Sediment toxicity data and excess simultaneously extracted metals from field-collected samples: Comparison to United States Environmental Protection Agency benchmarks.

US Environmental Protection Agency (USEPA) Procedures for the Derivation of Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: Metal Mixtures are based on the principle that metals toxicity to benthic organisms is determined by bioavailable metals concentrations in porewater. One ESB is based on the difference between simultaneously extracted metal (SEM) and acid volatile sulfide (AVS) concentrations in sediment (excess SEM). The excess SEM ESBs include a lower uncertainty bound, below which most samples (95%) are expected to be "nontoxic" (defined as a bioassay mortality rate ≤24%), and an upper uncertainty bound, above which most samples (95%) are expected to be "toxic" (defined as a mortality rate >24%). Samples that fall between the upper and lower bounds are classified as "uncertain." Excess SEM ESBs can, in principle, be improved by normalizing for organic carbon (OC). OC is a binding phase that reduces metals bioavailability. OC normalization should improve the accuracy of bioavailable metal concentration estimates, thus tightening uncertainty bounds. We evaluated field-collected sediments from 13 studies with excess SEM, OC, and bioassay data (n = 740). Use of the OC-normalized excess SEM benchmarks did not improve prediction accuracy. The ESB model predicts OC-normalized excess SEM exceeding the upper benchmark even when toxicity is not observed, because error in the OC normalization model increases at low OC concentrations. To minimize the likelihood of incorrectly identifying nontoxic samples as toxic, we recommend that OC normalization of excess SEM should not be considered for sediments with an OC concentration <1% and is questionable for sediments with an OC concentration of 1%-4%. Additional focused studies are needed to confirm or refine the minimum sediment OC concentrations that are applicable for reducing uncertainty in toxicity predictions due to excess SEM. Integr Environ Assess Manag 2022;18:174-186. © 2021 SETAC.

Collection and use of porewater data from sediment bioassay studies for understanding exposure to bioavailable metals.

The US Environmental Protection Agency Procedures for the Derivation of Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: Metal Mixtures (Cadmium, Copper, Lead, Nickel, Silver and Zinc) equilibrium partitioning approach causally link metal concentrations and toxicological effects; they apply to sediment and porewater (i.e., interstitial water). The evaluation of bioavailable metal concentrations in porewater, using tools such as the biotic ligand model, provides an advancement that complements sediment-based evaluations. However, porewater characterization is less commonly performed in sediment bioassays than sediment chemistry characterization due to the difficulty and expense of porewater collection as well as concerns about interpretation of porewater data. This study discusses the advantages and disadvantages of different porewater extraction methods for analysis of metals and bioavailability parameters during laboratory sediment bioassays, with a focus on peepers and centrifugation. The purpose is to provide recommendations to generate bioassay porewater data of sufficient quality for use in risk-based decision-making, such as for regulated cleanup actions. Comparisons of paired data from previous bioassay studies indicate that metal porewater concentrations collected via centrifugation tend to be higher than those collected via peepers. However, centrifugation disrupts the redox status of the sediment; also, metal concentrations can vary markedly based on centrifugation conditions. Data to compare the concentrations of peeper- and centrifugation-collected bioavailability parameters (e.g., major ions, pH) are much more limited, but indicate smaller differences than those observed for metal concentrations. While peepers can be sampled without altering the redox status of the porewater, the small volume of porewater peepers collected is enough for metal concentration analysis, but insufficient for analysis of all metal bioavailability parameters. Given the benefits of metal collection via peepers, it is optimal to use centrifugation and peepers in tandem for bioassay porewater collection to improve bioavailability predictions. Environ Assess Manag 2022;18:1321-1334. © 2021 SETAC.

Refining our understanding of metal bioavailability in sediments using information from porewater: Application of a multimetal biotic ligand model as an extension of the equilibrium partitioning sediment benchmarks.

The equilibrium partitioning sediment benchmarks (ESBs) derived by the US Environmental Protection Agency (USEPA) in 2005 provide a mechanistic framework for understanding metal bioavailability in sediments by considering equilibrium partitioning (EqP) theory, which predicts that metal bioavailability in sediments is determined largely by partitioning to sediment particles. Factors that favor the partitioning of metals to sediment particles, such as the presence of acid volatile sulfide (AVS) and sediment organic matter, reduce metal bioavailability to benthic organisms. Because ESBs link metal bioavailability to partitioning to particles, they also predict that measuring metals in porewater can lead to a more accurate assessment of bioavailability and toxicity to benthic organisms. At the time of their development, sediment ESBs based on the analysis of porewater metal concentrations were limited to comparison with hardness-dependent metals criteria for the calculation of interstitial water benchmark units (IWBUs). However, the multimetal biotic ligand model (mBLM) provides a more comprehensive assessment of porewater metal concentrations, because it considers factors in addition to hardness, such as pH and dissolved organic carbon, and allows for interactions between metals. To evaluate the utility of the various sediment and porewater ESBs, four Hyalella azteca bioassay studies were identified that included sediment and porewater measurements of metals and porewater bioavailability parameters. Evaluations of excess simultaneously extracted metals, IWBUs, and mBLM toxic units (TUs) were compared among the bioassay studies. For porewater, IWBUs and mBLM TUs were calculated using porewater metal concentrations from samples collected using centrifugation and peepers. The percentage of correct predictions of toxicity was calculated for each benchmark comparison. The mBLM-based assessment using peeper data provided the most accurate predictions for the greatest number of samples among the evaluation methods considered. This evaluation demonstrates the value of porewater-based evaluations in conjunction with sediment chemistry in understanding toxicity observed in bioassay studies. Integr Environ Assess Manag 2022;18:1335-1347. © 2021 SETAC.

Chimeric antigen receptor engineered NK cellular immunotherapy overcomes the selection of T-cell escape variant cancer cells.

BACKGROUND: As heterogeneous tumors develop in the face of intact immunity, tumor cells harboring genomic or expression defects that favor evasion from T-cell detection or elimination are selected. For patients with such tumors, T cell-based immunotherapy alone infrequently results in durable tumor control. METHODS: Here, we developed experimental models to study mechanisms of T-cell escape and demonstrated that resistance to T-cell killing can be overcome by the addition of natural killer (NK) cells engineered to express a chimeric antigen receptor (CAR) targeting programmed death ligand-1 (PD-L1). RESULTS: In engineered models of tumor heterogeneity, PD-L1 CAR-engineered NK cells (PD-L1 t-haNKs) prevented the clonal selection of T cell-resistant tumor cells observed with T-cell treatment alone in multiple models. Treatment of heterogenous cancer cell populations with T cells resulted in interferon gamma (IFN-γ) release and subsequent upregulation of PD-L1 on tumor cells that escaped T-cell killing through defects in antigen processing and presentation, priming escape cell populations for PD-L1 dependent killing by PD-L1 t-haNKs in vitro and in vivo. CONCLUSIONS: These results describe the underlying mechanisms governing synergistic antitumor activity between T cell-based immunotherapy that results in IFN-γ production, upregulation of PD-L1 on T-cell escape cells, and the use of PD-L1 CAR-engineered NK cells to target and eliminate resistant tumor cell populations.

Framing scientific analyses for risk management of environmental hazards by communities: case studies with seafood safety issues.

Risk management provides a context for addressing environmental health hazards. Critical to this approach is the identification of key opportunities for participation. We applied a framework based on the National Research Council's (NRC) analytic-deliberative risk management dialogue model that illustrates two main iterative processes: informing and framing. The informing process involves conveying information from analyses of risk issues, often scientific, to all parties so they can participate in deliberation. In the framing process, ideas and concerns from stakeholder deliberations help determine what and how scientific analyses will be carried out. There are few activities through which affected parties can convey their ideas from deliberative processes for framing scientific analyses. The absence of participation results in one-way communication. The analytic-deliberative dialogue, as envisioned by the NRC and promoted by the National Institute of Environmental Health Sciences (NIEHS), underscores the importance of two-way communication. In this article we present case studies of three groups--an Asian and Pacific Islander community coalition and two Native American Tribes--active in framing scientific analyses of health risks related to contaminated seafood. Contacts with these organizations were established or enhanced through a regional NIEHS town meeting. The reasons for concern, participation, approaches, and funding sources were different for each group. Benefits from their activities include increased community involvement and ownership, better focusing of analytical processes, and improved accuracy and appropriateness of risk management. These examples present a spectrum of options for increasing community involvement in framing analyses and highlight the need for increased support of such activities.

Modeling developmental processes in animals: applications in neurodevelopmental toxicology.

Biologically based dose-response models can provide a framework for incorporating mechanistic information into our assessments of neurotoxicity considering both kinetic and dynamic processes. We have constructed models for normal midbrain and neocortex development and we have extended these models to evaluate the neurodevelopmental toxicity of ethanol and methyl mercury. Using such modeling approaches, we have been able to test hypothesized modes of action for these neurodevelopmental toxicants. Specifically, we have compared ethanol's effects on neocortical neurogenesis and exacerbation of apoptosis during the synaptogenesis period. We have used methylmercury as an example of how one can link toxicokinetic and toxicodynamic models and also as an example of how mechanistic data on gene expression can support model development. In summary, using examples from our research group, this paper illustrates the need for models that evaluate both qualitative and quantitative kinetic and dynamic factors in order to understand the potential impacts of neurodevelopmental toxicants.

Fish consumption as a driver of risk-management decisions and human health-based water quality criteria.

The use and interpretation of fish consumption surveys and interviews, the application of fish consumption rates for sediment evaluation and cleanup, and the development of human health water quality criteria (HH WQC) are complex and interrelated issues. The present article focuses on these issues using examples from the United States, although the issues may be relevant for other countries. Some key considerations include the fact that there are many types of fish consumption surveys (e.g., 24-h recall surveys, food frequency questionnaires, creel surveys), and these surveys have different advantages and limitations. Identification of target populations for protection, identification of the species and quantities of fish consumed, and determination of bioaccumulation assumptions are important factors when developing water quality and sediment screening levels and standards. Accounting for the cultural importance of fish consumption for some populations is an even more complex element. Discussions about HH WQC often focus only on the fish consumption rate and may not have broad public input. Some states are trying to change this through extensive public participation efforts and use of probabilistic approaches to derive HH WQC. Finally, there are limits to what WQC can achieve. Solutions beyond the establishment of WQC that target toxics reduction from other sources may provide the greatest improvements to water quality and reductions in human health risks in the future.

From sediment to tissue and tissue to sediment: an evaluation of statistical bioaccumulation models.

Biota-sediment accumulation factors (BSAFs) and biota-sediment accumulation regressions (BSARs) are statistical models that may be used to estimate tissue chemical concentrations from sediment chemical concentrations or vice versa. Biota-sediment accumulation factors and BSARs are used to fill tissue concentration data gaps, set sediment preliminary remediation goals (PRGs), and make projections about the effectiveness of potential sediment cleanup projects in reducing tissue chemical concentrations. We explored field-based, benthic invertebrate biota-sediment chemical concentration relationships using data from the US Environmental Protection Agency (USEPA) Mid-Continent Ecology Division (MED) BSAF database. Approximately two thirds of the 262 relationships investigated were very poor (r(2) < 0.3 or p-value ≥ 0.05); for some of the biota-sediment relationships that did have a significant nonzero slope (p-value < 0.05), lipid-normalized tissue concentrations tended to decrease as the colocated organic carbon (OC)-normalized sediment concentration increased. Biota-sediment relationships were further evaluated for 3 of the 262 datasets. Biota-sediment accumulation factors, linear regressions, model II regressions, illustrative sediment PRGs, and confidence intervals (CIs) were calculated for each of the three examples. These examples illustrate some basic but important statistical practices that should be followed before selecting a BSAR or BSAF or relying on these simple models of biota-sediment relationships to support consequential management decisions. These practices include the following: one should not assume that the relationship between chemical concentrations in tissue and sediment is necessarily linear, one should not assume the model intercept to be zero, and one should not place too much stock on models that are heavily influenced by one or a few high chemical concentration data points. People will continue to use statistical models of field-based biota-sediment chemical concentration relationships to support sediment investigations and remedial action decisions. However, it should not be assumed that the models will be reliable. In developing and applying BSAFs and BSARs, it is essential that best practices are followed and model limitations and uncertainties are understood, acknowledged, and quantified as much as possible.

A surprising cross-species conservation in the genomic landscape of mouse and human oral cancer identifies a transcriptional signature predicting metastatic disease.

PURPOSE: Improved understanding of the molecular basis underlying oral squamous cell carcinoma (OSCC) aggressive growth has significant clinical implications. Herein, cross-species genomic comparison of carcinogen-induced murine and human OSCCs with indolent or metastatic growth yielded results with surprising translational relevance. EXPERIMENTAL DESIGN: Murine OSCC cell lines were subjected to next-generation sequencing (NGS) to define their mutational landscape, to define novel candidate cancer genes, and to assess for parallels with known drivers in human OSCC. Expression arrays identified a mouse metastasis signature, and we assessed its representation in four independent human datasets comprising 324 patients using weighted voting and gene set enrichment analysis. Kaplan-Meier analysis and multivariate Cox proportional hazards modeling were used to stratify outcomes. A quantitative real-time PCR assay based on the mouse signature coupled to a machine-learning algorithm was developed and used to stratify an independent set of 31 patients with respect to metastatic lymphadenopathy. RESULTS: NGS revealed conservation of human driver pathway mutations in mouse OSCC, including in Trp53, mitogen-activated protein kinase, phosphoinositide 3-kinase, NOTCH, JAK/STAT, and Fat1-4. Moreover, comparative analysis between The Cancer Genome Atlas and mouse samples defined AKAP9, MED12L, and MYH6 as novel putative cancer genes. Expression analysis identified a transcriptional signature predicting aggressiveness and clinical outcomes, which were validated in four independent human OSCC datasets. Finally, we harnessed the translational potential of this signature by creating a clinically feasible assay that stratified patients with OSCC with a 93.5% accuracy. CONCLUSIONS: These data demonstrate surprising cross-species genomic conservation that has translational relevance for human oral squamous cell cancer. Clin Cancer Res; 20(11); 2873-84. ©2014 AACR.

The clinical implications of antitumor immunity in head and neck cancer.

Recent developments have renewed interest in understanding the interaction between transformed cells and the immune system in the tumor microenvironment. Here, we provide a comprehensive review addressing the basics of tumor immunology in relation to head and neck cancer and the cellular components potentially involved in antitumor immune responses. In addition, we describe the mechanisms by which head and neck cancer cells escape immune-mediated killing and progress to form clinically significant disease. Further, we detail what effects standard anticancer therapies may have on antitumor immune responses and how these responses may be altered by current and investigational immunotherapies. Finally, we discuss future directions that need to be considered in the development of new immunotherapeutics designed to durably alter the immune response in favor of the host.

Comparative analysis of tumor-infiltrating lymphocytes in a syngeneic mouse model of oral cancer.

OBJECTIVE: To perform a comparative analysis of infiltrating immune cells in a newly developed C57BL/6 background syngeneic transplantable mouse oral cancer (MOC) model. STUDY DESIGN/SETTING: Scientific study in an academic medical center. METHODS: Use of carcinogen-induced tumorigenesis, tissue culture, cell line transplantation, and flow cytometric analysis techniques. RESULTS: Previously, the authors established a series of cell line models that displayed dichotomous growth phenotypes when transplanted into immunocompetent mice. They now show that the indolent growth pattern of the MOC1-generated tumors is associated with increased baseline and inducible major histocompatibility complex class I expression and increased CD8(+) T-cell infiltration into the tumor microenvironment. Conversely, the aggressive and metastatic pattern of MOC2-generated tumors has decreased basal and inducible class I expression and is associated with FOXP3(+)CD4(+) regulatory T-cell infiltration. Delayed primary tumor growth after targeted monoclonal antibody therapy of these FOXP3(+) regulatory cells further suggests that these immune cells contribute to the aggressive phenotype of MOC2. CONCLUSION: These data validate that key infiltrating immune cells identified here parallel findings in human head and neck cancer, making this newly developed syngeneic model a critical platform for the continued dissection of tumor-host interactions in head and neck cancer.

ERK1/2 regulation of CD44 modulates oral cancer aggressiveness.

Carcinogen-induced oral cavity squamous cell carcinoma (OSCC) incurs significant morbidity and mortality and constitutes a global health challenge. To gain further insight into this disease, we generated cell line models from 7,12-dimethylbenz(a)anthracene-induced murine primary OSCC capable of tumor formation upon transplantation into immunocompetent wild-type mice. Whereas several cell lines grew rapidly and were capable of metastasis, some grew slowly and did not metastasize. Aggressively growing cell lines displayed ERK1/2 activation, which stimulated expression of CD44, a marker associated with epithelial to mesenchymal transition and putative cancer stem cells. MEK (MAP/ERK kinase) inhibition upstream of ERK1/2 decreased CD44 expression and promoter activity and reduced cell migration and invasion. Conversely, MEK1 activation enhanced CD44 expression and promoter activity, whereas CD44 attenuation reduced in vitro migration and in vivo tumor formation. Extending these findings to freshly resected human OSCC, we confirmed a strict relationship between ERK1/2 phosphorylation and CD44 expression. In summary, our findings identify CD44 as a critical target of ERK1/2 in promoting tumor aggressiveness and offer a preclinical proof-of-concept to target this pathway as a strategy to treat head and neck cancer.

CXCR3 enhances a T-cell-dependent epidermal proliferative response and promotes skin tumorigenesis.

The chemokine receptor CXCR3 has been proposed to play a critical role in host antitumor responses. In this study, we defined CXCR3-expressing immune cell infiltration in human skin squamous cell carcinomas and then used CXCR3-deficient mice to assess the contribution of CXCR3 to skin tumorigenesis. Our studies employed two established protocols for chemical skin carcinogenesis [methylcholanthrene (MCA) or 7,12-dimethylbenz(a)anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA) models]. CXCR3 deletion did not affect tumor development in the MCA model; however, CXCR3 was important in the DMBA/TPA model where gene deletion reduced the incidence of skin tumors. This decreased incidence of skin tumors did not reflect differences in epidermal development but rather was associated with reduced epidermal thickness and proliferation in CXCR3(-/-) mice, implicating the CXCR3 pathway in DMBA/TPA-induced epidermal inflammation and proliferation. Notably, CXCR3 expressed in CD4(+) and CD8(+) T cells was found to be important for enhanced epidermal proliferation. Specifically, CXCR3-deficient mice reconstituted with T cells isolated from wild-type mice treated with DMBA/TPA restored wild-type levels of epidermal proliferation in the mutant mice. Taken together, our findings establish that CXCR3 promotes epidermal tumorigenesis likely through a T-cell-dependent induction of keratinocyte proliferation.

Contribution of PCB exposure from fish consumption to total dioxin-like dietary exposure.

Polychlorinated biphenyls (PCB) are the second greatest cause of fish advisories, and are often the greatest contributors to dioxin-like toxic equivalency (TEQ) in fish and seafood. Because fish consumption is associated with both contaminant risks and health benefits, incremental health risks from PCBs in fish should be considered within the context of overall TEQ associated dietary risk to enable consumers to make informed decisions about choosing to eat fish or alternate foodstuffs. In this paper, potential TEQ exposure from PCBs in fish for adults with a variety of consumption patterns and consuming fish from a variety of sources are calculated using recent consumption and fish contaminant data from the literature and compared to total TEQ exposure from all sources. For high-level consumers and individuals eating fish from relatively contaminated sites, PCB TEQ exposure from fish consumption alone may exceed the 1 pg TEQ/kg/day average adult daily intake estimated by EPA, which itself carries an upper bound cancer risk of 1 in 1000. PCB TEQ risk for average consumers of commercial fish is expected to be far less, but is highly uncertain, since there is a dearth of congener specific PCB data for commercial fish and seafood.

CD44 deficiency leads to enhanced neutrophil migration and lung injury in Escherichia coli pneumonia in mice.

CD44 is a major cell-surface receptor for hyaluronic acid (HA), a glycosaminoglycan component of extracellular matrix. HA-CD44 interactions have been implicated in leukocyte extravasation into an inflammatory site. This study examined the role of CD44 in acute inflammatory responses during pneumonias induced by Escherichia coli and Streptococcus pneumoniae using CD44-deficient mice. In E. coli-induced pneumonia, neutrophil accumulation in the lungs and edema formation was increased by 84% and 88%, respectively, in CD44-deficient mice compared to wild-type mice. In contrast, no difference was observed between these genotypes in S. pneumoniae-induced pneumonia, and the HA content in the lungs decreased after instillation of S. pneumoniae, but not E. coli, in both genotypes. Studies to determine the mechanisms for this enhanced response showed that: 1) neutrophil apoptosis was not different between these two genotypes in either type of pneumonia; 2) CD44 deficiency resulted in enhanced mRNA expression of several inflammatory genes; and 3) CD44-deficient neutrophils migrated through Matrigel in response to chemoattractants faster and in greater numbers than wild-type neutrophils in vitro and this increase was in part dependent on HA content in the Matrigel. These data demonstrate that CD44 deficiency results in enhanced inflammation in E. coli but not S. pneumoniae-induced pneumonia, suggesting a previously unrecognized role for CD44 in limiting the inflammatory response to E. coli.

A model for optimization of biomarker testing frequency to minimize disease and cost: example of beryllium sensitization testing.

A common problem with medical surveillance programs using biomarkers is determining the optimal frequency of testing to minimize adverse health effects and cost. In the case of beryllium-exposed workers, frequency of testing for beryllium sensitization may be especially important. Recent studies indicate a lack of dose response for beryllium sensitization, but do support a dose response for the development of chronic beryllium disease (CBD). Though unproven, this implies that early identification of sensitization and immediate removal from exposure may reduce development of CBD. A model is proposed to project the optimal frequency of sensitization testing using the current beryllium lymphocyte proliferation test (BeLPT) to minimize disease-related costs, assuming that a positive BeLPT will precede CBD. Conversion rates for cumulative exposure to disease development were adapted from the literature and used with testing costs and cost of disease estimates in the model. The model was run assuming several test frequency regimes. Results support the use of periodic testing in line with the annual schedule proposed in the Final Chronic Beryllium Disease Prevention Program Rule (1999) following initial testing within three months of first beryllium exposure. The financial and health benefits of reducing the time from exposure to detection of early disease was also explored with the model and demonstrated as a highly desirable characteristic for an alternative test or improved BeLPT. Limitations of the approach are discussed as well as options for adapting this biomarker optimization methodology to consider biomarkers of other exposure-associated diseases.