Therapeutic potential of HO-1 in autoimmune diseases

Effective protective mechanisms of HO-1 in diabetic complications: a narrative review

Diabetes mellitus is a metabolic disorder with persistent hyperglycemia caused by a variety of underlying factors. Chronic hyperglycemia can lead to diverse serious consequences and diversified complications, which pose a serious threat to patients. Among the major complications are cardiovascular disease, kidney disease, diabetic foot ulcers, diabetic retinopathy, and neurological disorders. Heme oxygenase 1 (HO-1) is a protective enzyme with antioxidant, anti-inflammatory and anti-apoptotic effects, which has been intensively studied and plays an important role in diabetic complications. By inducing the expression and activity of HO-1, it can enhance the antioxidant, anti-inflammatory, and anti-apoptotic capacity of tissues, and thus reduce the degree of damage in diabetic complications. The present study aims to review the relationship between HO-1 and the pathogenesis of diabetes and its complications. HO-1 is involved in the regulation of macrophage polarization and promotes the M1 state (pro-inflammatory) towards to the M2 state (anti-inflammatory). Induction of HO-1 expression in dendritic cells inhibits them maturation and secretion of pro-inflammatory cytokines and promotes regulatory T cell (Treg cell) responses. The induction of HO-1 can reduce the production of reactive oxygen species, thereby reducing oxidative stress and inflammation. Besides, HO-1 also has an important effect in novel programmed cell death such as pyroptosis and ferroptosis, thereby playing a protective role against diabetes. In conclusion, HO-1 plays a significant role in the occurrence and development of diabetic complications and is closely associated with a variety of complications. HO-1 is anticipated to serve as a novel target for addressing diabetic complications, and it holds promise as a potential therapeutic agent for diabetes and its associated complications. We hope to provide inspiration and ideas for future studies in the mechanism and targets of HO-1 through this review.

The Nrf2-HO-1 system and inflammaging

Nrf2 is a master transcriptional regulator of a number of genes involved in the adaptive response to oxidative stress. Among the genes upregulated by Nrf2, heme oxygenase-1 (HO-1) has received significant attention, given that the products of HO-1-induced heme catabolism have well established antioxidant and anti-inflammatory properties. This is evidenced in numerous models of inflammatory and autoimmune disease whereby induction of HO-1 expression or administration of tolerable amounts of HO-1 reaction products can ameliorate disease symptoms. Unsurprisingly, Nrf2 and HO-1 are now considered viable drug targets for a number of conditions. In recent years, the term 'inflammaging' has been used to describe the low-grade chronic inflammation observed in aging/aged cells. Increased oxidative stress is also a key factor associated with aging and there is convincing evidence that Nrf2, not only declines with age, but that Nrf2 and HO-1 can reduce cellular senescence and the senescence-associated secretory phenotype (SASP) which is now considered an underlying driver of age-related inflammatory disease. In this review, we describe the role of oxidative stress in 'inflammaging' and highlight the potential anti-aging properties of the Nrf2-HO-1 system. We also highlight established and newly emerging Nrf2 activators and their therapeutic application in age-related disease.

Nrf-2/ROS/NF-κB pathway is modulated by cynarin in human mesenchymal stem cells in vitro from ankylosing spondylitis

Ankylosing spondylitis (AS) is an immune chronic inflammatory disease, resulting in back pain, stiffness, and thoracolumbar kyphotic deformity. Based on the reported anti-inflammatory and antioxidant capacities of cynarin (Cyn), this study explored its protective role and molecular mechanisms in mesenchymal stem cells (MSCs) from AS. The target pathways and genes were verified using Western blotting, quantitative real-time polymerase chain reaction, and immunofluorescent staining, while molecular docking analysis was conducted. In AS-MSCs, we found that the expression levels of p-NF-κB, IL-6, IL-1β, and TNF-α were higher and IκB-α, Nrf-2, and HO-1 were lower compared with healthy control (HC)-MSCs. With molecular docking analysis, the biding affinities between Cyn and Keap1-Nrf-2 and p65-IκB-α were predicted. The mRNA and protein expression of p-NF-κB, IL-6, IL-1β, and TNF-α and the reactive oxygen species (ROS) generation were downregulated following Cyn administration. Meanwhile, the expression level of IκB-α, Nrf-2, and HO-1 were significantly increased after Cyn pretreatment. The results suggested that the protective mechanisms of Cyn in AS-MSCs were based on enhancing the antioxidation and suppression of excessive inflammatory responses via Nrf-2/ROS/NF-κB axis. Our findings demonstrate that Cyn is a potential candidate for alleviating inflammation in AS.

Analysis of the potential relationship between COVID-19 and Behcet's disease using transcriptome data

To investigate the potential role of COVID-19 in relation to Behcet's disease (BD) and to search for relevant biomarkers. We used a bioinformatics approach to download transcriptomic data from peripheral blood mononuclear cells (PBMCs) of COVID-19 patients and PBMCs of BD patients, screened the common differential genes between COVID-19 and BD, performed gene ontology (GO) and pathway analysis, and constructed the protein-protein interaction (PPI) network, screened the hub genes and performed co-expression analysis. In addition, we constructed the genes-transcription factors (TFs)-miRNAs network, the genes-diseases network and the genes-drugs network to gain insight into the interactions between the 2 diseases. We used the RNA-seq dataset from the GEO database (GSE152418, GSE198533). We used cross-analysis to obtain 461 up-regulated common differential genes and 509 down-regulated common differential genes, mapped the PPI network, and used Cytohubba to identify the 15 most strongly associated genes as hub genes (ACTB, BRCA1, RHOA, CCNB1, ASPM, CCNA2, TOP2A, PCNA, AURKA, KIF20A, MAD2L1, MCM4, BUB1, RFC4, and CENPE). We screened for statistically significant hub genes and found that ACTB was in low expression of both BD and COVID-19, and ASPM, CCNA2, CCNB1, and CENPE were in low expression of BD and high expression of COVID-19. GO analysis and pathway analysis was then performed to obtain common pathways and biological response processes, which suggested a common association between BD and COVID-19. The genes-TFs-miRNAs network, genes-diseases network and genes-drugs network also play important roles in the interaction between the 2 diseases. Interaction between COVID-19 and BD exists. ACTB, ASPM, CCNA2, CCNB1, and CENPE as potential biomarkers for 2 diseases.

HMOX1 pathway signature predicts clinical benefit from immunotherapy plus tyrosine kinase inhibitor therapy in advanced renal cell carcinoma

BACKGROUND

Immunotherapy (IO) plus tyrosine kinase inhibitor (TKI) emerged as standard first-line therapy for advanced renal cell carcinoma (RCC). The heme Oxygenase 1 (HMOX1) pathway is involved in tumor development and treatment resistance, which may affect the efficacy of TKI + IO.

METHODS

Two cohorts from our center (ZS-MRCC, ZS-HRRCC), one cohort from clinical trial (JAVELIN Renal 101) and the Cancer Genome Atlas (TCGA-KIRC) were enrolled. HMOX1 pathway signatures were determined for each sample by RNA-sequencing and gene set enrichment analysis. Immune infiltration was evaluated by flow cytometry. Response and progression-free survival (PFS) were set as primary endpoints.

RESULTS

Patients of low-HMOX1 signature showed higher objective response rate (43.5% vs. 27.3%) in ZS-MRCC cohort and longer PFS in both cohorts (ZS-MRCC cohort, p = 0.019; JAVELIN-101 cohort, p = 0.036). Patients in the high-HMOX1 signature arm also showed greater clinical benefit from TKI + IO, rather than TKI monotherapy (p < 0.001). In high-HMOX1 signature RCC tissues, CD8⁺ T cells showed a dysfunctional phenotype with decreased GZMB expression (Spearman's ρ = -0.32, p = 0.045). A risk score based on HMOX1 signature was further constructed by random forest approach, involving HMOX1 signature and immunologic features. In patients with a low risk level, TKI + IO combination therapy demonstrated longer PFS than TKI monotherapy (p < 0.001), however in individuals with a high risk score group, these two regimens did not give different advantages.

CONCLUSIONS

Our study identified the HMOX1 pathway signature was a potential prognostic factor of progression-free survival for TKI + IO combination therapy in the advanced RCC in different cohort, especially in first-line management of mRCC in the Javelin 101 cohort. Moreover, HMOX1 signature was associated with T-cell function in tumor environment.

Role of Nrf2 and HO-1 in intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a common age-related disease with clinical manifestations of lumbar and leg pain and limited mobility. The pathogenesis of IDD is mainly mediated by the death of intervertebral disc (IVD) cells and the imbalance of extracellular matrix (ECM) synthesis and degradation. Oxidative stress and inflammatory reactions are the important factors causing this pathological change. Therefore, the regulation of reactive oxygen species and production of inflammatory factors may be an effective strategy to delay the progression of IDD. In recent years, nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream regulated protein heme oxygenase-1 (HO-1) have received special attention due to their antioxidant, anti-inflammatory and anti-apoptotic protective effects. Recent studies have elucidated the important role of these two proteins in the treatment of IDD disease. However, Nrf2 and HO-1 have not been systematically reported in IDD-related diseases. Therefore, this review describes the biological characteristics of Nrf2 and HO-1, the relationship between Nrf2- and HO-1-regulated oxidative stress and the inflammatory response and IDD, and the progress in research on some extracts targeting Nrf2 and HO-1 to improve IDD. Understanding the role and mechanism of Nrf2 and HO-1 in IDD may provide novel ideas for the clinical treatment and development of Nrf2- and HO-1-targeted drugs.

FOXO3a Alleviates the Inflammation and Oxidative Stress via Regulating TGF-β and HO-1 in Ankylosing Spondylitis

This study aimed to investigate whether Forkhead box O3a (FOXO3a) modulates inflammation and oxidative stress in ankylosing spondylitis (AS). We applied bioinformatics analysis, quantitative real-time polymerase chain reaction, immunoblotting, enzyme linked immunosorbent assay, chromatin immunoprecipitation, and dual-luciferase reporter assay. Gene overexpression and knockdown of FOXO3a were conducted via lentivirus and small interfering RNA, respectively. Downregulated FOXO3a expression was first confirmed in AS patients. Interleukin-8 (IL-8) and IL-17A were highly expressed and negatively related with FOXO3a in AS. Total antioxidant capacity (T-AOC) were markedly decreased and positively associated with FOXO3a in AS. Overexpression of FOXO3a inhibited the secretion of inflammatory cytokines and promoted the production of antioxidant enzymes in Jurkat cells. Transforming growth factor-β (TGF-β) and heme oxygenase 1 (HO-1), which had binding sites to FOXO3a based on bioinformatics analysis, were abnormally expressed and positively related with FOXO3a. Accordingly, FOXO3a obviously elevated the protein and transcription levels of TGF-β and HO-1 in Jurkat cells. The above results were verified by silencing FOXO3a. Moreover, FOXO3a directly interacted with and promoted the transcription of TGF-β and HO-1. In summary, the modulation of cellular inflammation and oxidative stress via FOXO3a-mediated TGF-β and HO-1 activation is partly involved in the pathogenesis of AS.

Pinocembrin Reduces Keratinocyte Activation and Ameliorates Imiquimod-Induced Psoriasis-like Dermatitis in BALB/c Mice through the Heme Oxygenase-1/Signal Transducer and Activator of Transcription 3 Pathway

Psoriasis is an autoimmune disease characterized by chronic skin inflammation and excessive keratinocyte proliferation. The itchy, scaly, and erythematous lesions present on psoriatic skin negatively affect patients' quality of life. Pinocembrin is a flavonoid present in propolis, fruits, and vegetables. It exerts neuroprotective effects and was used for treating ischemic stroke in a human clinical trial. However, the effects of pinocembrin on psoriasis have never been examined. In this study, we evaluated the effects of pinocembrin on human HaCaT keratinocytes and BALB/c mice with imiquimod- (IMQ-) induced psoriatic dermatitis. In interferon-γ- (IFN-γ-) activated HaCaT cells, pinocembrin reduced the expression of inflammatory cytokines, namely, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and keratinocyte proliferation markers, namely, keratin (K)16, K17, and Ki-67. The mechanism underlying these inhibitory effects involved the regulation of the heme oxygenase- (HO-) 1/signal transducer and activator of transcription (STAT) 3 pathway. In the IMQ-induced psoriatic dermatitis mouse model, the topical application of pinocembrin significantly ameliorated the Skin Psoriasis Area and Severity Index score, epidermal thickness, inflammation, hyperplasia, hyperkeratosis, and cluster of differentiation (CD) 4⁺ T-cell infiltration. Expression of the inflammatory cytokines and keratinocyte proliferation markers in dorsal skin was significantly decreased in the pinocembrin-treated group. Meanwhile, in lesional skin, the expression of HO-1 was upregulated, but that of phospho-STAT3 (pSTAT3) was downregulated. Collectively, our results indicated the therapeutic potential of pinocembrin. Additional studies are warranted to evaluate its clinical benefits in patients with psoriasis.

Hypoxia-Induced Neuroinflammation in Alzheimer's Disease: Potential Neuroprotective Effects of Centella asiatica

Alzheimer's disease (AD) is a neurodegenerative disorder that is characterised by the presence of extracellular beta-amyloid fibrillary plaques and intraneuronal neurofibrillary tau tangles in the brain. Recurring failures of drug candidates targeting these pathways have prompted research in AD multifactorial pathogenesis, including the role of neuroinflammation. Triggered by various factors, such as hypoxia, neuroinflammation is strongly linked to AD susceptibility and/or progression to dementia. Chronic hypoxia induces neuroinflammation by activating microglia, the resident immune cells in the brain, along with an increased in reactive oxygen species and pro-inflammatory cytokines, features that are common to many degenerative central nervous system (CNS) disorders. Hence, interests are emerging on therapeutic agents and plant derivatives for AD that target the hypoxia-neuroinflammation pathway. Centella asiatica is one of the natural products reported to show neuroprotective effects in various models of CNS diseases. Here, we review the complex hypoxia-induced neuroinflammation in the pathogenesis of AD and the potential application of Centella asiatica as a therapeutic agent in AD or dementia.

Immunomodulatory Effects of Heme Oxygenase-1 in Kidney Disease

Kidney disease is a general term for heterogeneous damage that affects the function and the structure of the kidneys. The rising incidence of kidney diseases represents a considerable burden on the healthcare system, so the development of new drugs and the identification of novel therapeutic targets are urgently needed. The pathophysiology of kidney diseases is complex and involves multiple processes, including inflammation, autophagy, cell-cycle progression, and oxidative stress. Heme oxygenase-1 (HO-1), an enzyme involved in the process of heme degradation, has attracted widespread attention in recent years due to its cytoprotective properties. As an enzyme with known anti-oxidative functions, HO-1 plays an indispensable role in the regulation of oxidative stress and is involved in the pathogenesis of several kidney diseases. Moreover, current studies have revealed that HO-1 can affect cell proliferation, cell maturation, and other metabolic processes, thereby altering the function of immune cells. Many strategies, such as the administration of HO-1-overexpressing macrophages, use of phytochemicals, and carbon monoxide-based therapies, have been developed to target HO-1 in a variety of nephropathological animal models, indicating that HO-1 is a promising protein for the treatment of kidney diseases. Here, we briefly review the effects of HO-1 induction on specific immune cell populations with the aim of exploring the potential therapeutic roles of HO-1 and designing HO-1-based therapeutic strategies for the treatment of kidney diseases.

Anti-inflammatory effects of Flos Lonicerae Japonicae Water Extract are regulated by the STAT/NF-κB pathway and HO-1 expression in Virus-infected RAW264.7 cells

This study examined the effect of the Flos Lonicerae Japonicae water extract (FLJWE), chlorogenic acid, and luteolin on pseudorabies virus (PRV)-induced inflammation in RAW264.7 cells and elucidated related molecular mechanisms. The results revealed that FLJWE and luteolin, but not chlorogenic acid, inhibited the production of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and inflammatory cytokines in PRV-infected RAW 264.7 cells. We found that the FLJWE and luteolin suppressed nuclear factor (NF)-κB activation by inhibiting the phosphorylation of signal transducer and activator of transcription 1 and 3 (STAT1 and STAT3, respectively). Moreover, the FLJWE significantly upregulated the expression of pNrf2 and its downstream target gene heme oxygenase-1 (HO-1). Our data indicated that FLJWE and luteolin reduced the expression of proinflammatory mediators and inflammatory cytokines, such as COX-2 and iNOS, through the suppression of the JAK/STAT1/3-dependent NF-κB pathway and the induction of HO-1 expression in PRV-infected RAW264.7 cells. The findings indicate that the FLJWE can be used as a potential antiviral agent.

Dimethyl fumarate induced lymphopenia in multiple sclerosis: A review of the literature

Dimethyl fumarate (DMF) is a first line medication for multiple sclerosis. It has a favourable safety profile, however, there is concern regarding the occurrence of moderate-severe and sustained lymphopenia and the associated risk of progressive multifocal leukoencephalopathy. We carried out an extensive literature review to understand the molecular mechanisms underlying this adverse reaction. Dynamic changes in certain components of the immune system are likely to be important for the therapeutic effects of DMF, including depletion of memory T cells and decrease in activated T cells together with expansion of naïve T cells. Similar modifications were reported for the B cell components. CD8⁺ T cells are particularly susceptible to DMF-induced cell death, with marked reductions observed in lymphopenic subjects. The reasons underlying such increased sensitivity are not known, nor it is known how expansion of other lymphocyte subsets occurs. Understanding the molecular mechanisms underlying DMF action is challenging: in vivo DMF is rapidly metabolized to monomethyl fumarate (MMF), a less potent immunomodulator in vitro. Pharmacokinetics indicate that MMF is the main active species in vivo. However, the relative importance of DMF and MMF in toxicity remains unclear, with evidence presented in favour of either of the compounds as toxic species. Pharmacogenetic studies to identify genetic predictors of DMF-induced lymphopenia are limited, with inconclusive results. A role of the gut microbiome in the pharmacological effects of DMF is emerging. It is clear that further investigations are necessary to understand the mechanisms of DMF-induced lymphopenia and devise preventive strategies. Periodic monitoring of absolute lymphocyte counts, currently performed in clinical practise, allows for the early detection of lymphopenia as a risk-minimization strategy.

Naturally Derived Heme-Oxygenase 1 Inducers and Their Therapeutic Application to Immune-Mediated Diseases

Heme oxygenase (HO) is the primary antioxidant enzyme involved in heme group degradation. A variety of stimuli triggers the expression of the inducible HO-1 isoform, which is modulated by its substrate and cellular stressors. A major anti-inflammatory role has been assigned to the HO-1 activity. Therefore, in recent years HO-1 induction has been employed as an approach to treating several disorders displaying some immune alterations components, such as exacerbated inflammation or self-reactivity. Many natural compounds have shown to be effective inductors of HO-1 without cytotoxic effects; among them, most are chemicals present in plants used as food, flavoring, and medicine. Here we discuss some naturally derived compounds involved in HO-1 induction, their impact in the immune response modulation, and the beneficial effect in diverse autoimmune disorders. We conclude that the use of some compounds from natural sources able to induce HO-1 is an attractive lifestyle toward promoting human health. This review opens a new outlook on the investigation of naturally derived HO-1 inducers, mainly concerning autoimmunity.

Heme oxygenase-1 orchestrates the immunosuppressive program of tumor-associated macrophages

Tumor-associated macrophages (TAMs) contribute to the maintenance of a strong immunosuppressive environment, supporting tumor progression and resistance to treatment. To date, the mechanisms that drive acquisition of these immunosuppressive features are still poorly defined. Heme oxygenase-1 (HO-1) is the rate-limiting enzyme that catabolizes free heme. It displays important cytoprotective, antiinflammatory, and antioxidant properties. A growing body of evidence suggests that HO-1 may also promote tumor development. Herein, we show that HO-1 is highly expressed in monocytic cells in the tumor microenvironment (TME) once they differentiate into TAMs. Deletion of HO-1 in the myeloid compartment enhances the beneficial effects of a therapeutic antitumor vaccine by restoring CD8+ T cell proliferation and cytotoxicity. We further show that induction of HO-1 plays a major role in monocyte education by tumor cells by modulating their transcriptional and epigenetic programs. These results identify HO-1 as a valuable therapeutic target to reprogram the TME and synergize with current cancer therapies to facilitate antitumor response.

Cryptotanshinone Attenuates Inflammatory Response of Microglial Cells via the Nrf2/HO-1 Pathway

Cryptotanshinone (CTN), a monomer compound extracted from the dried roots and rhizomes of Salvia miltiorrhiza Bge, has a variety of pharmacological effects. However, little research has been done on the mechanism of CTN in attenuating neuroinflammation. The present study aimed to investigate whether CTN can ameliorate neuroinflammation induced by lipopolysaccharide (LPS) through the Nrf2/heme-oxygenase 1 (HO-1) signaling pathway in BV-2 microglial cells. We found that CTN attenuated the upregulated expression of inducible nitric oxide synthase, cyclooxygenase 2, NOD-like receptor pyrin domains-3, and nitric oxide induced by LPS in microglial cells. In addition, it curtailed the increased release of pro-inflammatory cytokines such as interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α in LPS-activated microglial cells. Furthermore, CTN significantly increased the levels of NF-κB, Nrf2, HO-1, and Akt proteins. We demonstrated that the anti-inflammatory action of CTN in BV-2 microglial cells was partially through the activation of the Nrf2/HO-1 pathway, which was regulated by the PI3K/Akt signaling pathway. Taken together, our results indicated that CTN downregulated the production and release of proinflammatory mediators in BV-2 microglial cells through activating the Nrf2/HO-1 pathway and subsequently protected neurons from inflammatory injury.

Sustained bile drainage decreases the organs injuries via inflammation-associated factors modulation in a severe acute pancreatitis rat model

The timely and effective treatment for severe acute pancreatitis (SAP) is favorable to prognosis. Decompression of the bile duct might be a feasible way to decrease the progression of SAP. The present study investigated the effects of sustained bile external drainage on organs injury caused by SAP in Sprague-Dawley (SD) rats and the mechanisms involved. A total of 72 female SD rats weighting 190-230 g were randomly divided into four groups (n=18): Sham operation group (SOG), SOG + bile drainage group (BDG), SAP group, and SAP + BDG. Sodium taurocholate solution (4%; 1 mg/kg body weight) was used to set up SAP model via injection of retrograde puncture of biliopancreatic duct through the duodenum. A cannula was inserted into the bile duct and fixed externally to establish BDG model. At each time points (t=3, 6, 12; n=6), tissues from the liver, lung, and pancreas, and blood samples were collected. Serum amylase (AMY) was analyzed in all the samples. The levels of tumor necrosis factor-α (TNF-α), heme oxygenase-1 (HO-1), interleukin-10 (IL-10) and high mobility group box 1 (HMGB1) were detected by ELISA. Hematoxylin-eosin staining was performed to observe the histopathological changes, and nuclear transcription factor (NF)-κB-p65 levels in the pancreas were analyzed by western blotting. The data indicated that BDG alleviated the SAP progression and multiple organs injuries. Meanwhile, the histopathological changes of the pancreas, liver, and lungs were improved by BDG. BDG decreased the pathological scores of pancreas significantly (P<0.05). The levels of AMY, TNF-α, HMGB1, and NF-κB-p65 were significantly downregulated by BDG (P<0.05), while the level of HO-1 was upregulated and IL-10 was unchanged. In summary, BDG may attenuate the multiple organs injuries caused by SAP via downregulation of TNF-α, HMGB1, NF-κB-p65 and upregulation of HO-1.

DC32, a Dihydroartemisinin Derivative, Ameliorates Collagen-Induced Arthritis Through an Nrf2-p62-Keap1 Feedback Loop

Artemisinins have been reported to have diverse functions, such as antimalaria, anticancer, anti-inflammation, and immunoregulation activities. DC32 [(9α,12α-dihydroartemisinyl) bis(2′-chlorocinnmate)], a dihydroartemisinin derivative possessing potent immunosuppressive properties, was synthesized in our previous study. Collagen-induced arthritis (CIA) in DBA/1 mice and inflammatory model in NIH-3T3 cells were established to evaluate the effect of DC32 on RA and discover the underlying mechanisms. The results showed that DC32 could markedly alleviate footpad inflammation, reduce cartilage degradation, activate the Nrf2/HO-1 signaling pathway, and increase the transcription of p62 in DBA/1 mice with CIA. Further mechanistic exploration with NIH-3T3 cells indicated that DC32 could increase the transcription, expression, and nuclear translocation of Nrf2. In addition, DC32 promoted degradation of Keap1 protein and upregulated HO-1 and p62 expression. Furthermore, the effect of DC32 on Keap1 degradation could be prevented by p62 knockdown using siRNA. Administration of DC32 could inhibit the activation of Akt/mTOR and ERK, and pretreatment of NIH-3T3 cells with the autophagy inhibitor 3-methyladenine (3-MA) attenuated the degradation of Keap1 induced by DC32. These results suggest that DC32 inhibits the degradation of Nrf2 by promoting p62-mediated selective autophagy and that p62 upregulation contributed to a positive feedback loop for persistent activation of Nrf2. In summary, our present study demonstrated that DC32 significantly suppressed rheumatoid arthritis (RA) via the Nrf2-p62-Keap1 feedback loop by increasing the mRNA and protein levels of Nrf2 and inducing p62 expression. These findings provide new mechanisms for artemisinins in RA treatment and a potential strategy for discovering antirheumatic drugs.

Hmox1 promotes osteogenic differentiation at the expense of reduced adipogenic differentiation induced by BMP9 in C3H10T1/2 cells

Mesenchymal stem cells (MSCs) are multipotent progenitors that can differentiate into a variety of cell types under proper stimuli. Bone morphogenetic protein 9 (BMP9) is able to simultaneously induce both adipogenic and osteogenic differentiation of MSCs although the regulatory molecules involved remain to be fully identified and characterized. Heme oxygenase 1 (Hmox1) plays an essential role not only in fat metabolism, but also in bone development. In the present study, we investigated the functional role of Hmox1 in BMP9-induced osteogenic/adipogenic differentiation in MSCs line C3H10T1/2 and probed the possible mechanism involved. We found that BMP9 promoted the endogenous expression of Hmox1 in C3H10T1/2 cells. Overexpression of Hmox1 or cobalt protoporphyrin (CoPP), an inducer of Hmox1, increased BMP9-induced osteogenic differentiation in vitro. Subcutaneous stem cell implantation in nude mice further confirmed that Hmox1 potentiated BMP9-induced ectopic bone formation in vivo. In contrast, Hmox1 reduced BMP9-induced adipogenic differentiation in C3H10T1/2 cells. Although had no obvious effect on BMP9-induced Smad1/5/8 phosphorylation, Hmox1 enhanced phosphorylation of p38, and AKT, while decreased phosphorylation of ERK1/2. Furthermore, Hmox1 increased total β-catenin protein level, and promoted the nuclear translocation of β-catenin in C3H10T1/2 cells. Taken together, our study strongly suggests that Hmox1 is likely to potentiate osteogenic differentiation and yet decrease adipogenic differentiation induced by BMP9 possibly through regulation of multiple signaling pathways.

Ultraviolet-A1 irradiation therapy for systemic lupus erythematosus

Systemic lupus erythematosus (lupus, SLE) is a chronic autoimmune disease characterized by the production of autoantibodies, which bind to antigens and are deposited within tissues to fix complement, resulting in widespread systemic inflammation. The studies presented herein are consistent with hyperpolarized, adenosine triphosphate (ATP)-deficient mitochondria being central to the disease process. These hyperpolarized mitochondria resist the depolarization required for activation-induced apoptosis. The mitochondrial ATP deficits add to this resistance to apoptosis and also reduce the macrophage energy that is needed to clear apoptotic bodies. In both cases, necrosis, the alternative pathway of cell death, results. Intracellular constituents spill into the blood and tissues, eliciting inflammatory responses directed at their removal. What results is “autoimmunity.” Ultraviolet (UV)-A1 photons have the capacity to remediate this aberrancy. Exogenous exposure to low-dose, full-body, UV-A1 radiation generates singlet oxygen. Singlet oxygen has two major palliative actions in patients with lupus and the UV-A1 photons themselves have several more. Singlet oxygen depolarizes the hyperpolarized mitochondrion, triggering non-ATP-dependent apoptosis that deters necrosis. Next, singlet oxygen activates the gene encoding heme oxygenase (HO-1), a major governor of systemic homeostasis. HO-1 catalyzes the degradation of the oxidant heme into biliverdin (converted to bilirubin), Fe, and carbon monoxide (CO), the first three of these exerting powerful antioxidant effects, and in conjunction with a fourth, CO, protecting against injury to the coronary arteries, the central nervous system, and the lungs. The UV-A1 photons themselves directly attenuate disease in lupus by reducing B cell activity, preventing the suppression of cell-mediated immunity, slowing an epigenetic progression toward SLE, and ameliorating discoid and subacute cutaneous lupus. Finally, a combination of these mechanisms reduces levels of anticardiolipin antibodies and protects during lupus pregnancy. Capping all of this is that UV-A1 irradiation is an essentially innocuous, highly manageable, and comfortable therapeutic agency.

Upregulation of HO-1 Attenuates LPS-Stimulated Proinflammatory Responses Through Downregulation of p38 Signaling Pathways in Rat Ovary

Heme oxygenase-1 (HO-1) plays a key role in the regulation of the inflammatory response. However, the specific mechanism underlying the anti-inflammatory role of HO-1 in the reproductive system is unclear. The aim of this study was to evaluate the role of the mechanism of HO-1 in the regulation of the inflammatory response stimulated by lipopolysaccharide (LPS) in rat ovary. LPS-stimulated inflammatory models were established. Rats were pretreated with HO-1 activator (hemin) or inhibitor (ZnPP) before LPS stimulation, and we evaluated the expression of HO-1 by real-time PCR and Western blot. The messenger RNA (mRNA) expression and secretion of IL-1β and IL-6 in rat ovary were analyzed using real-time PCR and ELISA. In addition, we also analyzed the p38 and p-p38 protein expression in the ovary. Our results demonstrate that HO-1 is an anti-inflammatory factor in LPS-stimulated ovary, which regulates the inflammatory response through downregulation of p38 signaling pathways in rat ovary.

Heme oxygenase-1 promoter polymorphisms and risk of spina bifida

BACKGROUND

Spina bifida is the most common form of neural tube defects (NTDs). Etiologies of NTDs are multifactorial, and oxidative stress is believed to play a key role in NTD development. Heme oxygenase (HO), the rate-limiting enzyme in heme degradation, has multiple protective properties including mediating antioxidant processes, making it an ideal candidate for study. The inducible HO isoform (HO-1) has two functional genetic polymorphisms: (GT)n dinucleotide repeats and A(-413)T SNP (rs2071746), both of which can affect its promoter activity. However, no study has investigated a possible association between HO-1 genetic polymorphisms and risk of NTDs.

METHODS

This case-control study included 152 spina bifida cases (all myelomeningoceles) and 148 non-malformed controls obtained from the California Birth Defects Monitoring Program reflecting births during 1990 to 1999. Genetic polymorphisms were determined by polymerase chain reaction and amplified fragment length polymorphisms/restriction fragment length polymorphisms using genomic DNA extracted from archived newborn blood spots. Genotype and haplotype frequencies of two HO-1 promoter polymorphisms between cases and controls were compared.

RESULTS

For (GT)n dinucleotide repeat lengths and the A(-413)T SNP, no significant differences in allele frequencies or genotypes were found. Linkage disequilibrium was observed between the HO-1 polymorphisms (D': 0.833); however, haplotype analyses did not show increased risk of spina bifida overall or by race/ethnicity.

CONCLUSION

Although, an association was not found between HO-1 polymorphisms and risk of spina bifida, we speculate that the combined effect of low HO-1 expression and exposures to known environmental oxidative stressors (low folate status or diabetes), may overwhelm antioxidant defenses and increase risk of NTDs and warrants further study.