Protective role of heme oxygenase 1 in the intestinal tissue injury in hemorrhagic shock in rats

Hirudin ameliorates myocardial ischemia-reperfusion injury in a rat model of hemorrhagic shock and resuscitation: roles of NLRP3-signaling pathway

Severe hemorrhage shock and resuscitation (HSR) has been reported to induce myocardial ischemia-reperfusion injury (MIRI), resulting in a poor prognosis. Hirudin, an effective thrombin inhibitor, can offer protection against MIRI. This study aimed to determine if hirudin administration ameliorates HSR-induced MIRI and the underlying mechanism. A rat model of HSR was established by bleeding rats to a mean arterial blood pressure of 30-35 mmHg for 45 min and then resuscitating them with all the shed blood through the left femoral vein. After HSR, 1 mg/kg of hirudin was administrated immediately. At 24 h after HSR, the cardiac injury was assessed using serum CK-MB, cTnT, hematoxylin-eosin (HE) staining, echocardiography, M1-polarized macrophages, and pyroptosis-associated factors, including cleaved caspase-1, Gasdermin D (GSDMD) N-terminal, IL-1β, and IL-18 were measured by immunofluorescence and western blot assays. Nigericin, a unique agonist, was utilized to evaluate the responsibilities of NLRP3 signaling. Under the HSR condition, rats exhibited a significant increase in myocardial injury score, an elevation of serum cTnT, CK-MB levels, an aggrandization of M1-polarized macrophages, an upregulation of pyroptosis-associated factors, including cleaved caspase-1, GSDMD N-terminal, IL-1β, and IL-18, but a significant decrease in left ventricular ejection fraction (EF%) and a reduction of left ventricular fractional shortening (FS%), while hirudin administration partially restored the changes. However, the NLRP3 agonist nigericin reversed the cardioprotective effects of hirudin. We determined the cardioprotective effects of hirudin against HSR-induced MIRI. The mechanism may involve the inhibition of NLRP3-induced pyroptosis.

Articles on hemorrhagic shock published between 2000 and 2021: A CiteSpace-Based bibliometric analysis

Objective

To conduct a bibliometric analysis of literature on hemorrhagic shock published between 2000 and 2021 with the help of Citespace to explore the current status, hotspots and research trends in this regard, with the results presented in a visualized manner.

Methods

The data over the past 22 years were retrieved from the Web of Science (WOS) Core Collection database and downloaded as the "Full Record and Cited References". Cooperative analysis, cluster analysis, co-citation analysis, and burst analysis were performed based on the data on countries/regions, institutions, journals, authors, and keywords through Citespace.

Results

A total of 2027 articles were retrieved. The number of annual publications fluctuated but was generally on an upward trend. The United States stands out as the most productive country (989 articles), the University of Pittsburgh the most productive publishing institution (109 articles), SHOCK the most cited journal (1486 articles), TAO LI the most productive author (40 articles), DEITCH EA the most cited author (261 times of citation), hemorrhagic shock the most frequent keyword (725 times of occurrence), and "traumatic brain injury" the most covered article in keyword clustering (29 articles). The burst analysis revealed Harvard University as the institution with the highest strength value and the Journal of Trauma and Acute Care Surgery the most important journal. It was also concluded that HASAN B ALAM, AARON M WILLIAMS, and LIMIN ZHANG may continue to publish high-quality articles in the future. In the meanwhile, both "protect" and "transfusion" were considered the hotspots and trends in current research.

Conclusions

The United States has been a major contributor to the publication of the articles over the past 22 years, with the most productive publishing institution, the most cited journal, and the most cited author all coming from the US. Hemorrhagic shock, injury, resuscitation, trauma, models, activation, expression, fluid resuscitation, rats, and nitric oxide are hot topics in relevant research. According to the keyword burst analysis, the areas related to "protect" and "transfusion" may rise as the research directions in the future. However, since the hotspots in the research of hemorrhagic shock are short-lived and fast-changing, the researchers should pay more attention to the development trend in this field.

CORM-3 alleviates the intestinal injury in a rodent model of hemorrhage shock and resuscitation: roles of GFAP-positive glia

Hemorrhagic shock and resuscitation (HSR) can induce severe intestinal damages, thereby leading to sepsis and long-term complications including dysbacteriosis and pulmonary injury. The NOD-like receptor protein 3 (NLRP3) inflammasome facilitates inflammation-associated cell recruitment in the gastrointestinal tract, and participates in many inflammatory bowel diseases. Previous studies have shown that exogenous carbon monoxide (CO) exerts neuroprotective effects against pyroptosis after HSR. We aimed to investigate whether carbon monoxide-releasing molecules-3 (CORM-3), an exogenous CO compound, could attenuate HSR-induced intestinal injury and the potential underlying mechanism.Rats were subjected to a HSR model by bleeding and re-infusion. Following resuscitation, 4 mg/kg of CORM-3 was administered intravenously into femoral vein. At 24 h and 7 d after HSR modeling, the pathological changes in intestinal tissues were evaluated by H&E staining. The intestinal pyroptosis, glial fibrillary acidic protein (GFAP)-positive glial pyroptosis, DAO (diamine oxidase) content, intestine tight junction proteins including zonula occludens-1 (ZO-1) and claudin-1 were further detected by immunofluorescence, western blot and chemical assays at 7 d after HSR. CORM-3 administration led to significantly mitigated HSR-induced intestinal injury, aggravation of intestinal pyroptosis indicated by cleaved caspase-1, IL-1β and IL-18, upregulation of GFAP-positive glial pyroptosis, decreased intensity of ZO-1 and claudin-1 in the jejunum, and increased of DAO in the serum. Nigericin, an agonist of NLRP3, significantly reversed the protective effects of CORM-3. CORM-3 alleviates the intestinal barrier dysfunction in a rodent model of HSR, and the potential mechanism may be associated with inhibition of NLRP3-associated pyroptosis. CORM-3 administration could be a promising therapeutic strategy for intestinal injury after hemorrhagic shock.

Dexmedetomidine improves acute lung injury by activating autophagy in a rat hemorrhagic shock and resuscitation model

Dexmedetomidine (DEX) can reduce lung injury in a hemorrhagic shock (HS) resuscitation (HSR) model in rats by inhibiting inflammation. Here, we aimed to investigate if these effects of DEX are due to autophagy activation. Therefore, we established HSR rat models and divided them into four groups. HS was induced using a blood draw. The rats were then resuscitated by reinjecting the drawn blood and saline. The rats were sacrificed 24 h after resuscitation. Lung tissues were harvested for histopathological examination, determination of wet/dry lung weight ratio, and detection of the levels of autophagy-related marker proteins LC3, P62, Beclin-1, and the ATG12-ATG5 conjugate. The morphological findings of hematoxylin and eosin staining in lung tissues and the pulmonary wet/dry weight ratio showed that lung injury improved in HSR + DEX rats. However, chloroquine (CQ), an autophagy inhibitor, abolished this effect. Detecting the concentration of autophagy-related proteins showed that DEX administration increased LC3, ATG12-ATG5, and Beclin-1 expression and decreased P62 expression. The expression levels of these proteins were similar to those in the HSR group after CQ + DEX administration. In summary, DEX induced autophagic activation in an HSR model. These findings suggest that DEX administration partially ameliorates HSR-induced lung injury via autophagic activation.

Role of Heme Oxygenase in Gastrointestinal Epithelial Cells

The gastrointestinal tract is a unique organ containing both vascular and luminal routes lined by epithelial cells forming the mucosa, which play an important role in the entry of nutrients and act as a selective barrier, excluding potentially harmful agents. Mucosal surfaces establish a selective barrier between hostile external environments and the internal milieu. Heme is a major nutritional source of iron and is a pro-oxidant that causes oxidative stress. Heme oxygenases (HOs) catalyze the rate-limiting step in heme degradation, resulting in the formation of iron, carbon monoxide, and biliverdin, which are subsequently converted to bilirubin by biliverdin reductase. In gastrointestinal pathogenesis, HO-1, an inducible isoform of HO, is markedly induced in epithelial cells and plays an important role in protecting mucosal cells. Recent studies have focused on the biological effects of the products of this enzymatic reaction, which have antioxidant, anti-inflammatory, and cytoprotective functions. In this review, the essential roles of HO in the gastrointestinal tract are summarized, focusing on nutrient absorption, protection against cellular stresses, and the maintenance and regulation of tight junction proteins, emphasizing the potential therapeutic implications. The biochemical basis of the potential therapeutic implications of glutamine for HO-1 induction in gastrointestinal injury is also discussed.

The Intestinal Redox System and Its Significance in Chemotherapy-Induced Intestinal Mucositis

Chemotherapy-induced intestinal mucositis (CIM) is a significant dose-limiting adverse reaction brought on by the cancer treatment. Multiple studies reported that reactive oxygen species (ROS) is rapidly produced during the initial stages of chemotherapy, when the drugs elicit direct damage to intestinal mucosal cells, which, in turn, results in necrosis, mitochondrial dysfunction, and ROS production. However, the mechanism behind the intestinal redox system-based induction of intestinal mucosal injury and necrosis of CIM is still undetermined. In this article, we summarized relevant information regarding the intestinal redox system, including the composition and regulation of redox enzymes, ROS generation, and its regulation in the intestine. We innovatively proposed the intestinal redox “Tai Chi” theory and revealed its significance in the pathogenesis of CIM. We also conducted an extensive review of the English language-based literatures involving oxidative stress (OS) and its involvement in the pathological mechanisms of CIM. From the date of inception till July 31, 2021, 51 related articles were selected. Based on our analysis of these articles, only five chemotherapeutic drugs, namely, MTX, 5-FU, cisplatin, CPT-11, and oxaliplatin were shown to trigger the ROS-based pathological mechanisms of CIM. We also discussed the redox system-mediated modulation of CIM pathogenesis via elaboration of the relationship between chemotherapeutic drugs and the redox system. It is our belief that this overview of the intestinal redox system and its role in CIM pathogenesis will greatly enhance research direction and improve CIM management in the future.

5-Aminolevulinic Acid Attenuates Glucose-Regulated Protein 78 Expression and Hepatocyte Lipoapoptosis via Heme Oxygenase-1 Induction

Endoplasmic reticulum (ER) stress plays a pivotal role in the progression of steatohepatitis. 5-aminolevulinic acid (5-ALA), a precursor in the heme biosynthetic pathway, has recently been reported to induce heme oxygenase (HO)-1. HO-1 exerts important cytoprotective actions. In this study, we aimed to explore the therapeutic potential of 5-ALA on palmitate-induced ER stress and lipoapoptosis. Huh-7 cells were treated with palmitic acid (PA) (800 μM) to induce steatosis for eight hours. Steatosis was evaluated by Lipi-green staining. 5-ALA (200 μM) was added with PA. The gene expression levels of the nuclear factor erythroid 2-related factor 2 (NRF2), HO-1, Glucose-regulated protein 78 (GRP78), activating transcription factor 6 (ATF6), PKR-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1 (IRE1), C/EBP homologous protein (CHOP), and B-cell lymphoma 2 (BCL-2) were evaluated by RT-PCR. Caspase-3/7 activity was evaluated by fluorescein active Caspase-3/7 staining. Cell death was evaluated by Annexin V/SYTOX green staining. PA significantly induced steatosis and increased GRP78 expression in Huh-7 cells. 5-ALA significantly induced HO-1 and decreased GRP78 expression. ATF6 was subsequently decreased. However, NRF2 and CHOP expression were not altered. Anti-apoptotic BCL-2 expression significantly increased, and Caspase 3/7 activity and cell death also decreased. 5-ALA has a therapeutic potential on hepatic steatosis by suppressing ER stress and lipoapoptosis by attenuating GRP78 via HO-1 induction.

TUDCA Ameliorates Liver Injury Via Activation of SIRT1-FXR Signaling in a Rat Hemorrhagic Shock Model

OBJECTIVE

The aim of this study was to investigate the changes of bile acids in the liver during hemorrhagic shock (HS) and their potential to attenuate liver injury via activation of SIRT1 (sirtuin 1)-FXR (farnesoid X receptor) signaling.

METHODS

A Sprague-Dawley (SD) rat HS model was established, whereas HepG2 cells were hypoxically cultured to simulate HS in vitro. Liver bile acids (BA) were profiled with ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). FXR expression was detected by western blot and immunohistochemistry. The mRNA levels of SIRT1 and FXR were detected by polymerase chain reaction. Protein expression of SIRT1, FoxM1, NF-κB, acetyl-NF-κB, p53, and acetyl-p53 was analyzed by western blot. Hepatocyte apoptosis and proliferation were measured by TUNEL assay and Ki-67 staining, respectively. Serum and supernatant cytokines were analyzed using ELISA assays. Liver injury was also assessed. To investigate the possible mechanisms, SIRT1 agonist (SRT1720), SIRT1 inhibitor (EX527), and FXR inhibitor (Z-guggulsterone) were used.

RESULTS

Tauroursodeoxycholic acid (TUDCA) in the liver decreased significantly after HS. SIRT1 and FXR expression was time-dependently downregulated by HS or hypoxia condition. TUDCA upregulated SIRT1-FXR activity, which inhibited expression and acetylation of NF-κB and p53 and increased FoxM1 expression, leading to decreased inflammatory response and apoptosis and increased proliferative capacity in hepatocytes, and attenuation of liver injury. EX527 pretreatment reversed the protective effect of TUDCA. Moreover, Z-guggulsterone supplementation decreased the protective effect of TUDCA in vitro.

CONCLUSION

TUDCA in the liver decreased during HS. TUDCA supplementation might attenuate HS-induced liver injury by upregulating SIRT1-FXR signaling.

Carbon Monoxide-Releasing Molecule-3 Ameliorates Acute Lung Injury in a Model of Hemorrhagic Shock and Resuscitation: Roles of p38MAPK Signaling Pathway

OBJECTIVE

It was reported that carbon monoxide-releasing molecule-3 (CORM-3) administration immediately after hemorrhagic shock and resuscitation (HSR) ameliorates the HSR-induced acute lung injury (ALI); however, the specific mechanism of the protective effects against HSR-induced ALI remains unclear.

METHODS

To induce hemorrhagic shock, rats were bled to a mean arterial blood pressure of 30 mm Hg for 45 min and then resuscitated with shed blood via the left vein. CORM-3 (4 mg/kg or 8 mg/kg) was respectively administrated after HSR. Twelve  hours post-HSR, lung injury was assessed by wet/dry (W/D) ratio, hematoxylin-eosin staining staining, and lung ultrasound; the apoptotic and pyroptotic macrophages were measured by immunofluorescence staining; and the expression of phosphorylated p38 mitogen activated protein kinase (p-p38MAPK) and total p38MAPK was measured by western blotting. SB203580 (5 mg/kg), a special inhibitor of p-p38MAPK, was administrated by abdominal cavity to assess the roles of p38MAPK in HSR-induced ALI.

RESULTS

Increased B-line score, lung injury score, and W/D ratio indicated the fact of ALI after HSR. Twelve hours post-HSR, CORM-3 administration significantly decreased the B-line score, lung injury score, W/D ratio, apoptotic and pyroptotic macrophages, and the expressions of p-p38MAPK. Further, SB203580 not only reduced HSR-induced ALI, but also enhanced the protective effects of CORM-3 against ALI.

CONCLUSION

We identified the protective effects of CORM-3 against HSR-induced ALI. The mechanism might be related to the inhibition of p38MAPK signaling pathway in lung macrophages.

Carbon monoxide-releasing molecule-3 protects against cortical pyroptosis induced by hemorrhagic shock and resuscitation via mitochondrial regulation

OBJECTIVE

Carbon monoxide (CO) releasing molecule (CORM)-3, a water-soluble CORM, has protective effects against inflammatory and ischemia/reperfusion injury. We determined the effect of CORM-3 against neuronal pyroptosis in a model of hemorrhagic shock and resuscitation (HSR) in rats via mitochondrial regulation.

METHODS

Rats were treated with CORM-3 (4 mg/kg) in vitro after HSR. We measured cortical CO content 3-24 h after HSR; assessed neuronal pyroptosis, mitochondrial morphology, ROS production, and mitochondrial membrane potential at 12 h after HSR; and evaluated brain magnetic resonance imaging at 24 h after HSR and learning ability 30 days after HSR. We also measured soluble guanylate-cyclase (sGC)-cyclic guanosine monophosphate (cGMP) signaling pathway activity using a blocker of sGC, NS2028, and ¹²⁵I-cGMP assay.

RESULTS

Among rats that underwent HSR, CORM-3-treated rats had more CO in the cortical tissue than sham- and iCORM-3-treated rats. CORM-3-treated rats had significantly less neuronal pyroptosis in the cortical tissue; higher sGC activity and cGMP content; lower ROS production; better mitochondrial morphology, function, and membrane potential; and enhanced learning/memory ability than HSR-treated rats. However, these neuroprotective effects of CORM-3 were partially inhibited by NS2028.

CONCLUSION

CORM-3 may alleviate neuronal pyroptosis and improve neurological recovery in HSR through mitochondrial regulation mediated by the sGC-cGMP pathway. Thus, CO administration could be a promising therapeutic strategy for hemorrhagic shock.

Therapeutic effect of carbon monoxide-releasing molecule-3 on acute lung injury after hemorrhagic shock and resuscitation

Hemorrhagic shock and resuscitation (HSR) induces a pulmonary inflammatory response and frequently causes acute lung injury. Carbon monoxide-releasing molecule-3 (CORM-3) has been reported to liberate and deliver CO under physiological conditions, which exerts organ-protective effects during systemic insults. The present study aimed to determine whether the administration of CORM-3 following HSR exerts a therapeutic effect against HSR-induced lung injury without any detrimental effects on oxygenation and hemodynamics. To induce hemorrhagic shock, rats were bled to a mean arterial blood pressure of 30 mmHg for 45 min and then resuscitated with the shed blood. CORM-3 or a vehicle was intravenously administered immediately following the completion of resuscitation. The rats were divided into four groups, including sham, HSR, HSR/CORM-3 and HSR/inactive CORM-3 groups. Arterial blood gas parameters and vital signs were recorded during HSR. The histopathological changes to the lungs were evaluated using a lung injury score, while pulmonary edema was evaluated on the basis of the protein concentration in bronchoalveolar lavage fluid and the lung wet/dry ratio. We also investigated the pulmonary expression levels of inflammatory mediators and apoptotic markers such as cleaved caspase-3 and transferase-mediated dUTP-fluorescein isothiocyanate nick-end labeling (TUNEL) staining. Although HSR caused significant lung histopathological damage and pulmonary edema, CORM-3 significantly ameliorated this damage. CORM-3 also attenuated the HSR-induced upregulation of tumor necrosis factor-α, inducible nitric oxide synthase and interleukin-1β genes, and the expression of interleukin-1β and macrophage inflammatory protein-2. In addition, the expression of interleukin-10, an anti-inflammatory cytokine, was inversely enhanced by CORM-3, which also reduced the number of TUNEL-positive cells and the expression of cleaved caspase-3 following HSR. Although CORM-3 was administered during the acute phase of HSR, it did not exert any influence on arterial blood gas analysis data and vital signs during HSR. Therefore, treatment with CORM-3 ameliorated HSR-induced lung injury, at least partially, through anti-inflammatory and anti-apoptotic effects, without any detrimental effects on oxygenation and hemodynamics.

Lactated Ringer' Solution may be Superior to Saline-Based 6% Hydroxyethyl Starch 130/0.4 for Early Resuscitation within 12 hours from Hemorrhagic Shock

Purpose: To compare the effects of fluid resuscitation with lactated Ringer's solution (LR) and saline-based 6% hydroxyethyl starch 130/0.4 (HES) on the inflammatory response and oxidative stress in the small intestine as well as on bacterial translocation to the liver. Methods: Sprague-Dawley rats were subjected to blood pressure-controlled hemorrhagic shock and then resuscitated with LR or HES. At 1, 3, 6, 12, and 24 hr after resuscitation, liver tissues were collected to count the bacterial colonies, and small intestines were harvested to analyze the levels of inflammatory (TNF-α and HO-1) and oxidative stress (MPO) mediators as well as the intestinal injury by immunohistochemistry, colorimetry and hematoxylin & eosin staining, respectively. Results: The expression level of TNF-α in the LR group was stable from 1 to 6 hr but decreased at 12 hr and then abruptly increased at 24 hr. The expression level of TNF-α in the LR group was significantly lower than that in the HES group, especially during the first 12 hr post-fluid infusion. MPO activity decreased to its lowest level at 3 hr but increased from 6 to 12 hr, with no difference at 24 hr between the two groups. Although a decreasing tendency was observed from 6 hr, HO-1 expression levels remained higher in the LR group than in the HES group at 12 and 24 hr, particularly at 12 hr. During the initial 12 hr, the LR group exhibited significantly lower colony-forming units in the liver tissues than the HES group. Chiu's score in the intestine decreased regardless of which resuscitative fluids were used. Conclusions: During early resuscitation (within 12 hr), LR may be superior to HES in reducing intestinal injuries by suppressing inflammatory and oxidative mediators.

Hemorrhagic Shock and the Microvasculature

The microvasculature plays a central role in the pathophysiology of hemorrhagic shock and is also involved in arguably all therapeutic attempts to reverse or minimize the adverse consequences of shock. Microvascular studies specific to hemorrhagic shock were reviewed and broadly grouped depending on whether data were obtained on animal or human subjects. Dedicated sections were assigned to microcirculatory changes in specific organs, and major categories of pathophysiological alterations and mechanisms such as oxygen distribution, ischemia, inflammation, glycocalyx changes, vasomotion, endothelial dysfunction, and coagulopathy as well as biomarkers and some therapeutic strategies. Innovative experimental methods were also reviewed for quantitative microcirculatory assessment as it pertains to changes during hemorrhagic shock. The text and figures include representative quantitative microvascular data obtained in various organs and tissues such as skin, muscle, lung, liver, brain, heart, kidney, pancreas, intestines, and mesentery from various species including mice, rats, hamsters, sheep, swine, bats, and humans. Based on reviewed findings, a new integrative conceptual model is presented that includes about 100 systemic and local factors linked to microvessels in hemorrhagic shock. The combination of systemic measures with the understanding of these processes at the microvascular level is fundamental to further develop targeted and personalized interventions that will reduce tissue injury, organ dysfunction, and ultimately mortality due to hemorrhagic shock. Published 2018. Compr Physiol 8:61-101, 2018.

Diabetes-Related Induction of the Heme Oxygenase System and Enhanced Colocalization of Heme Oxygenase 1 and 2 with Neuronal Nitric Oxide Synthase in Myenteric Neurons of Different Intestinal Segments

Increase in hyperglycaemia-induced oxidative stress and decreased effectiveness of endogenous defense mechanisms plays an essential role in the initiation of diabetes-related neuropathy. We demonstrated that nitrergic myenteric neurons display different susceptibilities to diabetic damage in different gut segments. Therefore, we aim to reveal the gut segment-specific differences in the expression of heme oxygenase (HO) isoforms and the colocalization of these antioxidants with neuronal nitric oxide synthase (nNOS) in myenteric neurons. After ten weeks, samples from the duodenum, ileum, and colon of control and streptozotocin-induced diabetic rats were processed for double-labelling fluorescent immunohistochemistry and ELISA. The number of both HO-immunoreactive and nNOS/HO-immunoreactive myenteric neurons was the lowest in the ileal and the highest in the colonic ganglia of controls; it increased the most extensively in the ileum and was also elevated in the colon of diabetics. Although the total number of nitrergic neurons decreased in all segments, the proportion of nNOS-immunoreactive neurons colocalizing with HOs was enhanced robustly in the ileum and colon of diabetics. We presume that those nitrergic neurons which do not colocalize with HOs are the most seriously affected by diabetic damage. Therefore, the regional induction of the HO system is strongly correlated with diabetes-related region-specific nitrergic neuropathy.

Dynamic changes in Bach1 expression in the kidney of rhabdomyolysis-associated acute kidney injury

Free heme, a pro-oxidant released from myoglobin, is thought to contribute to the pathogenesis of rhabdomyolysis-associated acute kidney injury (RM-AKI), because renal overexpression of heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme catabolism, confers protection against RM-AKI. BTB and CNC homology 1 (Bach1) is a heme-responsive transcription factor that represses HO-1. Here, we examined the changes with time in the gene expression of Bach1, HO-1, and δ-aminolevulinate synthase (ALAS1, a heme biosynthetic enzyme) in the rat kidney using an RM-AKI model induced by the injection of 50% glycerol (10 mL/kg body weight) into bilateral limbs. We also examined the protein expression of Bach1 in the nucleus and cytosol, and HO-1 in the rat kidney. Glycerol treatment induced significant elevation of serum creatinine kinase and aspartate aminotransferase levels followed by the marked elevation of serum blood urea nitrogen and creatinine levels, which caused serious damage to renal tubules. Following glycerol treatment, HO-1 mRNA and protein levels were significantly up-regulated, while ALAS1 mRNA expression was down-regulated, suggesting an increase in the free renal heme concentration. The Bach1 mRNA level was drastically increased 3 h after glycerol treatment, and the increased level was maintained for 12 h. Nuclear Bach1 protein levels were significantly decreased 3 h after treatment. Conversely, cytosolic Bach1 protein levels abruptly increased after 6 h. In conclusion, we demonstrate the dynamic changes in Bach1 expression in a rat model of RM-AKI. Our findings suggest that the increase in Bach1 mRNA and cytosolic Bach1 protein expression may reflect de novo Bach1 protein synthesis to compensate for the depletion of nuclear Bach1 protein caused by the induction of HO-1 by free heme.

Gut region-specific accumulation of reactive oxygen species leads to regionally distinct activation of antioxidant and apoptotic marker molecules in rats with STZ-induced diabetes

The aim of this study was to seek possible links between the regionality along the digestive tract and the accumulation of reactive oxygen species, the effectiveness of the antioxidant defense system and the sensitivity to the types of demise in different gut regions of rats with streptozotocin-induced diabetes. Significant changes were observed in the oxidative status and in the activity of the antioxidant defense system in the diabetic colon; the peroxynitrite production was doubled, the level of hemoxygenase-2 protein was increased 11-fold and the expression of anti-apoptotic bcl-2 was also increased. The segment-specific vulnerability of the gastrointestinal tract induced by hyperglycemia was also confirmed by electron microscopy, demonstrating the presence of severe necrosis in the colon of the diabetic rats. No remarkable histopathological alterations were seen in the duodenum of the diabetic animals and there were likewise no significant changes in the production of peroxynitrite in their duodenum, whereas the level of the free radical scavenger metallothionein-2 was increased ∼300-fold.

CONCLUSION

The spatially restricted vulnerability observed along the digestive tract could originate from a high level of oxidative stress via peroxynitrite production.

Pharmacological preconditioning with vitamin C attenuates intestinal injury via the induction of heme oxygenase-1 after hemorrhagic shock in rats

Pre-induction of heme oxygenase (HO)-1, which is regarded as an effective method of “organ preconditioning”, exerts beneficial effects during hemorrhagic shock (HS). However, the available HO-1 inducers exhibit disadvantages such as toxicity or complex technical requirements. Therefore, a safe and convenient HO-1 inducer would be promising and could be exploited in the treatment of foreseeable hemorrhaging, such as prior to major surgery. Here we investigated the effect of vitamin C (VitC), a common antioxidant, on intestinal HO-1 expression and examined whether VitC pretreatment prevented HS related intestinal tissue injuries after HO-1 induction. First, we conducted an in vitro study and found that HO-1 expression in rat intestinal epithelial cells (IEC-6) was induced by non-toxic VitC in a time and concentration dependent manner, and the mechanism was related to the activation of extracellular signal-regulated kinase 1/2 (ERK1/2). Next, we conducted an in vivo study and found that VitC induced intestinal HO-1 protein expression (mainly observed in the intestinal epithelial cells) and HO-1 activity in normal SD rats, and that these HO-1 levels were further enhanced by VitC in a rat model of HS. The HS related intestinal injuries, including histological damage, pro-inflammatory cytokine levels (tumor necrosis factor and interleukin-6), neutrophil infiltration and apoptosis decreased after VitC pretreatment, and this alleviating of organ injuries was abrogated after the inhibition of HO-1 activity by zinc protoporphyrin-IX. It was of note that VitC did little histological damage to the intestine of the sham rats. These data suggested that VitC might be applied as a safe inducer of intestinal HO-1 and that VitC pretreatment attenuated HS related intestinal injuries via the induction of HO-1.

Regional susceptibility to stress-induced intestinal injury in the mouse

Injury to the intestinal mucosa is a life-threatening problem in a variety of clinical disorders, including hemorrhagic shock, trauma, burn, pancreatitis, and heat stroke. The susceptibility to injury of different regions of intestine in these disorders is not well understood. We compared histological injury across the small intestine in two in vivo mouse models of injury, hemorrhagic shock (30% loss of blood volume) and heat stroke (peak core temperature 42.4°C). In both injury models, areas near the duodenum showed significantly greater mucosal injury and reductions in villus height. To determine if these effects were dependent on circulating factors, experiments were performed on isolated intestinal segments to test for permeability to 4-kDa FITC-dextran. The segments were exposed to hyperthermia (42°C for 90 min), moderate simulated ischemia (Po2 ∼30 Torr, Pco2 ∼60 Torr, pH 7.1), severe ischemia (Po2 ∼20 Torr, Pco2 ∼80 Torr, pH 6.9), or severe hypoxia (Po2 ∼0 Torr, Pco2 ∼35 Torr) for 90 min, and each group was compared with sham controls. All treatments resulted in marked elevations in permeability within segments near the duodenum. In severe hypoxia or hyperthermia, permeability was also moderately elevated in the jejunum and ileum; in moderate or severe ischemia, permeability was unaffected in these regions. The results demonstrate increased susceptibility of proximal regions of the small intestine to acute stress-induced damage, irrespective of circulating factors. The predominant injury in the duodenum may impact the pattern of acute inflammatory responses arising from breach of the intestinal barrier, and such knowledge may be useful for designing therapeutic strategies.

The role of toll-like receptor-4 in the development of multi-organ failure following traumatic haemorrhagic shock and resuscitation

Haemorrhagic shock and resuscitation (HS/R) following major trauma results in a global ischaemia and reperfusion injury that may lead to multiple organ dysfunction syndrome (MODS). Systemic activation of the immune system is fundamental to the development of MODS in this context, and shares many features in common with the systemic inflammatory response syndrome (SIRS) that complicates sepsis. An important advancement in the understanding of the innate response to infection involved the identification of mammalian toll-like receptors (TLRs) expressed on cells of the immune system. Ten TLR homologues have been identified in humans and toll-like receptor-4 (TLR4) has been studied most intensively. Initially found to recognise bacterial lipopolysaccharide (LPS), it has also recently been discovered that TLR4 is capable of activation by endogenous 'danger signal' molecules released following cellular injury; this has since implicated TLR4 in several non-infectious pathophysiologic processes, including HS/R. The exact events leading to multi-organ dysfunction following HS/R have not yet been clearly defined, although TLR4 is believed to play a central role as has been shown to be expressed at sites including the liver, lungs and myocardium following HS/R. Multi-organ dysfunction syndrome remains an important cause of morbidity and mortality in trauma patients, and current therapy is based on supportive care. Understanding the pathophysiology of HS/R will allow for the development of targeted therapeutic strategies aimed at minimising organ dysfunction and improving patient outcomes following traumatic haemorrhage. A review of the pathogenesis of haemorrhagic shock is presented, and the complex, yet critical role of TLR4 as both a key mediator and therapeutic target is discussed.

Translocation of heme oxygenase-1 to mitochondria is a novel cytoprotective mechanism against non-steroidal anti-inflammatory drug-induced mitochondrial oxidative stress, apoptosis, and gastric mucosal injury

The mechanism of action of heme oxygenase-1 (HO-1) in mitochondrial oxidative stress (MOS)-mediated apoptotic tissue injury was investigated. MOS-mediated gastric mucosal apoptosis and injury were introduced in rat by indomethacin, a non-steroidal anti-inflammatory drug. Here, we report that HO-1 was not only induced but also translocated to mitochondria during gastric mucosal injury to favor repair mechanisms. Furthermore, mitochondrial translocation of HO-1 resulted in the prevention of MOS and mitochondrial pathology as evident from the restoration of the complex I-driven mitochondrial respiratory control ratio and transmembrane potential. Mitochondrial translocation of HO-1 also resulted in time-dependent inhibition of apoptosis. We searched for the plausible mechanisms responsible for HO-1 induction and mitochondrial localization. Free heme, the substrate for HO-1, was increased inside mitochondria during gastric injury, and mitochondrial entry of HO-1 decreased intramitochondrial free heme content, suggesting that a purpose of mitochondrial translocation of HO-1 is to detoxify accumulated heme. Heme may activate nuclear translocation of NF-E2-related factor 2 to induce HO-1 through reactive oxygen species generation. Electrophoretic mobility shift assay and chromatin immunoprecipitation studies indicated nuclear translocation of NF-E2-related factor 2 and its binding to HO-1 promoter to induce HO-1 expression during gastric injury. Inhibition of HO-1 by zinc protoporphyrin aggravated the mucosal injury and delayed healing. Zinc protoporphyrin further reduced the respiratory control ratio and transmembrane potential and enhanced MOS and apoptosis. In contrast, induction of HO-1 by cobalt protoporphyrin reduced MOS, corrected mitochondrial dysfunctions, and prevented apoptosis and gastric injury. Thus, induction and mitochondrial localization of HO-1 are a novel cytoprotective mechanism against MOS-mediated apoptotic tissue injury.

Intestinal epithelial cell proliferation, apoptosis and expression of tight junction proteins in patients with obstructive jaundice

BACKGROUND

Intestinal hyperpermeability has been repeatedly confirmed in patients with obstructive jaundice and is considered a pivotal factor in the development of septic and renal complications in these patients. However, little is known on the mechanism(s) leading to this phenomenon. This study was undertaken to investigate the cellular and subcellular intestinal alterations in patients with obstructive jaundice.

DESIGN

Sixteen patients with obstructive jaundice of malignant (n = 8, group A) or benign (n = 8, group B) aetiology, without concomitant cholangitis, and eight healthy controls (group C) were subjected to duodenal biopsy distal to the ampulla of Vater. Specimens were examined histologically and the apoptotic activity in the cryptal epithelium was recorded. Epithelial proliferation was evaluated by immunohistochemical expression of Ki67 antigen. The expression of the tight junction (TJ) proteins occludin, claudin-1, claudin-4 and claudin-7 in the intestinal epithelium was also evaluated by immunohistochemistry.

RESULTS

Patients with malignant or benign obstructive jaundice presented significantly decreased intestinal epithelial cell proliferation rates compared with controls (P < 0·05), whereas no differences were detected in apoptotic activity. In a semiquantitative analysis of TJ protein expression, occludin, claudin-1 and -7 were significantly decreased (P < 0·001), whereas claudin-4 was significantly increased (P < 0·01) in jaundiced patients and their distribution was altered. No differences were detected between patients with malignant or benign obstructive jaundice for all intestinal barrier parameters studied.

CONCLUSION

Decreased enterocyte proliferation and altered TJ protein expression might represent important mechanisms for intestinal barrier dysfunction and hyperpermeability in patients with extrahepatic cholestasis. The potential pharmacological modulation of these factors may lead to better control of intestinal permeability in the jaundiced patient with improved clinical outcome.

Carbon monoxide involved in modulating HCO3- secretion in rat duodenum

We examined the effect of the tricarbonyl-dichlororuthenium (II) dimer (CORM-2), a carbon monoxide (CO) donor, on duodenal HCO(3)(-) secretion in rats and investigated whether endogenous CO produced by heme oxygenase (HO) is involved in the regulation of this secretion. Under urethane anesthesia, a duodenal loop was perfused with saline, and HCO(3)(-) secretion was measured at pH 7.0 using a pH stat method. CORM-2, biliverdin, FeCl(2), or ruthenium (III) chloride hydrate (RuCl(3)) was applied to the loop for 5 min. The mucosal application of CORM-2 dose-dependently increased HCO(3)(-) secretion, whereas neither RuCl(3), FeCl(2), nor biliverdin had an effect. The stimulatory effect was significantly attenuated by indomethacin but not N(G)-nitro-L-arginine methyl ester. The application of CORM-2 increased the mucosal prostaglandin (PG) E(2) content of the duodenum. The acid-induced HCO(3)(-) response was markedly inhibited by indomethacin and Sn(IV) protoporphyrin IX dichloride (SnPP; an inhibitor of HO) but not Cu(II) protoporphyrin dichloride, and the inhibitory effect of SnPP was significantly reversed by pretreatment with hemin, a substrate of HO. Perfusion of the duodenal loop with 100 mM HCl for 2 h caused a few hemorrhagic lesions in the mucosa, and this response was significantly worsened by the prior administration of SnPP and indomethacin. The expression of HO-1 but not HO-2 protein was up-regulated in the duodenum after the acid treatment. These results suggest that CO, generated endogenously or exogenously, stimulates HCO(3)(-) secretion in the duodenum, and this effect is mediated by endogenous PGs. It is assumed that HO/CO plays a role in maintaining the integrity of the duodenal mucosa.

HIF-1 mediates pathogenic inflammatory responses to intestinal ischemia-reperfusion injury

Acute lung injury (ALI) and the development of the multiple organ dysfunction syndrome (MODS) are major causes of death in trauma patients. Gut inflammation and loss of gut barrier function as a consequence of splanchnic ischemia-reperfusion (I/R) have been implicated as the initial triggering events that contribute to the development of the systemic inflammatory response, ALI, and MODS. Since hypoxia-inducible factor (HIF-1) is a key regulator of the physiological and pathophysiological response to hypoxia, we asked whether HIF-1 plays a proximal role in the induction of gut injury and subsequent lung injury. Utilizing partially HIF-1α-deficient mice in a global trauma hemorrhagic shock (T/HS) model, we found that HIF-1 activation was necessary for the development of gut injury and that the prevention of gut injury was associated with an abrogation of lung injury. Specifically, in vivo studies demonstrated that partial HIF-1α deficiency ameliorated T/HS-induced increases in intestinal permeability, bacterial translocation, and caspase-3 activation. Lastly, partial HIF-1α deficiency reduced TNF-α, IL-1β, cyclooxygenase-2, and inducible nitric oxide synthase levels in the ileal mucosa after T/HS whereas IL-1β mRNA levels were reduced in the lung after T/HS. This study indicates that prolonged intestinal HIF-1 activation is a proximal regulator of I/R-induced gut mucosal injury and gut-induced lung injury. Consequently, these results provide unique information on the initiating events in trauma-hemorrhagic shock-induced ALI and MODS as well as potential therapeutic insights.

Prevention of hemorrhagic shock-induced intestinal tissue injury by glutamine via heme oxygenase-1 induction

Hemorrhagic shock (HS) is an oxidative stress that causes intestinal tissue injury. Heme oxygenase 1 (HO-1) is induced by oxidative stress and is thought to play an important role in the protection of tissues from oxidative injury. We previously reported the ileum to be the most susceptible to HS-induced tissue injury site in the intestine because HO-1 induction is the lowest at this site. We also previously demonstrated that glutamine (GLN) significantly induced HO-1 in the lower intestinal tract. In the present study, we investigated whether GLN pretreatment improves HS-induced intestinal tissue injury in the ileum by HO-1 induction. Treatment of rats with GLN (0.75 g/kg, i.v.) markedly induced functional HO-1 protein in mucosal epithelial cells in the ileum. Glutamine treatment before HS (MAP of 30 mmHg for 60 min) significantly ameliorated HS-induced mucosal inflammation and apoptotic cell death in the ileum, as judged by significant decreases in gene expression of TNF-alpha, iNOS, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1, myeloperoxidase activity, the number of infiltrated neutrophils, DNA fragmentation by in situ oligo ligation assay, and activated caspase-3 expression, and by increases in gene expression of IL-10 and Bcl-2. In contrast, treatment with tin mesoporphyrin, a specific inhibitor of HO activity, abolished the beneficial effect of GLN pretreatment. These findings indicate that GLN pretreatment significantly ameliorated tissue injury in the ileum after HS by inducing HO-1. Glutamine treatment may thus protect mucosal cells from HS-induced oxidative damage via the anti-inflammatory and antiapoptotic properties of HO-1.

Heme oxygenase-1 induction in macrophages by a hemoglobin-based oxygen carrier reduces endotoxin-stimulated cytokine secretion

The inflammatory response after an insult may provoke further tissue damage, and the macrophage is central in this pathophysiology. Induction of heme oxygenase-1 (HO-1) attenuates postshock organ dysfunction, although the mechanism remains unclear. We hypothesized that HO-1 induction modifies the cytokine profile of LPS-stimulated macrophages. Heme oxygenase-1 was induced in murine and human macrophages with varying concentrations of a hemoglobin-based oxygen carrier (HBOC). Heme oxygenase-1 expression was analyzed by Western blotting of whole cell lysates. Macrophages were pretreated with HBOC for 4 h, then media with LPS were added for up to 24 h. The specific HO-1 inhibitor zinc protoporphyrin (ZnPP) was used to inhibit the effects of HO-1. Supernatants were analyzed for IL-6, IL-10, TNF-alpha, and monocyte chemotactic protein 1 (MCP-1) by enzyme-linked immunosorbent assay. Incubation of cells with HBOC produced a dose-dependent expression of HO-1. Heme oxygenase-1 expression decreased LPS-stimulated secretion of MCP-1, IL-6, IL-10, and TNF-alpha at both 4 and 24 h in murine and human macrophages. The addition of ZnPP to inhibit HO-1 partially restored MCP-1 and IL-6 secretion in murine macrophages. Furthermore, immunofluorescent microscopy revealed HBOC-induced HO-1 inhibited LPS-stimulated nuclear translocation of the p65 subunit of nuclear factor-kappaB. In summary, HBOC incubation of macrophages induced HO-1 expression, which reduced LPS-mediated cytokine release, and that MCP-1 and IL-6 secretion could be partially restored with ZnPP. These data encourage continued investigation into the role of HO-1 in protecting against posttraumatic organ dysfunction and the clinical potential of HBOC for HO-1 induction.

Research progress of enteric nervous system in esophagus

The functions of esophageal peristalsis and contraction were regulated and controlled by both neural and humoral system at all levels. Esophageal function depends on coordination of all the effectors regulated by enteric nervous system (ENS). Esophageal neurons are generally divided into two groups: the excitatory neurons and the inhibitory neurons. They regulate the tone, peristalsis and contraction of esophagus by interaction of various neurotransmitters. This article reviews recent research advancement of ENS in esophagus.

Hindlimb ischemia/reperfusion-induced remote injury to the small intestine: role of inducible nitric-oxide synthase-derived nitric oxide

Systemic inflammatory response syndrome, as a consequence of ischemia/reperfusion (I/R), negatively influences the function of the affected organs. The objective of this study was to assess the role of nitric oxide (NO) in remote intestinal inflammatory response elicited by hindlimb I/R. To this end, C57BL/6 (wild type; WT) and inducible nitric-oxide synthase (iNOS)-deficient mice were subjected to bilateral hindlimb ischemia (1 h) followed by 6 h of reperfusion. Some WT mice were injected with iNOS inhibitor N-[3-(aminomethyl)benzyl] acetamidine (1400W) (5 mg/kg s.c.) immediately before reperfusion, and proinflammatory response was assessed 6 h later. Hindlimb I/R resulted in dysfunction of the small intestine as assessed by the increase in permeability [blood-to-lumen clearance of Texas Red-dextran (molecular mass 3 kDa)] and an increase in the luminal levels of tumor necrosis factor (TNF)-alpha protein and nitrate/nitrite (NO(2)(-)/NO(3)(-)). The above-mentioned changes were accompanied by up-regulation of the proinflammatory phenotype in the mucosa of small intestine with respect to 1) an increase in TNF-alpha and iNOS protein expression, 2) leukocyte accumulation, 3) formation of edema, 4) an increase in leukocyte rolling/adhesion in the submucosal microvasculature, and 5) activation of transcription factor nuclear factor-kappaB and up-regulation of adhesion molecule expression. Interestingly, the most profound changes with respect to intestinal dysfunction were found in jejunum and ileum, whereas duodenum was affected the least. Interfering with iNOS activity (1400W and iNOS-deficient mice) significantly attenuated hindlimb I/R-induced inflammatory response and dysfunction of the small intestine with respect to the above-mentioned markers of inflammation. The obtained results indicate that hindlimb I/R induces remote inflammatory response in the small intestine through an iNOS-derived NO-dependent mechanism.

Transcriptional responses associated with sulfur mustard and thermal burns in porcine skin

In military and civilian environments, serious cutaneous damage can result from thermal burns or exposure to the blistering agent sulfur mustard [bis (2-chloroethyl) sulfide; HD]. Similar therapies have historically been used to treat cutaneous thermal and HD injuries; however, the underlying molecular mechanisms of tissue damage and wound healing may differ between the types of burns. Using microarray analysis, this study assessed the transcriptional responses to cutaneous HD and thermal injury at 48 hours post-exposure to identify molecular networks and genes associated with each type of skin injury. Ventral abdominal sites on each of 4 weanling swine were exposed to 400 mul of undiluted HD or a heated brass rod (70 degrees C) for 8 minutes and 45-60 seconds, respectively. At 48 hours post-exposure, total RNA was isolated from excised skin samples and hybridized to Affymetrix GeneChip Porcine Genome Arrays (containing 20,201 genes). Both HD and thermal exposure promoted significant transcriptional changes where 290 and 267 transcripts were increased and 197 and 707 transcripts were decreased with HD and thermal exposure, respectively. HD- and thermal-injured skin expressed 149 increased and 148 decreased common transcripts. Comparison of the 10 most significantly changed biological functions for HD and thermal exposures identified 7 overlapping functional groups. Canonical pathways analysis revealed 15 separate signaling pathways containing transcripts associated with both HD and thermal exposure. Within these pathways, 5 transcripts (CXCR4, FGFR2, HMOX1, IL1R1, and TLR4) were identified as known targets for existing phase II/III clinical trial or Food and Drug Administration (FDA)-approved drugs. This study is the first to directly assess transcriptional changes in porcine skin subjected to HD or thermal injury over the same time period.

Heme Oxygenase-1 is an Essential Cytoprotective Component in Oxidative Tissue Injury Induced by Hemorrhagic Shock

Hemorrhagic shock causes oxidative stress that leads to tissue injuries in various organs including the lung, liver, kidney and intestine. Excess amounts of free heme released from destabilized hemoproteins under oxidative conditions might constitute a major threat because it can catalyze the formation of reactive oxygen species. Cells counteract this by rapidly inducing the rate-limiting enzyme in heme breakdown, heme oxygenase-1 (HO-1), which is a low-molecular-weight stress protein. The enzymatic HO-1 reaction removes heme. As such, endogenous HO-1 induction by hemorrhagic shock protects tissues from further degeneration by oxidant stimuli. In addition, prior pharmacological induction of HO-1 ameliorates oxidative tissue injuries induced by hemorrhagic shock. In contrast, the deletion of HO-1 expression, or the chemical inhibition of increased HO activity ablated the beneficial effect of HO-1 induction, and exacerbates tissue damage. Thus, HO-1 constitutes an essential cytoprotective component in hemorrhagic shock-induced oxidative tissue injures. This article reviews recent advances in understanding of the essential role of HO-1 in experimental models of hemorrhagic shock-induced oxidative tissue injuries with emphasis on the role of its induction in tissue defense.