The potential of proteomics for providing new insights into environmental impacts on human health

'Omics' and endocrine-disrupting chemicals - new paths forward

The emerging field of omics - large-scale data-rich biological measurements of the genome - provides new opportunities to advance and strengthen research into endocrine-disrupting chemicals (EDCs). Although some EDCs have been associated with adverse health effects in humans, our understanding of their impact remains incomplete. Progress in the field has been primarily limited by our inability to adequately estimate and characterize exposure and identify sensitive and measurable outcomes during windows of vulnerability. Evolving omics technologies in genomics, epigenomics and mitochondriomics have the potential to generate data that enhance exposure assessment to include the exposome - the totality of the lifetime exposure burden - and provide biology-based estimates of individual risks. Applying omics technologies to expand our knowledge of individual risk and susceptibility will augment biological data in the prediction of variability and response to disease, thereby further advancing EDC research. Together, refined exposure characterization and enhanced disease-risk prediction will help to bridge crucial gaps in EDC research and create opportunities to move the field towards a new vision - precision public health.

Functional annotation of proteomic data from chicken heterophils and macrophages induced by carbon nanotube exposure

With the expanding applications of carbon nanotubes (CNT) in biomedicine and agriculture, questions about the toxicity and biocompatibility of CNT in humans and domestic animals are becoming matters of serious concern. This study used proteomic methods to profile gene expression in chicken macrophages and heterophils in response to CNT exposure. Two-dimensional gel electrophoresis identified 12 proteins in macrophages and 15 in heterophils, with differential expression patterns in response to CNT co-incubation (0, 1, 10, and 100 μg/mL of CNT for 6 h) (p < 0.05). Gene ontology analysis showed that most of the differentially expressed proteins are associated with protein interactions, cellular metabolic processes, and cell mobility, suggesting activation of innate immune functions. Western blot analysis with heat shock protein 70, high mobility group protein, and peptidylprolyl isomerase A confirmed the alterations of the profiled proteins. The functional annotations were further confirmed by effective cell migration, promoted interleukin-1β secretion, and more cell death in both macrophages and heterophils exposed to CNT (p < 0.05). In conclusion, results of this study suggest that CNT exposure affects protein expression, leading to activation of macrophages and heterophils, resulting in altered cytoskeleton remodeling, cell migration, and cytokine production, and thereby mediates tissue immune responses.

Recent progress and perspectives on the toxicity of carbon nanotubes at organism, organ, cell, and biomacromolecule levels

A wide application of carbon nanotubes (CNTs) is on the way owing to their unique structural, optical, mechanical and electronic properties, high specific surface area, and facile functionalization. As a result, human beings will inevitably be exposed to CNTs, especially when the tubes are utilized as diagnostic and therapeutic tools to better understand, detect, and treat human diseases. Therefore the new subject of nanotoxicology, which is the study of the toxicity of nanomaterials, is now gaining public concern. This review provides an overview and comments on recent advances (mostly within the last 3 years) in the toxicology of CNTs, including their toxicity targeted to cells, organs, tissues and the whole organism, including mammals and other species (e.g. aquatic species, plants, and bacteria). Not only these traditional subjects of toxicological study but the interaction of CNTs and biomacromolecules is also covered so that the mechanism of their toxicity may be understood and their undesirable properties are more likely to be avoided.

Proteomic responses of blue mussel (Mytilus) congeners to temperature acclimation

The ability to acclimate to variable environmental conditions affects the biogeographic range of species, their success at colonizing new habitats, and their likelihood of surviving rapid anthropogenic climate change. Here we compared responses to temperature acclimation (4 weeks at 7, 13 and 19°C) in gill tissue of the warm-adapted intertidal blue mussel Mytilus galloprovincialis, an invasive species in the northeastern Pacific, and the cold-adapted M. trossulus, the native congener in the region, to better understand the physiological differences underlying the ongoing competition. Using two-dimensional gel electrophoresis and tandem mass spectrometry, we showed that warm acclimation caused changes in cytoskeletal composition and proteins of energy metabolism in both species, consistent with increasing rates of filtration and respiration due to increased ciliary activity. During cold acclimation, changes in cytoskeletal proteins were accompanied by increasing abundances of oxidative stress proteins and molecular chaperones, possibly because of the increased production of aldehydes as indicated by the upregulation of aldehyde dehydrogenase. The cold-adapted M. trossulus showed increased abundances of molecular chaperones at 19°C, but M. galloprovincialis did not, suggesting that the two species differ in their long-term upper thermal limits. In contrast, the warm-adapted M. galloprovincialis showed a stronger response to cold acclimation than M. trossulus, including changes in abundance in more proteins and differing protein expression profiles between 7 and 13°C, a pattern absent in M. trossulus. In general, increasing levels of oxidative stress proteins inversely correlate with modifications in Krebs cycle and electron transport chain proteins, indicating a trade-off between oxidative stress resistance and energy production. Overall, our results help explain why M. galloprovincialis has replaced M. trossulus in southern California over the last century, but also suggest that M. trossulus may maintain a competitive advantage at colder temperatures. Anthropogenic global warming may reinforce the advantage M. galloprovincialis has over M. trossulus in the warmer parts of the latter’s historical range.

Feasibility of biomarker studies for engineered nanoparticles: what can be learned from air pollution research

OBJECTIVE

Occupational exposure to engineered nanoparticles (NP) may pose health risks to the workers. This article is to discuss the feasibility of identifying biomarkers that are associated with NP exposure.

METHODS

Scientific literature on the adverse health effects of ambient ultrafine particles (UFP) and NP was reviewed to discuss the feasibility of conducting biomarker studies to identify NP-induced early biological changes.

RESULTS

Various approaches for biomarker studies have been identified, including potential injury pathways that need to be considered and the methodologies that may be used for such studies.

CONCLUSIONS

Although NP may have novel mechanisms of injury, much can be learned from our experience in studying UFP. Oxidative stress-related pathways can be an important consideration for identifying NP-associated biomarkers, and one of the most effective approaches for such studies may be proteome profiling.

CLINICAL SIGNIFICANCE

Biomarker studies will provide valuable information to identify early biological events associated with the adverse health effects of engineered nanomaterials before the manifestation of clinical outcomes. This is particularly important for the health surveillance of workers who may be at higher risk due to their occupational settings.

Proteomic response to elevated PCO2 level in eastern oysters, Crassostrea virginica: evidence for oxidative stress

Estuaries are characterized by extreme fluctuations in CO2 levels due to bouts of CO2 production by the resident biota that exceed its capacity of CO2 consumption and/or the rates of gas exchange with the atmosphere and open ocean waters. Elevated partial pressures of CO2 (PCO2; i.e. environmental hypercapnia) decrease the pH of estuarine waters and, ultimately, extracellular and intracellular pH levels of estuarine organisms such as mollusks that have limited capacity for pH regulation. We analyzed proteomic changes associated with exposure to elevated PCO2 in the mantle tissue of eastern oysters (Crassostrea virginica) after 2 weeks of exposure to control (∼39 Pa PCO2) and hypercapnic (∼357 Pa PCO2) conditions using two-dimensional gel electrophoresis and tandem mass spectrometry. Exposure to high PCO2 resulted in a significant proteome shift in the mantle tissue, with 12% of proteins (54 out of 456) differentially expressed under the high PCO2 compared with control conditions. Of the 54 differentially expressed proteins, we were able to identify 17. Among the identified proteins, two main functional categories were upregulated in response to hypercapnia: those associated with the cytoskeleton (e.g. several actin isoforms) and those associated with oxidative stress (e.g. superoxide dismutase and several peroxiredoxins as well as the thioredoxin-related nucleoredoxin). This indicates that exposure to high PCO2 (∼357 Pa) induces oxidative stress and suggests that the cytoskeleton is a major target of oxidative stress. We discuss how elevated CO2 levels may cause oxidative stress by increasing the production of reactive oxygen species (ROS) either indirectly by lowering organismal pH, which may enhance the Fenton reaction, and/or directly by CO2 interacting with other ROS to form more free radicals. Although estuarine species are already exposed to higher and more variable levels of CO2 than other marine species, climate change may further increase the extremes and thereby cause greater levels of oxidative stress.

Better safe than sorry: Understanding the toxicological properties of inorganic nanoparticles manufactured for biomedical applications

The development of nanoparticles for biomedical applications including medical imaging and drug delivery is currently undergoing a dramatic expansion. However, as the range of nanoparticle types and applications increases, it is also clear that the potential toxicities of these novel materials and the properties driving such toxic responses must also be understood. Indeed, a detailed assessment of the factors that influence the biocompatibility and/or toxicity of nanoparticles is crucial for the safe and sustainable development of the emerging nanotechnologies. This review summarizes some of the recent developments in the field of nanomedicine with particular emphasis on inorganic nanoparticles for drug delivery. The synthesis routes, physico-chemical characteristics, and cytotoxic properties of inorganic nanoparticles are thus explored and lessons learned from the toxicological investigation of three common types of engineered nanomaterials of titania, gold, and mesoporous silica are discussed. Emphasis is placed on the recognition versus non-recognition of engineered nanomaterials by the immune system, the primary surveillance system against microorganisms and particles, which, in turn, is intimately linked to the issue of targeted drug delivery using such nanomaterials as carrier systems.

Global screening of human cord blood proteomes for biomarkers of toxic exposure and effect

BACKGROUND

Exposures of pregnant women to natural and manmade chemicals can lead to negative health effects in the baby, ranging from low birth weight to developmental defects. In some cases, diseases were postulated to have their basis in toxic exposure in utero or in early childhood. Therefore, an understanding of fetal responses to environmental exposures is essential. To that end, cord blood is a readily accessible biofluid whose proteomic makeup remains mostly unexplored when compared with that of adults.

OBJECTIVES

Our goal was an initial global assessment of the fetal serum proteome and for the identification of protein biomarkers indicative of toxic in utero exposures related to maternal cigarette smoking.

METHODS

Drawing from a repository of 300 samples, we selected umbilical cord blood sera from 12 babies born to six smokers and six nonsmokers and analyzed both sample pools by tandem mass spectrometry in conjunction with isobaric tags (iTRAQ) for protein quantification.

RESULTS

We identified 203 proteins, 17 of which were differentially expressed between the cigarette smoke-exposed and control populations. Most of the identified candidate biomarkers were biologically plausible, thereby underscoring the feasibility of screening neonates with global proteomic techniques for biomarkers of exposure and early biological effects triggered by in utero chemical exposures.

CONCLUSIONS

This validation study provides an initial view of the proteome of human cord blood sera; it demonstrates the feasibility of identifying therein by use of proteomics, biomarkers of environmental, toxic exposures.

Biomarkers in population studies: environmental mutagenesis and risk for cancer

Biomarkers of exposure and biological effects have frequently been used to monitor populations for their exposure to toxic substances and for the prediction of disease risk, such as cancer. Current interest is focused on improving the use of biomarkers to better understand biological mechanisms for improved risk assessment. Such improvements involve the understanding of inter-individual variations in response to exposure, integration of genomic and proteomic technologies into biomarker studies, development of functional biomarkers, and the use of high tech procedures like biosensors and lab-on-a-chip approaches. The latter two approaches can provide unique contributions by providing specific and real-time reporting of excessive exposure. Based on the generation of more reliable information regarding exposure-specific effects, biological mechanisms, and health risk, more realistic prevention and intervention protocols have been implemented. The usefulness and application of these biomarkers and technologies will be presented.

Important research questions in allergy and related diseases: nonallergic rhinitis: a GA2LEN paper

Nonallergic rhinitis (NAR) can be defined as a chronic nasal inflammation which is not caused by systemic IgE-dependent mechanisms. It is common and probably affects far more than 200 million people worldwide. Both children and adults are affected. However, its exact prevalence is unknown and its phenotypes need to be evaluated using appropriate methods to better understand its pathophysiology, diagnosis and management. It is important to differentiate between infectious rhinitis, allergic/NAR and chronic rhinosinusitis, as management differs for each of these cases. Characterization of the phenotype, mechanisms and management of NAR represents one of the major unmet needs in allergic and nonallergic diseases. Studies on children and adults are required in order to appreciate the prevalence, phenotype, severity and co-morbidities of NAR. These studies should compare allergic and NAR and consider different age group populations including elderly subjects. Mechanistic studies should be carried out to better understand the disease(s) and risk factors and to guide towards an improved diagnosis and therapy. These studies need to take the heterogeneity of NAR into account. It is likely that neuronal mechanisms, T cells, innate immunity and possibly auto-immune responses all play a role in NAR and may also contribute to the symptoms of allergic rhinitis.