552-558Ultraviolet
C (UVC) irradiation (λ: 200-280 nm) causes release of several secretory cytokines responsible for
inflammation. Our objective was to investigate whether inflammatory
response was also induced in bystander cells. For this purpose, the conditioned
medium containing the released factors from UVC irradiated A375 cells was used
in this study to evaluate the expression of inflammatory markers, such as
tumour necrosis factor alpha (TNFα),
nuclear factor
kappa-light-chain-enhancer of activated B cells (NFκB) and p38 mitogen-activated protein kinase (p38
MAPK) in its bystander cells. Inflammatory responses in bystander cells
subjected to further irradiation by UVC or other damaging agent like H2O2
were also examined. It was observed that
TNFα, NFκB and p38 MAPK
were not induced in UVC-bystander cells, but their expression was suppressed in
the UVC-bystander cells treated with UVC or H2O2. This
lowering in inflammatory response might be due to smaller depletion in the
reduced glutathione (GSH) content present in these treated bystander cells. The
study indicated that UVC-induced bystander effect was an intrinsic protective
response in cells, capable of suppressing inflammation induced in cells on
exposure to damaging agents.
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