Changes in Salivary Biomarkers and Oral Immune Parameters in Patients with Psoriasis: A Systematic Review

Background: Psoriasis is a chronic immune-mediated inflammatory disease characterized by systemic inflammation and complex immune dysregulation that extends beyond the skin and may affect the oral environment. Increasing evidence suggests that saliva may serve as a non-invasive diagnostic medium reflecting both local and systemic pathological processes. This systematic review aimed to critically evaluate current evidence on salivary biomarkers in psoriasis, focusing on inflammatory mediators, oxidative stress parameters, immune-related factors, and oral microbiota alterations, and to assess their potential clinical and diagnostic relevance. Methods: A systematic literature search was performed according to PRISMA guidelines using PubMed, Scopus, and Web of Science databases, covering studies published between 1994 and October 2024. Original human studies evaluating salivary biomarkers in patients with psoriasis were included based on predefined PECOS criteria. Studies involving confounding inflammatory oral diseases without separate analysis were excluded. Eleven eligible studies were included in a qualitative synthesis. Results: The analyzed studies consistently demonstrated multidimensional alterations in salivary composition in psoriasis patients compared with healthy controls. Increased levels of pro-inflammatory cytokines (TNF-α, IFN-γ, IL-2) and reduced anti-inflammatory IL-10 indicated persistent immune activation. Elevated oxidative stress markers, including total oxidant status and oxidative stress index, supported the role of redox imbalance in disease pathogenesis. Alterations in innate immune components, such as salivary α-amylase, immunoglobulin A, and lysozyme, suggested impaired oral immune regulation. Moreover, emerging microbiome data revealed shifts toward pro-inflammatory bacterial taxa, including Prevotella and Porphyromonas. Some studies indicated that biologic therapy may modulate salivary biomarker profiles. Conclusions: Salivary biomarkers reflect systemic inflammatory and immunological alterations associated with psoriasis and represent promising non-invasive tools for disease monitoring and clinical assessment. Nevertheless, substantial methodological heterogeneity and limited sample sizes highlight the need for large-scale, standardized, and longitudinal studies to validate their diagnostic applicability.