Association Between Inflammatory Cytokines and Systemic Inflammation Indices in Patients With Psoriasis: A...

Systemic inflammation indices derived from complete blood counts (CBC) are accessible markers of inflammatory burden, but their relationship with circulating cytokines in psoriasis remains unclear. We investigated associations between CBC-derived indices and serum cytokines in psoriasis.

In this cross-sectional study, we included 28 patients with psoriasis and 23 healthy controls. Serum IL-17, IL-22, IL-23, IL-31, IL-33, IL-36, TNF-α, TGF-β, and IFNγ were quantified by ELISA. CBC-derived indices were computed (neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), systemic inflammation response index (SIRI), and pan-immune-inflammation value (PIV). Case-control comparisons used the full sample. Cytokine-index associations were evaluated in psoriasis patients using bivariate correlations and multivariate GLM adjusted for age, smoking, and NAFLD. Multiplicity was controlled using Benjamini-Hochberg false discovery rate (BH-FDR); prespecified sensitivity analyses used log-transformed cytokines and Spearman correlations.

Psoriasis patients had higher levels of all cytokines (all p < 0.001) and higher SIRI versus controls (p < 0.001; q = 0.005). PIV showed a nominal case-control difference (p = 0.022) that did not remain significant after BH-FDR (q = 0.055), while NLR, PLR, and SII did not differ. In adjusted multivariate GLM, TGF-β showed a global association with the joint set of indices (Pillai's trace = 0.295; p = 0.039) that did not survive BH-FDR (q = 0.507) and was attenuated with log-transformation. Nominal univariate effects for TNF-α on SIRI (F = 4.600; p = 0.039) and PIV (F = 5.660; p = 0.023) did not remain significant after BH-FDR.

SIRI was consistently elevated in psoriasis, whereas PIV showed a nominal difference versus controls. Across exploratory analyses, SIRI and PIV showed the most consistent directional co-variation with cytokines, but associations were modest. These findings are hypothesis-generating and support further validation in larger cohorts to determine whether CBC-derived indices can serve as scalable adjunct markers of inflammatory activity in psoriasis.