THU0021 Differential effects of tr14 versus diclofenac on cox/lox pathways revealed by rnaseq. (12th June 2018) - St. Laurent, G.
Abstract : Background: Anti-inflammatory agents are used widely in treating numerous pain and inflammatory conditions. With a focus on the COX/LOX pathways in cutaneous wound repair in mice, the therapeutic activities of Tr14 (Traumeel), a multicomponent/multitarget natural product, and diclofenac (NSAID), a non-selective cyclooxygenase (COX) inhibitor were compared. The COX enzymes convert arachidonic acid into prostaglandins and thromboxanes, while the lipoxygenase (LOX) pathway generates more pro-inflammatory leukotrienes. Differential effects were identified via transcriptome analysis (RNAseq). Objectives: To compare the transcriptomic changes after administration of Tr14 or diclofenac in a mouse cutaneous wound healing model, with particular emphasis on the COX/LOX pathway. Methods: After abrasive wounding, the wounds were treated with topical Tr14 (34 mg/ml) in combination with subcutaneous Tr14 injections (9.5 mg/ml), or with subcutaneous Tr14 injections only, or topical diclofenac at clinically relevant doses (2 mg/ml). Skin samples were analysed for RNA transcript profiling by RNAseq at specific times (12 hour, 24 hour, 36 hour, 72 hour, 96 hour, 120 hour, 192 hour) after injury. Differentially expressed genes (DEGs) were computed at each time point between diclofenac vs control or Tr14 vs control, using EdgeR. Results: At early time points (12–36 hour), both control and Tr14-treated wounds showed marked increase in the inducible COX2 enzyme mRNA, while diclofenac-treated wounds did not, likely due to blocking the PGE2 necessary for the feedback induction. Tr14, in contrast, had a striking inhibitory effect on mRNA levels for leukotriene A4 hydrolase, which converts LTA4 to LTB4; microsomal glutathione S-transferase, which converts LTA4 to LTC4; and gamma-glutamyltransferase (LTC4 >LTD4). In contrast, Tr14, but not diclofenac strongly induced Nrf2 mRNA at 12–36 hours. Conclusions: Tr14 and diclofenac had very different effects on the COX/LOX synthetic pathway after cutaneous wounding. Tr14 allowed normal autoinduction of COX2 mRNA by PGE2, but suppressed mRNA levels for the key enzymes in the leukotriene synthetic pathway. A likely explanation for these effects is that Tr14 strongly induced Nrf2 mRNA, which is known to co-repress the leukotriene enzymes via transcription factor Bach1. Disclosure of Interest: None declared