PO:03:035 | Biomarkers of Gut Epithelial Damage, Microbial Translocation, and Innate Immune Activation Characterize Patients with Axial Psoriatic Arthritis from Psoriasis Patients: Soluble Biomarker Analysis Insights from the ATTRACT Study

Giulia Marchionni¹, Valentino Paci¹, Silvia Svegliati¹, Raffaella Sordillo¹, Federico Fiorini¹, Melania Giannoni¹, Anna Campanati¹, Raissa Di Zio¹, Devis Benfaremo¹, Giuseppe Lopalco², Florenzo Iannone², Ennio Lubrano³, Alberto Cauli⁴, Gianluca Moroncini¹, Dennis Poddubnyy⁵, Fabian Proft⁶, Michele M Luchetti Gentiloni¹ | ¹Marche Polytechnic University and Azienda Ospedaliero-Universitaria delle Marche, Ancona, Italy; ²University of Bari, Bari, Italy; ³Molise University, Campobasso, Italy; ⁴University of Cagliari, Azienda Ospedaliero Universitaria di Cagliari, Monserrato, Italy; ⁵University of Toronto, Toronto, Canada; ⁶Charité-Universitätsmedizin, Berlino, Germany

Background. Increasing evidence suggests that axial spondyloarthritis (axSpA) may be associated with intestinal damage, leading to the translocation of bacterial products into the bloodstream and activation of the innate immune system. In our recent cross-sectional study (ATTRACT), 29% of 365 screened patients with psoriasis (PsO) were diagnosed with axial Psoriatic Arthritis (axPsA) [1]. Given the described roles of intestinal permeability, microbial translocation, and anti-SOST/IgG in axSpA [2,3], we hypothesised that similar mechanisms may contribute to inflammation in axPsA.

Objectives. We aimed to assess plasma levels of I-FABP, LBP, sCD14, SOST, and anti-SOST/IgG as potential biomarkers of inflammation in PsO, peripheral PsA (perPsA), and axPsA patients naïve to biologic DMARDs. We also explored correlations between these biomarkers, clinical features, and disease activity.

Methods. we analysed plasma samples from 30 PsO, 20 perPsA, and 30 axPsA patients, and 25 healthy controls (HCs) from the ATTRACT study. I-FABP, LBP, sCD14, and SOST levels were assessed by commercial ELISAs; anti-SOST was evaluated by a validated peptide-binding ELISA [2,3].

Results. AxPsA patients showed significantly higher levels of I-FABP, LBP, and sCD14 compared to PsO and HCs. They also had higher I-FABP and LBP levels than perPsA patients. PerPsA patients showed elevated sCD14 compared to HCs only. Diagnostic performance: I-FABP (cut-off 306 pg/mL): 70% sensitivity, 76.7% specificity (AUC 0.76), LBP (cut-off 11.6 µg/mL): 70% sensitivity, 77% specificity (AUC 0.88), sCD14 (cut-off 1991 ng/mL): 70% sensitivity, 70% specificity (AUC 0.79). Contrary to previous data in axSpA, SOST and anti-SOST plasma levels were similar across groups, except for significantly higher SOST in axPsA versus PsO. We observed: Positive correlations of I-FABP and LBP with sCD14, SOST, and CRP, LBP with DAPSA, ASDAS, back pain and arthralgia duration, sCD14 with ASDAS, SOST with all biomarkers and clinical activity, Inverse correlation between SOST and anti-SOST.

Conclusions. This post hoc analysis from the ATTRACT study highlights increased biomarkers of gut epithelial damage, microbial translocation, and innate immune activation in axPsA patients compared to PsO and HCs. I-FABP and LBP showed good diagnostic accuracy, suggesting their utility in identifying axial involvement in PsA and offering a feasible, cost-effective alternative to complex genetic or imaging assessments.