Objective To investigate changes in sebum cytokines in response to hair cosmetics.
Design and setting A prospective study at a University hospital.
Methods We used a novel method for scalp surface sebum collection (Sebutape®) on three visits, sequentially a week apart, to investigate changes in six cytokines in 36 healthy women before and after shampoo and compared various chemical treatments (ammonium thioglycolate, “lye” sodium hydroxide and “no-lye” guanidine hydroxide relaxers) performed by a professional hairdresser.
Results Significant levels detected were IL-1 alpha (IL-1α) and IL-1 receptor antagonist (IL-1ra), which were higher in untreated scalp vs. forehead: P < 0.001. Baseline levels of scalp sebum IL-1α were 18 times higher than IL-1ra. The levels of IL-1α decreased uniformly after shampoo (visit 1) and various chemical treatments (both crown and vertex all P < 0.001 – visit 2) but increased on follow-up at visit 3. Decreases in IL-1ra mimicked IL-1α at the vertex [after shampoo (P = 0.018) and visit 3 (P = 0.014)], but not on the crown, a finding which may suggest site-specific scalp predisposition to inflammation. The ratio of IL-1ra/IL-1α increased in all groups after all chemical treatments and on follow-up (all P < 0.001) but was surprisingly not significantly different from natural hair that underwent shampoo.
Limitations A wider cytokine panel may reveal response differences in treatment groups.
Conclusions Baseline inflammatory scalp cytokines are higher than expected and reduce with shampooing. Scrutiny of the influence of hair moisturizer formulations and shampoo intervals and studies investigating pro-fibrotic cytokines are required. This may elucidate the predilection of afro-textured hair to scarring alopecia.