyroptosis often occur in AKI. However, the underlying biological pathways involved in endotoxin AKI remain poorly understood, especially those related to mitochondrial dynamics equilibrium disregulation and pyroptosis. Previous studies suggest that heme oxygenase- (HO-) 1 confers cytoprotection against AKI during endotoxic shock, and PTEN-induced putative kinase 1 (PINK1) takes part in mitochondrial dysfunction. Thus, in this study, we examine the roles of HO-1/PINK1 in maintaining the dynamic process of mitochondrial fusion/fission to inhibit pyroptosis and mitigate acute kidney injury in rats exposed to endotoxin.

Methods

An endotoxin-associated AKI model induced by lipopolysaccharide (LPS) was used in our study. Wild-type (WT) rats and PINK1 knockout (PINK1KO) rats, respectively, were divided into four groups: the control, LPS, Znpp+LPS, and Hemin+LPS groups. Rats were sacrificed 6 h after intraperitoneal injecting LPS to assess renal function, oxidative stress, and inflammation by plasma. Mitochondrial dynamics, morphology, and pyroptosis were evaluated by histological examinations.

Results

In the rats with LPS-induced endotoxemia, the expression of HO-1 and PINK1 were upregulated at both mRNA and protein levels. These rats also exhibited inflammatory response, oxidative stress, mitochondrial fission, pyroptosis, and decreased renal function. After upregulating HO-1 in normal rats, pyroptosis was inhibited; mitochondrial fission and inflammatory response to oxidative stress were decreased; and the renal function was improved. The effects were reversed by adding Znpp (a type of HO-1 inhibitor). Finally, after PINK1 knockout, there is no statistical difference in the LPS-treated group and Hemin or Znpp pretreated group.

Conclusions

HO-1 inhibits inflammation response and oxidative stress and regulates mitochondria fusion/fission to inhibit pyroptosis, which can alleviate endotoxin-induced AKI by PINK1.

Dietary Supplementation With High Fiber Alleviates Oxidative Stress and Inflammatory Responses Caused by Severe Sepsis in Mice Without Altering Microbiome Diversity

In this study, we demonstrated the effects of a high-fiber diet on intestinal lesions, oxidative stress and systemic inflammation in a murine model of endotoxemia. C57BL/6 mice were randomly assigned to four groups: the control group (CONTROL), which received a commercial normal-fiber rodent diet comprising normal fiber; a CLP group, which received a commercial normal-fiber rodent diet and underwent caecal ligation puncture (CLP); a high-fiber group (HFG), which received a commercial high-fiber rodent diet; and a high fiber + CLP group (HFCLP) which received a commercial high-fiber rodent diet and underwent CLP (30%). The sepsis model was created via CLP after 2 weeks of dietary intervention. Notably, dietary high-fiber supplementation in HFCLP group improved survival rates and reduced bacterial loads, compared with CLP alone. In the HFCLP group, dietary fiber supplementation decreased the serum concentrations of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6) and high-mobility group protein 1 (HMG-1) but raised the concentration of interleukin 10 (IL-10), compared with the levels in CLP mice. Meanwhile, high-fiber supplementation increased the relative proportions of Akkermansia and Lachnospiraceae. These data show that dietary high-fiber supplementation may be therapeutic for sepsis-induced lesions.

Activation of protein kinase C-α/heme oxygenase-1 signaling pathway improves mitochondrial dynamics in lipopolysaccharide-activated NR8383 cells

Mitochondrial function and morphology are dynamically regulated by fusion and fission. Heme oxygenase-1 (HO-1), which may be upregulated by protein kinase C-α (PKC-α), improves mitochondrial dynamics by controlling the balance between fusion and fission in vivo and in vitro. However, whether the PKC-α/HO-1 signaling pathway is one of the underlying mechanisms in adjusting mitochondrial dynamics in lipopolysaccharide (LPS)-activated macrophages has remained elusive. To explore this, NR8383 cells were pre-treated with PKC-α inhibitor Go6976 or PKC-α activator phorbol-12-myristate-13-acetate for 30 min and then stimulated with LPS for 24 h. Next, the expression of PKC-α, HO-1, mitofusin 1 (Mfn1) and mitofusin 2 (Mfn2), optic atrophy 1 (OPA1), dynamin-related protein 1 (Drp1) and fission 1 (Fis1) was detected to evaluate the possible implication of the PKC-α/HO-1 signaling pathway in the LPS-induced NR8383 cells. The results indicated that activation of the PKC-α/HO-1 signaling pathway increased superoxide dismutase activities and the respiratory control ratio (RCR), decreased the levels of malondialdehyde, reactive oxygen species (ROS), Drp1 and Fis1, and simultaneously enhanced the levels of Mfn1, Mfn2 and OPA1. In contrast, the PKC-α inhibitor decreased the expression of RCR, Mfn1, Mfn2 and OPA1, and increased the expression of MDA and ROS in NR8383 cells. The results suggest that activation of the PKC-α/HO-1 signaling pathway is necessary for the balance of mitochondrial dynamics and oxidative stress in macrophages, which provides clues for probing novel strategies against the detrimental effects of sepsis and other disease states.

Hydrogen Gas Protects Against Intestinal Injury in Wild Type But Not NRF2 Knockout Mice With Severe Sepsis by Regulating HO-1 and HMGB1 Release

The intestine plays an important role in the pathogenesis of sepsis. Hydrogen gas (H2), which has anti-oxidative, anti-inflammatory, and anti-apoptotic effects, can be effectively used to treat septic mice. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a redox-sensitive master switch that regulates the expression of antioxidant and protective enzymes. This study investigated the effects of 2% H2 on intestinal injuries and the underlying mechanisms in a mouse model of severe sepsis. Male Nrf2 knockout mice (Nrf2-KO) and wild-type (WT) mice were randomized into four groups: sham, sham+H2, cecal ligation and puncture (CLP), and CLP+H2. The survival rate was observed and recorded within 7 days, and pro-inflammatory cytokines (TNF-α, IL-6, HMGB1), anti-inflammatory cytokine (IL-10), antioxidant enzymes (superoxide dismutase, and catalase ), and oxidative products (MDA, 8-iso-PGF2α) were detected in the serum and intestine using an enzyme-linked immunosorbent assay. In addition, the protein and mRNA levels of heme oxygenase-1 (HO-1) and high mobility group box 1 (HMGB1) were measured by Western blotting and quantitative PCR, respectively. Immunofluorescence and immunohistochemistry were used to measure HMGB1 and HO-1 release into the intestine, respectively. The results showed that therapy with 2% H2 increased the survival rate, alleviated the injuries caused by oxidative stress and inflammation, reduced HMGB1 levels but increased HO-1 levels in WT septic mice, but not in Nrf2-KO mice. These data demonstrate that 2% H2 inhalation may be a promising therapeutic strategy for intestinal injuries caused by severe sepsis through the regulation of HO-1 and HMGB1 release. In addition, Nrf2 plays a key role in the protective effects of H2 against intestinal damage in this disease.

Heme Oxygenase-1/Carbon Monoxide-regulated Mitochondrial Dynamic Equilibrium Contributes to the Attenuation of Endotoxin-induced Acute Lung Injury in Rats and in Lipopolysaccharide-activated Macrophages

BACKGROUND

Sepsis-associated acute lung injury remains the major cause of mortality in critically ill patients and is characterized by marked oxidative stress and mitochondrial dysfunction. Mitochondrial dynamics are indispensable for functional integrity. Additionally, heme oxygenase (HO)-1/carbon monoxide conferred cytoprotection against end-organ damage during endotoxic shock. Herein, we tested the hypothesis that HO-1/carbon monoxide played a critical role in maintaining the dynamic process of mitochondrial fusion/fission to mitigate lung injury in Sprague-Dawley rats or RAW 264.7 macrophages exposed to endotoxin.

METHODS

The production of reactive oxygen species, the respiratory control ratio (RCR), and the expressions of HO-1 and mitochondrial dynamic markers were determined in macrophages. Concurrently, alterations in the pathology of lung tissue, lipid peroxidation, and the expressions of the crucial dynamic proteins were detected in rats.

RESULTS

Endotoxin caused a 31% increase in reactive oxygen species and a 41% decrease in RCR levels (n = 5 per group). In parallel, the increased expression of HO-1 was observed in lipopolysaccharide-stimulated macrophages, concomitantly with excessive mitochondrial fission. Furthermore, carbon monoxide-releasing molecule-2 or hemin normalized mitochondrial dynamics, which were abrogated by zinc protoporphyrin IX. Additionally, impaired mitochondrial dynamic balance was shown in Sprague-Dawley rats that received lipopolysaccharide, accompanied by pathologic injury, elevated malondialdehyde contents, decreased manganese superoxide dismutase activities, and lowered RCR levels in rat lung mitochondria. However, the above parameters were augmented by zinc protoporphyrin IX and were in turn reversed by hemin.

CONCLUSIONS

The HO-1/carbon monoxide system modulated the imbalance of the dynamic mitochondrial fusion/fission process evoked by lipopolysaccharide and efficiently ameliorated endotoxin-induced lung injury in vivo and in vitro.

Effect of Heme Oxygenase-1 on Mitofusin-1 protein in LPS-induced ALI/ARDS in rats

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a common and important oxidative stress in the lung. Mitochondrial fusion responds to the normal morphology and function of cells and is finely regulated by mitochondrial fusion proteins, such as mitofusin-1 protein (Mfn1), mitofusin-2 protein (Mfn2) and optical atrophy 1 (OPA1). Additionally, Mfn1 has been identified as the most important protein in mitochondrial fusion. Heme oxygenase-1 (HO-1) is a stress-inducible protein that plays a critical role in protecting against oxidative stress. However, whether the protection of HO-1 is related to mitochondrial fusion is still a question. Thus, our in vitro and in vivo experiments aimed to identify the relationship between HO-1 and Mfn1. Here, we used Hemin and ZnPP-IX as treatments in an in vivo experiment. Then, HO-1 and Mfn1 were measured using RT-PCR and Western blotting. Supernatants were analyzed for MDA, SOD, and ROS. Our results implied that HO-1 upregulation suppressed oxidative stress induced by LPS, and the possible mechanism could be associated with Mfn1 and the PI3K/Akt pathway.

Inflammation and Edema in the Lung and Kidney of Hemorrhagic Shock Rats Are Alleviated by Biliary Tract External Drainage via the Heme Oxygenase-1 Pathway

The lung and kidney are two organs that are easily affected by hemorrhagic shock (HS). We investigated roles of biliary tract external drainage (BTED) in inflammation and edema of the lung and kidney in HS and its relationship with the heme oxygenase-1 (HO-1) pathway. Rat models of HS were induced by drawing blood from the femoral artery until a mean arterial pressure (MAP) of 40 ± 5 mmHg was achieved. A MAP of 40 ± 5 mmHg was maintained for 60 min. Thirty-six Sprague-Dawley rats were randomized to the following groups: sham group; HS group; HS + zinc protoporphyrin IX (ZnPP), a specific HO-1 inhibitor, group; HS + BTED group; HS + BTED + ZnPP group; and HS + BTED + bile infusion (BI) group. HO-1 levels, aquaporin-1 levels, and ratios of dry/wet in the lung and kidney increased markedly after BTED, but tumor necrosis factor-α and myeloperoxidase levels in the lung and kidney decreased significantly after BTED under HS conditions. Under the condition that HO-1 was inhibited by ZnPP, all these effects induced by BTED disappeared in the lung and kidney. These results demonstrated that inflammation and edema of the lung and kidney of HS rats are alleviated by BTED via the HO-1 pathway.

Electroacupuncture Ameliorates Acute Renal Injury in Lipopolysaccharide-Stimulated Rabbits via Induction of HO-1 through the PI3K/Akt/Nrf2 Pathways

Electroacupuncture at select acupoints have been verified to protect against organ dysfunctions during endotoxic shock. And, heme oxygenase (HO)-1 as a phase II enzyme and antioxidant contributed to the protection of kidney in septic shock rats. The phosphatidylinositol 3-kinase (PI3K)-Akt pathway mediated the activation of NF-E2 related factor-2 (Nrf2), which was involved in HO-1 induction. To understand the efficacy of electroacupuncture stimulation in ameliorating acute kidney injury (AKI) through the PI3K/Akt/Nrf2 pathway and subsequent HO-1 upregulation, a dose of LPS 5mg/kg was administered intravenously to replicate the rabbit model of AKI induced by endotoxic shock. Electroacupuncture pretreatment was handled bilaterally at Zusanli and Neiguan acupoints for five consecutive days while sham electroacupuncture at non-acupoints as control. Results displayed that electroacupuncture stimulation significantly alleviated the morphologic renal damage, attenuated renal tubular apoptosis, suppressed the elevated biochemical indicators of AKI caused by LPS, enhanced the expressions of phospho-Akt, HO-1protein, Nrf2 total and nucleoprotein, and highlighted the proportions of Nrf2 nucleoprotein as a parallel. Furthermore, partial protective effects of elecroacupuncture were counteracted by preconditioning with wortmannin (the selective PI3K inhibitor), indicating a direct involvement of PI3K/Akt pathway. Inconsistently, wortmannin pretreatment made little difference to the expressions of HO-1, Nrf2 nucleoprotein and total protein, which indicated that PI3K/Akt may be not the only pathway responsible for electroacupuncture-afforded protection against LPS-induced AKI. These findings provide new insights into the potential future clinical applications of electroacupuncture for AKI induced by endotoxic shock instead of traditional remedies.

Effect of ERK1/2 signaling pathway in electro-acupuncture mediated up-regulation of heme oxygenase-1 in lungs of rabbits with endotoxic shock

Background

The anti-oxidative and anti-inflammatory activities of electro-acupuncture (EA), a traditional clinical method, are widely accepted, but its mechanisms are not yet well defined. In this study, we investigated the role of extracellular signal-regulated kinases1/2 (ERK1/2) pathways on electro-acupuncture – mediated up-regulation of heme oxygenase-1 (HO-1) in rabbit lungs injured by LPS-induced endotoxic shock.

Material/Methods

Seventy rabbits were randomly divided into 7 groups: group C, group M, group D, group SEAM, group EAM, group EAMPD, and group PD98059. Male New England white rabbits were given EA treatment on both sides once a day on days 1–5, and then received LPS to replicate the experimental model of injured lung induced by endotoxic shock. Then, they were killed by exsanguination at 6 h after LPS administration. The blood samples were collected for serum examination, and the lungs were removed for pathology examination, determination of wet-to-dry weight ratio, MDA content, SOD activity, serum tumor necrosis factor-α, determination of HO-1 protein and mRNA expression, and determination of ERK1/2 protein.

Results

The results revealed that after EA treatment, expression of HO-1and ERK1/2 was slightly increased compared to those in other groups, accompanied with less severe lung injury as indicated by lower index of lung injury score, lower wet-to-dry weight ratio, MDA content, and serum tumor necrosis factor-α levels, and greater SOD activity (p<0.05 for all). After pretreatment with ERK1/2 inhibitor PD98059, the effect of EA treatment and expression of HO-1 were suppressed (p<0.05 for all).

Conclusions

After electro-acupuncture stimulation at ST36 and BL13, severe lung injury during endotoxic shock was attenuated. The mechanism may be through up-regulation of HO-1, mediated by the signal transductions of ERK1/2 pathways. Thus, the regulation of ERK1/2 pathways via electro-acupuncture may be a therapeutic strategy for endotoxic shock.

Role of Nrf2/ARE pathway in protective effect of electroacupuncture against endotoxic shock-induced acute lung injury in rabbits

NF-E2 related factor 2 (Nrf2) is a major transcription factor and acts as a key regulator of antioxidant genes to exogenous stimulations. The aim of current study was to determine whether Nrf2/ARE pathway is involved in the protective effect of electroacupuncture on the injured lung in a rabbit model of endotoxic shock. A dose of lipopolysaccharide (LPS) 5 mg/kg was administered intravenously to replicate the model of acute lung injury induced by endotoxic shock. Electroacupuncture pretreatment was handled bilaterally at Zusanli and Feishu acupoints for five consecutive days while sham electroacupuncture punctured at non-acupoints. Fourty anesthetized New England male rabbits were randomized into normal control group (group C), LPS group (group L), electroacupuncture + LPS group (group EL) and sham electroacupuncture + LPS (group SEL). At 6 h after LPS administration, the animals were sacrificed and the blood samples were collected for biochemical measurements. The lungs were removed for calculation of wet-to-dry weight ratios (W/D), histopathologic examination, determination of heme oxygenase (HO)-1 protein and mRNA, Nrf2 total and nucleoprotein, as well as Nrf2 mRNA expression, and evaluation of the intracellular distribution of Nrf2 nucleoprotein. LPS caused extensive morphologic lung damage, which was lessened by electroacupuncture treatment. Besides, lung W/D ratios were significantly decreased, the level of malondialdehyde was inhibited, plasma levels of TNF-α and interleukin-6 were decreased, while the activities of superoxide dismutase, glutathione peroxidase and catalase were enhanced in the electroacupucnture treated animals. In addition, electroacupuncture stimulation distinctly increased the expressions of HO-1 and Nrf2 protein including Nrf2 total protein and nucleoprotein as well as mRNA in lung tissue, while these effects were blunted in the sham electroacupuncture group. We concluded that electroacupuncture treatment at ST36 and BL13 effectively attenuates lung injury in a rabbit model of endotoxic shock through activation of Nrf2/ARE pathway and following up-regulation of HO-1 expression.

Heme oxygenase 1 modulates thrombomodulin and endothelial protein C receptor levels to attenuate septic kidney injury

This study investigated the effects of heme oxygenase 1 (HO-1) on thrombomodulin (TM) and endothelial protein C receptor (EPCR) expression in sepsis-induced kidney injury. The role of HO-1 was evaluated in a cecal ligation and puncture (CLP)-induced model. Wistar rats were randomly assigned into four groups: sham, CLP, CLP + hemin (an HO-1 inducer), CLP + ZnPP (zinc protoporphyrin IX, an HO-1 inhibitor), and CLP + bilirubin. Compared with the sham group, the CLP group exhibited significantly elevated plasma levels of cystatin C, creatinine, urea nitrogen (blood urea nitrogen), tumor necrosis factor α, interleukin 1β, TM, and EPCR; lower plasma level of activated protein C, shorter prothrombin time and activated partial thromboplastin time; significantly increased microthrombus formation; and lower TM and EPCR mRNA and protein expression in the kidney. The administration of hemin lowered the plasma levels of cystatin C, creatinine, blood urea nitrogen, tumor necrosis factor α, interleukin 1β, TM, and EPCR; elevated plasma level of activated protein C; prolonged prothrombin time and activated partial thromboplastin time; attenuated microthrombus formation; and upregulated the expression of TM and EPCR and mRNA levels of TM and EPCR in the kidney in the CLP + hemin group. In contrast, ZnPP had the opposite effects. The results indicated that the enhanced induction of HO-1 increased the expression of TM and EPCR in the kidney and exerted an anticoagulant effect, thereby attenuating kidney injury in septic rats.

Role of HO-1 in protective effect of electro-acupuncture against endotoxin shock-induced acute lung injury in rabbits

Heme oxygenase (HO)-1 has been reported to play a great role in attenuating lung injury during endotoxic shock in our previous research. Although electro-acupuncture has been explored to reduce oxidative stress and decrease inflammatory reaction in animals with endotoxic shock, the mechanism of this effect is still unclear. The aim of this study was to determine whether HO-1 is involved in the effect of electro-acupuncture on the injured lung during endotoxic shock in rabbits. Sixty New England white rabbits were randomly divided into groups C, Z, ES, EA, AP, and EAZ. Before inducing endotoxic shock, group ES received no electro-acupuncture, while group EA received electro-acupuncture at ST36 (zusanli) and BL13 (feishu) acupoints on both sides for five days and group AP received electro-acupuncture (EA) stimulation at a non-acupoint. Groups ES, AP, EA, and EAZ received LPS to replicate the experimental model of injured lung induced by endotoxic shock, and electro-acupuncture was performed throughout the procedure with the same parameter. Groups EAZ and Z received the HO-1 inhibitor, ZnPP-IX, intraperitoneally. The animals were sacrificed by blood-letting at 6 h after LPS administration. The blood samples were collected for serum examination, and the lungs were removed for pathology examination, detection of alveolaer epithelial cell apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay (TUNEL assay), determination of wet to dry ratio, measurement of Evans blue (EB) contents, and determination of HO-1protein and mRNA expression. According to the results, EA at ST36 and BL13 could increase the expression of HO-1. At the same time, index of quantitative assessment (IQA) score and the number of TUNEL-positive cells decreased, while electro-acupuncture at the other points did not exert this effect, and pretreatment with ZnPP-IX in group EAZ suppressed the efficacy of electro-acupuncture preconditioning. In summary, electro-acupuncture stimulation at ST36 and BL13, while not the non-acupoint, could attenuate the lung injury during the endotoxic shock, and this effect was due to increased expression of HO-1.

Enhanced induction of heme oxygenase-1 suppresses thrombus formation and affects the protein C system in sepsis

Heme oxygenase-1 (HO-1) displays anti-inflammatory and cytoprotective activities in sepsis. Here, we investigated the effects of HO-1 on thrombus formation and the protein C system in a septic C57BL/6 mouse model induced by cecal ligation and perforation (CLP). Septic mice were either preinjected with the vehicle, pretreated with hemin (an HO-1 inducer) or zinc protoporphyrin IX (ZnPP, an HO-1 inhibitor), or given a combination of hemin + ZnPP. CLP increased significantly the hepatic expression of HO-1; increased thrombosis in livers, kidneys, and lungs; shortened the prothrombin time (PT) and activated partial thromboplastin time (APTT); elevated the levels of tumor necrosis factor-1α (TNF-1α), interleukin-6 (IL-6), and thrombomodulin (TM); reduced the levels of protein C (PC) and activated protein C (aPC); and downregulated hepatic expression of PC and TM. The preadministration of hemin to septic mice increased the expression and activity of HO-1; inhibited thrombosis in the preceding 3 organs; prolonged PT and APTT; inhibited the production of TNF-α and IL-6; upregulated the expression of PC and TM in livers; elevated the plasma levels of PC and aPC; and reduced the plasma levels of TM. In contrast, ZnPP showed opposite effects to hemin and reversed the effects of hemin by inhibiting the activity of HO-1. The administration of tricarbonyl dichloro ruthenium (II) dimer (CORM-2), which is a CO-releasing molecule, had a similar effect to hemin on thrombosis and the protein C system. The data indicate that the enhanced induction of HO-1 inhibits thrombus formation and affects the protein C system in sepsis.