Transcriptomic profiling of plaque psoriasis and cutaneous T cell subsets during treatment with secukinumab

The IL-17A inhibitor secukinumab is efficacious for the treatment of psoriasis. To better understand its mechanism of action, we investigated its impact on psoriatic lesions from 15 moderate-to-severe plaque psoriasis patients undergoing secukinumab treatment. We characterized the longitudinal transcriptomic changes of whole lesional skin tissue as well as cutaneous CD4+ and CD8+ T effector cells and CD4+ T regulatory cells across 12 weeks of treatment. Secukinumab was clinically effective and reduced disease-associated overexpression of IL17A, IL17F, IL23A, IL23R, and IFNG in whole tissue as soon as 2 weeks after initiation of treatment. IL17A overexpression in T cell subsets, primarily CD8+ T cells, was also reduced. While secukinumab treatment resolved 89-97% of psoriasis-associated expression differences in bulk tissue and T cell subsets by week 12 of treatment, we observed expression differences involved in interferon signaling and metallothionein synthesis that remained unresolved at this time point as well as potential treatment-associated expression differences involved in IL-15 signaling. These changes were accompanied by shifts in broader immune cell composition based on deconvolution of RNA-seq data. In conclusion, our study reveals several phenotypic and cellular changes within the lesion that underlie clinical improvement from secukinumab. We biopsied lesional skin from psoriatic patients before secukinumab treatment and at 2, 4, and 12 weeks of treatment for comparison with skin biopsies from 13 healthy subjects. We performed RNA-seq on bulk skin tissue as well as on CD8+ T cells, CD4 T effectors, and CD4+ Tregs sorted from these biopsies