Cloning and characterization of the human selenoprotein P promoter. Response of selenoprotein P expression to cytokines in liver cells

We isolated an 18-kilobase (kb) genomic selenoprotein P clone from a human placenta library and cloned, sequenced, and characterized the 5'-flanking region of the human selenoprotein P gene. Sequence analysis revealed an intron between base pairs (bp) -13 and -14 upstream of the ATG codon and another one between bp 534 and 535 of the coding region. The major transcription start site of selenoprotein P in human HepG2 hepatocarcinoma cells was mapped to bp -70 by 5'-rapid amplification of cDNA ends and by primer extension. 1.8 kb of the 5'-flanking sequence were fused to a luciferase reporter gene. They exhibited functional promoter activity in HepG2 hepatocarcinoma and Caco2 colon carcinoma cells in transient transfection experiments. Treatment of transfected HepG2 cells with the cytokines interleukin 1beta, tumor necrosis factor alpha, and interferon gamma repressed promoter activity. Nuclear extracts of interferon gamma-treated cells bound to a signal transducer and activator of transcription response element of the promoter in gel retardation experiments. By transfection of promoter-deletion constructs, a TATA box and a putative SP1 site were identified to be necessary for selenoprotein P transcription. These data indicate that the human selenoprotein P gene contains a strong promoter that is cytokine responsive. Furthermore, selenoprotein P, secreted by the liver, might react as a negative acute phase protein.

Selenoproteins are expressed in fetal human osteoblast-like cells

Selenoproteins are involved in mechanisms of cell differentiation and defense. We investigated the expression of glutathione peroxidases, as well as other selenoproteins, in fetal human osteoblasts (hFOB-cells). Using 75-selenium metabolic labelling of viable hFOB-cells, we identified several selenoproteins in cell lysates of about 45-80 kDa and in the migration range of 14 kDa to 24 kDa. Cells expressed low mRNA levels of both cellular glutathione peroxidase and plasma glutathione peroxidase mRNA as analysed by Southern analysis of RT-PCR products. Basal cellular glutathione peroxidase enzyme activity in hFOB-cells (19.7 nmol NADPH oxidised per min and microg protein) was further increased 2.5-fold by the addition of 100 nM sodium selenite to the culture medium for 3 days. Furthermore, expression of selenoprotein P mRNA was demonstrated by RT-PCR. hFOB-cells did not show activities of the selenoproteins type I or type II 5'-deiodinase. In summary, we identified cellular glutathione peroxidase, plasma glutathione peroxidase and selenoprotein P among of a panel of several 75-selenium labelled proteins in human fetal osteoblasts. The expression of selenoproteins like glutathione peroxidases in hFOB-cells represents a new system of osteoblast antioxidative defense that may be relevant for the protection against hydrogen peroxide produced by osteoclasts during bone remodelling.

Expression of selenoproteins in various rat and human tissues and cell lines

Various rat and human tissues and cell lines naturally exposed to endogenous or exogenous oxidative stress were examined for their pattern of selenoprotein transcripts. Selenoprotein P mRNA was mainly expressed in rat kidney, testis, liver and lung. In testis, a high phospholipid hydroperoxide glutathione peroxidase (PHGPx) but only a weak cytosolic glutathione peroxidase (cGPx) signal was obtained. In kidney, spleen, heart, liver and lung cGPx mRNA levels were higher than those of PHGPx and for both only weak signals were obtained with brain mRNA. The Northern blot results concerning the tissue distribution of cGPx in the rat were fully supported by activity measurements. None of the human tissues revealed a PHGPx mRNA signal, whereas selenoprotein P transcripts were present in all human tissues with the highest abundance in heart, liver, and lung, tissues which also exhibited strong cGPx signals. The gastrointestinal glutathione peroxidase (GPx-GI) was only expressed in human liver and colon liver. Liver, the organ that showed the broadest repertoire of selenoproteins, has to cope with reactive oxygen intermediates produced during detoxification reactions. Human cell lines of the myeloic system that may be exposed to oxidative stress during inflammatory processes showed distinct cGPx signals: epithelial cells showed low cGPx signals. Similar cGPx mRNA levels were found in normal human thyroid tissue and thyroid carcinoma cells. Among the human cell lines selenoprotein P expression was detected in HepG2 and HTh74 thyroid cells. Our data confirm the necessity of getting specific information on distinct tissue- and cell-specific patterns of selenoprotein expression as endpoints of selenium supply and biological function of the selenoprotein family. Analysis of total selenium contents of tissues or body fluids only provides integrative information on the global selenium status of individuals.

Proinflammatory cytokines inhibit the expression and function of human type I 5'-deiodinase in HepG2 hepatocarcinoma cells

OBJECTIVE

The sick euthyroid syndrome in critically ill patients without primary disease of the thyroid gland is characterised by low serum total triiodothyronine (T3), normal to elevated thyroxine (T4), elevated reverse T3 (rT3) and normal TSH levels. The aim of this work was to clarify if impaired T4 and rT3 5'-deiodination is an underlying mechanism.

DESIGN AND METHODS

We analysed the effect of the human recombinant proinflammatory cytokines interleukin (IL)-6 and IL-1beta, tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) on human type I 5'-iodothyronine deiodinase (5'DI) enzyme activity in the human hepatocarcinoma cell line HepG2, i.e. in a homologous human system. Furthermore, we analysed transcriptional effects of the cytokines by transient transfection assays using the luciferase or chloramphenicol acetyltransferase (CAT) reporter genes under the control of 1480 nucleotides of the human 5'DI promoter.

RESULTS

IL-6 at 500 pg/ml and TNF-alpha at 25 ng/ml had no significant effect, whereas 100 ng/ml IFN-gamma or 10 ng/ml IL-1beta reduced 5'DI enzyme activity to 77.9 and 59.5% of control values. IFN-gamma did not alter, IL-6 and TNF-alpha moderately decreased (in the case of IL-6 only in the CAT system), and IL-1beta (0.01-10 ng/ml) dose-dependently inhibited 5'DI promoter activity to a minimum of 38.1%.

CONCLUSION

IL-1beta inhibited both 5'DI enzyme and promoter activity and, thus, may exert its effect on thyroid hormone metabolism at least partially through direct inhibition of hepatic 5'DI gene transcription.

Expression pattern of gastrointestinal selenoproteins--targets for selenium supplementation

There is experimental and epidemiological evidence for an association between low selenium levels and gastrointestinal cancer incidence, prevalence, and mortality. To identify targets for selenium supplementation in the human digestive tract, we examined mRNA expression of various selenocysteine-containing proteins in normal mucosa biopsy specimens. Tissue samples from the esophagus and from different sites of the stomach, small bowel, and colon were obtained during endoscopies of the upper and lower gastrointestinal tract. Northern blot analyses revealed a lack of cytosolic glutathione peroxidase mRNA but a differential mRNA expression pattern of gastrointestinal and plasma glutathione peroxidase, selenoprotein P, and thioredoxin reductase. Glutathione peroxidase and thioredoxin reductase activities were detected in the mucosa of all biopsies, but the differential pattern did not reflect the differential mRNA steady-state levels. In addition to gastrointestinal glutathione peroxidase, which was found to play a role in colon cancer resistance, we identified further gastrointestinal selenoproteins, which may be involved in gastrointestinal cell defense and cell differentiation.

The influence of the cytokines Il-1beta and INFgamma on the expression of selenoproteins in the human hepatocarcinoma cell line HepG2

Metabolic labeling of HepG2 cells with 75selenite indicated the expression of more than four selenoproteins in the 80 to 45 kDa range and more than four selenoproteins in the 24 to 14 kDa range. Although there were no significant changes in the total protein content, determined by the method of BioRad, the densitometric analysis of the autoradiogramms showed a reduced expression of all labeled selenoproteins in the cell lysates of HepG2 after cytokine treatment for 24 hours. A stronger reduction was observed after treatment with Il-1beta than with IFNgamma. Moreover, the inhibitory effects were more significant for those selenoproteins in the higher molecular mass range. Our data on the inhibition of selenoprotein synthesis and on repression of SeP promoter activity show that the expression of selenoproteins, especially of SeP, is influenced by acute phase reaction and pro-inflammatory reactions.

Transforming growth factor-beta1 inhibits expression of selenoprotein P in cultured human liver cells

The effect of cytokines on the expression of selenoprotein P (SeP) in the human liver cell line HepG2 was investigated. Treatment with interleukin-1beta, interferon-gamma, and tumor necrosis factor-alpha had no effect on SeP levels in culture media or on SeP mRNA expression. Conversely, Western analysis revealed a dose-dependent reduction of SeP content in culture medium after treatment with transforming growth factor (TGF)-beta1 with an 1C50 of 31 pM. Treatment with 100 pM TGF-51 for 48 h led to a decrease to 21 +/- 9% of controls. RT-PCR analysis of SeP mRNA expression demonstrated an inhibition of SeP transcription to 40+/-2% of control levels after 24 h. The expression of a luciferase reporter construct under control of the human SeP promoter was downregulated by TGF-beta1 treatment in a dose-dependent fashion indicating a transcriptional regulation of the SeP gene by TGF-beta1.

Identification of an element within the promoter of human selenoprotein P responsive to transforming growth factor-beta

Selenoprotein P (SeP) is a plasma protein that contains up to 10 selenocysteine residues and accounts for about 50% of total selenium in human plasma. We have previously shown that SeP expression in the human liver cell line HepG2 is inhibited by transforming growth factor (TGF)-beta1 on a transcriptional level. Smad proteins are the transcriptional mediators of TGF-beta signalling and putative Smad-binding elements (SBE) comprising the core sequence CAGACA are present at two positions in the SeP promoter. The aim of our study was to investigate whether Smad molecules are involved in inhibition of SeP expression by TGF-beta1 and to locate the promoter region critical for this effect. As seen in electrophoretic-mobility-shift assays, TGF-beta1 treatment led to enhanced binding of nuclear proteins to a putative SBE from the SeP promoter. Overexpression of Smad 3 and 4, but not of Smad 2, resulted in a marked down-regulation of SeP mRNA expression. Similar effects were observed for luciferase expression under control of a human SeP-promoter construct. Deletion as well as point-mutation of putative SBEs led to a loss of promoter sensitivity towards TGF-beta1 treatment. Hence, we demonstrated an involvement of Smad 3 and 4 in transcriptional regulation of SeP by TGF-beta1 and we were able to identify the TGF-beta-responsive element in the SeP promoter.

Modulation of selenoprotein P expression by TGF-beta(1) is mediated by Smad proteins

Selenoprotein P (SeP) is a selenium-rich plasma protein which accounts for more than 50% this study, the effect of TGF-beta(1) on the expression of SeP in the human liver cell line HepG2 was investigated. Western analysis revealed a dose-dependent reduction of SeP content in cell supernatant. RT-PCR analysis of SeP-mRNA expression demonstrated a marked inhibition and a reporter gene under control of the SeP promoter was negatively regulated by TGF-beta(1). Smad proteins are the transcriptional mediators of TGF-beta signaling. A putative Smad-binding element (SBE) is present in the SeP promoter. In electrophoretic-mobility-shift assays, TGF-beta(1) enhanced the binding of nuclear proteins to this SBE. Overexpression of Smad3 and 4 resulted in a downregulation of SeP-promoter activity whereas deletion of the SBE led to a loss of TGF-beta(1) responsiveness. We conclude that SeP expression is modulated by the binding of Smad3/4 complexes to a functional SBE in the SeP promoter.

Elezanumab, a human anti-RGMa monoclonal antibody, promotes neuroprotection, neuroplasticity, and neurorecovery following a thoracic hemicompression spinal cord injury in non-human primates

Spinal cord injury (SCI) is a devastating condition characterized by loss of function, secondary to damaged spinal neurons, disrupted axonal connections, and myelin loss. Spontaneous recovery is limited, and there are no approved pharmaceutical treatments to reduce ongoing damage or promote repair. Repulsive guidance molecule A (RGMa) is upregulated following injury to the central nervous system (CNS), where it is believed to induce neuronal apoptosis and inhibit axonal growth and remyelination. We evaluated elezanumab, a human anti-RGMa monoclonal antibody, in a novel, newly characterized non-human primate (NHP) hemicompression model of thoracic SCI. Systemic intravenous (IV) administration of elezanumab over 6 months was well tolerated and associated with significant improvements in locomotor function. Treatment of animals for 16 weeks with a continuous intrathecal infusion of elezanumab below the lesion was not efficacious. IV elezanumab improved microstructural integrity of extralesional tissue as reflected by higher fractional anisotropy and magnetization transfer ratios in treated vs. untreated animals. IV elezanumab also reduced SCI-induced increases in soluble RGMa in cerebrospinal fluid, and membrane bound RGMa rostral and caudal to the lesion. Anterograde tracing of the corticospinal tract (CST) from the contralesional motor cortex following 20 weeks of IV elezanumab revealed a significant increase in the density of CST fibers emerging from the ipsilesional CST into the medial/ventral gray matter. There was a significant sprouting of serotonergic (5-HT) fibers rostral to the injury and in the ventral horn of lower thoracic regions. These data demonstrate that 6 months of intermittent IV administration of elezanumab, beginning within 24 h after a thoracic SCI, promotes neuroprotection and neuroplasticity of key descending pathways involved in locomotion. These findings emphasize the mechanisms leading to improved recovery of neuromotor functions with elezanumab in acute SCI in NHPs.

[Selenoproteins in bone, gastrointestinal tract and thyroid gland of the human]

BASIS

Selenium is an essential trace element, which is incorporated as selenocysteine (secys) into specific proteins in a regulated fashion. In the presence of a hairpin loop structure within the 3' untranslated region of the mRNA the opal stop codon UGA is coding for selenocysteine. Selenoprotein functions are dependent on secys incorporation. Members of the family of deiodinases as well as the family of glutathione peroxidases, selenoprotein P and thioredoxin reductase are selenoproteins.

DISCUSSION

Bone, the intestine and the thyroid rely on antioxidant systems against potential cell and DNA damage through endogenous and environmental peroxides and reactive oxygen species (ROS) potentially promoting inflammation and tumorigenesis. Optimized cell defense through antioxidant selenoproteins requires optimal selenium supplementation of the organism. We have analyzed the expression of selenoproteins in these tissues, thus providing molecular tools to further elucidate optimal selenium supply on a cellular level.

CONCLUSION

Clinical intervention studies that focus on the development of disease must confirm the relevance of optimized selenium supply for the pathogenesis, prevention and therapy of metabolic bone disease as well as chronic (autoimmune) inflammation and tumorigenesis in the thyroid and intestine.

Safety, Tolerability, and Pharmacokinetics of Single Doses of Exidavnemab (BAN0805), an Anti-α-Synuclein Antibody, in Healthy Western, Caucasian, Japanese, and Han Chinese Adults

Exidavnemab is a monoclonal antibody (mAb) with a high affinity and selectivity for pathological aggregated forms of α-synuclein and a low affinity for physiological monomers, which is in clinical development as a disease-modifying treatment for patients with synucleinopathies such as Parkinson's disease. Safety, tolerability, pharmacokinetics, immunogenicity, and exploratory biomarkers were assessed in two separate Phase 1 single ascending dose studies, including single intravenous (IV) (100 to 6000 mg) or subcutaneous (SC) (300 mg) administration of exidavnemab in healthy volunteers (HVs). Across the two studies, a total of 98 Western, Caucasian, Japanese, and Han Chinese HVs were enrolled, of which 95 completed the study. Exidavnemab was generally well tolerated. There were no serious adverse events or safety issues identified in laboratory analyses. Headache, asymptomatic COVID-19, back pain, and post lumbar puncture syndrome were the most frequently reported treatment-emergent adverse events. Following IV infusion, the pharmacokinetics of exidavnemab was approximately dose linear in the range 100-6000 mg. The terminal half-life was approximately 30 days, and the exposure was comparable across Western, Caucasian, Japanese, and Han Chinese volunteers. The absolute SC bioavailability was ∼71%. Cerebrospinal fluid exposure relative to serum after single dose was within the range expected for mAbs (approximately 0.2%). The anti-drug antibody rates were low and there was no effect of immunogenicity on the pharmacokinetics or safety. Dose-dependent reduction of free α-synuclein in plasma was observed. In summary, exidavnemab was found to have an excellent pharmacokinetic profile and was well tolerated in HVs, supporting the continued clinical development.

[Expert assessment of medical treatment errors--a new responsibility for the medical service of health insurance]

During the past few years there has been an enormous increase of inquiries for medical certificates concerning suspected mistakes in medical treatment (medical malpractice). The profound changes of the social circumstances and the social law (e.g. section 66 SGB V) are responsible for this situation. The legal involvement of the "Gesetzliche Krankenversicherung" (GKV) and the "Medizinischer Dienst der Krankenversicherung" (MDK) into social legislation concerning the expert opinion are mentioned. The general development of the judgement of medical malpractice and its legal background, which bases on the contract between doctor and patient, is shown. As a practical example serves the description of the procedure of judging medical malpractice in the MDK. First statistical results, which have been developed since summer 1997 in Hamburg are presented. Some interesting tendencies are obvious: orthopedics and surgery are involved with more than 50%. "Characteristic mistakes in therapy" are the most important question for the expert opinion. Creating a medical certificate concerning medical malpractice takes about 6-12 weeks. This tendency is decreasing because of fast learning procedures, caused by the increasing demand of expert opinions. The medical judgement of medical malpractice will become one of the main tasks of the medical service in health insurance. The "MDK's" have to adapt to this change in tasks in medical, legal and organisation-technical respect, if they want to offer competent and up to date judgement in future times.

Neutralizing RGMa with Elezanumab Promotes Cerebroprotection and Recovery in Rabbit Middle Cerebral Artery Occlusion

Repulsive guidance molecule A (RGMa) is an inhibitor of neuronal growth and survival which is upregulated in the damaged central nervous system following acute spinal cord injury (SCI), traumatic brain injury, acute ischemic stroke (AIS), and other neuropathological conditions. Neutralization of RGMa is neuroprotective and promotes neuroplasticity in several preclinical models of neurodegeneration and injury including multiple sclerosis, AIS, and SCI. Given the limitations of current treatments for AIS due to narrow time windows to intervention (TTI), and restrictive patient selection criteria, there is significant unmet need for therapeutic agents that enable tissue survival and repair following acute ischemic damage for a broader population of stroke patients. In this preclinical study, we evaluated whether elezanumab, a human anti-RGMa monoclonal antibody, could improve neuromotor function and modulate neuroinflammatory cell activation following AIS with delayed intervention times up to 24 h using a rabbit embolic permanent middle cerebral artery occlusion model (pMCAO). In two replicate 28-day pMCAO studies, weekly intravenous infusions of elezanumab, over a range of doses and TTIs of 6 and 24 h after stroke, significantly improved neuromotor function in both pMCAO studies when first administered 6 h after stroke. All elezanumab treatment groups, including the 24 h TTI group, had significantly less neuroinflammation as assessed by microglial and astrocyte activation. The novel mechanism of action and potential for expanding TTI in human AIS make elezanumab distinct from current acute reperfusion therapies, and support evaluation in clinical trials of acute CNS damage to determine optimal dose and TTI in humans.

HLA-DQA1*05 Associates With Anti-Tumor Necrosis Factor Immunogenicity and Low Adalimumab Trough Concentrations in Inflammatory Bowel Disease Patients From the SERENE Ulcerative Colitis and Crohn's Disease Studies

BACKGROUND AND AIMS

Anti-tumor necrosis factor (anti-TNF) therapies are commonly prescribed treatments for Crohn's disease (CD) and ulcerative colitis (UC). Many patients treated with anti-TNF therapy eventually develop anti-drug antibodies (ADAs). Understanding the factors associated with immunogenicity in anti-TNF-treated patients can help guide treatment. The Humira SERENE studies were Phase 3 trials investigating adalimumab induction regimens in CD and UC patients.

METHODS

We imputed alleles for 7 HLA genes in 1100 patients from the SERENE CD and SERENE UC trials. We then tested these alleles for association with time to immunogenicity. Subsequently, we tested loci significantly associated with immunogenicity for their association with patients who had consistently low drug serum concentrations.

RESULTS

This study replicated the association of HLA-DQA1*05 with time to immunogenicity (hazard ratio [HR] 1.42, p = 2.22E-06). Specifically, HLA-DQA1*05:05 was strongly associated (HR 1.76, p = 2.02E-10) and we detected a novel association represented by HLA-DRB1*01:02 (HR 3.16, p = 2.92E-07). Carriage of HLA-DQA1*05:05 and HLA-DRB1*01:02 was associated with patients who experienced consistently low adalimumab trough concentrations (HLA-DQA1*05:05: odds ratio [OR] 1.98, p = 0.0049; HLA DRB1*01:02: OR 7.06, p = 7.44E-05).

CONCLUSIONS

We found a significant association between alleles at genes in the human HLA locus and the formation of adalimumab immunogenicity and low adalimumab drug serum concentrations in large clinical studies of CD and UC patients. This work extends previous findings in CD to UC and directly shows a genetic association in patients with low drug concentrations. This work builds on existing literature to suggest that genetic screening could be a useful tool for clinicians concerned with patient anti-TNF immunogenicity.

CLINICAL TRIAL REGISTRATION NUMBERS

SERENE CD (NCT02065570), SERENE UC (NCT02065622).

Abstract TMP110: Elezanumab Decreases Neuronal Damage And Improves Functional Recovery In A Rabbit Model Of Permanent Middle Cerebral Artery Occlusion

Introduction: Current acute interventions for ischemic stroke aim to restore perfusion of affected tissue. There is an unmet need for therapies that protect neurons from ischemic damage and/or enhance natural repair processes to restore function. In humans, the neuronal growth and survival inhibitor RGMa (repulsive guidance molecule A) is upregulated following ischemic stroke. Elezanumab is a novel, humanized monoclonal antibody targeting RGMa. Preclinical evidence in traumatic and ischemic models of CNS damage suggest a protective and regenerative mechanisms for elezanumab following CNS damage.

Methods: Elezanumab was evaluated in a rabbit permanent middle cerebral artery occlusion (MCAO) model of acute ischemic stroke by injection of an autologous blood clot. In replicate experiments, elezanumab (1, 10 and 40 mg/kg) or IgG control was administered 6 hours post occlusion or 24 hours post occlusion (10 mg/kg). Animals were dosed weekly through 28 days. Functional ability was assessed using the Neuromotor Score, a composite of sensorimotor performance tasks. Ex vivo MRI, histology, and fluid biomarker analyses were performed.

Results: MCAO consistently reduced cerebral blood flow by ~60% and resulted in neuromotor dysfunction. All doses of elezanumab demonstrated statistically significantly improved neuromotor function and recovery rate versus controls when dosed 6 hours post occlusion. The 10 mg/kg group dosed 24 hours post occlusion did not show a statistically significant functional improvement versus controls. Infarct volumes, plasma neurofilament light chain levels, and histological evidence of microglial proliferation were all significantly reduced with elezanumab treatment versus controls, including in the delayed elezanumab treatment group.

Conclusions: Elezanumab treatment was associated with improved functional recovery and reduced markers of neuronal damage. Collectively, these data support a neuroprotective role for elezanumab in this translational model of acute ischemic stroke. Elezanumab is now being tested in a Phase 2a clinical trial for acute ischemic stroke.