Background: Regulatory T cells (Tregs) exhibit compromised immunosuppressive functions in psoriasis, yet understanding of their dysregulated perturbations remains limited. Methods: scRNA-seq data from the skin of patients with psoriasis and healthy controls were analyzed to identify emigrating cells and their populations and functional states. Pseudotime as well as cell-cell communication analyses were employed to explore the origins and interactions of psoriasis- related Tregs. hdWGCNA, LASSO, and XGBoost were applied to identify critical Treg-associated gene signatures (TRGS). Various machine learning algorithms were used to develop a diagnostic model for psoriasis. Results: Psoriatic lesions displayed a significant upregulation of C4-clustered genes, such as KRT14, DDIT4, and KRT1, in the granular and spinous layers of keratinocytes, which are associated with metabolic reprogramming under localized hypoxia. Psoriasis-associated Tregs exhibited increased glycolytic activity, impairing their functionality and highlighting the IL-17-HIF-1α axis. Pseudotime analysis revealed that Treg differentiation stalls at an intermediate stage, characterized by elevated expression of LTB, IL7R, and CCL5. Tregs were found to engage in IL16-CD4 autocrine signaling, potentially enhancing their proliferation and aggregation in psoriatic lesions. Five key Treg-related genes (TRGs)—CRIP1, FBXW11, CD47, ECH1, and H3F3A—were identified, and their expression was validated in a psoriasis-mimetic cellular model. The TRGS score exhibited a significant positive correlation with patients’ PASI score (r = 0.43, p < 0.001). Finally, a diagnostic model was constructed based on their differential expression patterns. Discussion: This study integrated single-cell transcriptomics and machine learning approaches to reveal the heterogeneity of Tregs and their key gene signatures in psoriasis, validated the expression of these genes through in vitro experiments, and ultimately constructed a high-accuracy diagnostic model based on TRGs. Conclusion: This study provides a comprehensive analysis of the cellular heterogeneity of the epidermal immune microenvironment in psoriasis through single-cell transcriptomics, offering valuable insights into metabolic reprogramming, developmental pathways, cell-cell interactions, and the functional properties of Tregs in psoriasis. Additionally, a high-accuracy diagnostic model for psoriasis was developed using machine learning techniques. These findings offer a single-cell molecular perspective on immune microenvironment regulation in psoriasis and contribute to the identification of diagnostic biomarkers as well as the refinement of clinical diagnostic strategies.
Huang et al. (Mon,) studied this question.