The use of high-dimensional flow-cytometry profiling can differentiate patients with psoriasis and patients with psoriatic arthritis (PsA), which may support a timelier diagnosis of PsA in patients with skin disease, according to findings from a cross-sectional and case-control study presented at the 2019 American College of Rheumatology (ACR)/Association of Rheumatology Professionals (ARP) Annual Meeting.

To reach this conclusion, Michelle Mulder, a PhD candidate in the Department of Rheumatology at Sint Maartenskliniek in Nijmegen, the Netherlands, and colleagues analyzed blood samples from 25 patients with psoriasis without arthritis and 33 patients with PsA.

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Among all patients, those with PsA were slightly older compared with patients with psoriasis. More patients with PsA had previously received methotrexate (MTX) than patients with psoriasis (51% vs 12%), although none of the patients were receiving biological therapy at baseline. Gender was comparable between the groups.

Peripheral blood samples were analyzed by high-dimensional flow cytometry, which enabled the characterization of ~150 immune-cell populations. The researchers performed semi-unsupervised and unsupervised computational flow cytometry analyses.

Semi-unsupervised analysis of high-dimensional flow cytometry data of peripheral blood from the groups clearly showed a clear distinction between patients with psoriasis vs patients with PsA, as indicated by principal component analysis. This distinction between patients with psoriasis and patients with PsA was independent of age, gender, Psoriasis Area and Severity Index scores, and MTX use. Unsupervised clustering also showed a clear distinction between both diseases.

Findings from the unsupervised computational analysis showed marked differences in the immune-cell subset profiles between patients with psoriasis and patients with PsA.

High-dimensional flow cytometry evaluation with semi-unsupervised and unsupervised analysis can differentiate psoriasis and PsA patients, the researchers concluded. “Following validation, the obtained immune profiles might be used to support the timely diagnosis of PsA in [psoriasis] patients, as well as target finding to prevent this disease-shift,” they wrote.

—Melinda Stevens

Reference:

Mulder M, van den Reek J, de Jong E, et al. High dimensional flowcytometric profiling distinguishes psoriasis and psoriatic arthritis [abstract 1912]. Arthritis Rheumatol. 2019;71(suppl 10). Presented at: 2019 ACR/ARP Annual Meeting; November 8-13, 2019; Atlanta, GA. https://acrabstracts.org/abstract/high-dimensional-flowcytometric-profiling-distinguishes-psoriasis-and-psoriatic-arthritis/. Accessed November 6, 2019.