High plasma tumor necrosis factor (TNF)-α levels are associated with an increased likelihood of developing psoriatic arthritis (PsA), whereas adiponectin levels are inversely linked with PsA compared with psoriasis (PsO). In addition, alcohol consumption significantly modifies the inverse association between adiponectin levels and the odds of developing PsA, according to cross-sectional study results published in the British Journal of Dermatology.

The investigators sought to use TNF-α and adiponectin levels to differentiate PsA from PsO and to explore whether circulating levels of these biomarkers are predictive of the risk for PsA in a population of patients with PsO. In their analysis, they included 180 patients with PsO only and 143 patients with an additional diagnosis of PsA from the Psoriatic Arthritis and Psoriasis Follow-Up Study, a multicenter registry at Brigham and Women’s Hospital in Boston, Massachusetts.

Both patients with PsO and PsA were similar in age (median, 51). There was a higher percentage of men in the PsA group  (56.2%) compared with patients in the PsO group (50.0%). Plasma levels of interleukin (IL)-6, C-reactive protein (CRP), TNF-α, total adiponectin, leptin, and high-molecular-weight (HMW) adiponectin were evaluated via enzyme-linked immunosorbent assay or immunoturbidmetric assay.

Participants with PsO and PsA demonstrated similar median plasma concentrations of IL-6, CRP, and human leptin. Median plasma levels of TNF-α were significantly higher in patients with PsA compared with patients with PsO (3.27 pg/mL vs 1.32 pg/mL, respectively; P <.001). Moreover, a slight decrease in median total adiponectin levels was reported in patients with PsA vs patients with PsO (4.66 µg/mL vs 5.36 µg/mL, respectively; P =.15) and with HMW adiponectin (2.58 µg/mL vs 3.01 µg/mL, respectively; P =.12).

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A high TNF-α level was associated with an increased likelihood of PsA (adjusted odds ratio [aOR] 2.25; 95% CI, 1.41-3.61). Moreover, a significantly inverse association was observed between a high total adiponectin level and the odds of developing PsA (aOR 0.61; 95% CI, 0.39-0.96). Likewise, an inverse association was reported for HMW adiponectin and PsA, although the association was only marginally significant after multivariate adjustment (aOR 0.64; 95% CI, 0.41-1.01). No significant associations were observed between plasma CRP levels, IL-6, or leptin levels and PsA. A significantly increased concentration of plasma TNF-α was noted in patients with PsA compared with patients with PsO.

A major limitation of the study is that it was based on a modest sample size in a cross-sectional setting, which is merely suggestive of the differentiation between PsA and PsO by serum biomarkers. Moreover, the study findings were not compared with those from healthy individuals without psoriatic disease.

The investigators concluded that additional large-scale studies in a prospective setting of patients with PsO are warranted in order to develop a clinically useful screening tool for risk prediction of PsA according to circulating biomarkers.

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Reference

Johnson CM, Fitch K, Merola JF, Han J, Qureshi A, Li WQ. Plasma TNF-α and adiponectin levels differentiate psoriatic arthritis from psoriasis patients [published online January 29, 2019]. Br J Dermatol. doi:10.1111/bjd.17700