Relationship between the changes in hepatokine levels and metabolic effects after laparoscopic sleeve gastrectomy in severely obese patients

PURPOSE

To clarify the relationships between the changes in hepatokines and weight loss, and between these changes and the metabolic effects, and the roles played by these changes, after laparoscopic sleeve gastrectomy (LSG).

METHODS

We recruited 25 Japanese patients with severe obesity, who underwent LSG. We measured two hepatokines: selenoprotein P (SeP) and leukocyte cell-derived chemotaxin 2 (LECT2), at the baseline, and then 6 months and 1 year after LSG. Finally, we compared the changes in the hepatokines with the parameters of type 2 diabetes (T2D) and non-alcoholic steatohepatitis (NASH).

RESULTS

Changes in LECT2 were correlated with the percentage of total weight loss (ρ = - 0.499, P = 0.024) and the decrease in total fat area (ρ = 0.559, P = 0.003). The changes in SeP were correlated with those in hemoglobin A1c (ρ = 0.526, P = 0.043) and the insulinogenic index (ρ = 0.638, P = 0.010) in T2D patients. In patients with NASH, the LECT2 levels were correlated with liver steatosis (ρ = 0.601).

CONCLUSIONS

SeP levels decrease in association with HbA1c reduction, whereas LECT2 levels are associated with reductions in fat mass and NASH scores after LSG. Hepatokines may be involved in the pathology of obesity and its complications.

Selenoprotein P deficiency is associated with higher risk of incident heart failure

INTRODUCTION

Selenium deficiency has been associated with mortality, cardiovascular disease and worsened prognosis in heart failure (HF). In a recent population-based study, high selenium levels were shown to be associated with reduced mortality and reduced incidence of HF, but only in non-smokers. Here, we aimed to examine if selenoprotein P (SELENOP), a main selenium carrier protein, is associated with incident HF.

MATERIALS AND METHODS

SELENOP concentrations were measured in plasma of 5060 randomly selected subjects from the population-based prospective cohort "Malmö Preventive Project" (n = 18240) using an ELISA approach. Exclusion of subjects with prevalent HF (n = 230) and subjects with missing data on co-variates included in the regression analysis (n = 27) resulted in complete data for 4803 subjects (29.1% women, mean age 69.6 ± 6.2 years, 19.7% smokers). Cox regression models adjusted for traditional risk factors were used to analyse SELENOP's association with incident HF. Further, subjects within the quintile with the lowest SELENOP concentrations were compared to subjects in the remaining quintiles.

RESULTS

Each 1 standard deviation increment in SELENOP levels was associated with lower risk of incident HF (n = 436) during a median follow-up period of 14.7 years (hazard ratio (HR) 0.90; CI95% 0.82-0.99; p = 0.043). Further analyses showed that subjects in the lowest SELENOP quintile were at the highest risk of incident HF when compared to quintiles 2-5 (HR 1.52; CI95% 1.21-1.89; p = 2.5 × 10-4).

CONCLUSION

Low selenoprotein P levels are associated with a higher risk of incident HF in a general population. Further studies are warranted.

Correlations of selenium and selenoprotein P with asymmetric dimethylarginine and lipid profile in patients with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is associated with an increased risk of cardiovascular diseases (CVD). Accumulating evidence has suggested that selenium (Se) is of importance for optimal function of the cardiovascular system. This study aimed to investigate the associations of selenium and selenoprotein P (SePP) with asymmetric dimethylarginine (ADMA) and lipid profile in women with PCOS.

METHODS

In this cross-sectional study, 125 females aged 18-45 years diagnosed with PCOS were recruited. An interviewer-administered questionnaire was applied to gather the relevant demographic characteristics, detailed clinical information, and lifestyle habits of participants. Fasting blood samples were obtained to measure biochemical parameters. Serum concentrations of total testosterone, sex hormone-binding globulin (SHBG), ADMA, and lipid profiles as well as anthropometric measurements were assessed across tertiles of serum Se and SePP concentrations.

RESULTS

There was a positive correlation between serum Se and SePP concentrations (r = 0.434, p < 0.001). Serum Se level was inversely correlated with ADMA (r = -0.21, p = 0.025) and TG (r = -0.17, p = 0.041) concentrations. There were also inverse correlations between SePP and ADMA (r = -0.34, p < 0.001), TG (r = -0.21, p = 0.019), and oxidized low density lipoprotein (ox-LDL) (r = -0.25, p = 0.007) levels. No significant relationship was found between serum Se and SePP concentrations with total cholesterol, low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), apolipoprotein-A1 (Apo-A1), apolipoprotein-B (Apo-B100), total testosterone, SHBG, and free androgen index as well as anthropometric parameters (All p > 0.05).

CONCLUSION

The present study found that Se and SePP levels were inversely correlated with ADMA and TG concentrations as well as ox-LDL levels.

Selenium Deficiency in COVID-19-A Possible Long-Lasting Toxic Relationship

In the last two years, there has been a surge in the number of publications on the trace element selenium (Se) and selenocysteine-containing selenoproteins in human health, largely due to the pandemic and the multiple roles that this micronutrient and Se-dependent selenoproteins play in various aspects of the disease [...].

Clinical Significance of Micronutrient Supplementation in Critically Ill COVID-19 Patients with Severe ARDS

The interplay between inflammation and oxidative stress is a vicious circle, potentially resulting in organ damage. Essential micronutrients such as selenium (Se) and zinc (Zn) support anti-oxidative defense systems and are commonly depleted in severe disease. This single-center retrospective study investigated micronutrient levels under Se and Zn supplementation in critically ill patients with COVID-19 induced acute respiratory distress syndrome (ARDS) and explored potential relationships with immunological and clinical parameters. According to intensive care unit (ICU) standard operating procedures, patients received 1.0 mg of intravenous Se daily on top of artificial nutrition, which contained various amounts of Se and Zn. Micronutrients, inflammatory cytokines, lymphocyte subsets and clinical data were extracted from the patient data management system on admission and after 10 to 14 days of treatment. Forty-six patients were screened for eligibility and 22 patients were included in the study. Twenty-one patients (95%) suffered from severe ARDS and 14 patients (64%) survived to ICU discharge. On admission, the majority of patients had low Se status biomarkers and Zn levels, along with elevated inflammatory parameters. Se supplementation significantly elevated Se (p = 0.027) and selenoprotein P levels (SELENOP; p = 0.016) to normal range. Accordingly, glutathione peroxidase 3 (GPx3) activity increased over time (p = 0.021). Se biomarkers, most notably SELENOP, were inversely correlated with CRP (r_s = −0.495), PCT (r_s = −0.413), IL-6 (r_s = −0.429), IL-1β (r_s = −0.440) and IL-10 (r_s = −0.461). Positive associations were found for CD8⁺ T cells (r_s = 0.636), NK cells (r_s = 0.772), total IgG (r_s = 0.493) and PaO₂/FiO₂ ratios (r_s = 0.504). In addition, survivors tended to have higher Se levels after 10 to 14 days compared to non-survivors (p = 0.075). Sufficient Se and Zn levels may potentially be of clinical significance for an adequate immune response in critically ill patients with severe COVID-19 ARDS.

Characterization and Quantification of Selenoprotein P: Challenges to Mass Spectrometry

Selenoprotein P (SELENOP) is an emerging marker of the nutritional status of selenium and of various diseases, however, its chemical characteristics still need to be investigated and methods for its accurate quantitation improved. SELENOP is unique among selenoproteins, as it contains multiple genetically encoded SeCys residues, whereas all the other characterized selenoproteins contain just one. SELENOP occurs in the form of multiple isoforms, truncated species and post-translationally modified variants which are relatively poorly characterized. The accurate quantification of SELENOP is contingent on the availability of specific primary standards and reference methods. Before recombinant SELENOP becomes available to be used as a primary standard, careful investigation of the characteristics of the SELENOP measured by electrospray MS and strict control of the recoveries at the various steps of the analytical procedures are strongly recommended. This review critically discusses the state-of-the-art of analytical approaches to the characterization and quantification of SELENOP. While immunoassays remain the standard for the determination of human and animal health status, because of their speed and simplicity, mass spectrometry techniques offer many attractive and complementary features that are highlighted and critically evaluated.

SeP is elevated in NAFLD and participates in NAFLD pathogenesis through AMPK/ACC pathway

Nonalcoholic fatty liver disease (NAFLD) is prevalent chronic liver diseases with unknown mechanism and no curative treatment. Hepatokines have demonstrated importance in NAFLD but, role of selenoprotein P (SeP) in NAFLD is unknown. A total of 79 patients with NAFLD and 79 healthy controls were included in this case-control study. SeP is elevated in patients with NAFLD. With elevating level of SeP, NAFLD prevalence, and detecting rate increases. As NAFLD aggravated, serum SeP increases. Correlation analysis demonstrates that SeP is positively associated with NAFLD risk factors including body mass index, alanine aminotransferase, aspartate aminotransferase, gamma-glutamyltransferase, and serum uric acid. Both NAFLD in vivo and in vitro models, SeP protein level is higher in liver. Small interfering RNA of SEPP1 inhibited TG accumulation by activating adenosine monophosphate activated protein kinase/acetyl-CoA carboxylase (AMPK/ACC), and overexpression of SEPP1 aggravated lipid accumulation and inhibited AMPK/ACC phosphorylation. SeP expression is activated in NAFLD and exacerbated NAFLD through AMPK/ACC, providing insight into new diagnostic, therapeutic target in NAFLD.

A spatial study on serum selenoprotein P and Keshan disease in Heilongjiang Province, China

BACKGROUND

Few spatial studies on serum selenoprotein P (SELENOP) and Keshan disease (KD) have been reported at the county-level in Heilongjiang province, China. This study aimed to provide visualized spatial epidemiological evidence of selenium molecular marker in residents living in endemic areas for the precise assessment of prevention, control, and elimination of KD.

METHODS

Using a spatial ecological study design, 587 subjects living in cities, townships, and rural areas of 50 KD endemic counties and 37 non-endemic counties in Heilongjiang province were investigated. The serum SELENOP levels of the participants were measured by enzyme-linked immunosorbent assay. Thematic maps were created, and spatial regression analysis was conducted using ordinary least squares.

RESULTS

The mean serum SELENOP level of the 587 subjects was 7.4 ± 3.0 μg/mL. The mean levels of serum SELENOP were higher in cities (7.4 ± 2.9 μg/mL) and townships (7.9 ± 3.2 μg/mL) than in rural areas (6.0 ± 3.0 μg/mL). The mean levels of serum SELENOP were trending towards high levels in non-endemic areas (7.4 ± 3.0 μg/mL) than in KD endemic areas (6.3 ± 3.3 μg/mL). Spatial regression analysis showed that the serum SELENOP level was positively correlated with the per capita gross domestic product.

CONCLUSION

Selenium deficiency may still exist in some KD endemic counties in Heilongjiang province, including Lingdong, Nenjiang, and Baiquan; these counties should be considered as key areas for precision prevention, control, and elimination of KD. Inclusion of selenium in the national surveillance of KD will provide more evidence for the assessment of KD elimination from a selenium nutrition perspective.

Toenail selenium, plasma selenoprotein P and risk of advanced prostate cancer: A nested case-control study

Low selenium status may be associated with increased risk of prostate cancer (PC), particularly aggressive PC, and variation in selenoprotein genes may constitute an important modifying factor. We aimed to investigate the association between two selenium status biomarkers [toenail selenium, plasma selenoprotein P (SELENOP)] and risk of advanced, high-grade and advanced-stage PC. We further studied whether variations in selenoprotein genes were associated with PC risk and selenium biomarker concentrations. In the "Diet, Cancer and Health" cohort, 27 178 men aged 50 to 65 years were enrolled from 1993 to 1997. Between baseline and 2012, 1160 cohort participants were diagnosed with advanced PC; among these 462 had high-grade and 281 had advanced-stage disease at diagnosis. Each case was risk set-matched to one control. Toenail selenium and plasma SELENOP concentrations were measured by neutron activation analysis and a SELENOP-ELISA, respectively, and genotyping was performed for 27 selected single nucleotide polymorphisms (SNPs) in 12 selenium pathway genes (including seven selenoproteins) by allele-specific PCR. Toenail selenium and circulating SELENOP concentrations were not associated with advanced, high-grade or advanced-stage PC. After adjustment for multiple testing, none of the genes were associated with PC risk. Neither toenail selenium nor plasma SELENOP was associated with advanced, high-grade or advanced-stage PC.

Effects of Bariatric Surgeries on Fetuin-A, Selenoprotein P, Angiopoietin-Like Protein 6, and Fibroblast Growth Factor 21 Concentration

Obesity is a civilization disease representing a global health problem. Excessive body weight significantly reduces the quality of life. It is also associated with the leading causes of death, including type 2 diabetes mellitus, cardiovascular diseases, and numerous types of cancer. The mainstay of therapy is a dietary treatment. However, in morbidly obese patients, dietary treatment is often insufficient. In these patients, the most effective procedure is bariatric surgery, but it is still difficult to predict its outcome and metabolic changes. Hepatokines are proteins secreted by hepatocytes. Many of them, including fetuin-A, selenoprotein P, angiopoietin-like protein 6, and fibroblast growth factor 21, have been linked to metabolic dysfunctions. In this context, hepatokines may prove helpful. This review investigates the possible changes in hepatokine profiles after selected bariatric surgery protocols. In this regard, Roux-en-Y gastric bypass is the most studied type of surgery. The overall analysis of published research identified fetuin-A as a potential marker of metabolic alternations in patients after bariatric surgery.

Interplay between Oxidative Stress and Metabolic Derangements in Non-Alcoholic Fatty Liver Disease: The Role of Selenoprotein P

Background: Pathogenetic mechanisms involved in the progression of non-alcoholic fatty liver disease (NAFLD) are complex and multifactorial. We investigated oxidative stress through the measurement of selenoprotein P (SeP) in serum and we explored its relation to metabolic derangements and liver damage in a group of non-diabetic NAFLD subjects. Methods: 57 NAFLD patients underwent a double-tracer oral glucose tolerance test (OGTT). Insulin resistance (IR) components were calculated at baseline as follows: hepatic-IR = (endogenous glucose production*insulin); peripheral-IR = (glucose rate of disappearance(Rd)); adipose-tissue(AT)-IR as Lipo-IR = (glycerol rate of appearance (Ra)*insulin) or AT-IR = (free fatty acids (FFAs)*insulin). The lipid and amino acid (AA) profiles were assessed by gas chromatography–mass spectrometry. SeP levels were measured by enzyme immunosorbent assay. Results: Circulating SeP correlated with insulin (r_S = 0.28), FFAs (r_S = 0.42), glucose Rd (r_S = −0.33) and glycerol Ra (r_S = −0.34); consistently, SeP levels correlated with Lipo-IR and AT-IR (r_S > 0.4). Among the AA and lipid profiles, SeP inversely correlated with serine (r_S = −0.31), glycine (r_S = −0.44) and branched chain AA (r_S = −0.32), and directly correlated with saturated (r_S = 0.41) and monounsaturated FFAs (r_S = 0.40). Hepatic steatosis and fibrosis increased in subjects with higher levels of SeP. In multivariable regression analysis, SeP was associated with the degree of hepatic fibrosis (t = 2.4, p = 0.022). Conclusions: SeP levels were associated with an altered metabolic profile and to the degree of hepatic fibrosis, suggesting a role in the pathogenesis of NAFLD.

Selenium and Copper as Biomarkers for Pulmonary Arterial Hypertension in Systemic Sclerosis

Circulating selenoprotein P (SELENOP) constitutes an established biomarker of Se status. SELENOP concentrations are reduced in inflammation and severe disease. Recently, elevated SELENOP levels have been suggested as diagnostic marker and therapeutic target in pulmonary arterial hypertension (PAH). We decided to re-evaluate this hypothesis. A group of healthy controls (n = 30) was compared with patients suffering from systemic sclerosis (SSc, n = 66), one third with SSc-related PAH. Serum was analysed for trace elements and protein biomarkers, namely SELENOP, glutathione peroxidase 3 (GPx3) and ceruloplasmin (CP). Compared to controls, patients with SSc-related PAH displayed reduced serum Se (91 ± 2 vs. 68 ± 2 µg/L) and SELENOP concentrations (3.7 ± 0.8 vs. 2.7 ± 0.9 mg/L), along with lower GPx3 activity (278 ± 40 vs. 231 ± 54 U/L). All three biomarkers of Se status were particularly low in patients with skin involvement. Serum Cu was not different between the groups, but patients with SSc-related PAH showed elevated ratios of Cu/Se and CP/SELENOP as compared to controls. Our data indicate that patients with SSc-related PAH are characterized by reduced Se status in combination with elevated CP, in line with other inflammatory diseases. Further analyses are needed to verify the diagnostic value of these TE-related biomarkers in PAH.

Selenoprotein P as Biomarker of Selenium Status in Clinical Trials with Therapeutic Dosages of Selenite

Selenoprotein P (SELENOP) is an established biomarker of selenium (Se) status. Serum SELENOP becomes saturated with increasing Se intake, reaching maximal concentrations of 5–7 mg SELENOP/L at intakes of ca. 100–150 µg Se/d. A biomarker for higher Se intake is missing. We hypothesized that SELENOP may also reflect Se status in clinical applications of therapeutic dosages of selenite. To this end, blood samples from two supplementation studies employing intravenous application of selenite at dosages >1 mg/d were analyzed. Total Se was quantified by spectroscopy, and SELENOP by a validated ELISA. The high dosage selenite infusions increased SELENOP in parallel to elevated Se concentrations relatively fast to final values partly exceeding 10 mg SELENOP/L. Age or sex were not related to the SELENOP increase. Western blot analyses of SELENOP verified the results obtained by ELISA, and indicated an unchanged pattern of immunoreactive protein isoforms. We conclude that the saturation of SELENOP concentrations observed in prior studies with moderate Se dosages (<400 µg/d) may reflect an intermediate plateau of expression, rather than an absolute upper limit. Circulating SELENOP seems to be a suitable biomarker for therapeutic applications of selenite exceeding the recommended upper intake levels. Whether SELENOP is also capable of reflecting other supplemental selenocompounds in high dosage therapeutic applications remains to be investigated.

Functional Biomarkers for the Selenium Status in a Human Nutritional Intervention Study

Soils in Germany are commonly low in selenium; consequently, a sufficient dietary supply is not always ensured. The extent of such provision adequacy is estimated by the optimal effect range of biomarkers, which often reflects the physiological requirement. Preceding epidemiological studies indicate that low selenium serum concentrations could be related to cardiovascular diseases. Inter alia, risk factors for cardiovascular diseases are physical inactivity, overweight, as well as disadvantageous eating habits. In order to assess whether these risk factors can be modulated, a cardio-protective diet comprising fixed menu plans combined with physical exercise was applied in the German MoKaRi (modulation of cardiovascular risk factors) intervention study. We analyzed serum samples of the MoKaRi cohort (51 participants) for total selenium, GPx activity, and selenoprotein P at different timepoints of the study (0, 10, 20, 40 weeks) to explore the suitability of these selenium-associated markers as indicators of selenium status. Overall, the time-dependent fluctuations in serum selenium concentration suggest a successful change in nutritional and lifestyle behavior. Compared to baseline, a pronounced increase in GPx activity and selenoprotein P was observed, while serum selenium decreased in participants with initially adequate serum selenium content. SELENOP concentration showed a moderate positive monotonic correlation (r = 0.467, p < 0.0001) to total Se concentration, while only a weak linear relationship was observed for GPx activity versus total Se concentration (r = 0.186, p = 0.021). Evidently, other factors apart from the available Se pool must have an impact on the GPx activity, leading to the conclusion that, without having identified these factors, GPx activity should not be used as a status marker for Se.

Copper and selenium status as biomarkers of neonatal infections

Neonatal infections are a major risk factor for neonatal mortality. A reliable diagnosis of early-onset sepsis (EOS) is hampered by the variable clinical presentations of the children. We hypothesized that changes in the Se or Cu status, or the biomarkers selenoprotein P (SELENOP) or ceruloplasmin (CP) alone or in combination may be informative of EOS. We generated a new human CP-specific non-competitive immunoassay (ELISA) suitable of analysing small sample volumes and validated the method with a commercial CP source. Using this novel CP assay, we analysed a case-control study of EOS (n = 19 control newborns, n = 18 suspected cases). Concentrations of Se, Cu, SELENOP, CP, interleukin-6 (IL-6), and C-reactive protein (CRP) along with the Cu/Se and CP/SELENOP ratios were evaluated by correlation analyses as biomarkers for EOS. Diagnostic value was estimated by receiver operating characteristic (ROC) curve analyses. The new CP-ELISA displayed a wide working range (0.10-6.78 mg CP/L) and low sample requirement (2 μL of serum, EDTA-, heparin- or citrate-plasma). Plasma CP correlated positively with Cu concentrations in the set of all samples (Pearson r = 0.8355, p < 0.0001). Three of the infected neonates displayed particularly high ratios of Cu/Se and CP/SELENOP, i.e., 3.8- to 6.9-fold higher than controls. Both the Cu/Se and the CP/SELENOP ratios correlated poorly with the early infection marker IL-6, but strongly and positively with the acute-phase protein CRP (Cu/Se-CRP: Spearman ϱ = 0.583, p = 0.011; CP/SELENOP-CRP: ϱ = 0.571, p = 0.013). The ROC curve analyses indicate that a combination of biomarkers for the Se and Cu status do not improve the early identification of EOS considerably. This study established a robust, highly precise, partly validated and scalable novel CP sandwich ELISA suitable for basic and clinical research, requiring minute amounts of sample. The ratio of circulating CP/SELENOP constitutes a promising new composite biomarker for detection of EOS, at least in a subset of severely diseased children.

Selenium and copper status - potential signposts for neurological remission after traumatic spinal cord injury

INTRODUCTION

Traumatic Spinal Cord Injury (TSCI) is a severe incident resulting in loss of motor and sensory function caused by complex pathological mechanisms including massive oxidative stress and extensive inflammatory processes. The essential trace elements selenium (Se) and copper (Cu) play crucial roles as part of the antioxidant defense.

HYPOTHESIS

Remission after TSCI is associated with characteristic dynamics of early changes in serum Cu and Se status.

STUDY DESIGN

Single-center prospective observational study.

PATIENTS AND METHODS

Serum samples from TSCI patients were analyzed (n = 52); 21 recovered and showed a positive abbreviated injury score (AIS) conversion within 3 months (G1), whereas 21 had no remission (G0). Ten subjects with vertebral fractures without neurological impairment served as control (C). Different time points (at admission, and after 4, 9, 12, and 24 h) were analyzed for total serum Se and Cu concentrations by total reflection X-ray fluorescence, and for Selenoprotein P (SELENOP) and Ceruloplasmin (CP) by sandwich ELISA.

RESULTS

At admission, CP and SELENOP concentrations were higher in the remission group (G1) than in the non-remission group (G0). Within 24 h, there were marginal changes in Se, SELENOP, Cu and CP concentrations in the groups of controls (C) and G0. In contrast, these parameters decreased significantly in G1. Binary logistic regression analysis including Cu and Se levels at admission in combination with Se and CP levels after 24 h allowed a prediction for potential remission, with an area under the curve (AUC) of 87.7% (CI: 75.1%-100.0%).

CONCLUSION

These data indicate a strong association between temporal changes of the Se and Cu status and the clinical outcome after TSCI. The dynamics observed may reflect an ongoing redistribution of the trace elements in favor of a better anti-inflammatory response and a more successful neurological regeneration.

Selenium Levels in Community Dwellers with Type 2 Diabetes Mellitus

Selenium (Se) is an essential micronutrient required by the human body and exerts biological functions through selenoproteins. The relationship between Se and diabetes remains ambiguous. This study aimed at, through measurements of serum selenoprotein P (SelP), glutathione peroxidase (GPx3), and Se content in serum and hair, evaluating Se levels in community dwellers with type 2 diabetes mellitus (T2DM). A total of 336 subjects, including 176 T2DM patients (65.5 ± 8.7 years old) and 160 healthy residents (63.7 ± 9.8 years old, as controls), were recruited in this cross-sectional community-based study performed in Suzhou. Samples of fasting venous blood and hair were collected for measurements of Se levels, glycometabolism, and biochemistry parameters. We found that the serum Se level and SelP concentration in T2DM patients were substantially higher than those in healthy residents (p < 0.05). There was no significant difference in GPx3 activity and hair Se level between the two groups of subjects (p > 0.05). Serum Se was positively correlated with both GPx3 and hair Se in T2DM patients (r = 0.167 and 0.164, respectively, p < 0.05) and negatively correlated with SelP in healthy controls (r = - 0.293, p < 0.05). In conclusion, this study showed significantly higher levels of serum Se and SelP in community dwellers with T2DM than in matched healthy residents.

Can hepatokines be regarded as novel non-invasive serum biomarkers of intrahepatic lipid content in obese children?

PURPOSE

Hepatokines are proteins produced by the liver and involved in regulating glucose and lipid metabolism. However, their role as the biomarkers of intrahepatic lipid content is not clear. The aim of the study was to evaluate the serum concentration of selected hepatokines: fibroblast growth factor-21 (FGF-21), selenoprotein P (SELENOP) and sex hormone-binding globulin (SHBG) in obese children.

PATIENTS AND METHODS

The cross-sectional study included 86 obese children with suspected liver disease. Nonalcoholic fatty liver disease (NAFLD) was diagnosed in children with liver steatosis in ultrasound with elevated alanine aminotransferase (ALT) serum activity and excluded other liver diseases. The total intrahepatic lipid content (TILC) was assessed by magnetic resonance proton spectroscopy (¹H-MRS).

RESULTS

The concentration of FGF-21 and SELENOP was significantly higher and SHBG significantly lower in children with NAFLD compared to controls. Only FGF-21 level was significantly higher in NAFLD children than in obese patients without NAFLD. The significant positive correlation of FGF-21 with ALT, gamma glutamyltransferase (GGT), triglycerides, homeostatic model assessment-insulin resistance (HOMA-IR), the degree of liver steatosis in ultrasound and TILC in ¹H-MRS were found. The ability of serum FGF-21 to diagnose severe liver steatosis was significant.

CONCLUSIONS

FGF-21 can be considered as a suitable biomarker in predicting TILC and fatty liver in obese children.

Selenoprotein-P Deficiency Predicts Cardiovascular Disease and Death

Selenoprotein-P (SELENOP) is the main carrier of selenium to target organs and reduces tissue oxidative stress both directly and by delivering selenium to protective selenoproteins. We tested if the plasma concentration of SELENOP predicts cardiovascular morbidity and mortality in the primary preventive setting. SELENOP was measured from the baseline exam in 2002–2006 of the Malmö Preventive Project, a population-based prospective cohort study, using a validated ELISA. Quintiles of SELENOP concentration were related to the risk of all-cause mortality, cardiovascular mortality, and a first cardiovascular event in 4366 subjects during a median (interquartile range) follow-up time of 9.3 (8.3–11) years using Cox proportional Hazards Model adjusting for cardiovascular risk factors. Compared to subjects in the lowest quintile of SELENOP, the risk of all three endpoints was significantly lower in quintiles 2–5. The risk (multivariate adjusted hazard ratio, 95% CI) decreased gradually with the lowest risk in quintile 4 for all-cause mortality (0.57, 0.48–0.69) (p < 0.001), cardiovascular mortality (0.52, 0.37–0.72) (p < 0.001), and first cardiovascular event (0.56, 0.44–0.71) (p < 0.001). The lower risk of a first cardiovascular event in quintiles 2–5 as compared to quintile 1 was significant for both coronary artery disease and stroke. We conclude that the 20% with lowest SELENOP concentrations in a North European population without history of cardiovascular disease have markedly increased risk of cardiovascular morbidity and mortality, and preventive selenium supplementation studies stratified for these subjects are warranted.

Metabolomics signature associated with circulating serum selenoprotein P levels

PURPOSE

Selenoprotein P (SELENOP) has been previously related to various metabolic traits with partially conflicting results. The identification of SELENOP-associated metabolites, using an untargeted metabolomics approach, may provide novel biological insights relevant to disentangle the role of SELENOP in human health.

METHODS

In this cross-sectional study, 572 serum metabolites were identified by comparing the obtained LC-MS/MS spectra with spectra stored in Metabolon's spectra library. Serum SELENOP levels were measured in 832 men and women using an ELISA kit.

RESULTS

Circulating SELENOP levels were associated with 24 out of 572 metabolites after accounting for the number of independent dimensions in the metabolomics data, including inverse associations with alanine, glutamate, leucine, isoleucine and valine, an unknown compound X-12063, urate and the peptides gamma-glutamyl-leucine, and N-acetylcarnosine. Positive associations were observed between SELENOP and several lipid compounds. Of the identified metabolites, each standard deviation increase in the branched-chain amino acids (isoleucine, leucine, valine), alanine and gamma-glutamyl-leucine was related to higher odds of having T2DM [OR (95% CI): 1.96 (1.41-2.73); 1.62 (1.15-2.28); 1.94 (1.45-2.60), 1.57 (1.17-2.11), and 1.52 (1.13-2.05), respectively].

CONCLUSIONS

Higher serum SELENOP levels were associated with an overall healthy metabolomics profile, which may provide further insights into potential mechanisms of SELENOP-associated metabolic disorders.

Calculation of an Adequate Intake (AI) Value and Safe Range of Selenium (Se) for Chinese Infants 0-3 Months Old Based on Se Concentration in the Milk of Lactating Chinese Women with Optimal Se Intake

The required selenium intake for optimal health in Chinese residents was published in 2014. However, the adequate intake (AI) value for Chinese infants 0-3 months old is not established. This study assessed the current selenium nutritional status of 264 lactating Chinese women from three geographical locations with different Se levels (Liangshan in Sichuan province, Enshi in Hubei province, and Xicheng District in Beijing), to screen mothers with optimal Se intake, and to modify the AI value of Se for Chinese infants 0-3 months old. Milk and plasma Se concentrations were determined by inductively coupled plasma mass spectrometry (ICP-MS) and glutathione peroxidase 3 (GPx3), and plasma selenoprotein P (SEPP1) was measured by ELISA. Daily Se intake (Y, μg/day) in lactating Chinese woman was calculated from plasma Se concentrations (X, μg/L) using the formula logY = 1.623 log(X) + 3.433. Plasma Se concentrations in lactating Chinese women were 78.19 ± 25.71, 112.48 ± 24.57, and 183.83 ± 45.81 μg/L from Se-deficient, Se-moderate, and seleniferous areas, respectively. Se intakes calculated from concentrations of plasma Se were 45.6 ± 21.69, 80.03 ± 27.69, and 223.10 ± 50.95 μg/day, respectively. An optimal dietary Se intake is not lower than the recommended nutrient intake (RNI) but not more than the tolerable upper intake level (UL). A range of 78-400 μg Se/day was defined as the optimal daily Se intake for lactating Chinese women. The percentages of mothers within this range in Sichuan, Beijing, and Enshi were 8.11, 45.13, and 6.06%, respectively. Based on milk Se concentrations of mothers with optimal daily Se intake, the adequate Se intake value and a safe range for Chinese infants 0-3 months of age were calculated as 15.29 and 8-35 μg Se/day, respectively. The Se status of Chinese lactating women has improved, particularly in traditionally Se-deficient and Se-toxic regions. A safe range for daily Se intake in Chinese infants may be regarded as a guideline for infant formula.

A spatial ecological study of selenoprotein P and Keshan disease

Few spatial ecological studies on selenoprotein P (SePP) and Keshan disease (KD) have been reported. The main objective of this study is to investigate the relationships of SePP with KD, economic indicators and soil selenium and to visualize the evidence for KD precise prevention and control. An ecological study design was employed. The serum SePP of 2351 subjects living in rural areas, general cities and developed cities in 15 KD endemic provinces and 13 KD non-endemic provinces in China were measured. Spatial description and spatial analysis of SePP were conducted. The subjects were adults aged. The mean serum SePP level of KD endemic area residents was 14.20 mg/L, significantly lower than that in non-endemic areas, 15.30 mg/L (t = - 3.19, P = 0.0010). Serum SePP levels were low among the people in the KD endemic provinces of Shandong, Inner Mongolia, Heilongjiang, etc. The mean serum SePP level of the 2351 people was 15.04 (95% CI: 14.76 and 15.31) mg/L. The mean serum SePP levels of residents in developed cities, general cities and rural areas were 16.54 mg/L, 14.98 mg/L and 14.44 mg/L, respectively, and were significantly different (F = 17.00, P < 0.0010). Spatial regression analysis showed that the spatial distribution of SePP was positively correlated with per capita consumption expenditure and soil selenium. Selenium deficiency may still exist among residents living in the KD endemic provinces. Shandong, Inner Mongolia, and Heilongjiang should be the target provinces, visualized by spatial analysis, for KD precise prevention and control.

Plasma selenoprotein P concentration and lung cancer risk: results from a case-control study nested within the Shanghai Men's Health Study

Selenoprotein P (SELENOP) is a major selenoenzyme in plasma and linked to antioxidant properties and possibly to lung cancer; however, supporting evidence is limited. We investigated the association between pre-diagnostic plasma SELENOP concentration and lung cancer risk in a case-control study of 403 cases and 403 individually matched controls nested within the Shanghai Men's Health Study. SELENOP concentration in pre-diagnostic plasma samples was measured by a sandwich enzyme-linked immunosorbent assay. Cases were diagnosed with lung cancer between 2003 and 2010. Multivariate conditional logistic regression was used to estimate odds ratios (OR) and the corresponding 95% confidence intervals (CI) for studying the association between plasma SELENOP concentration and lung cancer risk. Cases had slightly lower plasma SELENOP concentration than controls (4.3 ± 1.2 versus 4.4 ± 1.1 mg/l, P difference = 0.09). However, the multivariate analysis showed no association between plasma SELENOP concentration and lung cancer risk among all participants (OR = 1.08, 95% CI = 0.54-2.14 for quartile 4 versus quartile 1), or by smoking status or tumor aggressiveness. In contrast, although the number of cases was limited, plasma SELENOP concentration was positively associated with lung adenocarcinoma risk (OR = 5.38, 95% CI = 1.89-15.35 for tertile 3 versus tertile 1), but not with squamous cell lung carcinoma (OR = 1.69, 95% CI = 0.43-6.70). Our study of adult men living in selenium non-deficient areas in China provides little support for the inverse association between pre-diagnostic plasma SELENOP concentration and lung cancer risk. Our finding of a positive association with risk of lung adenocarcinoma needs to be interpreted with caution.

Selenoprotein P as the major transporter for mercury in serum from methylmercury-poisoned rats

Selenium (Se) has been found to promote weight gain, decrease hepatic damage, but redistribute mercury (Hg) in brains and livers in methylmercury (MeHg)-poisoned rats. The aims of the present work were to examine the effects of Se on the levels of Hg in serum and the role of serum selenoproteins in binding with Hg in MeHg-poisoned rats. The concentration of Se, Hg and MeHg were studied using ICP-MS and CVAFS. The Hg- and Se-binding selenoproteins were separated and quantified using affinity chromatography with post-column isotope dilution analysis using both enriched ⁷⁸Se and ¹⁹⁹Hg. It was found that Se treatment reduced Hg levels in serum in MeHg-poisoned rats. Among the three separated selenoproteins, the amounts of SelP-bound Hg and Se increased to 73% and 93.6%, from 64.4% and 89.3% of the total Hg and Se, respectively after Se treatment, suggesting that SelP acts as a major transporter for Hg and pool for Se in serum. Over 90% of the total Hg was MeHg in serum, and the molar ratios of MeHg to Se as 1:4 and 1:9 in the formed MeHg-Se-SelP complex in the control and the Se treatment group, respectively. The elevated Se level binding with SelP facilitated the Hg extraction from tissues and organs, as well as its redistribution in brains and livers through blood circulation in the MeHg-poisoned rats. Together, our findings provide direct evidence that serum SelP is the major Hg transporter in MeHg-poisoned rats.

Serum selenoprotein P, but not selenium, predicts future hyperglycemia in a general Japanese population

We aimed to test the hypothesis that selenoprotein P (SELENOP), a hepatokine involved in the development of both insulin resistance and impaired insulin production in mice, is related to future onset of hyperglycemia in humans. 76 healthy non-pregnant human subjects without diabetes underwent oral glucose tolerance test (OGTT) at baseline and 4-years follow-up. Nine subjects developed either impaired glucose tolerance or type 2 diabetes at follow-up. At baseline, SELENOP concentrations correlated negatively with insulinogenic index, but not with homeostasis model assessment-estimated insulin resistance (HOMA-IR). Multivariate analysis showed that baseline SELENOP predicted fasting plasma glucose at follow-up independently of the other parameters. The receiver operating characteristic (ROC) curve analysis showed that baseline concentrations of serum SELENOP, but not of selenium, were a reliable test to predict future onset of glucose intolerance. In conclusion, elevation of circulating SELENOP, but not of circulating selenium, was positively and independently associated with future onset of glucose intolerance in a general Japanese population.

Associations and interactions between variants in selenoprotein genes, selenoprotein levels and the development of abdominal aortic aneurysm, peripheral arterial disease, and heart failure

Background

Little is known on the role of selenoprotein genes in cardiovascular disease. This study examines the associations of the SEPP1, SELENOS, TXNRD1, TXNRD2, GPX4, and SOD2 polymorphisms and selenoprotein P (SeP) and thioredoxin concentrations with the development of abdominal aortic aneurysm (AAA) and aortoiliac occlusive disease (AOID), as well as their influence on cardiac phenotype.

Methods

564 patients with AAA, 400 patients with AIOD, and 543 controls were enrolled and characterized for coronary artery disease, myocardial infarction, and systolic heart failure (HF) occurrence. In AAA, the coexistence of peripheral arterial disease (PAD) was examined. Genotypes were determined using TaqMan-based assays. Selenoprotein concentration was assessed using the ELISA method.

Results

The SELENOS rs34713741T, SEPP1 rs3877899A, and GPX4 rs713041T alleles were related to a 30–60% increase in the AIOD/PAD risk in the recessive or dominant model (all associations at P < .05). The SEPP1 rs3877899A allele was a protective factor for the development of AAA without concomitant PAD (OR = 0.68 for the dominant model, P = .014), but not AAA with concomitant PAD. The cumulative two-locus effects of selenoprotein genes on the AAA/AIOD risk were observed, including the multiplicative interaction between the SELENOS rs34713741T and GPX4 rs713041T alleles (both in the recessive model) affecting the AIOD risk (OR = 5.27, P = .001) and its clinical phenotype. Coexistence of HF in aortic diseases was related to both the SEPP1 rs7579A allele (OR = 1.83 for carriers, P = .013) and increased SeP concentrations; SeP level ≥8.5 mg/mL caused a 3.5-fold increase in the risk of HF. In AAA, SeP levels were correlated with BMI (r = -0.575, P < .0001).

Conclusions

Our results provide evidence that selenoprotein polymorphisms constitute a risk factor for HF and peripheral atherosclerosis, but prevent the development of AAA. Excessive weight might result in reduced antioxidant reserve efficiency in AAA. Validation studies are required to establish whether SeP concentration may be a marker for HF.

Serum selenium and selenoprotein-P levels in autoimmune thyroid diseases patients in a select center: a transversal study

OBJECTIVE

Selenium (Se) supplementation has been used to help prevent the progression of Graves' ophthalmopathy (GO) and autoimmune thyroid diseases (AITD) patients. We investigated Se serum and selenoprotein P (SePP) levels in Graves' disease (GD) with and without GO, Hashimoto's thyroiditis (HT) patients and in 27 control individuals (C).

SUBJECTS AND METHODS

We studied 54 female and 19 male patients: 19 with GD without GO, 21 GD with GO, 14 with HT and 19 with HT+LT4. Se values were measured using graphite furnace atomic absorption spectrophotometry. Serum SePP levels were measured by ELISA.

RESULTS

Median Se levels were similar among all groups; GD patients: 54.2 (46.5-61.1 μg/L), GO: 53.6 (43.5-60.0 μg/L), HT: 51.9 (44.6-58.5 μg/L), HT+LT4 54.4 (44-63.4) and C group patients: 56.0 (52.4-61.5 μg/L); P = 0.48. However, serum SePP was lower in GO patients: 0.30 (0.15-1.05 μg/mL) and in HT patients: 0.35 (0.2-1.17 μg/mL) compared to C group patients: 1.00 (0.564.21 μg/mL) as well as to GD patients: 1.19 (0.62-2.5 μg/mL) and HT+LT4 patients: 0.7 (0,25-1.95); P = 0.002. Linear regression analysis showed a significant relationship between SePP and TPOAb values (r = 0.445, R2 = 0.293; P < 0.0001). Multiple regression analysis found no independent variables related to Se or SePP.

CONCLUSION

A serum Se concentration was lower than in some other countries, but not significantly among AITD patients. The low serum SePP levels in GO and HT patients seems to express inflammatory reactions with a subsequent increase in Se-dependent protein consumption remains unclear.

ARHGEF10 knockout inhibits platelet aggregation and protects mice from thrombus formation

Essentials ARHGEF10 single-nucleotide polymorphism provides risk of ischemic and atherothrombotic stroke. The role of ARHGEF10 in platelet function was examined using ARHGEF10 knockout mice. ARHGEF10 deficiency inhibits platelet function and arterial thrombus formation. ARHGEF10 knockout protects mice from stroke-induced infarction.

SUMMARY

Background ARHGEF10, a member of the Rho guanine nucleotide exchange factor (GEF) family, stimulates Rho GTPases. Rho GTPases have been reported to regulate a variety of cellular behaviors, such as cell polarity, cytoskeletal organization, and gene transcription. ARHGEF10 single-nucleotide polymorphisms are linked to the risk of ischemic stroke. However, the role of ARHGEF10 in platelet function remains unknown. Objective To examine the role of ARHGEF10 in platelet function. Methods ARHGEF10-/- were generated. We examined the in vitro and in vivo effects of ARHGEF10 knockout on platelet function and arterial thrombosis formation. Results ARHGEF10-/- mice had normal platelet counts, but showed altered aggregation in response to thrombin, collagen, ADP, protease-activated receptor-4 peptide, and U46619 stimulation. ARHGEF10 knockout influenced platelet spreading on fibrinogen-coated surfaces, and caused the platelets to show less lamellipodia-like extension than wild-type platelets. ARHGEF10 knockout also inhibited platelet clot retraction induced by thrombin stimulation. ARHGEF10 knockout resulted in prolonged tail bleeding time and inhibited the stable thrombus formation induced by FeCl3 in the carotid artery. Conclusions ARHGEF10 serves as an important regulator in platelet shape change, spreading, and aggregation. Moreover, ARHGEF10 also plays an important role in arterial thrombosis formation.

Response of Selenium and Selenogenome in Immune Tissues to LPS-Induced Inflammatory Reactions in Pigs

Circulating concentration of the essential trace element selenium (Se) was significantly lower in inflammatory disorders. Although Se plays physiological roles mainly through the function of 25 selenoproteins, the response of the selenogenome in immune tissues during inflammatory reactions remains unclear. The objective of this study was to determine the Se retention and selenogenome expression in immune tissues during the lipopolysaccharide (LPS)-induced inflammatory response in porcine. A total of 12 male pigs were randomly divided into two groups and injected with LPS or saline. After 4 h postinjection, blood samples were collected and pigs were euthanized. Pigs challenged with LPS had 36.8 and 16.6 % lower (P < 0.05) Se concentrations in the serum and spleen, respectively, than those injected with saline. Moreover, the activities of GPX decreased (P < 0.05) by 23.4, 26.6, and 30.4 % in the serum, thymus, and lymph node, respectively, in the pigs injected with LPS. Furthermore, the LPS challenge altered (P < 0.05) the mRNA expression of 14, 16, 10, and 6 selenoprotein genes in the liver, spleen, thymus, and lymph node, respectively. Along with 10 previously reported selenoprotein genes, the response of Txnrd2, Txnrd3, Sep15, Selh, Seli, Seln, Selo, Selt, Selx, and Sephs2 to inflammatory reaction in immune tissues were newly illustrated in this study. In conclusion, the LPS-induced inflammatory response impaired Se metabolism and was associated with dysregulation of the selenogenome expression in immune tissues.

Sex-specific and inter-individual differences in biomarkers of selenium status identified by a calibrated ELISA for selenoprotein P

Selenoprotein P (SELENOP) is a liver-derived transporter of selenium (Se) in blood, and a meaningful biomarker of Se status. Se is an essential trace element for the biosynthesis of enzymatically-active selenoproteins, protecting the organism from oxidative damage. The usage of uncalibrated assays hinders the comparability of SELENOP concentrations and their pathophysiological interpretation across different clinical studies. On this account, we established a new sandwich SELENOP-ELISA and calibrated against a standard reference material (SRM1950). The ELISA displays a wide working range (11.6-538.4µg/L), high accuracy (2.9%) and good precision (9.3%). To verify whether SELENOP correlates to total Se and to SELENOP-bound Se, serum samples from healthy subjects and age-selected participants from the Berlin Aging Study II were analyzed by SELENOP-ELISA and Se quantification. SELENOP was affinity-purified and its Se content was determined from a subset of samples. There was a high correlation of total Se and SELENOP concentrations in young and elderly men, and in elderly women, but not in young women, indicating a specific sexual dimorphism in these biomarkers of Se status in young subjects. The Se content of isolated SELENOP was independent of sex and age (mean±SD: 5.4±0.5). By using this calibrated SELENOP-ELISA, prior reports on pathological SELENOP concentrations in diabetes and obesity are challenged as the reported values are outside reasonable limits. Biomarkers of Se status in clinical research need to be measured by validated assays in order to avoid erroneous data and incorrect interpretations, especially when analyzing young women. The Se content of circulating SELENOP differs between individuals and may provide some important diagnostic information on Se metabolism and status.

Alterations in serum levels of fetuin A and selenoprotein P in chronic hepatitis C patients with concomitant type 2 diabetes: A case-control study

BACKGROUND

Insulin resistance (IR) and type 2 diabetes mellitus (T2DM) are serious extrahepatic manifestations of chronic hepatitis C virus (HCV) infection. However, the mechanism underlying the IR in chronic HCV is obscure. Hepatokines are group of liver-derived protein, which affect the glucose and lipid metabolism in several tissues. Fetuin A (also known as human α2-HS-glycoprotein) is one of the hepatokines, which was recognized as a natural inhibitor of the insulin receptor tyrosine kinase in liver and skeletal muscle. Additionally, selenoprotein P has emerged as an important hepatokine, which primarily acts as selenium transporter and has been reported to be implicated in glucose homeostasis in human.

OBJECTIVE

The aim of the current case-control study was to investigate the serum levels of both fetuin A and selenoprotein P in chronic hepatitis C patients with or without T2DM and to correlate their levels with other biochemical parameters of insulin resistance.

MAIN FINDINGS

Our results showed that, serum fetuin A levels increased significantly in HCV patients compared with controls (P<0.01) and surplus increase was found in HCV with concomitant T2DM (P>0.001). However, selenoprotein P levels significantly elevated only in patients with both HCV and T2DM (P<0.05) compared with the healthy subjects. Both fetuin A and selenoprotein P were positively correlated with fasting blood glucose. Yet, only fetuin A was significantly correlated to the HOMA-IR (r=0.28; P=0.03).

CONCLUSIONS

These results indicate crucial roles played by fetuin A and selenoprotein P in the IR caused by HCV and that both hepatokines may be targets for the development of therapies to treat or inhibit insulin resistance associated to HCV. However, further studies on large scale should be conducted to confirm our findings.

Prediagnostic selenium status and hepatobiliary cancer risk in the European Prospective Investigation into Cancer and Nutrition cohort

BACKGROUND

Selenium status is suboptimal in many Europeans and may be a risk factor for the development of various cancers, including those of the liver and biliary tract.

OBJECTIVE

We wished to examine whether selenium status in advance of cancer onset is associated with hepatobiliary cancers in the EPIC (European Prospective Investigation into Cancer and Nutrition) study.

DESIGN

We assessed prediagnostic selenium status by measuring serum concentrations of selenium and selenoprotein P (SePP; the major circulating selenium transfer protein) and examined the association with hepatocellular carcinoma (HCC; n = 121), gallbladder and biliary tract cancers (GBTCs; n = 100), and intrahepatic bile duct cancer (IHBC; n = 40) risk in a nested case-control design within the EPIC study. Selenium was measured by total reflection X-ray fluorescence, and SePP was determined by a colorimetric sandwich ELISA. Multivariable ORs and 95% CIs were calculated by using conditional logistic regression.

RESULTS

HCC and GBTC cases, but not IHBC cases, showed significantly lower circulating selenium and SePP concentrations than their matched controls. Higher circulating selenium was associated with a significantly lower HCC risk (OR per 20-μg/L increase: 0.41; 95% CI: 0.23, 0.72) but not with the risk of GBTC or IHBC. Similarly, higher SePP concentrations were associated with lowered HCC risk only in both the categorical and continuous analyses (HCC: P-trend ≤ 0.0001; OR per 1.5-mg/L increase: 0.37; 95% CI: 0.21, 0.63).

CONCLUSION

These findings from a large prospective cohort provide evidence that suboptimal selenium status in Europeans may be associated with an appreciably increased risk of HCC development.

Selenium and its relationship with selenoprotein P and glutathione peroxidase in children and adolescents with Hashimoto's thyroiditis and hypothyroidism

The essential trace element selenium (Se) is required for thyroid hormone synthesis and metabolism. Selenoproteins contain selenocysteine and are responsible for biological functions of selenium. Glutathione peroxidase (GPx) is one of the major selenoproteins which protects the thyroid cells from oxidative damage. Selenoprotein P (SePP) is considered as the plasma selenium transporter to tissues. The aim of this study was to evaluate serum Se and SePP levels, and GPx activity in erythrocytes of children and adolescents with treated Hashimoto's thyroiditis, hypothyroidism, and normal subjects. Blood samples were collected from 32 patients with Hashimoto's thyroiditis, 20 with hypothyroidism, and 25 matched normal subjects. All the patients were under treatment with levothyroxine and at the time of analysis all of the thyroid function tests were normal. GPx enzyme activity was measured by spectrophotometry at 340 nm. Serum selenium levels were measured by high-resolution continuum source graphite furnace atomic absorption. SePP, TPOAb (anti-thyroid peroxidase antibody), and TgAb (anti-thyroglobulin antibody) were determined by ELISA kits. T4, T3, T3 uptake and TSH were also measured. Neither GPx activity nor SePP levels were significantly different in patients with Hashimoto's thyroiditis or hypothyroidism compared to normal subjects. Although GPx and SePP were both lower in patients with hypothyroidism compared to those with Hashimoto's thyroiditis and normal subjects but the difference was not significant. Serum Se levels also did not differ significantly in patients and normal subjects. We did not find any correlation between GPx or SePP with TPOAb or TgAb but SePP was significantly correlated with Se. Results show that in patients with Hashimoto's thyroiditis or hypothyroidism who have been under treatment with levothyroxine and have normal thyroid function tests, the GPx, SePP and Se levels are not significantly different.

Chronic Kidney Disease Distinctly Affects Relationship Between Selenoprotein P Status and Serum Thyroid Hormone Parameters

INTRODUCTION

Chronic kidney disease (CKD) impairs thyroid hormone (TH) metabolism and is associated with low serum triiodothyronine (T3) concentrations in patients with a low glomerular filtration rate (GFR). Whether this results from decreased T3 formation from thyroxine (T4) by impaired 5'-deiodinase (DIO) activity and/or enhanced degradation of T3 and increased reverse triiodothyronine (rT3) formation from T4 by elevated 5-DIO activity remains unclear. Both activating 5'- and the inactivating 5-deiodination of TH are catalyzed by three selenium (Se)-dependent DIO isoenzymes. Selenoprotein P (SePP) is the major constituent of serum selenium, and functions as Se transport protein from liver to kidney and several other organs. This study tested the hypothesis that serum SePP and TH status are associated with the degree of renal impairment in patients with CKD.

PATIENTS AND METHODS

A total of 180 CKD patients (stages 1-5) and 70 chronic hemodialysis (CHD) patients undergoing hemodialysis three times per week for at least two years were prospectively investigated for clinical data, parameters of renal function, serum TH profile (thyrotropin, T4, free thyroxine [fT4], T3, free triiodothyronine (fT3), rT3, thyroxine-binding globulin [TBG]), C-reactive protein (CRP), and serum SePP.

RESULTS

In CKD patients, renal function was negatively associated with SePP concentration (standardized β = -0.17, p = 0.029); that is, SePP concentrations increased in more advanced CKD stages. In contrast, significantly lower SePP concentrations were found in patients on hemodialysis compared with CKD patients (M ± SD = 2.7 ± 0.8 mg/L vs. 3.3 ± .9 mg/L; p < 0.001). Notably, in CKD patients, the SePP concentration was negatively associated with T4 (standardized β = -0.16, p = 0.039) and fT4 (standardized β = -0.16, p = 0.039) concentrations, but no association was found with T3, fT3, rT3, T3/T4, rT3/T3, rT3/T4, or TBG concentrations. The SePP concentration was also negatively associated with CRP levels (standardized β = -0.17, p = 0.029). In the CHD group, no association was detected between SePP and the investigated TH parameters.

SUMMARY AND CONCLUSION

Impaired renal function is positively correlated with serum concentrations of SePP. In patients undergoing CHD treatment, SePP concentrations were significantly reduced, but the TH profile remained unaffected. These findings indicate an important contribution of kidney function on serum SePP homeostasis, and consequently on Se status.

Selenium status is associated with colorectal cancer risk in the European prospective investigation of cancer and nutrition cohort

Suboptimal intakes of the micronutrient selenium (Se) are found in many parts of Europe. Low Se status may contribute to colorectal cancer (CRC) development. We assessed Se status by measuring serum levels of Se and Selenoprotein P (SePP) and examined the association with CRC risk in a nested case-control design (966 CRC cases; 966 matched controls) within the European Prospective Investigation into Cancer and Nutrition. Se was measured by total reflection X-ray fluorescence and SePP by immunoluminometric sandwich assay. Multivariable incidence rate ratios (IRRs) and 95% confidence intervals (CIs) were calculated using conditional logistic regression. Respective mean Se and SePP levels were 84.0 μg/L and 4.3 mg/L in cases and 85.6 μg/L and 4.4 mg/L in controls. Higher Se concentrations were associated with a non-significant lower CRC risk (IRR = 0.92, 95% CI: 0.82-1.03 per 25 μg/L increase). However, sub-group analyses by sex showed a statistically significant association for women (p(trend) = 0.032; per 25 μg/L Se increase, IRR = 0.83, 95% CI: 0.70-0.97) but not for men. Higher SePP concentrations were inversely associated with CRC risk (p(trend) = 0.009; per 0.806 mg/L increase, IRR = 0.89, 95% CI: 0.82-0.98) with the association more apparent in women (p(trend) = 0.004; IRR = 0.82, 95% CI: 0.72-0.94 per 0.806 mg/L increase) than men (p(trend) = 0.485; IRR = 0.98, 95% CI: 0.86-1.12 per 0.806 mg/L increase). The findings indicate that Se status is suboptimal in many Europeans and suggest an inverse association between CRC risk and higher serum Se status, which is more evident in women.

Selenium status in U.K. pregnant women and its relationship with hypertensive conditions of pregnancy

Dietary intake/status of the trace mineral Se may affect the risk of developing hypertensive conditions of pregnancy, i.e. pre-eclampsia and pregnancy-induced hypertension (PE/PIH). In the present study, we evaluated Se status in U.K. pregnant women to establish whether pre-pregnant Se status or Se supplementation affected the risk of developing PE/PIH. The samples originated from the SPRINT (Selenium in PRegnancy INTervention) study that randomised 230 U.K. primiparous women to treatment with Se (60 μg/d) or placebo from 12 weeks of gestation. Whole-blood Se concentration was measured at 12 and 35 weeks, toenail Se concentration at 16 weeks, plasma selenoprotein P (SEPP1) concentration at 35 weeks and plasma glutathione peroxidase (GPx3) activity at 12, 20 and 35 weeks. Demographic data were collected at baseline. Participants completed a FFQ. U.K. pregnant women had whole-blood Se concentration lower than the mid-range of other populations, toenail Se concentration considerably lower than U.S. women, GPx3 activity considerably lower than U.S. and Australian pregnant women, and low baseline SEPP1 concentration (median 3.00, range 0.90-5.80 mg/l). Maternal age, education and social class were positively associated with Se status. After adjustment, whole-blood Se concentration was higher in women consuming Brazil nuts (P= 0.040) and in those consuming more than two seafood portions per week (P= 0.054). A stepwise logistic regression model revealed that among the Se-related risk factors, only toenail Se (OR 0.38, 95% CI 0.17, 0.87, P= 0.021) significantly affected the OR for PE/PIH. On excluding non-compliers with Se treatment, Se supplementation also significantly reduced the OR for PE/PIH (OR 0.30, 95% CI 0.09, 1.00, P= 0.049). In conclusion, U.K. women have low Se status that increases their risk of developing PE/PIH. Therefore, U.K. women of childbearing age need to improve their Se status.

Selenoprotein P is not elevated in gestational diabetes mellitus

Selenoprotein P concentrations have been found to be associated with insulin resistance and elevated in patients with type 2 diabetes mellitus (DM). The aim of the present study was to investigate circulating selenoprotein P level and its possible relationship with metabolic parameters in gestational diabetes mellitus (GDM). Plasma selenoprotein P concentrations were measured in 30 pregnant women with GDM, 35 pregnant women without GDM and 22 healthy nonpregnant women. No difference in selenoprotein P levels was observed among the groups [6.2 (4.5-8.2), 7.9 (4.5-10.7) and 6.7 (5.3-9.1) ng/ml, respectively, p = 0.69]. In pregnant women with and without GDM, selenoprotein P did not correlate with age, gestational age, prepregnancy body mass index (BMI), HbA1c, glucose concentrations at oral glucose tolerance test (OGTT), area under curve (AUC) glucose, total cholesterol, LDL cholesterol and triglycerides levels (p > 0.05). But, there were statistically significant correlations between selenoprotein P and current BMI (r = -0.28, p = 0.04) and HDL cholesterol levels (r = 0.43, p = 0.01). We found that selenoprotein P concentrations are not elevated in women with GDM but associated with BMI and HDL cholesterol.

Consumption of selenium-enriched broccoli increases cytokine production in human peripheral blood mononuclear cells stimulated ex vivo, a preliminary human intervention study

SCOPE

Selenium (Se) is a micronutrient essential for human health, including immune function. Previous research indicates that Se supplementation may cause a shift from T helper (Th)1- to Th2-type immune responses. We aim to test the potential health promoting effects of Se-enriched broccoli.

METHODS AND RESULTS

In a human trial, 18 participants consumed control broccoli daily for 3 days. After a 3-day wash-out period, the participants were provided with Se-enriched broccoli containing 200 μg of Se per serving for 3 days. Plasma and peripheral blood mononuclear cell (PBMC) samples were collected at the start and end of each broccoli feeding period for analysis of total Se and measurement of cytokine production from PBMC stimulated with antigens ex vivo. Plasma Se content remained consistent throughout the control broccoli feeding period and the baseline of the Se-enriched broccoli period (1.22 μmol/L) and then significantly increased following 3 days of Se-enriched broccoli feeding. Interleukin (IL-2, IL-4, IL-5, IL-13, and IL-22) production from PBMC significantly increased after 3 days of Se-enriched broccoli feeding compared with baseline.

CONCLUSION

This study indicates that consumption of Se-enriched broccoli may increase immune responses toward a range of immune challenges.

Epidemiology of selenium and type 2 diabetes: can we make sense of it?

The potential of some selenoproteins to protect against oxidative stress led to the expectation that selenium would be protective against type 2 diabetes, and indeed in early in vivo and in vitro studies, selenium (as selenate) was shown to have antidiabetic and insulin-mimetic effects. However, more recently, findings from observational cross-sectional studies have raised concern that high selenium exposure may be associated with type 2 diabetes or insulin resistance, at least in well-nourished populations, though trial results have been inconsistent. Moreover, the largest trials that investigated the effects of selenium supplementation on diabetes endpoints have had cancer prevention as their primary outcome, casting doubt on the interpretation of posthoc analyses. Factors affecting serum/plasma selenium are not just location and level of disease-associated inflammation but the fact that higher concentrations of plasma selenoprotein P yet lower concentrations of glutathione peroxidase are found in type 2 diabetic patients than in normal subjects. From a public health perspective, selenium is marketed as a dietary supplement and is commonly added to multivitamin/mineral preparations that are consumed in many Western countries. Based on current evidence, however, the indiscriminate use of selenium supplements in individuals and populations with adequate-to-high selenium status cannot be justified and may increase risk. In conclusion, although there is a clear link between certain selenoproteins and glucose metabolism or insulin resistance, the relationship between selenium and type 2 diabetes is undoubtedly complex. It is possible that the relationship is U-shaped, with possible harm occurring both below and above the physiological range for optimal activity of some or all selenoproteins.

Serum selenium and selenoprotein P in patients with silicosis

OBJECTIVES

Selenoprotein P (SeP) is a selenium (Se) supply protein, which is an antioxidant micronutrient considered to be vital for human health. The aim of this study was to assess the serum selenium status in patients with silicosis.

METHODS

We conducted a retrospective case-control study where serum samples from a total of 78 patients (males with a median age of 73.5 years old) with silicosis and 20 healthy controls (males with a median age of 72.5 years old) were assayed for Se and SeP. They underwent medical and job history taking, lung function testing, and chest radiography examinations. Levels of serum Se were measured using electrothermal atomic absorption spectrophotomerty, while levels of SeP were assessed with sandwich Enzyme Immunoassay. Spearman's rank correlation test was carried out to evaluate the relationship between Se and SeP. The Mann-Whitney test was used to evaluate differences in serum Se and SeP between study groups.

RESULTS

The median serum Se and SeP concentrations were significantly lower in cases (74.0 μg/l and 4.2mg/l, respectively) compared with controls (116.0 μg/l and 5.8 mg/l, respectively). In both cases and controls, serum Se was positively correlated with serum SeP (rho=0.781, p<0.001 and rho=0.768, p<0.001, respectively). Serum Se and SeP levels were significantly lower in patients classified in category four compared with those who were classified in category two or three.

CONCLUSIONS

Serum Se and SeP concentrations were found to be at inadequate levels in patients with silicosis, and decreased significantly with the severity of the disease.

Selenoprotein P and Yunnan endemic sudden cardiac death--an ecological study

The aim of the present study was to explore the role of selenoprotein P (SePP) in the etiology of the endemic sudden cardiac death in Yunnan, China. The levels of SePP of 124 subjects and glutathione peroxidase (GPx) of 119 subjects were measured. The subjects were from the old and new endemic areas and non-endemic areas. The levels of SePP and GPx of the subjects of the old endemic area were significantly higher than those of the subjects of the new endemic area and the non-endemic areas, respectively. The Pearson's correlation among SePP, GPx, and the number of the incident cases of the disease were statistically significant. These correlations show that there is an inverse relationship among the number of patients and the levels of SePP (r  =  - 0.9800, P  =  0.0200) and GPx (r  =  - 0.961, P  =  0.009). The results show that selenium deficiency might play an important role in the incidence of the disease.

Bone turnover and bone mineral density are independently related to selenium status in healthy euthyroid postmenopausal women

CONTEXT

Selenium status may have direct effects on bone and indirect effects through changes in thyroid hormone sensitivity.

OBJECTIVE

We hypothesized that variation in selenium status in healthy euthyroid postmenopausal women is associated with differences in bone turnover, bone mineral density (BMD) and fracture susceptibility.

DESIGN

The Osteoporosis and Ultrasound Study (OPUS) is a 6-yr prospective study of fracture-related factors.

SETTING

The study was comprised of a population-based cohort from five European cities.

PARTICIPANTS

A total of 2374 postmenopausal women participated. Subjects with thyroid disease and nonthyroidal illness and those receiving drugs affecting thyroid status or bone metabolism were excluded, leaving a study population of 1144.

INTERVENTIONS

There were no interventions.

MAIN OUTCOME MEASURES

We measured selenium (micrograms per liter); selenoprotein P (milligrams per liter); free T(4) (picomoles per liter); free T(3) (picomoles per liter); TSH (milliunits per liter); bone turnover markers; BMD; and vertebral, hip, and nonvertebral fractures.

RESULTS

Higher selenium levels were associated with higher hip BMD at study entry (β = 0.072, P = 0.004) and lower levels of bone formation (osteocalcin: β = -0.101, P < 0.001; procollagen type 1 N-terminal propeptide: β = -0.074, P = 0.013) and resorption markers (C-telopeptide of type 1 collagen: β = -0.058, P = 0.050; N-telopeptide of type 1 collagen: β = -0.095, P = 0.002). Higher selenoprotein P was associated with higher hip (β = 0.113, P < 0.001) and lumbar spine BMD (β = 0.088, P = 0.003) at study entry, higher hip BMD after the 6-yr follow-up (β = 0.106, P = 0.001) and lower osteocalcin (β = -0.077, P = 0.009), C-telopeptide of type 1 collagen (β = -0.075, P = 0.012), and N-telopeptide of type 1 collagen (β = -0.110, P < 0.001).

CONCLUSION

Selenium status is inversely related to bone turnover and positively correlated with BMD in healthy euthyroid postmenopausal women independent of thyroid status.

A randomized trial of selenium supplementation and risk of type-2 diabetes, as assessed by plasma adiponectin

Background

Evidence that selenium affects the risk of type-2 diabetes is conflicting, with observational studies and a few randomized trials showing both lower and higher risk linked to the level of selenium intake and status. We investigated the effect of selenium supplementation on the risk of type-2 diabetes in a population of relatively low selenium status as part of the UK PRECISE (PREvention of Cancer by Intervention with SElenium) pilot study. Plasma adiponectin concentration, a recognised independent predictor of type-2 diabetes risk and known to be correlated with circulating selenoprotein P, was the biomarker chosen.

Methods

In a randomized, double-blind, placebo-controlled trial, five hundred and one elderly volunteers were randomly assigned to a six-month intervention with 100, 200 or 300 µg selenium/d as high-selenium or placebo yeast. Adiponectin concentration was measured by ELISA at baseline and after six months of treatment in 473 participants with one or both plasma samples available.

Results

Mean (SD) plasma selenium concentration was 88.5 ng/g (19.1) at baseline and increased significantly in the selenium-treatment groups. In baseline cross-sectional analyses, the fully adjusted geometric mean of plasma adiponectin was 14% lower (95% CI, 0–27%) in the highest than in the lowest quartile of plasma selenium (P for linear trend = 0.04). In analyses across randomized groups, however, selenium supplementation had no effect on adiponectin levels after six months of treatment (P = 0.96).

Conclusions

These findings are reassuring as they did not show a diabetogenic effect of a six-month supplementation with selenium in this sample of elderly individuals of relatively low selenium status.

Trial Registration

Controlled-Trials.com ISRCTN25193534

Impact of intensive physical activity on selenium status

Various biomarkers were used to assess selenium (Se) status during 3 months of basic military training in a group of recruits. Samples of whole blood and plasma or serum were taken from a group of conscripts three times: at the beginning (n = 15), in the middle immediately after a severely stressful physical activity (n = 15) and at the end of military training (n = 13). Selenium was determined in diet samples, blood, plasma and plasma protein fractions as selenoprotein P (SelP) and glutathione peroxidase (eGPx). Selenium was determined by hydride generation-atomic fluorescence spectrometry and fractionation of proteins performed by affinity chromatography. Total serum glutathione, erythrocyte and serum GPx activity were followed as well. The average Se intake was calculated according to meal consumption questionnaires and Se determined in composite diet samples, giving an assessed intake of 48 ± 10 μg/day. At all three samplings, the average blood Se concentration was within the framework of adequate supply (87 ± 12, 94 ± 15 and 80 ± 13 ng/g). Plasma Se was between 70 and 80 ng/g (71 ± 10, 79 ± 9 and 76 ± 10 ng/g), which is believed to enable the full expression of plasma GPx. The average shares of plasma Se proteins were 61 ± 6%, 58 ± 6% and 54 ± 9% for SelP and 27 ± 4%, 34 ± 7% and 29 ± 5% for GPx. Although the observed tendency of the increases of serum and erythrocyte GPx activities at the second and third samplings with respect to the first was statistically insignificant, it is still indicative of some protection against oxidative stress, while the decreasing SelP levels during training suggest a slowly decreasing biologically active selenium pool.

Serum selenoprotein P levels in patients with type 2 diabetes and prediabetes: implications for insulin resistance, inflammation, and atherosclerosis

CONTEXT AND OBJECTIVE

The dysregulation of hepatokines may be associated with the pathogenesis of insulin resistance and type 2 diabetes. A recent study has suggested that selenoprotein P (SeP), a novel hepatokine, may play a role in the regulation of glucose metabolism and insulin sensitivity. We examined the relationship between circulating SeP levels and clinical parameters associated with insulin resistance in humans.

PARTICIPANTS AND METHODS

We compared serum SeP concentrations in 100 subjects with diverse glucose tolerance statuses. Furthermore, we evaluated the relationship between SeP and cardiometabolic risk factors including insulin resistance, high-sensitivity C-reactive protein, and carotid intima-media thickness.

RESULTS

Serum SeP concentrations were significantly higher in patients with type 2 diabetes or prediabetes than those with normal glucose tolerance (all P < 0.01) and decreased in a stepwise manner [1032.4 (495.9-2149.4) vs. 867.3 (516.3-1582.7) vs. 362.0 (252.5-694.5), P = 0.004]. In addition, overweight and obese subjects had significantly increased SeP levels compared with lean subjects (P = 0.002). Spearman's partial correlation analysis adjusted for age and gender showed a significant relationship between SeP and cardiometabolic factors including body mass index, waist circumference, systolic blood pressure, triglycerides, glucose, hemoglobin A1c, aspartate aminotransferase, and insulin resistance. Furthermore, in multiple regression analyses, SeP showed an independent association with carotid intima-media thickness as well as high-sensitivity C-reactive protein, even after adjustment for other confounding factors.

CONCLUSIONS

Circulating SeP concentrations were elevated in patients with glucose metabolism dysregulation and were related to various cardiometabolic parameters including insulin resistance, inflammation, and atherosclerosis.

Selenoprotein-related disease in a young girl caused by nonsense mutations in the SBP2 gene

CONTEXT

Selenoproteins are essential for life, and their biosynthesis requires the incorporation of the rare amino acid selenocysteine (Sec) in a process mediated by the Sec insertion sequence-binding protein 2 (SBP2). Although SBP2 is considered a rate-limiting factor mediating Sec incorporation, there has been little evidence so far linking SBP2 dysfunction to widespread selenoprotein-related disease.

OBJECTIVE

The objective of the study was to report the discovery of novel truncation mutations in the SBP2 gene (R120X/R770X) in a female adolescent and the clinical consequences of the combined deficiency of selenoproteins.

SUBJECTS AND METHODS

A 12-yr-old girl who presented with a syndrome of abnormal thyroid hormone metabolism, delayed bone maturation, congenital myopathy, and impaired mental and motor coordination development and her family were studied. The coding region of the SBP2 gene was analyzed by sequencing, and gel shift assays were performed to address the in vitro binding properties of the mutant SBP2 protein.

RESULTS

Serum levels of selenium and glutathione peroxidase in the proband were reduced, and selenoprotein P levels were undetectable. DNA sequencing of the SBP2 gene revealed a compound heterozygous mutation (R120X/R770X). The R120X mutation disrupted all functional motifs and the R770X inhibited the binding of SBP2 to Sec insertion sequence elements. Interestingly, selenium supplementation normalized serum selenium and glutathione peroxidase but not selenoprotein P levels and did not restore thyroid hormone metabolism dysfunction.

CONCLUSIONS

This distinctive phenotype can only be explained by the combined deficiency of functionally important selenoproteins and pinpoints the clinical relevance of selenoproteins and selenium economy in human development.

Serum selenium and selenoprotein P status in adult Danes - 8-year followup

Selenium is an essential micronutrient important to human health. The main objective of this study is to describe serum selenium and selenoprotein P status in two samples of the Danish population. In addition, the influence of various factors potentially associated with selenium status was investigated. Blood samples from a total of 817 randomly selected subjects from two cities in Denmark were analyzed. Half of the samples were collected in 1997-1998 and the other half in 2004-2005. Samples from women aged 18-22, 40-45 and 60-65 years, and men aged 60-65 years were selected for this study. All subjects had filled in a food frequency questionnaire (FFQ) and a questionnaire with information about smoking habits, alcohol consumption and exercise habits. Mean serum selenium level was 98.7+/-19.8microg/L and median selenoprotein P level was 2.72 (2.18-3.49)mg/L. Serum selenium and selenoprotein P increased with age, and selenoprotein P was higher in men than in women. Serum selenium levels decreased by 5% on average from 1997-98 to 2004-05 (P<0.001), whereas selenoprotein P level increased (P<0.001). The intake of fish correlated weakly with serum selenium level (r=0.14, P<0.001) but not with selenoprotein P level. Smoking status, alcohol intake, exercise habits, BMI and medicine use did not influence selenium status. It is concluded that selenium status in this Danish population is at an acceptable level. No major groups with regard to age, sex or lifestyle factors could be identified as being in risk for selenium deficiency.

Plasma selenium measurements in subjects from areas with contrasting gastric cancer risks in Colombia

BACKGROUND

An inverse association between selenium status and incidence of different neoplasias including gastric cancer has been reported. This pilot study aimed to determine and compare selenium status in two Colombian populations with different gastric cancer risks: a high-risk area in the volcanic region of the Andes Mountains and a low-risk area on the Pacific coast.

METHODS

Eighty nine adult males were recruited in the outpatient clinics of two public hospitals (44 and 45 from high- and low-risk areas, respectively) and provided a blood sample. Seventy one (79.8%) participants underwent upper gastrointestinal endoscopy. Plasma selenium was assayed using a fluorometric method, selenoprotein-P by ELISA, and glutathione peroxidase activity by a spectrophometric method. Histological diagnosis and Helicobacter pylori infection were evaluated in gastric biopsy samples. Unpaired samples t-test and linear regression analyses were used for statistical analyses.

RESULTS

Although none of the subjects in either of the two geographic areas was selenium deficient, the level of plasma selenium was significantly lower in men from the high-risk area compared with those from the low-risk area. Levels of selenoprotein-P and glutathione peroxidase activity were similar between groups after adjustment for confounders. Selenium measurements were not associated with histopathological diagnosis.

CONCLUSIONS

The high incidence of gastric cancer in the Andean region of Colombia is unlikely to be explained by selenium deficiency. We cannot exclude, however, that suboptimal selenium levels may exist in the gastric mucosa of subjects in the high-risk area. Therefore, the benefit of selenium supplementation in gastric cancer prevention cannot be dismissed.

New assay for the measurement of selenoprotein P as a sepsis biomarker from serum

Selenium (Se) is incorporated into selenoproteins as the 21st proteinogenic amino acid selenocysteine. Serum Se concentrations decline during critical illness and are indicative of poor prognosis. Serum Se is mainly contained in the hepatically derived selenoprotein P (SePP) which controls the expression of antioxidative selenoproteins. Here, we describe the development of an immunoluminometric sandwich assay that uses two polyclonal sheep antihuman SePP antibodies. After assessing the stability of the analyte, we determined SePP concentrations in samples from healthy individuals and patients with sepsis. The analytical detection limit was 0.016 mg SePP/L serum. The assay was linear on dilution. SePP was stable in serum at room temperature for at least 24 h and resistant to six freeze-thaw cycles. Median SePP concentration in healthy individuals was 3.04 mg SePP/L serum (25th-75th percentiles, 2.6-3.4 mg/L) which corresponded to 98.4 microg Se/L serum. The interlaboratory CV was <20% for SePP values >0.06 mg/L. There was no association with gender, but concentrations differed between young and older individuals. Median SePP concentrations were significantly (P<0.0001) decreased in patients with sepsis (n=60) compared to healthy controls (n=318). Since SePP contains the major fraction of serum Se, we conclude that downregulation of SePP biosynthesis or removal of circulating SePP from blood underlies the negative acute phase response of serum Se in critical illness.

Serum selenium measurements in women with early-stage breast cancer with and without chemotherapy-induced ovarian failure

Blood selenium has been shown to decline as breast cancer progresses and fluctuate with estrogen. The objective of this study was to determine the effect of estrogen depletion resulting from chemotherapy-induced ovarian failure on serum selenium and selenoproteins in stage I/II premenopausal breast cancer patients. Serum selenium, glutathione peroxidase (GPx) activity, and selenoprotein P (SelP) were measured and a dietary questionnaire was completed at baseline (before chemotherapy) and 6, 12, and 24 months after start of chemotherapy. Twelve months after the start of adjuvant chemotherapy 33 (75%) patients developed ovarian failure (OF) and 11 (25%) retained menstrual function (non-OF). Dietary selenium intake was 30-58% above the Recommended Dietary Allowance for both groups. By six months the mean estradiol (pg/ml) was lower in the OF group than in the non-OF group (32+/-5 versus 140+/-62 pg/ml, p=0.01) and this difference was maintained at 12 and 24 months. However, there was no differences in serum selenium, GPx activity, or SelP in the OF and non-OF groups at 6, 12, and 24 months. Selenium status in premenopausal breast cancer patients, as measured by serum selenium, GPx and SelP, was within the normal range before and following adjuvant chemotherapy, and was not affected by chemotherapy-induced ovarian failure.