Anti-inflammatory and anti-mitotic properties of donepezil in primary keratinocytes and T cells support therapeutic potential for inflammatory skin diseases

The non-neuronal acetylcholine system in skin produces anti-inflammatory effects beneficial for conditions like atopic dermatitis, psoriasis, and acne vulgaris. To understand the effect of pharmacologically increased acetylcholine, we evaluated whether the acetylcholinesterase inhibitor donepezil could reduce markers of inflammation in primary epidermal keratinocytes and CD4+ T cells from healthy human donors. Acetylcholine and its analog carbachol had limited effect on TNF-α production and ATP levels, while donepezil was inhibitory in both cell types. In keratinocytes, donepezil induced transcriptome changes affecting cell cycle genes and cytokines, accompanied by morphological changes and G1 phase arrest. RNA-seq in T cells showed altered cytokine profiles and perturbation of diverse signaling pathways. Other acetylcholinesterase inhibitors (rivastigmine and galantamine) lacked the TNF-α and proliferation-suppressing effects of donepezil. Keratinocytes and T cells treated with donepezil showed reduced levels of ATP, which was not accompanied by cell death as measured by dye exclusion. We conclude that donepezil acts at least partly through alternative mechanisms by binding to off-target intracellular proteins rather than through acetylcholine augmentation alone in these cell types. The cytokine suppressing and antiproliferative properties of donepezil suggest utility as a topical treatment for inflammatory skin disorders.