TIME OF DAY dependent immune changes were associated with disease severity and treatment response in psoriasis, according to a new study that identified distinct inflammatory patterns later in the day and partial restoration of immune rhythms following anti IL 23 therapy.
Psoriasis is a chronic inflammatory skin disease that places a substantial burden on patients, with symptoms often worsening later in the day. Although these daily fluctuations have been recognised clinically, the systemic immune mechanisms underlying them have remained unclear. Researchers therefore investigated whether time of day dependent immune variation was associated with disease activity and therapeutic response.
Peripheral blood samples were collected from patients with psoriasis in the morning and evening before and after anti IL 23 therapy. Researchers measured immune cell subsets, serum cytokines, and chemokines, while publicly available skin transcriptomic datasets were analysed using the ZeitZeiger algorithm to assess time of day dependent inflammatory signatures within psoriatic skin.
Patients with psoriasis demonstrated reduced time of day variation in circulating lymphocytes, largely driven by lower evening lymphocyte counts. At the same time, they exhibited an evening biased inflammatory profile characterised by increased cytokines and chemokines involved in inflammation and leukocyte migration.
The degree of daily immune variation was associated with disease severity. Time of day dependent variation in interleukin 31 positively correlated with Psoriasis Area and Severity Index (PASI) scores, whereas variation in T helper 17 cells and the CD4 positive to CD8 positive ratio showed negative correlations with disease severity.
Patients who did not respond to treatment also had higher pretreatment evening interleukin 31 levels together with a more pro inflammatory immune profile than treatment responders.
Anti IL 23 therapy reduced inflammatory mediator levels and partially restored disrupted time of day immune dynamics, particularly during the evening. Transcriptomic analyses also demonstrated increased late time of day inflammatory activity and immune cell infiltration within psoriatic skin before treatment, both of which were attenuated following therapy.
The authors concluded that psoriasis is characterised by disrupted time of day immune regulation that is associated with both disease severity and treatment response. They suggested that incorporating temporal immune context into biomarker assessment could improve interpretation of inflammatory markers and help inform future therapeutic strategies.
Reference
Zhan Q et al. Time-of-day–dependent immune dynamics are associated with disease severity and therapeutic response in psoriasis. Br J Dermatol. 2026;DOI:10.1093/bjd/ljag314.
Featured image: RFBSIP on Adobe Stock
Each article is made available under the terms of the Creative Commons Attribution-Non Commercial 4.0 License.
