In vivo response of GsdmA3Dfl/+ mice to topically applied anti-psoriatic agents: effects on epidermal thickness, as determined by optical coherence tomography and H&E staining.

This study evaluated in vivo the potential of optical coherence tomography (OCT) to determine changes in thickness of the epidermis in response to the topically applied anti-psoriatics betamethasone dipropionate (BD), salicylic acid (SA) and also fish oil (FO). GsdmA3Dfl/+ mice have an inflammatory hair loss phenotype that includes hyperproliferation and epidermal thickening, hence a potential psoriasis model. Changes in epidermal thickness were evaluated over a period of 10 days, with the mice treated with combined BD + SA, FO + SA and BD + FO + SA. The data were validated with conventional measurement using H&E staining coupled with microscopy. Initial baseline measurement revealed an average epidermal thickness of 26.92 ± 1.17 μm. After 10 days of treatment with BD, the average epidermal thickness was reduced by 38.8% (P = 0.0001), and inversely, treatment with FO resulted in an unexpected 105% increase (P = 0.0001) in epidermal thickness. Combined BD + FO treatment did not cause any significant change (P = 0.3755) and may further indicate opposing effects on keratinocyte proliferation. The data obtained using OCT were statistically the same as those obtained by H&E/microscopy (P = 0.4325), supporting a greater role for OCT in dermatological studies, while also allowing a reduction in the number of animals used in such studies as sacrifice at individual timepoints is not necessary.