Longitudinal stability in cigarette smokers of urinary eicosanoid biomarkers of oxidative damage and inflammation

Association of Urinary Biomarkers of Tobacco Exposure with Lung Cancer Risk in African American and White Cigarette Smokers in the Southern Community Cohort Study

BACKGROUND

After accounting for smoking history, lung cancer incidence is greater in African Americans than Whites. In the multiethnic cohort, total nicotine equivalents (TNE) are higher in African Americans than Whites at similar reported cigarettes per day. Greater toxicant uptake per cigarette may contribute to the greater lung cancer risk of African Americans.

METHODS

In a nested case-control lung cancer study within the Southern Community Cohort, smoking-related biomarkers were measured in 259 cases and 503 controls (40% White; 56% African American). TNE, the trans-3-hydroxycotinine/cotinine ratio, 4-(methylnitrosamino)-1-3-(pyridyl)-1-butanol (NNAL), mercapturic acid metabolites of volatile organic compounds, phenanthrene metabolites, cadmium (Cd), and (Z)-7-(1R,2R,3R,5S)-3,5-dihydroxy-2-[(E,3S)-3-hydroxyoct-1-enyl]cyclopenyl]hept-5-enoic acid were quantified in urine. Unconditional logistic regression was used to estimate the ORs and 95% confidence intervals (CI) for each biomarker and lung cancer risk.

RESULTS

TNE, NNAL, and Cd were higher in cases than controls (adjusted for age, race, sex, body mass index, and cigarettes per day). Among cases, these levels were higher in African Americans compared with Whites. After accounting for age, sex, body mass index, and pack-years, a one-SD increase in log-TNE (OR = 1.30; 95% CI, 1.10-1.54) and log-NNAL (OR = 1.27; 95% CI, 1.03-1.58 with TNE adjustment) was associated with lung cancer risk. In this study, in which NNAL concentration is relatively high, the association for log-TNE was attenuated after adjustment for log-NNAL.

CONCLUSIONS

Smoking-related biomarkers provide additional information for lung cancer risk in smokers beyond smoking pack-years.

IMPACT

Urinary NNAL, TNE, and Cd concentrations in current smokers, particularly African American smokers, may be useful for predicting lung cancer risk.

The Metabolomic Profile of Microscopic Colitis Is Affected by Smoking but Not Histopathological Diagnosis, Clinical Course, Symptoms, or Treatment

Microscopic colitis (MC) is classified as collagenous colitis (CC) and lymphocytic colitis (LC). Genetic associations between CC and human leucocyte antigens (HLAs) have been found, with smoking being a predisposing external factor. Smoking has a great impact on metabolomics. The aim of this explorative study was to analyze global metabolomics in MC and to examine whether the metabolomic profile differed regarding the type and course of MC, the presence of IBS-like symptoms, treatment, and smoking habits. Of the 240 identified women with MC aged ≤73 years, 131 completed the study questionnaire; the Rome III questionnaire; and the Visual Analog Scale for Irritable Bowel Syndrome (VAS-IBS). Blood samples were analyzed by ultra-high-performance liquid chromatograph mass spectrometry (UHLC-MS/UHPLC-MSMS). The women, 63.1 (58.7-67.2) years old, were categorized based on CC (n = 76) and LC (n = 55); one episode or refractory MC; IBS-like symptoms or not; use of corticosteroids or not; and smoking habits. The only metabolomic differences found in the univariate model after adjustment for false discovery rate (FDR) were between smokers and non-smokers. Serotonin was markedly increased in smokers (p < 0.001). No clear patterns appeared when conducting a principal component analysis (PCA). No differences in the metabolomic profile were found depending on the type or clinical course of the disease, neither in the whole MC group nor in the subgroup analysis of CC.

The Effects of Black Raspberry as a Whole Food-Based Approach on Biomarkers of Oxidative Stress in Buccal Cells and Urine of Smokers

Cigarette smoke is a rich source of free radicals that can promote oxidative stress and carcinogenesis, including head and neck squamous cell carcinoma (HNSCC) development; importantly, 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-iso-prostaglandin F2α (8-isoprostane) are biomarkers of oxidative stress. Several mechanisms, including the antioxidant properties of black raspberry (BRB), account for their chemopreventive effects. In the present clinical trial, we tested the hypothesis that BRB administration reduces biomarkers levels of oxidative stress in buccal cells and urine of smokers. One week after enrolling 21 smokers, baseline buccal cells and urine samples were collected before the administration of BRB lozenges for 8 weeks (5/day, 1 gm BRB/lozenge). Buccal cells and urine samples were collected at the middle and the end of BRB administration. The last samples were collected after the BRB cessation (washout period). We analyzed levels of 8-oxodG and 8-isoprostane (LC/MS-MS), urinary cotinine (ELISA), and creatinine (spectrophotometry). BRB significantly reduced the levels of 8-oxodG by 17.08% (P = 0.00079) in buccal cells and 12.44% (P = 0.034) in urine at the middle of BRB administration as compared with baseline; the corresponding values at the end of BRB administration were 16.46% (P = 0.026) in buccal cells and 25.72% (P = 0.202) in urine. BRB had no significant effect on the levels of urinary 8-isoprostane. BRB's capacity to inhibit 8-oxodG formation of smokers' buccal cells and urine is clearly evident and the reduction in 8-oxodG suggests that antioxidant abilities are central to BRB's HNSCC chemopreventive properties.

PREVENTION RELEVANCE

Cigarette smoke contains highly active components namely free radicals that can promote oxidative stress and oral cancer. We found that black raspberry (BRB) inhibited the formation of oxidative stress markers in the oral cavity and urine of smokers suggesting the antioxidant abilities of BRB in preventing oral cancer.

The Relationship of Preconception and Early Pregnancy Isoprostanes with Fecundability and Pregnancy Loss

BACKGROUND

Although redox stress likely plays an important role in reproductive health, the utility of peripheral biomarkers of oxidative stress, such as isoprostanes, during the periconception period remains underexplored. We evaluated the relationship between isoprostanes during preconception and gestational week 4 and women's reproductive health outcomes.

METHODS

The Effects of Aspirin in Gestation and Reproduction trial (2007-2011) enrolled 1228 women attempting pregnancy and followed them for up to 6 menstrual cycles and throughout pregnancy if they became pregnant. We measured creatinine-adjusted, log-transformed isoprostanes 8-iso-prostaglandin F 2α (8-iso-PGF2α), its metabolite 2,3-dinor-iPF2α-III, and stereoisomers 5-iso-PGF2α-VI and 8,12-iso-iPF2α-VI in urine during preconception and 4 weeks gestation. We evaluated pregnancy among participants in each menstrual cycle using human chorionic gonadotropin (hCG) and defined pregnancy loss as observed loss following positive hCG. We calculated fecundability odds ratios (FOR) and 95% confidence intervals (CI) using discrete-time Cox proportional hazards models and relative risk of pregnancy loss using adjusted log-binomial models.

RESULTS

Higher preconception isoprostane levels were associated with lower fecundability [e.g., FOR = 0.89; 95% CI = 0.81, 0.97 per interquartile range (IQR) increase in 8-iso-PGF2α]. Among 797 pregnancies, isoprostane levels increased from preconception to 4 weeks gestation (e.g., mean difference = 0.12; 95% CI = 0.10, 0.14 ng/mL for 8-iso-PGF2α) and higher isoprostanes at 4 weeks gestation were associated with lower risk of pregnancy loss (e.g., RR = 0.79; 95% CI = 0.62, 1.00 per IQR increase in 8-iso-PGF2α).

CONCLUSIONS

Preconception urinary isoprostanes may identify redox stress pathways associated with lower fecundability. However, the increase in isoprostanes into gestational week 4 and the associated lower risk of pregnancy loss may suggest confounding by latent factors in early pregnancy.

Association of Urinary Biomarkers of Smoking-Related Toxicants with Lung Cancer Incidence in Smokers: The Multiethnic Cohort Study

BACKGROUND

While cigarette smoking is the leading cause of lung cancer, the majority of smokers do not develop the disease over their lifetime. The inter-individual differences in risk among smokers may in part be due to variations in exposure to smoking-related toxicants.

METHODS

Using data from a subcohort of 2,309 current smokers at the time of urine collection from the Multiethnic Cohort Study, we prospectively evaluated the association of ten urinary biomarkers of smoking-related toxicants [total nicotine equivalents (TNE), a ratio of total trans-3'-hydroxycotinine (3-HCOT)/cotinine (a phenotypic measure of CYP2A6 enzymatic activity), 4-(methylnitrosamino)-1-3-(pyridyl)-1-butanol (NNAL), S-phenylmercapturic acid (SPMA), 3-hydroxypropyl mercapturic acid (3-HPMA), phenanthrene tetraol (PheT), 3-hydroxyphenanthrene (PheOH), the ratio of PheT/PheOH, cadmium (Cd), and (Z)-7-(1R,2R,3R,5S)-3,5-dihydroxy-2-[(E,3S)-3-hydroxyoct-1-enyl]cyclopenyl]hept-5-enoic acid (8-iso-PGF2α)] with lung cancer risk (n = 140 incident lung cancer cases over an average of 13.4 years of follow-up). Lung cancer risk was estimated using Cox proportional hazards models.

RESULTS

After adjusting for decade of birth, sex, race/ethnicity, body mass index, self-reported pack-years, creatinine, and urinary TNE (a biomarker of internal smoking dose), a one SD increase in log total 3-HCOT/cotinine (HR, 1.33; 95% CI, 1.06-1.66), 3-HPMA (HR, 1.41; 95% CI, 1.07-1.85), and Cd (HR, 1.45; 95% CI, 1.18-1.79) were each associated with increased lung cancer risk.

CONCLUSIONS

Our study demonstrates that urinary total 3-HCOT/cotinine, 3-HPMA, and Cd are positively associated with lung cancer risk. These findings warrant replication and consideration as potential biomarkers for smoking-related lung cancer risk.

IMPACT

These biomarkers may provide additional information on lung cancer risk that is not captured by self-reported smoking history or TNE. See related commentary by Etemadi et al., p. 289.

Urinary Leukotriene E4 and Prostaglandin D2 Metabolites Increase in Adult and Childhood Severe Asthma Characterized by Type 2 Inflammation. A Clinical Observational Study

Rationale: New approaches are needed to guide personalized treatment of asthma.Objectives: To test if urinary eicosanoid metabolites can direct asthma phenotyping.Methods: Urinary metabolites of prostaglandins (PGs), cysteinyl leukotrienes (CysLTs), and isoprostanes were quantified in the U-BIOPRED (Unbiased Biomarkers for the Prediction of Respiratory Diseases Outcomes) study including 86 adults with mild-to-moderate asthma (MMA), 411 with severe asthma (SA), and 100 healthy control participants. Validation was performed internally in 302 participants with SA followed up after 12-18 months and externally in 95 adolescents with asthma.Measurement and Main Results: Metabolite concentrations in healthy control participants were unrelated to age, body mass index, and sex, except for the PGE₂ pathway. Eicosanoid concentrations were generally greater in participants with MMA relative to healthy control participants, with further elevations in participants with SA. However, PGE₂ metabolite concentrations were either the same or lower in male nonsmokers with asthma than in healthy control participants. Metabolite concentrations were unchanged in those with asthma who adhered to oral corticosteroid treatment as documented by urinary prednisolone detection, whereas those with SA treated with omalizumab had lower concentrations of LTE₄ and the PGD₂ metabolite 2,3-dinor-11β-PGF_2α. High concentrations of LTE₄ and PGD₂ metabolites were associated with lower lung function and increased amounts of exhaled nitric oxide and eosinophil markers in blood, sputum, and urine in U-BIOPRED participants and in adolescents with asthma. These type 2 (T2) asthma associations were reproduced in the follow-up visit of the U-BIOPRED study and were found to be as sensitive to detect T2 inflammation as the established biomarkers.Conclusions: Monitoring of urinary eicosanoids can identify T2 asthma and introduces a new noninvasive approach for molecular phenotyping of adult and adolescent asthma.Clinical trial registered with www.clinicaltrials.gov (NCT01976767).

Recent progress in the LC-MS/MS analysis of oxidative stress biomarkers

The presence of a dynamic and balanced equilibrium between the production of reactive oxygen (ROS) and nitrogen (RNS) species and the in-house antioxidant defense mechanisms is characteristic for a healthy body. During oxidative stress (OS), this balance is switched to increased production of ROS and RNS, exceeding the capacity of physiological antioxidant systems. This can cause damage to biological molecules, leading to loss of function and even cell death. Nowadays, there is increasing scientific and clinical interest in OS and the associated parameters to measure the degree of OS in biofluids. An increasing number of reports using LC-MS/MS methods for the analysis of OS biomarkers can be found. Since bioanalysis is usually complicated by matrix effects, various types of cleanup procedures are used to effectively separate the biomarkers from the matrix. This is an essential part of the analysis to prepare a reproducible and homogenous solution suitable for injection onto the column. The present review gives a summary of the chromatographic methods used for the determination of OS biomarkers in both urine and plasma, serum, and whole blood samples. The first part mainly describes the biological background of the different OS biomarkers, while the second part reports examples of chromatographic methods for the analysis of different metabolites connected with OS in biofluids, covering a period from 2015 till early 2020. The selected examples mainly include LC-MS/MS methods for isoprostanes, oxidized proteins, oxidized lipoproteins, and DNA/RNA biomarkers. The last part explains the clinical relevance of this review.

Identification and quantification of phenanthrene ortho-quinones in human urine and their association with lipid peroxidation

Although human exposure to polycyclic aromatic hydrocarbons (PAH) has been associated with in vivo oxidative damage, and hydroxyPAH metabolites have been used as biomarkers to assess PAH-induced oxidative stress, few studies have looked at the likely causative compounds for oxidative stress in humans - PAH quinones. We developed a method using pre-column derivatization - liquid chromatography-heated electrospray ionization-tandem mass spectrometry (LC-HESI-MS/MS) to analyze ortho-phenanthrene quinones (PheQs) in human urine. 1,2-PheQ and 3,4-PheQ were identified and quantified in 3 mL of human urine; their total concentrations were higher in cigarette smokers (0.79 ± 0.98 nmol/6h urine) than in nonsmokers (0.20 ± 0.98 nmol/6h urine) (p < 0.01). The total of 1,2-PheQ and 3,4-PheQ were more strongly correlated with urinary (Z)-7-[1R,2R,3R,5S)-3,5-dihydroxy-2-[(E,3S)-3-hydroxyoct-1-enyl]cyclopentyl]hept-5-enoic acid (8-iso-PGF_2α), a biomarker of lipid peroxidation (R² = 0.53, p < 0.001), than the other phenanthrene metabolites including phenanthrene tetraol (PheT), phenanthrene-1,2-dihydrodiol (1,2-PheD), and total phenanthrene phenols (OHPhe), consistent with the concept that PheQs and likely other PAH quinones play a causal role in the generation of reactive oxygen species (ROS) in humans. Thus, PheQs may be suitable as biomarkers to assess human exposure to oxygenated PAH and the subsequent oxidative damage. This study provides unique support, by analysis of human urinary metabolites, for the PAH quinone mediated oxidative damage hypothesis of PAH carcinogenesis.

Kava as a Clinical Nutrient: Promises and Challenges

Kava beverages are typically prepared from the root of Piper methysticum. They have been consumed among Pacific Islanders for centuries. Kava extract preparations were once used as herbal drugs to treat anxiety in Europe. Kava is also marketed as a dietary supplement in the U.S. and is gaining popularity as a recreational drink in Western countries. Recent studies suggest that kava and its key phytochemicals have anti-inflammatory and anticancer effects, in addition to the well-documented neurological benefits. While its beneficial effects are widely recognized, rare hepatotoxicity had been associated with use of certain kava preparations, but there are no validations nor consistent mechanisms. Major challenges lie in the diversity of kava products and the lack of standardization, which has produced an unmet need for quality initiatives. This review aims to provide the scientific community and consumers, as well as regulatory agencies, with a broad overview on kava use and its related research. We first provide a historical background for its different uses and then discuss the current state of the research, including its chemical composition, possible mechanisms of action, and its therapeutic potential in treating inflammatory and neurological conditions, as well as cancer. We then discuss the challenges associated with kava use and research, focusing on the need for the detailed characterization of kava components and associated risks such as its reported hepatotoxicity. Lastly, given its growing popularity in clinical and recreational use, we emphasize the urgent need for quality control and quality assurance of kava products, pharmacokinetics, absorption, distribution, metabolism, excretion, and foundational pharmacology. These are essential in order to inform research into the molecular targets, cellular mechanisms, and creative use of early stage human clinical trials for designer kava modalities to inform and guide the design and execution of future randomized placebo controlled trials to maximize kava's clinical efficacy and to minimize its risks.

A Review of Efforts to Improve Lipid Stability during Sample Preparation and Standardization Efforts to Ensure Accuracy in the Reporting of Lipid Measurements

Lipidomics is a rapidly growing field, fueled by developments in analytical instrumentation and bioinformatics. To date, most researchers and industries have employed their own lipidomics workflows without a consensus on best practices. Without a community-wide consensus on best practices for the prevention of lipid degradation and transformations through sample collection and analysis, it is difficult to assess the quality of lipidomics data and hence trust results. Clinical studies often rely on samples being stored for weeks or months until they are analyzed, but inappropriate sampling techniques, storage temperatures, and analytical protocols can result in the degradation of complex lipids and the generation of oxidized or hydrolyzed metabolite artifacts. While best practices for lipid stability are sample dependent, it is generally recommended that strategies during sample preparation capable of quenching enzymatic activity and preventing oxidation should be considered. In addition, after sample preparation, lipid extracts should be stored in organic solvents with antioxidants at -20 °C or lower in an airtight container without exposure to light or oxygen. This will reduce or eliminate sublimation, and chemically and physically induced molecular transformations such as oxidation, enzymatic transformation, and photon/heat-induced degradation. This review explores the available literature on lipid stability, with a particular focus on human health and/or clinical lipidomic applications. Specifically, this includes a description of known mechanisms of lipid degradation, strategies, and considerations for lipid storage, as well as current efforts for standardization and quality insurance of protocols.

Relationships between the Nicotine Metabolite Ratio and a Panel of Exposure and Effect Biomarkers: Findings from Two Studies of U.S. Commercial Cigarette Smokers

BACKGROUND

We examined the nicotine metabolite ratio's (NMR) relationship with smoking intensity, nicotine dependence, and a broad array of biomarkers of exposure and biological effect in commercial cigarette smokers.

METHODS

Secondary analysis was conducted on two cross-sectional samples of adult, daily smokers from Wave 1 (2013-2014) of the Population Assessment of Tobacco Use and Health (PATH) Study and baseline data from a 2014-2017 randomized clinical trial. Data were restricted to participants of non-Hispanic, white race. The lowest quartile of NMR (<0.26) in the nationally representative PATH Study was used to distinguish slow from normal/fast nicotine metabolizers. NMR was modeled continuously in secondary analysis.

RESULTS

Compared with slow metabolizers, normal/fast metabolizers had greater cigarettes per day and higher levels of total nicotine equivalents, tobacco-specific nitrosamines, volatile organic componds, and polycyclic aromatic hydrocarbons. A novel finding was higher levels of inflammatory biomarkers among normal/fast metabolizers versus slow metabolizers. With NMR modeled as a continuous measure, the associations between NMR and biomarkers of inflammation were not significant.

CONCLUSIONS

The results are suggestive that normal/fast nicotine metabolizers may be at increased risk for tobacco-related disease due to being heavier smokers, having higher exposure to numerous toxicants and carcinogens, and having higher levels of inflammation when compared with slow metabolizers.

IMPACT

This is the first documentation that NMR is not only associated with smoking exposure but also biomarkers of biological effects that are integral in the development of tobacco-related disease. Results provide support for NMR as a biomarker for understanding a smoker's exposure and potential risk for tobacco-related disease.

Effects of immediate versus gradual nicotine reduction in cigarettes on biomarkers of biological effects

AIM

A previous study showed significantly greater reductions in number of cigarettes smoked and biomarkers of toxicant and carcinogen exposure in smokers assigned to immediate reduction of nicotine in cigarettes to very low levels versus gradually over time or continued smoking of normal nicotine content cigarettes. This study examines the effects of these approaches on selected biomarkers associated with harmful biological effects.

DESIGN

Three-arm, randomized controlled trial.

SETTING

Ten United States academic institutional sites.

PARTICIPANTS

Daily smokers uninterested in quitting smoking with a mean age of 45.1 [standard deviation (SD) = 13.4)] years and smoking 17.1 (SD = 8.5) cigarettes/day; 43.9% (549 of 1250) female; 60.6% (758 of 1250) white ethnicity.

INTERVENTIONS

(1) Smoking cigarettes where nicotine content was immediately reduced to very low levels (n = 503); (2) smoking cigarettes where nicotine content was gradually reduced, with dose changes occurring monthly (n = 498); and (3) continued smoking with normal nicotine content cigarettes (n = 249).

MEASUREMENTS

Smokers were assessed at baseline while smoking their usual brand cigarettes, and again at 4, 8, 12, 16 and 20 weeks. Outcomes were areas under the concentration time curve (AUC) for the period of study of biomarkers of inflammation, oxidative stress and hematological parameters.

FINDINGS

No consistent significant differences were observed across groups (Bayes factors showing data to be insensitive), with the only exception being red blood cell size variability, which was observed to be lower in the immediate versus gradual nicotine reduction [mean difference =  -0.11; 95% confidence interval (CI) = -0.18, -0.04, P = 0.004] and normal nicotine control groups (mean difference = - 0.15, 95% CI = -0.23, -0.06, P = 0.001).

CONCLUSION

It remains unclear whether switching to very low nicotine cigarettes leads to a short-term reduction in biomarkers of tobacco-related harm.