The Inflammatory Potential of Dietary Manganese in a Cohort of Elderly Men

The protective role of sesame oil against Parkinson's-like disease induced by manganese in rats

Chronic exposure to manganese (Mn) results in motor dysfunction, biochemical and pathological alterations in the brain. Oxidative stress, inflammation, and dysfunction of dopaminergic and GABAergic systems stimulate activating transcription factor-6 (ATF-6) and protein kinase RNA-like ER kinase (PERK) leading to apoptosis. This study aimed to investigate the protective effect of sesame oil (SO) against Mn-induced neurotoxicity. Rats received 25 mg/kg MnCl2 and were concomitantly treated with 2.5, 5, or 8 ml/kg of SO for 5 weeks. Mn-induced motor dysfunction was indicated by significant decreases in the time taken by rats to fall during the rotarod test and in the number of movements observed during the open field test. Also, Mn resulted in neuronal degeneration as observed by histological staining. The striatal levels of lipid peroxides and reduced glutathione (oxidative stress markers), interleukin-6 and tumor necrosis factor-α (inflammatory markers) were significantly elevated. Mn significantly reduced the levels of dopamine and Bcl-2, while GABA, PERK, ATF-6, Bax, and caspase-3 were increased. Interestingly, all SO doses, especially at 8 ml/kg, significantly improved locomotor activity, biochemical deviations and reduced neuronal degeneration. In conclusion, SO may provide potential therapeutic benefits in enhancing motor performance and promoting neuronal survival in individuals highly exposed to Mn.

Activation of ERK/NF-kB Pathways Contributes to the Inflammatory Response in Epithelial Cells and Macrophages Following Manganese Exposure

Different types of metals, including manganese (Mn), are constantly encountered in various environmental matrices due to natural and anthropogenic activities. They induce a sustained inflammatory response in various organs, which is considered to be an important priming event in the pathogenesis of several diseases. Mn-induced neuroinflammation and subsequent neurodegeneration are well recognized. However, emerging data suggest that occupationally and environmentally relevant levels may affect various organs, including the lungs. Therefore, the present study was carried out to investigate the effects of Mn (as Mn2+) exposure on the inflammatory response in human normal bronchial (BEAS-2B) and adenocarcinoma alveolar basal (A549) epithelial cells, as well as in murine macrophages (J774). Mn2+ exposure significantly induced mRNA and protein expression of various pro-inflammatory mediators (cytokines and chemokines) in all cells compared to corresponding vehicle controls. Furthermore, Mn2+ treatment also led to increased phosphorylation of extracellular-signal-regulated kinase (ERK)1/2 and nuclear factor-kappa B (NF-kB) p65 in both epithelial cells and macrophages. As expected, cells treated with inhibitors of ERK1/2 (PD98059) and NF-kB p65 (IMD0354) effectively mitigated the expression of various pro-inflammatory mediators induced by Mn2+, suggesting that ERK/NF-kB pathways have a critical role in the Mn2+-induced inflammatory response. Further, in vivo studies are required to confirm these in vitro findings to support clinical translation.

Protective effects of blueberries on vascular function: A narrative review of preclinical and clinical evidence

Blueberries are rich in nutrients and (poly)phenols, popular with consumers, and a major agricultural crop with year-round availability supporting their use in food-based strategies to promote human health. Accumulating evidence indicates blueberry consumption has protective effects on cardiovascular health including vascular dysfunction (i.e., endothelial dysfunction and arterial stiffening). This narrative review synthesizes evidence on blueberries and vascular function and provides insight into underlying mechanisms with a focus on oxidative stress, inflammation, and gut microbiota. Evidence from animal studies supports beneficial impacts on vascular function. Human studies indicate acute and chronic blueberry consumption can improve endothelial function in healthy and at-risk populations and may modulate arterial stiffness, but that evidence is less certain. Results from cell, animal, and human studies suggest blueberry consumption improves vascular function through improving nitric oxide bioavailability, oxidative stress, and inflammation. Limited data in animals suggest the gut microbiome mediates beneficial effects of blueberries on vascular function; however, there is a paucity of studies evaluating the gut microbiome in humans. Translational evidence indicates anthocyanin metabolites mediate effects of blueberries on endothelial function, though this does not exclude potential synergistic and/or additive effects of other blueberry components. Further research is needed to establish the clinical efficacy of blueberries to improve vascular function in diverse human populations in a manner that provides mechanistic information. Translation of clinical research to the community/public should consider feasibility, social determinants of health, culture, community needs, assets, and desires, barriers, and drivers to consumption, among other factors to establish real-world impacts of blueberry consumption.

Nutrition, DNA methylation and obesity across life stages and generations

Obesity is a complex multifactorial condition that often manifests in early life with a lifelong burden on metabolic health. Diet, including pre-pregnancy maternal diet, in utero nutrition and dietary patterns in early and late life, can shape obesity development. Growing evidence suggests that epigenetic modifications, specifically DNA methylation, might mediate or accompany these effects across life stages and generations. By reviewing human observational and intervention studies conducted over the past 10 years, this work provides a comprehensive overview of the evidence linking nutrition to DNA methylation and its association with obesity across different age periods, spanning from preconception to adulthood and identify future research directions in the field.

Association of blood manganese concentrations with 24-h based brachial and central blood pressure, and pulse-wave velocity

Potential environmental determinants of BP and hypertension in older adults are far less known than their lifestyle risk factors. Manganese (Mn) is an essential element for life that may induce changes in blood pressure (BP), but the direction of the association is unclear. We aimed to examine the association of blood manganese (bMn) with 24-h-based brachial, central BP (cBP), and pulse-wave velocity (PWV). With this purpose, we analyzed data from 1009 community-living adults aged >65 years without BP medication. bMn was measured using inductively-coupled plasma-mass spectrometry and 24-h BP with validated devices. The association of bMn (median: 6.77 μg/L; IQR: 5.59-8.27) with daytime brachial and central systolic (SBP) and with diastolic BP (DBP) was non-linear, with BP increases up to around the median of Mn and then stabilization or slight rightward decrease. Mean BP differences (95% confidence interval) comparing Mn Q2 to Q5 (vs Q1 quintile) for brachial daytime SBP were 2.56 (0.22; 4.90), 3.59 (1.22; 5.96), 3.14 (0.77; 5.51) and 1.72 (-0.68; 4.11) mmHg, respectively; and 2.22 (0.70, 3.73), 2.55 (1.01, 4.08), 2.45 (0.91; 3.98), and 1.68 (0.13; 3.24), respectively, for DBP. Daytime central-pressures showed a similar dose-response relationship with bMn as daytime brachial-pressures. The association with nighttime BP was linearly positive for brachial BPs, and only increasing for Q5 for cBP. Regarding PWV, a tendency to significant linear increase along bMn levels was observed (p-trend = 0.042). The present findings extend the scarce evidence on the association between Mn and brachial BP to 2 other vascular parameters, suggesting Mn levels as a candidate risk factor for increasing levels of both brachial and cBPs in older adults, yet further research is needed with larger cohort studies in adults at all age ranges.

Profiling of Circulatory Elements Reveals Alteration of Essential and Toxic Trace Metals in Crohn's Disease

The status of essential and toxic trace metals in the blood of Crohn's disease (CD) patients is unexplained. This study aimed to provide the first elemental profiling of the most recognized essential elements (Mn, Cu, Zn, Se) and selected toxic trace elements (As, Cd, Pb, and U) in sera and cell lysate (CL) samples of CD patients (n = 84). The results were compared with sex- and age-matched samples from the control group (CG). CD sera contained significantly higher levels of Mn, As, Cd, Pb, and U than did CG sera. An identical pattern, with the added inclusion of Cu (also higher in CD patients than in the CG), was obtained for CL samples. However, the most important finding was hypermanganesemia, which indicates that Mn could act as a toxic trace metal in CD. As, Cd, and U were the most significant toxic elements that showed antagonistic effects on the extrusion of essential Mn and Cu. Circulatory system screening markers for CD are hereby proposed (Mn/Cu, Mn/As, and Mn/Pb ratios). These three metal ratios were strongly and significantly correlated with F-Calprotectin levels, and deserve consideration as new markers of CD. The target metals and metal ratios should be taken into consideration as novel initiating and/or modifying factors for CD.

Genetics and Epigenetics of Manganese Toxicity

PURPOSE OF REVIEW

At elevated levels, the essential element manganese (Mn) is neurotoxic and increasing evidence indicates that environmental Mn exposure early in life negatively affects neurodevelopment. In this review, we describe how underlying genetics may confer susceptibility to elevated Mn concentrations and how the epigenetic effects of Mn may explain the association between Mn exposure early in life and its toxic effects later in life.

RECENT FINDINGS

Common polymorphisms in the Mn transporter genes SLC30A10 and SLC39A8 seem to have a large impact on intracellular Mn levels and, in turn, neurotoxicity. Genetic variation in iron regulatory genes may to lesser extent also influence Mn levels and toxicity. Recent studies on Mn and epigenetic mechanisms indicate that Mn-related changes in DNA methylation occur early in life. One human and two animal studies found persistent changes from in utero exposure to Mn but whether these changes have functional effects remains unknown. Genetics seems to play a major role in susceptibility to Mn toxicity and should therefore be considered in risk assessment. Mn appears to interfere with epigenetic processes, potentially leading to persistent changes in developmental programming, which warrants further study.

Celecoxib prevents tumor necrosis factor-α (TNF-α)-induced cellular senescence in human chondrocytes

Osteoarthritis (OA) is a cartilage degenerative disease commonly observed in the elderly population and significantly impacts the normal life of OA patients. It has been reported that the development of pathological cell senescence in chondrocytes is involved in the pathogenesis of OA. Celecoxib is a common non-steroidal anti-inflammatory drug, and it has been recently reported to exert therapeutic effects on OA. However, its underlying mechanism is still unclear. The present study intends to explore its mechanism and provide fundamental evidence for the application of Celecoxib in the treatment of clinical OA. Tumor necrosis factor-α (TNF-α) was utilized to establish an in vitro model of chondrocytes senescence. The elevated reactive oxygen species (ROS) generation, increased cell cycle arrest in G0/G1 phase, reduced telomerase activity, and upregulated senescence-associatedβ-galactosidase (SA-β-Gal) staining were all observed in TNF-α-treated chondrocytes, which were then dramatically reversed by 10 and 20 μM Celecoxib. In addition, the upregulated DNA damage biomarkers, p-ATM, and p-CHK2, observed in TNF-α-treated chondrocytes were significantly downregulated by 10 and 20 μM Celecoxib. Lastly, the expression level of p21 and p53 was greatly elevated in chondrocytes by stimulation with TNF-α which was then pronouncedly repressed by treatment with Celecoxib. Taken together, our data reveal that Celecoxib ameliorated TNF-α-induced cellular senescence in human chondrocytes.

Sodium P-aminosalicylic Acid Attenuates Manganese-Induced Neuroinflammation in BV2 Microglia by Modulating NF-κB Pathway

Exposure to high levels of manganese (Mn) leads to brain Mn accumulation, and a disease referred to as manganism. Activation of microglia plays an important role in Mn-induced neuroinflammation. Sodium p-aminosalicylic acid (PAS-Na) is a non-steroidal anti-inflammatory drug that inhibits Mn-induced neuroinflammation. The aim of the current study was to explore the role of NF-κB in the protective mechanism of PAS-Na on Mn-induced neuroinflammation in BV2 microglial experimental model. We treated BV2 microglia with 200 μM Mn for 24 h followed by 48 h treatment with graded concentrations of PAS-Na, using an NF-kB inhibitor, JSH-23, as a positive control. MTT results established that 200 and 400 μM PAS-Na treatment increased the Mn-induced cell viability reduction. NF-κB (P65) mRNA expression and the phosphorylation of p65 were increased in Mn-treated BV2 cell, and suppressed by PAS-Na, analogous to the effect of JSH-23 pretreatment. Furthermore, PAS-Na significantly reduced the contents of the inflammatory cytokine TNF-α and IL-1β, both of which were increased by Mn treatment. The current results show that PAS-Na attenuated Mn-induced inflammation by abrogating the activation of the NF-κB signaling pathways and reduced the release of pro-inflammatory cytokines.

Environmental neurotoxicants and inflammasome activation in Parkinson's disease - A focus on the gut-brain axis

Inflammasomes are multi-protein complexes expressed in immune cells that function as intracellular sensors of environmental, metabolic and cellular stress. Inflammasome activation in the brain, has been shown to drive neuropathology and disease progression by multiple mechanisms, making it one of the most attractive therapeutic targets for disease modification in Parkinson's Disease (PD). Extensive inflammasome activation is evident in the brains of people with PD at the sites of dopaminergic degeneration and synuclein aggregation. While substantial progress has been made on validating inflammasome activation as a therapeutic target for PD, the mechanisms by which inflammasome activation is triggered and sustained over the disease course remain poorly understood. A growing body of evidence point to environmental and occupational chemical exposures as possible triggers of inflammasome activation in PD. The involvement of the gastrointestinal system and gut microbiota in PD pathophysiology is beginning to be elucidated, especially the profound link between gut dysbiosis and immune activation. While large cohort studies confirmed specific changes in the gut microbiota in PD patients compared to age-matched healthy controls, recent research suggest that synuclein pathology could be initiated in the gastrointestinal tract. In this review, we present a summarized perspective on current understanding on inflammasome activation and the gut-brain-axis link during PD pathophysiology. We discuss multiple environmental toxicants that are implicated as the etiological agents in causing idiopathic PD and their mechanistic underpinnings during neuroinflammatory events. We additionally present future directions that needs to address the research questions related to the gut-microbiome-brain mechanisms in PD.

Dietary Micronutrients from Zygote to Senility: Updated Review of Minerals' Role and Orchestration in Human Nutrition throughout Life Cycle with Sex Differences

Micronutrients such as selenium, fluoride, zinc, iron, and manganese are minerals that are crucial for many body homeostatic processes supplied at low levels. The importance of these micronutrients starts early in the human life cycle and continues across its different stages. Several studies have emphasized the critical role of a well-balanced micronutrient intake. However, the majority of studies looked into or examined such issues in relation to a specific element or life stage, with the majority merely reporting the effect of either excess or deficiency. Herein, in this review, we will look in depth at the orchestration of the main element requirements across the human life cycle beginning from fertility and pregnancy, passing through infancy, childhood, adolescence, and reaching adulthood and senility, with insight on the interactions among them and underlying action mechanisms. Emphasis is given towards approaches to the role of the different minerals in the life cycle, associated symptoms for under- or overdoses, and typical management for each element, with future perspectives. The effect of sex is also discussed for each micronutrient for each life stage as literature suffice to highlight the different daily requirements and or effects.

Estimating daily intakes of manganese due to breast milk, infant formulas, or young child nutritional beverages in the United States and France: Comparison to sufficiency and toxicity thresholds

BACKGROUND

Although manganese (Mn) is an essential nutrient, recent research has revealed that excess Mn in early childhood may have adverse effects on neurodevelopment.

METHODS

We estimated daily total Mn intake due to breast milk at average body weights by reviewing reported concentrations of breast milk Mn and measurements of body weight and breast milk intake at 3 weeks, 4.25 months, 7 months, and 18 months. We compared these figures to the Mn content measured in 44 infant, follow-up, and toddler formulas purchased in the United States and France. We calculated Mn content of formula products made with ultra-trace elemental analysis grade water (0 μg Mn/L) and with water containing 250 μg Mn/L, a concentration which is relatively high but less than the World Health Organization Health-based value of 400 μg Mn/L or the United States Environmental Protection Agency Health Advisory of 350 μg Mn/L.

RESULTS

Estimated mean daily Mn intake from breast milk ranged from 1.2 μg Mn/kg/day (3 weeks) to 0.16 μg Mn/kg/day (18 months), with the highest intakes at the youngest age stage we considered, 3 weeks. Estimated daily Mn intake from formula products reconstituted with 0 μg Mn/L water ranged from 130 μg Mn/kg/day (3 weeks) to 4.8 μg Mn/kg/day (18 months) with the highest intakes at 3 weeks. Formula products provided 28-520 times greater than the mean daily intake of Mn from breast milk for the 4 age stages that we considered. Estimated daily Mn intake from formula products reconstituted with water containing 250 μg Mn/L ranged from 12 μg Mn/kg/day to 170 μg Mn/kg/day, which exceeds the United States Environmental Protection Agency Reference Dose of 140 μg Mn/kg/day for adults.

CONCLUSIONS

Mn deficiency is highly unlikely with exclusive breast milk or infant formula feeding, but established tolerable daily intake levels for Mn may be surpassed by some of these products when following labeled instructions.

Epigenetic signatures underlying inflammation: an interplay of nutrition, physical activity, metabolic diseases, and environmental factors for personalized nutrition

Aim and objective

Emerging translational evidence suggests that epigenetic alterations (DNA methylation, miRNA expression, and histone modifications) occur after external stimuli and may contribute to exacerbated inflammation and the risk of suffering several diseases including diabetes, cardiovascular diseases, cancer, and neurological disorders. This review summarizes the current knowledge about the harmful effects of high-fat/high-sugar diets, micronutrient deficiencies (folate, manganese, and carotenoids), obesity and associated complications, bacterial/viral infections, smoking, excessive alcohol consumption, sleep deprivation, chronic stress, air pollution, and chemical exposure on inflammation through epigenetic mechanisms. Additionally, the epigenetic phenomena underlying the anti-inflammatory potential of caloric restriction, n-3 PUFA, Mediterranean diet, vitamin D, zinc, polyphenols (i.e., resveratrol, gallic acid, epicatechin, luteolin, curcumin), and the role of systematic exercise are discussed.

Methods

Original and review articles encompassing epigenetics and inflammation were screened from major databases (including PubMed, Medline, Science Direct, Scopus, etc.) and analyzed for the writing of the review paper.

Conclusion

Although caution should be exercised, research on epigenetic mechanisms is contributing to understand pathological processes involving inflammatory responses, the prediction of disease risk based on the epigenotype, as well as the putative design of therapeutic interventions targeting the epigenome.

Individual species and cumulative mixture relationships of 24-hour urine metal concentrations with DNA methylation age variables in older men

BACKGROUND

Globally, toxic metal exposures are a well-recognized risk factor for many adverse health outcomes. DNA methylation-based measures of biological aging are predictive of disease, but have poorly understood relationships with metal exposures.

OBJECTIVE

We performed a pilot study examining the relationships of 24-h urine metal concentrations with three novel DNA methylation-based measures of biological aging: DNAmAge, GrimAge, and PhenoAge.

METHODS

We utilized a previously established urine panel of five common metals [arsenic (As), cadmium (Cd), lead (Pb), manganese (Mn), and mercury (Hg)] found in a subset of the elderly US Veterans Affairs Normative Aging Study cohort (N = 48). The measures of DNA methylation-based biological age were calculated using CpG sites on the Illumina HumanMethylation450 BeadChip. Bayesian Kernel Machine Regression (BKMR) was used to determine metals most important to the aging outcomes and the relationship of the cumulative metal mixture with the outcomes. Individual relationships of important metals with the biological aging outcomes were modeled using fully-adjusted linear models controlling for chronological age, renal function, and lifestyle/environmental factors.

RESULTS

Mn was selected as important to PhenoAge. A 1 ng/mL increase in urine Mn was associated with a 9.93-year increase in PhenoAge (95%CI: 1.24, 18.61, p = 0.03). The cumulative urine metal mixture was associated with increases in PhenoAge. Compared to a model where each metal in the mixture is set to its 50th percentile value, every one-unit increase of the cumulative mixture with each metal at its 70th percentile was associated with a 2.53-year increase in PhenoAge (95%CI: 0.10, 4.96, P<0.05).

CONCLUSION

Our results add novel evidence that metals detected in urine are associated with increases in biological aging and suggest that these DNA methylation-based measures may be useful for identifying individuals at-risk for diseases related to toxic metal exposures. Further research is necessary to confirm these findings more broadly.

Dietary Manganese, Plasma Markers of Inflammation, and the Development of Type 2 Diabetes in Postmenopausal Women: Findings From the Women's Health Initiative

OBJECTIVE

To examine the association between manganese intake and the risk of type 2 diabetes in postmenopausal women and determine whether this association is mediated by circulating markers of inflammation.

RESEARCH DESIGN AND METHODS

We included 84,285 postmenopausal women without a history of diabetes from the national Women's Health Initiative Observational Study (WHI-OS). Replication analysis was then conducted among 62,338 women who participated in the WHI-Clinical Trial (WHI-CT). Additionally, data from a case-control study of 3,749 women nested in the WHI-OS with information on biomarkers of inflammation and endothelial dysfunction were examined using mediation analysis to determine the relative contributions of these known biomarkers by which manganese affects type 2 diabetes risk.

RESULTS

Compared with the lowest quintile of energy-adjusted dietary manganese, WHI-OS participants in the highest quintile had a 30% lower risk of type 2 diabetes (hazard ratio [HR] 0.70 [95% CI 0.65, 0.76]). A consistent association was also confirmed in the WHI-CT (HR 0.79 [95% CI 0.73, 0.85]). In the nested case-control study, higher energy-adjusted dietary manganese was associated with lower circulating levels of inflammatory biomarkers that significantly mediated the association between dietary manganese and type 2 diabetes risk. Specifically, 19% and 12% of type 2 diabetes risk due to manganese were mediated through interleukin 6 and hs-CRP, respectively.

CONCLUSIONS

Higher intake of manganese was directly associated with a lower type 2 diabetes risk independent of known risk factors. This association may be partially mediated by inflammatory biomarkers.

Adjuvant Therapies in Diabetic Retinopathy as an Early Approach to Delay Its Progression: The Importance of Oxidative Stress and Inflammation

Diabetes mellitus (DM) is a progressive disease induced by a sustained state of chronic hyperglycemia that can lead to several complications targeting highly metabolic cells. Diabetic retinopathy (DR) is a multifactorial microvascular complication of DM, with high prevalence, which can ultimately lead to visual impairment. The genesis of DR involves a complex variety of pathways such as oxidative stress, inflammation, apoptosis, neurodegeneration, angiogenesis, lipid peroxidation, and endoplasmic reticulum (ER) stress, each possessing potential therapeutic biomarkers. A specific treatment has yet to be developed for early stages of DR since no management is given other than glycemic control until the proliferative stage develops, offering a poor visual prognosis to the patient. In this narrative review article, we evaluate different dietary regimens, such as the Mediterranean diet, Dietary Pattern to Stop Hypertension (DASH) and their functional foods, and low-calorie diets (LCDs). Nutraceuticals have also been assessed in DR on account of their antioxidant, anti-inflammatory, and antiangiogenic properties, which may have an important impact on the physiopathology of DR. These nutraceuticals have shown to lower reactive oxygen species (ROS), important inflammatory factors, cytokines, and endothelial damage biomarkers either as monotherapies or combined therapies or concomitantly with established diabetes management or nonconventional adjuvant drugs like topical nonsteroidal anti-inflammatory drugs (NSAIDs).

Ambulatory Blood Pressure in Relation to Plasma and Urinary Manganese

The association of blood pressure (BP) with manganese-an essential trace element required for human health-remains poorly studied. In 734 randomly recruited Swiss participants (mean age, 47.5 years; 51.4% women), we related ambulatory BP to 2 biomarkers, plasma manganese (pMn) and the urinary manganese (uMn) excretion. To allow for diurnal variation, we assessed BP and uMn over 24 hours and during wakefulness and sleep, using split urine samples. Twenty-four-hour, daytime, and nighttime systolic/diastolic BPs averaged 119.8/78.1, 123.8/81.2, and 107.0/68.3 mm Hg; the corresponding median uMn were 199.5, 83.0, and 51.5 μmol and median pMn, 0.52 μg/L. In analyses dichotomized by the median of the biomarkers, greater pMn was associated with higher 24-hour systolic/diastolic BP (+4.1/+2.3 mm Hg; P≤0.0003), greater daytime uMn with lower daytime BP (-3.5/-1.9 mm Hg; P≤0.0067), and greater nighttime uMn with higher nighttime BP (+2.9/+1.2 mm Hg; P≤0.046). In multivariable-adjusted analyses, significance (P≤0.030) was retained for the positive association of 24-hour and daytime diastolic BP with pMn and for systolic BP in relation to uMn at night. The association sizes for a 2-fold increment in the biomarkers amounting to 0.77 mm Hg (95% CI, 0.08-1.47 mm Hg), 0.97 (CI, 0.20-1.76) and 1.33 (CI, 0.20-2.50 mm Hg), respectively. In conclusion, there were positive associations between diastolic BP and pMn over 24 hours and during daytime and between systolic BP and uMn at night.

Manganese is associated with increased plasma interleukin-1β during pregnancy, within a mixtures analysis framework of urinary trace metals

Exposure to trace metals may impact reproductive health outcomes through perturbations in maternal immune signaling molecules. We conducted a cross-sectional study of 390 pregnant women from the LIFECODES birth cohort and investigated the associations between 17 urinary metals and five immune biomarkers measured in the 3rd trimester (median 26 weeks gestation). We used linear regression to estimate pair-wise associations and applied elastic net and Bayesian kernel machine regression to identify important contributing exposures analytes as well as non-linear effects. Maternal urinary manganese, nickel, and barium were positively associated with maternal plasma interleukin-1β (IL-1β). Elastic net and Bayesian kernel machine regression identified manganese as the dominant trace metal in association with IL-1β. An interquartile range difference in manganese (0.6 μg/L) was associated with a 29 % increase in IL-1β (95 % CI: 12.4-48.2). In conclusion, trace metal exposures were associated with biomarkers of immune perturbations, and this warrants further investigation.

Inflammasomes: An Emerging Mechanism Translating Environmental Toxicant Exposure Into Neuroinflammation in Parkinson's Disease

Evidence indicates that complex gene-environment interactions underlie the incidence and progression of Parkinson's disease (PD). Neuroinflammation is a well-characterized feature of PD widely believed to exacerbate the neurodegenerative process. Environmental toxicants associated with PD, such as pesticides and heavy metals, can cause cellular damage and stress potentially triggering an inflammatory response. Toxicant exposure can cause stress and damage to cells by impairing mitochondrial function, deregulating lysosomal function, and enhancing the spread of misfolded proteins. These stress-associated mechanisms produce sterile triggers such as reactive oxygen species (ROS) along with a variety of proteinaceous insults that are well documented in PD. These associations provide a compelling rationale for analysis of sterile inflammatory mechanisms that may link environmental exposure to neuroinflammation and PD progression. Intracellular inflammasomes are cytosolic assemblies of proteins that contain pattern recognition receptors, and a growing body of evidence implicates the association between inflammasome activation and neurodegenerative disease. Characterization of how inflammasomes may function in PD is a high priority because the majority of PD cases are sporadic, supporting the widely held belief that environmental exposure is a major factor in disease initiation and progression. Inflammasomes may represent a common mechanism that helps to explain the strong association between exposure and PD by mechanistically linking environmental toxicant-driven cellular stress with neuroinflammation and ultimately cell death.