Patient and Health Care Professional Perceptions of the Experience and Impact of Symptoms of Moderate-to-Severe Crohn's Disease in US and Europe: Results from the Cross-Sectional CONFIDE Study.

BACKGROUND: Crohn's disease (CD) significantly affects patients' health-related quality of life and well-being. AIMS: Communicating Needs and Features of IBD Experiences (CONFIDE) survey explores the experience and impact of moderate-to-severe CD symptoms on patients' lives and identifies communication gaps between patients and health care professionals (HCPs). METHODS: Online, quantitative, cross-sectional surveys of patients, and HCPs were conducted in the United States (US), Europe (France, Germany, Italy, Spain, United Kingdom), and Japan. Criteria based on previous treatment, steroid use, and/or hospitalization defined moderate-to-severe CD. US and Europe data are presented as descriptive statistics. RESULTS: Surveys were completed by 215 US and 547 European patients and 200 US and 503 European HCPs. In both patient groups, top three symptoms currently (past month) experienced were diarrhea, bowel urgency, and increased stool frequency, with more than one-third patients wearing diaper/pad/protection at least once a week in past 3 months due to fear of bowel urgency-related accidents. HCPs ranked diarrhea, blood in stool, and increased stool frequency as the most common symptoms. Although 34.0% US and 27.2% European HCPs ranked bowel urgency among the top five symptoms affecting patient lives, only 12.0% US and 10.9% European HCPs ranked it among top three most impactful symptoms on treatment decisions. CONCLUSION: Bowel urgency is common and impactful among patients with CD in the US and Europe. Differences in patient and HCP perceptions of experiences and impacts of bowel urgency exist, with HCPs underestimating its burden. Proactive communication between HCPs and patients in clinical settings is crucial for improving health outcomes in patients with CD.

Acute Treatment Patterns, Migraine Burden, and Healthcare Resource Use in People With Migraine: Results From the OVERCOME (EU) Observational Study.

INTRODUCTION: The ObserVational survey of the Epidemiology, tReatment and Care Of MigrainE (OVERCOME) European Union (EU) is part of an overarching population-based study program that also includes the United States and Japan. Here, we report data on the migraine/severe headache burden and the use of acute medication and healthcare resources in Spain and Germany. METHODS: OVERCOME (EU) was an online, non-interventional, cross-sectional survey conducted in adults in Spain and Germany between October 2020 and February 2021. A total migraine cohort was established based on health survey participants who reported headache/migraine in the last 12 months AND identified as having migraine based on modified International Classification of Headache Disorders, third edition criteria OR self-reported physician diagnosis. Data were analyzed for the total migraine cohort and the subcohort with moderate to severe headache attacks, with average pain severity ≥ 5 points, pain duration ≥ 4 h, and at least moderate disability due to migraine [Migraine Disability Assessment (MIDAS) score ≥ 11] over the past 3 months. RESULTS: Pain of moderate or severe intensity was the most frequent symptom in the total migraine cohort (n = 19,103/20,756; 92.0%). Proportions of participants reporting severe disability (MIDAS Grade IV), poorer quality of life (QoL; Migraine-Specific QoL Questionnaire), and higher interictal burden (Migraine Interictal Burden Scale-4), generally increased with number of headache days (HDs)/month. Most participants (92.5%) reported current acute migraine/severe headache medication use, although only 39.0% were using triptans. In the moderate to severe attacks subcohort (n = 5547), 48.4% were using triptans, with nonsteroidal anti-inflammatory drugs the most common acute medication. The moderate to severe attacks subcohort also reported poorer QoL and greater pain and disability with increasing HDs/month, although severe interictal burden was reported for ~ 60% of participants regardless of HDs/month. Treatment satisfaction (six-item migraine Treatment Optimization Questionnaire) in those using triptans was generally poor in both total and subcohorts. CONCLUSION: High migraine-related burden levels were reported, despite use of acute medication. Although triptans are recommended for moderate to severe migraine attacks in Spanish and German guidelines, less than half of participants were using triptans; treatment satisfaction in those using triptans was generally poor. New tailored treatment options may help address unmet needs in current acute treatment.

Treatment pattern and health care resource utilization for Taiwanese patients with migraine: a population-based study.

Objectives: Given the substantial disease burden, appropriate and effective management of migraine is a public health priority. To gain insights into real-world migraine management practices in Taiwan, current treatment patterns, costs, and health care resource use were assessed. Methods: This was a retrospective, longitudinal study using the Taiwan National Health Insurance Research Database. Included patients had an initial diagnosis of migraine (defined using International Classification of Diseases codes) between 1 January 2013 and 31 December 2017. Data analyzed included demographics; the use, number, and type of acute and preventive medications; and drug and medical services costs. Data were stratified according to migraine type (chronic [CM] or episodic [EM] migraine). Results: A total of 312,718 patients were included in the analyses: 53,992 (17.3%) had CM and 258,726 (82.7%) had EM. Most patients (81.7%) had used acute and/or preventive medications; acute medications used more frequently than preventive medications (78.0% vs. 20.2%). Acute medications were used by 81.6 and 77.3% of patients with CM and EM, respectively. Commonly used acute medications were acetaminophen (68.8%), ergots (49.4%), and non-steroidal anti-inflammatory drugs (38.4%); the use of triptans (6.0%), tramadol (3.1%), and other opioids (0.2%) was less common. A total of 28.6 and 18.5% of patients with CM and EM, respectively, used preventive medications. Flunarizine (68.9%), propranolol (40.7%), and topiramate (16.0%) were the most commonly used preventive medications. Most patients had used 1-2 acute or preventive medications, with the use of ≥3 acute or preventive medications more common in patients with CM than EM. Average total medical cost per annum was 4,169 New Taiwan Dollars (NTDs) per CM patient and 2,928 NTDs per EM patient, with CM patients having higher costs associated with medical service utilization and acute medication use. Conclusion: These real-world data suggest unmet needs for Taiwanese patients with migraine, including under-utilization of preventive medications and greater costs and health care resource use for patients with CM versus EM. These findings provide important information on treatment patterns, cost, and health care resource use for patients with migraine in Taiwan.

Burden and Unmet Needs in Migraine Patients: Results from the OVERCOME (Spain) Study.

INTRODUCTION: This analysis aimed to evaluate demographics, migraine-related disability, symptoms, diagnosis and healthcare consultation, work productivity, and treatment patterns according to headache frequency in adults with migraine in the OVERCOME (ObserVational survey of the Epidemiology, tReatment and Care Of MigrainE) (Spain) study. METHODS: Data were obtained from an observational, cross-sectional, web-based survey conducted between October 2020-February 2021 in Spain. Eligible participants were adult members of online survey panels living in Spain who were able to read and write Spanish and fulfilled the International Classification of Headache Disorders, third edition (ICHD-3) criteria for migraine or had a self-reported physician diagnosis. RESULTS: In total, 10,229 patients comprised the Spanish sample. Only 56.2% of respondents had a confirmed healthcare professional (HCP) diagnosis of migraine, despite almost all meeting modified ICHD-3 criteria. Pain severity, migraine-related disability, and interictal burden increased with increasing number of headache days per month. Migraine impacted on respondents' work productivity, with increases in presenteeism, work productivity loss, and daily activity impairment at higher headache frequencies. Over the past year, 66.2% of all HCP visits were specifically due to migraine, most commonly with a general practitioner or pharmacist. A subgroup of 1277 patients (12.5% of the total survey population) met eligibility criteria for migraine preventive medications, of whom only 36.6% were currently taking a preventive. CONCLUSIONS: Results of the OVERCOME (Spain) survey reveal the substantial burden of migraine, which is directly linked to headache frequency. However, most patients experiencing frequent headaches and eligible for migraine preventives are currently not taking them. Findings highlight the importance of addressing unmet needs for people with migraine in Spain.

Preventive treatment patterns and treatment satisfaction in migraine: results of the OVERCOME (EU) study.

BACKGROUND: Insights into the burden, needs and treatment of migraine from internet-based surveys in diverse real-world migraine populations are needed, especially at a time when novel preventive migraine medications are becoming part of the therapeutic armamentarium. The objectives of this analysis are to describe traditional preventive (orals and onabotulinum toxin A) treatment patterns in the OVERCOME (EU) study migraine cohort, as well as treatment patterns and patient satisfaction with current treatment in a subgroup of respondents eligible for migraine preventive medication. METHODS: The cross-sectional non-interventional OVERCOME (EU) study was conducted (October 2020-February 2021) via an online survey among adults (aged ≥ 18 years) resident in Germany or Spain. Participants, registered in existing online panels, who were willing to provide consent were considered. The migraine cohort included participants reporting headache/migraine in the past year, identified based on a validated migraine diagnostic questionnaire and/or self-reported physician diagnosis. A subgroup of survey respondents defined as eligible for migraine preventive medication at the point in time the cross-sectional survey was taken was also analysed. Variables assessed included sociodemographic and migraine-related clinical characteristics, preventive (traditional and calcitonin gene-related peptide monoclonal antibodies) treatment patterns and patient satisfaction with current treatment. Results are descriptive only. RESULTS: Of the 20,756 participants in the migraine cohort, 78.5% sought professional medical care, 50.8% received a migraine diagnosis and only 17.7% had ever used preventive medication. Half (53.3%) of participants currently using preventives took their most recent medication for six months or less. Most patients (73.9%) classified as eligible for preventive medication (based on headache frequency and/or at least moderate disability due to migraine) reported not using traditional preventives and many of those who did (66.8%) were not satisfied with their current standard of care. CONCLUSIONS: Our findings highlight the low proportion of people diagnosed with migraine despite a higher rate of consultation and suggest the need for better access to treatment for people with migraine and new preventive therapies with improved efficacy and safety profiles to improve adherence and patient satisfaction.

Efficacy and Safety of Galcanezumab as a Preventive Treatment for Episodic Migraine in South Korean Patients: A Post-Hoc Analysis of a Phase 3 Clinical Trial.

BACKGROUND AND PURPOSE: The estimated prevalence of migraines in South Korea is 6.0%, with affected patients having unmet needs. The efficacy, safety, and tolerability of galcanezumab, a humanized monoclonal antibody, for episodic migraine (EM) prevention was evaluated in South Korean patients. METHODS: During the double-blind period of the EVOLVE-2 phase 3 trial, patients with EM were randomized into placebo, 120 mg-galcanezumab, and 240-mg galcanezumab treatment groups. The primary endpoint was the overall mean change from baseline in the number of monthly migraine headache days during the 6-month double-blind period. We conducted a post-hoc analysis of the South Korean cohort in EVOLVE-2. RESULTS: Among 98 South Korean patients in the intent-to-treat population, significant changes from baseline were observed in the number of monthly migraine headache days in the 240-mg galcanezumab group compared with the placebo group (-2.64, p=0.013), in the percentage of patients with ≥50% reduction in the number of monthly migraine headache days (120 mg: odds ratio=2.43, p=0.030; 240 mg: odds ratio=2.60, p=0.019), in the number of monthly migraine headache days with acute medication use (120 mg: -2.22, p=0.006; 240 mg: -2.23, p=0.005), and in the Migraine-Specific Quality-of-Life Role Function-Restrictive (120 mg: 8.34, p=0.040). Numerical improvements from baseline were observed relative to the placebo group in at least one galcanezumab group for: the percentage of patients with ≥75% reduction in the number of monthly migraine headache days functional impairment, and disease severity. The most common treatment-emergent adverse event in the combined galcanezumab group was injection site reaction, which led to treatment discontinuation for one patient. CONCLUSIONS: Galcanezumab treatment demonstrated efficacy and a favorable safety and tolerability profile in South Korean patients with EM.

Prevalence Rates of Primary Headache Disorders and Evaluation and Treatment Patterns Among Korean Neurologists.

BACKGROUND AND PURPOSE: Several studies have found that the prevalence of migraine is higher among healthcare professionals than in the general population. Furthermore, several investigations have suggested that the personal experiences of neurologists with migraine can influence their perception and treatment of the disease. This study assessed these relationships in Korea. METHODS: A survey was used to investigate the following characteristics among neurologists: 1) the prevalence rates of migraine, primary stabbing headache, and cluster headache, and 2) their perceptions of migraine and the pain severity experienced by patients, diagnosing migraine, evaluation and treatment patterns, and satisfaction and difficulties with treatment. RESULTS: The survey was completed by 442 actively practicing board-certified Korean neurologists. The self-reported lifetime prevalence rates of migraine, migraine with aura, primary stabbing headache, and cluster headache were 49.8%, 12.7%, 26.7%, and 1.4%, respectively. Few of the neurologists used a headache diary or validated scales with their patients, and approximately half were satisfied with the effectiveness of preventive medications. Significant differences were observed between neurologists who had and had not experienced migraine, regarding certain perceptions of migraine, but no differences were found between these groups in the evaluation and preventive treatment of migraine. CONCLUSIONS: The high self-reported lifetime prevalence rates of migraine and other primary headache disorders among Korean neurologists may indicate that these rates are underreported in the general population, although potential population biases must be considered. From the perspective of neurologists, there is an unmet need for the proper application of headache diaries, validated scales, and effective preventive treatments for patients. While the past experiences of neurologists with migraine might not influence how they evaluate or apply preventive treatments to migraine, they may influence certain perceptions of the disease.

Persistence, use of resources and costs in patients under migraine preventive treatment: the PERSEC study.

BACKGROUND: Migraine represents a serious burden for national health systems. However, preventive treatment is not optimally applied to reduce the severity and frequency of headache attacks and the related expenses. Our aim was to assess the persistence to traditional migraine prophylaxis available in Spain and its relationship with the healthcare resource use (HRU) and costs. METHODS: Retrospective observational study with retrospective cohort design of individuals with migraine treated with oral preventive medication for the first time from 01/01/2016 to 30/06/2018. One-year follow-up information was retrieved from the Big-Pac™ database. According to their one-year persistence to oral prophylaxis, two study groups were created and describe regarding HRU and healthcare direct and indirect costs using 95% confidence intervals (CI). The analysis of covariance (ANCOVA) was performed as a sensitivity analysis. Patients were considered persistent if they continued on preventive treatment until the end of the study or switched medications within 60 days or less since the last prescription. Non-persistent were those who permanently discontinued or re-initiated a treatment after 60 days. RESULTS: Seven thousand eight hundred sixty-six patients started preventive treatment (mean age (SD) 48.2 (14.8) and 80.4% women), of whom 2,545 (32.4%) were persistent for 6 months and 2,390 (30.4%) for 12 months. Most used first-line preventive treatments were antidepressants (3,642; 46.3%) followed by antiepileptics (1,738; 22.1%) and beta-blockers (1,399; 17.8%). The acute treatments prescribed concomitantly with preventives were NSAIDs (4,530; 57.6%), followed by triptans (2,217; 28.2%). First-time preventive treatment prescribers were mostly primary care physicians (6,044; 76.8%) followed by neurologists (1,221; 15.5%). Non-persistent patients required a higher number of primary care visits (mean difference (95%CI): 3.0 (2.6;3.4)) and days of sick leave (2.7 (0.8;4.5)) than the persistent ones. The mean annual expenditure was €622 (415; 829) higher in patients who not persisted on migraine prophylactic treatment. CONCLUSIONS: In this study, we observed a high discontinuation rate for migraine prophylaxis which is related to an increase in HRU and costs for non-persistent patients. These results suggest that the treatment adherence implies not only a clinical benefit but also a reduction in HRU and costs.

Metastable DNA methylation sites associated with longitudinal lung function decline and aging in humans: an epigenome-wide study in the NAS and KORA cohorts.

DNA methylation is an epigenetic regulator of gene transcription, which has been found to be both metastable and variable within human cohort studies. Currently, few studies have been done to identify metastable DNA methylation biomarkers associated with longitudinal lung function decline in humans. The identification of such biomarkers is important for screening vulnerable populations. We hypothesized that quantifiable blood-based DNA methylation alterations would serve as metastable biomarkers of lung function decline and aging, which may help to discover new pathways and/or mechanisms related to pulmonary pathogenesis. Using linear mixed models, we performed an Epigenome Wide Association Study (EWAS) between DNA methylation at CpG dinucleotides and longitudinal lung function (FVC, FEV1, FEF25-75%) decline and aging with initial discovery in the Normative Aging Study, and replication in the Cooperative Health Research in the Region of Augsburg cohort. We identified two metastable epigenetic loci associated with either poor lung function and aging, cg05575921 (AHRR gene), or lung function independently of aging, cg06126421 (IER3 gene). These loci may inform basic mechanisms associated with pulmonary function, pathogenesis, and aging. Human epigenomic variation, may help explain features of lung function decline and related pathophysiology not attributable to DNA sequence alone, such as accelerated pulmonary decline in smokers, former smokers, and perhaps non-smokers. Our EWAS across two cohorts, therefore, will likely have implications for the human population, not just the elderly.

DNA methylation and exposure to ambient air pollution in two prospective cohorts.

Long-term exposure to air pollution has been associated with several adverse health effects including cardiovascular, respiratory diseases and cancers. However, underlying molecular alterations remain to be further investigated. The aim of this study is to investigate the effects of long-term exposure to air pollutants on (a) average DNA methylation at functional regions and, (b) individual differentially methylated CpG sites. An assumption is that omic measurements, including the methylome, are more sensitive to low doses than hard health outcomes. This study included blood-derived DNA methylation (Illumina-HM450 methylation) for 454 Italian and 159 Dutch participants from the European Prospective Investigation into Cancer and Nutrition (EPIC). Long-term air pollution exposure levels, including NO2, NOx, PM2.5, PMcoarse, PM10, PM2.5 absorbance (soot) were estimated using models developed within the ESCAPE project, and back-extrapolated to the time of sampling when possible. We meta-analysed the associations between the air pollutants and global DNA methylation, methylation in functional regions and epigenome-wide methylation. CpG sites found differentially methylated with air pollution were further investigated for functional interpretation in an independent population (EnviroGenoMarkers project), where (N=613) participants had both methylation and gene expression data available. Exposure to NO2 was associated with a significant global somatic hypomethylation (p-value=0.014). Hypomethylation of CpG island's shores and shelves and gene bodies was significantly associated with higher exposures to NO2 and NOx. Meta-analysing the epigenome-wide findings of the 2 cohorts did not show genome-wide significant associations at single CpG site level. However, several significant CpG were found if the analyses were separated by countries. By regressing gene expression levels against methylation levels of the exposure-related CpG sites, we identified several significant CpG-transcript pairs and highlighted 5 enriched pathways for NO2 and 9 for NOx mainly related to the immune system and its regulation. Our findings support results on global hypomethylation associated with air pollution, and suggest that the shores and shelves of CpG islands and gene bodies are mostly affected by higher exposure to NO2 and NOx. Functional differences in the immune system were suggested by transcriptome analyses.

Genome-Wide Analysis of DNA Methylation and Fine Particulate Matter Air Pollution in Three Study Populations: KORA F3, KORA F4, and the Normative Aging Study.

BACKGROUND: Epidemiological studies have reported associations between particulate matter (PM) concentrations and cancer and respiratory and cardiovascular diseases. DNA methylation has been identified as a possible link but so far it has only been analyzed in candidate sites. OBJECTIVES: We studied the association between DNA methylation and short- and mid-term air pollution exposure using genome-wide data and identified potential biological pathways for additional investigation. METHODS: We collected whole blood samples from three independent studies-KORA F3 (2004-2005) and F4 (2006-2008) in Germany, and the Normative Aging Study (1999-2007) in the United States-and measured genome-wide DNA methylation proportions with the Illumina 450k BeadChip. PM concentration was measured daily at fixed monitoring stations and three different trailing averages were considered and regressed against DNA methylation: 2-day, 7-day and 28-day. Meta-analysis was performed to pool the study-specific results. RESULTS: Random-effect meta-analysis revealed 12 CpG (cytosine-guanine dinucleotide) sites as associated with PM concentration (1 for 2-day average, 1 for 7-day, and 10 for 28-day) at a genome-wide Bonferroni significance level (p ≤ 7.5E-8); 9 out of these 12 sites expressed increased methylation. Through estimation of I2 for homogeneity assessment across the studies, 4 of these sites (annotated in NSMAF, C1orf212, MSGN1, NXN) showed p > 0.05 and I2 < 0.5: the site from the 7-day average results and 3 for the 28-day average. Applying false discovery rate, p-value < 0.05 was observed in 8 and 1,819 additional CpGs at 7- and 28-day average PM2.5 exposure respectively. CONCLUSION: The PM-related CpG sites found in our study suggest novel plausible systemic pathways linking ambient PM exposure to adverse health effect through variations in DNA methylation. CITATION: Panni T, Mehta AJ, Schwartz JD, Baccarelli AA, Just AC, Wolf K, Wahl S, Cyrys J, Kunze S, Strauch K, Waldenberger M, Peters A. 2016. A genome-wide analysis of DNA methylation and fine particulate matter air pollution in three study populations: KORA F3, KORA F4, and the Normative Aging Study. Environ Health Perspect 124:983-990; http://dx.doi.org/10.1289/ehp.1509966.

Effects of metformin on metabolite profiles and LDL cholesterol in patients with type 2 diabetes.

OBJECTIVE: Metformin is used as a first-line oral treatment for type 2 diabetes (T2D). However, the underlying mechanism is not fully understood. Here, we aimed to comprehensively investigate the pleiotropic effects of metformin. RESEARCH DESIGN AND METHODS: We analyzed both metabolomic and genomic data of the population-based KORA cohort. To evaluate the effect of metformin treatment on metabolite concentrations, we quantified 131 metabolites in fasting serum samples and used multivariable linear regression models in three independent cross-sectional studies (n = 151 patients with T2D treated with metformin [mt-T2D]). Additionally, we used linear mixed-effect models to study the longitudinal KORA samples (n = 912) and performed mediation analyses to investigate the effects of metformin intake on blood lipid profiles. We combined genotyping data with the identified metformin-associated metabolites in KORA individuals (n = 1,809) and explored the underlying pathways. RESULTS: We found significantly lower (P < 5.0E-06) concentrations of three metabolites (acyl-alkyl phosphatidylcholines [PCs]) when comparing mt-T2D with four control groups who were not using glucose-lowering oral medication. These findings were controlled for conventional risk factors of T2D and replicated in two independent studies. Furthermore, we observed that the levels of these metabolites decreased significantly in patients after they started metformin treatment during 7 years' follow-up. The reduction of these metabolites was also associated with a lowered blood level of LDL cholesterol (LDL-C). Variations of these three metabolites were significantly associated with 17 genes (including FADS1 and FADS2) and controlled by AMPK, a metformin target. CONCLUSIONS: Our results indicate that metformin intake activates AMPK and consequently suppresses FADS, which leads to reduced levels of the three acyl-alkyl PCs and LDL-C. Our findings suggest potential beneficial effects of metformin in the prevention of cardiovascular disease.

Evolutionary age of repetitive element subfamilies and sensitivity of DNA methylation to airborne pollutants.

BACKGROUND: Repetitive elements take up >40% of the human genome and can change distribution through transposition, thus generating subfamilies. Repetitive element DNA methylation has associated with several diseases and environmental exposures, including exposure to airborne pollutants. No systematic analysis has yet been conducted to examine the effects of exposures across different repetitive element subfamilies. The purpose of the study is to evaluate sensitivity of DNA methylation in differentially‒evolved LINE, Alu, and HERV subfamilies to different types of airborne pollutants. METHODS: We sampled a total of 120 male participants from three studies (20 high-, 20 low-exposure in each study) of steel workers exposed to metal-rich particulate matter (measured as PM10) (Study 1); gas-station attendants exposed to air benzene (Study 2); and truck drivers exposed to traffic-derived elemental carbon (Study 3). We measured methylation by bisulfite-PCR-pyrosequencing in 10 differentially‒evolved repetitive element subfamilies. RESULTS: High-exposure groups exhibited subfamily-specific methylation differences compared to low-exposure groups: L1PA2 showed lower DNA methylation in steel workers (P=0.04) and gas station attendants (P=0.03); L1Ta showed lower DNA methylation in steel workers (P=0.02); AluYb8 showed higher DNA methylation in truck drivers (P=0.05). Within each study, dose-response analyses showed subfamily-specific correlations of methylation with exposure levels. Interaction models showed that the effects of the exposures on DNA methylation were dependent on the subfamily evolutionary age, with stronger effects on older LINEs from PM10 (p‒interaction=0.003) and benzene (p‒interaction=0.04), and on younger Alus from PM10 (p-interaction=0.02). CONCLUSIONS: The evolutionary age of repetitive element subfamilies determines differential susceptibility of DNA methylation to airborne pollutants.

Effects of airborne pollutants on mitochondrial DNA methylation.

BACKGROUND: Mitochondria have small mitochondrial DNA (mtDNA) molecules independent from the nuclear DNA, a separate epigenetic machinery that generates mtDNA methylation, and are primary sources of oxidative-stress generation in response to exogenous environments. However, no study has yet investigated whether mitochondrial DNA methylation is sensitive to pro-oxidant environmental exposures. METHODS: We sampled 40 male participants (20 high-, 20 low-exposure) from each of three studies on airborne pollutants, including investigations of steel workers exposed to metal-rich particulate matter (measured as PM1) in Brescia, Italy (Study 1); gas-station attendants exposed to air benzene in Milan, Italy (Study 2); and truck drivers exposed to traffic-derived Elemental Carbon (EC) in Beijing, China (Study 3). We have measured DNA methylation from buffy coats of the participants. We measured methylation by bisulfite-Pyrosequencing in three mtDNA regions, i.e., the transfer RNA phenylalanine (MT-TF), 12S ribosomal RNA (MT-RNR1) gene and "D-loop" control region. All analyses were adjusted for age and smoking. RESULTS: In Study 1, participants with high metal-rich PM1 exposure showed higher MT-TF and MT-RNR1 methylation than low-exposed controls (difference = 1.41, P = 0.002); MT-TF and MT-RNR1 methylation was significantly associated with PM1 exposure (beta = 1.35, P = 0.025); and MT-RNR1 methylation was positively correlated with mtDNA copy number (r = 0.36; P = 0.02). D-loop methylation was not associated with PM1 exposure. We found no effects on mtDNA methylation from air benzene (Study 2) and traffic-derived EC exposure (Study 3). CONCLUSIONS: Mitochondrial MT-TF and MT-RNR1 DNA methylation was associated with metal-rich PM1 exposure and mtDNA copy number. Our results suggest that locus-specific mtDNA methylation is correlated to selected exposures and mtDNA damage. Larger studies are needed to validate our observations.