Modulation of Lipopolysaccharide‐Induced NF‐κB Signaling Pathway by 635 nm Irradiation via Heat Shock Protein 27 in Human Gingival Fibroblast Cells

Abstract Heat shock protein‐27 ( HSP 27) is a member of the small HSP family which has been linked to the nuclear factor‐kappa B ( NF ‐ κB ) signaling pathway regulating inflammatory responses. Clinical reports have suggested that low‐level light therapy/laser irradiation ( LLLT ) could be an effective alternative treatment to relieve inflammation during bacterial infection associated with periodontal disease. However, it remains unclear how light irradiation can modulate the NF ‐ κB signaling pathway. We examined whether or not 635 nm irradiation could lead to a modulation of the NF ‐ kB signaling pathway in HSP 27‐silenced cells and analyzed the functional cross‐talk between these factors in NF ‐ κB activation. The results showed that 635 nm irradiation led to a decrease in the HSP 27 phosphorylation, reactive oxygen species ( ROS ) generation, I‐κB kinase ( IKK )/inhibitor of κB ( IκB )/ NF ‐ κB phosphorylation, NF ‐ κB p65 translocation and a subsequent decrease in the COX ‐1/2 expression and prostaglandin ( PGE 2 ) release in lipopolysaccharide( LPS )‐induced human gingival fibroblast cells ( hGFs ). However, in HSP 27‐silenced hGFs , no obvious changes were observed in ROS generation, IKK / IκB / NF ‐ κB phosphorylation, NF ‐ κB p65 translocation, nor in COX ‐1/2 expression, or PGE 2 release. This could be a mechanism by which 635 nm irradiation modulates LPS ‐induced NF ‐ κB signaling pathway via HSP 27 in inflammation. Thus, HSP 27 may play a role in regulating the anti‐inflammatory response of LLLT .