Increased PD-L1 Expression in Human Skin Acutely and Chronically Exposed to UV Irradiation

Sally E. Dickinson*, Maria Khawam, Viktoria Kirschnerova, Prajakta Vaishampayan, Sara M. Centuori, Kathylynn Saboda, Valerie S. Calvert, Emanuel F. Petricoin, Clara Curiel-Lewandrowski

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Overexpression of PD-L1 (CD274) on tumor cells may represent a hallmark of immune evasion, and overexpression has been documented in several tumors including cutaneous squamous cell carcinoma (cSCC). While PD-L1/PD-1 activity in the skin has been primarily described in inflammatory models, our goal was to examine PD-L1 expression in human keratinocytes exposed to UV irradiation. We assessed PD-L1 expression in human sun-protected (SP) and sun-damaged (SD) skin, actinic keratosis (AK), and cSCC using IHC and protein microarray. Both methods found low baseline levels of PD-L1 in SP and SD skin and significantly increased expression in cSCC. Next, we examined PD-L1 expression in acute models of UV exposure. In human SP skin exposed to 2-3 MED of UV (n = 20), epidermal PD-L1 was induced in 70% of subjects after 24 h (P = 0.0001). SKH-1 mice exposed to acute UV also showed significant epidermal PD-L1 induction at 16, 24 and 48 h. A time- and dose-dependent induction of PD-L1 was confirmed in cultured human keratinocytes after UV, which was markedly reduced in the presence of MEK/ERK, JNK or STAT3 inhibitors. These findings suggest that UV induces upregulation of PD-L1 through established, pharmacologically targetable stress-signaling pathways in keratinocytes.

Original languageEnglish
Pages (from-to)778-784
Number of pages7
JournalPhotochemistry and Photobiology
Issue number4
StatePublished - 1 Jul 2021
Externally publishedYes


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