Application of heme oxygenase-1, carbon monoxide and biliverdin for the prevention of intestinal ischemia/reperfusion injury

Hydrogen-enriched preservation protects the isogeneic intestinal graft and amends recipient gastric function during transplantation

BACKGROUND

Inhaled hydrogen gas exerts antioxidant and anti-inflammatory effects in rat intestinal transplantation. Here, we investigated whether ex vivo donor organ treatment with dissolved hydrogen would prevent intestinal graft injury.

METHODS

Isogeneic intestinal transplantation was performed in Lewis rats with vascular flush, luminal preservation, and cold graft storage in nitrogen-bubbled (SITxN2) or hydrogen-bubbled (SITxH2) preservation solution. Lactated Ringer's solution and 3-hr cold ischemia time were used for mechanistic investigations, whereas survival experiments were performed with University of Wisconsin solution and 6-hr cold ischemia time.

RESULTS

During the early phase of ischemia-reperfusion injury, hydrogen-enriched solution significantly preserved mucosal graft morphology, diminished graft malondialdehyde levels demonstrating substantial reduction potential and blunted proinflammatory molecular responses (early growth response gene [EGR-1], interleukin [IL]-6, IL-1ß, and inducible nitric oxide synthase) within the reperfused intestinal graft muscularis. During the late phase of ischemia-reperfusion injury, circulating IL-6 protein and lactate dehydrogenase levels were significantly ameliorated in SITxH2 animals, which were associated with a favorable functional outcome in in vivo liquid gastrointestinal transit and recipient solid gastric emptying of chrome steel balls, and marked prevention of the posttransplant associated suppression of in vitro muscarinic jejunal contractility. Reflecting improved graft preservation, hydrogen preloading of grafts increased recipient survival rates from 41% to 80%. Anti-inflammatory and antiapoptotic heme oxygenase-1 was significantly upregulated in the hydrogen-treated graft muscularis but not mucosa before reperfusion.

CONCLUSIONS

Graft preloading with hydrogen demonstrated superior morphologic and functional graft protection in rodent intestinal transplantation, ultimately facilitating recipient survival. Antioxidant capacity and muscularis heme oxygenase-1 upregulation are possible protective mechanisms.

Heme oxygenase-1 expression and its significance for acute rejection following kidney transplantation in rats

OBJECTIVE

To analyze rejection and antiapoptotic effects of heme oxygenase-1 (HO-1) in kidney transplantations, to investigate the protective effects of endogenous HO-1 induced by hemin on acute rat kidney allograft rejection.

METHODS

We selected 27 Brown-Norway rats and 27 male Lewis rats as donors and recipients, respectively, randomly dividing them into three groups: kidney transplantation alone, hemin treatment group, and cyclosporine (CsA) group (n = 18). Six recipient rats were harvested on the first, fifth, or seventh days after operation among each group to examine histopathologic changes in renal tissue, HO-1 protein expression, and acute rejection as well as to measure serum creatinine values.

RESULTS

HO-1 expression in both the kidney transplantation model group and the hemin-induced groups were higher compared with the CsA group (P < .05-.01). The expression increased with the aggravation of rejection; the expression in the CsA group also increased after transplantation but was obviously lower than that of the hemin-induced group (P < .01). The rejection process was relatively mild as indenset by histopathologic examination. The serum creatinine levels among the hemin-induced group were lower compared to the kidney transplantation control group (P < .05), but higher compared to the CsA group (P < .05).

CONCLUSION

HO-1 provided protection of allografts against rejection in rats, but such effects were poorer than those achieved using potent immunosuppressive agents like CsA.

Divergent role of heme oxygenase inhibition in the pathogenesis of sepsis

The reduction of neutrophil migration to an infectious focus is associated with a high mortality in severe sepsis. Previously, we showed that heme oxygenase (HO) products downregulate neutrophil recruitment in a noninfectious inflammatory model. The present study was designed to determine the role of HO in sepsis induced by cecal ligation and puncture (CLP) model. We demonstrated that pretreatment, but not the combination of pretreatment plus posttreatment with zinc protoporphyrin IX (ZnPP IX), an HO inhibitor, prevented the reduction of CXCR2 on circulating neutrophils and the failure of intraperitoneal neutrophil migration to the site of infection. Consequently, bacterial dissemination, systemic inflammatory response, and organ injury were prevented. In addition, pretreatment with the HO inhibitor avoided hypotension and consequently increased survival. Moreover, in mice subjected to severe CLP, the pretreatment, but not the combination of pretreatment plus posttreatment with ZnPP IX, prevented the increase of plasmatic free heme observed in nontreated severe CLP. The administration of exogenous hemin to mice subjected to moderate sepsis consistently increased the mortality rate. Furthermore, hemin resulted in a reduction of neutrophil migration both in vivo and in vitro. Altogether, our results demonstrated that pretreatment with the HO inhibitor prevents the pathological findings in severe CLP. However, the combination of pretreatment plus posttreatment with ZnPP IX enhances sepsis severity because of an increase in circulating levels of heme, which is deleterious to the host tissues and also inhibits neutrophil migration.

Ischemic preconditioning and remote ischemic preconditioning have protective effect against cold ischemia-reperfusion injury of rat small intestine

PURPOSE

To investigate the protective effect of ischemic preconditioning (IPC) and remote ischemic preconditioning (RIPC) against cold ischemia-reperfusion injury (IRI) associated with small bowel transplantation (SBT).

METHODS

Male Lewis rats weighing 200-300 g were used for this study. The rats were assigned to three groups: control, ischemic preconditioning (IPC), or remote ischemic preconditioning (RIPC). Heterotopic SBT was thereafter performed. The recipient rats were killed 3, 6, 12 and 24 h after transplantation. Specimens from the intestine were histologically scored according to a grading system (Park et al.). Serum lactate dehydrogenase (LDH), aspirate aminotransferase (AST), alanine aminotransferase (ALT) were examined and heme oxygenase-1 (HO-1) were analyzed by ELISA where HO-1 served as an indicator of protection against IRI.

RESULTS

The values of tissue injury were significantly lower in the IPC and RIPC groups than in control group at 3 h after SBT. The serum LDH, AST and ALT levels also significantly decreased in the IPC and RIPC groups at 3 h after SBT, but these protective effects against cold IRI diminished by 12 and 24 h after SBT. The serum HO-1 level significantly increased in the IPC and RIPC groups 3 h after SBT.

CONCLUSION

Both IPC and RIPC were found to ameliorate ischemia-reperfusion injury after rat SBT in the early phase. HO-1 may therefore play a protective role against cold IRI.

Carbon monoxide liberated from carbon monoxide-releasing molecule exerts an anti-inflammatory effect on dextran sulfate sodium-induced colitis in mice

BACKGROUND

Endogenous carbon monoxide (CO) is one of the three products of heme degradation by heme oxygenase-1 (HO-1) and exerts novel anti-inflammatory and anti-apoptotic effects as a gaseous second messenger. The purpose of this investigation was to determine whether exogenous CO could modulate intestinal inflammation.

METHODS

Acute colitis was induced with 2% DSS in male C57BL/6 mice. CO-releasing molecule-2 (CORM-2; tricarbonyldichlororuthenium(II) dimer) was intraperitoneally administered twice daily and the disease activity index (DAI) was determined. We measured tissue-associated myeloperoxidase (MPO) activity as an index of neutrophil infiltration, and the production of keratinocyte chemoattractant (KC) and tumor necrosis factor-α (TNF-α) protein in the intestinal mucosa. In an in-vitro study, young adult mouse colonic epithelial (YAMC) cells were incubated with TNF-α, and KC mRNA/protein expression and nuclear translocation of nuclear factor-kappa B (NF-κB) were measured with or without CORM-2 treatment.

RESULTS

After DSS administration, DAI score increased in a time-dependent manner, and this increase was ameliorated by CORM-2 treatment. Increases in MPO activity and in the production of KC and TNF-α after DSS administration were significantly inhibited by CORM-2. TNF-α-induced KC production in YAMC cells was also inhibited by CORM-2 treatment. Further, nuclear translocation of NF-κB in YAMC cells was inhibited by CORM-2.

CONCLUSION

CORM-liberated CO significantly inhibited inflammatory response in murine colitis by inhibition of cytokine production in the colonic epithelium. These results suggest that CO could become a new therapeutic molecule for inflammatory bowel disease.

The role of heme oxygenase and carbon monoxide in inflammatory bowel disease

Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease, is a chronic and recurrent inflammatory disorder of the intestinal tract. Since the precise pathogenesis of IBD remains unclear, it is important to investigate the pathogenesis of IBD and to evaluate new anti-inflammatory strategies. Recent evidence suggests that heme oxygenase-1 (HO-1) plays a critical protective role during the development of intestinal inflammation. In fact, it has been demonstrated that the activation of HO-1 may act as an endogenous defensive mechanism to reduce inflammation and tissue injury in various animal intestinal injury models induced by ischemia-reperfusion, indomethacin, lipopolysaccharide-associated sepsis, trinitrobenzene sulfonic acid or dextran sulfate sodium. In addition, carbon monoxide (CO) derived from HO-1 has been shown to be involved in the regulation of intestinal inflammation. Furthermore, administration of a low concentration of exogenous CO has a protective effect against intestinal inflammation. These data suggest that HO-1 and CO may be novel therapeutic molecules for patients with gastrointestinal inflammatory diseases. In this review, we present what is currently known regarding the role of HO-1 and CO in intestinal inflammation.

Protection against lung graft injury from brain-dead donors with carbon monoxide, biliverdin, or both

BACKGROUND

The process of brain death can induce acute lung injury in donors and aggravate ischemia-reperfusion injury in grafts. Carbon monoxide (CO) and biliverdin (BV) have been shown to attenuate ischemia-reperfusion injury. We therefore examined if the administration of both CO and BV provide enhanced cytoprotection against lung graft injury from brain-dead (BD) rat donors.

METHODS

Brain death was induced in all donors, after which they were observed for 1.5 hours and then underwent lung transplantation. The recipients were ventilated with 40% oxygen (control group), ventilated with 250 ppm CO in 40% oxygen (CO group), treated with BV (35 mg/kg) intraperitoneally (BV group), or treated with CO and BV conjointly (COBV group) before transplantation (n = 8 each group). The recipients were sacrificed 2 hours after lung transplantation by exsanguination. Serum levels of interleukin (IL)-8 and tumor necrosis factor (TNF)-α were measured by enzyme-linked immunosorbent assay.

RESULTS

CO and/or BV treatment attenuated partial pressure of arterial oxygen (Pao(2))/fraction of inspired oxygen (Fio(2)) aggravation in the recipients after reperfusion, reduced the wet weight/dry weight ratio, decreased the lung injury score, inhibited the activity of myeloperoxidase in grafts, and decreased serum levels of IL-8 and TNF-α compared with the control group (p < 0.05). The COBV group had significantly decreased malonaldehyde levels and increased superoxide dismutase levels in lung grafts compared with the CO group (p < 0.05). The static pressure-volume curve of the lungs was ameliorated in the CO group, BV group, and COBV group compared with the control group (p < 0.05).

CONCLUSIONS

CO and BV exert protective effects through anti-inflammatory and anti-oxidant mechanisms, and dual treatment provided enhanced cytoprotection against lung graft injury from BD rat donors.

Heme oxygenase in the regulation of vascular biology: from molecular mechanisms to therapeutic opportunities

Heme oxygenases (HOs) are the rate-limiting enzymes in the catabolism of heme into biliverdin, free iron, and carbon monoxide. Two genetically distinct isoforms of HO have been characterized: an inducible form, HO-1, and a constitutively expressed form, HO-2. HO-1 is a kind of stress protein, and thus regarded as a sensitive and reliable indicator of cellular oxidative stress. The HO system acts as potent antioxidants, protects endothelial cells from apoptosis, is involved in regulating vascular tone, attenuates inflammatory response in the vessel wall, and participates in angiogenesis and vasculogenesis. Endothelial integrity and activity are thought to occupy the central position in the pathogenesis of cardiovascular diseases. Cardiovascular disease risk conditions converge in the contribution to oxidative stress. The oxidative stress leads to endothelial and vascular smooth muscle cell dysfunction with increases in vessel tone, cell growth, and gene expression that create a pro-thrombotic/pro-inflammatory environment. Subsequent formation, progression, and obstruction of atherosclerotic plaque may result in myocardial infarction, stroke, and cardiovascular death. This background provides the rationale for exploring the potential therapeutic role for HO system in the amelioration of vascular inflammation and prevention of adverse cardiovascular outcomes.

Intestinal ischemia/reperfusion: microcirculatory pathology and functional consequences

BACKGROUND

Intestinal ischemia and reperfusion (I/R) is a challenging and life-threatening clinical problem with diverse causes. The delay in diagnosis and treatment contributes to the continued high in-hospital mortality rate.

RESULTS

Experimental research during the last decades could demonstrate that microcirculatory dysfunctions are determinants for the manifestation and propagation of intestinal I/R injury. Key features are nutritive perfusion failure, inflammatory cell response, mediator surge and breakdown of the epithelial barrier function with bacterial translocation, and development of a systemic inflammatory response. This review provides novel insight into the basic mechanisms of damaged intestinal microcirculation and covers therapeutic targets to attenuate intestinal I/R injury.

CONCLUSION

The opportunity now exists to apply this insight into the translation of experimental data to clinical trial-based research. Understanding the basic events triggered by intestinal I/R may offer new diagnostic and therapeutic options in order to achieve improved outcome of patients with intestinal I/R injury.

Heme oxygenase in the regulation of vascular biology: from molecular mechanisms to therapeutic opportunities

Heme oxygenases (HOs) are the rate-limiting enzymes in the catabolism of heme into biliverdin, free iron, and carbon monoxide. Two genetically distinct isoforms of HO have been characterized: an inducible form, HO-1, and a constitutively expressed form, HO-2. HO-1 is a kind of stress protein, and thus regarded as a sensitive and reliable indicator of cellular oxidative stress. The HO system acts as potent antioxidants, protects endothelial cells from apoptosis, is involved in regulating vascular tone, attenuates inflammatory response in the vessel wall, and participates in angiogenesis and vasculogenesis. Endothelial integrity and activity are thought to occupy the central position in the pathogenesis of cardiovascular diseases. Cardiovascular disease risk conditions converge in the contribution to oxidative stress. The oxidative stress leads to endothelial and vascular smooth muscle cell dysfunction with increases in vessel tone, cell growth, and gene expression that create a pro-thrombotic/pro-inflammatory environment. Subsequent formation, progression, and obstruction of atherosclerotic plaque may result in myocardial infarction, stroke, and cardiovascular death. This background provides the rationale for exploring the potential therapeutic role for HO system in the amelioration of vascular inflammation and prevention of adverse cardiovascular outcomes.

Inhalation of carbon monoxide ameliorates TNBS-induced colitis in mice through the inhibition of TNF-α expression

BACKGROUND

Carbon monoxide (CO), long considered a toxic gas, has recently been shown to mediate anti-inflammatory effects in various animal models. The aim of this study was to investigate whether the inhalation of CO ameliorated 2,4,6-trinitrobenzine sulfonic acid (TNBS)-induced colitis in mice.

METHODS

The CO treatment group was exposed to CO gas at a concentration of 200 ppm in a closed cage starting on the day when TNBS was administered and throughout the remaining study period. The distal colon was removed, and ulcerative lesions were subsequently evaluated with macroscopic damage scores. Furthermore, thiobarbituric acid (TBA)-reactive substances and tissue-associated myeloperoxidase (MPO) activity in colonic mucosa were measured as indices of lipid peroxidation and neutrophil infiltration. The expressions of TNF-α in colonic mucosa were also measured by enzyme-linked immunosorbent assay. In additional experiments in vitro, CD4(+) T cells isolated from the spleen were stimulated with anti-CD3/CD28 Ab, and the cells and supernatants were collected and evaluated for TNF-α expression.

RESULTS

The increased colonic damage after TNBS administration was significantly inhibited by the treatment with CO. Furthermore, CO significantly inhibited the increases in TBA-reactive substances, MPO activity and TNF-α production in colonic mucosa after the induction of TNBS colitis. In CD4(+) T cells isolated from mice treated with CO inhalation, the production of TNF-α was significantly inhibited.

CONCLUSIONS

The inhalation of CO protected mice from developing intestinal inflammation. Based on these data, the beneficial effects of CO in a murine colitis model may be attributed to its anti-inflammatory properties.

Carbon monoxide: endogenous mediator, potential diagnostic and therapeutic target

The primary objectives of this article are to review the potential role of carbon monoxide (CO) as an endogenous mediator, diagnostic marker for pulmonary disorders, and therapeutic target in critical illness. The review will start by focusing on the importance of the heme oxygenase (HO)-CO axis as an endogenous system as it relates to the cardiovascular and pulmonary systems. It will elucidate the influence of HO gene expression on critical events like shock, sepsis, ischemia-reperfusion and others. Our focus will then shift and look at the potential diagnostic role of exhaled CO in major inflammatory states of the lung, and finally we will highlight the activities on inhaled CO being considered as a possible therapeutic tool and the controversies surrounding it.

Current theories on the pathophysiology of multiple organ failure after trauma

Despite the enormous efforts to elucidate the mechanisms of the development of multiple organ failure (MOF) following trauma, MOF following trauma is still a leading cause of late post-injury death and morbidity. Now, it has been proven that excessive systemic inflammation following trauma participates in the development of MOF. Fundamentally, the inflammatory response is a host-defence response; however, on occasion, this response turns around to cause deterioration to host depending on exo- and endogenic factors. Through this review we aim to describe the pathophysiological approach for MOF after trauma studied so far and also introduce the prospects of this issue for the future.

The expression of heme oxygenase-1 induced by lansoprazole

Our previous studies have demonstrated that lansoprazole inhibits acute inflammatory reactions as well as intestinal mucosal injuries induced by ischemia-reperfusion or indomethacin administration in rats. Thus, proton pump inhibitors such as lansoprazole have been demonstrated to prevent gastrointestinal mucosal injury by mechanisms independent of acid inhibition. In our in vitro study, lansoprazole induced the expression of heme oxygenase-1 (HO-1) on rat gastric epithelial cells (RGM-1 cells), and exerted anti-inflammatory effect on the dependent of HO-1 expression. Furthermore, NF-E2-related factor-2 (Nrf2) played an important role in HO-1 expression induced by lansoprazole. In this review, we focused on lansoprazole-induced HO-1 expression, its anti-inflammatory action, and the role of Nrf2 in its expression.

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.

Cobalt protoporphyrin inhibition of lipopolysaccharide or lipoteichoic acid-induced nitric oxide production via blocking c-Jun N-terminal kinase activation and nitric oxide enzyme activity

In the present study, low doses (0.5, 1, and 2 microM) of cobalt protoporphyrin (CoPP), but not ferric protoporphyrin (FePP) or tin protoporphyrin (SnPP), significantly inhibited lipopolysaccharide (LPS) or lipoteichoic acid (LTA)-induced inducible nitric oxide (iNOS) and nitric oxide (NO) production with an increase in heme oxygenase 1 (HO-1) protein in RAW264.7 macrophages under serum-free conditions. IC(50) values of CoPP inhibition of NO and iNOS protein individually induced by LPS and LTA were around 0.25 and 1.7 microM, respectively. This suggests that CoPP is more sensitive at inhibiting NO production than iNOS protein in response to separate LPS and LTA stimulation. NO inhibition and HO-1 induction by CoPP were blocked by the separate addition of fetal bovine serum (FBS) and bovine serum albumin (BSA). Decreasing iNOS/NO production and increasing HO-1 protein by CoPP were observed with CoPP pretreatment, CoPP co-treatment, and CoPP post-treatment with LPS and LTA stimulation. LPS- and LTA-induced NOS/NO productions were significantly suppressed by the JNK inhibitor, SP600125, but not by the ERK inhibitor, PD98059, through a reduction in JNK protein phosphorylation. Transfection of a dominant negative JNK plasmid inhibited LPS- and LTA-induced iNOS/NO production and JNK protein phosphorylation, suggesting that JNK activation is involved in LPS- and LTA-induced iNOS/NO production. Additionally, CoPP inhibition of LPS- and LTA-induced JNK, but not ERK, protein phosphorylation was identified in RAW264.7 cells. Furthermore, CoPP significantly reduced NO production in a cell-mediated, but not cell-free, iNOS enzyme activity assay accompanied by HO-1 induction. However, attenuation of HO-1 protein stimulated by CoPP via transfection of HO-1 siRNA did not affect NO's inhibition of CoPP against LPS stimulation. CoPP effectively suppressing LPS- and LTA-induced iNOS/NO production through blocking JNK activation and iNOS enzyme activity via a HO-1 independent manner is first demonstrated herein.

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.

Therapeutic antioxidant medical gas

Medical gases are pharmaceutical gaseous molecules which offer solutions to medical needs and include traditional gases, such as oxygen and nitrous oxide, as well as gases with recently discovered roles as biological messenger molecules, such as carbon monoxide, nitric oxide and hydrogen sulphide. Medical gas therapy is a relatively unexplored field of medicine; however, a recent increasing in the number of publications on medical gas therapies clearly indicate that there are significant opportunities for use of gases as therapeutic tools for a variety of disease conditions. In this article, we review the recent advances in research on medical gases with antioxidant properties and discuss their clinical applications and therapeutic properties.

Hydrogen inhalation ameliorates oxidative stress in transplantation induced intestinal graft injury

Ischemia/reperfusion (I/R) injury during small intestinal transplantation (SITx) frequently causes complications including dysmotility, inflammation and organ failure. Recent evidence indicates hydrogen inhalation eliminates toxic hydroxyl radicals. Syngeneic, orthotopic SITx was performed in Lewis rats with 3 h of cold ischemic time. Both donor and recipient received perioperative air or 2% hydrogen inhalation. SITx caused a delay in gastrointestinal transit and decreased jejunal circular muscle contractile activity 24 h after surgery. Hydrogen treatment resulted in significantly improved gastrointestinal transit, as well as jejunal smooth muscle contractility in response to bethanechol. The transplant induced upregulation in the inflammatory mediators CCL2, IL-1 beta, IL-6 and TNF-alpha were mitigated by hydrogen. Hydrogen significantly diminished lipid peroxidation compared to elevated tissue malondialdehyde levels in air-treated grafts demonstrating an antioxidant effect. Histopathological mucosal erosion and increased gut permeability indicated a breakdown in posttransplant mucosal barrier function which was significantly attenuated by hydrogen treatment. In recipient lung, hydrogen treatment also resulted in a significant abatement in inflammatory mRNA induction and reduced neutrophil recruitment. Hydrogen inhalation significantly ameliorates intestinal transplant injury and prevents remote organ inflammation via its antioxidant effects. Administration of perioperative hydrogen gas may be a potent and clinically applicable therapeutic strategy for intestinal I/R injury.

Expression of inducible nitric oxide synthase and heme oxygenase-1 in the esophageal mucosa of patients with reflux esophagitis

AIM: To detect the expression of inducible nitric oxide synthase (iNOS) and heme oxygenase-1 (HO-1) in human esophageal mucosa of patients with reflux esophagitis (RE), and to find out the role of gas messenger molecules such as nitric oxide (NO) and carbon monoxide (CO) in the pathogenesis of RE.

METHODS: The distributions of iNOS and HO-1 proteins in esophageal tissues 77 RE patients and 20 normal controls were detected by immunohistochemistry (SP method), and the relationship between iNOS and HO-1 expression was analyzed.

RESULTS: iNOS and HO-1 were expressed mainly in esophageal mucosal epithelia. The expression levels of iNOS and HO-1 in RE patients were significantly higher than those in the normal controls (0.2473 ± 0.0548 vs 0.1616 ± 0.0169; 0.2334 ± 0.0511 vs 0.1776 ± 0.0164; both P < 0.01). Moreover the expression of HO-1 was positively correlated with iNOS expression in esophageal mucosa of RE patients (r = 0. 513, P = 0.000). There was no marked difference between iNOS and NO expression in the normal controls (r = -0.073, P = 0.758).

CONCLUSION: HO-1 and iNOS are abnormally expressed in esophageal mucosa of RE patients, suggesting that NO and CO may play important roles in the pathogenesis of gastrointestinal motility disorders such as RE.