Analgesic effect of light-emitting diode phototherapy on incised wound is via inhibiting IL-6, COX-2 and PGE-2 but not IL1-β and TNF-α

Ping-Heng Tan, Chien-Cheng Liu

Department of Anesthesiology, E-DA Hospital, I-Shou University, Kaohsiung, Taiwan


Background and goal of study: Light-emitting diode (LED) phototherapy has been reported to relieve pain and enhance tissue repair through several mechanisms. The treatment of postsurgical pain remains a challenge for physicians. The analgesic effects of LEDs on incised skin wounds have never been examined. In this study, we examined the analgesic effects of LED therapy on skin incision pain and measured changes in cyclo-oxygenase 2 (COX-2), prostaglandin E2 (PGE2) and pro-inflammatory cytokines (interleukin (IL)-6, IL1-β, and tumor necrosis factor α (TNF-α).
Materals and Methods: The animal protocols were approved by the Institutional Review Board of I-Shou University, Kaohsiung, Taiwan. The rats were randomly assigned to different groups that received LED therapy on the skin 6 days before incision (LI group), 6 days after incision (IL group), or 3 days before incision and another 3 days after incision (LIL group). One group received only skin incisions (I group). Thermal hyperalgesia was tested 1 day after incision in the LI and I groups and after LED therapy in the other groups. After behavioral testing, the skin tissues were collected for COX-2, PGE2, IL-6, IL1-β and TNF-α protein analyses (n=6 each group). 
Results and Discussion: The thermal withdrawal latency was significantly decreased in the incision-only group (p=0.013) but not in the three LED treatment groups. Significantly decreased mechanical withdrawal thresholds were noted after skin incision in all LED treatment groups (p<0.05). The expression of IL-6, COX-2 and PGE2 were significantly decreased in the three LED-treated groups compared to the I group (p<0.05). IL1-β and TNF-α were significantly decreased in the LI group (P=0.025 and 0.011, respectively) but not in the other two LED-treated groups.
Conclusions: LED therapy relieved thermal hyperalgesia but not mechanical allodynia in incised wounds, and this analgesic effect was possibly produced by the inhibition of IL-6, COX-2 and PGE2 expression. Preemptive LED phototherapy was able to transiently suppress the expression of IL-1ß and TNF-α one day after incision. LED phototherapy was not able to suppress the expression of IL-1ß and TNF-α after the incision. LED therapy has therapeutic potential for the treatment of post-surgical pain.

Acknowledgements: This work was supported by National Science Council Grant MOST 103-2314-B-214-003-MY3, NSC 103-2321-B-214-001-, and E-Da Hospital Grant EDPJ 103054, 103055, and EDAHP 104028. Taiwan.

Analgesic effect of light-emitting diode phototherapy on incised wound is via inhibiting IL-6, COX-2 and PGE-2 but not IL1-&#946; and TNF-&#945;

Analgesic effect of light-emitting diode phototherapy on incised wound is via inhibiting IL-6, COX-2 and PGE-2 but not IL1-β and TNF-α