The effect of expressive writing on wound healing: Immunohistochemistry analysis of skin tissue two weeks after punch biopsy wounding.

OBJECTIVE:To investigate the effects of expressive writing and its timing (pre or post wounding) on re-epithelialisation and leucocyte subsets within healing tissue. We previously showed expressive writing pre-wounding improved re-epithelialisation. Here we investigate cellular processes in the wound. METHODS:In a 2(writing content) x 2(writing timing) randomized trial, 122 participants were randomized to perform either expressive or control writing, before or after a 4 mm punch biopsy wound. On day 14 post-wounding, participants had a 5 mm punch biopsy of the initial wound. Seven of 16 primary registered outcomes were analysed, including re-epithelialisation from two photographs of the 4 mm biopsy (previously reported). This paper reports immunohistochemistry analysis of five primary outcomes - Langerhans cells, immune cell activation (HLA and CD3+), and macrophages (CD68 and MPO) - in the 5 mm biopsies in a random sample of 96 participants. RESULTS:Participants who performed either writing task pre-wounding had greater Langerhans cell infiltration, than those who wrote post-wounding (F(1,85) = 7.86, p = .006, ηp2 = 0.08). Those who performed expressive writing also had greater Langerhans cell infiltration than those who performed control writing (F(1,85) = 4.00, p = .049, ηp2 = 0.04). There were no significant group or interaction effects on immune cell activation or macrophages. Healed wounds on day 10 had lower levels of macrophages (z = -1.96, p = .050), and CD3+ cells (z = -1.99, p = .046) than non-healed wounds. CONCLUSION:Langerhans cells in the healing skin are affected by the timing and topic of writing. More research is needed to further explore timing and corroborate these results. CLINICAL TRIALS REGISTRATION:Registered at https://www.anzctr.org.au/ (Trial ID: ACTRN12614000971639).