Serum levels of adipokines and cytokines in psoriasis patients: a systematic review and meta-analysis

Abstract

Purpose: To evaluate the association of serum levels of adipokines and cytokines with psoriasis.

Materials and methods: A comprehensive literature search was performed in PubMed, ScienceDirect and Web of Science for the available relevant studies published before December 1, 2016. Differences in serum marker levels between patients and controls were pooled as standardized mean differences (SMDs) with 95% confidence interval to combine the effect estimations. We also conducted stratified analysis, meta-regression analysis and sensitivity analysis.

Results: Sixty-three studies containing 2876 psoriasis patients and 2237 healthy controls were included in this meta-analysis. The pooled serum levels of TNF-α, IFN-γ, IL-2, IL-6, IL-8, IL-18, IL-22, chemerin, lipocalin-2, resistin, sE-selectin, fibrinogen and C3 were higher in psoriasis patients compared with healthy controls (all P < 0.05). In contrast, adiponectin levels were lower. Serum levels of IL-1β, IL-4, IL-10, IL-12, IL-17, IL-21, IL-23, visfatin and omentin were not significantly different between psoriasis patients and controls (all P > 0.05). However, increased serum levels of IL-17 correlated with psoriasis in men. For other biomarkers, age, gender and psoriasis area and severity index did not explain the differences in effect size between the studies.

Conclusions: Serum levels of TNF-α, IFN-γ, IL-2, IL-6, IL-8, IL-18, IL-22, chemerin, lipocalin-2, resistin, sE-selectin, fibrinogen, complement 3, and adiponectin correlate with psoriasis and can be used as potential biomarkers for psoriasis and response to the treatment. Future studies are needed to identify additional players involved in the pathogenesis of psoriasis and to fully decipher the underlying mechanism.

Keywords: adipokine; cytokine; meta-analysis; psoriasis; serum.

Figure 1. Flowchart for the selection of eligible studies

Figure 2. A forest plot of pooled standardized mean differences (SMDs) in serum levels of adipokines and cytokines

The diamond represents the exact estimate from the study. The width of the line extending from each diamond represents the 95% confidence interval (CI). All individual study data and forest plots for all individual cytokines and adipokines are detailed in the Supplementary Files.

Figure 3. The meta-regression analysis for gender to assess differences in IL-17 serum levels between psoriasis patients and healthy controls

Figure 4. A schematic representation of role of the inflammatory factors in psoriasis