title: Chronic exposure to arsenic, LINE-1 hypomethylation, and blood pressure: a cross-sectional study in Bangladesh.
abstract: Chronic exposure to arsenic is associated with cancer and hypertension. Growing evidence suggests that altered methylation in long interspersed nuclear element-1 (LINE-1) is involved in many types of disorders, including cardiovascular disease. Here we evaluated the association between arsenic exposure and LINE-1 methylation levels, especially in relation to blood pressure (BP).
  
  
  
  A total of 236 subjects (175 from arsenic-endemic areas and 61 from a non-endemic area) in rural Bangladesh were recruited. The subjects' arsenic exposure levels (i.e., drinking water, hair and nail arsenic concentrations) were measured by inductively coupled plasma mass spectroscopy. The subjects' LINE-1 methylation levels were determined by pyrosequencing.
  
  
  
  The average LINE-1 methylation levels of the subjects living in the arsenic-endemic areas were significantly (p < 0.01) lower than those of the subjects living in the non-endemic area. In a sex-stratified analysis, the arsenic exposure levels in female but not male subjects showed a significant inverse association with LINE-1 methylation levels before (water arsenic: p < 0.01, hair arsenic: p < 0.05, nail arsenic: p < 0.001) and after (water arsenic: p < 0.01, hair arsenic: p < 0.05, nail arsenic: p < 0.001) adjustment for age, body mass index and smoking. Analyses examining interactions among arsenic levels, BP and LINE-1 methylation showed that arsenic-related elevated levels of BP were associated with LINE-1 hypomethylation.
  
  
  
  Our findings demonstrated that chronic exposure to arsenic was inversely associated with LINE-1 methylation levels in blood leukocyte DNA and this was more pronounced in females than males; in addition, the decreased levels of LINE-1 methylation might be involved in the arsenic-induced elevation of BP.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Rajshahi, Rajshahi-6205, Bangladesh. khossainbio@gmail.com.
authors.forename: Khaled
authors.initials: K
authors.lastname: Hossain
authors.affiliation: Center for Health and Environmental Risk Research, National Institute for Environmental Studies, Tsukuba 305-8506, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Rajshahi, Rajshahi-6205, Bangladesh.
authors.forename: M M
authors.initials: MM
authors.lastname: Hasibuzzaman
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Rajshahi, Rajshahi-6205, Bangladesh.|Department of Applied Nutrition and Food Technology, Islamic University, Kushtia-7003, Bangladesh.
authors.forename: Md Shofikul
authors.initials: MS
authors.lastname: Islam
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Rajshahi, Rajshahi-6205, Bangladesh.
authors.forename: Atiqur
authors.initials: A
authors.lastname: Rahman
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Rajshahi, Rajshahi-6205, Bangladesh.|Department of Applied Nutrition and Food Technology, Islamic University, Kushtia-7003, Bangladesh.
authors.forename: Sudip Kumar
authors.initials: SK
authors.lastname: Paul
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Rajshahi, Rajshahi-6205, Bangladesh.
authors.forename: Tanzina
authors.initials: T
authors.lastname: Tanu
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Rajshahi, Rajshahi-6205, Bangladesh.
authors.forename: Shakhawoat
authors.initials: S
authors.lastname: Hossain
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Rajshahi, Rajshahi-6205, Bangladesh.
authors.forename: Zahangir Alam
authors.initials: ZA
authors.lastname: Saud
authors.affiliation: Exim Bank Agricultural University, Chapainawabganj, Bangladesh.
authors.forename: Mashiur
authors.initials: M
authors.lastname: Rahman
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Rajshahi, Rajshahi-6205, Bangladesh.
authors.forename: Farjana
authors.initials: F
authors.lastname: Nikkon
authors.affiliation: Laboratory of Molecular Nutrition and Toxicology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima 770-8514, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Miyataka
authors.affiliation: Laboratory of Molecular Nutrition and Toxicology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima 770-8514, Japan.
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Himeno
authors.affiliation: Center for Health and Environmental Risk Research, National Institute for Environmental Studies, Tsukuba 305-8506, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Nohara
mesh_terms: D000328:Adult; D001151:Arsenic / Q000009:adverse effects* / Q000032:analysis; D001459:Bangladesh; D001794:Blood Pressure / Q000187:drug effects*; D003430:Cross-Sectional Studies; D019175:DNA Methylation / Q000187:drug effects*; D060766:Drinking Water / Q000032:analysis; D004781:Environmental Exposure / Q000009:adverse effects* / Q000032:analysis; D005260:Female; D006197:Hair / Q000737:chemistry; D006801:Humans; D020084:Long Interspersed Nucleotide Elements / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009262:Nails / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000009:adverse effects* / Q000032:analysis
chemical_list: D060766:Drinking Water; D014874:Water Pollutants, Chemical; D001151:Arsenic
keywords: Arsenic; Bangladesh; Blood pressure; Hypertension; Hypomethylation; LINE-1