Figure 9. Effect of ROS on P. acnes growth.

(A) HaCaT cells (dark line) and P. acnes suspension (Abs_{600 nm} = 0.5) (gray line) were incubated for 2 h under appropriate conditions with various concentrations of chemically generated O₂ ^•− ranging from 0,0191 µM to 10 mM. The viability of HaCaT cells was determined by the MTT assay as described in Materials and Methods. P. acnes suspension was then incubated for 5 days at 37°C under anaerobic conditions and the bacterial growth was evaluated by culturing bacteria on RCM solid media and by measuring the Abs at 600 nm. (B) HaCaT cells were preincubated with 40 µM DPI, 2 mM DDC, 50 µM MnTBAP, and stimulated with P. acnes (MOI of 50) in DMEM 10% SVF without antibiotics at 37°C, 5% CO₂. After 5 h of stimulation, liquid RCM was added to each well and the incubation for 5 days at 37°C under anaerobic conditions was started. P. acnes growth was then evaluated by measuring the Abs at 600 nm and by culturing bacteria on RCM solid media. Control experiment was run in parallel with the P. acnes in DMEM 10% SVF without antibiotics alone.