Sally R. Littau

Pulmonary Biomarkers Based on Alterations in Protein Expression after Exposure to Arsenic

Objective Environmental exposure to arsenic results in multiple adverse effects in the lung. Our objective was to identify potential pulmonary protein biomarkers in the lung-lining fluid of mice chronically exposed to low-dose As and to validate these protein changes in human populations exposed to As. Methods Mice were administered 10 or 50 ppb As (sodium arsenite) in their drinking water for 4 weeks. Proteins in the lung-lining fluid were identified using two-dimensional gel electrophoresis (n = 3) or multidimensional protein identification technology (MUDPIT) (n = 2) coupled with mass spectrometry. Lung-induced sputum samples were collected from 57 individuals (tap water As ranged from ~ 5 to 20 ppb). Protein levels in sputum were determined by ELISA, and As species were analyzed in first morning void urine. Results Proteins in mouse lung-lining fluid whose expression was consistently altered by As included glutathione-S-transferase (GST)-omega-1, contraspin, apolipoprotein A-I and A-IV, enolase-1, peroxiredoxin-6, and receptor for advanced glycation end products (RAGE). Validation of the putative biomarkers was carried out by evaluating As-induced alterations in RAGE in humans. Regression analysis demonstrated a significant negative correlation (p = 0.016) between sputum levels of RAGE and total urinary inorganic As, similar to results seen in our animal model. Conclusion Combinations of proteomic analyses of animal models followed by specific analysis of human samples provide an unbiased determination of important, previously unidentified putative biomarkers that may be related to human disease.

Occupational PAH Exposures during Prescribed Pile Burns

Wildland firefighters are exposed to particulate matter and gases containing polycyclic aromatic hydrocarbons (PAHs), many of which are known carcinogens. Our objective was to evaluate the extent of firefighter exposure to particulate and PAHs during prescribed pile burns of mainly ponderosa pine slash and determine whether these exposures were correlated with changes in urinary 1-hydroxypyrene (1-HP), a PAH metabolite. Personal and area sampling for particulate and PAH exposures were conducted on the White Mountain Apache Tribe reservation, working with 21 Bureau of Indian Affairs/Fort Apache Agency wildland firefighters during the fall of 2006. Urine samples were collected pre- and post-exposure and pulmonary function was measured. Personal PAH exposures were detectable for only 3 of 16 PAHs analyzed: naphthalene, phenanthrene, and fluorene, all of which were identified only in vapor-phase samples. Condensed-phase PAHs were detected in PM2.5 area samples (20 of 21 PAHs analyzed were detected, all but naphthalene) at concentrations below 1 microg m(-3). The total PAH/PM2.5 mass fractions were roughly a factor of two higher during smoldering (1.06 +/- 0.15) than ignition (0.55 +/- 0.04 microg mg(-1)). There were no significant changes in urinary 1-HP or pulmonary function following exposure to pile burning. In summary, PAH exposures were low in pile burns, and urinary testing for a PAH metabolite failed to show a significant difference between baseline and post-exposure measurements.

Acute cardiovascular effects of firefighting and active cooling during rehabilitation.

Objectives: To determine the cardiovascular and hemostatic effects of fire suppression and postexposure active cooling. Methods: Forty-four firefighters were evaluated before and after a 12-minute live-fire drill. Next, 50 firefighters performing the same drill were randomized to undergo postfire forearm immersion in 10°C water or standard rehabilitation. Results: In the first study, heart rate and core body temperature increased and serum C-reactive protein decreased but there were no significant changes in fibrinogen, sE-selectin, or sL-selectin. The second study demonstrated an increase in blood coagulability, leukocyte count, factors VIII and X, cortisol, and glucose, and a decrease in plasminogen and sP-selectin. Active cooling reduced mean core temperature, heart rate, and leukocyte count. Conclusions: Live-fire exposure increased core temperature, heart rate, coagulability, and leukocyte count; all except coagulability were reduced by active cooling.

Tracheobronchial Markers of Lung Injury in Smoke Inhalation Victims

Although smoke inhalation injury victims frequently develop severe hypoxemia and are at increased risk of acute respiratory distress syndrome (ARDS), no early prognostic tests are currently available. The objectives were to determine early longitudinal changes in tracheobronchial fluid inflammatory markers and assess the value of initial concentrations as predictors of subsequent lung injury. Partial pressure of arterial oxygen (Pao2) and the fraction of inspired oxygen (Fio2) were recorded approximately every 6 hours from intubated smoke inhalation victims admitted to a regional burn center. Tracheobronchial suction fluid was collected every 2 hours and assayed for interleukins (IL-1&bgr;, -8, and -10), tumor necrosis factor-&agr;, transforming growth factor-&bgr;1, soluble Fas ligand (sFasL), and complement factor 5a. Temporal trends in marker concentrations during 36 hours and the relations between initial concentrations and lowest Pao2/Fio2 or ARDS within 72 hours were assessed using random coefficients modeling and cross-sectional analysis. In 21 subjects with tracheobronchial samples collected within 6.5 hours of intubation, 14 (66.7%) developed acute hypoxemia (Pao2/Fio2 ≤200) within 72 hours of exposure and nine (42.9%) developed ARDS, as defined by the American-European consensus conference on ARDS. IL-8 increased sharply in the first 6.5 hours postexposure (P < .001), and IL-1&bgr; in the first 6.1 hours (P < .001). No significant temporal trends in IL-10, tumor necrosis factor-&agr;, transforming growth factor-&bgr;1, sFasL, or complement factor 5a were found. Only initial IL-8 was associated with increased Pao2/Fio2 (P = .013) and with a minimum Pao2/Fio2 >200 (P = .042) during 72 hours. In smoke inhalation victims, tracheobronchial IL-1&bgr; and IL-8 increase rapidly and high initial IL-8 may predict improved oxygenation.

Environmental arsenic exposure and serum matrix metalloproteinase-9

The objective of this study was to evaluate the relationship between environmental arsenic exposure and serum matrix metalloproteinase (MMP)-9, a biomarker associated with cardiovascular disease and cancer. In a cross-sectional study of residents of Arizona, USA (n=215) and Sonora, Mexico (n=163), drinking water was assayed for total arsenic, and daily drinking water arsenic intake was estimated. Urine was speciated for arsenic, and concentrations were adjusted for specific gravity. Serum was analyzed for MMP-9 using ELISA. Mixed model linear regression was used to assess the relation among drinking water arsenic concentration, drinking water arsenic intake, urinary arsenic sum of species (the sum of arsenite, arsenate, monomethylarsonic acid and dimethylarsinic acid), and MMP-9, controlling for autocorrelation within households. Drinking water arsenic concentration and intake were positively associated with MMP-9, both in crude analysis and after adjustment for gender, country/ethnicity, age, body mass index, current smoking, and diabetes. Urinary arsenic sum of species was positively associated with MMP-9 in multivariable analysis only. Using Akaike’s Information Criterion, arsenic concentration in drinking water provided a better fitting model of MMP-9 than either urinary arsenic or drinking water arsenic intake. In conclusion, arsenic exposure evaluated using all three exposure metrics was positively associated with MMP-9.

Comparison of Acute Health Effects from Exposures to Diesel and Biodiesel Fuel Emissions

Objective: To investigate the comparative acute health effects associated with exposures to diesel and 75% biodiesel/25% diesel (B75) blend fuel emissions. Methods: We analyzed multiple health endpoints in 48 healthy adults before and after exposures to diesel and B75 emissions in an underground mine setting—lung function, lung and systemic inflammation, novel biomarkers of exposure, and oxidative stress were assessed. Results: B75 reduced respirable diesel particulate matter by 20%. Lung function declined significantly more after exposure to diesel emissions. Lung inflammatory cells along with sputum and plasma inflammatory mediators increased significantly to similar levels with both exposures. Urinary 8-hydroxydeoxyguanosine, a marker of oxidative stress, was not significantly changed after either exposure. Conclusions: Use of B75 lowered respirable diesel particulate matter exposure and some associated acute health effects, although lung and systemic inflammation were not reduced compared with diesel use.

Occupational heat strain in a hot underground metal mine.

Objective: In a hot underground metal mine, this study evaluated the relationship between job task, physical body type, work shift, and heat strain. Methods: Thirty-one miners were evaluated during 98 shifts while performing deep shaft-sinking tasks. Continuous core body temperature, heart rate, pre- and postshift urine specific gravity (USG), and body mass index were measured. Results: Cutting and welding tasks were associated with significantly (P < 0.05) increased core body temperature, maximum heart rate, and increased postshift urine specific gravity. Miners in the obese level II and III body mass index categories, as well as those working night shift, had lower core body temperatures (P < 0.05). Conclusions: This study confirms that job task, body type, and shift are risk factors for heat strain.

Environmental arsenic exposure, selenium and sputum alpha-1 antitrypsin

Exposure to arsenic in drinking water is associated with increased respiratory disease. Alpha-1 antitrypsin (AAT) protects the lung against tissue destruction. The objective of this study was to determine whether arsenic exposure is associated with changes in airway AAT concentration and whether this relationship is modified by selenium. A total of 55 subjects were evaluated in Ajo and Tucson, Arizona. Tap water and first morning void urine were analyzed for arsenic species, induced sputum for AAT and toenails for selenium and arsenic. Household tap-water arsenic, toenail arsenic and urinary inorganic arsenic and metabolites were significantly higher in Ajo (20.6±3.5 μg/l, 0.54±0.77 μg/g and 27.7±21.2 μg/l, respectively) than in Tucson (3.9±2.5 μg/l, 0.16±0.20 μg/g and 13.0±13.8 μg/l, respectively). In multivariable models, urinary monomethylarsonic acid (MMA) was negatively, and toenail selenium positively associated with sputum AAT (P=0.004 and P=0.002, respectively). In analyses stratified by town, these relationships remained significant only in Ajo, with the higher arsenic exposure. Reduction in AAT may be a means by which arsenic induces respiratory disease, and selenium may protect against this adverse effect.

Cytokine genotype and phenotype effects on lung function decline in firefighters.

Objective: We conducted this study to evaluate the association of cytokine genotypes and sputum concentrations on longitudinal decline in lung function in firefighters. Methods: In 67 firefighters with at least four pulmonary function tests, DNA was analyzed for functional polymorphisms of interleukin (IL)-1&bgr;, IL-1 receptor antagonist (IL-1RA), IL-8, IL-10, tumor necrosis factor-alpha (TNF-&agr;) genes, and sputum evaluated for cytokine concentration by ELISA. Results: The annual rate of FEV1 decline was greater in firefighters with TT genotypes at IL-10 (−819) (P = 0.009) and with CT or TT genotypes at IL-1RA (2018) (P = 0.050). These genotypes were not associated with concentrations of sputum cytokine, but increased IL-1RA was associated with a slower rate of FEV1 decline (P = 0.025), as was increased sputum macrophage count (P = 0.002). Conclusions: Cytokine genotypes were associated with the rate of FEV1 decline but did not alter concentrations of sputum cytokine. Increased sputum IL-1RA may be protective.

Tracheobronchial protease inhibitors, body surface area burns, and mortality in smoke inhalation.

The objective of this study was to assess tracheobronchial protease inhibitor concentrations longitudinally and determine whether initial concentrations predict subsequent lung injury and mortality in intubated burn victims. Tracheobronchial suction fluid was collected every 2 hours for 36 hours. Alpha-1-antitrypsin (AAT), secretory leukocyte peptidase inhibitor (SLPI), alpha-2-macroglobulin (A2M), and cell and differential counts were assayed. Partial pressure of oxygen in arterial blood/fraction of inspired oxygen (PaO2/FIO2) and peak airway pressure (PAP) were recorded for 72 hours. Standard statistics were used to evaluate cross-sectional relationships; random coefficient (mixed) models were used to evaluate temporal trends in marker concentrations and relation to clinical outcomes. Among 29 patients, 24 (83%) developed hypoxemia (PaO2/FIO2 <200); six died within 2 weeks. When adjusted for gender, age, %TBSA burn, and positive end-expiratory pressure setting, A2M (P = .007) and neutrophils (P = .032) increased linearly during 36 hours, and SLPI decreased (P = .038). Initial SLPI concentration was a negative predictor of maximum PAP (P = .009). None of the markers predicted longitudinal change in PaO2/FIO2. Mean levels of AAT and A2M in initial samples were significantly lower in patients with >35% TBSA burn (P = .010 and .033, respectively), when compared with patients with less severe burns. However, patients with increased A2M in combination with >35% TBSA burn had a 6-fold (95% CI: 1.8–20) increased relative risk of death. Tracheobronchial AAT and A2M levels were significantly lower in patients with more severe burns and increased over time. Initial SLPI levels predicted subsequent PAP. Increased early A2M in combination with extensive burn predicted early mortality.