Untargeted Metabolomic Study of Lung Cancer Patients after Surgery with Curative Intent.

Lung cancer (LC) is a leading cause of mortality, claiming more than 1.8 million deaths per year worldwide. Surgery is one of the most effective treatments when the disease is in its early stages. The study of metabolic alterations after surgical intervention with curative intent could be used to assess the response to treatment or the detection of cancer recurrence. In this study, we have evaluated the metabolomic profile of serum samples (n = 110) from preoperative (PRE) and postoperative (POST) LC patients collected at two different time points (1 month, A; 3-6 months, B) with respect to healthy people. An untargeted metabolomic platform based on reversed phase (RP) and hydrophilic interaction chromatography (HILIC), using ultra-high performance liquid chromatography (UHPLC) and mass spectrometry (MS), was applied (MassIVE ID MSV000092213). Twenty-two altered metabolites were annotated by comparing all the different studied groups. DG(14,0/22:1), stearamide, proline, and E,e-carotene-3,3'-dione were found altered in PRE, and their levels returned to those of a baseline control group 3-6 months after surgery. Furthermore, 3-galactosyllactose levels remained altered after intervention in some patients. This study provides unique insights into the metabolic profiles of LC patients after surgery at two different time points by combining complementary analytical methods.

Omics insights into the responses to dietary selenium.

Selenium is a well-known health-relevant element related with cancer chemoprevention, neuroprotective roles, beneficial in diabetes, and in several infectious diseases, among others. It is naturally present in some foods, but deficiency in people led to the production of nutraceuticals, supplements, and functional food enriched in this element. There is a U-shaped link between selenium levels and health and a narrow range between toxic and essential levels, and thus, supplementation should be performed carefully. Omics methodologies have become valuable approaches to delve into the responses of dietary selenium in mammals that allowed a deeper knowledge about the metabolism of this element as well as its biological role. In this review, we discuss omics approaches from the workflows to their applications that has been previously used to deep insight into the metabolism of dietary selenium. There is a special focus on selenoproteins, metabolomics responses in blood and tissues (e.g., brain, reproductive organs, etc.) as well as the impact on gut microbiota and its metabolites profile. Thus, we mainly reviewed heteroatom-tagged proteomics, metallomics, metabolomics, and metataxonomics, usually combined with transcriptomics, genomics, and other molecular methods.

Untargeted Gut Metabolomics to Delve the Interplay between Selenium Supplementation and Gut Microbiota.

Selenium (Se) is an essential trace element with important health roles due to the antioxidant properties of selenoproteins. To analyze the interplay between Se and gut microbiota, gut metabolomic profiles were determined in conventional (C) and microbiota depleted mice (Abx) after Se-supplementation (Abx-Se) by untargeted metabolomics, using an analytical multiplatform based on GC-MS and UHPLC-QTOF-MS (MassIVE ID MSV000087829). Gut microbiota profiling was performed by 16S rRNA gene amplicon sequencing. Significant differences in the levels of about 70% of the gut metabolites determined, including fatty acyls, glycerolipids, glycerophospholipids, and steroids, were found in Abx-Se compared to Abx, and only 30% were different between Abx-Se and C, suggesting an important effect of Se-supplementation on Abx mice metabolism. At genus level, the correlation analysis showed strong associations between metabolites and gut bacterial profiles. Likewise, higher abundance of Lactobacillus spp., a potentially beneficial genus enriched after Se-supplementation, was associated with higher levels of prenol lipids, phosphatidylglycerols (C-Se), steroids and diterpenoids (Abx-Se), and also with lower levels of fatty acids (Abx-Se). Thus, we observed a crucial interaction between Se intake-microbiota-metabolites, although further studies to clarify the specific mechanisms are needed. This is the first study about untargeted gut metabolomics after microbiota depletion and Se-supplementation.

Impact of Antibiotic-Induced Depletion of Gut Microbiota and Selenium Supplementation on Plasma Selenoproteome and Metal Homeostasis in a Mice Model.

Selenium (Se) is a micronutrient involved in important health functions and it has been suggested to shape gut microbiota. Limited information on Se assimilation by gut microbes and the possible link with selenoproteins are available. For this purpose, conventional and gut microbiota-depleted BALB/c mice were fed a Se-supplemented diet. The absolute quantification of mice plasma selenoproteins was performed for the first time using heteroatom-tagged proteomics. The gut microbiota profile was analyzed by 16S rRNA gene sequencing. Se-supplementation modulated the concentration of the antioxidant glutathione peroxidase and the Se-transporter selenoalbumin as well as the metal homeostasis, being influenced by microbiota disruption, which suggests an intertwined mechanism. Se also modulated microbiota diversity and richness and increased the relative abundance of some health-relevant taxa (e.g., families Christensenellaceae, Ruminococcaceae, and Lactobacillus genus). This study demonstrated the potential beneficial effects of Se on gut microbiota, especially after antibiotic-treatment and the first associations between specific bacteria and plasma selenoproteins.

Absolute quantification of selenoproteins and selenometabolites in lung cancer human serum by column switching coupled to triple quadrupole inductively coupled plasma mass spectrometry.

One of the most important causes of the high mortality rate and low life expectancy of lung cancer is the detection at advanced stages. Thus, there is an urgent need for early diagnosis and the search of new selective biomarkers. Selenium is an important constituent of selenoproteins and a powerful antioxidant able to protect against cancer. In this work, the absolute quantification of selenium in selenoproteins and the total content in selenometabolites has been performed for the first time in serum from lung cancer patients (LC) and healthy controls (HC). To this end, a method for the simultaneous speciation of selenoproteins using size exclusion chromatography (SEC) and affinity chromatography (AF) with detection by ICP-QQQ-MS, and quantification by isotopic dilution (IDA) (SEC-AF-HPLC-SUID-ICP-QQQ-MS) was developed to determine the selenium concentration in eGPx, SEPP1 and SeAlb, as well as total selenometabolites, to find alterations that may serve as biomarkers of this disease. In the same way, a method based on anion-exchange chromatography coupled to ICP-QQQ-MS was developed to quantify selenometabolites (SeCys2, SeMeSeCys, SeMet, selenite and selenate) in the same LC and HC serum samples. The results showed that the averaged concentrations of selenium in eGPx, SeAlb and selenite were significantly higher in LC patients (LC (eGPx: 21.24 ± 0.77 ng g-1; SeAlb: 49.56 ± 3.16 ng g-1 and Se(IV): 6.20 ± 1.22 ng g-1) than in HC group (eGPx: 16.96 ± 0.53 ng g-1; SeAlb: 38.33 ± 2.66 ng g-1 and Se(IV): 3.56 ± 0.55 ng g-1). In addition, the ratios between selenoproteins and selenometabolites have been calculated for the first to study their potential use as LC biomarkers. The rates eGPx/SEPP1, SEPP1/SeAlb, eGPx/Se(IV) and SEPP1/Se(IV) were significantly different between LC and HC groups.

Metabolic impairments, metal traffic, and dyshomeostasis caused by the antagonistic interaction of cadmium and selenium using organic and inorganic mass spectrometry.

Cadmium (Cd) has become one of the most important environmental pollutants in the world, derived from natural and industrial sources, which is known to be accumulated in the human body, producing serious health effects. On the other hand, Selenium (Se) is an essential element for mammals, which is well known for its antagonistic interaction against Cd toxicity, such as the prevention of oxidative stress induced by this element. For this reason, the use of complementary analytical methods to study the homeostasis of metals, "traffic" between different organs and massive information about metabolites altered by the exposure, is of great interest. To this end, a metabolomic workflow based on the use of direct infusion mass spectrometry (DIMS) and gas chromatography mass spectrometry (GC-MS) was applied in mice serum. On the other hand, metal homeostasis and traffic between different organs and serum of mice exposed to Cd and Se have been evaluated by determining the concentration of metals by inductively coupled plasma mass spectrometry. This work demonstrates for the first time that Cd exposure causes a decrease of all the elements studied in the lung except itself. On the other hand, Se provokes As trafficking from metabolically less active organs (brain, lung, and testes) to others with greater metabolic activity (kidney), which also facilitates its excretion. Moreover, when mice are only exposed to Se, it provokes the accumulation of almost all the elements in the kidney, except Cd that increases also in the liver and brain. However, when both elements are simultaneously administered, Se increases Cd concentration in all the organs except in the serum and especially in the testis. On the other hand, important metabolic alterations have been detected in the energy and amino acid metabolism, as well as degradation of phospholipidic membranes, and in free fatty acids. In summary, the results show the high potential of the combined use of organic and inorganic mass spectrometry to establish Cd and Se interaction and the biological impairments caused and to provide information about metal traffic and metabolomic changes in exposure experiments.

Insights into cancer and neurodegenerative diseases through selenoproteins and the connection with gut microbiota - current analytical methodologies.

Introduction: Selenium plays many key roles in health especially in connection with cancer and neurodegenerative diseases. However, it needs to be appreciated that the essentiality/toxicity of selenium depends on both, a narrow range of concentration and the chemical specie involved. In this context, selenoproteins are essential biomolecules against these disorders, mainly due to its antioxidant action. To this end, analytical methodologies may allow identifying and quantifying individual selenospecies in human biofluids and tissues. Areas covered: This review focus on the role of selenoproteins in medicine, with special emphasis in cancer and neurodegenerative diseases, considering the possible link with gut microbiota. In particular, this article reviews the analytical techniques and procedures recently developed for the absolute quantification of selenoproteins and selenometabolites in human biofluids and tissues. Expert commentary: The beneficial role of selenium in human health has been extensively studied and reviewed. However, several challenges remain unsolved as discussed in this article: (i) speciation of selenium (especially selenoproteins) in cancer and neurodegenerative disease patients; (ii) supplementation of selenium in humans using functional foods and nutraceuticals; (iii) the link between selenium and selenoproteins expression and the gut microbiota and (iv) analytical methods and pitfalls for the absolute quantification of selenoproteins and selenometabolites.

Simultaneous Speciation of Selenoproteins and Selenometabolites in Plasma and Serum.

Selenium is an essential element incorporated to different proteins with important biological functions in connection to antioxidant activity, cancer-protective properties, neurodegenerative pathologies, and prevention of effects of diabetes, among others. In addition, selenoamino acids play a basic role in the global equilibrium of key selenium-biomolecules synthesis, including selenoprotein P, selenoalbumin, and glutathione peroxidase. Homeostasis of these selenium-containing biomolecules involves different organs in living organisms including human, and bloodstream is the connection fluid in this process. Therefore, it is very important to have an analytical methodology suitable for selenium proteins and metabolites speciation in serum and plasma samples. For this purpose, a simultaneous speciation method for Se-containing biomolecules in serum/plasma is described on the basis of in series three-dimensional chromatography: size exclusion, affinity, and anion exchange high performance liquid chromatography (3D/SE-AF-AEC-HPLC), using different columns of each type and hyphenation to inductively coupled plasma-(quadrupole) mass spectrometry (ICP-MS). The method allows the quantitative simultaneous analysis of selenoprotein P (SeP), extracellular glutathione peroxidase (eGPx), selenoalbumin (SeAlb), selenite, and selenate in serum (from human and mouse) using species-unspecific isotope dilution (SUID). In addition, a simplified two-dimensional approach (2D/SE-AF-HPLC-SUID-ICP-MS) is described when selenium metabolites are globally analyzed. The method provides detection limits in the range 0.2-1.3 ng of Se g-1 and avoids typical interferences in this matrix from chloride and bromide with a chromatographic runtime less than 35 min.

Selenium, selenoproteins and selenometabolites in mothers and babies at the time of birth.

The deficiency of Se, an essential micronutrient, has been implicated in adverse pregnancy outcomes. Our study was designed to determine total serum Se, selenoproteins (extracellular glutathione peroxidase (GPx-3), selenoprotein P (SeP)), selenoalbumin (SeAlb) and selenometabolites in healthy women and their newborns at delivery. This cross-sectional study included eighty-three healthy mother-baby couples. Total Se and Se species concentrations were measured in maternal and umbilical cord sera by an in-series coupling of two-dimensional size-exclusion and affinity HPLC. Additional measurements of serum SeP concentration and of serum GPx-3 enzyme activity were carried out using ELISA. Total Se concentration was significantly higher in maternal serum than in cord serum (68·9 (sd 15·2) and 56·1 (sd 14·6) µg/l, respectively; P<0·01). There were significant correlations between selenoprotein and SeAlb concentrations in mothers and newborns, although they also showed significant differences in GPx-3 (11·2 (sd 3·7) v. 10·5 (sd 3·5) µg/l; P<0·01), SeP (42·5 (sd 9·5) v. 28·1 (sd 7·7) µg/l; P<0·01) and SeAlb (11·6 (sd 3·6) v. 14·1 (sd 4·3) µg/l; P<0·01) concentrations in maternal and cord sera, respectively. Serum GPx-3 activity and concentration were positively correlated in mothers (r 0·33; P=0·038) but not in newborns. GPx-3 activity in cord serum was significantly correlated with gestational age (r 0·44; P=0·009). SeAlb concentration was significantly higher in babies, whereas SeP and GPx-3 concentrations were significantly higher in mothers. The differences cannot be explained by simple diffusion; specific transfer mechanisms are probably involved. GPx-3 concentrations in mothers, at delivery, are related to maternal Se status, whereas the GPx-3 activity in cord serum depends on gestational age.