Indoor Air Pollution from Biomass Burning Activates Akt in Airway Cells and Peripheral Blood Lymphocytes

Abstract

Biomass burning is a major source of indoor air pollution in rural India. The authors investigated in this study whether cumulative exposures to biomass smoke cause activation of the serine/threonine kinase Akt in airway cells and peripheral blood lymphocytes (PBL). For this, the authors enrolled 87 premenopausal (median age 34 years), nonsmoking women who used to cook with biomass (wood, dung, crop wastes) and 85 agematched control women who cooked with cleaner fuel liquefied petroleum gas. Immunocytochemical and immunoblotting assays revealed significantly higher levels of phosphorylated forms of Akt protein (p-Akt ser473 and p-Akt thr308 ) in PBL, airway epithelial cells, alveolar macrophages, and neutrophils in sputum of biomass-using women than control. Akt activation in biomass users was associated with marked rise in generation of reactive oxygen species and concomitant depletion of superoxide dismutase. Measurement of particulate matter having a diameter of less than 10 and 2.5 mm in indoor air by real-time aerosol monitor showed 2 to 4 times more particulate pollution in biomass-using households, and Akt activation was positively associated with particulate pollution after controlling potential confounders. The findings suggest that chronic exposure to biomass smoke activates Akt, possibly via generation of oxidative stress.

Chronic exposure to biomass fuel is associated with increased carotid artery intima-media thickness and a higher prevalence of atherosclerotic plaque

“…Principally, the mechanisms involve increases in oxidative stress, lung-mediated inflammation and stimulation of the autonomic nervous system 40. Despite a paucity of controlled studies in the field of biomass fuel smoke exposure in humans, recent studies have demonstrated that exposure is associated with increased airway inflammation,16 serum amyloid A,15 inflammatory cytokines, circulating neutrophils,17 oxidised LDL particles and reactive oxygen species,11 all of which are associated with the development of atherosclerosis. Intriguingly, however, the biomass fuel group in our study actually demonstrated less inflammation (lower hsCRP) than those in the clean fuel group.…”

Neutrophilic Inflammatory Response and Oxidative Stress in Premenopausal Women Chronically Exposed to Indoor Air Pollution from Biomass Burning

“…Immunocytochemical Localization of iNOS ICC of iNOS in isolated blood neutrophils and sputum cells were done following a standard procedure [38,40]. In brief, slides were air dried and fixed in icecold methanol for 30 min, air dried, washed in PBS thrice, and blocked in 3% BSA (Sigma-Aldrich Chemicals, Saint Louis, MO, USA) for 1 h at room temperature.…”

“…Generation of ROS was measured in leukocytes present in anticoagulated venous blood and sputum cells by flow cytometry using DCF-DA (Sigma Chem, USA) following the procedure of Rothe and Valet [47] with slight modifications [40]. For this, 10,000 events were acquired in a flow cytometer (FACSCalibur with sorter, Becton Dickinson [BD], San Jose, CA, USA) using Cell Quest software (BD).…”

“…Whole sputum collected in PBS with 0.1% dithiotheritol were used for cell lysate preparation for SOD assay followed by our previously published procedure [40]. Lysates were centrifuged at 15,000×g for 10 min at 4°C in an Eppendorf microcentrifuge.…”

“…Our earlier studies have linked IAP from BMF with upregulation of ribosome biogenesis [36,37], inappropriate response of DNA damage repair proteins in the face of increased DNA damage [38,39], overactivation of signal transduction pathway involving Akt, i.e., protein kinase B [40], and hypertension with elevated levels of oxidized low-density lipoprotein indicating cardiovascular disease [41]. These findings along with observations from other studies led us to hypothesize that chronic exposure to IAP from biomass burning could be associated with neutrophilic inflammatory responses and oxidative stress in premenopausal women of rural India who cook regularly with BMF.…”