Figure 1. Metformin prevents the release of IL-6 and enhanced tendency to thrombosis induced by exposure to particulate matter air pollution.

(A,B) Mice were administered metformin in the drinking water (150 mg/kg/day) then exposed to concentrated ambient particulate matter air pollution < 2.5 μm in diameter (CAPS) via inhalation in a versatile aerosol concentrator for eight hours daily on three consecutive weekdays. At the end of the third day, a standardized ferric chloride injury was induced in the carotid artery and the time to thrombosis was assessed using an ultrasonic probe placed on the artery distal to the injury (n=6, 5, 10 and 5 mice per condition, correspondingly, p<0.05 for comparison with filtered air controls). (C) Mice treated as in (A) were harvested for measurement of IL6 mRNA in alveolar macrophages (n=4 animals per condition, * p <0.05). (D) Mice were treated with a standardized PM from the US National Institute of Standards and Technology (NIST) 10 μg/animal, intratracheally, and 24 hours later the levels of IL-6 in the BAL fluid (ELISA) were measured (n=3 mice per condition, * p < 0.05 for indicated comparison). (E) Mice were treated with metformin in the drinking water for 24 hours and the levels of oxidized and reduced nicotinamide adenine dinucleotide (NAD⁺/NADH) were measured in BAL fluid macrophages by mass spectroscopy (n=5 animals per condition, * p<0.05). (F,G) Alveolar macrophages from BAL fluid were allowed to adhere overnight to glass coverslips, loaded with the mitochondrially localized oxidant sensitive dye MitoSOX (5 μM) and then exposed to PM containing perfusate (10 μg/ml) in the presence or absence of metformin (1 mM) on the stage of an epifluorescent microscope and oxidation of the dye was recorded from the same cellular region over time (n=3 mice per condition, * p<0.05). See also Figure S1.