Basic and Translational Science: A Report from the GRAPPA 2016 Annual Meeting

Broad proteomic screen reveals shared serum proteomic signature in patients with psoriatic arthritis and psoriasis without arthritis

OBJECTIVE

To identify novel serum proteins involved in the pathogenesis of PsA as compared with healthy controls, psoriasis (Pso) and AS, and to explore which proteins best correlated to major clinical features of the disease.

METHODS

A high-throughput serum biomarker platform (Olink) was used to assess the level of 951 unique proteins in serum of patients with PsA (n = 20), Pso (n = 18) and AS (n = 19), as well as healthy controls (HC, n = 20). Pso and PsA were matched for Psoriasis Area and Severity Index (PASI) and other clinical parameters.

RESULTS

We found 68 differentially expressed proteins (DEPs) in PsA as compared with HC. Of those DEPs, 48 proteins (71%) were also dysregulated in Pso and/or AS. Strikingly, there were no DEPs when comparing PsA with Pso directly. On the contrary, hierarchical cluster analysis and multidimensional scaling revealed that HC clustered distinctly from all patients, and that PsA and Pso grouped together. The number of swollen joints had the strongest positive correlation to ICAM-1 (r = 0.81, P < 0.001) and CCL18 (0.76, P < 0.001). PASI score was best correlated to PI3 (r = 0.54, P < 0.001) and IL-17 receptor A (r = -0.51, P < 0.01). There were more proteins correlated to PASI score when analysing Pso and PsA patients separately, as compared with analysing Pso and PsA patients pooled together.

CONCLUSION

PsA and Pso patients share a serum proteomic signature, which supports the concept of a single psoriatic spectrum of disease. Future studies should target skin and synovial tissues to uncover differences in local factors driving arthritis development in Pso.

Prologue: 2016 Annual Meeting of the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA)

The 2016 annual meeting of the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) was held in Miami, Florida, USA, and attended by rheumatologists, dermatologists, and representatives of biopharmaceutical companies and patient groups. As in previous years, GRAPPA members held a symposium for trainees to discuss their research in psoriatic disease with experts in the field. A strategic planning session was convened by the Steering Committee this year to review the work of GRAPPA since its inception in 2003. Other subjects featured during the annual meeting included a partnership with KPMG LLP (UK) to conduct interviews at research centers worldwide to analyze the process of care in psoriasis and psoriatic arthritis (PsA); a discussion of the effects of interleukin 17–related pathways on the skin and joints in psoriasis and PsA; summaries of recently published treatment recommendations and related guides; 4 separate discussions of psoriasis patient examinations; updates from working groups in the Outcome Measures in Rheumatology and the International Dermatology Outcome Measures; a discussion of patient centricity from GRAPPA’s patient research partners; and an update of research and educational projects from GRAPPA. In this prologue, we introduce the papers that summarize that meeting.