Upregulation of heme oxygenase-1 with hemin prevents D-galactosamine and lipopolysaccharide-induced acute hepatic injury in rats

Immune and inflammatory mechanism of remote ischemic conditioning: A narrative review

The benefits of remote ischemic conditioning (RIC) on multiple organs have been extensively investigated. According to existing research, suppressing the immune inflammatory response is an essential mechanism of RIC. Based on the extensive effects of RIC on cardiovascular and cerebrovascular diseases, this article reviews the immune and inflammatory mechanisms of RIC and summarizes the effects of RIC on immunity and inflammation from three perspectives: (1) the mechanisms of the impact of RIC on inflammation and immunity; (2) evidence of the effects of RIC on immune and inflammatory processes in ischaemic stroke; and (3) possible future applications of this effect, especially in systemic infectious diseases such as sepsis and sepsis-associated encephalopathy. This review explores the possibility of using RIC as a treatment in more inflammation-related diseases, which will provide new ideas for the treatment of this kind of disease.

The IL-6/HO-1/STAT3 signaling pathway is implicated in the amelioration of acetaminophen-induced hepatic toxicity: A neonatal rat model

The widespread use of acetaminophen (APAP) in children as an over-the-counter treatment can cause acute liver failure through accidental overdose or ingestion. Therefore, the current research sought to investigate the function of hemin in mitigating the acute hepatotoxic effect of APAP in rat offspring. Thirty-two rats were assigned into four groups: control, hemin, APAP, and hemin/APAP groups. Liver enzymes were measured in serum along with oxidative stress indicators, tumor necrosis factor-α (TNF-α), interleukin-1beta (IL-1β), total nitrites (NOx), and caspase 3 in liver. Immunoblotting of heme oxygenase-1 (HO-1), interleukin-6 (IL-6), Janus kinase 2 (Jak2), and signal transducer and activator of transcription 3 (STAT3) was carried out. The Bax/Bcl2 mRNA expression ratio was determined. A histological study and an immunohistochemical study of phosphorylated STAT3 were also done. Hemin reduced liver enzymes, MDA, TNF-α, NOx, caspase 3, IL-1β, p-STAT3 expression, p-Jak2 expression, IL-6 expression, and Bax/Bcl2 mRNA expression ratio. In contrast, hemin increased GSH, TAC, and the expression of HO-1, improving the histopathological picture of liver tissue. Thus, hemin could ameliorate APAP-induced hepatic toxicity in rat offspring through anti-oxidant, anti-apoptotic, and anti-inflammatory actions with a possible role for the IL-6/HO-1/Jak2/STAT3 pathway.

Rosuvastatin Induces Renal HO-1 Activity and Expression Levels as a Main Protective Mechanism against STZ-Induced Diabetic Nephropathy

Background and Objectives: Nephroprotective effect of statins is still controversial. The aim of this study was to investigate the possible hemin-like nephroprotective effect of rosuvastatin (RSV) in streptozotocin (STZ)-induced diabetic rats. Materials and Methods: DN was induced in rats via a single dose of 50 mg/kg STZ i.p., with or without RSV (10 mg/kg orally) for 30 days. To investigate hemin-like effect of RSV on renal heme oxygenase-1 (HO-1), RSV was administered in the presence or absence of an inhibitor of HO-1; zinc protoporphyrin-XI (ZnPP), in a dose of 50 µmol/kg i.p. Results: Induction of diabetes with STZ caused, as expected, significant hyperglycemia, as well as deteriorated kidney function, lipid profile and histopathological architecture. The DN group also showed renal oxidative stress, indicated by decreased superoxide dismutase, catalase, and reduced glutathione, with increased malondialdehyde, myeloperoxidase and nitric oxide. Renal expression of inflammatory marker TNF-α, and pro-apoptotic marker caspase 3, were also increased in the DN group. Administration of RSV in DN rats did not improve glucose level but succeeded in recovering kidney function and normal structure as well as improving the lipid profile. RSV also improved renal oxidative, inflammatory, and apoptotic statuses. Interestingly, the administration of RSV increased renal expression and activity of HO-1 compared to the untreated DN group. Co-administration of ZnPP blocked the effect of RSV on HO-1 and deteriorated all RSV favorable effects. Conclusions: RSV can protect against DN, at least in part, via increasing renal HO-1 expression and/or activity, which seems to be upstream to RSV antioxidant, anti-inflammatory, and anti-apoptotic effects.

Sinapic acid ameliorates D-galactosamine/lipopolysaccharide-induced fulminant hepatitis in rats: Role of nuclear factor erythroid-related factor 2/heme oxygenase-1 pathways

BACKGROUND

Sinapic acid (SA) has been shown to have various pharmacological properties such as antioxidant, antifibrotic, anti-inflammatory, and anticancer activities. Its mechanism of action is dependent upon its ability to curb free radical production and protect against oxidative stress-induced tissue injuries.

AIM

To study the hepatoprotective effects of SA against lipopolysaccharide (LPS)/D-galactosamine (D-GalN)-induced acute liver failure (ALF) in rats.

METHODS

Experimental ALF was induced with an intraperitoneal (i.p.) administration of 8 μg LPS and 800 mg/kg D-GalN in normal saline. SA was administered orally once daily starting 7 d before LPS/D-GalN treatment.

RESULTS

Data showed that SA ameliorates acute liver dysfunction, decreases serum levels of alanine transaminase (ALT), and aspartate aminotransferase (AST), as well as malondialdehyde (MDA) and NO levels in ALF model rats. However, pretreatment with SA (20 mg/kg and 40 mg/kg) reduced nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation and levels of inflammatory cytokines (tumor necrosis factor-α and interleukin 6). Also, SA increased the activity of the nuclear factor erythroid-related factor 2/heme oxygenase-1 (Nrf2/HO-1) signaling pathway.

CONCLUSION

In conclusion, SA offers significant protection against LPS/D-GalN-induced ALF in rats by upregulating Nrf2/HO-1 and downregulating NF-κB.

Luzindole attenuates LPS/d-galactosamine-induced acute hepatitis in mice

Melatonin is a well-documented hormone that plays central roles in the regulation of sleep–wake cycles. There is cumulative evidence to suggest that melatonin is also a pleiotropic regulator of inflammation, and luzindole has been widely used as a melatonin receptor antagonist. This study investigated the potential effects of luzindole on LPS/d-galactosamine (d-GalN)-induced acute hepatitis. The results indicated that treatment with luzindole alleviated histological damage in the liver, reduced the level of transaminases in plasma and improved the survival of LPS/d-GalN-exposed mice. Treatment with luzindole also suppressed the production of the pro-inflammatory cytokines TNF-α and IL-6 in LPS/d-GalN-exposed mice. In addition, treatment with luzindole inhibited the activation of caspase-3, -8 and -9, and suppressed the cleavage of caspase-3 and poly(ADP-ribose) polymerase. Therefore, treatment with luzindole attenuates LPS/d-GalN-induced acute liver injury, suggesting that luzindole might have potential value for the intervention of inflammation-based hepatic disorders.

Helenalin from Centipeda minima ameliorates acute hepatic injury by protecting mitochondria function, activating Nrf2 pathway and inhibiting NF-κB activation

Acute liver injury is a life-threatening syndrome that often caused by hepatocyte damage and is characterized by inflammatory and oxidative responses. Helenalin isolated from Centipeda minima (HCM) has been found to have anti-inflammatory and anti-oxidative effects. Here, this study aimed to investigate the effects and underlying mechanisms of HCM on Lipopolysaccharide/D-Galactosamine (LPS/D-GalN)-induced acute liver injury. Mice were intragastrically administered with various dose of HCM for 10 days; 2 h after the final treatment, the mice were injected with 50 μg/kg LPS and 800 mg/kg D-GalN. The histopathological changes, hepatocyte apoptosis, serum cytokines, oxidative stress and inflammatory cytokines were assessed. The results showed that HCM significantly ameliorated the hepatic injury, as evidenced by the attenuation of histopathological changes and the decrease in serum aminotransferase and total bilirubin activities. HCM markedly decreased hepatocyte apoptosis by modulating the mitochondria-dependent pathway, including the increase in the Bcl-2/Bax ratio, the inhibition of caspase-3, -8 and -9, and the inhibition of cytochrome C release. Moreover, HCM strongly alleviated oxidative stress, lipid peroxidation and reactive oxygen species (ROS) generation by activating the Nrf2 signaling pathway. In addition, HCM significantly attenuated inflammatory cytokines including TNF-α, IL6 and IL-1β as well as NO production by inhibiting TLR4 signaling transduction and NF-κB activation. In conclusion, HCM protects hepatocytes from damage induced by LPS/D-GalN, which may contribute to its ability to alleviate hepatocyte apoptosis by protecting the mitochondrial function, inhibit oxidative stress by activating the Nrf2 pathway, and attenuate inflammation by inhibiting NF-κB activation. This study demonstrates that HCM may be developed as a potential agent for the treatment of acute liver failure.

Madecassoside ameliorates lipopolysaccharide-induced neurotoxicity in rats by activating the Nrf2-HO-1 pathway

Neuroinflammation is a predisposing factor for several neurodegenerative diseases. The purpose of this study was to evaluate the protective effect of madecassoside (MA) in lipopolysaccharide (LPS)-induced cognitive impairment and neuroinflammation in rats. MA has many protective effects such as antioxidant and anti-inflammatory properties. We investigated whether MA could improve neurocognitive dysfunction caused by intracerebroventricular injection of LPS. We examined the effects and mechanisms of action of MA on LPS-induced neuroinflammation in the cortex and hippocampus. Our study revealed that MA (120 mg/kg, i.g) treatment for 14 days reduced LPS-induced neurotoxicity by reducing cognitive impairments and suppressing the production of inflammatory cytokines such as interleukin 1 beta (IL-1β), tumor necrosis factor alpha(TNF-α), and interleukin 6(IL-6) via activation of nuclear factor erythroid 2-related factor 2 (Nrf2) signaling. Furthermore, MA treatment enhanced protein levels of heme oxygenase (HO)-1 by upregulating Nrf2 in LPS-stimulated neurotoxicity. Collectively, these results suggest that MA is effective in preventing neurodegenerative diseases by improving memory functions due to its anti-inflammatory activities and activation of Keap1-Nrf2/HO-1 signaling. As such, MA may be a potential therapy for addressing memory impairment caused by neuroinflammation.

Kynurenic Acid Protects against Thioacetamide-Induced Liver Injury in Rats

Acute liver failure (ALF) is a life-threatening disorder of liver function. Kynurenic acid (KYNA), a tryptophan metabolite formed along the kynurenine metabolic pathway, possesses anti-inflammatory and antioxidant properties. Its presence in food and its potential role in the digestive system was recently reported. The aim of this study was to define the effect of KYNA on liver failure. The Wistar rat model of thioacetamide-induced liver injury was used. Morphological and biochemical analyses as well as the measurement of KYNA content in liver and hepatoprotective herbal remedies were conducted. The significant attenuation of morphological disturbances and aspartate and alanine transaminase activities, decrease of myeloperoxidase and tumor necrosis factor-α, and elevation of interleukin-10 levels indicating the protective effect of KYNA in thioacetamide (TAA) - induced liver injury were discovered. In conclusion, the hepatoprotective role of KYNA in an animal model of liver failure was documented and the use of KYNA in the treatment of ALF was suggested.

Dendritic cells with increased expression of suppressor of cytokine signaling 1(SOCS1) gene ameliorate lipopolysaccharide/d-galactosamine-induced acute liver failure

Acute liver failure is a devastating clinical syndrome with extremely terrible inflammation reaction, which is still lack of effective treatment in clinic. Suppressor of Cytokine Signaling 1 protein is inducible intracellular negative regulator of Janus kinases (JAK)/signal transducers and activators of transcription (STAT) pathway that plays essential role in inhibiting excessive intracellular signaling cascade and preventing autoimmune reaction. In this paper, we want to explore whether dendritic cells (DCs) with overexpression of SOCS1 have a therapeutic effect on experimental acute liver failure. Bone marrow derived dendritic cells were transfected with lentivirus encoding SOCS1 and negative control lentivirus, thereafter collected for costimulatory molecules analysis, allogeneic Mixed Lymphocyte Reaction and Western blot test of JAK/STAT pathway. C57BL/6 mice were randomly separated into normal control and treatment groups which respectively received tail vein injection of modified DCs, negative control DCs and normal saline 12 h earlier than acute liver failure induction. Our results indicated that DCs with overexpression of SOCS1 exhibited like regulatory DCs (DCregs) with low level of costimulatory molecules and poor allostimulatory ability in vitro, which was supposed to correlate with block of JAK2/STAT1 signaling. In vivo tests, we found that infusion of modified DCs increased survival rate of acute liver failure mice and alleviate liver injury via inhibition of TLR4/HMGB1 pathway. We concluded that DCs transduced with SOCS1 gene exhibit as DCregs through negative regulation of JAK2/STAT1 pathway and ameliorated lipopolysaccharide/d-galactosamine induced acute liver failure via inhibition of TLR4 pathway.

Madecassoside prevents acute liver failure in LPS/D-GalN-induced mice by inhibiting p38/NF-κB and activating Nrf2/HO-1 signaling

Madecassoside (MA), a triterpenoid saponin isolated from Centella asiatica, exerts various pharmacological activities including antioxidative and anti-inflammatory effects. The aim of this study was to explore the protective effect of MA in the treatment of lipopolysaccharide (LPS) and D-galactosamine (D-GalN)-induced acute liver failure(ALF) in mice. We hypothesized that MA administration may decrease the degree of liver injury caused by LPS/D-GalN. In this study, we investigated this hypothesis by treating a mouse model of LPS/D-GalN-induced liver injury with MA. Our study demonstrated that MA (20 mg/kg and 40 mg/kg) treatment for 10 days attenuated LPS/D-GalN-induced liver injury by protecting liver function, suppressing the production of inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6, and recovering antioxidant enzyme activity. MA also significantly suppressed LPS-stimulated protein levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 by blocking the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and eukaryotic transcription factor nuclear factor-kappa B (NF-κB). In addition, MA treatment enhanced protein levels of heme oxygenase (HO)-1 and anti-oxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase) through the upregulation of nuclear factor E2-related factor 2 (Nrf2) in LPS-stimulated liver injury. These results suggest that MA is a promising agent for the treatment of LPS/D-GalN-induced liver injury that could serve as a candidate for the development of a hepatoprotective drug against ALF.

Detoxifying effect of pyridoxine on acetaminophen-induced hepatotoxicity via suppressing oxidative stress injury

The detoxifying effect of pyridoxine against acetaminophen (APAP)-induced hepatotoxicity was investigated. HepG2 cells were co-treated with APAP and pyridoxine to compare with betaine or methionine for 24 h. LDH, ALT and AST activities were measured to determine direct cells damage in vitro and in vivo. Lipid peroxidation, antioxidant enzymes activity, and glutathione level were measured. Cytochrome c releaseand procaspase-3, cleaved caspase-3, Bcl-2, or Bax protein levels were measured to determine APAP-induced apoptotic cell death. Pyridoxine treatment significantly increased cell viability and decreased leakage of LDH activity against APAP-induced hepatotoxicity in HepG2 cells. ALT and AST activities were dose-dependently reduced by pyridoxine treatment compared to APAP-treated group. Significant increases in activities of GST and GPx were observed after co-treatment with APAP and pyridoxine. Although APAP-induced Nrf2 and HO-1 expression levels were gradually reduced in HepG2 cells by pyridoxine treatment, induction of antioxidant enzymes activities were dose-dependently increased. These protected effects of pyridoxine against APAP-induced hepatoxicity were closely associated with suppression of APAP-induced oxidative stress and apoptotic cell death in HepG2 cells. These data indicated that the protective action of pyridoxine against hepatic cell injuries was involved in the direct antioxidant activity which provides a pivotal mechanism for its potential hepatoprotective action.

Preadministration of Hydrogen-Rich Water Protects Against Lipopolysaccharide-Induced Sepsis and Attenuates Liver Injury

Despite significant advances in antibiotic therapy and intensive care, sepsis remains the most common cause of death in intensive care units. We previously reported that molecular hydrogen (H2) acts as a therapeutic and preventive antioxidant. Here, we show that preadministration of H2-dissolved water (HW) suppresses lipopolysaccharide (LPS)-induced endotoxin shock in mice. Drinking HW for 3 days before LPS injection prolonged survival in a mouse model of sepsis. The H2 concentration immediately increased in the liver but not in the kidney after drinking HW. The protective effects of the preadministration of HW on LPS-induced liver injury were examined. Twenty-four hours after LPS injection, preadministration of HW reduced the increase in both apoptosis and oxidative stress. Moreover, preadministration of HW enhanced LPS-induced expression of heme oxyganase-1 and reduced endothelin-1 expression. These results indicate the therapeutic potential of HW in preventing acute injury of the liver with attenuation of an increase in oxidative stress. HW is likely to trigger adaptive responses against oxidative stress.

A Phenolic Acid and Flavonoid Fraction Isolated from Lolium multiflorum Lam. Prevents d-Galactosamine-Induced Liver Damages through the Augmentation of Nrf2 Expression

The aims of this study were to explore whether a phenolic acid and flavonoid fraction (named PAFF) isolated from Lolium multiflorum Lam. protects against d-galactosamine (GalN)-induced liver damages in mice and to investigate the associated mechanisms. ICR mice received oral administration with various concentrations (50, 100, and 200 mg/kg body weight) of PAFF once per 2 days for seven times before intraperitoneal injection with 800 mg/kg GalN. After a day of GalN challenge, blood and tissue samples were analyzed by biochemical, histopathological, real time RT-PCR, and Western blot methods. GalN challenge induced severe damage to hepatocytes with hepatocellular vacuolization and necrosis. GalN treatment increased serum ALT, ALP, AST, and LDH levels and hepatic MDA levels and stimulated mRNA and protein expressions of Nrf2 and HO-1 in the liver. GalN treatment also diminished the levels of GSH and the activities of CAT, SOD, and GPx in the liver. However, combined treatment with PAFF inhibited GalN-mediated increases in the histological damages and the levels of serum enzymes and hepatic MDA, restored the activities of hepatic antioxidant enzymes up to those in the control values, and augmented the GalN-stimulated expression of Nrf2 and HO-1 in the liver. Furthermore, PAFF treatment alone increased the cellular SOD activity and the expression of Nrf2 and HO-1 in the liver. Our results suggest that PAFF may protect against GalN-induced liver damage by decreasing oxidative stress and increasing cellular antioxidant activities through an activation of Nrf2/HO-1-dependent pathway.

Modulation of heme oxygenase-1 expression and activity affects streptozotocin-induced diabetic nephropathy in rats

Heme oxygenase (HO)-1 has exhibited nephro-protective actions in different animal models; however, its full mechanistic potential in diabetic nephropathy (DN) has not yet been elucidated. Hence, the present study has been undertaken by inducing DN in rats using streptozotocin (50 mg/kg i.p.), with or without either HO-1 inducer; hemin (HM; 40 μmol/kg, s.c.), or HO-1 blocker; zinc protoporphyrin-IX (ZnPP; 50 μmol/kg, i.p.), for one month. Compared to control, rats with DN suffered from hyperglycemia and hyperlipidemia, with signs of renal damage, as assessed by distortion in renal histopathologic architecture and kidney function. Renal oxidative/nitrosative stress was evident by increased malondialdehyde, nitric oxide, myeloperoxidase, with decreased reduced glutathione, superoxide dismutase, and catalase. DN group also exhibited high renal expression of the pro-inflammatory cytokine; tumor necrosis factor (TNF)-α, and the apoptotic marker; caspase 3, assessed by Western blot. Renal HO-1 protein expression and activity were increased in DN rats compared to control. Administration of HM, but not ZnPP, to DN rats improved kidney function, histopathologic features, lipid profile, TNF-α, and caspase 3 expressions, with no effect on blood glucose level. HM increased, while ZnPP decreased renal HO-1 activity in DN rats. It is noteworthy that neither intervention affected HO-1 activity or renal oxidative capacity in non-diabetic rats. Interestingly, the expression of HO-1 was upregulated by both HM and ZnPP in DN rats. In conclusion, activation of HO-1 via HM ameliorated renal damage in STZ-induced DN in rats, probably through antioxidant, anti-nitrosative, anti-inflammatory, and anti-apoptotic mechanisms.

Hemin protects against oxygen-glucose deprivation-induced apoptosis activation via neuroglobin in SH-SY5Y cells

This study aimed to investigate the mechanism underlying the neuroprotective effect of hemin in oxygen-glucose deprivation (OGD)-treated neurons. OGD-treated SH-SY5Y cells (human neuroblastoma cells) were used in the study. The cellular viability of SH-SY5Y cells was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and the cell apoptosis rate was determined by flow cytometry analysis with Annexin V-fluorescein isothiocyanate and propidium iodide staining with or without hemin pretreatment. Cell viability and apoptotic activation were detected after hemin administration combined with neuroglobin (Nqb), thioredoxin-1, peroxiredoxin-2, or heme oxygenase-1 siRNA transient transfection. The release of cytochrome c from mitochondria and the interaction between Ngb and cytochrome c were examined with hemin pretreatment. Hemin had a neuroprotective effect in OGD-treated SH-SY5Y cells, which was mainly mediated by the upregulation of Ngb. Moreover, the release of cytochrome c from mitochondria was inhibited by hemin-induced Ngb expression through facilitating the interaction of Ngb with cytochrome c in mitochondria. The present findings provided new insights into the neuroprotective mechanisms of hemin. It was concluded that low-dose hemin pretreatment had a neuroprotective effect in OGD-treated SH-SY5Y cells, through inhibiting cell apoptosis. The neuroprotective effects of hemin following hypoxic-ischemic neuronal damage were mainly mediated by Ngb. One underlying mechanism was hemin-induced overexpression of mitochondrial Ngb, which inhibited endogenous apoptosis via the association with cytochrome c.

Ratiometric Two-Photon Fluorescent Probe for in Vivo Hydrogen Polysulfides Detection and Imaging during Lipopolysaccharide-Induced Acute Organs Injury

Acute organ injury observed during sepsis, caused by an uncontrolled release of inflammatory mediators, such as lipopolysaccharide (LPS), is quite fatal. The development of efficient methods for early diagnosis of sepsis and LPS-induced acute organ injury in living systems is of great biomedical importance. In living systems, cystathionine γ-lyase (CSE) can be overexpressed due to LPS, and H₂S_n can be formed by CSE-mediated cysteine metabolism. Thus, acute organ injury during sepsis may be correlated with H₂S_n levels, making accurate detection of H₂S_n in living systems of great physiological and pathological significance. In this work, our previously reported fluorescent platform was employed to design and synthesize a FRET-based ratiometric two-photon (TP) fluorescent probe TPR-S, producing a large emission shift in the presence of H₂S_n. In this work, a naphthalene derivative two-photon fluorophore was chosen as the energy donor; a rhodol derivative fluorophore served as the acceptor. The 2-fluoro-5-nitrobenzoate group of probe TPR-S reacted with H₂S_n and was selectively removed to release the fluorophore, resulting in a fluorescent signal decrease at 448 nm and enhancement at 541 nm. The ratio value of the fluorescence intensity between 541 and 448 nm (I_541 nm/I_448 nm) varied from 0.13 to 8.12 (∼62-fold), with the H₂S_n concentration changing from 0 to 1 mM. The detection limit of the probe was 0.7 μM. Moreover, the probe was applied for imaging H₂S_n in living cells, tissues, and organs of LPS-induced acute organ injury, which demonstrated its practical application in complex biosystems as a potential method to achieve early diagnosis of LPS-induced acute organ injury.

Pyropia yezoensis glycoprotein regulates antioxidant status and prevents hepatotoxicity in a rat model of D-galactosamine/lipopolysaccharide-induced acute liver failure

The present study aimed to investigate the effects of Pyropia yezoensis glycoprotein (PYGP) on hepatic antioxidative enzyme activity and mitogen-activated protein kinase (MAPK) phosphorylation in a rat model of D-galactosamine/lipopolysaccharide (D-GalN/LPS)-induced hepatotoxicity. Glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) were measured to determine the severity of hepatotoxicity. Treatment with D‑GalN/LPS significantly increased the GOT, GPT and lipid peroxidation levels, and decreased the antioxidant capacity of the rats. Treatment with PYGP (150 and 300 mg/kg/body weight) decreased the levels of GOT, GPT and lipid peroxidation levels. The activities of antioxidative enzymes, including catalase, glutathione S‑transferase and glutathione were upregulated following PYGP treatment. Furthermore, D‑GalN/LPS‑induced MAPK phosphorylation, and inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expression were downregulated by PYGP. These results indicated that PYGP may exert hepatoprotective effects via the upregulation of antioxidative enzymes, and the downregulation of the MAPK signaling pathway and iNOS and COX-2 expression.

Enhanced expression of glucose-regulated protein 78 correlates with malondialdehyde levels during the formation of liver cirrhosis in rats

The aim of the present study was to explore the role of glucose-regulated protein 78 (GRP78) in the development of liver cirrhosis promoted by intestinal endotoxemia in rats. Fifty-one male Wistar rats were randomly divided into the liver cirrhosis 4-week, 6-week and 8-week groups and the normal control group at each time point. Liver cirrhosis was induced by employing multiple pathogenic factors in the rats. Blood and liver tissues were collected. The levels of alanine aminotransferase (ALT), homocysteine, endotoxin and tumor necrosis factor-α (TNF-α) in the plasma, and TNF-α, malondialdehyde (MDA) and procollagen type III peptide (PIIIP) in the liver tissues were determined. The mRNA and protein expression levels of GRP78 in the liver were detected using reverse transcription-quantitative polymerase chain reaction and immunohistochemistry. Morphological changes were observed through hematoxylin and eosin and van Gieson staining of the liver. Liver cirrhosis caused marked histopathological changes to the livers of the rats. Following significant increases in the levels of ALT, homocysteine, endotoxin and TNF-α in the plasma, and TNF-α, MDA and PIIIP in the liver tissues of all experimental groups with the progression of liver cirrhosis, the mRNA and protein expression levels of GRP78 also gradually increased. In addition, correlation analysis indicated that the enhanced expression of GRP78 correlated with the MDA levels of the rats during the formation of liver cirrhosis.

Spiranthes sinensis Suppresses Production of Pro-Inflammatory Mediators by Down-Regulating the NF-κB Signaling Pathway and Up-Regulating HO-1/Nrf2 Anti-Oxidant Protein

Spiranthes sinensis is an east Asian wild orchid used in Chinese folk medicine. In this study, an ethyl acetate fraction from S. sinensis(SSE) was found to suppress the production of LPS-stimulated inflammatory mediators in RAW264.7 cells and BALB/c mice. SSE inhibited the production of pro-inflammatory mediators such as nitric oxide (NO), prostaglandin E2 (PGE2), tumo necrosis factor-α (TNF-α), IL-1β, and IL-6 in LPS-stimulated RAW264.7 cells. SSE also significantly suppressed LPS-stimulated protein levels of iNOS and mPGES-1 by blocking IκB phosphorylation, NF-κB nuclear translocation, and MAPKs phosphorylation. In addition, SSE treatment also enhanced protein levels of HO-1 and anti-oxidant enzymes (SOD-1, CAT, and GPx-1) through the nuclear translocation of Nrf2 in LPS-stimulated RAW264.7 cells. In vivo, we demonstrated that SSE attenuated the levels of pro-inflammatory mediators (NO, TNF-α, IL-1β, and IL-6), ALT, and AST in the serum of LPS-stimulated BALB/c mice. Western blotting revealed that SSE enhanced HO-1 expression in lung and liver tissue after LPS injection in mice. These results suggest that the anti-inflammatory properties of SSE involve the suppression of iNOS, mPGES-1, and inflammatory mediators by inducing the HO-1 pathway in LPS-stimulated RAW264.7 cells and BALB/c mice.

The effects of pentoxifylline and caffeic acid phenethyl ester in the treatment of d-galactosamine-induced acute hepatitis in rats

The aim of this study was to investigate histological changes in hepatic tissue and effects of pentoxifylline (PTX) and caffeic acid phenethyl ester (CAPE) on these changes using histochemical and biochemical methods in rats, in which hepatitis was established by D-galactosamine (D-GAL). Rats were divided into five groups as follows: control group, D-GAL (24 h) group, D-GAL group, d-GAL + PTX group, and D-GAL + CAPE group. In histological evaluations, the control group showed normal appearance of the liver cells. However in the d-GAL groups, focal areas consisting of inflammatory, necrotic, and apoptotic cells were detected in parenchyma. Glycogen loss was observed in the hepatocytes localized at the periphery of lobule. It was found that number of mast cells of portal areas were significantly higher in D-GAL groups compared with other groups (p = 0.0001). In addition, the number of cells with positive staining by Ki-67 and caspase-3 were significantly increased in GAL groups compared with the control group (p = 0.0001). In biochemical analysis, there was an increase in malondialdehyde and myeloperoxidase levels, while a decrease was observed in glutathione level and glutathione peroxidase activity in groups treated with d-GAL compared with the control group. On the other hand, it was seen that, in the groups treated with D-GAL, histological and biochemical injuries in the liver were reduced by administration of PTX and CAPE. In this study, we demonstrated the ameliorative effects of PTX and CAPE on D-GAL-induced liver injury.

Dynamic correlation between induction of the expression of heme oxygenase-1 and hepatitis B viral replication

Heme oxygenase‑1 (HO‑1) possesses significant potential as a drug target for hepatitis B, which may be transferable to patient therapy. The aim of the present study was to clarify the dynamic correlation between the hepatitis B virus (HBV) and HO‑1. The levels of HBV replication and expression of HO‑1 were investigated in HepG2.2.15 hepatoma cells following exposure to 5‑50 µM hemin for 1‑6 days. The mRNA expression levels of HO‑1 were then detected using reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). HBV replication levels were determined by enzyme‑immunoassay and a PCR‑fluorescence quantitation assay. The results of the present study demonstrated that the mRNA expression levels of HO‑1 increased in a dose‑dependent manner in the HepG2.2.15 cells, following exposure to 5‑50 µM hemin. The mRNA expression levels of HO‑1 reached a peak following exposure of the cells to hemin for three days, subsequently the expression of HO‑1 decreased. Following exposure to hemin at an optimal concentration of 50 µM for 1‑6 days, the levels of the hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) in the cells were significantly reduced. This marked reduction in the expression of HBsAg and HBeAg reached its peak on the first day, following which the inhibition weakened as the duration of exposure increased. In addition, the inhibition of HBV DNA replication increased with the a longer duration of exposure. Furthermore, HBV DNA levels were significantly decreased following exposure to hemin for 3‑6 days. In conclusion, the present study demonstrated that induced expression of HO‑1 interfered with HBV replication in a dose and time‑dependent manner, implying that a reduction of the HBV viral load may contribute to upregulation in the expression of HO‑1.

Sulforaphane increases the survival rate in rats with fulminant hepatic failure induced by D-galactosamine and lipopolysaccharide

Fulminant hepatic failure (FHF) is a life-threatening clinical syndrome, with liver transplantation being the only effective therapy. Sulforaphane (SFN) is a natural compound that is extracted from cruciferous vegetables and possesses potent anti-inflammatory, antioxidant, and anticancer activities. This study was designed to test the hypothesis that SFN (3 mg/kg) may protect against FHF induced in rats by administering a combination of D-galactosamine (GalN; 300 mg/kg) and lipopolysaccharide (LPS; 30 μg/kg). The rats were given a single intraperitoneal injection of SFN, 1 hour before the FHF induction. Sulforaphane reduced the mortality and alleviated the pathological liver injury. In addition, SFN significantly reduced the increase in serum aminotransferase activities and lipid peroxidation. The glutathione content decreased in the GalN/LPS group, and this decrease was attenuated by SFN. Increases in serum tumor necrosis factor α, interleukin-6, and interleukin-10, which were observed in GalN/LPS-treated rats, were significantly reduced after using SFN. The GalN/LPS treatment increased the expression of superoxide dismutase-1, glutathione peroxidase 2, catalase, and heme oxygenase-1 genes. Sulforaphane inhibited the induction of reactive oxygen species scavenging proteins. Moreover, SFN inhibited GalN/LPS-induced caspase-3 activation and suppressed FAS and FASL expression. These findings suggest that SFN alleviates GalN/LPS-induced liver injury, possibly by exerting antioxidant, anti-inflammatory, and antiapoptotic effects and modulating certain antioxidant defense enzymes.

Potential role of catalase in mice with lipopolysaccharide/D-galactosamine-induced fulminant liver injury

AIM

Lipopolysaccharide (LPS)-induced liver injury in D-galactosamine (D-Gal)-sensitized mice is a well-established animal model widely used in exploring the pathogenesis of fulminant hepatitis. Increasing evidence has indicated that reactive oxygen species (ROS)-induced oxidative injury may be involved in LPS/D-Gal-induced hepatitis. Catalase (CAT) is a major antioxidant enzyme while aminotriazole (ATZ) is commonly used as a CAT inhibitor. In the present study, the effects of ATZ on LPS/D-Gal-induced liver injury were investigated.

METHODS

Fuliminant liver injury was induced by intraperitoneal injection of LPS combined with D-Gal, ATZ was administrated 0.5 h prior to LPS/D-Gal challenge. The degree of liver injury, the level of hepatic oxidative stress, the grade of hepatic apoptosis and the survival of experimental animals were determined.

RESULTS

Our experimental data showed that treatment with ATZ significantly enhanced LPS/D-Gal-induced elevation of serum aspartate transaminase (AST) and alanine transaminase (ALT), exacerbated the hepatic histopathological abnormality and decreased the survival rate of experimental animals. ATZ inhibited the activity of CAT, increased the content of H2 O2 and the levels of malondialdehyde (MDA) in liver tissues. In addition, treatment with ATZ also enhanced LPS/D-Gal-induced hepatic apoptosis as evidenced by increased caspases activities in liver tissues and increased number of terminal deoxynucleotidyl transferase dUTP nick end labeling positive cells in liver sections.

CONCLUSION

These findings suggested that CAT might be involved in the progression of LPS/D-Gal-induced fulminant liver injury.

Hemin attenuates cisplatin-induced acute renal injury in male rats

Background. The aim of this study is to investigate the protective effects of hemin (the heme oxygenase-1 [OH-1] inducer) against nephrotoxic effects induced by cisplatin [cis-diamminedichloroplatinum II (CP)] in male rats. Methods. The evaluation was performed through monitoring renal redox parameters: lipid peroxidation (LPO), glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione reductase (GR), and reduced glutathione (GSH). The work also examined renal function tests (urea and creatinine), tissue proinflammatory mediator like nitric oxide (NO), and kidney cytopathology. Results. A single intraperitoneal dose of CP (10 mg/kg b.w.) caused significant elevation of blood urea, serum creatinine, and renal LPO and NO, along with significant decline of the activities of GPx and GR, but renal SOD activity and GSH level were statistically insignificant as compared to control group. Subcutaneous injection of hemin (40 µmol/kg b.w.) partially ameliorated CP-induced renal damage, based on suppression of blood urea, serum creatinine, the renal MDA and NO levels, and increased antioxidant capacity in CP-treated rats. The results of histopathological and ultrastructural investigations supported the renoprotective effect of hemin against CP-induced acute toxicity. Conclusion. The induction of HO-1 by hemin is a promising approach in the treatment of CP-induced nephrotoxicity. However, further preclinical studies are warranted to test effectiveness of CP/hemin on the outcome of tumor chemotherapy.

Upregulation of heat shock protein 32 with hemin alleviates acute heat-induced hepatic injury in mice

Heat shock protein 32 (HSP32) is a stress response protein that can be induced by heat stress in the liver, and its induction can act as an important cellular defence mechanism against heat-induced liver injury. To investigate the functional role of HSP32 in protecting liver tissue against heat stress in mice and the mechanism by which it achieves this protective effect, HSP32 expression and carbon monoxide (CO) contents in a model of mice subjected to acute, transient heat exposure were examined. Furthermore, functional and histological parameters of liver damage and the possible involvement of oxidative stress to induce oxidative deterioration of liver functions and caspase-3 expression were also investigated in this study. We found that heat treatment of mice produced severe hepatic injury, whereas upregulation of HSP32 with hemin pretreatment prevented mice from liver damage. In contrast, addition of Sn-protoporphyrin (SnPP) to inhibit HSP32 expression completely reversed its hepatoprotective effect. It is concluded that upregulation of HSP32 by hemin could alleviate acute heat-induced hepatocellular damage in mice, and its by-product CO seems to play a more important role in hepatoprotective mechanism.

Effect of remote ischemic post-conditioning on systemic inflammatory response and survival rate in lipopolysaccharide-induced systemic inflammation model

BACKGROUND

Remote ischemic preconditioning (RIPC) and postconditioning (RpostC) have protective effects on ischemia and reperfusion injury. The effects have been reported to activate heme oxygenase-1 (HO-1) and attenuate nuclear factor kappa B (NF-κB) and subsequently reduce systemic inflammation. Ischemic preconditioning prevented inflammatory responses by modulating HO-1 expression in endotoxic shock model. Therefore, we investigated whether RpostC could have protective effects on lipopolysaccharide (LPS)-induced systemic inflammation.

METHODS

The LPS-induced sepsis mice received LPS (20 mg/kg) intraperitoneally. Remote ischemic conditioning was induced with three 10-min ischemia/10-min reperfusion cycles of the right hind limbs using tourniquet before LPS injection (RIPC) or after LPS injection (RpostC). The effects of RIPC and RpostC were examined for the survival rate, serum cytokines, NF-κB, HO-1 and liver pathology in the LPS injected mice.

RESULTS

Survival rate within 120 hours significantly increased in the LPS injected and remote ischemic conditioned mice than in LPS only injected mice (60-65% vs 5%, respectively, p < 0.01). Tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β) and interleukin-6 (IL-6) increased markedly in the LPS only injected mice, however, remote ischemic conditioning suppressed the changes (p < 0.05). Interleukin-10 (IL-10) level was significantly higher in the LPS injected and RpostC treated mice than in the LPS only injected mice (p = 0.014). NF-κB activation was significantly attenuated (p < 0.05) and HO-1 levels were substantially higher in the LPS injected and remote ischemic conditioned mice than in the LPS only injected mice. Neutrophil infiltration was significantly attenuated in the LPS injected and remote ischemic conditioned mice than in the only LPS injected mice (p < 0.05).

CONCLUSIONS

RpostC attenuated inflammatory responses and improved survival outcomes of mice with LPS-induced systemic inflammation. The mechanism may be caused by modifying NF-κB mediated expression of cytokines.

Protective effect of danhong injection on acute hepatic failure induced by lipopolysaccharide and d-galactosamine in mice

Acute hepatic failure (AHF), which leads to an extremely high mortality rate, has become the focus of attention in clinic. In this study, Danhong injection (DHI) was investigated to evaluate the preventive and protective effect on AHF induced by lipopolysaccharide (LPS) and D-galactosamine (GalN) in mice. For AHF induction, ICR mice were intraperitoneally injected with D-GalN (700 mg/kg) and LPS (20  μ g/kg). DHI was administrated twice, at 12 and 1 h, respectively, before D-GalN/LPS injection. After stimulation with D-GalN/LPS for 1 and 6 h, serum and livers were collected for analysis. We found that mice administrated with DHI displayed a higher survival rate, lower serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBil), glutathione S-transferase (GST), and tumor necrosis factor (TNF)- α . DHI inhibited the elevations of hepatic lipid peroxidation (malondialdehyde), caspase-8 activity, and mRNA expression levels of inflammatory cytokines (interleukin-1 β and interleukin-6) increased by D-GalN/LPS in the liver. Furthermore, liver histopathological analysis indicated that the DHI group showed markedly fewer apoptotic (TUNEL positive) cells and less pathological changes than those in the AHF model group. These results provide a novel insight into the pharmacological actions of DHI as a potential candidate for treating AHF.

NLRP3 inflammasome activation in D-galactosamine and lipopolysaccharide-induced acute liver failure: role of heme oxygenase-1

D-Galactosamine (GalN) and lipopolysaccharide (LPS) are commonly used to study mechanisms of hepatic malfunction that result in hepatic inflammation and subsequent fulminant hepatic failure. Inflammasomes are intracellular multiprotein complexes that in response to cellular danger signals trigger the biological maturation of proinflammatory cytokines. Heme oxygenase-1 (HO-1) is a cytoprotective enzyme that induces anti-inflammatory and antioxidant activity against oxidative cellular stress. This study examined activation of the NACHT, LRR, and PYD domain-containing protein 3 (NLRP3) inflammasome in GalN/LPS-induced hepatic injury and the role of HO-1 in the signaling pathways of inflammasome. Mice (C57BL/6) were pretreated twice with hemin (HO-1 inducer, 30 mg/kg) and zinc protoporphyrin (ZnPP; HO-1 inhibitor, 10mg/kg) at 12 and 2h before GalN (800 mg/kg)/LPS (40 μg/kg) administration. HO-1 induction with hemin reversed the lethality induced by GalN/LPS administration, and ZnPP pretreatment blocked this change. Lipid peroxidation markedly increased after GalN/LPS treatment, whereas glutathione content decreased in the GalN/LPS group. These changes were attenuated by hemin, but ZnPP reversed the effects of hemin. Serum levels of tumor necrosis factor-α (TNF-α) and interleukin (IL)-1β increased after GalN/LPS treatment; these increases were attenuated by hemin. Hepatic mRNA levels of TNF-α, IL-1β, and NLRP3 increased after GalN/LPS treatment, and hemin attenuated increases in TNF-α and IL-1β. After GalN/LPS treatment, the hepatic expression of NLRP3, ASC, and caspase-1 (p10) was increased. In immunoprecipitation studies, hemin attenuated the interaction of NLRP3 with ASC and caspase-1. GalN/LPS induced expression of the thioredoxin-interacting protein (TXNIP) gene and the interaction between NLRP3 and TXNIP; again, hemin attenuated these effects. The effects of hemin were reversed by ZnPP. Our findings suggest that activation of the NLRP3 inflammasome leads to a GalN/LPS-induced inflammatory response through TXNIP-NLRP3 interaction. Furthermore, HO-1 overexpression may protect the liver against GalN/LPS-induced inflammation through suppression of the NLRP3 signaling pathway.

Haeme oxygenase activity protects the host against excessive cardiac inflammation during experimental Trypanosoma cruzi infection

The infection with Trypanosoma cruzi induces a robust cardiac inflammation that plays a pathogenic role in the development of Chagas heart disease. In this study, we aimed at investigating the effects of Haem Oxygenase (HO) during experimental infection by T. cruzi in BALB/c and C57BL/6 mice. HO has recently emerged as a key factor modulating the immune response in diverse models of inflammatory diseases. In mice with two different genetic backgrounds, the pharmacologic inhibition of HO activity with zinc-protoporphyrin IX (ZnPPIX) induced enhanced myocarditis and reduced parasitaemia, which was accompanied by an amplified production of nitric oxide and increased influx of CD4(+), CD8(+) and IFN-γ(+) cells to the myocardium in comparison with the control group. Conversely, treatment with haemin (an activator of HO) lead to a decreased number of intracardiac CD4(+) (but not CD8(+)) cells compared to the control group. The mechanism involved in these observations is a modulation of the induction of regulatory T cells, because the stimulation or inhibition of HO was parallelled by an enhanced or reduced frequency of regulatory T cells, respectively. Hence, HO may be involved in the regulation of heart tissue inflammation and could be a potential target in conceiving future therapeutic approaches for Chagas disease.

Simvastatin treatment ameliorates injury of rat testes induced by cadmium toxicity

Cadmium-induced testicular toxicity is mediated through oxidative stress and inflammation which eventually lead to cell death. Simvastatin, the antihyperlipidemic agent, exhibits additional antioxidant and anti-inflammatory activities. The aim of the present work was to investigate the protective effect of simvastatin against cadmium-induced testicular toxicity in rats. The rats received a single intraperitoneal (i.p.) injection of cadmium chloride (2 mg/kg). Simvastatin treatment (5 mg/kg/day, i.p.) was applied for three consecutive days, starting 1 day before cadmium administration. Cadmium significantly decreased serum testosterone, and testicular reduced glutathione and catalase activity, and significantly increased testicular malondialdehyde, nitric oxide, and cadmium ion levels. Simvastatin significantly ameliorated the biochemical changes induced by cadmium. Cadmium-induced testicular tissue injury observed by histopathological examination was attenuated by simvastatin. In addition, simvastatin significantly decreased the expression of inducible nitric oxide synthase, cyclooxygenase-2, tumor necrosis factor-α, nuclear factor-κB, and caspase-3, and increased heme oxygenase-1 expression in testicular tissue of rats exposed to cadmium toxicity. It was concluded that simvastatin, through its antioxidant and anti-inflammatory activities, provided a significant protective effect against cadmium-induced testicular toxicity in rats. However, starting treatment with simvastatin before cadmium exposure, as done in the present work, is not clinically applicable. Therefore, other investigations are needed to assess the protective effect of simvastatin treatment following induction of cadmium testicular toxicity.

Activation of renal haeme oxygenase-1 alleviates gentamicin-induced acute nephrotoxicity in rats

Objectives

This study aimed to investigate whether activation of haeme oxygenase (HO)-1 enzyme by haemin would have beneficial effects on the functional and histological outcome against gentamicin-induced renal damage in rats and sought to elucidate the underlying mechanisms of the therapeutic action.

Methods

Nephrotoxicity was induced by injection of gentamicin (80 mg/kg, i.p.) once daily for seven days. Haemin (50 μmol/kg, i.p.) was given to the control and gentamicin-treated rats in the presence or absence of a HO-1 inhibitor, zinc protoporphyrin IX (ZnPP, 50 μmol/kg per day, i.p.).

Key findings

Haemin treatment prevented gentamicin-induced elevated serum creatinine, urinary protein levels and ameliorated the impaired creatinine clearance. Haemin compensated the deficits in antioxidant enzyme activity and attenuated lipid peroxidation along with decreased reactive oxygen species (ROS) production in renal tissues due to gentamicin. Moreover, haemin pre-administration evoked increased renal HO-1 activity. Additionally, haemin significantly attenuated elevated renal tumour necrosis factor-α (TNF-α), nuclear factor-kappaB (NF-κB) levels and caspase-3 activity alongside ameliorating glomerular pathology. These therapeutic effects were abolished by ZnPP pretreatment.

Conclusions

Here is the first evidence demonstrating the protective effect of HO-1 against gentamicin-associated nephrotoxicity. Suppression of oxidative/inflammatory insults alongside the corresponding decline of apoptosis were presumably responsible for this renoprotection.

Geniposidic acid protects against D-galactosamine and lipopolysaccharide-induced hepatic failure in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Geniposidic acid (GA) is an iridoid glucoside isolated from Gardeniae jasminoides Ellis (Rubiaceae) that has long been used to treat inflammation, jaundice and hepatic disorders.

AIMS OF THE STUDY

This study examined the cytoprotective properties of GA against D-galactosamine (GalN)/lipopolysaccharide (LPS)-induced fulminant hepatic failure.

MATERIALS AND METHODS

Mice were given an intraperitoneal injection of GA (12.5, 25, 50 mg/kg) 1h before receiving GalN (800 mg/kg)/LPS (40 μg/kg). Liver and blood samples were collected 1 and 8 h after GalN/LPS injection.

RESULTS

The survival rate of the GA group was significantly higher than the control. GalN/LPS increased serum aminotransferase activity, serum tumor necrosis factor-α level and hepatic lipid peroxidation and decreased hepatic glutathione content. These changes were attenuated by GA. GA augmented increases in serum interleukin-6 level, heme oxygenase-1 and NF-E2-related factor 2 protein expression. Mice treated with GA decreased cleaved caspase-8 and caspase-3 protein expression and showed significantly fewer apoptotic cells. GA increased Bcl-xL protein expression and decreased Bax protein expression. Moreover, GA treatment enhanced phosphorylation of signal transducer and activator of transcription 3.

CONCLUSION

Our findings suggest that geniposidic acid alleviates GalN/LPS-induced liver injury by enhancing antioxidative defense system and reducing apoptotic signaling pathways.

Low dose of carbon monoxide intraperitoneal injection provides potent protection against GalN/LPS-induced acute liver injury in mice

Carbon monoxide (CO) is an important effector-signaling molecule involved in various pathophysiological processes. Here we investigated the protective effects of exogenous CO in a murine model of acute liver damage induced by d-galactosamine (GalN) and lipopolysaccharide (LPS). Exogenous CO gas was administered to mice via intraperitoneal injection (first at a dose of 15 ml kg(-1) and then, 6 h later, 8 ml kg(-1)), which caused a significant elevation of blood carboxyhemoglobin levels of up to 12-14% for more than 12 h. GalN/LPS were given to induce acute liver damage in mice 30 min prior to CO exposure. This showed that GalN/LPS induced severe liver injury in mice, whereas CO injection remarkably improved the survival rate of mice and led to attenuated hepatocellular damage. CO exhibited anti-oxidative capabilities by inhibiting hepatic malondialdehyde contents and restoring superoxide dismutase and glutathione, as well as by reducing inducible NOS/NO production. The anti-apoptotic and anti-inflammatory effects of CO were substantial, characterized by a notable inhibition of hepatocyte apoptosis and a reduction of pro-inflammatory cytokines in mice. Our findings thus supported the hypothesis that exogenous CO provides protective effects against acute liver damage in mice, mainly dependent on its anti-oxidative, anti-inflammatory and anti-apoptotic properties.

Protective effects of captopril in diabetic rats exposed to ischemia/reperfusion renal injury

Objectives

To investigate the potential protective effects of captopril, the angiotensin-converting enzyme inhibitor, in diabetic rats exposed to ischaemia/reperfusion (I/R) renal injury.

Methods

Following successful induction of diabetes, captopril treatment (50 mg/kg/day, p.o.) was applied for 4 weeks, after which bilateral renal ischaemia was induced for 30 min followed by reperfusion for 24 h.

Results

Captopril significantly attenuated hyperglycaemia and hypoinsulinaemia in diabetic rats, and significantly reduced the elevations of serum creatinine and aldosterone levels, and renal malondialdehyde, tumour necrosis factor-α and nitric oxide (NO), and prevented the depletion of reduced glutathione caused by I/R in diabetic rats. Histopathological renal tissue damage induced by I/R in diabetic rats was ameliorated by captopril treatment. Immunohistochemical analysis revealed that captopril significantly attenuated the reduction of insulin content in pancreatic islet β-cells, and decreased the I/R-induced expression of inducible NO synthase, nuclear factor-κB, Fas ligand and caspase-3, and increased the expression of survivin and heme oxygenase-1 in the kidney tissue of diabetic rats.

Conclusions

Captopril represents a potential candidate to reduce the risk of renal injury induced by ischaemia/reperfusion in type 2 diabetes.

Involvement of heme oxygenase-1 in β-cyclodextrin-hemin complex-induced cucumber adventitious rooting process

Our previous results showed that β-cyclodextrin-hemin complex (CDH) exhibited a vital protective role against cadmium-induced oxidative damage and toxicity in alfalfa seedling roots by the regulation of heme oxygenase-1 (HO-1) gene expression. In this report, we further test whether CDH exhibited the hormonal-like response. The application of CDH and an inducer of HO-1, hemin, were able to induce the up-regulation of cucumber HO-1 gene (CsHO1) expression and thereafter the promotion of adventitious rooting in cucumber explants. The effect is specific for HO-1 since the potent HO-1 inhibitor zinc protoporphyrin IX (ZnPP) blocked the above responses triggered by CDH, and the inhibitory effects were reversed further when 30% saturation of CO aqueous solution was added together. Further, molecular evidence showed that CDH triggered the increases of the HO-1-mediated target genes responsible for adventitious rooting, including one DnaJ-like gene (CsDNAJ-1) and two calcium-dependent protein kinase (CDPK) genes (CsCDPK1 and CsCDPK5), and were inhibited by ZnPP and reversed by CO. The calcium (Ca2+) chelator ethylene glycol-bis (2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) and the Ca2+ channel blocker lanthanum chloride (LaCl3) not only compromised the induction of adventitious rooting induced by CDH but also decreased the transcripts of above three target genes. However, the application of ascorbic acid (AsA), a well-known antioxidant in plants, failed to exhibit similar inducible effect on adventitious root formation. In short, above results illustrated that the response of CDH in the induction of cucumber adventitious rooting might be through HO-1-dependent mechanism and calcium signaling.

KEY MESSAGE

Physiological, pharmacological and molecular evidence showed that β-cyclodextrin-hemin complex (CDH) was able to induce cucumber adventitious rooting through heme oxygenase-1 (HO-1)-dependent mechanism and calcium signaling.

Efficacy of MK615 for the treatment of patients with liver disorders

AIM: To investigate the hepatoprotective effect of MK615, a Japanese apricot extract, in an animal model, and its clinical therapeutic effect.

METHODS: Wistar rats were administered physiological saline (4 mL/kg) or MK615 solution (4 mL/kg) for 7 d. On the sixth d, acute hepatic injury was induced by administering a single intraperitoneal injection (ip) of D-galactosamine hydrochloride (D-GalN) (600 mg/kg). Plasma levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined, and liver tissues were used for histopathological analysis. Fifty-eight patients with liver disorders [hepatitis C (n = 40), non-alcoholic fatty liver disease (n = 15), and autoimmune liver disease (n = 3)] were orally administered commercially available Misatol ME-containing MK615 (13 g/d) daily for 12 wk. Blood and urine were sampled immediately before and 6 wk, 12 wk, and 16 wk after the start of intake to measure various biochemical parameters. The percentage change in ALT and AST levels after 12 wk from the pre-intake baseline served as a primary endpoint.

RESULTS: D-GalN effectively induced acute hepatic injury in the rats. At 48 h after the ip injection of D-GalN, the plasma levels of ALT (475.6 ± 191.5 IU/L vs 225.3 ± 194.2 IU/L, P < 0.05) and AST (1253.9 ± 223.4 IU/L vs 621.9 ± 478.2 IU/L, P < 0.05) in the MK615 group were significantly lower than the control group. Scattered single cell necrosis, loss of hepatocytes, and extensive inflammatory cell infiltration were observed in hepatic tissue samples collected from the control group. However, these findings were less pronounced in the group receiving MK615. At the end of the clinical study, serum ALT and AST levels were significantly decreased compared with pre-intake baseline levels from 103.5 ± 58.8 IU/L to 71.8 ± 39.3 IU/L (P < 0.05) and from 93.5 ± 55.6 IU/L to 65.5 ± 34.8 IU/L (P < 0.05), respectively. A reduction of ≥ 30% from the pre-study baseline ALT level was observed in 26 (45%) of the 58 patients, while 25 (43%) patients exhibited similar AST level reductions. The chronic hepatitis C group exhibited significant ALT and AST level reductions from 93.4 ± 51.1 IU/L to 64.6 ± 35.1 IU/L (P < 0.05) and from 94.2 ± 55.5 IU/L to 67.2 ± 35.6 IU/L (P < 0.05), respectively. A reduction of ≥ 30% from the pre-study baseline ALT level was observed in 20 (50%) of the 40 patients. ALT levels in both the combined ursodeoxycholic acid (UDCA) treatment and the UDCA uncombined groups were significantly lower after Misatol ME administration. MK615 protected hepatocytes from D-GalN-induced cytotoxicity in rats. Misatol ME decreased elevated ALT and AST levels in patients with liver disorders.

CONCLUSION: These results suggest that MK615 and Misatol ME are promising hepatoprotective agents for patients with liver disorders.

The protection by heme oxygenase-1 induction against thioacetamide-induced liver toxicity is associated with changes in arginine and asymmetric dimethylarginine

This study was designed to investigate the role of HO-1 induction in prevention of thioacetamide (TAA)-induced oxidative stress, inflammation and liver damage. The changes in hepatic dimethylarginine dimethylaminohydrolase (DDAH) activity as well as plasma arginine and asymmetric dimethylarginine (ADMA) levels were also measured to evaluate nitric oxide (NO) bioavailability. Rats were divided into four groups as control, hemin, TAA and hemin + TAA groups. Hemin (50 mg kg(-1) , i.p.) was injected to rats 18 h before TAA treatment to induce HO-1 enzyme expression. Rats were given TAA (300 mg kg(-1) , i.p.) and killed 24 h after treatment. Although TAA treatment produced severe hepatic injury, upregulation of HO-1 ameliorated TAA-induced liver damage up to some extent as evidence by decreased serum alanine transaminase, aspartate transaminase and arginase activities and histopathological findings. Induction of HO-1 stimulated antioxidant system and decreased lipid peroxidation in TAA-treated rats. Myeloperoxidase activity and inducible NO synthase protein expression were decreased, whereas DDAH activity was increased by hemin injection in TAA-treated rats. Induction of HO-1 was associated with increased arginine levels and decreased ADMA levels, being the main determinants of NO production, in plasma of TAA-treated rats. In conclusion, our results indicate that HO-1 induction alleviated increased oxidative stress and inflammatory reactions together with deterioration in NO production in TAA-induced liver damage in rats.

Echinacea alkamides prevent lipopolysaccharide/D-galactosamine-induced acute hepatic injury through JNK pathway-mediated HO-1 expression

This study aimed to shed light on the anti-inflammatory and hepatoprotective effect of the major alkamides dodeca-2E,4E,8Z,10Z(E)-tetraenoic acid isobutylamides (Alk-8/9), isolated from Echinacea purpurea roots, against acute fulminant hepatitis induced by lipopolysaccharide/D-galactosamine (LPS/D-GalN) in mice. The results show that Alk-8/9 dose-dependently induced heme oxygenase (HO)-1 protein expression in LPS-stimulated murine macrophages that was likely regulated by the JNK-mediated pathway through increasing SAPK/JNK phosphorylation, c-jun protein expression, and phosphorylation, and transcription factor AP-1 binding consensus DNA activity. The HO-1 inhibitor or CO scavenger significantly reversed the inhibitory effect of Alk-8/9 on TNF-α expression, whereas N-acetyl-L-cysteine was observed to reduce Alk-8/9-induced HO-1 expression in LPS-treated macrophages. Furthermore, Alk-8/9 markedly induced c-jun and HO-1 protein expression and suppressed serum aminotransferase activities, TNF-α expression, and hepatocyte damage in liver tissues of LPS/d-GalN-treated mice. This paper suggests a new application of Echinacea, a top-selling herbal supplement, as a hepatoprotective agent.

Hepatoprotective effects of IL-22 on fulminant hepatic failure induced by d-galactosamine and lipopolysaccharide in mice

Interleukin-22 (IL-22), a member of the IL-10 cytokine family that is produced by activated Th22, Th1 and Th17 cells as well as natural killer cells, plays an important role in increase of innate immunity, protection from damage and enhancement of regeneration. Here, we examined the effects of IL-22 on acute liver failure model induced by d-galactosamine (GalN) and lipopolysaccharide (LPS). Administration of recombinant human IL-22 (rhIL-22) reduced the death rate markedly and prevented mice from severe hepatic injury, as evidenced by decreased serum alanine aminotransferase (ALT) and total bilirubin (T.Bil) activity as well as improved histological signs in liver. Furthermore, IL-22 treatment decreased the hepatic malondialdehyde (MDA) contents and increased the reduced glutathione levels. Serum tumor necrosis factor α (TNF-α) level and hepatic caspase-3 activity were significantly lower in mice administrated with IL-22. Moreover, IL-22 treatment significantly enhanced activation of STAT3 and up-regulated the expression of Bcl-xL, heme oxygenase-1 (HO-1) and redox factor-1 (Ref-1) in the liver injury induced by GalN/LPS. Collectively, these data indicate that IL-22 can provide critical protection against GalN/LPS-induced liver injury through anti-apoptotic, anti-oxidant and anti-inflammatory actions.

Hepatoprotective and Antioxidative Activities of Cornus officinalis against Acetaminophen-Induced Hepatotoxicity in Mice

The fruit of Cornus officinalis Sieb. et Zucc. is commonly prescribed in Asian countries as a tonic formula. In this study, the hepatoprotective effect of ethanolic extracts of the fruit of C. officinalis (ECO) was investigated in a mouse model of acetaminophen- (APAP-) induced liver injury. Pretreatment of mice with ECO (100, 250, and 500 mg/kg for 7 days) significantly prevented the APAP (200 mg/kg) induced hepatic damage as indicated by the serum marker enzymes (AST, ALT, and LDH). Parallel to these changes, ECO treatment also prevented APAP-induced oxidative stress in the mice liver by inhibiting lipid peroxidation (MDA) and restoring the levels of antioxidant enzymes (SOD, CAT, and HO-1) and glutathione. Liver injury and collagen accumulation were assessed using histological studies by hematoxylin and eosin staining. Our results indicate that ECO can prevent hepatic injuries associated with APAP-induced hepatotoxicity by preventing or alleviating oxidative stress.

Differential Oxidative Stress Responses to D-Galactosamine-Lipopolysaccharide Hepatotoxicity Based on Real Time PCR Analysis of Selected Oxidant/Antioxidant and Apoptotic Gene Expressions in Rat

Oxidative stress and apoptosis are proposed mechanisms of cellular injury in studies of xenobiotic hepatotoxicity. This study is focused on addressing the mutual relationship and early signals of these mechanisms in the D-galactosamine and lipopolysaccharide (D-GalN/LPS) hepatotoxicity model, with the help of standard liver function and biochemistry tests, histology, and measurement of gene expression by RT-PCR. Intraperitoneal injection of 400 mg/kg D-GalN and 50 μg/kg LPS was able to induce hepatotoxicity in rats, as evidenced by significant increases in liver enzymes (ALT, AST) and raised bilirubin levels in plasma. Heme oxygenase-1 and nitric oxide synthase-2 gene expressions were significantly increased, along with levels of their products, bilirubin and nitrite. The gene expression of glutathione peroxidase 1 remained unchanged, whereas a decrease in superoxide dismutase 1 gene expression was noted. Furthermore, the significant increase in the gene expression of apoptotic genes Bid, Bax and caspase-3 indicate early activation of apoptotic pathways, which was confirmed by histological evaluation. In contrast, the measured caspase-3 activity remained unchanged. Overall, the results have revealed differential oxidative stress and apoptotic responses, which deserves further investigations in this hepatotoxicity model.

Tacrolimus modulates liver and pancreas nitric oxide synthetase and heme-oxygenase isoforms and cytokine production after endotoxemia

Cytoprotective effects of tacrolimus are due to its unspecific anti-inflammatory and anti-oxidant properties. Neither the exact mechanisms nor if there is any organ-specificity or dose-dependent response have not been yet elucidated. Our aim was to evaluate the effect of tacrolimus on oxidative stress and mediator production in liver and pancreatic tissue secondary to endotoxemia. Wistar rats were pretreated with intraperitoneal injection of tacrolimus (0.07, 0.15, and 0.3mg/kg) 24h before Escherichia coli LPS was administrated. Animals were sacrificed 24h after LPS administration and iNOS, eNOS, and nNOS and type 1 and 2 heme-oxygenase (HO) expression were measured. TNF-α and IL-1 tissue expression and plasmatic NO, CO, TNF-α, and IL-1 were also determined. LPS exposure increased iNOS expression in both organs, eNOS did not show variations and liver nNOS expression was significantly lower. Tacrolimus diminished both pancreas and liver iNOS and nNOS expression. Both liver and pancreatic eNOS expression augmented when tacrolimus was administrated. High doses of tacrolimus were correlated with ameliorated liver HO-1 plus HO-2 and pancreas HO-1 expression after LPS stimulation. Tacrolimus treatment diminished TNF-α but not IL-1 expression increase after LPS challenge in hepatic tissue. Pancreatic TNF-α and IL-1 values diminished partially when high doses were employed. Plasmatic NO, CO, TNF-α, and IL-1 concentrations increase after LPS challenge was diminished when highest doses of tacrolimus were given. In conclusion, tacrolimus exerts a protective effect on commonly observed harmful phenomena after LPS stimulation by modulating liver and pancreas oxidative enzyme expression and cytokine production.

Induction of heme oxygenase-1 attenuates lipopolysaccharide-induced cyclooxygenase-2 expression in mouse brain endothelial cells

Background

Prostaglandin E₂ (PGE₂), an arachidonic acid metabolite converted by cyclooxygenase-2 (COX-2), plays important roles in the regulation of endothelial functions in response to bacterial infection. The enzymatic activity of COX-2 can be down-regulated by heme oxygenase-1 (HO-1) induction. However, the mechanisms underlying HO-1 modulating COX-2 protein expression are not known.

Objective

The aim of the present study was to investigate whether the up-regulation of HO-1 regulates COX-2 expression induced by lipopolysaccharide (LPS), an endotoxin produced by Gram negative bacteria, in mouse brain endothelial cells (bEnd.3)

Methods

Cultured bEnd.3 cells were used to investigate LPS-induced COX-2 expression and PGE₂ production. Cobalt protoporphyrin IX (CoPP, an HO-1 inducer), infection with a recombinant adenovirus carried with HO-1 gene (Adv-HO-1), or zinc protoporphyrin (ZnPP, an HO-1 inhibitor) was used to stimulate HO-1 induction or inhibit HO-1 activity. The expressions of COX-2 and HO-1 were evaluated by western blotting. PGE₂ levels were detected by an enzyme-linked immunoassay. Hemoglobin (a chelator of carbon monoxide, CO, one of metabolites of HO-1) and CO-RM2 (a CO releasing molecule) were used to investigate the mechanisms of HO-1 regulating COX-2 expression.

Results

We found that LPS-induced COX-2 expression and PGE₂ production were mediated through NF-κB (p65) via activation of Toll-like receptor 4 (TLR4). LPS-induced COX-2 expression was inhibited by HO-1 induction by pretreatment with CoPP or infection with Adv-HO-1. This inhibitory effect of HO-1 was reversed by pretreatment with either ZnPP or hemoglobin. Pretreatment with CO-RM2 also inhibited TLR4/MyD88 complex formation, NF-κB (p65) activation, COX-2 expression, and PGE₂ production induced by LPS.

Conclusions

We show here a novel inhibition of HO-1 on LPS-induced COX-2/PGE₂ production in bEnd.3. Our results reinforce the emerging role of cerebral endothelium-derived HO-1 as a protector against cerebral vascular inflammation triggered by bacterial infection.

Transgenic expression of haem oxygenase-1 in pancreatic beta cells protects non-obese mice used as a model of diabetes from autoimmune destruction and prolongs graft survival following islet transplantation

AIMS/HYPOTHESIS

Haem oxygenase 1 (HO-1) has strong anti-apoptotic, anti-inflammatory and antioxidative effects that help protect cells against various forms of immune attack. We investigated whether transgenic expression of Ho-1 (also known as Hmox1) in pancreatic beta cells would protect NOD mice from autoimmune damage and prolong graft survival following islet transplantation.

METHODS

To evaluate the protective effect of beta cell-specific HO-1 in autoimmune diabetes, we used an insulin promoter-driven murine Ho-1 construct (pIns-mHo-1) to generate a transgenic NOD mouse. Transgene expression, insulitis and the incidence of diabetes in mice were characterised. Lymphocyte composition, the development of T helper (Th)1, Th2 and T regulatory (Treg) cells, T cell proliferation and lymphocyte-mediated disease transfer were analysed. The potential effects of transgenic islets and islet transplantation on apoptosis, inflammation and the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) were evaluated.

RESULTS

Transgenic mice showed less severe insulitis and a lower incidence of diabetes than non-transgenic control littermates. Lymphocyte composition and functions were not affected. Islets from transgenic mice expressed lower levels of proinflammatory cytokines/chemokines, proapoptotic gene expression and amounts of ROS/RNS, and were more resistant to TNF-α- and IFN-γ-induced apoptosis. Islet grafts from transgenic mice also survived longer in diabetic recipients than control islets.

CONCLUSIONS/INTERPRETATION

Transgenic overexpression of Ho-1 in beta cells protected NOD mice from diabetes and delayed the autoimmune destruction of islet grafts, providing valuable insight into the development of better strategies for clinical islet transplantation in patients with type 1 diabetes.