Description and utilization of the United States department of defense serum repository: a review of published studies, 1985-2012

Multi-Autoantibody Testing Identifies Expansion of Reactivity to Targeted Antigens Before a Diagnosis of Rheumatoid Arthritis

OBJECTIVE

Rheumatoid arthritis (RA) has a "pre-RA" period in which multiple autoantibodies, including antibodies to citrullinated (cit) proteins (ACPA), rheumatoid factor (RF), anti-peptidyl arginine deiminase (anti-PAD), among others, have been described; however, few studies have tested all autoantibodies in a single pre-RA cohort. This study aims to evaluate the prevalence of multiple autoantibodies in pre-RA and potentially identify an autoantibody profile in pre-RA that indicates imminent onset of clinical RA.

METHODS

We evaluated 148 individuals with two pre- and one post-RA diagnosis samples available from the Department of Defense Serum Repository and matched controls. Samples were tested for immuglobulin (Ig) G anti-cyclic cit peptide-3 (anti-CCP3), five ACPA fine specificities, five anti-PAD isoforms, as well as RF IgA and RF IgM using commercial platforms; cutoffs were determined using levels present in <1% of controls.

RESULTS

Positivity of anti-CCP3, RF IgA and RF IgM, anti-PAD1, anti-cit-vimentin 2, anti-cit-fibrinogen, and anti-cit-histone 1 increased over time in pre-RA, although anti-PAD and ACPA fine specificities were predominately present within anti-CCP3-positive individuals. Within anti-CCP3-positive samples from the pre-RA period, positivity for RFs as well as anti-PAD and ACPA fine specificities classified samples as being closer to the time of RA diagnosis.

CONCLUSION

Multiple autoantibodies are present in pre-RA and increase in positivity as the time of RA diagnosis approaches. These results confirm previous findings predicting imminent RA and provide a pathway using commercial-grade assays to assess the risk for and timing of development of clinical RA.

Endocrine disrupting chemical mixture exposure and risk of papillary thyroid cancer in U.S. military personnel: A nested case-control study

Single-pollutant methods to evaluate associations between endocrine disrupting chemicals (EDCs) and thyroid cancer risk may not reflect realistic human exposures. Therefore, we evaluated associations between exposure to a mixture of 18 EDCs, including polychlorinated biphenyls (PCBs), brominated flame retardants, and organochlorine pesticides, and risk of papillary thyroid cancer (PTC), the most common thyroid cancer histological subtype. We conducted a nested case-control study among U.S. military servicemembers of 652 histologically-confirmed PTC cases diagnosed between 2000 and 2013 and 652 controls, matched on birth year, sex, race/ethnicity, military component (active duty/reserve), and serum sample timing. We estimated mixture odds ratios (OR), 95% confidence intervals (95% CI), and standard errors (SE) for associations between pre-diagnostic serum EDC mixture concentrations, overall PTC risk, and risk of histological subtypes of PTC (classical, follicular), adjusted for body mass index and military branch, using quantile g-computation. Additionally, we identified relative contributions of individual mixture components to PTC risk, represented by positive and negative weights (w). A one-quartile increase in the serum mixture concentration was associated with a non-statistically significant increase in overall PTC risk (OR = 1.19; 95% CI = 0.91, 1.56; SE = 0.14). Stratified by histological subtype and race (White, Black), a one-quartile increase in the mixture was associated with increased classical PTC risk among those of White race (OR = 1.59; 95% CI = 1.06, 2.40; SE = 0.21), but not of Black race (OR = 0.95; 95% CI = 0.34, 2.68; SE = 0.53). PCBs 180, 199, and 118 had the greatest positive weights driving this association among those of White race (w = 0.312, 0.255, and 0.119, respectively). Findings suggest that exposure to an EDC mixture may be associated with increased classical PTC risk. These findings warrant further investigation in other study populations to better understand PTC risk by histological subtype and race.

Organochlorine pesticides and risk of papillary thyroid cancer in U.S. military personnel: a nested case-control study

BACKGROUND

The effects of organochlorine pesticide (OCP) exposure on the development of human papillary thyroid cancer (PTC) are not well understood. A nested case-control study was conducted with data from the U.S. Department of Defense Serum Repository (DoDSR) cohort between 2000 and 2013 to assess associations of individual OCPs serum concentrations with PTC risk.

METHODS

This study included 742 histologically confirmed PTC cases (341 females, 401 males) and 742 individually-matched controls with pre-diagnostic serum samples selected from the DoDSR. Associations between categories of lipid-corrected serum concentrations of seven OCPs and PTC risk were evaluated for classical PTC and follicular PTC using conditional logistic regression, adjusted for body mass index category and military branch to compute odds ratios (OR) and 95% confidence intervals (CIs). Effect modification by sex, birth cohort, and race was examined.

RESULTS

There was no evidence of associations between most of the OCPs and PTC, overall or stratified by histological subtype. Overall, there was no evidence of an association between hexachlorobenzene (HCB) and PTC, but stratified by histological subtype HCB was associated with significantly increased risk of classical PTC (third tertile above the limit of detection (LOD) vs. Collapse

Key Words

• Hexachlorobenzene
• Hexachlorocyclohexane
• Organochlorine pesticides
• Papillary thyroid cancer

Collapse

MESH Headings

• Male
• Humans
• Female
• Military Personnel
• Thyroid Cancer, Papillary/epidemiology
• Hexachlorobenzene
• Case-Control Studies
• Pesticides
• Hydrocarbons, Chlorinated
• Thyroid Neoplasms/chemically induced
• Thyroid Neoplasms/epidemiology
• Hexachlorocyclohexane

Collapse

Grants

• R01ES020361 NIH HHS
• R01ES020361 NIH HHS
• National Institutes of Health
• Murtha Cancer Center Research Program
• Oak Ridge Associated Universities
• National Cancer Institute Intramural Research Program

Collapse

Affiliation(s)

Jennifer A Rusiecki Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Room E-2009, Bethesda, MD, 20814, USA.
Jordan McAdam Murtha Cancer Center Research Program, 4494 North Palmer Road, Bethesda, MD, USA Henry M. Jackson Foundation for the Advancement of Military Medicine, 1401 Rockville Pike, Rockville, MD, USA
Hristina Denic-Roberts Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Room E-2009, Bethesda, MD, 20814, USA Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN, USA
Andreas Sjodin Division of Laboratory Sciences, Centers for Disease Control and Prevention (CDC), Atlanta, GA, USA
Mark Davis Division of Laboratory Sciences, Centers for Disease Control and Prevention (CDC), Atlanta, GA, USA
Richard Jones Division of Laboratory Sciences, Centers for Disease Control and Prevention (CDC), Atlanta, GA, USA
Thanh D Hoang Division of Endocrinology, Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
Mary H Ward Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD, USA
Shuangge Ma Department of Biostatistics, Yale School of Public Health, New Haven, CT, USA
Yawei Zhang Department of Environmental Health Sciences, Yale School of Public Health, New Haven, CT, USA Department of Cancer Prevention and Control, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China

Collapse

Alpha-Gal IgE Prevalence Patterns in the United States: An Investigation of 3,000 Military Recruits

BACKGROUND

IgE to the oligosaccharide galactose-alpha-1,3-galactose (alpha-gal) is an important cause of allergic reactions to mammalian meat. The "alpha-gal syndrome" is strongly associated with a preceding history of tick bites and in the United States is most commonly reported in parts of the southeast, but there has been limited investigation into national alpha-gal sensitization patterns and the relevance of other risk factors.

OBJECTIVE

To systematically investigate alpha-gal IgE prevalence, regional patterns, and risk factors.

METHODS

Alpha-gal IgE was measured by ImmunoCAP in biobanked serum samples collected from 3000 service members who presented for intake to 1 of 10 military bases in the central/eastern United States. Alpha-gal IgE sensitization (cutoff 0.1 international units/mL) was related to home of record at enlistment.

RESULTS

Of the cohort, 2456 (81.9%) subjects were male, median age was 19 years (interquartile range: 18-22 years), and alpha-gal IgE was detected in 179 (6.0%). Home of record spanned all 50 states, with a median of 36 recruits per state (range: 3-261). The highest prevalence rates were in Arkansas (39%), Oklahoma (35%), and Missouri (29%), with several other southeastern states >10%. Granular mapping revealed sensitization patterns that closely mimicked county-level Amblyomma americanum reports and Ehrlichia chaffeensis infections. Sensitization was associated with male sex, rural residence, and White race in univariate and multivariable models.

CONCLUSIONS

In this systematic survey, the prevalence of alpha-gal IgE among incoming military personnel was 6.0%. There were significant regional differences, with an overall pattern consistent with the known range of the lone star tick (A. americanum) and highest frequency in an area including Arkansas, Oklahoma, and Missouri.

Elevated serum TARC levels precede classic Hodgkin lymphoma diagnosis by several years

Tumor cells in classic Hodgkin lymphoma produce high quantities of the thymus- and activation-related chemokine (TARC). We measured TARC levels in prediagnostic serum samples and found strikingly increased values in the vast majority of patients, as early as 6 years before diagnosis.

A Nested Case-Control Study of Serum Per- and Polyfluoroalkyl Substances and Testicular Germ Cell Tumors among U.S. Air Force Servicemen

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are a component of firefighting foams used at military installations. Although high PFAS exposures have been related to cancer risks among civilian populations, the effects for military personnel are unclear.

OBJECTIVES

We investigated associations between serum PFAS concentrations and testicular germ cell tumors (TGCT) among U.S. Air Force servicemen.

METHODS

This nested case-control study involved active-duty Air Force servicemen with sera from the Department of Defense Serum Repository. We selected 530 cases and 530 controls individually matched on birth date, race and ethnicity, year entered the service, and year of sample collection, with prediagnostic serum samples collected between 1988 and 2017. A second prediagnostic sample, collected a median of 4 y after the first, was selected for 187 case-control pairs. Seven PFAS were quantified using isotope-dilution tandem mass spectrometry. Odds ratios (ORs) and 95% confidence intervals (CIs) from conditional logistic regression adjusting for military grade, number of deployments, and, in some models, other PFAS, estimated associations between PFAS concentrations (categorized using quartiles among controls) and TGCT.

RESULTS

Elevated concentrations of some PFAS were observed for military employment in firefighting [perfluorooctanesulfonic acid (PFOS), perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid] and service at a base with high PFAS concentrations in drinking water (PFHxS). Elevated PFOS concentrations in the second sample were positively associated with TGCT [OR for fourth vs. first quartile ( OR Q 4 ) = 2.6 , 95% CI: 1.1, 6.4; p trend = 0.02 ], including after adjustment for other PFAS (OR Q 4 = 4.6 , 95% CI: 1.4, 15.1; p trend = 0.009 ). Associations with PFOS in the first/only samples were weak and not statistically significant. Elevated concentrations of perfluorononanoic acid were inversely associated with TGCT, whereas results were null for other PFAS.

DISCUSSION

We identified service-related predictors of PFAS concentrations and increased TGCT relative risks with elevated PFOS concentrations among Air Force servicemen. These findings warrant further investigation in other populations and military service branches. https://doi.org/10.1289/EHP12603.

Military occupation and testicular germ cell tumour risk among US Air Force servicemen

OBJECTIVES

Testicular germ cell tumours (TGCTs) are the most commonly diagnosed malignancy among active duty US military servicemen. Occupational risk factors may play a role in TGCT aetiology, although the evidence is inconclusive. The objective of our study was to investigate associations between military occupations and TGCT risk among US Air Force (USAF) servicemen.

METHODS

This nested case-control study among active duty USAF servicemen obtained information on military occupations for 530 histologically confirmed TGCT cases diagnosed during 1990-2018 and 530 individually matched controls. We determined military occupations using Air Force Specialty Codes ascertained at two time points: at case diagnosis and at a time point on average 6 years earlier. We computed adjusted ORs and 95% CIs from conditional logistic regression models to evaluate associations between occupations and TGCT risk.

RESULTS

The mean age at TGCT diagnosis was 30 years. Increased TGCT risk was observed for pilots (OR=2.84, 95% CI: 1.20-6.74) and servicemen with aircraft maintenance jobs (OR=1.85, 95% CI: 1.03-3.31) who held those jobs at both time points. Fighter pilots (n=18) and servicemen with firefighting jobs (n=18) at the time of case diagnosis had suggestively elevated TGCT odds (OR=2.73, 95% CI: 0.96-7.72 and OR=1.94, 95% CI: 0.72-5.20, respectively).

CONCLUSIONS

In this matched, nested case-control study of young active duty USAF servicemen, we found that pilots and men with aircraft maintenance jobs had elevated TGCT risk. Further research is needed to elucidate specific occupational exposures underlying these associations.

Vitamin D status in active duty Navy military personnel: a systematic review

OBJECTIVES

Active duty Navy military personnel are prone to vitamin D deficiency due to an occupational environment detrimental to sunlight exposure. The main objective of this systematic review is to provide a worldwide overview of vitamin D status in this population.

METHODS

The Condition, Context, Population (CoCoPop) mnemonic was used to define the inclusion criteria (vitamin D status; all contexts; active duty Navy military personnel). Studies with recruits or veterans were excluded. Scopus, Web of Science and PubMed/Medline databases were searched from inception to 30 June 2022. Joanna Briggs Institute and Downs & Black checklists were used for quality assessment and data were synthesised in narrative and tabular formats.

RESULTS

Thirteen studies published between 1975 and 2022 and conducted in northern hemisphere Navies, including mainly young and male service members, were included. The prevalence of vitamin D deficiency was globally reported as significant. Nine studies included a total of 305 male submariners who performed 30-92 days submarine patrol and reported the effect of sunlight deprivation in the decrease of vitamin D levels.

CONCLUSIONS

This new systematic review underlines the high prevalence of vitamin D deficiency in the Navy, especially in submariners, and the need to implement measures to prevent vitamin D deficiency. Serum 25(OH)D data available and the heterogeneity of the studies limited a pooled analysis. Most studies included only submariners, which may limit generalisability to all active duty Navy military personnel. Further research on this topic should be promoted.

PROSPERO REGISTRATION NUMBER

CRD42022287057.

Longitudinal Changes in Immune Activation Serum Biomarkers Prior to Diagnosis and Risk of B-cell NHL Subtypes

BACKGROUND

To examine the contribution of B-cell activation molecules to B-cell follicular lymphoma (FL) and diffuse large B-cell lymphoma (DLBCL), a prospective study was conducted using pre-diagnosis serial serum samples from the US Department of Defense Serum Repository.

METHODS

Each case (n = 142 FL, n = 211 DLBCL) was matched to two controls on age, gender, race, military branch, and blood collection dates. Immune activation molecules (IL1β, IL2, IL4, IL5, IL6, IL10, IL12, CXCL13, IL8, TNFα, IFNγ, GM-CSF, VEGF, sCD30, IgE) were quantified using ELISA or multiplex immunometric (Luminex) assay. Longitudinal data were analyzed using linear mixed modeling. As serial specimens were collected over several years before diagnosis, we evaluated the temporal dynamics of these markers.

RESULTS

Increased serum levels of sCD30, CXCL13, and to a lesser extent IL10, were associated with both FL and DLBCL in cases compared with controls, with a median follow-up of 5.5 years from the earliest specimen collection to diagnosis date. Significant increasing sCD30 and CXCL13 trajectories for FL and DLBCL subtypes were noted starting at the earliest time points and with IL10 levels increasing significantly at time points closer to diagnosis.

CONCLUSIONS

These results suggest that sCD30, CXCL13, and IL10 may contribute to the etiology of FL and DLBCL and are potential biomarkers for these non-Hodgkin lymphoma subtypes.

IMPACT

The increasing trajectories of the B-cell activation molecules, sCD30, CXCL13, and to a lesser extent IL10, may indicate early disease-induced effects or reflect the chronic stimulation of B-cells that promotes the development of FL and DLBCL subtypes.

Antibodies to Citrullinated Protein Antigens, Rheumatoid Factor Isotypes and the Shared Epitope and the Near-Term Development of Clinically-Apparent Rheumatoid Arthritis

Background/Purpose

In rheumatoid arthritis (RA) autoantibodies including antibodies to citrullinated protein antigens (ACPA) and rheumatoid factor (RF) can be predictive of incident clinical RA. However, there is limited understanding of how antibody changes over time impact prediction of the likelihood and timing of future clinical RA.

Materials and Methods

We evaluated relationships between ACPA, the shared epitope (SE), RF isotypes and incident RA in a prospective cohort of 90 ACPA(+) individuals without baseline arthritis identified through health-fair testing (i.e. Healthfair). We also evaluated ACPA and RF isotypes and time-to-diagnosis of RA in a retrospective cohort of 215 individuals with RA from the Department of Defense Serum Repository (DoDSR).

Results

Twenty-six of 90 (29%) of ACPA(+) Healthfair participants developed incident RA. Baseline or incident dual RF-IgA and RF-IgM positivity was associated with increased risk for incident RA (HR 3.09; 95% CI 1.15 to 8.29) although RFs were negative in ~50% of individuals with incident RA. SE was associated with increased risk of RA (HR 2.87, 95% CI 1.22-6.76). In the DoDSR cohort, triple positivity for ACPA, RF-IgA and RF-IgM was present a median of 1-2 years prior to RA diagnosis, with some sex-specific differences.

Conclusion

These findings can be used to counsel individuals at-risk for future RA and to design clinical trials for RA prevention. The findings also suggest that RF could be a surrogate outcome as a success of an immunologic intervention in RA prevention. Additional studies are needed to understand the biologic of different patterns of autoantibody elevations in RA evolution.

Circulating plasma metabolites and risk of rheumatoid arthritis in the Nurses' Health Study

OBJECTIVES

RA develops slowly over years. We tested for metabolic changes prior to RA onset using a large non-targeted metabolomics platform to identify novel pathways and advance understanding of RA development.

METHODS

Two hundred and fifty-four incident RA cases with plasma samples drawn pre-RA onset in the Nurses' Health Study (NHS) cohorts were matched 1:2 to 501 controls on age, race, menopause/post-menopausal hormone use and blood collection features. Relative abundances of 360 unique, known metabolites were measured. Conditional logistic regression analyses assessed associations between metabolites and incidence of RA, adjusted for age, smoking and BMI, accounting for multiple comparisons. Subgroup analyses investigated seropositive (sero+) RA and RA within 5 years of sample collection. Significant metabolites were then tested in a female military pre-RA case-control study (n = 290).

RESULTS

In the NHS, metabolites associated with RA and sero+RA in multivariable models included 4-acetamidobutanoate (odds ratio (OR) = 0.80/S.d., 95% CI: 0.66, 0.95), N-acetylputrescine (OR = 0.82, 95% CI: 0.69, 0.96), C5 carnitine (OR = 0.84, 95% CI: 0.71, 0.99) and C5:1 carnitine (OR = 0.81, 95% CI: 0.68, 0.95). These were involved primarily in polyamine and leucine, isoleucine and valine metabolism. Several metabolites associated with sero+RA within 5 years of diagnosis were replicated in the independent military cohort: C5 carnitine (OR = 0.55, 95% CI: 0.33, 0.92), C5:1 carnitine (OR = 0.62, 95% CI: 0.39, 0.99) and C3 carnitine (OR = 0.57, 95% CI: 0.36, 0.91).

CONCLUSION

Several metabolites were inversely associated with incidence of RA among women. Three short-chain acylcarnitines replicated in a smaller dataset and may reflect inflammation in the 5-year period prior to sero+RA diagnosis.

Respiratory Health after Military Service in Southwest Asia and Afghanistan. An Official American Thoracic Society Workshop Report

Since 2001, more than 2.7 million U.S. military personnel have been deployed in support of operations in Southwest Asia and Afghanistan. Land-based personnel experienced elevated exposures to particulate matter and other inhalational exposures from multiple sources, including desert dust, burn pit combustion, and other industrial, mobile, or military sources. A workshop conducted at the 2018 American Thoracic Society International Conference had the goals of: 1) identifying key studies assessing postdeployment respiratory health, 2) describing emerging research, and 3) highlighting knowledge gaps. The workshop reviewed epidemiologic studies that demonstrated more frequent encounters for respiratory symptoms postdeployment compared with nondeployers and for airway disease, predominantly asthma, as well as case series describing postdeployment dyspnea, asthma, and a range of other respiratory tract findings. On the basis of particulate matter effects in other populations, it also is possible that deployers experienced reductions in pulmonary function as a result of such exposure. The workshop also gave particular attention to constrictive bronchiolitis, which has been reported in lung biopsies of selected deployers. Workshop participants had heterogeneous views regarding the definition and frequency of constrictive bronchiolitis and other small airway pathologic findings in deployed populations. The workshop concluded that the relationship of airway disease, including constrictive bronchiolitis, to exposures experienced during deployment remains to be better defined. Future clinical and epidemiologic research efforts should address better characterization of deployment exposures; carry out longitudinal assessment of potentially related adverse health conditions, including lung function and other physiologic changes; and use rigorous histologic, exposure, and clinical characterization of patients with respiratory tract abnormalities.

Environmental Chemicals Altered in Association With Deployment for High Risk Areas

OBJECTIVE

A study was conducted using serum samples and high-resolution metabolomics (HRM) to test for changes in abundance of environmental chemicals in deployment in high-risk areas (Balad, Iraq; Bagram, Afghanistan).

METHODS

Pre and Post-deployment serum samples for deployment (cases) and matched controls stationed domestically were analyzed by HRM and bioinformatics for the relative abundance of 271 environmental chemicals.

RESULTS

Of the 271 chemicals, 153 were measurable in at least 80% of the samples in one of the pre- or post-deployment groups. Several pesticides and other chemicals were modestly elevated post-deployment in the Control as well as the Bagram and Balad samples. Similarly, small decreases were seen for some chemicals.

CONCLUSION

These results using serum samples show that for the 271 environmental chemicals studied, 56% were detected and small differences occurred with deployment to high-risk areas.

Advances in Comprehensive Exposure Assessment: Opportunities for the US Military

OBJECTIVE

Review advances in exposure assessment offered by the exposome concept and new -omics and sensor technologies.

METHODS

Narrative review of advances, including current efforts and potential future applications by the US military.

RESULTS

Exposure assessment methods from both bottom-up and top-down exposomics approaches are advancing at a rapid pace, and the US military is engaged in developing both approaches. Top-down approaches employ various -omics technologies to identify biomarkers of internal exposure and biological effect. Bottom-up approaches use new sensor technology to better measure external dose. Key challenges of both approaches are largely centered around how to integrate, analyze, and interpret large datasets that are multidimensional and disparate.

CONCLUSIONS

Advances in -omics and sensor technologies may dramatically enhance exposure assessment and improve our ability to characterize health risks related to occupational and environmental exposures, including for the US military.

Metabolome-Wide Association Study of Deployment to Balad, Iraq or Bagram, Afghanistan

OBJECTIVE

To use high-resolution metabolomics (HRM) to identify metabolic changes in military personnel associated with deployment to Balad, Iraq, or Bagram, Afghanistan.

METHODS

Pre- and post-deployment samples were obtained from the Department of Defense Serum Repository (DoDSR). HRM and bioinformatics were used to identify metabolic differences associated with deployment.

RESULTS

Differences at baseline (pre-deployment) between personnel deployed to Bagram compared with Balad or Controls included sex hormone and keratan sulfate metabolism. Deployment to Balad was associated with alterations to amino acid and lipid metabolism, consistent with inflammation and oxidative stress, and pathways linked to metabolic adaptation and repair. Difference associated with deployment to Bagram included lipid pathways linked to cell signaling and inflammation.

CONCLUSIONS

Metabolic variations in pre- and post-deployment are consistent with deployment-associated responses to air pollution and other environmental stressors.

Integrative Network Analysis Linking Clinical Outcomes With Environmental Exposures and Molecular Variations in Service Personnel Deployed to Balad and Bagram

OBJECTIVE

To develop a computational approach to link clinical outcomes with environmental exposures and molecular variations measured in Department of Defense (DOD) serum-repository samples.

METHODS

International Classification of Diseases, Ninth Division codes which corresponded to cardiopulmonary symptoms for service personnel were selected to test for associations with deployment-related inhalation hazards and metabolomics, micro-RNA, cytokine, plasma markers, and environmental exposure analyses for corresponding samples. xMWAS and Mummichog were used for integrative network and pathway analysis.

RESULTS

Comparison between 41 personnel exhibiting new cardio-pulmonary diagnoses after deployment start-date to 25 personnel exhibiting no symptoms identified biomarkers associated with cardiopulmonary conditions. Integrative network and pathway analysis showed communities of clinical, molecular, and environmental markers associated with fatty acid, lipid, nucleotide, and amino acid metabolism pathways.

CONCLUSIONS

The current proof of principle study establishes a computational framework for integrative analysis of deployment-related exposures, molecular responses, and health outcomes.

Detection of Head and Neck Cancer Based on Longitudinal Changes in Serum Protein Abundance

BACKGROUND

Approximately 85% of the U.S. military active duty population is male and less than 50 years of age, with elevated levels of known risk factors for oropharyngeal squamous cell carcinoma (OPSCC), including smoking, excessive use of alcohol, and greater numbers of sexual partners, and elevated prevalence of human papilloma virus (HPV). Given the recent rise in incidence of OPSCC related to the HPV, the Department of Defense Serum Repository provides an unparalleled resource for longitudinal studies of OPSCC in the military for the identification of early detection biomarkers.

METHODS

We identified 175 patients diagnosed with OPSCC with 175 matched healthy controls and retrieved a total of 978 serum samples drawn at the time of diagnosis, 2 and 4 years prior to diagnosis, and 2 years after diagnosis. Following immunoaffinity depletion, serum samples were analyzed by targeted proteomics assays for multiplexed quantification of a panel of 146 candidate protein biomarkers from the curated literature.

RESULTS

Using a Random Forest machine learning approach, we derived a 13-protein signature that distinguishes cases versus controls based on longitudinal changes in serum protein concentration. The abundances of each of the 13 proteins remain constant over time in control subjects. The AUC for the derived Random Forest classifier was 0.90.

CONCLUSIONS

This 13-protein classifier is highly promising for detection of OPSCC prior to overt symptoms.

IMPACT

Use of longitudinal samples has significant potential to identify biomarkers for detection and risk stratification.

Cholera in travellers: a systematic review

Exposure to cholera is a risk for individuals and groups travelling to endemic areas, and the bacteria can be imported to cholera-free countries by returning travellers. This systematic review of the literature describes the circumstances in which cholera infection can occur in travellers and considers the possible value of the cholera vaccine for prevention in travellers. PubMed and EMBASE were searched for case reports of cholera or diarrhoea among travellers, with date limits of 1 January 1990-30 April 2018. Search results were screened to exclude the following articles: diarrhoea not caused by cholera, cholera in animals, intentional cholera infection in humans, non-English articles and publications on epidemics that did not report clinical details of individual cases and publications of cases pre-dating 1990. Articles were reviewed through descriptive analytic methods and information summarized. We identified 156 cases of cholera imported as a consequence of travel, and these were reviewed for type of traveller, source country, serogroup of cholera, treatment and outcomes. The case reports retrieved in the search did not report consistent levels of detail, making it difficult to synthesize data across reports and draw firm conclusions from the data. This clinical review sheds light on the paucity of actionable published data regarding the risk of cholera in travellers and identifies a number of gaps that should drive additional effort. Further information is needed to better inform evidence-based disease prevention strategies, including vaccination for travellers visiting areas of cholera risk. Modifications to current vaccination recommendations to include or exclude current or additional traveller populations may be considered as additional risk data become available. The protocol for this systematic review is registered with PROSPERO (registration number: 122797).

Emerging Challenges and Opportunities in Infectious Disease Epidemiology

Much of the intellectual tradition of modern epidemiology stems from efforts to understand and combat chronic diseases persisting through the 20th century epidemiologic transition of countries such as the United States and United Kingdom. After decades of relative obscurity, infectious disease epidemiology has undergone an intellectual rebirth in recent years amid increasing recognition of the threat posed by both new and familiar pathogens. Here, we review the emerging coalescence of infectious disease epidemiology around a core set of study designs and statistical methods bearing little resemblance to the chronic disease epidemiology toolkit. We offer our outlook on challenges and opportunities facing the field, including the integration of novel molecular and digital information sources into disease surveillance, the assimilation of such data into models of pathogen spread, and the increasing contribution of models to public health practice. We next consider emerging paradigms in causal inference for infectious diseases, ranging from approaches to evaluating vaccines and antimicrobial therapies to the task of ascribing clinical syndromes to etiologic microorganisms, an age-old problem transformed by our increasing ability to characterize human-associated microbiota. These areas represent an increasingly important component of epidemiology training programs for future generations of researchers and practitioners.

MicroRNA Expression Profiling of the Armed Forces Health Surveillance Branch Cohort for Identification of "Enviro-miRs" Associated With Deployment-Based Environmental Exposure

OBJECTIVE

The aim of this study was to identify serum microRNA (miRNA) biomarkers that indicate deployment-associated exposures in service members at military installations with open burn pits. Another objective was to determine detection rates of miRNAs in Department of Defense Serum Repository (DoDSR) samples with a high-throughput methodology.

METHODS

Low-volume serum samples (n = 800) were profiled by miRNA-capture isolation, pre-amplification, and measurement by a quantitative PCR-based OpenArray platform. Normalized quantitative cycle values were used for differential expression analysis between groups.

RESULTS

Assay specificity, dynamic range, reproducibility, and detection rates by OpenArray passed target desired specifications. Serum abundant miRNAs were consistently measured in study specimens. Four miRNAs were differentially expressed in the case deployment group subjects.

CONCLUSIONS

miRNAs are suitable RNA species for biomarker discovery in the DoDSR serum specimens. Serum miRNAs are candidate biomarkers for deployment and environmental exposure in military service members.

Utility of the Department of Defense Serum Repository in Assessing Deployment Exposure

OBJECTIVE

This paper describes why the research project was conducted in terms of demonstrating the utility of the Department of Defense Serum Repository in addressing deployment environmental exposures.

METHODS

The history deployment exposure surveillance was reviewed and the rationale for developing validated biomarkers that were detected in sera in postdeployment samples and compared with nondeployed controls was described. The goal was to find validated biomarkers that are associated with both exposures and health outcomes.

RESULTS

The articles in this supplement described novel serum biomarkers that were found to be associated with deployment exposures and weakly associated with some health outcomes.

CONCLUSIONS

Future research must continue to validate the use of serum biomarkers when operational contingencies prevent the gold standard collection of real-time breathing zone samples in deployed service members.

Detection of Serum microRNAs From Department of Defense Serum Repository: Correlation With Cotinine, Cytokine, and Polycyclic Aromatic Hydrocarbon Levels

OBJECTIVE

The aim of this study was to investigate whether serum samples from the Department of Defense Serum Repository (DoDSR) are of sufficient quality to detect microRNAs (miRNAs), cytokines, immunoglobulin E (IgE), and polycyclic aromatic hydrocarbons (PAHs).

METHODS

MiRNAs were isolated and quantified by polymerase chain reaction (PCR) array. Cytokines and chemokines related to inflammation were measured using multiplex immunoassays. Cotinine and IgE were detected by enzyme-linked immunoassay (ELISA) and PAHs were detected by Liquid Chromatography/Mass Spectroscopy.

RESULTS

We detected miRNAs, cytokines, IgE, and PAHs with high sensitivity. Eleven of 30 samples tested positive for cotinine suggesting tobacco exposure. Significant associations between serum cotinine, cytokine, IgE, PAHs, and miRNA were discovered.

CONCLUSION

We successfully quantified over 200 potential biomarkers of occupational exposure from DoDSR samples. The stored serum samples were not affected by hemolysis and represent a powerful tool for biomarker discovery and analysis in retrospective studies.

Metabolic Pathways and Networks Associated With Tobacco Use in Military Personnel

OBJECTIVE

The aim of this study is to use high-resolution metabolomics (HRM) to identify metabolic pathways and networks associated with tobacco use in military personnel.

METHODS

Four hundred deidentified samples obtained from the Department of Defense Serum Repository were classified as tobacco users or nonusers according to cotinine content. HRM and bioinformatic methods were used to determine pathways and networks associated with classification.

RESULTS

Eighty individuals were classified as tobacco users compared with 320 nonusers on the basis of cotinine levels at least 10 ng/mL. Alterations in lipid and xenobiotic metabolism, and diverse effects on amino acid, sialic acid, and purine and pyrimidine metabolism were observed. Importantly, network analysis showed broad effects on metabolic associations not simply linked to well-defined pathways.

CONCLUSIONS

Tobacco use has complex metabolic effects that must be considered in evaluation of deployment-associated environmental exposures in military personnel.

Pilot Metabolome-Wide Association Study of Benzo(a)pyrene in Serum From Military Personnel

OBJECTIVE

A pilot study was conducted to test the feasibility of using Department of Defense Serum Repository (DoDSR) samples to study health and exposure-related effects.

METHODS

Thirty unidentified human serum samples were obtained from the DoDSR and analyzed for normal serum metabolites with high-resolution mass spectrometry and serum levels of free benzo(a)pyrene (BaP) by gas chromatography-mass spectrometry. Metabolic associations with BaP were determined using a metabolome-wide association study (MWAS) and metabolic pathway enrichment.

RESULTS

The serum analysis detected normal ranges of glucose, selected amino acids, fatty acids, and creatinine. Free BaP was detected in a broad concentration range. MWAS of BaP showed associations with lipids, fatty acids, and sulfur amino acid metabolic pathways.

CONCLUSION

The results show that the DoDSR samples are of sufficient quality for chemical profiling of DoD personnel.

High-Resolution Metabolomics Assessment of Military Personnel: Evaluating Analytical Strategies for Chemical Detection

OBJECTIVE

The aim of this study was to maximize detection of serum metabolites with high-resolution metabolomics (HRM).

METHODS

Department of Defense Serum Repository (DoDSR) samples were analyzed using ultrahigh resolution mass spectrometry with three complementary chromatographic phases and four ionization modes. Chemical coverage was evaluated by number of ions detected and accurate mass matches to a human metabolomics database.

RESULTS

Individual HRM platforms provided accurate mass matches for up to 58% of the KEGG metabolite database. Combining two analytical methods increased matches to 72% and included metabolites in most major human metabolic pathways and chemical classes. Detection and feature quality varied by analytical configuration.

CONCLUSIONS

Dual chromatography HRM with positive and negative electrospray ionization provides an effective generalized method for metabolic assessment of military personnel.

25-hydroxyvitamin D, influenza vaccine response and healthcare encounters among a young adult population

BACKGROUND

Influenza causes significant morbidity and mortality; the pandemic in 2009-2010 was a reminder of the potential for novel strains and antigenic changes. Studies have shown that vitamin D deficiency may be associated with poor vaccine immunogenicity, therefore we sought to determine if there was a correlation between 25-hydroxyvitamin D [25(OH)D] and influenza vaccine response.

METHODS

A retrospective observational study was conducted among young, healthy military members to evaluate the association between total 25(OH)D levels with post influenza vaccination antibody titers and healthcare encounters during the 2009-10 influenza season. Univariate analyses were performed to evaluate whether 25(OH)D levels are associated with baseline characteristics and post-vaccination antibody responses. Multivariable logistic regression models were utilized to determine the associations between antibody responses and 25(OH)D levels adjusting for possible confounders.

RESULTS

A total of 437 subjects were studied. Most participants were young adults (91% were 18-39 years of age), 50% were male, and 56% resided in the southern U.S. Overall, 152 (34.8%) were vitamin D deficient, 167 (38.2%) insufficient, and 118 (27.0%) with normal 25(OH)D levels. There were no demographic differences by 25(OH)D category. Only 224 (51.3%) demonstrated a seroprotective anti-influenza post-vaccination titer, which did not vary by categorical 25(OH)D levels [vitamin D deficient vs. normal: OR 1.10 (0.68-1.78) and insufficient vs. normal: OR 1.25 (0.78-2.01)] or continuous vitamin D levels [OR 0.98 (0.84-1.15)]. There were also no associations with increased influenza like illnesses, respiratory diagnoses and healthcare encounters between the vitamin D groups.

CONCLUSION

Vitamin D insufficiency and deficiency were highly prevalent despite evaluating a young, healthy adult population. There were no significant associations between 25(OH)D levels and post-vaccination antibody titers to influenza vaccine. Further studies are required to discover strategies to improve vaccine efficacy as well as to determine the role of 25(OH)D in vaccine immunity.

Thyroid-Stimulating Hormone, Thyroid Hormones, and Risk of Papillary Thyroid Cancer: A Nested Case-Control Study

Background: The effects of thyroid-stimulating hormone (TSH) and thyroid hormones on the development of human papillary thyroid cancer (PTC) remain poorly understood.Methods: The study population consisted of 741 (341 women, 400 men) histologically confirmed PTC cases and 741 matched controls with prediagnostic serum samples stored in the Department of Defense Serum Repository. Concentrations of TSH, total T3, total T4, and free T4 were measured in serum samples. Conditional logistic regression models were used to calculate ORs and 95% confidence intervals (CI).Results: The median time between blood draw and PTC diagnosis was 1,454 days. Compared with the middle tertile of TSH levels within the normal range, serum TSH levels below the normal range were associated with an elevated risk of PTC among women (OR, 3.74; 95% CI, 1.53-9.19) but not men. TSH levels above the normal range were associated with an increased risk of PTC among men (OR, 1.96; 95% CI, 1.04-3.66) but not women. The risk of PTC decreased with increasing TSH levels within the normal range among both men and women (P_trend = 0.0005 and 0.041, respectively).Conclusions: We found a significantly increased risk of PTC associated with TSH levels below the normal range among women and with TSH levels above the normal range among men. An inverse association between PTC and TSH levels within the normal range was observed among both men and women.Impact: These results could have significant clinical implications for physicians who are managing patients with abnormal thyroid functions and those with thyroidectomy. Cancer Epidemiol Biomarkers Prev; 26(8); 1209-18. ©2017 AACR.

Elevated Serum Levels of sCD30 and IL6 and Detectable IL10 Precede Classical Hodgkin Lymphoma Diagnosis

Background: We investigated whether an immune system environment characterized by elevated serum levels of B-cell activation molecules was associated with the subsequent development of classical Hodgkin lymphoma (cHL).Methods: We measured serum levels of B-cell-stimulatory cytokines, IL6 and IL10, soluble CD30 (sCD30), and total IgE prior to cHL diagnosis in 103 cases and 206 matched controls with archived specimens in the DoD Serum Repository.Results: Prediagnosis serum sCD30 and IL6 levels had strong positive associations with risk of a cHL diagnosis 0 to 1 year prior to diagnosis [sCD30 OR = 5.5; 95% confidence interval (CI), 3.4-9.0; IL6 OR = 4.6; 95% CI, 2.9-7.5] and >1 year to 2 years pre-cHL diagnosis (sCD30 OR = 3.3; 95% CI, 1.6-6.7; IL6 OR = 2.9; 95% CI, 1.3-6.5). We observed similar, albeit not consistently significant positive associations, over 4 or more years preceding diagnosis. We did not observe a clear association with IgE levels. Of note, detectable IL10 levels were significantly associated with Epstein-Barr virus (EBV)-positive cHL cases compared with EBV-negative cases.Conclusion: In this prospective analysis, elevated sCD30 and IL6 levels and detectable IL10 preceded cHL diagnosis.Impact: The associations of these cytokines with cHL risk may reflect the production of these molecules by proliferating nascent cHL tumor cells, or by immune cells responding to their presence, prior to clinical detection. The stable elevation in cHL risk, 4 or more years prediagnosis, also suggests that a B-cell-stimulatory immune system milieu precedes, and may promote, lymphomagenesis. Cancer Epidemiol Biomarkers Prev; 26(7); 1114-23. ©2017 AACR.

Deployment-Associated Exposure Surveillance With High-Resolution Metabolomics

OBJECTIVE

The aim of this study was to assess the suitability of high-resolution metabolomics (HRM) for measure of internal exposure and effect biomarkers from deployment-related environmental hazards.

METHODS

HRM provides extensive coverage of metabolism and data relevant to a broad spectrum of environmental exposures. This review briefly describes the analytic platform, workflow, and recent applications of HRM as a prototype environmental exposure surveillance system.

RESULTS

Building upon techniques available for contemporary occupational medicine and exposure sciences, HRM methods are able to integrate external exposures, internal body burden of environmental agents, and relevant biological responses with health outcomes.

CONCLUSIONS

Systematic analysis of existing Department of Defense Serum Repository samples will provide a high-quality, cross-sectional reference dataset for deployment-associated exposures while at the same time establishing a foundation for precision medicine.

Polycyclic Aromatic Hydrocarbons and Polychlorinated Dibenzo-p-Dioxins/Dibenzofurans in Microliter Samples of Human Serum as Exposure Indicators

OBJECTIVE

The objectives were: 1) measure polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in 100 μL of human serum and 2) assess PAH and PCDD/PCDF as markers of burn pit exposures during military deployments.

METHODS

PAHs and PCDDs/PCDFs were analyzed in 100 μL serum samples collected pre- and post-deployment from 200 persons deployed to Iraq or Afghanistan (CASE); 200 persons not deployed (CONTROL) with gas chromatography/mass spectrometry.

RESULTS

Naphthalene was found in ∼83% of the samples and was statistically different between post-deployment CASE personnel and pre-deployment. 1,2,3,4,6,7,8-Heptachlorodibenzo-p-dioxin, Octachlorodibenzo-p-dioxin, 1,2,3,7,8,9-Hexachlorodibenzofuran, and 1,2,3,4,6,7,8-Heptachlorodibenzofuran were found in ∼38% of samples. Concentrations were significantly different between CASE and CONTROL and between pre- and post-deployment samples.

CONCLUSIONS

PAH and PCDD/PCDF in serum can serve as exposure markers and measurements in small volumes is feasible for quantifying exposure to burn pits.

Towards a blood-based diagnostic panel for bipolar disorder

BACKGROUND

Bipolar disorder (BD) is a costly, devastating and life shortening mental disorder that is often misdiagnosed, especially on initial presentation. Misdiagnosis frequently results in ineffective treatment. We investigated the utility of a biomarker panel as a diagnostic test for BD.

METHODS AND FINDINGS

We performed a meta-analysis of eight case-control studies to define a diagnostic biomarker panel for BD. After validating the panel on established BD patients, we applied it to undiagnosed BD patients. We analysed 249 BD, 122 pre-diagnostic BD, 75 pre-diagnostic schizophrenia and 90 first onset major depression disorder (MDD) patients and 371 controls. The biomarker panel was identified using ten-fold cross-validation with lasso regression applied to the 87 analytes available across the meta-analysis studies. We identified 20 protein analytes with excellent predictive performance [area under the curve (AUC)⩾0.90]. Importantly, the panel had a good predictive performance (AUC 0.84) to differentiate 12 misdiagnosed BD patients from 90 first onset MDD patients, and a fair to good predictive performance (AUC 0.79) to differentiate between 110 pre-diagnostic BD patients and 184 controls. We also demonstrated the disease specificity of the panel.

CONCLUSIONS

An early and accurate diagnosis has the potential to delay or even prevent the onset of BD. This study demonstrates the potential utility of a biomarker panel as a diagnostic test for BD.