Heme oxygenase-1 mediates the anti-inflammatory effects of acute alcohol on IL-10 induction involving p38 MAPK activation in monocytes

Lactobacillus strains reduce the toxic effects of a subchronic exposure to arsenite through drinking water

The aim of the present study was to determine the efficacy of LAB strains in reducing the intestinal toxicity of arsenite [As(III)] and its tissue accumulation. For this purpose, Balb/c mice were randomly separated in four groups. One group received no treatment (control), one group received only As(III) (30 mg/L) via drinking water and the remaining two groups received As(III) via water and a daily dose of two LAB strains (Lactobacillus intestinalis LE1 and Lacticaseibacillus paracasei BL23) by gavage during 2 months. The results show that both strains reduce the pro-inflammatory and pro-oxidant response observed at the colonic level, partially restore the expression of the intercellular junction proteins (CLDN3 and OCLN) responsible for the maintenance of epithelial integrity, and increase the synthesis of the major mucin of the colonic mucus layer (MUC2), compared to animals treated with As(III) alone. Microbial metabolism of short-chain fatty acids also undergoes a recovery and the levels of fatty acids in the lumen reach values similar to those of untreated animals. All these positive effects imply the restoration of mucosal permeability, and a reduction of the marker of endotoxemia LPS binding protein (LBP). Treatment with the bacteria also has a direct impact on intestinal absorption, reducing the accumulation of As in the internal organs. The data suggest that the protective effect may be due to a reduced internalization of As(III) in intestinal tissues and to a possible antioxidant and anti-inflammatory activity of the bacteria through activation of pathways such as Nrf2 and IL-10. In vitro tests show that the protection may be the result of the combined action of structural and metabolic components of the LAB strains.

Mucin2 regulated by Ho1/p38/IL-10 axis plays a protective role in polystyrene nanoplastics-mediated intestinal toxicity

Micro/nano-plastics (MPs/NPs) are a newly discovered environmental pollutant that can be ingested by humans through food and drinking water. In this study we evaluated the impact of MPs/NPs on the intestinal barrier and its mechanism. Doses of MPs/NPs were used to treat Caco-2/HT29-MTX in-vitro model and in-vivo model. In in-vitro model, 20 nm polystyrene nanoplastics (PS-NPs) had higher cytotoxicity than larger particles (200 nm and 2000 nm), and led to the increase of the permeability along with the decreased expression of tight junction proteins. Intriguingly, 20 nm PS-NPs elevated the expression of MUC2 simultaneously. Further studies revealed that PS-NPs increased the expression of HO1 through ROS generation, and then activated p38 to elevate IL-10 secretion in Caco-2 cell. The IL-10 secreted by Caco-2 cell promoted the expression of MUC2 in HT29-MTX cell through STAT1/3. Elevated MUC2 expression alleviates the cytotoxicity of PS-NPs. Besides, increased intestinal permeability and up-regulation of MUC2 through Ho1/p38/IL-10 pathway was also observed in 20 nm PS-NPs treated mouse model. In conclusion, PS-NPs can induce the intestinal toxicity and result in the increased adaptive expression of MUC2 to resist this adverse effect. People with inadequate mucin expression need to pay more attention to the toxicity of PS-NPs. This study provided a valuable insight for clarifying the mechanism and potential risk of intestinal toxicity induced by nanoplastics.

Heme oxygenase 1 in erythropoiesis: an important regulator beyond catalyzing heme catabolism

Heme oxygenase 1 (HO-1), encoded by the HMOX-1 gene, is the main heme oxygenase that catalyzes the degradation of heme into iron, carbon monoxide, and biliverdin. HMOX-1 gene expression is stimulated by oxidative stress and regulated at transcriptional and post-transcriptional levels. After translation, subcellular location and protein stability of HO-1 are also altered by different extracellular and intracellular stimuli. HO-1 plays a key role in regulating iron homeostasis and cell protection and has become a new target for disease treatment. Erythropoiesis is a tightly controlled, iron-dependent process that begins with hematopoietic stem cells and maturates to red blood cells. HO-1 is expressed in hematopoietic stem/progenitor cells, hematopoietic niche cells, erythroblasts, and especially erythroblastic island and phagocytic macrophages. HO-1 functions importantly in the entire erythroid development process by influencing hematopoietic stem cell proliferation, erythroid lineage engagement, terminal erythroid differentiation, and even senescent RBC erythrophagocytosis. HO-1 is also related to stress erythropoiesis and certain red blood cell diseases. Elucidation of HO-1 regulation and function in erythropoiesis will be of great significance for the treatment of related diseases.

The immunosuppression pathway of tumor-associated macrophages is controlled by heme oxygenase-1 in glioblastoma patients

The immunosuppressive tumor microenvironment (TME) in glioblastoma (GBM) is mainly driven by tumor-associated macrophages (TAMs). We explored whether their sustained iron metabolism and immunosuppressive activity were correlated, and whether blocking the central enzyme of the heme catabolism pathway, heme oxygenase-1 (HO-1), could reverse their tolerogenic activity. To this end, we investigated iron metabolism in bone marrow-derived macrophages (BMDMs) isolated from GBM specimens and in in vitro-derived macrophages (Mφ) from healthy donor (HD) blood monocytes. We found that HO-1 inhibition abrogated the immunosuppressive activity of both BMDMs and Mφ, and that immunosuppression requires both cell-to-cell contact and soluble factors, as HO-1 inhibition abolished IL-10 release, and significantly reduced STAT3 activation as well as PD-L1 expression. Interestingly, not only did HO-1 inhibition downregulate IDO1 and ARG-2 gene expression, but also reduced IDO1 enzymatic activity. Moreover, T cell activation status affected PD-L1 expression and IDO1 activity, which were upregulated in the presence of activated, but not resting, T cells. Our results highlight the crucial role of HO-1 in the immunosuppressive activity of macrophages in the GBM TME and demonstrate the feasibility of reprogramming them as an alternative therapeutic strategy for restoring immune surveillance.

Interleukin-10 and Its Receptors at the Maternal-Conceptus Interface: Expression, Regulation, and Implication for Th2 Cytokine Predominance and Maternal Immune Tolerance in the Pig, a True Epitheliochorial Placentation Species†

The appropriate balance between pro-inflammatory and anti-inflammatory cytokines is important for the maternal immune tolerance during pregnancy in mammals. Among the various cytokines, interleukin (IL)-10 (IL10) plays an essential role in anti-inflammatory responses, while IL12 is involved in pro-inflammatory responses during pregnancy. However, the roles of IL10 and IL12 in the endometrium during pregnancy have not been studied in pigs. Thus, we investigated the expression of IL10, IL12 (IL12A and IL12B) and their receptors (IL10RA, IL10RB, IL12RB1, and IL12RB2) at the maternal-conceptus interface. IL10, IL12, and their receptors were expressed in the endometrium during the estrous cycle and pregnancy in a pregnancy stage-specific manner. During pregnancy, IL10 expression increased on Day 15, whereas the expression of IL12A and IL12B decreased after the implantation period. IL10 protein was localized to luminal epithelial (LE), stromal cells, and macrophages; IL10RA protein to LE, endothelial, stromal, and T cells; and IL10RB mRNA to LE cells in the endometrium. IL10 and IL10RA proteins and IL10RB mRNA were also localized to chorionic epithelial (CE) cells. In endometrial explants, the expression of IL10RA and IL10RB was induced by estradiol-17β, IL-1β, and/or interferon-γ. Heme oxygenase 1, an IL10-inducible factor, was expressed in the endometrium with highest levels on Day 30 of pregnancy and was localized to LE and CE cells. These results in pigs suggest that conceptus-derived signals change the endometrial immune environment by regulating the expression of IL10 and IL10 receptors at the maternal-conceptus interface and that IL10 may provide anti-inflammatory conditions for the maternal immune tolerance. Summary Sentence: IL10 expression increases at the maternal-conceptus interface in pigs.

Heme oxygenase-1 induction mitigates burn-associated early acute kidney injury via the TLR4 signaling pathway

OBJECTIVES

Early acute kidney injury (AKI) after burn contributes to disastrous prognoses for severely burned patients. Burn-induced renal oxidative stress and secondary proinflammatory mediator release contribute to early AKI development, and Toll-like receptor (TLR) 4 regulates inflammation. Heme oxygenase-1 (HO-1) is a stress-responsive enzyme that plays a vital role in protecting against ischemia-induced organ injury via its antioxidant properties and regulation of inflammation. We investigated the potential effect of HO-1 induction in preventing burn-induced early AKI and its related mechanism.

METHODS

A classic major-burn rat model was established using a 100 °C water bath, and hemin was injected intraperitoneally immediately after the injury to induce HO-1. Histological staining and blood tests were used to assess AKI progression based on structural changes and function. Renal levels of HO-1, oxidative stress, proinflammatory mediators and TLR4-related signals were detected using ELISA, immunostaining, qRT-PCR, and western blotting. The selective TLR4 inhibitor TAK242 and TLR4 inducer LPS were introduced to determine the roles of HO-1 in burn-related renal inflammation and the TLR4 pathway.

RESULTS

Hemin improved burn-induced renal histological damage and dysfunction, and this beneficial effect was related to reduced renal oxidative stress and the release of proinflammatory mediators, such as tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, IL-6 and intracellular adhesion molecule-1 (ICAM-1). Hemin downregulated the expression of TLR4 and the subsequent phosphorylation of IKKα/β, IκBα, and NF-κB p65;. TAK242 exerted an effect similar to but weaker than hemin; and LPS reversed the antiinflammatory effect of hemin and the regulation of TLR4 signals. These results suggested that the TLR4 signaling pathway mediated the HO-1-facilitated regulation of renal inflammation after burn.

CONCLUSION

The present study demonstrated that HO-1 induction prevented burn-induced early AKI by targeting renal inflammation, which was mediated via regulation of the TLR4/NF-κB signaling pathway.

Deciphering the Role of Heme Oxygenase-1 (HO-1) Expressing Macrophages in Renal Ischemia-Reperfusion Injury

Ischemia-reperfusion injury (IRI) is a leading cause of acute kidney injury (AKI), which contributes to the development of chronic kidney disease (CKD). Renal IRI combines major events, including a strong inflammatory immune response leading to extensive cell injuries, necrosis and late interstitial fibrosis. Macrophages act as key players in IRI-induced AKI by polarizing into proinflammatory M1 and anti-inflammatory M2 phenotypes. Compelling evidence exists that the stress-responsive enzyme, heme oxygenase-1 (HO-1), mediates protection against renal IRI and modulates macrophage polarization by enhancing a M2 subset. Hereafter, we review the dual effect of macrophages in the pathogenesis of IRI-induced AKI and discuss the critical role of HO-1 expressing macrophages.

DNA or Protein Methylation-Dependent Regulation of Activator Protein-1 Function

Epigenetic regulation and modification govern the transcriptional mechanisms that promote disease initiation and progression, but can also control the oncogenic processes, cell signaling networks, immunogenicity, and immune cells involved in anti-inflammatory and anti-tumor responses. The study of epigenetic mechanisms could have important implications for the development of potential anti-inflammatory treatments and anti-cancer immunotherapies. In this review, we have described the key role of epigenetic progression: DNA methylation, histone methylation or modification, and protein methylation, with an emphasis on the activator protein-1 (AP-1) signaling pathway. Transcription factor AP-1 regulates multiple genes and is involved in diverse cellular processes, including survival, differentiation, apoptosis, and development. Here, the AP-1 regulatory mechanism by DNA, histone, or protein methylation was also reviewed. Various methyltransferases activate or suppress AP-1 activities in diverse ways. We summarize the current studies on epigenetic alterations, which regulate AP-1 signaling during inflammation, cancer, and autoimmune diseases, and discuss the epigenetic mechanisms involved in the regulation of AP-1 signaling.

Calming the (Cytokine) Storm: Dimethyl Fumarate as a Therapeutic Candidate for COVID-19

COVID-19 has rapidly spread worldwide and incidences of hospitalisation from respiratory distress are significant. While a vaccine is in the pipeline, there is urgency for therapeutic options to address the immune dysregulation, hyperinflammation and oxidative stress that can lead to death. Given the shared pathogenesis of severe cases of COVID-19 with aspects of multiple sclerosis and psoriasis, we propose dimethyl fumarate as a viable treatment option. Currently approved for multiple sclerosis and psoriasis, dimethyl fumarate is an immunomodulatory, anti-inflammatory and anti-oxidative drug that could be rapidly implemented into the clinic to calm the cytokine storm which drives severe COVID-19.

Suppressed LPS-mediated TLR4 signaling in the plateau zokor (Eospalax baileyi) compared to the bamboo rat (Rhizomys pruinosus) and rat (Rattus norvegicus)

Ecological immunology involves the study of the immune function of wildlife, which is seldom compared with that of model animals. Here, we evaluated and compared the level of the innate immune response in the plateau zokor (Eospalax baileyi), an indigenous underground rodent from the Tibetan Plateau, with that in the bamboo rat (Rhizomys pruinosus) and Sprague-Dawley (SD) rat (Rattus norvegicus). The spleen was observed by ordinary light and transmission electron microscopy, and the spleen index was calculated. After liposaccharide (LPS) challenge, the expression of Toll-like receptor 2 (TLR2), TLR4, and hypoxia-inducible factor 1α (HIF-1α) in the spleen was detected by Western blot analysis and immunofluorescence. The expression of nuclear factor-κB1 (NF-κB1) and mitogen-activated protein kinase 14 (MAPK14) in the spleen was detected by real-time quantitative polymerase chain reaction, and the levels of interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), and interferon-β (IFN-β) in the spleen were detected by enzyme-linked immunoassay. The spleen index of the plateau zokor was lower than that of the bamboo rat and SD rat. The expression of TLR4, NF-κB1, and MAPK14 and the levels of IL-6 and TNF-α in the spleen of the plateau zokor were lower than those of the bamboo rat and SD rat, while the expression of TLR2 and HIF-1α and the level of IFN-β were higher than those of the bamboo rat and SD rat. We speculate that suppression of the TLR4 signaling pathway in the plateau zokor is an adaptation to hypoxic tunnels that decreases antigenic risk and maintains immune homeostasis. Moreover, the spleen of the plateau zokor is reduced in size, reducing the innate immunity investment in the spleen. We also noted that high levels of HIF-1α in the spleen of the plateau zokor suppressed crosstalk between HIF-1α and TLR4, promoting the innate immune response.

MicroRNA-155 and microRNA-181a, via HO-1, participate in regulating the immunotoxicity of cadmium in the kidneys of exposed Cyprinus carpio

Cadmium (Cd) is a nonessential metal that is a contaminant in aquatic ecosystems. Cd can accumulate in aquatic animals, leading to detrimental effects in tissues, and Cd exposure can induce immunotoxicity in fish. MicroRNAs (miRNAs) play critical roles in immune responses, yet the participation of miRNAs in Cd-induced immunotoxicity remains poorly understood. The present study evaluated the effects of Cd exposure on the immune responses and the mRNAs and miRNAs expressions of immune-related genes in Cyprinus carpio (C. carpio). Then, microRNA-155 (miR-155) was overexpressed and microRNA-181a (miR-181a) was knocked down to determine which miRNA plays a key role in the immune response to Cd. The results showed that 0.5 mg/L Cd²⁺ significantly decreased the activity of alkaline phosphatase (AKP) and acid phosphatase (ACP) in the kidneys of C. carpio. Cd exposure upregulated the mRNA expressions of interleukin (IL)-1β, IL-8, nuclear factor-kappa B (NF-κB), tumour necrosis factor-α (TNF-α), and Toll-like receptor 4(TLR-4) and downregulated those of IL-10 and heme oxygenase-1 (HO-1) in C. carpio kidneys. Cd exposure also led to upregulation of miR-155 and miR-181a expressions. Furthermore, AKP and ACP activity in the kidneys was markedly changed after intraperitoneal injection of C. carpio with miR-155 agomir and miR-181a antagomir. All detected mRNA expressions were significantly decreased after injection of miR-155 agomir, and IL-10, NF-κB, TNF-α, and HO-1 mRNA expressions were markedly increased after injection of miR-181a antagomir. The results of this study demonstrate that Cd exposure can immunocompromise C. carpio by targeting HO-1 through miR-155 and miR-181a. This is the first study to reveal that Cd exposure induces immunotoxicity through miR-155 and miR-181a in the kidneys of C. carpio.

TonEBP Suppresses the HO-1 Gene by Blocking Recruitment of Nrf2 to Its Promoter

TonEBP is a key transcriptional activator in macrophages with an M1 phenotype. High expression of TonEBP is associated with many inflammatory diseases. Heme oxygenase-1 (HO-1), a stress-inducible protein, is induced by various oxidative and inflammatory signals, and its expression is regarded as an adaptive cellular response to inflammation and oxidative injury. Here, we show that TonEBP suppresses expression of HO-1 by blocking Nrf2 binding to the HO-1 promoter, thereby inducing polarization of macrophages to the M1 phenotype. Inhibition of HO-1 expression or activity significantly reduced the inhibitory responses on M1 phenotype and stimulatory effects on M2 phenotype by TonEBP knockdown. Additional experiments showed that HO-1 plays a role in the paracrine anti-inflammatory effects of TonEBP knockdown in macrophages. Identification of HO-1 as a downstream effector of TonEBP provides new possibilities for improved therapeutic approaches to inflammatory diseases.

The effect of continuous blood purification on P38MAPK signaling pathway in patients with multiple organ dysfunction syndrome

OBJECTIVE

The aim of the study was to investigate the role of p38MAPK signaling pathway in patients with multiple organ dysfunction syndrome treated with continuous blood purification.

METHODS

Blood samples were obtained to analyze the protein level of inflammatory factors (IL-1, IL-8, IL-10, and TNF-α) and phosphorylated p38MAPK by utilizing ELISA assay and Western blotting, respectively. The relative mRNA level of iNOS was detected by using RT-PCR. In vitro study was conducted in Caco-2 cells, which were treated with serum from patients subjected to continuous blood purification. Serum-induced inflammatory factors and phosphorylated p38MAPK were also analyzed in Caco-2 cells.

RESULTS

The protein levels of IL-1, IL-8, IL-10, and TNF-α were significantly decreased in Caco-2 cells treated with serum obtained from patients who were subjected to continuous blood purification therapy at the time course of 12 and 24 hours. A drastic decrease (P < 0.05) was observed in the level of IL-8 and TNF-α after continuous blood purification therapy in the patients treated with continuous blood purification therapy compared with control group.

CONCLUSION

Our study conducted in vivo and in vitro demonstrated that the continuous blood purification therapy could ameliorate the inflammatory response via activating the p38MAPK signaling pathway.

IVIg and LPS Co-stimulation Induces IL-10 Production by Human Monocytes, Which Is Compromised by an FcγRIIA Disease-Associated Gene Variant

Intravenous Immunoglobulin (IVIg) is used to treat autoimmune or inflammatory diseases, but its mechanism of action is not completely understood. We asked whether IVIg can induce interleukin-10 (IL-10) and reduce pro-inflammatory cytokine production in human monocytes, and whether this response is reduced in monocytes from people with an Fcγ receptor IIA (FcγRIIA) gene variant, which is associated with increased risk of inflammatory diseases and poor response to antibody-based biological therapy. IVIg increased IL-10 production and reduced pro-inflammatory cytokine production in response to bacterial lipopolysaccharide (LPS), which required FcγRI and FcγRIIB and activation of MAPKs, extracellular signal-regulated kinase 1/2 (ERK1/2), and p38. IL-10 production was lower and pro-inflammatory cytokine production was higher in monocytes from people with the FcγRIIA risk variant and the risk variant prevented IL-10 production in response to (IVIg+LPS). Finally, we show that IVIg did not induce MAPK activation in monocytes from people with the risk variant. Our results demonstrate that IVIg can skew human monocytes to an anti-inflammatory, IL-10-producing activation state, which is compromised in monocytes from people with the FcγRIIA risk variant. This research has profound implications for the use of IVIg because 25% of the population is homozygous for the FcγRIIA risk variant and its efficacy may be reduced in those individuals. In addition, this research may be useful to develop new therapeutic strategies to replace IVIg by cross-linking FcγRIs and FcγRIIBs to promote anti-inflammatory macrophage activation, independent of the FcγRIIA genotype.

Implications of macrophage polarization in autoimmunity

Macrophages are extremely heterogeneous and plastic cells with an important role not only in physiological conditions, but also during inflammation (both for initiation and resolution). In the early 1990s, two different phenotypes of macrophages were described: one of them called classically activated (or inflammatory) macrophages (M1) and the other alternatively activated (or wound-healing) macrophages (M2). Currently, it is known that functional polarization of macrophages into only two groups is an over-simplified description of macrophage heterogeneity and plasticity; indeed, it is necessary to consider a continuum of functional states. Overall, the current available data indicate that macrophage polarization is a multifactorial process in which a huge number of factors can be involved producing different activation scenarios. Once a macrophage adopts a phenotype, it still retains the ability to continue changing in response to new environmental influences. The reversibility of polarization has a critical therapeutic value, especially in diseases in which an M1/M2 imbalance plays a pathogenic role. In this review, we assess the high plasticity of macrophages and their potential to be exploited to reduce chronic/detrimental inflammation. On the whole, the evidence detailed in this review underscores macrophage polarization as a target of interest for immunotherapy.

The extracellular matrix of eggshell displays anti-inflammatory activities through NF-κB in LPS-triggered human immune cells

Avian eggshell membrane (ESM) is a natural biomaterial that has been used as an alternative natural bandage on burned and cut skin injuries for >400 years in Asian countries, and is available in large quantities from egg industries. Our aim was to characterize ESM that was separated and processed from egg waste, and to study whether this material possesses anti-inflammatory properties, making it suitable as an ingredient in industrial production of low cost wound healing products. Our results show that the processed ESM particles retain a fibrous structure similar to that observed for the native membrane, and contain collagen, and carbohydrate components such as hyaluronic acid and sulfated glycosaminoglycans, as well as N-glycans, mostly with uncharged structures. Furthermore, both processed ESM powder and the ESM-derived carbohydrate fraction had immunomodulation properties in monocytes and macrophage-like cells. Under inflammatory conditions induced by lipopolysaccharide, the ESM powder and the isolated carbohydrate fraction reduced the activity of the transcription factor nuclear factor-κB. The expression of the immune regulating receptors toll-like receptor 4 and ICAM-1, as well as the cell surface glycoprotein CD44, all important during inflammation response, were down-regulated by these fractions. Interestingly, our experiments show that the two fractions regulated cytokine secretion differently: ESM depressed inflammation by increased secretion of the anti-inflammatory cytokine IL-10 while the carbohydrate fraction reduced secretions of the pro inflammatory cytokines IL-1β and IL-6. Also, the phosphorylation of p65 and p50 subunits of nuclear factor-κB, as well as nuclear localization, differed between processed ESM powder and carbohydrate fraction, suggesting different down-stream regulation during inflammation. In conclusion, processed ESM powder and its soluble carbohydrate components possess anti-inflammatory properties, demonstrating the potential of ESM as a novel biological wound dressing for treatment of chronic inflammatory wounds.

Heme Oxygenase-1 Modulates Human Respiratory Syncytial Virus Replication and Lung Pathogenesis during Infection

Human respiratory syncytial virus (hRSV) is the leading cause of severe lower respiratory tract infections in children. The development of novel prophylactic and therapeutic antiviral drugs against hRSV is imperative to control the burden of disease in the susceptible population. In this study, we examined the effects of inducing the activity of the host enzyme heme oxygenase-1 (HO-1) on hRSV replication and pathogenesis on lung inflammation induced by this virus. Our results show that after hRSV infection, HO-1 induction with metalloporphyrin cobalt protoporphyrin IX significantly reduces the loss of body weight due to hRSV-induced disease. Further, HO-1 induction also decreased viral replication and lung inflammation, as evidenced by a reduced neutrophil infiltration into the airways, with diminished cytokine and chemokine production and reduced T cell function. Concomitantly, upon cobalt protoporphyrin IX treatment, there is a significant upregulation in the production of IFN-α/β mRNAs in the lungs. Furthermore, similar antiviral and protective effects occur by inducing the expression of human HO-1 in MHC class II⁺ cells in transgenic mice. Finally, in vitro data suggest that HO-1 induction can modulate the susceptibility of cells, especially the airway epithelial cells, to hRSV infection.

Mesenchymal stem cells increase expression of heme oxygenase-1 leading to anti-inflammatory activity in treatment of acute liver failure

BACKGROUND

Mesenchymal stem cells (MSCs) have been studied for the treatment of acute liver failure (ALF) for several years. MSCs may exert their effect via complex paracrine mechanisms. Heme oxygenase (HO) 1, a rate-limiting enzyme in heme metabolism, exerts a wide range of anti-inflammatory, anti-apoptotic and immunoregulatory effects in a variety of diseases. However, the relationship between MSCs and HO-1 in the treatment of ALF is still unclear. We investigated the preventive and therapeutic potential of intravenously administered BMSCs.

METHODS

Bone marrow-derived mesenchymal stem cells (BMSCs) obtained from Sprague-Dawley rats were isolated and cultured. We employed BMSCs, hemin (a HO-1 inducer) and zinc protoporphyrin (ZnPP, the HO-1 activity inhibitor) in D-galactosamine (D-Gal)/lipopolysaccharides (LPS)-induced ALF rats. Rats were sacrificed at days 1, 3, 5, and 7 post-transfusion, respectively. Blood samples and liver tissues were collected. Hepatic injury, HO-1 activity, chemokines, inflammatory cytokines, the number and oxidative activity of neutrophils, ki67, and TUNEL-positive cells were evaluated.

RESULTS

HO-1 induction or BMSCs transplantation attenuated D-galactosamine/lipopolysaccharide-induced increases in alanine aminotransferase, aspartate aminotransferase, total bilirubin (TBIL), ammonia, and inflammatory cytokines. Treatment with hemin or BMSCs also inhibited neutrophil infiltration, oxidative activity, and hepatocyte apoptosis. The protective effect of BMSCs was partially neutralized by ZnPP, suggesting the key role of HO-1 in the process.

CONCLUSIONS

These findings may correlate with inhibition of nuclear factor-κ B activation. BMSCs ameliorated ALF by increasing the HO-1 expression, which reduced PMN infiltration and function, and played an important anti-inflammatory and anti-apoptotic role. Proposed mechanism by which BMSCs reduce inflammation, neutrophil activation, and hepatocyte apoptosis and promote hepatocyte proliferation via HO-1. BMSCs increase HO-1 expression in liver via Nrf2. HO-1 protects against LPS/D-Gal-induced ALF by inhibiting neutrophil infiltration and inflammatory burst, and hepatocyte apoptosis and necrosis. HO-1 also promotes hepatocyte proliferation.

Role of cytokines and chemokines in alcohol-induced tumor promotion

Excessive chronic alcohol consumption has become a worldwide health problem. The oncogenic effect of chronic alcohol consumption is one of the leading concerns. The mechanisms of alcohol-induced tumorigenesis and tumor progression are largely unknown, although many factors have been implicated in the process. This review discusses the recent progress in this research area with concentration on alcohol-induced dysregulation of cytokines and chemokines. Based on the available evidence, we propose that alcohol promotes tumor progression by the dysregulation of the cytokine/chemokine system. In addition, we discuss specific transcription factors and signaling pathways that are involved in the action of these cytokines/chemokines and the oncogenic effect of alcohol. This review provides novel insight into the mechanisms of alcohol-induced tumor promotion.

Postprandial effects of wine consumption on Platelet Activating Factor metabolic enzymes

Platelet Activating factor (PAF) is a potent inflammatory mediator that is involved in the initiation and the prolongation of atherosclerosis. The purpose of the study was to investigate the effect of wine consumption on the activity of PAF metabolic enzymes and on IL-6 levels as a cytokine inflammatory marker. Healthy men participated in 4 daily trials and consumed a standardized meal along with Robola wine (trial R), or Cabernet Sauvignon (trial CS), or ethanol solution (trial E), or water (trial W). A significant trial effect was found in the activity of lyso-PAF acetyltransferase (Lyso-PAF AT) (p_trial=0.01). In specific, R trial decreased enzyme activity compared to E trial (p=0.03) while a trend for differentiation was observed between CS trial and E one (p=0.06) as well as between R trial and W one (p=0.07). Concerning PAF-cholinephosphotransferase (PAF-CPT) activity, a significant trial effect was found (p_trial<0.00). Specifically, both R (p=0.002) and CS (p=0.001) trials decreased enzyme activity compared to E trial. Concerning lipoprotein-associated phospholipase A2 (LpPLA2) no time either trial effect was observed. Concerning IL-6 levels a significant time effect was found (p_time<0.00) while no trial effect was revealed. In conclusion, the protective effect of wine consumption could partly be explained through the modulation of PAF metabolism by wine micro-constituents that lead to lower PAF levels.

Specific expression of heme oxygenase-1 by myeloid cells modulates renal ischemia-reperfusion injury

Renal ischemia-reperfusion injury (IRI) is a major risk factor for delayed graft function in renal transplantation. Compelling evidence exists that the stress-responsive enzyme, heme oxygenase-1 (HO-1) mediates protection against IRI. However, the role of myeloid HO-1 during IRI remains poorly characterized. Mice with myeloid-restricted deletion of HO-1 (HO-1^M-KO), littermate (LT), and wild-type (WT) mice were subjected to renal IRI or sham procedures and sacrificed after 24 hours or 7 days. In comparison to LT, HO-1^M-KO exhibited significant renal histological damage, pro-inflammatory responses and oxidative stress 24 hours after reperfusion. HO-1^M-KO mice also displayed impaired tubular repair and increased renal fibrosis 7 days after IRI. In WT mice, HO-1 induction with hemin specifically upregulated HO-1 within the CD11b⁺ F4/80^lo subset of the renal myeloid cells. Prior administration of hemin to renal IRI was associated with significant increase of the renal HO-1⁺ CD11b⁺ F4/80^lo myeloid cells in comparison to control mice. In contrast, this hemin-mediated protection was abolished in HO-1^M-KO mice. In conclusion, myeloid HO-1 appears as a critical protective pathway against renal IRI and could be an interesting therapeutic target in renal transplantation.

Luteolin protects mice from severe acute pancreatitis by exerting HO-1-mediated anti-inflammatory and antioxidant effects

Reseda odorata L. has long been used in traditional Asian medicine for the treatment of diseases associated with oxidative injury and acute inflammation, such as endotoxemia, acute lung injury, acute myocardial infarction and hepatitis. Luteolin, the main component of Reseda odorata L., which is also widely found in many natural herbs and vege-tables, has been shown to induce heme oxygenase-1 (HO-1) expression to exert anti-inflammatory and antioxidant effects. In this study, we aimed to examine the effects of luteolin on mice with severe acute pancreatitis (SAP), and to explore the underlying mechanisms. Cerulein and lipopolysaccharide were used to induce SAP in male Institute of Cancer Research (ICR) mice in the SAP group. The SAP group was divided into 4 subgroups, as follows: the vehicle, luteolin, zinc protoporphyrin (ZnPP) only, and luteolin (Lut) + ZnPP (luteolin plus zinc protoporphyrin treatment) groups. The wet/dry weight ratios, hematoxylin and eosin staining and pathological scores of pancreatic tissues were assessed and compared to those of the control mice. Amylase, lipase, nuclear factor-κB (NF-κB) and myeloperoxidase activities, and malondialdehyde, tumor necrosis factor α (TNFα), interleukin (IL)-6, IL-10 and HO-1 levels, as well as the expression of HO-1 were determined in serum and/or pancreatic tissue samples. SAP was successfully induced in male mice compared to normal control mice. The wet/dry weight ratios, pathological scores, and amylase and lipase activity, as well as the levels of TNFα and IL-6 were significantly reduced in the pancreatic tissues of the mice in the Lut group compared with those of the mice in the vehicle group. The Lut group exhibited a significant increase in HO-1 expression in the pancreas and enhanced serum HO-1 and IL-10 levels compared with the vehicle group. The suppression of HO-1 activity in the ZnPP group significantly abolished the protective effects of luteolin. NF-κB expression in the pancreatic tissues from the mice in the Lut + ZnPP group was significantly increased following the suppression of HO-1 activity. On the whole, our findings demonstrate that luteolin protects mice from SAP by inducing HO-1-mediated anti-inflammatory and antioxidant activities, in association with the suppression of the activation of the NF-κB pathway.

MicroRNA-877-5p is involved in the trovafloxacin-induced liver injury

Trovafloxacin develops severe hepatotoxicity; however, the underlying mechanism of the trovafloxacin-induced liver injury has not been cleared. It has been shown that microRNAs (miRNAs) can be involved in the development of drug-induced liver injuries. We performed a miRNA microarray analysis to identify hepatic miRNAs that were induced or reduced by trovafloxacin in mice. It was demonstrated that miR-877-5p was the most increased miRNA in the mouse liver 24h after the trovafloxacin administration. To investigate the role of miR-877-5p in the liver, we established miR-877-5p-overexpressed HepG2 cells. Microarray analysis detected altered expressions in 2077 (>2-fold) and 1547 (<0.5-fold) genes in the miR-877-5p overexpressing cells compared to the mock cells. Especially, SLCO4C1, PEPCK, MT1M, HIST1H2BM, LGI1, and PLA2G2A were markedly increased or decreased in the miR-877-5p overexpressing cells. We conducted a correlation analysis between the expression levels of miR-877-5p and the six genes in eight miR-877-5p stably-expressed clones. It was shown that the PEPCK expression levels were correlated with miR-877-5p expression levels. PEPCK is associated with development of apoptotic cell death; therefore, the increased miR- 877-5p-induced PEPCK can be a trigger that is involved in the development of trovafloxacin-induced liver injury.

Heme Oxygenase 1 Up-Regulates Glomerular Decay Accelerating Factor Expression and Minimizes Complement Deposition and Injury

Complement-activation controllers, including decay accelerating factor (DAF), are gaining emphasis as they minimize injury in various dysregulated complement-activation disorders, including glomerulopathies. Heme oxygenase (HO)-1 overexpression or induction has been shown to attenuate injury in complement-dependent models of glomerulonephritis. This study investigated whether up-regulation of DAF by heme oxygenase 1 (HO-1) is an underlying mechanism by using Hmox-1-deficient rats (Hmox1^+/-; Hmox1^-/-) or rats with HO-1 overexpression targeted to glomerular epithelial cells (GEC^HO-1), which are particularly vulnerable to complement-mediated injury owing to their terminally differentiated nature. Constitutively expressed DAF was decreased in glomeruli of Hmox1^-/- rats and augmented in glomeruli of GEC^HO-1 rats. In GEC^HO-1 rats with anti-glomerular basement membrane antibody mediated, complement-dependent injury, complement component C3 fragment b (C3b) deposition was reduced, whereas proteinuria was diminished. In glomeruli of wild-type rats, the natural Hmox substrate, hemin, induced glomerular DAF. This effect was attenuated in glomeruli of Hmox1^-/- rats and augmented in glomeruli of GEC^HO-1 rats. Hemin analogues differing in either metal or porphyrin ring functionalities, acting as competitive Hmox-substrate inhibitors, also increased glomerular DAF and reduced C3b deposition after spontaneous complement activation. In the presence of a DAF-blocking antibody, the reduction in C3b deposition was reversed. These observations establish HO-1 as a physiologic regulator of glomerular DAF and identify hemin analogues as inducers of functional glomerular DAF able to minimize C3b deposition.

Bacteroides fragilis Enterotoxin Upregulates Heme Oxygenase-1 in Intestinal Epithelial Cells via a Mitogen-Activated Protein Kinase- and NF-κB-Dependent Pathway, Leading to Modulation of Apoptosis

The Bacteroides fragilis enterotoxin (BFT), a virulence factor of enterotoxigenic B. fragilis (ETBF), interacts with intestinal epithelial cells and can provoke signals that induce mucosal inflammation. Although expression of heme oxygenase-1 (HO-1) is associated with regulation of inflammatory responses, little is known about HO-1 induction in ETBF infection. This study was conducted to investigate the effect of BFT on HO-1 expression in intestinal epithelial cells. Stimulation of intestinal epithelial cells with BFT resulted in upregulated expression of HO-1. BFT activated transcription factors such as NF-κB, AP-1, and Nrf2 in intestinal epithelial cells. Upregulation of HO-1 in intestinal epithelial cells was dependent on activated IκB kinase (IKK)-NF-κB signals. However, suppression of Nrf2 or AP-1 signals in intestinal epithelial cells did not result in significant attenuation of BFT-induced HO-1 expression. HO-1 induction via IKK-NF-κB in intestinal epithelial cells was regulated by p38 mitogen-activated protein kinases (MAPKs). Furthermore, suppression of HO-1 activity led to increased apoptosis in BFT-stimulated epithelial cells. These results suggest that a signaling pathway involving p38 MAPK-IKK-NF-κB in intestinal epithelial cells is required for HO-1 induction during exposure to BFT. Following this induction, increased HO-1 expression may regulate the apoptotic process in responses to BFT stimulation.

Melatonin prevents secondary intra-abdominal hypertension in rats possibly through inhibition of the p38 MAPK pathway

Exogenous administration of melatonin has been demonstrated to down-regulate inflammatory responses and attenuate organ damage in various models. However, the salutary effect of melatonin against secondary intra-abdominal hypertension (IAH) remains unclear. This study sought to test the influence of melatonin on secondary IAH in a pathophysiological rat model and the underlying mechanisms involved. Before resuscitation, male rats underwent a combination of induced portal hypertension, applying an abdominal restraint device, and hemorrhaging to mean arterial pressure (MAP) of 40mmHg for 2h. After blood reinfusion, the rats were treated with lactated Ringer solution (LR) (30mL/h), melatonin (50mg/kg) +LR, and SB-203580 (10μmol/kg)+LR. LR was continuously infused for 6h. MAP, the inferior vena cava pressure and urine output were monitored. Histopathological examination, immunofluorescence of tight junction proteins, and transmission electron microscopy were administered. Intestinal permeability, myeloperoxidase activity, malondialdehyde, glutathione peroxidase, and levels of TNF-a, IL-2, and IL-6, were assessed. The expression of extracellular signal-regulated kinase, p38, c-Jun NH2-terminal kinase, translocation of nuclear factor kappa B subunit, signal transducers and activators of transcription and tight junction proteins were detected by Western blot. We found that melatonin inhibited the inflammatory responses, decreased expression of p38 MAPK, attenuated intestinal injury, and prevented secondary IAH. Moreover, administration of SB203580 abolished the increase in p38 MAPK and also attenuated intestinal injury. These data indicate that melatonin exerts a protective effect in intestine in secondary IAH primarily by attenuating the inflammatory responses which are in part attributable to p38 MAPK inhibition.

Sinomenine activation of Nrf2 signaling prevents hyperactive inflammation and kidney injury in a mouse model of obstructive nephropathy

Sinomenine is originally derived from medicinal herb and used preferentially in treatment of rheumatoid diseases in Far East regions. SIN has strong anti-inflammatory and immune-regulatory properties, acting mainly through inhibiting NF-kB signaling. Although the upstream target through which SIN affects NF-kB activity is unknown, evidence suggests that SIN might regulate inflammation through Nrf2 signaling. In this study we explored the role of Nrf2 in mediating SIN's anti-inflammation and kidney protection in a mouse model of obstructive nephropathy. We found that SIN is an activator of Nrf2 signaling. It markedly increased Nrf2 protein level, Nrf2 nuclear translocation, Nef2 transcription capacity, and the downstream protein expression. We further demonstrated that SIN activation of Nrf2 is likely due to its repression of the Nrf2 inhibitor Keap1 since it drastically reduced Keap1 protein through the PKC-sensitive ubiquitination-proteasomal degradation. SIN treatment of nephropathy mice effectively reduced the kidney damage and inflammatory responses, balanced renal oxidative stress, and improved the pathological protein expression in an Nrf2 dependent manner. In addition, SIN also Nrf2-dependently modulated macrophage M1/M2 polarization and inhibited the IkBα phosphorylation and NF-kB nuclear translocation, hence revealing an important upstream event that contributed to its anti-inflammation and tissue protection. Taken together our study has identified a novel pathway through which SIN exerts its anti-inflammation and renal protective functions, and provided a molecular basis for SIN potential applications in the treatment of kidney and other inflammatory disorders.

Oral delivery of Lactococcus lactis that secretes bioactive heme oxygenase-1 alleviates development of acute colitis in mice

BACKGROUND

Mucosal delivery of therapeutic proteins using genetically modified strains of lactic acid bacteria (gmLAB) is being investigated as a new therapeutic strategy.

METHODS

We developed a strain of gmLAB, Lactococcus lactis NZ9000 (NZ-HO), which secretes the anti-inflammatory molecule recombinant mouse heme oxygenase-1 (rmHO-1). The effects of short-term continuous oral dosing with NZ-HO were evaluated in mice with dextran sulfate sodium (DSS)-induced acute colitis as a model of inflammatory bowel diseases (IBD).

RESULTS

We identified the secretion of rmHO-1 by NZ-HO. rmHO-1 was biologically active as determined with spectroscopy. Viable NZ-HO was directly delivered to the colon via oral administration, and rmHO-1 was secreted onto the colonic mucosa in mice. Acute colitis in mice was induced by free drinking of 3 % DSS in water and was accompanied by an increase in the disease activity index score and histopathological changes. Daily oral administration of NZ-HO significantly improved these colitis-associated symptoms. In addition, NZ-HO significantly increased production of the anti-inflammatory cytokine interleukin (IL)-10 and decreased the expression of pro-inflammatory cytokines such as IL-1α and IL-6 in the colon compared to a vector control strain.

CONCLUSIONS

Oral administration of NZ-HO alleviates DSS-induced acute colitis in mice. Our results suggest that NZ-HO may be a useful mucosal therapeutic agent for treating IBD.

Exosomes derived from alcohol-treated hepatocytes horizontally transfer liver specific miRNA-122 and sensitize monocytes to LPS

Hepatocyte damage and inflammation in monocytes/macrophages are central to the pathogenesis of alcoholic hepatitis (AH). MicroRNAs (miRNAs) regulate all of these processes. MiRNA-122 is abundantly expressed in hepatocytes while monocytes/macrophages have low levels. The role of exosomes in AH and possible cross talk between hepatocyte-derived exosomes and immune cells is not explored yet. Here, we show that the number of exosomes significantly increases in the sera of healthy individuals after alcohol binge drinking and in mice after binge or chronic alcohol consumption. Exosomes isolated from sera after alcohol consumption or from in vitro ethanol-treated hepatocytes contained miRNA-122. Exosomes derived from ethanol-treated Huh7.5 cells were taken up by the recipients THP1 monocytes and horizontally transferred a mature form of liver-specific miRNA-122. In vivo, liver mononuclear cells and Kupffer cells from alcohol-fed mice had increased miRNA-122 levels. In monocytes, miRNA-122 transferred via exosomes inhibited the HO-1 pathway and sensitized to LPS stimulation and increased levels of pro-inflammatory cytokines. Finally, inflammatory effects of exosomes from ethanol-treated hepatocytes were prevented by using RNA interference via exosome-mediated delivery of a miRNA-122 inhibitor. These results demonstrate that first, exosomes mediate communication between hepatocytes and monocytes/macrophages and second, hepatocyte-derived miRNA-122 can reprogram monocytes inducing sensitization to LPS.

Heme oxygenase-1 dysregulation in the brain: implications for HIV-associated neurocognitive disorders

Heme oxygenase-1 (HO-1) is a highly inducible and ubiquitous cellular enzyme that subserves cytoprotective responses to toxic insults, including inflammation and oxidative stress. In neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease and multiple sclerosis, HO-1 expression is increased, presumably reflecting an endogenous neuroprotective response against ongoing cellular injury. In contrast, we have found that in human immunodeficiency virus (HIV) infection of the brain, which is also associated with inflammation, oxidative stress and neurodegeneration, HO-1 expression is decreased, likely reflecting a unique role for HO-1 deficiency in neurodegeneration pathways activated by HIV infection. We have also shown that HO-1 expression is significantly suppressed by HIV replication in cultured macrophages which represent the primary cellular reservoir for HIV in the brain. HO-1 deficiency is associated with release of neurotoxic levels of glutamate from both HIV-infected and immune-activated macrophages; this glutamate-mediated neurotoxicity is suppressed by pharmacological induction of HO-1 expression in the macrophages. Thus, HO-1 induction could be a therapeutic strategy for neuroprotection against HIV infection and other neuroinflammatory brain diseases. Here, we review various stimuli and signaling pathways regulating HO-1 expression in macrophages, which could promote neuronal survival through HO-1-modulation of endogenous antioxidant and immune modulatory pathways, thus limiting the oxidative stress that can promote HIV disease progression in the CNS. The use of pharmacological inducers of endogenous HO-1 expression as potential adjunctive neuroprotective therapeutics in HIV infection is also discussed.

Effective suppression of nitric oxide production by HX106N through transcriptional control of heme oxygenase-1

Heme oxygenase-1 (HO-1) has been suggested to be a key neuroprotective enzyme because of its widespread distribution in the brain as well as its strong antioxidative effects. HX106N, a water-soluble botanical formulation, has previously been demonstrated to prevent amyloid β-induced memory impairment and oxidative stress in mice by upregulating HO-1 levels. In this study, the underlying molecular mechanisms of HX106N-induced HO-1 expression were investigated using BV-2 cells, a murine microglial cell line, and primary microglia. Treatment with HX106N induced the expression of HO-1 at the transcriptional level through the stress-responsive element-containing enhancer present in the ho-1 promoter. Nuclear factor E2-related factor 2 (Nrf2) was activated in cells treated with HX106N. The results from knockdown assay showed that small interfering RNA of Nrf2 attenuated HX106N-mediated HO-1 expression. Pharmacological inhibitors of p38 and JNK mitogen-activated protein kinases suppressed the HX106N-mediated induction of HO-1. The NF-κB signaling pathway was activated by HX106N and played a role in HX106N-induced HO-1 expression. Furthermore, HO-1 and one of its by-products during the enzymatic degradation of heme, CO, were found to be involved in HX106N-mediated suppression of NO production. Taken together, these data indicate that HX106N exerts potent antioxidative effects by increasing the expression of HO-1 through multiple signaling pathways, leading to the suppression of NO production.

Moderate alcohol induces stress proteins HSF1 and hsp70 and inhibits proinflammatory cytokines resulting in endotoxin tolerance

Binge or moderate alcohol exposure impairs host defense and increases susceptibility to infection because of compromised innate immune responses. However, there is a lack of consensus on the molecular mechanism by which alcohol mediates this immunosuppression. In this study, we show that cellular stress proteins HSF1 and hsp70 play a mechanistic role in alcohol-mediated inhibition of the TLR4/MyD88 pathway. Alcohol exposure induced transcription factor HSF1 mRNA expression and DNA binding activity in primary human monocytes and murine macrophages. Furthermore, HSF1 target gene hsp70 mRNA and protein are upregulated by alcohol in monocytes. In vitro pre-exposure to moderate alcohol reduced subsequent LPS-induced NF-κB promoter activity and downstream TNF-α, IL-6 and IL-1β production in monocytes and macrophages, exhibiting endotoxin tolerance. Mechanistic analysis demonstrates that alcohol-induced HSF1 binds to the TNF-α promoter in macrophages at early time points, exerting transrepression and decreased TNF-α expression. Furthermore, association of hsp70 with NF-κB subunit p50 in alcohol-treated macrophages correlates with reduced NF-κB activation at later time points. Hsp70 overexpression in macrophages was sufficient to block LPS-induced NF-κB promoter activity, suggesting alcohol-mediated immunosuppression by hsp70. The direct crosstalk of hsp70 and HSF1 was further confirmed by the loss of alcohol-mediated endotoxin tolerance in hsp70- and HSF1-silenced macrophages. Our data suggest that alcohol-mediated activation of HSF1 and induction of hsp70 inhibit TLR4-MyD88 signaling and are required for alcohol-induced endotoxin tolerance. Using stress proteins as direct drug targets would be clinically relevant in alcohol abuse treatment and may serve to provide a better understanding of alcohol-mediated immunosuppression.

The mononuclear phagocyte system in homeostasis and disease: a role for heme oxygenase-1

SIGNIFICANCE

Heme oxygenase-1 (HO-1) is a potential therapeutic target in many diseases, especially those mediated by oxidative stress and inflammation. HO-1 expression appears to regulate the homeostatic activity and distribution of mononuclear phagocytes (MP) in lymphoid tissue under physiological conditions. It also regulates the ability of MP to modulate the inflammatory response to tissue injury.

RECENT ADVANCES

The induction of HO-1 within MP-particularly macrophages and dendritic cells-modulates the effector functions that they acquire after activation. These effector functions include cytokine production, surface receptor expression, maturation state, and polarization toward a pro- or anti-inflammatory phenotype. The importance of HO-1 in MP is emphasized by their expression of specific receptors that primarily function to ingest heme-containing substrate and deliver it to HO-1.

CRITICAL ISSUES

MP are the first immunological responders to tissue damage. They critically affect the outcome of injury to many organ systems, yet few therapies are currently available to specifically target MP during disease pathogenesis. Elucidation of the role of HO-1 expression in MP may help to direct broadly applicable therapies to clinical use that are based on the immunomodulatory capabilities of HO-1.

FUTURE DIRECTIONS

Unraveling the complexities of HO-1 expression specifically within MP will more completely define how HO-1 provides cytoprotection in vivo. The use of models in which HO-1 expression is specifically modulated in bone marrow-derived cells will allow for a more complete characterization of its immunoregulatory properties.

Gabapentin enhances the morphine anti-nociceptive effect in neuropathic pain via the interleukin-10-heme oxygenase-1 signalling pathway in rats

In the present study, we investigated the anti-inflammatory mechanisms by which gabapentin enhances morphine anti-nociceptive effect in neuropathic pain in rats and the interaction between the anti-nociceptive effects of gabapentin on morphine and the interleukin (IL)-10-heme-oxygenase (HO)-1 signal pathway in a rat model of neuropathic pain. The neuropathic pain model was induced via a left L5/6 spinal nerve ligation (SNL) in rats. The anti-nociceptive effect of gabapentin and IL-10 on morphine was examined over a 7-day period, and the effects of the anti-IL-10 and HO-1 inhibitor zinc protoporphyrin (ZnPP) on gabapentin/morphine co-injection were assessed. Drug administration was given over 7 days, and on day 8, both anti-inflammatory cytokine IL-10, a stress-induced protein HO-1 and pro-inflammatory cytokines IL-1β, IL-6 and TNF-α were measured. Gabapentin attenuated morphine tolerance over 7 days of co-administration, and reduced the expression of pro-inflammatory cytokines but increased IL-10 and HO-1 expression. The effect of gabapentin on morphine was partially blocked using the anti-IL-10 antibody or the HO-1 inhibitor zinc protoporphyrin. Our findings indicated that the anti-nociceptive effects of gabapentin on morphine might be caused by activation of the IL-10-HO-1 signalling pathway, which resulted in the inhibition of the expression of pro-inflammatory cytokines in neuropathic pain in the rat spinal cord.

Suppression of inflammatory cell trafficking and alveolar simplification by the heme oxygenase-1 product carbon monoxide

Bronchopulmonary dysplasia (BPD), a lung disease of prematurely born infants, is characterized in part by arrested development of pulmonary alveolae. We hypothesized that heme oxygenase (HO-1) and its byproduct carbon monoxide (CO), which are thought to be cytoprotective against redox stress, mitigate lung injury and alveolar simplification in hyperoxia-exposed neonatal mice, a model of BPD. Three-day-old C57BL/6J mice were exposed to air or hyperoxia (FiO2, 75%) in the presence or absence of inhaled CO (250 ppm for 1 h twice daily) for 21 days. Hyperoxic exposure increased mean linear intercept, a measure of alveolar simplification, whereas CO treatment attenuated hypoalveolarization, yielding a normal-appearing lung. Conversely, HO-1-null mice showed exaggerated hyperoxia-induced hypoalveolarization. CO also inhibited hyperoxia-induced pulmonary accumulation of F4/80+, CD11c+, and CD11b+ monocytes and Gr-1+ neutrophils. Furthermore, CO attenuated lung mRNA and protein expression of proinflammatory cytokines, including the monocyte chemoattractant CCL2 in vivo, and decreased hyperoxia-induced type I alveolar epithelial cell CCL2 production in vitro. Hyperoxia-exposed CCL2-null mice, like CO-treated mice, showed attenuated alveolar simplification and lung infiltration of CD11b+ monocytes, consistent with the notion that CO blocks lung epithelial cell cytokine production. We conclude that, in hyperoxia-exposed neonatal mice, inhalation of CO suppresses inflammation and alveolar simplification.

Cytoprotective role of heme oxygenase-1 and heme degradation derived end products in liver injury

The activation of heme oxygenase-1 (HO-1) appears to be an endogenous defensive mechanism used by cells to reduce inflammation and tissue damage in a number of injury models. HO-1, a stress-responsive enzyme that catabolizes heme into carbon monoxide (CO), biliverdin and iron, has previously been shown to protect grafts from ischemia/reperfusion and rejection. In addition, the products of the HO-catalyzed reaction, particularly CO and biliverdin/bilirubin, have been shown to exert protective effects in the liver against a number of stimuli, as in chronic hepatitis C and in transplanted liver grafts. Furthermore, the induction of HO-1 expression can protect the liver against damage caused by a number of chemical compounds. More specifically, the CO derived from HO-1-mediated heme catabolism has been shown to be involved in the regulation of inflammation; furthermore, administration of low concentrations of exogenous CO has a protective effect against inflammation. Both murine and human HO-1 deficiencies have systemic manifestations associated with iron metabolism, such as hepatic overload (with signs of a chronic hepatitis) and iron deficiency anemia (with paradoxical increased levels of ferritin). Hypoxia induces HO-1 expression in multiple rodent, bovine and monkey cell lines, but interestingly, hypoxia represses expression of the human HO-1 gene in a variety of human cell types (endothelial cells, epithelial cells, T cells). These data suggest that HO-1 and CO are promising novel therapeutic molecules for patients with inflammatory diseases. In this review, we present what is currently known regarding the role of HO-1 in liver injuries and in particular, we focus on the implications of targeted induction of HO-1 as a potential therapeutic strategy to protect the liver against chemically induced injury.

Hepatic gene expression patterns following trauma-hemorrhage: effect of posttreatment with estrogen

The aim of this study was to examine the role of estrogen on hepatic gene expression profiles at an early time point following trauma-hemorrhage in rats. Groups of injured and sham controls receiving estrogen or vehicle were killed 2 h after injury and resuscitation, and liver tissue was harvested. Complementary RNA was synthesized from each RNA sample and hybridized to microarrays. A large number of genes were differentially expressed at the 2-h time point in injured animals with or without estrogen treatment. The upregulation or downregulation of a cohort of 14 of these genes was validated by reverse transcription-polymerase chain reaction. This large-scale microarray analysis shows that at the 2-h time point, there is marked alteration in hepatic gene expression following trauma-hemorrhage. However, estrogen treatment attenuated these changes in injured animals. Pathway analysis demonstrated predominant changes in the expression of genes involved in metabolism, immunity, and apoptosis. Upregulation of low-density lipoprotein receptor, protein phosphatase 1, regulatory subunit 3C, ring-finger protein 11, pyroglutamyl-peptidase I, bactericidal/permeability-increasing protein, integrin, αD, BCL2-like 11, leukemia inhibitory factor receptor, ATPase, Cu transporting, α polypeptide, and Mk1 protein was found in estrogen-treated trauma-hemorrhaged animals. Thus, estrogen produces hepatoprotection following trauma-hemorrhage likely via antiapoptosis and improving/restoring metabolism and immunity pathways.

Pharmacologic inhibition of CXCL10 in combination with anti-malarial therapy eliminates mortality associated with murine model of cerebral malaria

Despite appropriate anti-malarial treatment, cerebral malaria (CM)-associated mortalities remain as high as 30%. Thus, adjunctive therapies are urgently needed to prevent or reduce such mortalities. Overproduction of CXCL10 in a subset of CM patients has been shown to be tightly associated with fatal human CM. Mice with deleted CXCL10 gene are partially protected against experimental cerebral malaria (ECM) mortality indicating the importance of CXCL10 in the pathogenesis of CM. However, the direct effect of increased CXCL10 production on brain cells is unknown. We assessed apoptotic effects of CXCL10 on human brain microvascular endothelial cells (HBVECs) and neuroglia cells in vitro. We tested the hypothesis that reducing overexpression of CXCL10 with a synthetic drug during CM pathogenesis will increase survival and reduce mortality. We utilized atorvastatin, a widely used synthetic blood cholesterol-lowering drug that specifically targets and reduces plasma CXCL10 levels in humans, to determine the effects of atorvastatin and artemether combination therapy on murine ECM outcome. We assessed effects of atorvastatin treatment on immune determinants of severity, survival, and parasitemia in ECM mice receiving a combination therapy from onset of ECM (day 6 through 9 post-infection) and compared results with controls. The results indicate that CXCL10 induces apoptosis in HBVECs and neuroglia cells in a dose-dependent manner suggesting that increased levels of CXCL10 in CM patients may play a role in vasculopathy, neuropathogenesis, and brain injury during CM pathogenesis. Treatment of ECM in mice with atorvastatin significantly reduced systemic and brain inflammation by reducing the levels of the anti-angiogenic and apoptotic factor (CXCL10) and increasing angiogenic factor (VEGF) production. Treatment with a combination of atorvastatin and artemether improved survival (100%) when compared with artemether monotherapy (70%), p<0.05. Thus, adjunctively reducing CXCL10 levels and inflammation by atorvastatin treatment during anti-malarial therapy may represent a novel approach to treating CM patients.

Activation of peroxisome proliferator activated receptor alpha ameliorates ethanol mediated liver fibrosis in mice

BACKGROUND

Peroxisome proliferator activated receptor alpha (PPARα) ameliorates ethanol induced hepatic steatohepatitis. However, its role in alcoholic liver fibrosis has not been fully clarified. The aim of this study was to elucidate the effect and the molecular basis of PPARα in ethanol induced liver fibrosis in mice.

METHODS

C57BL/6J mice were fed with 4% ethanol-containing Lieber-DeCarli liquid diet for eight weeks, and intraperitoneal injected with 5% carbon tetrachloride (CCl4) for the last four weeks to induce alcoholic liver fibrosis. PPARα agonist WY14643 was administered to mice during the last couple of weeks. The effects of PPARα induction on liver histology, activation of hepatic stellate cells (HSCs), as well as hepatic expression of inflammatory and fibrogenic factors were assessed.

RESULTS

The ethanol plus CCl4 treated mice exhibited progressive liver injury including piecemeal necrosis of hepatocytes, severe inflammatory cells infiltration and bridging fibrosis. This was accompanied by down-regulated hepatic expression of PPARα and the protective cytokines adiponectin, heme oxygenase-1 and interleukin-10. Additionally, up-regulation of the proinflammatory cytokine tumor necrosis factor-alpha, as well as the profibrogenic genes osteopontin, transforming growth factor-beta 1, visfatin, phosphatidylinositol 3-kinase, matrix metalloproteinase-2 (MMP-2) and MMP-9 was observed. WY14643 treatment restored expression of cytokines altered by ethanol plus CCl4 treatment and concomitantly ameliorated the liver injury.

CONCLUSIONS

The present study provides evidence for the protective role of PPARα induction in ameliorating ethanol mediated fibrosis through mediation of inflammatory and fibrogenic factors.

Protective effect of tropisetron on rodent hepatic injury after trauma-hemorrhagic shock through P38 MAPK-dependent hemeoxygenase-1 expression

Tropisetron can decrease inflammatory cell responses and alleviate organ damage caused by trauma-hemorrhage, but the mechanism of these effects remains unknown. The p38 mitogen-activated protein kinase/hemeoxygenase-1 (p38 MAPK/HO-1) pathway exerts anti-inflammatory effects on different tissues. The aim of this study was to investigate whether p38 MAPK/HO-1 plays any role in the tropisetron-mediated attenuation of hepatic injury after trauma-hemorrhage. Male Sprague-Dawley rats underwent trauma-hemorrhage (mean blood pressure maintained at approximately 35–40 mmHg for 90 min), followed by fluid resuscitation. During resuscitation, several treatment regimens were administered: four doses of tropisetron alone (0.1, 0.3, 1, 3 mg/kg body weight), or a single dose of tropisetron (1 mg/kg body weight) with and without a p38 MAPK inhibitor (SB-203580, 2 mg/kg body weight) or HO antagonist (chromium-mesoporphyrin, 2.5 mg/kg body weight). Various parameters were measured, and the animals were sacrificed at 24 h post-resuscitation. The results showed that trauma-hemorrhage increased the following parameters: plasma concentrations of aspartate (AST) and alanine aminotransferases (ALT), hepatic myeloperoxidase (MPO) activity, and levels of cytokine-induced neutrophil chemoattractant-1 and -3 (CINC-1 and CINC-3), intercellular adhesion molecule-1 (ICAM-1), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and macrophage inflammatory protein-1α (MIP-1α). These parameters were significantly improved in the tropisetron-treated rats subjected to trauma-hemorrhage. Tropisetron treatment also increased hepatic p38 MAPK and HO-1 expression compared with vehicle-treated trauma-hemorrhaged rats. Co-administration of SB-203580 or chromium-mesoporphyrin with tropisetron abolished the tropisetron-induced beneficial effects on the above parameters and hepatic injury. These results suggest that the protective effect of tropisetron administration on alleviation of hepatic injury after trauma-hemorrhage is likely mediated through p38 MAPK-dependent HO-1 expression.

Curcumin increases rat mesenchymal stem cell osteoblast differentiation but inhibits adipocyte differentiation

Background:

Curcumin is a phenolic natural product isolated from the rhizome of Curcuma longa (turmeric) and has effects on bone health and fat formation. The bone marrow mesenchymal stem cells (MSCs) are multipotent cells capable of differentiating into osteoblasts and adipocytes. Osteoblast differentiation of MSCs can be a result of upregulation of heme oxygenase (HO)-1 expression. Curcumin can potently induce HO-1 expression.

Objective:

The present study describes the effects of curcumin on rat MSC (rMSCs) differentiation into osteoblasts and adipocytes.

Materials and Methods:

Rat bone marrow MSCs were isolated and treated with or without curcumin. Osteoblast differentiation was confirmed and determined by alkaline phosphatase (ALP) activity, mineralized nodule formation, the expression of Runx2 (runt-related transcription factor 2) and osteocalcin. Adipocyte differentiation was determined by Oil red O staining and the expression of peroxisome proliferator-activated receptor-γ 2 (PPARγ2) and CCAAT/enhancer-binding protein (C/EBP) α.

Results:

Curcumin increased ALP activity and osteoblast-specific mRNA expression of Runx2 and osteocalcin when rMSCs were cultured in osteogenic medium. In contrast, curcumin decreased adipocyte differentiation and inhibited adipocyte-specific mRNA expression of PPARγ2 and C/EBPα when rMSCs were cultured in adipogenic medium. HO-1 expression was increased during osteogenic differentiation of rMSCs.

Conclusions:

These findings demonstrate that curcumin can promote osteogenic differentiation of rMSCs and inhibit adipocyte formation. The effect of curcumin on osteogenic differentiation of rMSCs is correlated with HO-1 expression.

Blockage of heme oxygenase-1 abrogates the protective effect of regulatory T cells on murine pregnancy and promotes the maturation of dendritic cells

Regulatory T cells (Treg) play an important role in fetal protection. They expand during normal pregnancy and protect fetal antigens from maternal effector cells. Their effect is associated with the up-regulation of tolerance-associated molecules at the fetal-maternal interface. Among these, Heme Oxygenase-1 (HO-1, coded by Hmox1) is of special importance as its blockage correlates with increased abortion rates and its up-regulation positively affects pregnancy outcome. Here, we aimed to investigate whether the protective effect of Treg is mediated by HO-1 in a mouse model. HO-1 blockage by Zinc Protoporhyrin (ZnPPIX) abrogated the protective effect of Treg transfer. We found that HO-1 is important in maintaining maternal dendritic cells (DCs) in an immature state, which contributes to the expansion of the peripheral Treg population. This brings to light one essential pathway through which Treg mediates the semi-allogeneic fetus tolerance.

Induction of Bcl-3 by acute binge alcohol results in toll-like receptor 4/LPS tolerance

Acute alcohol binge results in immunosuppression and impaired production of proinflammatory cytokines, including TNF-α. TNF-α production is induced by LPS, a TLR4 ligand, and is tightly regulated at various levels of the signaling cascade, including the NF-κB transcription factor. Here, we hypothesized that acute alcohol induces TLR4/LPS tolerance via Bcl-3, a nuclear protein and member of the NF-κB family. We found that acute alcohol pretreatment resulted in the same attenuating effect as LPS pretreatment on TLR4-induced TNF-α production in human monocytes and murine RAW 264.7 macrophages. Acute alcohol-induced Bcl-3 expression and IP studies revealed increased association of Bcl-3 with NF-κB p50 homodimers in alcohol-treated macrophages and in mice. ChIP assays revealed increased occupancy of Bcl-3 and p50 at the promoter region of TNF-α in alcohol-pretreated cells. To confirm that the Bcl-3-p50 complex regulates transcription/production of TNF-α during acute alcohol exposure, we inhibited Bcl-3 expression using a targeted siRNA. Bcl-3 knockdown prevented the alcohol-induced inhibition of TNF-α mRNA and protein production. In a mouse model of binge alcohol, an increase in Bcl-3 and a concomitant decrease in TNF-α but no change in IL-10 production were found in mice that received alcohol followed by LPS challenge. In summary, our novel data suggest that acute alcohol treatment in vitro and in vivo induces molecular signatures of TLR4/LPS tolerance through the induction of Bcl-3, a negative regulator of TNF-α transcription via its association with NF-κB p50/p50 dimers.

Intermittent hypoxia conditioning protects mitochondrial cytochrome c oxidase of rat cerebellum from ethanol withdrawal stress

Intermittent hypoxia (IH) conditioning minimizes neurocognitive impairment and stabilizes brain mitochondrial integrity during ethanol withdrawal (EW) in rats, but the mitoprotective mechanism is unclear. We investigated whether IH conditioning protects a key mitochondrial enzyme, cytochrome c oxidase (COX), from EW stress by inhibiting mitochondrially directed apoptotic pathways involving cytochrome c, Bax, or phosphor-P38 (pP38). Male rats completed two cycles of a 4-wk ethanol diet (6.5%) and 3 wk of EW. An IH program consisting of 5-10 bouts of 5-8 min of mild hypoxia (9.5-10% inspired O(2)) and 4 min of reoxygenation for 20 consecutive days began 3 days before the first EW period. For some animals, vitamin E replaced IH conditioning to test the contributions of antioxidant mechanisms to IH's mitoprotection. During the second EW, cerebellar-related motor function was evaluated by measuring latency of fall from a rotating rod (Rotarod test). After the second EW, COX activity in cerebellar mitochondria was measured by spectrophotometry, and COX, cytochrome c, Bax, and pP38 content were analyzed by immunoblot. Mitochondrial protein oxidation was detected by measuring carbonyl contents and by immunochemistry. Earlier IH conditioning prevented motor impairment, COX inactivation, depletion of COX subunit 4, protein carbonylation, and P38 phosphorylation during EW. IH did not prevent cytochrome c depletion during EW, and Bax content was unaffected by EW ± IH. Vitamin E treatment recapitulated IH protection of COX, and P38 inhibition attenuated protein oxidation during EW. Thus IH protects COX and improves cerebellar function during EW by limiting P38-dependent oxidative damage.