The effects of acute social stress on epidermal Langerhans' cell frequency and expression of cutaneous neuropeptides

Psychological stress is believed to exacerbate inflammatory skin disease but the underlying mechanisms are poorly understood. We investigated the impact of acute social stress - Trier public speaking test - on: epidermal Langerhans' cell (LC) frequency; and cutaneous nerve fiber expression of protein gene product (PGP) 9.5 and calcitonin gene-related peptide (CGRP). Thirty-six healthy volunteers each had a pair of baseline 6 mm biopsies taken from sun-protected buttock skin. A second pair of biopsies was taken from contralateral buttock 4 hours (n=5) or 24 hours (n=15) after the Trier stressor. Controls (n=16) did not perform the Trier and had biopsies 24 hours apart. One of each pair of biopsies (baseline; 4 or 24 hours) was processed for counts of epidermal CD1a ⁺ LC; the other examined for PGP 9.5 and CGRP expression. We observed a significant (P<0.01) 16.4% reduction in epidermal LC frequency 24 hours post-stressor as compared with baseline; there was no significant change from baseline in non-stressed controls. At 24 hours, PGP 9.5 and CGRP were increased (P=0.025) and reduced (P=0.03), respectively, from baseline in the stressed group compared with controls. These data suggest that acute social stress reduces epidermal LC frequency and modulates cutaneous neuropeptide expression thereby supporting the concept of a "brain-skin" axis.