Inflammation is a complex process involving distinct but overlapping biochemical and molecular events that are highly regulated. Pulsed electromagnetic field (PEMF) therapy is increasingly used to treat pain and edema associated with inflammation following surgery involving soft tissue. However, the molecular and cellular effects of PEMF therapy on pathways involved in the resolution of inflammation are poorly understood. Using cell culture lines relevant to trauma-induced inflammation of the skin (human dermal fibroblasts, human epidermal keratinocytes, and human mononuclear cells), we investigated the effect of PEMF on gene expression involved in the acute and resolution phases of inflammation. We found that PEMF treatment was followed by changes in the relative amount of messenger (m)RNAs encoding enzymes involved in heme catabolism and removal of reactive oxygen species, including an increase in heme oxygenase 1 and superoxide dismutase 3 mRNAs, in all cell types examined 2 hours after PEMF treatment. A relative increase in mRNAs encoding enzymes involved in lipid mediator biosynthesis was also observed, including an increase in arachidonate 12- and 15-lipoxygenase mRNAs in dermal fibroblasts and epidermal keratinocytes, respectively. The relative amount of both of these lipoxygenase mRNAs was elevated in mononuclear cells following PEMF treatment relative to nontreated cells. PEMF treatment was also followed by changes in the mRNA levels of several cytokines. A decrease in the relative amount of interleukin 1 beta mRNA was observed in mononuclear cells, similar to that previously reported for epidermal keratinocytes and dermal fibroblasts. Based on our results, we propose a model in which PEMF therapy may promote chronic inflammation resolution by mediating gene expression changes important for inhibiting and resolving inflammation.
Keywords: acute inflammation; cytokines; eicosanoids; heme oxygenase; lipid mediators; reactive oxygen species; resolution phase; resolvins.