Fig. 3
Biochemical response of triple cell co-culture system following exposures to volcanic ash and diesel exhaust particles. a Total reduced glutathione (GSH), b tumour necrosis factor-α (TNF-α) release, c interleukin-8 (IL-8) release and d interleukin-1β (IL-1β) release of the triple cell co-culture model after exposure to 0.26 ± 0.09 μg/cm2 of single exposure to volcanic ash (SEVA), 0.89 ± 0.29 μg/cm2 of repeated exposure to volcanic ash (REVA), diesel exhaust particles (DEP; 0.02 mg/mL), co-exposure to diesel exhaust particles and 0.26 ± 0.09 μg/cm2 of single exposure to volcanic ash (DEP + SEVA), and co-exposure to diesel exhaust particles and 0.89 ± 0.29 μg/cm2 of repeated exposure to volcanic ash (DEP + REVA). The respective positive assay controls are tert-Butyl Hydrogen Peroxide (tBHP; 250 μL of 100 mM) and lipopolysaccharide (LPS; 100 μL of 1 μg/mL), added to the apical and basal compartment of the triple cell co-culture, respectively. The negative control was cell culture medium only. Data are presented as the mean ± standard error of the mean. Data shown are related to the following repetitions for each exposure: SEVA n = 4; REVA, DEP, DEP + SEVA and DEP + REVA n = 3; negative and positive controls n = 8. * indicates p < 0.05