Dietary vanadium induces oxidative stress in the intestine of broilers

Associations between prenatal multiple metal exposure and preterm birth: Comparison of four statistical models

BACKGROUND

Exposure to some heavy metals has been demonstrated to be related to the risk of preterm birth (PTB). However, the effects of multi-metal mixture are seldom assessed. Thus, we aimed to investigate the associations of maternal exposure to metal mixture with PTB, and to identify the main contributors to PTB from the mixture.

METHODS

The population in the nested case-control study was from a prospective cohort enrolled in Wuhan, China between 2012 and 2014. Eighteen metals were measured in maternal urine collected before delivery. Logistic regression, elastic net regularization (ENET), weighted quantile sum regression (WQSR), and Bayesian kernel machine regression (BKMR) were used to estimate the overall effect and identify important mixture components that drive the associations with PTB.

RESULTS

Logistic regression found naturally log-transformed concentrations of 13 metals were positively associated with PTB after adjusting for the covariates, and only V, Zn, and Cr remained the significantly positive associations when additionally adjusting for the 13 metals together. ENET identified 11 important metals for PTB, and V (β = 0.23) had the strongest association. WQSR determined the positive combined effect of metal mixture on PTB (OR: 1.44, 95%CI: 1.32, 1.57), and selected Cr and V (weighted 0.41 and 0.32, respectively) as the most weighted metals. BKMR analysis confirmed the overall mixture was positively associated with PTB, and the independent effect of V was the most significant. Besides, BKMR showed the non-linear relationships of V and Cu with PTB, and the potential interaction between Zn and Cu.

CONCLUSION

Applying different statistical models, the study found that exposure to the metal mixture was associated with a higher risk of PTB, and V was identified as the most important risk factor among co-exposed metals for PTB.

Contribution of trace element exposure to gestational diabetes mellitus through disturbing the gut microbiome

BACKGROUND

A healthy gut microbiome is critical for glucose metabolism during pregnancy. In vivo studies indicate that trace element affects the composition and function of the gut microbiome and potentially leads to metabolic disorders but their relationships are largely unknown. We aimed to investigate whether the gut microbiome plays a role in the relationship between trace element exposure and gestational diabetes mellitus (GDM).

METHODS

In a prospective cohort study, serum levels of 22 trace elements and the fecal gut microbiome composition were assessed in 837 pregnant women in the second trimester between 22 and 24 weeks of pregnancy prior to GDM diagnosis. Regression and mediation analysis were used to explore the link between element exposure, the gut microbiome, and GDM.

RESULTS

128 pregnant women (15.3%) were diagnosed with GDM. No individual trace elements were found significantly associated with GDM. In contrast, the composition of the gut microbiome was dramatically altered in women later diagnosed with GDM and characterized by lower alpha diversity and lower abundance of co-abundance groups (CAGs) composed of genera belonging to Ruminococcaceae, Coriobacteriales, and Lachnospiraceae. Rubidium (Rb) was positively associated with alpha diversity indices while mercury (Hg) and vanadium (V) showed negative associations. Elements including rubidium (Rb), thallium (Tl), arsenic (As), and antimony (Sb) were significantly correlated with GDM-related CAGs and mediation analysis revealed that Rb and Sb were inversely related to GDM risk by altering abundance levels of CAGs enriched for Lachnospiraceae, Coriobacteriales, and Ruminococcaceae.

CONCLUSION

Our study indicates that trace element exposure is associated with specific gut microbiome features that may contribute to GDM development, which could provide a new avenue for intervening in environmental exposure-related GDM.

Vanadium and Oxidative Stress Markers - In Vivo Model: A Review

This review article is an attempt to summarize the current state of knowledge of the impact of Vanadium (V) on Oxidative Stress (OS) markers in vivo. It shows the results of our studies and studies conducted by other researchers on the influence of different V compounds on the level of selected Reactive Oxygen Species (ROS)/Free Radicals (FRs), markers of Lipid peroxidation (LPO), as well as enzymatic and non-enzymatic antioxidants. It also presents the impact of ROS/peroxides on the activity of antioxidant enzymes modulated by V and illustrates the mechanisms of the inactivation thereof caused by this metal and reactive oxygen metabolites. It also focuses on the mechanisms of interaction of V with some nonenzymatic compounds of the antioxidative system. Furthermore, we review the routes of generation of oxygen-derived FRs and non-radical oxygen derivatives (in which V is involved) as well as the consequences of FR-mediated LPO (induced by this metal) together with the negative/ positive effects of LPO products. A brief description of the localization and function of some antioxidant enzymes and low-molecular-weight antioxidants, which are able to form complexes with V and play a crucial role in the metabolism of this element, is presented as well. The report also shows the OS historical background and OS markers (determined in animals under V treatment) on a timeline, collects data on interactions of V with one of the elements with antioxidant potential, and highlights the necessity and desirability of conducting studies of mutual interactions between V and antioxidant elements.

Vanadium in Biosphere and Its Role in Biological Processes

Ultra-trace elements or occasionally beneficial elements (OBE) are the new categories of minerals including vanadium (V). The importance of V is attributed due to its multifaceted biological roles, i.e., glucose and lipid metabolism as an insulin-mimetic, antilipemic and a potent stress alleviating agent in diabetes when vanadium is administered at lower doses. It competes with iron for transferrin (binding site for transportation) and with lactoferrin as it is secreted in milk also. The intracellular enzyme protein tyrosine phosphatase, causing the dephosphorylation at beta subunit of the insulin receptor, is inhibited by vanadium, thus facilitating the uptake of glucose inside the cell but only in the presence of insulin. Vanadium could be useful as a potential immune-stimulating agent and also as an antiinflammatory therapeutic metallodrug targeting various diseases. Physiological state and dose of vanadium compounds hold importance in causing toxicity also. Research has been carried out mostly on laboratory animals but evidence for vanadium importance as a therapeutic agent are available in humans and large animals also. This review examines the potential biochemical and molecular role, possible kinetics and distribution, essentiality, immunity, and toxicity-related study of vanadium in a biological system.

Urinary vanadium concentration in relation to premature rupture of membranes: A birth cohort study

Heavy metal exposure has been indicated to be linked with reproductive and developmental toxicity. However, human studies on the association between heavy metal exposure and premature rupture of membranes (PROM) are limited. Thus, we aimed to evaluate the associations between urinary metal concentrations in pregnant women and the risk of PROM. The study was conducted among 7290 pregnant women from an ongoing cohort study in China. Levels of urinary metals were determined using an inductively coupled plasma-mass spectrometry and adjusted by creatinine concentration (μg/g creatinine). Adjusted odds ratios (OR) and 95% confidence intervals (CI) for PROM and preterm PROM were estimated using logistic regression models. Among 12 urinary metals detected, vanadium (V) have shown stable positive associations with PROM and preterm PROM. With one unit increase in natural logarithmically transformed urinary V concentration, adjusted OR of 1.57 (95% CI: 1.47, 1.66) for PROM was observed. Compared with the lowest tertile of urinary V, we also observed positive associations between V levels and PROM (for the medium tertile, adjusted OR = 1.66, 95% CI: 1.34, 2.05; for the highest tertile, adjusted OR = 3.75, 95% CI: 3.09, 4.54). In addition, higher adjusted ORs for preterm PROM were observed (for the highest tertile, adjusted OR = 8.14, 95% CI: 4.55, 14.55). Further stratified analysis suggested the associations were more pronounced among women delivering male infants than those with female infants. Our present epidemiological study indicated that pregnant women exposure to higher level of V might lead to an increased risk of PROM.

Effects of oxidative stress induced by high dosage of dietary iron ingested on intestinal damage and caecal microbiota in Chinese Yellow broilers

The objective of this trial was to test the effects of oxidative stress induced by a high dosage of dietary iron on intestinal lesion and the microbiological compositions in caecum in Chinese Yellow broilers. A total of 450 1-day-old male chicks were randomly allotted into three groups. Supplemental iron (0, 700 and 1,400 mg/kg) was added to the basal diet resulting in three treatments containing 245, 908 and 1,651 mg/kg Fe (measured value) in diet respectively. Each treatment consisted of six replicate pens with 25 birds per pen. Jejunal enterocyte ultrastructure was observed by transmission electron microscopy. The results showed that a high dosage of dietary iron induced oxidative stress in broilers. Dilated endoplasmic reticulum (ER), autophagosome formation of jejunal enterocytes and decreased villi were caused by this oxidative stress. Compared to the control, concentration of the malondialdehyde (MDA) in jejunal mucosa in the 908 and 1,651 mg/kg Fe groups increased by 180% (p < .01) and 155% respectively (p < .01); activity of copper-zinc superoxide dismutase (Cu/ZnSOD) increased in jejunum (p < .01); and the concentration of plasma reduced glutathione (GSH) decreased by 34.9% (p < .01) in birds fed 1,651 mg/kg Fe. Gene expression of nuclear factor, erythroid-derived 2-like 2 (Nrf2) and zonula occludens-1 (ZO-1), in the higher dietary Fe groups was enhanced (p < .05). Species of microbial flora in caecum increased caused by oxidative stress. The PCR-DGGE (denaturing gradient gel electrophoresis) dendrograms revealed different microbiota (65% similarity coefficient) between the control and iron-supplemented groups (p < .05). These data suggest high dosage of iron supplement in feed diet can induce oxidative stress in Chinese Yellow broilers, and composition of microbiota in the caecum changed. It implied there should be no addition of excess iron when formulating diets in Chinese Yellow broilers.

Primary study on the toxic mechanism of vanadyl trehalose in Kunming mice

It has been shown that vanadyl trehalose could lower blood glucose but show mild toxicity to the stomach and intestine in diabetic Kunming mice. We analysed antioxidant levels, pro-inflammatory cytokine expression, apoptosis factors and intestinal microflora alteration to explore the mechanism of vanadyl trehalose toxicity in Kunming mice. The results revealed that oral administration of vanadyl trehalose at tested dose caused significant changes in oxidative stress factor (MDA levels elevated but SOD and T-AOC decreased), expression of inflammatory factor (IL-1β, COX-2, TNF-α and iNOS increased), and apoptosis factor (Bcl-2/Bax decreased and caspase-3 increased), and intestinal microflora dysbiosis (the number of Enterobacteriaceae and Enterococcus increased and Lactobacillus and Bifidobacterium decreased) relative to the control of Kunming mice. These results suggest that the toxic mechanisms of vanadyl trehalose on the stomach and intestine likely involve activation of the oxidative stress system, increased inflammatory response, promotion of apoptosis and the disruption of the normal intestinal microflora.

Vanadium toxicity in the thymic development

The purpose of this study was to define the toxic effects of vanadium on thymic development in broilers fed on diets supplemented with 0, 5, 15, 30, 45 and 60 mg/kg of vanadium for 42 days. We examined the changes of relative weigh, cell cycle phase, apoptotic cells, and protein expression of Bcl-2, Bax, and caspase-3 in the thymus by the methods of flow cytometry, TUNEL (terminal-deoxynucleotidyl transferase mediated nick end labeling) and immunohistochemistry. The results showed that dietary high vanadium (30 mg/kg, 45 mg/kg and 60 mg/kg) caused the toxic effects on thymic development, which was characterized by decreasing relative weigh, increasing G0/G1 phase (a prolonged nondividing state), reducing S phase (DNA replication) and proliferating index (PI), and increasing percentages of apoptotic thymocytes. Concurrently, the protein expression levels of Bax and caspase-3 were increased, and protein expression levels of Bcl-2 were decreased. The thymic development suppression caused by dietary high vanadium further leads to inhibitive effects on T lymphocyte maturity and activity, and cellular immune function. The above-mentioned results provide new evidences for further understanding the vanadium immunotoxicity. In contrast, dietary 5 mg/kg vanadium promoted the thymic development by increasing relative weigh, decreasing G0/G1 phase, increasing S phase and PI, and reducing percentages of apoptotic thymocytes when compared to the control group and high vanadium groups.

Monitoring impacts of air pollution: PIXE analysis and histopathological modalities in evaluating relative risks of elemental contamination

Environmental toxicants invariably affect all biological organisms resulting to sufferings ranging from subclinical to debilitating clinical conditions. This novel research aimed to determine the toxic burdens of increased environmental elements in some vital organs/tissues of the wild animals (starling, owl, crow and pigeon), exposed to air polluted environment were assessed using particle induced X-ray emission and histopathological approaches. The presence of significantly elevated amounts of elemental toxicants namely: Aluminum (Al), Chlorine (Cl), Iron (Fe), Potassium (K), Magnesium (Mg), Manganese (Mn), Silicon (Si) and Vanadium (V) from the skin, muscle, lungs, liver and kidney of sampled animals were in concurrence with the observed histopathological changes. The skin of sampled starling, owl, pigeon and crow spotlighted highly significant increase (P < 0.001) in Al, Cl, Mg and Si. Muscle samples with myodegenerative lesions and mineral depositions highlighted substantial augmentation (P < 0.001) in the amount of Al, Fe, Mn, Si and V. The lungs of starling, owl, and pigeon were severely intoxicated (P < 0.001) with increased amount of Al, Fe, K, Mn and Si producing pulmonary lesions of congestion, edema, pneumonitis and mineral debris depositions. Liver samples revealed that the sampled animals were laden with Cl, Fe, Mg, Mn and V with histopathological profound degenerative changes and hepatic necrosis. Kidney sections presented severe tubular degenerative and necrotic changes that may be attributed to increased amounts of Cl and Fe. These current findings implied that the environmental/elemental toxicants and the accompanying lesions that were discerned in the organs/tissues of sampled birds may as well be afflicting people living within the polluted area. Further assessment to more conclusively demonstrate correlations of current findings to those of the populace within the area is encouraged.

Magnesium can protect against vanadium-induced lipid peroxidation in the hepatic tissue

The protective effect of magnesium as magnesium sulfate (MS) on sodium-metavanadate- (SMV-) induced lipid peroxidation (LPO) under in vivo and in vitro conditions was studied. The 18-week SMV intoxication (Group II, 0.125 V_end/mL) enhanced spontaneous malondialdehyde (MDA) generation in rat liver, compared with the control (Group I) and MS-supplemented animals (Group III, 0.06 Mg_end/mL). Coadministration of SMV with MS (Group IV, SMV-MS) caused a return of the MDA level to the control value range. The effect seems to result from the Mg_end-independent action and its antagonistic interaction with V_end. The in vitro treatment of liver supernatants (LS) obtained from all the tested animals groups with selected exogenous concentrations of Fe_exg or V_exg exhibited enhanced MDA production, compared with spontaneously formed MDA. It also showed Mg_exg-stimulating effect on LPO (LS I, Group I) and revealed that the changes in the MDA generation in LS IV (Group IV) might have resulted from the synergistic interactions of V_end with Fe_exg and V_exg and from the antagonistic interactions of Mg_end with Fe_exg and V_exg. The findings allow a suggestion that adequate Mg intake for a specific period in the conditions of SMV exposure may prevent V-induced LPO in the liver.

Exploratory study using proton induced X-ray emission analysis and histopathological techniques to determine the toxic burden of environmental pollutants

The aim of this novel research was to determine the toxic burden of increased elements in water resources on the inhabitant wild animals (squirrels, turtles, bats), using particle induced x-ray emission (PIXE) and histopathological approaches. PIXE analysis of skin, muscle, lung, liver and kidney revealed significant increase in Al, Cl, Fe, Mg, Mn, Si and V. Moreover, data clearly reflect a significant (P < 0.001) deposition of toxic elements (Al, Cl, Fe and K) in the lung producing interstitial/proliferative pneumonitis, intra-alveolar hemorrhages, and thickening of alveolar capillary walls. The results obtained from the liver samples emphasized that majority of the animals were intoxicated with Cl, Mg, S, Si and V, which have produced profound deterioration and swelling of the hepatocytes. Likewise, histopathology of the kidney sections spotlighted severe nephritis and degenerative changes, which could be associated with the elevated amount of Al, Cl and Mg. This data undoubtedly provide relevant information on the heavy burden of toxic elements and their pathological outcomes in wild animals and highlight their potential risks for human exposure. Thus, the information provided is critical for developing effective strategies in dealing with health hazards associated with elemental exposures.

Effect of dietary vanadium on intestinal microbiota in broiler

The purpose of this 42-day study was to examine the effect of dietary vanadium on intestinal microorganism diversity in the duodenum, ileum, cecum, and rectum segments of broilers by the plate count and polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE). A total of 420 1-day-old avian broilers were divided into six groups and fed on a control diet or the same diet supplemented with vanadium at the doses of 5, 15, 30, 45, and 60 mg/kg in the form of ammonium metavanadate. In comparison with control group, the dietary vanadium at the doses of 45 and 60 mg/kg could decrease the counts of Bifidobacterium spp. in the intestinal tract at 21 and 42 days of age. With increasing level in dietary vanadium, the counts of Escherichia coli were significantly increased in the ileum, cecum, and rectum and were decreased in the duodenum at 21 and 42 days of age. However, the counts of Lactobacilli were decreased in the cecum and rectum and increased in the ileum of 45 and 60 mg/kg groups. The colonization of these three bacteria could be affected by dietary vanadium. DGGE analysis showed that the number of bands in duodenum, ileum, cecum, and rectum were obviously decreased in the 30, 45, and 60 mg/kg groups at 21 and 42 days of age. In conclusion, the dietary vanadium in excess of 30 mg/kg could alter the amount and diversity of intestinal bacteria in broilers, implying that the structure and initial balance in the intestinal microbiota were disrupted.

Changes of IgA+ cells and cytokines in the cecal tonsil of broilers fed on diets supplemented with vanadium

The cecal tonsil of broiler is known as a secondary lymphoid tissue, which is involved in antigen-specific humoral immune responses. The purpose of this study was to investigate the effects of dietary vanadium on the tissue distribution and quantity of immunoglobulin A-positive (IgA(+)) cell in the cecal tonsil by immunohistochemistry. Simultaneously, the changes in interleukin-6 (IL-6), interleukin-10 (IL-10), interferon gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) contents in the cecal tonsil were also quantified by enzyme-linked immunosorbent assay (ELISA). A total of 420 one-day-old avian broilers were divided into six groups and fed on a corn-soybean basal diet (control diet) or the same diet supplemented respectively with 5, 15, 30, 45, and 60 mg/kg of vanadium in the form of ammonium metavanadate for 42 days. The results showed that the population of the IgA(+) cells in the cecal tonsil were significantly lower (p < 0.05 or p < 0.01) in the 45 and 60 mg/kg groups than that in the control group. Meanwhile, IL-10, IFN-γ and TNF-α contents in the cecal tonsil were significantly decreased (p < 0.05 or p < 0.01) in the 30, 45 and 60 mg/kg groups in comparison with those of the control group. However, IL-6 content in the cecal tonsil was only decreased (p < 0.05 or p < 0.01) in 60 mg/kg at 14 and 28 days of age. In conclusion, dietary vanadium in excess of 30 mg/kg reduced the numbers of the IgA(+) cells and changed the contents of the abovementioned cytokines in the cecal tonsil, which may finally impact the function of local mucosal humoral immunity in broilers.

Dietary vanadium induces lymphocyte apoptosis in the bursa of Fabricius of broilers

The purpose of this 42-day study was to investigate the apoptosis in the bursa of Fabricius induced by different levels of dietary vanadium. A total of 420 1-day-old avian broilers were divided into 6 groups in which there were 7 replicates in each group and 10 broilers in each replicate and fed on a corn-soybean basal diet as control diet (vanadium 0.073 mg/kg) or the same diet amended to contain 5, 15, 30, 45, and 60 mg/kg vanadium supplied as ammonium metavanadate (NH(4)VO(3)). Ultrastructurally, mitochondrial injury and increased numbers of apoptotic cells with condensed nuclei were observed in the 30, 45, and 60 mg/kg groups. As measured by flow cytometry, the percentages of apoptotic lymphocytes were significantly increased in the 15-, 30-, 45-, and 60-mg/kg groups when compared with those of control group. Meanwhile, the terminal deoxynucleotidyl transferase 2'-deoxyuridine 5'-triphosphate nick end-labeling assay showed that there were increased numbers of apoptotic cells in the 30-, 45-, and 60-mg/kg groups. Immunohistochemical tests showed increased numbers of positive cells under Bax and caspase-3 protein detection and decreased Bcl-2 protein in the 15-, 30-, 45-, and 60-mg/kg groups. The vanadium content of the bursa was found to be significantly increased in the 30-, 45-, and 60-mg/kg groups. These results suggested that dietary vanadium in excess of 15 mg/kg could cause lymphocyte apoptosis in the bursa of Fabricius and impact humoral immunity in broilers. Lymphocyte apoptosis in the bursa induced by high levels of dietary vanadium is associated with mitochondrial injury and changes in levels of apoptogenic proteins, such as Bcl-2, Bax, and caspase-3.