FRI0444 Periostin in systemic sclerosis: serum levels and skin expression of a novel possible biomarker
Authors: G. De Luca, C. Campochiaro, S. Franchini, S. Burastero, S. Sartorelli, A. Giachi, G. Cavalli, C. Doglioni, L. Dagna
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Periostin(PN), a matricellular protein, serves as a regulator of wound healing and fibrosis. PN<sup>-/-</sup> mice develop lower degrees of fibrosis when exposed to bleomycin(BLM), suggesting a possible role in the pathogenesis of Systemic Sclerosis(SSc)<sup>1</sup>. PN serum levels are increased in SSc and seem to be associated with skin disease severity<sup>2</sup>. <h3>Objectives</h3> To evaluate the role of serum PN as a biomarker of SSc severity, and to determine PN tissue expression in SSc patients. <h3>Methods</h3> PN serum levels were assessed by ELISA in 48 patients: 3 primary Raynaud's, 12 early SSc, 11 SSc without organ involvement, 22 SSc with organ involvement. All SSc patients met 2013 ACR/EULAR criteria. PN serum levels were evaluated in 28 sex-/age-matched healthy-controls(HCs). Data regarding disease subtypes and organ involvement were correlated. PN skin expression was determined by immunohistochemistry on paired involved and uninvolved skin biopsy samples in 10 patients(4 lcSSc and 6 dcSSc) in combination with a-SMA, CD68, CD3, CD4, CD8, CD163, CD20 and CD131. <h3>Results</h3> PN serum levels were higher in SSc patients compared to HCs(32.7±8.0 vs 27.7±7.3 ng/ml, p&lt;0.001). Its levels were comparable among different groups. No differences in PN serum levels were detected when comparing disease subtypes, disease duration, presence and extent of organ involvement, autoantibodies profile and current or previous treatment. Higher PN levels were found in SSc patients with active pattern at nailfold videocapillaroscopy and a history of digital ulcers(p&lt;0.02). PN serum levels did not correlate with skin or lung disease extent. Skin samples from involved SSc skin showed high PN expression in the upper dermis and in the fibrotic area of the lower dermis(more evident in dcSSc), suggesting a role in skin fibrosis. In all SSc involved skin, PN was expressed in areas where ongoing fibroproliferation and macrophage/T lymphocytic infiltration occured, indirectly suggesting a pathogenic role in inflammation driven-fibrosis. Interestingly, an identical PN immunohistochemical expression was evident in uninvolved dcSSc skin, but not in lcSSc skin. <h3>Conclusions</h3> In our cohort PN serum levels are elevated in SSc patients but they do not correlate with disease features. Its postulated role as a severity biomarker needs to be further elucidated. The different immunohistochemical expression of PN in uninvolved skin from dcSSc and lcSSc patients suggests a possible pathogenic role in the progressive inflammation-driven fibrosis that characterise diffuse cutaneous involvement. <h3>References</h3> [1] Yang L, et al. Periostin facilitates skin sclerosis via PI3K/Akt dependent mechanism in a mouse model of scleroderma. PLoSOne2012. [2] Yamaguchi Y, et al. Serum Periostin levels are correlated with progressive skin sclerosis in patients with systemic sclerosis. Br J Dermatol2013. <h3>Disclosure of Interest</h3> None declared