Strong associations of serum selenoprotein P with all-cause mortality and mortality due to cancer, cardiovascular, respiratory and gastrointestinal diseases in older German adults

Selenium: The Toxicant for Pathogen and Pest but the Guardian of Soil and Crop

Selenium (Se) is an essential micronutrient for higher organisms and plays a beneficial role in plant growth and development. In recent years, there has been growing interest in the using of Se to enhance plant resilience, particularly in mitigating the effects of diseases and pests in agricultural systems. This review offers a comprehensive analysis of the sources and chemical forms of Se in soil, investigates the mechanisms of plant uptake and metabolism of different Se forms, and evaluates the physical and chemical inhibition of pathogens by various Se forms, as well as the role of Se in enhancing plant systemic resistance for crop protection. Additionally, we summarize current research on the role of Se in pest and disease control and explore potential future research directions, with a focus on integrating Se into sustainable agricultural practices. The insights presented in this review seek to establish a solid scientific foundation for Se-based approaches to pest control and emphasize its potential application in sustainable agriculture.

Low blood levels of selenium, selenoprotein P and GPx3 are associated with accelerated biological aging: results from the Berlin Aging Study II (BASE-II)

BACKGROUND

Biological age reflects inter-individual differences in biological function and capacity beyond chronological age. DNA methylation age (DNAmA) and its deviation from chronological age, DNAmA acceleration (DNAmAA), which was calculated as residuals of leukocyte cell count adjusted linear regression of DNAmA on chronological age, were used to estimate biological age in this study. Low levels of serum selenium, selenoprotein P (SELENOP), and the selenocysteine-containing glutathione peroxidase 3 (GPx3) are associated with adverse health outcomes and selenium supplementation is discussed as an anti-aging intervention.

METHODS

In this study, we cross-sectionally analyzed 1568 older participants from the observational Berlin Aging Study II (mean age ± SD: 68.8 ± 3.7 years, 51% women). Serum selenium was measured by total reflection X-ray fluorescence (TXRF) spectroscopy and SELENOP was determined by sandwich ELISA. GPx3 was assessed as part of a proteomics dataset using liquid chromatography-mass spectrometry (LC-MS). The relationship between selenium biomarkers and epigenetic clock measures was analyzed using linear regression analyses. P values and 95% confidence intervals (not adjusted for multiple testing) are stated for each analysis.

RESULTS

Participants with deficient serum selenium levels (< 90 μg/L) had a higher rate of biological aging (DunedinPACE, β = - 0.02, SE = 0.01, 95% CI - 0.033 to - 0.004, p = 0.010, n = 865). This association remained statistically significant after adjustment for age, sex, BMI, smoking, and first four genetic principal components (β = - 0.02, SE = 0.01, 95% CI - 0.034 to - 0.004, p = 0.012, n = 757). Compared to the highest quartile, participants in the lowest quartile of SELENOP levels showed an accelerated biological aging rate (DunedinPACE, β = - 0.03, SE = 0.01, 95% CI - 0.051 to - 0.008, p = 0.007, n = 740, fully adjusted model). Similarly, after adjustment for confounders, accelerated biological age was found in participants within the lowest GPx3 quartile compared to participants in the fourth quartile (DunedinPACE, β = - 0.04, SE = 0.01, 95% CI - 0.06 to - 0.02, p = 0.001, n = 674 and GrimAge, β = - 0.98, SE = 0.32, 95% CI - 1.6 to - 0.4, p = 0.002, n = 608). Only the association with GPx3 remained statistically significant after multiple testing correction.

CONCLUSION

Our study suggests that low levels of selenium biomarkers are associated with accelerated biological aging measured through epigenetic clocks. This effect was not substantially changed after adjustment for known confounders.

Elucidating emerging signaling pathways driving endothelial dysfunction in cardiovascular aging

The risk for developing cardiovascular diseases dramatically increases in older individuals, and aging vasculature plays a crucial role in determining their morbidity and mortality. Aging disrupts endothelial balance between vasodilators and vasoconstrictors, impairing function and promoting pathological vascular remodeling. In this Review, we discuss the impact of key and emerging molecular pathways that transduce aberrant inflammatory signals (i.e., chronic low-grade inflammation-inflammaging), oxidative stress, and mitochondrial dysfunction in aging vascular compartment. We focus on the interplay between these events, which contribute to generating a vicious cycle driving the progressive alterations in vascular structure and function during cardiovascular aging. We also discuss the primary role of senescent endothelial cells and vascular smooth muscle cells, and the potential link between vascular and myeloid cells, in impairing plaque stability and promoting the progression of atherosclerosis. The aim of this summary is to provide potential novel insights into targeting these processes for therapeutic benefit.

Serum selenium, selenoprotein P and glutathione peroxidase 3 in rheumatoid, psoriatic, juvenile idiopathic arthritis, and osteoarthritis

Selenoprotein P (SELENOP) controls selenium (Se) transport, and glutathione peroxidase 3 (GPx3) elicits antioxidant activity in blood. Inflammation associates with Se deficiency, but knowledge concerning selenoproteins in inflammatory rheumatic musculoskeletal diseases (iRMD) is limited. We compared three Se biomarkers in patients with rheumatoid (RA), psoriatic (PsA), and juvenile idiopathic arthritis (JIA) in comparison to osteoarthritis (OA) and healthy subjects, to improve the data base on selenoprotein expression in iRMD. The cross-sectional study enrolled n=272 patients with RA (n=131), PsA (n=67), JIA (n=22) and OA (n=52). Serum Se was quantified by total reflection X-ray fluorescence, SELENOP by ELISA and GPx3 by an enzymatic test. Data from the EPIC trial served as reference. Impairment of daily life was assessed by the Functional Ability Questionnaire (FfbH). Serum SELENOP and Se concentrations correlated linearly in all groups and were below the average measured in EPIC. Se concentration was not different between the patient groups. Compared to controls, SELENOP levels were low in iRMD patients. GPx3 activity was particularly low in JIA and PsA. Seropositive but not seronegative RA patients displayed a disrupted interaction between GPx3 and Se or SELENOP. SELENOP associated with the functional status measured by the FfbH, most pronounced in OA (R=0.76, P < .01). The data indicate selenoprotein deficiency in the majority of patients with iRMD, and a positive relation of SELENOP with functional status in OA. Since increased Se supply improves selenoprotein biosynthesis, a personalized correction of diagnosed deficiency merits consideration to improve Se transport and ameliorate disease burden.

Circulating Glutathione Peroxidase-3 in Elderly-Association with Renal Function, Cardiovascular Mortality, and Impact of Selenium and Coenzyme Q10 Supplementation

Low-selenium status was associated with impaired renal function, which improved after selenium and coenzyme Q10 supplementation in an RCT. Here, we evaluated serum glutathione peroxidase-3 (GPx3) and its relation to serum selenium, selenoprotein P (SELENOP), renal function, mortality, and the impact of supplementation, which are all important, especially in elderly individuals. In total, 383 study participants (197 receiving selenium yeast and coenzyme Q10 and 186 on a placebo) were evaluated. We applied benchmark dose modelling to determine GPx3 saturation, ANCOVA, Kaplan-Meier, and multivariate Cox proportional regression analyses for mortality evaluations. Selenium and GPx3 activity were modestly correlated. In comparison with SELENOP, GPx3 levelled off at a much lower value, 100 vs. 150 µg Se/L. GPx3 was associated with renal function, but not SELENOP. Supplementation increased glomerular function by ≈23% with an increase in GPx3. Being low in GPx3 displayed twice the risks of mortality in both placebos and active treatments. At serum selenium <100 µg/L, GPx3 activity was dependent on both selenium status and renal function. As renal function is reduced in the elderly, GPx3 is not an appropriate marker of selenium status. Low GPx3 was associated with an increased risk of mortality dependent of selenium status and independent of renal function.

Deciphering the associations of selenium distribution in serum GPx-3 and selenoprotein P with cardiovascular risk factors in a healthy population with moderate levels of selenium: The ATTICA study

BACKGROUND

Selenium (Se) is an essential micronutrient, important for human health. The relationship of Se with cardiovascular risk factors is still inconclusive, especially regarding the role of different selenoproteins. The present study evaluated the relation of total serum Se as well as its distribution in plasma selenoproteins, namely glutathione peroxidase 3 (GPx3) and selenoprotein P (SelP) with cardiovascular risk factors in a sex-specific manner, in a healthy population with moderate levels of Se.

METHODS

A sub-sample from the ATTICA Study's database, consisting of 398 participants (160 females and 238 males) with data on Se and selenoproteins levels, was considered. GPx3, SelP and the main non-specific serum selenium containing protein, selenoalbumin (SeAlb) were simultaneously determined in human plasma by high-performance liquid chromatography (HPLC) coupled with inductively coupled plasma mass spectrometry (ICP-MS) at baseline.

RESULTS

Participants that belong to the highest tertiles of GPx3 and SelP presented the lowest blood pressure. Homocysteine was inversely associated with SelP and its ratio SelP/TSe in both sexes. In males, the lowest tertile of GPx3 showed lower adiponectin levels (0.66 ± 0.21 μg/mL) in comparison to the 2nd tertile of GPx3 (p=0.002), SelP was inversely associated with visceral adipose index (VAI) (-2.29 ± 0.81, p=0.005). Particularly, in males, the middle tertile of SelP had the lowest VAI values. Regarding females, lower Lp(a) concentration by 11.96 ± 5.84 mg/dL was observed in low SelP levels while higher leptin concentration by 2.30 ± 0.73 μg/L and lower fibrinogen concentration by 27.32 ± 13.30 mg/dL was detected in low GPx3 levels.

CONCLUSION

Circulating selenoproteins exert differentiated effects on cardiovascular risk factors, some of them in a sex-specific manner.

The association between selenium status and global and attention-specific cognition in very old adults in the Newcastle 85+ Study: cross-sectional and longitudinal analyses

BACKGROUND

Selenium has potential safeguarding properties against cognitive decline, because of its role in protecting DNA, proteins, and lipids in the brain from oxidative damage. However, acute and chronic overexposure to selenium can be neurotoxic.

OBJECTIVE

The aim of this analysis was to explore the association between selenium status [serum selenium and selenoprotein P (SELENOP) concentrations and glutathione peroxidase 3 (GPx3) activity] and cognitive function in 85-y olds living in Northeast England at baseline and ≤5 y of follow-up.

METHODS

Global cognitive performance was assessed in 755 participants from the Newcastle 85+ study using the standardized Mini-Mental State Examination and attention-specific cognition was assessed using composite scores derived from the Cognitive Drug Research System. Serum selenium, SELENOP, and GPx3 activity were measured at baseline by total reflection X-ray fluorescence, enzyme-linked immunosorbent assay, and coupled-enzyme reaction, respectively. Regression analyses explored linear and nonlinear associations between continuous values and tertiles of selenium status biomarkers, respectively, and cognitive function at baseline. Generalized linear mixed models explored associations between continuous values and tertiles of selenium status biomarkers, and global cognitive decline over 5 y, and attention-specific cognitive decline over 3 y.

RESULTS

Over 3 and 5 y, none of the selenium biomarkers were associated with the rate of cognitive decline. At baseline, in fully adjusted models, higher serum selenium was nonlinearly associated with global cognition (β = 0.05 ± 0.01, P = 0.387 linear, β = 0.04 ± 0.01, P = 0.002 nonlinear). SELENOP and GPx3 activity were not associated with any cognitive outcomes.

CONCLUSIONS

There were no associations between selenium status and cognitive decline. However, serum selenium, but not SELENOP or GPx3 activity, was positively associated nonlinearly with global cognition at baseline. Furthermore, these associations were not evident during follow-up, potentially because of residual confounding and reverse causation.

Differential associations between selenoprotein P and distal sensorimotor polyneuropathy in people with and without diabetes: KORA F4/FF4 study

BACKGROUND

Oxidative stress is a risk factor for distal sensorimotor polyneuropathy (DSPN). Selenoprotein P is a protein with antioxidant properties but has not been investigated in the context of DSPN. This study aimed to assess the associations between selenoprotein P and DSPN in people without and with type 2 diabetes (T2D).

METHODS

Cross-sectional and prospective analyses were based on 1053 (including 217 with T2D) and 513 participants (including 79 with T2D), respectively, aged 61-82 years from the population-based KORA F4 survey. DSPN at baseline (KORA F4) and in the follow-up survey KORA FF4 was defined based on the Michigan Neuropathy Screening Instrument. Serum levels of full-length selenoprotein P were quantified by ELISA. Associations between selenoprotein P and prevalent or incident DSPN were estimated using logistic regression analysis adjusting for multiple confounders.

RESULTS

Selenoprotein P levels were not associated with prevalent DSPN in the total sample. However, there was a significant interaction by diabetes status. Higher levels of selenoprotein P were associated with lower odds of prevalent DSPN in individuals without T2D (fully adjusted model: OR 0.825 [95 % CI 0.682, 0.998], p = 0.0476), but not in those with T2D (OR [95 % CI] 1.098 [0.829, 1.454], p = 0.5132; pinteraction = 0.0488). Selenoprotein P levels were not associated with incident DSPN over a follow-up of 6.5 years.

CONCLUSION

In individuals without T2D from the older general population, lower selenoprotein P levels were associated with a higher prevalence of DSPN. Whether the antioxidant properties of selenoprotein P are responsible for the observed associations remains to be elucidated in future research.

Selenium, diabetes, and their intricate sex-specific relationship

Selenium (Se) is an essential trace element, which is inserted as selenocysteine (Sec) into selenoproteins during biosynthesis, orchestrating their expression and activity. Se is associated with both beneficial and detrimental health effects; deficient supply or uncontrolled supplementation raises concerns. In particular, Se was associated with an increased incidence of type 2 diabetes (T2D) in a secondary analysis of a randomized controlled trial (RCT). In this review, we discuss the intricate relationship between Se and diabetes and the limitations of the available clinical and experimental studies. Recent evidence points to sexual dimorphism and an association of Se deficiency with gestational diabetes mellitus (GDM). We highlight the emerging evidence linking high Se status with improved prognosis in patients with T2D and lower risk of macrovascular complications.

Selenoprotein P increases upon selenium and coenzyme Q10 supplementation and is associated with telomere length, quality of life and reduced inflammation and mortality

BACKGROUND

Selenoprotein P (SELENOP) transports selenium to extrahepatic tissues and is a biomarker of selenium status. Low soil selenium leads to low dietary selenium intake. A consequence is an increased risk of cardiovascular disease.

OBJECTIVE

To investigate clinical aspects associated with SELENOP deficiency, including biomarkers of inflammation, quality of life, and mortality within 12 years, and the effect of dietary selenium and coenzyme Q10 supplementation on SELENOP.

METHODS

SELENOP was determined at inclusion and after four years of supplementation in 403 elderly community-living participants low in selenium receiving selenium yeast (200 μg/day) and coenzyme Q10 (200 mg/day), or placebo. Pre-intervention, the average serum selenium level was 67 μg/L. T-tests, repeated measures of variance, Cox proportional regressions analyses, Kaplan-Meier graphs and ANCOVA analyses were applied. Associations with biomarkers of inflammation, telomere length, quality of life and mortality were investigated. Benchmark modelling was used to determine the serum selenium concentration at which the saturation levels of SELENOP and GPx3 was achieved. Comparison with GPx3 and serum selenium to identify increased mortality risk was performed, and the effect of supplementation on SELENOP levels were evaluated.

RESULTS

Inverse associations were observed between the level of SELENOP at inclusion and biomarkers for inflammation. At follow-up, shorter telomere lengths were seen in those with low levels of SELENOP at inclusion, whereas high levels of SELENOP were associated with better quality of life and decreased mortality. SELENOP had increased prognostic power compared to GPx3 and selenium. Saturation of SELENOP was achieved at a serum selenium level of 146 μg/L, and for GPx3 at 99 μg/L. Supplementation induced higher levels of SELENOP.

CONCLUSION

Significant associations between SELENOP and inflammation, length of telomeres, quality of life, and mortality were observed. Thus, selenium supplementation improved SELENOP expression, thereby facilitating systemic selenium bioavailability and resulting in the observed positive health effects.

Maternal selenium deficiency during pregnancy in association with autism and ADHD traits in children: The Odense Child Cohort

BACKGROUND

Selenoproteins regulate pathways controlling neurodevelopment, e.g., redox signaling and thyroid hormone metabolism. However, studies investigating maternal selenium in relation to child neurodevelopmental disorders are scarce.

METHODS

719 mother-child pairs from the prospective population-based Odense Child Cohort study in Denmark were included. Three selenium biomarkers, i.e. concentrations of serum selenium, selenoprotein P (SELENOP), and activity of glutathione peroxidase 3 (GPX3), along with serum copper, zinc and iron were measured in early third trimester (at 28.9+/-0.8 weeks of pregnancy). ADHD and ASD traits in children were assessed systematically using the established Child Behaviour Checklist at 5 years of age, based on a Danish reference cohort with cut-off at 90th percentile. Multivariable regression models adjusted for biologically relevant confounders were applied.

RESULTS

155 of 719 (21.6 %) children had ASD traits and 59 of 719 (8.2 %) children had traits of ADHD at 5 years of age. In crude and adjusted models, all three selenium biomarkers associated inversely with ADHD traits. For ADHD, fully adjusted OR for 10 μg/L increment in selenium was 0.76 (95 % CI 0.60, 0.94), for one mg/L increment in SELENOP was 0.73 (0.56, 0.95), and for 10 U/L increment in GPx3 was 0.93 (0.87,1.00). Maternal total selenium was inversely associated with child ASD traits, OR per 10 μg/L increment was 0.85 (0.74, 0,98). SELENOP and GPx3 were not associated with ASD traits. The associations were specific to selenium, as other trace elements such as copper, zinc, or iron were not associated with the outcomes.

CONCLUSIONS

The results provide coherent evidence for selenium deficiency as a risk factor for ADHD and ASD traits in an environment with borderline supply, the causality of which should be elucidated in a randomized controlled trial.

Selenoprotein P in a Rodent Model of Exercise; Theorizing Its Interaction with Brain Reward Dysregulation, Addictive Behavior, and Aging

Exercise promotes health and wellness, including its operation as a protective factor against a variety of psychological, neurological, and chronic diseases. Selenium and its biomarker, selenoprotein P (SEPP1), have been implicated in health, including cancer prevention, neurological function, and dopamine signaling. SEPP1 blood serum levels were compared with a one-way ANOVA between sedentary (SED), moderately exercised (MOD) [10 m/min starting at 10 min, increasing to 60 min], and high-intensity interval training (HIIT) exercised rats [30 min in intervals of 2-min followed by a 1-min break, speed progressively increased from 10 to 21 m/min]. HIIT rats showed significantly higher serum SEPP1 concentrations compared to MOD and SED. More specifically, HIIT exercise showed an 84% increase in SEPP1 levels compared to sedentary controls. MOD rats had greater serum SEPP1 concentrations compared to SED, a 33% increase. The results indicated that increased exercise intensity increases SEPP1 levels. Exercise-induced increases in SEPP1 may indicate an adaptive response to the heightened oxidative stress. Previous studies found a significant increase in dopamine D2 receptor (D2R) binding in these same rats, suggesting a potential association between SEPP1 and dopamine signaling during exercise. Modulating antioxidants like SEPP1 through personalized therapies, including exercise, has broad implications for health, disease, and addiction.